JP2013154597A - Piezoelectric actuator substrate for liquid discharge head, liquid discharge head and recording apparatus using the same, and method for manufacturing piezoelectric actuator substrate for liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a piezoelectric actuator substrate for a liquid discharge head, which can inspect electric connection through a conductor in a plurality of penetration holes, and to provide a piezoelectric actuator substrate for a liquid discharge head, a liquid discharge head and a recording apparatus using the same.SOLUTION: A piezoelectric actuator substrate for a liquid discharge head is manufactured by manufacturing a piezoelectric actuator element which includes a laminate in which a common electrode 34 is disposed therein and a plurality of individual electrodes 35 are disposed on the surface thereof, a plurality of penetration holes which penetrate through layers in the laminate and are connected to the common electrode 34, and a plurality of first surface electrodes 71 for the common electrode arranged at each penetration hole; inspecting the conduction between the first surface electrode 71 for the common electrode and the common electrode 34 of the piezoelectric actuator element; and then forming a second surface electrode 72 for the common electrode so as to connect the plurality of first surface electrodes 71 for the common electrode of the piezoelectric actuator element.

Description

  The present invention relates to a piezoelectric actuator substrate for a liquid ejection head that ejects droplets, a liquid ejection head and a recording apparatus using the same, and a method for manufacturing a piezoelectric actuator substrate for a liquid ejection head.

  In recent years, printing apparatuses using inkjet recording methods such as inkjet printers and inkjet plotters are not only printers for general consumers, but also, for example, formation of electronic circuits, manufacture of color filters for liquid crystal displays, manufacture of organic EL displays It is also widely used for industrial applications.

  In such an ink jet printing apparatus, a liquid discharge head for discharging liquid is mounted as a print head. This type of print head includes a heater as a pressurizing unit in an ink flow path filled with ink, heats and boiles the ink with the heater, pressurizes the ink with bubbles generated in the ink flow path, A thermal head system that ejects ink as droplets from the ink ejection holes, and a part of the wall of the ink channel filled with ink is bent and displaced by a displacement element, and the ink in the ink channel is mechanically pressurized, and the ink A piezoelectric method for discharging liquid droplets from discharge holes is generally known.

  In addition, in such a liquid discharge head, a serial type that performs recording while moving the liquid discharge head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and main scanning from the recording medium There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with a liquid discharge head that is long in the direction fixed. The line type has the advantage that high-speed recording is possible because there is no need to move the liquid discharge head as in the serial type.

  In order to print droplets at a high density in any of the serial type and line type liquid discharge heads, the density of the liquid discharge holes for discharging the droplets formed in the liquid discharge head must be increased. There is a need to.

  Accordingly, the liquid discharge head includes a manifold and a flow path member having a liquid discharge hole that connects the manifold via a plurality of liquid pressurization chambers, and a plurality of displacement elements provided so as to cover the liquid pressurization chambers. A structure obtained by laminating a piezoelectric actuator substrate having the structure is known (for example, see Patent Document 1). In this liquid ejection head, the liquid pressurizing chambers connected to the plurality of liquid ejection holes are arranged in a matrix, and the displacement element of the actuator unit provided so as to cover it is displaced by deformation of the piezoelectric body, Ink is ejected from each liquid ejection hole, and printing is possible at a resolution of 600 dpi in the main scanning direction.

JP 2003-305852 A

In the liquid discharge head as described in Patent Document 1, individual drive signals are supplied to the respective displacement elements, and the electrodes serving as the ground potential are connected common electrodes. Even if the common electrode is electrically connected, if the electrical resistance between them is large, the drive signal that is actually applied to the displacement element, and fluctuations such as the waveform being distorted with respect to the original drive signal may occur. In a liquid discharge head in which the voltage is turned on and off in units of several microseconds as a signal, such rounding of the drive signal affects variations in the discharge characteristics and cannot be ignored.

  When the wiring of the ground potential is performed through the conductor in the through hole penetrating the piezoelectric ceramic layer, it is conceivable to arrange a large number of through holes to strengthen the ground. In such a case, even if the conductor in one of the through holes is not connected or has poor conduction such as high conductor resistance, the conductors in many through holes are electrically connected. It was difficult to inspect because of the connection.

  Accordingly, an object of the present invention is to provide a method for manufacturing a piezoelectric actuator substrate for a liquid discharge head capable of inspecting an electrical connection through a conductor in a plurality of through holes, a piezoelectric actuator substrate for a body discharge head, and a liquid discharge head using the same And providing a recording apparatus.

  A piezoelectric actuator substrate for a liquid discharge head according to the present invention includes a laminate in which a vibration plate and at least one piezoelectric ceramic layer are laminated, and a main surface on the piezoelectric ceramic layer side of the laminate in a first direction and A plurality of individual electrodes arranged in a direction different from the first direction, a common electrode arranged in the laminated body, and the piezoelectric ceramic layer so as to be connected to the common electrode A piezoelectric actuator substrate for a liquid discharge head comprising a plurality of through holes and a surface electrode for a common electrode disposed across the plurality of through holes on a main surface on the piezoelectric ceramic layer side, The common electrode surface electrode is for a second common electrode that connects a plurality of first common electrode surface electrodes arranged for each one of the through holes and a plurality of the first common electrode surface electrodes. surface Characterized in that it comprises a pole.

  Preferably, the plurality of individual electrodes are arranged in a polygonal region, and the plurality of through holes and the common electrode surface electrode are arranged along at least one side of the polygonal shape.

  The first common electrode surface electrode is not disposed in the through-hole disposed in the central portion of the one side, and the second common electrode surface electrode is the first common electrode surface. It is preferable that it is connected with the common electrode without interposing.

  It is preferable that the arrangement density of the through holes at the end of the one side is higher than the arrangement density of the through holes at the center of the one side.

  It is preferable that the through-hole and the second surface electrode for common electrode are disposed up to a portion extending the one side.

  The through holes are preferably arranged in two or more rows along the one side.

  The liquid discharge head of the present invention includes the piezoelectric actuator substrate for the liquid discharge head, a plurality of discharge holes, and a plurality of pressurizing chambers connected to the plurality of discharge holes, respectively, A plurality of pressurizing chambers and a flow path member joined to the piezoelectric actuator substrate for the liquid discharge head so that the plurality of individual electrode bodies and the plurality of pressurizing chambers overlap each other. Features.

The recording apparatus of the present invention includes the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the piezoelectric actuator substrate and the transport unit. And

  A method of manufacturing a piezoelectric actuator substrate for a liquid discharge head includes: a laminated body in which a diaphragm and at least one piezoelectric ceramic layer are laminated; and a main surface of the laminated body on the piezoelectric ceramic layer side in a first direction and A plurality of individual electrodes arranged in a direction different from the first direction, a common electrode arranged in the laminated body, and the piezoelectric ceramic layer so as to be connected to the common electrode Manufacturing a piezoelectric actuator element body having a plurality of through-holes and a plurality of first common electrode surface electrodes arranged for each of the through-holes, and the plurality of the piezoelectric actuator element bodies An inspection step that the first common electrode surface electrode is electrically connected to the common electrode, and the plurality of first common electrode surface electrodes of the piezoelectric actuator element body that has undergone the inspection step. As it connects the and forming a second common electrode for the surface electrode.

  According to the method for manufacturing a piezoelectric actuator substrate for a liquid discharge head, conduction through a plurality of through holes can be confirmed. As a result, the ground of the common electrode is unlikely to become unstable, and variations in ejection characteristics are reduced.

1 is a schematic configuration diagram of a printer that is a recording apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of a first flow path member and a piezoelectric actuator substrate that constitute the liquid ejection head of FIG. 1. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. It is a top view of a piezoelectric actuator substrate concerning one embodiment of the present invention. (A) is a longitudinal cross-sectional view along the VV line of FIG. 3, (b) is a longitudinal cross-sectional view along the XX line of FIG.

  FIG. 1 is a schematic configuration diagram of a color ink jet printer which is a recording apparatus including a liquid discharge head according to an embodiment of the present invention. This color inkjet printer 1 (hereinafter referred to as printer 1) has four liquid ejection heads 2. These liquid discharge heads 2 are arranged along the conveyance direction of the printing paper P and are fixed to the printer 1. The liquid discharge head 2 has an elongated shape in a direction from the front to the back in FIG. This long direction is sometimes called the longitudinal direction.

  In the printer 1, a paper feed unit 114, a transport unit 120, and a paper receiver 116 are sequentially provided along the transport path of the printing paper P. In addition, the printer 1 is provided with a control unit 100 for controlling the operation of each unit of the printer 1 such as the liquid discharge head 2 and the paper feeding unit 114.

  The paper supply unit 114 includes a paper storage case 115 that can store a plurality of printing papers P, and a paper supply roller 145. The paper feed roller 145 can send out the uppermost print paper P among the print papers P stacked and stored in the paper storage case 115 one by one.

Between the paper feed unit 114 and the transport unit 120, two pairs of feed rollers 118a and 118b and 119a and 119b are arranged along the transport path of the printing paper P. The printing paper P sent out from the paper supply unit 114 is guided by these feed rollers and further sent out to the transport unit 120.

  The transport unit 120 includes an endless transport belt 111 and two belt rollers 106 and 107. The conveyor belt 111 is wound around belt rollers 106 and 107. The conveyor belt 111 is adjusted to such a length that it is stretched with a predetermined tension when it is wound around two belt rollers. Thus, the conveyor belt 111 is stretched without slack along two parallel planes each including a common tangent line of the two belt rollers. Of these two planes, the plane closer to the liquid ejection head 2 is a transport surface 127 that transports the printing paper P.

  As shown in FIG. 1, a conveyance motor 174 is connected to the belt roller 106. The transport motor 174 can rotate the belt roller 106 in the direction of arrow A. The belt roller 107 can rotate in conjunction with the transport belt 111. Therefore, the conveyance belt 111 moves along the direction of arrow A by driving the conveyance motor 174 and rotating the belt roller 106.

  In the vicinity of the belt roller 107, a nip roller 138 and a nip receiving roller 139 are arranged so as to sandwich the conveyance belt 111. The nip roller 138 is urged downward by a spring (not shown). A nip receiving roller 139 below the nip roller 138 receives the nip roller 138 biased downward via the conveying belt 111. The two nip rollers are rotatably installed and rotate in conjunction with the conveyance belt 111.

  The printing paper P sent out from the paper supply unit 114 to the transport unit 120 is sandwiched between the nip roller 138 and the transport belt 111. As a result, the printing paper P is pressed against the transport surface 127 of the transport belt 111 and is fixed on the transport surface 127. The printing paper P is transported in the direction in which the liquid ejection head 2 is installed according to the rotation of the transport belt 111. The outer peripheral surface 113 of the conveyor belt 111 may be treated with adhesive silicon rubber. Thereby, the printing paper P can be securely fixed to the transport surface 127.

  The four liquid discharge heads 2 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each liquid discharge head 2 has a head body 13 at the lower end. A large number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the head body 13.

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. Each liquid discharge head 2 is supplied with liquid from an external liquid tank (not shown). The liquid discharge holes 8 of each liquid discharge head 2 are arranged at equal intervals in one direction (a direction parallel to the print paper P and perpendicular to the transport direction of the print paper P and the longitudinal direction of the liquid discharge head 2). , It can be printed without gaps in one direction. The colors of the liquid ejected from each liquid ejection head 2 are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid ejection head 2 is disposed with a slight gap between the lower surface of the head body 13 and the transport surface 127 of the transport belt 111.

  The printing paper P transported by the transport belt 111 passes through the gap between the liquid ejection head 2 and the transport belt 111. At that time, droplets are ejected from the head main body 13 constituting the liquid ejection head 2 toward the upper surface of the printing paper P. As a result, a color image based on the image data stored by the control unit 100 is formed on the upper surface of the printing paper P.

  A separation plate 140 and two pairs of feed rollers 121a and 121b and 122a and 122b are arranged between the transport unit 120 and the paper receiver 116. The printing paper P on which the color image is printed is conveyed to the peeling plate 140 by the conveying belt 111. At this time, the printing paper P is peeled from the transport surface 127 by the right end of the peeling plate 140. Then, the printing paper P is sent out to the paper receiving unit 116 by the feed rollers 121a to 122b. In this way, the printed printing paper P is sequentially sent to the paper receiving unit 116 and stacked on the paper receiving unit 116.

  Note that a paper surface sensor 133 is installed between the liquid ejection head 2 and the nip roller 138 that are the most upstream in the transport direction of the printing paper P. The paper surface sensor 133 includes a light emitting element and a light receiving element, and can detect the leading end position of the printing paper P on the transport path. The detection result by the paper surface sensor 133 is sent to the control unit 100. The control unit 100 can control the liquid ejection head 2, the conveyance motor 174, and the like so that the conveyance of the printing paper P and the printing of the image are synchronized based on the detection result sent from the paper surface sensor 133.

  Next, the head main body 13 constituting the liquid discharge head of the present invention will be described. FIG. 2 is a top view showing the head main body 13 shown in FIG. FIG. 3 is an enlarged top view of a region surrounded by the alternate long and short dash line in FIG. 2 and is a part of the head main body 13. FIG. 4 is an enlarged perspective view of the same position as in FIG. 3, in which some of the flow paths are omitted so that the position of the liquid discharge holes 8 can be easily understood. 3 and 4, for easy understanding of the drawings, the liquid pressurization chamber 10 (liquid pressurization chamber group 9), the squeeze 12 and the liquid discharge holes which are to be drawn by broken lines below the piezoelectric actuator substrate 21 are shown. 8 is drawn with a solid line. FIG. 5 is a plan view of the piezoelectric actuator substrate 21. Similarly, in FIG. 5, the first common electrode surface electrode 71 and the through hole 39 are drawn with solid lines. 6A is a longitudinal sectional view taken along line VV in FIG. 3, and FIG. 6B is a longitudinal sectional view taken along line XX in FIG.

  The head main body 13 has a flat plate-like channel member 4 and a piezoelectric actuator substrate 21 on the channel member 4. The piezoelectric actuator substrate 21 has a trapezoidal shape, and is disposed on the upper surface of the flow path member 4 so that a pair of parallel opposing sides of the trapezoid is parallel to the longitudinal direction of the flow path member 4. In addition, two piezoelectric actuator substrates 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of the two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator substrates 21 adjacent to each other on the flow path member 4 partially overlap in the short direction of the flow path member 4. In the area printed by driving the overlapping piezoelectric actuator unit 21, the droplets ejected by the two piezoelectric actuator substrates 21 are mixed and landed.

  A manifold 5 that is a part of the liquid flow path is formed inside the flow path member 4. The manifold 5 has an elongated shape extending along the longitudinal direction of the flow path member 4, and an opening 5 b of the manifold 5 is formed on the upper surface of the flow path member 4. A total of ten openings 5 b are formed along each of two straight lines (imaginary lines) parallel to the longitudinal direction of the flow path member 4. The opening 5b is formed at a position that avoids a region where the four piezoelectric actuator substrates 21 are disposed. The manifold 5 is supplied with liquid from a liquid tank (not shown) through the opening 5b.

The manifold 5 formed in the flow path member 4 is branched into a plurality of branches (the manifold 5 at the branched portion may be referred to as a sub-manifold 5a). The manifold 5 connected to the opening 5 b extends along the oblique side of the piezoelectric actuator substrate 21 and is disposed so as to intersect with the longitudinal direction of the flow path member 4. In a region sandwiched between two piezoelectric actuator substrates 21, one manifold 5 is shared by adjacent piezoelectric actuator substrates 21,
The sub-manifold 5 a branches off from both sides of the manifold 5. These sub-manifolds 5 a extend in the longitudinal direction of the head main body 13 adjacent to each other in regions facing the piezoelectric actuator substrates 21 inside the flow path member 4.

  The flow path member 4 has four liquid pressurizing chamber groups 9 in which a plurality of liquid pressurizing chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The liquid pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The liquid pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These liquid pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator substrate 21. Accordingly, each liquid pressurizing chamber group 9 formed by these liquid pressurizing chambers 10 occupies a region having almost the same size and shape as the piezoelectric actuator substrate 21. Further, the opening of each liquid pressurizing chamber 10 is closed by adhering the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  In the present embodiment, as shown in FIG. 3, the manifold 5 branches into four rows of E1-E4 sub-manifolds 5a arranged in parallel with each other in the short direction of the flow path member 4, and each sub-manifold The liquid pressurizing chambers 10 connected to 5a constitute a row of liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the four rows are arranged in parallel to each other in the short direction. Yes. Two rows of liquid pressurizing chambers 10 connected to the sub-manifold 5a are arranged on both sides of the sub-manifold 5a.

  As a whole, the liquid pressurizing chambers 10 connected from the manifold 5 constitute rows of the liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the rows are 16 rows parallel to each other in the short direction. It is arranged. The number of liquid pressurizing chambers 10 included in each liquid pressurizing chamber row is arranged so as to gradually decrease from the long side toward the short side, corresponding to the outer shape of the displacement element 50 that is an actuator. ing. The liquid discharge holes 8 are also arranged in the same manner. As a result, it is possible to form an image with a resolution of 600 dpi in the longitudinal direction as a whole.

  That is, when the liquid discharge hole 8 is projected so as to be orthogonal to a virtual straight line parallel to the longitudinal direction of the flow path member 4, each sub-manifold 5a is connected to the range R of the virtual straight line shown in FIG. Two liquid discharge holes 8, that is, a total of 16 liquid discharge holes 8 are equally spaced at 600 dpi. Moreover, the individual flow paths 32 are connected to the sub manifolds 5a at intervals corresponding to 150 dpi on average. This is because the individual flow paths 32 connected to the sub-manifolds 5a are not always connected at equal intervals when the 600 dpi liquid discharge holes 8 are divided and connected to the four sub-manifolds 5a. This means that the individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm intervals if 150 dpi) in the extending direction of 5a, that is, the main scanning direction.

  Individual electrodes 35 to be described later are formed at positions facing the respective liquid pressurizing chambers 10 and a dummy liquid pressurizing chamber to be described later on the upper surface of the piezoelectric actuator substrate 21. That is, the individual electrode 35 is formed on the upper surface of the piezoelectric actuator substrate 21 in the first direction and in a direction different from the first direction. The individual electrode 35 is slightly smaller than the liquid pressurizing chamber 10, has a shape substantially similar to the liquid pressurizing chamber 10, and fits in a region facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21. Is arranged.

A large number of liquid discharge holes 8 are formed in the liquid discharge surface on the lower surface of the flow path member 4. These liquid discharge holes 8 are arranged at a position avoiding a region facing the sub-manifold 5 a arranged on the lower surface side of the flow path member 4. Further, these liquid discharge holes 8 are arranged in a region facing the piezoelectric actuator substrate 21 on the lower surface side of the flow path member 4. These liquid discharge hole groups 7 occupy regions of substantially the same size and shape as the piezoelectric actuator substrate 21, and the liquid droplets are discharged from the liquid discharge holes 8 by displacing the corresponding displacement elements 50 of the piezoelectric actuator substrate 21. Can be discharged. The arrangement of the liquid discharge holes 8 will be described in detail later. The liquid discharge holes 8 in each region are arranged at equal intervals along a plurality of straight lines parallel to the longitudinal direction of the flow path member 4.

  The above-described flow channel is a flow channel that is directly related to the discharge of droplets, but the flow channel member 4 is provided with a dummy liquid pressurizing chamber that is omitted in the drawing. The dummy liquid pressurizing chambers are formed in a line around the trapezoidal region where the liquid pressurizing chamber 10 is provided. Because the dummy liquid pressurization chamber makes the rigidity of the flow path member 4 around the liquid pressurization chamber 10 on the outermost side of the liquid pressurization chamber 10 close to the state of the other liquid pressurization chambers 10, Variations in liquid ejection characteristics can be reduced. The shape of the dummy liquid pressurizing chamber is the same as that of the liquid pressurizing chamber, but it is not connected to other flow paths. The dummy liquid pressurizing chamber is arranged so as to extend the matrix-like arrangement of the liquid pressurizing chamber 10.

  The flow path member 4 included in the head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are a cavity plate 22, a base plate 23, an aperture (squeezing) plate 24, supply plates 25 and 26, manifold plates 27, 28 and 29, a cover plate 30 and a nozzle plate 31 in order from the upper surface of the flow path member 4. is there. A number of holes are formed in these plates. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 32 and the sub-manifold 5a. As shown in FIG. 6, the head main body 13 has a liquid pressurizing chamber 10 on the upper surface of the flow path member 4, the sub-manifold 5a on the inner lower surface side, and the liquid discharge holes 8 on the lower surface. Each portion constituting the path 32 is disposed close to each other at different positions, and the sub manifold 5 a and the liquid discharge hole 8 are connected via the liquid pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. First, the liquid pressurizing chamber 10 formed in the cavity plate 22. Second, there is a communication hole that forms a flow path that connects from one end of the liquid pressurizing chamber 10 to the sub-manifold 5a. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the liquid pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub manifold 5a). The communication hole includes the aperture 12 formed in the aperture plate 24 and the individual supply flow path 6 formed in the supply plates 25 and 26.

  Third, there is a communication hole that constitutes a flow channel that communicates from the other end of the liquid pressurizing chamber 10 to the liquid discharge hole 8, and this communication hole is referred to as a descender (partial flow channel) in the following description. . The descender is formed on each plate from the base plate 23 (specifically, the outlet of the liquid pressurizing chamber 10) to the nozzle plate 31 (specifically, the liquid discharge hole 8). Fourthly, there is a communication hole constituting the sub-manifold 5a. The communication holes are formed in the manifold plates 27 to 29.

  Such communication holes are connected to each other to form an individual flow path 32 from the liquid inflow port (the outlet of the submanifold 5a) from the submanifold 5a to the liquid discharge hole 8. The liquid supplied to the sub manifold 5a is discharged from the liquid discharge hole 8 through the following path. First, from the sub-manifold 5a, it passes through the individual supply flow path 6 and reaches one end of the aperture 12. Next, it proceeds horizontally along the extending direction of the aperture 12 and reaches the other end of the aperture 12. From there, it reaches one end of the liquid pressurizing chamber 10 upward. Further, the liquid pressurizing chamber 10 proceeds horizontally along the extending direction of the liquid pressurizing chamber 10 and reaches the other end of the liquid pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the liquid discharge hole 8 opened on the lower surface.

The piezoelectric actuator substrate 21 includes two piezoelectric ceramic layers 21 as shown in FIG.
It has a laminated structure consisting of a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The thickness of the laminated body of the piezoelectric ceramic layers 21a and 21b of the piezoelectric actuator substrate 21 is about 40 μm. The piezoelectric actuator substrate 21 is laminated on the planar surface of the flow path member 4 where the liquid pressurizing chamber 10 is open, and any one of the piezoelectric ceramic layers 21 a and 21 b includes a plurality of liquid pressurizing chambers 10. It extends so as to straddle (see FIG. 3). The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator substrate 21 is made of a common electrode 34 made of a metal material such as Ag—Pd, an individual electrode 35 made of a metal material such as Au, and a metal material such as Ag made on the individual electrode 25. A connection land 36 is provided. As described above, the individual electrode 35 is disposed on the upper surface of the piezoelectric actuator substrate 21 at a position facing the liquid pressurizing chamber 10 and the dummy liquid pressurizing chamber. And a connection electrode 35b drawn to a position where there is no 10. The thickness of the individual electrode 35 is 0.3 to 1 μm. A connection land 36 is formed on a connection electrode 35b located in a connection land formation region 80 described later. The connection land 36 is made of, for example, silver containing glass frit, and has a convex shape with a thickness of about 5 to 15 μm. Further, connection bumps are further formed on the connection lands 36 as necessary, and are electrically joined to electrodes provided on an FPC (Flexible Printed Circuit) (not shown). Although details will be described later, a drive signal (drive voltage) is supplied to the individual electrode 35 from the control unit 100 through the FPC. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The above is the structure in the case where the piezoelectric actuator substrate 21 has two piezoelectric ceramic layers. However, the piezoelectric ceramic layers having three or more phases are laminated so that the individual electrodes 35 and the common electrodes 34 are alternately arranged. You may arrange.

  The individual electrodes 35 are formed in a matrix over substantially the entire surface of one main surface of the piezoelectric actuator substrate 21. That is, the first direction and the first direction are formed in different directions.

  Of the individual electrodes 35, the individual electrodes in the rows A, B, and C are dummy individual electrodes 65 that are directly below the dummy liquid pressurizing chamber. The connection electrodes drawn from the dummy individual electrodes may or may not have dummy connection lands 66 formed. The dummy connection land 66 is also formed independently in a portion where the individual electrode 35 (including the dummy individual electrode 35) is not formed, and pressure applied when the piezoelectric actuator substrate 21 and the flow path member 4 are joined. Can be equalized.

  The common electrode 34 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 34 extends so as to cover all the liquid pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 21. The thickness of the common electrode 34 is about 2 μm. The common electrode 34 is a conductor in the plurality of through holes 39 and is connected to the second common electrode surface electrode 72. The diameter of the through hole is about 50 to 200 μm. A first common electrode surface electrode 71 is formed between some of the through holes 39 and the second common electrode surface electrode 72. The conductor in the through hole 39 may be filled with a via conductor in advance, or the first common electrode surface electrode 71 or the second common electrode surface electrode 72 may enter the through hole 39.

With this structure, when the piezoelectric actuator substrate 21 is manufactured, the conduction or resistance value through the conductor in the through hole 39 between the plurality of first common electrode surface electrodes 71 and the common electrode 34 is obtained. Can be confirmed. If a part of the resistance is high or there is a part that is not conductive, a difference occurs between the drive signal that is effectively applied to the displacement element 50 in the vicinity thereof and the drive signal that is applied to the other displacement element 50. A difference occurs in the discharge characteristics. When the drive signal includes a change in signal on the order of μ seconds, the influence of such a ground becomes large.

  In order to reduce the influence of the ground in each displacement element 50, the individual electrodes 35, that is, the displacement elements 50 are arranged in a polygonal shape, and a plurality of through holes 39 are arranged along one of them to connect them. A second common electrode surface electrode 72 may be provided. Since the stability of the ground is distributed so as to spread from one side, the difference in ejection characteristics between the adjacent displacement elements 50 is reduced. At this time, the displacement elements 50 are preferably arranged in a plurality of rows along one side, and the rows are preferably aligned in the direction of the resolution of 600 dpi. This is because variations in ejection characteristics are reduced in that direction.

  Furthermore, if the polygonal shape in which the displacement element 50 is arranged has two opposite sides parallel to each other and a plurality of through holes 39 and second surface electrodes for the common electrode are arranged on the two sides, Increases stability. Furthermore, the arrangement of the displacement elements 50 is preferably square.

  The first common electrode surface electrode 71 is preferably provided in all the through holes 39 in order to confirm the conduction of the conductors in the through holes 39. However, when the first common electrode surface electrode 71 and the second common electrode surface electrode 72 are fired, the conductor contracts and the piezoelectric actuator substrate 21 may be warped. Less is better. Therefore, it should be provided only at the portion located at the end of the arrangement of the through holes 39, which has a great influence when there is no conduction. In this way, the ground at the end, which tends to weaken the ground, can be strengthened, and even if the end is warped, there is little influence on the ejection characteristics. In this case, the end portions are, for example, five portions from the end of the arrangement of the through holes 39, or a portion that is 1/10 end in the length of the first common electrode surface electrode 71. In this case, at the central portion of the arrangement of the through holes 39, the common electrode 34 and the second common electrode surface electrode 72 are electrically connected without passing through the first common electrode surface electrode 71.

  Further, in order to stabilize the ground, it is preferable to increase the density of the arrangement of the through holes 29 at the end of the arrangement of the through holes 39. Furthermore, the ground can be stabilized by disposing the through hole 39 and the second common electrode surface electrode 72 to the outside where one side of the polygonal shape on which the displacement element 50 is disposed is extended.

  Further, when the through holes 39 are arranged in two or more rows along one side of the polygonal shape where the displacement elements 50 are arranged, the positions of the through holes 39 of the piezoelectric actuator substrate 21 fluctuated due to variations in firing shrinkage. In some cases, conduction can be obtained by at least one of the columns.

  As shown in FIG. 6, the common electrode 34 and the individual electrode 35 are disposed so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is called an active portion, and the piezoelectric ceramic in that portion is polarized in the thickness direction. In the piezoelectric actuator substrate 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 21b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator substrate 21 has a so-called unimorph type configuration.

As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 35, pressure is applied to the liquid in the liquid pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 32. That is, the portion of the piezoelectric actuator substrate 21 that faces each liquid pressurizing chamber 10 corresponds to each liquid pressurizing chamber 1.
This corresponds to the individual displacement element 50 (actuator) corresponding to 0 and the liquid discharge port 8. That is, in the laminate composed of two piezoelectric ceramic layers, the displacement element 50 having a unit structure as shown in FIG. 6 is provided immediately above the liquid pressurizing chamber 10 for each liquid pressurizing chamber 10. Are formed by a diaphragm 21a, a common electrode 34, a piezoelectric ceramic layer 21b, and individual electrodes 35, and the piezoelectric actuator substrate 21 includes a plurality of displacement elements 50. In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 5 to 7 pL (picoliter).

  A large number of individual electrodes 35 are individually electrically connected to the actuator control means via contacts and wirings on the FPC so that potentials can be individually controlled.

  An example of a driving method at the time of liquid ejection of the piezoelectric actuator substrate 21 in the present embodiment will be described with respect to a driving voltage (drive signal) supplied to the individual electrode 35. When an electric field is applied to the piezoelectric ceramic layer 21b in the polarization direction by setting the individual electrode 35 to a potential different from that of the common electrode 34, the portion to which the electric field is applied functions as an active portion that is distorted by the piezoelectric effect. At this time, the piezoelectric ceramic layer 21b expands or contracts in the thickness direction, that is, the stacking direction, and tends to contract or extend in the direction perpendicular to the stacking direction, that is, the surface direction, due to the piezoelectric lateral effect. On the other hand, since the remaining piezoelectric ceramic layer 21a is an inactive layer that does not have a region sandwiched between the individual electrode 35 and the common electrode 34, it does not spontaneously deform. That is, the piezoelectric actuator substrate 21 has the piezoelectric ceramic layer 21b on the upper side (that is, the side away from the liquid pressurizing chamber 10) as a layer including the active portion and the lower side (that is, close to the liquid pressurizing chamber 10). This is a so-called unimorph type configuration in which the piezoelectric ceramic layer 21a on the side) is an inactive layer.

  In this configuration, when the individual electrode 35 is set to a predetermined positive or negative potential with respect to the common electrode 34 by the actuator controller so that the electric field and the polarization are in the same direction, a portion sandwiched between the electrodes of the piezoelectric ceramic layer 21b. (Active part) contracts in the surface direction. On the other hand, the piezoelectric ceramic layer 21a, which is an inactive layer, is not affected by an electric field, so that it does not spontaneously shrink and tries to restrict deformation of the active portion. As a result, there is a difference in strain in the polarization direction between the piezoelectric ceramic layer 21b and the piezoelectric ceramic layer 21a, and the piezoelectric ceramic layer 21b is deformed so as to protrude toward the liquid pressurizing chamber 10 (unimorph deformation). .

In an actual driving procedure in the present embodiment, the individual electrode 35 is set to a potential higher than the common electrode 34 (hereinafter referred to as a high potential) in advance, and the individual electrode 35 is temporarily set to the same potential as the common electrode 34 every time there is a discharge request. (Hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to the original shape at the timing when the individual electrode 35 becomes low potential, and the volume of the liquid pressurizing chamber 10 is compared with the initial state (the state where the potentials of both electrodes are different). To increase. At this time, a negative pressure is applied to the liquid pressurizing chamber 10 and the liquid is sucked into the liquid pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to protrude toward the liquid pressurizing chamber 10, and the volume of the liquid pressurizing chamber 10 is reduced so that the inside of the liquid pressurizing chamber 10 Becomes a positive pressure, the pressure on the liquid rises, and droplets are ejected. That is, a drive signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the manifold 5 to the liquid discharge hole 8 in the liquid pressurizing chamber 10. According to this, when the inside of the liquid pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplet can be ejected with a stronger pressure.

The liquid discharge head 2 as described above is manufactured as follows, for example. A tape composed of a piezoelectric ceramic powder and an organic composition is formed by a general tape forming method such as a roll coater method or a slit coater method, and a plurality of green sheets that become piezoelectric ceramic layers 21a and 21b after firing are produced. . An electrode paste to be the common electrode 34 is formed on a part of the green sheet by a printing method or the like. The green sheet is provided with a through hole 39 and filled with a via conductor as necessary.

  Next, each green sheet is laminated to produce a laminate, and pressure adhesion is performed. The laminated body after pressure contact was fired in a high-concentration oxygen atmosphere to produce a piezoelectric actuator body. Thereafter, the individual electrode 35 and the first common electrode surface electrode 71 were printed and baked on the surface of the piezoelectric actuator element body using Au paste. After the application, the first common electrode surface electrode 71 is inspected to confirm continuity or to measure the conductor resistance value, and the connection through the conductor in each through hole 39 is confirmed. What is necessary is just to confirm that a conductor resistance value is 3 ohms or less per through-hole, for example. Thereafter, using the Ag-Pd paste, the connection land 66 and the second common electrode surface electrode 72 are printed and baked to produce the piezoelectric actuator substrate 21.

  Next, the flow path member 4 is produced by laminating plates 22 to 31 obtained by a rolling method or the like via an adhesive layer. Holes to be the manifold 5, the individual supply flow path 6, the liquid pressurizing chamber 10, the descender, and the like are processed in the plates 22 to 31 into a predetermined shape by etching.

  These plates 22 to 31 are preferably formed of at least one metal selected from the group consisting of Fe—Cr, Fe—Ni, and WC—TiC, particularly when ink is used as a liquid. Since it is desired to be made of a material having excellent corrosion resistance against ink, Fe-Cr is more preferable.

  The piezoelectric actuator substrate 21 and the flow path member 4 can be laminated and bonded through, for example, an adhesive layer. As the adhesive layer, a known material can be used, but in order not to affect the piezoelectric actuator substrate 21 and the flow path member 4, an epoxy resin, phenol resin, polyphenylene having a thermosetting temperature of 100 to 150 ° C. It is preferable to use at least one thermosetting resin adhesive selected from the group of ether resins. By heating to the thermosetting temperature using such an adhesive layer, the piezoelectric actuator substrate 21 and the flow path member 4 can be heat-bonded.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Channel member 5 ... Manifold 5a ... Sub manifold 5b ... Manifold opening 6 ... Individual supply channel 8 ... Liquid Discharge hole 9 ... Liquid pressurization chamber group 10 ... Liquid pressurization chamber 11a, b, c, d ... Liquid pressurization chamber row 12 ... Squeeze 13 ... Liquid discharge head body 15a, b , C, d: liquid discharge hole array 21: piezoelectric actuator substrate 21a: piezoelectric ceramic layer (vibrating plate)
21b ... Piezoelectric ceramic layer 22-31 ... Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 35a ... Individual electrode body 35b ... Connection electrode 36 ... Connection land 39 ... through hole 50 ... pressurizing part (displacement element)
65 ... dummy individual electrode 66 ... dummy connection land 71 ... surface electrode for first common electrode 72 ... surface electrode for second common electrode

Claims (9)

A laminate in which a diaphragm and at least one piezoelectric ceramic layer are laminated;
A plurality of individual electrodes arranged on the main surface of the laminate on the piezoelectric ceramic layer side in a first direction and a direction different from the first direction;
A common electrode disposed inside the laminate;
A plurality of through holes penetrating the piezoelectric ceramic layer so as to be connected to the common electrode;
A piezoelectric actuator substrate for a liquid discharge head comprising a common electrode surface electrode disposed across the plurality of through holes on a main surface on the piezoelectric ceramic layer side,
The common electrode surface electrode is for a second common electrode that connects a plurality of first common electrode surface electrodes arranged for each one of the through holes and a plurality of the first common electrode surface electrodes. A piezoelectric actuator substrate for a liquid discharge head, comprising a surface electrode.   The plurality of individual electrodes are arranged in a polygonal region, and the plurality of through holes and the common electrode surface electrode are arranged along at least one side of the polygonal shape. Item 2. A piezoelectric actuator substrate for a liquid discharge head according to Item 1.   The first common electrode surface electrode is not disposed in the through-hole disposed in the central portion of the one side, and the second common electrode surface electrode is the first common electrode surface. The piezoelectric actuator substrate for a liquid discharge head according to claim 2, wherein the piezoelectric actuator substrate is connected to the common electrode without any interposition.   4. The piezoelectric actuator substrate for a liquid ejection head according to claim 2, wherein an arrangement density of the through holes at an end portion of the one side is higher than an arrangement density of the through holes at a central portion of the one side.   5. The piezoelectric actuator substrate for a liquid ejection head according to claim 2, wherein the through-hole and the second common electrode surface electrode are arranged up to a portion extending the one side.   6. The piezoelectric actuator substrate for a liquid discharge head according to claim 2, wherein the through holes are arranged in two or more rows along the one side.   The piezoelectric actuator substrate for a liquid discharge head according to claim 1, a plurality of discharge holes, and a plurality of pressurizing chambers respectively connected to the plurality of discharge holes, and the diaphragm Covers the plurality of pressurizing chambers, and has a flow path member joined to the piezoelectric actuator substrate for the liquid discharge head so that the plurality of individual electrode bodies and the plurality of pressurizing chambers overlap each other. A liquid discharge head.   The liquid ejection head according to claim 7, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the piezoelectric actuator substrate and the transport unit. Recording device. A laminate in which a diaphragm and at least one piezoelectric ceramic layer are laminated;
A plurality of individual electrodes arranged on the main surface of the laminate on the piezoelectric ceramic layer side in a first direction and a direction different from the first direction;
A common electrode disposed inside the laminate;
A plurality of through holes penetrating the piezoelectric ceramic layer so as to be connected to the common electrode;
Producing a piezoelectric actuator element body comprising a plurality of first common electrode surface electrodes arranged for each one of the through holes;
An inspection step that the plurality of first common electrode surface electrodes of the piezoelectric actuator element body are electrically connected to the common electrode;
Forming a second common electrode surface electrode so as to connect the plurality of first common electrode surface electrodes of the piezoelectric actuator element body that has undergone the inspection process. Method.

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