JP2008173867A - Liquid droplet discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharge device capable of keeping a large number of nozzles and pressure chambers arranged in high density with a simple constitution and applying to draw and hit by enlarging the volume of the pressure chamber by applying voltage, and to enlarge the displace quantity of the same. <P>SOLUTION: In the liquid droplet discharge device, a piezoelectric actuator 7 has a structure constituted by extending a plurality of piezoelectric sheets 7A, 7B over a plurality of rows of the pressure chambers 3 respectively and laminating and integrating the plurality of piezoelectric sheets 7A, 7B in the row direction of the pressure chambers 3. Pairs of electrodes 5, 6 is respectively oriented perpendicularly to the faces of the pressure chambers 3 between the plurality of piezoelectric sheets 7A, 7B, piezoelectric active portions S1 are polarized in the reverse direction to the pairs of electrodes 5, 6 and in a direction parallel to the faces of the pressure chambers 3. In the piezoelectric actuator 7, the volume of the pressure chambers 3 is enlarged by the contract displacement of the piezoelectric active portions S1 in a direction perpendicular to the polarizing direction by applying voltage across the pairs of electrodes 5, 6 to provide discharge pressure to ink by stopping applying the voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge device such as an ink jet printer.

  2. Description of the Related Art Conventionally, in an ink jet printer that is one form of a droplet discharge device, an active portion (energy There is one using an ink jet head in which a piezoelectric actuator having a generating means) is joined. As such a piezoelectric actuator, a piezoelectric sheet having an individual electrode pattern formed on the surface and a piezoelectric sheet having a common electrode pattern formed on the surface are alternately laminated, and arranged individually above the portion. A top piezoelectric sheet having a surface electrode for an electrode and a surface electrode for a common electrode formed on a surface thereof, and is fired and integrated, and the surface electrode for the common electrode is formed on the top piezoelectric sheet Are long formed in the direction along the surface (see, for example, Patent Document 1).

  In such a case, there is a demand to increase the number of nozzles and pressure chambers and to increase the resolution by arranging them at high density.

  In addition, as a driving method of such an ink jet head, a so-called pushing method in which the piezoelectric layer is deformed in a convex manner to reduce the volume of the pressure chamber and ink is ejected, and a piezoelectric layer is deformed in a convex manner in the upward direction. There is a so-called striking method that discharges ink (specifically, a method in which the volume of the pressure chamber is first increased and then the pressure chamber is returned to its original volume when the pressure in the pressure chamber changes from negative to positive). Are known. In the case of the striking method, there is an advantage that the driving frequency is high and the driving voltage is low. Therefore, although there is a demand to adopt the striking method, printing is not performed in the case of the striking method. There is a drawback that a voltage must be applied to the piezoelectric layer in a state.

  Therefore, the inventor uses the so-called piezoelectric longitudinal effect in which the piezoelectric actuator of Patent Document 1 exerts on the pressure chamber the displacement of the piezoelectric active portion in the opposing direction of a pair of electrodes positioned parallel to one surface of each pressure chamber. The structure using the so-called piezoelectric lateral effect that exerts on the pressure chamber the displacement of the piezoelectric active portion orthogonal to the opposing direction of the pair of electrodes positioned orthogonal to one surface of each pressure chamber. In this case, the inventors have conceived that the volume of the pressure chamber can be increased when a voltage is applied, and the present invention can be achieved.

By the way, as an ink jet type print head that can easily realize the striking method, a plurality of piezoelectric sheets are stacked in a direction perpendicular to the nozzle row direction with electrodes interposed therebetween, and a plurality of piezoelectric actuators are manufactured. A device including a piezoelectric actuator that is divided and processed for each surface of a pressure chamber communicating with each nozzle is known (for example, see Patent Document 2).
Japanese Patent Laying-Open No. 2006-15539 (FIG. 4) JP-A-5-193129 (FIGS. 4 to 8)

  In the one described in Patent Document 2, a laminated body in which a piezoelectric sheet and an electrode are laminated is disposed along the nozzle row direction, and is cut so that one piezoelectric actuator faces each nozzle. Therefore, it is necessary to arrange one stacked body in one row of nozzles. For this reason, when there are a plurality of nozzles, it is necessary to prepare a stack as many as the number of the nozzles, and to fix each stack on the base, which makes the configuration complicated and increases the number of nozzles and pressure chambers. Cannot be arranged at high density.

  In the present invention, a large number of nozzles and pressure chambers can be arranged with high density with a simple configuration, and the volume of the pressure chambers can be increased by applying a voltage, and the displacement can be reduced. It is an object to provide a droplet discharge device that can be enlarged.

  A first aspect of the present invention is a cavity unit having a plurality of rows of pressure chambers corresponding to a plurality of rows of nozzles for discharging droplets, and a pair of electrodes positioned facing one surface of each pressure chamber. A piezoelectric actuator having a piezoelectric active portion sandwiched therebetween, wherein the piezoelectric actuator extends each of a plurality of piezoelectric sheets over a plurality of rows of the pressure chambers, and the plurality of piezoelectric sheets are arranged in a row direction of the pressure chambers. Each of the pair of electrodes is oriented in a direction perpendicular to the surface of the pressure chamber between the plurality of piezoelectric sheets, and the piezoelectric active portion is formed of the pair of electrodes. By the displacement of the piezoelectric active portion in the direction perpendicular to the polarization direction by applying a voltage between the pair of electrodes, and polarized in a direction parallel to the surface of the pressure chamber. Pressure Characterized in providing a discharge pressure to the ink in the chamber.

  In this case, each of the plurality of piezoelectric sheets extends over a plurality of rows of the pressure chambers, and the plurality of piezoelectric sheets are stacked and integrated in the column direction of the pressure chambers, and each of the pair of electrodes Is oriented in a direction perpendicular to the surface of the pressure chamber between the plurality of piezoelectric sheets, and the piezoelectric active portion is polarized in a direction opposite to the pair of electrodes and in a direction parallel to the surface of the pressure chamber. Since the displacement of the piezoelectric active portion in a direction orthogonal to the polarization direction by applying a voltage between the pair of electrodes, a discharge pressure is applied to the liquid in the pressure chamber. The displacement can be increased, and it is possible to apply a voltage at the time of ejection to perform striking. When applying discharge pressure to the liquid in the pressure chamber, it is only necessary to apply a voltage between the pair of electrodes, which reduces the cost of the power supply system compared to a method in which voltage is constantly applied and voltage application is cut off during discharge. it can. Further, since the plurality of piezoelectric sheets are extended over the plurality of rows of the pressure chambers and the plurality of piezoelectric sheets are stacked in the column direction of the pressure chambers, the plurality of piezoelectric active portions are arranged in the plurality of rows of the pressure chambers. As a result, a large number of nozzles and pressure chambers can be arranged with high density.

  3. The liquid droplet ejection apparatus according to claim 1, wherein the cavity unit includes a partition wall between the plurality of pressure chambers, and the piezoelectric actuator is orthogonal to a stacking direction of the piezoelectric sheets. The piezoelectric actuator and the cavity unit are formed by alternately stacking the plurality of piezoelectric sheets by alternately forming the piezoelectric active portion and the non-displaceable inactive portion in a direction to be moved. It can be set as the structure which joined.

  In this way, the piezoelectric actuator and the cavity unit are joined by the inactive portion and the partition wall that are not displaced, and the piezoelectric active portion is arranged corresponding to the pressure chamber. The liquid is discharged efficiently.

  According to a third aspect of the present invention, in the droplet discharge device according to the second aspect, the cavity unit has a staggered arrangement of the pressure chambers in adjacent rows, and the piezoelectric actuator is in the row in one row. The piezoelectric active portion and the inactive portion in the row adjacent to the piezoelectric active portion may be arranged in a direction orthogonal to the row direction.

  According to this configuration, the piezoelectric actuators in one row of the piezoelectric actuator and the inactive portions in the row adjacent thereto are arranged side by side in a direction perpendicular to the row direction. The pressure chambers are arranged in a staggered arrangement, and a large number of nozzles and pressure chambers can be arranged with higher density.

  According to a fourth aspect of the present invention, in the liquid droplet ejection device according to the first to third aspects, the piezoelectric actuator includes a piezoelectric sheet having one of the pair of electrodes formed on a surface thereof and the piezoelectric sheet on a surface thereof. A piezoelectric sheet on which the other electrode of the pair of electrodes is formed may be alternately stacked in the row direction and integrated.

  If it does in this way, the piezoelectric actuator in Claims 1-3 can be manufactured easily.

  5. The liquid droplet ejection apparatus according to claim 4, wherein the one electrode is positioned corresponding to each pressure chamber, and the other electrode is the two pressure chambers in the adjacent row. It can be set as the structure extended over the position corresponding to.

  In this way, since the other electrode extends across the position corresponding to both pressure chambers in the adjacent row, it is shared for both pressure chambers in the adjacent row, and the piezoelectric active portion is provided. It can be arranged at high density.

  6. The liquid droplet ejection apparatus according to claim 1, wherein one of the pair of electrodes is independent for each of the pressure chambers, and one end thereof is the piezoelectric actuator. It can also be set as the structure exposed to the surface on the opposite side to the said cavity unit.

  In this case, one electrode is independent for each pressure chamber, and one end of the electrode is exposed on the surface opposite to the cavity unit of the piezoelectric actuator. Connection with a connection terminal portion of the substrate can be easily performed.

  According to a seventh aspect of the present invention, in the liquid droplet ejection device according to the sixth aspect, the other electrode of the pair of electrodes may extend across a plurality of rows of the pressure chambers.

  In this case, since the other electrode extends over a plurality of rows of the pressure chambers, it can be shared for the plurality of rows of the pressure chambers, and the piezoelectric active portions can be arranged at high density.

  As described in claim 8, in the droplet discharge device according to claim 6 or 7, a conductive plate having flexibility is provided between the cavity unit and the piezoelectric actuator. The other electrode of the pair of electrodes may be connected to the plate.

  In this way, the electrical connection of the other electrode can be easily realized through the conductive plate without impairing the deformation function of the piezoelectric actuator.

  According to a ninth aspect of the present invention, in the droplet discharge device according to any one of the first to eighth aspects of the present invention, there is flexibility between the cavity unit and the piezoelectric actuator, and liquid in the pressure chamber is not allowed. It can be set as the structure by which the permeable board is provided.

  In this way, it is possible to prevent the liquid in the pressure chamber from penetrating into the piezoelectric actuator and conducting between the pair of electrodes.

  The liquid droplet ejection apparatus according to any one of claims 1 to 9, wherein the piezoelectric sheet is made of lead zirconate titanate, and the pair of electrodes is a silver-palladium-based conductive paste. Can be configured to be screen-printed.

  In this way, the lead zirconate titanate, which is the material of the piezoelectric sheet, and the silver-palladium-based conductive paste, which is the material of the pair of electrodes, have a large difference in thermal shrinkage. The occurrence of bending deformation around the provided portion is suppressed.

  In the present invention, each of the plurality of piezoelectric sheets extends over a plurality of rows of the pressure chambers, and the plurality of piezoelectric sheets are stacked and integrated in the column direction of the pressure chambers, and each of the pair of electrodes The piezoelectric sheets are oriented in a direction perpendicular to the surface of the pressure chamber, and the piezoelectric active portion is polarized in a direction opposite to the pair of electrodes and in a direction parallel to the surface of the pressure chamber, By applying a voltage between the electrodes, the displacement of the piezoelectric active portion in a direction perpendicular to the polarization direction is applied to the liquid in the pressure chamber, so that the displacement of the piezoelectric active portion can be increased. It is possible to strike by applying a voltage during ejection. In addition, when the discharge pressure is applied to the liquid in the pressure chamber, a voltage may be applied between the pair of electrodes, and the cost of the power supply system can be reduced compared to a method in which a voltage is constantly applied and the voltage is cut off during ejection. . Further, since the plurality of piezoelectric sheets are extended over the plurality of rows of the pressure chambers and the plurality of piezoelectric sheets are stacked in the column direction of the pressure chambers, the plurality of piezoelectric active portions are arranged in the plurality of rows of the pressure chambers. As a result, a large number of nozzles and pressure chambers can be arranged with high density.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, an ink jet head which is an example of a droplet discharge device will be described.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an ink jet head which is an example of a liquid ejection apparatus according to the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the inkjet head 1 includes a cavity unit 4 having a plurality of rows of pressure chambers 3 corresponding to a row of a plurality of nozzles 2 that eject ink (droplets), and each pressure chamber 3. And a piezoelectric actuator 7 having a piezoelectric active portion S1 positioned opposite to one surface of the electrode and sandwiched between a pair of electrodes 5 and 6. Connected to the pair of electrodes 5 and 6 is a connection terminal portion 8a of a wiring board 8 provided with a wiring (signal line) for inputting a drive signal.

  The cavity unit 4 includes a stacked body 11 formed by stacking a plurality of plates (plate materials), and a diaphragm 12 is provided on the upper side of the stacked body 11. A piezoelectric actuator 7 is provided on the upper side of the diaphragm 12. That is, the diaphragm 12 is provided between the cavity unit 4 and the piezoelectric actuator 7. The diaphragm 12 is liquid-impermeable and flexible so that ink in the pressure chamber 3 does not penetrate into the piezoelectric actuator 7.

  In this laminated body 11, a cavity plate 21, a base plate 22, aperture plates 23A and 23B, two manifold plates 24A and 24B, a damper plate 25, a spacer plate 14, and a nozzle plate 13 are stacked in order from the upper side, and an adhesive Alternatively, they are integrated by metal diffusion bonding. The plates 14 and 21 to 25 excluding the nozzle plate 13 are rectangular metal plates, and an ink flow path is formed by a combination of through holes formed through these plates.

  The nozzle plate 13 is a polymer synthetic resin plate (for example, polyimide) in which one nozzle 2 is provided for each pressure chamber 3 of the cavity plate 21 described later. The nozzle 2 is formed by subjecting a polymer synthetic resin plate to excimer laser processing. A plurality of nozzles 2 are arranged in rows in a direction perpendicular to the paper surface of FIG. 1 (direction along the paper surface of FIG. 2: arrow L direction), and the rows are arranged in the direction along the paper surface of FIG. A plurality of rows are arranged in the (N direction).

  In the cavity plate 21, a plurality of through-hole portions serving as the pressure chambers 3 are formed in a plurality of rows in an array state corresponding to the nozzles 2. The diaphragm 12 is laminated on the upper surface of the cavity plate 21 so as to block the plurality of pressure chambers 3 (cavities). The cavity plate 21 has partition walls 3a between the plurality of pressure chambers 3 (see FIG. 2).

  The manifold plates 24A and 24B are formed with through holes to be the manifolds 24Aa and 24Ba. The manifolds 24 </ b> Aa and 24 </ b> Ba extend long along each row of the pressure chambers 3 (that is, in the direction L perpendicular to the paper surface of FIG. 1). The base plate 22 and the aperture plates 23A and 23B are formed with a communication hole 22a, a long and narrow communication hole 23Aa, and a communication hole 23Ba that serve as a communication path that connects one end in the longitudinal direction of each pressure chamber 3 and the manifolds 24Aa and 24Ba. ing. The manifolds 24Aa and 24Ba are connected at their ends to an ink supply source (not shown), and the ink supplied from the ink supply source is supplied to the plurality of manifolds 24Ba, 23Aa and 22a via the communication hole portions 23Ba, 23Aa and 22a. The pressure chamber 3 is distributed and supplied.

  The damper plate 25 is provided with a damper chamber 25a formed as a recess on the lower surface, leaving a thin damper wall at a position corresponding to the manifolds 24a and 24b.

  The other end in the longitudinal direction of each pressure chamber 3 and each nozzle 2 are connected to the base plate 22, the aperture plates 23A and 23B, the manifold plates 24A and 24B, and the communicating holes 22b, 23Ab, 23Bb, 24Ab, and 24Bb formed in the damper plate 25. , 25b. The ink in each pressure chamber 3 is ejected from the corresponding nozzle 2 to the outside by the ejection pressure received from the piezoelectric actuator.

  The piezoelectric actuator 7 has a structure in which each of the plurality of piezoelectric sheets 7A and 7B extends over a plurality of rows of the pressure chambers 3 and the plurality of piezoelectric sheets 7A and 7B are stacked and integrated in the column direction of the pressure chambers 3. It is. That is, each of the piezoelectric sheets 7A and 7B is flat in a direction orthogonal to the plane formed by the plurality of pressure chambers 3, and has a wide flat surface (a surface parallel to the paper surface of FIG. 1) facing each other. A plurality of the pressure chambers 3 are stacked in the row direction (L direction). And each of a pair of electrodes 5 and 6 is orientated in the direction orthogonal to the surface of the pressure chamber 3 between the plurality of piezoelectric sheets 7A and 7B, and the pair of electrodes 5 and 6 are arranged between the piezoelectric sheets 7A and 7B. They are arranged alternately in the stacking direction (L direction).

  As shown in FIG. 4, one of the pair of electrodes 5 and 6 (hereinafter referred to as individual electrode) 5 is positioned corresponding to each pressure chamber 3 individually, and the length direction of the pressure chamber 3 (N direction). ) Has approximately the same length as the pressure chamber 3. The pressure chambers 3 are located on an extension line of the partition walls 3a between the pressure chambers 3 in adjacent rows in a plan view, that is, the pressure chambers 3 in adjacent rows form a staggered arrangement. For this reason, the individual electrodes 5 also have a corresponding staggered arrangement. The other electrode (hereinafter referred to as a common electrode) 6 extends over a position corresponding to each pressure chamber 3 in the adjacent row. More specifically, the thickness of two piezoelectric sheets 7A and 7B after sintering the piezoelectric actuator 7 described later is substantially the width in the column direction L of each of the pressure chambers 3 and the partition walls 3a. The individual electrode 5 is located at the center of the pressure chamber 3, and the common electrode 6 is located along both sides of the pressure chamber 3 in the width direction. As shown in FIG. 3, the width of the pressure chamber 3 is slightly larger than the thickness of the two piezoelectric sheets 7A and 7B.

  The regions of the piezoelectric sheets 7A and 7B sandwiched between the pair of electrodes 5 and 6 are polarized in the facing direction of both electrodes (in the direction of arrow D in FIG. 3) by a known polarization process, and this region is used as the piezoelectric active portion S1. . This polarization direction is also a direction parallel to the upper surface of the pressure chamber 3. The region of the piezoelectric sheets 7A and 7B corresponding to the upper side of the partition wall 3a, that is, the region sandwiched only by the common electrode 6 is an inactive portion S2 that is not polarized. Accordingly, the piezoelectric actuator 7 includes the piezoelectric active portions S1 and the inactive portions S2 alternately in the stacking direction (L direction) of the piezoelectric sheets 7A and 7B and the direction perpendicular to the piezoelectric sheet 7A and 7B (N direction).

  Then, the piezoelectric active part S1 of the piezoelectric actuator 7 is opposed to the pressure chamber 3, the inactive part S2 is opposed to the partition wall 3a, and the piezoelectric actuator 7 and the cavity unit 4 are joined via the diaphragm 12 and an adhesive. ing. That is, the inactive part S2 is fixed to the partition wall 3a.

  Each individual electrode 5 has its upper end exposed at the upper surface of the piezoelectric actuator 7 (surface opposite to the pressure chamber 3), and the exposed end of each of the flexible wiring boards 8 disposed on the upper surface of the piezoelectric actuator 7. It is electrically connected to the connection terminal portion 8a. The wiring board 8 has a wiring (signal line) for inputting a driving signal from a driving signal source (not shown), and selectively supplies a driving signal to each individual electrode 5. Each common electrode 6 has a lower end exposed at the lower surface (surface on the pressure chamber 3 side) of the piezoelectric actuator 7, and the exposed end is electrically connected to the diaphragm 12. The diaphragm 12 is made of a conductive material, and is preferably connected to one wiring of the wiring board 8. The diaphragm 12 may be connected to wiring that connects the cavity unit 4 to the ground. Further, the common electrode 6 can be exposed to the upper surface of the piezoelectric actuator 7 and connected to one wiring of the wiring board 8 without being connected to the diaphragm 12. In this case, the diaphragm 12 can be formed of an electrically insulating plate.

  When a positive voltage of the drive signal is applied to the individual electrode 5 through the wiring substrate 8 and the common electrode 6 is connected to the ground potential, that is, when a voltage is applied between the individual electrode 5 and the common electrode 6, the piezoelectric active part S1 An electric field is generated in the same direction as the polarization direction D, and the piezoelectric active portion S1 is contracted and displaced in a direction orthogonal to the polarization direction D as indicated by a chain line in FIG. The diaphragm 12 bonded thereto is also displaced integrally to enlarge the pressure chamber 3 and cause pressure fluctuation in the ink in the pressure chamber 3. At the timing when the pressure fluctuation changes from negative to positive, the voltage supply to the individual electrode 5 is stopped, and the contracted piezoelectric active portion S1 returns to apply positive pressure to the ink in the pressure chamber 3. The applied pressure and the positive pressure fluctuation are superimposed, and the ink in the pressure chamber is ejected from the nozzle 2 with a strong pressure.

  At this time, no electric field is generated in the inactive portions S2 on both sides of the piezoelectric active portion, and the inactive portion S2 is not displaced and remains fixed on the partition wall 3a.

  As shown in FIG. 5, the piezoelectric actuator 7 is formed by stacking and integrating piezoelectric sheets 7A and 7B formed larger than the piezoelectric actuator 7 assembled in one ink jet head, and firing. It is manufactured by cutting to the size.

  That is, in the piezoelectric sheet 7A, two rectangular individual electrodes 5 (one electrode 5 only at a position along the edge of the sheet) are arranged in a row at intervals in the N direction on the sheet surface. A plurality of columns are arranged in a direction orthogonal to the columns. Furthermore, another piezoelectric sheet 7A provided with the individual electrodes 5 having a staggered arrangement in plan view with respect to the individual electrodes is prepared. On the other hand, in the piezoelectric sheet 7B, on the sheet surface, a plurality of strip-shaped common electrodes 6 having a height of two are arranged in parallel in a direction perpendicular to the column direction. A positional relationship in which the line X1 between the individual electrodes 5 and 5 substantially coincides with the center line Y1 of the common electrode 6 and the line X2 between the common electrodes 6 and 6 substantially coincides with the center line Y2 of the individual electrode 5 Thus, both piezoelectric sheets 7A and 7B are laminated. In this case, two types of piezoelectric sheets 7A are alternately sandwiched between the plurality of piezoelectric sheets 7B, and a number of piezoelectric sheets corresponding to the length of the piezoelectric actuator 7 in the L direction are stacked.

  Then, after being integrated and sintered, the height H of one piezoelectric actuator 7 is formed by cutting along the lines X1-Y1 and X2-Y2, and in the column direction of the individual electrodes. A plurality of piezoelectric actuators are formed by cutting the length of one piezoelectric actuator 7 for each length in the N direction. As a result, the electrode 5 is exposed on one cut surface and the electrode 6 is exposed on the other cut surface. In FIG. 5, the exposed electrodes are alternately reversed in the vertical direction, but the surface where the electrodes 5 are exposed is used.

  Here, the piezoelectric sheets 7A and 7B are made of lead zirconate titanate, and the pair of electrodes are screen-printed with a silver-palladium-based conductive paste.

  In the embodiment, in the case where the pressure chambers 3 are in a plurality of rows, the piezoelectric actuator 7 is configured by laminating the piezoelectric sheets 7A and 7B having a length extending over the rows in the row direction. The piezoelectric active portions S1 sandwiched between the six can be arranged with high density. As a result, the pressure chambers 3 and the nozzles 2 can be arranged with high density. Moreover, since the pressure chamber 3 has a width in the column direction L that is shorter than a length in the direction N orthogonal thereto, piezoelectric sheets 7A and 7B that are long in the length direction are stacked in the width direction of the pressure chamber 3. Thus, the electrodes 5, 6 can be arranged in the length direction of the pressure chamber 3, and the piezoelectric active portion corresponding to the pressure chamber 3 can be constituted by a small number of piezoelectric sheets 7A, 7B. This also makes it possible to arrange the pressure chambers 3 and the nozzles 2 with higher density.

  In each piezoelectric sheet, since the length in the opposing length direction of the electrode orthogonal to the thickness in the direction in which the electrodes 5 and 6 are opposed can be sufficiently large, the displacement is longer than the displacement of the piezoelectric longitudinal effect in the thickness direction. The displacement in the direction (height H in FIG. 1) can be increased. Furthermore, the displacement can realize so-called striking that expands the volume of the pressure chamber by applying a voltage and reduces the volume by stopping the application of voltage.

  Further, even when the number of electrodes is high and the density is high, the end of the piezoelectric actuator 7 is exposed on the upper surface, so that the connection with the drive signal source can be easily performed. Further, as shown in FIG. 5, a piezoelectric actuator can be easily obtained by integrally manufacturing a plurality of laminated bodies of piezoelectric actuators and cutting them.

  In the embodiment, the diaphragm 12 is provided between the cavity unit and the piezoelectric actuator. However, depending on the type of liquid used in the pressure chamber 3, such a plate may be omitted. You can also. Further, in the above-described embodiment, the width of the pressure chamber is approximately the size of two piezoelectric sheets. However, the pressure chamber can be made to correspond to a larger number of sheets or within the width of the pressure chamber. It can also comprise so that the group with the electrode 6 may be arrange | positioned more.

  In the above embodiment, the case where the droplet discharge device is an ink jet printer has been described. However, the present invention is not limited to this, and a colored liquid is applied as fine droplets or a conductive liquid is discharged. The present invention can also be applied to other droplet discharge devices that form a wiring pattern.

1 is a cross-sectional view illustrating a schematic configuration of an inkjet head which is an example of a liquid ejection apparatus according to the present invention. It is sectional drawing in the II-II line of FIG. It is explanatory drawing of ink discharge. It is a top view which shows the state which removed the flexible flat cable. It is explanatory drawing of the manufacturing method of the said inkjet head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Nozzle 3 Pressure chamber 3a Partition 4 Cavity unit 5 One electrode 6 The other electrode 7 Piezoelectric actuator 7A, 7B Piezoelectric sheet S1 Piezoelectric active part S2 Inactive part

Claims (10)

A cavity unit having a plurality of rows of pressure chambers corresponding to a plurality of rows of nozzles for discharging droplets;
A piezoelectric actuator having a piezoelectric active portion located opposite to one surface of each pressure chamber and sandwiched between a pair of electrodes;
The piezoelectric actuator has a structure in which each of a plurality of piezoelectric sheets extends over a plurality of rows of the pressure chambers, and the plurality of piezoelectric sheets are stacked and integrated in a row direction of the pressure chambers, Each of the electrodes is oriented in a direction perpendicular to the surface of the pressure chamber between the plurality of piezoelectric sheets, and the piezoelectric active portion is opposed to the pair of electrodes and in a direction parallel to the surface of the pressure chamber Is polarized,
A droplet discharge device that applies discharge pressure to ink in the pressure chamber by displacement of the piezoelectric active portion in a direction orthogonal to the polarization direction by applying a voltage between the pair of electrodes. The cavity unit has a partition wall between the plurality of pressure chambers,
The piezoelectric actuator is formed by laminating the plurality of piezoelectric sheets by alternately forming the piezoelectric active portions and the non-displaceable inactive portions in a direction in which the piezoelectric sheets are laminated and a direction orthogonal thereto.
The droplet discharge device according to claim 1, wherein the piezoelectric actuator and the cavity unit are joined with the inactive portion facing the partition. In the cavity unit, the pressure chambers in adjacent rows form a staggered arrangement,
3. The droplet discharge device according to claim 2, wherein the piezoelectric actuator has the piezoelectric active portion in one row and the inactive portion in a row adjacent to the piezoelectric active portion in a direction orthogonal to the row direction. .   The piezoelectric actuator includes a piezoelectric sheet in which one electrode of the pair of electrodes is formed on a surface and a piezoelectric sheet in which the other electrode of the pair of electrodes is formed on a surface are alternately stacked in the column direction. The droplet discharge device according to claim 1, wherein the droplet discharge device is integrated.   The one electrode is positioned corresponding to each of the pressure chambers, and the other electrode extends across positions corresponding to both pressure chambers of the adjacent row. 4. The droplet discharge device according to 4.   One of the pair of electrodes is independent for each of the pressure chambers, and one end of the electrode is exposed on a surface of the piezoelectric actuator opposite to the cavity unit. 6. The droplet discharge device according to any one of 5 above.   The droplet discharge device according to claim 6, wherein the other electrode of the pair of electrodes extends over a plurality of rows of the pressure chambers.   A flexible conductive plate is provided between the cavity unit and the piezoelectric actuator, and the other electrode of the pair of electrodes is connected to the conductive plate. The droplet discharge device according to claim 6 or 7.   9. The plate according to claim 1, wherein a plate is provided between the cavity unit and the piezoelectric actuator so as to be flexible and impermeable to liquid in the pressure chamber. Droplet discharge device. The piezoelectric sheet is made of lead zirconate titanate,
The droplet discharge device according to claim 1, wherein the pair of electrodes is a screen-printed silver-palladium conductive paste.

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