JP2005088516A - Inkjet printer head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To arbitrarily provide a fitting embodiment by turning reversely the drawing direction of a flexible flat cable 40 to a piezoelectric actuator 12. <P>SOLUTION: On a wide width face of a top sheet 35 of the piezoelectric actuator 12, a number of individual surface electrodes 58 electrically conducted to an individual electrode, and a number of common surface electrodes 57 electrically conducted to a common electrode, are formed in an island shape. The common surface electrodes 57 and the individual surface electrodes 58 are arranged in a point symmetry using a central point on the wide width face of the top sheet 35 as a center O of symmetry, and are arranged in a point symmetry using an individual connecting electrode part 78 formed on the wide width face of the flexible flat cable 40 as the center O of symmetry. The common connecting electrode part 77 is composed of the first parts 77a and 77a along a pair of long side edges, and the second parts 77b connecting to this and along a free end edge, and can be electrically connected respectively with a number of the common surface electrodes 57 and the individual surface electrodes 58 when the flexible flat cable 40 is rotatably moved by 180°around the center O of symmetry. <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 has a nozzle plate having a plurality of nozzles, a base plate having a pressure chamber for each nozzle, and a manifold chamber as a common ink chamber connected to the ink supply source and connected to each pressure chamber. It consists of a manifold plate and the like. 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 (joining electrode) in the flexible flat cable for transmitting an external control signal and the surface electrode of the uppermost sheet of the piezoelectric actuator are joined. On the other hand, the surface electrode and the individual electrode or the common electrode are connected by a conductive portion extending in the stacking direction of the piezoelectric actuator.

  In this case, the surface electrode for the common electrode and the surface electrode for the individual electrode are arranged on the uppermost sheet of the piezoelectric actuator in the longitudinal direction of the sheet (the direction in which the nozzle row extends, the pressure chamber, and hence the active portion row). As a result of being arranged in the vicinity of the left and right side edges along the direction), the lead having a fine width to be connected to the joining electrode (joining terminal portion) in the flexible flat cable and to be connected to the external driving IC (integrated circuit element) Since a large number of lines are formed in the narrow part of the sheet (in the direction perpendicular to the short side), the distance between adjacent lead wires is proportional to the increase in the number of active parts by subtracting the number of nozzles. And the mutual inductance generated between adjacent lead wires increases, and there is a problem that the printing performance deteriorates.

Therefore, as shown in Patent Document 3, by extending a flexible flat cable in a direction orthogonal to the long side direction of the uppermost sheet, a lead wire having a fine width is formed along the extending direction of the flexible flat cable. It has been considered to prevent the mutual inductance from increasing.
JP 2002-36544 A Japanese Patent Laid-Open No. 2002-19102 JP 2001-260349 A

  By the way, the cavity unit and the piezoelectric actuator are prepared in the form of a pre-joined nozzle head, and the flexible flat cable joined to the nozzle head is fixed to the lower surface of a carriage on which an ink cartridge or the like can be mounted. The other end of the flexible flat cable is connected to a control board that outputs a print command of the main body of the printer. Which side of the pair of long sides of the nozzle head to draw the flexible flat cable from the outside depends on the design of the printer, but the surface formed on the surface of the uppermost sheet of the piezoelectric actuator according to the drawing direction If the electrode pattern had to be changed, the manufacturing cost would increase.

  The present invention has been made to solve the above-mentioned conventional problems, and by devising the pattern of the surface electrode for the individual electrode and the surface electrode for the common electrode formed on the surface of the uppermost sheet of the piezoelectric actuator. An object of the present invention is to provide an ink jet printer head capable of changing the drawing direction of the flexible flat cable by 180 degrees and reducing the manufacturing cost.

  In order to achieve the above-mentioned object, the invention according to claim 1 includes a plurality of nozzle rows composed of a plurality of nozzles arranged in a row along the first direction and a pressure chamber corresponding to each nozzle. A laminated piezoelectric actuator having an active portion that can be selectively driven for each pressure chamber and having a plurality of rows formed therein is joined to the cavity unit, and a wide surface of the piezoelectric actuator is bonded to the cavity unit. In the ink jet printer head formed by joining the electrode portion for joining formed on the wide surface of the flexible flat cable to the surface electrode formed on the piezoelectric actuator, the piezoelectric actuator is formed by laminating a plurality of sheets including a piezoelectric sheet. The piezoelectric sheet between the two 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 is The wide area of the top sheet of the piezoelectric actuator is configured to be the active portion corresponding to each pressure chamber, and a large number of individual surface electrodes that are electrically connected to the individual electrodes are electrically connected to the common electrode. The common surface electrodes and the individual surface electrodes are arranged in a point-symmetrical manner with the center point of the wide surface of the surface sheet as the center of symmetry. The junction electrode portion formed on the wide surface of the flexible flat cable is electrically connected to the common surface electrodes and the individual surface electrodes when the flexible flat cable is rotated 180 degrees about the symmetry center. Are arranged so that they can be joined together.

  According to a second aspect of the present invention, in the ink jet printer head according to the first aspect, the common surface electrode is a portion near the outer periphery of the wide surface of the surface sheet and is perpendicular to the first direction. The individual surface electrodes are formed in a portion near the inner periphery of the wide surface of the surface sheet.

  According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, the flexible flat cable is joined by rotating 180 degrees along a second direction orthogonal to the first direction. It is configured to be possible.

  According to a fourth aspect of the present invention, in the inkjet printer head according to any one of the first to third aspects, the common bonding electrode portion formed on the flexible flat cable and bonded to the common surface electrode includes: The flexible flat cable is formed in a strip shape on a pair of side edges along the second direction and a free end edge in the first direction that communicates with the pair of side edges. It is formed in a region surrounded by.

  According to the first aspect of the present invention, the common surface electrode and the individual surface electrode are arranged symmetrically with respect to the center point of the wide surface of the surface sheet, while the flexible flat cable The junction electrode portion formed on the wide surface of the first electrode is electrically joined to the plurality of common surface electrodes and individual surface electrodes, respectively, when the flexible flat cable is rotated 180 degrees around the symmetry center. Therefore, it is possible to extremely easily perform the operation of rotating the flexible flat cable by rotating the drawing direction by 180 degrees and using the same head unit.

  According to the second aspect of the present invention, the common surface electrode includes a plurality of the surface electrodes closer to the outer periphery of the wide surface of the surface sheet, with appropriate intervals in the first direction and the second direction perpendicular thereto. Since the plurality of groups of common surface electrodes and the common junction electrode portion on the wide surface of the flexible flat cable can be joined to each other, the joint strength is improved. Therefore, even if the flexible flat cable expands and contracts in the first direction due to a temperature change or the like, it is possible to improve reliability without causing peeling of the joint.

  In addition, since the individual surface electrode is formed near the inner periphery of the wide surface of the surface sheet, a large number of corresponding individual joints are used by utilizing a wide area of the wide surface of the flexible flat cable. There is an effect that the electrode part and its lead wire can be arranged.

  According to the third aspect of the present invention, the width of the flexible flat cable can be increased in parallel with the longitudinal direction (first direction) of the topsheet and thus the piezoelectric actuator. The area margin for arranging the joining electrode portion for the individual electrode and the lead wire thereof is increased, and the degree of freedom in design is improved.

  According to the fourth aspect of the present invention, among the joint portions between the piezoelectric actuator and the flexible flat cable, the joint portion for common can extend in the first direction and the second direction to increase the joint area. There exists an effect that intensity | strength can be improved further.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a perspective view of an ink jet printer to which the present invention is applied, FIG. 2 is a plan view of the printer head according to the first embodiment viewed from the back side, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. 4 is a perspective view of each component of the head unit, FIG. 5 is a partially enlarged perspective view of the main part of the cavity unit, FIG. 6A is a cross-sectional view taken along line VI-VI in FIG. 4, and FIG. FIG. 8 is a partially enlarged sectional view of the piezoelectric actuator, FIG. 9 is a partially enlarged perspective view showing the positions of the individual electrodes, dummy electrodes and their internal conductive electrodes in the piezoelectric sheet, and FIGS. Is a diagram showing electrode patterns of each layer in the piezoelectric actuator 12, FIGS. 18 to 19 are plan views showing the overlapping state of the electrode patterns, and FIG. 20 is an overlapping arrangement of the surface electrode of the piezoelectric actuator and the joining electrode of the flexible flat cable. Is a plan view showing the state.

  As shown in FIG. 1, a color inkjet printer 100 according to the present invention includes, for example, an ink cartridge 61 in which four color inks of cyan, magenta, yellow, and black are partitioned and filled, and a sheet ( An ink jet printer head (hereinafter simply referred to as a printer head) 63 for printing on a recording medium) 62, a carriage 64 on which the ink cartridge 61 and the printer head 63 are mounted, and the carriage 64 in the transport direction of the paper 62 ( Extending in the reciprocating direction of the carriage 64 and the drive unit 65 for reciprocating in the sub-scanning direction (hereinafter referred to as the first direction or Y direction) (main scanning direction, hereinafter referred to as the second direction, X direction); A platen roller 66 disposed opposite to the printer head 63 and a purge device 67 Eteiru.

  The drive unit 65 is disposed at the lower end portion of the carriage 64 and extends parallel to the platen roller 66, the guide plate 72 is disposed at the upper end portion of the carriage 64 and extends parallel to the carriage shaft 71, and the carriage shaft 71. And the guide plate 72, and two pulleys 73 and 74 disposed at both ends of the carriage shaft 71, and a timing belt 75 wound around the pulleys 73 and 74.

  The carriage 64 joined to the timing belt 75 is supported by the carriage shaft 71 and the guide plate 72 and can reciprocate linearly by the driving force from one pulley 73 that rotates in accordance with the driving of the motor 76.

  The paper 62 conveyed in the Y direction (first direction) from a paper supply unit (not shown) is introduced between the platen roller 66 and the printer head 63 and ejected from the printer head 63 as will be described later. As a result, predetermined printing is performed, and then the paper is discharged.

  The purge device 67 is provided on the side of the platen roller 66 and is disposed so as to face the printer head 63 when the printer head 63 is in the reset position. The purge device 67 includes a purge cap 81 that abuts against an opening surface of the nozzles 11a of the printer head 63, which will be described later, a pump 82 and a cam 83, and an ink reservoir 84. Yes. When the printer head 63 is at the reset position, the defective ink containing bubbles and the like accumulated inside the printer head 63 is sucked by the pump 82 by driving the cam 83 so that the printer head 63 is recovered. Yes. The sucked defective ink is stored in the ink storage section 84.

  A wiper member 86 is disposed adjacent to the purge device 67 at a position on the platen roller 66 side in the purge device 67. The wiper member 86 is formed in a spatula shape, and wipes the nozzle surface of the printer head 63 as the carriage 64 moves. When the nozzle surface is wiped, the wiper member 86 protrudes upward, and when the nozzle surface is not wiped, it retracts downward.

  The cap 85 covers the plurality of nozzles 11a of the printer head 63 mounted on the carriage 64 that is returned to the reset position when printing is completed in order to prevent ink from drying.

  As shown in FIGS. 2 and 3, the printer head 63 has a plurality of nozzles 11a (see FIG. 7) arranged in a row in the Y direction (first direction) on the front surface (lower surface in FIG. 3). A head unit 6 and a head holder 1 for fixing and supporting the back side of the head unit 6 via an adhesive as will be described later are provided.

  The head holder 1 includes the mounting portion 3 on which the ink cartridge 61 described above is mounted, and ink is supplied from the ink cartridge 61 to the head unit 6 via an ink supply sleeve 4 for each color described later. It has become so.

  In that case, as shown in FIGS. 2 and 3, a slit 87 for pulling out the flexible flat cable 40 fixed to the head unit 6 is formed in the bottom plate 1 a of the head holder 1 which is the lower surface of the mounting portion 3 of the ink cartridge 61. And an adhesive 89 for fixing the through holes 88 and 88 for projecting the four cylindrical sleeves 4 projecting from the head unit 6 and a protruding portion of a spacer plate 19 having high rigidity, which will be described later, to the head holder 1. Pour holes 89a and 89b for use are formed. As the adhesive 89, for example, a UV adhesive which is a photo-curing adhesive is injected.

  The slit 87 is formed elongated along the long side (Y direction) near the center of the bottom 1a. The pouring holes 89a and 89b are formed in a trapezoidal shape opposite to each other in a side sectional view in which the area of the opening on the lower surface side of the bottom plate 1a is smaller than the area of the opening on the upper surface side. A plurality of locations are provided along. Each casting hole 55 is opened to face the upper surface of the overhanging portion of the spacer plate 19 having high rigidity.

  Next, the configuration of the head unit 6 will be described. As shown in FIGS. 4 to 7, the head unit 6 has a cavity unit 10 formed by laminating a plurality of metal plates, and is bonded and laminated to the cavity unit 10 via an adhesive or an adhesive sheet. The plate-type piezoelectric actuator 12 and a flexible flat cable 40 joined to the back surface (upper surface) of the plate-type piezoelectric actuator 12 for electrical connection with an external device.

  As shown in FIGS. 2 and 4, the head unit 6 of this embodiment is a long head that is provided with a large number of nozzles 11 a and is long in the Y direction (first direction). The head holder 1 to which is attached is also configured to be long in the Y direction, as shown in FIG.

  The cavity unit 10 is configured as shown in FIGS. That is, a total of 9 base plates 22 in which the nozzle plate 11, 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. It is the structure which laminated | stacked by laminating | stacking the flat board of 1 sheet with the adhesive agent, respectively.

  The rigidity of at least one spacer plate among the plurality of spacer plates 19 to 21 is set to be higher than the rigidity of other plates (including nozzle plate, cover plate, damper plate, manifold plate, spacer plate, and base plate). Is set to be larger (higher).

  In this embodiment, the size of the plate in the stacking direction (plate thickness direction) is considerably smaller than the vertical and horizontal dimensions of the flat plate surface. . For example, with the outer peripheral portion of the flat plate of the cavity unit fixed, the bending rigidity (longitudinal elastic modulus and cross-sectional secondary moment) with respect to bending vibration or bending deformation of the flat plate of the cavity unit due to an external force perpendicular to the flat plate surface. Product).

  In order to increase (increase) the rigidity, except for the nozzle plate 11 made of synthetic resin, each of the plates 15 to 22 is made of 42% nickel alloy steel plate, and the cover plate 15, damper plate 16, manifold plates 17, 18, The upper two spacer plates 20 and 21 and the base plate 22 have a thickness of about 50 μm to 150 μm. On the other hand, the thickness of the first spacer plate 19 disposed immediately above the manifold plate 18 is about 300 μm to 500 μm, which is set to be much larger than the rigidity of the other plates 11, 15 to 18, and 20 to 22. . In the illustrated embodiment, the plan view shape of the first spacer plate 19 is made larger than the plan view shapes of the other plates. For example, the outer peripheral edge of the first spacer plate 19 that is also rectangular in plan view is formed so as to appropriately protrude by the dimension H1 with respect to the outer peripheries of the other plates 11, 15 to 18, and 20 to 22 in rectangular shape in plan view. Yes.

  As another means for increasing the rigidity of the first spacer plate 19, in addition to the plate thickness, the strength (tensile strength) of the material of the plate is increased. For example, the material of the plate other than the first spacer plate 19 is chromium strong steel, and the material of the first spacer plate 19 is nickel / chrome / molybdenum steel, stainless steel, tungsten steel, cobalt / chromium / tungsten steel, etc. Use materials with different tensile strengths. Moreover, you may raise rigidity by hardening carbon steel and alloy steel.

  In the embodiment, the rigidity of the first spacer plate 19 adjacent to the manifold plates 17 and 18 immediately above is increased, but the rigidity of the third spacer plate 21 adjacent to the base plate 22 having the pressure chambers 23 is directly below (lower surface). May be increased, the rigidity of the second spacer plate 20 may be increased, or the rigidity of both may be increased. When there is one spacer plate interposed between the base plate 22 and the manifold plate 18, the rigidity thereof is increased.

  The nozzle plate 11 has a large number of nozzles 11a 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 10). In FIG. 3, the rows formed in the Y direction and the sub-scanning direction) are provided in a four-row staggered arrangement.

  That is, the cavity unit 10 is cut along the X direction (short side direction, main scanning direction) in FIG. 1, and only the right side of the center line C of the short side is shown in FIG. The nozzles 11a-1 in the row and the nozzles 11a-2 in the second row closer to the center line C are two parallel adjacent reference lines (not shown) extending in the first direction of the nozzle plate 11. In the same manner, the third row of nozzles 11a-3 and the fourth row are arranged on the left side of the center line C. The nozzles 11a-4 (however, not shown in FIG. 6A) are each a minute pitch P along two parallel adjacent reference lines extending in the first direction (Y direction). A large number of holes are formed in a staggered arrangement at intervals of. Further, a set of the first row nozzle 11 a-1 and the second row nozzle 11 a-2, and a set of the third row nozzle 11 a-3 and the fourth row nozzle 11 a-4 are the cavity unit 10. They are arranged in parallel in the short side direction (second direction, X direction in FIG. 1, main scanning direction) with an interval. 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 11a is 150, that is, the arrangement density is 75 (dpi [dot per inch]). is there.

  The base plate 22 which is the uppermost layer of the cavity unit 10 shown in FIG. 4 is provided with pressure chambers 23 penetrating in the plate thickness direction with the same pitch P corresponding to the nozzles 11a. The pressure chambers 23 are formed in a row in the long side direction (Y direction) of the cavity unit 10. Accordingly, the adjacent pressure chambers 23 are isolated from each other by an elongated partition wall 24 that is substantially parallel to the short side of the cavity unit 10. The width dimension W2 of each partition wall 24 is set slightly smaller than the width dimension W1 of the pressure chamber 23 (see FIG. 5).

  The first row of pressure chambers 23-1 corresponds to the first row of nozzles 11a-1. Similarly, the second row of pressure chambers 23-2 is the second row of nozzles 11a-2, the third row of pressure chambers 23-3 is the third row of nozzles 11a-3, and the fourth row of pressure chambers. 23-4 has a corresponding relationship with the fourth row of nozzles 11a-4.

  Next, two piezoelectric actuators 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 10 is arranged in the column direction (first direction, Y direction) of the nozzles 11a thereon. This will be described from the relationship with the arrangement of the active portion in 12 (indicated by 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 11a 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 10 in the longitudinal direction (the Y direction), and the other piezoelectric actuator 12b is disposed in the rear half. The

  Each of the piezoelectric actuators 12a (or 12b), as will be described in detail later, has the piezoelectric between the electrodes facing each other in the stacking direction of the individual electrode 36 and the common electrode formed by sandwiching the piezoelectric sheet in the stacking direction. A sheet is provided as an active part, and a voltage is applied between an arbitrary individual electrode 36 and a common electrode 37, whereby a piezoelectric sheet is applied in the stacking direction to the active part of the piezoelectric sheet corresponding to the applied individual electrode 36. Distortion due to the vertical effect is generated. The active portions are formed in the same number in the same row with the same number as the number of pressure chambers 23.

  That is, the active portions are arranged along the row direction (first direction, Y direction) of the nozzles 11a (pressure chambers 23), and are the same number as the number of the nozzle rows (four). Are arranged in the direction (X direction). 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 10, the X direction), and the arrangement interval (pitch P) between adjacent active parts is also described later. Similar to the arrangement of the pressure chambers 23, the pressure chambers 23 are arranged in a staggered manner.

  The pressure chambers 23 are arranged in two groups in the longitudinal direction (Y direction) of the base plate 22 corresponding to the two piezoelectric actuators 12a and 12b. That is, the group of pressure chambers 23 corresponding to one actuator 12a corresponds to the one in the first half of the nozzle 11a in the column direction (Y direction), and the group of pressure chambers 23 corresponding to the other actuator 12b is the nozzle 11a. Corresponding to the latter half in the row direction (Y direction) of each, the same interval as the arrangement interval (pitch P) of the nozzles 11a, and two sets of two staggered arrangements 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, X 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. 5 and FIG. 6 (a)).

  Further, 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 11. The nozzles 11a communicate with each of the nozzles 11a through the communication passages 25 as flow passages. A part of the communication passage 25 is at least one of the plates 15 to 21 stacked between the base plate 22 and the nozzle plate 11. 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 11a corresponding to each pressure chamber 23 can be determined. The straight line (perpendicular line) orthogonal to the surface of the base plate 22 reaches the nozzle plate 11 from the outflow end 23a (ink outflow portion) of the nozzle 23. More, in which it is possible to set the horizontal direction (direction along the first direction of the plate, Y-direction) at a position shifted by a distance L3 (see FIG. 7).

  That is, as shown in FIGS. 4 and 7, the gap L2 between the pressure chambers 23 of the two groups of the piezoelectric actuators 12a and 12b is wider than the arrangement interval (pitch P) of the pressure chambers 23 in the longitudinal direction of the base plate 22. 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. The piezoelectric actuators 12a and 12b are arranged in series (see FIG. 7).

  As a result, the pitch P of the nozzles 11a is set to be constant in the column direction, but the position of the corresponding pressure chamber 23 is transverse to the line (perpendicular) perpendicular to the plate thickness (Y direction). ) Is shifted by a distance L3, so that at least a part of the communication passage 25 connected from the outflow end 23a of each corresponding pressure chamber 23 to the nozzle 11a is a concave groove parallel to the flat plate surface of the plate as described above. By configuring the plate-like communication path 50, the communication paths 25 in the other plates are penetrated perpendicularly to the plate thickness direction of each plate, and only communicated with one end and the other end of the concave groove-shaped communication path 50. Thus, the lateral shift can be dealt with. 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 FIGS. 5 and 7A, one end 50a that is open to the surface (upper surface) side of the third spacer plate 21 and communicates with the outflow end 23a of the corresponding pressure chamber 23; From the 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 50c communicating with the upper end of the vertical communication passage 25 in the lower second spacer plate 20. Become.

  Thus, a part of the communication path 25 as an ink flow path from the pressure chamber 23 to the corresponding nozzle 11a is formed in the concave groove-shaped communication path 50 extending in parallel with the plane of the plate, and the other communication paths. By adopting a shape that penetrates the nozzle 25 in the direction perpendicular to the plane of the plate, even if the position of the nozzle 11a corresponding to the pressure chamber 23 is greatly displaced in plan view, the ink flow that allows both to communicate easily The road can be designed. Further, it is extremely easy to control so that the total length (the distance including the concave groove-shaped communication path 50) of the communication path 25 as the ink flow path from each pressure chamber 23 to the corresponding nozzle 11a 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 11a. 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 10 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.

  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 immediately above the manifold plates 17 and 18, which is a combination of the two plates. The plate 19 and the lower damper plate 16 are stacked so as to be 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, a retreat component propagated by ink and directed toward the manifold chamber 26 is absorbed by the vibration of the damper plate 16 having a thin plate thickness, so-called crosstalk occurs. It is prevented from occurring.

  The second spacer plate 20 is formed with an ink flow restricting portion 28 corresponding to each pressure chamber 23. As shown in FIG. 6B, the diaphragm portion 28 is formed such that the area of both end portions 28a and 28b in the longitudinal direction is large and the middle area is small as shown in FIG. 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 28b of the throttle portion 28 with the inlet end 23b of the pressure chamber 23 (FIGS. 5 and 6A). reference).

  A total of eight ink supply holes 31 are provided for each manifold chamber 26, as shown in FIG. The ink supply hole 31 is a set of two (one color), and a filter 32 for removing dust in the ink supplied from the ink cartridge 61 is fixed to the upper surface of the ink supply hole 31 with an adhesive.

  In addition, on each filter 32 (a set of two ink supply holes 31), cylindrical sleeves 4 project from the ink cartridge 61 in order to receive ink (see FIG. 2). Each sleeve 4 has an ink passage inside, and has a large-diameter portion with a large outer diameter at the lower portion and a small-diameter portion with a small outer diameter at the upper portion, and each lower end surface thereof is above the filter 32. It is firmly bonded and fixed with epoxy resin or the like. The outer periphery of the small diameter portion is fitted with a rubber packing or an O-ring that is an annular elastic seal body in order to prevent ink leakage when connecting to the flow path member connected to the ink cartridge 61. (Not shown).

  Next, the configuration of the piezoelectric actuator 12 will be described in detail. As shown in FIG. 8, each piezoelectric actuator 12 (indicated by reference numerals 12a and 12b) is a plurality of (seven in the embodiment) piezoelectric ceramic plates each having a thickness of about 30 μm. A structure in which sheets 33 and 34 are alternately stacked, a constraining layer including two sheets 46 and 47 is stacked on the top surface of the group, and a top sheet 35 as a surface sheet is stacked on the top surface. is there. 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) It is formed in a row along the long side direction, the Y direction in FIG. 3, and the row direction of each nozzle 11a.

  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. In addition, the individual electrode 36-2 in the second row and the individual electrode 36-3 in the third row are arranged in the central portion of each piezoelectric sheet 33 in the short side direction (see FIG. 11).

  The pattern of each individual electrode 36-1, 36-2, 36-3, 36-4 is parallel to the short side of each piezoelectric sheet 33 along a second direction (X direction) orthogonal to the first direction. It extends in a shape. 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. 11). 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. 11). reference).

  Further, each end portion 36a has a first individual connection pattern of a dummy individual electrode 38 (see FIG. 10) as a first island-like individual conduction portion in the piezoelectric sheet 34 adjacent vertically, and a lower layer sheet 46 in a constraining layer described later. 53 (see FIG. 12) at least partially overlaps with each other in plan view, and is disposed at a position where it can be electrically connected to the internal conduction electrodes 42a, 42b, and 90 penetrating the piezoelectric sheet 34 and the lower layer sheet 46 (see FIG. 12). 11, see FIG.

  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 (see FIG. 11).

  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. 10 and 15). 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 first electric conduction portion 37a that is long in the longitudinal direction (X direction) of each pressure chamber 23 (the straight portion 36b of the individual electrode 36), and in the longitudinal direction of each pressure chamber 23. Corresponding to both end portions 23a and 23b, a second electrically conductive portion 37b that connects (electrically connects) both ends of the first electrically conductive portion 37a along the first direction (Y direction) is formed. To form. The pattern of the common electrode 37 will be described in more detail with reference to FIGS. 10 and 15. For example, the plan view having a length substantially equal to the longitudinal dimension of each pressure chamber 23 of the pressure chamber 23-1 in the first row. A rectangular first electrical conducting portion 37a and the upper ends corresponding to the longitudinal ends 23a, 23b of each pressure chamber 23 are connected to both ends of each first electrical conducting portion 37a, and the pressure chambers 23 are arranged in the column direction. A second electrically conductive portion 37b extending in the (Y direction), and is a region surrounded by the first electrically conductive portion 37a and the second electrically conductive portion 37b, and the first row of pressure chambers 23-1. A strip-shaped blank portion 48 is formed above the partition wall 24 located between the adjacent pressure chambers 23.

  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. 10 and 15).

  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 (X direction) in which the straight line of the one end 44 (45) of the piezoelectric actuator 12a (12b) extends in plan view ( (See FIG. 10).

  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 The interval between the contour edges is set to a certain distance.

  Thus, when each dummy individual electrode 38 as the first island-shaped individual conductive portion is formed in an inclined shape, the length of each dummy individual electrode 38 can be formed long, while the contour of the adjacent pattern region is The distance 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 edges constant (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 or more. When a voltage is applied to each of the electrodes, current does not leak between adjacent electrodes, and only the active portion corresponding to a predetermined pressure chamber can be operated reliably, and the print quality can be maintained well. There is an effect. As a result, the size of the short side (X 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 at a position that does not overlap vertically in a plan view and is appropriately separated by a distance e1 (see FIG. 9).

  On the upper surface of the lower sheet 46 of the two sheets 46, 47 as the constraining layer, as shown in FIG. 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 is also inclined at an angle α (an acute angle of about 60 degrees) with respect to the direction (X direction) in which the one end 44 (45) of the piezoelectric actuator 12a (12b) extends in a plan view. It extends to. 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. 13, 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. 13 and 18). 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 of the pattern areas 56 and 56 is set to a constant distance.

  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 of each second connection pattern 56 can be formed long, but adjacent to each other. The distance 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 at a constant distance (see FIGS. 14 and 18). 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 (X direction) of each piezoelectric actuator 12a (12b) can be shortened, and the ink jet printer head can be formed compactly.

  As shown in FIGS. 16 and 18, the upper surface of the top sheet 35 as a top sheet which is the uppermost layer of the piezoelectric actuator 12 overlaps with a part of the contact pattern 55 in the upper layer sheet 47 in plan view. Thus, a plurality of common conductive layers 51 are formed. 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 52 (individually indicated by reference numerals 52-1, 52-2, 52-3, 52-4) are arranged and formed at regular intervals (see FIG. 18). As shown in FIG. 16, each of the individual conductive layers 52-1, 52-2, 52-3, 52-4 has a short edge (in the X direction) of the top sheet 35, and further, each individual electrode 36-1, Although it is substantially parallel to 36-2, 36-3, and 36-4 and extends in the direction of the portion of the straight portion 36b of each individual electrode, it is shorter than the straight portion 36b of each individual electrode. Further, the individual conductive layers 52-1, 52-2, 52-3, 52-4 formed on the upper surface of the top sheet 235 are arranged in parallel below each other as shown in FIGS. 18 and 19. It is located above the partition wall 24 between the pressure chambers 23, 23 adjacent to each other. In FIG. 18, it is slightly shifted from the center of the partition wall 24, but it may be made to coincide with the center.

  Furthermore, as shown in FIG. 17, the top sheet 35 is connected to the upper surface of the top sheet 35 to the common junction electrode portion 77 and the individual junction electrode portion 78 formed on the lower surface of the flat cables 40 and 40, respectively. As the surface electrode (retrofitted electrode), an individual surface electrode 58 having a rectangular shape in plan view and a common surface electrode 57 are formed. In this case, as shown in FIG. 19, the individual surface electrode 58 is flat on an appropriate portion in the length direction of each individual conductive layer 52-1, 52-2, 52-3, 52-4 in the top sheet 35. It is formed in an island shape so as to overlap and partially connect electrically when viewed, and in the column direction (Y direction) of each individual conductive layer 52-1, 52-2, 52-3, 52-4 Adjacent locations are arranged in a staggered manner so as to be displaced in the X direction.

  In other words, in the illustrated embodiment, each individual surface electrode 58 is disposed 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 portion, And it arrange | positions above the partition 24 between the adjacent pressure chambers 23 and 23 (refer FIG. 19).

  As a modification of this embodiment, the individual surface electrodes 58 arranged above the partition wall 24 between the adjacent pressure chambers 23 are arranged with respect to the corresponding pressure chambers 23 (active parts). The distance may be shifted in the Y direction by a distance of 1.5 times (pitch P).

  Further, as shown in FIGS. 4 and 19, the individual surface electrode 58 at a position closest to the opposing end portions 44 and 45 of the two piezoelectric actuators 40 and 40 arranged in series is arranged at 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.

  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 90 are formed of conductive members (conductive paste) filled in the through holes, respectively (see FIG. 12).

  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. An internal conduction electrode 91 made of a conductive member filled in each is formed (see FIG. 12).

  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 92 and the contact pattern 55 and the contact pattern 54 are electrically connected to each other in the through hole in order to electrically connect the portions 53-3 and 53-4 individually. Internal conduction electrodes 93 are respectively formed in the holes (see FIG. 13).

  In the same manner as described above, the top sheet 35 is provided with the positions of the individual conductive layers 52-1, 52-2, 52-3, 52-4, and the second connection pattern 56-in the upper layer sheet 47 adjacent below. An internal conduction electrode 94 is provided in the through hole in order to electrically connect the parts 1, 56-2, 56-3 and 56-4 individually, and the top sheet 35 is provided for its common use. Internal conductive electrodes 95 are formed in the through holes in order to electrically connect the conductive layer 51 and the connection pattern 55 in the upper layer sheet 47 adjacent below (see FIG. 16).

  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, 90, 92, 94 at positions that do not overlap in plan view.

  Further, the common surface electrode 57 is retrofitted in an island shape so as to overlap a part of the common conductive layer 51 formed on the upper surface of the top sheet 35 in plan view. Retrofitting of the common surface electrode 57 and the individual surface electrode 58 is performed by screen-printing a silver-palladium conductive member.

  In this case, the common surface electrode 57 shown by a black rectangle in FIG. 17 and the individual surface electrode 58 shown by a white rectangle have a center point O in a plan view of the wide surface of the top sheet 35 as a symmetrical center. They are arranged symmetrically. It should be noted that the number of individual surface electrodes 58 shown in FIG. 17 is smaller than that of the embodiment so that the illustration becomes clear.

  On the other hand, corresponding joint electrode portions (common joint electrode portion 77 and individual joint electrode portion 78) formed on the wide surface of the flexible flat cable 40 are horizontally 180 degrees with the flexible flat cable 40 as the symmetry center O. They are arranged so that they can be electrically joined to the large number of common surface electrodes 57 and individual surface electrodes 58 when rotated (see FIG. 20).

  The above embodiment will be described in more detail. The common surface electrode 57 is a portion near the outer periphery of the wide surface of the top sheet 35, and the second direction perpendicular to the first direction (Y direction). They are arranged and formed in a plurality of groups at appropriate intervals in the (X direction). For details, in FIG. 17, the first group 57-1 in the vertical position (two) and the vertical position (two) arranged along the left and right side edges in the first direction (Y direction) of the top sheet 35. The second group 57-2 and the upper and lower positions arranged so as to straddle the left and right sides of the Y1 axis parallel to the first direction (Y direction) through the symmetry center (fixed point) O of the top sheet 35. (Second) third group 57-3 and the fourth group 57-4 in the vertical position (two) arranged between the first group 57-1 on the left side of the Y1 axis and the Y1 axis On the right side of the second group 57-2 and the fifth group 57-5 in the vertical position (two). The common surface electrodes 57 of the first group 57-1 and the second group 57-2 are arranged equidistant from the fixed point O on opposite sides of the symmetry center (fixed point) O, respectively. The common surface electrodes 57 in the upper and lower third groups 57-3 are also arranged at equal distances from the fixed point O on opposite sides of the symmetry center (fixed point) O, respectively. Further, the common surface electrodes 57 of the fourth group 57-4 and the fifth group 57-5 are also arranged at equal distances from the fixed point O on the opposite sides of the symmetry center (fixed point) O, respectively. Naturally, the individual surface electrode 58 is also arranged at an equal distance from the fixed point O on the opposite side across the center of symmetry (fixed point) O at the inner peripheral portion of the wide surface of the top sheet 35.

  On the other hand, on the lower surface (wide surface) of the flexible flat cable 40, a common bonding electrode portion 77 bonded to the common surface electrode 57 and an individual bonding electrode portion 78 bonded to the individual surface electrode 58. And are formed. In the embodiment shown in FIG. 20, the common joint electrode portion 77 communicates with first portions 77 a and 77 a along a pair of side edges along the second direction (X direction) in the flexible flat cable 40, and these. In addition, the second portion 77b is formed in a strip shape along the free end edge in the first direction (Y direction). The large number of individual bonding electrode portions 78 correspond to the individual surface electrodes 58 in a region surrounded by the common bonding electrode portions 77 (a pair of first portions 77a and 77a and a second portion 77b). Is formed. One end of a lead wire (not shown) extending along the second direction (X direction) is connected to each individual joint electrode portion 78, and the other end of each lead wire and the common joint electrode portion 77 are connected to each other. The other end is electrically joined to a driving integrated circuit 40a (see FIG. 2) attached to one side of each flexible flat cable 40.

  When configured as described above, for example, as shown by a two-dot chain line in FIG. 4 and a solid line in FIG. 20, the flexible flat cable 40 is pulled out from the right side of the long side of the head unit 6 to the top of the piezoelectric actuator 12. When bonding to the sheet 35, the second portion 77b of the common bonding electrode portion 77 is bonded to the first group 57-1, while the first portions 77a and 77a are connected to at least the third group 57-3 and the first group 57-1. The fifth group 57-5 is joined (in addition, the fourth group 57-4 may be joined).

  Conversely, when the flexible flat cable 40 is joined to the top sheet 35 of the piezoelectric actuator 12 so as to be pulled out to the left of the long side of the head unit 6, as shown by the solid line in FIG. The second portion 77b is joined to the second group 57-2, while the first portions 77a and 77a are joined to at least the third group 57-3 and the fourth group 57-4 (in addition to the fifth group 57-2). Group 57-5 may also be joined).

  The flexible flat cable 40 has a conventionally known configuration, that is, the lead having the fine width made of a conductor such as copper foil made of an electrically insulating synthetic resin material having flexibility and durability against bending deformation. Covering the wire, only the corresponding portion of the common joint electrode portion 77 and the individual joint electrode portion 78 are opened on one side of the square surface of the flexible flat cable 40, and bumps are formed in the openings. When the bump is made of solder, the bump is superimposed on the common surface electrode 57 and the individual surface electrode 58 and bonded by heating and pressing. If the bump material such as anisotropic conductive resin is of a type that is conductive by pressure, simple pressure bonding may be used.

  As described above, in the present invention, the common surface electrode 57 and the individual surface electrode 58 are arranged symmetrically with respect to the center point O of the wide surface of the surface sheet as the center of symmetry. Bonding electrode portions formed on the wide surface of the cable 40 are respectively connected to the large number of common surface electrodes 77 and individual surface electrodes 78 when the flexible flat cable is rotated 180 degrees around the symmetry center O. Since they are arranged so that they can be electrically joined, the operation of reversing the flexible flat cable 40 by rotating the drawing direction by 180 degrees can be very easily performed using the same head unit 6. In that case, only the 2nd part 77b and the 1st group 57-1 (2nd group 57-2) along the free end edge (1st direction (Y direction)) in the flexible flat cable 40 are joined, and a flexible flat cable is used. The flexible flat cable 40 is not joined to the common surface electrode 77 on the side far from the free end edge 40 in the second direction (X direction) (that is, in the longitudinal direction of the flexible flat cable 40). Even if it expands and contracts in the (X direction) due to a temperature change or the like, the bonding at the second portion 77b is maintained. Further, when the middle portion in the longitudinal direction of the flexible flat cable 40 is bent and pulled out from the slit 87 (see FIGS. 2 and 3) of the head holder 1, the bending can be smoothly performed.

  Further, the first portions 77a and 77a of the common junction electrode portion 77 and the fourth group 57-4 and the fifth group 57-5 of the common surface electrode 57 are both in the second direction (X direction). Since it is formed long, even if the flexible flat cable 40 expands and contracts in the X direction due to a temperature change or the like, it is possible to improve reliability that does not occur due to peeling of the joint.

  Furthermore, since the first portions 77a and 77a are formed within the width dimension (Y-direction dimension) of the flexible flat cable 40, the flexible flat cable 40 and thus the head unit 6 can be made compact.

  Moreover, since the third group 57-3 is arranged so as to enter the inner side (center part) of the top sheet 35 in the first direction between the rows of the island-shaped individual surface electrodes 58, The wide surface of the top sheet 35 can be used effectively.

  When the width direction of the flexible flat cable 40 to be joined to the piezoelectric actuator 12 is made parallel to the longitudinal direction (first direction) of the top sheet 35 and then the piezoelectric actuator 12, a large number of individual electrodes are arranged in the longitudinal direction. Therefore, an area margin for arranging the individual electrode bonding electrode portion 78 and the lead wire thereof is increased, and the degree of freedom in design is improved.

  In the embodiment, the number of nozzle rows is four, but the present invention can be applied to one or more nozzle rows. Needless to say, the present invention can be applied to the joining of a single piezoelectric actuator and a single flexible flat cable.

1 is a perspective view of an inkjet printer head to which the present invention is applied. It is the top view seen from the back side of a printer head. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. 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. (A) is the VI-VI line arrow expanded sectional view of FIG. 4, (b) is an enlarged plan view of an aperture | diaphragm | squeeze part. FIG. 7 is an enlarged sectional view taken along line VII-VII in FIG. 4. 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 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 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. 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. It is a partially expanded plan view which shows the overlapping state of a top sheet and a flexible flat cable.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet printer head 11 Cavity unit 12 Piezoelectric actuator 22 Base plate 23 Pressure chamber 24 Nozzle 33, 34 Piezo sheet 35 Top sheet 36 Individual electrode 37 Common electrode 40 Flat cable 57 Common surface electrode 58 Individual surface electrode 77 Common joint electrode part 77a 1st part 77b 2nd part 78 Individual joining electrode part

Claims (4)

A cavity unit in which a plurality of nozzle rows composed of a plurality of nozzles arranged in a row along the first direction and a plurality of rows of pressure chambers corresponding to the respective nozzles are formed in each cavity. A laminated type piezoelectric actuator for ejecting ink having an active part that can be selectively driven is joined to the wide surface of the flexible flat cable with respect to the surface electrode formed on the wide surface of the piezoelectric actuator. In the ink jet printer head formed by joining the joined electrode portions,
The piezoelectric actuator is formed by laminating a plurality of sheets including a piezoelectric sheet,
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 is configured to be the active portion corresponding to each pressure chamber,
A large number of individual surface electrodes that are electrically connected to the individual electrodes and a large number of common surface electrodes that are electrically connected to the common electrodes are formed in an island shape on the wide surface of the surface sheet of the piezoelectric actuator. The common surface electrode and the individual surface electrode are arranged in a point-symmetrical manner with the center point of the wide surface of the surface sheet as the center of symmetry, and are formed on the wide surface of the flexible flat cable. Is arranged so that the flexible flat cable can be electrically joined to the common surface electrodes and the individual surface electrodes, respectively, when the flexible flat cable is rotated 180 degrees about the symmetry center. Inkjet printer head. The common surface electrodes are arranged near the outer periphery of the wide surface of the surface sheet, and are arranged and divided into a plurality of groups at appropriate intervals in the first direction and the second direction perpendicular thereto.
2. The ink jet printer head according to claim 1, wherein the individual surface electrode is formed at an inner peripheral portion of the wide surface of the surface sheet.   3. The inkjet printer head according to claim 1, wherein the flexible flat cable is configured to be capable of being joined by being rotated by 180 degrees along a second direction orthogonal to the first direction. 4. . The common joint electrode portion formed on the flexible flat cable and joined to the common surface electrode is connected to the pair of side edges along the second direction in the flexible flat cable, and to the first Formed in a band shape with the free edge in the direction,
The inkjet printer head according to claim 1, wherein the individual joining electrode is formed in a region surrounded by the common joining electrode portion.

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