JP2011056730A - Liquid delivering head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce variation of a displacement characteristic caused by power loss associated with elongation and high-density formation of an actuator. <P>SOLUTION: A piezoelectric member 12 has a first common external electrode 23 and an individual external electrode 23 on surfaces opposed to each other which are side surfaces to a driving surface of a piezoelectric element pillar 12A. Moreover, the piezoelectric member has a second common external electrode connected with the first common external electrode 23 on the surface where the individual external electrode 23 of the piezoelectric member 12 is formed in the piezoelectric element pillar. An FPC 15 is connected to the surface where the individual external electrode 23 of the piezoelectric member 12 is formed, thereby feeding an electricity to the individual external electrode 23 and the second common external electrode 25. The FPC has on a front end connected to the piezoelectric member 12, a common electrode wiring 32B connected astride a plurality of second common external electrodes 25 formed in a plurality of piezoelectric element pillars 12B, and an individual electrode wiring 32A arranged retreated from the front end direction from the common electrode line 32B and connected to the individual external electrode 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention particularly relates to a liquid discharge head and an image forming apparatus having a diaphragm.

  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. As an apparatus, an ink jet recording apparatus or the like 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. “Image” is not limited to a planar image (two-dimensional image), but also includes an image given to a three-dimensionally formed image, or an image formed by three-dimensionally modeling a solid itself. It is.

  As a conventional liquid discharge head, a piezoelectric body as pressure generating means for generating pressure by pressurizing ink, which is a liquid in a liquid chamber, particularly a stacked piezoelectric element in which piezoelectric layers and internal electrodes are alternately stacked is used. A so-called piezoelectric device that includes a piezoelectric actuator and deforms an elastically deformable diaphragm that forms a wall surface in a liquid chamber by displacement in the d33 or d31 direction of the multilayer piezoelectric element, and discharges droplets by changing the volume and pressure in the liquid chamber. A mold head is known.

  As a piezoelectric actuator used in such a liquid discharge head, a plurality of driving portions (driving piezoelectric element columns) and non-driving portions (non-driving piezoelectric element columns) are formed by performing groove processing on the laminated piezoelectric member. Then, a wiring electrode of a wiring board such as an FPC (flexible printed cable) is joined to an external electrode (also referred to as an end face electrode) from which the internal electrode of the laminated piezoelectric member is drawn to the end face, and each piezoelectric element column is subjected to an image signal. Some drive signals are given.

  For example, in Patent Document 1, it is possible to provide individual external electrodes and common external electrodes on the same surface by providing common external electrodes in the non-driving parts at both ends in the arrangement direction of the driving parts, and to provide a drive signal with one FPC. Yes.

  Further, in Patent Document 2, a common electrode pattern formed on a common electrode portion of an FPC cable is directly connected to a common electrode of each stacked piezoelectric element, and each individual electrode pattern is connected to a drive unit in each stacked piezoelectric element. By connecting only by solder bonding or the like, the FPC cable is directly connected to the end face electrode of the multilayer piezoelectric element.

JP-A-10-286951 JP-A-10-109410

  By the way, in order to cope with higher speed and higher image quality in the image forming apparatus, the length and density of the liquid ejection head, that is, the length and density of the piezoelectric actuator are increasing. By increasing the length of the piezoelectric actuator, a large number of piezoelectric element columns are arranged, and the power loss due to the resistance values of the internal electrode layer and the external electrode layer of the piezoelectric element increases. Therefore, there is no displacement characteristics between the piezoelectric element column in the vicinity of the common electrode wiring connected to the power supply member (wiring member) that supplies power to the piezoelectric element column and the piezoelectric element column in a part away from the part where the common electrode wiring is connected. There is a problem of being different.

  That is, as in the configuration disclosed in Patent Document 1, in the configuration in which the common external electrode is provided only at the non-driving portions at both ends of the piezoelectric member, the piezoelectric element columns near the both ends and the piezoelectric element columns at the center Then, the displacement characteristics are different, and the droplet ejection characteristics vary.

  In order to solve this problem, the common electrode wiring of the power feeding member may be provided in the vicinity of each piezoelectric element column. However, when such an arrangement is made, the wiring density of the power supply member increases, which causes a problem that high-density wiring cannot be performed. In addition, since the common electrode wiring is sandwiched between the individual electrode wirings, it is difficult to combine the common electrode wiring into one wiring member, and there is a problem that the degree of freedom of wiring is significantly reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce variations in displacement characteristics in the piezoelectric element column arrangement direction while ensuring the degree of freedom of wiring without increasing the wiring density of wiring members. And

In order to solve the above problems, the piezoelectric actuator according to the present invention is:
A piezoelectric member having a plurality of piezoelectric element columns in which piezoelectric layers and internal electrodes are alternately laminated;
A wiring member that feeds power to the piezoelectric element column of the piezoelectric member,
The piezoelectric member is
A surface side having a first common external electrode provided on one of opposing surfaces from which the internal electrode is drawn and an individual external electrode provided on the other surface, and on which the individual external electrode is formed A second common external electrode connected to the first common external electrode,
The wiring member is
Connected to the surface of the piezoelectric member on which the individual external electrodes are formed, to supply power to the individual external electrodes and the second common external electrode;
A common electrode wiring connected across a plurality of second common external electrodes formed on the plurality of piezoelectric element columns at a distal end connected to the piezoelectric member, and retracted from the distal direction with respect to the common electrode wiring And an individual electrode wiring connected to the individual external electrode.

Here, the piezoelectric member has a driving piezoelectric element column and a non-driving piezoelectric element column arranged,
The second common external electrodes formed on the non-driving piezoelectric element columns may be connected across the wiring member.

  In this case, the non-driving piezoelectric element columns to which the wiring members are connected may be arranged for each fixed number of non-driving piezoelectric element columns.

  The first common external electrode and the second common external electrode may be connected by an internal electrode.

  Further, the piezoelectric element column has an external electrode divided on the surface side on which the individual external electrode is formed, divided into a distal end side and a proximal end side in the stacking direction of the piezoelectric element columns, and the distal end portion The external electrode on the side may be a second common external electrode, and the external electrode on the base end side may be the individual external electrode.

  A plurality of the piezoelectric members may be arranged in the arrangement direction of the piezoelectric element columns.

  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.

  The piezoelectric actuator according to the present invention has the first common external electrode provided on one of the opposing surfaces from which the internal electrode is drawn, and the individual external electrode provided on the other surface, The wiring member has a second common external electrode connected to the first common external electrode on the surface side on which the external electrode is formed, and the wiring member is connected to the surface on which the individual external electrode of the piezoelectric member is formed. A common electrode wiring that feeds power to the second common external electrode and is connected to the tip portion connected to the piezoelectric member across the plurality of second common external electrodes formed on the plurality of piezoelectric element columns, and a common electrode Since it is configured to have an individual electrode wiring that is disposed rearward from the wiring and connected to the individual external electrode, a common electrode wiring is arranged at or near each piezoelectric element column and the piezoelectric element. Each piezoelectric element in the column arrangement direction Reduces the variations in displacement characteristics of the column, moreover, without increasing the wiring density of the wiring member can be ensured freedom of wiring can be summarized into one easily even common electrode lines.

  According to the liquid ejection head according to the present invention, since the piezoelectric actuator according to the present invention is provided, it is possible to perform satisfactory droplet ejection without variation in droplet ejection characteristics even when the length and density are increased.

  According to the image forming apparatus of the present invention, since the liquid ejection head according to the present invention is provided, a high-quality image can be formed at high speed.

FIG. 4 is an exploded perspective view illustrating an example of a liquid discharge head according to the present invention. It is sectional explanatory drawing which follows the direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head. It is sectional explanatory drawing of an example along the nozzle arrangement direction (liquid chamber short direction) of the head. It is sectional explanatory drawing of the other example along the nozzle arrangement direction (liquid chamber short direction) of the head. FIG. 3 is an explanatory cross-sectional view for explaining the piezoelectric actuator according to the first embodiment of the present invention. It is front explanatory drawing with which it uses for description of the electrode structure of a piezoelectric member, and the wiring structure of a wiring member. It is side surface explanatory drawing with which it uses for description of the electrode structure of the piezoelectric member in the piezoelectric actuator which concerns on 2nd Embodiment of this invention, and the wiring structure of a wiring member. It is side surface explanatory drawing used for description of the electrode structure of the piezoelectric member in the piezoelectric actuator which concerns on 3rd Embodiment of this invention, and the wiring structure of a wiring member. It is principal part front explanatory drawing of an example of the piezoelectric actuator which concerns on 4th Embodiment of this invention. It is principal part front explanatory drawing of the other example of the piezoelectric actuator which concerns on 4th Embodiment of this invention. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to the present invention. Similarly it is principal part plane explanatory drawing. It is a whole block diagram which shows the other example of the image forming apparatus which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of a liquid discharge head 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. FIG. 4 is an enlarged sectional explanatory view of one liquid chamber portion.

  The liquid discharge head includes a flow path plate (flow path substrate, liquid chamber substrate) 1 formed of a SUS substrate, a vibration plate member 2 that forms a vibration plate bonded to the lower surface of the flow path plate 1, and a flow path plate. A plurality of liquid chambers as individual flow paths each having a nozzle plate 3 joined to the upper surface of the nozzle 1 and a plurality of nozzles 4 for discharging droplets (liquid droplets) communicated with each other via a nozzle communication path 5. (Also referred to as a pressurized liquid chamber, a pressure chamber, a pressurized chamber, a flow path, etc.) 6, a fluid resistance section 7 that also serves as a supply path for supplying ink to the liquid chamber 6, and the fluid resistance section 7 A communication portion 8 communicating with the liquid chamber 6 is formed, and ink is supplied from a common liquid chamber 10 formed in a frame member 17 described later through a supply port 9 formed in the diaphragm member 2 in the communication portion 8.

  The flow path plate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path plate 1 is formed by etching the SUS substrate with 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 is formed of the first layer 2A and the second layer 2B, the first layer 2A forms a thin portion, and the first layer 2A and the second layer 2B form a thick portion. . And this diaphragm member 2 has each vibration field (diaphragm part) 2a formed in the 1st layer 2A which forms the wall surface corresponding to each liquid room 6, and in this vibration field 2a, An island-shaped convex portion 2b formed by the thick portions of the first layer 2A and the second layer 2B is provided on the outer surface (the side opposite to the liquid chamber 6), and the vibration region 2a is deformed into the island-shaped convex portion 2b. A piezoelectric actuator 100 according to the present invention including an electromechanical conversion element as a driving means (actuator means, pressure generating means) is arranged.

  The piezoelectric actuator 100 includes a plurality of (here, two) laminated piezoelectric members 12 that are bonded to an adhesive on a base member 13, and the piezoelectric member 12 has one groove 31 processed by half-cut dicing. A required number of piezoelectric element columns 12A and 12B are formed in a comb shape at a predetermined interval with respect to the piezoelectric member 12. The piezoelectric element columns 12A and 12B of the piezoelectric member 12 are the same, but the piezoelectric element column that is driven by giving a drive waveform is used as the drive piezoelectric element column 12A, and the piezoelectric element is used as a simple column without giving the drive waveform. The columns are distinguished as non-driving piezoelectric element columns 12B. Then, the upper end surface (joint surface) of the drive piezoelectric element column 12 </ b> A is joined to the island-shaped convex portion 2 b of the diaphragm member 2.

  Here, the piezoelectric member 12 is obtained by alternately stacking the piezoelectric material layers 21 and the internal electrodes 22A and 22B. The internal electrodes 22A and 22B are respectively substantially perpendicular to the end face, that is, the diaphragm member 2 of the piezoelectric member 12. Pulled out to the side surface (surface along the laminating direction), connected to the end face electrodes (external electrodes) 23, 24 formed on this side surface, and a voltage is applied between the end face electrodes (external electrodes) 23, 24 to form the laminating direction Cause displacement. The details of the electrode configuration of the piezoelectric member 12 will be described later.

  The piezoelectric member 12 is connected to an FPC 15 which is a flexible wiring board as a flexible power supply member (wiring member) for supplying a driving signal to the driving piezoelectric element column 12A. Although not shown, the FPC 15 includes a driver IC (drive circuit) that gives a drive waveform to the drive piezoelectric element column 12A.

  Here, as described above, the piezoelectric element columns 12A and 12B of the piezoelectric member 12 are the same, and the piezoelectric element column to be driven by applying a driving waveform is not applied to the driving piezoelectric element column 12A. A piezoelectric element column used as a mere support is a non-driving piezoelectric element column 12B, and as shown in FIG. 3, the driving piezoelectric element column 12A and the non-driving piezoelectric element column 12B are alternately used as a bi-pitch configuration. As shown in FIG. 5, it is possible to adopt a normal pitch configuration in which all the piezoelectric element columns are used as the driving piezoelectric element columns 12A.

  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.

  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 element 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 for supplying recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as a cartridge.

  In the liquid discharge head configured as described above, for example, when driven by a punching method, a driving pulse voltage of 20 to 50 V is selectively applied to the driving piezoelectric element column 12A according to an image recorded from a control unit (not shown). Is applied to the piezoelectric element column 12A to which the pulse voltage is applied, and the vibration region 2a of the vibration plate 2 is deformed in the direction of the nozzle plate 3, and the liquid chamber 6 changes its volume (volume). A liquid droplet is discharged from the nozzle 4 of the nozzle plate 3 by pressurizing the liquid. 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, when the voltage application to the piezoelectric element column 12A is turned off, 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, the recording liquid is filled into the liquid chamber 6 from the common liquid chamber 10, and droplets are ejected from the nozzle 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.

  Therefore, details of the piezoelectric actuator according to the first embodiment of the present invention in this liquid discharge head will be described with reference to FIGS. 5 is a cross-sectional explanatory view in which two piezoelectric members are sectioned on the same surface unlike FIG. 2, and the left side shows the connection state of the driving piezoelectric element column 12A and the right side of the non-driving piezoelectric element column 12B. FIG. 6A is an explanatory side view for explaining the electrode configuration of the piezoelectric member, and FIG. 6B is a side view for explaining the wiring configuration of the wiring member.

  As described above, the piezoelectric actuator 100 includes a piezoelectric member 12 having a plurality of piezoelectric element columns 12A and 12B in which piezoelectric layers 21A and internal electrodes 22A and 22B are alternately stacked, and a driving piezoelectric element column 12A of the piezoelectric member 12. And an FPC 15 as a wiring member for supplying power.

  And the piezoelectric member 12 has the 1st common external electrode 24 and the separate external electrode 23 in the mutually opposing surface (end surface) which pulled out internal electrode 22A, 22B, and the surface in which the separate external electrode 23 was formed. On the side, the first common external electrode 24 and the second common external electrode 25 connected through the internal electrode 22C are provided.

  In other words, here, the first common external electrode 24 and the individual external electrode 23 are provided on the opposite side surfaces (end surfaces) of the drive piezoelectric element column 12A, and the individual external electrodes of the drive piezoelectric element column 12A of the non-drive piezoelectric element column 12B. A second common external electrode 25 is formed on the same surface as 23. Here, no external electrode is formed on the base side portion of this surface, and each of the individual external electrodes 23 and the second common external electrode 25 are formed so as not to be connected to each other. The external electrode non-formation part may be formed by patterning, or may be scraped off after forming the external electrode. In the present embodiment, each of the individual external electrodes 23 and the second common external electrode 25 are not connected to each other by chamfering.

  Further, the individual external electrodes 23 of the drive piezoelectric element column 12A of the piezoelectric member 12 are formed on the base member 13 side with respect to the internal electrode 22C which is a part of the surface connected to the FPC 15, and the first common external electrode 24 and I try not to connect. On the other hand, the second external electrode 25 on the FPC 15 connection surface of the non-drive piezoelectric element column 12B is formed on the entire surface connected to the FPC 15, and is connected to the first common external electrode 24 through the internal electrode 22C. Further, the first common external electrode 24 provided on the driving piezoelectric element column 12A and the non-driving piezoelectric element column 12B is a portion on the base side of the piezoelectric member (the piezoelectric member remains by half-cut dicing of the piezoelectric element member as shown in FIG. 3). .) Are connected to each other to form an integral electrode.

Thereby, the connection on the common electrode side of the driving piezoelectric element column 12A is connected from the FPC 15 to the second common external electrode 25 of the adjacent non-driving piezoelectric element column 12B and further to the first common external electrode 24 through the internal electrode 22C. Even if it is a piezoelectric element column in the vicinity of the center of the piezoelectric member 12, the connection can be formed with a common electrode wiring of an extremely short distance, and variation in droplet discharge characteristics due to a difference in wiring resistance is suppressed. It becomes possible.

  In this example, the internal electrode 22C that connects (electrically connects) the first common external electrode 24 and the second common external electrode 25 is a single layer, but it may be a plurality of layers.

  Further, as the external electrodes 23, 24, 25, a metal film is formed to a thickness of about 1 μm by sputtering. The metal film is a multilayer film of Cr, Ni, Cu, Au or the like, and Au having a high bonding reliability with solder is preferable on the outermost surface. Since Au is expensive and the sputtering process takes a long time, the productivity is lowered. Therefore, the external electrodes 23, 24, and 25 are formed as thin films of about 1 μm as described above.

  In addition, as a method of forming the external electrode only in a part like the individual external electrode 23, a method of masking at the time of sputtering or a method of partially removing by a laser or mechanical processing is used. In addition, when removing partially, a part of piezoelectric element may be removed.

  Although not shown, the internal electrode 22C is patterned in a comb shape without forming the external electrode only in part, so that the internal electrode 22C is not connected to the individual external electrode 23 but only to the second common external electrode 25. It can also be.

  The FPC 15 as a wiring member has a wiring (electrode) 32 formed on the base material 31, a solder resist 33, and a driving IC 34, and is fixed to the base member 13 with a hot melt adhesive 16.

  The FPC 15 is connected to the surface of the piezoelectric member 12 where the individual external electrodes 23 are formed, and supplies power to the individual external electrodes 23 and the second common external electrode 25. The FPC 15 has a common electrode wiring 32B connected to the distal end portion connected to the piezoelectric member 12 across the plurality of second common external electrodes 25 formed on the plurality of non-driving piezoelectric element columns 12B, and a common electrode wiring. 32, the individual electrode wirings 32 </ b> A are disposed so as to recede from the front end direction than 32 and are connected to the individual external electrodes 23.

  Here, the wiring (electrode) 32 is formed of highly conductive Cu with a thickness of 8 μm. In the case of lower resistance, a thick film having a thickness of 12 μm, 18 μm, 35 μm or the like can also be used. The solder resist 33 is formed in a partial region 15B (FIG. 6) of the FPC 15.

  In the FPC 15 and the piezoelectric member 12, the individual electrode wiring 32 </ b> A is connected to the individual external electrode 23, and the common electrode wiring 32 </ b> B is connected to the second common external electrode 25 with solder 41. As a method of connecting the individual external electrode 23 and the second common external electrode 25 of the piezoelectric member 12 and the electrode wirings 32A and 32B of the FPC 15, the electrodes are aligned, the piezoelectric member 12 and the FPC 15 are overlapped, and a heater chip (block ), A heater bonding method in which the base material 31 on the back surface of the electrode portion 15A of the FPC 15 is pressurized and the temperature of the heater chip is increased in a pulsed manner to melt and harden the solder 41, or the FPC 15 transmits a laser such as glass. For example, a laser bonding method in which the electrode wires 32A and 32B of the FPC 15 and the solder 41 are irradiated with laser light in a state of being pressed by a rigid member to melt and cure the solder 41 can be used.

  The solder 41 may be any metal material having a lower melting point than the electrode wiring 32 of the FPC 15 and the base material 31 of the FPC 15 and made of a conductive material. Lead (Pb) It is preferable that it does not contain. For example, as the solder 41, solder containing tin (Sn) and bismuth (Bi) as main components can be used. Since lead is not contained, it is effective from the viewpoint of environmental protection, and the solder 41 mainly composed of tin (Sn) and bismuth (Bi) has a very low melting point among non-lead members. Therefore, the electrode wiring 32 of the FPC 15 and the external electrodes 23 and 25 of the piezoelectric member 12 can be easily welded without damaging the FPC 15 and the piezoelectric member 12.

  Here, the solder 41 is used as the electrical connection member, but an anisotropic conductive film, a conductive adhesive, or the like can also be used.

  The solder 41 is formed in advance on the external electrodes 23 and 25 of the piezoelectric member 12 or the electrode 32 (electrode portion 15A) of the FPC 15 by a printing method, a plating method, or the like.

  Here, although FPC is used as the wiring member, it may be any film provided with a plurality of electrodes that are thin and parallel to each other. For example, TAB (Tape Automated Bonding) can also be used. .

  As described above, according to the piezoelectric actuator of the liquid discharge head, the first common external electrode and the individual external electrode are provided on the opposite end surfaces from which the internal electrode of the piezoelectric element column is drawn, and the individual external electrode is formed. The wiring member has a second common external electrode connected to the first common external electrode on the formed surface side, and the wiring member is connected to the surface on which the individual external electrode of the piezoelectric member is formed, and is shared with the individual external electrode. Power is supplied to the external electrode, the tip connected to the piezoelectric member has a common electrode wiring connected across the plurality of second common external electrodes formed on the plurality of piezoelectric element columns, and the tip of the common electrode wiring. Since it is configured to have an individual electrode wiring that is disposed backward from the direction and connected to the individual external electrode, a common electrode wiring is disposed at or near each piezoelectric element column, and the piezoelectric element column arrangement Each piezoelectric in direction Reduces the variations in displacement characteristics of the child column, moreover, without increasing the wiring density of the wiring member can be ensured freedom of wiring can be summarized into one easily even common electrode lines.

  That is, the common electrode wiring of the wiring member is located in the vicinity of each piezoelectric element column. At this time, the common electrode wiring of the wiring member is configured to extend in the piezoelectric element arrangement direction, but the common electrode wiring (conductive layer) of the wiring member is sufficiently larger than the external electrode layer and the internal electrode layer of the piezoelectric element column. It can be formed thick (about 10 times), and power loss due to resistance hardly poses a problem, and the connection between the second common external electrode and the common electrode wiring is the same as the connection of the normal wiring member, and the connection resistance Etc., and there is almost no variation in displacement characteristics of each piezoelectric element column due to a change in the resistance value in the piezoelectric element column arrangement direction.

  Also, along with the increase in length and density of the head, especially when a plurality of piezoelectric element pillars are driven simultaneously, even if the current to the common electrode increases, the burning and scorching due to the heat generation of the common electrode is reduced. be able to.

  In this case, since the common electrode wiring is not arranged between the individual electrode wirings, high-density wiring can be performed and the common electrode wiring can be integrated into one wiring member. Also, the degree of freedom of wiring can be secured.

  In addition, since there is no common electrode wiring of the wiring member between the individual electrode wirings, there is no common electrode wiring between the connection portions with the driving IC, and it is necessary to increase the IC size, or the common electrode wiring of the wiring member intersects with the individual wiring. Since it is not necessary to make it, it does not raise the cost of the wiring member.

  By providing the piezoelectric actuator in the liquid discharge head, it is possible to perform good droplet discharge with little variation in droplet discharge characteristics between the piezoelectric element columns even when the head is lengthened and densified.

  In the above embodiment, the driving piezoelectric element columns and the non-driving piezoelectric element columns are alternately arranged on the piezoelectric member, the second common external electrode is formed on the non-driving piezoelectric element column, and is connected to the common electrode wiring. The so-called crosstalk in which the adjacent non-driving piezoelectric element columns are displaced by the displacement of the driving piezoelectric element columns can be suppressed. That is, in this case, since the voltage applied between the internal electrodes of the non-driving piezoelectric element column is “0”, the displacement of the non-driving piezoelectric element column can be suppressed.

  Further, the non-driving piezoelectric element columns on which the second common external electrodes are formed are provided for every predetermined number of driving piezoelectric element columns (in the above embodiment, each non-driving piezoelectric element column is formed on the non-driving piezoelectric element columns forming the second common external electrode). The resistance of the common wiring portion can be greatly reduced, and when a plurality of wiring members are connected side by side in response to the increase in the length of the piezoelectric member. In addition, the common electrode can be easily taken out from each wiring member.

  Further, by connecting the first common external electrode and the second common external electrode with the internal electrode, there is no need to connect the internal electrode in a member other than the piezoelectric member or in the manufacturing process, which increases man-hours and changes other parts. The first common external electrode and the second common external electrode can be electrically connected without any problem.

Next, a piezoelectric actuator according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory side view for explaining the electrode configuration of the piezoelectric member and the wiring configuration of the wiring member.
Here, the external electrode on the surface connected to the FPC 15 of the piezoelectric member 12 is divided into the distal end side and the base member 13 side (base end side) by the slit 26. As a result, the second common external electrode 25 is formed on the upper side (tip side) and the individual external electrode 23 is formed on the lower side (base end side) on the end face of the drive piezoelectric element column 12A. Further, the second common external electrode 25 is formed on the upper surface (tip side) on the end face of the non-drive piezoelectric element 12B, and the lower (base end side) electrode portion is electrically connected to the first common external electrode 24. Therefore, it becomes a simple electrode film (electrically connected to the second common external electrode 25 through the common wiring electrode 32B of the FPC).

  In addition, as a method for dividing the external electrode vertically, a method of forming a groove with a dicer or a method of removing the electrode with a laser can be used.

  The configuration of the electrode wiring of the FPC 15 is the same as that in the first embodiment.

  The FPC 15 and the piezoelectric member 12 are connected by soldering the individual electrode wiring 32A to the individual external electrode 23 and the common electrode wiring 32B to the second common external electrode 25, respectively.

  With this configuration, the second common external electrode 25 is also formed on the drive piezoelectric element column 12A and is connected to the common electrode wiring 32B of the FPC 15, so that the connection strength is improved.

Next, a piezoelectric actuator according to a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory side view for explaining the electrode configuration of the piezoelectric member and the wiring configuration of the wiring member.
Here, a normal pitch configuration is adopted in which all the piezoelectric element columns of the piezoelectric member 2 are the driving piezoelectric element columns 12A. That is, as in the second embodiment, the external electrode on the surface connected to the FPC 15 of the piezoelectric member 12 is divided by the slit 26 into the drive surface 12a side and the base member 13 side. As a result, the second common external electrode 25 is formed on the upper side (tip side) and the individual external electrode 23 is formed on the lower side (base end side) on the end face of the drive piezoelectric element column 12A.

  On the other hand, individual electrode wirings 32A are formed on the FPC 15 at an arrangement pitch of the piezoelectric element columns so as to be connected to the individual external electrodes 23 of the respective driving piezoelectric element columns 12A. The wide non-driving piezoelectric element column 12B at the end of the piezoelectric member 12 does not have to be divided vertically.

  The FPC 15 and the piezoelectric member 12 are connected by soldering the individual electrode wiring 32A to the individual external electrode 23 and the common electrode wiring 32B to the second common external electrode 25, respectively.

  In this way, the external electrode on the surface forming the individual external electrode of the piezoelectric member is divided into two parts, the distal end side and the proximal end side, and the individual electrode wiring of the wiring member is connected using the proximal end electrode as the individual electrode. By connecting the electrode on the tip end side to the common electrode wiring of the wiring member as the second common external electrode connected through the first common external electrode and the internal electrode, it is easy without patterning the external electrode and the internal electrode. A low-cost piezoelectric actuator can be obtained by simple slit processing.

Next, different examples of the piezoelectric actuator according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 9 and FIG. 10 are schematic front explanatory views excluding the FPC of the actuator.
In the example of FIG. 9, six piezoelectric members 12 are arranged on a straight line on the base member 13, and the piezoelectric members 12 are connected. The interval between the piezoelectric members 12 is about 10 μm, and the rows of the piezoelectric members may be a plurality of rows.
In the example of FIG. 10, two piezoelectric members 12 are arranged on a straight line on the base member 13, and the piezoelectric members are connected. The gap between the piezoelectric members 12 is about 0 to 10 μm.

  Although details of the piezoelectric member and wiring members such as FPC are not shown, they are the same as those in the first to third embodiments. In this case, a wiring member such as an FPC may be individually connected for each piezoelectric member, or one FPC (wiring member) may be connected to two or more piezoelectric members. it can.

  When the plurality of piezoelectric members are arranged in this way, even if the current value flowing through the common external electrode of the plurality of piezoelectric members increases, the non-driving piezoelectric element column or the second common external electrode of the driving piezoelectric element column Since the FPC common electrode wiring is connected, it is possible to obtain a long piezoelectric actuator that does not cause a problem due to an increase in current.

  The liquid discharge head according to the present invention can also be configured as a head-integrated cartridge or a cartridge-integrated head in which a cartridge for supplying ink to the head is integrated.

  Note that an ink cartridge in which a tank for supplying ink to the liquid discharge head of each of the above embodiments is integrated can be configured.

Next, an example of the image forming apparatus according to the present invention including the liquid discharge head according to the present invention will be described with reference to FIGS. FIG. 11 is a schematic configuration diagram for explaining the overall configuration of the mechanism portion of the apparatus, and FIG. 12 is a plan view of a main portion of the mechanism portion.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held 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 that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes a plurality of recording heads 234 including the liquid discharge head unit according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows consisting of these nozzles are arranged in the sub-scanning direction orthogonal to the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching liquid ejection heads 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a has a black (K) droplet. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. . Note that, here, a two-head configuration is used to eject four color droplets, but a liquid ejection head for each color may be provided.

  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 by the supply unit 224 via the supply tube 236 of each color.

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

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

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

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

  Further, a maintenance / recovery mechanism 281 for maintaining and recovering the nozzle state of the recording head 234 is disposed in a non-printing area on one side in the scanning direction of the carriage 233. The maintenance / recovery mechanism 281 includes cap members (hereinafter referred to as “caps”) 282a and 282b (hereinafter referred to as “caps 282” when not distinguished) 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.

  Further, in the non-printing area on the other side in the scanning direction of the carriage 233, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to the recording in order to discharge the recording liquid thickened during the recording. A discharge receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

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

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

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

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, stable droplet discharge can be performed even if the head is lengthened and densified, and high speed is achieved. Thus, a high quality image can be formed.

Next, another example of the image forming apparatus according to the present invention including the liquid ejection head according to the present invention will be described with reference to FIG. FIG. 13 is a schematic configuration diagram of the entire mechanism unit of the apparatus.
This image forming apparatus is a line type image forming apparatus, has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided, a sheet 403 fed from the sheet feeding tray 404 is taken in, a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405, and then the side of the apparatus main body 401. The paper 403 is discharged to a paper discharge tray 406 attached to the printer.

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

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

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

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

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

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

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

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

  In the image forming apparatus configured as described above, the conveyance belt 433 moves in the direction indicated by the arrow, and is charged by contact with the charging roller 434 to which a high potential application voltage is applied. When the sheet 403 is fed onto the sheet 433, the sheet 403 is electrostatically attracted to the conveyance belt 433. In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface.

  Then, the paper 403 is moved around the conveyor belt 433 and droplets are ejected from the recording head 411, whereby a required image is formed on the paper 403, and the paper 403 on which the image has been recorded is the paper discharge roller 438. As a result, the paper is discharged to the paper discharge tray 406.

  As described above, since the image forming apparatus includes the recording head including the liquid discharge head according to the present invention, it is stable even if a plurality of nozzles are driven simultaneously by increasing the density and length of the head. Droplet discharge can be performed, and a high-quality image can be formed at high speed.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. 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.

1 Channel plate (channel substrate)
2 vibration plate member 3 nozzle plate 4 nozzle 6 liquid chamber 10 common liquid chamber 12 piezoelectric member 12A driving piezoelectric element column 12B non-driving piezoelectric element column 13 base member 15 FPC (wiring member)
15A electrode portion 23 individual external electrode 24 first common external electrode 25 second common external electrode 31 base material 32A individual electrode wiring 32B common electrode wiring 100 piezoelectric actuator 233 carriage 234 recording head

Claims (8)

A piezoelectric member having a plurality of piezoelectric element columns in which piezoelectric layers and internal electrodes are alternately laminated;
A wiring member that feeds power to the piezoelectric element column of the piezoelectric member,
The piezoelectric member is
A surface side having a first common external electrode provided on one of opposing surfaces from which the internal electrode is drawn and an individual external electrode provided on the other surface, and on which the individual external electrode is formed A second common external electrode connected to the first common external electrode,
The wiring member is
Connected to the surface of the piezoelectric member on which the individual external electrodes are formed, and feeds power to the individual external electrodes and the second common external electrode;
A common electrode wiring connected across a plurality of second common external electrodes formed on the plurality of piezoelectric element columns at a distal end connected to the piezoelectric member, and retracted from the distal direction with respect to the common electrode wiring And a separate electrode wiring connected to the separate external electrode. The piezoelectric member has a driving piezoelectric element column and a non-driving piezoelectric element column arranged,
2. The piezoelectric actuator according to claim 1, wherein the second common external electrodes formed on the non-driving piezoelectric element columns are connected across the wiring member.   3. The piezoelectric actuator according to claim 2, wherein the non-driving piezoelectric element columns to which the wiring members are connected are arranged for each fixed number of non-driving piezoelectric element columns.   The piezoelectric actuator according to any one of claims 1 to 3, wherein the first common external electrode and the second common external electrode are connected by an internal electrode.   On the surface side where the individual external electrodes of the piezoelectric element columns are formed, the piezoelectric element columns have external electrodes that are divided into two in the stacking direction of the piezoelectric element columns: a distal end side and a proximal end side. 5. The piezoelectric actuator according to claim 1, wherein the external electrode is a second common external electrode, and the external electrode on the base end side is the individual external electrode. 6.   6. The piezoelectric actuator according to claim 1, wherein a plurality of the piezoelectric members are arranged in an arrangement direction of the piezoelectric element columns.   A liquid discharge head comprising the piezoelectric actuator according to claim 1.   An image forming apparatus comprising the liquid discharge head according to claim 7.

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