JP5671899B2 - Piezoelectric actuator, liquid discharge head, and image forming apparatus - Google Patents

Description

  The present invention relates to a piezoelectric actuator, a liquid discharge head, and an image forming apparatus.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. An apparatus (for example, an ink jet recording apparatus) is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  As a liquid discharge head, for example, a groove is formed on a piezoelectric body as pressure generating means for generating pressure by applying ink, which is liquid in a liquid chamber, in particular, a laminated piezoelectric member in which piezoelectric layers and internal electrodes are alternately stacked. A piezoelectric actuator having a plurality of columnar piezoelectric elements (piezoelectric columns) applied thereto, and deforming an elastically deformable diaphragm that forms a wall surface in the liquid chamber by displacement of the laminated piezoelectric member in the direction d33 or d31. A so-called piezoelectric head that discharges droplets by changing the volume and pressure in the room is known.

  Then, a wiring member on which a driver IC is mounted, for example, a flexible printed circuit board (hereinafter referred to as “FPC”) is connected to each piezoelectric column of the piezoelectric actuator.

  Here, a plurality of wiring patterns are provided in parallel in the FPC so as to correspond to the respective piezoelectric columns. However, since each wiring pattern is very fine, the FPC wiring pattern and the electrodes of the piezoelectric columns There is a possibility that the bonding strength of the material is insufficient and peeling of the bonding occurs.

  Therefore, conventionally, it is known that an FPC and a base member to which a piezoelectric member is fixed are joined with a hot melt adhesive, and the hot melt adhesive is melted by laser light (Patent Document 1).

JP 2008-218963 A

  However, when the hot melt adhesive is directly heated and melted with a laser as disclosed in Patent Document 1 described above, a large heating amount is required. It becomes larger and the FPC itself is damaged or burnt.

  Moreover, the melt unevenness of the hot melt adhesive occurs depending on the melted part, and in the part where the melt amount is large, the hot melt spreads to the joint portion between the FPC and the piezoelectric column, which affects the driving of the piezoelectric column, while the melt amount In a portion where the FPC is small, the bonding strength between the FPC and the base member cannot be sufficiently obtained, and there is a problem that peeling of the bonding portion between the FPC and the piezoelectric column occurs.

  The present invention has been made in view of the above problems, and an object thereof is to ensure sufficient bonding strength between a wiring member and a piezoelectric column without causing damage to the wiring member.

In order to solve the above problems, the piezoelectric actuator according to the present invention is:
A piezoelectric member formed with a plurality of piezoelectric columns;
A base member to which the piezoelectric member is fixed;
A wiring member formed with a wiring pattern for transmitting a drive signal to the piezoelectric pillar of the piezoelectric member,
The wiring member is provided with a bonding electrode pattern that does not contribute to transmission of a drive signal at a position corresponding to a bonding portion between the base member and the wiring member.
The wiring member is configured to be bonded and fixed to the wall surface of the base member with a hot-melt adhesive at the bonding portion.

  The liquid discharge head according to the present invention includes the piezoelectric actuator according to the present invention.

  The image forming apparatus according to the present invention includes the liquid discharge head according to the present invention.

According to the piezoelectric actuator according to the present invention, heating unevenness is reduced with sufficient heating amount obtained when Les Za bonding, without causing damage to the wiring member, a sufficient bonding strength of the wiring member and the piezoelectric column It can be secured.

  According to the liquid discharge head according to the present invention, the piezoelectric actuator according to the present invention is provided, so that the reliability is improved.

  According to the image forming apparatus of the present invention, since the liquid discharge head according to the present invention is provided, stable image formation can be performed.

FIG. 3 is an exploded perspective view illustrating an example of a liquid discharge head according to the first embodiment of the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is sectional explanatory drawing of the bipitch structure along the liquid chamber transversal direction of the head. It is sectional explanatory drawing of the normal pitch structure along the liquid chamber transversal direction of the head. It is a plane explanatory view of the piezoelectric actuator used for explanation of the FPC holding structure in the head. It is front explanatory drawing of FIG. It is side explanatory drawing of FIG. It is explanatory drawing with which it uses for description of the joining method to the base member of FPC similarly. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory side view illustrating an overall configuration showing an example of an image forming apparatus equipped with a liquid discharge head according to the present invention. Similarly it is principal part plane explanatory drawing.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head including a piezoelectric actuator according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional explanatory view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIGS. 3 and 4 are nozzle arrangement directions of the head. It is sectional explanatory drawing of the different example along (liquid chamber transversal direction).

  The liquid discharge head includes a flow path substrate (liquid chamber substrate) 1 formed of a SUS substrate, a vibration plate member 2 bonded to the lower surface of the flow path substrate 1, and a nozzle plate 3 bonded to the upper surface of the flow path substrate 1. And a plurality of nozzles 4 for ejecting droplets (liquid droplets) by these, respectively, as a plurality of liquid chambers (pressurized liquid chamber, pressure chamber, Also referred to as a pressure chamber, a flow path, etc.) 6, a fluid resistance portion 7 that also serves as a supply path for supplying ink to the liquid chamber 6, and a communication portion 8 that communicates with the liquid chamber 6 via the fluid resistance portion 7. Ink is supplied from a common liquid chamber 10 formed in a frame member 17 to be described later to the communication portion 8 through a supply port 9 formed in the diaphragm member 2.

  The flow path substrate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path substrate 1 is formed by etching the SUS substrate using an acidic etchant or machining such as punching (pressing) to open openings such as the communication path 5, the pressurized liquid chamber 6, and the fluid resistance portion 7. Each is formed.

  The diaphragm member 2 has each vibration region (diaphragm portion) 2a that forms a wall surface corresponding to each liquid chamber 6, and an island-shaped convex portion on the outer side of the vibration region 2a (on the side opposite to the liquid chamber 6). 2b is provided, and the upper end surfaces (joint surfaces) of the piezoelectric columns 12A and 12B of the laminated piezoelectric member 12 as drive means (actuator means, pressure generating means) for deforming the vibration region 2a are joined to the island-shaped convex portions 2b. doing. The lower end surface of the multilayer piezoelectric member 12 is joined to the base member 13.

  Here, the piezoelectric member 12 is formed by alternately laminating piezoelectric material layers 21 and internal electrodes 22a and 22b, and the internal electrodes 22a and 22b are respectively end surfaces, that is, side surfaces substantially perpendicular to the diaphragm 2 of the piezoelectric element 12. Are connected to the end face electrodes (external electrodes) 23 and 24 formed on the side surfaces, and a voltage is applied between the end face electrodes (external electrodes) 23 and 24 to cause displacement in the stacking direction. Here, the external electrode 23 is used as an individual external electrode (individual electrode), and the external electrode 24 is used as a common external electrode (common electrode).

  This piezoelectric member 12 is obtained by forming grooves by half-cut dicing and forming a required number of piezoelectric columns 12A and 12B in a comb-like shape at a predetermined interval with respect to one piezoelectric member.

  The piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, but the piezoelectric column that is driven by giving a driving waveform is the driving piezoelectric column 12A, and the piezoelectric column that is used as a simple column without giving the driving waveform is not driven. It is distinguished as the piezoelectric column 12B. In this case, as shown in FIG. 3, the bi-pitch configuration in which the driving piezoelectric columns 12A and the non-driving piezoelectric columns 12B are used alternately, or all the piezoelectric columns are used as the driving piezoelectric columns 12A as shown in FIG. Any of the normal pitch configurations can be used.

  The piezoelectric member 12 is connected to an FPC 15 as a flexible wiring member for giving a driving signal to the driving piezoelectric column 12A. The FPC 15 is bonded to the base member 13 with a hot melt adhesive 16 in the vicinity of the piezoelectric member 12.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the respective liquid chambers 6 and bonded to the flow path plate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  This head is configured to pressurize the ink in the liquid chamber 6 using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric member 12, and the discharge direction of the liquid droplets is the flow direction of the recording liquid in the liquid chamber 6. The liquid droplets are ejected by different side shooter methods. By adopting the side shooter system, the size of the piezoelectric member 12 becomes substantially the size of the head, and the miniaturization of the piezoelectric member 12 can be directly linked to the miniaturization of the head, and the head can be easily miniaturized.

  Further, a frame member 17 formed by injection molding with an epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the actuator portion composed of the piezoelectric member 12, the base member 13, the FPC 15, and the like. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port 19 for supplying a recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as an ink cartridge.

  In the liquid ejection head configured as described above, for example, when driven by a pushing method, a drive pulse voltage of 20 to 50 V is selectively applied to the drive piezoelectric column 12A according to an image recorded from a control unit (not shown). As a result, the driving piezoelectric column 12A to which the pulse voltage is applied is displaced to deform the vibration region 2a of the vibration plate 2 in the direction of the nozzle plate 3, and the liquid in the liquid chamber 6 is changed by the volume (volume) change of the liquid chamber 6. , The droplets are ejected from the nozzles 4 of the nozzle plate 3. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, the application of voltage to the drive piezoelectric column 12A is turned off, so that the diaphragm 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. . At this time, ink is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  In addition to the above-described pushing, the liquid ejection head is not limited to the pulling method (a method of releasing the diaphragm 2 from the pulled state and pressurizing it with a restoring force), and the pulling-pushing method (the diaphragm 2 at the intermediate position). It is also possible to drive by pulling from this position and then extruding.

  Next, an FPC holding structure in the liquid discharge head will be described with reference to FIGS. 5 is an explanatory plan view of the piezoelectric actuator, FIG. 6 is an explanatory front view of FIG. 5, and FIG. 7 is an explanatory side view of FIG. Here, the piezoelectric columns of the piezoelectric member 12 are illustrated in a bi-pitch configuration.

  In the FPC 15, a wiring pattern 31 (only the individual wiring pattern connected to the individual electrode of the driving piezoelectric column 12A is illustrated) for transmitting a driving signal is formed on a transparent base material 30 made of polyimide. . One end of the wiring pattern 31 is joined and electrically connected to the electrode of the piezoelectric pillar 12A with solder 32, and the other end is connected to a driver IC 40 mounted on the FPC 15.

  Further, on the FPC 15, a bonding electrode pattern 33, which is an electrode pattern that does not contribute to transmission of a drive signal, is formed on the base material 30 at a position corresponding to the bonding portion between the FPC 15 and the base member 13. As shown in FIG. 6, the bonding electrode pattern 33 is formed in a region that fits on the wall surface 13 a of the base member 13.

  These wiring patterns 31 and bonding electrode patterns 33 are alternately arranged at the same intervals in the pattern arrangement direction.

  The FPC 15 is joined to the wall surface 13a of the base member 13 by a hot melt adhesive 35 at the joint.

  As shown in FIG. 8, the FPC 15 is bonded to the base member 13 by irradiating the hot melt adhesive 35 with laser light from the laser head 50 through the FPC 15 and thermally melting it.

  At this time, since the bonding electrode pattern 33 is provided in the FPC 15, the hot melt adhesive 35 can be indirectly heated by heating the bonding electrode pattern 33 at the time of laser irradiation. Thereby, the heating amount of the polyimide base material 30 of the FPC 15 can be suppressed, and damage and scoring of the FPC itself can be reduced.

  Here, the bonding electrode pattern 33 only needs to absorb the laser and generate heat, and may be embedded (sandwiched) in the transparent base material 30 made of polyimide of the FPC 15, or on either side of the FPC 15. May be exposed. In the case where the bonding electrode pattern 33 is exposed on the side facing the base member 13, it is possible to use solder as a hot melt adhesive instead of the hot melt adhesive 35.

  In addition, since the hot melt adhesive 35 is indirectly heated by heating the bonding electrode pattern 33, melting unevenness of the hot melt adhesive 35 can be reduced. As a result, the adverse effect on the driving of the piezoelectric column 12A due to the spread of the hot melt adhesive 35 to the joint between the FPC 15 and the electrode of the driving column 12A can be reduced. In addition, since the bonding strength between the FPC 15 and the base member 13 can be stably obtained, it is possible to reduce peeling of the bonding portion between the FPC 15 and the piezoelectric column 12A.

  In particular, in the case of joining with solder as described above, the solder does not wet and spread in the unexposed region of the joining electrode pattern 33, so that the solder is connected to the individual electrode of the drive piezoelectric column 12A, causing a problem. Can also be prevented.

  Further, by alternately arranging the wiring pattern 31 and the bonding electrode pattern 33 at the same interval, the electrode interval becomes equal as in the bonding by the solder 32 between the wiring pattern 31 and the piezoelectric column 12A. Even in the joining with the member 13 by the hot melt adhesive 35, even if the laser head is not intermittently fed, a uniform molten state can be obtained by constant speed feeding. Therefore, using the same laser head, the FPC 15 can be electrically joined and fixed only by performing two scans, and high productivity can be maintained.

  As described above, the wiring member is provided with the joining electrode pattern corresponding to the joint portion between the base member and the wiring member, and the wiring member is fixed to the wall surface of the base member with a hot-melt adhesive. In addition, a sufficient amount of heating can be obtained when laser bonding is performed, and heating unevenness is reduced, so that sufficient bonding strength between the wiring member and the piezoelectric column can be ensured without causing damage to the wiring member.

  In this case, by connecting the electrode pattern for joining of the wiring member within the wall surface of the base member, the joint portion between the wiring member and the base member due to expansion (heating) and contraction (cooling) of the wiring member Since the expansion (heating) and contraction (cooling) of the base member itself due to the heating of the base member can be reduced, it is possible to prevent the piezoelectric column electrodes of the piezoelectric member from bending or falling. In addition, it is possible to reduce the occurrence of poor bonding due to the melted hot melt adhesive spreading to the joint portion between the wiring member and the piezoelectric column and entering. Further, it is possible to reduce the occurrence of problems in the subsequent assembling process due to the molten hot melt spreading to the bottom surface of the base member, thereby enabling more efficient bonding.

  In the above embodiment, the FPC is used as the wiring member. However, it may be a thin film and provided with a plurality of electrodes arranged in parallel with each other. For example, TAB (Tape Automated Bonding) is used. You can also.

  In addition, a head-integrated liquid tank in which the above-described liquid discharge head and a liquid tank that supplies liquid to the liquid discharge head are integrated can be configured.

Next, an example of an image forming apparatus equipped with the liquid ejection head according to the present invention will be described with reference to FIGS. 9 is an explanatory side view for explaining the overall configuration of the image forming apparatus, and FIG.
This image forming apparatus is a serial type image forming apparatus, and holds a carriage 233 slidably in a main scanning direction by main and sub guide rods 231 and 232 which are guide members horizontally mounted on left and right side plates 221A and 221B. The main scanning motor (not shown) moves and scans in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 has recording heads 234a and 234b (which are composed of liquid ejection heads according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). When not distinguished, it is referred to as “recording head 234”). 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.

  Each of the recording heads 234 has two nozzle rows. One nozzle row of the recording head 234a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 234b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. In this example, four-color droplets are ejected in a two-head configuration. However, a recording head for each color can be provided, and a nozzle row in which a plurality of nozzles ejecting four-color droplets are arranged. It is also possible to have a single recording head configuration.

  The carriage 233 is equipped with sub tanks 235a and 235b (referred to as “sub tank 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 cartridge 210 of each color via a supply tube 236 for each color by a supply unit (not shown).

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. 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 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. 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) for capping each nozzle surface of the recording head 234, and nozzle surfaces. A wiper blade 283 that is a blade member for wiping the ink, and an empty discharge receiver 284 that receives liquid droplets for discharging the liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid. ing.

  In addition, in the non-printing area on the other side in the scanning direction of the carriage 233, the liquid that receives liquid droplets when performing idle ejection that ejects liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. An ink recovery unit (empty discharge receiver) 288 that is a recovery container is disposed, and the ink recovery unit 288 includes 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 image forming apparatus includes the liquid ejection head according to the present invention, the reliability of the recording head is improved and stable recording can be performed.

  In the above-described embodiment, the present invention has been described with reference to an example in which the present invention is applied to a serial type image forming apparatus. Further, the present invention can be applied to an image forming apparatus using a liquid other than the narrowly defined ink, a fixing processing liquid, or the like.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Nozzle plate 3 Vibrating plate 4 Nozzle 6 Individual liquid chamber 10 Common liquid chamber 12 Piezoelectric member 12A, 12B Piezoelectric column 13 Base member 15 FPC (wiring member)
23 Individual Electrode 31 Wiring Pattern 33 Bonding Electrode Pattern 35 Hot Melt Adhesive 234 Carriage 235 Recording Head

Claims (6)

A piezoelectric member formed with a plurality of piezoelectric columns;
A base member to which the piezoelectric member is fixed;
A wiring member formed with a wiring pattern for transmitting a drive signal to the piezoelectric pillar of the piezoelectric member,
The wiring member is provided with a bonding electrode pattern that does not contribute to transmission of a drive signal at a position corresponding to a bonding portion between the base member and the wiring member.
The piezoelectric actuator according to claim 1, wherein the wiring member is bonded and fixed to the wall surface of the base member with a hot-melt adhesive at the bonding portion.   The piezoelectric actuator according to claim 1, wherein the bonding electrode pattern is accommodated within a wall surface of the base member.   The piezoelectric actuator according to claim 1, wherein the wiring pattern of the wiring member and the bonding electrode pattern are alternately provided in a pattern arrangement direction.   4. The piezoelectric actuator according to claim 3, wherein the wiring pattern of the wiring member and the bonding electrode pattern are alternately provided at the same interval.   A liquid discharge head comprising the piezoelectric actuator according to claim 1.   An image forming apparatus comprising the liquid discharge head according to claim 5.

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