JP5521652B2 - Piezoelectric actuator, liquid discharge head, and image forming apparatus - Google Patents

Description

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

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

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

  Conventionally, as a liquid discharge head, a piezoelectric element, particularly a stacked piezoelectric element in which piezoelectric layers and internal electrodes are alternately stacked, is used as pressure generating means (actuator means) for generating pressure to pressurize ink that is liquid in a liquid chamber. Using a so-called piezoelectric actuator that deforms an elastically deformable diaphragm that forms the wall surface of the liquid chamber by displacement in the d33 or d31 direction of the multilayer piezoelectric element, and discharges the liquid droplet by changing the volume / pressure in the liquid chamber The piezoelectric head used is known.

  In such a piezoelectric head, for example, using a laminated piezoelectric element, an FPC (flexible substrate) is provided for each of an external electrode (also referred to as an end face electrode) serving as a common electrode with internal electrodes drawn to the end face and an external electrode serving as an individual electrode. Common wiring electrodes and individual wiring electrodes of wiring members such as flexible printed cables and flexible wiring boards) are joined, and a drive signal corresponding to an image signal is given to each piezoelectric element.

  In this case, both ends of the piezoelectric element member forming the piezoelectric element column are set as non-driving piezoelectric element columns, and a common electrode is provided on the non-driving piezoelectric element column at both ends to join the common wiring electrode of a wiring member such as an FPC. One is known (Patent Document 1).

  In a line-type head in which a plurality of nozzle openings are arranged on one continuous nozzle plate, and the piezoelectric element is formed by processing a plurality of bulk piezoelectric bodies so as to correspond to the nozzle openings. It is also known that the common electrode of the piezoelectric body conducts the conductive portion of the piezoelectric body with respect to the conductive base member, and the common electrode is taken out from the conductive base member (Patent Document 2).

  In addition, it is also known that a wiring pattern is formed on a base member plate, and the wiring pattern and an electrode pattern of a piezoelectric element are electrically connected by a resin material containing conductive particles (Patent Document 3).

Japanese Patent No. 3114771 JP 2007-055021 A JP 2005-035226 A

  By the way, as the image forming apparatus increases in speed, the liquid discharge head also becomes longer. With this, a plurality of piezoelectric element columns arranged on the end side and a central piezoelectric element column are arranged. The difference in the resistance value of the voltage application path (generally formed by a metal thin film formed on the surface of the piezoelectric element) becomes large, and a uniform displacement amount cannot be secured in each piezoelectric element column. There are challenges.

  Therefore, this voltage application path was filled with a conductive resin or the like to increase the cross-sectional area and reduce the resistance. However, with the increase in the length of the head, the conductive resin is joined to the metal layer of the piezoelectric element. The resistance is no longer negligible. In order to reduce the resistance of the joint, metal fusion joining using solder or the like (melting and joining the metal) is effective, but the base member has a weight (size) to reduce vibration of the piezoelectric element. Therefore, the base member has a large heat capacity. Therefore, a large amount of heat is required for soldering, and for example, solder in a fine region such as a gap between piezoelectric element members is heated and melted. Was difficult.

  The present invention has been made in view of the above-described problems. For example, it is possible to reduce the amount of heat necessary for metal fusion bonding using a laser or the like to bond a fine bonding region with low resistance, and to apply a voltage application path. The resistance value can be freely set by controlling the cross-sectional area.

In order to solve the above problems, the piezoelectric actuator is
A plurality of piezoelectric element columns are formed on a plurality of piezoelectric element members disposed on the base member,
A wiring member is joined to the piezoelectric element column,
On the base member, a low thermal conductive layer and a conductive layer having a thermal conductivity lower than that of the base member are laminated at least in a region other than a joint portion with the piezoelectric element member,
A part of the conductive layer is melted or joined to the common electrode of the piezoelectric element column via a molten metal.

  Here, the conductive layer on the base member may be configured not to be formed at a joint portion between the base member and the piezoelectric element member.

  Further, the low thermal conductive layer on the base member may be configured not to be formed at a joint portion between the base member and the piezoelectric element member.

  The base member may be formed of a conductive member, and the conductive layer and the base member may be electrically connected.

  Further, a metal layer made of a metal material different from the conductive layer may be formed between the low thermal conductive layer and the conductive layer.

  Moreover, it can be set as the structure by which the conductive layer of the material different from the said base member is formed in at least one part between the said base member and the said low heat conductive layer.

  Further, the low thermal conductive layer can be configured to have conductivity.

  Further, the low thermal conductive layer can be configured to be positioned at a position lower than the bottom of the groove forming the plurality of piezoelectric element columns in the piezoelectric element member.

  The piezoelectric element members may be arranged in two rows on the base member, and the distance between the two rows of piezoelectric element members may be abutted against the low thermal conductive layer.

  In addition, at least two rows of the piezoelectric element members are arranged on the base member, and a concave portion lower than the joint surface between the base member and the piezoelectric element member is formed between the rows of the piezoelectric element members. The low thermal conductive layer can be formed on the bottom surface of the recess.

  In this case, the width of the recess can be larger than the width between the rows of the piezoelectric element members.

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

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

  According to the piezoelectric actuator of the present invention, the low thermal conductive layer and the conductive layer having a lower thermal conductivity than the base member are laminated on the base member at least in a region other than the joint portion with the piezoelectric element member. Since the layer is partly melted or joined to the common electrode of the piezoelectric element column via molten metal, for example, the amount of heat required for metal fusion joining using a laser or the like is reduced and fine joining is performed. The region can be bonded to a low resistance, and the resistance value can be freely set by controlling the cross-sectional area of the voltage application path by controlling the thickness of the metal formed by melting.

  According to the liquid discharge head according to the present invention, since the piezoelectric actuator according to the present invention is provided, good droplet discharge characteristics can be obtained.

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

1 is an exploded perspective view of a first embodiment of a liquid ejection 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 in alignment with the nozzle arrangement direction (liquid chamber short direction) of the head. It is side surface explanatory drawing similarly explaining joining with a wiring member (illustrated in the permeation | transmission state). It is a section explanatory view excluding the wiring member of a 1st embodiment of a piezoelectric actuator concerning the present invention. It is sectional explanatory drawing with which it uses for description of the manufacturing process before the slit process of the piezoelectric element member of the actuator. It is a plane explanatory view of the internal electrode of the piezoelectric element member before slit processing. It is sectional explanatory drawing except the wiring member of 2nd Embodiment of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 3rd Embodiment of the piezoelectric actuator which concerns on this invention. It is a disassembled perspective explanatory drawing of 2nd Embodiment of the liquid discharge head which concerns on this 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 a partial cross-sectional explanatory drawing along the nozzle arrangement direction (liquid chamber short direction) of the head. It is side surface explanatory drawing similarly explaining joining with a wiring member (illustrated in the permeation | transmission state). It is sectional explanatory drawing except the wiring member of 4th Embodiment of the piezoelectric actuator which concerns on this invention. It is a cross-sectional explanatory drawing except the wiring member of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 5th Embodiment of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 6th Embodiment of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 7th Embodiment of the piezoelectric actuator which concerns on this invention. It is explanatory drawing of the manufacturing process of the polyimide sheet of the actuator. It is sectional explanatory drawing except the wiring member of 8th Embodiment of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 9th Embodiment of the piezoelectric actuator which concerns on this invention. It is sectional explanatory drawing except the wiring member of 10th Embodiment of the piezoelectric actuator which concerns on 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. A first embodiment of a liquid discharge head including a piezoelectric actuator according to the present invention will be described with reference to FIGS. 1 is an exploded perspective view of the head, FIG. 2 is a cross-sectional view along a direction (liquid chamber longitudinal direction) orthogonal to the nozzle arrangement direction of the head, and FIG. 3 is a nozzle arrangement direction of piezoelectric actuators of the head. Cross-sectional explanatory drawing along the (liquid chamber short direction), FIG. 4 is also a side explanatory view for explaining the joining with the wiring member (illustrated in a transparent state).

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

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

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

  Here, the piezoelectric element member 12 is formed by alternately stacking the piezoelectric material layers 21 and the internal electrodes 22A and 22B, and the internal electrodes 22A and 22B are respectively provided on the end surfaces, that is, the diaphragm member 2 of the piezoelectric element member 12. By pulling out to the vertical side surface, connecting to the end face electrodes (external electrodes) 23, 24 formed on the side face, and applying a voltage between the end face electrodes (external electrodes) 23, 24, displacement in the stacking direction occurs. Here, the external electrode 23 is used as an individual external electrode (individual electrode), and the external electrode 24 is used as a common external electrode (common electrode).

  This piezoelectric element member 12 is formed by processing grooves 31 (FIG. 3) by half-cut dicing and forming a required number of piezoelectric element columns 12A and 12B in a comb-like shape at a predetermined interval with respect to one piezoelectric element member. It is. The piezoelectric element columns 12A and 12B of the piezoelectric element member 12 are the same, but the piezoelectric element column that is driven by giving a drive waveform is used as a drive piezoelectric element column 12A, and a piezoelectric element that is used as a simple support without giving a drive waveform. The element columns are distinguished as non-driving piezoelectric element columns 12B. Further, the non-driving piezoelectric element column 12B at the end of the piezoelectric element member 12 is a non-driving piezoelectric element column 12Ba formed wide to take out the common electrode to the outside.

  The piezoelectric element member 12 is connected to an FPC 15 as a flexible wiring member for giving a driving signal to the driving piezoelectric element column 12A. The FPC 15 includes a common wiring electrode 41 connected to the individual electrode 23 of the driving piezoelectric element column 12A and a common electrode 24 connected to the common electrode 24 of the plurality of driving piezoelectric element columns 12A taken out to the non-driving piezoelectric element 12Ba at the end. A common wiring electrode 42 connected to the common electrode portion 25 is provided. The FPC 15 is bonded to the base member 13 in the vicinity of the piezoelectric element member 12 with a hot melt adhesive (not shown). In addition, as a heating method for connecting the FPC 15 and the piezoelectric element member 12, there are a contact heating method using a heater and a non-contact heating method using a laser or the like, but laser bonding is preferable. The FPC 15 and the piezoelectric element member 12 may be bonded to each other with a rigid member such as, but it is preferable that the FPC 15 and the piezoelectric element member 12 are bonded to each other with a laser while being closely bonded by air pressure.

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

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

  Further, a frame member 17 formed by injection molding with epoxy resin or polyphenylene sulfite is bonded to the outer peripheral side of the piezoelectric actuator 100 according to the present invention composed of the piezoelectric element member 12, the base member 13, the FPC 15, and the like. doing. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port 19 for supplying a recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as an ink cartridge.

  In the liquid ejection head configured as described above, for example, when driven by a punching method, a drive pulse voltage of 20 to 50 V is selectively applied to the drive piezoelectric element column 12A according to an image recorded from a control unit (not shown). When applied, the driving piezoelectric element 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 liquid chamber 6 is changed by the volume (volume) change of the liquid chamber 6. By pressurizing the liquid inside, droplets are ejected from the nozzle 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, by turning off the application of voltage to the driving piezoelectric element column 12A, the diaphragm 2 returns to the original position and the liquid chamber 6 becomes the original shape, so that further negative pressure is generated. To do. 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 first embodiment of a piezoelectric actuator according to the present invention that constitutes the liquid ejection head will be described with reference to FIG.
In the piezoelectric actuator 100, the piezoelectric element member 12 is bonded to the base member 13 with an adhesive 50, and the region other than the bonding region of the base member 13 with the piezoelectric element member 12 is more thermally conductive than the base member 13. The low thermal conductive layer 51 and the conductive layer 52 having a low rate are laminated, and a part of the conductive layer 52 is melted and joined to the common electrode 24 of the piezoelectric element member 12.

  Here, SUS is used as the base member 13, but is not limited thereto. For example, Cu or the like may be used as long as the vibration generated when the driving piezoelectric element column 12A of the piezoelectric element member 12 is driven can be efficiently suppressed.

  Although the polyimide is used as the low thermal conductive layer 51, it is not limited to this. For example, an inorganic material such as ceramic or metal oxide, or a heat resistant material such as an organic material may be used. Further, a metal material with low thermal conductivity such as Ti may be used instead of polyimide. Ti is about 1/20 of the thermal conductivity of Cu, has a high heat storage effect, and is electrically conductive, so that a sufficient conductive area can be taken, which is advantageous for low resistance.

  As the conductive layer 52, the conductive layer 52 is formed using a solder paste, and metal fusion bonding with the common electrode 24 is performed.

  In this way, on the base member, a low thermal conductive layer and a conductive layer having a lower thermal conductivity than the base member are laminated in a region other than the bonding region with the piezoelectric element member, and the conductive layer partially melts. In this configuration, first, a low thermal conductive layer is provided to reduce the amount of heat necessary for metal fusion bonding using, for example, a laser, thereby forming a fine bonding region. The resistance value can be set freely by controlling the cross-sectional area of the voltage application path by controlling the thickness of the metal formed by melting.

  Second, the voltage application path of the common electrode for the plurality of piezoelectric element pillars is formed of a conductive layer, so that the resistance of the voltage application path can be reduced and applied to a liquid discharge head. The displacement characteristics of each piezoelectric element column in the direction can be made uniform, and stable droplet ejection characteristics can be obtained.

  Next, an example of the manufacturing process of this piezoelectric actuator will be described with reference to FIGS. 6 is a cross-sectional explanatory diagram for explaining the manufacturing process before slitting of the piezoelectric element member of the actuator, and FIG. 7 is a plan explanatory view of the internal electrode of the piezoelectric element member before slitting.

  First, in order to form the piezoelectric element member 12, as shown in FIG. 6A, an internal electrode 22A having the pattern shown in FIG. 7A and an internal electrode 22B having the pattern shown in FIG. Of the piezoelectric element members 70 are alternately stacked via the piezoelectric layers 21, and a metal film 71 is formed on the piezoelectric element member 70 as shown in FIG. 6B. As the material of the metal film 71, Ag, Au, Cu, or the like can be used. In this example, Au is formed to a thickness of 0.4 μm by sputtering. After that, as shown in FIG. 6C, a processed surface 74 is formed by obliquely notching the end portion that becomes the outer side in the short direction of the base member 13 at the time of joining on the bottom side that becomes the joining surface with the base member 13. Thus, the individual electrode layer 72 and the common electrode layer 73 made of the metal film 71 are formed.

  Next, a photosensitive polyimide precursor serving as a heat storage layer (low thermal conductive layer) 51 is applied to the surface of the base member 13 to be bonded to the piezoelectric element member 70 in a thickness of 5 μm. The application method is not particularly limited, such as a transfer method, a spray method, or a dipping method. Thereafter, prebaking is performed at 100 ° C./1 minute, and the polyimide at the joint portion between the piezoelectric element member 70 and the base member 13 is removed by a photolithography process.

  In addition, the shape of the polyimide as the low heat conductive layer 51 may be a continuous line shape or an intermittent line shape. Here, a continuous linear pattern was used. Further, the height (thickness) of polyimide as the low thermal conductive layer 51 is set so as not to exceed the bottom 54 of the dicing cut when the groove is formed on the piezoelectric element member 70. Accordingly, when the piezoelectric element columns 12A and 12B are formed by dicing, polyimide is prevented from entering the cutting region of the dicing blade, and dicing of dissimilar materials is prevented to ensure the accuracy of forming the dicing groove and Long life can be achieved.

  Then, the patterned polyimide is baked at a high temperature of 300 ° C. for 5 hours, and a polyimide film is formed as the low thermal conductive layer 51.

  Thereafter, the adhesive 50 is applied to the back surface of the piezoelectric element member 70 or an opening 53 (region where polyimide is not formed) which becomes a bonding surface on the base member 13. As the adhesive 50, an epoxy adhesive, an ultraviolet curable adhesive, an anaerobic adhesive, or the like can be used. An anaerobic ultraviolet curable adhesive that cures at a low temperature and has a relatively fast curing time can be used. Used.

  Then, the piezoelectric element member 70 and the base member 13 are directly bonded with the adhesive 50. The piezoelectric element members 70 are positioned by abutting against the edge 51 a of the low thermal conductive layer (polyimide) 51. Since the low thermal conductive layer (polyimide) 51 is patterned by a photolithography process, it can be formed with high accuracy, and the piezoelectric element member 70 can be positioned by abutting and positioning on the polyimide formed with high accuracy. , 70 can be positioned with high accuracy. The piezoelectric element member 70 can be disposed with an accuracy of inter-column position of ± 10 μm by abutting positioning on the anaerobic ultraviolet curable adhesive 50 and the low thermal conductive layer (polyimide) 51.

  Next, a solder paste for forming the conductive layer 52 is supplied between the rows of the piezoelectric element members 70 and 70. As a supply method, it supplies by inject | pouring between rows by dispensing. As a method for heating the solder paste, a semiconductor laser was used, and the beam diameter was reduced to 500 μm and irradiated between the rows of the piezoelectric element members 70 and 70. The semiconductor laser locally heats the solder paste, and the heat supplied to the solder is stored by the low thermal conductive layer (polyimide) 51 on the base. Moreover, the common electrode layer 73 of the piezoelectric element members 70 and 70 is also heated by the irradiated laser, and the solder paste that becomes the conductive layer 52 is in contact with the metal portion of the common electrode layer 73 and is sufficiently melted. A state is obtained.

  The method of heating the solder paste that becomes the conductive layer 52 is not limited to the semiconductor laser, and a xenon lamp having a relatively small irradiation area may be used as the light source. It is also possible to melt the solder by bringing a heat source having a sharp tip such as a soldering iron close to the laser instead of a laser. The piezoelectric element member 70 and the base member 13 are directly bonded with the adhesive 50, so that the positional deviation of the piezoelectric element members 70 and 70 does not occur even after the solder paste is heated, and the positional accuracy before heating is increased. ± 10 μm or less can be secured.

  In this way, the piezoelectric element member 70 and the base member 13 are directly bonded by the adhesive 50, and heat is used to form an electrical connection for obtaining conduction of the solder paste that becomes the piezoelectric element member 70 and the conductive layer 52. Since it is difficult for the polyimide which is the low thermal conductive layer 51 to diffuse to the base member 13 side, a sufficient amount of heat is instantaneously stored in the solder paste and the underlying polyimide by spot heating using a laser. While maintaining a high-precision positional relationship between them, a good electrical connection can be formed between the common electrode layer 73 of the piezoelectric element members 70 and 70 and the solder paste as the conductive layer 51, and the resistance of the common electrode can be reduced. Is possible.

  Then, after the common electrode layers 73 and 73 of the piezoelectric element members 70 and 70 are metal-bonded to the conductive layer 52, the piezoelectric element member 70 is grooved to form the drive piezoelectric element columns 12A and 12B. The individual electrode layer 72 is made into the piezoelectric element member 12 divided into the individual electrodes 23, and then the piezoelectric actuator 100 is joined by bonding the electrodes 41 and 42 of the FPC 15 to the individual electrode 23 and the common electrode portion 25 of the piezoelectric element member 12. can get.

Next, a second embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG. FIG. 8 is an explanatory cross-sectional view of the actuator excluding the wiring member.
Here, in the first embodiment, after forming the low thermal conductive layer 51 formed on the base member 13, without forming the opening 53, the piezoelectric element member 12 with the adhesive 50 is directly formed on the low thermal conductive layer 51. 12 are joined. Even if it does in this way, since the effect similar to the said 1st Embodiment is acquired and the photolitho process which patterns a polyimide can be skipped, it can form at lower cost.

Next, a third embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG. FIG. 9 is an explanatory cross-sectional view of the actuator excluding the wiring member.
Here, in the first embodiment, after the opening 53 is formed in the low thermal conductive layer 51 formed on the base member 13, the metal layer 55 different from the conductive layer 52 is formed on the surface of the base member 13 and the low thermal conductive layer 51. The piezoelectric element members 12 and 12 are bonded onto the metal layer 55 with an adhesive 50. The material of the metal layer 55 is preferably a material such as Au or Ag that can be easily joined to the solder forming the conductive layer 52 and that the surface is not easily oxidized.

  As described above, a metal layer different from the conductive layer is formed between the low thermal conductive layer and the conductive layer, so that it is easy to form an alloy with the conductive layer, and it is possible to reduce electrical connection failure and The resistance of the electrode can be reduced. By using an inert material such as Au as the metal layer, there is an effect of preventing surface oxidation.

  Next, a second embodiment of the liquid ejection head according to the present invention will be described with reference to FIGS. 10 is an exploded perspective view of the head, FIG. 11 is a sectional explanatory view along a direction (liquid chamber longitudinal direction) perpendicular to the nozzle arrangement direction of the head, and FIG. 12 is a nozzle arrangement direction (liquid chamber) of the head. FIG. 13 is an explanatory side view for explaining the joining with a wiring member (shown in a transparent state).

  This liquid discharge head is configured as a line type head by arranging three piezoelectric element members 12 per row on the base member 13 with a gap 32 corresponding to the width of the groove 31. The electrical connection between the common electrode 24 of the piezoelectric element member 12 and the FPC 15 is performed by joining the common wiring electrode 42 of the FPC 15 to the base member 13 with solder or the like, as shown in FIG. Since the configuration other than the piezoelectric actuator 100 is substantially the same as that of the liquid ejection head according to the first embodiment, the corresponding portions are denoted by the same reference numerals and description thereof is omitted.

Therefore, a fourth embodiment of the piezoelectric actuator according to the present invention constituting this liquid discharge head will be described with reference to FIG. FIG. 14 is an explanatory cross-sectional view of the actuator excluding the wiring member.
In this piezoelectric actuator 100, a low thermal conductive layer 51 having a lower thermal conductivity than the base member 13 is formed on the base member 13, and a conductive layer including a through-hole-shaped opening 60 formed in the low thermal conductive layer 51. A common metal layer (a solder layer in this case) 61 is laminated, a conductive layer 52 is laminated on the solder layer 61, and the piezoelectric element member 12 is bonded to the solder layer 61 with an adhesive 50. A part of the conductive layer 52 is melted and joined to the electrode 24.

  Also in this embodiment, SUS is used as the base member 13, but the present invention is not limited to this. For example, a material having conductivity such as Cu may be used, and any material that can efficiently suppress vibration generated when the driving piezoelectric element column 12A of the piezoelectric element member 12 is driven may be used. It is preferable that the conductivity be as high as possible.

  Moreover, although the polyimide is used as the low heat conductive layer 51, it is not restricted to this. For example, an inorganic material such as ceramic or metal oxide, or a heat resistant material such as an organic material may be used. Further, a metal material with low thermal conductivity such as Ti may be used instead of polyimide. Ti is about 1/20 of the thermal conductivity of Cu, has a high heat storage effect, and is electrically conductive, so that a sufficient conductive area can be taken, which is advantageous for low resistance.

  As the conductive layer 52, the conductive layer 52 is formed using a solder paste, and metal fusion bonding with the common electrode 24 is performed. Further, although a solder layer is used as the metal layer 61, it is not limited to solder.

  Thus, on the base member, a low thermal conductive layer and a conductive layer having a lower thermal conductivity than the base member are laminated at least in a region other than the bonding region with the piezoelectric element member, and a part of the conductive layer is melted. By adopting a structure in which the piezoelectric element column is joined to the common electrode, for example, the amount of heat necessary for metal fusion joining using a laser or the like can be reduced, and a fine joining region can be joined with low resistance. In addition, by controlling the thickness of the metal formed by melting, the resistance value can be set freely by controlling the cross-sectional area of the voltage application path.

  Since the common electrode 24 of the piezoelectric element member 12 is electrically connected to the base member 13 through the conductive layer 52 and the solder layer (metal layer) 61, the common wiring electrode 42 of the FPC 15 is connected to the base member 13 as described above. Connected. As a result, the common electrode line can be easily taken out even with the configuration of the line type head.

Next, an example of the manufacturing process of this piezoelectric actuator will be described.
First, the piezoelectric element member 70 as described in the first embodiment is manufactured. Since the common electrode line is taken out from the base member 13, the internal electrodes 22A and 22B may have a pattern as shown in FIG. And the photosensitive polyimide precursor used as the thermal storage layer (low heat conductive layer) 51 is apply | coated to the surface joined to the piezoelectric element member 70 of the base member 13 by thickness 5 micrometers. The application method is not particularly limited, such as a transfer method, a spray method, or a dipping method. Thereafter, pre-baking is performed at 100 ° C./1 minute, and a through-hole shaped opening 60 is formed through a photolithography process. The through hole shape means a shape that penetrates, and the planar shape is not limited, and may be a hole shape or a slit shape.

  Then, the patterned polyimide is baked at a high temperature of 300 ° C. for 5 hours to form a polyimide film as the low thermal conductive layer 51.

  Next, a solder film to be the metal layer 61 was formed on the low thermal conductive layer (polyimide film) 51 with a thickness of 10 μm. As a method for forming the solder film, paste-like solder is formed by a screen printing method, but it is also possible to use a sputtering method or the like. Thereafter, by performing a heat treatment at 250 ° C., an electrical bond is formed at the interface between the base member 13 of the opening 60 and the solder to be the metal layer 61, and a stable bonded state is obtained.

  Thereafter, the adhesive 50 is applied to the back surface of the piezoelectric element member 70 and bonded onto the metal layer 61. The adhesive 50 is not limited as described above. Here, the piezoelectric element member 70 is joined with a positional accuracy of ± 5 μm using an ultraviolet curable adhesive.

  Next, the solder paste for forming the conductive layer 52 between the rows of the piezoelectric element members 70 and 70 is supplied by a dispenser or the like as described above. Subsequently, the injected solder paste is heated to be alloyed with the underlying solder layer (metal layer) 61. As a heating method, as described above, the semiconductor laser was used to squeeze the beam diameter to 500 μm and irradiate between the rows of the piezoelectric element members 70 and 70. Since the semiconductor laser is locally heated, the base member 13 and the entire piezoelectric element members 70 and 70 are not heated, and no difference in thermal expansion occurs. Also, the heat supplied to the solder is stored by the underlying polyimide film (low thermal conductive layer) 51, and the solder paste that becomes the conductive layer 52 becomes familiar with the underlying solder layer (metal layer) 61 to obtain a good alloy layer. I was able to. Moreover, the common electrode layer 73 of the piezoelectric element member 70 is also heated by the irradiated laser, and good bonding with the metal portion of the common electrode layer 73 is obtained.

  Thus, when metal fusion bonding is performed to obtain electrical continuity between the piezoelectric element member 70 and the base member 13, heat is diffused to the base member 13 side by the polyimide (low thermal conductive layer) 51 when heat is supplied. Therefore, a sufficient amount of heat is instantaneously stored in the solder paste and the underlying polyimide, and the base member 13 and the entire piezoelectric element member 70 do not need to be heated, and a good bonding can be obtained. As a result, a difference in linear expansion between the plurality of piezoelectric element members 70 and the base member 13 is unlikely to occur, and the piezoelectric element members 70 and 70 aligned with high accuracy are electrically stable while maintaining a highly accurate positional relationship. The conductive layer 52 (including the metal layer 61) can be obtained.

Next, a fifth embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG. In addition, the figure is sectional explanatory drawing except the wiring member of the actuator.
Here, in the fourth embodiment, the metal layer 62 formed of a metal other than solder is formed on the metal layer 61 formed of the solder layer, and the conductive layer 52 is formed on the metal layer 62. It is. The metal layer 62 is preferably made of a material such as Au or Ag that is easy to form a solder and alloy layer and is less likely to be oxidized on the surface.

  With this configuration, since the piezoelectric element member 12 is not directly fixed on the metal layer 61 formed of the solder layer, the metal layer 61 of the fixing part of the piezoelectric element is slightly melted when the conductive layer 52 is melted. Even if it does, it can prevent that the piezoelectric element member 70 shifts.

Next, a sixth embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG. In addition, the figure is sectional explanatory drawing except the wiring member of the actuator.
Here, in the fourth embodiment, a metal layer 63 made of a material other than the metal layer 61 and the conductive layer 52 and easily forming a solder and alloy layer is formed on the base member 13. A low thermal conductive layer 51 and a metal layer 61 are formed on 63. As the metal layer 63, Au was formed into a film with a thickness of 5 μm by sputtering. In addition to Au, other conductive materials such as Cu and Si can be used. By comprising in this way, the electrical joining of the base member 13 and the piezoelectric element member 12 can be stabilized, and a highly reliable joining state can be obtained.

Next, a seventh embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG. In addition, the figure is sectional explanatory drawing except the wiring member of the actuator.
Here, a metal layer 63 such as Au is formed on the base member 13, a solder layer 64 as a metal layer is formed on the metal layer 63, and Cu is formed on both surfaces of the polyimide 66 a on the solder layer 64. The polyimide sheet 66 on which the conductive layers 66 b and 66 c made of is formed is bonded, and the conductive layer 52 is further formed on the polyimide sheet 66.

  The metal layer 63 is formed with a thickness of 3 μm, for example, by sputtering, and the solder layer 64 is formed with a thickness of 10 μm by sputtering.

  For example, as shown in FIG. 19, the polyimide sheet 66 is formed by forming a photosensitive polyimide precursor 92 with a thickness of 20 μm on a Cu sheet 91 having a thickness of 10 μm to be a conductive layer 66b, and passing through a predetermined position through a photolithography process. After the opening 93 is formed, it is cured at 300 ° C. for 5 hours, and then Cu 94 to be the conductive layer 66c is formed on the sheet 91 and the precursor 92 to a thickness of 10 μm by sputtering or electroforming. The polyimide sheet 66 which is a laminate of the polyimide 92 and Cu 91 and 94 obtained in this way is placed on the base member 13 and subjected to heat treatment at 270 ° C., whereby the sheet 66 and the solder layer 63 on the base member 13 Can form an alloy layer to obtain an electrically conductive structure. After temporarily fixing a plurality of piezoelectric element members 70, 70 to such a structure, a solder paste is supplied between the rows of piezoelectric element members 70, 70, and Cu ( The conductive layer 66c is alloyed.

  In the present embodiment, since the polyimide sheet 66 that becomes the low thermal conductive layer is manufactured separately from the base member 13, the process time can be shortened by parallelizing the steps. Moreover, since the polyimide sheet 66 can be manufactured by arranging individual pieces and making them large, a sheet for a low thermal conductive layer can be formed at low cost.

  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 eighth embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG.
In the present embodiment, a recess 57 lower than the joint surface 53 between the base member 13 and the piezoelectric element member 12 is formed in the base member 13 between the rows of the piezoelectric element members 12, 12. A polyimide 51 which is a conductive layer is formed.

  Here, it is preferable that the width (width in the direction orthogonal to the row direction) W1 of the recess 57 is equal to or greater than the width W2 (for example, about 0.3 mm) between the rows of the piezoelectric element members 12 and 12. Further, the cross-sectional shape of the recess 57 (the cross-sectional shape in FIG. 20) is not limited to a rectangle, and may be a curved R shape. Furthermore, it is preferable that the depth of the concave portion 57 is not less than ½ of the width W1 of the concave portion 57.

Here, an example of the manufacturing process of the piezoelectric actuator of this embodiment will be described.
For example, the concave portion 57 is formed between the rows of the piezoelectric element members 70 and 70 on the surface of the base member 13 made of SUS, Cu, or the like, which is joined to the piezoelectric element members 70 and 70 described in the first embodiment.

  And the photosensitive polyimide precursor used as the thermal storage layer (low heat conductive layer) 51 is apply | coated to the surface which joins the piezoelectric element members 70 and 70 of the base member 13 by thickness 5 micrometers. Thereafter, prebaking is performed at 100 ° C./1 minute, and the polyimide at the joint portion between the piezoelectric element member 70 and the base member 13 is removed by a photolithography process. Thereby, the polyimide 51 is formed only on the bottom surface of the recess 57. Further, the piezoelectric element member 70 is directly joined to the base member 13, so that the piezoelectric element member 70 is not displaced and can be positioned with high accuracy.

  Then, the patterned polyimide is baked at a high temperature of 300 ° C. for 5 hours, and a polyimide film is formed as the low thermal conductive layer 51.

  Thereafter, the adhesive 50 is applied to the back surface of the piezoelectric element member 70 or an opening 53 (region where polyimide is not formed) which becomes a bonding surface on the base member 13.

  Then, the piezoelectric element member 70 and the base member 13 are directly bonded with the adhesive 50. When the piezoelectric element member 70 is joined, the adhesive 50 overflows on both sides of the piezoelectric element member 70 by applying a pressing force (for example, about 30 N). The amount of overflow of the adhesive 50 is appropriately adjusted according to the application position of the adhesive 50 and the application amount. The adhesive 50 overflowing between the rows of the piezoelectric element members 70 after the pressurization has the width W1 of the recess 57 equal to or larger than the width W2 between the piezoelectric element rows, Since the edge of the recess 57 appears first, it flows into the bottom surface side of the recess 57 along the wall surface of the recess 57 and is stored. That is, since the adhesive 50 does not reach the edge of the surface of the piezoelectric element member 70 on the common electrode layer 73 side, it can be reliably prevented from creeping up to the common electrode layer 73 of the piezoelectric element member 70.

  Next, a solder paste for forming the conductive layer 52 is supplied between the rows of the piezoelectric element members 70 and 70. As a supply method, it supplies by inject | pouring between rows by dispensing. As a method for heating the solder paste, a semiconductor laser was used, and the beam diameter was reduced to 500 μm and irradiated between the rows of the piezoelectric element members 70 and 70. The semiconductor laser locally heats the solder paste, and the heat supplied to the solder is stored by the low thermal conductive layer (polyimide) 51 on the base. Moreover, the common electrode layer 73 of the piezoelectric element members 70 and 70 is also heated by the irradiated laser, and the solder paste that becomes the conductive layer 52 is in contact with the metal portion of the common electrode layer 73 and is sufficiently melted. A state is obtained.

  The piezoelectric element member 70 and the base member 13 are directly bonded with the adhesive 50, so that the positional deviation of the piezoelectric element members 70 and 70 does not occur even after the solder paste is heated, and the positional accuracy before heating is increased. ± 10 μm or less can be secured.

  In this way, the piezoelectric element member 70 and the base member 13 are directly bonded by the adhesive 50, and heat is used to form an electrical connection for obtaining conduction of the solder paste that becomes the piezoelectric element member 70 and the conductive layer 52. Since the polyimide that is the low thermal conductive layer 51 is difficult to diffuse to the base member 13 side, a sufficient amount of heat is instantaneously stored in the solder paste and the underlying polyimide by spot heating using a laser. While maintaining a high-precision positional relationship between them, a good electrical connection can be formed between the common electrode layer 73 of the piezoelectric element members 70 and 70 and the solder paste as the conductive layer 51, and the resistance of the common electrode can be reduced. Is possible.

  Then, after the common electrode layers 73 and 73 of the piezoelectric element members 70 and 70 are metal-bonded to the conductive layer 52, the piezoelectric element member 70 is grooved to form the drive piezoelectric element columns 12A and 12B. The individual electrode layer 72 is made into the piezoelectric element member 12 divided into the individual electrodes 23, and then the piezoelectric actuator 100 is joined by bonding the electrodes 41 and 42 of the FPC 15 to the individual electrode 23 and the common electrode portion 25 of the piezoelectric element member 12. can get.

  The other points are the same as described in the manufacturing process of the piezoelectric actuator of the first embodiment.

  In this way, by forming the recess in the base member and forming the low thermal conductive layer on the bottom surface of the recess, it is possible to prevent the adhesive from creeping up to the surface on the common electrode side when bonding the adhesive. Further, by preventing the adhesive from creeping up to the common electrode layer, when a conductive layer such as a solder paste is formed, electrical connection by melting the metal between the conductive layer and the common electrode layer is ensured.

  In this case, by making the width of the recesses in the base member larger than the width between the rows of the piezoelectric element members, the protrusion of the bonding adhesive of the piezoelectric element members is reliably stored in the recesses, and the adhesive to the common electrode surface can be stored. Crawling can be prevented.

Next, a ninth embodiment of the piezoelectric actuator according to the present invention will be described with reference to FIG.
In the present embodiment, in the eighth embodiment, the polyimide film formed on the bonding surface of the base member 13 to the piezoelectric element member 12 is left as the low heat conductive layer 51 without forming an opening.

  Even if comprised in this way, the effect similar to the said 8th Embodiment can be acquired, and the patterning of a polyimide film becomes unnecessary.

Next, a tenth embodiment of a piezoelectric actuator according to the present invention will be described with reference to FIG.
In the present embodiment, in the eighth embodiment, a metal layer 55 different from the conductive layer 52 is formed on the bonding surface of the base member 13 with the piezoelectric element member 12 and the surface of the low thermal conductive layer 51 in the recess 57. . The metal layer 52 need not be formed on the entire surface of the base member 13, but may be formed on at least the low thermal conductive layer (polyimide film) 51. In this embodiment, 5 μm of Au is formed by sputtering.

  As described above, by forming a metal layer different from the conductive layer between the low thermal conductive layer and the conductive layer, it becomes easier to form an alloy with the conductive layer, and it is possible to reduce electrical connection failure, The resistance of the common electrode can be reduced. By using an inert material such as Au as the metal layer, the effect of preventing surface oxidation can also be obtained.

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. 23 is a schematic configuration diagram for explaining the overall configuration of the mechanism unit of the apparatus, and FIG. 24 is a plan view of a main part of the mechanism unit.
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 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 four-color droplet is ejected with a two-head configuration, but a liquid ejection head for each color may be provided (the configuration described with reference to FIGS. 13 and 26).

  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.

  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 247 and pressed against the conveying belt 251 by the leading end pressure 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.

  Thus, since the image forming apparatus includes the liquid discharge head according to the present invention as a recording head, stable droplet discharge characteristics can be obtained, and a high-quality image can be stably 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. 25 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 202 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.

  In addition, a maintenance / recovery mechanism 412k, 412c, 412m, 412y (referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) is provided to maintain and recover the performance of the head corresponding to each recording head 411. 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 transport belt 433 moves in the direction indicated by the arrow and is charged by coming into contact with the charging roller 434 to which a high potential applied voltage is applied. In this case, the charging belt 433 is charged at a predetermined charging pitch by switching the polarity of the charging voltage of the charging roller 434 at predetermined time intervals.

  Here, when the sheet 403 is fed onto the conveying belt 433 charged to this high potential, the inside of the sheet 403 is in a polarized state, and the electric charge having the opposite polarity to the electric charge on the conveying belt 433 is conveyed. The charge on the transport belt 433 and the charge on the transported paper 403 are electrostatically attracted to each other, and the paper 403 is electrostatically attracted to the transport belt 433. Is done. 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, stable droplet discharge characteristics can be obtained, and a high-quality image can be stably formed.

  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.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Vibration board member 3 Nozzle plate 4 Nozzle 6 Individual liquid chamber 10 Common liquid chamber 12 Piezoelectric element member 12A, 12B Piezoelectric element column 12Ba Piezoelectric element column 13 Base member 15 FPC (wiring member)
23 Individual Electrode 24 Common Electrode 41 Individual Wiring Electrode 42 Common Wiring Electrode 50 Adhesive 51 Low Thermal Conductive Layer 52 Conductive Layer 55 Metal Layer 61 Metal Layer (Conductive Layer)
62 Metal layer 63 Metal layer 66 Polyimide sheet 234 Carriage 235 Print head 411 k, 411 c, 411 m, 411 y Print head (liquid ejection head)

Claims (13)

A plurality of piezoelectric element columns are formed on a plurality of piezoelectric element members disposed on the base member,
A wiring member is joined to the piezoelectric element column,
On the base member, a low thermal conductive layer and a conductive layer having a thermal conductivity lower than that of the base member are laminated at least in a region other than a joint portion with the piezoelectric element member,
The piezoelectric actuator is characterized in that a part of the conductive layer is melted or joined to a common electrode of the piezoelectric element column via a molten metal.   The piezoelectric actuator according to claim 1, wherein the conductive layer on the base member is not formed at a joint portion between the base member and the piezoelectric element member.   3. The piezoelectric actuator according to claim 1, wherein the low thermal conductive layer on the base member is not formed at a joint portion between the base member and the piezoelectric element member. 4.   The piezoelectric actuator according to any one of claims 1 to 3, wherein the base member is formed of a conductive member, and the conductive layer and the base member are electrically connected.   5. The piezoelectric actuator according to claim 1, wherein a metal layer made of a metal material different from that of the conductive layer is formed between the low thermal conductive layer and the conductive layer.   6. The piezoelectric actuator according to claim 4, wherein a conductive layer made of a material different from that of the base member is formed at least partly between the base member and the low thermal conductive layer.   The piezoelectric actuator according to claim 4, wherein the low thermal conductive layer has electrical conductivity.   8. The piezoelectric actuator according to claim 1, wherein the low thermal conductive layer is located at a position lower than a bottom portion of a groove forming the plurality of piezoelectric element columns in the piezoelectric element member. 9. .   The piezoelectric element members are arranged in two rows on the base member, and the distance between the two rows of piezoelectric element members is positioned by being abutted against the low thermal conductive layer. The piezoelectric actuator according to any one of the above.   The base member has at least two rows of the piezoelectric element members, and the base member is formed with a recess lower than the joining surface between the base member and the piezoelectric element member between the rows of the piezoelectric element members. 6. The piezoelectric actuator according to claim 1, wherein the low thermal conductive layer is formed on a bottom surface of the recess.   The piezoelectric actuator according to claim 10, wherein a width of the concave portion is larger than a width between rows of the piezoelectric element members.   A liquid discharge head comprising the piezoelectric actuator according to claim 1.   An image forming apparatus comprising the liquid discharge head according to claim 12.

Images