JP2003305852A - Inkjet head and inkjet printer having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability in electrical connection between a discrete electrode and a power supply member of an actuator unit. <P>SOLUTION: Each discrete electrode 35a on a piezoelectric sheet 41 farthest from a pressure chamber 10 of a piezoelectric sheet for constituting the actuator unit 21 is electrically joined to power supply pads 55a and 55b of an FPC at two points corresponding to the vicinity of its both ends. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for printing by ejecting ink onto a print medium, and an ink jet printer having the ink jet head.

[0002]

2. Description of the Related Art In an ink jet printer, an ink jet head distributes ink supplied from an ink tank into a plurality of pressure chambers and selectively applies pressure to the pressure chambers to eject ink from nozzles. As one means for selectively applying pressure to the pressure chamber,
An actuator unit in which a plurality of ceramic piezoelectric sheets are stacked may be used.

As an example of such an ink jet head, a plurality of continuous flat plate-like piezoelectric sheets are laminated over a plurality of pressure chambers, and at least one of the piezoelectric sheets is common to many pressure chambers and has a ground potential. There is known one having one actuator unit sandwiched by a held common electrode and a large number of individual electrodes, that is, drive electrodes arranged at positions corresponding to the respective pressure chambers (see Patent Document 1). The portion of the piezoelectric sheet sandwiched between the individual electrode and the common electrode and polarized in the stacking direction is used as an active layer in the stacking direction by the so-called piezoelectric vertical effect when the individual electrodes on both sides are set to a potential different from that of the common electrode. Expand and contract. As a result, the volume inside the pressure chamber fluctuates, and ink can be ejected toward the print medium from the nozzle that communicates with the pressure chamber.

[0004]

[Patent Document 1] Japanese Unexamined Patent Publication No. 4-341852

[0005]

In such an ink jet head, the individual electrode and the power supply member for supplying a drive signal to the individual electrode must be connected directly or indirectly via another member. Improving the reliability of such connection is very important for preventing failure of the inkjet head and the inkjet printer including the inkjet head.

A main object of the present invention is to provide an ink jet head and an ink jet printer including the same which can improve the reliability of the electrical connection between the individual electrodes of the actuator unit and the power feeding member.

[0007]

According to a first aspect of the present invention, there is provided a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source. Are provided adjacent to each other, an actuator unit fixed to one surface of the flow channel unit for changing the volume of the pressure chamber, and a power supply terminal for supplying a drive signal to the actuator unit. And a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other. At least the piezoelectric sheet farthest from the pressure chamber is sandwiched by the common electrode and at least one individual electrode, and the pressure chamber is The individual electrodes on the surface of the piezoelectric sheet farthest away from the surface on the side opposite to the pressure chamber side are electrically joined to the power supply terminal at each of the plurality of electrical contacts on the individual electrode. An inkjet head including a plurality of piezoelectric sheets, and an inkjet printer having such an inkjet head are provided (claim 1).

According to a second aspect of the present invention, a plurality of pressure chambers each having one end connected to a nozzle and the other end connected to an ink supply source are provided, and the plurality of pressure chambers are arranged adjacent to each other along a plane. A flow path unit, an actuator unit fixed to one surface of the flow path unit for changing the volume of the pressure chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. The actuator unit is provided with a common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the pressure chambers, and a plurality of piezoelectric sheets laminated with each other, A plurality of at least one piezoelectric sheet other than the piezoelectric sheet farthest from the chamber is sandwiched by the common electrode and at least one individual electrode; An electric sheet, and a plurality of surface electrodes arranged at positions corresponding to the individual electrodes on the surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber, each surface electrode Is electrically connected to the power supply terminal at each of a plurality of electric contacts connected to the corresponding individual electrode via a conductive material provided in a through hole penetrating one or more of the piezoelectric sheets and on a surface electrode. An inkjet head is provided that includes a plurality of surface electrodes that are joined together (claim 5).

According to this, the individual electrode and the power supply terminal provided on the power supply member are connected directly or indirectly via the surface electrode, and the individual electrode or the surface electrode and the power supply member are connected at a plurality of electrical contacts. Since they are electrically bonded, even if some of the electrical contacts in them are not electrically bonded to the individual electrode or surface electrode and the power supply member, or some of the electrical contacts are electrically bonded. Even if is released, the electrical connection between the two is secured. Therefore, the reliability of the electrical connection between the individual electrode and the power supply member is improved, and the inkjet head and the inkjet printer including the inkjet head are less likely to malfunction.

Further, an individual electrode or a surface electrode is arranged at a position corresponding to each pressure chamber on a surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber. Since the power supply terminal provided on the power supply member is electrically joined, a conductive member for electrically connecting the individual electrode or the surface electrode and the power supply member is provided along the piezoelectric sheet to the end thereof. There is no need to form it separately. Since such a separate conductive member is formed avoiding the individual electrodes or the surface electrodes on the uppermost piezoelectric sheet, it is necessary to ensure a sufficient space between the individual electrodes or the surface electrodes when attempting to ensure sufficient electrical insulation. Therefore, it is necessary to secure the pressure chambers, and as a result, the arrangement density of the pressure chambers is reduced. Further, such a separate conductive member may hinder the deformation of the piezoelectric sheets in the stacking direction. According to the present invention, it is possible to electrically connect the individual electrode or the surface electrode and the power feeding member without providing a separate conductive member as described above, so that the arrangement density of the pressure chambers can be improved, and The amount of deformation of the piezoelectric sheets in the stacking direction can be increased.

In the present invention, the electric contacts may be provided at two locations corresponding to the vicinity of both ends of the pressure chamber (claim 2). In this case, the reliability of the electrical connection between the surface electrode or the individual electrode and the power supply terminal is improved as compared with the case where the electrical contacts are arranged close to each other, and the failure is less likely to occur.

Further, in the present invention, the electrical contact is
It is preferably provided outside the region corresponding to the pressure chamber (claim 3). In this case, the deformation of the portion of the individual electrode in the region corresponding to the pressure chamber in the stacking direction of the actuator unit is hardly obstructed by the electrical contact. Therefore, the portion of the individual electrode in the region corresponding to the pressure chamber can be largely displaced in the stacking direction of the actuator units while resisting the internal pressure generated in the pressure chamber. Therefore, the volume change amount of the pressure chamber becomes large, and it is possible to eject a sufficient amount of ink even if the pressure chamber is made smaller to achieve higher integration.

According to a third aspect of the present invention, a plurality of pressure chambers each having one end connected to a nozzle and the other end connected to an ink supply source are provided, and the plurality of pressure chambers are arranged adjacent to each other along a plane. A flow path unit, an actuator unit fixed to one surface of the flow path unit for changing the volume of the pressure chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. The actuator unit comprises a common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, at least the The piezoelectric sheet farthest from the pressure chamber is sandwiched by the common electrode and at least one individual electrode, and the farthest from the pressure chamber. A plurality of piezoelectric sheets in which each individual electrode on the surface of the piezoelectric sheet opposite to the surface on the pressure chamber side is electrically joined to the power supply terminal, and the piezoelectric sheet farthest from the pressure chamber. A plurality of peripheral electrodes arranged around a region where the plurality of individual electrodes are present on a surface opposite to the surface on the pressure chamber side, which is electrically connected to the common electrode and the power supply terminal. An inkjet head including at least one peripheral electrode electrically connected to the inkjet head, and an inkjet printer having such an inkjet head are provided.

According to a fourth aspect of the present invention, a plurality of pressure chambers each having one end connected to a nozzle and the other end connected to an ink supply source are provided, and the plurality of pressure chambers are arranged adjacent to each other along a plane. A flow path unit, an actuator unit fixed to one surface of the flow path unit for changing the volume of the pressure chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. The actuator unit is provided with a common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the pressure chambers, and a plurality of piezoelectric sheets laminated with each other, A plurality of at least one piezoelectric sheet other than the piezoelectric sheet farthest from the chamber is sandwiched by the common electrode and at least one individual electrode; An electric sheet, and a plurality of surface electrodes arranged at positions corresponding to the individual electrodes on the surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber, each surface electrode Is connected to the corresponding individual electrode via a conductive material provided in a through hole penetrating one or more of the piezoelectric sheets and is electrically joined to the power supply terminal; A plurality of peripheral electrodes arranged around a region in which the plurality of surface electrodes are present on a surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber, the common electrode and An inkjet head is provided that includes at least one peripheral electrode that is electrically connected and electrically connected to the power supply terminal (claim 10).

According to this, at least one of the plurality of peripheral electrodes arranged around the area where the individual electrode or the surface electrode is present on the surface of the piezoelectric sheet farthest from the pressure chamber on the side opposite to the surface on the pressure chamber side. When the external force is applied to the power supply member to peel it off, the electrical connection between the power supply member and the surrounding electrode is first released. After that, the electrical connection between the individual electrode or the surface electrode and the power supply terminal is released. Therefore, unless a relatively large force is applied, the electrical connection between the individual electrode or the surface electrode and the power supply terminal is not released, the reliability of the electrical connection between them is improved, and an inkjet head and an inkjet having the same are provided. Printer failure is less likely to occur.

Further, since the at least one peripheral electrode is electrically connected to the common electrode and electrically connected to the power supply terminal, the common electrode is kept at a constant potential without using a separate member other than the power supply member. Can be kept. That is, the power supply member can be used both to supply the drive signal to the individual electrodes and to keep the common electrode at a constant potential, so that the structure of the inkjet head can be simplified.

Further, an individual electrode or a surface electrode is arranged at a position corresponding to each pressure chamber on the surface of the piezoelectric sheet farthest from the pressure chamber on the side opposite to the surface on the pressure chamber side. Since the power supply terminal provided on the power supply member is electrically joined, it is not necessary to separately form a conductive member for electrically connecting the individual electrode or the surface electrode and the power supply member on the piezoelectric sheet. . Therefore, the arrangement density of the pressure chambers can be improved, and moreover, the deformation amount of the piezoelectric sheets in the stacking direction can be increased.

In the present invention, the region may be substantially surrounded by a plurality of the peripheral electrodes (claim 7). In this case, the reliability of the electrical connection between the surface electrode or the individual electrode and the power supply pad is improved regardless of the direction of the force for peeling off the power supply member.

Further, in the present invention, it is preferable that two or more of the peripheral electrodes are electrically connected to the common electrode and electrically connected to the power supply terminal (claim 8). As a result, the potential of the common electrode is more reliably maintained at a constant potential, so that the inkjet head and the inkjet printer having the inkjet head are less likely to malfunction.

According to a fifth aspect of the present invention, a plurality of pressure chambers each having one end connected to a nozzle and the other end connected to an ink supply source are included, and the plurality of pressure chambers are arranged adjacent to each other along a plane. A flow path unit, an actuator unit fixed to one surface of the flow path unit for changing the volume of the pressure chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. The actuator unit comprises a common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, at least the The piezoelectric sheet farthest from the pressure chamber is sandwiched by the common electrode and at least one individual electrode, and the farthest from the pressure chamber. A plurality of piezoelectric elements in which each individual electrode on the surface of the piezoelectric sheet opposite to the surface on the pressure chamber side is electrically joined to the power supply terminal at each of two electrical contacts on the individual electrode. A sheet, wherein the individual electrode is provided with a first electrode region having a planar shape similar to the pressure chamber, and one of the electrical contacts connected to one end of the first electrode region. A second electrode region and a third electrode region provided with one of the electrical contacts, the third electrode region being connected to the other end of the first electrode region so as to face the second electrode region. And the first
With respect to a direction in which a connecting portion between the second electrode region and the second electrode region is substantially orthogonal to a direction connecting the second electrode region and the third electrode region. The second electrode region has a length shorter than that of the second electrode region, and the connecting portion between the first electrode region and the third electrode region connects the second electrode region and the third electrode region. An inkjet head is provided that has a length that is shorter than the first electrode region and the third electrode region in a direction substantially orthogonal to the connecting direction (claim 11).

According to this, in addition to improving the reliability of the electrical connection between the individual electrode of the actuator unit and the power supply member as in the above-described invention, the first electrode region and the second electrode region are connected. Since the range of the active layer corresponding to the connecting part and the connecting part of the first electrode region and the third electrode region is reduced, the distance between the active layers corresponding to the adjacent pressure chambers is increased. , It is possible to suppress the occurrence of crosstalk between the adjacent pressure chambers.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of an ink jet printer including an ink jet head according to a first embodiment of the present invention. Inkjet printer 10 shown in FIG.
1 is a color inkjet printer having four inkjet heads 1. In this printer 101, a paper feed unit 111 is provided on the left side of the drawing, and a paper discharge unit 11 is provided on the right side of the drawing.
2 are configured respectively.

Inside the printer 101, a paper conveyance path is formed which flows from the paper feed section 111 toward the paper discharge section 112. Immediately downstream of the paper feeding unit 111, a pair of feed rollers 105a that nips and conveys a sheet that is an image recording medium,
105b is arranged. Pair of feed rollers 105
The sheet is sent from left to right in the figure by a and 105b. Two belt rollers 1 are provided in the middle of the paper transport path.
06 and 107, and an endless conveyor belt 108 that is wound so as to be stretched between both rollers 106 and 107 are arranged. The outer peripheral surface of the conveyor belt 108, that is, the conveyor surface is treated with silicone, and while holding the paper conveyed by the pair of feed rollers 105a and 105b on the conveyor surface of the conveyor belt 108 by its adhesive force, The belt roller 106 is driven to rotate clockwise (in the direction of arrow 104) in the figure so that it can be conveyed toward the downstream side (right side).

Pressing members 109a and 109b are arranged at the insertion and ejection positions of the paper with respect to the belt roller 106, respectively. Holding members 109a, 109b
Is for pressing the paper onto the carrying surface of the carrying belt 108 so that the paper on the carrying belt 108 does not float from the carrying surface, and to firmly adhere the paper to the carrying surface.

A peeling mechanism 110 is provided immediately downstream of the transport belt 108 along the paper transport path. The peeling mechanism 110 peels the sheet adhered to the conveyance surface of the conveyance belt 108 from the conveyance surface, and the right sheet ejection unit 112.
It is configured to be sent to.

The four ink jet heads 1 have head bodies 1a at their lower ends. The head body 1a is
Each of them has a rectangular cross section, and they are arranged close to each other so that the longitudinal direction thereof is a direction perpendicular to the paper conveyance direction (direction perpendicular to the paper surface of FIG. 1). That is, the printer 101 is a line printer. The bottom surfaces of the four head main bodies 1a face the paper transport path, and the bottom surfaces are provided with nozzles having a large number of ink ejection openings each having a minute diameter. Magenta, yellow, cyan, and black inks are ejected from each of the four head bodies 1a.

The head body 1a is arranged so that a small gap is formed between the lower surface of the head body 1a and the conveying surface of the conveying belt 108, and a sheet conveying path is formed in this gap portion. With this configuration, when the paper conveyed on the conveyor belt 108 sequentially passes immediately below the four head main bodies 1a, ink of each color is ejected from the nozzles toward the upper surface of the paper, that is, the printing surface. A desired color image can be formed on a sheet.

The ink jet printer 101 has a maintenance unit 117 for automatically performing maintenance on the ink jet head 1. The maintenance unit 117 includes four head bodies 1
Four caps 116 for covering the lower surface of a and a purging mechanism not shown are provided.

The maintenance unit 117 is used when the ink jet printer 101 is printing.
It is located at a position (retracted position) immediately below the paper feeding unit 111. Then, when a predetermined condition is satisfied after the printing is completed (for example, when the printing operation is not performed for a predetermined time, or when the power of the printer 101 is turned off), the four head main bodies are used. 1a is moved to a position immediately below, and at this position (cap position), the cap 116 covers the lower surface of the head body 1a,
The ink of the nozzle portion of the head body 1a is prevented from drying.

The belt rollers 106 and 107 and the conveyor belt 108 are supported by the chassis 113. The chassis 113 has a cylindrical member 115 arranged below it.
It is placed on top. The cylindrical member 115 is rotatable about a shaft 114 attached at a position deviated from the center thereof. Therefore, when the height of the upper end of the cylindrical member 115 changes with the rotation of the shaft 114, the chassis 113 moves up and down accordingly. Maintenance unit 1
When moving 17 from the retracted position to the cap position,
The cylindrical member 115 is rotated in advance by an appropriate angle to make the chassis 1
13, transport belt 108 and belt rollers 106, 10
It is necessary to lower 7 from the position shown in FIG. 1 by an appropriate distance to secure a space for moving the maintenance unit 117.

In a region surrounded by the conveyor belt 108, a substantially rectangular parallelepiped shape (conveyance) which supports the inkjet head 1 from the inner peripheral side by contacting the lower surface of the conveyor belt 108 located at a position facing the ink jet head 1 The guide 121 having the same width as the belt 108)
Are arranged.

Next, the structure of the ink jet head 1 according to this embodiment will be described in more detail. Figure 2
FIG. 3 is a perspective view of the inkjet head 1. Figure 3
FIG. 3 is a sectional view taken along line III-III in FIG. 2. 2 and 3
As shown in FIG. 1, the inkjet head 1 according to the present embodiment has a head main body 1a having a rectangular planar shape extending in one direction (main scanning direction) and a base 131 for supporting the head main body 1a. ing. The base 131 includes the individual electrodes 35a and 35b (see FIG. 9) in addition to the head body 1a.
Driver IC1 for supplying a drive signal to (see (a))
32 and the substrate 133 are supported.

As shown in FIG. 2, the base 131 is partially adhered to the upper surface of the head main body 1a to support the head main body 1a, and is adhered to the upper surface of the base block 138. Base block 13
8 and a holder 139 for holding 8. The base block 138 is a substantially rectangular parallelepiped member having a length substantially the same as the length of the head body 1a in the lengthwise direction. Base block 138 made of metallic material such as stainless steel
Has a function as a lightweight structure that reinforces the holder 139. The holder 139 includes a holder main body 141 arranged on the head main body 1a side, and a pair of holder support portions 142 extending from the holder main body 141 to the side opposite to the head main body 1a. A pair of holder support parts 14
2 is a plate-shaped member, and is a holder body 14
They are provided in parallel with each other at a predetermined interval along the lengthwise direction of 1.

A pair of skirts 141a projecting downward are provided at both ends of the holder body 141 in the sub-scanning direction (direction orthogonal to the main scanning direction). Here, since the pair of skirts 141a are formed over the entire width in the longitudinal direction of the holder body 141, the pair of skirts 141a form a substantially rectangular parallelepiped groove 141b on the lower surface of the holder body 141. ing. The base block 138 is housed in the groove 141b. The upper surface of the base block 138 and the holder body 141
The bottom surface of the groove portion 141b is bonded with an adhesive. The thickness of the base block 138 is the holder body 14
Since it is slightly larger than the depth of the first groove portion 141b, the lower end portion of the base block 138 protrudes below the skirt portion 141a.

Inside the base block 138, an ink reservoir 3 which is a substantially rectangular parallelepiped void (hollow region) extending in the lengthwise direction is formed as a flow path of ink supplied to the head main body 1a. There is. Base block 138
On the lower surface 145 of the opening 3 b communicating with the ink reservoir 3.
(See FIG. 4) are formed. Ink pool 3
Is connected to a main ink tank (ink supply source) (not shown) in the printer body by a supply tube (not shown). Therefore, the ink reservoir 3 is appropriately replenished with ink from the main ink tank.

The lower surface 145 of the base block 138 projects below the periphery in the vicinity of the opening 3b. The base block 138 is in contact with the flow path unit 4 (see FIG. 3) of the head body 1a only in the portion 145a of the lower surface 145 near the opening 3b. Therefore, the region of the lower surface 145 of the base block 138 other than the portion 145a near the opening 3b is separated from the head body 1a, and the actuator unit 21 is arranged in this separated portion.

A driver IC 132 is fixed to the outer surface of the holder support portion 142 of the holder 139 via an elastic member 137 such as sponge. A heat sink 134 is closely arranged on the outer surface of the driver IC 132. The heat sink 134 is a member having a substantially rectangular parallelepiped shape and efficiently dissipates heat generated by the driver IC 132. The driver IC 132 includes a flexible printed wiring board (FPC: Flexible Printed Circuit) which is a power feeding member.
cuit) 136 is connected. The FPC 136 connected to the driver IC 132 is electrically joined to the substrate 133 and the head body 1a by soldering. A substrate 133 is arranged above the driver IC 132 and the heat sink 134 and outside the FPC 136. Between the upper surface of the heat sink 134 and the substrate 133, and between the lower surface of the heat sink 134 and the FPC 136.
And a seal member 149 are bonded to each other.

The FPC 136 is provided between the lower surface of the skirt portion 141a of the holder body 141 and the upper surface of the flow path unit 4.
The seal member 150 is arranged so as to sandwich the. That is, the FPC 136 includes the flow path unit 4 and the holder body 1.
It is fixed to 41 by a seal member 150. This prevents the head body 1a from bending when the head body 1a is elongated, and the actuator unit 21 and the FPC 136 are prevented.
It is possible to prevent stress from being applied to the connection portion with and to securely hold the FPC 136.

As shown in FIG. 2, in the vicinity of the lower corner of the inkjet head 1 in the main scanning direction, six convex portions 30a are evenly spaced along the side wall of the inkjet head 1. These protruding portions 30a are portions provided at both ends in the sub-scanning direction of the nozzle plate 30 (see FIG. 7) in the lowermost layer of the head body 1a. That is, the nozzle plate 30 is bent about 90 degrees along the boundary line between the protruding portion 30a and other portions.
The protruding portions 30a are provided at positions corresponding to the vicinity of both ends of sheets of various sizes used for printing in the printer 101. Since the bent portion of the nozzle plate 30 has a rounded shape rather than a right angle, the jam of the sheet that is caused when the leading edge of the sheet conveyed in the direction close to the head 1 comes into contact with the side surface of the head 1. That is, jamming is less likely to occur.

FIG. 4 is a schematic plan view of the head body 1a. In FIG. 4, the ink reservoir 3 formed in the base block 138 is virtually depicted by a broken line.
As shown in FIG. 4, the head body 1a has a rectangular planar shape extending in one direction (main scanning direction). The head main body 1a has a number of pressure chambers 10 to be described later and a flow path unit 4 in which an ink ejection port 8 at the tip of a nozzle (see also FIGS. 5, 6, and 7) is formed, and the upper surface thereof is provided. A plurality of trapezoidal actuator units 21 arranged in two rows in a zigzag pattern are bonded. Each actuator unit 21 is arranged such that its parallel facing sides (upper side and lower side) are along the longitudinal direction of the flow path unit 4. The hypotenuses of the adjacent actuator units 21 overlap each other in the width direction of the flow path unit 4.

The lower surface of the flow path unit 4 corresponding to the adhesion area of the actuator unit 21 is an ink ejection area. As will be described later, a large number of ink ejection openings 8 are arranged in a matrix on the surface of the ink ejection area. Further, in the base block 138 arranged above the flow path unit 4, the ink reservoir 3 is formed along the longitudinal direction thereof. The ink reservoir 3 communicates with an ink tank (not shown) through an opening 3a provided at one end thereof and is always filled with ink. The ink reservoir 3 has two openings 3b along its extending direction.
They are paired one by one, and are provided in a zigzag pattern in a region where the actuator units 21 are not provided.

FIG. 5 is an enlarged view of the area surrounded by the alternate long and short dash line drawn in FIG. As shown in FIGS. 4 and 5,
The ink reservoir 3 communicates with the manifold 5 in the flow channel unit 4 located below the ink reservoir 3 through the opening 3b. The opening 3b is provided with a filter (not shown) for capturing dust and the like contained in the ink. The front end of the manifold 5 is branched into two to form a sub-manifold 5a. One actuator unit 21
Two sub-manifolds 5a enter into the lower part of the actuator unit 21 from two openings 3b located on both sides of the inkjet head 1 in the longitudinal direction. That is, one actuator unit 2
A total of four sub-manifolds 5 a extend along the longitudinal direction of the inkjet head 1 in the lower part of the nozzle 1.
Each sub-manifold 5a is filled with the ink supplied from the ink reservoir 3.

FIG. 6 is an enlarged view of the area surrounded by the alternate long and short dash line drawn in FIG. As shown in FIGS. 5 and 6,
On the upper surface of the actuator unit 21, individual electrodes 35a having a substantially rhombic plan shape are regularly arranged in a matrix, and at positions inside the actuator unit 21 that vertically overlap with the individual electrodes 35a. An individual electrode 35b having the same shape as the individual electrode 35a is arranged. In addition, a large number of ink ejection openings 8 are regularly arranged in a matrix on the surface of the ink ejection area corresponding to the actuator unit 21 of the flow path unit 4. Inside the flow path unit 4, substantially rhombic pressure chambers (cavities) 10 each having a planar shape slightly larger than the individual electrodes 35a and 35b and communicating with each ink ejection port 8 and apertures 12 are arranged in a matrix. It is regularly arranged. The pressure chamber 10 is formed at a position corresponding to the individual electrodes 35a and 35b, and most of the individual electrodes 35a and 35b are included in the region of the pressure chamber 10 in a plan view. 5 and 6, in order to make the drawings easy to understand, the pressure chamber 10 and the aperture 12 and the like in the actuator unit 21 or the flow path unit 4 which should be drawn by broken lines are drawn by solid lines. Further, in FIG. 6, for the sake of convenience, the power supply pad 55 provided on the FPC 136 side attached to the upper surface of the actuator unit 21.
a, 55b, 55c are drawn.

As shown in FIGS. 5 and 6, a large number of grounding electrodes 38 each having a circular shape are formed as peripheral electrodes near the outer edge of the upper surface of the actuator unit 21. The large number of grounding electrodes 38 are separated so that the adjacent electrodes are substantially evenly spaced. Therefore, the individual electrode 35 on the upper surface of the actuator unit 21 is
The region where a is formed is surrounded by a large number of grounding electrodes 38 over the entire circumference.

FIG. 7 is a partial cross-sectional view of the head body shown in FIG. 4 and the flexible printed wiring board attached to the head body along the longitudinal direction of the pressure chamber. As can be seen from FIG. 7, each ink ejection port 8 is formed at the tip of a tapered nozzle. Each ink ejection port 8 has a pressure chamber 10.
(Length 900 μm, width 350 μm) and aperture 12
Through the sub-manifold 5a. In this way, the ink jet head 1 includes the ink reservoir 3, the manifold 5, and the sub-manifold 5 in the ink jet head 1.
An ink flow path 32 is formed to reach the ink ejection port 8 through the a, the aperture 12, and the pressure chamber 10.

As is clear from FIG. 7, the pressure chamber 1
0 and the aperture 12 are provided at different heights.
As a result, as shown in FIG. 6, in the flow path unit 4 corresponding to the ink ejection region below the actuator unit 21, the aperture 12 communicating with one pressure chamber 10 is connected to the pressure chamber adjacent to the pressure chamber 10. It can be arranged at the same position as 10 in a plan view. As a result, since the pressure chambers 10 are in close contact with each other and are arranged at high density, high-resolution image printing is realized by the inkjet head 1 having a relatively small occupied area.

The pressure chambers 10 are arranged in the planes shown in FIGS. 5 and 6 in the longitudinal direction (first array direction) of the inkjet head 1 and in a direction slightly inclined from the width direction of the inkjet head 1 (second array). Direction) in the ink ejection area. The first arrangement direction and the second arrangement direction form an angle θ slightly smaller than a right angle. The ink ejection openings 8 are arranged at 50 dpi in the first arrangement direction. On the other hand, 12 pressure chambers 10 are arranged in the second arrangement direction so that 12 pressure chambers are included in the ink ejection region corresponding to one actuator unit 21. As a result, twelve ink ejection openings 8 are present in the entire width of the inkjet head 1 in a range separated by the distance between two ink ejection openings 8 adjacent in the first arrangement direction. It should be noted that at both ends (corresponding to the hypotenuse of the actuator unit 21) of each ink ejection area in the first arrangement direction, a complementary relationship with an ink ejection area corresponding to another actuator unit 21 facing in the width direction of the inkjet head 1 is provided. Therefore, the above condition is satisfied. Therefore, in the ink jet head 1 according to the present embodiment, ink is sequentially ejected from a large number of ink ejection openings 8 arranged in the first and second arrangement directions as the ink jet head 1 moves in the width direction relative to the paper. By ejecting droplets, printing can be performed at 600 dpi in the main scanning direction.

FIG. 8 is a partially exploded perspective view of the head main body depicted in FIG. 4 and the FPC 136 attached to the head main body. As shown in FIGS. 7 and 8, the main part on the bottom side of the inkjet head 1 is, from above, the FPC 136, the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, the manifold plates 26, 27. , 28, the cover plate 29, and the nozzle plate 30 have a laminated structure in which a total of 11 sheet materials are laminated. Of these, the FPC 136 and the actuator unit 21
The flow path unit 4 is composed of nine plates excluding.

As will be described later in detail, the actuator unit 21 is a layer in which five piezoelectric sheets are laminated and electrodes are arranged so that three of the layers have a portion which becomes an active layer when an electric field is applied ( Hereinafter, it will be simply referred to as "a layer having an active layer"), and the remaining two layers are inactive layers. The cavity plate 22 is a metal plate provided with a large number of substantially rhombic openings corresponding to the pressure chambers 10. The base plate 23 is configured such that one pressure chamber 10 of the cavity plate 22 is different from the pressure chamber 10
And the aperture 12 and a communication hole from the pressure chamber 10 to the ink ejection port 8 are provided. The aperture plate 24 is a metal plate in which, for each pressure chamber 10 of the cavity plate 22, a communication hole from the pressure chamber 10 to the ink ejection port 8 is provided in addition to the aperture 12. The supply plate 25 is a metal plate in which a communication hole between the aperture 12 and the sub-manifold 5a and a communication hole from the pressure chamber 10 to the ink ejection port 8 are provided for each pressure chamber 10 of the cavity plate 22. The manifold plates 26, 27, and 28 are metal plates in which, in addition to the sub-manifold 5a, a communication hole from the pressure chamber 10 to the ink ejection port 8 is provided for each pressure chamber 10 of the cavity plate 22. Cover plate 29
Is a metal plate in which a communication hole from the pressure chamber 10 to the ink ejection port 8 is provided for each pressure chamber 10 of the cavity plate 22. Nozzle plate 30
Is a metal plate provided with a tapered ink ejection port 8 functioning as a nozzle for each pressure chamber 10 of the cavity plate 22.

These ten plates 21 to 30 are aligned with each other and stacked so that the ink flow path 32 as shown in FIG. 7 is formed. This ink flow path 32
First extends upward from the sub-manifold 5a, extends horizontally in the aperture 12, then further upwards, extends again horizontally in the pressure chamber 10, and then obliquely downward in the direction away from the aperture 12. Vertically downwards toward the ink ejection port 8.

Next, the structure of the actuator unit 21 and the connection between the actuator unit 21 and the FPC 136 will be described. FIG. 9 (a) shows F along the line IXA-IXA drawn in FIG.
FIG. 8 is a cross-sectional view of the actuator unit to which the PC 136 is attached, which is an enlarged view of a region surrounded by an alternate long and short dash line depicted in FIG. 7. FIG. 9B shows the IXB depicted in FIG.
FIG. 9 is a cross-sectional view of the actuator unit to which the FPC 136 is attached, taken along line IXB. FIG. 10A shows
FIG. 10 is an enlarged view in a circular frame drawn by the alternate long and short dash line in FIG.
FIG. 10B is an enlarged view of the inside of a circular frame drawn by the alternate long and short dash line of FIG. 9B.

As shown in FIGS. 9 (a) and 9 (b),
Each actuator unit 21 has a thickness of 15 μm.
It includes five piezoelectric sheets 41, 42, 43, 44 and 45 which are formed to be the same at about m. These piezoelectric sheets 41 to 45 are the same as those in the inkjet head 1.
It is a continuous layered flat plate (continuous flat plate layer) so as to be arranged over a large number of pressure chambers 10 formed in one ink ejection region. By arranging the piezoelectric sheets 41 to 45 as a continuous flat plate layer over a large number of pressure chambers 10, it is possible to arrange the individual electrodes 35a and 35b in high density by using, for example, a screen printing technique. There is. Therefore, the pressure chambers 10 formed at the positions corresponding to the individual electrodes 35a and 35b can be arranged at high density, and high-resolution images can be printed. In the present embodiment, the piezoelectric sheets 41 to 45 are
It is made of a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity. 7 and 9 (a), the FPC 136 and the piezoelectric sheet 41 are depicted as being bonded to each other over their entire surfaces, but in reality, both are attached to the main electrode portion 60 of each individual electrode 35a.
Then it is not glued. This is to prevent the FPC 136 attached to the main electrode portion 60 from inhibiting the deformation of the actuator unit 21 with respect to the pressure chamber 10. The same applies to FIG. 12 (a).

The piezoelectric sheet 41 on the uppermost layer of the actuator unit 21 and the piezoelectric sheet 42 adjacent below the piezoelectric sheet 41.
And a common electrode 34a having a thickness of about 2 μm is interposed between and. The common electrode 34a is a single conductive sheet that extends over almost the entire area of one actuator unit 21. Similarly, between the piezoelectric sheet 43 adjacent below the piezoelectric sheet 42 and the piezoelectric sheet 44 adjacent below the piezoelectric sheet 42, the thickness 2 having the same shape as the common electrode 34a is formed.
A common electrode 34b of about μm is interposed.

The common electrodes 34a and 34b may be formed in a larger number for each pressure chamber 10 than the pressure chamber 10 so that the projection region in the stacking direction includes the pressure chamber region. A large number of smaller than the pressure chambers 10 may be formed for each pressure chamber 10 so that the region is included in the pressure chamber region, and it is not always necessary that the conductive sheet is formed on the entire surface of the sheet. However, at this time, it is necessary that the common electrodes are electrically connected so that all the portions corresponding to the pressure chamber 10 have the same potential.

As shown in FIG. 9A, the piezoelectric sheet 41
At the position corresponding to the pressure chamber 10 on the upper surface of the
An individual electrode 35a of about μm is formed. As shown in FIG. 11 which is a schematic partially enlarged plan view of FIG. 6, the individual electrode 35a has a substantially rhombic plan shape and has a pressure chamber 10
2 having a substantially rhombus shape formed continuously from a main electrode portion 60 having a similar shape (length 850 μm, width 250 μm) and an acute angle portion at both ends smaller than the main electrode portion 60.
It has one auxiliary electrode part 61a, 61b. In the main electrode portion 60, the projection area in the stacking direction is included in the pressure chamber area (the area surrounded by the broken line in FIG. 11). On the other hand, in most of the auxiliary electrode portions 61a and 61b, the projection area in the stacking direction is not included in the pressure chamber area.

As is apparent from FIG. 11, the individual electrode 35
In a, the width of the connecting portion 63a between the main electrode portion 60 and the auxiliary electrode portion 61a (the length in the direction orthogonal to the direction connecting the two auxiliary electrode portions 61a and 61b) is the width of the main electrode portion 60 and the auxiliary electrode. It is smaller than the width of the portion 61a.
Similarly, the connecting portion 6 between the main electrode portion 60 and the auxiliary electrode portion 61b
The width of 3b is smaller than the width of the main electrode portion 60 and the width of the auxiliary electrode portion 61b. That is, in the individual electrode 35a, the connecting portions 63a and 63b between the main electrode portion 60 and the auxiliary electrode portions 61a and 61b have a constricted shape.

Since the connecting portions 63a and 63b have the constricted shape as described above, the connecting portions 63a and 63b do not have such a constricted shape and the main electrode portion 60 and the auxiliary electrode portions 61a and 61b are thick. The range of the active layer corresponding to the connecting portions 63a and 63b is smaller than that in the case of connecting by the width. As a result, the distance between the adjacent pressure chambers 10 becomes large, so that the occurrence of crosstalk between the adjacent pressure chambers 10 is suppressed.

At a position between the piezoelectric sheet 42 and the piezoelectric sheet 43 and corresponding to the individual electrode 35a, the individual electrode 3
An individual electrode 3 having a shape similar to that of 5a and having a thickness of about 2 μm
5b is interposed. The individual electrode 35b is also the individual electrode 35a.
Since it also has a constricted shape, the crosstalk suppressing effect can be obtained from this point as well. No electrodes are arranged between the piezoelectric sheet 44 and the piezoelectric sheet 45 adjacent therebelow, and below the piezoelectric sheet 45.

As shown in FIG. 9A, the individual electrode 35a
The through holes 4 are formed in the piezoelectric sheets 41 and 42 between the positions corresponding to the auxiliary electrode portion 61a between the and individual electrodes 35b.
1a and 42a are formed. Through hole 41a,
42a is filled with a conductive material (silver palladium, etc.) 48 as shown in FIG.
The individual electrodes 35 a and the individual electrodes 35 b are connected to each other via 8 for each corresponding to each pressure chamber 10.

As shown in FIG. 9B, the ground electrode 38
Through holes 41b, 42b, 43b penetrating the piezoelectric sheets 41, 42, 43 are formed below the.
The through holes 41b, 42b, and 43b have the same structure as shown in FIG.
As shown in (b), a conductive material (silver palladium, etc.) 49
Are filled, and the ground electrode 38 is connected to the common electrode 34a and the common electrode 34b through the conductive material 49. In the present embodiment, the electrodes 34a, 34
b, 35a, 35b and 38 are made of a metal material such as Ag-Pd.

The FPC 136 includes the individual electrodes 35a and 35b and the common electrodes 34a and 3 of the actuator unit 21.
4b and the driver IC 132 are connected to each other. As shown in FIGS. 9A and 9B, the individual electrode 35a and the ground electrode 38 arranged on the upper surface of the actuator unit 21 are connected to each other. Has a large number of power supply pads 55a, 55b, 55c electrically connected by soldering to the lower surface.

As shown in FIGS. 9 (a) and 9 (b),
The FPC 136 has a base film 51, a cover film 52 attached to the base film 51, and a printed wiring 53 patterned between the films 51 and 52. The printed wiring 53 is the pressure chamber 1.
Each 0 is separately connected to the driver IC 132. The base film 51 and the cover film 52 are both sheet-shaped members having an insulating property. The FPC 136 is
The cover film 52 is arranged so as to contact the upper surface of the piezoelectric sheet 41 that is the uppermost layer of the actuator unit 21.

Through holes 5 are selectively formed in the cover film 52.
2a, 52b, 52c are formed, and the through hole 52
Power supply pads 55 made of a conductive material having substantially the same thickness as the cover film 52 are provided in the a, 52b, and 52c.
a, 55b, 55c are arranged respectively. The power supply pads 55a, 55b, 55c have through holes 52a, 52
The printed wiring 53 is in contact with the bottom of the recess formed by b and 52c.

The power supply pads 55a and 55b are shown in FIG. 9 (a).
As shown in, the pressure chamber 10 is provided slightly outside in the longitudinal direction, that is, at a position corresponding to the auxiliary electrode portions 61a and 61b. The power supply pads 55a and 55b are electrically joined to the auxiliary electrode portions 61a and 61b by soldering. That is, in the present embodiment, one individual electrode 35a is electrically joined to the FPC 136 at two electric contacts (each at a position corresponding to each power supply pad 55a, 55b). in this way,
By electrically connecting the power supply pads 55a and 55b to the auxiliary electrode portions 61a and 61b of the individual electrode 35a,
The potentials of the individual electrodes 35a and 35b can be independently controlled for each pressure chamber 10 via the printed wiring 53 and the conductive material 48 in the through holes 41a and 42a.

On the other hand, the power supply pad 55c is provided at a position corresponding to the ground electrode 38 formed near the outer edge of the actuator unit 21, as shown in FIG. 9B. The power supply pad 55c is electrically joined to the ground electrode 38 by soldering. As a result, the printed wiring 53 and the through holes 41b and 42 are formed.
b, 43b via the conductive material 49 in the common electrode 34a,
The potential of 34b can be maintained at the ground potential.

In the present embodiment, all of the many ground electrodes 38 are electrically joined to the power supply pad 55c by soldering, and the common electrode 34 is provided through the conductive material 49.
a and 34b. However, the ground electrode 38
Does not need to be electrically joined to the power supply pad 55c, and a part of the ground electrode 38 may be the common electrode 34a.
It does not have to be connected to 34b. Because the common electrodes 34a and 34b are formed as one continuous flat plate that extends over all the pressure chambers 10, at least 1
If one ground electrode 38 is electrically connected to the power supply pad 55c and connected to the common electrodes 34a and 34b,
The common electrode 34 is provided in the region corresponding to all the pressure chambers 10.
This is because the potentials of a and 34b can be maintained at the ground potential.

In the ink jet head 1 according to this embodiment, the piezoelectric sheets 41 to 43 are polarized in the thickness direction. Therefore, the individual electrodes 35a and 35b have different potentials from the common electrodes 34a and 34b, and the piezoelectric sheet 41
When an electric field is applied in the direction of polarization to ~ 43, the portion to which the electric field is applied acts as an active layer and expands or contracts in the thickness direction, that is, the stacking direction, and as a result, due to the piezoelectric lateral effect. Attempts to shrink or expand in the direction perpendicular to the stacking direction, that is, in the plane direction. On the other hand, the remaining two piezoelectric sheets 44 and 45 are inactive layers that do not have a region sandwiched between the individual electrodes 35a and 35b and the common electrodes 34a and 34b, and therefore cannot be deformed spontaneously. That is, the actuator unit 21 is placed on the upper side (that is,
The three piezoelectric sheets 41 to 43 apart from the pressure chamber 10 are used as layers in which the active layer exists and are located on the lower side (that is, the pressure chamber 10).
It is a so-called unimorph type structure in which two piezoelectric sheets 44 and 45 (which are close to each other) are used as inactive layers.

Therefore, the driver IC 132 is controlled so that the electric field and the polarization are in the same direction, and the individual electrodes 35a and 3a.
When 5b is a positive or negative predetermined potential, the piezoelectric sheets 41 to
43 individual electrodes 35a, 35b and common electrodes 34a, 34
The active layer sandwiched by b contracts in the surface direction, while the piezoelectric sheets 44 and 45 do not contract spontaneously. At this time, as shown in FIG. 9A, the piezoelectric sheets 41 to 45
The lower surface of the pressure chamber 1 is formed in the cavity plate 22.
Since it is fixed to the upper surface of the partition that divides 0, the piezoelectric sheets 41 to 45 are consequently deformed (unimorph deformation) so as to be convex toward the pressure chamber 10 based on the piezoelectric lateral effect.
Then, the volume of the pressure chamber 10 decreases, the pressure of the ink rises, and the ink is ejected from the ink ejection port 8. After that, when the potentials of the individual electrodes 35a and 35b return to their original values, the piezoelectric sheets 41 to 45 return to their original flat plate shapes, and the volume of the pressure chamber 10 returns to the original volume, so that ink is sucked from the manifold 5 side.

As another driving method, the individual electrodes 35a, 35b are set to a potential different from that of the common electrodes 34a, 34b in advance, and the individual electrodes 35a, 3 are supplied every time an ejection request is made.
5b is once set to the same potential as the common electrodes 34a, 34b, and then, again at a predetermined timing, the individual electrodes 35a, 35b are again set.
Can have a potential different from that of the common electrodes 34a and 34b. In this case, the piezoelectric sheets 41 to 45 return to their original shape at the timing when the individual electrodes 35a and 35b and the common electrodes 34a and 34b have the same potential, and the volume of the pressure chamber 10 is in the initial state (the potential of both electrodes is The ink is sucked into the pressure chamber 10 from the manifold 5 side as compared with the (different state). After that, at a timing when the individual electrodes 35a and 35b are set to different potentials from the common electrodes 34a and 34b again,
The piezoelectric sheets 41 to 45 are deformed so as to be convex toward the pressure chamber 10, and the volume of the pressure chamber 10 decreases, so that the pressure on the ink rises and the ink is ejected.

If the direction of the electric field applied to the piezoelectric sheets 41 to 43 is opposite to the direction of its polarization, the piezoelectric lateral effect causes
The active layers in the piezoelectric sheets 41 to 43 sandwiched between the individual electrodes 35a and 35b and the common electrodes 34a and 34b tend to extend in the direction perpendicular to the polarization direction. Therefore, the piezoelectric sheet 41
To 45 are deformed so as to be concave on the pressure chamber 10 side. Therefore, the volume of the pressure chamber 10 increases and ink is sucked from the manifold 5 side. Then, the individual electrodes 35a, 3
When the potential of 5b returns to the original, the piezoelectric sheets 41 to 45 return to their original flat plate shapes, and the volume of the pressure chamber 10 returns to the original volume, so that ink is ejected from the ink ejection port 8.

As described above, in the ink jet head 1 of the present embodiment, the individual electrode 35a and the FPC 136 provided on the piezoelectric sheet 41 farthest from the pressure chamber 10 are connected to the auxiliary electrode portion 61a and the power supply pad 55a. The two electrical contacts between the auxiliary electrode portion 61b and the power supply pad 55b are directly connected by electrical connection by soldering. Therefore, at one of the electrical contacts, the individual electrodes 35a and F
Even if the electrical connection with the PC 136 is not performed in some cases or the electrical connection at one of the electrical contacts is released, the electrical connection between the two is ensured. Therefore, the reliability of the electrical connection between the individual electrode 35a and the FPC 136 is improved, and the inkjet head 1 and the inkjet printer 101 having the inkjet head 1 are less likely to malfunction.

Further, each pressure chamber 1 on the surface opposite to the surface on the pressure chamber 10 side of the piezoelectric sheet 41 farthest from the pressure chamber 10.
Since the individual electrode 35a is arranged at a position corresponding to 0, and the individual electrode 35a and the power supply pads 55a and 55b provided on the FPC 136 are directly and electrically joined by soldering, the FPC 136 on the side surface of the actuator 21. It is not necessary to extend the conductive member, which is electrically connected to the individual electrode 35a and is electrically connected to, along the piezoelectric sheet 41 to the end thereof. Since such a separate conductive member is formed so as to avoid the individual electrodes 35a on the piezoelectric sheet 41, if an attempt is made to ensure sufficient electrical insulation,
It is necessary to secure a sufficient space between the individual electrodes 35a, and as a result, the arrangement density of the pressure chambers 10 is reduced. In addition, the separate conductive member is the piezoelectric sheet 4.
The deformation of 1 to 45 in the stacking direction may be hindered. According to the present embodiment, the individual electrodes 35a and the FPCs 136 can be electrically connected without providing a separate conductive member as described above, so that the arrangement density of the pressure chambers 10 can be improved, and , Piezoelectric sheets 41-45
It is possible to increase the amount of deformation in the stacking direction.

Further, in the ink jet head 1 according to this embodiment, the auxiliary electrode portion 61a and the power supply pad 55a are provided.
, And the auxiliary electrode portion 61b and the power supply pad 55b at a total of two electrical contacts, both of which are connected to the pressure chamber 1
Since it corresponds to the 0 outer region, the deformation in the stacking direction of the main electrode portion 60 corresponding to the inner region of the pressure chamber 10 of the individual electrode 35a is hardly obstructed. Therefore, the main electrode portion 60 of the individual electrode 35a can be largely displaced in the stacking direction while resisting the internal pressure in the pressure chamber 10. Therefore, the volume change amount of the pressure chamber 10 becomes large,
Even if the pressure chamber 10 is reduced in size to achieve higher integration, a sufficient amount of ink can be ejected.

The individual electrode 35a on the piezoelectric sheet 41 is also used.
Electrode 38 for grounding arranged around the region in which the
However, the power supply pad 5 electrically connected to the individual electrode 35a
Since it is electrically joined to the FPC 136 having 5a and 55b by soldering, when a force for peeling off the FPC 136 is applied from the outside, the FPC 136 and the ground electrode 38 are first electrically joined. After the release, the electrical connection between the individual electrode 35a and the power supply pads 55a and 55b is released. Therefore, unless relatively large force is applied, the individual electrode 35a and the power supply pad 5
5a, 55b electrical connection is not released,
The reliability of these electrical connections is improved, and an inkjet head 1 and an inkjet printer 1 including the inkjet head 1 are provided.
01 failure is less likely to occur.

Further, in the ink jet head 1 according to the present embodiment, the individual electrode 35a and the power supply pads 55a, 5a and 5b.
Since the structure for preventing the electrical connection with 5b is partially used as the power supply structure for keeping the common electrodes 34a and 34b at the ground potential, the structure of the inkjet head 1 is simplified. There is.

Then, the individual electrode 35 on the piezoelectric sheet 41 is formed.
Since the region where a is formed is surrounded by a large number of grounding electrodes 38, it is difficult to release the electrical connection between the FPC 136 and the individual electrode 35a regardless of the direction from which the force for peeling the FPC 136 is removed. And power supply pads 55a, 55
The reliability of the electrical connection with b is improved.

Further, since the FPC 136 is used as the power feeding member, the head body 1a and the driver IC 132 are
It is easy to electrically connect between and. On the other hand, FP
Although the C136 is likely to be applied with a force for peeling it off, as described above, it is electrically joined to the individual electrode 35a at two electric contacts for each pressure chamber 10 and the actuator unit 2 is connected to the plurality of grounding electrodes 38 at a large number.
By being electrically connected to No. 1, the strength is improved and the reliability is increased.

In this embodiment, the individual electrode 35a is
The electric contacts between the FPC 136 and the FPC 136 are provided at two locations corresponding to the vicinity of both ends of each pressure chamber 10, but three or more electric contacts may be provided for each individual electrode 35a. Further, the position of each electric contact can be arbitrarily changed. However, it is more preferable that they are relatively distant as in the present embodiment than that they are closely arranged.

Further, in the present embodiment, the individual electrode 3
The grounding electrode 38 may not be arranged around the region where the 5a is present. Further, in the present embodiment, a plurality of ground electrodes 3 are provided around the area where the individual electrode 35a is present.
8 is arranged and the grounding electrode 38 is electrically joined to the FPC 136, the individual electrode 35a formed on the piezoelectric sheet 41 has one electric contact (power supply pad 55
a) or 55b), and may be electrically bonded to the FPC 136.

Further, two or more ground electrodes 38 may be arranged around the area where the individual electrodes are formed, and the number and arrangement of the ground electrodes 38 can be arbitrarily changed. Therefore, the ink ejection area does not necessarily have to be surrounded by the grounding electrode 38 over the entire circumference.

In the present embodiment, the ground electrode 38 is also used.
Is connected to the common electrode 34a through the conductive material 49 provided in the through hole 41b, but a conductive member for drawing out to the end of the piezoelectric sheet is formed for each of the ground electrode and the common electrode. , These conductive members may be connected to the FPC 136 at the ends of the piezoelectric sheet.

Next, a second embodiment of the present invention will be described with further reference to FIGS. 12 (a) to 13 (b). FIGS. 12A and 12B are views of the inkjet head according to the present embodiment shown in FIGS.
It is sectional drawing corresponding to (b). FIG. 13 (a) is shown in FIG.
FIG. 2 (a) is an enlarged view in a circular frame drawn with a dashed line. FIG. 13B is an enlarged view in a circular frame drawn by the alternate long and short dash line in FIG. In this embodiment, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The ink jet head according to the present embodiment differs from the ink jet head 1 according to the first embodiment in that the piezoelectric sheet 41 including the active layer farthest from the pressure chamber 10 is provided in the first embodiment. While the individual electrodes 35a are arranged on the surface opposite to the surface on the pressure chamber 10 side, in the present embodiment, as shown in FIG. 12A, six electrodes included in the actuator unit 80 are included. The surface electrode 76 is arranged instead of the individual electrode on the surface of the piezoelectric sheet 81-86 farthest from the pressure chamber 10 opposite to the surface on the pressure chamber 10 side. .

Regarding the structure of the actuator unit 80 in the ink jet head according to this embodiment,
This will be described in detail below. As shown in FIGS. 12A and 12B, the actuator unit 80 includes six piezoelectric sheets 81, 82, 83, 84, 85, 86.
The piezoelectric sheets 81 to 86 are continuous flat layers, and the piezoelectric sheets 81 to 86 are arranged over a large number of pressure chambers 10 formed in an ink ejection area corresponding to one actuator unit 80 in the inkjet head. ing.

A common electrode 74 having a thickness of about 2 μm is provided between the piezoelectric sheet 82 which is the second layer from the uppermost layer of the actuator unit 80 and the piezoelectric sheet 83 which is adjacent to the lowermost piezoelectric sheet 82.
a is present. The common electrode 74a extends over almost the entire area within one actuator unit 80.
It is a conductive sheet. Similarly, between the piezoelectric sheet 84 adjacent to the lower layer of the piezoelectric sheet 83 and the piezoelectric sheet 85 adjacent to the lower layer thereof, the common electrode 74b having the same shape as the common electrode 74a and having a thickness of about 2 μm is interposed. .

As shown in FIG. 12A, the piezoelectric sheet 8
3 and the piezoelectric sheet 84 at a position corresponding to the pressure chamber 10, the individual electrode 35a having the main electrode portion 60 and the two auxiliary electrode portions 61a and 61b on both sides thereof as shown in FIG. An individual electrode 75a having the same shape as the above and having a thickness of about 2 μm is interposed. Further, between the piezoelectric sheets 85 and 86, at a position corresponding to the individual electrode 75a, an individual electrode 75b having the same shape as the individual electrode 75a and having a thickness of about 2 μm is interposed.

At the position corresponding to the pressure chamber 10 on the upper surface of the uppermost piezoelectric sheet 81, the individual electrode 75 is formed.
a surface electrode 76 having a shape similar to that of a and having a thickness of about 1 μm
Are formed. No electrodes are arranged between the piezoelectric sheet 81 and the piezoelectric sheet 82 adjacent therebelow, and below the piezoelectric sheet 86.

As shown in FIG. 12A, the individual electrode 75
Through holes 81a, 82a, 83a, 84a, and 85a are formed in the piezoelectric sheets 81 to 85 between the positions of a and the individual electrode 75b corresponding to one auxiliary electrode portion. Through holes 81a, 82a, 83a, 84a,
85a is filled with a conductive material (such as silver palladium) 98 as shown in FIG.
The surface electrodes 76, the individual electrodes 75 a, and the individual electrodes 75 b are connected to each other via 8 for each corresponding to each pressure chamber 10.

On the upper surface of the piezoelectric sheet 81 and in the vicinity of the outer edge of the upper surface of the actuator unit 80, as with the grounding electrode 38 shown in FIGS. 78 is formed. The large number of grounding electrodes 78 are separated so that the adjacent electrodes are substantially evenly spaced. Therefore, the region where the surface electrode 76 is formed on the upper surface of the actuator unit 80 is surrounded by many grounding electrodes 78 over the entire circumference.

As shown in FIG. 12B, the ground electrode 7
Through holes 81 b, 82 b, 83 b, 84 b penetrating the piezoelectric sheets 81, 82, 83, 84 are formed below the plate 8. Through holes 81b, 82b, 83
As shown in FIG. 13B, a conductive material (silver-palladium or the like) 99 is filled in b and 84b, and the ground electrode 78 is connected to the common electrode 74a and the common electrode 74b through the conductive material 99. It is connected. In the present embodiment, the electrodes 74a, 74b, 75a, 75b, 78 are
It is made of a metal material such as Ag-Pd.

In this embodiment, one surface electrode 76 has two electrical contacts (each of which is a power supply pad 55).
FPC13 at positions corresponding to a and 55b)
6 is electrically connected. Thereby, the conductive material 9 in the printed wiring 53 and the through holes 81a to 85a is formed.
The potential of the individual electrodes 75a and 75b is applied via the pressure chamber 10
Each can be controlled independently.

On the other hand, the ground electrode 78 is electrically joined to the power supply pad 55c of the FPC 136. As a result, the printed wiring 53 and the through holes 81b to 84b are formed.
The potentials of the common electrodes 74a and 74b can be maintained at the ground potential via the conductive material 99 inside.

In this embodiment, the actuator unit 80 has the three piezoelectric sheets 83 to 85 as layers in which the active layers are present, and the three piezoelectric sheets 81 arranged so as to sandwich the piezoelectric sheets 83 to 85, 82 and 86 are configured as inactive layers. Then, the driver IC 13
2 to control the individual electrodes 75a, 7 via the surface electrode 76.
If 5b is set to a predetermined positive or negative potential, the piezoelectric sheet 83-
A portion sandwiched between the individual electrode and the common electrode in 85 functions as an active layer. Then, the active layer expands or contracts in the thickness direction of the sheet due to the piezoelectric effect, the volume of the pressure chamber 10 changes, and ink is ejected from the ink ejection port.

In the ink jet head of the present embodiment, the surface electrode 76 and the FPC 136 provided on the piezoelectric sheet 81 farthest from the pressure chamber 10 have the above-mentioned two components.
The electrical contacts at the points are directly connected by electrical connection by soldering. Therefore, even if the electric contact between the surface electrode 76 and the FPC 136 may not be made at one of the electric contacts, or even if the electric connection at the one electric contact is released, the electric connection between them is secured. To be done. Therefore, the individual electrodes 35a and 35b and the FP
The reliability of the electrical connection with the C136 is improved, and the inkjet head 1 and the inkjet printer 101 including the inkjet head 1 are less likely to malfunction.

Further, each pressure chamber 1 on the surface of the piezoelectric sheet 81 farthest from the pressure chamber 10 opposite to the surface on the pressure chamber 10 side.
The surface electrode 76 is disposed at a position corresponding to 0, and the power supply pad 55 provided on the surface electrode 76 and the FPC 136.
Since a and 55b are directly and electrically joined by soldering, there is no need to separately form a conductive member for electrically connecting the surface electrode 76 and the FPC 136 along the piezoelectric sheet 81. According to the present embodiment, the surface electrode 76 and the FP can be formed without providing such a separate conductive member.
Since the C136 can be electrically connected, the arrangement density of the pressure chambers 10 can be improved, and moreover, the deformation amount of the piezoelectric sheets 81 to 86 in the stacking direction can be increased.

In addition, according to this embodiment, the same benefits as those of the first embodiment can be obtained.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-mentioned embodiments, and various design changes are possible within the scope of the claims. Is. For example, the materials for the piezoelectric sheet and the electrodes are not limited to those described above, and other known materials may be used. Further, the planar shape, the cross-sectional shape, the arrangement form, etc. of the pressure chambers may be appropriately changed. Further, the number of piezoelectric sheets including the active layer and the number of piezoelectric sheets not including the active layer can be appropriately changed. Further, the layer thicknesses of the piezoelectric sheet including the active layer and the piezoelectric sheet not including the active layer may be the same or different. Further, in the above-described embodiment, the inactive layers are all piezoelectric sheets, but an insulating sheet other than the piezoelectric sheet may be used as the inactive layer.

[0099]

As described above, according to the present invention,
It is possible to provide an inkjet head having excellent reliability of electrical connection between the individual electrodes of the actuator unit and the power supply member, and an inkjet printer including the inkjet head.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an inkjet printer including an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the inkjet head according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 is a plan view of a head body included in the inkjet head depicted in FIG. 2. FIG.

5 is an enlarged view of a region surrounded by an alternate long and short dash line drawn in FIG. 4. FIG.

FIG. 6 is an enlarged view of a region surrounded by an alternate long and short dash line drawn in FIG.

7 is a partial cross-sectional view of the head main body depicted in FIG. 4 and a flexible printed wiring board attached to the head main body.

FIG. 8 is a partial exploded perspective view of the head body and the flexible printed wiring board attached to the head body depicted in FIG.

9 (a) is a cross-sectional view of the actuator unit to which the flexible printed wiring board is attached, taken along line IXA-IXA shown in FIG. 6, and shown in FIG. It is an enlarged view of the area | region enclosed by the dashed-dotted line. FIG. 9B is taken along line IXB-IXB drawn in FIG.
It is sectional drawing of the actuator unit to which the flexible printed wiring board was attached.

10 (a) is an enlarged view of the inside of a circular frame drawn by the alternate long and short dash line in FIG. 9 (a). FIG. 10B is an enlarged view of the inside of a circular frame drawn by the alternate long and short dash line of FIG. 9B.

11 is a schematic partial enlarged plan view of FIG.

FIG. 12 (a) is a sectional view of an inkjet head according to a second embodiment of the present invention, corresponding to FIG. 9 (a). FIG. 12B is a sectional view of the inkjet head according to the second embodiment of the present invention, which corresponds to FIG. 9B.

FIG. 13A is an enlarged view of the inside of a circular frame drawn by the alternate long and short dash line in FIG. FIG. 13B is an enlarged view in a circular frame drawn by the alternate long and short dash line in FIG.

[Explanation of symbols]

1 Inkjet Head 1a Head Body 4 Channel Unit 5 Manifold 5a Sub Manifold 8 Ink Ejection Port 10 Pressure Chamber 12 Aperture 21 Actuator Unit 22 Cavity Plate 30 Nozzle Plate 32 Ink Channels 34a, 34b Common Electrodes 35a, 35b Individual Electrode 38 Grounding Electrodes (peripheral electrodes) 41 to 43 Piezoelectric sheets (layers including active layers) 44, 45 Piezoelectric sheets (inactive layers) 41a, 42a Through holes 41b to 43b Through holes 48, 49 Conductive materials 55a, 55b, 55c Power supply pads ( Power supply terminal) 101 Inkjet printer 136 Flexible printed wiring board (FPC) (power supply member)

Claims (13)

[Claims] 1. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit are provided, and the actuator unit is A common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, wherein the piezoelectric electrodes at least farthest from the pressure chamber The sheet is sandwiched by the common electrode and at least one of the individual electrodes, and the pressure chamber of the piezoelectric sheet that is farthest from the pressure chamber. A plurality of piezoelectric sheets, each individual electrode on the surface opposite to the side surface is electrically bonded to the power supply terminal at each of a plurality of electrical contacts on the individual electrode. An inkjet head characterized in that. 2. The ink jet head according to claim 1, wherein the electric contacts are provided at two locations corresponding to the vicinity of both ends of the pressure chamber. 3. The electrical contact is provided outside an area corresponding to the pressure chamber.
The inkjet head according to item 2. 4. The power feeding member is a flexible printed wiring board, according to claim 1.
Inkjet head according to item. 5. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane, and the pressure. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit are provided, and the actuator unit is , A common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, wherein the piezoelectric sheets farthest from the pressure chambers A plurality of piezoelectric sheets in which at least one piezoelectric sheet other than the above is sandwiched by the common electrode and at least one individual electrode; A plurality of surface electrodes arranged at positions corresponding to the individual electrodes on the surface opposite to the pressure chamber side surface of the piezoelectric sheet farthest away from the piezoelectric sheet, each surface electrode being one or a plurality of the piezoelectric electrodes. A plurality of electrical contacts connected to the corresponding individual electrodes through a conductive material provided in a through-hole penetrating the sheet and electrically connected to the power supply terminal at each of a plurality of electrical contacts on the surface electrode; An ink-jet head including a front surface electrode of. 6. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit are provided, and the actuator unit is A common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, wherein the piezoelectric electrodes at least farthest from the pressure chamber The sheet is sandwiched by the common electrode and at least one of the individual electrodes, and the pressure chamber of the piezoelectric sheet that is farthest from the pressure chamber. Each individual electrode on the surface opposite to the side surface is electrically bonded to the power supply terminal, a plurality of piezoelectric sheets, and the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber A plurality of peripheral electrodes arranged around a region where the plurality of individual electrodes are present on a surface opposite to the surface, the peripheral electrodes being electrically connected to the common electrode and electrically connected to the power supply terminal. An inkjet head comprising a plurality of peripheral electrodes, at least one of which is included. 7. The ink jet head according to claim 6, wherein the region is substantially surrounded by a plurality of the peripheral electrodes. 8. The ink jet head according to claim 6, wherein two or more of the peripheral electrodes are electrically connected to the common electrode and electrically joined to the power supply terminal. 9. The power feeding member is a flexible printed wiring board, according to any one of claims 6 to 8.
Inkjet head according to item. 10. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit are provided, and the actuator unit is , A common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, wherein the piezoelectric sheets are farthest from the pressure chambers A plurality of piezoelectric sheets in which at least one piezoelectric sheet other than the above is sandwiched between the common electrode and at least one individual electrode; A plurality of surface electrodes arranged at positions corresponding to the individual electrodes on the surface opposite to the pressure chamber side surface of the piezoelectric sheet farthest from the chamber, each surface electrode being one or more of the above A plurality of surface electrodes, which are connected to the corresponding individual electrodes and are electrically joined to the power supply terminals through a conductive material provided in a through hole that penetrates the piezoelectric sheet, and are most distant from the pressure chamber. A plurality of peripheral electrodes arranged around a region where the plurality of surface electrodes are present on a surface opposite to the surface on the pressure chamber side of the piezoelectric sheet, the peripheral electrodes being electrically connected to the common electrode, and An inkjet head comprising: at least one peripheral electrode electrically connected to the power supply terminal. 11. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, the plurality of pressure chambers being arranged adjacent to each other along a plane, and the pressure unit. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit are provided, and the actuator unit is A common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, wherein the piezoelectric electrodes at least farthest from the pressure chamber The sheet is sandwiched by the common electrode and at least one of the individual electrodes, and the pressure of the piezoelectric sheet most distant from the pressure chamber. A plurality of piezoelectric sheets, wherein each individual electrode on the surface opposite to the chamber-side surface is electrically joined to the power supply terminal at each of two electric contacts on the individual electrode. A second electrode region in which the individual electrode is connected to one end of the first electrode region and a first electrode region having a planar shape similar to the pressure chamber, and in which one of the electrical contacts is provided. And a third electrode region provided with one of the electrical contacts, the third electrode region being connected to the other end of the first electrode region so as to face the second electrode region, With respect to a direction in which a connecting portion between the second electrode region and the second electrode region is substantially orthogonal to a direction connecting the second electrode region and the third electrode region. The first electrode region has a length shorter than that of the second electrode region, The connection between the electrode region and the third electrode region is substantially orthogonal to the direction connecting the second electrode region and the third electrode region, and the first electrode region and the first electrode region An inkjet head having a length shorter than the electrode region of No. 3. 12. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. An inkjet printer including an inkjet head including an actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. Wherein the actuator unit is a common electrode held at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated on each other, The piezoelectric sheet farthest from the pressure chamber is sandwiched between the common electrode and at least one individual electrode. , Each individual electrode on the surface of the piezoelectric sheet farthest from the pressure chamber opposite to the surface on the pressure chamber side is electrically connected to the power supply terminal at each of a plurality of electrical contacts on the individual electrode. An inkjet printer, comprising: a plurality of piezoelectric sheets bonded to each other. 13. A flow channel unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane, and the pressure. An inkjet printer including an inkjet head including an actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, and a power supply member provided with a power supply terminal for supplying a drive signal to the actuator unit. Wherein the actuator unit is a common electrode kept at a constant potential, a plurality of individual electrodes arranged at positions corresponding to the respective pressure chambers, and a plurality of piezoelectric sheets laminated with each other, The piezoelectric sheet farthest from the pressure chamber is sandwiched between the common electrode and at least one individual electrode. In, a plurality of piezoelectric sheets, each individual electrode on the surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber is electrically joined to the power supply terminal, A plurality of peripheral electrodes arranged around an area where the plurality of individual electrodes are present on a surface opposite to the surface on the pressure chamber side of the piezoelectric sheet farthest from the pressure chamber, the common electrode An inkjet printer, comprising: a plurality of peripheral electrodes that are electrically connected to and electrically connected to the power supply terminal.