JP2014087977A - Piezoelectric actuator substrate, liquid ejection head using the same, and recording apparatus - Google Patents

Abstract

A piezoelectric actuator substrate with good connectability to via-hole conductors, a liquid discharge head using the same, and a printing apparatus are provided.
A piezoelectric actuator substrate includes a diaphragm, a common electrode, a piezoelectric ceramic layer, and surface electrodes including a plurality of individual electrodes 25 and common surface electrodes 228, 328, and 428, which are stacked in this order. A piezoelectric actuator substrate provided with via holes penetrating the ceramic layer and via hole conductors 228a, 328a, 428a formed so that a part of the common surface electrode enters the via hole, and the plurality of individual electrodes 25 are Are arranged so as to form individual electrode rows 35 that are long in one direction and aligned in a direction not parallel to one direction, and the via-hole conductor extends the individual electrode belonging to the nearest individual electrode row in one direction. Between the areas.
[Selection] Figure 6

Description

  The present invention relates to a piezoelectric actuator substrate including a piezoelectric element, a liquid discharge head that discharges droplets using the piezoelectric actuator substrate, and a recording apparatus.

  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, such a liquid ejection head has a serial type that performs recording while moving the liquid ejection head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and is long in the main scanning direction. There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with the liquid discharge head 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.

  Therefore, a long liquid discharge head in one direction is provided so as to cover the pressure chamber and a flow path member having discharge holes that connect the manifold and the manifold through a plurality of pressure chambers, respectively, as a common flow path. In addition, a structure in which a piezoelectric actuator substrate having a plurality of displacement elements is laminated is known (for example, see Patent Document 1). The piezoelectric actuator substrate used in this liquid discharge head includes a common electrode, individual electrodes, and a piezoelectric ceramic layer sandwiched between them. Further, in this liquid discharge head, the pressurizing chambers connected to the plurality of discharge holes are arranged in a matrix, and the displacement element of the piezoelectric actuator substrate provided so as to cover it is displaced, so that each discharge hole Ink is ejected and printing is possible at a resolution of 600 dpi in the main scanning direction.

JP 2003-305852 A

  When manufacturing the piezoelectric actuator substrate described in Patent Document 1, it is conceivable to provide a via-hole conductor that penetrates the piezoelectric ceramic layer in order to electrically connect the common electrode inside the piezoelectric actuator substrate to the outside. In this case, the process can be simplified if the via hole conductor is formed by inserting a common surface conductor formed on the surface of the piezoelectric actuator substrate into the via hole penetrating the piezoelectric ceramic layer. In such a case, it is preferable to form the common surface electrode and the individual electrode simultaneously by screen printing and firing.

When a common surface conductor is inserted into a via hole to form a via hole conductor, even if the common surface conductor is not filled in the entire inside of the via hole, in order to ensure the connection, normal printing that is performed on the surface of the piezoelectric actuator substrate is performed. In comparison, the amount of paste required for printing increases. The amount of paste supplied through the screen plate making is limited to the amount of paste accumulated in the traveling direction of the squeegee at that site. When printing individual electrodes that are long in one direction, the amount of paste accumulated in the squeegee of that part is small, so there are not enough via-hole conductors to be printed, and connection may be insufficient. there were.
was there.

  Accordingly, it is an object of the present invention to provide a piezoelectric actuator substrate with good via hole conductor connectivity, a liquid discharge head using the same, and a printing apparatus.

  In the piezoelectric actuator substrate of the present invention, a diaphragm, a common electrode, a piezoelectric ceramic layer, and a surface electrode including a plurality of individual electrodes and a common surface electrode are laminated in this order, and penetrate through the piezoelectric ceramic layer. A piezoelectric actuator substrate comprising a via hole conductor, and a via hole conductor electrically connecting the common surface electrode and the common electrode, wherein a part of the common surface electrode is formed in the via hole. The plurality of individual electrodes are arranged to form one or more individual electrode rows, each of which is long in one direction and arranged in a direction not parallel to the one direction, and the via-hole conductor is A plurality of the individual electrodes belonging to the nearest individual electrode row that is the individual electrode row closest to the via-hole conductor are respectively arranged in the one direction. Characterized in that it is arranged between the poured was region.

  The liquid discharge head according to the present invention includes a flow path member including a plurality of discharge holes and a plurality of pressurizing chambers connected to the discharge holes, and the piezoelectric device according to claim 1. The actuator substrate is laminated so that the positions of the plurality of individual electrodes and the plurality of pressurizing chambers are aligned.

  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.

  According to the present invention, the connectivity of via-hole conductors can be improved.

1 is a schematic configuration diagram of a color inkjet printer that is a recording apparatus including a liquid ejection head according to an embodiment of the present invention. FIG. 2 is a plan view of a 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. (A) is the longitudinal cross-sectional view along the VV line of FIG. 3, (b) is sectional drawing to which a part of vertical cut along the XX line of FIG. 3 was expanded. (A)-(c) is an enlarged plan view of the piezoelectric actuator board | substrate of other embodiment of this invention.

  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 the liquid discharge heads 2 fixed to the printer 1 have an elongated shape extending in the direction from the front to the back in FIG. ing. 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 liquid discharge head 2 has a head body 2a at the lower end. The lower surface of the head body 2a is a discharge hole surface 4-1, in which a large number of discharge holes for discharging liquid are provided.

  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 ejection holes 8 of each liquid ejection head 2 are open to the surface of the liquid ejection holes, and are in one direction (a direction parallel to the printing paper P and perpendicular to the conveyance direction of the printing paper P, and the longitudinal direction of the liquid ejection head 2. (Direction) at equal intervals, it is possible to print without gaps in one direction. The colors of the liquid ejected from each liquid ejection head 2 are, for example, magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid discharge head 2 is arranged with a slight gap between the lower surface of the liquid discharge head main 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 2 a 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 liquid discharge head 2 of the present invention will be described. FIG. 2 is a plan view of the head main body 2a. FIG. 3 is an enlarged view of a region surrounded by a one-dot chain line in FIG. FIG. 4 is an enlarged view of a region surrounded by a one-dot chain line in FIG. 2, and is a diagram in which a part of the flow paths different from FIG. In FIGS. 3 and 4, for easy understanding of the drawings, the squeezing 6, the discharge hole 8, the pressurizing chamber 10, and the like to be drawn by broken lines below the piezoelectric actuator substrate 21 are drawn by solid lines. 5A is a longitudinal sectional view taken along line VV in FIG. 3, and FIG. 5B is an enlarged sectional view of a part of the longitudinal section taken along line XX in FIG.

  The liquid ejection head 2 includes a reservoir and a metal casing in addition to the head body 2a. Also. The head body 2 a includes a flow path member 4 and a piezoelectric actuator substrate 21 in which a displacement element (pressurizing unit) 30 is formed.

The flow path member 4 constituting the head body 2a includes a manifold 5, a plurality of pressurizing chambers 10 connected to the manifold 5, and a plurality of discharge holes 8 connected to the plurality of pressurizing chambers 10, respectively. The pressurizing chamber 10 opens to the upper surface of the flow path member 4, and the upper surface of the flow path member 4 is the pressurizing chamber surface 4.
-2. In addition, an opening 5a connected to the manifold 5 is provided on the upper surface of the flow path member 4, and liquid is supplied from the opening 5a.

  A piezoelectric actuator substrate 21 including a displacement element 30 is bonded to the upper surface of the flow path member 4, and each displacement element 30 is provided so as to be positioned on the pressurizing chamber 10. The piezoelectric actuator substrate 21 is connected to a signal transmission unit 92 such as an FPC (Flexible Printed Circuit) which is a wiring substrate for supplying a signal to each displacement element 30. In FIG. 2, the outline of the vicinity of the signal transmission unit 92 connected to the piezoelectric actuator substrate 21 is indicated by a dotted line so that the state where the two signal transmission units 92 are connected to the piezoelectric actuator substrate 21 can be seen. In the region of the signal transmission portion 92 facing the piezoelectric actuator substrate 21, a large number of wires are arranged so as to extend along the short direction of the head body 2a, and are not shown on the left and right of FIG. It is connected to the part. The signal sent from the control unit 100 passes through another circuit board or the like as necessary, is transmitted to the signal transmission unit 92, and is supplied to the displacement element 30. The piezoelectric actuator substrate 21 side of the wiring of the signal transmission unit 92 is an electrode electrically connected to the piezoelectric actuator substrate 21, and this electrode is arranged in a rectangular shape at the end of the signal transmission unit 92. ing. The two signal transmission portions 92 are connected so that their ends come to the center portion in the short direction of the piezoelectric actuator substrate 21. The two signal transmission portions 92 extend from the central portion toward the long side of the piezoelectric actuator substrate 21.

  In addition, a driver IC is mounted on the signal transmission unit 92. The driver IC is mounted so as to be pressed against the metal casing, and the heat of the driver IC is transmitted to the metal casing and dissipated to the outside. A drive signal for driving the displacement element 30 on the piezoelectric actuator substrate 21 is generated in the driver IC. A signal for controlling the generation of the drive signal is generated by the control unit 100 and input from the end of the signal transmission unit 92 opposite to the side connected to the piezoelectric actuator substrate 21. A circuit board or the like is provided in the liquid ejection head 2 between the control unit 100 and the signal transmission unit 92 as necessary.

  The head body 2 a has one piezoelectric actuator substrate 21 including a flat plate-like flow path member 4 and a displacement element 30 connected on the flow path member 4. The planar shape of the piezoelectric actuator substrate 21 is rectangular, and is arranged on the upper surface of the flow path member 4 so that the long side of the rectangle is along the longitudinal direction of the flow path member 4.

  Two manifolds 5 are formed inside the flow path member 4. The manifold 5 has an elongated shape that extends from one end side in the longitudinal direction of the flow path member 4 to the other end side, and the manifold opening 5a that opens to the upper surface of the flow path member 4 at both ends. Is formed. By supplying the liquid from both ends of the manifold 5 to the flow path member 4, it is possible to prevent the liquid from being insufficiently supplied. Further, as compared with the case where the liquid is supplied from one end of the manifold 5, the difference in pressure loss caused when the liquid flows through the manifold 5 can be reduced to about half, so that the variation in the liquid discharge characteristics can be reduced.

  In the manifold 5, at least a central portion in the length direction, which is a region connected to the pressurizing chamber 10, is partitioned by a partition wall 15 provided at an interval in the width direction. The partition wall 15 has the same height as the manifold 5 in the central portion in the length direction, which is a region connected to the pressurizing chamber 10, and completely separates the manifold 5 into a plurality of sub-manifolds 5b. By doing so, it is possible to provide the discharge hole 8 and a descender connected from the discharge hole 8 to the pressurizing chamber 10 so as to overlap with the partition wall 15 when seen in a plan view.

In FIG. 2, the whole of the manifold 5 excluding both ends is partitioned by a partition wall 15. In addition to this, one of the both end portions other than one end portion may be partitioned by the partition wall 15. In addition, only the vicinity of the opening 5a opened on the upper surface of the flow path member 4 is not partitioned, and a partition wall may be provided in the depth direction of the flow path member 4 from the opening 5a. In any case, it is preferable that both ends of the manifold 5 are not partitioned by the partition wall 15 because the flow resistance is reduced and the supply amount of the liquid can be increased because there is a portion that is not partitioned.

  The portion of the manifold 5 divided into a plurality of parts may be referred to as a sub-manifold 5b. In this embodiment, two manifolds 5 are provided independently, and openings 5a are provided at both ends. One manifold 5 is provided with seven partition walls 15 and divided into eight sub-manifolds 5b. The width of the sub-manifold 5b is larger than the width of the partition wall 15, so that a large amount of liquid can flow through the sub-manifold 5b. In addition, the length of the seven partition walls 15 becomes longer as they are closer to the center in the width direction. At both ends of the manifold 5, the ends of the partition walls 15 are closer to the ends of the manifold 5 as the partition walls 15 are closer to the center in the width direction. It ’s close. As a result, the flow resistance generated by the outer wall of the manifold 5 and the flow resistance generated by the partition wall 15 are balanced, and the individual supply flow that is the portion connected to the pressurizing chamber 10 in each sub-manifold 5b. The pressure difference of the liquid at the end of the region where the channel 14 is formed can be reduced. Since the pressure difference in the individual supply channel 14 leads to a pressure difference applied to the liquid in the pressurizing chamber 10, the discharge variation can be reduced if the pressure difference in the individual supply channel 14 is reduced.

  The flow path member 4 is formed by two-dimensionally expanding a plurality of pressurizing chambers 10. The pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The pressurizing chamber 10 is connected to one sub-manifold 5b through an individual supply channel 14. Along with one sub-manifold 5b, pressurizing chamber rows 11 that are columns of pressurizing chambers 10 connected to the sub-manifold 5b are provided in two columns, one on each side of the sub-manifold 5b. Yes. Accordingly, 16 columns of pressurizing chambers 11 are provided for one manifold 5, and 32 columns of pressurizing chamber rows 11 are provided in the entire head body 2a. The intervals in the longitudinal direction of the pressurizing chambers 10 in the respective pressurizing chamber rows 11 are the same, for example, 37.5 dpi.

  A dummy pressurizing chamber 16 is provided at the end of each pressurizing chamber row 11. The dummy pressurizing chamber 16 is connected to the manifold 5 but is not connected to the discharge hole 8. A dummy pressurizing chamber row in which dummy pressurizing chambers 16 are arranged in a straight line is provided outside the 32 columns of pressurizing chamber rows 11. The dummy pressurizing chamber 16 is not connected to either the manifold 5 or the discharge hole 8. By these dummy pressurizing chambers, the structure (rigidity) around the pressurizing chamber 10 that is one inward from the end is close to the structure (rigidity) of the other pressurizing chambers 10, thereby reducing the difference in liquid ejection characteristics. it can. It should be noted that the influence of the difference in the surrounding structure is large because the pressurizing chambers 10 adjacent to each other in the lengthwise direction of the pressurizing chamber 10 are close to each other. Is provided. Since the influence in the width direction is relatively small, it is provided only on the side closer to the end of the head main body 21a. Thereby, the width | variety of the head main body 21a can be made small.

The pressurizing chambers 10 connected to one manifold 5 are arranged at substantially equal intervals on the rows and on the columns along the row direction which is the longitudinal direction of the liquid discharge head 2 and the column direction which is the short direction. Has been placed. The row direction is the short direction (the shorter of the diagonal lines) of the rhombic pressurizing chamber 10. The rhombus shape of the pressurizing chamber 10 may have a side length different by about 10%. In addition, the direction of the diagonal line connecting the obtuse angle portions and the row direction have an angle of about 10 degrees or less because the pressurizing chamber 10 is arranged in a state where it is rotated in a plane or the length of the side is different. It may be. The column direction is the longitudinal direction of the rhombic pressurizing chamber 10 (the longer one of the diagonal lines). The direction of the diagonal line connecting the acute angle portions and the column direction are at an angle of about 10 degrees or less because the pressurizing chamber 10 is arranged in a state of being rotated in a plane or the lengths of the sides are different. May be. That is, the angle formed by the rhombic diagonal lines of the pressurizing chamber 10 with respect to the row direction and the column direction is small. By arranging the pressurizing chambers 10 in a lattice shape and arranging the rhombic pressurizing chambers 10 having such angles, crosstalk can be reduced. This is because the corners face each other in both the row direction and the column direction with respect to one pressurizing chamber 10, so that the flow path member is more than the case where the sides face each other. This is because vibration is difficult to be transmitted through 4. Here, by making the obtuse angle portions 10b face each other in the longitudinal direction, the density of the pressurizing chambers 10 in the longitudinal direction can be increased, whereby the density of the discharge holes 8 in the longitudinal direction can be increased. The liquid ejection head 2 with a resolution can be obtained. If the intervals between the pressurizing chambers 10 on the rows and columns are equal, the crosstalk can be reduced by eliminating the narrower intervals than others, but the intervals may differ by about ± 20%.

  When the pressurizing chambers 10 are arranged in a grid pattern and the piezoelectric actuator substrate 21 is formed in a rectangular shape having outer sides along rows and columns, the piezoelectric actuator substrate 21 is formed on the pressurizing chamber 10 from the outer sides. Since the individual electrodes 25 are arranged at equal distances, the piezoelectric actuator substrate 21 can be hardly deformed when the individual electrodes 25 are formed. When the piezoelectric actuator substrate 21 and the flow path member 4 are joined, if this deformation is large, stress may be applied to the displacement element 30 near the outer side, resulting in variations in displacement characteristics. However, by reducing the deformation, The variation can be reduced. In addition, since the dummy pressurizing chamber row of the dummy pressurizing chamber 16 is provided outside the pressurizing chamber row 11 closest to the outer side, the influence of deformation can be made less susceptible. The pressurizing chambers 10 belonging to the pressurizing chamber row 11 are arranged at equal intervals, and the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals. The pressurizing chamber rows 11 are arranged at equal intervals in the short direction, and the columns of the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals in the short direction. Thereby, it is possible to eliminate a portion where the influence of the crosstalk becomes particularly large.

  When the flow path member 4 is viewed in plan, the pressurizing chamber 10 belonging to one pressurizing chamber row 11 is overlapped with the pressurizing chamber 10 belonging to the adjacent pressurizing chamber row 11 in the longitudinal direction of the liquid ejection head 2. By arranging so as not to become crosstalk, crosstalk can be suppressed. On the other hand, when the distance between the pressurizing chamber rows 11 is increased, the width of the liquid discharge head 2 is increased. The influence of the relative position accuracy of the liquid discharge head 2 on the printing result is increased. Therefore, by making the width of the partition wall 15 smaller than that of the sub-manifold 5b, the influence of the accuracy on the printing result can be reduced.

  The pressurizing chambers 10 connected to one sub-manifold 5 b constitute two pressurizing chamber rows 11, and the discharge holes 8 connected to the pressurizing chambers 10 belonging to one pressurizing chamber row 11 are One discharge hole row 9 is configured. The discharge holes 8 connected to the pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 open to different sides of the sub-manifold 5b. In FIG. 4, the partition wall 15 is provided with two rows of discharge hole rows 9, but the discharge holes 8 belonging to the respective discharge hole rows 9 are connected to the sub-manifold 5 b on the side close to the discharge holes 8 in the pressurizing chamber 10. Are connected through. When the discharge hole 8 connected to the adjacent sub-manifold 5b via the pressurizing chamber row 11 and the liquid discharge head 2 are arranged so as not to overlap in the longitudinal direction, the pressurizing chamber 10 and the discharge hole 8 are connected. Since crosstalk between the flow paths can be suppressed, the crosstalk can be further reduced. If the entire flow path connecting the pressurizing chamber 10 and the discharge hole 8 is arranged so as not to overlap in the longitudinal direction of the liquid discharge head 2, the crosstalk can be further reduced.

In addition, the width of the liquid discharge head 2 can be reduced by arranging the pressurizing chamber 10 and the sub-manifold 5b so as to overlap each other in plan view. When the ratio of the overlapping area to the area of the pressurizing chamber 10 is 80% or more, and further 90% or more, the width of the liquid discharge head 2 can be further reduced. Further, the bottom surface of the pressurizing chamber 10 where the pressurizing chamber 10 and the sub-manifold 5b overlap is less rigid than the case where the pressurizing chamber 10 and the sub-manifold 5b do not overlap. There is a risk of variation. By making the ratio of the area of the pressurizing chamber 10 overlapping the sub-manifold 5b to the area of the entire pressurizing chamber 10 substantially the same in each pressurizing chamber 10, the rigidity of the bottom surface constituting the pressurizing chamber 10 is increased. Variations in ejection characteristics due to changes can be reduced. Here, “substantially the same” means that the difference in area ratio is 10% or less, particularly 5% or less.

  A plurality of pressurizing chambers are formed by a plurality of pressurizing chambers 10 connected to one manifold 5. Since there are two manifolds 5, there are two pressurizing chamber groups. The arrangement of the pressurizing chambers 10 related to ejection in each pressurizing chamber group is the same, and is arranged to be translated in the lateral direction. These pressurizing chambers 10 are arranged over almost the entire surface although there are portions where the gaps between the pressurizing chamber groups are slightly wide in the region facing the piezoelectric actuator substrate 21 on the upper surface of the flow path member 4. . That is, the pressurizing chamber group formed by these pressurizing chambers 10 occupies an area having almost the same size and shape as the piezoelectric actuator substrate 21. Further, the opening of each pressurizing chamber 10 is closed by bonding the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  A descender connected to the discharge hole 8 opened in the discharge hole surface 4-1 on the lower surface of the flow path member 4 extends from a corner portion of the pressurizing chamber 10 facing the corner portion where the individual supply flow path 14 is connected. ing. The descender extends in a direction away from the pressurizing chamber 10 in plan view. More specifically, the pressurizing chamber 10 extends away from the direction along the long diagonal line while being shifted to the left and right with respect to that direction. As a result, the discharge chambers 8 can be arranged at intervals of 1200 dpi as a whole, while the pressurization chambers 10 are arranged in a lattice pattern in which the intervals within the pressurization chamber rows 11 are 37.5 dpi.

  In other words, when the discharge holes 8 are projected so as to be orthogonal to the virtual straight line parallel to the longitudinal direction of the flow path member 4, each manifold 5 is within the range of R of the virtual straight line shown in FIG. That is, 16 discharge holes 8 connected to, and a total of 32 discharge holes 8 are equally spaced by 1200 dpi. Thus, by supplying the same color ink to all the manifolds 5, an image can be formed with a resolution of 1200 dpi in the longitudinal direction as a whole. Further, one discharge hole 8 connected to one manifold 5 is equally spaced at 600 dpi within the range of R of the imaginary straight line. As a result, by supplying different colors of ink to the respective manifolds 5, it is possible to form two-color images with a resolution of 600 dpi in the longitudinal direction as a whole. In this case, if two liquid ejection heads 2 are used, an image of four colors can be formed at a resolution of 600 dpi, and printing accuracy is higher and printing settings are easier than using a liquid ejection head capable of printing at 600 dpi. Can be.

  Furthermore, a reservoir may be joined to the flow path member 4 in the liquid ejection head 2 so as to stabilize the liquid supply from the opening 5a of the manifold. The reservoir is provided with a flow path that branches the liquid supplied from the outside and is connected to the two openings 5a, so that the liquid can be stably supplied to the two openings. By making the flow path lengths after branching substantially equal, temperature fluctuations and pressure fluctuations of the liquid supplied from the outside are transmitted to the openings 5a at both ends of the manifold 5 with a small time difference. Variations in droplet ejection characteristics can be further reduced. By providing a damper in the reservoir, the liquid supply can be further stabilized. Further, a filter may be provided so as to prevent foreign matters in the liquid from moving toward the flow path member 4. Furthermore, a heater may be provided so as to stabilize the temperature of the liquid toward the flow path member 4.

Individual electrodes 25 are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. The individual electrode 25 includes an individual electrode main body 25a that is slightly smaller than the pressurizing chamber 10 and has a shape substantially similar to the pressurizing chamber 10, and an extraction electrode 25b that is extracted from the individual electrode main body 25a. In the same manner as the pressurizing chamber 10, the individual electrode 25 constitutes an individual electrode row and an individual electrode group. One end of the extraction electrode 25b is connected to the individual electrode main body 25a, and the other end passes through the acute angle portion 10a of the pressurization chamber 10, and outside the pressurization chamber 10, two acute angle portions of the pressurization chamber 10 are provided. 10a is drawn to a region that does not overlap with the extended row of diagonal lines connecting 10a.

  A common surface electrode 28 is formed on the upper surface of the piezoelectric actuator substrate 21. A part of the common surface electrode 28 is electrically connected to the common electrode 24 through a via-hole conductor 28a that enters the via-hole 21ba formed in the piezoelectric ceramic layer 21b. The common surface electrodes 28 are formed in two rows at the center in the short direction of the piezoelectric actuator substrate 21 along the longitudinal direction which is the row direction. Further, one row is formed near the end in the longitudinal direction along the short direction which is the row direction. Since the common surface electrode 28 is arranged along the individual electrode row 35 in the row direction, the difference in propagation time until the drive signal is transmitted to each displacement element 30 due to the position in the row direction is reduced. The decrease in printing accuracy can be reduced. This influence increases when driving at a high frequency of 10 kHz or higher, and further increases when driving at a frequency of 20 kHz or higher, particularly 40 kHz or higher. Therefore, the arrangement of the common surface electrode 28 is important when driving at a high frequency. . Although the illustrated common surface electrode 28 is formed intermittently on a straight line, it may be formed continuously on a straight line. In order to reduce the difference in propagation time, a plurality of via-hole conductors 28 a are preferably arranged along the individual electrode rows 35.

  The piezoelectric actuator substrate 21 is formed by laminating and firing the piezoelectric ceramic layer 21a having the via hole 21ba, the common electrode 24, and the piezoelectric ceramic layer 21b as will be described later, and then forming the individual electrode 25 and the common surface electrode 28 in the same process. Preferably, a part of the common surface electrode 28 enters the via hole 21ba to form a via hole conductor 28a, and the common surface electrode 28 and the common electrode are electrically connected. The positional variation between the individual electrode 25 and the pressurizing chamber 10 greatly affects the ejection characteristics, and if the individual electrode 25 is formed and then fired, the piezoelectric actuator substrate 21 may be warped. When the substrate 21 is joined to the flow path member 4, stress is applied to the piezoelectric actuator substrate 21, and the displacement may vary due to the influence. Therefore, the individual electrode 25 is formed after firing. Similarly, the common surface electrode 28 is likely to be warped, and the formation with the individual electrode 25 increases the positional accuracy and simplifies the process. It is formed in the same process.

  Such positional variation of via holes due to firing shrinkage that may occur when firing the piezoelectric actuator substrate 21 mainly occurs in the longitudinal direction of the piezoelectric actuator substrate 21, and therefore the manifold 5 having an even number of common surface electrodes 28. In the center, in other words, it is provided in the center of the piezoelectric actuator substrate 21 in the short direction, and the common surface electrode 28 is long in the longitudinal direction of the piezoelectric actuator substrate 21, so that it is common with the via hole. It can be prevented that the surface electrode 28 is not electrically connected due to the positional shift.

  Two signal transmission portions 92 are arranged and bonded to the piezoelectric actuator substrate 21 from the two long sides of the piezoelectric actuator substrate 21 toward the center. At this time, the connection is facilitated by forming the connection electrode 26 and the common electrode connection electrode on the extraction electrode 25b and the common surface electrode 28 of the piezoelectric actuator substrate 21a, respectively, and connecting them. At that time, if the area of the common surface electrode 28 and the common electrode connection electrode is made larger than the area of the connection electrode 26, the end of the signal transmission unit 92 (the front end and the longitudinal end of the piezoelectric actuator substrate 21). Since the connection can be made stronger by the connection on the common surface electrode 28, the signal transmission part 92 can be made difficult to peel off from the end.

Further, the discharge hole 8 is arranged at a position avoiding the area facing the manifold 5 arranged on the lower surface side of the flow path member 4. Further, the discharge hole 8 is disposed in a region facing the piezoelectric actuator substrate 21 on the lower surface side of the flow path member 4. These discharge holes 8 occupy a region having almost the same size and shape as the piezoelectric actuator substrate 21 as a group, and the displacement elements 30 of the corresponding piezoelectric actuator substrate 21 are displaced to displace the discharge holes 8 from the discharge holes 8. Droplets can be ejected.

  The flow path member 4 included in the head main body 2a has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 4a, a base plate 4b, an aperture plate 4c, a supply plate 4d, manifold plates 4e to j, a cover plate 4k, and a nozzle plate 4l in order from the upper surface of the flow path member 4. A number of holes are formed in these plates. Since the thickness of each plate is about 10 to 300 μm, the formation accuracy of the holes to be formed can be increased. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 12 and the manifold 5. In the head main body 2a, the pressurizing chamber 10 is on the upper surface of the flow path member 4, the manifold 5 is on the inner lower surface side, the discharge holes 8 are on the lower surface, and the parts constituting the individual flow path 12 are close to each other in different positions. The manifold 5 and the discharge hole 8 are connected via the pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. The first is the pressurizing chamber 10 formed in the cavity plate 4a. Second, there is a communication hole that constitutes an individual supply channel 14 that is connected from one end of the pressurizing chamber 10 to the manifold 5. This communication hole is formed in each plate from the base plate 4b (specifically, the inlet of the pressurizing chamber 10) to the supply plate 4c (specifically, the outlet of the manifold 5). The individual supply flow path 14 includes a squeeze 6 that is formed in the aperture plate 4c and is a portion where the cross-sectional area of the flow path is small.

  Third, there is a communication hole constituting a flow path communicating from the other end of the pressurizing chamber 10 to the discharge hole 8, and this communication hole is referred to as a descender (partial flow path) in the following description. The descender is formed on each plate from the base plate 4b (specifically, the outlet of the pressurizing chamber 10) to the nozzle plate 4l (specifically, the discharge hole 8). The hole of the nozzle plate 41 is opened as a discharge hole 8 having a diameter of 10 to 40 μm, for example, which is open to the outside of the flow path member 4, and the diameter increases toward the inside. . Fourthly, communication holes constituting the manifold 5. The communication holes are formed in the manifold plates 4e to 4j. Holes are formed in the manifold plates 4e to 4j so that the partition walls 15 remain so as to constitute the sub-manifold 5b. The partition 15 in each manifold plate 4e-j cannot be held when the entire portion to be the manifold 5 is made a hole, so the partition 15 is connected to the outer periphery of each manifold plate 4e-j with a half-etched tab. To be.

  The first to fourth communication holes are connected to each other to form an individual flow path 12 from the liquid inflow port (outlet of the manifold 5) to the discharge hole 8 from the manifold 5. The liquid supplied to the manifold 5 is discharged from the discharge hole 8 through the following path. First, from the manifold 5, it enters the individual supply flow path 14 and reaches one end of the throttle 6. Next, it proceeds horizontally along the extending direction of the restriction 6 and reaches the other end of the restriction 6. From there, it reaches one end of the pressurizing chamber 10 upward. Furthermore, it progresses horizontally along the extending direction of the pressurizing chamber 10 and reaches the other end of the pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the discharge hole 8 opened in the lower surface.

The piezoelectric actuator substrate 21 has a laminated structure composed of two piezoelectric ceramic layers 21a and 21b which are piezoelectric bodies. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The thickness from the lower surface of the piezoelectric ceramic layer 21a of the piezoelectric actuator substrate 21 to the upper surface of the piezoelectric ceramic layer 21b is about 40 μm. Both of the piezoelectric ceramic layers 21 a and 21 b extend so as to straddle the plurality of pressure chambers 10. These piezoelectric ceramic layers 21a and 21b are made of, for example, a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator substrate 21 includes a common electrode 24 made of a metal material such as Ag—Pd and an individual electrode 25 made of a metal material such as Au. As described above, the individual electrode 25 includes the individual electrode main body 25a disposed at the position facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21, and the extraction electrode 25b extracted therefrom. A connection electrode 26 is formed at a portion of one end of the extraction electrode 25 b that is extracted outside the region facing the pressurizing chamber 10. The connection electrode 26 is made of, for example, silver-palladium containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 26 is electrically joined to an electrode provided in the signal transmission unit 92. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 25 through the signal transmission unit 92. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 24 is formed over almost the entire surface in the region between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 24 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 21. The thickness of the common electrode 24 is about 2 μm. The common electrode 24 is connected to the common surface electrode 28 formed on the piezoelectric ceramic layer 21b so as to avoid the electrode group composed of the individual electrodes 25, via the via hole conductor 28a in the via hole 21ba formed in the piezoelectric ceramic layer 21b. They are connected, grounded, and held at ground potential. The common surface electrode 28 is connected to another electrode on the signal transmission unit 92 in the same manner as the multiple individual electrodes 25.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 25, the volume of the pressurizing chamber 10 corresponding to the individual electrode 25 changes, and the liquid in the pressurizing chamber 10 is pressurized. Is added. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 12. That is, the portion of the piezoelectric actuator substrate 21 that faces each pressurizing chamber 10 corresponds to the individual displacement element 30 corresponding to each pressurizing chamber 10 and the liquid discharge port 8. That is, in the laminate composed of the two piezoelectric ceramic layers 21a and 21b, the displacement element 30 which is a piezoelectric actuator substrate having a unit structure as shown in FIG. The piezoelectric actuator substrate 21 includes a plurality of displacement elements 30 serving as pressurizing units. The diaphragm 21a is located directly above the pressurizing chamber 10 and is formed by a common electrode 24, a piezoelectric ceramic layer 21b, and individual electrodes 25. ing. In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 1.5 to 4.5 pl (picoliter).

  The large number of individual electrodes 25 are individually electrically connected to the control unit 100 via the signal transmission unit 92 and wiring so that the potential can be individually controlled. When an electric field is applied to the piezoelectric ceramic layer 21b in the polarization direction by setting the individual electrode 25 to a potential different from that of the common electrode 24, a portion to which the electric field is applied functions as an active portion that is distorted by the piezoelectric effect. In this configuration, when the control unit 100 sets the individual electrode 25 to a predetermined positive or negative potential with respect to the common electrode 24 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 pressurizing chamber 10 (unimorph deformation).

In an actual driving procedure in the present embodiment, the individual electrode 25 is set to a potential higher than the common electrode 24 (hereinafter referred to as a high potential) in advance, and the individual electrode 25 is temporarily set to the same potential as the common electrode 24 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. Thereby, at the timing when the individual electrode 25 becomes a low potential, the piezoelectric ceramic layer 21a.
, 21b returns to the original shape, and the volume of the pressurizing chamber 10 increases compared to the initial state (a state where the potentials of the two electrodes are different). At this time, a negative pressure is applied to the pressurizing chamber 10 and the liquid is sucked into the pressurizing chamber 10 from the manifold 5 side. After that, at the timing when the individual electrode 25 is set to a high potential again, the piezoelectric ceramic layers 21 a and 21 b are deformed so as to protrude toward the pressurizing chamber 10. The pressure becomes positive and the pressure on the liquid rises, and droplets are ejected. That is, in order to discharge the droplet, a drive signal including a pulse based on a high potential is supplied to the individual electrode 25. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the orifice 6 to the discharge hole 8. According to this, when the inside of the pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplets can be discharged at a stronger pressure.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the ejection holes 8, that is, the droplet amount (volume) adjusted by the number of droplet ejections. For this reason, the number of droplet discharges corresponding to the designated gradation expression is continuously performed from the discharge holes 8 corresponding to the designated dot region. In general, when liquid ejection is performed continuously, it is preferable that the interval between pulses supplied to eject liquid droplets is AL. As a result, the period of the residual pressure wave of the pressure generated when discharging the previously discharged liquid droplet coincides with the pressure wave of the pressure generated when discharging the liquid droplet discharged later, and these are superimposed. Thus, the pressure for discharging the droplet can be amplified. In this case, it is considered that the speed of the liquid droplets ejected later increases, but this is preferable because the landing points of a plurality of liquid droplets are close.

  When the piezoelectric actuator substrate 21 as described above is manufactured, the via electrode 21ba is formed including the piezoelectric ceramic layers 21a and 21b and the common electrode 24 in order to increase the positional accuracy of the individual electrodes 25 and simplify the process. After firing the piezoelectric actuator body, the individual electrodes 25 and the common surface electrode 28 are printed by screen printing, and a part of the paste of the common surface electrode 28 enters the via hole 21ba to contact the common electrode 24. Then, the individual electrode 25 and the common surface electrode 28 are preferably fired.

  In order to print the shape of the individual electrode 25 with high accuracy, the squeegee is preferably moved along the longitudinal direction of the individual electric electrode 25 for printing. The individual electrodes 25 are arranged in the short direction to form individual electrode rows 35, and the common surface electrodes 28 are arranged along the individual electrode rows 35, so that the common surface electrodes 28 are located at the center of the piezoelectric actuator substrate 21. If the electrodes are disposed at both ends, the common surface electrode 28 is printed after the large number of individual electrodes 25 are printed.

  The via hole 21ba does not need to be entirely filled with the via hole conductor 38a. However, in order to increase the connection reliability, more paste must be supplied than when printing only on a normal surface. The direct source of the paste is the paste on the screen, and more specifically, the paste that accumulates on the squeegee that passes over it when printed. If the pattern used for printing differs in the use of paste depending on the location, the paste accumulated in the squeegee moves in a direction perpendicular to the direction of the squeegee as printing progresses, and the amount of paste accumulated in the squeegee varies depending on the position. Become smaller. However, since this action is not so responsive, the amount of paste accumulated in the squeegee at the portion where the printing pattern with a large amount of paste used has been printed is small, and the via-hole conductor 28a is printed. May be inadequate.

Specifically, in a region having a pattern (A1 in FIG. 6) continuously in the longitudinal direction of the individual electrode 25 (more specifically, the individual electrode body 25a), the amount of paste used is large. If via hole conductor 28a is printed after printing, the possibility of connection failure increases. Therefore, the via-hole conductors 28a extend in the longitudinal direction from the individual electrode rows 35 that are continuously formed in the longitudinal direction of the plurality of individual electrodes 25 belonging to the closest individual electrode row closest to the via-hole conductor 28a. It is preferable to arrange in the area A2 between the areas A1. If a part of the via-hole conductor 28a is arranged so as to be included in the region A2, the amount of paste at the supply source increases, and the reliability of connection can be improved. Furthermore, if the entire via-hole conductor 28a is arranged in the region A2, the reliability can be further improved. In order to increase the reliability, the via-hole conductor 28a may be arranged so as to be removed from the region in which each of the plurality of individual electrode bodies 25a is extended in the longitudinal direction.

  Such an arrangement is obtained when the individual electrode body 25a has a rectangular shape and forms the individual electrode rows 35 side by side in the lateral direction, compared to the case where the individual electrode body 25a has a rhombus shape. Is more effective. If the individual electrode body 25a has a rectangular shape and the printing along the longitudinal direction of the individual electrode body 25a increases the amount of paste consumed, the area outside the region where the individual electrode body 25a is extended in the longitudinal direction as described above. Therefore, the necessity of arranging the via-hole conductor 28a is increased.

  6A to 6C are plan views of another embodiment of the piezoelectric actuator substrate 21 of the present invention. FIG. 6A shows the individual electrode 25, the individual electrode row 35 (the closest individual electrode row), the surface common electrode 228, and the via-hole conductor 228a. FIGS. 6B and 6C show the surface common electrodes 328 and 428 and the via-hole conductors 328a and 328b. The positional relationship between the individual electrodes 25 and the individual electrode rows 35 is the same as that shown in FIG.

  In the piezoelectric actuator substrate of FIG. 6A, the via-hole conductor 228a extends in the longitudinal direction in the region in which the individual electrode body 25a of the individual electrode 25 belonging to the nearest individual electrode row (individual electrode row 35) is continuously formed. They are arranged between the extended areas A1, and are further arranged at positions deviating from the area where the entire individual electrode body 25a is extended in the longitudinal direction. As a result, printing of the individual electrode body 25a is affected by the fact that the paste accumulated in the squeegee is reduced, and the amount of the via-hole conductor 228a is reduced, so that poor connection is unlikely to occur.

  In addition, the via hole conductor 228a is disposed on the closest individual electrode row side in the common surface electrode 228, in other words, the closest individual electrode with respect to the center in the width direction of the common surface electrode 228. Since the arrangement near the row reduces the amount of paste on the squeegee, which is reduced by printing the common surface electrode 228 before printing the via-hole conductor 228a, the connection of the via-hole conductor 228a. The certainty can be further increased.

  In the piezoelectric actuator substrate of FIG. 6B, a notch portion 328b in which the common surface electrode 328 is notched is provided on the closest individual electrode row side of the portion where the via hole conductor 328a of the common surface electrode 328 is disposed. Is provided. Since the cut-out portion 328b is present, the amount of paste used before printing the via-hole conductor 328a can be reduced, so that the reliability of connection of the via-hole conductor 328a can be further increased.

  In the piezoelectric actuator substrate of FIG. 6C, the notch 428b provided in the common surface electrode 428 is notched along the planar shape of the via-hole conductor 428a. Thereby, since the usage-amount of the paste before printing the via-hole conductor 428a can be decreased, the certainty of a via-hole conductor 428a connection can be improved more. Further, the cutout portion 428b has a shape in which the cutout width increases from the portion along the planar shape of the viahole conductor 428a toward the nearest individual electrode row side, whereby the viahole conductor 428a. By reducing the amount of paste used around the paste pool on the squeegee, which is the direct supply source, the paste does not flow there, and as a result, the connectivity of the via-hole conductor 428a can be improved.

  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 24 is formed on a part of the green sheet by a printing method or the like. Via holes 21ba are formed in the green sheet to be the piezoelectric ceramic layer 21b with a mold or the like.

  Next, each green sheet is laminated to produce a laminate, and after pressure-contacting, the laminate is cut into a rectangular shape and further fired in a high-concentration oxygen atmosphere. A silver paste to be the individual electrode 25 and the common surface electrode 28 is printed on the surface of the fired piezoelectric actuator substrate body by screen printing while moving the squeegee in the longitudinal direction of the individual electrode 25. The common surface electrode 28 is disposed on the via hole 21ba, and the via hole conductor 28a enters the via hole 21ba. Thereafter, firing was performed to form the common surface electrode 28 including the individual electrode 25 and the via-hole conductor 28a. Thereafter, the connection electrode 26 is printed using Ag paste and fired to produce the piezoelectric actuator substrate 21.

  Next, the flow path member 4 is produced by laminating plates 4a to 1l obtained by a rolling method or the like via an adhesive layer. Holes to be the manifold 5, the individual supply flow path 14, the pressurizing chamber 10, the descender, and the like are processed in the plates 4a to 4l into a predetermined shape by etching.

  These plates 4a to 4l 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. A well-known adhesive layer can be used as the adhesive layer, but in order not to affect the piezoelectric actuator substrate 21 and the flow path member 4, an epoxy resin or a phenol resin 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 polyphenylene 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.

  Next, in order to electrically connect the piezoelectric actuator substrate 21 and the control circuit 100, a silver paste is supplied to the connection electrode 26, an FPC which is a signal transmission unit 92 on which a driver IC is mounted in advance is placed, and heat is applied. In addition, the silver paste is cured and electrically connected. The driver IC was mounted by electrically flip-chip connecting the FPC to the FPC with solder, and then supplying a protective resin around the solder and curing it.

  Subsequently, if necessary, the reservoir is bonded so that the liquid can be supplied from the opening 5a, the metal housing is screwed, and then the joint is sealed with a sealant, whereby the liquid discharge head 2 is Can be produced.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... Head main body 4 ... Flow path member 4a-1 ... (flow path member) plate 4-1 ... Discharge hole surface 4-2 ... Pressure chamber surface 5 ... Manifold (common flow path)
5a ... (manifold) opening 5b ... sub-manifold 6 ... squeezing 8 ... discharge hole 9 ... discharge hole row 10 ... pressurizing chamber 11 ... pressurizing chamber row 12. ..Individual channel 14 ... Individual supply channel 15 ... Partition wall 21 ... Piezoelectric actuator substrate 21a ... Piezoelectric ceramic layer (vibrating plate)
21b ... Piezoelectric ceramic layer 21ba ... Via hole 24 ... Common electrode 25 ... Individual electrode 25a ... Individual electrode body 25b ... Extraction electrode 26 ... Connection electrode 28, 228, 328, 428 ... Common surface electrode 28a, 228a, 328a, 428a ... Via hole conductor 35 ... Individual electrode row 30 ... Displacement element (pressurizing part)
92 ... Signal transmission part

Claims (7)

A diaphragm, a common electrode, a piezoelectric ceramic layer, a surface electrode including a plurality of individual electrodes and a common surface electrode are laminated in this order, a via hole penetrating the piezoelectric ceramic layer, and the common surface electrode A piezoelectric actuator substrate comprising a via-hole conductor that electrically connects the common surface electrode and the common electrode, wherein a part of
The plurality of individual electrodes are arranged so as to constitute one or more individual electrode rows, each of which is long in one direction and arranged in a direction not parallel to the one direction,
The via-hole conductor is disposed between regions extending in the one direction from the plurality of individual electrodes belonging to the nearest individual electrode row that is the individual electrode row closest to the via-hole conductor. Piezoelectric actuator substrate.   2. The piezoelectric actuator substrate according to claim 1, wherein the via-hole conductor is disposed on the closest individual electrode row side in the common surface electrode.   The piezoelectric actuator substrate according to claim 1, wherein the common surface electrode extends along the individual electrode row, and a plurality of the via-hole conductors are arranged along the individual electrode row. .   4. The piezoelectric actuator substrate according to claim 3, wherein the common surface electrode includes a cutout portion on the closest individual electrode row side of the portion where the via-hole conductor is disposed.   5. The piezoelectric actuator substrate according to claim 4, wherein the cutout portion is cut out along a planar shape of the via-hole conductor.   A flow path member including a plurality of discharge holes and a plurality of pressurizing chambers respectively connected to the discharge holes, and the piezoelectric actuator substrate according to any one of claims 1 to 5, wherein the plurality of individual electrodes And a plurality of pressure chambers are laminated so that the positions thereof are aligned.   A recording apparatus comprising: the liquid discharge head according to claim 6; a transport unit that transports a recording medium to the liquid discharge head; and a control unit that controls the piezoelectric actuator substrate.

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