Nozzle plate, liquid jetting head and liquid jetting device

The present invention relates to a nozzle plate having a liquid repellent treatment on its surface, a liquid injection head, and a liquid injection device.

The liquid injection device is a device provided with a liquid injection head and injects various liquids from a nozzle provided in a nozzle plate of the liquid injection head. Examples of this liquid injection device include image recording devices such as an inkjet printer and an inkjet plotter, but recently, various types of liquid injection devices have been manufactured by taking advantage of the feature that a very small amount of liquid can be accurately landed at a predetermined position. It is also applied to devices. For example, a display manufacturing device that manufactures color filters such as liquid crystal displays, an electrode forming device that forms electrodes such as an organic EL (Electro Luminescence) display and a FED (field emission display), and a chip that manufactures a biochip (biochemical element). It is applied to manufacturing equipment. Then, the recording head for the image recording device injects liquid ink, and the color material injection head for the display manufacturing device injects a solution of each color material of R (Red), G (Green), and B (Blue). Further, the electrode material injection head for the electrode forming apparatus injects a liquid electrode material, and the bioorganic material injection head for the chip manufacturing apparatus injects a solution of the bioorganic substance.

In such a liquid injection device, a part of the droplets ejected from the nozzle may adhere to the surface of the nozzle plate (specifically, the surface on the side where the droplets are ejected). In particular, if the liquid adheres to the vicinity of the nozzle, it may interfere with the droplets ejected from the nozzle and cause problems such as bending of the flight direction of the droplets. In order to suppress such a defect, a liquid injection head having a liquid repellent film formed on the surface of the nozzle plate is disclosed (see Patent Document 1).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2014-124874</text></patcit></p>

<p> By the way, the liquid injection device is provided with a wiping member (for example, a wiper or the like) that wipes the surface of the nozzle plate in order to remove ink, dust, and the like adhering to the surface of the nozzle plate. The wiping operation by the wiping member may wear the liquid repellent film on the surface of the nozzle plate, and the liquid repellent property on the surface of the nozzle plate may decrease. In particular, when the liquid ejected from the nozzle contains a pigment such as titanium oxide, this pigment acts like an abrasive, and the liquid-repellent film is more easily worn.</p><p> The present invention has been made in view of such circumstances, and an object of the present invention is to provide a nozzle plate, a liquid injection head, and a liquid injection device in which deterioration of liquid repellency is suppressed.</p>

<p> The nozzle plate of the present invention has been proposed in order to achieve the above object, and is a nozzle plate in which a nozzle for ejecting a liquid is opened on one surface side, and the DLC layer is the one surface. The surface of the DLC layer formed on the side has a concave-convex shape composed of concave portions and convex portions, and the end portion of the adjacent convex portion on the side where the liquid contacts intersects with the one surface. It is characterized in that the position is different in the direction of the nozzle.</p><p> According to this configuration, the uneven shape of the surface of the DLC layer can impart liquid repellency to one surface of the nozzle plate. That is, the lotus effect can improve the liquid repellency on one surface of the nozzle plate. In addition, as a liquid-repellent layer that imparts liquid-repellency to the nozzle plate, a DLC layer with excellent abrasion resistance (in other words, durability) is used, so deterioration of the liquid-repellent property on one surface of the nozzle plate is suppressed. it can.</p><p> In the above configuration, it is desirable that the uneven shape of the DLC layer is formed by arranging a plurality of particles having different sizes.</p><p> According to this configuration, an uneven shape can be easily formed on the DLC layer.</p><p> Further, in any of the above configurations, it is desirable that the DLC layer contains fluorine.</p><p> According to this configuration, the liquid repellency on one surface of the nozzle plate can be further improved.</p><p> Further, in any of the above configurations, it is desirable that the arithmetic mean roughness Ra of the surface of the DLC layer is 1 [μm] or less.</p><p> According to this configuration, the liquid repellency on one surface of the nozzle plate can be further improved.</p><p> Further, in any of the above configurations, it is desirable that the amorphous layer is formed on the one surface side and the DLC layer is laminated on the amorphous layer.</p><p> According to this configuration, the adhesion of the DLC layer to the nozzle plate can be improved. As a result, deterioration of liquid repellency due to peeling of the DLC layer can be suppressed.</p><p> The liquid injection head of the present invention is characterized by including a nozzle plate having any of the above configurations.</p><p> According to this configuration, the reliability of the liquid injection head can be improved because the nozzle plate is provided with high durability.</p><p> Further, the liquid injection device of the present invention is characterized by including the liquid injection head having the above configuration.</p><p> According to this configuration, the reliability of the liquid injection device can be improved.</p>

<figref num="1">It is a perspective view explaining the structure of a printer.</figref><figref num="2">It is sectional drawing of the main part explaining the structure of a recording head.</figref><figref num="3">It is a schematic diagram which enlarged the cross section of a nozzle plate.</figref><figref num="4">It is a graph which shows the relationship between the surface roughness and the contact angle.</figref><figref num="5">It is a schematic diagram explaining the manufacturing method of a DLC layer.</figref><figref num="6">It is a schematic diagram which enlarged the cross section of the nozzle plate in 2nd Embodiment.</figref>

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are given as suitable specific examples of the present invention, but the scope of the present invention is the scope of the present invention unless otherwise specified in the following description to limit the present invention. It is not limited to these aspects. In the following, as a kind of liquid injection head, an inkjet recording head (hereinafter, recording head) 3 mounted on an inkjet printer (hereinafter, printer) 1 which is a kind of liquid injection device will be described as an example. To do.

FIG. 1 is a perspective view of the printer 1. The printer 1 is a device that records an image or the like by injecting ink (a type of liquid) onto the surface of a recording medium 2 (a type of landing target) such as recording paper. The printer 1 includes a recording head 3, a carriage 4 to which the recording head 3 is attached, a carriage moving mechanism 5 for moving the carriage 4 in the main scanning direction, a transport mechanism 6 for transferring the recording medium 2 in the sub scanning direction, and the like. There is. Here, the above ink is stored in the ink cartridge 7 as a liquid supply source. The ink cartridge 7 is detachably attached to the recording head 3. It is also possible to adopt a configuration in which the ink cartridge is arranged on the main body side of the printer and is supplied from the ink cartridge to the recording head through the ink supply tube.

The carriage moving mechanism 5 described above includes a timing belt 8. The timing belt 8 is driven by a pulse motor 9 such as a DC motor. Therefore, when the pulse motor 9 is operated, the carriage 4 is guided by the guide rod 10 installed on the printer 1 and reciprocates in the main scanning direction (the width direction of the recording medium 2). The position of the carriage 4 in the main scanning direction is detected by a linear encoder (not shown) which is a kind of position information detecting means. The linear encoder transmits the detection signal, that is, an encoder pulse (a kind of position information) to the control unit of the printer 1.

The home position, which is the standby position of the recording head 3, is set at a position deviated from one end side (right side in FIG. 1) in the main scanning direction with respect to the area (or printing area) where the recording medium 2 is conveyed. ing. A cap 11 and a wiper 12 are provided at this home position. The cap 11 is a member made of, for example, an elastic body that seals the nozzle surface 23 (described later) of the recording head 3 that stands by at the home position. The wiper 12 is a member that wipes the nozzle surface 23 of the recording head 3 that stands by at the home position. The wiper 12 in the present embodiment is made of an elastic body such as an elastomer and is formed in a blade shape. As the wiper 12, a sheet-like member made of cloth such as cotton or silk can also be used.

Next, the recording head 3 will be described. FIG. 2 is a cross-sectional view of a main part for explaining the configuration of the recording head 3. FIG. 3 is a schematic view of an enlarged cross section of the nozzle plate 21. Since the configuration of the recording head 3 is generally symmetrical in the direction orthogonal to the nozzle row direction, only one configuration is shown in FIG. Further, in FIG. 3, contrary to FIG. 2, the nozzle surface 23 is shown to be upward. Further, in the following description, for convenience, the head case 16 side will be referred to as an upper side (or upper side), and the nozzle surface 23 side will be described as a lower side (or a lower side). As shown in FIG. 2, the recording head 3 in the present embodiment is attached to the head case 16 in a state where the actuator unit 14 and the flow path unit 15 are stacked.

The head case 16 is a box-shaped member made of synthetic resin, and a liquid introduction path 18 for supplying ink to each pressure chamber 30 is formed inside the head case 16. The liquid introduction path 18 is a space in which ink common to a plurality of pressure chambers 30 is stored together with the common liquid chamber 25 described later. In the present embodiment, two liquid introduction paths 18 are formed corresponding to the rows of the pressure chambers 30 arranged side by side in the two rows. Further, in the lower part (flow path unit 15 side) of the head case 16, a rectangular parallelepiped shape is recessed from the lower surface of the head case 16 (the surface on the flow path unit 15 side) to the middle of the height direction of the head case 16. However, a containment space 17 is formed. When the flow path unit 15 is joined in a state of being positioned on the lower surface of the head case 16, the actuator unit 14 laminated on the communication board 24, which will be described later, is accommodated in the accommodation space 17. Further, an insertion opening 19 for communicating the space outside the head case 16 and the accommodation space 17 is provided on a part of the ceiling surface of the accommodation space 17. A wiring board such as an FPC (flexible printed circuit board) (not shown) is inserted into the accommodation space 17 through the insertion opening 19 and connected to the actuator unit 14 in the accommodation space 17.

The flow path unit 15 in the present embodiment has a communication board 24 and a nozzle plate 21. The nozzle plate 21 is a silicon substrate (for example, a silicon single crystal substrate) bonded to the lower surface of the communication substrate 24 (the surface opposite to the pressure chamber forming substrate 29). In the present embodiment, the nozzle plate 21 seals the opening on the lower surface side of the space serving as the common liquid chamber 25, which will be described later. Further, a plurality of nozzles 22 are provided in a straight line (row) on the nozzle plate 21. Two rows of nozzles 22 (that is, nozzle rows) composed of the plurality of nozzles 22 are formed on the nozzle plate 21. The nozzles 22 constituting each nozzle row are provided from the nozzle 22 on one end side to the nozzle 22 on the other end side at a pitch corresponding to the dot formation density, for example, at equal intervals along the main scanning direction. The nozzle plate is joined to a region of the communicating substrate that is out of the common liquid chamber inward, and the opening on the lower surface side of the space that becomes the common liquid chamber is sealed with a member such as a flexible compliance sheet. You can also. Further, in the following description, the outer surface of the nozzle plate 21 through which the nozzle 22 opens (the lower surface in FIG. 2, corresponding to one surface in the present invention) is referred to as a nozzle surface 23.

As shown in FIG. 3, on the surface of the nozzle plate 21 in this embodiment, for example, a thermal oxide film (SiO)₂) And a base layer 39 composed of a tantalum oxide film (TaOx) and a tantalum nitride film (TaN) laminated thereto. The base layer 39 is a layer that has ink resistance and protects the surface of the nozzle plate 21. The base layer 39 can protect the nozzle surface 23 of the nozzle plate 21 even if defects such as pinholes and cracks occur in a part of the DLC layer 40. The base layer 39 may have a single-layer structure composed of one layer, or may have a laminated structure in which a plurality of layers are laminated. When it is composed of a plurality of layers, the outermost layer may be configured to have ink resistance. Further, the base layer 39 is also formed on the inner surface of the nozzle 22 and the surface opposite to the nozzle surface 23.

A DLC (diamond-like carbon) layer 40 is laminated as a liquid-repellent layer having liquid-repellent properties on the surface of the base layer 39 (one surface side of the nozzle plate 21) on the nozzle surface 23. In the present embodiment, the DLC layer 40 is formed on the entire surface of the nozzle surface 23. As shown in FIG. 3, the DLC layer 40 is formed in a state in which a plurality of columnar particles 41 are arranged side by side. The columnar particles 41 are made of, for example, microcrystalline diamond or DLC having a size of several tens [nm] to several [μm], and are irregularly and densely arranged on the nozzle surface 23. Then, the particles 41 form a minute uneven shape on the surface of the DLC layer 40. That is, the particles 41 form the convex portion 49 having an uneven shape, and the concave portion 50 having an uneven shape is formed between the particles. Here, the tip end portion (the end portion on the side where the ink contacts) of the particle 41 (convex portion 49) is configured to have a tapered shape toward the direction intersecting one surface (in other words, the height direction). ing. Therefore, the concave portion 50 is formed between a surface inclined obliquely from the tip of the convex portion 49 and a surface obliquely inclined from the tip of the convex portion 49 adjacent thereto. That is, the concave portion 50 is formed so as to expand toward the tip end side in the height direction of the convex portion 49. Further, the individual particles 41 are formed to have different sizes. Therefore, the tip portions of the adjacent convex portions 49 are formed so that their positions are different in the height direction.

By forming the concave-convex shape on the nozzle surface 23 in this way, it is possible to impart liquid repellency to the nozzle surface 23 by the Lotus effect. That is, by giving the nozzle surface 23 an uneven shape, it is possible to impart liquid repellency on the same principle that the surface of the lotus leaf repels water. Further, since the tip of the convex portion 49 is tapered, the contact area of the ink (liquid) in the convex portion 49 can be reduced, and the ink (liquid) comes into contact with the convex portion 49 in a state close to point contact. .. Thereby, the liquid repellency on the nozzle surface 23 can be further improved. Further, since the heights of the adjacent convex portions 49 are different, the distance between the tips of the adjacent convex portions 49 can be increased as compared with the case where the heights of the adjacent convex portions are the same. That is, the position where the ink comes into contact can be expanded. As a result, the liquid repellency can be further improved. Then, by forming the DLC layer 40 in a state in which a plurality of columnar particles 41 are arranged side by side, the DLC layer 40 having liquid repellency can be easily formed. The method of forming the DLC layer 40 on the nozzle surface 23 will be described in detail later.

Here, the liquid repellency (degree of liquid repellency) changes according to the uneven shape of the surface of the DLC layer 40, that is, the roughness. FIG. 4 is a graph showing the relationship between the surface roughness of the DLC layer 40 (arithmetic mean roughness Ra [μm]) and the contact angle (contact angle with respect to pure water [°]). From this graph, it can be seen that the smaller the Ra, the larger the contact angle. In particular, when Ra is 1 [μm], the contact angle is about 95 [°]. In a general printer, the contact angle on the nozzle surface 23 is required to be 90 [°] or more, so it is desirable to configure the DLC layer 40 so that the Ra on the surface is 1 [μm] or less. In this embodiment, the DLC layer 40 is formed so that Ra on the surface is about 0.08 [μm] (that is, 80 [nm]). Therefore, the nozzle surface 23 in the present embodiment has a contact angle of about 110 [°]. Further, the DLC layer 40 in the present embodiment is formed to have a thickness (film thickness) of about 200 to 300 [nm].

As shown in FIG. 2, the communication board 24 is a silicon board that constitutes the upper part (the portion on the head case 16 side) of the flow path unit 15. The communication substrate 24 communicates with the liquid introduction path 18 and stores ink common to each pressure chamber 30. A common liquid chamber 25 and ink from the liquid introduction path 18 pass through the common liquid chamber 25. The individual communication passages 26 that are individually supplied to the pressure chamber 30 and the nozzle communication passages 27 that communicate the pressure chamber 30 and the nozzle 22 are formed by anisotropic etching or the like. The common liquid chamber 25 is a long empty space along the nozzle row direction, and is formed in two rows corresponding to the rows of pressure chambers 30 arranged side by side in the two rows. Further, a plurality of individual passages 26 and nozzle passages 27 are formed along the nozzle row direction.

As shown in FIG. 2, the actuator unit 14 in the present embodiment is unitized by laminating a pressure chamber forming substrate 29, a diaphragm 31, a piezoelectric element 32 which is a kind of actuator, and a sealing plate 33. It is joined to the communication board 24. The actuator unit 14 is formed smaller than the accommodation space 17 so that it can be accommodated in the accommodation space 17.

The pressure chamber forming substrate 29 is a silicon substrate (for example, a silicon single crystal substrate) that constitutes a lower portion (a portion on the flow path unit 15 side) of the actuator unit 14. A part of the pressure chamber forming substrate 29 is removed in the plate thickness direction by anisotropic etching, and a plurality of spaces to be the pressure chamber 30 are arranged side by side along the nozzle row direction. The lower part of this space is partitioned by the communication board 24, and the upper part is partitioned by the diaphragm 31 to form the pressure chamber 30. Further, this space, that is, the pressure chamber 30, is formed in two rows corresponding to the nozzle rows formed in two rows. Each pressure chamber 30 is an empty portion that is long in the direction orthogonal to the nozzle row direction, and the individual communication passage 26 communicates with one end in the longitudinal direction, and the nozzle communication passage 27 communicates with the other end. Communicate.

The diaphragm 31 is, for example, silicon dioxide (SiO) formed on the upper surface of the pressure chamber forming substrate 29.₂) And zirconium oxide (ZrO) formed on this elastic film.₂), And an insulator film. The region corresponding to each pressure chamber 30 in the diaphragm 31 is a drive region 35 in which bending deformation is allowed, and the piezoelectric element 32 is laminated. The piezoelectric element 32 in the present embodiment is a so-called bending mode piezoelectric element. The piezoelectric element 32 is formed by, for example, sequentially laminating a lower electrode layer, a piezoelectric layer, and an upper electrode layer on a diaphragm 31. Either one of the upper electrode film and the lower electrode film is a common electrode commonly formed on each piezoelectric element 32, and the other is an individual electrode individually formed on each piezoelectric element 32. Then, when an electric field corresponding to the potential difference between the two electrodes is applied between the lower electrode layer and the upper electrode layer, the piezoelectric element 32 bends and deforms in a direction away from or close to the nozzle 22. As a result, the volume of the pressure chamber 30 changes, and the ink in the pressure chamber 30 changes in pressure. Then, by utilizing this pressure fluctuation, the ink in the pressure chamber 30 can be ejected from the nozzle 22. The piezoelectric elements 32 in the present embodiment are formed in two rows along the nozzle row direction, corresponding to the pressure chambers 30 arranged in two rows along the nozzle row direction.

As shown in FIG. 2, the sealing plate 33 is a substrate made of silicon single crystal, metal, synthetic resin, or the like bonded to the upper surface of the pressure chamber forming substrate 29 (specifically, the upper surface of the diaphragm 31). .. On the lower surface of the sealing plate 33, a piezoelectric element accommodating space 36 recessed from the lower surface of the sealing plate 33 to the middle of the sealing plate 33 in the plate thickness direction is formed. A row of piezoelectric elements 32 is accommodated in the piezoelectric element accommodating space 36. In the present embodiment, the piezoelectric element accommodating space 36 is formed in two rows corresponding to the rows of the piezoelectric elements 32 formed in two rows. An opening is formed in the portion between the two piezoelectric element accommodating spaces 36 through which the sealing plate 33 is penetrated in the plate thickness direction. In this opening, the terminal of the wiring board inserted through the insertion opening 19 and the terminal of the wiring extending from the piezoelectric element 32 are connected.

Next, a method of manufacturing the recording head 3, particularly a method of manufacturing the nozzle plate 21, will be described in detail. In this embodiment, a method of forming the DLC layer 40 on the substrate 42 (for example, a silicon wafer) to be the nozzle plate 21 and then dividing the DLC layer 40 into individual nozzle plates 21 will be exemplified. FIG. 5 is a schematic view of a cross section of the nozzle plate 21 (board 42) for explaining the film forming method of the DLC layer 40 (plasma ion implantation method in this embodiment).

First, the nozzle 22 is formed at a predetermined position on the substrate 42 to be the nozzle plate 21. The nozzle 22 is formed in a state of penetrating the nozzle plate 21 by, for example, a laser or a Bosch method. Next, the base layer 39 is formed on the surface of the substrate 42. The base layer 39 is formed on the surface of the nozzle plate 21 by thermal oxidation, for example, with a thermal oxide film (SiO).₂) Is formed, and then a layer such as a tantalum oxide film (TaOx) is formed by a sputtering method, an ALD method (atomic layer deposition method), a chemical vapor deposition method, a vacuum vapor deposition method, or the like.

After the base layer 39 is formed on the nozzle plate 21, the DLC layer 40 is formed by using the plasma ion implantation method as shown in FIG. In the plasma ion implantation method, a gas plasma P is generated in a chamber (container) by an RF (high frequency) power source (not shown), and a high voltage pulse bias is applied to a substrate 42 arranged in the chamber by a pulse power source 44, for example, a number. It is a method of accelerating the ions in the plasma P by applying it in a period of tens to several hundreds of microseconds. As a result, the substrate 42 is repeatedly irradiated with high-energy ions in a short time (see the arrow in FIG. 5), and the DLC layer 40 is formed on the substrate 42. In this embodiment, acetylene (C) is used as the process gas.₂H₂) And methane (CH₄) Etc. were introduced into the chamber at a flow rate of 40 [sccm], and the gas pressure in the chamber was adjusted to 1 [Pa]. In addition, plasma was generated inside the chamber by applying high-frequency power with a frequency of 13.56 [MHz] through a circuit installed inside the chamber. Further, a pulse bias having a negative electrode bias peak voltage of -5 [KV] and a frequency of 4000 [Hz] was applied to the substrate 42 by the pulse power supply 44. Then, in the present invention, the above plasma ion implantation method was performed with the substrate 42 heated by a heating mechanism such as a heater (not shown).

Here, the configuration of the layer formed on the substrate 42 can be changed by changing the temperature of the substrate 42 in the plasma ion implantation method. Specifically, when the temperature of the substrate 42 is 200 ° C. or lower, an amorphous single layer is formed on the substrate 42. Further, when the temperature of the substrate 42 is 300 ° C., a layer of DLC is formed on the substrate 42. This DLC layer is composed of a plurality of columnar particles 41 made of microcrystalline diamond or DLC arranged side by side. That is, on the surface of the DLC layer formed on the substrate 42, fine uneven shapes (convex portion 49 and concave portion 50) due to the columnar particles 41 are formed. As described above, when the temperature of the substrate 42 is higher than 300 ° C., crystals or the like grow in columns from the surface of the substrate 42, and a layer of DLC having an uneven shape is formed. Then, as the temperature of the substrate 42 rises from 300 ° C., the size of the columnar particles 41 formed on the substrate 42 becomes smaller, and the uneven shape of the surface becomes smaller. That is, the higher the temperature of the substrate 42 in the plasma ion implantation method, the smaller the Ra on the surface of the DLC layer 40 formed on the substrate 42. In the present embodiment, the temperature of the substrate 42 in the plasma ion implantation method is set to 400 ° C., and a DLC layer is formed on the substrate 42. As a result, the DLC layer 40 having Ra on the surface of about 0.08 [μm] is formed.

When the DLC layer 40 is formed on the substrate 42 by the above method, it is divided into individual nozzle plates 21 by a cutter or the like. As a result, the nozzle plate 21 in which the DLC layer 40 is formed on the nozzle surface 23 is produced. After that, the divided nozzle plate 21 is joined to the lower surface of the communication board 24, and the actuator unit 14 is joined to the upper surface of the communication board 24. Then, the recording head 3 is created by attaching the head case 16 to the communication board 24 so that the actuator unit 14 is accommodated in the accommodation space 17.

As described above, by using the plasma ion implantation method, the nozzle plate 21 in which the DLC layer 40 having an uneven shape on the surface is formed can be easily manufactured. As a result, liquid repellency can be imparted to the nozzle surface 23 of the nozzle plate 21. That is, the lotus effect can improve the liquid repellency on the nozzle surface 23 of the nozzle plate 21. Further, since the layer (liquid repellent layer) that imparts liquid repellency to the nozzle plate 21 is the DLC layer 40 having excellent abrasion resistance (in other words, durability), the liquid repellency on the nozzle surface 23 of the nozzle plate 21 is used. Deterioration of sex can be suppressed. As a result, the durability of the nozzle plate 21 against the wiping operation by the wiper 12 is improved, and the reliability of the recording head 3 and the printer 1 is improved. Further, by adjusting the temperature of the substrate 42 in the plasma ion implantation method, the surface roughness of the DLC layer 40 can be adjusted, and the degree of liquid repellency (specifically, the contact angle with respect to ink) on the surface of the nozzle plate 21 can be adjusted. Can be adjusted. In the present embodiment, since the surface of the DLC layer 40 is formed so that the arithmetic mean roughness Ra is 1 [μm] or less, the liquid repellency on the nozzle surface 23 of the nozzle plate 21 can be further improved. ..

By the way, in the first embodiment described above, the DLC layer 40 is laminated on the nozzle surface 23 of the nozzle plate 21, but the present invention is not limited to this. In the nozzle plate 21 of the second embodiment shown in FIG. 6, an amorphous layer 46 is formed on the nozzle surface 23, and a DLC layer 47 is laminated on the amorphous layer 46. Specifically, as in the first embodiment described above, the base layer 39 is formed on the surface of the nozzle plate 21. Then, the amorphous layer 46 and the DLC layer 47 are laminated in this order on the surface of the base layer 39 on the nozzle surface 23. The amorphous layer 46 is an amorphous layer different from DLC and has substantially the same composition as the DLC layer 47. Since the DLC layer 47 has the same configuration as that of the first embodiment described above, the description thereof will be omitted. In the present embodiment, the amorphous layer 46 is formed to a thickness (thickness) of about 100 to 300 [nm], and the DLC layer 47 is formed to a thickness (thickness) of about 200 to 300 [nm]. There is. By arranging the amorphous layer 46 between the nozzle surface 23 and the DLC layer 47 in this way, the amorphous layer 46 can function as a buffer film. That is, since the amorphous layer 46 is softer than the DLC layer 47, it can absorb an impact from the outside. Further, since the amorphous layer 46 and the DLC layer 47 have substantially the same composition, the DLC layer 47 easily adheres to the amorphous layer 46. That is, the adhesion of the DLC layer 47 to the nozzle plate can be improved. As a result, it is possible to suppress a decrease (deterioration) in liquid repellency due to peeling or falling off of a part of the DLC layer 47 (particles 41 and the like constituting the DLC layer 47). Since the other configurations are the same as those in the first embodiment described above, the description thereof will be omitted.

Such a method of manufacturing the nozzle plate 21 will be described. First, the nozzle 22 and the base layer 39 are formed on the substrate 42 (nozzle plate 21) in the same manner as in the first embodiment described above. Next, the amorphous layer 46 is laminated on the base layer 39. Here, the amorphous layer 46 can be created by adjusting the temperature of the substrate 42 in the plasma ion implantation method. Specifically, the temperature of the substrate 42 in the plasma ion implantation method is set to 200 ° C., and the other film-forming conditions are the same as the film-forming conditions of the DLC layer 40 in the first embodiment. .. As a result, the amorphous layer 46 is formed on the surface of the substrate 42. Then, the DLC layer 47 is formed by the plasma ion implantation method under the film forming conditions of the DLC layer 40 in the first embodiment. As a result, the DLC layer 47 having a Ra on the surface of about 0.08 [μm] is laminated on the amorphous layer 46. It is also possible to change the film forming conditions so that the amorphous layer 46 is a layer in which graphene is formed into a film.

The DLC layer 40 and the DLC layer 47 in each of the above-described embodiments are not limited to the DLC layer composed only of carbon. It may contain hydrogen or fluorine. In particular, by incorporating fluorine into the DLC layer 40 and the DLC layer 47, it is possible to further improve the liquid repellency on the nozzle surface 23 of the nozzle plate 21. For example, by forming the DLC layer 40 and the DLC layer 47 into an F-DLC (fluorine-containing diamond-like carbon) layer containing 0.5 to 30 [atomic%] of fluorine, the liquid repellency is higher than that of the fluorine-free DLC layer. Can be improved. Even in this case, it is desirable that the surfaces of the DLC layer 40 and the DLC layer 47 (that is, the F-DLC layer) are formed so that the arithmetic mean roughness Ra is 1 [μm] or less. Further, as a method of incorporating fluorine into the DLC layer 40 and the DLC layer 47, for example, in the plasma ion implantation method, a gas containing a fluorine component (fluorine atom) in the gas introduced into the chamber (for example, carbon tetrafluoride gas). (CF₄)) Is made possible.

By the way, in each of the above-described embodiments, the nozzle plate 21 made of silicon has been illustrated, but the present invention is not limited to this. For example, a metal nozzle plate can be adopted. Further, when the nozzle plate itself has ink resistance, the underlying layer on the surface of the nozzle plate can be eliminated. In this case, a DLC layer or an amorphous layer is laminated on the surface of the nozzle plate. Further, in each of the above-described embodiments, a so-called bending vibration type piezoelectric element has been exemplified as a driving element that causes pressure fluctuation in the ink in the pressure chamber 30, but the present invention is not limited to this. For example, various actuators such as a so-called longitudinal vibration type piezoelectric element, a heat generating element, and an electrostatic actuator that fluctuates the volume of the pressure chamber by using electrostatic force can be adopted.

In the above description, as the liquid injection device, an inkjet printer 1 provided with an inkjet recording head 3 which is a kind of liquid injection head has been described as an example, but the present invention includes another liquid injection head. It can also be applied to a liquid injection device. For example, a liquid injection device equipped with a color material injection head used for manufacturing a color filter such as a liquid crystal display, an electrode material injection head used for electrode formation of an organic EL (Electro Luminescence) display, a FED (surface emitting display), etc. The present invention can also be applied to a liquid injection device provided, a liquid injection device provided with a bioorganic substance injection head used for manufacturing a biochip (biochemical element), and the like. The color material injection head for display manufacturing equipment injects a solution of each color material of R (Red), G (Green), and B (Blue) as a kind of liquid. Further, the electrode material injection head for the electrode forming apparatus injects a liquid electrode material as a kind of liquid, and the bioorganic matter injection head for a chip manufacturing apparatus injects a solution of a bioorganic substance as a kind of liquid.

1 ... printer, 2 ... recording medium, 3 ... recording head, 4 ... carriage, 5 ... carriage moving mechanism, 6 ... transport mechanism, 7 ... ink cartridge, 8. .. Timing Belt, 9 ... Pulse Motor, 10 ... Guide Rod, 11 ... Cap, 12 ... Wiper, 14 ... Actuator Unit, 15 ... Flow Unit, 16 ... Head case, 17 ... containment space, 18 ... liquid inlet, 19 ... insertion opening, 21 ... nozzle plate, 22 ... nozzle, 23 ... nozzle surface, 24 ... communication Substrate, 25 ... common liquid chamber, 26 ... individual carriage, 27 ... nozzle carriage, 29 ... pressure chamber forming substrate, 30 ... pressure chamber, 31 ... vibrating plate, 32 ... piezoelectric element, 33 ... sealing plate, 35 ... drive area, 36 ... piezoelectric element accommodation space, 39 ... underlayer, 40 ... DLC layer, 41 ... particles, 42 ... board, 44 ... pulse power supply, 46 ... amorphous layer, 47 ... DLC layer, 49 ... convex part, 50 ... concave part