JP2012195538A - Flexible wiring member, actuator, liquid discharge head, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which: a flexible wiring member obtained by connecting a FPC and a FFC may have disconnection or cracks at an end of the junction thereof.SOLUTION: An electrode 302 of an FPC 15 and an electrode 312 of an FFC 16 are connected by soldering. A solder fillet 320 is formed in a substantially triangle shape with an acute top-most edge 312b on an apical surface 312a of the electrode 312 of the FFC 16 as an apex and a front-back direction of the electrode 302 of the FPC 15 as the base, and covers the apical surface 312a of the electrode 312 of the FFC 16.

Description

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

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

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself. In addition, the flexible wiring member and the actuator according to the present invention are not limited to those used in the liquid discharge head or the image forming apparatus, but the following description will be made on the flexible wiring member and actuator used in the actuator of the liquid discharge head.

  As the liquid discharge head, for example, a diaphragm member that forms a part of the wall surface of a plurality of pressure generation chambers individually corresponding to a plurality of nozzles arranged in parallel for discharging droplets is displaced by a piezoelectric element to generate each pressure. Some use a piezoelectric actuator that discharges droplets by changing the volume of the chamber. The actuator is not limited to a piezoelectric actuator, and for example, a thermal actuator, an electrostatic actuator, or the like may be used.

  For example, when using a piezoelectric actuator, the electrodes of each piezoelectric element are connected to a control unit via a flexible printed circuit board (hereinafter referred to as “FPC”) on which a drive circuit (driver IC) is mounted. And a flexible flat cable (hereinafter referred to as “FFC”) for transmitting various signals supplied from the apparatus main body side to the FPC, and a signal transmission for controlling the displacement of the piezoelectric element for each pressure generating chamber by the control unit. Like to do.

  Conventionally, as a connection structure for connecting an FPC and an FFC, for example, in order to reliably prevent a circuit pattern in the vicinity of the connection portion from being disconnected when bending stress is applied in the vicinity of the connection portion, a solder joint portion of the FPC and the FFC is used. Is known to be reinforced with an insulating film (Patent Document 1).

  In addition, in order to prevent the occurrence of disconnection between the FFC conductor and the circuit board, the lead terminal at the tip of the conductor located at the side edge in the width direction of the FFC is more widely exposed from the coating than the other lead terminals. Yes (Patent Document 2).

JP 2010-027762 A JP 2006-179192 A

  However, in the configuration disclosed in Patent Document 1, it is impossible to prevent disconnection and cracks caused by stress generated at the end of the solder joint. In addition, there is a problem that it is impossible to prevent disconnection and cracks that are easily generated starting from a hard and brittle layer generated by copper erosion.

  Further, even with the configuration disclosed in Patent Document 2, there is a problem that it is not possible to prevent disconnection and cracks generated at the end of the solder joint due to stress generated at the end of the solder joint.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent disconnection and cracks that occur at the end of the solder joint when the electrodes of at least two flat cables are connected by solder joint. .

In order to solve the above problems, the flexible wiring member according to the present invention is:
A wiring board in which electrodes of at least two flexible cables are joined together by soldering,
The solder fillet at the connection portion of the two flexible cables has a configuration in which the thickness gradually or gradually decreases before and after the connection direction.

  Here, the film thicknesses of the electrodes of the two flexible cables can be different.

  In this case, it can be set as the structure from which the thickness of the said solder fit is thin before and behind the connection direction from the front-end | tip of a flexible cable with a thick film thickness of the said electrode among the said 2 flexible cables.

  Moreover, it can be set as the structure whose flexible cable with a thin film thickness of the said electrode is a flexible printed circuit board among the said 2 flexible cables.

  In this case, a solder film can be formed on the entire surface of the electrode of the flexible printed board.

  Moreover, it can be set as the structure whose flexible film | membrane with a thick film thickness of the said electrode is a flexible flat cable among the said 2 flexible cables.

  In addition, the distal end portion of one connection portion of the two flexible cables is formed in a shape that gradually or gradually increases in thickness from the distal end of the surface opposite to the joint surface toward the joint surface side, The thickness of the solder fillet from the front end of the connecting portion can be reduced in the connecting direction.

In addition, one tip portion of the two flexible cables is warped in a direction in which the tip side separates from the other flexible cable,
The solder fillet is formed in a substantially triangular shape with the tip of the surface opposite to the joint surface of the electrode of the one flexible cable as the apex and the longitudinal direction of the electrode of the other flexible cable as the base, and Covers the tip of one flexible cable electrode

  The actuator according to the present invention is one in which electrical wiring is made by the flexible wiring member according to the present invention.

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

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

  According to the flexible wiring board of the present invention, the solder fillet at the connecting portion of the two flexible cables has a configuration in which the thickness is gradually or stepwise reduced before and after the connecting direction. Stress concentration occurring in the substrate can be relaxed, and disconnection and cracks occurring in the flexible substrate electrode can be prevented. In addition, by forming the solder fillet shape so that the thickness is gradually or stepwise reduced before and after the connecting direction, solder wetting and spreading are not hindered, so that the generation of solder balls can be reduced. As a result, occurrence of a short circuit between the electrodes can be reduced. Furthermore, the resistance value can be stabilized as compared with the case where the fillet shape is inferior, and the electric characteristics are improved.

  According to the actuator of the present invention, since the electric wiring is made by the flexible wiring member of the present invention, the reliability is improved.

  According to the liquid ejection head according to the present invention, since the actuator according to the present invention is provided, the reliability is improved.

  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 is improved.

It is a schematic exploded perspective view showing an example of a liquid discharge head according to the present invention. It is sectional explanatory drawing along the liquid chamber longitudinal direction of the head. It is sectional explanatory drawing of an example along the liquid chamber transversal direction of the head. It is sectional explanatory drawing of the other example along the liquid chamber transversal direction of the head. It is expansion explanatory drawing of the connection part of the flexible wiring member in 1st Embodiment of this invention. FIG. 6 is a cross-sectional explanatory view taken along line AA in FIG. 5. It is an expansion explanatory view before joining of the connection part of the flexible wiring member. It is expansion explanatory drawing of the connection part with which it uses for description of the joining process of the flexible wiring member. It is explanatory drawing explaining the shape of the solder joint part of FPC and FFC of a comparative example. It is expansion explanatory drawing of the electrode part in the connection part of the flexible wiring member in 2nd Embodiment of this invention. It is expansion explanatory drawing of the electrode part in the connection part of the flexible wiring member in 3rd Embodiment of this invention. It is expansion explanatory drawing of the electrode part in the connection part of the flexible wiring member in 4th Embodiment of this invention. It is expansion explanatory drawing of the electrode part in the connection part of the flexible wiring member in 5th Embodiment of this invention. (A) Explanatory drawing used for description of the connection part before joining of the flexible wiring member in 6th Embodiment of this invention, (b) is an expanded explanatory view of the electrode part in the connection part which shows the state after joining. FIG. 3 is a side explanatory view of a mechanism unit of the image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part.

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

  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 which is an actuator 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 columns 12A and 12B are formed in a comb-like shape at a predetermined interval with respect to the piezoelectric member 12. The piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, but a piezoelectric column that is driven by giving a driving waveform is a driving column 12A, and a piezoelectric column that is used as a simple column without giving a driving waveform is a non-driving column. It is distinguished as 12B. Then, the upper end surface (joint surface) of the drive 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 Resulting in displacement.

  The piezoelectric member 12 is connected to a flexible wiring member 300 according to the present invention for supplying a drive signal to the drive column 12A. The flexible wiring member 300 is formed by soldering an FPC 15 that is a flat cable and an FFC 16 that is a flat cable, and the FPC 15 is a driver IC (drive circuit) that applies a drive waveform (drive signal) to the drive column 12A (not shown). Is mounted and connected to the piezoelectric member 12, and the other end of the FFC 16 is connected to a control board (control unit) (not shown) of the apparatus main body.

  Here, as described above, the piezoelectric columns 12A and 12B of the piezoelectric member 12 are the same, and the piezoelectric column to be driven by giving a driving waveform is used as the driving column 12A, and a simple column without giving the driving waveform. A non-driving column 12B is used as the non-driving column 12B, and the driving column 12A and the non-driving column 12B are alternately used as shown in FIG. 3, but all the piezoelectric columns are driven as shown in FIG. It can also be set as the normal pitch structure used as the pillar 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 ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the drive column 12A according to an image recorded from a control unit (not shown). As a result, the drive column 12A to which the pulse voltage is applied is displaced to deform the vibration region 2a of the vibration plate member 2 in the direction of the nozzle plate 3, and the ink in the liquid chamber 6 is removed by the change in volume (volume) of the liquid chamber 6. By applying pressure, droplets are discharged from the nozzles 4 of the nozzle plate 3. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, when the voltage application to the piezoelectric column 12A is turned off, the diaphragm member 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. . At this time, ink is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  In addition to the above-described punching, the liquid discharge head is not limited to the pulling method (a method in which the vibrating plate member 2 is released from the pulled state and pressurized with a restoring force), and the pulling-pushing method (the vibrating plate member 2 is fixed). It can also be driven by a method such as a method of holding at an intermediate position, pulling from this position, and then extruding.

  Next, the flexible wiring member in 1st Embodiment of this invention is demonstrated with reference to FIG. 5 thru | or FIG. 5 is an enlarged explanatory view of the connecting portion of the flexible wiring member, FIG. 6 is a sectional explanatory view taken along line AA of FIG. 5, and FIG. 7 is an enlarged explanatory view of the connecting portion of the flexible wiring member before joining. FIG. 8 is an enlarged explanatory view of a connecting portion for explaining the joining process of the flexible wiring member.

  As described above, the flexible wiring board 300 is formed by connecting the FPC 15 and the FFC 16 by soldering.

  In the FPC 15, an electrode 302 made of a conductor pattern is formed on a base material 301, and the electrode 302 is covered with a protective film 303. The substrate 301 is made of polyimide, the conductor pattern (electrode) 302 is made of Cu, and the protective film 302 is made of a resist. A two-layer solder 305 made of Sn (underlayer) and SnBi is formed in advance on the connection portion 304 of the electrode 302 not covered with the protective film 303 by plating.

  In the FFC 16, an electrode 312 made of a conductor pattern is formed on a base material 311 and is covered with a protective film 313. The base material 311 and the protective film 313 are made of PET resin, and the conductor pattern (electrode) 312 is made of Cu. The connection portion 314 not covered with the protective film 313 of the electrode 302 is subjected to Ni and Au two-layer plating 315.

  Further, the tip end portion 316 of the connection portion 314 of the FFC 16 with the FPC 15 is cut by pressing or shearing, and is formed to warp in the direction opposite to the surface (joining surface) to be joined to the FPC 15. Further, the tip 316 of the connecting portion 314 of the FFC 311 is formed in such a shape that the tip of the surface opposite to the bonding surface side of the tip surface 312a of the electrode 312 is the leading edge 312b by cutting the tip obliquely.

  The width W1 of the electrode 302 of the FPC 15 is formed to be narrower than the width W2 of the electrode 312 of the FFC 16.

  Then, as shown in FIG. 8, a part of the connection part 304 of the FPC 15 and a part of the connection part 414 of the FFC 16 are overlapped and heated by the heater chip 400 to melt the solder 305 of the FPC 15. The connecting portion 314 of the FFC 16 is joined and connected via the solder 305.

  At this time, the tip portion 316 of the connection portion 314 of the FFC 16 has a shape that warps on the opposite side to the joint surface with the FPC 15, and the tip surface 312a of the electrode 312 of the joint portion 314 recedes from the leading edge 312b to the joint surface side. The melted solder 305 wets and spreads to the tip surface 312a of the electrode 312 of the FFC 16 and also enters between the bonding surface side of the tip 316 and the electrode 302.

  As a result, the solder fillet 320 formed of the melted solder 305 has a substantially triangular shape with the sharpest tip 312b of the tip surface 312a of the electrode 312 of the FFC 311 as the apex and the front and back direction of the electrode 302 of the FPC 15 as the base. The tip end surface 312a of the electrode 312 of the FFC 311 is formed. That is, the solder fillet 320 has a shape in which the thickness gradually decreases from the tip 312b of the electrode 312 of the FFC 311 in the connecting direction.

  As described above, since the thickness of the solder fillet 320 is the thickest at the tip surface 312a of the electrode 312 of the FFC 16, the bonding strength at the tip 316 is maximized at the connection portion 314 of the FFC 16, and the tip 316 of the FFC 16 is the starting point. Disconnection and cracks of the electrode 302 of the FPC 15 can be reduced.

  In this case, the solder 305 is plated on the FPC 15 side in advance, and the connection portion 304 of the FPC 15 and a part of the connection portion 314 of the FFC 16 are overlapped so that the connection portion 314 of the FFC 16 is positioned at the connection portion 304 (plating portion) of the FPC 15. Since the solder 305 is also present on the FPC 15 side from the front end of the FFC 16, the solder 205 is less likely to be wet and spread, and the solder fillet having the above-described shape can be easily formed.

  In addition, when the structure which provides solder plating in the FFC16 side is taken, since there is no solder ahead of the edge part of FFC16 (FPC15 side) at the time of joining, it is easy to generate | occur | produce the fillet defect by insufficient wetting and spreading of solder.

  In addition, by using SnBi (melting point 214 ° C.) having a low melting point as the solder 305, bonding at a lower temperature than Sn (melting point 232 ° C.) is possible, and melting of the FFC 16 resin (base material 311) can be reduced. A solder fillet shape can be obtained. In addition, by performing low-temperature bonding using a low melting point solder, it is possible to reduce the occurrence of so-called “Cu erosion” in which Cu melts into the solder at a high temperature to form a brittle layer. It is possible to reduce disconnection and cracks generated by the stress generated at the end portion (meaning the portion where FPC 15 and FFC 16 are joined). Furthermore, the generation of solder balls can be reduced by performing low-temperature bonding using low melting point solder.

  In addition, by forming the Au plating film 315 on the surface of the electrode 312 of the FFC 16, the solder becomes more easily spread and a good solder fillet shape can be obtained.

  Further, by making the width W2 of the electrode 312 of the FFC 16 wider than the width W1 of the electrode 302 of the FPC 15 heated by the heater chip, the solder balls can be further reduced. In other words, when the width W1 of the electrode 302 of the FPC 15 subjected to solder plating is wider than the width W2 of the electrode 312 of the FFC 16, solder balls are likely to occur and solder overflow is likely to occur.

  Moreover, the cutting | disconnection method of FFC16 can make the front-end | tip part shape of the junction part 314 into a substantially triangle or a substantially trapezoid by performing by press, shearing, etc. as mentioned above. In order to align the shape of the tip of the electrode 312 of the FFC 16, it is preferable to use an FFC in which the exposed electrode 312 faces the same surface.

Here, as a comparative example, the shape of the solder joint portion of the FPC and FFC of the comparative example will be described with reference to FIG.
In this comparative example, the solder fillet 520 swells at the tip end surface 312a of the electrode 312 of the FFC 16 at the connection portion between the FPC 15 and the FFC 16.

  Therefore, a crack is generated at the end of the solder joint due to the stress generated at the end (tip) of the solder joint at the time of joining the FPC 15 and the FFC 16.

  As described above, the solder fillet at the connection portion of the two flexible cables constituting the flexible wiring member has a shape in which the thickness is gradually or stepwise reduced before and after the connection direction, so that the end of the solder joint portion It is possible to alleviate the stress concentration that occurs in the substrate, and it is possible to prevent disconnection and cracks reported to the flexible wiring board.

  In addition, by forming the solder fillet shape so that the thickness is gradually or stepwise reduced before and after the connecting direction, solder wetting and spreading are not hindered, so that the generation of solder balls can be reduced. As a result, occurrence of a short circuit between the electrodes can be reduced. Further, the resistance value can be stabilized as compared with the case where the fillet shape is poor, and the electrical characteristics are improved.

  One of the two flexible cables has a distal end warped in a direction in which the distal end side is away from the other flexible cable, and the solder fillet has the distal end on the surface opposite to the joint surface of one flexible cable as the apex. The thickness of the other flexible cable can be easily connected by forming a substantially triangular shape with the base of the longitudinal direction of the electrode of the other flexible cable and covering the tip surface of the electrode of the one flexible cable. It is possible to obtain a solder fillet shape that becomes gradually thinner before and after the direction, and to relieve stress concentration generated at the end of the solder joint, thereby preventing disconnection and cracking of the flexible wiring board.

Next, the flexible wiring member in 2nd Embodiment of this invention is demonstrated with reference to FIG. In addition, FIG. 10 is an enlarged explanatory view of an electrode portion in a connection portion of the flexible wiring member.
In the present embodiment, the tip 316 of the electrode 312 of the FFC 16 is formed in a substantially triangular shape having an acute angle (this is an example in which the warp of the first embodiment is not provided).

  Even when the tip portion 316 of the electrode 312 of the FFC 16 has such a shape, the substantially triangular solder fillet 320 is formed at the time of joining, and the stress generated at the end of the solder joining portion can be relieved. Disconnection and cracks generated at the end of the can be reduced. Further, since it is not necessary to warp the FFC 16, the thickness of the solder joint can be minimized, and there is an effect of saving space.

Next, the flexible wiring member in 3rd Embodiment of this invention is demonstrated with reference to FIG. In addition, FIG. 11 is an enlarged explanatory view of an electrode portion in a connection portion of the flexible wiring member.
In the present embodiment, the tip portion 316 of the electrode 312 of the FFC 16 is formed in a trapezoidal shape with the joint surface side receding obliquely.

  Even if the tip 316 of the joint portion 314 of the electrode 312 of the FFC 16 is formed in such a shape, a substantially triangular solder fillet 320 is formed at the time of joining, and the stress generated at the end of the solder joint can be relieved. It is possible to reduce disconnection and cracks generated at the end of the solder joint.

  Further, with such a configuration, it is not necessary to cut the tip of the FFC obliquely as described above, and the FFC tip can be formed by lightly grinding the tip after cutting vertically. When the tip of the FFC 16 is cut obliquely, the cut counterpart is cut in a reverse inclination, so that it cannot be used as the FFC 16 of the present invention and wastes the material. The material of FFC 16 can be used effectively without waste.

Next, the flexible wiring member in 4th Embodiment of this invention is demonstrated with reference to FIG. In addition, FIG. 12 is an enlarged explanatory view of an electrode portion in a connection portion of the flexible wiring member.
In the present embodiment, the joint surface side of the tip portion 316 of the electrode 312 of the FFC 16 is formed in a step shape.

  By forming the tip 316 of the joint portion 314 of the electrode 312 of the FFC 16 in this shape, the solder fillet 320 gradually decreases in thickness toward the FPC 15 side and gradually decreases in the connection direction in the FFC 16 side. The stress generated at the end of the solder joint can be relaxed, and disconnection and cracks generated at the end of the solder joint can be reduced. In addition, the bonding strength can be further improved by the presence of the stepped portion.

Next, the flexible wiring member in 5th Embodiment of this invention is demonstrated with reference to FIG. FIG. 13 is an enlarged explanatory view of the electrode portion in the connection portion of the flexible wiring member.
In the present embodiment, the joining surface side of the tip portion 316 of the electrode 312 of the FFC 16 is formed in a curved shape (bow shape) so as to be a concave shape.

  Even if the tip portion of the joining portion 314 of the electrode 312 of the FFC 16 is formed in such a shape, a substantially triangular solder fillet 320 is formed at the time of joining, and the stress generated at the end of the solder joining portion can be relieved. Disconnections and cracks that occur at the end of the solder joint can be reduced. Further, since the solder can be accommodated in the concave portion, it is possible to reduce the amount of solder protrusion as compared with the second embodiment.

Next, the flexible wiring member in 6th Embodiment of this invention is demonstrated with reference to FIG. 14A is an explanatory diagram for explaining the connection portion before joining, and FIG. 14B is an enlarged explanatory view of an electrode portion in the connection portion showing a state after joining.
Here, a reinforcing plate 331 is provided on the surface of the base material 311 on the FFC 16 side, and an insulating film 332 is provided on the surface opposite to the bonding surface of the electrode 15 of the FPC 15 after bonding. This insulating film 332 is a tough, excellent heat resistance, low water absorption polyethylene terephthalate (PET) layer and an acrylic resin layer, and the outer surface of the PET layer is coated with a charged layer, and the outer surface of the acrylic resin layer is coated. Has an adhesive seal, and is formed by covering the adhesive seal with release paper.

  That is, the reinforcing plate 331 is provided on the surface of the FFC 16 opposite to the electrode 312 of the base material 311, and when connecting the electrode 302 of the FPC 15 and the electrode 313 of the FFC 16, the FPC 15 Heat is applied to the solder 305 on the electrode 302 so that the solder 305 is thermally fused and electrically connected.

  Further, by increasing the plating thickness of the solder 305 on the electrode 302 of the FPC 15, excess solder flows out when the FFC 16 and the FPC 15 are joined, and remains at the tip of the FPC 15 (solder 340). Although this portion is exposed to the outside of the FPC 15 and there is a risk of short-circuiting, it is possible to improve electrical reliability by covering this portion with the insulating film 332.

  At this time, as shown in FIG. 14 (b), the insulating film 332 is attached so as to cover at least the front end portion of the FFC 16, preferably the entire solder joint region, so that the functional insulating film 332 having a multilayer structure is formed. Is used as a reinforcing member to prevent pattern breakage in the conductor pattern of the FPC 15 at the solder joint, thereby causing problems in the output image.

  Since the actuator in which the electrical wiring is performed by the flexible wiring member 300 of each of the above-described embodiments reduces the disconnection and cracks of the wiring member, the reliability is improved. Similarly, the reliability of the liquid discharge head including this actuator is also improved.

  Note that a head-integrated liquid cartridge (cartridge-integrated head) can be obtained by integrating the above-described liquid discharge head and a tank that supplies liquid to the liquid discharge head.

Next, an 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 FIGS. FIG. 15 is an explanatory side view of the mechanism part of the apparatus, and FIG. 16 is an explanatory plan view of the main part of the mechanism part.
This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes a plurality of recording heads 234 including the liquid ejection head according to the present invention for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Nozzle rows composed of 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 feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

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

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

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

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

  Further, a maintenance / recovery mechanism 281 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 when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge thickened ink. Yes.

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

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

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

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

  As described above, since the image forming apparatus includes the liquid discharge head according to the present invention, the reliability is improved and a high-quality image can be formed.

  In the above-described embodiment, the example in which the present invention is applied to the serial type image forming apparatus has been described. However, the present invention can be similarly applied to a line type image forming apparatus. In the above-described embodiment, the example in which the FPC and the FFC are connected has been described. However, the present invention can be similarly applied to the connection between the FPC and the FPC and the FFC and the FFC.

1 Channel plate (channel substrate)
2 Vibrating plate member 3 Nozzle plate 4 Nozzle 6 Liquid chamber 10 Common liquid chamber 12 Piezoelectric member 12A Driving column 12B Non-driving column 112 Piezoelectric column 13 Base member 15 FPC (flexible wiring board)
16 FFC (flexible flat cable)
23 Electrode 300 Flexible wiring member 302 Electrode 304 Connection portion 305 Solder 312 Electrode 314 Connection portion 233 Carriage 234a, 234b Recording head

Claims (11)

A wiring board in which electrodes of at least two flexible cables are joined together by soldering,
A flexible wiring member, wherein the solder fillet at the connection portion of the two flexible cables has a shape in which the thickness gradually decreases before and after the connection direction.   The flexible wiring member according to claim 1, wherein the film thicknesses of the electrodes of the two flexible cables are different.   3. The flexible wiring member according to claim 2, wherein the thickness of the solder fit is reduced in the connecting direction from the front end of the flexible cable having the electrode having a large thickness among the two flexible cables.   The flexible wiring member according to any one of claims 1 to 3, wherein a flexible cable having a thin film thickness of the electrode is a flexible printed circuit board among the two flexible cables.   The flexible wiring member according to claim 4, wherein a solder film is formed on the entire surface of the electrode of the flexible printed board.   The flexible wiring member according to any one of claims 1 to 5, wherein a flexible cable having a thick film thickness of the electrode is a flexible flat cable among the two flexible cables.   The distal end portion of one connection portion of the two flexible cables is formed in a shape in which the thickness gradually or gradually increases from the distal end of the surface opposite to the joint surface toward the joint surface side, and the one connection portion The flexible wiring member according to any one of claims 1 to 6, wherein the thickness of the solder fillet is reduced from the front end to the front and rear in the connecting direction. One tip of the two flexible cables is warped in the direction in which the tip side is away from the other flexible cable,
The solder fillet is formed in a substantially triangular shape with the tip of the surface opposite to the joint surface of the electrode of the one flexible cable as the apex and the longitudinal direction of the electrode of the other flexible cable as the base, and A flexible wiring member, characterized in that the tip end surface of an electrode of one flexible cable is covered.   An actuator characterized in that electrical wiring is made by the flexible wiring member according to any one of claims 1 to 8.   A liquid discharge head comprising the actuator according to claim 9.   An image forming apparatus comprising the liquid discharge head according to claim 9.

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