JP5358924B2 - Liquid ejection head and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of joining failures because stain adheres at the time of joining when a piezoelectric element and an FPC are FPC laser joined or heater joined to each other, and consequently because a laser transmittance decreases. <P>SOLUTION: The liquid discharge head is equipped with a diaphragm 2 which forms at least partial wall surfaces of liquid chambers 6 that communicate with nozzles 4 for discharging liquid droplets, piezoelectric element pillars 12A of the piezoelectric element 12 which deforms the diaphragm 2, and the FPC 15 with connection electrodes 31 directly connected to external electrodes 23a formed at side surfaces nearly perpendicular to the diaphragm 2 of the piezoelectric element pillars 12A. The connection electrode 31 of the FPC 15 is formed from a position retreated by a distance L from the front end side of the diaphragm joining side of a region where the FPC and the piezoelectric element 12 are opposed to each other. The connection electrode 31 is hindered from being present at the front end side. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

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

  In general, a printer, a fax machine, a copier, a plotter, or an image forming apparatus that combines a plurality of these functions includes, for example, a recording head composed of a liquid ejection head that ejects ink droplets, It is also referred to as “paper”, but the material is not limited, and a recording medium, recording medium, transfer material, recording paper, etc. are also used synonymously.) Some perform formation (recording, printing, printing, and printing are also used synonymously).

  The “image forming apparatus” means an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. “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 ejecting a droplet). means. Further, “ink” is not limited to ink in a narrow sense, and is not particularly limited as long as it becomes liquid when ejected, and includes, for example, a DNA sample, a resist, a pattern material, and the like. .

  As the liquid ejection head, at least a part of wall surfaces of a plurality of liquid chambers arranged corresponding to a plurality of nozzles arranged in parallel to eject ink droplets is formed by a diaphragm, and the diaphragm is formed by a piezoelectric element. There is known a piezoelectric head that deforms and changes the volume of a liquid chamber to eject ink droplets.

  In such a piezoelectric head, for example, using a laminated piezoelectric element, an electrode of a wiring means such as an FPC (flexible printed cable) is joined to an external electrode (also referred to as an end face electrode) from which an internal electrode is drawn to the end face. A drive signal corresponding to an image signal is given to each piezoelectric element.

  In this case, an electrical connection between an electrode (which is also referred to as a “second electrode”) provided on a wiring means such as an FPC and an external electrode (which is also referred to as a “first electrode”) of the piezoelectric element. As a method of performing, for example, a metal is interposed between the first electrode and the second electrode, both the electrodes are brought into close contact with a laser transmitting rigid member such as glass, and the metal is melted by laser light to thereby melt the first electrode. And a method in which the first electrode and the second electrode are welded together with a metal by melting the metal by thermocompression bonding such as a heater. It has been.

Conventionally, in Patent Document 1, for the purpose of preventing short-circuiting when soldering microelectrodes at a fine pitch, FPC is performed when the conductive electrode of the FPC board and the electrode pad of the device are thermocompression bonded via solder. It is described that a solder pool is provided in the length direction of the terminal.
Japanese Patent Laid-Open No. 2003-218494 discloses a technique for driving a piezoelectric element for the purpose of joining a lead-out wiring and an external wiring cable, improving durability current, and preventing deformation and cracking of the substrate. A method is described in which a connection terminal for wiring and an external wiring cable are joined by a metal melted by a laser. JP 2003-063006 A

  As described above, the second electrode of the FPC and the first electrode of the piezoelectric element are generally electrically connected by laser bonding or heater bonding (thermocompression bonding). However, conventional FPCs (flexible printed cables) are provided with the second electrode up to the tip. Therefore, in the case of laser bonding, fumes such as flux at the time of bonding adhere to a pressing member such as glass, and there is a problem in that laser transmittance is reduced and bonding failure occurs. In addition, in the case of heater bonding, there is a problem that flux or the like adheres to the heater chip during bonding and heat transfer to the bonding becomes insufficient, or that these stains adhere to the electrodes, resulting in poor bonding. Furthermore, there is a problem in that the solder crawls up on the electrodes during bonding, so that the solder flows to the bonding surface with the diaphragm of the piezoelectric element, resulting in poor bonding with the diaphragm.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the occurrence of defective bonding between electrodes of a piezoelectric element and wiring means.

In order to solve the above problems, a liquid-liquid ejection head according to the present invention is
A diaphragm that forms at least a part of a wall surface of a liquid chamber that communicates with a nozzle that discharges droplets;
A piezoelectric element bonded to the diaphragm and deforming the diaphragm;
Wiring means having a connection electrode directly connected by a solder member to an external electrode formed on a side surface substantially perpendicular to the diaphragm of the piezoelectric element;
The external electrode of the piezoelectric element is covered with a non-conductive member at a position facing the front end surface on the diaphragm side of the wiring member in a region where the wiring means and the piezoelectric element are opposed to each other. did.

  Here, the wiring means can be configured as FPC or TAB.

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

According to the liquid drop discharge head of the present invention, while reducing the mutual interference, it is possible to improve the workability of the piezoelectric element columns.

  According to the image forming apparatus according to the present invention, since the liquid ejection head according to the present invention is provided, the reliability can be improved.

  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. 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, and upper end surfaces (joint surfaces) 12a of the piezoelectric element columns 12A and 12B of the laminated piezoelectric element 12 as driving means (actuator means, pressure generating means) for deforming the vibration region 2a on the island-shaped convex portions 2b. Are joined. Further, the lower end surface of the multilayer piezoelectric element 12 is joined to the base member 13.

  Here, the piezoelectric element 12 is formed by alternately laminating piezoelectric material layers 21 and internal electrodes 22a and 22b. The internal electrodes 22a and 22b are respectively end faces, that is, side surfaces substantially perpendicular to the diaphragm 2 of the piezoelectric element 12. Are connected to end face electrodes (external electrodes) 23a and 23b formed on the side surfaces, and a voltage is applied to the end face electrodes (external electrodes) 23a and 23b to cause displacement in the stacking direction. The piezoelectric element 12 is obtained by forming grooves by half-cut dicing to form a required number of piezoelectric element columns 12A and 12B for one piezoelectric element member.

  The piezoelectric element columns 12A and 12B of the piezoelectric element 12 are the same, but the piezoelectric element column that is driven by giving a driving waveform is the piezoelectric element column 12A, and the piezoelectric element column that is used as a simple column without giving the driving waveform. Is distinguished as the piezoelectric element column 12B. In this case, as shown in FIG. 3, the piezoelectric element columns 12A for driving and the piezoelectric element columns 12B for supporting columns are alternately used, or all the piezoelectric element columns are driven piezoelectrically as shown in FIG. Any of the normal pitch configurations used as the element pillars 12A can be adopted.

  A connection electrode 32 (to be described later) of the FPC 15 serving as a wiring means is directly connected to the external electrode 23a of each driving piezoelectric element column 12A of the piezoelectric element 12 by a solder member in order to give a driving signal. A drive circuit (driver IC) 16 for selectively applying a drive waveform to each of the 12 drive piezoelectric element columns 12A is mounted. The external electrodes 23b of all the piezoelectric element columns 12A are electrically connected in common and connected to the common wiring of the FPC 15.

  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.

  The 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 element 12, and the liquid droplet ejection direction is different from the recording liquid flow direction in the liquid chamber 6. The liquid droplets are ejected by the side shooter method. By adopting the side shooter system, the size of the piezoelectric element 12 becomes approximately the size of the head, and the miniaturization of the piezoelectric element 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 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 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 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 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, a connection structure between the piezoelectric element (column) and the FPC in this liquid discharge head will be described with reference to FIGS. 5 is a schematic explanatory view along a direction orthogonal to the nozzle arrangement direction of the piezoelectric unit, FIG. 6 is a perspective view of the same principal part, and FIG. 7 is a schematic explanatory view along the direction of the nozzle arrangement of the piezoelectric unit. Here, all the piezoelectric element columns of the piezoelectric element 12 are illustrated in a normal pitch configuration used as the driving piezoelectric element column 12A.

  Here, the external electrode (end face electrode) 23a of the piezoelectric element column 12A of the piezoelectric element 12 and the connection electrode 31 of the FPC 15 are electrically connected by being directly joined by the solder member 32 provided on the connection electrode 31 of the FPC 15. ing. In this case, the connection electrode 31 of the FPC 15 is provided from a position retreated by a distance L from the tip on the diaphragm 2 side in a region facing the FPC 15 and the external electrode 23 a of the piezoelectric element 12. That is, the connection electrode 31 of the FPC 15 is configured not to exist on the front end side on the diaphragm 2 side in the region facing the piezoelectric element 12.

  In order to join the external electrode 23a of the piezoelectric element 12 and the connection electrode 31 of the FPC 15, the solder member 32 is melted by irradiating each connection electrode 31 and the FPC 15 made of a resin member with laser light or thermocompression bonding with a heater. Do that.

  At this time, the connection electrode 31 does not exist on the front end side of the diaphragm side of the region facing the piezoelectric element 12 of the FPC 15, so that in the case of laser bonding, fumes such as flux at the time of bonding of the pressing member such as glass It can be prevented from adhering to the upper surface of the joining portion, lowering the laser transmittance, and causing poor joining. In addition, in the case of thermocompression bonding using a heater, flux or the like is difficult to protrude from the front end surface of the FPC 15 at the time of bonding, and does not adhere to the heater chip, resulting in insufficient heat transfer to the bonding or contamination of these. Bonding failure due to adhering to the member does not occur.

  The solder member 32 may be any material that has a lower melting point than the connection electrode 31 made of a metal member and the FPC 15 made of a resin material and is made of a conductive material. Pb) is preferably not contained. For example, a solder mainly composed of tin (Sn) and bismuth (Bi) can be used as the solder member 32. Since lead is not contained, it is effective from the viewpoint of environmental protection, and the solder member 32 mainly composed of tin (Sn) and bismuth (Bi) has a very low melting point among non-lead members. Therefore, the electrode 31 and the external electrode 23a can be easily welded without damaging the FPC 15 and the piezoelectric element 12.

  Further, although FPC is used here as the wiring means, 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. .

Next, a second embodiment of the present invention will be described with reference to FIG. In addition, FIG. 8 is an enlarged explanatory view of a state before joining of a joining portion between the wiring means and the piezoelectric element in the same embodiment.
Here, the connection electrode 31 of the FPC 15 is provided up to the tip on the diaphragm joint side in the region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other, but the region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other. Thus, the front end side of the diaphragm 2 is covered with a non-conductive member (film) 33.

  As described above, the connection electrode 31 of the wiring means is configured such that the tip end side on the diaphragm joint side of the region where the wiring means and the piezoelectric element face each other is covered with the non-conductive member 33, whereby the first electrode described above is used. Similarly to the embodiment, fumes such as flux at the time of laser bonding do not adhere to the upper surface of the bonding portion of the pressing member such as glass, and it is possible to prevent the laser transmittance from being lowered and the occurrence of bonding failure. During thermocompression bonding with a heater, flux or the like is difficult to protrude from the front end surface of the FPC 15 and does not adhere to the heater chip, resulting in insufficient heat transfer to the junction, or poor adhesion due to adhesion of these stains to the joining member. Will not occur.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is an enlarged explanatory view of a state before joining of the joint portion between the wiring means and the piezoelectric element in the embodiment.
Here, the external electrode 23a of the piezoelectric element 12 does not exist on the tip end side on the diaphragm joint side in the region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other, and the distance L from the joint surface 12b with the diaphragm 2 Only set back.

  In this case, the connection electrode 31 on the FPC 15 side does not exist on the front end side on the diaphragm joint side in the region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other (the first embodiment), diaphragm joint It is possible to adopt a configuration in which the front end side is covered with a non-conductive member 33 (the second embodiment), or in the region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other on the diaphragm joint side It can also be set as the structure which is provided to the front-end | tip and is not coat | covered with the nonelectroconductive member (film | membrane) 33. FIG.

  Thus, the external electrode 23a of the piezoelectric element does not exist on the front end portion side on the diaphragm joint side in the region where the wiring means and the piezoelectric element face each other, thereby obtaining the same effect as that of the first embodiment described above. be able to.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, FIG. 10 is an enlarged explanatory view of a state before joining of a joint portion between the wiring unit and the piezoelectric element in the same embodiment.
Here, the external electrode 23a of the piezoelectric element 12 is provided up to the tip of the diaphragm joint side in a region where the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other, but the FPC 15 and the external electrode 23a of the piezoelectric element 12 face each other. In this region, the tip end side on the diaphragm joint side is covered with a non-conductive member (film) 33. The configuration on the FPC 15 side may be any configuration described in the third embodiment.

  As described above, the external electrode 23a of the piezoelectric element has a configuration in which the tip end side on the diaphragm joint side in the region where the wiring means and the piezoelectric element face each other is covered with the nonconductive member, thereby the first embodiment described above. The same effect can be obtained.

Next, an example of a wiring member joining apparatus for joining a wiring means such as an FPC and a piezoelectric element will be described with reference to a schematic configuration diagram of FIG.
This wiring member joining apparatus 100 electrically joins and connects a plurality of parallel first electrodes provided on a thin film-like first wiring member and a plurality of parallel second electrodes provided on a second wiring member. To do. In the following description, FIG. 11 is a height direction Z-axis direction when viewed from the front, a plane orthogonal to the height direction is the XY plane, and a width direction (lateral direction) when FIG. 11 is viewed from the front is the Y-axis direction.

  In the wiring member joining apparatus 10, the base 111 is provided with a first member holding mechanism 112, a second member holding mechanism 113, a laser irradiation mechanism 114, a camera 115, and an air path forming mechanism 116. The drive is controlled centrally by a control mechanism (not shown).

  The first member holding mechanism 112 includes a joining XY direction adjusting unit 117 provided on the base 111, a joining Z-axis direction adjusting unit 118 attached thereto, and an adjusting stage 119 attached thereto. The joining XY direction adjusting unit 117 includes an X-axis drive unit that is supported by a guide shaft that extends in the X-axis direction (not shown) and a Y-axis that is supported by a guide shaft that extends in the Y-axis direction. The driving unit is configured to be movable along the XY plane. A joining Z-axis direction adjusting unit 118 is attached to the joining XY direction adjusting unit 117 so as to be movable together with the joining XY direction adjusting unit 117.

  The bonded Z-axis direction adjusting unit 118 is configured to be freely movable along the Z-axis direction with respect to the bonded XY direction adjusting unit 117. In other words, the joint XY direction adjusting unit 117 and the joint Z axis direction adjusting unit 118 can be moved to a desired position so as to be movable together with the joint Z axis direction adjusting unit 118. In addition, an adjustment stage 119 is attached to the bonding Z-axis direction adjustment unit 118.

  The adjustment stage 119 is a plate-like member provided so as to extend along the XY plane at the upper end position of the bonding Z-axis direction adjustment unit 118. An upper surface (119a) along the XY plane of the adjustment stage 119 serves as a mounting surface 119a for the first wiring member (the FPC 15 described above), and a plurality of positioning pins 120 (only one is shown in FIG. 11) protruding from this surface. And the first wiring member (FPC 15) placed on the placement surface 119a can be sucked and held. Each positioning pin 120 roughly determines the mounting position of the first wiring member (FPC 15) mounted on the mounting surface 119a of the adjustment stage 119.

  With the configuration described above, the first member holding mechanism 112 has a desired position in a state in which the first wiring member (FPC 15) sucked and held on the mounting surface 119a of the adjustment stage 119 extends along the XY plane. Can be adjusted. A second member holding mechanism 113 is provided to fix and hold the second wiring member (piezoelectric element 12) joined to the first wiring member (FPC 15).

  The second member holding mechanism 113 has a second member mounting table 122 attached to a fixed table 121 provided on the base 111, and a second wiring member mounted on the second member mounting table 122. Can be sucked and held (here, the piezoelectric element 12 as the second wiring member attached thereto is fixed via the base member 13). The second member holding mechanism 113 is a first wiring member (FPC15) that is sucked and held in a state of being approximately positioned by the first member holding mechanism 112 above the joint portion of the second wiring member (piezoelectric element 12) that is sucked and held. The relative positional relationship with the first member holding mechanism 112 is set so that the joint portion is located. A laser irradiation mechanism 14 is provided in order to irradiate the joint with laser light.

  The laser irradiation mechanism 114 is attached to the base 111 so as to be always fixed at a fixed position via the mounting arm 123, and includes a laser XY direction adjustment unit 124, a laser Z axis direction adjustment unit 125, and a laser irradiation unit. 126.

  Although not shown, the laser XY direction adjusting unit 124 is supported by an X-axis driving unit supported to be driven by a guide shaft extending in the X-axis direction and a guide shaft extending by the Y-axis direction. It is comprised by the Y-axis drive part, and is movable along an XY plane. A laser Z-axis direction adjusting unit 125 is attached to the laser XY direction adjusting unit 124 so as to be movable together with the laser XY direction adjusting unit 124.

  Although not shown, the laser Z-axis direction adjustment unit 125 is configured so as to be freely accessible along the Z-axis direction with respect to the laser XY direction adjustment unit 124. It is possible to move together with the laser Z-axis direction adjusting unit 125, that is, to move to a desired position on the base 111 by the laser XY direction adjusting unit 124 and the laser Z-axis direction adjusting unit 125. The laser irradiation unit 126 is attached to the laser Z-axis direction adjustment unit 125.

  The laser irradiation unit 126 can emit laser light L, and a semiconductor laser is employed. The laser irradiation unit 126 is capable of emitting the laser beam L along the Z-axis direction regardless of the position moved by the laser XY direction adjusting unit 124 and the laser Z-axis direction adjusting unit 125. Is attached. For this reason, the laser irradiation mechanism 114 functions as an irradiation unit.

  A camera 115 is provided so as to be positioned between the laser irradiation unit 126 and the second wiring member (piezoelectric element 12) sucked and held by the second member holding mechanism 113. Although not shown, the camera 115 is positioned on the optical axis of the laser light L emitted from the laser irradiation unit 126 regardless of the movement of the laser irradiation unit 126 (for example, interlocked with the laser irradiation unit 126). So as to be fixed to the laser Z-axis direction adjusting portion 125). For this reason, the camera 115 can image the vicinity of the irradiation region of the laser light L without obstructing the irradiation of the laser light L by the laser irradiation unit 126. The air path forming mechanism 116 holds the air path forming plate 127 between the camera 115 and the second wiring member (piezoelectric element 12) sucked and held by the second member holding mechanism 113.

  The air path forming mechanism 116 includes an air path XY direction adjusting unit 128 and an air path forming plate 127. Although not shown, the air passage XY direction adjusting unit 128 is supported by an X-axis driving unit supported to be driven by a guide shaft extending in the X-axis direction and a guide shaft extending by the Y-axis direction. The Y-axis driving unit is movable along the XY plane. An air path forming plate 127 is detachably fixed and held on the air path XY direction adjusting unit 128 so as to be movable together with the air path XY direction adjusting unit 128.

  As will be described later, the air path XY direction adjusting unit 128 includes an air path forming plate 127 having a plate shape as a whole extending along the XY plane, and the laser beam L emitted from the laser irradiation unit 126 and the laser beam L The air path forming plate 127 is fixedly held so that the optical axis of the coincident camera 115 vertically cuts the inside of the laser transmitting plate portion 141 and the air path forming notch portion 143 provided on the air path forming plate 127. . Further, the air path XY direction adjusting unit 128 moves the air path forming plate with respect to the laser beam L and the optical axis of the camera 115 when the laser irradiation unit 126 is moved by the laser XY direction adjusting unit 124 and the laser Z axis direction adjusting unit 125. 127 is configured to be interlocked with the position of the laser irradiation unit 126 so that the positional relationship of 127 is maintained. Accordingly, the laser light L emitted from the laser irradiation unit 126 passes through the air path forming plate 127 regardless of the position of the laser irradiation unit 126 to be moved, and the first wiring member (FPC15) and the second wiring member. A joint portion with (piezoelectric element 12) can be irradiated.

  Here, a semiconductor laser is used as the laser beam, but since it is inexpensive and easy to control, the joining operation can be performed inexpensively and appropriately. Further, since the semiconductor laser has a high transmittance to the resin material, the connection electrodes 31 and the external electrodes 23a are not damaged without damaging the FPC 15 (first wiring member) and the piezoelectric element 12 (second wiring member). Can be appropriately joined.

  In addition, although a semiconductor laser is used as the laser irradiation unit 26, it has a high absorption rate to the portion (the solder member 32 described above) that is irradiated for bonding, and the first wiring member (FPC 15) has a high transmittance. For example, a YAG (Yttrium / Aluminum / Garnet) laser emitted continuously may be used, and the present invention is not limited to the above-described embodiments.

  Here, the bonding is performed using a laser. However, this bonding may be performed using a thermocompression bonding tool such as a heater chip, and in this case, the same effect on bonding failure can be expected.

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.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and sub guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 201A and 201B. 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 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 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 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, there is no bonding failure, the reliability of the recording head is improved, and stable recording can be performed.

  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.

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 typical explanatory drawing which follows the direction orthogonal to the nozzle arrangement direction of the piezoelectric unit of the head. It is a principal part perspective explanatory drawing similarly. FIG. 6 is a schematic explanatory view along the direction in which the piezoelectric units are similarly arranged. FIG. 10 is an enlarged explanatory view of a state before bonding of a bonding portion between a wiring member and a piezoelectric element in a liquid ejection head according to a second embodiment of the present invention. FIG. 10 is an enlarged explanatory view of a state before bonding of a bonding portion between a wiring member and a piezoelectric element in a liquid ejection head according to a third embodiment of the present invention. FIG. 10 is an enlarged explanatory diagram of a state before bonding of a bonding portion between a wiring member and a piezoelectric element in a liquid ejection head according to a fourth embodiment of the present invention. It is a typical block diagram explaining an example of a wiring member joining apparatus. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Channel plate 2 ... Nozzle plate 3 ... Vibration plate 4 ... Nozzle 6 ... Individual liquid chamber 10 ... Common liquid chamber 12 ... Piezoelectric element 12A, 12B ... Piezoelectric element column 13 ... Base member 15 ... FPC (wiring means)
23a ... External electrode 31 ... Connection electrode 32 ... Solder member 234 ... Carriage 235 ... Recording head

Claims (3)

A diaphragm that forms at least a part of a wall surface of a liquid chamber that communicates with a nozzle that discharges droplets;
A piezoelectric element bonded to the diaphragm and deforming the diaphragm;
Wiring means having a connection electrode directly connected by a solder member to an external electrode formed on a side surface substantially perpendicular to the diaphragm of the piezoelectric element;
The external electrode of the piezoelectric element is covered with a non-conductive member at a position facing the front end surface on the diaphragm side of the wiring member in a region where the wiring means and the piezoelectric element face each other. Discharge head. 2. The liquid discharge head according to claim 1 , wherein the wiring means is FPC or TAB. An image forming apparatus comprising the liquid ejection head according to claim 1 or 2.

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