JP6401077B2 - Liquid discharge head and recording apparatus using the same - Google Patents

Description

  The present invention relates to a liquid discharge head and a recording apparatus using the same.

  Conventionally, as a printing head, for example, an inkjet head (liquid ejection head) that performs various types of printing by ejecting liquid onto a recording medium is known. A flow path member having an ink jet head connected to the manifold and the manifold via a plurality of pressurizing chambers, and a plurality of individual electrodes and a plurality of individual electrodes provided to cover the pressurizing chambers, respectively. A piezoelectric actuator substrate having a plurality of displacement elements including a common electrode facing each other and a piezoelectric ceramic layer sandwiched between them is known (for example, see Patent Document 1). reference.). In this liquid ejection head, the pressurizing chambers connected to the plurality of ejection holes are arranged in a matrix, and the displacement elements of the piezoelectric actuator substrate provided so as to cover the chambers are displaced by deformation of the piezoelectric body. Ink is ejected from the ejection holes.

JP 2003-305852 A

  However, when the displacement element is driven in the liquid ejection head described in Patent Document 1 to drive the liquid, stress is applied to the piezoelectric body around the displacement element, and when ejection is repeated, the piezoelectric body around the displacement element As a result, the shape becomes different from the initial shape. As a result, a pressure different from the initial state is applied to the displacement element, resulting in a problem of driving deterioration in which the displacement is reduced.

  Accordingly, it is an object of the present invention to provide a liquid discharge head and a recording apparatus that are unlikely to cause drive deterioration.

The liquid discharge head of the present invention includes a flow path member including a plurality of discharge holes and a plurality of pressurization chambers respectively connected to the plurality of discharge holes, and the flow path member includes the plurality of pressurization chambers. A piezoelectric substrate laminated so as to cover the piezoelectric substrate, wherein the piezoelectric substrate is laminated on the diaphragm, and is disposed on the flow path member side. A piezoelectric layer, and a plurality of pairs of electrodes that are disposed to face the plurality of pressurizing chambers and sandwich the piezoelectric layer therebetween, the piezoelectric layer and the vibration Each of the plates is applied with a compressive stress in the plane direction, and the compressive stress in the plane direction applied to the piezoelectric layer is smaller than the compressive stress in the plane direction applied to the diaphragm. To do.
In addition, the liquid discharge head of the present invention includes a flow path member including a plurality of discharge holes and a plurality of pressurizing chambers connected to the plurality of discharge holes, and the flow path member includes the plurality of pressurizing chambers. A liquid discharge head comprising: a piezoelectric substrate laminated to cover the pressure chamber, wherein the piezoelectric substrate is laminated on the vibration plate and disposed on the flow path member side. And a plurality of pairs of electrodes that are arranged to face the plurality of pressurizing chambers and sandwich the piezoelectric layer therebetween, the piezoelectric layer The applied planar compressive stress is smaller than the planar compressive stress applied to the diaphragm, the piezoelectric layer has a tetragonal perovskite crystal structure at room temperature, and the diaphragm is at room temperature. It has a cubic perovskite crystal structure The degree of orientation of the tetragonal c-axis in the direction perpendicular to the principal surface of the piezoelectric substrate in an inactive portion not sandwiched between the pair of electrodes of the piezoelectric layer is Vc = I (002) / {I (002) + I (200)} (where I (002) is the diffraction intensity of the (002) plane of the tetragonal crystal in the X-ray diffraction measurement, and I (200) is the (200) plane The diffraction intensity), Vc is 0.5 or less.

  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 liquid discharge head.

  According to the liquid discharge head of the present invention, it is difficult to cause drive deterioration.

(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 first 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. It is a longitudinal cross-sectional view along the VV line of FIG.

  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 moves the printing paper P relative to the liquid ejection head 2 by transporting the printing paper P that is a recording medium from the transporting roller 80 a to the transporting roller 80 b. The control unit 88 controls the liquid ejection head 2 based on image and character data to eject liquid toward the printing paper P, land droplets on the printing paper P, and print 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. One is arranged between each of the three liquid ejection heads 2 at a position shifted in 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. In FIGS. 3 and 4, for easy understanding of the drawings, 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. FIG. 5 is a longitudinal sectional view taken along line VV in FIG.

  The liquid discharge head 2 may include a reservoir and a metal casing in addition to the head main 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 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 joined to the upper surface of the flow path member 4, and each displacement element 30 is disposed on the pressurizing chamber 10. The piezoelectric actuator substrate 21 is connected to a signal transmission unit 60 that supplies a signal to each displacement element 30. 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 two signal transmission units 60 are connected to the piezoelectric actuator substrate 21. The electrodes formed on the signal transmission unit 60 that are electrically connected to the piezoelectric actuator substrate 21 are arranged in a rectangular shape at the end of the signal transmission unit 60. The two signal transmission parts 60 are connected so that each end comes to the center part in the short direction of the piezoelectric actuator substrate 21. The two signal transmission parts 60 extend from the central part toward the long side of the piezoelectric actuator substrate 21.

  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.

  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.

  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 path 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 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. 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 has a plurality of pressurizing chambers 10 arranged two-dimensionally. 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. Therefore, 16 pressurizing chamber rows 11 are provided for one manifold 5, and 32 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.

  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 that 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. In addition, 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 in adjacent pressurizing chamber rows 11 may be arranged in a staggered manner so as to be positioned between each other. By doing so, the distance between the pressurizing chambers 10 belonging to the adjacent pressurizing chamber rows 11 becomes longer, so that 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. Each of the discharge holes 8 connected to the pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 opens to the different partition wall 15 side 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 holes 8 respectively connected to the adjacent sub-manifolds 5b via the pressurizing chamber rows 11 are arranged so as not to overlap each other in the longitudinal direction of the liquid discharge head 2, the pressurizing chamber 10 and the discharge holes 8 are arranged. Since crosstalk between the flow paths connecting the two 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 pressure chambers 10 connected to one manifold 5 constitute a pressure chamber group (the same range as the displacement element group 31), and one flow path member 4 has two manifolds 5. Therefore, 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 of the pressurizing chamber 10 facing the corner to which the individual supply channel 14 is connected, the channel connected to the discharge hole 8 opened in the discharge hole surface 4-1 on the lower surface of the channel member 4. 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 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. 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.

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. 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. The individual electrodes 25 constitute individual electrode rows and individual electrode groups in the same manner as the pressurizing chamber 10. Further, on the upper surface of the piezoelectric actuator substrate 21, a common electrode surface electrode 28 as a second electrode electrically connected to the common electrode 24 as a third electrode through a via hole (not shown) is formed. Has been. The common electrode surface electrode 28 exists along the outer periphery of the piezoelectric actuator substrate 21, and the individual electrode 25 is disposed between the outer periphery where the individual electrode 25 is disposed on the inner side and the individual electrode 25 on the inner side of the outer periphery. And a protruding portion extending along the row direction in which the are arranged. Details of the shape of the common electrode surface electrode 28 will be described later. The common electrode surface electrode 28 and the common electrode 24 are electrically connected through a conductor in a via hole (not shown) disposed in the piezoelectric ceramic layer 21b.

  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 portions constituting the individual flow path 12 are close to each other. 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 ceramic layers 21a and 21b. These ceramic layers 21a and 21b each have a thickness of about 20 μm. The thickness from the lower surface of the ceramic layer 21a of the piezoelectric actuator substrate 21 to the upper surface of the ceramic layer 21b is about 40 μm. Both of the ceramic layers 21 a and 21 b extend so as to straddle the plurality of pressure chambers 10. Ceramic layer 21b is, for example, having ferroelectricity, made of lead zirconate titanate (PZT), NaNbO ₃ system, BaTiO ₃ system, (BiNa) NbO ₃ system, a piezoelectric ceramic material, such as BiNaNb ₅ O ₁₅ system It is a piezoelectric ceramic layer (hereinafter sometimes referred to as a piezoelectric ceramic layer 21b). The ceramic layer 21a functions as a diaphragm (hereinafter, may be referred to as a diaphragm 21a), and does not necessarily have to be a piezoelectric body, and may be a paraelectric body, but is simultaneously fired with the piezoelectric ceramic layer 21b. When performing the above, it is preferable to use a ceramic having a composition close to that of the piezoelectric ceramic layer 21b.

  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 materials for the common electrode 24 and the individual electrodes 25, conductive materials such as Au, Ag, Pd, Pt, Cu, Al, Ni, and alloys thereof can be used. As described above, the individual electrode 25 includes the individual electrode main body 25a disposed at a 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 bump 26 is formed at a portion of one end of the extraction electrode 25b that is extracted outside the region facing the pressurizing chamber 10. On the common electrode 28, common electrode connection bumps (not shown) are formed. The connection bumps 26 and the common electrode connection bumps are made of, for example, silver-palladium containing glass frit, and have a convex shape with a thickness of about 15 μm. The connection bumps 26 and the common electrode connection bumps are electrically joined to the electrodes provided in the signal transmission unit 60. 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 formed over almost the entire surface in the region between the 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 2 μm. The common electrode 24 is a via hole (not shown) formed through the piezoelectric ceramic layer 21b on 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. ), And is 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. Function 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, since the ceramic layer 21a which is an inactive layer is not affected by the electric field, the ceramic layer 21a does not spontaneously shrink and tries to suppress displacement in the surface direction of the active portion. As a result, there is a difference in distortion in the plane direction between the piezoelectric ceramic layer 21b and the ceramic layer 21a, and the piezoelectric ceramic layer 21b is deformed so as to protrude 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 there is a discharge request, and then a predetermined potential is set. At this timing, the potential is set again. Thereby, at the timing when the individual electrode 25 becomes low potential, the ceramic layers 21a and 21b return to the original (flat) shape (beginning), and the volume of the pressurizing chamber 10 is in an initial state (state where the potentials of both electrodes are different). ) And increase. 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 time of the natural vibration period of the liquid in the pressurizing 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 pressurizing chamber 10 is greatly affected by the physical properties of the liquid and the shape of the pressurizing chamber 10, but besides that, the physical properties of the piezoelectric actuator substrate 21 and the flow path connected to the pressurizing chamber 10 Also affected by the characteristics of.

  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.

  One of the causes of drive deterioration in the pulling operation basically as described above is that when the diaphragm 21a is made of a piezoelectric ceramic material, the active portion sandwiched between the individual electrode body 25a and the common electrode 24 is used. When a tensile stress is repeatedly applied to the diaphragm 21a in the overlapping portion, ferroelastic domain switching occurs, and the portion extends in the plane direction. As a result, even when no voltage is applied to the active portion, the displacement element 30 is slightly bent toward the pressurizing chamber. Since the amount of displacement when a voltage is applied is a difference from this state, the amount of displacement is reduced by preliminarily bending.

  The deformation of the vibration plate 21a mainly occurs in a standby state in driving that is maintained in the deformed state. By continuing the standby state, the c domain facing in the thickness direction of the diaphragm 21a is domain-switched in the surface direction of the piezoelectric actuator substrate 21 due to deformation due to displacement, so that the displacement element 30 is in a stable state in a bent state. Try to be.

In order to make such ferroelastic domain switching difficult to occur, it is effective to apply a compressive stress to the diaphragm 21a. In order to do so, for example, by using the flow path member 4 having a thermal expansion coefficient larger than that of the piezoelectric ceramic layers 21a and 21b, the piezoelectric actuator substrate 21 and the flow path member 4 are heated and joined. What is necessary is just to perform by the difference in the amount of shrinkage at the time of temperature drop.

  However, if it does so, a compressive stress will act also on the active part of the piezoelectric ceramic layer 21b, the piezoelectric constant of the active part will become low, and the amount of displacement will become small. Therefore, in the present invention, the compressive stress applied to the piezoelectric ceramic layer 21b and the diaphragm 21a is changed. By applying a large compressive stress to the diaphragm 21a, the drive deterioration is suppressed, the compressive stress applied to the piezoelectric ceramic layer 21b is reduced (in some cases, a tensile stress is added), and the piezoelectric constant is kept high.

  Specifically, a piezoelectric actuator substrate 21 having a convex curve toward the flow path member 4 is manufactured and bonded to the flow path member 4 so that the piezoelectric ceramic layer 21b has a compressive stress applied to the diaphragm 21a. Increase the applied compressive stress. In order to increase the compressive stress applied to the diaphragm 21a, it is preferable to apply the compressive stress due to the above-described difference in thermal expansion coefficient.

  In order to manufacture the warped piezoelectric actuator substrate 21, the firing shrinkage amount of the piezoelectric ceramic layer 21b may be made larger than the firing shrinkage amount of the diaphragm 21a. For this purpose, it is preferable to change the material composition between the diaphragm 21a and the piezoelectric ceramic layer 21b. This can also be done by changing the packing of the material in the green sheet before firing, but doing so lowers the packing before firing of the piezoelectric ceramic layer 21b that increases the shrinkage, and the piezoelectric ceramic layer 21b after firing is reduced. The porosity increases, and the characteristics and reliability of the piezoelectric ceramic layer 21b decrease. In addition, the variation in the amount of warpage increases, and the variation in the displacement element 50 may increase.

In order to change the shrinkage rate, for example, Ag is added to the piezoelectric ceramic layer 21b with respect to the composition of the piezoelectric ceramic layer 21b and the vibration plate 21a mainly composed of lead zirconate titanate to thereby shrink the piezoelectric ceramic layer 21b. The rate can be increased. In addition, the shrinkage rate may be increased by adding Bi or BiFeO ₃ to lead zirconate titanate.

  The drive deterioration may also occur when the diaphragm 21a is made of, for example, a paraelectric ceramic material that does not have piezoelectricity. This is because the same ferroelastic domain switching occurs in a portion (inactive portion) not sandwiched between the electrodes of the piezoelectric ceramic layer 21b. As the active portion contracts in the surface direction, a tensile stress is applied to the inactive portion existing around the active portion, and ferroelastic domain switching occurs, and the portion extends. As a result, the active part receives compressive stress from the surrounding inactive part, and is in a slightly contracted state even when no voltage is applied. When the active portion is contracted in advance, the amount of displacement is reduced.

  In order to make it difficult for the ferroelastic domain switching in the inactive portion of the piezoelectric ceramic layer 21b to occur, the domain state of the inactive portion is set to a stable state that does not change (almost) even when tensile stress is applied. What is necessary is just to set it as the state where more c-axis was orientated by the surface direction.

In particular, when a lead-free dielectric material that is difficult to increase both the piezoelectric constant and the coercive electric field is used as a material constituting the diaphragm 21a and the piezoelectric ceramic layer 21b, the inertness of the piezoelectric ceramic layer 21b is thus obtained. The effect of improving the durability due to the portion having a tetragonal c-axis oriented more in the plane direction becomes remarkable. Specific examples of the materials include niobic acid compounds (Nb acid alkali compounds (NAC) such as sodium Nb acid, Nb alkaline earth compounds (NAEC) such as Nb acid barium), titanic acid compounds (barium titanate). (BT), calcium titanate (CT), and the like) and zirconate-based compounds (barium zirconate (BZ), calcium zirconate (CZ), and the like).

As an example of the lead-free piezoelectric ceramic material constituting the piezoelectric ceramic layer 21b, at least one of Nb, Sb and Ta, at least one of Cu, Mg and Zn, Ba, Ti, Sn, Zr and And a barium titanate-based dielectric material containing Bi. Such a barium titanate-based piezoelectric ceramic material is preferable because it has a high dielectric constant and a high coupling coefficient, so that a high piezoelectric strain constant (hereinafter sometimes simply referred to as d ₃₁ ) can be obtained.

  Further, when a material further containing Ca, that is, a barium titanate-based material in which a part of the A site is substituted with Ca, an orthorhombic-tetragonal phase transition temperature (hereinafter, O- T-phase transition temperature) may be further shifted to a lower temperature side, and the temperature range of the tetragonal crystal, that is, the ferroelectric phase that exhibits piezoelectricity, can be expanded. Can be further stabilized, which is preferable.

Specifically, the barium titanate-based piezoelectric ceramic material suitable for the piezoelectric ceramic layer 21b is represented by the following composition formula.
_{(Ba 1-a-b Ca} a Bi b) γ (Ti 1-c-d-e Zr c Sn d (M1 2/3 M2 1/3) e) O 3 ··· ( Equation 1)
However, M1 is at least one of Cu, Mg, and Zn, and M2 is at least one of Nb, Sb, and Ta. Moreover, a, b, c, d, e, and γ satisfy the following relationship.
0 ≦ a ≦ 0.110
0 <b ≦ 0.014
0 ≦ (c + d) ≦ 0.090
0 <e ≦ 0.015
0.96 ≦ γ ≦ 1.04
Here, γ represents the ratio A / B of the A site and B site of the perovskite structure represented by the general formula ABO ₃ . In addition, the O ratio may vary.

By adopting such a composition, a piezoelectric constant, for example, d ₃₁ is as high as 100 pm / V or more, and a tetragonal crystal that is a ferroelectric phase can stably exist over a wide temperature range (for example, room temperature to 100 ° C.). It becomes.

When the above-described barium titanate-based piezoelectric ceramic material is used for the piezoelectric ceramic layer 21b, the paraelectric ceramic material constituting the vibration plate 21a has a composition close to that of the above-described barium titanate-based piezoelectric ceramic material. It is preferable for simultaneous firing of the piezoelectric ceramic layer 21b and the diaphragm 21a. In this case, a barium titanate-based paraelectric ceramic material suitable for the diaphragm 21a is specifically represented by the following composition formula.
(Ba _1- vw _Srv Bi _w ) _δ (Ti _1-x-yz Zr _x Sn _y (M3 _2/3 M4 _1/3 ) _z ) O ₃ (Formula 2)
However, M3 is at least one of Cu, Mg, and Zn, and M4 is at least one of Nb, Sb, and Ta. Moreover, v, w, x, y, z, and δ satisfy the following relationship.
0.10 ≦ v ≦ 0.70
0 <w ≦ 0.014
0 ≤ x ≤ 0.090
0 ≤ y ≤ 0.090
0 <z ≦ 0.015
0.96 ≦ δ ≦ 1.04
Here, δ represents the ratio A / B of the A site and B site of the perovskite structure represented by the general formula ABO ₃ . In addition, the O ratio may vary.

  With such a composition, the barium titanate-based paraelectric ceramic material constituting the vibration plate 21a has a ferroelectric-paraelectric phase transition temperature Tc of room temperature or lower. Further, the barium titanate-based piezoelectric ceramic material constituting the piezoelectric ceramic layer 21b represented by the above formula 1 has a low thermal expansion coefficient at a high temperature (for example, 600 to 800 ° C.) and a low temperature (for example, 25 to 200 ° C.), the coefficient of thermal expansion is large. Due to the behavior of the thermal expansion coefficient, the warp of the piezoelectric actuator substrate 21 is reduced. Further, since the thermal expansion coefficient of the diaphragm 21a at a low temperature is larger than the thermal expansion coefficient of the piezoelectric ceramic layer 21b, the compressive stress applied to the piezoelectric ceramic layer 21b becomes larger than the compressive stress applied to the diaphragm 21a. Tensile stress is applied in the plane direction of the piezoelectric ceramic layer 21b, and the piezoelectric ceramic layer 21b is in a state in which more tetragonal c-axes are aligned in the plane direction.

The barium titanate-based paraelectric ceramic material having the composition represented by Formula 2 has a higher Young's modulus and is less likely to be deformed than the barium titanate-based piezoelectric ceramic material having the composition represented by Formula 1 above. The drive deterioration can be suppressed as compared with the case where the vibration plate 21a is formed of a piezoelectric body.

  Each of the piezoelectric ceramic layer 21b and the diaphragm 21a contains 0.1 to 0.5% by mass of Cu in terms of CuO with respect to the components represented by the above composition formulas (Formula 1 and Formula 2). By doing so, sintering can be performed at a lower temperature, and simultaneous firing with an electrode material having a low melting point becomes possible. Further, even when fired in the air, the reduction reaction hardly occurs, the deterioration of the piezoelectric characteristics can be suppressed, the variation in the ceramic characteristics can be suppressed, and the ceramic can be stably manufactured.

  Further, the barium titanate-based material constituting the piezoelectric ceramic layer 21b and the diaphragm 21a may contain elements such as Mn, Co, and Cr in addition to the above-described elements. By containing a small amount of such an element, the sinterability, temperature characteristics of relative permittivity, and heat resistance of the barium titanate material are improved.

  The barium titanate-based material constituting the piezoelectric ceramic layer 21b and the diaphragm 21a may contain elements such as Si, Ce, Al, Na, Fe, Ni, and Mo as inevitable impurities in the process. In this embodiment, you may contain these elements in 0.5 mass% or less in total. These elements do not affect the characteristics of the barium titanate material as long as the total content in the barium titanate material is 0.5% by mass or less.

  The composition of the ceramic material and the content of impurity elements can be confirmed by elemental analysis such as X-ray fluorescence analysis or ICP emission spectroscopic analysis.

  Piezoelectric actuator substrates 21 having different shrinkage rates were produced between the piezoelectric ceramic layer 21b and the diaphragm 21a, and the liquid ejection head 2 was produced using the piezoelectric actuator substrate 21 to evaluate the characteristics.

Example 1
As the piezoelectric ceramic layer 21b and the vibration plate _{21a, Pb 1-x-y} Sr x Ba y (Zn 1/3 Sb 2/3) as a common basic composition _{a (Ni 1/2 Te 1/2) b} Zr 1- _a-b-c Ti _c O ₃ + αPb _1/2 NbO ₃ (where 0 ≦ x ≦ 0.14, 0 ≦ y ≦ 0.1
4, 0.05 ≦ a ≦ 0.1, 0.002 ≦ b ≦ 0.01, 0.44 ≦ c ≦ 0.50, α = 0.1 to 1.0 mass%) Using. The amount of Ag shown in Table 1 was added to the piezoelectric ceramic layer 21b with respect to 100 parts by mass of this composition. Ag was not added to the diaphragm 21a.

  The piezoelectric actuator substrate 21 was produced as follows. The Ag-Pd paste used as the common electrode 24 was printed on the green sheet used as the vibration plate 21a, and the green sheet used as the piezoelectric ceramic layer 21b was stacked to produce a laminate. In the Ag—Pd paste, the piezoelectric ceramic particles having the above basic composition were added as a co-material so as to suppress the diffusion of Ag in the common electrode 24. After firing the laminate, the individual electrodes 25 were baked.

  A piezoelectric actuator substrate 21 having a size of 50 mm × 25 mm was produced. The piezoelectric actuator substrate 21 was placed on a flat surface with the convex side (vibrating plate 21a side) facing up, and the height of the highest portion was measured. A value obtained by subtracting the thickness of the piezoelectric actuator substrate 21 from the value was used as the warp of the piezoelectric actuator substrate 21.

  The piezoelectric actuator substrate 21 was heated and bonded to the flow path member 4 at 120 ° C. to produce the liquid discharge head 2, and the piezoelectric ceramic layer 21 b was polarized by a high temperature polarization method. Compressive stress, displacement (when applying a voltage of 1 V / μm), and drive deterioration were measured. The measurement results are shown in Table 1. Sample No. For No. 1, the piezoelectric ceramic layer 21b and the diaphragm 21a have the same composition but warped to one side due to manufacturing variations, so the convex side was bonded to the flow path member 4.

  The stress was measured by measuring X-ray stress on the surface of the liquid ejection head 2 on the piezoelectric ceramic layer 21b side and on the surface of the diaphragm 21a. On the piezoelectric ceramic layer 21 side, the surface from which the individual electrode 25 was removed was measured, and on the diaphragm 21a side, the flow path member 4 at the measurement site was removed so that the surface of the diaphragm 21a was exposed, and the exposed surface was exposed. The surface of the diaphragm 21a was measured. The compressive stress of the piezoelectric ceramic layer 21b was subtracted from the compressive stress of the diaphragm 21a to obtain a stress difference. The shrinkage rate of each layer is not the shrinkage rate of the manufactured piezoelectric actuator substrate 21 but the shrinkage rate when the green sheet of each layer is fired. The drive deterioration is a ratio in which the displacement amount is reduced from the initial displacement amount after 100,000 cycles after the voltage is adjusted so that the displacement amount of each sample becomes 90 nm. In addition, the porosity of each layer was 0.1% or less because the raw material packing was made high in a green sheet state.

  The amount of displacement was increased by reducing the compressive stress applied to the piezoelectric ceramic layer 21b. This is presumably because the piezoelectric constant of the piezoelectric ceramic layer 21b has increased. The compressive stress applied to the diaphragm 21a is almost the same for each sample. However, if the compressive stress applied to the piezoelectric ceramic layer 21b is small, the voltage for obtaining a desired amount of displacement can be lowered. The drive deterioration became 3% or less by making the difference in compressive stress 70 MPa or more.

  If the warpage amount of the piezoelectric actuator substrate 21 exceeds 350 μm, the possibility of cracking increases when the piezoelectric actuator substrate 21 is bonded to the flow path member 4. Therefore, the warpage amount is preferably 350 μm or less.

(Example 2)
Composition formula as a piezoelectric ceramic layer _{21b (Ba 1-a-b} Ca a Bi b) γ (Ti 1-c-d-e Zr c Sn d (Cu 2/3 Sb 1/3) e) O 3 ( where γ = 1.0, a = 0.0698, b = 0.0035, c = 0.0558, d = 0.140, e = 0.0035) CuO is 0.25% by mass. The one (hereinafter sometimes referred to as F1) was used. Further, the composition formula as the diaphragm _{21a (Ba 1-v-w} Sr v Bi w) δ (Ti 1-x-y-z Zr x Sn y (M3 2/3 M4 1/3) z) O 3 of v , W, x, y, z, M3, and M4 were those having compositions as shown in Table 2 (hereinafter sometimes referred to as P1 to P3). Note that δ was set to 1.0.

  The piezoelectric actuator substrate 21 was produced as follows. An Ag—Pd paste (Ag: Pd ratio is 3: 7 in terms of mass ratio) that is a common electrode 24 is printed on a green sheet that is to be a diaphragm 21a, and a green sheet that is to be a piezoelectric ceramic layer 21b is stacked to form a laminate. Produced. All the green sheets had a thickness of 30 μm. The laminate was fired at 1300 ° C. for 3 hours in the air atmosphere, and then the individual electrode 25 was baked. As a comparative example, a material using the material of F1 for the diaphragm 21a was also manufactured (Sample No. 4).

  The crystal structures of the piezoelectric ceramic layer 21b and the diaphragm 21a were obtained by performing X-ray diffraction (XRD) measurement on the surface of the fired laminated body on the piezoelectric ceramic layer 21b side and the surface on the diaphragm 21a side, respectively. This was confirmed by analyzing the X-ray diffraction pattern. F1 was a tetragonal crystal structure, and P1 to P3 were cubic perovskite crystal structures.

  The Curie temperatures of P1 to P3 and F1 were confirmed by measuring the temperature dependence of the dielectric constant using test pieces obtained by firing the green sheets of P1 to P3 and F1 individually. The Curie temperature (Tc) of F1 was 100 ° C. Table 2 shows the Curie temperatures (Tc) of P1 to P3.

  A piezoelectric actuator substrate 21 having a size of 50 mm × 25 mm was produced. The piezoelectric actuator substrate 21 was placed on a flat surface with the convex side (vibrating plate 21a side) facing up, and the height of the highest portion was measured. A value obtained by subtracting the thickness of the piezoelectric actuator substrate 21 from the value was used as the warp of the piezoelectric actuator substrate 21.

  The piezoelectric actuator substrate 21 was heated and bonded at 150 ° C. using the flow path member 4 and an epoxy adhesive to produce the liquid discharge head 2, and the piezoelectric ceramic layer 21 b was polarized by a high temperature polarization method. The compressive stress, c-axis orientation degree Vc in the inactive part, and driving deterioration were measured.

The stress was measured by measuring X-ray stress on the surface of the liquid ejection head 2 on the piezoelectric ceramic layer 21b side and on the surface of the diaphragm 21a. On the piezoelectric ceramic layer 21b side, the surface from which the individual electrode 25 was removed was measured, and on the diaphragm 21a side, the flow path member 4 at the measurement site was removed so that the surface of the diaphragm 21a was exposed, and the exposed surface was exposed. The surface of the diaphragm 21a was measured. The compressive stress of the piezoelectric ceramic layer 21b was subtracted from the compressive stress of the diaphragm 21a to obtain a stress difference. Confirmation of the degree of orientation c of the c-axis in the inactive part is carried out by performing local X-ray diffraction measurement of the inactive part and calculating the following from the peak intensity of the (200) plane and (002) plane of the obtained X-ray diffraction pattern. Calculated by the formula.
Vc = I (002) / {I (200) + I (002)}
The measurement of the inactive part by local X-ray diffraction was performed by irradiating the surface of the inactive part 80 μm away from the edge of the individual electrode 25 with CuKα rays with a collimator diameter of 20 μm.

  The drive deterioration is caused by applying a voltage having a drive voltage waveform of ± 1.83 kV / cm and a frequency of 2 kHz to the common electrode 24 at room temperature (5-35 ° C.) and driving the displacement element 30 for 10 billion cycles. This is the rate at which the displacement amount has decreased from the initial displacement amount. The results are shown in Table 3.

  Sample No. In Nos. 5 to 7, paraelectric P1 to P3 are used for the diaphragm 21a, and the compressive stress applied to the piezoelectric ceramic layer 21b is smaller than the compressive stress applied to the diaphragm 21a, so that in the inactive portion of the piezoelectric ceramic layer 21b. Vc was 0.5 or less, and the drive deterioration was 8.0% or less.

  On the other hand, sample No. 1 using the same F1 material as the piezoelectric ceramic layer 21b as the diaphragm 21a. In No. 4, the compressive stress applied to the piezoelectric ceramic layer 21b and the compressive stress applied to the diaphragm 21a were approximately the same, and the drive deterioration was as large as 17.5%.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... Head main body 4 ... Channel member 4a-4l ... (channel 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 ... Pressure chamber row 12 ... Individual channel 14 ... Individual supply channel 15 ... Partition wall 16 ... Dummy pressurizing chamber 21 ... Piezoelectric actuator substrate 21a ... Piezoelectric Ceramic layer (diaphragm)
21b ... Piezoelectric ceramic layer 24 ... Common electrode 25 ... Individual electrode 25a ... Individual electrode body 25b ... Extraction electrode 26 ... Connection bump 28 ... Common electrode surface electrode 30 ... -Displacement element 60 ... Signal transmission unit 70 ... (Head mounted) frame 72 ... Head group 80a ... Paper feed roller 80b ... Collection roller 82a ... Guide roller 82b ... Conveyance roller 88: Control unit P: Printing paper

Claims (5)

A flow path member having a plurality of discharge holes and a plurality of pressurization chambers respectively connected to the plurality of discharge holes, and the flow path member are stacked so as to cover the plurality of pressurization chambers. A liquid discharge head comprising a piezoelectric substrate,
The piezoelectric substrate is disposed so as to face the vibration plate disposed on the flow path member side, the piezoelectric layer laminated on the vibration plate, and the plurality of pressurizing chambers, respectively, A plurality of pairs of electrodes sandwiching the piezoelectric layer, and
Both the piezoelectric layer and the diaphragm are subjected to a planar compressive stress, and the planar compressive stress applied to the piezoelectric layer is a planar compressive force applied to the diaphragm. A liquid discharge head characterized by being smaller than stress.   2. The liquid discharge head according to claim 1, wherein a compressive stress in a plane direction applied to the piezoelectric layer is 70 MPa or less smaller than a compressive stress in a plane direction applied to the diaphragm.   The liquid ejection head according to claim 1, wherein the piezoelectric layer and the diaphragm are made of ceramics and have a porosity of 0.1% or less. A flow path member having a plurality of discharge holes and a plurality of pressurization chambers respectively connected to the plurality of discharge holes, and the flow path member are stacked so as to cover the plurality of pressurization chambers. A liquid discharge head comprising a piezoelectric substrate,
The piezoelectric substrate is disposed so as to face the vibration plate disposed on the flow path member side, the piezoelectric layer laminated on the vibration plate, and the plurality of pressurizing chambers, respectively, A plurality of pairs of electrodes sandwiching the piezoelectric layer, and
The compressive stress in the plane direction applied to the piezoelectric layer is smaller than the compressive stress in the plane direction applied to the diaphragm,
The piezoelectric layer has a tetragonal perovskite type crystal structure at room temperature, and the diaphragm has a cubic perovskite type crystal structure at room temperature,
In the inactive portion of the piezoelectric layer that is not sandwiched between the pair of electrodes, the degree of orientation of the tetragonal c-axis in the direction perpendicular to the main surface of the piezoelectric substrate is expressed as Vc = I (002) / {I (002) + I (200)} (where I (002) is the diffraction intensity of the (002) plane of the tetragonal crystal in the X-ray diffraction measurement, and I (200) is the diffraction of the (200) plane. Strength)
Liquid discharge head you wherein the Vc is 0.5 or less.   A recording apparatus comprising: the liquid discharge head according to claim 1; a transport unit that transports a recording medium to the liquid discharge head; and a control unit that controls the liquid discharge head. apparatus.

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