Ink jet head, ink jet method and ink jet device

Liquid discharge head, liquid discharge method and liquid discharge device

The invention relates to a liquid discharge head, which discharges required liquid by means of bubbles generated by applying heat energy to the liquid. The invention also relates to a liquid discharge head box and a liquid discharge device using the liquid discharge head. Specifically, the present invention relates to a liquid discharge head with a plurality of movable members, the movable member can be displaced by the growth of bubbles, and the present invention also relates to a liquid discharge head box and a liquid discharge head using the liquid discharge head. Drainage device.

The present invention is suitable for printers that can record on various recording media such as paper, fiber, textile, cloth, leather, metal, plastic, glass, wood, and ceramics. The present invention is also applicable to copiers, facsimile equipment with communication systems, and equipment with printers such as word processors. The invention is also suitable for recording systems with complex structures in combination with various processing devices in actual use.

In the specification of the present invention, the term "recording" not only means generating text, graphics, and other meaningful images on a recording medium, but also means generating patterns or other images without specific meanings.

The existing inkjet recording method, the so-called bubble jet recording method, is to apply energy, such as thermal energy, to the ink to cause the ink to produce a change in the ink state (bubble generation) accompanied by a sudden change in the volume of the ink. The force of, the ink is discharged from the discharge port, so that the discharged ink adheres to the recording medium to form an image. As described in the specification of U.S. Patent No. 4,723,129 and other documents, the recording apparatus adopting the bubble jet recording method generally has a discharge port for discharging ink; an ink flow channel communicating with the discharge port; The electrothermal conversion device in the channel, the electrothermal conversion device is used to generate the energy required to discharge the ink.

This type of recording method can record high-quality images with low noise and high speed. At the same time, the use of the liquid discharge head to achieve the recording method can provide a higher density of discharge ports for discharging ink, obtain a higher-resolution recording image with a smaller volume device, and facilitate obtaining a color image. In recent years, the bubble jet recording method has been widely used in a variety of office equipment, such as printers, copiers, and fax equipment, as well as in textile printing systems and other industrial fields.

Nowadays, as bubble spray technology and processes are widely used in products currently used in many fields, various requirements as described below have been put forward in recent years.

In order to obtain higher quality images, it is recommended to update the driving conditions so that the liquid discharge method can achieve good ink discharge based on the stable growth of bubbles, where the stable growth of bubbles can ensure high-speed discharge of ink. From the viewpoint of high-quality recording, it is recommended to improve the structure of the ink flow channel so that the resulting liquid discharge head can refill the discharged liquid in the liquid flow channel with high quality.

In addition to this type of liquid discharge head, the specification of Japanese Patent Application Publication No. 6-31918 (refer to page 3 of the application in particular) discloses an invention that focuses on the problem of backflow (pressure direction and discharge) associated with the generation of bubbles. The opposite direction of the port), because the reverse flow causes energy loss in the process of liquid discharge, so the structure should be improved to avoid the above reverse flow. The invention disclosed in this specification directs the triangular portion of a triangular plate member toward each heater that generates bubbles. With the help of the plate set as described above, the invention can temporarily and slightly suppress the reverse flow. However, the invention does not mention the interrelationship between the growth of the bubbles and the triangular parts, nor does it disclose how to set this interrelationship. Therefore, this invention still has the following problems.

In other words, in the invention disclosed above, the heater is located at the bottom of the recessed portion, so that it is difficult to linearly communicate the heater with the liquid discharge port. Therefore, the uniform shape of each droplet cannot be ensured stably. At the same time, since the growth of each bubble initially appears at the periphery of each tip of the triangular part, the bubble grows from one side of the triangular plate to the completely opposite side. Therefore, the growth of each bubble is completed in the liquid, just like when there is no triangular plate part. Therefore, for bubble growth, it is meaningless to set a triangular plate. On the contrary, each bubble envelops the entirety of each triangular plate component. During the bubble contraction stage, this situation will interfere with the flow of the refilling liquid to the outside of each heater located in the above-mentioned recessed portion. Therefore, fine bubbles gather in the recessed portion, which does not conform to its own working principle, which is based on the growth of bubbles to achieve liquid discharge.

Meanwhile, the publication of the patent application EP436047A1 discloses an invention that proposes to make a first shutoff valve located between the liquid discharge port and the vicinity of the bubble generation part alternately open and close, and make the bubble generation part and the ink supply part alternately open and close. A second valve between the sections alternately opens and closes so that they are completely closed (as shown in Figures 4-9 of EP436047A1). However, this invention inevitably divides each of the three chambers into two. Therefore, the ink that accompanies the droplets during discharge forms a prominent tail. Compared with the usual discharge method in which each bubble grows, shrinks, and disappears, a large number of "satellite dots" are generated (presumably, the bubble cannot be effectively used. The half-moon indentation produced during the disappearance). When refilling, when each bubble disappears, liquid should be supplied to the bubble generating part. However, since it is impossible to supply liquid into the vicinity of each discharge port before the next bubble is generated, not only the volume of each discharged droplet changes significantly, but the frequency of discharge response becomes extremely small. Therefore, the described invention is very impractical.

On the other hand, the applicant of the present invention has proposed some inventions that help to effectively discharge liquid droplets. These inventions use the same movable member (plate or similar as the prior art), the free end of which is located near the row of its fulcrum. Liquid port side). Among the described inventions, the solution disclosed in the specification of Japanese Patent Application Publication No. 9-48127 is that in order to avoid even slight interference from the movement of the movable member as described above, the invention adjusts the displacement of the movable member. Upper limit. Similarly, an invention is disclosed in the specification of Japanese Patent Application Laid-Open Publication No. 9-323420, which utilizes the convenience brought by the movable member, in which the position of the common liquid chamber upstream of the movable member is set to be movable To the downstream side, that is, the side of the free end of the movable member, to enhance the refilling ability. However, these inventions did not pay attention to each individual foaming element as a whole, and the foaming element is used to form liquid droplets, nor did they pay attention to the mutual relationship between them, because the design of the present invention determined The premise adopts such a mode so that when the bubble growth is temporarily wrapped by the movable member, the bubble is immediately discharged to the side of the discharge port.

In the next stage thereafter, the applicant disclosed an invention in Japanese Patent Application Publication No. 10-24588, in which a part of the bubble generation area is separated from the movable member as a new invention (sonic wave), The research is to increase the pressure wave to make the bubble grow and constitute the relevant components of the liquid discharge. However, this invention also only pays attention to the growth of each bubble during liquid discharge. Therefore, when designing the invention, each individual element involved in the formation of the droplet itself, which is used to form the bubble, was considered, and the relationship between each of them was not considered.

Although it has been known that the bubble front (shorter edge type) produced by the film boiling method has a great influence on the discharge, there is no invention to improve this specific part so that it can effectively contribute to the formation of each inkjet drop. Increase contribution. The inventor actively studied the above-mentioned parts in order to explain the invention technically when it was declared as a patent.

From the perspective of the formation of inkjet droplets, the various processes from the formation of each bubble to the disappearance of the bubble are accurately analyzed. Thus, a number of inventions have been derived from the above-mentioned precise analysis. The present invention is one of them. It is used to reduce the satellite dots that are unique to inkjet printing, which can reduce the quality of printing, and also pollute the equipment itself and the recording medium. Compared with the traditional technology, the present invention can achieve an extremely high technical level in terms of stabilizing image quality when implementing continuous liquid discharge operations.

The main objects of the present invention are as follows: The first object of the present invention is to propose an extremely novel discharge principle, according to this principle, the generated bubbles and the liquid on the discharge port side, as well as the liquid on the liquid supply side are affected The structure of the movable part and the entire liquid flow channel is suppressed.

The second object of the present invention is to provide a liquid discharging method and a liquid discharging head, which can reduce satellite spots by controlling the formation process of each sprayed droplet, and basically eliminate satellite spots in the spraying operation.

The third object of the present invention is to reduce the system load of the required structure of the recording device so that the backflow caused by the existence of satellite points and the fluctuation of the meniscus liquid level can be eliminated.

In order to achieve the above-mentioned object, the liquid discharge head of the present invention includes: a heating element for generating heat energy to generate bubbles in the liquid; a liquid discharge port constituting a part for discharging the liquid; a liquid flow channel with the The liquid discharge port is connected, and the liquid flow channel is provided with a bubble generation area. It is used to make liquid generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; a restricting member restricts the movement of the movable member within a certain range, using The energy generated when the bubbles are generated discharges the liquid from the liquid discharge port. When the liquid discharge head generates bubbles, the liquid flow channel encloses the bubbles, and there is a gap in the liquid flow channel on the side of the movable member, so that when the bubbles disappear, the liquid on the upstream side of the movable member can flow into the bubble generation area.

Alternatively, the liquid discharge head of the present invention includes: a heating member for generating heat energy to generate bubbles in the liquid; a liquid discharge port constituting a part for discharging the liquid; a liquid flow channel and the liquid discharge port Connected, the liquid flow channel has a bubble generation area for making the liquid generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; The movement of the movable member is restricted within a certain range, and the liquid is discharged from the liquid discharge port by using the energy when the bubbles are generated. With this liquid discharge head, the restriction member faces the bubble generation area of the liquid flow path. When the vicinity of the free end of the movable movable member is substantially in contact with each of the restricting members, the liquid discharge port is removed, and the liquid flow channel with the bubble generation area forms a substantially closed In the space, before the bubble reaches the maximum volume, the movable member is moved to make it elastically extend to the upstream side, and then in the bubble disappearing stage, the elasticity of the movable member is used to move the protruding part to the downstream side.

Alternatively, the liquid discharge head of the present invention includes: a heating member for generating heat energy to generate bubbles in the liquid; a liquid discharge port constituting a part for discharging the liquid; a liquid flow channel and the liquid discharge port Connected, the liquid flow channel has a bubble generation area for making the liquid generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; The movement of the movable member is restricted within a certain range, and the liquid is discharged from the liquid discharge port by using the energy when the bubbles are generated. For this type of liquid discharge head, when the moved movable member is substantially in contact with the restricting member, the liquid discharge port is removed, and the liquid flow path with the bubble generation area forms a substantially closed When the bubble reaches the maximum volume, the bubble will not block the liquid flow channel in the space.

Alternatively, the liquid discharge head of the present invention includes: a heating member for generating heat energy to generate bubbles in the liquid; a liquid discharge port constituting a part for discharging the liquid; a liquid flow channel and the liquid discharge port Connected, the liquid flow channel has a bubble generation area for making the liquid generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; The movement of the movable member is restricted within a certain range, and the liquid is discharged from the liquid discharge port by using the energy when the bubbles are generated. For this type of liquid discharge head, when the moved movable member is substantially in contact with the restricting member, the liquid discharge port is removed, and the liquid flow path with the bubble generation area forms a substantially closed When the bubble grows to the maximum, there is liquid toward the movable member and is continuously connected with the liquid located on the downstream side of the bubble generation area in the space.

Alternatively, the liquid discharge head of the present invention includes: a heating member for generating heat energy to generate bubbles in the liquid; a liquid discharge port constituting a part for discharging the liquid; a liquid flow channel and the liquid discharge port Connected, the liquid flow channel has a bubble generation area for making the liquid generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; The movement of the movable member is restricted within a certain range, and the liquid is discharged from the liquid discharge port by using the energy when the bubbles are generated. For this type of liquid discharge head, when the moved movable member is substantially in contact with the restricting member, the liquid discharge port is removed, and the liquid flow path with the bubble generation area forms a substantially closed When the bubble reaches the maximum volume, the bubble will not cover the substantially contacted part of the movable member.

Alternatively, the liquid discharge head of the present invention includes: a heating member for heating the liquid in the liquid flow channel to generate bubbles in the liquid; a liquid discharge port communicated with the downstream side of the liquid flow channel, using The pressure generated by the growth of the bubble discharges the liquid; a liquid flow channel communicates with the liquid discharge port, and the liquid flow channel has a bubble generation area for generating bubbles in the liquid; a movable member is arranged at In the bubble generation area, it moves as the bubble grows; a restriction member restricts the movement of the movable member within a certain range, and the heating member and the liquid discharge port are in a linear communication state, respectively , Using the energy generated when the bubbles are generated to discharge the liquid from the liquid discharge port. For this type of liquid discharge head, the restriction member faces the bubble generation area, and when the movable member after the movement is substantially in contact with the restriction member, the liquid discharge port is removed, and the bubble generation area is removed. The liquid flow channel in the area forms a substantially closed space. When the bubble disappears, the movable member covers a part of the heating member, so that the liquid located in the area covered by the movable member can escape from the The movable part flows out on one side.

Alternatively, the liquid discharge head of the present invention includes: a heating member for heating the liquid in the liquid flow channel to generate bubbles in the liquid; a liquid discharge port communicated with the downstream side of the liquid flow channel, using The pressure generated by the growth of the bubble discharges the liquid; a liquid flow channel communicates with the liquid discharge port, and the liquid flow channel has a bubble generation area for generating bubbles in the liquid; a movable member is arranged at The bubble generation area moves with the growth of the bubble; a restricting member restricts the movement of the movable member within a certain range, the heating member and the liquid discharge port are in a linear communication state, The liquid is discharged from the liquid discharge port by the energy generated when the bubbles are generated. For this type of liquid discharge head, the restriction member faces the bubble generation area, and when the movable member after the movement is substantially in contact with the restriction member, the liquid discharge port is removed, and the bubble generation area is removed. The liquid flow channel in the area forms a substantially closed space, and when the bubble disappears, the movable member covers the disappearing point of the bubble.

Alternatively, the liquid discharge head of the present invention includes: a liquid discharge port for discharging liquid; a liquid flow channel communicated with the liquid discharge port, and the liquid flow channel has a plurality of bubble generation regions to form the liquid Bubbles; a movable member disposed in the liquid flow channel, facing the bubble generation area, the movable member with a free end, the free end is on the downstream side with respect to the liquid flow in the direction of the liquid discharge port, Among the plurality of bubble generation regions, the movable member is provided only in the bubble generation region on the upstream side toward the liquid flow direction of the liquid discharge port.

In order to achieve the aforementioned object of the invention, the liquid discharge device of the present invention includes a liquid discharge head as described in any of the preceding paragraphs, and a member carrying a recording medium for carrying the recording medium that receives the liquid discharged from the liquid discharge head.

Further, in order to achieve the above-mentioned object of the invention, the liquid discharge method of the present invention adopts a liquid discharge head with: a heating element for generating heat energy to generate bubbles in the liquid; and a liquid discharge port, which constitutes The part where the liquid is discharged; a liquid flow channel communicating with the liquid discharge port, the liquid flow channel having a bubble generation area for making the liquid generate bubbles; a movable member arranged in the bubble generation area , Move with the growth of the bubble; a restricting member that restricts the movement of the movable member within a certain range, and uses the energy when the bubble is generated to discharge the liquid from the liquid discharge port, the liquid discharge method The method includes the following steps: when the bubble grows, the movable member wraps the bubble; when the bubble disappears, the liquid located on the upstream side of the movable member can flow into the bubble generating area through the gap provided on the side of the movable member.

Alternatively, the liquid discharge method of the present invention may use a liquid discharge head with: a heating element for generating heat energy to generate bubbles in the liquid; and a liquid discharge port constituting a part for discharging the liquid A liquid flow channel connected with the liquid discharge port, the liquid flow channel with a bubble generation area for the liquid to generate bubbles; a movable member is provided in the bubble generation area, along with the bubble A restriction component that restricts the movement of the movable member within a certain range, and uses the energy generated when bubbles are generated to discharge the liquid from the liquid discharge port. The liquid discharge method includes the following steps: Before the bubble reaches the maximum volume, the movable member is basically in contact with the restricting member, and the movable member is moved to make it elastically extend to the upstream side, so that the liquid with the bubble generating area can circulate The channel forms a substantially closed space except for the liquid discharge port; during the contraction stage of the bubble, its own elasticity is used to move the protruding part of the movable member to the downstream side.

Alternatively, the liquid discharge method of the present invention may use a liquid discharge head with: a heating element for generating heat energy to generate bubbles in the liquid; and a liquid discharge port constituting a part for discharging the liquid A liquid flow channel connected with the liquid discharge port, the liquid flow channel with a bubble generation area for the liquid to generate bubbles; a movable member is provided in the bubble generation area, along with the bubble A restriction component that restricts the movement of the movable member within a certain range, and uses the energy generated when bubbles are generated to discharge the liquid from the liquid discharge port. The liquid discharge method includes the following steps: Before the air bubble reaches the maximum volume, the movable member is basically in contact with the restricting member. When the air bubble reaches the maximum volume, there is no air bubble blocking the flow of the liquid in the space.

Alternatively, the liquid discharge method of the present invention may use a liquid discharge head with: a heating member for heating the liquid in the liquid flow channel to generate bubbles in the liquid; a liquid discharge port, and The downstream side of the liquid flow channel is connected, and the liquid is discharged by the pressure generated by the growth of the bubble; a liquid flow channel is connected to the liquid discharge port, and the liquid flow channel has a bubble generation area for Causes the liquid to generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; a restricting member restricts the movement of the movable member within a certain range, and the heating The component and the liquid discharge port are in a state of linear communication, and the liquid is discharged from the liquid discharge port by using the energy when the bubble is generated. The method further includes the following step: before the bubble reaches the maximum volume, the movable member Basically contact with the restricting member, remove the liquid discharge port, the liquid flow channel with the bubble generation area forms a substantially closed space; before the bubble disappears, the movable member is covered A part of the heating component; allowing the liquid located in the area covered by the movable member to flow out from the side of the movable member.

Alternatively, the liquid discharge method of the present invention may use a liquid discharge head with: a heating member for heating the liquid in the liquid flow channel to generate bubbles in the liquid; a liquid discharge port, and The downstream side of the liquid flow channel is communicated, and the liquid is discharged by the pressure generated by the growth of the bubble; a liquid flow channel is connected to the liquid discharge port, and the liquid flow channel has a bubble generation area for Causes the liquid to generate bubbles; a movable member is arranged in the bubble generation area and moves with the growth of the bubble; a restricting member restricts the movement of the movable member within a certain range, and the heating The component and the liquid discharge port are in a state of linear communication, and the liquid is discharged from the liquid discharge port by using the energy when the bubble is generated. The method further includes the following step: before the bubble reaches the maximum volume, the movable member The liquid flow channel with the bubble generation area is substantially in contact with the restriction member, and the liquid flow channel with the bubble generation area forms a substantially closed space; when the bubble disappears, the movable member covers the disappearing point of the bubble.

Since air bubbles can overflow around the back of the movable member, the valve mechanism of the movable member of the present invention can suppress the deflection of each movable member, thereby stabilizing the discharge performance. Furthermore, when the bubbles disappear, a "well" type environment is formed in each bubble generation area, even in a structure without a liquid circulation system, the accumulation of residual bubbles and the accumulation of heat around each heating component are eliminated. It is also possible to avoid or eliminate the movement of the liquid in the upstream direction accompanied by the reverse flow, that is, the pressure wave directed to the upstream side. Reduce the resistance of the liquid from each liquid flow channel to increase the refill performance. The inertia caused by the reverse wave and acting in the direction opposite to the liquid supply direction is suppressed, and the meniscus-shaped liquid surface is quickly sucked into each discharge port. However, before the retraction amount of the meniscus liquid surface becomes larger, the rapid suction of the meniscus liquid surface described above is controlled. In this way, the generation of satellite points is avoided to increase the refill frequency and printing speed. Moreover, the vibration of the half-moon-shaped liquid surface is suppressed, so as to stabilize the ejection process and improve the printing quality. When the valve mechanism can function by generating air bubbles, the resistance of each movable member from the liquid flow channel is reduced to a specific moving position of the movable member, so that the movable member can quickly reach an appropriate position. move Place. This improves the drainage efficiency.

In the present invention, before the main refilling starts, the inertia in the static state is reduced as described above, and the movement starts in the refilling direction. As a result, refilling can be performed stably and quickly, which contributes to sufficient droplet formation. The half-moon-shaped liquid surface is quickly sucked into each discharge port, suppressing the back wave of the liquid, that is, the pressure wave pointing in the upstream direction, moving to the upstream direction to avoid satellite spots, thereby stabilizing the discharge volume and improving the quality of printing.

The present invention can restrain the liquid from moving in the upstream direction with the reverse wave, that is, the pressure wave pointing in the upstream direction, and at the same time, by making the bubbles escape from the closed space, thereby ensuring the liquid flow, that is, the fluid is in a good state. The closed space, especially after the formation of a substantially closed space based on bubble growth, when the volume of the bubble decreases and starts to be refilled, from the blocked state, each movable member touches the part. Thereby, each movable part can be quickly restored, and the liquid discharge amount can be stabilized, so as to improve the printing quality.

The invention uses air pockets to ensure that there is a narrow space (nearly 10 microns) between the fulcrum side of each movable member and the bubble generation area of the liquid flow, so that the whole can be restored.

The invention can stably form liquid droplets without generating satellite points. This improves the overall quality of printed products.

Especially with the structure of the present invention, the tail part of the liquid column that is connected to the discharged liquid droplet is quickly cut off from the meniscus liquid surface, and the vibration of the meniscus liquid surface is stabilized at a high speed. High-quality high-speed recording, good response during continuous ejection, and stable droplet formation.

Furthermore, in the liquid discharge head of the present invention, when the movable member is moved so as to be brought into contact with the restricting member, each liquid flow path is substantially divided with respect to the liquid flow in the direction of the liquid discharge port. Therefore, the liquid can be discharged stably and at a high speed as the bubbles grow in each bubble generation area. Furthermore, the number of satellites and the vibration of the meniscus can be reduced. The free end of each movable member of the bubble generation area facing the upstream side is located on the downstream side, the movable member responds well, and the movable member and the liquid flow channel can respectively correspond one-to-one. Therefore, the space required to support the movable member is minimized, and the volume of the liquid discharge head is correspondingly reduced.

The liquid discharge method of the present invention can eject larger liquid droplets. Using the liquid discharge head of the present invention, the liquid is ejected at a stable liquid discharge speed. In each bubble generation area, the bubble generation area is located on the downstream side. After the bubbles, the bubbles generated in the bubble generation area located on the upstream side are generated. As a result, droplets of different discharge volumes can be stably formed in each nozzle.

Under the enlightenment of a preferred embodiment of the present invention described below, other objectives and advantages other than the above are obvious to those skilled in the art. In the description, the drawings are numbered to form a part of an example of the present invention, and the example is described. However, the various embodiments of the present invention are not exhausted. Therefore, the claims used to determine the scope of the present invention at the end of the specification do not carry reference numerals.

Among them, the terms "upstream" and "downstream" used in the specification of the present invention refer to the direction of liquid flow from the liquid supply source through each bubble generating area (or each movable member) toward the liquid discharge port, or used as an indicator structure The expression of direction.

The term "downstream side" referring to the bubble itself refers to the downstream side of the aforementioned liquid flow direction or the aforementioned structural direction, or refers to the area where the bubble is generated is located on the downstream side of the central area of each heating member. Likewise, the term "upstream" referring to the bubbles themselves refers to the upstream side of the aforementioned liquid flow direction or the aforementioned structural direction, or refers to the area where the bubbles are generated is located on the upstream side of the central area of each heating member.

The expression used in the present invention: the "basic contact" between each movable member and the restricting member refers to the close state of a few μm liquid between the two or the state of direct contact between each movable member and the restricting member .

1A, 1B, 1C, 1D, 1E, and 1F are front cross-sectional views of the liquid discharge head according to the first embodiment of the present invention, taken along the direction of the liquid flow path. By dividing the process into stages AF, each liquid is shown A peculiar phenomenon in the flow channel.

Figures 2A, 2B, 2C, 2D, 2E, and 2F are perspective plan views of each process AF shown in Figures 1A-1F as viewed from the top plate side along the direction of the substrate through the top plate; Figures 2G, 2H, 2I, 2J, 2K, and 2L are front sectional views taken along the lines 2G-2G to 2L-2L viewed from the upstream side.

Fig. 3 is a perspective view showing a part of the liquid discharge head shown in Figs. 1B and 2B.

Fig. 4 is a perspective view showing a part of the liquid discharge head shown in Figs. 1C and 2C.

Figures 5A, 5B, 5C, 5D, 5E, and 5F show the front cross-sectional views of the liquid discharge head shown in Figures 1A-1F along the direction of the liquid flow channel. By dividing the process into AF, each liquid flow channel is shown Peculiar phenomenon.

Fig. 6 is a front cross-sectional view of an embodiment of the liquid discharge head shown in Figs. 1A-1F, taken along the direction of the liquid flow path, showing that when the bubble reaches the maximum volume, the basic structure composed of the movable member and the restricting member A state where the liquid flow in a closed space will not be blocked.

Figures 7A, 7B, 7C, 7D, 7E, and 7F are front cross-sectional views of the liquid discharge head according to the second embodiment of the present invention, taken along the direction of the liquid flow path. When the heating element located on the upstream side is driven, it passes The process is divided into stages AF, which represent the unique phenomena in each liquid flow channel.

Figures 8A, 8B, 8C, 8D, and 8E show the front cross-sectional views of the liquid discharge head shown in Figures 7A-7F. When the heating element located on the downstream side is driven, the process is divided into stages AE to indicate each liquid flow A peculiar phenomenon in Tao.

Fig. 9 is a perspective view showing a part of the liquid discharge head shown in Fig. 7B.

Figures 10A, 10B, 10C, 10D, 10E, and 10F show front cross-sectional views of the liquid discharge head shown in Figures 7A-7F. When the two heating components are driven, the process is divided into stages AF to indicate each liquid flow A peculiar phenomenon in Tao.

11A, 11B, and 11C are views showing another structure of the movable member shown in FIGS. 2A-2F, 3, and 4, respectively.

Fig. 12 is a graph showing the relationship between the area of the heating member and the ejection amount.

13A and 13B are longitudinal sectional views showing the liquid discharge head of the present invention. Fig. 13A shows an example with a protective film, and Fig. 13B shows an example without a protective film.

Fig. 14 is a view showing the driving waveform of the heating element used in the present invention.

Fig. 15 is an exploded perspective view showing the overall structure of the liquid discharge head of the present invention.

16A and 16B are views showing a side spray type liquid discharge head suitable for the liquid discharge method of the present invention.

Fig. 17 is a view schematically showing the configuration of a liquid discharge device having a liquid discharge head having the structure shown in Figs. 1A-1F, and Figs. 16A and 16B thereon.

FIG. 18 is a block diagram showing the entire apparatus for performing inkjet recording according to the liquid discharge method and the liquid discharge head of the present invention.

19 is a front cross-sectional view showing a liquid flow path for expressing the "linear communication state" of the liquid discharge head of the present invention.

(First Embodiment) FIGS. 1A-1F are front cross-sectional views showing the liquid discharge head according to the first embodiment of the present invention taken along the direction of the liquid flow path, which expresses the unique phenomenon in the liquid flow path by dividing the process into AF.

The heating element 2 in the liquid discharge head of this embodiment is located on a flat and smooth substrate 1 and acts as a liquid discharge energy generating element to cause thermal energy to act on the liquid to perform liquid discharge. A liquid flow channel 10 is provided on the substrate 1 corresponding to the heating member 2, and the liquid flow channel 10 communicates with the liquid discharge port 18 and at the same time communicates with the common liquid chamber 13 to supply liquid into the plurality of liquid flow channels 10. Each liquid flow channel receives a certain amount of liquid from the common liquid chamber 13, which corresponds to the amount of liquid discharged from each liquid discharge port 18. A reference mark M shows a meniscus-shaped liquid surface formed by the discharged liquid. The capillary force generated by each discharge port 18 and the inner wall of the liquid flow channel 10 connected to it makes the meniscus liquid surface near each discharge port 18 relative to the common liquid chamber 13 which is usually under negative pressure. The internal pressure is balanced.

The substrate 1 with the heating member 2 and the top plate 50 are adhered to form a liquid flow path 10, and a bubble generation area 11 is formed near the top plate where the heating member 2 is in contact with the discharge liquid, and the heating member 2 is rapidly heated in this region 11 to make The discharged liquid forms bubbles. Each liquid flow channel 10 with a bubble generating area 11 is respectively provided with a movable member 31 so that at least a part of the movable member faces the heating member 2. The free end 32 of the movable member 31 is located on the downstream side, facing the liquid discharge port 18, while the movable member 31 is supported on the support member 34 located on the upstream side. Specifically, in order to suppress the growth of half of the bubbles located on the upstream side, the free end 32 in this embodiment is located in the central part of the bubble generation area 11, where the growth of half of the bubbles located on the upstream side will affect the reverse flow toward the upstream side. And have an impact on the inertia of the liquid. As the bubble generated in the bubble generation area 11 grows, the movable member 31 can move relative to the support member 34. The fulcrum 33 of displacement is a part of the movable member 31 supported by the supporting member 34.

In order to suppress the growth of half of the bubbles located on the upstream side, a stopper (restriction member) 64 is provided above the central portion of the bubble generation area 11 to restrict the displacement of the movable member 31 within a certain range. A low liquid flow path resistance area 65 is provided in the path from the common liquid chamber 13 to the liquid discharge port 18, where the liquid flow path resistance is lower than the liquid flow path 10, and the stopper 64 is used on the upstream side as boundary. The structure of the liquid flow channel in the region 65 is such that the upper wall is not provided, or the cross-sectional area of the liquid flow channel is increased, so that when the liquid moves, the resistance of the liquid flowing through the channel can be reduced.

Utilizing the above structure, the characteristic of the liquid discharge head proposed by the present invention is that, unlike the prior art, each liquid discharge port 18 is not considered, and the movable member 31 and the stopper 64 are in contact with each other after being moved. , Each liquid flow channel 10 with a bubble generating area 11 forms a substantially closed space.

The liquid discharge operation of the liquid discharge head of this embodiment will be described in detail below.

FIG. 1A shows the situation before energy is not applied to the heating element 2, such as electric energy, and shows the situation before the heating element generates heat. What is important is that for each bubble generated by the heat generation of the heating member 2, the movable member 31 only faces half of the bubbles located on the upstream side, and the stopper 64 that restricts the movement of the movable member 31 is located at the center of the bubble generating region 11 Above. In other words, by virtue of the structure of the liquid flow channel and the arrangement position of each movable member, half of the bubbles on the upstream side can be suppressed under the movable member 31.

FIG. 1B shows a situation where a part of the liquid filled in the bubble generation area 11 is heated by the heating member 2 and the bubble 40 basically grows to the maximum after the film boils. At this time, the pressure wave generated by the bubble 40 spreads in the liquid flow channel 10, and the liquid moves to the upstream side and the downstream side with the central area of the bubble generation area as the boundary. Thereafter, on the upstream side, the movable member 31 moves with the growth of the bubble 40 under the action of the liquid flow. On the downstream side, the discharged liquid droplets 66 are ejected from the liquid discharge port 18. Due to the presence of the low resistance zone 65 of the liquid flow path, the movement of the upstream side liquid, that is, the liquid moving toward the common liquid chamber 13 forms a larger liquid flow. This is because the liquid flow resistance of the liquid flow channel at the resistance zone 65 is lower than that of the downstream side. With side resistance, the liquid flows easily. However, when the movable member 31 gets closer to or comes into contact with the stopper 64, its further movement will be restricted. Thereafter, the movement of the liquid to the upstream side is greatly restricted, and the growth of the bubble 40 to the upstream side is also restricted by the movable member 31 accordingly. However, since the moving force of the liquid directed to the upstream side is large, the movable member 31 is subjected to stress that pulls it to the upstream side. A part of the bubble 40 whose growth is restricted by the movable member 31 overflows through the narrow gap between the two side walls constituting the liquid flow channel 10 and the side of the movable member 31 and reaches the upper surface of the movable member 31. The overflowing bubbles are referred to as "overflowing bubbles 41" in the specification.

In the above embodiment, the overall structure of the liquid flow path toward the liquid discharge port is gradually widened from the upstream side of the movable member 31 to the downstream side.

The portion of the bubble 40 at the liquid discharge port of the present invention maintains a "linear communication state" with the liquid discharge port. Compared with the liquid flow channel shown in FIG. 19, a straight liquid flow channel structure is maintained between the bubble and the liquid discharge port. More specifically, the ideal state to be achieved is: the propagation direction of the pressure wave generated when the bubble grows, the direction of the liquid flow thereafter, and the direction of discharge are in a straight line, so that the discharge direction of the droplet 66 and its discharge speed , And other conditions are stable at a very high level. If the structure is only to connect the discharge port 18 and the heating part 2 (especially the heating part at the discharge port (located on the downstream side), which has a greater impact on the formation of bubbles) in a straight line, the present invention is sufficient as a solution. The above-mentioned ideal state or close to the ideal state of the structure. If there is no liquid in the liquid flow channel, the realized state can be observed from the outside of the liquid discharge port. Especially in this state, the downstream side of the heating member can be observed. In the above structure, it is better to arrange from the perspective of stabilizing the discharge direction so that the extension line of the discharge axis of the discharge port intersects the center of the heating member.

On the other hand, as described above, the movement of the movable member 31 to the part of the air bubble 40 located on the upstream side is restricted due to the presence of the stopper 64. Therefore, this part of the bubbles here is subject to the stress generated by the movable member 31, so the volume is small. Under the action of the inertia of the liquid flowing to the upstream side, the movable member 31 bends and protrudes to the upstream side. In this part, when viewed as a whole, the amount of air bubbles entering the area constituted by the stopper, the liquid flow channel partition 101, the movable member 31 and the fulcrum 33 is substantially zero.

Here, the total convex curvature should be within a small range of a maximum of nearly 20 microns.

At this time, the liquid in the space formed by the contact between the restricting member and the movable member comes into contact with the movable member when the bubble formed is maximized, and then comes into contact with the liquid on the downstream side of the bubble generation region in the space. More specifically, the structure is arranged so that the bubble does not cover the portion of the movable member that must be contacted when the bubble is the largest. When the movable member is out of the contact state, the structure can make the inflowing liquid flow smooth, and can be refilled quickly and stably. As shown in Fig. 6, it is preferable that the largest bubble 4a does not obstruct the liquid flow in the above-mentioned space so that it can be connected to the liquid located on the upstream side of the heating member 2 in the space. Here, the minimum liquid flow path distance (height) formed by the contact between the restricting member and the movable member is set to 40 microns or more, or the liquid flow resistance at the discharge port is made smaller than the above minimum liquid flow path distance In order to control the formation of bubbles, the structure can be formed.

In this way, the liquid flow to the upstream side is greatly restricted, avoiding the mixing of the liquid with the liquid in the adjacent nozzles, the backflow of the liquid in the liquid supply system which will hinder the further refilling described below, and the pressure change.

The liquid flow of this embodiment is disturbed by the upper surface of the movable member 31, so that bubbles surround the upper surface of the movable member 31, but the upper surface of the liquid flow channel top plate and the movable member 31 constituting the low liquid flow channel resistance region 65 They are all flat, and there is a narrow gap between them. Therefore, the bubbles located near the side of the movable member 31 must be a whole. Under the combined action of the above-mentioned state and the large liquid moving force directed to the upstream side, the movable member 31 is subjected to the stress that causes it to be pulled upstream as described above.

Fig. 1C shows a state when the negative pressure inside the bubble in the liquid flow channel prevents the liquid from moving to the downstream side after the film boils, and the bubble 40 starts to shrink. At this time, the liquid force generated by the bubble growth is still large on the upstream side. Therefore, after the bubble 40 starts to contract, the movable member 31 still contacts the stopper 64 within a certain period of time, and most of the contracted bubbles 40 form the moving force of the liquid from the liquid discharge port 18 in the upstream direction. In the state shown in FIG. 1B, the movable member 31 is subjected to compressive stress to bend it toward the upstream side. By drawing out the liquid flow from the stress relief side, that is, the upstream side shown in FIG. 1C, the force generated by the movable member itself causes it to form a convex surface in the upstream direction. Therefore, at a certain point, the force of pulling the movable member back from the upstream side exceeds the above-mentioned moving force of the upstream side liquid, and the liquid starts to flow from the upstream side to the liquid discharge port, albeit only slightly. As a result, the bending of the movable member 31 is reduced, so that it starts to move in a convex surface in the upstream direction. In other words, the air bubbles 40 on the upstream side and the downstream side are in an unbalanced state, and thus a unidirectional liquid flow is temporarily formed in the liquid flow path in the direction of the liquid discharge port as a whole.

Taking the liquid flow channel as a whole, the movable member 31 after moving inside it still remains in contact with the stopper 64 immediately thereafter. Therefore, regardless of the discharge port 18, the liquid flow channel 10 with the bubble generation area 11 is basically a closed space. The energy generated by the contraction of the bubble 40 is an important force in the overall balance, which causes the liquid near the discharge port 18 to move in the upstream direction. Therefore, the meniscus-shaped liquid surface M is deeply retracted from the liquid discharge port 18 into the inside of the liquid flow channel 10, thereby rapidly cutting off the liquid column connected to the discharged liquid droplet 66. As shown in FIG. 1D, the number of satellite spots (micro spots) 67 generated and left outside the liquid discharge port 18 is reduced.

FIG. 1D shows the state of truncating the meniscus-shaped liquid surface M and the discharged liquid droplet 66 when the bubble disappearing process is basically finished. In the low liquid flow path resistance area 65, the movable member 31 starts to move downward. Since the elasticity of the movable member 31 resists the liquid moving force pointing in the upstream direction and the contraction force generated by the disappearance of the bubble 40, the movable member moves. After the above movement, the liquid flow in the low liquid flow channel resistance zone 65 starts to flow in the downstream direction. After the passage is closed, the contact between the movable member 31 and the stop member 64 starts to separate. The liquid flow in the downstream direction in the low liquid flow channel resistance zone 65 increases rapidly and flows into the liquid flow channel 10 through the stopper 64, wherein the liquid flow channel resistance in the resistance zone 65 is relatively small. As a result, the liquid flow that retracts the meniscus-shaped liquid surface M into the liquid flow channel 10 is drastically reduced. The half-moon-shaped liquid surface M begins to return to the position where bubbles are formed at a relatively slow speed, and as much as possible the liquid column remaining outside the discharge port 18 or forming a convex surface in the direction of the discharge port 18 is sucked in instead of being sucked into it. Truncated. The return flow through the meniscus M and the flow refilled from the upstream side are added together to form an area where the flow rate is almost zero between the liquid discharge port 18 and the heating element 2, thereby making the meniscus shape The liquid level is calmer. This operation depends on the flow rate and surface tension of the ink, but the present invention can greatly reduce the satellite points separated from the liquid column. When the satellite points are attached to the printed product, the image quality will be reduced. When the nozzle is on the circumference, it will affect the discharge and have a negative effect on the direction of the discharge.

Before the meniscus-shaped liquid level M is sucked into the liquid flow channel deeply, the liquid level M will start to recover by itself. Therefore, although the moving speed of the liquid itself is not very high, the above recovery will be completed in a short time. Therefore, a meniscus-shaped liquid surface is rarely formed excessively, that is, it is rarely unstable at the discharge port 18 and protrudes out of the discharge port 18 more. After that, the phenomenon of slight vibration with the discharge port 18 as a balance point can be eliminated in a very short time, and it is this phenomenon that causes excessive formation of a meniscus-shaped liquid surface. This phenomenon of slight vibration also has a negative effect on print quality. Since this phenomenon is eliminated more quickly, the present invention is beneficial to realize stable and high-quality printing.

Relative to the state of linear communication on the downstream side and the bubbles and liquid on the heating part during the disappearance of the bubbles, the basically closed environment dominates on the upstream side, and an extremely unbalanced state may occur. In other words, the vanishing point of the bubble moves violently in the direction of the fulcrum of the movable member. The subsequent liquid flow in the upstream direction also moves at high speed on the surface of the heating element (see Figures 5A-5F).

The above-mentioned liquid flow helps to eliminate liquid stagnation or siltation, which will cause the formation of bubbles on the surface of the heating member to become unstable, and at the same time, the above-mentioned liquid flow improves the surface uniformity and enhances the stability of the bubbles. Moreover, if the aforementioned bubble disappearing point moves from the heating element to the fulcrum side, the cavitation may not directly damage the heating element. As a result, the service life of the heating components is significantly increased.

Furthermore, since the liquid flow that moves the vanishing point of the bubble can flow out of the liquid flow channel 10 and the common chamber 13 from the side of the movable member 31, liquid sludge can be eliminated more effectively.

As shown in FIG. 1D, the flow rate of the liquid flowing into the liquid flow path 10 through the space between the movable member 31 and the stopper 64 as described above is accelerated on the surface of the wall on the side of the top plate 50. Therefore, the remaining bubbles, such as the fine bubbles here, become very small, which significantly increases the stability of the drainage.

On the other hand, since the rapid suction as shown in FIG. 1C forms a meniscus-shaped liquid surface, some of the satellite points 67 left immediately after the above-mentioned discharged liquid droplet 66 are very close to the discharged liquid droplet. A so-called "slip stream" phenomenon occurs here. A vortex is generated behind the flying discharged droplet 66. The above phenomenon causes the satellite point to follow the discharged droplet and is attracted by the discharged droplet.

This phenomenon will be accurately described below. In the conventional liquid discharge head, the liquid droplets are not spherical when ejected from the liquid discharge port of the liquid discharge head. When the droplet is ejected, it is basically a liquid column with a spherical top. Its tail is elongated by the main droplet and the half-moon-shaped liquid surface, and when it is cut off from the half-moon-shaped liquid surface, a satellite point is formed at its tail. It is known that the satellite points fly toward the recording medium together with the main droplet. The satellite point flies behind the main drop, and the satellite point is attracted by the half-moon-shaped liquid surface. Therefore, the ejection speed of the satellite point is reduced, so that its striking position deviates from the striking position of the main droplet. This inevitably reduces the print quality. The force of the liquid discharge head of the present invention to suck back the half-moon-shaped liquid surface is far greater than the aforementioned traditional liquid discharge head. Therefore, after the main droplet is discharged, the suction force acting on the tail increases. The force of cutting off the tail from the half-moon-shaped liquid surface is correspondingly increased, shortening the action time. As a result, the satellite point formed by the tail becomes very small, and the distance between the main droplet and the satellite point is also reduced. Furthermore, since the tail will not be continuously attracted by the meniscus for a long period of time, the ejection speed will not be reduced. Thus, due to the slipstream phenomenon occurring behind the discharged droplet 66, the satellite point 67 is attracted to the main droplet.

Fig. 1E shows a state resulting from the further development of the state shown in Fig. 1D. Here, the satellite 67 is closer to the discharged liquid drop 66. At the same time, the satellite points are sucked toward the discharged droplets. Then, the attractive force generated by the slipstream phenomenon increases accordingly. On the other hand, due to the completion of the bubble disappearing process of the bubble 40 and the excessive movement of the movable member 31, the movement of the liquid from the upstream side in the direction toward the liquid discharge port 18 is lower than the initial position. After that, the phenomenon that occurs is that the liquid is sucked from the upstream side and discharged in the direction toward the liquid discharge port 18. Furthermore, due to the stopper 64, by enlarging the cross-sectional area of the liquid flow channel, the liquid flow increases in the direction toward the liquid discharge port 18, and the recovery speed of the meniscus-shaped liquid surface M to the liquid discharge port 18 is increased. In this way, the refill performance of this embodiment is significantly improved.

As shown in FIG. 5E, in the process of the bubble disappearing in the present invention, the bubble disappearing point, that is, the so-called cavitation point 42 is located in the lower region of the movable member 31. Furthermore, when cavitation occurs, the movable member 31 also moves downward, and the movable member stays on the line connecting the cavitation point 42 and the discharge port 18 in a straight line (indicated by a broken line in FIG. 5E). Therefore, the shock wave generated by the cavitation will not directly affect the discharge port. This reduces or eliminates the scattering of liquid droplets from the meniscus-shaped liquid surface caused by air pockets, the so-called "micropoints". This is because when the shock wave reaches the movable member 31, the movable member 31 itself bounces back the shock wave generated by the cavitation or absorbs its energy. The vibration absorbed by the movable member propagates in the direction of the fulcrum and is attenuated during the propagation process. Therefore, there is almost no negative effect on drainage.

Moreover, when air pockets are generated when the bubbles disappear, the movable member 31 moves downward to separate the bubble disappearing point and the liquid discharge port 18. Therefore, the shock wave of cavitation does not directly affect the discharge port 18, and most of them are absorbed by the movable member 31. Therefore, when the shock wave of the air pocket reaches the half-moon-shaped liquid surface, almost no ultra-fine droplets are generated on the half-moon-shaped liquid surface, that is, the so-called "micropoints". This significantly reduces the phenomenon that the micro-dots adhere to the substrate and reduce the image quality; or the micro-dots adhere to the periphery of the liquid discharge opening 18 and cause the liquid discharge to be unstable.

Moreover, with the movable member 31, the point where air pockets are generated due to the disappearance of bubbles can be moved to the side of the fulcrum 33. As a result, damage to the heating component 2 is reduced. The excessively viscous ink is forcibly taken out from the enclosed area between the movable member 31 and the heating member 2 in order to remove it, thereby enhancing the service life of the liquid discharge device. It is also possible to reduce the adhesion of overheated ink to the heating member caused by this phenomenon in this area, which will improve the stability of the liquid discharge device.

FIG. 1F shows a situation obtained when the state shown in FIG. 1E is further developed, and a satellite 67 is added to the ejected droplet 66. For other embodiments, the combination of the ejected droplets 66 and the satellite 67 does not necessarily occur under any conditions during each ejection. Depending on the conditions, this phenomenon occurs or does not occur at all. However, by eliminating satellite points or at least reducing the number of satellite points, there is almost no deviation between the striking positions of the main droplet and the satellite points on the recording medium, thereby minimizing negative effects on print quality. In other words, the sharpness of the printed image is enhanced, so as to obtain better printing quality, and at the same time, the image can be prevented from being fogged, and the generated fog can reduce the occurrence of bad phenomena such as dirtying the printing medium or the inside of the recording device.

In the meantime, due to the reaction of its overspray, the movable member 31 moves in the direction toward the stopper 64 again. Due to the structure of the movable member 31, the Young's coefficient, the viscosity of the liquid in the liquid flow channel, and the gradually weakened vibration determined by gravity, the movable member 31 stops moving, and thus the movement finally stops at the initial position.

The upward movement of the movable member 31 controls the liquid to flow from the common chamber 13 in the direction toward the liquid discharge port 18. Then, the movement of the meniscus-shaped liquid surface M quickly stops at the periphery of the liquid discharge port. As a result, the factors that may reduce the print quality can be significantly reduced, and the liquid discharge state may be unstable due to the over-ejection of the meniscus liquid surface or the like.

The following focuses on the specific effects of this embodiment.

Figures 2A-2F are perspective plan views of each process AF shown in Figures 1A-1F when viewed from the top plate side to the direction of the substrate through the top plate; Figures 2G-2L are viewed from the upstream side along the line of Figures 1A-1F A cross-sectional view taken from the lines 2G-2G to 2L-2L in the middle. Fig. 3 is a perspective view showing a part of the print head shown in Figs. 1B and 2B. Fig. 4 is a perspective view showing a part of the print head shown in Figs. 1C and 2C. The heating member 2, the movable member 31 and the air bubble 40 are displayed opaquely, while the liquid is displayed transparently.

In this embodiment, FIGS. 2A-2L show the state when the movable member envelops the bubble when the bubble grows. As shown in FIGS. 2A-2L, there is a narrow gap between the two side surfaces of the wall constituting the liquid flow path 10 and the side portions of the movable member 31, so that the movable member 31 can be moved smoothly. Furthermore, with the help of the heating member 2 during the bubble growth stage, the bubble 40 causes the movable member 31 to move. Air bubbles can reach the upper surface of the movable member 31 through the gap, and enter the low liquid flow path resistance area 65 in a small amount (see FIG. 2B and FIG. 3). The overflowing air bubbles 41 enter the area at the periphery of the back of the movable member 31 (the back of the bubble generating area 11), so as to suppress the deflection of the movable member 31 and stabilize the discharge performance.

Furthermore, when the bubble 40 starts to disappear, due to the gap, when the overflowing bubble is drawn into the bubble generating area 11 from the low liquid flow path resistance region 65 through the gap, the overflowing bubble 41 causes the liquid to flow from the upstream side of the movable member . As shown in FIG. 4, while the bubble 40 disappears rapidly, the meniscus-shaped liquid surface is sucked back from the liquid discharge port 18 side at the aforementioned high speed. At this time, the liquid discharge port 18 is removed, and by means of the mutual contact between the movable member 31 and the stopper 64 after the movement, the liquid flow channel 10 with the bubble generation area 11 forms a substantially closed space, thereby forming a closed space. The so-called "wells" surrounded by each space filled with liquid. In this "well", the contraction of the bubble 40 causes the fluid to immediately appear from the gap and the side of the discharge port 18. Therefore, the bubbles and heat accumulated in the vicinity of the heating member 2 can be eliminated even in a system without a liquid circulation system, so that extremely stable liquid discharge performance can be obtained. In this regard, the structure of this embodiment is designed so that the bubbles can overflow from the gap when the bubbles grow. However, if the bubble can be wrapped by the movable member as it grows, and when the bubble disappears, the bubble can flow into the bubble generation area together with the liquid on the upstream side of the movable member through the gap, there is no need to restrict the overflow of the bubble in this design. Similarly, in order to achieve this design, it is best to set the width of each gap to 8-13 μm.

Furthermore, during the disappearance of the bubble of the bubble 40, the overflowing bubble 41 causes the liquid to flow from the low liquid flow path resistance area 65 to the bubble generation area 11, and at the same time, the meniscus-shaped liquid surface is sucked back from the liquid discharge port 18 at a high speed as described above. , The process of disappearing bubbles is completed quickly. Specifically, due to the liquid flow generated by the overflowing air bubble 41, it is almost impossible for air bubbles to remain in the corners of the movable member 31 and the liquid flow path 10.

With the liquid discharge head configured as described above, when liquid droplets are discharged from the liquid discharge port by generating bubbles, the discharged liquid droplets are almost in the form of a liquid column having a spherical portion at the end. This situation is the same as the conventional structure of the liquid discharge head. However, the movable member of the present invention is moved by the bubble growth process. After that, when the moved movable member comes into contact with the restricting member, removing the liquid discharge port will cause the liquid flow path with the bubble generation area to form a Basically closed space. Therefore, if the bubble disappears in this state, the closed space will be maintained until the movable member leaves the restricting member due to the disappearance of the bubble. Therefore, most of the energy that the bubbles disappear can be used to move the liquid near the discharge port to the upstream side. Therefore, after the bubble disappears, the half-moon-shaped liquid surface is quickly sucked into the inside of the liquid flow channel. After that, the huge suction force formed by the half-moon-shaped liquid surface can quickly cut off the liquid formed by connecting with the discharged liquid drop outside the discharge port. The tail of the column. In this way, each satellite point formed by the tail will become smaller, which helps to significantly improve the quality of the printed product.

Furthermore, since the tail portion is not continuously subjected to the suction force of the meniscus-shaped liquid surface for a long period of time, the discharge speed does not slow down. Similarly, the distance between the discharged droplet and each satellite point is shortened, so that the satellite point is attracted to the discharged droplet by virtue of the so-called "slip stream" that appears behind the flying droplet. Therefore, a combination of discharged liquid droplets and satellite dots will be formed, so that a liquid discharge head that hardly generates satellite dots can be formed.

The present invention is also special in that the movable member only suppresses bubbles that grow in the upstream direction with respect to the liquid flow toward the liquid discharge port of the liquid discharge head. It is more preferable that the free end of the movable member is substantially located in the central part of the bubble generation area. This structure can suppress backflow to the upstream side and liquid inertia due to bubble growth, which is not directly related to discharge. This makes it possible to easily guide the growth components of the bubbles on the downstream side to the discharge port. Furthermore, the special feature of the present invention is that, in the liquid discharge head, the restriction member is used as the boundary to reduce the liquid flow path resistance of the liquid flow path located on the side opposite to the liquid discharge port. With the above structure, since the liquid flow channel with low resistance of the liquid flow channel is added, the movement of the liquid in the upstream direction caused by the growth of the bubble becomes a larger liquid flow. Therefore, when the movable member being moved comes into contact with the restricting member, the movable member is subjected to stress that tries to pull it in the upstream direction. Therefore, if the bubble disappearing process starts at this time, the moving force of the liquid in the upstream direction due to the growth of the bubble is still fully retained, so that it can maintain the above-mentioned closed space for a certain period of time, until the elasticity of the movable member overcomes the reason The force generated by the movement of the liquid. In other words, with the above structure, the half-moon-shaped liquid surface can be sucked back more reliably at high speed. Similarly, when the bubble disappearing process develops to the extent that the elasticity of the movable member exceeds the force of the liquid moving in the upstream direction caused by the growth of the bubble, the movable member moves downward in order to return to the initial state, and then even in the low liquid state. The resistance zone of the flow channel will also form a flow in the downstream direction. Due to the low resistance of the liquid flow channel in the downstream direction of the liquid flow in the low liquid flow channel resistance zone, the liquid flow quickly becomes a larger liquid flow and flows into the liquid flow channel through the restricting member. Therefore, as the liquid moves downstream toward the discharge port, the suction of the meniscus liquid surface is quickly stopped, and the vibration of the meniscus liquid surface is stabilized very quickly.

(Second Embodiment) The second embodiment of the present invention will be described below with reference to the drawings.

Figures 7A-7F and Figures 8A-8E are front cross-sectional views of a liquid discharge head according to an embodiment of the present invention taken along the direction of the liquid flow channel. When the heating element located on the upstream or downstream side is driven, the process is divided into AF and AE respectively show unique phenomena in each liquid flow channel. Figs. 7A-7F show a peculiar phenomenon when driving each heating element located on the upstream side. 8A-8E show the unique phenomenon when driving each heating element located on the downstream side.

In the liquid discharge head of this embodiment, the heating members 2 and 3 are arranged on a flat and smooth substrate 1 so that heat energy is applied to the liquid to discharge the liquid as a liquid discharge energy generating element. On this substrate 1, liquid flow channels 10 are provided corresponding to the heating members 2 and 3, respectively. For one liquid flow channel 10, each of the heating elements 2 and 3 is arranged in the longitudinal direction, respectively. Each heating element can generate heat independently. The heating member 3 located on the downstream side occupies a smaller area than the heating member 2 located on the upstream side. This is to reduce the discharge amount of each droplet ejected. By using the above-mentioned two heating elements 2 and 3, which can be driven appropriately, ejection droplets with different discharge volumes can be ejected respectively.

The liquid flow channel 10 is connected to the liquid discharge port 18 and is connected to the common chamber 13 at the same time, so as to supply liquid into a plurality of liquid flow channels 10. Each liquid flow channel 10 receives a certain amount of liquid from the common chamber 13 corresponding to the amount of liquid discharged from each liquid discharge port 18. The reference mark M shows a meniscus-shaped liquid surface formed by the discharged liquid. With respect to the internal pressure of the common chamber 13 which is usually negative due to the capillary force, the meniscus-shaped liquid level M is balanced near each discharge port 18, wherein the above-mentioned capillary force is generated by each discharge port. 18 and the inner wall of the liquid flow channel 10 connected to it.

The structure of the above-mentioned liquid flow path 10 is as follows: the substrate 1 with the heating members 2 and 3 and the top plate 50 are bonded, and the bubble generation regions 11 and 12 are located in the area near the plane contacting the heating members 2 and 3 and the ejected liquid. The heating parts 2 and 3 can be quickly heated to make the sprayed liquid form bubbles. The movable member 31 is provided in each liquid flow channel 10 so that at least a part thereof faces the bubble generation area 11 on the upstream side, and the movable member is made to grow with the bubbles generated by heating the heating members 2 and 3 It can be moved. The movable member 31 has its free end 32 on the downstream side, facing the liquid discharge port 18, and at the same time, it is supported by the support member 34 on the upstream side. In this embodiment, in order to suppress the growth of half of the bubbles located on the upstream side, the free end 32 is provided in the central portion of the bubble generation area 11, where the growth of the half of the bubbles will cause the backflow and liquid inertia toward the upstream side to be generated. influences. The fulcrum 33 located where the movable member 31 can move serves as a supporting part of the supporting member 34 to the movable member 31.

In order to suppress the growth of half of the bubbles generated by the heating member 2 on the upstream side, a stopper (restriction member) 64 is provided above the central portion of the bubble generation area 11 to restrict the movement of the movable member 31 within a certain range. In the liquid flow flowing from the common chamber 13 to the liquid discharge port 18, a low liquid flow channel resistance region 65 is provided on the upstream side with the stopper 64 as a boundary, and the resistance of the liquid flow channel is smaller than that of the liquid flow channel 10. The structure of the liquid flow channel in the area 65 is designed so that there is no upper wall and the cross-sectional area of the liquid flow channel is not enlarged. That is, when the liquid flows, the resistance of the liquid from the liquid flow channel is small.

Using the above structure, it is recommended to make a liquid discharge head structure different from the prior art. The special feature of the liquid discharge head is that each discharge port 18 is removed, by means of the movable member 31 and the stopper 64 after the movement. In contact with each other, each liquid flow channel 10 with bubble generating regions 11 and 12 constitutes a substantially closed space.

The liquid discharge operation of the liquid discharge head of this embodiment will be described in detail below. As described above, for one liquid flow channel 10, the liquid discharge head of this embodiment has two heating members 2 and 3, respectively. Therefore, depending on which of the heating members 2 and 3 is driven, there may be multiple discharge modes.

First, referring to Figs. 7A-7F, the discharge operation when the heating member 2 located on the upstream side is driven will be described.

FIG. 7A shows a state before energy, such as electric energy, is applied to the heating member 2, and this figure shows a state before the heating member 2 generates heat. What is important here is that for each bubble formed by the heating member 2, the movable member 31 should face the half of the bubble located on the upstream side, and the stopper 64 that restricts the movement of the movable member 31 is provided in the center of the bubble generating area 11. Section above. In other words, by the structure of the liquid flow channel and the position setting of each movable member 31, half of the bubbles located on the upstream side are wrapped under the movable member 31.

FIG. 7B shows a state where a part of the liquid filled in the bubble generating area 11 is heated by the heating member 2 so that the bubble 40 grows to the maximum as the film boils. Thereafter, the liquid in the liquid flow channel 10 moves to the downstream side and the upstream side due to the action of the pressure wave generated by the generation of the air bubble 40. On the upstream side, the movable member 31 is pushed by the liquid flow accompanying the growth of the bubble 40, and on the downstream side, the ejected liquid droplets 66 are discharged from the liquid discharge port 18. Here, the liquid moves to the upstream side, that is, moves toward the common chamber 13, and a large liquid flow is formed by the low liquid flow path resistance area 65. However, when the movable member 31 moves close to the stopper 64 or stops when it comes into contact with the stopper, its further movement is restricted, thereby restricting a large amount of liquid from moving to the upstream side there. At the same time, the presence of the movable member 31 also restricts the growth of the air bubble 40 to the upstream side. However, since the moving force of the liquid in the direction toward the upstream side is great, the stress received by the movable member 31 pulls it toward the upstream side. Furthermore, a part of the air bubbles 40 whose growth is restricted by the movable member 31 passes through the tiny gaps between the two sides of the movable member 31 and the walls on both sides. The above-mentioned walls on both sides are formed by each protruding from the movable member 31. The liquid flow channel 10 on the surface side is formed. The above-mentioned overflowing bubbles are referred to as "overflowing bubbles 41" in this specification.

FIG. 7C shows the state when the bubble 40 starts to shrink, when the negative pressure in the bubble exceeds the liquid and moves to the downstream side in the liquid flow channel, and then enters the aforementioned film boiling stage. At this time, the liquid force generated by the growth of the bubble in the upstream direction still remains large. Therefore, the movable member 31 still maintains contact with the stopper 64 for a period of time after the bubble 40 starts to contract. The contraction of most of the bubbles 40 causes the liquid to move from the liquid discharge port 18 in an upstream direction. In other words, after the state shown in FIG. 7B, the stopper 64 immediately contacts the moved movable member 31, so that the liquid flow channel 10 with the bubble generating area 11 forms a substantially closed space except for the liquid discharge port 18. Therefore, the energy generated by the contraction of the bubble 40 can be used as a force for moving the liquid in the vicinity of the liquid discharge port 18 in the upstream direction. As a result, the meniscus-shaped liquid surface M is deeply drawn into the liquid flow channel 10 from the liquid discharge port 18, so that the liquid column connected to the discharged liquid droplet 66 is strongly and quickly cut off. Therefore, as shown in FIG. 7D, the number of satellite dots (micro dots) 67 remaining outside the liquid discharge port 18 is significantly reduced.

FIG. 7D shows the state where the liquid droplet 66 is ejected after the bubble disappearing process is finished and the meniscus-shaped liquid surface M is cut off. In the low liquid flow path resistance region 65, the elasticity of the movable member 31 exceeds the moving force of the liquid in the upstream direction. After that, the movable member 31 starts its downward movement. Along with this, the liquid flow in the low liquid flow path resistance region 65 starts to move in the downstream direction. At the same time, since the liquid flow is in the downstream direction of the low liquid flow channel resistance zone 65, the liquid flow channel resistance is relatively small, so the liquid flow quickly becomes larger and partially flows into the liquid flow channel 10 through the stopper 64. Therefore, the liquid flow drawn into the inside of the liquid flow passage 10 by the meniscus-shaped liquid surface M is suddenly reduced. After that, the half-moon-shaped liquid surface M starts to return to the position when the bubbles started to be generated at a relatively slow speed, and at the same time sucks back the liquid column remaining outside the liquid discharge port 18. In this way, the vibration of the meniscus is stabilized at a high speed.

On the other hand, due to the rapid retraction of the meniscus-shaped liquid surface as shown in FIG. 7C, the discharged liquid droplet 66 and the satellite 67 following the discharged liquid droplet are very close to each other. Then a so-called slipstream phenomenon occurs. Due to the vortex formed behind the flying discharged droplet 66, the slipstream phenomenon causes the satellite point to closely follow the discharged droplet and is attracted by it.

The above phenomenon is exactly described below. With the conventional liquid discharge head, the liquid is not spherical when it is discharged from the liquid discharge port of the liquid discharge head. The liquid droplet is almost in the shape of a liquid column when it is discharged, and its spherical part is located at its end. Therefore, its tail is simultaneously tensioned by the main droplet and the half-moon-shaped liquid surface. When it is cut off from the half-moon-shaped liquid surface, the satellite point is formed by the tail. It is currently known that the satellites fly to the recording medium together with the main droplet. The satellite point flies behind the main droplet, and the satellite point is also attracted by the half-moon-shaped liquid surface. Therefore, its ejection speed becomes slow, so that the striking position of the satellite point is different from the position of the main droplet. This inevitably reduces the quality of printing. As mentioned above, the force of the liquid discharge head of the present invention to suck back the meniscus liquid surface is greater than that of the conventional liquid discharge head. Therefore, after the main droplet is discharged, the attraction force to the tail is increased. The force of truncating the tail from the half-moon-shaped liquid surface increases, and it speeds up accordingly. Therefore, the satellite point formed by the tail becomes smaller, and the distance between the main droplet and the satellite point is also shortened. Furthermore, since the tail will not be continuously attracted by the half-moon-shaped liquid surface for a long period of time, the discharge speed will not slow down. Thereafter, the satellite 67 is attracted to the main droplet under the action of the slip flow phenomenon that appears behind the discharged droplet 66.

Fig. 7E shows a state in which the state shown in Fig. 7D is further developed. Here, the satellite 67 is closer to the discharged droplet 66, and at the same time, is attracted to the discharged droplet. Since then, the attraction generated by the slipstream phenomenon has increased. On the other hand, the movement of the liquid from the upstream side in the direction toward the liquid discharge port 18 creates a phenomenon in which the liquid is sucked out from the upstream side and pushed in the direction of the liquid discharge port 18, due to the excessive movement of the movable member 31 The movement causes it to be moved lower than its initial position. Furthermore, due to the stopper 64, the cross-sectional area of the liquid flow channel is enlarged, the liquid flow toward the liquid discharge port 18 is increased, and the speed at which the meniscus liquid surface returns to the liquid discharge port 18 is increased. As a result, the refill performance of this embodiment is significantly improved.

Fig. 7F shows a state in which the state shown in Fig. 7E is further developed. The satellite 67 merges into the discharged droplet 66. For other embodiments, it is not necessary that the combination of the liquid droplet 66 and the satellite 67 is discharged every time the jet is ejected under any circumstances. Depending on the situation, the above phenomenon occurs or does not occur at all. However, by removing satellite points or at least reducing the number of satellite points, there is almost no deviation between the striking positions of the main droplet and the satellite points on the recording medium, thereby minimizing the negative effect that affects the quality of printing. In other words, the sharpness of the printed image is improved to improve the print quality, while avoiding the generation of fog, and reducing the occurrence of problems such as the fog that pollutes the printing medium or the interior of the recording device.

In the meantime, due to the reaction of the excessive movement of the movable member 31, the movable member 31 moves in the direction of the stopper 64 again. Thereafter, the vibration determined by the structure of the movable member 31, Young's modulus, liquid velocity in the liquid flow path, and gravity is reduced to stabilize it, and finally the movable member stops at its initial position. With the upward movement of the movable member 31, in order to quickly stabilize the movement of the meniscus-shaped liquid surface near the liquid discharge port, the liquid flow from the common chamber 13 side in the direction toward the liquid discharge port 18 is controlled. This can significantly reduce the phenomenon of excessive movement of the meniscus and other factors that make the discharge conditions unstable and reduce the quality of printing.

The following describes other special effects when the heating element 2 located on the upstream side is driven.

Fig. 9 is a perspective view showing a part of the liquid discharge head shown in Fig. 7B. Fig. 9 shows a state basically the same as that of Fig. 7B except for the nozzles that are perspectively marked with a broken line. In this embodiment, there is a slight gap between the two side walls constituting the wall of the liquid flow channel 10, and the two sides of the movable member 31 allow the movable member 31 to be moved smoothly. Furthermore, in the process of bubble growth using the heating member 2, the bubble 40 moves the movable member 31, and at the same time, the bubble overflows to the upper surface side of the movable member 31, and enters the low liquid flow path resistance area 65 through the gap. The overflowing bubbles 41 entering the region 65 wrap around the back of the movable member 31 (the side opposite to the bubble generating region 11) to suppress the displacement of the movable member 31, thereby stabilizing the displacement performance.

Furthermore, during the disappearance of the bubble of the bubble 40, the overflow bubble 41 pushes the liquid to flow from the low liquid flow channel resistance area 65 to the bubble generation area 11, and at the same time sucks back to the meniscus-shaped liquid surface from the liquid discharge port 18 side at a high speed as described above. The process of disappearing bubbles is completed quickly. Specifically, by virtue of the liquid flow generated by the overflowing air bubble 41, it is almost impossible for the air bubble to remain in the corners of the movable member 31 and the liquid flow path 10.

Next, referring to Figs. 8A-8E, the liquid discharge operation when the heating member 3 located on the downstream side is driven will be described.

FIG. 8B shows a state where a part of the liquid filled in the bubble generation area 12 is heated by the heating member 3 located on the downstream side, so that the bubble 42 grows to the maximum as the film boils. After that, on the downstream side, the ejected liquid droplets 68 are discharged from the liquid discharge port 18. The size of the discharged liquid droplet is smaller than the liquid droplet 66 discharged by the above-mentioned driving of the heating member 2 located on the upstream side (see FIGS. 7A-7F). On the other hand, the liquid outflow is now on the upstream side. However, since the movable member 31 is moved to a certain extent by the liquid flow, the flow of the liquid flow to the upstream side is restricted.

FIG. 8C shows the shrinking process of the bubble 42. At this time, the bubble disappearing point of the bubble 42 has deviated from the heating member 3 to the upstream side. Because the distance is long and the movable member 31 and the stopper 64 are provided, the cross-sectional area of the liquid flow path is small, so the bubble 42 The resistance of the liquid flow path to the common chamber 13 is far greater than the resistance of the liquid flow path from the bubble 42 to the liquid discharge port 18. This means that the meniscus-shaped liquid surface M is sucked back to a greater extent, so that the discharged liquid droplets 68 can maintain a sufficient discharge speed, while suppressing the discharge volume to a low level.

FIG. 8D shows the end of the bubble disappearing process, and also shows the state where the discharged liquid drop 68 and the meniscus-shaped liquid surface M are cut off. At this time, the movable member 31 moves downward after the bubbles disappear. Therefore, the resistance of the liquid flow channel is small, and the meniscus-shaped liquid level M returns to its original state at a high speed.

In FIG. 8E, the movable member 31 moves upward due to its own elasticity, suppressing the high-speed liquid flow from the upstream side, thereby quickly stabilizing the operation of the meniscus M. As shown in Figs. 7A-7F, the liquid discharge condition can be stabilized by the stable movement of the meniscus-shaped liquid surface M, so as to improve the printing quality.

As mentioned above, the liquid discharge head of this embodiment utilizes each heating member 2 on the upstream side described in conjunction with FIGS. 7A-7F and each heating member 3 on the downstream side described in conjunction with FIGS. 8A-8E, with the aid of Larger droplets can achieve high-speed printing, and smaller droplets can be used to achieve high-quality printing.

Specifically, the heating member 2 for larger droplets is located on the upstream side of the heating member 3 for smaller droplets, and the bubbles 40 formed by the heating member 3 are blocked by the stopper 64 and the movable member located in the central area. 31 is divided, so that large droplets and small droplets can be discharged stably at high speed. Similarly, the number of satellites and the vibration of the half-moon liquid surface can be reduced, and high-quality prints can be obtained. In order to describe more accurately, the ejection velocity of each drop must be maintained at a certain level or higher. In the present invention, the heating element 3 for smaller droplets is arranged on the side close to the discharge port 18 to increase the discharge speed and at the same time increase the speed at which the meniscus-shaped liquid surface M is sucked back under the action of the movable member 31 , Thereby suppressing the increase in the discharge volume. Arranging the heating element 2 for larger droplets on the upstream side can suppress the growth of bubbles 40 to the common chamber 13 side by virtue of the movable member 31, thereby maintaining very reliable liquid discharge conditions.

Furthermore, since only one movable member 31 is provided in a one-to-one correspondence with the liquid flow path 10, compared with the case where the movable member is provided for each of the heating members 2 and 3, it is possible to reduce the amount required to support the movable member. The space on the substrate 1 is minimized. Likewise, the free end 32 of the movable member 31 is located above the heating member 2 on the upstream side. Therefore, the movable member 31 does not need to be lengthened, so that the movement of the movable member 31 better matches the movement of each of the bubbles 40 and 42 accordingly. Therefore, when each heating member 2 and 3 is driven by high frequency, the movable member 31 will function more reliably for each bubble 40 and 42 in the liquid and liquid flow path 10.

So far, the case where the two heating members 2 and 3 are driven separately to discharge liquid has been described, but it is also possible to drive the two heating members 2 and 3 at the same time to eject larger liquid droplets.

Next, a liquid discharge method for ejecting larger droplets by driving the two heating members 2 and 3 at the same time will be described with reference to FIGS. 10A-10F.

If you want to drive the heating components 2 and 3 to eject larger droplets at the same time, you can increase the discharge volume, but because the number of satellites has increased, the quality of the printed product will be reduced. However, in the present invention, after the heating member 3 on the downstream side is driven, the heating member 2 on the upstream side is driven with a certain delay time. As a result, the discharge volume can be stably increased.

First, as shown in FIG. 10A, the heating member 3 located on the downstream side is driven to generate bubbles 42. As shown in FIG. 10B, the heating element 2 on the upstream side is driven to generate the air bubbles 40 after approximately 5-15 μs after the heating element 3 is driven. At this time, the bubbles 42 generated by the heating member 3 located on the downstream side have entered the shrinking process. However, the liquid flow to the liquid discharge port 18 is also composed of the generated large-volume bubbles 40, so that the liquid discharge speed can be greatly increased in the subsequent spraying process. Therefore, larger droplets can be ejected at a stable liquid discharge speed (usually 8-20 m/s or preferably 10-18 m/s).

In FIG. 10C, with the disappearance of the bubbles 40 and 42 and the state after the movable member 31 moves, the meniscus-shaped liquid surface M is sucked back at a high speed, reducing the number of satellite points. In the process shown in FIG. 10D and the like, basically the same functional effects as those in FIG. 7D and the like are produced.

(Other Embodiments) The following describes various embodiments applicable to the liquid discharge head using the aforementioned liquid discharge method.

(Movable member) FIGS. 11A-11C are views showing other structures of the movable member 31. As shown in FIG. Fig. 11A shows a rectangular movable member; Fig. 11B is an example in which the fulcrum side is narrow to make the operation of the movable member more convenient; Fig. 11C is an example in which the fulcrum side is wider to increase the strength of the movable member.

In each embodiment, the movable member 31 is made of nickel with a thickness of 3 μm. However, the material is not limited to this. As the material for the movable part, it is good enough to only have the ability to resist solvent corrosion to the sprayed liquid. If it also has elasticity, it can better function as the movable part.

As the material of the movable member 31, it is preferable to use a metal with a long service life, such as silver, nickel, gold, iron, titanium, aluminum, platinum, tantalum, stainless steel, phosphor bronze or its alloy; a resin of the nitrile group, such as acrylic Nitriles, butadiene, styrene; amide group resins, such as polyamide; carboxyl resins, such as polycarbonate; aldehyde group resins, such as polyacetal; sulfone group resins, such as polysulfone; or liquid crystal polymers, or Other resins and their compounds; metals with strong ink corrosion resistance, such as gold, tungsten, tantalum, nickel, stainless steel, titanium, and their alloys, or coat any of them on the surface to obtain ink corrosion resistance ; Or amide group resins, such as polyamide; aldehyde group resins, such as polyacetal; ketone group resins, such as polyether ketone; imide group resins, such as polyimide; hydroxyl group resins, such as phenol resin Vinyl resins, such as polyethylene; epoxy resins, such as epoxy resins; amino resins, such as ether ammonia resins; methylol group resins, such as xylene resin and its compounds; or ceramics, such as Silicon dioxide, silicon nitride and their compounds. The movable member 31 of the present invention uses a movable member with a thickness of the order of μm to achieve the purpose.

The positional relationship between the heating member and the movable member will be described below. With the optimal setting of the heating part and the movable part, the liquid flow can be appropriately controlled when bubbles are formed by the heating part, and the liquid flow can be effectively utilized.

According to the prior art, the so-called bubble jet recording method is adopted, that is, thermal energy or similar energy is applied to the ink, and the change of its state is accompanied by a drastic ink volume change (bubble generation). Thereafter, the effect based on this state change is used. The ink is discharged from each ink ejection port, making it adhere to the recording medium to form an image. As can be seen from Figure 12, one of the areas S where no bubbles are generated does not contribute to the ink ejection, but it will affect the heating part The performance relationship between area and ink ejection volume. Similarly, it can be understood from the observable heating conditions on the heating elements that the area S that does not participate in generating bubbles is located around each heating element. It is assumed that there is a width of nearly 4 μm around the heating element that does not participate in the generation of bubbles.

Therefore, in order to effectively utilize the pressure of the bubbles, the effective action area of each movable member should be set directly above the effective area where the bubbles are generated, which is located within approximately 4 μm or more of the periphery of the heating member. However, the present invention emphasizes that bubbles should act on the liquid flow in the liquid flow path located on the upstream and downstream sides, almost in the center of the bubble generation area (actually within the range of approximately plus or minus 10 μm from the center to the direction of the liquid flow). Therefore, the bubble generation effect is divided into an independent stage and an overall stage. After that, the most important thing is to design so that the movable member only faces the part located on the upstream side of the aforementioned central area. The effective area for generating bubbles of this embodiment is determined to be within a range of approximately 4 μm or more around the periphery of the heating member. However, the scope is not necessarily limited to this. The determination of this range depends on the type of heating element or its construction method.

Furthermore, in order to better form the aforementioned substantially closed space, it is preferable to set the distance between the movable member and the heating member to 10 μm or less.

(Substrate) The structure of the substrate is described below.

13A and 13B are longitudinal cross-sectional views showing the liquid ejecting head of the present invention. Fig. 13A shows a liquid ejection head with a protective film which will be described later. Figure 13B shows a liquid ejection head without a protective film.

The base plate 1 is provided with a top plate 50 with a plurality of grooves, constituting each liquid flow channel 10, a liquid discharge port 18 communicating with the liquid flow channel 10, a low liquid flow channel resistance area 65 and a common chamber 13.

A silicon oxide film or a silicon nitride film 106 is formed on the substrate 1, and the base 107 is made of silicon or the like for insulation and heat accumulation. On this film, the resistance layer 105 (0.01-0.2μm thick) is made of hafnium boride (HfB2), tantalum nitride (TaN), aluminum tantalum (TaAl) or the like, and the composition is made of aluminum or the like The wire electrode 104 (0.2-1.0 [mu]m thick) is formed so as to form the heating member 2 as shown in FIG. 5A. A voltage is applied to the resistance layer 105 by the wire electrode 104, and energy is applied to it, and heating is performed. A protective layer 103 made of silicon oxide, silicon nitride or the like with a thickness of 0.1-2.0 μm is formed on the resistance layer between the wire electrodes. Furthermore, a thin layer of tantalum or the like is used to form the anti-cavitation layer 102 (0.1-0.6 μm thick) to prevent ink or other liquids from damaging the resistance layer 105.

Specifically, the pressure and shock waves generated when the bubbles are generated and when the bubbles disappear are extremely large, which greatly reduces the service life of the hard but fragile oxide film. Therefore, the anti-cavitation layer 102 is made of a metal material such as tantalum (Ta).

Similarly, a combination of the liquid, the structure of the liquid flow channel, and the resistance material without the protective layer 103 provided in the aforementioned resistance layer 105 can also constitute a certain structure. Such an example is shown in Figure 13B. The material for the resistance layer 105 that does not require any protective layer 103 may be an alloy of iridium-tantalum-aluminum, or other materials.

In this way, the structure of the heating member can be made with only the resistance layer (heating member) between the electrodes. Similarly, it is also possible to provide a protective layer to protect the resistance layer.

Here, each heating part is configured to use a heating part with a resistance layer, and the resistance layer serves as a heating part to provide heat according to an electrical signal, but the heating part is not necessarily limited to this. If the heating element can generate bubbles in the bubble-generating liquid, the heating element is good enough and the bubbles can eject the liquid. For example, it is possible to use a heating member with a light-heat conversion element that generates heat when receiving laser light or other beams, or a heating member with a heating member that generates heat when subjected to high-frequency electric waves.

Here, in the semiconductor manufacturing process, the above-mentioned substrate 1 can be integrally combined with transistors, diodes, latches, shift registers or some other functional elements to selectively drive the electrothermal conversion device, except for the resistance layer 105 as described above. Outside of the device constituting the heating member, the wire electrode 104 provides an electrical signal to the resistive layer.

In order to drive the heating part of the electrothermal conversion device provided on the substrate 1 as described above to eject the liquid, a rectangular pulse as shown in FIG. 14 is applied to the resistance layer 105 through the wire electrodes 104, so that the resistance layer between the wire electrodes 105 is heated sharply. By applying a voltage of 24V to drive the heating element of the inkjet head in each of the foregoing embodiments, the pulse width is approximately 4 μsec, the current is only 100 mA, and the electrical signal is 6 kHz or higher. The ink serves as the liquid discharged from each liquid discharge port through the foregoing operation. However, the condition of the driving signal is not necessarily limited to this. It is good enough if the driving signal only causes the bubble-generating liquid to properly generate bubbles.

(Ejection Liquid) For recording, the aforementioned liquid may employ ink with components that can be used in conventional bubble jet equipment as the liquid (recording liquid) here.

It is also possible to use liquids with low bubble generating ability; liquids whose properties are easily changed or transformed after heating; or high-viscosity liquids that are easily unusable in the traditional sense, such as liquids.

However, as the ejection liquid itself and its performance, it is best to avoid using liquids that will hinder the discharge, generate bubbles, operate the movable member, and the like.

As the ejection liquid for recording, high-viscosity ink or the like can be used. In addition, the present invention performs recording using a recording liquid containing the following components as an example of a suitable ejection liquid: component of pigment ink (viscosity 2cP) (C-1, food black 2) color 3wt % Diethylene Glycol 10wt% Thiodiethylene Glycol 5wt% Ethanol 5wt% Water 77wt% enhances the liquid discharge ability, the ejection speed of the ink is increased, making it possible to obtain excellent recorded images, and at the same time improve the impact of the droplets Accuracy.

(Structure of Liquid Discharge Head) FIG. 15 is an exploded perspective view showing the overall structure of the liquid discharge head of the present invention.

The substrate 1 with a plurality of heating members 2 is provided on a support 70 made of aluminum or the like. The supporting member 34 supporting the movable member 31 is provided so that each movable member faces each half of the heating member 2 on the side of the common chamber 13 respectively. Furthermore, a groove between the top plate 50 and the common chamber 13 is formed, wherein the top plate 50 has a plurality of grooves constituting the liquid flow channel 10.

(Side spray type) The side spray type liquid discharge head will be briefly described below with reference to the attached drawings 1A-1F to 5A-5F. The heating part and the liquid discharge port of the liquid discharge head face each other on parallel surfaces and discharge liquid to the liquid discharge head. The head applies ejection liquid. 16A and 16B are views showing the side spray liquid discharge head.

In FIGS. 16A and 16B, the heating member 2 provided on the base plate 1 and the liquid discharge port 18 provided on the top plate 50 are opposed to each other. Each liquid discharge port 18 communicates with the liquid flow channel 10 on the path heating component 2. In the vicinity of the surface area where the liquid and the heating member 2 contact, there is a bubble generation area. Two movable parts 31 are supported on the base plate 1, and each movable part 31 is in a plane symmetrical to the surface passing through the center of the heating part. The free ends of the movable member 31 are opposed to each other on the heating member. Each movable member 31 has the same projected area on the heating member 2, and the free ends of each movable member 31 are separated from each other by a certain distance. Here, if it is assumed that each movable member is separated by a partition wall passing through the central portion of the heating member, the free end of each movable member is located near the center of the heating member, respectively.

Each stopper 64 is provided for the top plate 50 to limit the movement of each movable member 31 within a certain range. In the liquid flow from the common chamber 13 to the discharge port 18, a low liquid flow path resistance area 65 having a lower liquid flow path resistance than the liquid flow path 10 is provided on the upstream side, and a stopper 64 is used as World. In this area 65, the structure of the liquid flow channel includes a liquid flow channel cross section wider than that of the liquid flow channel 10, so that when the liquid moves, the resistance of the liquid from the liquid flow channel is reduced.

The specific functions and structural effects of this embodiment are described below.

FIG. 16A shows a state where a part of the liquid filled in the bubble generation region 11 is heated by the heating member 2 and the bubble 40 grows to the maximum along with the film boiling. At this time, using the pressure formed by the bubble 40, the liquid in the liquid flow channel 10 moves in the direction toward the liquid discharge port 18. The growth of the bubble 40 causes each movable member 31 to move, prompting the ejected liquid droplet 66 to be ready to fly.Outlet18. Out of the drain 18. Here, with each low liquid flow path resistance zone 65, the liquid moving in the direction toward the common chamber 13 becomes a larger liquid flow. However, when the two movable parts 31 are moved to approach or come into contact with each stopper 64, their further movement is restricted. Thereafter, the movement of the liquid in the direction toward the common chamber 13 is also greatly restricted. At the same time, the growth of the bubble 40 to the upstream side is also restricted by the movable member 31. However, since the moving force of the liquid to the upstream side is great, the growth of a part of the bubbles 40 is restricted by each movable member 31, and the part of the bubbles 40 passes through the side wall of the liquid flow channel 10 and the side portion of the movable member 31. The gap therebetween overflows to the upper surface side of the movable member 31. In other words, overflow bubbles 41 are formed here.

When the film boils and the bubble 40 begins to shrink, the liquid force directed in the upstream direction still remains large. Each movable member 31 is still in contact with the stopper 64. Therefore, almost all of the contracted bubbles 40 are used to move the liquid from the liquid discharge port 18 to the upstream side. At the same time, the meniscus-shaped liquid surface is deeply sucked into the liquid flow channel 10 from the liquid discharge port 18, and the liquid column connected to the discharged liquid droplet 66 is quickly cut off with a large force. Therefore, the droplets remaining on the outside of the liquid discharge port 18, that is, the satellite points, become smaller.

When the bubble disappearing process is basically over, in each low liquid flow channel resistance zone 65, the elasticity (restoring force) of each movable member 31 overcomes the moving trend of the liquid flow in the upstream direction, and the direction of each movable member 31 The downward movement starts, and thereafter, along with the above movement, the movement of the liquid flow in the downstream direction in the low liquid flow path resistance region 65 also starts. Since in the low liquid flow path resistance zone 65, the flow path resistance when flowing in the downstream direction is small, the liquid flow quickly becomes a larger liquid flow, which flows into the liquid flow channel 10 through each stopper 64. . Fig. 16B shows the liquid flow during the disappearance of the bubble 40, as indicated by the symbols A and B. The liquid flow A represents a partial flow that flows from the common chamber 13 through the upper side (the surface opposite to the heating member) of the movable member 31 in the direction toward the liquid discharge port 18. The liquid flow B represents the divided flow flowing through the two sides of the movable member 31 and on the heating element 2.

As described above, the ejection liquid of this embodiment is supplied from the low liquid flow path resistance area 65 in order to increase the liquid refilling speed. At the same time, the common chamber 13 located next to each low liquid flow channel resistance area 65 is still provided to reduce the liquid flow channel resistance, thereby realizing higher-speed refilling.

During the disappearance of the bubble 40, the overflowing bubble 41 causes the liquid flow to flow from each low liquid flow channel resistance area 65 to the bubble generation area 11. Then, as described above, the bubble disappearing process is quickly completed, and the meniscus-shaped liquid surface is sucked back from the liquid discharge port 18 side at a high speed. Specifically, due to each overflow bubble 41, it is almost impossible for the bubble to stay on the movable member 31 or in the corner of the liquid flow channel 10 under the action of the liquid flow.

(Liquid Discharge Device) Fig. 17 is a schematic diagram showing the structure of a liquid discharge device with the liquid ejection head described in conjunction with Figs. 1A-1F and Figs. 16A and 16B. Specifically, this embodiment will describe an inkjet recording apparatus that uses ink as the ejection liquid. The carriage HC of the liquid discharging device is mounted on it, and the liquid tank 90 containing the ink and the liquid jet head 200 are detachably mounted on the ink jet head box. The carriage can reciprocate in the width direction of a recording medium 150, such as a sheet of recording paper, which is carried on a member that supports the recording medium.

When a drive signal supply member (not shown) sends a drive signal to the liquid discharge device on the carriage, the recording liquid is ejected from the liquid ejection head to the recording medium in accordance with the drive signal.

The liquid discharge device of this embodiment is provided with a motor 111 serving as a driving source to drive the recording medium support member and the carriage; gears 112 and 113 that transmit the driving force from the driving source to the carriage; a carriage shaft 115 and the like. By adopting the recording device and the liquid discharge method suitable for the recording device, it is possible to obtain high-quality images of the recorded object by ejecting the liquid on various recording media.

Fig. 18 is a block diagram of the main body of an apparatus for performing inkjet recording using the liquid discharge method and liquid ejection head of the present invention.

The recording device receives printing information from the host 300 as a control signal. The printing information is temporarily stored in the input interface 301 inside the printing device, and at the same time converted into data that can be processed by the recording device, and then input to the CPU 302, which also serves as a device for providing driving signals to the liquid jet head. The CPU 302 uses the RAM 304 and other peripheral devices to process the data input to the CPU 302 according to the control program stored in the ROM 303, thereby converting it into data (image data) for printing.

The CPU 302 also generates drive data for driving a drive motor. In order to record image data on an appropriate position on the recording medium, the drive motor moves the recording medium and the recording head in synchronization with the image data. The image data and the driving data of the motor are transmitted to the inkjet head 200 and the driving motor 306 through the inkjet head driver 307 and the motor driver 305, so as to drive the inkjet head and the motor at a controlled time to form an image.

The recording medium suitable for the aforementioned recording device to attach ink or other liquid to it includes various types of paper and OHP thin layers, plastic materials, fabrics, aluminum, copper or some other metal materials, leather materials that can be used for high-density discs and decorative plates For example, cowhide, pigskin or artificial leather, wooden materials, such as wood, synthetic boards, bamboo, ceramic materials, such as tiles, and sponges or other three-dimensional structures.

Among the aforementioned recording devices, there are recording devices for recording on various types of paper and OHP thin layers or the like; there are recording devices for plastic recording on plastic materials, such as high-density disks; and there are recording devices for recording on metals and metal disks. Devices; there are recording devices used for leather recording on leather; there are recording devices used for wood recording on wood; there are recording devices used for ceramics recording on ceramic materials; and on sponges or other three-dimensional nets Recording device for recording. The fabric printing device here includes recording on cloth or the like.

The ejection liquid used in each of the above-mentioned liquid discharge devices should meet the requirements of use, that is, the liquid is suitable for the respective recording medium and recording conditions.