JP2005059551A - Ink jet printer head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet printer head in which print performance is enhanced while lowering the driving voltage. <P>SOLUTION: The ink jet printer head is arranged such that a piezoelectric sheet between a discrete electrode 36 and a common electrode 37 facing the laying direction thereof becomes an active part corresponding to each pressure chamber 23 when a piezoelectric sheet 33 provided with the discrete electrode 36 of a piezoelecric actuator being bonded to a cavity unit and a piezoelectric sheet 34 provided with the common electrode 37 are laid in layers alternately. The common electrode 37 is patterned to include a first electrically conductive part 37a elongated in the longitudinal direction of each pressure chamber 23 while overlapping the arranging position thereof in the plan view, and a second electrically conductive part 37b for coupling the opposite ends of the first electrically conductive part 37a along the X-axis direction in correspondence with the opposite ends of each pressure chamber 23 in the longitudinal direction. Consequently, a voltage is applied substantially uniformly on the first electrically conductive part 37a, and the quantity of conductive paste used and the capacitance are reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inkjet printer head, and more particularly to a configuration of an inkjet printer head that selectively ejects ink from a plurality of nozzles by driving a piezoelectric actuator.

  In the on-demand type ink jet printer head of the prior art, as disclosed in Patent Document 1 and Patent Document 2, etc., a plurality of plates are stacked to form a cavity unit having an ink flow path. The plate is a manifold as a nozzle plate having a plurality of nozzles, a base plate having a pressure chamber for each nozzle, and a common ink chamber connected to the ink supply source and connected to each pressure chamber. It is comprised from the manifold plate etc. which have a chamber. The piezoelectric actuator is configured by alternately laminating common electrodes and individual electrodes with a piezoelectric ceramic plate (piezoelectric sheet) interposed therebetween, and is a portion of the piezoelectric sheet between the individual electrodes and the common electrode facing each other in the laminating direction. The piezoelectric actuator and the cavity unit are joined so that the active portion overlaps the pressure chamber in plan view.

  Then, in order to apply a voltage to each active part of the piezoelectric actuator, the joining terminal part in the cable member such as a flat cable for transmitting a control signal from the outside is joined to the surface electrode of the uppermost sheet of the piezoelectric actuator. The surface electrode and the individual electrode or the common electrode are connected by a conduction portion extending in the stacking direction of the piezoelectric actuator.

  In addition, as shown in Patent Document 2 and the like, a dummy individual electrode corresponding to the extended end portion of each individual electrode in the other piezoelectric sheet adjacent in the stacking direction is formed on one piezoelectric sheet on which the common electrode is formed. The other piezoelectric sheet is formed with a dummy common electrode corresponding to an extended end portion (leading portion) of the common electrode in the one piezoelectric sheet, and each piezoelectric sheet has a through hole penetrating in the thickness direction thereof. It is disclosed that a common electrode and a dummy common electrode are connected by an internal conductive electrode filled therein, and each individual electrode and a dummy individual electrode are connected.

And in the said patent document 2, the pattern shape in planar view of a dummy individual electrode is the same rectangular shape as the shape of the extended end part of the individual electrode in an adjacent piezoelectric sheet, Comprising: The direction orthogonal to the long side of a piezoelectric sheet The through-hole is formed in the middle of the dummy individual electrode in a plan view pattern so as to reach the side edge of the long side.
JP 2002-36544 A Japanese Patent Laid-Open No. 2002-19102

  By the way, in the plan view of the piezoelectric sheet, the shape of the common electrode necessary as the active portion only needs to be substantially equal to the shape of the individual electrode, and all these common electrodes need only be connected to the lead portion. In Patent Documents 1 and 2, in the plan view of the piezoelectric actuator, the shape of the common electrode is substantially the center of the flat plate surface of the piezoelectric sheet, except for the location of the island-like individual dummy electrode to the individual electrode. The lead-out portion is formed near the side edge of the piezoelectric sheet so as to be connected to the common electrode.

  Therefore, the amount of silver-palladium-based conductive material (conductive paste) used for forming the common electrode increases, and the manufacturing cost increases.

  Further, in order to make the active part act, a driving voltage is applied between the individual electrode and the common electrode. However, if the formation area of the common electrode is large, the capacitance of the entire piezoelectric actuator increases, There is a problem in that a predetermined piezoelectric strain cannot be applied to each active portion unless the voltage to be applied is increased.

  Further, in Patent Documents 1 and 2, two rows of active portions are formed in one piezoelectric actuator. However, when the number of rows of the active portions increases, the influence of the above problem increases.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an ink jet printer head capable of reducing the driving voltage and reducing the manufacturing cost.

  In order to achieve the above object, according to the first aspect of the present invention, a plurality of nozzle rows arranged in a row along the first direction and a row of pressure chambers corresponding to each nozzle are formed. In the ink jet printer head formed by bonding a stacked piezoelectric actuator for ejecting ink having an active portion that can be selectively driven for each pressure chamber to the cavity unit, each of the pressure chambers includes: In plan view, it is formed long in a direction intersecting the first direction, and the piezoelectric actuator is formed by laminating a plurality of sheets including a piezoelectric sheet and sandwiching the piezoelectric sheets in the laminating direction. The piezoelectric sheet between the electrodes facing each other in the stacking direction of the individual electrode and the common electrode is configured to be the active portion corresponding to each pressure chamber, while the common electrode The pattern overlaps with the arrangement position of each pressure chamber in plan view, and corresponds to the first electrically conductive portion that is long along the longitudinal direction of each pressure chamber, and both ends in the longitudinal direction of each pressure chamber. The first electrical conducting portion is formed to include a second electrical conducting portion that connects both ends of the first electrical conducting portion along the first direction.

  According to a second aspect of the present invention, in the ink jet printer head according to the first aspect of the present invention, the individual flat electrodes and the piezoelectric elements on the sheet adjacent in the stacking direction are formed on the same flat surface on which the common electrode pattern is formed. A first island-like individual conducting portion for electrical conduction through an internal conducting electrode penetrating in the sheet thickness direction of the sheet is constant from an edge extending along the first direction in the common electrode pattern. They are separated by a distance.

  According to a third aspect of the present invention, in the inkjet printer head according to the second aspect of the present invention, a pattern of the common electrode is formed on one flat plate surface of the sheet laminated above the piezoelectric sheet constituting the active portion. Forming a common conduction part electrically connected to the part and electrically conducting via each first island-like individual conduction part and an internal conduction electrode penetrating in the plate thickness direction of the sheet The second island-shaped individual conductive portion is formed at a predetermined distance from an edge extending along the first direction in the pattern of the common conductive portion.

According to a fourth aspect of the present invention, in the ink jet printer head according to the third aspect, the nozzle row and the corresponding pressure chamber row are appropriately spaced in a second direction intersecting the first direction. Arranged in multiple rows,
On the flat plate surface of the piezoelectric sheet, edges extending along the first direction in the pattern of the common electrode are formed at appropriate intervals in the second direction, and the first island-shaped individual conducting portion is formed. And the 2nd island-like individual conduction | electrical_connection part is formed in the area | region between the said both edges.

  According to a fifth aspect of the present invention, in the ink jet printer head according to any one of the first to fourth aspects, the plurality of nozzles are arranged in four rows, and the piezoelectric elements are arranged corresponding to the rows of the nozzles. The actuator is formed with four rows of active portions so as to correspond to the nozzle rows.

  According to the first aspect of the present invention, the piezoelectric sheet between the electrodes facing each other in the stacking direction of the individual electrode and the common electrode formed by sandwiching the piezoelectric sheet in the stacking direction corresponds to each pressure chamber. When forming the active portion, the pattern of the common electrode overlaps the arrangement position of each pressure chamber in plan view, and is long along the longitudinal direction of each pressure chamber, and The piezoelectric sheet is formed so as to correspond to both ends in the longitudinal direction of each pressure chamber, and to include both ends of the first electrically conductive portion connected along the first direction. Compared with the case where the pattern of the common electrode is formed on almost the entire flat plate surface, the amount of conductive paste used for pattern formation is reduced, and the manufacturing cost can be reduced. In addition, since the capacitance of the piezoelectric actuator is small by the area of the conductive portion of the common electrode, the required applied voltage (driving voltage) for discharging ink to the piezoelectric actuator can be reduced. As a result, the driving voltage circuit board However, the manufacturing cost can be reduced by using a low voltage. Furthermore, since the both ends of the 1st electrical conduction part long in the longitudinal direction of a pressure chamber are each connected to the 2nd electrical conduction part, the longitudinal direction of each 1st electrical conduction part and arrangement | sequence of several 1st electrical conduction parts There is little voltage drop in the direction, and there is an effect that each active part can be operated almost uniformly.

  According to invention of Claim 2 and 3, the outline of a pattern bleeds at the time of printing formation of each pattern of a common electrode, an individual electrode, the 1st and 2nd island-like individual conduction part, and a common conduction part. Even if there is a slight error in the pattern area (area), the distance between the electrodes formed on the same plane of the piezoelectric sheet can be maintained at a predetermined distance. The current does not leak between the electrodes, and only the active part corresponding to the predetermined pressure chamber can be operated reliably, and the print quality can be satisfactorily maintained while being compact.

  According to the fourth aspect of the present invention, when a plurality of rows of nozzles (pressure chamber rows) are formed on the plane portion of one piezoelectric actuator, the electrodes are electrically connected to the individual electrodes in the stacking direction. Since the pattern of the common conduction part that is also electrically connected to the common electrode in the stacking direction is formed so as to surround the first and second island-like individual conduction parts, an external drive signal is transmitted. As a result, the bonding electrode portion with the flat cable can be formed on the flat plate portion of the sheet on the piezoelectric sheet. As a result, the size of the piezoelectric actuator in the second direction (short side direction) can be shortened.

  According to a fifth aspect of the present invention, in the ink jet printer head according to any one of the first to fourth aspects, the plurality of nozzles are arranged in four rows, and the piezoelectric elements are arranged corresponding to the rows of the nozzles. Since the actuator is formed with four rows of active portions corresponding to the rows of the nozzles, in addition to the effect of the invention according to any one of claims 1 to 4, for the color, etc. The multi-nozzle inkjet printer can be manufactured in a compact manner.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a cavity unit 11 and a piezoelectric actuator 12 in a piezoelectric inkjet printer head 10 according to an embodiment of the present invention. FIG. 2 is a third spacer plate 21 adjacent to the cavity plate and its lower surface side. FIG. 3 is an enlarged sectional view taken along the line III-III in FIG. 1, FIG. 4A is an enlarged sectional view taken along the line IV-IV in FIG. 12 is a diagram showing electrode patterns of each layer in the piezoelectric actuator 12, FIGS. 13 to 16 are plan views showing the overlapping state of the electrode patterns, and FIG. 19 is a diagram showing the form of the ink flow path from one end of the pressure chamber to the nozzles. FIG.

  In FIG. 1, the plate laminated piezoelectric actuator 12 joined to the upper surface of the cavity unit 11 made of a metal plate has flexibility as an example of a cable member for connection to an external device. The flat cable 13 (individually indicated by reference numerals 13a and 13b, see FIGS. 1, 3 and 4A) is lap-joined.

  The cavity unit 11 is configured as shown in FIGS. That is, a total of 9 base plates 22 in which the nozzle plate 14, the cover plate 15, the damper plate 16, the two manifold plates 17, 18, the three spacer plates 19, 20, 21 and the pressure chamber 23 are formed in order from the lower layer. In this embodiment, each of the plates 15 to 22 is made of 42% nickel alloy steel plate and has a thickness of 50 μm, except for the nozzle plate 14 made of synthetic resin. It has a thickness of about ~ 150 μm.

  The nozzle plate 14 has a large number of nozzles 24 for ejecting ink having a small diameter (in the embodiment, about 25 μm) in the first direction (the long side direction of the cavity unit 11) in FIG. In FIG. 3, four rows formed along the X-axis direction) are provided in a four-row staggered arrangement.

  That is, the cavity unit 11 is cut along the Y-axis direction (short side direction) in FIG. 1, and only the right side of the center line C of the short side is shown in FIG. 24-1 and the second row of nozzles 24-2 closer to the center line C are connected to two parallel adjacent reference lines (not shown) of the nozzle plate 14 extending in the first direction. A large number of holes are formed in a staggered arrangement at intervals of a minute pitch P along the same line. Similarly, on the left side of the center line C, the third row of nozzles 24-3 and the fourth row of nozzles 24- 4 (not shown in FIG. 3 and FIG. 4A) is a minute pitch along two parallel adjacent reference lines extending in the first direction (X-axis direction). A large number of holes are formed in a staggered arrangement at intervals of P. Further, the set of the first row nozzle 24-1 and the second row nozzle 24-2 and the set of the third row nozzle 24-3 and the fourth row nozzle 24-4 are the same as those of the cavity unit 11. They are arranged in parallel in the short-side direction (second direction, Y-axis direction in FIG. 1) at intervals. In the embodiment, the length of each nozzle row of the first row to the fourth row is 2 inches, and the number of each nozzle 24 is 150, that is, the arrangement density is 75 (dpi [dot per inch]). is there.

  In the base plate 22 which is the uppermost layer of the cavity unit 11 shown in FIG. 2, pressure chambers 23 are provided so as to penetrate the plate thickness direction with the same pitch P corresponding to the nozzles 24. The pressure chambers 23 are arranged in a row in the long side direction (X-axis direction) of the cavity unit 11. Therefore, the adjacent pressure chambers 23 are isolated by the elongated partition wall 70 that is substantially parallel to the short side of the cavity unit 11 (see FIGS. 2, 3, and 13). The width dimension W2 of each partition wall 70 is set slightly smaller than the width dimension W1 of the pressure chamber 23 (see FIGS. 2 and 13).

  The first row of pressure chambers 23-1 corresponds to the first row of nozzles 24-1. Similarly, the second row of pressure chambers 23-2 is the second row of nozzles 24-2, and the third row of pressure chambers 23-3 is the third row of nozzles 24-3, and the fourth row of pressure chambers. 23-4 has a corresponding relationship with the nozzle 24-4 in the fourth row.

  Next, two piezoelectric elements are arranged such that the arrangement relationship of the pressure chambers 23 in the base plate 22 which is the uppermost layer of the cavity unit 11 is arranged in the column direction (first direction, X-axis direction) of the nozzles 24 thereon. This will be described from the relationship with the arrangement of the active portion in the actuator 12 (indicated by reference numerals 12a and 12b individually).

  One piezoelectric actuator 12a (or 12b) has 75 active portions so as to actuate half (75 per row) of pressure chambers 23 in the row direction out of the number of nozzles 24 in the four rows. Arranged. Accordingly, as shown in FIGS. 1 and 3, one piezoelectric actuator 12a is disposed in the front half of the upper surface of the cavity unit 11 in the longitudinal direction (the X-axis direction), and the other piezoelectric actuator 12b is disposed in the rear half. Is done.

  Each piezoelectric actuator 12a (or 12b) is arranged corresponding to each position of the common electrode 37 and each pressure chamber 23, as will be described in detail later with reference to FIGS. When the individual electrodes 36 formed are alternately stacked with the piezoelectric sheets sandwiched therebetween, the individual electrodes 36 formed with the piezoelectric sheets sandwiched in the stacking direction and the common electrode 37 between the electrodes facing each other in the stacking direction. The piezoelectric sheet becomes an active part corresponding to each pressure chamber 23. When a voltage is applied between any individual electrode 36 and the common electrode 37, distortion due to the piezoelectric longitudinal effect is generated in the active direction of the piezoelectric sheet corresponding to the applied individual electrode 36 in the stacking direction. To do. The active portions are formed in the same number in the same row with the same number as the number of pressure chambers 23.

  In other words, the active portions are arranged along the row direction (X-axis direction) of the nozzles 24 (pressure chambers 23), and are arranged in the second direction by the same number as the number of the nozzle rows (four). It has been. Each active part is formed long in the longitudinal direction of the pressure chamber 23 in the second direction (the width direction of the cavity unit 11, the Y-axis direction), and the arrangement interval (pitch P) between adjacent active parts is also described later. The pressure chambers 23 are arranged in a staggered manner (see FIG. 3).

  The pressure chambers 23 are arranged in two groups in the longitudinal direction (X-axis direction) of the base plate 22 corresponding to the two piezoelectric actuators 12a and 12b. In other words, the pressure chambers 23 of the group corresponding to one actuator 12a correspond to those in the first half of the row direction (first direction, X-axis direction) of the nozzles 24, and the pressure of the group corresponding to the other actuator 12b. The chambers 23 correspond to the latter half of the nozzles 24 in the row direction (first direction, X-axis direction), and have the same interval as the arrangement interval (pitch P) of the nozzles 24 and two rows of staggered shapes. Two sets of arrays are arranged in a total of four rows (see FIG. 1).

  Each of the pressure chambers 23 is long in the width direction (second direction, Y-axis direction) of the base plate 22 and is formed so as to penetrate the base plate 22 in the thickness direction. An inlet end 23b of each pressure chamber 23 communicates with a manifold chamber 26 described later via a second ink passage 30, a throttle portion 28, and a first ink passage 29 formed in the spacer plates 19, 20, and 21 (FIG. 2 and FIG. 4 (a)).

  In addition, the outflow end 23 a of each pressure chamber 23 is ink formed on the spacer plates 19, 20, 21, the manifold plates 17, 18, the damper plate 16, and the intermediate plate 15 positioned between the base plate 22 and the nozzle plate 14. Each of the communication passages 25 is communicated with each nozzle 24 via each communication passage 25 as a flow passage. A part of this communication passage 25 is at least one of the plates 15 to 21 stacked between the base plate 22 and the nozzle plate 14. The (one layer) plate is provided with a concave groove-like flow passage 50 substantially parallel to the flat plate surface (front surface or back surface), so that the position of the nozzle 24 corresponding to each pressure chamber 23 can be determined. A straight line (perpendicular line) perpendicular to the surface of the base plate 24 extends from the outflow end 23a (ink outflow portion) of the nozzle plate 14 to the nozzle plate 14. , In which can be set in the lateral direction (direction along the first direction of the plate, X-axis direction) to the distance L3 shifted position (see FIGS. 2 and 3).

  That is, as shown in FIGS. 1, 3, and 19, the space between the two pressure chambers 23 of the piezoelectric actuators 12 a and 12 b is wider than the arrangement interval (pitch P) of the pressure chambers 23 in the longitudinal direction of the base plate 22. The interval L2 is set. This is because, in manufacturing each piezoelectric actuator 12a, 12b, the distance L1 between the individual electrodes 36, 36 at the end of the row and the one end 44 (one end 45 of the other piezoelectric actuator 12b) of the piezoelectric actuator 12a adjacent to it. Since it is difficult to manufacture the individual electrodes 36 to be equal to or less than ½ of the pitch P, the distance L1 is set to a size that facilitates the manufacture of the piezoelectric actuators 12a and 12b, and a larger interval L2 is set.

  Then, one end 44 of one piezoelectric actuator 12a and one end 45 of the other piezoelectric actuator 12b adjacent to each other are opposed to each other, and the distance between the opposing ends 44, 45 is separated by a distance L4. Both piezoelectric actuators 12a and 12b are arranged in series (see FIGS. 1 and 3).

  As a result, the pitch P of the nozzles 24 is set to be constant in the row direction, but the position of the corresponding pressure chamber 23 is transverse to the line (perpendicular) perpendicular to the plate thickness (X-axis). Since at least a part of the communication passage 25 connected from the outflow end 23a of each corresponding pressure chamber 23 to the nozzle 24 is parallel to the flat plate surface of the plate as described above. By constituting the groove-shaped communication path 50, the communication paths 25 in the other plates are vertically penetrated in the plate thickness direction of each plate and communicated with one end and the other end of the groove-shaped communication path 50. It is possible to cope with the lateral displacement only by this. The groove-shaped communication path 50 extends in the extending direction of the pressure chamber 23 together with the lateral displacement and is inclined symmetrically with respect to the center of the interval L2 between the two groups of pressure chambers 23.

  In the present embodiment, the groove-shaped communication path 50 is provided in the third spacer plate 21 adjacent to the lower surface side of the base plate 22 provided with the pressure chamber 23. More specifically, as shown in FIG. 2 to FIG. 4A and FIG. 19, one end that opens to the surface (upper surface) side of the third spacer plate 21 and communicates with the outflow end 23 a of the corresponding pressure chamber 23. 50a, a concave groove-like horizontal passage portion 50b opened to the back surface (lower surface) side of the third spacer plate 21, and the other end communicating with the upper end of the vertical communication passage 25 in the lower second spacer plate 20 50c.

  In this way, a part of the communication path 25 as an ink flow path from the pressure chamber 23 to the corresponding nozzle 24 is formed in the concave groove communication path 50 extending in parallel to the plane of the plate, and the other communication paths. By adopting a shape that penetrates 25 in the direction perpendicular to the plane of the plate, even if the positions of the nozzles 24 corresponding to the pressure chambers 23 are greatly displaced in plan view, the ink flow that allows them to communicate easily The road can be designed. In addition, it is extremely easy to control so that the total length (the distance including the concave groove-like communication path 50) of the communication path 25 as the ink flow path from each pressure chamber 23 to the corresponding nozzle 24 is equal.

  A manifold chamber 26 is formed in the two manifold plates 17 and 18 so as to extend along the row of the nozzles 24. More specifically, the length of each manifold chamber 26 is a length obtained by dividing the pressure chambers 23 arranged in the direction of each nozzle row into appropriate numbers. In the embodiment, one group (one group of pressure chambers 23) is provided. The number of the pressure chambers 23 in one row is 75), and the cavity unit 11 has four rows of the pressure chambers 23, and is arranged for each row. Therefore, in the embodiment, eight manifold chambers 26 are formed. One end portion in the longitudinal direction of each manifold chamber 26 communicates with the ink supply holes 31 formed in the end portions of the spacer plates 19 to 21 and the base plate 22 stacked thereabove. A filter 32 for removing dust in ink supplied from an ink supply source such as an ink tank (not shown) is stretched on the upper surface of the ink supply hole 31 formed in the end of the uppermost base plate 22. .

  Further, the depth of each manifold chamber 26 is formed by etching or the like so as to cover the entire plate thickness of the manifold plates 17 and 18, and the first spacer plate on the upper layer of the manifold plates 17 and 18 obtained by combining these two plates. 19 and a lower damper plate 16 are stacked so as to be hermetically sealed. The damper plate 16 is formed with a damper chamber 27 having the same shape as the manifold chamber 26 in plan view and having a plate thickness reduced by etching on the lower surface side.

  Of the pressure waves acting on the pressure chamber 23 by driving the piezoelectric actuator 12, the retreat component toward the manifold chamber 26 is absorbed by the vibration of the damper plate 16 having a thin plate thickness to prevent so-called crosstalk. To do.

  The second spacer plate 20 is formed with an ink flow restricting portion 28 corresponding to each pressure chamber 23. As shown in FIG. 4B, the diaphragm portion 28 is formed so that the area of both end portions 28a and 28b in the longitudinal direction is large and the intermediate area is small. In addition, the longitudinal direction of each throttle portion 28 is formed to be parallel to the longitudinal direction of the pressure chamber 23. Then, the first spacer plate 19 is laminated on the lower surface side of the second spacer plate 20, and the third spacer plate 21 is laminated on the upper surface side, whereby the narrowed portion 28 is sealed. A first ink passage 29 formed in the first spacer plate 19 communicates the manifold chamber 26 with one end portion 28 a of the throttle portion 28. On the other hand, the second ink passage 30 formed in the third spacer plate 21 communicates the other end portion 28b of the throttle portion 28 with the inlet end 23b of the pressure chamber 23 (FIGS. 2 and 4A). reference).

  On the other hand, as shown in FIG. 5, each of the piezoelectric actuators 12 is composed of a plurality of (seven in the embodiment) piezoelectric sheets 33 and 34 made of piezoelectric ceramic plates each having a thickness of about 30 μm. In this structure, a constraining layer composed of two sheets 46 and 47 is laminated on the upper surface of the group, and a top sheet 35 is further laminated on the upper surface. The sheet and the top sheet of the constraining layer may be piezoelectric ceramic plates or other materials as long as they have electrical insulation.

  As shown in FIG. 8, on the upper surface (flat plate surface) of the even-numbered piezoelectric sheet 33 counted upward from the lowermost piezoelectric sheet 34 having the common electrode 37, each pressure chamber 23 (indicated by a dotted line) in the cavity unit 11. The pattern of the narrow individual electrodes 36 (indicated by reference numerals 36-1, 36-2, 36-3, 36-4 individually) for each location corresponding to the first direction (the piezoelectric sheet 33) 3 in the long side direction, the X-axis direction in FIG. 3, and the row direction of the nozzles 24.

  The individual electrodes 36-1 in the first row and the individual electrodes 36-4 in the fourth row are respectively arranged on the sides close to the side edges of the long sides of each pair of the piezoelectric sheets 33. Further, the individual electrode 36-2 in the second row and the individual electrode 36-3 in the third row are disposed at the central portion in the short side direction of each piezoelectric sheet 33.

  The patterns of the individual electrodes 36-1, 36-2, 36-3, and 36-4 are formed on the short sides of the piezoelectric sheets 33 along a second direction (Y-axis direction) orthogonal to the first direction. Extends in parallel. In that case, the straight portions 36b of the individual electrodes 36-1, 36-2, 36-3, 36-4 are respectively connected to the pressure chambers 23-1, 23-2, 23-3, 23-4 (FIG. 8). It is substantially the same length as that of the dotted line) and overlaps in a plan view, and is formed in a straight line having a slightly narrower width than each pressure chamber. The end 36a where the individual electrode 36-1 in the first row and the individual electrode 36-2 in the second row face each other, the individual electrode 36-3 in the third row, and the individual electrode 36-4 in the fourth row. The end portions 36a facing each other are bent at an angle α (an acute angle of about 60 degrees) with respect to the straight portion 36b in plan view, and extend outside the pressure chamber. The bending direction is a direction away from the opposite one end 44 (45) of the two piezoelectric actuators 12a and 12b in a plan view and extends in a direction in which both ends 36a and 36a approach each other (FIG. 8). reference).

  Further, each end 36a has a dummy individual electrode 38 as a first island-like individual conductive portion in the vertically adjacent piezoelectric sheet 34 and a first connection pattern 53 of a lower layer sheet 46 in a constraining layer described later (see FIG. 9). ) And at least a portion thereof in plan view, and are disposed at positions where they can be electrically connected to the internal conduction electrodes 42a, 42b, and 60 that penetrate the piezoelectric sheet 34 and the lower layer sheet 46, respectively (see FIG. 13).

  Further, the piezoelectric sheet 33 is a portion that partially overlaps a common electrode 37 in a piezoelectric sheet 34 to be described later in plan view, surrounds the row of the individual electrodes 36-1 and 36-2, and the individual electrode 36. A dummy common electrode 43 is formed so as to surround the columns -3 and 36-4.

  The common electrode 37 is printed on each surface of the lowermost piezoelectric sheet 34 and the odd-numbered piezoelectric sheets 34 counted upward (see FIGS. 7 and 14). The common electrode 37 is disposed at the position of the pressure chambers 23-1, 23-2, 23-3, 23-4 in each row and the individual electrodes 36-1, 36-2, 36-3, 36-4 in each row. And a long first electric conducting portion 37a that extends in the longitudinal direction (Y-axis direction) of each pressure chamber 23 (the straight portion 36b of the individual electrode 36), and the longitudinal direction of each pressure chamber 23. Corresponding to both end portions 23a and 23b of the second electrical conductive portion 37b for connecting (electrically connecting) both ends of the first electrical conductive portion 37a along the first direction (X-axis direction). It forms so that it may become. The pattern of the common electrode 37 will be described in more detail with reference to FIG. 7. For example, the common electrode 37 has a rectangular shape in plan view having a length substantially equal to the length of each pressure chamber 23 in the first row of pressure chambers 23-1. The first electrically conductive portion 37a is connected to both ends of each first electrically conductive portion 37a above the corresponding longitudinal ends 23a, 23b of each pressure chamber 23, and the row direction of the pressure chambers 23 (X-axis) A second electric conduction portion 37b extending in the direction), and is a region surrounded by the first electric conduction portion 37a and the second electric conduction portion 37b and adjacent to the pressure chambers 23-1 in the first row. A strip-shaped blank portion 72 is formed so as to correspond to the upper part of the partition wall 70 located between the two.

The ends of the first and second electrically conductive portions 37a and 37b are formed on a four-circumferential side conductive portion 37c formed so as to surround the side edge along the long side and the side edge along the short side of the piezoelectric sheet 34. Connected together.
The arrangement interval P of each first electrically conductive portion 37a is set to be equal to the arrangement interval P of each individual electrode 36-1, 36-2, 36-3, 36-4 and consequently the arrangement interval P of the pressure chamber 23 ( (See FIGS. 7 and 14).

  Piezoelectric elements corresponding to the space between the first row pressure chambers 23-1 and the second row pressure chambers 23-2 (and between the third row and fourth row pressure chambers 23-3 and 23-4). In the region of the sheet 34, in the region surrounded by the long side edge 37b 'of the two rows of the second electrically conductive portions 37b, a substantially oval dummy individual electrode 38 (individually designated by reference numeral 38-1) in plan view. , 38-2, 38-3, 38-4) are arranged at regular intervals along the column direction of the pressure chambers 23 and thus the individual electrodes 36. The dummy individual electrodes 38 are arranged and formed at regular intervals so as to overlap with at least a part of each one end portion 36a instead of the straight portion 36b of each individual electrode 36 in a plan view. Each of the oval dummy individual electrodes 38 also extends in the same direction as the direction in which the one end 36a of each individual electrode 36 extends in a plan view. In other words, each extends in an inclined manner at an angle α (an acute angle of about 60 degrees) with respect to the direction in which the straight line of the one end 44 (45) of the piezoelectric actuator 12a (12b) extends in plan view.

  Each dummy individual electrode 38 is referred to as a first island-shaped individual conduction portion. The distance between the contour edge of the pattern area of each dummy individual electrode 38 and the long edge 37b 'of the second electrically conductive portion 37b at the closest position, and the pattern area of the adjacent dummy individual electrodes 38, 38 Is set to a certain distance e2 (see the two-dot chain line in FIG. 15).

  Thus, when each dummy individual electrode 38 as the first island-shaped individual conductive portion is formed in an inclined shape, the length dimension m1 of each dummy individual electrode 38 can be formed long, but the adjacent pattern region The distance n1 between the long side edges 37b 'and 37b' of the pair of second electrically conductive portions 37b facing each other can be set short while keeping the distance between the contour edges at a constant distance e2 (see FIGS. 7 and 15). . As a result, even when there is a slight error in the pattern area (area) due to blurring of the pattern outline during printing of each pattern, the interval between adjacent patterns can be maintained at a predetermined distance e2 or more. Therefore, when a voltage is applied to each electrode, current does not leak between adjacent electrodes, and only the active part corresponding to the predetermined pressure chamber can be operated reliably, maintaining good print quality. There is an effect that can be done. As a result, the size of the short side (Y-axis direction) of each piezoelectric actuator 12a (12b) can be shortened, and the ink jet printer head can be formed compactly.

  Except for the lowermost piezoelectric sheet 34, the upper piezoelectric sheets 34 and 33 are electrically connected to a plurality of locations of the common electrode 37 such as the trunks 37a, 37b, and 37c and the dummy common electrode 43 in the vertical direction. In order to connect, at the positions of the electrodes 37 and 43, conductive members (conductive paste) filled in a plurality of through-holes drilled so as to penetrate the thickness of the piezoelectric sheets 34 and 33, respectively. The internal conduction electrode 41 is formed. Similarly, end portions 36 a of the individual electrodes 36-1, 36-2, 36-3 and 36-4 in the plurality of piezoelectric sheets 33, and the dummy individual electrodes 38-1 and 38-2 in the piezoelectric sheet 34. 38-3 and 38-4 are drilled so as to penetrate through the plate thickness of the piezoelectric sheets 33 and 34 at the positions of the end 36a and the electrode 38 in order to electrically connect each of them in the vertical direction. Internal conductive electrodes 42a and 42b are formed of conductive members (conductive paste) filled in the plurality of through holes provided. In that case, the internal conductive electrode 42a in the piezoelectric sheet 33 and the internal conductive electrode 42b in the piezoelectric sheet 34 are formed by appropriately separating the distance e1 at a position that does not overlap vertically in a plan view (see FIG. 6).

  On the upper surface of the lower sheet 46 of the two sheets 46, 47 as the constraining layer, as shown in FIG. 9, the first connection pattern 53 (individually, reference numeral 53- 1, 53-2, 53-3, and 53-4) overlap with at least a part of each of the dummy individual electrodes 38-1, 38-2, 38-3, and 38-4 in the piezoelectric sheet 34 in plan view. In such a manner, they are arranged and formed at regular intervals. Each of the first connection patterns 53 also extends in an inclined manner at an angle α (an acute angle of about 60 degrees) with respect to the direction in which the one end 44 (45) of the piezoelectric actuator 12a (12b) extends in plan view. . Further, at four corners on the upper surface of the lower layer sheet 46, contact patterns 54 as common conductive portions are formed at positions overlapping with a part of the common electrode 37 in the piezoelectric sheet 34 in plan view. Has been.

  On the other hand, as shown in FIG. 10, on the upper surface of the upper layer sheet 47, a contact pattern as a common conductive portion that overlaps with the common electrode 37 in the piezoelectric sheet 34 in the same size in plan view. 55 and at least a part of the first connection pattern 53 (individually indicated by reference numerals 53-1, 53-2, 53-3, 53-4) in the lower layer sheet 46 so as to overlap in plan view. In addition, second connection patterns 56 (individually indicated by reference numerals 56-1, 56-2, 56-3, 56-4) are arranged and formed at regular intervals.

  This second connection pattern 56 is referred to as a second island-shaped individual conduction portion. In the embodiment, the dummy individual electrode 38 which is the first island-shaped individual conductive portion is an internal conductive electrode 60 which will be described later and penetrates in the layer thickness direction of each piezoelectric sheet via the first connection pattern 53. , 62 are electrically connected.

  Each of the second connection patterns 56 also extends in an inclined manner at an angle α (an acute angle of about 60 degrees) with respect to the direction in which the one end 44 (45) of the piezoelectric actuator 12a (12b) extends in plan view. (See FIGS. 10 and 16). Further, the distance at the closest position between the contour edge of the pattern region of each second connection pattern 56 and the linear contour edge 55a of the pattern region of the connection pattern 55, and the adjacent second connection pattern The interval between the contour edges 56 and 56 is set to a constant distance e2 (see the two-dot chain line in FIG. 16).

  As described above, when each second connection pattern 56 as the second island-shaped individual conductive portion is formed in an inclined shape, the length dimension m2 of each second connection pattern 56 can be formed long, but adjacent to each other. The distance n2 between the pair of opposing contour edges 55a, 55a can be set short while keeping the distance between the contour edges of the pattern region to be maintained at a constant distance e2 (see FIGS. 10 and 16). As a result, even when there is a slight error in the pattern area (area) due to blurring of the pattern outline during printing of each pattern, the interval between adjacent patterns can be maintained at a predetermined distance e2 or more. Therefore, when a voltage is applied to each electrode, current does not leak between adjacent electrodes, and only the active part corresponding to the predetermined pressure chamber can be operated reliably, and the print quality is improved. There is an effect that it can be held.

  As a result, the size of the short side (Y-axis direction) of each piezoelectric actuator 12a (12b) can be shortened, and the ink jet printer head can be formed compactly.

  As shown in FIG. 11, a plurality of common conductive layers 57 are formed on the upper surface of the top sheet 35 so as to overlap a part of the contact pattern 55 in the upper layer sheet 47 in plan view. Further, on the top surface of the top sheet 35, the second connection patterns 56-1, 56-2, 56-3, and 56-4 in the upper layer sheet 47 are individually overlapped with each other in plan view. Conductive layers 58 (indicated individually by reference numerals 58-1, 58-2, 58-3, 58-4) are formed at regular intervals (see FIG. 17). As shown in FIG. 11, each of the individual conductive layers 58-1, 58-2, 58-3, 58-4 has a short edge (in the Y-axis direction) of the top sheet 35, and further, each individual electrode 36-1. , 36-2, 36-3, 36-4 and is formed in a straight line extending in the direction of the portion of the straight line portion 36b of each individual electrode, but shorter than the straight line portion 36b of each individual electrode. (Refer to FIG. 8 and FIG. 11 for comparison). Further, the individual conductive layers 58-1, 58-2, 58-3, 58-4 formed on the upper surface of the top sheet 235 are arranged in parallel below each other as shown in FIGS. Is positioned above the partition wall 70 between the pressure chambers 23 adjacent to each other. In FIG. 17, it is slightly shifted from the center of the partition wall 70, but it may be coincident with the center.

  Further, as shown in FIG. 12, on the top surface of the top sheet 35, as a retrofitted electrode for connecting to the connection electrode 71 of the flat cables 13a and 13b, an individual surface electrode 66 having a rectangular shape in plan view and the like is common. A front surface electrode 67 and a dummy portion 68 are formed. In that case, as shown in FIG. 18, the individual surface electrode 66 is flat on an appropriate portion in the length direction of each individual conductive layer 58-1, 58-2, 58-3, 58-4 in the top sheet 35. It is formed in an island shape so as to be partially and electrically connected partially in view, and the row direction (X-axis direction) of each individual conductive layer 58-1, 58-2, 58-3, 58-4 Are arranged in a zigzag pattern so as to be displaced in the Y-axis direction.

  In other words, in the illustrated embodiment, each individual surface electrode 66 is arranged at a position shifted by approximately half of their arrangement interval (pitch) P in plan view with respect to the corresponding pressure chamber 23 and thus the active part, And it will be arrange | positioned above the partition 70 between the adjacent pressure chambers 23 and 23 (refer FIG. 18).

  As a modification of this embodiment, the individual surface electrodes 66 arranged above the partition walls 70 between the adjacent pressure chambers 23 are arranged with respect to the corresponding pressure chambers 23 (active portions). The distance may be shifted in the X-axis direction by a distance of 1.5 times (pitch P).

  Further, as shown in FIGS. 3 and 18, the individual surface electrode 66 at a position closest to the opposing one end portions 44 and 45 of the two piezoelectric actuators 12 a and 12 b arranged in series is the one end. The distance L5 from the portions 44 and 45 is arranged so as to be biased so as to be larger than the distance L1 from the corresponding active portion and thus the one end portions 44 and 45 of the pressure chamber 23.

  The common surface electrode 67 is retrofitted in an island shape so as to overlap a part of the common conductive layer 57 formed on the upper surface of the top sheet 35 in a plan view. The dummy portion 68 is retrofitted in an island shape on the extension of the common conductive layer 57 in the X-axis direction. The electrode 67 and the dummy portion 68 are also positioned above the partition wall 70 as shown in FIG.

  Further, each dummy individual of the piezoelectric sheet 34 adjacent on the lower side is provided at each of the first connection patterns 53-1, 53-2, 53-3, 53-4 of the lower layer sheet 46. In order to electrically connect each of the electrodes 38-1, 38-2, 38-3, and 38-4 in the vertical direction, a plurality of holes formed so as to penetrate the plate thickness of the lower layer sheet 46 are provided. Internal conductive electrodes 60 are formed of conductive members (conductive paste) filled in the through holes, respectively (see FIG. 9).

  Further, in order to make an electrical connection in the vertical direction with the common electrode 37 of the piezoelectric sheet 34 adjacent on the lower side, the connection pattern 54 in the lower layer sheet 46 has a plurality of through holes similar to those described above. The internal conduction electrode 61 made of a conductive member filled in each is formed (see FIG. 9).

  Similarly, in the upper layer sheet 47, the locations of the second connection patterns 56-1, 56-2, 56-3, 56-4 and the first connection patterns 53-1, 53-2 of the lower layer sheet 46, The internal conductive electrode 62 and the through pattern 55 for electrically connecting the contact pattern 55 and the contact pattern 54 are electrically connected to the through holes in order to electrically connect the portions 53-3 and 53-4 individually. Internal conduction electrodes 63 are respectively formed in the holes (see FIG. 10).

  In the same manner as described above, the top sheet 35 is also provided with the positions of the individual conductive layers 58-1, 58-2, 58-3, 58-4 and the second connection pattern 56- in the upper layer sheet 47 adjacent to the bottom sheet 35-. An internal conduction electrode 64 is provided in the through hole in order to individually electrically connect the locations of 1, 56-2, 56-3, and 56-4. Internal conductive electrodes 65 are formed in the through holes in order to electrically connect the conductive layer 57 and the connecting pattern 55 in the upper layer sheet 47 adjacent below (see FIG. 11).

  When several sheets are stacked, the individual electrodes 36 and the dummy individual electrodes 38 corresponding to the upper and lower adjacent sheets, the first connection pattern 53, and the second connection pattern 56 are connected vertically. It is preferable to arrange the internal conduction electrodes 42a, 42b, 60, 62, 64 at positions that do not overlap each other in plan view.

  In the present invention, the internal connection electrodes for electrically connecting the individual electrodes 36 to the individual surface electrodes 66 and the common surface electrodes 67 in the piezoelectric actuators 12a and 12b are the lower layer sheet 46 and the upper layer as the constraining layers. The first connection pattern 53, the second connection pattern 56, the individual conductive layer 58 formed along each plane of the sheet 47 and the top sheet 35, and the sheets 46, 47, 35 are arranged in the vertical direction (plate thickness). The concept includes internal conduction electrodes 60, 62, and 64 penetrating in the direction.

  As an example of the manufacturing method of the piezoelectric actuator 12, the piezoelectric sheets 33 and 34, the constraining layer sheets 46 and 47, and the top sheet 35 are all made of a ceramic plate. On the surface of a large green sheet made of a ceramic plate, a piezoelectric sheet 33, for each region constituting each operation unit, so that a plurality of operation units of the piezoelectric actuator 12 are integrally formed in a matrix. In 34, the electrode patterns of the individual electrode 36, common electrode 37, dummy individual electrode 38, and dummy common electrode 43 are screen-printed with a conductive paste such as a silver-palladium paste (see FIGS. 7 and 8). On the upper and lower two constraining layer sheets 46 and 47, the first and second connection patterns 53 and 56 and the contact patterns 54 and 55 are similarly formed by screen printing using the conductive paste (FIGS. 9 and 10). reference). Then, each electrode pattern of the individual conductive layer 58 and the common conductive layer 57 is screen-printed with the conductive paste on the top sheet 35 (see FIG. 11).

  Note that the internal conductive electrodes 41, 42, 60 to 65 in the piezoelectric sheets 34 and 33, the upper and lower layer sheets 46 and 47, and the top sheet 35 excluding the lowermost piezoelectric sheet 34 are formed after the through holes in the plate thickness direction are formed. Pour the paste. Next, a plurality of material sheets are laminated in a state where the positions of the regions constituting each operation unit are aligned with each other, and then pressed in the laminating direction, integrated, and then fired.

  Next, on the upper surface of the top sheet 35, as a retrofitted electrode for connecting to the connection electrode 71 of the flat cables 13a and 13b, the individual surface electrode 66, the common surface electrode 67, and the dummy portion having a rectangular shape in plan view, etc. 68 are each screen-printed with a thick film and then dried (see FIG. 12). Since the electrodes 66 and 67 are not fired, the solderability with the connection electrodes 71 of the flat cables 13a and 13b can be improved later.

  An adhesive sheet (not shown) made of an ink non-permeable synthetic resin material as an adhesive layer is formed on the entire lower surface (a flat plate surface facing the pressure chamber 23) of the plate-type piezoelectric actuator 12 having such a configuration. ) Is applied in advance or a thermosetting adhesive is applied, and then the piezoelectric actuators 12a and 12b are applied to the cavity unit 11 and the individual electrodes 36 are applied to the pressure chambers 23 of the cavity unit 11, respectively. Correspondingly, the one end portions 44 and 45 are bonded and fixed with a distance L4 therebetween (see FIGS. 4A and 3). At this time, a planar jig is applied to the upper surfaces of the piezoelectric actuators 12a and 12b, and the piezoelectric actuators 12a and 12b are pushed toward the cavity unit 11, but protrude from the upper surfaces of the piezoelectric actuators 12a and 12b. Since the electrodes 66 and 67 and the dummy portion 68 correspond to the partition wall 70 between the pressure chambers 23 as shown in FIG. 12, the adhesive on the partition wall 70 is piezoelectrically applied by the pressing force applied through the electrode 66. The actuators 12a and 12b are securely bonded to the partition wall 70. Therefore, ink leaks due to poor adhesion, and the pressing force does not act directly on the pressure chamber that is a cavity, so that the pressure chamber can be prevented from being deformed and the piezoelectric actuator can be prevented from cracking.

  Further, the flat cables 13a and 13b are pressed against the upper surfaces of the piezoelectric actuators 12a and 12b so that various connection electrodes 71 of the flat cables 13a and 13b are connected to the individual surface electrodes 66 and Each is electrically connected to the common surface electrode 67.

  In this case, as in the case of bonding the piezoelectric actuator and the cavity unit, the individual surface electrodes 66 are located above the partition wall 70 between the adjacent pressure chambers 23, 23, so that the flexible flat cables 13a, 13b Can be increased, and electrical connection between the connection electrode 71, the individual surface electrode 66, and the common surface electrode 67 can be completed.

  In the embodiment, the first connection pattern for connecting the individual surface electrode 66 on the upper surface of the uppermost sheet of each piezoelectric actuator and the individual electrode 36 by inclining the end 36a of the individual electrode 36. 53, the second connection pattern 56, and the individual conductive layer 58 and the internal conduction electrodes 60, 62, 64 for connecting them vertically are individually separated from the one end 44 (45) in the X-axis direction. Thus, the position of the individual surface electrode 66 can also be biased so as to be greatly separated from the one end 44 (45) in the X-axis direction, and adjacent to the flat cables 13a and 13b to be arranged. A design that does not interfere with each other can be easily achieved by easily separating the intervals.

  In addition, as shown in FIG. 18, the individual surface electrode 66 is retrofitted to the island-shaped individual conductive layer 58 formed on the upper surface of the top sheet 35, so that the X-axis direction (the row direction of the nozzles 24). ), The arrangement position of the individual surface electrode 66 arranged so as to be separated from the one end 44 (45) can be further designed to be shifted within a predetermined range. Accordingly, the distance L5 from the opposing one end 44 (45) of the individual surface electrodes 66, 66 on the conductive layer formed on the upper surface of each of the piezoelectric actuators 12a, 12b arranged in series in the X-axis direction is set as follows. Similarly, if the first end portion 44 (45) and the active portion (pressure chamber 23) are biased so as to be separated from the active portion (pressure chamber 23), the distance from the side edge of each flat cable to the connection electrode 71 is conventional. Even if the road is large, both the flat cables 13a and 13b are joined to the piezoelectric actuators 12a and 12b in a state where they do not overlap with each other at the opposite ends 44 and 45 (a state where they do not interfere with each other). Can be arranged.

  The individual surface electrode 66 and the common surface electrode 67 are omitted, and the connection electrodes 71 of the flat cables 13 a and 13 b are directly connected to the individual conductive layer 58 and the common conductive layer 57 exposed on the upper surface of the top sheet 35. May be joined.

  In this configuration, by applying a high voltage for polarization between all the individual electrodes 36 and the common electrode 37 via the individual surface electrodes 66 and the common surface electrodes 67 in the piezoelectric actuators 12a and 12b, The portions of the piezoelectric sheets 33 and 34 sandwiched between the individual electrodes 36 and the common electrode 37 are polarized. As a result, the portions of the piezoelectric sheets 33 and 34 sandwiched between the individual electrodes 36 and the common electrode 37 serve as active portions. Then, a driving voltage is applied between the individual electrode 36 and the common electrode 37 via an arbitrary individual surface electrode 66 and a common surface electrode 67 to generate an electric field parallel to the polarization direction in the corresponding active portion. As a result, the active portion expands in the stacking direction, the internal volume of the corresponding pressure chamber 23 is reduced, and the ink in the pressure chamber 23 is ejected from the corresponding nozzle 24 in the form of droplets, so that predetermined printing is performed. Is done.

  In this case, as described above, the pattern of the common electrode 37 has a first electrically conductive portion 37a that overlaps with each of the pressure chambers 23 and thus the individual electrode 36 in plan view, and both ends of the first electrically conductive portion 37a. A strip-shaped blank portion 72 can be formed above the partition wall 70 between the adjacent pressure chambers 23 by being connected and configured by the second electrically conductive portion 37 b extending in the column direction of the individual electrodes 36. Therefore, as compared with the case where the common electrode 37 is formed on almost the entire surface of the piezoelectric sheet 34 as in the prior art, the number of nozzle rows and thus the pressure chamber rows increases in proportion to the increase in the number of nozzle rows. The amount of electrically conductive electrode material (conductive paste) such as silver-palladium is reduced, and the manufacturing cost can be reduced.

  Further, since the capacitance of each of the piezoelectric actuators 12a and 12b is small by the amount of the area of the conductive portion of the common electrode 37, the value of the applied voltage (drive voltage) required for ink ejection is set to each of the piezoelectric actuators 12a and 12b. As a result, the drive voltage circuit board can be used for a low voltage, and the manufacturing cost can be reduced.

  Then, compared to a comb-like pattern in which only one end of each first electrically conductive portion 37a is connected to one second electrically conductive portion 37b, two second electric A current flows with little voltage drop along the entire length of each first electrically conductive portion 37a via the conductive portion 37b, so that each active portion can be displaced by piezoelectric strain with a uniform strength over the entire length, The voltage drop also decreases in the column direction of the first electrically conductive portions 37a, and the discharge performance of the nozzle can be made uniform and stable.

  Furthermore, since the pattern of the first electric conduction part 37a and the second electric conduction part 37b is formed so as to surround the circumference of each pressure chamber and the whole circumference of the row of pressure chambers, the piezoelectric actuator is formed by stacking green sheets. There is an effect that the flatness in forming is also improved.

  When four colors of ink (black, cyan, yellow, magenta) are used in color printing, for example, the first row of nozzles 24-1 is used for discharging black ink, and the second row of nozzles 24- When 2 is set to discharge cyan ink, the third row nozzle 24-3 is set to discharge yellow ink, and the fourth row nozzle 24-4 is set to discharge magenta ink, the first formed on the corresponding manifold plate 17 (18). The manifold chamber 26 in the row is filled with black ink, the manifold chamber 26 in the second row is filled with cyan ink, the manifold chamber 26 in the third row is filled with yellow ink, and the fourth row The manifold chamber 26 is filled with magenta ink.

  As described above, in the present embodiment, the pressure chamber 23 is divided into two groups along the row direction of the nozzles 24, and the interval between the groups is increased to L2. Since at least a part of the communication passage 25 communicating with each other is constituted by a concave groove-like flow passage 50 substantially parallel to the flat plate surface of one plate, the arrangement interval (pitch) of the nozzles 24 is set. When a head having a large number of nozzles is manufactured while keeping the same as the conventional one, the piezoelectric actuators 12a and 12b can be used by arranging the nozzles 24 having a short length in the row direction.

  Accordingly, since the amount of contraction when firing each actuator when the piezoelectric actuator is manufactured is reduced, the variation in the interval between the active portions can be reduced, and a piezoelectric actuator with high dimensional accuracy can be manufactured efficiently.

  Moreover, in the said embodiment, although the row | line | column of the nozzle was 4 rows, it can apply with respect to 1 or more nozzle rows in this invention. Needless to say, the present invention can be applied to the joining of a single piezoelectric actuator and a single cable member.

FIG. 2 is a perspective view showing a cavity unit, a piezoelectric actuator, and a flat cable separately of the piezoelectric inkjet printer head according to the first embodiment of the present invention. It is a partial exploded perspective view of a cavity unit. It is an III-III arrow expanded sectional view of FIG. FIG. 4A is an enlarged sectional view taken along the line IV-IV in FIG. 1, and FIG. It is a partial expanded sectional view of a piezoelectric actuator. It is a partial expansion perspective view which shows the position of the individual electrode in a piezoelectric sheet, a dummy electrode, and those internal conduction electrodes. It is a partially cutaway enlarged plan view of a piezoelectric sheet showing a pattern such as a common electrode. It is a partially cutaway enlarged plan view of a piezoelectric sheet showing patterns of individual electrodes and the like. It is a partially notched enlarged plan view which shows the pattern in the lower layer sheet | seat of a constrained layer. It is a partially notched enlarged plan view which shows the pattern in the upper layer sheet | seat of a constrained layer. It is a partially notched enlarged plan view which shows patterns, such as an individual conductive layer, in a top sheet. It is a partially cutout enlarged plan view showing a pattern of individual surface electrodes and the like on the top sheet. It is a partially notched enlarged plan view showing the overlapping relationship between the individual electrode and the dummy electrode with respect to the pressure chamber in the active part. It is a partially cutaway enlarged plan view of a piezoelectric sheet showing details of a pattern such as a common electrode. It is explanatory drawing shown by the more detailed partial enlarged plan view of FIG. It is explanatory drawing shown in the partially expanded plan view of FIG. FIG. 5 is a partially cutaway enlarged plan view showing an overlapping relationship among individual electrodes, first and second connection patterns, and individual conductive layers with respect to a pressure chamber in a plan view of the top sheet. It is a partially notched enlarged plan view showing the overlapping relationship among the individual electrode, the individual conductive layer, and the individual surface electrode with respect to the pressure chamber in a plan view of the top sheet. FIG. 3 is a partially enlarged plan view showing an arrangement relationship between the pressure chambers of FIG. 2 and a grooved communication path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet printer head 11 Cavity unit 12 Piezoelectric actuator 13 Flat cable 22 Base plate 23 Pressure chamber 24 Nozzle 33, 34 Piezoelectric sheet 36 Individual electrode 37 Common electrode 37a 1st electrical conduction part 37b 2nd electrical conduction part 37c 4 circumference side edge conduction part 38 Dummy individual electrode 41, 42, 60 to 65 as first island-like individual conduction portion Internal conduction electrode 43 Dummy common electrode 50 Concave groove-shaped communication path 53 First connection pattern 54 Contact pattern 55 Contact pattern 56 Second connection pattern as two island-shaped individual conductive portions 57 Common conductive layer 58 Individual conductive layer 66 Individual surface electrode 67 Common surface electrode 70 Bulkhead 72 Blank portion

Claims (5)

Can be selectively driven for each pressure chamber in a cavity unit in which a plurality of nozzle rows arranged in a row along the first direction and a row of pressure chambers corresponding to each nozzle are formed. In an inkjet printer head formed by bonding a laminated piezoelectric actuator for ejecting ink having an active part,
Each of the pressure chambers is formed long in a direction intersecting the first direction in plan view,
The piezoelectric actuator is formed by laminating a plurality of sheets including a piezoelectric sheet,
While the piezoelectric sheet between the two electrodes facing each other in the laminating direction of the individual electrode and the common electrode formed sandwiching the piezoelectric sheet in the laminating direction is configured as the active portion corresponding to each pressure chamber,
The common electrode pattern overlaps the arrangement position of each pressure chamber in plan view, and is long along the longitudinal direction of each pressure chamber, and both ends in the longitudinal direction of each pressure chamber Corresponding to the above, an ink jet printer head characterized in that the first electric conductive portion is formed to include a second electric conductive portion connecting both ends of the first electric conductive portion along the first direction.   The same flat surface on which the common electrode pattern is formed is electrically connected to each individual electrode in the sheet adjacent in the stacking direction via an internal conductive electrode penetrating in the plate thickness direction of the piezoelectric sheet. 2. The inkjet according to claim 1, wherein the first island-shaped individual conductive portion is formed at a predetermined distance from an edge extending along the first direction in the common electrode pattern. Printer head. On one flat plate surface of the sheet laminated above the piezoelectric sheet constituting the active part, a common conduction part electrically connected to a part of the pattern of the common electrode is formed,
The second island-shaped individual conductive portion for electrically conducting through each first island-shaped individual conductive portion and the internal conductive electrode penetrating in the plate thickness direction of the sheet is a pattern of the common conductive portion. The inkjet printer head according to claim 2, wherein the inkjet printer head is formed at a predetermined distance from an edge extending along the first direction. The row of nozzles and the row of pressure chambers corresponding thereto are arranged in a plurality of rows at appropriate intervals in a second direction intersecting the first direction,
On the flat plate surface of the piezoelectric sheet, edges extending along the first direction in the pattern of the common electrode are formed at appropriate intervals in the second direction, and the first island-shaped individual conducting portion is formed. 4. The ink jet printer head according to claim 3, wherein the second island-shaped individual conductive portion is formed in a region between the two edges.   Four rows of the plurality of nozzles are arranged, and the piezoelectric actuators arranged corresponding to the rows of the nozzles have four rows of active portions corresponding to the rows of the nozzles. The ink jet printer head according to claim 1, wherein

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