Ink-jet holed plate for ink jetting head and its mfg. method

Orifice plate for inkjet printing head and manufacturing method thereof

Technical field

The present invention relates to inkjet printers, and more particularly to orifice plates inserted in the print heads of the ink cartridges used in these printers.

Background technique

A printer includes one or more ink cartridges. According to some designs, the ink cartridge has several discrete ink pools with more than one ink color. Each ink tank is connected to a print head through a pipe, and the print head is installed on the main body of the ink cartridge.

The printing head is controlled so that tiny ink droplets can be ejected from the printing head to the printing medium (such as paper), and the printing medium moves forward through the printer. Control the ejection of ink droplets so that the ink droplets can form a recognizable image on the paper.

The ink droplets are discharged through the nozzle holes formed in a nozzle orifice plate, and the nozzle orifice plate covers most of the print head. The orifice plate is generally bonded to the upper part of an ink barrier layer of the print head. The shape of this barrier determines the individual ink chambers. Each ink chamber is aligned with the orifice for discharging ink droplets, and is integrated with the orifice.

The ink droplets are discharged from the ink chamber through a thermal transducer (such as a thin film resistor). The resistor is placed on an insulating substrate, preferably a commonly used silicon wafer on which an insulating layer (such as silicon dioxide) is grown. The resistor is covered with a suitable passivation layer and other layers, which are well known in the art and are described, for example, in U.S. Patent No. 4,719,477, which is incorporated herein by reference.

The resistor is selectively driven (heated) with a current pulse. The heat from the resistor is sufficient to form a vapor bubble in the three ink chambers, thereby forcing an ink drop through the associated orifice. After each ink drop is discharged, the ink chamber is refilled with ink that flows into the ink chamber through a channel connected to the ink tank ink conduit.

Using at least three different color inks: cyan, yellow, and magenta, color printing on white media can be achieved. These three colors can be combined to form black. However, in order to improve printing efficiency, a separate black ink source is generally provided.

Generally speaking, in addition to other factors, as long as the volume of each ink drop ejected from the print head is precisely controlled, the print quality can be improved. Specifically, when the volume of ink droplets of one color can be controlled relative to the volume of ink droplets of another color, the printing quality can be improved. For example, to produce a blue dot, a cyan ink drop and a magenta ink drop are discharged to the same position on the print medium. A black dot consists of a single drop of black ink. In order to ensure that the blue dot (or any other two sub-colors) is not unacceptably large, the ink chamber and/or orifice of the print head can be designed so that the size of the black ink droplets is approximately cyan, yellow, And magenta ink produces twice the size of ink droplets.

Another important design consideration for inkjet printers involves the so-called switch-on energy or TOE. The switch-on energy refers to the amount of energy required to heat the resistor in an ink chamber to produce a vapor bubble for discharging a drop of ink. People expect the minimum TOE, mainly to minimize the operating temperature of the print head and avoid some problems related to high operating temperature, such as the generation of air bubbles in the ink.

The number of refills of the ink chamber may be a limiting factor related to the overall operating efficiency of the printer, because the refillable frequency of the ink chamber limits the dischargeable frequency of ink droplets. Another important factor is the structure of the ink chamber and the connecting channel. The structure should stabilize the ink flow that refills the ink chamber as quickly as possible, so that the ejected ink droplets will not be affected by the ink in the ink chamber. The impact of any fluctuations.

One way to meet the above design considerations is to improve the shapes of the nozzle holes, ink chambers, and ink channels. In the past, the added barrier layer was a single layer, which had a uniform depth in the entire print head area, and the ink chamber was formed in the barrier layer. Fix a uniform depth orifice plate to the barrier layer. As a result, designers who are keen to modify the shape of one ink chamber relative to another are restricted to only modify the length or width of the ink chamber. Similarly, by changing the diameter instead of changing the depth, the size of one nozzle hole can be changed relative to the size of another nozzle hole.

Summary of the invention

The invention expands the selection range of the inkjet print head designer. The present invention relates to a method for manufacturing an orifice plate of an inkjet printer. The orifice plate defines both an orifice and an ink chamber. The structure of the orifice plate allows one ink chamber in the same print head to be deeper than the other ink chamber (wider and longer if desired), and the other chamber can be next to the first ink chamber. An ink chamber. Similarly, the structure of the channel that transfers the ink to the first chamber can be made deeper or shallower as needed relative to the structure of the other channel on the print head.

The advantages of the present invention can be best understood by combining the preferred embodiment of an inkjet cartridge. The ink pool carried by the inkjet cartridge is composed of four color groups: cyan, yellow, magenta, and black. One color group of ink chambers, channels, and/or nozzles can be changed in the shape of the ink chambers, channels, and nozzles provided by the present invention with respect to such another color group. For example, the ink chamber associated with black ink can be made deeper than the ink chamber associated with cyan ink.

A preferred embodiment for implementing the present invention uses a layer of photoresist material as the orifice plate and barrier layer. Irradiating this material with electromagnetic radiation (such as ultraviolet light) changes the radiation intensity of the entire orifice plate area, thus changing the depth of the polymerization and crosslinking that occurs in the layer. After arranging the mask (one or more) for irradiation control, it is possible to select ink chambers of different sizes on the same orifice plate, and so on.

After studying the following parts of the specification and the drawings, other advantages and features of the present invention will become clear.

Description of the drawings

Figure 1 is a perspective view of an ink jet cartridge carrying a print head having an orifice plate formed in accordance with a preferred embodiment of the present invention.

Figure 2 is an enlarged plan view of a print head, depicting an arrangement of 4 nozzle groups related to the 4 ink colors carried in the ink cartridge.

Fig. 3 is an enlarged cross-sectional view of the print head taken along line 3-3 of Fig. 2, showing an orifice plate manufactured in accordance with a preferred embodiment of the present invention.

Figures 4-5 show the preferred steps used in manufacturing an orifice plate according to the present invention.

Figure 6 is a cross-sectional view showing another preferred embodiment of a print head and orifice plate made in accordance with the present invention.

detailed description

Referring now to FIG. 1, a preferred embodiment of the present invention is implemented on an inkjet cartridge 20. The inkjet cartridge 20 includes a plastic body 22 that includes a liquid ink pool for separately containing four ink sources: cyan, yellow, magenta, and black ink.

The main body 22 is shaped to have a downwardly extending head 24. The print head 26 is fixed to the lower side of the header 24. The print head is formed with tiny nozzle holes, from which ink droplets can be ejected to the printing medium. As shown in Figure 2, the nozzle holes are arranged in groups, and each group has several individual nozzle holes: the cyan group 30, the yellow group 32, the magenta group 34, and the black group 36. Each group delivers the ink color associated with its group name. Figure 2 depicts the outer surface of the print head, which is covered by an orifice plate 40 (Figure 3) which will be described more fully below and formed in accordance with the present invention. However, it is worth noting here that the term "orifice plate" in the following attempts to mean a unit component that will combine the orifice, the ink chamber (thus omitting a separate barrier), and in at least one implementation The channels of the print head in the example are all combined in one layer.

FIG. 3 shows a cross-sectional view of the print head 26 taken along line 3-3 of FIG. 2, thereby describing one nozzle hole 42 of the black group 36 and one nozzle hole 44 of the magenta group 34.

The print head includes a substrate 48 having a silicon substrate 50, which is preferably a conventional silicon wafer on which an insulating layer such as silicon dioxide is grown. As described in the prior art such as U.S. Patent No. 4,719,477, the substrate includes a layer of resistive material, such as tantalum aluminum, and each part 52 of this resistive material is connected to the flex circuit 54 through some conductive layers (FIG. 1) On some wiring on the above, the circuit 54 is installed to the outside of the ink cartridge 20. These connections are terminated at contacts 56, which are mated with similar contacts on the printer tray (not shown), and the contacts on the printer tray are connected to the microprocessor of the printer, for example, through a ribbon-shaped multi-core wire. Device.

Now returning to FIG. 3, the various parts 52 of the resistive material will be referred to below as resistors 52. The resistor 52 is a part of the control layer 58 collectively referred to as the substrate 48, which includes a passivation layer and other layers. For example, it is described in U.S. Patent No. 4,719,477.

The orifice plate 40 is an integral part fixed to the control layer, and for each orifice, it includes an ink chamber that is integrated with the orifice so that it is in liquid communication with the orifice and is located below. Figure 3 shows a representative "colored" ink chamber 60 (connected to the magenta ink tank) and a representative "black" ink chamber 62 (connected to the black ink tank). The resistor 52 is selectively driven (heated) by a current pulse. The heat from the resistor is sufficient to evaporate some ink in selected ink chambers 60, 62, thereby forcing an ink drop through the associated orifice 44, 42.

After each ink drop is ejected, the ink chamber is refilled with ink that flows into the ink chamber through a channel connected to the corresponding ink pool. One such "colored" channel 64 connected to the colored ink chamber 60 is shown in FIG. The figure also shows a "black" channel connected to the black ink chamber 62. As described in conjunction with FIG. 6, the ink chamber can also be filled and refilled through the slits extending through the substrate 50 and the control layer 58, so that the passage in the orifice plate is unnecessary.

A colored ink chamber 60 and a black ink chamber 62 depicted in FIG. 3 illustrate an important aspect of the present invention. Specifically, in order to find a solution to the design considerations discussed above, the present invention allows designers to deal with a unitary orifice plate 40, in which one (or more) ink chambers 60 can be made more than in the same unit. The other chamber 62 on the orifice plate is deeper. In this connection, it is considered that the depth is measured in the vertical direction of FIG. 3 from the outer surface 68 of the orifice plate 40 to the substrate 48.

In considering the depth of a nozzle hole, it is beneficial to consider this structure in terms of an annular portion, which can be described as the annular portion of the nozzle orifice plate that surrounds the nozzle hole and covers the associated ink chamber. As shown in the cross-sectional view of FIG. 3, a "colored" ring portion 70 exists in the orifice plate material surrounding the colored orifice 44 and is located between the dotted lines 72. The dotted line 72 represents the upward direction of the ink chamber 60 below. Protruding. Similarly, a "black" ring portion 74 exists in the orifice plate material surrounding the black orifice 42 and is located between the dotted lines 76, which represent the upward protrusion of the ink chamber 62 below.

Referring now to FIG. 3, in the same orifice plate 40, the depth of one channel 66 is equal to or greater than the depth of the other channel 64. When considering the channel, although the depth is measured vertically, the dimension of the desired depth refers to the distance the channel extends above the substrate 48.

Although the above description refers to a substantially cylindrical nozzle hole and ink chamber, it should be understood that the nozzle hole and the connected ink chamber may be any of a variety of shapes. For example, even if the nozzle hole is cylindrical, the ink chamber below may be square or rectangular (with rounded corners). The above-mentioned ring portion or ring member may also be changed into a slightly frame-shaped shape. Therefore, it is not desirable to limit the term ring portion to only a specific ring shape.

Obviously, the length (measured in the horizontal direction of FIG. 3) and width (measured in the direction perpendicular to the plane of FIG. 3) between two nozzles, ink chambers, or channels can be varied. However, the present invention relates to the variation of the depth dimension at both ends of an orifice plate as discussed above. This depth change, either only the depth itself, or combined with variable length and width dimensions, greatly increases the number of options available to technicians responsible for print head design. For example, the ratio of the depth of an ink chamber to the combined depth of the ink chamber and its associated nozzles, the volume of the discharged ink drop, the length of the ink drop tail, the refill time of the ink chamber, and the ejection of an ink drop It is related to the time required to refill the ink chamber. This description will now be turned to a preferred method of manufacturing a unitary orifice plate having nozzle holes, ink chambers, and channels of various depths.

First, refer to FIG. 4, which shows a section of the print head that is substantially the same as the section of FIG. 3, of course, before completing the processing of the section of FIG. 4. In a preferred embodiment, the production of the orifice plate 40 starts with a base layer composed of a photoresist material 80 which is added to the substrate 48 that has been manufactured as described above. (In another way, the orifice plate can be made on a mandrel, the orifice plate is removed, and then the orifice plate is bonded to a prefabricated substrate.) In a preferred embodiment, the layer The photoresist material 80 (FIG. 4) includes a photopolymerizable epoxy resin, generally referred to as SU-8 in the business community. An example is available from MicroChem Corp. of Newton, MA, sold under the name SU8-10. However, it can be clearly seen that the orifice plate can include any one of a variety of negative photoresist materials. The negative photoresist material is exposed to electromagnetic radiation (such as ultraviolet radiation) in the range of 200-500 nanometers. After that, it becomes insoluble in the developer.

The photoresist material 80 of the layer is located at a depth "D" of the substrate about 20 μm. Once the layer of photoresist material 80 is added, the layer is irradiated with ultraviolet radiation through a mask 82. The pattern of the mask 82 should divide the photoresist layer into at least three different types of regions. As a result of the radiation blocking patterns 84, 86 on the mask 82, one area does not receive any radiation. These patterns may include, for example, a thin layer of chromium. The shape of a blocking pattern 84 is consistent with the diameter of the colored orifice 44 with a relatively small diameter in a plan view (that is, viewed in a direction parallel to the plane of FIG. 4). The other blocking pattern 86 corresponds to the diameter of the black nozzle hole 42 in plan view.

Surrounding the blocking pattern 84 is an attenuation pattern 88 on a mask 82 for attenuating the intensity of the radiation source. The attenuation pattern can be, for example, a thin layer of interference filter material, or a thin absorbing film, such as silver, or nickel-chromium-iron alloy, which is called inconel. As a result, the radiation ring of relatively low intensity reaches the outer surface 68 of the layer of photoresist material 80. This low-intensity radiation is depicted by arrow 90 in FIG. 4.

In the area leaving the barrier patterns 84, 86 and the attenuation pattern 88, relatively high intensity source radiation reaches the outer surface 68 of the layer of photoresist material 80. This high intensity radiation is indicated by arrow 92 in FIG. 4.

The photoresist layer 80 is polymerized and cross-linked in the area exposed to the radiation. This polymeric crosslink is shown in Figure 4 as a double shaded area. Specifically, the polymer cross-linking in the area exposed to high-intensity radiation reaches the depth "D2, which is relatively deeper than the polymer cross-linking depth "D1 in the area exposed to relatively low radiation.

The size of the low-intensity radiation is selected so that the penetration depth "D1" of the polymerization cross-linking in the low-intensity zone is consistent with the design depth of the annular portion 70 around the colored nozzle hole 44. Similarly, the size of the high-intensity radiation is selected so that the penetration depth "D2" of the polymerization and cross-linking in the high-intensity zone is consistent with the design depth of the annular portion 74 around the black nozzle hole 44.

Now referring to FIG. 5, the photoresist material 80 of the layer is then subjected to high-intensity radiation directed to this layer through the mask 96. The mask 96 is patterned, with blocking patterns 98, 100, and blocking patterns. 98 and 100 are on the outer surface 68 of the layer of photoresist material 80 and cover the corresponding parts of the layer of photoresist material 80 and the nozzle holes 44 and 42 and the annular parts 70 and 74. In another way, the blocking patterns 98, 100 correspond to the shapes of the ink chambers 60, 62 in plan view.

As shown in Figure 5, the high-intensity radiation used in this step is selected so as to ensure that the entire depth "D" in the radiation-receiving area is polymerized and cross-linked, such as between the ink chambers 60 and 62. area. Once this irradiation is completed, the layer of photoresist material 80 is baked (for example, 95°, 30 minutes), and developed in a conventional manner to remove the rest of the layer that has not been irradiated, as in 102 and 104 As shown at the place. These portions not irradiated with radiation correspond to the continuous colored orifices 44 and the ink chamber 60, respectively, and to the continuous black orifices 42 and the ink chamber 62, respectively. The development step produces the unitary nozzle orifice plate 40 of the present invention, which includes nozzle holes and ink chambers of varying shapes in the same component.

In the case where it is desired to create a channel as shown at 64 in FIG. 3, the pattern formed by the corresponding portion of the mask 96 above the channel 64 has an attenuation filtering function so as to allow moderate-level intensity radiation to pass through the layer The photoresist material 80 (Figure 5), and the resulting polymerized cross-linking depth is close to but less than the depth "D" selected by the print head designer. The remaining unirradiated parts and the unirradiated parts 102 and 104 discussed above are removed at the same time. In this way, channels of different depths can be created in the same orifice plate.

Figure 6 shows another print head design, in which the function of the above-mentioned channels is replaced by feed slits 264, 266, said feed slits 264, 266 are formed by a control layer 258 (the control layer 258 is similar to the previous Described layer 58). The supply slits 264, 266 are in liquid communication with the ink chamber, which appears after removing the undeveloped areas 202, 204, and the related ducts 265 and 267 are etched in the silicon substrate 250 . These pipes 265, 267 are connected to the corresponding colored and black ink pools in the ink cartridge. Therefore, it can be clearly seen that this embodiment does not need to form a channel in the photoresist layer 280. This layer 280 can also be processed in the manner described above in connection with FIGS. 4 and 5.

Although the present invention has been described in conjunction with a preferred embodiment, it is obvious to those skilled in the art that the scope of the present invention is not limited to these embodiments, but can be extended to the various types defined in the appended claims. Various improvements and equivalents.