JP2015160333A - Piezoelectric substrate, assembly using the same, liquid ejection head and recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric substrate in which an electrode, in particular, an electrode for common electrode (second electrode) has strong mechanical connection between the electrode and the outside, and to provide an assembly, a liquid ejection head and a recording device each of which uses the piezoelectric substrate.SOLUTION: A piezoelectric substrate 21 comprises: a piezoelectric ceramic layer; a plurality of first electrodes 25; a second electrode; a third electrode; and a penetrating conductor 34 penetrating the piezoelectric ceramic layer and electrically connecting the second electrode and the third electrode together. The second electrode comprises an internal connection part 28a connected to the penetrating conductor 34, an external connection part 28b with width narrower than the internal connection part 28a, and a connection part 28c electrically connecting the internal connection part 28a and the external connection part 28b together. The connection part 28c is thinner than the internal connection part 28a and the external connection part 28b. The second electrode and the outside are electrically connected together at the external connection part 28b.

Description

  The present invention relates to a piezoelectric substrate, an assembly using the same, a liquid discharge head, and a recording apparatus.

  Conventionally, as a liquid ejection head, for example, an inkjet head that performs various types of printing by ejecting a liquid onto a recording medium is known. The liquid discharge head includes a flow path member including a plurality of discharge holes and a plurality of pressure chambers, and a piezoelectric actuator substrate including a displacement element that pressurizes the liquid in the pressure chamber. The displacement element is composed of a common electrode, an individual electrode, and a piezoelectric body sandwiched between them, and the common electrode is disposed on the same surface as the individual electrode through a through conductor penetrating the piezoelectric body. The common electrode surface electrode is electrically connected. In order to drive the displacement element, an FPC (Flexible Printed Circuit) is electrically connected to the individual electrode and the common electrode surface electrode of the piezoelectric actuator substrate (see, for example, Patent Document 1).

JP 2006-123519 A

  In a piezoelectric substrate (piezoelectric actuator substrate) used in a liquid discharge head as described in Patent Document 1, an individual electrode (first electrode) and a common electrode surface electrode (second electrode) are used to drive a displacement element. If the electrode is to be electrically connected to the outside, the connection condition changes due to the difference in the planar shape and cross-sectional shape of the individual electrode and the surface electrode for the common electrode, so the mechanical connection becomes weaker than the other. There was a problem that the weaker one could be connected.

  In particular, in a piezoelectric substrate using a piezoelectric ceramic, the via hole in which the through conductor is disposed is often formed before firing because it is easier to form the via hole before firing. Then, since the positional deviation of the via hole occurs due to the dimensional variation in the planar direction due to firing shrinkage, the common electrode surface electrode is formed into a large planar shape so that it can be electrically connected even if the positional deviation occurs. As a result, the mechanical connection between the surface electrode for the common electrode and the outside may be weakened.

  Accordingly, an object of the present invention is to provide an electrode of a piezoelectric substrate, in particular, a piezoelectric substrate having a strong mechanical connection between the electrode for the common electrode (second electrode) and the outside, and an assembly, a liquid discharge head, and a recording apparatus using the same. Is to provide.

The piezoelectric substrate of the present invention includes a piezoelectric ceramic layer, a plurality of first electrodes and second electrodes arranged on one main surface of the piezoelectric ceramic layer, and the other main surface of the piezoelectric ceramic layer. A third electrode disposed to face the plurality of first electrodes, and the piezoelectric ceramic layer penetrating the second electrode and the third electrode. A flat plate-like piezoelectric substrate including a through conductor, and when the piezoelectric substrate is viewed in plan, the second electrode has an internal connection portion connected to the through conductor, and the internal connection An external connection portion that is narrower than the portion, and a connection portion that electrically connects the internal connection portion and the external connection portion, the connection portion being more than the internal connection portion and the external connection portion The thickness is small, and the second electrode and the outside are in the external connection portion. Characterized in that it is electrically connected.

  An assembly of the present invention includes a wiring including the piezoelectric substrate and a plurality of wirings arranged facing the piezoelectric substrate and electrically connected to the plurality of first electrodes and the second electrode. An assembly including a substrate, wherein the planar shape of the wiring substrate is long in one direction, and has a pair of sides along the one direction, and the external connection portion has the pair of sides. The second electrode and the wiring are electrically connected to each other at the external connection portion along the pair of sides.

  The liquid discharge head of the present invention is a liquid discharge head in which a plurality of discharge holes and a flow path member including a plurality of pressurizing chambers connected to the plurality of discharge holes are joined to the piezoelectric substrate. The piezoelectric ceramic layer is deformed by applying a voltage between the first electrode and the second electrode to pressurize the liquid in the pressurizing chamber.

  The liquid discharge head of the present invention includes a flow path member including a plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, and the assembly, and the flow path member. And the piezoelectric substrate are bonded to each other, and by applying a voltage between the first electrode and the second electrode, the piezoelectric ceramic layer is deformed, and the pressure chamber The liquid is pressurized.

  The recording apparatus of the 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 liquid discharge head.

  According to the piezoelectric substrate of the present invention, in the second electrode, the electrical connection with the outside is performed by the external connection portion, so that the mechanical connection is strengthened. In addition, since the electrical connection between the second electrode and the third electrode is performed in the internal connection portion wider than the external connection portion in the second electrode, the second electrode may be displaced due to misalignment during manufacturing. And the third electrode are unlikely to be connected.

(A) is a side view of a recording apparatus including a liquid ejection head according to an embodiment of the present invention, and (b) is a plan view. FIG. 2 is a plan view of a head body that is a main part of 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 a longitudinal cross-sectional view along the VV line of FIG. 3, (b) is an enlarged plan view of the vicinity of the first electrode (individual electrode), and (c) is a diagram of the piezoelectric actuator substrate. It is a longitudinal cross-sectional view along the dashed-dotted line shown by (b). (A) is a top view of the 2nd electrode (surface electrode for common electrodes) of the piezoelectric actuator board | substrate shown by FIGS. 2-4, (b) is a longitudinal section of the piezoelectric actuator board | substrate of the part of (a) It is a top view, (c), (d) is a top view of the 2nd electrode in other embodiment of this invention.

FIG. 1A is a schematic side view of a (color inkjet) printer 1 which is a recording apparatus including a liquid discharge head 2 according to an embodiment of the present invention, and FIG. 1B is a schematic plan view. It is. The printer 1 transfers the printing paper P, which is a recording medium, from the conveyance roller 80a to the conveyance roller 80.
The printing paper P is moved relative to the liquid ejection head 2 by being conveyed to b. The control unit 88 controls the liquid ejection head 2 based on image and character data, ejects liquid toward the recording medium P, causes droplets to land on the printing paper P, and prints on the printing paper P. Record such as.

  In the present embodiment, the liquid discharge head 2 is fixed to the printer 1, and the printer 1 is a so-called line printer. As another embodiment of the recording apparatus of the present invention, the operation of moving the liquid ejection head 2 by reciprocating in the direction intersecting the transport direction of the printing paper P, for example, the direction substantially orthogonal, and the printing paper P There is a so-called serial printer that alternately conveys.

  A flat plate (head mounting) frame 70 is fixed to the printer 1 so as to be substantially parallel to the printing paper P. The frame 70 is provided with 20 holes (not shown), and the 20 liquid discharge heads 2 are mounted in the respective hole portions, and the portion of the liquid discharge head 2 that discharges the liquid is the printing paper P. It has come to face. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm. The five liquid ejection heads 2 constitute one head group 72, and the printer 1 has four head groups 72.

  The liquid discharge head 2 has a long and narrow shape in the direction from the front to the back in FIG. 1A and in the vertical direction in FIG. This long direction is sometimes called the longitudinal direction. Within one head group 72, the three liquid ejection heads 2 are arranged along a direction that intersects the conveyance direction of the printing paper P, for example, a substantially orthogonal direction, and the other two liquid ejection heads 2 are conveyed. Each of the three liquid ejection heads 2 is arranged at a position shifted along the direction. The liquid discharge heads 2 are arranged so that the printable range of each liquid discharge head 2 is connected in the width direction of the print paper P (in the direction intersecting the conveyance direction of the print paper P) or the ends overlap. Thus, printing without gaps in the width direction of the printing paper P is possible.

  The four head groups 72 are arranged along the conveyance direction of the recording paper P. Liquid (ink) is supplied to each liquid discharge head 2 from a liquid tank (not shown). The liquid ejection heads 2 belonging to one head group 72 are supplied with the same color ink, and four color inks can be printed by the four head groups. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). A color image can be printed by printing such ink under the control of the control unit 88.

  The number of liquid ejection heads 2 mounted on the printer 1 may be one if it is a single color and the range that can be printed by one liquid ejection head 2 is printed. The number of the liquid ejection heads 2 included in the head group 72 and the number of the head groups 72 can be appropriately changed according to the printing target and printing conditions. For example, the number of head groups 72 may be increased to perform multicolor printing. Also, by arranging a plurality of head groups 72 that print in the same color and printing alternately in the transport direction, the printing speed (transport speed) can be increased. Alternatively, a plurality of head groups 72 for printing in the same color may be prepared and arranged so as to be shifted in a direction crossing the transport direction, so that the resolution in the width direction of the print paper P may be increased.

  Further, in addition to printing colored inks, a liquid such as a coating agent may be printed for surface treatment of the printing paper P.

The printer 1 performs printing on a printing paper P that is a recording medium. The printing paper P is wound around the paper feed roller 80a, passes between the two guide rollers 82a, passes through the lower side of the liquid ejection head 2 mounted on the frame 70, and thereafter It passes between the two conveying rollers 82b and is finally collected by the collecting roller 80b. When printing, the printing paper P is conveyed at a constant speed by rotating the conveyance roller 82 b and printed by the liquid ejection head 2. The collection roller 80b winds up the printing paper P sent out from the conveyance roller 82b. The conveyance speed is, for example, 75 m / min. Each roller may be controlled by the controller 88 or may be manually operated by a person.

  In addition to the printing paper P, the recording medium may be a cloth or the like. In addition, the printer 1 is configured to convey a conveyance belt instead of the printing paper P, and the recording medium is not only a roll-shaped one, but also a sheet, cut cloth, wood, It may be a tile. Furthermore, a wiring pattern of an electronic device may be printed by discharging a liquid containing conductive particles from the liquid discharge head 2. Still further, the chemical may be produced by discharging a predetermined amount of liquid chemical agent or liquid containing the chemical agent from the liquid discharge head 2 toward the reaction container or the like and reacting.

  In addition, a position sensor, a speed sensor, a temperature sensor, and the like may be attached to the printer 1, and the control unit 88 may control each part of the printer 1 according to the state of each part of the printer 1 that can be understood from information from each sensor. In particular, if the discharge characteristics (discharge amount, discharge speed, etc.) of the liquid discharged from the liquid discharge head 2 are affected by the outside, the temperature of the liquid discharge head 2, the temperature of the liquid in the liquid tank, the liquid tank Depending on the pressure applied by the liquid to the liquid ejection head 2, the drive signal for ejecting the liquid in the liquid ejection head 2 may be changed.

  Next, the liquid discharge head 2 according to an embodiment of the present invention will be described. FIG. 2 is a plan view showing a head main body 2a which is a main part of the liquid ejection head 2 shown in FIG. FIG. 3 is an enlarged plan view of a region surrounded by a one-dot chain line in FIG. 2, and is a part of the head main body 2a. In FIG. 3, for the sake of explanation, some of the flow paths are omitted. FIG. 4 is an enlarged plan view at the same position as FIG. 3, and a part of the flow path different from FIG. 3 is omitted. 5A is a longitudinal sectional view taken along the line VV in FIG. 3, and FIG. 5B is an enlarged plan view of the vicinity of the individual electrode (first electrode) 25 of the head body 2a. FIG. 5C is a longitudinal sectional view of the piezoelectric actuator substrate 21 taken along the alternate long and short dash line shown in FIG. 6A is a plan view of the common electrode surface electrode (second electrode) 28 of the piezoelectric actuator substrate 21 used in the head body 2a, and FIG. 6B is a common electrode surface electrode. 2 is a longitudinal sectional view of a piezoelectric actuator substrate 21 in the vicinity of 28. FIG. 3 and 4, in order to make the drawings easy to understand, the pressurizing chamber 10, the squeezing 6, the discharge holes 8, and the like that are to be drawn by broken lines below the piezoelectric actuator substrate 21 are drawn by solid lines. 5 (a), FIG. 5 (c), and FIG. 6 (b), which are longitudinal cross-sectional views, are larger in the horizontal scale than the vertical scale in the figure, and are drawn vertically longer than the actual shape. It is.

  In addition to the head main body 2a, the liquid discharge head 2 may include a reservoir for supplying liquid to the head main body 2a and a metal casing. The head body 2a includes a flow path member 4 and a piezoelectric actuator substrate 21 that is a piezoelectric substrate in which a displacement element 30 is formed.

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

In addition, a piezoelectric actuator substrate 21 including a displacement element 30 is bonded to the upper surface of the flow path member 4 by adhesion, and each displacement element 30 is disposed on the pressurizing chamber 10. The piezoelectric actuator substrate 21 is connected to a signal transmission unit (wiring substrate) 60 such as an FPC (Flexible Printed Circuit) for supplying a signal to each displacement element 30.
The piezoelectric actuator substrate and the signal transmission unit are collectively called an assembly. In FIG. 2, the outline of the vicinity of the signal transmission unit 60 connected to the piezoelectric actuator substrate 21 is indicated by a dotted line so that the signal transmission unit 60 is connected to the piezoelectric actuator substrate 21. The electrodes of the wiring 60 c formed in the signal transmission unit 60 and electrically connected to the piezoelectric actuator substrate 21 are arranged in a rectangular shape at the end of the signal transmission unit 60. The signal transmission unit 60 is disposed so as to face the piezoelectric actuator substrate 21 and is disposed along the longitudinal direction of the piezoelectric actuator substrate 21 and further extends downward in FIG. It is electrically connected to the controller 88 (via a circuit board or the like). A large number of wirings 60 c included in the signal transmission unit 60 are arranged in a direction intersecting the longitudinal direction of the signal transmission unit 60 and extend along the longitudinal direction. The wirings 60c in FIG. 2 are schematically shown so that the direction in which they are arranged and the direction in which they extend are understood.

  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 (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.

  The manifold 5 is partitioned by a partition wall 15 provided at an interval in the short-side direction at least in the central portion in the longitudinal direction, which is a region connected to the pressurizing chamber 10. The partition wall 15 has the same height as the manifold 5 in the central portion in the longitudinal 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 the flow path connected from the discharge hole 8 to the pressurizing chamber 10 so as to overlap with the partition wall 15 in a plan view.

  The portion of the manifold 5 divided into a plurality of parts may be referred to as a sub-manifold 5b. In the present 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.

  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 or elliptical 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, two pressurizing chamber rows 11, which are rows of pressurizing chambers 10 connected to the sub-manifold 5b, are provided on each side of the sub-manifold 5b, for a total of two rows. Yes. Accordingly, 16 rows of pressurizing chambers 11 are provided for one manifold 5, and 32 heads of pressurizing chambers 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.

One column of dummy pressurizing chambers 16 is provided at the end of each pressurizing chamber row 11. The dummy pressurizing chambers 16 in the dummy pressurizing chamber row are connected to the manifold 5 but are not connected to the discharge holes 8. Further, one dummy pressurizing chamber row in which dummy pressurizing chambers 16 are arranged in a straight line is provided outside the 32 pressurizing chamber rows 11. The dummy pressurizing chamber 16 in this dummy pressurizing chamber row is not connected to either the manifold 5 or the discharge hole 8. By these dummy pressurizing chambers 16, the structure (rigidity) around the pressurizing chamber 10 one inner side from the end is close to the structure (rigidity) of the other pressurizing chambers 10, so that the difference in liquid ejection characteristics can be reduced. Less. In addition, since the influence of the surrounding structure difference has a large influence on the pressurizing chambers 10 adjacent to each other in the length direction, the dummy pressurizing chambers are provided at both ends in the length direction. 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 chamber 10 connected to one manifold 5 is arranged on a lattice that forms rows and columns along each outer side of the rectangular piezoelectric actuator substrate 21. As a result, the individual electrodes 25, which are the first electrodes formed on the pressurizing chamber 10, are arranged at equal distances from the outer side of the piezoelectric actuator substrate 21, so that the individual electrodes 25 are formed. At this time, the piezoelectric actuator substrate 21 can be hardly deformed. 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 rows 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.

  In the present embodiment, the pressurizing chambers 10 are arranged in a lattice shape, but the pressurizing chambers 10 of adjacent pressure chamber rows 11 may be arranged in a staggered manner so as to be positioned between each other. In this way, since the distance between the pressurizing chambers 10 belonging to the adjacent pressurizing chamber row 11 becomes longer, crosstalk can be further suppressed.

  Regardless of how the pressurizing chamber rows 11 are arranged, when the flow path member 4 is viewed in plan, the pressurizing chamber 10 belonging to one pressurizing chamber row 11 is added to the adjacent pressurizing chamber row 11. By arranging the pressure chamber 10 and the liquid discharge head 2 so as not to overlap in the longitudinal direction, 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, so that the accuracy of the installation angle of the liquid discharge head 2 relative to the printer 1 and the use of a plurality of liquid discharge heads 2 are 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 chamber 10 connected to one sub-manifold 5b forms two rows of 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 formed. 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, two discharge hole rows 9 are provided in the partition wall 15, but the discharge holes 8 belonging to each discharge hole row 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, 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, crosstalk can be further reduced.

A plurality of pressurizing chambers 10 connected to one manifold 5 are combined with a pressurizing chamber group (displacement element group 3
Is the same range as 1), and there are two manifolds 5, so 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 at a position translated in the short 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 a region having almost the same 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.

  From the corner facing the corner to which the individual supply channel 14 of the pressurizing chamber 10 is connected, there is a channel connected to the discharge hole 8 opened in the discharge hole surface 4-1 on the lower surface of the channel member 4. It is growing. This flow path extends in a direction away from the pressurizing chamber 10 in a 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 with a resolution of 600 dpi, and printing accuracy is higher than when four liquid ejection heads capable of printing at 600 dpi are used. Can also be done easily. At this time, since the two manifolds 5 are arranged apart from each other, groups of ejection holes 8 that eject ink of the same color are also arranged apart from each other, which may occur due to wiping or the like. It is difficult for some inks to mix. In addition, the range of R of the imaginary straight line is covered with the discharge holes 8 connected to the pressurizing chambers 10 belonging to the one pressurizing chamber row arranged in the short direction of the head main body 2a.

  The discharge hole 8 is disposed at a position that avoids a region facing the manifold 5 disposed 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 shape as the piezoelectric actuator substrate 21 as one group, and a droplet is discharged from the discharge hole 8 by displacing the displacement element 30 of the corresponding piezoelectric actuator substrate 21. Can be discharged.

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. The thickness of the flow path member 4 is about 500 μm to 2 mm. 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 that forms a flow path that communicates with the discharge hole 8 from the other end opposite to the end to which the individual supply path 14 of the pressurizing chamber 10 is connected. This communication hole may be called 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).

  Fourthly, there is a communication hole constituting the sub-manifold 5a. 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 portions to be the partition walls 15 remain so as to constitute the sub-manifold 5b. The partition portion in each manifold plate 4e-j is connected to each manifold plate 4e-j by a half-etched support portion (not shown in the figure).

  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. The liquid that has entered the descender from the pressurizing chamber 10 moves in the horizontal direction and is mainly directed downward and reaches the discharge hole 8 opened in the lower surface, and is discharged to the outside.

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. The piezoelectric ceramic layers 21a, 21b may, for example, strength with a dielectric, lead zirconate titanate (PZT), NaNbO ₃ system, BaTiO ₃ system, (BiNa) NbO ₃ system, such as BiNaNb ₅ O ₁₅ system Made of ceramic material. The piezoelectric ceramic layer 21a functions as a vibration plate and does not necessarily have to be a piezoelectric body. Instead, other ceramic layers or metal plates that are not piezoelectric bodies may be used.

  Individual electrodes 25 as first electrodes are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. As with the pressurizing chamber 10, the individual electrodes 25 constitute an individual electrode row and an individual electrode group.

The individual electrode 25 is slightly smaller than the pressurizing chamber 10, and has an individual electrode main body 25a having a shape substantially similar to the pressurizing chamber 10, an extraction electrode 25b extracted from the individual electrode main body 25a, and an extraction electrode And a land portion 25c disposed at one end of 25b. The individual electrode main body 25a and the extraction electrode 25b are made of, for example, a metal material such as Au and have a thickness of 0.3 to
It is about 2 μm. The land portion 25c is made of, for example, Ag—Pd containing glass frit, and is formed in a circular shape having a thickness of about 5 to 15 μm. The land portion 25c is a portion for electrical connection with the outside, and is thicker than the individual electrode main body 25a and the extraction electrode 25b. The thickness of the land portion 25b is the height from the upper surface of the piezoelectric ceramic layer 21b to the upper surface of the land portion 25b, and the land portion 25b is formed on a part of the extraction electrode 25b. The thickness of the land portion 25b is a value obtained by adding the thickness of the land portion 25b alone and the thickness of the extraction electrode 25b.

  A common electrode surface electrode 28 as a second electrode is formed on the upper surface of the piezoelectric actuator substrate 21. The common electrode surface electrode 28 is electrically connected to the common electrode 24 that is the third electrode through a through conductor 34 that penetrates the piezoelectric ceramic layer 21b. A plurality of piezoelectric actuator substrates 21 are arranged along the longitudinal direction at the center in the short direction (see FIG. 3). The common electrode surface electrode 28 includes an internal connection portion 28a connected to the through conductor 34, an external connection portion 28b narrower than the internal connection portion 28a, and the internal connection portion 28a and the external connection portion 28b. The connection part 28c connected electrically is included. In addition, the width | variety said here is the shortest thing among the length of the delivery including an applicable part. In FIG. 6A, the width of the internal connection portion 28a is Wa, the width of the external connection portion 28b is Wb, and Wb <Wa.

  The internal connection part 28a and the external connection part 28b are made of, for example, Ag—Pd containing glass frit, and have a thickness of about 5 to 15 μm. If the internal connection portion 28a and the external connection portion 28b have the same composition as the land portion 25c and are formed in the same process, the manufacturing cost can be reduced. Further, if the composition of the external connection portion 28b and the land portion 25c are the same, the connection state with the outside becomes close and the difference in strength can be reduced.

  The connection portion 28c is made of, for example, a metal material such as Au, and has a thickness of about 0.3 to 2 μm. If the connection portion 28c has the same composition as the individual electrode main body 25a and the extraction electrode 25b and is formed in the same process, the manufacturing cost can be reduced.

  A connection bump 27 is formed on the land portion 25c. A common electrode connection bump 32 is formed on the external connection portion 28 b which is a part of the common electrode surface electrode 28. The connection bumps 27 and the common electrode connection bumps 32 are conductive resins containing conductive particles such as silver particles, and are formed in a convex shape with a height of about 50 μm. The connection bumps 27 and the common electrode connection bumps 32 are electrically joined to electrodes provided in the signal transmission unit 60. In this embodiment, the connection bump 27 and the common electrode connection bump 32 are formed. However, the connection bump 27 and the common electrode connection bump 32 may not be formed on the piezoelectric actuator substrate 21 of the present invention. Absent. Although details will be described later, a drive signal is supplied from the control unit 88 to the individual electrode 25 through the signal transmission unit 60. 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 made of a metal material such as Ag—Pd, and 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 actuator substrate 21. The thickness of the common electrode 24 is about 0.5 to 3 μm. The common electrode 24 is formed through the piezoelectric ceramic layer 21b in the internal connection portion 28a of the common electrode surface electrode 28 formed on the piezoelectric ceramic layer 21b so as to avoid the electrode group composed of the individual electrodes 25. They are connected via a through electrode 34 that enters the via hole, and are grounded and held at the ground potential. The common electrode surface electrode 28 is directly or indirectly connected to the control unit 88 in the same manner as the large number of individual electrodes 25.

  A portion sandwiched between the individual electrode 25 and the common electrode 24 of the piezoelectric ceramic layer 21b is polarized in the thickness direction, and becomes a displacement element 30 having a unimorph structure that is displaced when a voltage is applied to the individual electrode 25. Yes. More specifically, when an electric field is applied in the polarization direction to the piezoelectric ceramic layer 21b by setting the individual electrode 25 to a potential different from that of the common electrode 24, an active portion where the applied electric field is distorted by the piezoelectric effect. Work as. In this configuration, when the control unit 88 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, the 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 21a and the piezoelectric ceramic layer 21b, and the piezoelectric ceramic layer 21a is deformed so as to be convex toward the pressurizing chamber 10 (unimorph deformation).

  Next, the liquid discharge operation will be described. The displacement element 30 is driven (displaced) by a drive signal supplied to the individual electrode 25 through a driver IC or the like under the control of the control unit 88. In the present embodiment, liquid can be ejected by various driving signals. Here, a so-called strike driving method will be described.

  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 once set to the same potential as the common electrode 24 (hereinafter referred to as a low potential) each time an ejection request is made, and then a predetermined potential At this timing, the potential is set again. Thereby, the piezoelectric ceramic layers 21a and 21b return to the original (flat) shape at the timing when the individual electrode 25 becomes low potential (beginning), and the volume of the pressurizing chamber 10 is in an initial state (the potentials of both electrodes are different). Increase compared to the state). As a result, a negative pressure is applied to the liquid in the pressurizing chamber 10. Then, the liquid in the pressurizing chamber 10 starts to vibrate with the natural vibration period. Specifically, first, the volume of the pressurizing chamber 10 begins to increase, and the negative pressure gradually decreases. Next, the volume of the pressurizing chamber 10 becomes maximum and the pressure becomes almost zero. Next, the volume of the pressurizing chamber 10 begins to decrease, and the pressure increases. Thereafter, the individual electrode 25 is set to a high potential at a timing at which the pressure becomes substantially maximum. Then, the first applied vibration overlaps with the next applied vibration, and a larger pressure is applied to the liquid. This pressure propagates through the descender and discharges the liquid from the discharge hole 8.

In other words, a droplet can be ejected by supplying a pulse driving signal that is a low potential for a certain period with the high potential as a reference to the individual electrode 25. If this pulse width is AL (Acoustic Length), which is half the natural vibration period of the liquid in the pressure chamber 10, in principle, the discharge speed and discharge amount of the liquid can be maximized. The natural vibration period of the liquid in the pressure chamber 10 is greatly influenced by the physical properties of the liquid and the shape of the pressure chamber 10, but besides that, from the physical properties of the actuator substrate 21 and the characteristics of the flow path connected to the pressurizing chamber 10. Also affected by.

  Note that the pulse width is actually set to a value of about 0.5 AL to 1.5 AL because there are other factors to consider, such as combining the ejected droplets into one. Further, since the discharge amount can be reduced by setting the pulse width to a value outside of AL, the pulse width is set to a value outside of AL in order to reduce the discharge amount.

  A large number of individual electrodes 25 are arranged on the piezoelectric actuator substrate 21 in order to increase the resolution. When the size of the liquid discharge head 2 is increased, there is a problem that the alignment accuracy required for installation becomes high. Therefore, the individual electrodes 25 are arranged in a narrow range as much as possible, and the common electrode surface electrode 28 is arranged. It is better to reduce the area to be used.

Therefore, the extraction electrode 25b has a land portion 25c formed at a position where the extraction electrode 25b is extracted just outside the pressurizing chamber 10 (a position closer to the original pressurizing chamber 10 than the other pressurizing chambers 10). Further, a connection bump 27 is formed on the land portion 25c and is electrically connected to the outside. The piezoelectric ceramic layer 21b between the lead electrode 25b, the land portion 25c and the connection bump 27 and the common electrode 34 is also piezoelectrically deformed when a voltage is applied to the individual electrode body 25a. The deformation of this portion is not so preferable because the amount of displacement of the displacement element 30 is reduced or the vibration is transmitted to the adjacent pressurizing chamber 10 to cause crosstalk. Therefore, the extraction electrode 25b, the land portion 25c, and the connection bump 27 are made thin or small within a range where electrical or mechanical connection can be made so as to reduce the piezoelectric deformation region. The common electrode connection bumps 32 are not limited by such piezoelectric deformation, but are often preferably the same height as the connection bumps 27 when connected to the signal transmission unit 60. The connection bump 27 is almost the same size and height.

  Considering the manufacturing process of the piezoelectric actuator substrate 21, the individual electrode 25, the common electrode surface electrode 28, the connection bump 27, and the common electrode connection bump 32 are preferably formed after firing the piezoelectric ceramic layer 21b. When the individual electrode 25 or the common electrode surface electrode 28 is formed by firing, the individual electrode 25 or the common electrode surface electrode 28 and the piezoelectric actuator substrate 21 completely match the shrinkage amount due to firing and the shrinkage curve due to temperature. Therefore, when firing at the same time, there is a difference in size between the portion where the individual electrode 25 and the common electrode surface electrode 28 are present and the portion where the individual electrode 25 and the common electrode surface electrode 28 are absent during the shrinkage process. Then, warping or deformation occurs in the piezoelectric actuator substrate 21 after firing. The through conductor 34 is preferably formed by forming a via hole in the piezoelectric ceramic layer 21b before firing to form a via hole 34, and placing the conductor therein. This is because it is easier to open the through-hole before firing, and there is a possibility that breakage or the like may occur if processed after firing.

  From the above points, as a manufacturing process of the piezoelectric actuator substrate 21, the via heel 34 is formed on the piezoelectric ceramic layer 21b before firing, and after firing, a paste that becomes the individual electrode 25, the surface electrode 28 for the common electrode is applied, It is preferable to bake (omitted portions and processes having low relationship).

  In such a process, the via hole 34 is displaced due to variations in the firing dimensions of the piezoelectric ceramic layer 21b. The planar shape of the common electrode surface electrode 28 in the connecting portion is increased so that the common electrode surface electrode 28 and the common electrode 24 are not electrically connected due to the displacement.

  Specifically, the size of the common electrode surface electrode 28 is preferably 1% or more, more preferably 1.5% or more of the dimension of the piezoelectric actuator substrate 21. For example, when the dimension of the piezoelectric actuator substrate 21 is 4 cm × 11 cm, the size of the common electrode surface electrode 28 is preferably 400 μm × 1100 μm or more, and more preferably 600 μm × 1650 μm or more. Further, in order to increase the reliability of the electrical connection, the common electrode surface electrode 28 and the via hole 34 are not only overlapped but are formed so that the common electrode surface electrode 28 covers the via hole 34. preferable. In order to do so, the size of the common electrode surface electrode 28 is preferably set to a value obtained by adding the dimension of the via hole 34 to the above-described dimension, for example, 100 to 300 μm. In this case, the longitudinal direction of the common electrode surface electrode 28 and the longitudinal direction of the piezoelectric actuator substrate 21 are preferably matched.

  On the other hand, in the extraction electrode 25b and the land portion 25c, the extraction electrode 25b is made thinner and the land portion 25c is made smaller in order to reduce unnecessary piezoelectric deformation as described above. The width W2 of the extraction electrode 25b is preferably 30 to 300 μm, more preferably 50 to 200 μm. The width (size) W3 of the land portion 25c is circular and preferably has a diameter of 30 to 300 μm, and more preferably 50 to 200 μm.

Then, if the piezoelectric actuator substrate 21 is a substrate having a length in the short direction of 2 cm or more and the diameter of the via hole 34 is 100 μm, the width of the common electrode surface electrode 28 is 300 μm or more, and the diameter of the land portion 25 c is 200 μm or less. The width will be more than 1.5 times different. For the above-described reason, the common electrode surface electrode 28 tends to be larger and the land portion 25c tends to be designed smaller. Depending on the method for forming the common electrode surface electrode 28 and the land portion 25c and how the material to be used for the common electrode surface electrode 28 and the land portion 25c is supplied, it is costly to apply a liquid material. In this case, a difference occurs in the cross-sectional shape after the supply due to the difference in the planar shape to be formed. That is, when the width is narrow, the center is high and has a convex shape, and when the width is wide, the shape is almost flat. When printing is performed by screen printing or the like, this tendency increases due to the viscosity of the paste used in such printing and the behavior of the paste during printing. As a result, the land portion 25c having a convex central portion has a high central portion, and the cross-sectional shape is a raised shape at the central portion. However, the mechanical connection between the common electrode surface electrode 28 and the common electrode connection bump 32 is weaker than that.

  On the other hand, the common electrode surface electrode 28 is provided with a wide internal connection portion 28 a to be connected to the through conductor 34 and an external connection portion 28 b narrower than the internal connection portion 28 a, and the common electrode connection bump 32. The connection is made at the external connection portion 28b. Since the central portion of the external connection portion 28b is convex and close to the cross-sectional shape of the land portion 25c, the mechanical connection with the common electrode connection bump 32 is strengthened. The planar shape of the external connection portion 28b is preferably substantially the same as the planar shape of the land portion 25c. Here, “substantially the same” means that the larger one is 1.4 times or less of the smaller one, further 1.2 times or less, and preferably within the range of manufacturing variation.

  Further, if the size of the connection bump 27 and the common electrode connection bump 32 is larger than that of the land portion 25c and the external connection portion 28b, the connection bump 27 and the common electrode connection bump 32 are also bonded to the piezoelectric ceramic layer 21b. Since the adhesive strength between the resin and the piezoelectric ceramic layer 21b is increased, the mechanical connection is strengthened. In particular, in the conventional common electrode surface electrode 28, since the common electrode connection bump 32 is disposed in a wide portion, the common electrode connection bump 32 is accommodated in the common electrode surface electrode 28, so that Since it was not joined to the ceramic layer 21b, the strength was low.

  As described above, the internal connection portion 28a needs to have a certain large area. Moreover, since it is preferable to form the internal connection part 28a simultaneously with the land part 25c on a process, the thickness becomes thick. In particular, when forming the internal connection portion 28a, when a part of the paste enters the via hole 34 to make an electrical connection with the common electrode 24, the internal connection is made so that it is difficult to disconnect at the edge of the via hole 34 or the like. It is necessary to heat the part 28a. As a result, the internal connection portion 28a has a structure in which conductors are relatively concentrated, and the internal connection portion 28a and its surroundings may be locally warped. Here, the step of forming the internal connection portion 28a after the piezoelectric ceramic layers 21a and 21b are fired is considered. However, if the internal connection portion 28a is formed even in the case of sintered ceramics, firing shrinkage and heat Slight warping occurs due to differences in expansion coefficients.

  Even if the external connection portion 28b has a strong connection strength with the outside as a single structure, if there is a local warp around the internal connection portion 28a, the height may vary and the connection may be weakened. Therefore, the external connection portion 28b and the internal connection portion 28a are connected by the connection portion 28c having a smaller thickness. By doing so, since the external connection portion 28b and the internal connection portion 28a can be arranged apart from each other, the external connection portion 28b can be hardly affected by the warp around the internal connection portion 28a. Further, since the thin connection portion 28c exists around the external connection portion 28b, the difference between the shape of the external connection portion 28b and the shape of the land portion 25c is reduced, and the difference in connection state is also reduced. it can.

  The warpage around the internal connection portion 28a becomes particularly large when the thickness of the piezoelectric actuator substrate (to be precise, from below the piezoelectric ceramic layer 21a to above the piezoelectric ceramic layer 21b) is 100 μm or less. When a square internal connection portion 28a having a side of 300 μm was formed on the piezoelectric actuator substrate 21 having a thickness of 40 μm, the warp affected from the end of the internal connection portion 28a to about 300 μm. When the internal connection portion 28a is about 1 to 2 mm in size, the warpage of the internal connection portion 28a itself is large, but the range affected by the warpage is almost 300 μm. That is, by separating the distance Lc between the internal connection portion 28a and the external connection portion 28b by 300 μm or more, it is possible to suppress the warpage around the internal connection portion 28a from affecting the external connection portion 28b.

  In order to further reduce the warpage around the external connection portion 28b, the width Wc of the connection portion 28c is preferably narrower than the width (size) Wb of the external connection portion 28b. The same applies to the individual electrode 25, and the width W2 of the extraction electrode 25b is preferably narrower than the width (size) W3 of the land portion 25c. In order to reduce the difference in the connection state between the external connection portion 28b and the land portion 25c, it is preferable to set Wb = W3 and Wc = W2 within the range of manufacturing accuracy.

  The external connection portion 28 b preferably has a shape that extends along the longitudinal direction of the piezoelectric actuator substrate 21. Since the piezoelectric actuator substrate 21 is elongated in the printing resolution direction, the dimensions of the same piezoelectric actuator substrate 21 are obtained when the external connection portion 28b is formed in a shape that extends in a direction that does not extend along the longitudinal direction of the piezoelectric actuator substrate 21 (for example, an orthogonal direction). On the other hand, the effective printable area is reduced. That is, the printable area can be widened by forming the external connection portion 28 b in a shape extending along the longitudinal direction of the piezoelectric actuator substrate 21. Further, in the head main body 2a of the present embodiment, the two manifolds 5 are spaced apart in order to suppress color mixing when using different color inks. By making the external connection portion 28b extend along the longitudinal direction of the piezoelectric actuator substrate 21, the area of the piezoelectric actuator substrate 21 can be used effectively.

  Next, another form of the common electrode surface electrode will be described. FIG. 6C shows a common electrode surface electrode 128 according to another embodiment, which can be used instead of the common electrode surface electrode 28 shown in FIG. 3. The common electrode surface electrode 128 is arranged along the longitudinal direction of the piezoelectric actuator substrate 21 in the order of an internal connection portion 128a, a connection portion 128c, an external connection portion 128b, another connection portion 128c, and another internal connection portion 128a. Yes. A plurality of such common electrode surface electrodes 128 may be arranged, or may be arranged so as to repeat the same arrangement by extending to the left and right of the figure as shown. By being configured in such a shape, since the electrical connection with the common electrode 24 and the electrical connection with the outside are performed at a plurality of places, some electrical connections are not connected. However, the difference in conduction operation due to this can be reduced.

  FIG. 6D is a common electrode surface electrode 228 in another embodiment, and can be used instead of the common electrode surface electrode 28 shown in FIG. 3. In the common electrode surface electrode 228, a plurality of through conductors 34 are disposed in one internal connection portion 228a, and a plurality of common electrode connection bumps 32 are also disposed in one external connection portion 228b. Thereby, even if some electrical connections are not connected, the difference in conduction operation due to this can be reduced.

Since a large number of wirings 60c are arranged in the signal transmission unit 60, the signal transmission unit 60 is long in one direction, the wiring 60c extends in one direction, and is arranged in a direction (width direction) intersecting the one direction. It is preferable to arrange. Since the common electrode surface electrode 28 becomes a so-called ground,
The wiring 60c connected thereto is preferably thicker than the other wirings 60c, and is preferably provided at the end of the signal transmission unit 60 in the width direction. For this reason, the electrical connection between the signal transmission portion 60 and the common electrode surface electrode 28 is performed at two opposing sides located at the end in the width direction of the outer peripheral portion 28a of the common electrode surface electrode 28. Preferably.

  Although the liquid ejection head 2 has been described above, the piezoelectric substrate can be used as an actuator other than the liquid ejection head, for example, a speaker, a buzzer, a sensor, a filter constituting an electrical circuit, or the like. When these piezoelectric substrates are bonded to other members with an adhesive, or when the surroundings are covered with a resin or the like, there is an effect of suppressing the inflow thereof. In particular, an assembly in which a piezoelectric substrate and a wiring substrate are electrically joined is useful for a sensor including a large number of sensor elements.

  The liquid discharge head 2 as described above is manufactured as follows. A tape composed of a piezoelectric ceramic raw material 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. . On some green sheets, an Ag—Pd paste to be the common electrode 24 is formed on the surface thereof by a printing method or the like. Also, a via hole 34 that connects the common electrode 24 and the common electrode surface electrode 28 is formed in a part of the green sheet.

  Next, each green sheet is laminated to produce a laminate, and pressure adhesion is performed. The laminated body after pressure contact is fired in a high concentration oxygen atmosphere to obtain a fired body. Thereafter, the individual electrode main body 25a, the extraction electrode 25b, and the connection electrode 28c are printed on the surface of the fired body using an organic gold paste and fired. The individual electrode body 25a, the extraction electrode 25b, and the connection electrode 28c are made from the same paste and have substantially the same composition.

  Further, the land portion 25c, the internal connection portion 28a, and the external connection portion 28b are printed using Ag—Pd paste and fired. The Ag—Pd paste printed as the internal connection portion 28 a enters the via hole 34 opened in the green sheet and is connected to the common electrode 24, and the entered Ag—Pd paste becomes the through electrode 34. Thus, after firing, the common electrode surface electrode 28 and the common electrode 24 are electrically connected. The land portion 25c, the internal connection portion 28a, and the external connection portion 28b are made of the same paste and have substantially the same composition. As described above, the piezoelectric actuator substrate 21 is manufactured.

  Next, the flow path member 4 is obtained by laminating plates 4a to 4l obtained by a rolling method or the like via an adhesive layer, and the manifold 5, the individual supply flow path 14, and the pressurizing chamber 10 Further, holes to be descenders and the like are processed 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. As described above, the flow path member 4 having a plurality of pressure element groups is produced.

The piezoelectric actuator substrate 21 and the flow path member 4 can be laminated and bonded through, for example, an adhesive layer. As a result, the pressurizing chamber 10 is closed with the piezoelectric actuator substrate 21. 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.

  Thereafter, a conductive resin containing Ag particles is applied on the land portion 25c and the external connection portion 28b of the piezoelectric actuator substrate 21, and cured to form the connection bump 27 and the common electrode connection bump 32. Subsequently, the connection bump 27 and the common electrode connection bump 32 are electrically connected to the FPC which is the signal transmission unit 60. Furthermore, the liquid discharge head 2 can be obtained by applying a voltage between the individual electrode 25 and the common electrode 24 through the FPC, and polarizing the piezoelectric ceramic layer 21b sandwiched between them.

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 5a ... (Manifold) opening 5b ... Sub-manifold 6 ... Squeeze 8 ... Discharge hole 9 ... Discharge hole row 10 ... Addition Pressure chamber 11 ... Pressurization chamber row 12 ... Individual flow path 14 ... Individual supply flow path 15 ... Partition wall 16 ... Dummy pressurization chamber 21 ... Piezoelectric actuator substrate (piezoelectric substrate)
21a: Piezoelectric ceramic layer (diaphragm)
21b: Piezoelectric ceramic layer 24: Common electrode (third electrode)
25 ... Individual electrode (first electrode)
25a ... Individual electrode body 25b ... Extraction electrode 25c ... Land part 27 ... Connection bump 28, 128, 228 .. Surface electrode for common electrode (second electrode)
28a, 128a, 228a ... internal connection part 28b, 128b, 228b ... external connection part 28c, 128c, 228c ... connection part 30 ... displacement element 32 ... common electrode connection bump 34 ...・ Penetration conductor (via hole)
60 ... Signal transmission part (wiring board)
60c ... Wiring 70 ... (head mounting) frame 72 ... head group 80a ... paper feed roller 80b ... collection roller 82a ... guide roller 82b ... transport roller 88 ... control Part P: Printing paper

Claims (13)

A piezoelectric ceramic layer, a plurality of first and second electrodes disposed on one main surface of the piezoelectric ceramic layer, and the plurality of first electrodes on the other main surface of the piezoelectric ceramic layer A third electrode disposed to face the electrode, and a through conductor that penetrates the piezoelectric ceramic layer and electrically connects the second electrode and the third electrode. A flat plate-shaped piezoelectric substrate including:
When the piezoelectric substrate is viewed in plan view,
The second electrode includes an internal connection portion connected to the through conductor, an external connection portion narrower than the internal connection portion, and a connection electrically connecting the internal connection portion and the external connection portion. The connection portion is thinner than the internal connection portion and the external connection portion, and the second electrode and the outside are electrically connected at the external connection portion. A characteristic piezoelectric substrate.   Each of the plurality of first electrodes includes a first electrode body and a land portion, and the first electrode body is thinner than the land portion, and the plurality of first electrodes and the outside The piezoelectric substrate according to claim 1, wherein the land portion is electrically connected.   The piezoelectric substrate according to claim 2, wherein a width of the external connection portion and a width of the land portion are substantially the same.   The piezoelectric substrate according to claim 3, wherein a shape of the external connection portion and a shape of the land portion are substantially the same.   The connection part and the first electrode body are made of substantially the same material, and the internal connection part, the external connection part, and the land part are made of substantially the same material. The piezoelectric substrate in any one of 2-4.   The thickness of the piezoelectric substrate is 100 μm or less, the width of the internal connection part is 300 μm or more, and the internal connection part and the external connection part are separated by 300 μm or more. The piezoelectric substrate according to any one of the above.   The portions where the plurality of first electrodes and the outside are electrically connected to each other are disposed at the peripheral edge of the plurality of first electrodes, and the second electrode and the outside are electrically connected to each other. The piezoelectric substrate according to claim 1, wherein a portion to be connected is disposed at a peripheral edge portion of the external connection portion.   The planar shape of the piezoelectric substrate is long in one direction, the external connection portion and the internal connection portion are arranged side by side in the one direction, and the connection portion extends in the one direction. The piezoelectric substrate according to claim 1.   The second electrode is repeatedly arranged in the one direction in the order of the internal connection portion, the connection portion, the external connection portion, the other connection portion, and the other internal connection portion. The piezoelectric substrate according to claim 8. A piezoelectric substrate according to any one of claims 1 to 9, and a plurality of piezoelectric substrates arranged facing the piezoelectric substrate and electrically connected to the plurality of first electrodes and the second electrode An assembly including a wiring board including wiring,
The planar shape of the wiring board is long in one direction and has a pair of sides along the one direction.
The external connection portion extends along each of the pair of sides, and the second electrode and the wiring are electrically connected in the external connection portion along the pair of sides. An assembly characterized by being connected.   A liquid discharge head in which a plurality of discharge holes and a flow path member including a plurality of pressurizing chambers respectively connected to the plurality of discharge holes are joined to the piezoelectric substrate according to claim 1. The liquid discharge head is characterized in that by applying a voltage between the first electrode and the second electrode, the piezoelectric ceramic layer is deformed to pressurize the liquid in the pressurizing chamber. .   A flow path member including a plurality of discharge holes and a plurality of pressurizing chambers respectively connected to the plurality of discharge holes, and the assembly according to claim 10, wherein the flow path member and the piezoelectric substrate Is a liquid discharge head to which the piezoelectric ceramic layer is deformed by applying a voltage between the first electrode and the second electrode, and pressurizes the liquid in the pressurizing chamber. A liquid discharge head.   13. A recording apparatus comprising: the liquid discharge head according to claim 11; a transport unit that transports a recording medium to the liquid discharge head; and a control unit that controls the liquid discharge head.

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