JP5929264B2 - Droplet discharge head, ink cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a droplet discharge head, an ink cartridge, and an image forming apparatus. More specifically, the present invention relates to a droplet discharge head that discharges droplets from a nozzle by displacing a diaphragm by a driving unit, and an ink cartridge and an image forming apparatus including the droplet discharge head.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, and a multifunction machine of these, for example, an apparatus including a recording head (hereinafter also referred to as a head) constituted by a droplet discharge head is used. However, the material is not limited, and printing medium, recording medium, recording paper, transfer material, recording paper, etc. are also used interchangeably), and ink (recording liquid) as a liquid is attached to the paper while transporting it. A so-called ink jet type image forming apparatus (also referred to as an ink jet recording apparatus) that performs image formation (recording, printing, printing, and printing are also used synonymously) is known.

  In recent years, inkjet recording apparatuses have become widespread due to advances in printing speed, image quality, price reduction, and miniaturization. A droplet discharge head used in such an ink jet recording apparatus generally has a plurality of nozzle rows, a plurality of individual liquid chambers (pressure chambers) communicating with the nozzle rows, and the plurality of individual liquid chambers. In general, a common liquid chamber having a relatively large volume is communicated. By selectively applying energy to the individual liquid chamber, the individual liquid chamber can be deformed, and droplets can be ejected to form an arbitrary image on demand.

  A plurality of methods for generating pressure fluctuations in the individual liquid chambers of the droplet discharge head have been put into practical use and commercialized. For example, a thermal ink jet method in which a liquid is vaporized by installing a heater in the individual liquid chamber and pressure fluctuation is used, a method in which an actuator is installed in the individual liquid chamber, and the like can be mentioned. As a method using an actuator, a piezoelectric element method, an electrostatic method, or the like is known depending on the type of actuator.

  Although the method using an actuator is compatible with inks with a wide range of physical properties, it is difficult to increase the density of the liquid chamber arrangement and to reduce the size of the head, but by using a so-called MEMS (Micro Electro Mechanical Systems) process. Technology for increasing the density has been established. In other words, by using a unimorph actuator in which a diaphragm, electrode, piezoelectric body, etc. are stacked using thin film formation technology in an individual liquid chamber, individual piezoelectric elements, electrodes, and wiring are used using a semiconductor device manufacturing process (photolithography). It has become possible to increase the density by patterning.

  Inkjet recording heads are increasingly required to support higher printing speeds, and in order to achieve higher speeds, it is required to eject ink at a high frequency from nozzles. It is necessary to increase the rigidity of the droplet discharge head to shorten the natural period. Also, in response to the demand for higher image quality, the number of nozzles tends to increase to increase the density. Accordingly, the interval between the individual liquid chambers tends to be narrowed, and it is necessary to cope with the downsizing and high density of the head. In response to the demand for higher speed, attempts have been made to increase the length of the head. For example, a so-called line-type printer having a recording head that can cover the entire width of the recording medium has been proposed.

  By the way, it is known that a change in pressure generated in a space around the piezoelectric element may cause a change in the droplet discharge performance of the head. Specifically, when the temperature of the space changes due to heat generated by bonding the adhesive when the head is assembled, heat during the photolithography process, or heat generation of the piezoelectric element driven by the head, the surroundings of the piezoelectric element The pressure in the space also changes, and the discharge characteristics change.

  In order to solve such a problem, it has been devised that the space around the piezoelectric element is not sealed. For example, in Patent Document 1, a plurality of nozzles, a plurality of pressure chambers communicating with each nozzle and storing ink to be ejected, a diaphragm serving as one wall portion of the plurality of pressure chambers, and a diaphragm are stacked. A partition member having a space formed at a position facing the pressure chamber across the diaphragm, a piezoelectric element provided in the diaphragm within the space for displacing the diaphragm by application of a driving voltage, and laminated on the partition member And a wiring layer portion connected to an electrode for applying a driving voltage to the piezoelectric element, and an ink jet head in which a groove communicating the space and the atmosphere is formed on a surface exposed to the space in the wiring layer portion. Has been.

  Further, in Patent Document 2, a cavity is formed between a piezoelectric element substrate on which a piezoelectric element is provided, an upper substrate disposed so as to be opposed to the piezoelectric element substrate, and an upper substrate and the piezoelectric element substrate. There is disclosed a liquid droplet ejection head that includes a rib partition and in which the cavity communicates with the atmosphere.

  In the technique described in Patent Document 1, the space formed on the piezoelectric element is formed by being surrounded by three members of the flow path substrate, the partition member, and the wiring layer portion, and the wiring located above the piezoelectric element. It communicates with the atmosphere through a groove provided in the layer portion. In the technique described in Patent Document 2, the space formed on the piezoelectric element is formed by being surrounded by three members of the piezoelectric element substrate, the upper substrate, and the rib partition, and the cavity provided in the rib partition is formed. Through the atmosphere.

  In Patent Document 1, since the partition member is formed of DFR (dry fill resist), it is necessary to process the partition member with a narrow width in order to increase the density, but the processing accuracy of DFR is inferior to that of silicon. Therefore, there is a problem that it is difficult to achieve a small size and high density. In order to eject liquid droplets at a high frequency, it is necessary to hold the periphery of each piezoelectric element for each piezoelectric element in order to shorten the natural period. However, DFR has low rigidity, so it supports high-speed printing. Is difficult. Furthermore, an ink flow path is formed in the partition member, but DFR has a problem that the selectivity is low in consideration of ink resistance.

  In the technique described in Patent Document 2, since the partition member is formed of a photosensitive resin, it is necessary to hold the periphery of the piezoelectric element for each piezoelectric element in order to eject ink at a high frequency. The photosensitive resin has a problem that it cannot cope with high-speed printing because of its low rigidity.

  Therefore, the present invention provides a space around the piezoelectric element by forming a space on the piezoelectric element with two members, a flow path substrate and a holding substrate made of silicon, and providing a groove portion for communicating with the atmosphere on the holding substrate. A liquid droplet ejection head, an ink cartridge, and an image forming apparatus that can suppress a change in pressure in a space formed in the space, can cope with a higher speed, and can be reduced in size and density. The purpose is to provide.

  In order to achieve such an object, a droplet discharge head according to the present invention includes a nozzle plate provided with a plurality of nozzles for discharging a liquid, and a plurality of liquid chambers joined to the nozzle plate and separated by a partition wall. A flow path substrate, driving means for generating a pressure for pressurizing the liquid in the liquid chamber, a vibration plate forming at least a part of a wall surface of the liquid chamber, and the nozzle plate of the flow path substrate In a droplet discharge head having a holding substrate made of silicon and bonded to the opposite side, the holding substrate and the flow channel at a position facing the driving means on the flow channel substrate side A space portion surrounded by the substrate is provided, and the space portion communicates with the atmosphere through a groove portion provided in the holding substrate.

  According to the present invention, it is possible to suppress the pressure change in the space formed on the piezoelectric element, to cope with the increase in speed, and to reduce the size and increase the density.

1 is a cross-sectional view in the longitudinal direction of an individual liquid chamber of an ink jet recording head that is an embodiment of a droplet discharge head according to the present invention. It is a top view of the flow-path board | substrate of an inkjet recording head. It is sectional drawing of the individual liquid chamber short direction of an inkjet recording head. 2A and 2B are schematic views of a holding substrate according to the first embodiment, in which FIG. 1A is a plan view of the holding substrate from the common liquid chamber substrate side, and FIG. 2B is a plan view of the holding substrate from the flow path substrate side. 4A and 4B are schematic views of a holding substrate according to a second embodiment, in which FIG. 5A is a holding substrate plan view from the common liquid chamber substrate side, and FIG. 5B is a holding substrate plan view from the flow path substrate side. FIG. 9A is a schematic diagram of a holding substrate according to a third embodiment, where FIG. 9A is a plan view of the holding substrate from the common liquid chamber substrate side, and FIG. FIG. 10 is a schematic diagram of a holding substrate according to a fourth embodiment, where (A) is a plan view of the holding substrate from the common liquid chamber substrate side, and (B) is a plan view of the holding substrate from the flow path substrate side. It is a perspective view showing an example of a head integrated ink cartridge. It is a schematic block diagram (1) explaining the whole structure of the mechanism part of an inkjet recording device. It is principal part top explanatory drawing of the mechanism part of an inkjet recording device. It is a schematic block diagram (2) explaining the whole structure of the mechanism part of an inkjet recording device.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

<First Embodiment>
(Droplet ejection head configuration)
The droplet discharge head (inkjet recording head 100) according to the present embodiment is joined to a nozzle plate (nozzle plate 1) provided with a plurality of nozzles (nozzles 2) for discharging liquid (ink), and the nozzle plate. A flow path substrate (flow path substrate 10) provided with a plurality of liquid chambers (individual liquid chambers 11) separated by a partition wall (flow path substrate partition wall 16) and a pressure for pressurizing the liquid in the liquid chamber The holding means (piezoelectric element 24), the vibration plate (vibration plate 13) that forms at least a part of the wall surface of the liquid chamber, and the nozzle plate of the flow path substrate are bonded to the opposite side of the nozzle plate. In the droplet discharge head provided with the holding substrate 40), the holding substrate is located in a space (holding substrate recess 41) surrounded by the holding substrate and the flow path substrate at a position facing the driving means on the flow path substrate side. ) Space portion are those that communicates with the atmosphere via a groove provided on the holding substrate (first channel section 44 and / or the second channel section 45).

  FIG. 1 is a cross-sectional view in the longitudinal direction of an individual liquid chamber of an ink jet recording head 100 which is an embodiment of a droplet discharge head according to the present invention. 2 is a plan view (top view) of the flow path substrate of the ink jet recording head 100, and FIG. 3 is a sectional view of the ink jet recording head 100 in the short direction of the individual liquid chamber.

  The configuration of the inkjet recording head 100 will be described with reference to FIGS. The ink jet recording head 100 has a laminated structure in which the nozzle plate 1 is bonded to the lower surface of the flow path substrate 10 on which the vibration plate 13 is stacked, and the holding substrate 40 and the common liquid chamber substrate 50 are stacked on the flow path substrate 10. The ink channel is formed.

  The ink ejected from the nozzle 2 is first supplied from a common liquid chamber 51 communicating with an ink tank (not shown) to a holding substrate opening 43 provided in the holding substrate 40 and an ink supply opening to the flow path substrate 10. The liquid is supplied to the individual liquid chamber 11 through the port 17 and the ink supply path 12 communicating from the ink supply port 17 to the individual liquid chamber 11. Further, due to pressure generated by driving a piezoelectric element 24 (consisting of a lower electrode (common electrode) 21, a piezoelectric body 22, and an upper electrode (individual electrode) 23) formed on the diaphragm 13 of the individual liquid chamber 11. The liquid is discharged from the nozzle 2 communicating with the individual liquid chamber 11.

  The piezoelectric element 24 is drawn from the upper electrode 23 and the lower electrode 21 using the individual electrode wiring 25 and the common electrode wiring 27, respectively, and is connected to the driving IC 60. The drive IC 60 controls the piezoelectric element 24 by selectively supplying a voltage supplied from a drive voltage control unit (not shown) to the piezoelectric element 24 based on the print pattern. Hereinafter, a configuration example of each unit will be described.

[Nozzle plate]
The nozzle plate 1 is a substrate on which a plurality of (for example, four) rows of ink ejection nozzles 2 are arranged. The material of the nozzle plate 1 can be variously selected according to desired rigidity and workability. For example, a metal or alloy such as SUS or nickel, an inorganic material such as silicon or ceramics, or a resin material such as polyimide can be used.

  In addition, the processing method of the nozzle 2 should just select the optimal method from the material characteristic of the nozzle plate 1, and the required precision and workability, for example, electroforming plating method, etching method, press processing method, laser processing method The photolithography method or the like may be used. In addition, the opening diameter of the nozzle 2, the number of nozzle arrays, the array density, and the like may be set in a desired combination according to the specifications required for the inkjet recording head 100.

[Channel substrate]
In the flow path substrate 10, an individual liquid chamber 11, an ink supply port 17, and an ink supply path 12 that is a fluid resistance portion from the ink supply port 17 to the individual liquid chamber 11 are formed. The individual liquid chamber 11 is disposed on the surface to be joined to the nozzle plate 1. Further, the vibration plate 13, the piezoelectric element 24, the individual electrode wiring 25, the individual electrode pad 26, the common electrode wiring 27, the common electrode pad 28, and the like are disposed on the surface on the side to be bonded to the holding substrate 40. A first insulating film 29 is disposed so as to cover the individual electrode wiring 25 and the common electrode wiring 27, and a second insulating film 30 is disposed so as to cover the entire surface or a part of the piezoelectric element 24.

  The material of the flow path substrate 10 can be variously selected from desired processability and physical properties. For example, it is preferable to use a silicon substrate capable of using a photolithography method at 300 dpi (about 85 μm pitch) or more.

  When the individual liquid chamber 11 is processed, for example, a wet etching method, a dry etching method, or the like can be used when a photolithography method is used. Thereby, the individual liquid chamber 11 side of the diaphragm 13 can be formed as a silicon dioxide film or the like to serve as an etch stop layer, so that the height of the liquid chamber can be controlled with high accuracy.

The individual liquid chamber 11 is provided at a position corresponding to the nozzle 2, applies pressure to the ink, and discharges ink droplets from the nozzle 2. A diaphragm 13 is formed in the upper part of the individual liquid chamber 11, and a piezoelectric element 24 in which a lower electrode 21, a piezoelectric body 22, and an upper electrode 23 are stacked is formed on the diaphragm 13. As the diaphragm 13, it is preferable to use a highly rigid material such as silicon, nitride, oxide, or carbide. Alternatively, a stacked structure of these materials may be used. In the case of a laminated film, it is preferable that the residual stress is reduced in consideration of the internal stress of each material. For example, in the case of stacked the _Si 3 _{N 4} and SiO _2, the SiO ₂ as a _Si 3 _{N 4} as the tensile stress and compressive stress are alternately laminated, it is possible to relieve stress.

  Moreover, although the thickness of the diaphragm 13 can be selected according to a desired characteristic, the range of 0.5 micrometer-10 micrometers is preferable, for example, More preferably, it is the range of 1.0-5.0 micrometers. This is because if the diaphragm 13 is too thin, the diaphragm 13 is likely to be damaged due to cracks or the like, and if it is too thick, the amount of displacement becomes small and the discharge efficiency decreases. On the other hand, if it is too thin, the natural frequency of the diaphragm 13 is lowered, which leads to the drive frequency not being increased.

  A conductive material can be used for the lower electrode 21 and the upper electrode 23. For example, metals, alloys, conductive compounds and the like. Further, it may be a single layer film or a laminated film. Note that it is necessary to use a highly stable material that does not react with the piezoelectric body 22 or diffuse. It is also preferable to form an adhesion layer in consideration of adhesion between the piezoelectric body 22 and the diaphragm 13. Examples of the lower electrode 21 and the upper electrode 23 include, for example, Pt, Ir, Ir oxide, Pd, Pd oxide, and the like as highly stable materials. Further, Ti, Ta, W, Cr, or the like can be used as an adhesion layer with the diaphragm 13.

  As the piezoelectric body 22, a ferroelectric material exhibiting piezoelectricity can be used. For example, lead zirconate titanate or barium titanate can be used. The film formation method of the piezoelectric body 22 is not particularly limited, and for example, a sputtering method, a sol-gel method, or the like can be used. Note that the sol-gel method is preferable because the film forming temperature is low.

  The upper electrode 23 and the piezoelectric body 22 are patterned for each individual liquid chamber 11. For patterning, a normal photolithography method can be used. In the case where the piezoelectric body 22 is formed by the sol-gel method, a spin coating method or a printing method may be used.

  The piezoelectric element 24 including the piezoelectric body 22 and the lower and upper electrodes 21 and 23 is preferably formed at a position corresponding to the upper portion of the individual liquid chamber 11. When formed on the flow path substrate partition 16 that partitions the individual liquid chamber 11, the deformation of the vibration plate 13 is hindered, which may cause a decrease in discharge efficiency or damage of the piezoelectric element 24 due to stress concentration.

  In addition, an ink supply path 12 communicating with the individual liquid chamber 11 is formed in the flow path substrate 10. The ink supply path 12 has a function of supplying ink from the common liquid chamber 51 to the individual liquid chamber 11, and at the same time, by driving the piezoelectric element 24, the pressure generated in the individual liquid chamber 11 prevents the backflow of ink and the nozzle. 2 has a function of discharging.

  Therefore, it is necessary to reduce the cross-sectional area of the individual liquid chamber 11 in the ink flow direction and increase the fluid resistance. Forming the individual liquid chamber 11 and the ink supply path 12 using a photolithography method (including etching) using a silicon substrate as the flow path substrate 10 can be processed under the same conditions as the individual liquid chamber 11. preferable.

  In order to increase the fluid resistance by making the height of the ink supply path 12 lower than that of the individual liquid chamber 11, it is necessary to control the overetching amount of the individual liquid chamber 11 by time management. Due to the variation, the fluid resistance cannot be made uniform. As a result, the discharge uniformity is deteriorated.

  The ink supply path 12 communicates with the common liquid chamber 51 through the ink supply port 17 through which the diaphragm 13 opens and the holding substrate opening 43.

  The individual liquid chambers 11 are arranged via the flow path substrate partition walls 16 from the front direction to the back direction in the cross-sectional view shown in FIG. 1 (FIG. 3). The individual liquid chamber 11 is partitioned by a flow path substrate partition wall 16, and a piezoelectric element 24 corresponding to each is formed.

  The height of the individual liquid chamber 11 can be arbitrarily selected according to the head characteristics, but is preferably in the range of 20 to 100 μm, for example. The flow path substrate partition 16 can be arbitrarily set according to the arrangement density, but the partition width is preferably 10 to 30 μm, for example. In addition, when the partition wall width is narrow, when the piezoelectric element 24 of the adjacent individual liquid chamber 11 is driven, mutual interference between adjacent liquid chambers may occur, resulting in a large discharge variation. Therefore, when it is necessary to narrow the partition wall width, it is preferable to reduce the liquid chamber height.

[Electrode wiring]
In order to input drive signals to the arranged piezoelectric elements 24, individual electrodes are drawn from the upper electrode 23 and common electrodes are drawn from the lower electrode 21. As shown in FIG. 2, the individual electrodes are drawn from the arranged upper electrodes 23 to the individual electrode pads 26 through the individual electrode wirings 25. The lower electrode 21 extends to the ink supply path before the ink supply port 17 on the side opposite to the individual electrode pad 26, and is drawn out to the common electrode pad 28 through the common electrode wiring 27 that is electrically connected to the lower electrode 21. In FIG. 2, the illustration of the diaphragm 13 is omitted.

  A first insulating film 29 is formed between the lower electrode 21 and the common electrode wiring 27, and is electrically connected via a contact hole 15 opened in the first insulating film 29. Similarly, a first insulating film 29 is formed between the upper electrode 23 and the individual electrode wiring 25 and is electrically connected through a contact hole 14 opened in the first insulating film 29. Further, the common electrode pad 28 and the individual electrode pad 26 are connected to the drive IC 60.

  The individual electrode wiring 25 and the common electrode wiring 27 are preferably formed using the same material and the same process. As the electrode material, a low resistance metal, alloy, conductive material, or the like can be used. Further, it is necessary to use a material having a low contact resistance with the upper electrode 23 and the lower electrode 21. For example, Al, Au, Ag, Pd, Ir, W, Ti, Ta, Cu, Cr, or the like can be used.

In order to reduce contact resistance, a stacked structure of these materials may be used. As a material for reducing contact resistance, a conductive compound may be used. For example, oxides, nitrides, and composite compounds thereof such as Ta ₂ O ₅ , TiO ₂ , TiN, ZnO, In ₂ O ₃ , and SnO can be used. The film thickness is not particularly limited, but is preferably 1 μm or less, for example.

  In addition, it is preferable to use a film forming method with high film thickness uniformity such as a vacuum film forming method. Since these electrodes serve as a joint surface with the holding substrate 40, it is necessary to have a film thickness and a film forming method that can ensure height uniformity.

  The individual electrode wiring 25 and the common electrode wiring 27 are drawn out to the outside of the holding substrate to form the individual electrode pad 26 and the common electrode pad 28. Further, a wire 62 for inputting a signal from the driving IC 60 is connected to the individual electrode pad 26 and the common electrode pad 28. The other end of the wire 62 is connected to a driving IC pad 61 formed on the driving IC 60.

  The wiring connection method is not particularly limited. For example, ACF bonding using FPC, solder bonding, wire bonding method, flip chip method for directly bonding to the output terminal of the driving IC 60, or the like may be used. it can. What is necessary is just to select the material and structure of a pad according to each joining system.

[Holding substrate]
The holding substrate 40 is bonded to the side of the flow path substrate 10 facing the nozzle plate 1 in order to ensure the rigidity of the flow path substrate 10 (20 to 100 μm thick). The material of the holding substrate 40 is silicon. In order to prevent warping of the flow path substrate 10, it is preferable to select a material having a close thermal expansion coefficient. Moreover, it is also preferable to use ceramic materials such as glass, SiO ₂ , ZrO ₂ , and Al ₂ O ₃ .

  The holding substrate 40 has a holding substrate opening 43 that is an ink supply path for supplying liquid from the common liquid chamber 51 to the individual liquid chamber 11. The holding substrate opening 43 forms a part of the common liquid chamber 51 and communicates with the ink supply port 17 on the flow path substrate 10 side.

  Further, the holding substrate 40 has a holding substrate recess 41 formed in a region facing the individual liquid chamber 11. The holding substrate recess 41 is a space formed by excavation of the holding substrate 40, and the piezoelectric element 24 is disposed therein to form an operation region in which the piezoelectric element 24 can be displaced.

  Each holding substrate recess 41 is divided for each adjacent individual liquid chamber 11 and separated by a holding substrate partition wall 42. The holding substrate partition 42 is preferably bonded on the flow path substrate partition 16. Thereby, the rigidity of the thin channel substrate 10 can be increased, and the mutual interference between the adjacent liquid chambers when the piezoelectric element 24 is driven can be reduced. Further, since the holding substrate recess 41 is partitioned for each individual liquid chamber 11, high processing accuracy is required for high density, and in the 300 dpi head, the holding substrate partition width 42 should be 5 to 20 μm. desirable.

  FIG. 4 shows a schematic diagram of the holding substrate 40 of the present embodiment. 4A shows a holding substrate plan view from the common liquid chamber substrate side, and FIG. 4B shows a holding substrate plan view from the flow path substrate side. As shown in FIG. 4, the holding substrate recess 41 is formed for each individual liquid chamber 11 (that is, for each piezoelectric element 24), and viewed from each holding substrate recess 41 from the side opposite to the holding substrate opening 43. A concave groove (first groove portion) 44 communicating with the atmosphere outside the head is provided. By connecting the spaces (respective holding substrate recesses 41) on the piezoelectric elements 24 to the atmosphere by the concave grooves 44, it is possible to suppress the pressure of the spaces from changing even if the temperature changes. In addition, as shown in FIG. 4, the concave groove 44 is preferably provided on the surface of the holding substrate 40 on the flow path substrate 10 side.

(Production method)
Hereinafter, a specific example of a method for manufacturing the ink jet recording head 100 will be described. After a diaphragm 13 having a three-layer structure is formed by laminating SiO ₂ 0.6 μm, Si 1.5 μm, and SiO ₂ 0.4 μm on a silicon wafer having a diameter of 6 inches and a thickness of 600 μm, Ti 20 nm is formed as the lower electrode 21. , Pt 200 nm was formed by sputtering.

  Next, after forming a 2 μm thick film of lead zirconate titanate (PZT) on the lower electrode 21 by a sol-gel method using an organometallic solution, the film was baked at 700 ° C. to form a piezoelectric film of PZT (piezoelectric). Body 22). Thereafter, Pt was deposited on the piezoelectric film by a 200 nm sputtering method to form the upper electrode 23.

  Next, after the upper electrode 23 was formed, the upper electrode 23, the piezoelectric body 22, and the lower electrode 21 were patterned by a dry etching method to form a piezoelectric element pattern having the arrangement shown in FIGS.

  The arrangement pitch of the piezoelectric elements 24 was 85 μm, and the width of the piezoelectric body 22 was 50 μm. The length of the piezoelectric element 24 in the longitudinal direction was 1000 μm. The number of arrangement of the piezoelectric elements 24 was 300.

  After forming the piezoelectric element 24, a first insulating film 29 (interlayer insulating film) is formed by plasma CVD, and the individual electrode contact hole 14 and the common electrode contact hole 15 are formed on the first insulating film 29 on the upper electrode 23. After the formation, Ti 50 nm and Al 500 nm were sequentially stacked and dry-etched, whereby the individual electrode wiring 25 and the common electrode wiring 27 were pattern-formed. The electrode pattern is as shown in FIG. 2, and the width of the common electrode wiring 27 is 300 μm.

  2 is removed by dry etching, the ink supply port 17 is formed in the flow path substrate 10, and the flow path substrate 10 is completed.

  Next, the holding substrate 40 having the holding substrate recess 41, the holding substrate opening 43, and the groove 44 was formed using a silicon wafer having a diameter of 6 inches. First, the silicon wafer is polished to a thickness of 400 μm, and an oxide film or the like is formed on the flow path substrate 10 side.

  Thereafter, the oxide film is patterned by photolithography so that the holding substrate recess 41 and the holding substrate opening 43 are opened. Further, a resist is formed thereon, and the resist is patterned by photolithography so that only the holding substrate opening 43 is opened.

  Then, the holding substrate opening 43 is formed through from the flow path substrate 10 side by ICP etching. Thereafter, only the resist on the flow path substrate 10 side is removed, and the flow path substrate 10 side is half-etched by ICP etching using the first patterned oxide film pattern as a mask. When the oxide film is finally removed, the holding substrate opening 43 penetrating the ink supply port 17 on the flow path substrate 10 side can be formed.

  Further, as shown in FIG. 4, the holding substrate recess 41 is formed for each individual liquid chamber 11 (that is, for each piezoelectric element 24), and communicates from each holding substrate recess 41 to the side opposite to the holding substrate opening 43. A concave groove (first groove portion) 44 was formed. The width of the holding substrate partition wall 42 was 10 μm.

  According to the holding substrate 40, since it is silicon ICP etching, high processing accuracy is obtained and sufficient rigidity can be ensured, so that it is possible to cope with downsizing, high density and high speed. Further, the cost can be reduced as compared with the case where the holding substrate 40 is made of DFR or the like, and the ink resistance and moisture permeability resistance are better than those of the resin.

  An epoxy-based adhesive was applied and bonded to the bonding surface of the prepared holding substrate 40 with a flexographic printing machine at a film thickness of 2 μm, and the adhesive was cured to bond to the flow path substrate 10. Thereafter, the 600 μm channel substrate 10 was polished to 80 μm, and then the individual liquid chamber 11 and the ink supply channel 12 were formed by ICP dry etching.

  The width of the individual liquid chamber 11 was 60 μm, the width of the ink supply path 12 was 30 μm, and the length was 300 μm. Etching of the ink supply path 12 and the individual liquid chamber 11 was performed until reaching the vibration plate 13 to have the same height. Moreover, since the diaphragm 13 in the ink supply port 43 is etched in advance, a through-hole can be formed.

  Further, after cutting the wafer into chips by dicing, the nozzle plate 1 and the flow path substrate 10 were joined by the same method as the holding substrate 40. As the nozzle plate 1, a SUS material having a thickness of 30 μm formed by pressing a nozzle having a diameter of 20 μm at a pitch of 85 μm was used.

  Further, as shown in FIG. 1, a common liquid chamber substrate 50 made of SUS is bonded to the opposite side of the flow path substrate 10 of the holding substrate 40, and connected to an ink tank (not shown). The inkjet recording head 100 was obtained by bonding TAB mounted with the driving IC 60 by ACF bonding.

  According to the ink jet recording head 100 according to the present embodiment described above, the holding substrate recess 41 is formed so as to correspond to the individual liquid chamber 11 (piezoelectric element 24), and each holding substrate recess 41 is connected to the holding substrate opening 43. Is provided with a concave groove (first groove portion 44) communicating with the atmosphere from the opposite side, so that the space (each holding substrate concave portion 41) on each piezoelectric element 24 can be communicated with the atmosphere by the concave groove 44. In addition, pressure fluctuations in the space around the piezoelectric element due to temperature changes or the like can be suppressed.

  In addition, since silicon ICP etching is used, high processing accuracy can be obtained and sufficient rigidity can be ensured, so that it is possible to cope with high speed, and miniaturization and high density can be achieved. Further, the cost can be reduced as compared with the case where the holding substrate is made of DFR or the like, and the ink resistance and moisture permeability resistance can be improved as compared with the resin.

<Second Embodiment>
Hereinafter, other embodiments of the droplet discharge head according to the present invention will be described. In addition, the description about the same point as the said embodiment is abbreviate | omitted. The manufacturing method may be the same method as in the first embodiment.

  FIG. 5 shows a schematic diagram of the holding substrate 40 of the second embodiment. 5A shows a holding substrate plan view from the common liquid chamber substrate side, and FIG. 5B shows a holding substrate plan view from the flow path substrate side.

  In the present embodiment, each holding substrate recess 41 formed corresponding to each piezoelectric element 24 together with the groove (first groove) 44 is a recess groove (second groove portion) communicating with the holding substrate recesses 41 adjacent to each other. ) 45 is further provided. The forming method may be the same method as that for the first groove portion 44.

  According to this embodiment, it becomes possible to reduce the pressure difference between the adjacent recessed parts 41 by connecting the adjacent recessed parts 41 with the effect of the said 1st Embodiment.

<Third Embodiment>
FIG. 6 shows a schematic diagram of the holding substrate 40 of the third embodiment. 6A shows a holding substrate plan view from the common liquid chamber substrate side, and FIG. 6B shows a holding substrate plan view from the flow path substrate side.

  In the present embodiment, similarly to the second embodiment, a concave groove (second groove portion) 45 is provided, and the second groove portion 45 is further communicated to the atmosphere from the concave portions 41 at both ends without the adjacent concave portions 41. It is a configuration.

  According to the present embodiment, in addition to communicating with the atmosphere from each recess 41 through the first groove 44, the second groove 45 also communicates with the atmosphere from the recess 41 at both ends. In addition to the effect of the embodiment, it is possible to further reduce the pressure difference between the adjacent recesses.

<Fourth Embodiment>
FIG. 7 shows a schematic diagram of the holding substrate 40 of the fourth embodiment. 7A shows a holding substrate plan view from the common liquid chamber substrate side, and FIG. 7B shows a holding substrate plan view from the flow path substrate side.

  In the first to third embodiments, the concave groove (first groove portion) 44 is provided from the concave portion 41 on the piezoelectric element 24 to the side opposite to the holding substrate opening 43. For example, the concave portion on the piezoelectric element 24 is provided. In the case where it is necessary to enclose the opposite side of the holding substrate opening 43 from 41 with a resin or the like, the concave groove 44 may be buried, or it may be counterflowed. It may be difficult to provide the groove (first groove portion) 44.

  Therefore, in the present embodiment, the concave groove (first groove portion) 44 is not provided, but only the concave groove (second groove portion) 45 communicating between the concave portions 41 is provided, and the concave groove (second groove portion) is provided as in the third embodiment. Grooves) 45 are communicated to the atmosphere from both ends.

  According to this embodiment, even when it is difficult to provide the concave groove (first groove portion) 44, it is possible to reduce the pressure difference between the adjacent concave portions.

<Fifth Embodiment>
Next, an embodiment of the ink cartridge according to the present invention will be described. The droplet discharge head according to the embodiment described above is preferably a head-integrated ink cartridge (droplet discharge head-integrated cartridge) provided with the droplet discharge head.

  FIG. 8 is a schematic diagram illustrating an example of the ink cartridge 90. The ink cartridge 90 is obtained by integrating the ink jet recording head 100 according to any of the above embodiments having the nozzles 2 and the like, and an ink tank 91 that supplies ink to the ink jet recording head 100.

  Since the ink tank 90 integrated with the ink tank is equipped with the above-described ink jet recording head 100, it is possible to provide an ink cartridge that can realize both high printing speed and high image quality.

<Sixth Embodiment>
Next, an embodiment of an image forming apparatus according to the present invention will be described. The image forming apparatus (inkjet recording apparatus) including the droplet discharge head or the ink cartridge according to the embodiment described above is preferable.

  The ink jet recording apparatus according to this embodiment will be described with reference to FIGS. FIG. 9 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 10 is a plan view for explaining a main portion of the mechanism portion. In the present embodiment, an image forming apparatus (inkjet recording apparatus) provided with a droplet discharge head will be described.

  This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 is provided with a recording head 234 including a droplet discharge head unit according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). A nozzle row composed of a plurality of nozzles is arranged in the sub-scanning direction orthogonal to the main scanning direction, and is mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching droplet discharge heads 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a receives black (K) droplets. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. To do.

  Note that, here, a two-head configuration is used to eject droplets of four colors, but a droplet ejection head for each color can also be provided. The carriage 233 is equipped with sub tanks 235a and 235b (referred to as sub tanks 235 when not distinguished) for supplying ink of each color corresponding to the nozzle rows of the recording head 234. The sub tank 235 is supplied with ink of each color from the ink cartridges 210 (210k, 210c, 210m, 210y) of each color via a supply tube 236 of each color.

  On the other hand, as a paper feed unit for feeding the paper 242 loaded on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feed) that feeds the paper 242 from the paper stacking unit 241 one by one. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251.

  The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown). Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 for maintaining and recovering the nozzle state of the recording head 234 is disposed in a non-printing area on one side in the scanning direction of the carriage 233. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as caps) 282a and 282b (hereinafter referred to as caps 282 when not distinguished) and caps for wiping the nozzle surfaces. A wiper blade 283, which is a blade member, and a blank discharge receptacle 284 that receives droplets when performing blank discharge for discharging droplets that do not contribute to recording in order to discharge thickened ink are provided.

  In addition, in the non-printing area on the other side of the carriage 233 in the scanning direction, idle ejection that receives droplets when performing idle ejection that ejects droplets that do not contribute to recording in order to discharge ink that has been thickened during recording or the like. A receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width.

  When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, since the ink jet recording apparatus includes the ink jet recording head according to the above-described embodiment, it is possible to suppress the pressure fluctuation in the space on the piezoelectric element. In addition, it can cope with small size, high density and high speed.

<Seventh Embodiment>
Next, another embodiment of the image forming apparatus according to the present invention will be described. FIG. 11 is a schematic configuration diagram of the entire mechanism unit.

  This image forming apparatus is a line type image forming apparatus, has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided, a sheet 403 fed from the sheet feeding tray 404 is taken in, a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405, and then the side of the apparatus main body 401. The paper 403 is discharged to a paper discharge tray 406 attached to the printer.

  Also, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided, and when performing duplex printing, the sheet 403 is conveyed into the duplex unit 407 while being transported in the reverse direction by the transport mechanism 405 after one-side (front) printing is completed. Then, the other side (back side) is sent back to the transport mechanism 405 as the printable side, and the paper 403 is discharged to the paper discharge tray 406 after the other side (back side) printing is completed.

  Here, the image forming unit 402 is, for example, four full-line liquids according to the present invention that discharge droplets of each color of black (K), cyan (C), magenta (M), and yellow (Y). The recording heads 411k, 411c, 411m, and 411y (which are referred to as recording heads 411 when not distinguishing colors) are configured with droplet discharge heads, and each recording head 411 has a nozzle surface on which nozzles for discharging droplets are directed downward. The head holder 413 is attached.

  In addition, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (referred to as a maintenance / recovery mechanism 412 when not distinguishing colors) for maintaining and recovering the head performance corresponding to each recording head 411 is provided, and purge processing and wiping processing are provided. During the head performance maintenance operation such as the above, the recording head 411 and the maintenance / recovery mechanism 412 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 412 faces the nozzle surface of the recording head 411.

  Here, the recording head 411 is arranged to eject droplets of each color in the order of blank, cyan, magenta, and yellow from the upstream side in the paper conveyance direction, but the arrangement and the number of colors are not limited to this. Further, as the line-type head, one or a plurality of heads provided with a plurality of nozzle rows for discharging droplets of each color at a predetermined interval can be used. A head and a recording liquid cartridge for supplying ink to the heads It can be integrated or separate.

  The paper 403 in the paper feed tray 404 is separated one by one by a paper feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401, and is registered along the guide surface 423 a of the transport guide member 423. It is sent between 425 and the conveyor belt 433, and is sent to the conveyor belt 433 of the conveyor mechanism 405 via the guide member 426 at a predetermined timing.

  In addition, the conveyance guide member 423 is also formed with a guide surface 423 b for guiding the paper 403 sent out from the duplex unit 407. Further, a guide member 427 for guiding the sheet 403 returned from the transport mechanism 405 to the duplex unit 407 during duplex printing is also provided.

  The conveyance mechanism 405 includes an endless conveyance belt 433 that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432, a charging roller 434 that charges the conveyance belt 433, and an image forming unit 402. A platen member 435 that maintains the flatness of the conveying belt 433 at the opposite portion, a pressing roller 436 that presses the paper 403 fed from the conveying belt 433 against the conveying roller 431 side, and other ink (not shown) that adheres to the conveying belt 433. It has a cleaning roller made of a porous body or the like as a cleaning means for removing.

  On the downstream side of the transport mechanism 405, a paper discharge roller 438 and a spur 439 for sending the paper 403 on which an image is recorded to the paper discharge tray 406 are provided.

  In the image forming apparatus configured as described above, the conveyance belt 433 moves in the direction indicated by the arrow, and is charged by contact with the charging roller 434 to which a high potential application voltage is applied. The conveyance belt is charged to this high potential. When the sheet 403 is fed onto the sheet 433, the sheet 403 is electrostatically attracted to the conveyance belt 433.

  In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface. Then, the paper 403 is moved around the conveyor belt 433 and droplets are ejected from the recording head 411, whereby a required image is formed on the paper 403, and the paper 403 on which the image has been recorded is the paper discharge roller 438. As a result, the paper is discharged to the paper discharge tray 406.

  As described above, since the ink jet recording apparatus includes the ink jet recording head according to the above-described embodiment, it is possible to suppress the pressure fluctuation in the space on the piezoelectric element. In addition, it can cope with small size, high density and high speed.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

  For example, in the above embodiment, the liquid droplet ejection head according to the present invention is applied to an ink jet head. However, a liquid droplet other than ink, for example, a liquid droplet ejection head that ejects a liquid resist for patterning, a gene analysis sample The present invention can also be applied to a droplet discharge head for discharging.

DESCRIPTION OF SYMBOLS 1 Nozzle plate 2 Nozzle 10 Flow path board | substrate 11 Individual liquid chamber 12 Ink supply path 13 Diaphragm 14 Contact hole (individual electrode)
15 Contact hole (common electrode)
16 Channel board partition 17 Ink supply port 21 Lower electrode (common electrode)
22 Piezoelectric 23 Upper electrode (individual electrode)
24 piezoelectric element 25 individual electrode wiring 26 individual electrode pad 27 common electrode wiring 28 common electrode pad 29 first insulating film 30 second insulating film 40 holding substrate 41 holding substrate recess 42 holding substrate partition wall 43 holding substrate opening 44 concave groove (first) One groove)
45 Groove (second groove)
50 Common liquid chamber substrate 51 Common liquid chamber 60 Driving IC
61 driving IC pad 62 wire 90 ink cartridge 91 ink tank 100 inkjet recording head (droplet ejection head)

JP 2011-115972 A JP 2006-281777 A

Claims (9)

A nozzle plate provided with a plurality of nozzles for discharging liquid;
A flow path substrate provided with a plurality of liquid chambers bonded to the nozzle plate and separated by a partition;
Drive means for generating pressure to pressurize the liquid in the liquid chamber;
A diaphragm forming at least a part of the wall surface of the liquid chamber;
In a droplet discharge head comprising a holding substrate made of silicon bonded to the opposite side of the flow path substrate from the nozzle plate,
The holding substrate has a space portion surrounded by the holding substrate and the flow path substrate at a position facing the driving unit on the flow path substrate side,
The liquid droplet ejection head, wherein the space portion communicates with the atmosphere through a groove portion provided in the holding substrate. 2. The space according to claim 1, wherein a plurality of the space portions are formed for each of the driving means, each of the plurality of space portions has a first groove portion, and the first groove portion communicates with the atmosphere. Droplet discharge head.   The droplet discharge head according to claim 2, wherein the plurality of spaces communicate with each other via a second groove.   The droplet discharge head according to claim 3, wherein an end of the second groove communicates with the atmosphere. A plurality of the space portions are formed for each of the driving means , and the plurality of space portions communicate with each other via the second groove portion,
The droplet discharge head according to claim 1, wherein the second groove portion communicates with the atmosphere. A common liquid chamber substrate provided on the opposite side of the holding substrate to the flow path substrate and provided with a common liquid chamber;
The holding substrate has a holding substrate opening that opens from the common liquid chamber to the flow path substrate,
5. The liquid droplet ejection head according to claim 2, wherein the first groove portion communicates with the atmosphere from a side facing the holding substrate opening as viewed from the space portion.   The droplet discharge according to any one of claims 2 to 6, wherein the first groove part and / or the second groove part is provided on a side of the holding substrate joined to the flow path substrate. head. A droplet discharge head according to any one of claims 1 to 7,
An ink cartridge comprising: an ink tank that supplies ink to the droplet discharge head. An image forming apparatus comprising the liquid droplet ejection head according to claim 1 or the ink cartridge according to claim 8.