JP2014151623A - Piezoelectric actuator device, liquid droplet discharge head, ink cartridge, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator device capable of improving durability of a wiring connection part in an upper electrode layer for supplying electric potential to the upper electrode layer.SOLUTION: A piezo electric actuator device includes: a nozzle hole 301; a channel formation substrate 208 having a pressurized liquid chamber 202 communicating with the nozzle hole 301; a diaphragm 203 forming one face of the pressurized liquid chamber 202; a piezoelectric element 201 laminated on the diaphragm 203 in sequence. The piezoelectric element 201 includes a lower electrode layer 211, a piezoelectric layer 212, and an upper electrode layer 213, which are laminated from the side of the diaphragm 203 in sequence. The whole parts of the piezoelectric layer 212 are disposed on the lower electrode layer 211. The upper electrode layer 213 is disposed to straddle from an area opposed to the pressurized liquid chamber 202 to an outside area thereof. A wiring connection part 215 in the upper electrode layer for supplying electric potential to the upper electrode layer 213 is disposed in an outside area of the area opposed to the pressurized liquid chamber 202.

Description

  The present invention relates to a piezoelectric actuator device, a droplet discharge head, an ink cartridge, and an image forming apparatus.

  For example, a droplet discharge head of an ink jet image forming apparatus used in an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, or a plotter is known. The droplet discharge head includes a nozzle that discharges ink droplets, a pressurized liquid chamber that communicates with the nozzle, and energy generation means that pressurizes ink in the pressurized liquid chamber. The droplet discharge head discharges ink droplets from the nozzles by pressurizing the ink in the pressurized liquid chamber with the energy generated by the energy generating means.

  The pressurized liquid chamber is also referred to as an ink flow path, a pressurized chamber, a pressure chamber, a discharge chamber, a liquid chamber, and the like. The energy generating means is, for example, a device provided with an electromechanical conversion element such as a piezoelectric element, a device provided with an electrothermal conversion element such as a heater, or a diaphragm that forms the wall surface of the ink flow path and the diaphragm. And the like having electrodes arranged in the same manner.

  As a piezo-type liquid droplet ejection head, there are known a longitudinal vibration type in which a piezoelectric element extends and contracts in an axial direction and a lateral vibration (bend mode) type using the bending of the piezoelectric element. In recent years, a thin film piezoelectric actuator in which a piezoelectric element is formed as a thin film is known as the latter lateral vibration type.

  The thin film piezoelectric actuator is formed on a lower electrode layer formed on a substrate, a PZT (lead zirconate titanate) layer which is a piezoelectric layer formed on the lower electrode layer, and on the PZT layer. And a laminated structure having an upper electrode layer. The characteristics of the lower electrode layer and the upper electrode layer formed with the PZT layer interposed therebetween are the material characteristics for ensuring the piezoelectric characteristics and crystallinity of the PZT layer, and the electrical characteristics for propagating the drive signal from the external circuit. Surface function is required. In order to satisfy these functions, the upper electrode layer and the lower electrode layer are usually formed in a laminated structure of two layers or three layers.

  By providing the PZT layer and the upper electrode layer for each of the pressurized liquid chambers with respect to the plurality of pressurized liquid chambers, the piezoelectric elements corresponding to the pressurized liquid chambers are individually driven. The upper electrode layer is disposed in a region facing the pressurized liquid chamber in order to secure a displacement amount per unit driving voltage of the PZT layer.

  The lower electrode layer, the piezoelectric element, and the upper electrode layer are covered with an insulating film. The insulating film is provided with a connection hole for forming a connection portion with a wiring for supplying a potential to each electrode. A junction between the electrode and the wiring is formed in the connection hole.

FIG. 19 is a schematic diagram for explaining a configuration example of a droplet discharge head.
As shown in FIG. 19, the droplet discharge head is a laminated substrate in which a subframe substrate 400, an actuator substrate 200, and a nozzle substrate 300 are bonded together with an adhesive.

  In the subframe substrate 400, an actuator protection cavity 401 and a subframe joint portion 402 are formed on the surface facing the actuator substrate 200.

  A piezoelectric element 201 having a laminated structure of a lower electrode layer, a piezoelectric layer, and an upper electrode layer is formed on one surface of the actuator substrate 200. On the piezoelectric element 201, interlayer insulating films 204 and 214, wirings 205 and 206 for transmitting signals from an external drive circuit, and a passivation protection film 207 for protecting the wirings 205 and 206 are formed as a basic configuration. . A pressurized liquid chamber 202 and a partition wall 209 are formed on the other surface of the actuator substrate 200 via a vibration plate 203.

  When the actuator substrate 200 and the subframe substrate 400 are bonded, the upper surface of the passivation protection film 207 positioned above the partition wall 209 and the lower surface of the subframe bonding portion 402 of the subframe substrate 400 are bonded by an adhesive.

  The nozzle substrate 300 includes a nozzle hole 301 formed by a known press process, a Ni electroforming method, or the like. The nozzle substrate 300 is bonded to the lower surface of the partition wall 209 of the actuator substrate 200 with an adhesive.

  FIG. 20 is a schematic plan view and cross-sectional view for explaining a conventional droplet discharge head. In FIG. 20, the cross-sectional view corresponds to the ZZ position in the plan view. In the plan view of FIG. 20, the interlayer insulating films 204 and 214, the passivation protection film 207, and the subframe substrate 400 are not shown. In the cross-sectional view of FIG.

  In the actuator substrate 200 of the conventional droplet discharge head, a piezoelectric layer 212 and an upper electrode layer 213 are disposed in a region facing the pressurized liquid chamber 202. The lower electrode layer 211, the piezoelectric layer 212 and the upper electrode layer 213 are covered with an interlayer insulating film 214. An interlayer insulating film 204 is formed on the interlayer insulating film 214.

  A wiring 205 for supplying a potential to the upper electrode layer 213 and a wiring 206 for supplying a potential to the lower electrode layer 211 are formed on the interlayer insulating film 214. In the interlayer insulating films 204 and 214, a connection hole for electrically connecting the wiring 205 and the upper electrode layer 213 and a connection hole for electrically connecting the wiring 206 and the lower electrode layer 211 are formed. ing.

  The upper electrode layer wiring connection portion 215 between the wiring 205 and the upper electrode layer 213 is disposed on the piezoelectric layer 212. A lower electrode layer wiring connection portion 216 between the wiring 206 and the lower electrode layer 211 is disposed on the partition wall 209 via the diaphragm 203. In the cross-sectional view of FIG. 20, for convenience, the lower electrode layer wiring connection portion 216 is illustrated.

  In order to ensure the amount of displacement per unit drive voltage of the piezoelectric element 201, a device has been devised such that only the minimum components other than the lower electrode layer 211, the piezoelectric layer 212, and the upper electrode layer 213 are disposed. .

  Also, Patent Document 1 discloses an invention of a droplet discharge head that can improve the reliability by preventing peeling of a piezoelectric layer and generation of cracks. The droplet discharge head is intended to prevent destruction of the piezoelectric layer at the boundary between the pressurized liquid chamber (pressure generation chamber) and the partition wall (peripheral wall).

  The liquid droplet ejection head disclosed in the cited document 1 has a piezoelectric active part that is a substantial driving part and a piezoelectric layer continuous from the piezoelectric active part in a region facing the pressurized liquid chamber. And a piezoelectric body inactive portion that is not driven in an active manner. The piezoelectric inactive portion is realized by removing the lower electrode layer directly below the piezoelectric layer.

  In Cited Document 1, when the piezoelectric active portion is driven, displacement at the boundary between the pressurized liquid chamber and the partition wall is suppressed by the piezoelectric inactive portion, thereby preventing the piezoelectric layer from peeling and cracking. It is supposed to be done. Further, in the cited document 1, a piezoelectric inactive portion is extended from the region facing the pressurized liquid chamber to the outside of the region, and the lead electrode extends from the pressurized liquid chamber to the partition through the piezoelectric inactive portion. It is disclosed that it can be extended.

  However, in the droplet discharge head shown in FIG. 20, the upper electrode layer 213 stacked on the piezoelectric layer 212 has poor adhesion at the film interface with the piezoelectric layer 212. Further, the upper electrode layer wiring connection portion 215 between the wiring 205 and the upper electrode layer 213 is disposed on a portion where the piezoelectric layer 212 is displaced (deformed). As a result, stress concentrates on the upper electrode layer wiring connection portion 215, and the interface between the upper electrode layer 213 and the piezoelectric layer 212 tends to peel off in the vicinity of the upper electrode layer wiring connection portion 215. Therefore, the conventional droplet discharge head has a problem that it is difficult to ensure the reliability of the upper electrode layer wiring connection portion 215.

  As described above, the conventional droplet discharge head has a problem that the durability of the upper electrode layer wiring connection portion for supplying a potential to the upper electrode layer is low, and the reliability in use is low.

  Further, in the droplet discharge head disclosed in the cited document 1, the piezoelectric inactive portion of the piezoelectric layer is formed in the removal region of the lower electrode layer, that is, the surface of the diaphragm, so that the crystal orientation of the piezoelectric layer is There was a problem that they were not aligned and could not be controlled. For example, when the surface of the diaphragm is SiO, if a PZT layer as a piezoelectric layer is formed on the diaphragm, the crystal orientation of the PZT layer is not aligned. Further, when heat treatment is applied, peeling may occur at the film interface between the PZT layer and the diaphragm. In addition, the piezoelectric inactive portion acts as an obstruction factor in securing the amount of displacement per unit drive voltage of the piezoelectric element.

  An object of the present invention is to improve the durability of an upper electrode layer wiring connecting portion for supplying a potential to an upper electrode layer in a piezoelectric actuator device.

  A piezoelectric actuator device according to the present invention includes a nozzle hole, a flow path forming substrate having a pressurized liquid chamber communicating with the nozzle hole, a vibrating plate forming one surface of the pressurized liquid chamber, and an upper surface of the vibrating plate. A piezoelectric actuator device comprising a lower electrode layer, a piezoelectric layer, and a piezoelectric element having an upper electrode layer, which are stacked in order, wherein the piezoelectric layer is disposed on the lower electrode layer. And at least the upper electrode layer is arranged to extend from a region facing the pressurized liquid chamber to a region outside the region, and an upper electrode layer wiring connection for supplying a potential to the upper electrode layer. The portion is arranged at a position outside the region facing the pressurized liquid chamber.

  The piezoelectric actuator device of the present invention can improve the durability of the upper electrode layer wiring connecting portion for supplying a potential to the upper electrode layer.

It is a schematic plan view and a cross-sectional view for explaining an embodiment of a droplet discharge head provided with an embodiment of a piezoelectric actuator device. FIG. 5 is a schematic cross-sectional view for explaining an example of a process for forming the liquid ejection head shown in FIG. 1. FIG. 3 is a schematic cross-sectional view for explaining an example of a process for forming the liquid ejection head shown in FIG. 1, and a schematic cross-sectional view for explaining a process subsequent to FIG. 2. FIG. 4 is a schematic cross-sectional view for explaining an example of a process for forming the liquid ejection head shown in FIG. 1, and is a schematic cross-sectional view for explaining a process subsequent to FIG. 3. It is the schematic plan view and sectional drawing for demonstrating the Example of the droplet discharge head provided with the other Example of the piezoelectric actuator apparatus. FIG. 6 is a schematic cross-sectional view for explaining a part of the example of forming the liquid ejection head shown in FIG. 5. FIG. 6 is a schematic cross-sectional view for explaining a part of an example of the liquid discharge head forming process shown in FIG. 5, and is a schematic cross-sectional view for explaining a process subsequent to FIG. 6. It is a schematic plan view and a cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. FIG. 9 is a schematic cross-sectional view for explaining a part of the example of forming the liquid ejection head shown in FIG. 8. FIG. 10 is a schematic cross-sectional view for explaining a part of the liquid discharge head forming process example shown in FIG. 8, and is a schematic cross-sectional view for explaining a process subsequent to FIG. 9. It is a schematic plan view and a cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. FIG. 12 is a schematic cross-sectional view for explaining a part of the example of forming the liquid discharge head shown in FIG. 11. FIG. 13 is a schematic cross-sectional view for explaining a part of the formation process example of the liquid ejection head shown in FIG. 11, and a schematic cross-sectional view for explaining a process subsequent to FIG. 12. It is a schematic plan view and a cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. FIG. 15 is a schematic cross-sectional view for explaining a part of the example of the forming process of the liquid discharge head shown in FIG. 14. FIG. 16 is a schematic cross-sectional view for explaining a part of the liquid discharge head forming process example shown in FIG. 14, and is a schematic cross-sectional view for explaining a process subsequent to FIG. 15. 1 is a schematic side view for explaining the overall configuration of an embodiment of an image forming apparatus. FIG. 2 is a schematic plan view of an essential part of the apparatus. It is the schematic for demonstrating the structural example of a droplet discharge head. It is the schematic top view and sectional drawing for demonstrating the conventional droplet discharge head.

  In the piezoelectric actuator device of the present invention, an example in which the piezoelectric layer is disposed only in a region facing the pressurized liquid chamber can be given. According to this aspect, the upper electrode layer wiring connection portion is not disposed via the diaphragm without the deformation source piezoelectric layer being disposed below the upper electrode layer wiring connection portion for supplying a potential to the upper electrode layer. A configuration fixed to the flow path forming substrate can be realized. Thereby, the displacement (deformation) of the upper electrode layer wiring connection portion is suppressed, and defects due to peeling of the upper electrode layer wiring connection portion are prevented.

  Further, a dummy piezoelectric layer formed simultaneously with the same material as the piezoelectric layer and at a distance from the piezoelectric layer immediately below the upper electrode layer and below the upper electrode layer wiring connection portion. It may be arranged. According to this aspect, the upper electrode layer wiring connection portion is electrically stabilized, and electrical defects are reduced.

  Furthermore, a dummy lower electrode layer that is formed of the same material as the lower electrode layer at the same time and is spaced apart from the lower electrode layer may be disposed immediately below the dummy piezoelectric layer. According to this aspect, the upper electrode layer wiring connection portion is electrically stabilized, electrical defects are reduced, and the crystal orientation of the dummy piezoelectric layer can be controlled.

  Further, a buffer layer for reducing a step formed in the upper electrode layer may be embedded in a space between the piezoelectric layer and the dummy piezoelectric layer. According to this aspect, the conduction failure of the upper electrode layer is reduced.

  In addition, a dummy lower electrode layer formed simultaneously with the same material as the lower electrode layer and spaced apart from the lower electrode layer immediately below the upper electrode layer and below the upper electrode layer wiring connection portion. It may be arranged. According to this aspect, the upper electrode layer wiring connection portion is electrically stabilized, and electrical defects are reduced.

  A droplet discharge head according to the present invention includes the piezoelectric actuator device of the present invention. The droplet discharge head of the present invention is an upper electrode layer wiring connection portion for supplying a potential to the upper electrode layer while ensuring a displacement amount per unit driving voltage of the piezoelectric element by the effect of the piezoelectric actuator device of the present invention. The durability of can be improved.

  An ink cartridge according to the present invention is an ink cartridge in which a liquid droplet ejection head that ejects liquid droplets and a liquid tank that supplies liquid to the liquid droplet ejection head are integrated. It is a droplet discharge head. The ink cartridge of the present invention is an upper electrode layer for supplying a potential to the upper electrode layer while ensuring a displacement amount per unit driving voltage of the piezoelectric element in the droplet discharge head by the effect of the piezoelectric actuator device of the present invention. The durability of the wiring connection portion can be improved.

  An image forming apparatus according to the present invention is an image forming apparatus provided with a droplet discharge head for discharging droplets, wherein the droplet discharge head is the droplet discharge head of the present invention. According to the image forming apparatus of the present invention, due to the effect of the piezoelectric actuator device of the present invention, an upper electrode for supplying a potential to the upper electrode layer while ensuring a displacement amount per unit driving voltage of the piezoelectric element in the droplet discharge head. The durability of the layer wiring connection portion can be improved.

  FIG. 1 is a schematic plan view and cross-sectional view for explaining an embodiment of a droplet discharge head provided with an embodiment of a piezoelectric actuator device. In FIG. 1, the cross-sectional view corresponds to the A-A ′ position in the plan view. In the plan view of FIG. 1, the interlayer insulating film, the passivation protective film, and the subframe substrate are not shown. An exploded perspective view of this embodiment is the same as FIG.

  The droplet discharge head of this embodiment includes a nozzle substrate 300, an actuator substrate 200, and a subframe substrate 400. The nozzle substrate 300, the actuator substrate 200, and the subframe substrate 400 are laminated in that order. The nozzle substrate 300 and the actuator substrate 200 are bonded by, for example, an adhesive. The actuator substrate 200 and the subframe substrate 400 are bonded together by, for example, an adhesive.

  The nozzle substrate 300 includes a plurality of nozzle holes 301 formed by a known press process, Ni electroforming method, or the like.

  The actuator substrate 200 includes a flow path forming substrate 208, a vibration plate 203, a piezoelectric element 201, interlayer insulating films 204 and 214, wirings 205 and 206, and a passivation protection film 207.

  The flow path forming substrate 208 is formed of, for example, a silicon substrate. The flow path forming substrate 208 includes a pressurized liquid chamber 202 and a partition wall 209. The pressurized liquid chamber 202 is formed for each nozzle hole 301 at a position communicating with the nozzle hole 301. The partition wall 209 defines a formation region of the pressurized liquid chamber 202.

  A vibration plate 203 is formed on the upper surface of the flow path forming substrate 208 (the surface opposite to the surface to which the nozzle substrate 300 is bonded). The vibration plate 203 covers the pressurized liquid chamber 202 and forms one surface of the pressurized liquid chamber 202.

  A piezoelectric element 201 is formed on the vibration plate 203. The piezoelectric element 201 includes a lower electrode layer 211, a piezoelectric layer 212, and an upper electrode layer 213. The lower electrode layer 211, the piezoelectric layer 212, and the upper electrode layer 213 are stacked on the vibration plate 203 in that order.

  The lower electrode layer 211 is disposed so as to extend from a region facing the pressurized liquid chamber 202 to a region outside the region (region above the partition wall 209). Further, the lower electrode layer 211 is disposed across a region facing the plurality of pressurized liquid chambers 202. However, the lower electrode layer 211 may be provided for each corresponding pressurized liquid chamber 202.

  The piezoelectric layer 212 is provided for each corresponding pressurized liquid chamber 202. All portions of the piezoelectric layer 212 are disposed on the lower electrode layer 211. In addition, the piezoelectric layer 212 is disposed over a region above the partition wall 209 from a region facing the pressurized liquid chamber 202.

  The upper electrode layer 213 is provided for each corresponding piezoelectric layer 212. The piezoelectric layer 212 is disposed on the piezoelectric layer 212 from the region facing the pressurized liquid chamber 202 to the region above the partition wall 209.

An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the vibration plate 203. The interlayer insulating film 214 functions as a protective film for the piezoelectric element 201.
An interlayer insulating film 204 is formed on the interlayer insulating film 214.

  On the interlayer insulating film 204, wirings 205 and 206 made of, for example, a metal material are formed. The wiring 205 is for supplying a potential to the upper electrode layer 213. The wiring 206 is for supplying a potential to the lower electrode layer 211.

  Connection holes for electrically connecting the wiring 205 and the upper electrode layer 213 are formed in the interlayer insulating films 204 and 214. A conductive material is embedded in the connection hole, and an upper electrode layer wiring connection portion 215 for electrically connecting the wiring 205 and the upper electrode layer 213 is formed. The upper electrode layer wiring connection portion 215 is disposed at a position outside the region facing the pressurized liquid chamber 202, that is, above the partition wall 209. Below the upper electrode layer wiring connection portion 215, a piezoelectric layer 212 and a lower electrode layer 211 exist between the upper electrode layer 213 and the diaphragm 203.

  In addition, connection holes for electrically connecting the wiring 206 and the lower electrode layer 211 are also formed in the interlayer insulating films 204 and 214. A conductive material is embedded in the connection hole, and a lower electrode layer wiring connection portion 216 for electrically connecting the wiring 206 and the lower electrode layer 211 is formed. The lower electrode layer wiring connecting portion 216 is disposed at a position outside the region facing the pressurized liquid chamber 202, that is, above the partition wall 209. The lower electrode layer wiring connection portion 216 is provided at a position different from the arrangement region of the piezoelectric layer 212. In the cross-sectional view of FIG. 1, for convenience, the lower electrode layer wiring connection portion 216 is illustrated.

A passivation protection film 207 covering the wirings 205 and 206 is formed on the interlayer insulating film 204.
The interlayer insulating film 204 and the passivation protection film 207 are provided with openings in a region facing the pressurized liquid chamber 202, for example. The opening is for increasing the displacement efficiency of the piezoelectric element 201. As described above, in order to secure the displacement amount per unit drive voltage of the piezoelectric element 201, a device other than the lower electrode layer 211, the piezoelectric layer 212, and the upper electrode layer 213 is arranged such that only a minimum amount is arranged. It has been subjected.

  The subframe substrate 400 is formed of, for example, a silicon substrate. In the subframe substrate 400, an actuator protection cavity 401 and a subframe bonding portion 402 are formed on the bonding surface with the actuator substrate 200. In addition to these, the sub-frame substrate 400 is formed with ink supply holes for supplying ink from the outside, openings for routing electric wiring to the outside, marks for alignment with the actuator substrate 200, and the like.

  In the droplet discharge head of this embodiment, the lower electrode layer 211, the piezoelectric layer 212, and the upper electrode layer 213 extend to a region outside the region facing the pressurized liquid chamber 202 (a region above the partition wall 209). Are arranged. Further, the upper electrode layer wiring connection portion 215 for supplying a potential to the upper electrode layer 213 is disposed at a position outside the region facing the pressurized liquid chamber 202.

  Therefore, the upper electrode layer wiring connection portion 215 is mechanically fixed to the partition wall 209 of the flow path forming substrate 208 through the upper electrode layer 213, the piezoelectric layer 212, the lower electrode layer 211, and the vibration plate 203. That is, the upper electrode layer wiring connection portion 215 is disposed in a region where there is no influence of driving deformation of the piezoelectric element 201. Thereby, the displacement of the upper electrode layer wiring connection part 215 is suppressed, the peeling failure near the upper electrode layer wiring connection part 215 is reduced, and the durability and reliability of the upper electrode layer wiring connection part 215 are improved. .

  Further, since the upper electrode layer wiring connection portion 215 is not disposed in the region facing the pressurizing liquid chamber 202, the liquid droplet ejection head of this embodiment is more pressurized liquid than the conventional liquid droplet ejection head. The amount of material disposed in the region facing the chamber 202 can be reduced. Thereby, the obstruction factor for ensuring the displacement amount per unit drive voltage of the piezoelectric element 201 is reduced.

  Furthermore, since all the parts of the piezoelectric layer 212 are disposed on the lower electrode layer 211, the crystal orientation during the formation of the piezoelectric layer 212 can be controlled. Thereby, peeling of the piezoelectric layer 212 is prevented.

  As described above, the droplet discharge head of this embodiment can improve the reliability of continuous use.

  2, 3, and 4 are schematic cross-sectional views for explaining an example of a process for forming the liquid discharge head shown in FIG. 1. 2, 3, and 4 correspond to the A-A ′ position in the plan view of FIG. 1. With reference to FIG. 2, FIG. 3 and FIG. The parentheses for each step described below correspond to the parentheses in FIGS. 2, 3, and 4.

(1) The vibration plate 203 is formed on the flow path forming substrate 208 in order to form the actuator substrate 200 (see FIG. 1). The flow path forming substrate 208 is, for example, a silicon wafer having a surface orientation of <100> and a thickness of 625 μm (micrometer). The diaphragm 203 is formed by forming a silicon oxide film, a silicon nitride film, and a polysilicon film in a desired configuration by, for example, a thermal oxidation method and a CVD (chemical vapor deposition) method.

(2) On the vibration plate 203, a lower electrode layer 211, a piezoelectric layer 212, and an upper electrode layer 213 for forming a piezoelectric element are formed in that order. The lower electrode layer 211 is a laminated film of a Ti layer, a Pt layer, and a SrRuO ₃ layer (SRO layer) formed by, for example, a sputtering method. The piezoelectric layer 212 is a PZT layer formed with a desired thickness by, for example, a sol-gel method. The upper electrode layer 213 is a laminated film of an SRO layer and a Pt layer formed by, for example, a sputtering method.

(3) A photoresist pattern 501 for patterning the upper electrode layer 213 is formed on the upper electrode layer 213 by photolithography.

(4) The upper electrode layer 213 is patterned by an etching technique using the photoresist pattern 501 as a mask. The photoresist pattern 501 is removed.
A photoresist pattern for patterning the piezoelectric layer 212 is formed by photolithography. The piezoelectric layer 212 is patterned by the etching technique using the photoresist pattern as a mask. The photoresist pattern is removed.

  A photoresist pattern for patterning the lower electrode layer 211 is formed by photolithography. The lower electrode layer 211 is patterned by the etching technique using the photoresist pattern as a mask. The photoresist pattern is removed. Thereby, the piezoelectric element 201 is formed.

An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the vibration plate 203. The interlayer insulating film 214 is, for example, an Al ₂ O ₃ film formed by an ALD (Atomic Layer Deposition) method.

(5) An interlayer insulating film 204 is formed on the interlayer insulating film 214. The interlayer insulating film 204 is a silicon oxide film formed by, for example, a CVD method. Connection holes for forming the upper electrode layer wiring connection portion 215 and the lower electrode layer wiring connection portion 216 used for propagation of signals of the external circuit are formed in the interlayer insulating films 204 and 214, for example, by photolithography and etching techniques. Form. A conductive material is formed in the connection hole and on the interlayer insulating film 204. The conductive material is patterned to form wirings 205 and 206 having a desired pattern.

  A passivation protective film 207 is formed on the interlayer insulating film 204 and the wirings 205 and 206 as an insulating protective film for the wirings 205 and 206. The passivation protective film 207 is, for example, a silicon nitride film (SiN film) formed by a plasma CVD method.

In the present embodiment, in order to increase the displacement efficiency of the piezoelectric element 201, the passivation protection film 207 and the interlayer insulating film 204 in a desired region of the region facing the pressurized liquid chamber 202 are removed by photolithography and etching technology. To form an opening. In addition, the passivation film 207, the interlayer insulating films 204 and 214, and the vibration plate 203 in the region serving as the ink supply port are removed by photolithography and etching techniques to form the ink supply port.
Thereby, formation of the actuator substrate 200 is completed.

(6) The subframe substrate 400 is disposed on the actuator substrate 200. The subframe substrate 400 is, for example, a silicon wafer having a plane orientation of <100> and a thickness of 400 μm. The subframe substrate 400 includes an actuator protection cavity 401 formed of a recess formed in a region corresponding to the piezoelectric element 201, and a subframe bonding portion 402 bonded to the actuator substrate 200. The actuator substrate 200 is formed with an opening for mounting a drive IC (not shown), an ink supply hole for supplying ink from the outside, an alignment mark for alignment, and the like. Each component of the actuator substrate 200 is formed by, for example, a photolithography technique and an etching technique.

  An adhesive 502 is applied to the lower surface of the subframe joint portion 402 of the subframe substrate 400 disposed on the actuator substrate 200. The adhesive 502 is applied only to the convex pattern portion of the joint surface (the lower surface of the subframe joint portion 402), for example, by a known flexographic printing technique. The thickness of the adhesive 502 is, for example, 3 μm.

(7) Using the wafer bonding apparatus, the actuator substrate 200 and the sub-frame substrate 400 are bonded via an adhesive 502 (not shown). In forming the pressurized liquid chamber 202 on the flow path forming substrate 208, the flow path forming substrate 208 is polished in order to set the flow path forming substrate 208 to a desired liquid chamber height. A resist pattern 503 for forming a pressurized liquid chamber is formed on the back surface of the flow path forming substrate 208 by photolithography.

(8) A portion of the flow path forming substrate 208 is removed by an etching technique using the resist pattern 503 as a mask, and the pressurized liquid chamber 202 and the partition 209 are formed. The pressurized liquid chamber 202 is formed at a position communicating with the ink supply port (see FIG. 2 (5)). The resist pattern 503 is removed.

(9) The nozzle substrate 300 in which the nozzle holes 301 are formed is bonded to the back surface of the actuator substrate 200 (the lower surface of the flow path forming substrate 208) using, for example, an adhesive. Thereby, the formation of the droplet discharge head shown in FIG. 1 is completed.

  FIG. 5 is a schematic plan view and a cross-sectional view for explaining an embodiment of a droplet discharge head provided with another embodiment of the piezoelectric actuator device. In FIG. 5, the cross-sectional view corresponds to the B-B ′ position in the plan view. In the plan view of FIG. 5, the interlayer insulating film, the passivation protective film, and the subframe substrate are not shown. An exploded perspective view of this embodiment is the same as FIG.

  The droplet discharge head of this embodiment further includes an interlayer insulating film 217 as compared with the droplet discharge head shown in FIG. The interlayer insulating film 217 is for electrically insulating the lower electrode layer 211 and the upper electrode layer 213 from each other.

  The piezoelectric layer 212 is disposed only in a region facing the pressurized liquid chamber 202. The upper electrode layer 213 is formed on the piezoelectric layer 212 and the interlayer insulating film 217. The upper electrode layer 213 is disposed on the piezoelectric layer 212, that is, across the region facing the pressurized liquid chamber 202 from the region outside the region (the region above the partition wall 209).

  In the droplet discharge head of this embodiment, the piezoelectric layer 212 that is the deformation operation source is not disposed below the upper electrode layer wiring connection portion 215, and the upper electrode layer wiring connection portion 215 forms the interlayer insulating film 217 and the vibration plate 203. The structure fixed to the flow-path formation board | substrate 208 via is implement | achieved. Thereby, the displacement (deformation) of the upper electrode layer wiring connection portion 215 is suppressed, and a defect due to peeling of the upper electrode layer wiring connection portion 215 is prevented.

  Furthermore, in the piezoelectric element 201, since the upper electrode layer wiring connection part 215 is not disposed on the piezoelectric layer 212, suppression of the displacement amount of the piezoelectric element 201 is reduced. Thereby, the displacement amount per unit drive voltage of the piezoelectric element 201 in the droplet discharge head of this embodiment is improved more than that in the droplet discharge head shown in FIG.

  6 and 7 are schematic cross-sectional views for explaining a part of an example of a process for forming the liquid discharge head shown in FIG. 6 and 7 correspond to the position B-B ′ in the plan view of FIG. 5. With reference to FIG.6 and FIG.7, this formation process example is demonstrated. The parentheses for each step described below correspond to the parentheses in FIGS. The steps (1) to (2) and the steps (5) to (9) in this example of the forming step are the same as the steps (1) to (2) and the steps (5) to (9) described above. Description is omitted.

(3-1-1) The diaphragm 203 and the lower electrode are formed on the flow path forming substrate 208 in the same manner as the steps (1) and (2) described with reference to FIGS. A layer 211 and a piezoelectric layer 212 are formed. An SRO layer 213a that is a part of the upper electrode layer 213 (see FIG. 5) is formed on the piezoelectric layer 212 by sputtering. A photoresist pattern 504 for patterning the SRO layer 213a is formed on the SRO layer 213a by photolithography.

(3-1-2) The SRO layer 213a is patterned by the etching technique using the photoresist pattern 504 as a mask. The photoresist pattern 501 is removed. Thereafter, the piezoelectric layer 212 and the lower electrode layer 211 are patterned in the same manner as the patterning step of the piezoelectric layer 212 and the lower electrode layer 211 in the step (4) described with reference to FIG. The SRO layer 213a remains on the piezoelectric layer 212.

(3-1-3) An interlayer insulating film 217 that covers the lower electrode layer 211, the piezoelectric layer 212, and the SRO layer 213a is formed on the vibration plate 203. The interlayer insulating film 217 is an Al ₂ O ₃ film formed by ALD, for example.

(3-1-4) A photoresist pattern 505 having an opening corresponding to the formation region of the SRO layer 213a is formed by photolithography. The interlayer insulating film 217 on the SRO layer 213a is removed by an etching technique using the photoresist pattern 505 as a mask.

(3-1-5) The photoresist pattern 505 is removed. By sputtering, an SRO layer and a Pt layer are sequentially formed, and an upper electrode layer 213 is formed. The upper electrode layer 213 is patterned into a desired pattern by photolithography and etching techniques to form the upper electrode layer 213 that bears a part of the wiring. Thereby, the piezoelectric element 201 is formed.

(4-1) An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the interlayer insulating film 217. The interlayer insulating film 214 is, for example, an Al ₂ O ₃ film formed by the ALD method.

  After the step (4-1), the droplet discharge shown in FIG. 5 is performed through steps according to the steps (5) to (9) described above with reference to FIGS. The formation of the head is completed.

  FIG. 8 is a schematic plan view and cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. In FIG. 8, the cross-sectional view corresponds to the C-C ′ position in the plan view. In the plan view of FIG. 8, the interlayer insulating film, the passivation protective film, and the subframe substrate are not shown. An exploded perspective view of this embodiment is the same as FIG.

  The droplet discharge head of this embodiment further includes a dummy lower electrode layer 218 and a dummy piezoelectric layer 219, as compared with the droplet discharge head shown in FIG.

  The dummy piezoelectric layer 219 is simultaneously formed of the same material as the piezoelectric layer 212 below the upper electrode layer wiring connection portion 215 and immediately below the upper electrode layer 213, and is disposed at a distance from the piezoelectric layer 212. Is.

  The dummy lower electrode layer 218 is formed of the same material as that of the lower electrode layer 211 immediately below the dummy piezoelectric layer 219, and is disposed with a space from the lower electrode layer 211.

  The dummy piezoelectric layer 219 and the dummy lower electrode layer 218 are connected to the upper electrode layer wiring even if the connection hole penetrates the upper electrode layer 213 when forming the connection hole for forming the upper electrode layer wiring connection portion 215. The portion 215 functions so as not to cause an electrical connection failure. Thereby, in the droplet discharge head of this embodiment, in addition to the effect of the droplet discharge head shown in FIG. 5, the upper electrode layer wiring connection portion 215 is electrically stabilized, and the electrical defects are reduced. .

  FIG. 9 and FIG. 10 are schematic cross-sectional views for explaining a part of the example of the process of forming the liquid discharge head shown in FIG. 9 and 10 correspond to the C-C 'position in the plan view of FIG. With reference to FIG.9 and FIG.10, this example of a formation process is demonstrated. The parentheses for each step described below correspond to the parentheses in FIGS. 9 and 10. The steps (1) to (2) and the steps (5) to (9) in this example of the forming step are the same as the steps (1) to (2) and the steps (5) to (9) described above. Description is omitted.

(3-2-1) In the same manner as the above steps (1) and (2) described with reference to FIGS. 2 (1) and 2 (2), the diaphragm 203 and the lower electrode are formed on the flow path forming substrate 208. A layer 211 and a piezoelectric layer 212 are formed. An SRO layer 213a which is a part of the upper electrode layer 213 (see FIG. 8) is formed on the piezoelectric layer 212 by sputtering. A photoresist pattern 506 for patterning the SRO layer 213a is formed on the SRO layer 213a by photolithography.

(3-2-2) The SRO layer 213a is patterned by the etching technique using the photoresist pattern 506 as a mask. The photoresist pattern 506 is removed. Thereafter, the piezoelectric layer 212 and the lower electrode layer 211 are patterned in the same manner as the patterning step of the piezoelectric layer 212 and the lower electrode layer 211 in the step (4) described with reference to FIG. Simultaneously with the formation of the pattern of the piezoelectric layer 212, the dummy piezoelectric layer 219 is formed. Simultaneously with the formation of the pattern of the lower electrode layer 211, the dummy lower electrode layer 218 is formed. The SRO layer 213a remains on the piezoelectric layer 212 and the dummy piezoelectric layer 219.

(3-2-3) An interlayer insulating film 217 that covers the lower electrode layer 211, the piezoelectric layer 212, the SRO layer 213a, the dummy lower electrode layer 218, and the dummy piezoelectric layer 219 is formed on the vibration plate 203. The interlayer insulating film 217 is an Al ₂ O ₃ film formed by ALD, for example.

(3-2-4) By the photoengraving technique, an opening corresponding to the formation region of the SRO layer 213a on the piezoelectric layer 212 and an opening corresponding to the formation region of the SRO layer 213a on the dummy piezoelectric layer 219 are provided. A photoresist pattern 507 is formed. The interlayer insulating film 217 on the SRO layer 213a is removed by an etching technique using the photoresist pattern 507 as a mask.

(3-2-5) The photoresist pattern 507 is removed. By sputtering, an SRO layer and a Pt layer are sequentially formed, and an upper electrode layer 213 is formed. The upper electrode layer 213 is patterned into a desired pattern by photolithography and etching techniques to form the upper electrode layer 213 that bears a part of the wiring. The upper electrode layer 213 is disposed over the dummy piezoelectric layer 219 from the piezoelectric layer 212 through the interlayer insulating film 217. Thereby, the piezoelectric element 201 is formed.

(4-2) An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the interlayer insulating film 217. The interlayer insulating film 214 is, for example, an Al ₂ O ₃ film formed by the ALD method.

  After the step (4-1), the droplet discharge shown in FIG. 8 is performed through steps according to the steps (5) to (9) described above with reference to FIGS. The formation of the head is completed.

  FIG. 11 is a schematic plan view and cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. In FIG. 11, the cross-sectional view corresponds to the D-D ′ position in the plan view. In the plan view of FIG. 11, illustration of an interlayer insulating film, a passivation protective film, and a subframe substrate is omitted. An exploded perspective view of this embodiment is the same as FIG.

  The droplet discharge head of this embodiment does not include the dummy piezoelectric layer 219 as compared with the droplet discharge head shown in FIG. A dummy lower electrode layer 218 formed simultaneously with the same material as the lower electrode layer 211 and spaced from the lower electrode layer 211 is disposed directly below the upper electrode layer 213 below the upper electrode layer wiring connection portion 215. Has been.

  The dummy lower electrode layer 218 is electrically connected to the upper electrode layer wiring connection portion 215 even if the connection hole penetrates the upper electrode layer 213 when the connection hole for forming the upper electrode layer wiring connection portion 215 is formed. Functions so as not to cause poor connection. Thereby, in the droplet discharge head of this embodiment, in addition to the effect of the droplet discharge head shown in FIG. 5, the upper electrode layer wiring connection portion 215 is electrically stabilized, and the electrical defects are reduced. .

  12 and 13 are schematic cross-sectional views for explaining a part of a process example of forming the liquid discharge head shown in FIG. 12 and 13 correspond to the D-D ′ position in the plan view of FIG. 11. With reference to FIG.12 and FIG.13, this formation process example is demonstrated. The parentheses for each step described below correspond to the parentheses in FIGS. The steps (1) to (2) and the steps (5) to (9) in this example of the forming step are the same as the steps (1) to (2) and the steps (5) to (9) described above. Description is omitted.

(3-3-1) The diaphragm 203 and the lower electrode are formed on the flow path forming substrate 208 in the same manner as the above steps (1) and (2) described with reference to FIGS. A layer 211 and a piezoelectric layer 212 are formed. An SRO layer 213a that is a part of the upper electrode layer 213 (see FIG. 11) is formed on the piezoelectric layer 212 by sputtering. A photoresist pattern 508 for patterning the SRO layer 213a is formed on the SRO layer 213a by photolithography. The photoresist pattern 508 is not formed in a region where the dummy lower electrode layer 218 is to be formed.

(3-3-2) The SRO layer 213a is patterned by the etching technique using the photoresist pattern 508 as a mask. The photoresist pattern 508 is removed. Thereafter, the piezoelectric layer 212 and the lower electrode layer 211 are patterned in the same manner as the patterning step of the piezoelectric layer 212 and the lower electrode layer 211 in the step (4) described with reference to FIG. When forming the pattern of the piezoelectric layer 212, the piezoelectric layer 212 in the region where the dummy lower electrode layer 218 is to be formed is removed. Simultaneously with the formation of the pattern of the lower electrode layer 211, the dummy lower electrode layer 218 is formed. The SRO layer 213a remains on the piezoelectric layer 212.

(3-3-3) An interlayer insulating film 217 that covers the lower electrode layer 211, the piezoelectric layer 212, the SRO layer 213a, and the dummy lower electrode layer 218 is formed on the vibration plate 203. The interlayer insulating film 217 is an Al ₂ O ₃ film formed by ALD, for example.

(3-3-4) A photoresist pattern 509 having an opening corresponding to the formation region of the SRO layer 213a on the piezoelectric layer 212 and an opening corresponding to the formation region of the dummy lower electrode layer 218 is formed by photolithography. Form. The interlayer insulating film 217 on the SRO layer 213a and the interlayer insulating film 217 on the dummy lower electrode layer 218 are removed by etching technique using the photoresist pattern 509 as a mask.

(3-3-5) The photoresist pattern 509 is removed. By sputtering, an SRO layer and a Pt layer are sequentially formed, and an upper electrode layer 213 is formed. The upper electrode layer 213 is patterned into a desired pattern by photolithography and etching techniques to form the upper electrode layer 213 that bears a part of the wiring. The upper electrode layer 213 is disposed over the dummy lower electrode layer 218 via the interlayer insulating film 217 from the piezoelectric layer 212. Thereby, the piezoelectric element 201 is formed.

(4-3) An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the interlayer insulating film 217. The interlayer insulating film 214 is, for example, an Al ₂ O ₃ film formed by the ALD method.

  After the step (4-1), the droplet discharge shown in FIG. 11 is performed through steps according to the steps (5) to (9) described with reference to FIGS. 2, 3 and 4 above. The formation of the head is completed.

  FIG. 14 is a schematic plan view and cross-sectional view for explaining an embodiment of a droplet discharge head provided with still another embodiment of the piezoelectric actuator device. In FIG. 14, the cross-sectional view corresponds to the E-E ′ position in the plan view. In the plan view of FIG. 14, illustration of an interlayer insulating film, a passivation protective film, and a subframe substrate is omitted. An exploded perspective view of this embodiment is the same as FIG.

  The droplet discharge head of this embodiment further includes a buffer layer 220 embedded in a space between the piezoelectric layer and the dummy piezoelectric layer, as compared with the droplet discharge head shown in FIG. ing. The buffer layer 220 is disposed across a boundary region between a region facing the pressurized liquid chamber 202 and a region outside the region.

  In the droplet discharge head of this embodiment, the buffer layer 220 is provided in the vibration region facing the pressurized liquid chamber 202 and the fixed region facing the partition wall 209, so that the vibration displacement of the upper electrode layer 213 is reduced. It can be suppressed. Furthermore, since the buffer layer 220 reduces the step formed in the upper electrode layer 213 which is a thin film, the probability of the upper electrode layer 213 becoming defective in conduction is reduced. Therefore, the droplet discharge head of this embodiment can further improve the electrical reliability of the droplet discharge head in addition to the effects of the droplet discharge head shown in FIG.

  FIG. 15 and FIG. 16 are schematic cross-sectional views for explaining a part of an example of the liquid discharge head forming process shown in FIG. 15 and 16 correspond to the E-E 'position in the plan view of FIG. With reference to FIGS. 15 and 16, an example of this forming process will be described. The parentheses for each step described below correspond to the parentheses in FIGS. 15 and 16. The steps (1) to (2) and the steps (5) to (9) in this example of the forming step are the same as the steps (1) to (2) and the steps (5) to (9) described above. Description is omitted.

(3-4-1) The vibration plate 203, the lower electrode layer 211, and the piezoelectric layer 212 are formed on the flow path forming substrate 208 in the same manner as in the step (3-2-1) described with reference to FIG. Then, an SRO layer 213a and a photoresist pattern 506 are formed.

(3-2-2) The SRO layer 213a, the piezoelectric layer 212, and the lower electrode layer 211 are patterned in the same manner as in the step (3-2-2) described with reference to FIG. Each pattern of the SRO layer 213a, the piezoelectric layer 212, the dummy piezoelectric layer 219, the lower electrode layer 211, and the dummy lower electrode layer 218 is formed.

(3-2-3) The interlayer insulating film 217 is formed in the same manner as in the above step (3-2-3) described with reference to FIG. A buffer layer 220 is formed on the interlayer insulating film 217. The buffer layer 220 is left in a desired region by a photoengraving technique and an etching technique, or by an etchback technique. The buffer layer 220 is, for example, a low-density silicon oxide formed by a CVD method. However, the material of the buffer layer 220 is not limited to this.

(3-2-4) A photoresist pattern 507 is formed in the same manner as the step (3-2-4) described with reference to FIG. A photoresist pattern 507 is also formed on the buffer layer 220. The interlayer insulating film 217 on the SRO layer 213a is removed by an etching technique using the photoresist pattern 507 as a mask.

(3-2-5) The photoresist pattern 507 is removed. By sputtering, an SRO layer and a Pt layer are sequentially formed, and an upper electrode layer 213 is formed. The upper electrode layer 213 is also formed on the buffer layer 220. The upper electrode layer 213 is patterned into a desired pattern by photolithography and etching techniques to form the upper electrode layer 213 that bears a part of the wiring. The upper electrode layer 213 is disposed across the dummy piezoelectric layer 219 from the piezoelectric layer 212 through the interlayer insulating film 217 and the buffer layer 220. Thereby, the piezoelectric element 201 is formed.

(4-2) An interlayer insulating film 214 that covers the piezoelectric element 201 is formed on the interlayer insulating film 217. The interlayer insulating film 214 is, for example, an Al ₂ O ₃ film formed by the ALD method.

  After the step (4-1), the droplet discharge shown in FIG. 14 is performed through steps according to the steps (5) to (9) described above with reference to FIGS. 2, 3 and 4. The formation of the head is completed.

Next, an embodiment of the image forming apparatus will be described with reference to FIGS.
FIG. 17 is a schematic side view for explaining the overall configuration of the apparatus. FIG. 18 is a schematic plan view of an essential part of the apparatus.

  In this image forming apparatus, a carriage 103 is slidably held in a main scanning direction by a guide rod 101 and a guide rail 102 which are horizontally disposed on left and right side plates (not shown). The carriage 103 is moved and scanned in the direction indicated by the arrow (main scanning direction) via the timing belt 105 by the main scanning motor 104.

  For example, a recording head 107 composed of four droplet ejection heads is arranged on the carriage 103 in such a manner that a plurality of ink ejection openings are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed downward. Yes. The four droplet discharge heads discharge, for example, ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). In addition, as a droplet discharge head constituting the recording head 107, a droplet discharge head using a piezoelectric actuator such as a piezoelectric element is used.

  The carriage 103 is also equipped with a sub-tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) through an ink supply tube (not shown).

  In this embodiment, the sub-tank 108 and the recording head 107 constitute the liquid droplet ejection apparatus according to the present invention. However, the recording head 107 is composed of the liquid droplet ejection head according to the present invention, and the sub-tank 108 is separately provided. You can also Alternatively, an ink cartridge can be mounted without using a sub tank.

  On the other hand, a half-moon roller (sheet feeding roller) 113 and a separation pad 114 are provided as a sheet feeding unit for feeding sheets 112 stacked on a sheet stacking unit (pressure plate) 111 such as a sheet feeding cassette 110. The paper feed roller 113 is for separating and feeding the sheets 112 from the sheet stacking unit 111 one by one. The separation pad 114 is disposed to face the paper feed roller 113 and is formed of a material having a large friction coefficient. The separation pad 114 is biased toward the paper feed roller 113 side.

  As a conveyance unit for conveying the paper 112 fed from the paper supply unit below the recording head 107, a conveyance belt 121, a counter roller 122, a conveyance guide 123, a pressing member 124, a tip end And a pressure roller 125. The transport belt 121 is for transporting the paper 112 by electrostatic adsorption. The counter roller 122 is for conveying the paper 112 fed from the paper supply unit via the guide 115 with the conveyance belt 121 interposed therebetween. The conveyance guide 123 is to change the direction of the sheet 112 fed substantially vertically upward by approximately 90 ° and follow the conveyance belt 121. The tip pressurizing roller 125 is urged toward the transport belt 121 by the pressing member 124. Further, a charging roller 126 that is a charging unit for charging the surface of the conveyance belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt. The conveyor belt 121 is stretched between the conveyor roller 127 and the tension roller 128. The transport roller 127 is rotated from the sub-scanning motor 131 through the timing belt 132 and the timing roller 133. Thereby, the conveyance belt 121 is configured to circulate in the belt conveyance direction (sub-scanning direction) in FIG. A guide member 129 is disposed on the back side of the conveying belt 121 so as to correspond to an image forming area formed by the recording head 107.

  As shown in FIG. 11, a slit disk 134 is attached to the shaft of the transport roller 127, and a sensor 135 for detecting the slit of the slit disk 134 is provided. An encoder 136 is configured.

  The charging roller 126 is arranged so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121, and applies 2.5N to both ends of the shaft as a pressing force.

  Further, an encoder scale 142 having slits is provided on the front side of the carriage 103 as shown in FIG. An encoder sensor 143 is provided on the front side of the carriage 103. The encoder sensor 143 is a transmissive photosensor that detects a slit of the encoder scale 142. The encoder scale 142 and the encoder sensor 143 constitute an encoder 144 for detecting the position of the carriage 103 in the main scanning direction (position relative to the home position).

  Further, as a paper discharge unit for discharging the paper 112 recorded by the recording head 107, a separation unit for separating the paper 112 from the conveying belt 121, a paper discharge roller 152 and a paper discharge roller 153, and paper discharge And a paper discharge tray 154 for stocking the paper 112 to be used.

  A double-sided paper feeding unit 161 is detachably attached to the back. The double-sided paper feeding unit 161 takes in and reverses the paper 112 returned by the reverse rotation of the transport belt 121 and feeds it again between the counter roller 122 and the transport belt 121.

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit. The paper 112 fed substantially vertically upward is guided by the guide 115 and is transported while being sandwiched between the transport belt 121 and the counter roller 122. Further, the leading edge of the paper 112 is guided by the transport guide 123 and pressed against the transport belt 121 by the front end pressure roller 125, and the transport direction is changed by approximately 90 °.

  At this time, an alternating voltage is applied to the charging roller 126 by a control circuit (not shown) so that a positive output and a negative output are alternately repeated from a high voltage power source. As a result, the charging voltage pattern in which the conveyor belt 121 alternates, that is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction that is the circumferential direction. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Therefore, by driving the recording head 107 according to the image signal while moving the carriage 103, ink droplets are ejected onto the stopped paper 112 to record one line, and after the paper 112 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 112 has reached the recording area, the recording operation is finished, and the paper 112 is discharged onto the paper discharge tray 154.

  In the case of duplex printing, the conveyance belt 121 is reversely rotated when the recording of the front surface (surface to be printed first) is completed. As a result, the recorded paper 112 is fed into the double-sided paper feeding unit 161. The paper 112 is reversed (the back surface is set to be a printing surface) and fed again between the counter roller 122 and the conveyance belt 121. Timing control is performed, and the sheet 112 is conveyed onto the conveyance belt 121 and recorded on the back surface, and then discharged to the discharge tray 154 in the same manner as the recording operation described above.

  Note that the image forming apparatus according to the present invention can also be applied to a printer, a facsimile machine, a copying machine, a complex machine of these, and the like. The image forming apparatus according to the present invention is also applied to a liquid droplet discharge head or liquid droplet discharge apparatus that discharges a liquid other than ink, such as a DNA sample, a resist, or a pattern material, or an image forming apparatus that includes these. be able to.

  As mentioned above, although the Example of this invention was described, the numerical value, material, arrangement | positioning, number, etc. in the said Example are examples, This invention is not limited to these, It was described in the claim Various modifications are possible within the scope of the present invention.

  In each of the above examples, the material of each constituent film and the example of the film forming method are shown. However, each constituent film may be a film having each functional performance, and the materials and constituents described in the above examples may be used. It is not limited to the membrane method.

201 Piezoelectric element 202 Pressurized liquid chamber 203 Diaphragm 208 Flow path forming substrate 211 Lower electrode layer 212 Piezoelectric layer 213 Upper electrode layer 215 Upper electrode layer wiring connection portion 218 Dummy lower electrode layer 219 Dummy piezoelectric layer 220 Buffer layer 301 Nozzle Hole

Japanese Patent No. 3114808

Claims (9)

A nozzle hole, a flow path forming substrate having a pressurized liquid chamber communicating with the nozzle hole, a diaphragm forming one surface of the pressurized liquid chamber, and a lower electrode layer sequentially laminated on the diaphragm; In a piezoelectric actuator device comprising a piezoelectric layer and a piezoelectric element having an upper electrode layer,
All of the piezoelectric layer is disposed on the lower electrode layer,
At least the upper electrode layer is disposed across a region outside the region from a region facing the pressurized liquid chamber,
The piezoelectric actuator device according to claim 1, wherein an upper electrode layer wiring connecting portion for supplying a potential to the upper electrode layer is disposed at a position outside a region facing the pressurized liquid chamber.   The piezoelectric actuator device according to claim 1, wherein the piezoelectric layer is arranged only in a region facing the pressurized liquid chamber.   Below the upper electrode layer wiring connection portion, a dummy piezoelectric layer that is simultaneously formed of the same material as the piezoelectric layer and is spaced apart from the piezoelectric layer is disposed immediately below the upper electrode layer. The piezoelectric actuator device according to claim 2.   4. The piezoelectric actuator according to claim 3, wherein a dummy lower electrode layer that is simultaneously formed of the same material as the lower electrode layer and is spaced apart from the lower electrode layer is disposed immediately below the dummy piezoelectric layer. apparatus.   The piezoelectric actuator device according to claim 3 or 4, wherein a buffer layer for reducing a step formed in the upper electrode layer is embedded in a space between the piezoelectric layer and the dummy piezoelectric layer.   Below the upper electrode layer wiring connection portion, a dummy lower electrode layer formed simultaneously with the same material as the lower electrode layer and spaced from the lower electrode layer is disposed immediately below the upper electrode layer. The piezoelectric actuator device according to claim 2.   A liquid droplet ejection head comprising the piezoelectric actuator device according to claim 1. In an ink cartridge in which a droplet discharge head for discharging droplets and a liquid tank for supplying liquid to the droplet discharge head are integrated,
An ink cartridge, wherein the droplet discharge head is the droplet discharge head according to claim 7. In an image forming apparatus provided with a droplet discharge head for discharging droplets,
An image forming apparatus, wherein the droplet discharge head is the droplet discharge head according to claim 7.

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