JP2014104646A - Liquid discharge head and recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head capable of reducing crosstalk.SOLUTION: The liquid discharge head includes: a flow path member having multiple discharge ports, multiple compression chambers 10, and a manifold; and a piezoelectric actuator substrate. The manifold includes: a partition wall; and multiple sub manifolds. The piezoelectric actuator substrate has: first areas R1 located on the partition wall; and second areas R2 located on the sub manifolds. A second electrode has: a second electrode body 25a located over the compression chamber 10; and a pulled out electrode 25b pulled out from the second electrode body 25a. Each of a pair of the second electrodes provided on the second area R2 has a first notch part 27, and the first notch parts 27 of the pair of the second electrodes face each other.

Description

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

  In recent years, printing apparatuses using an inkjet recording method, such as an inkjet printer or an inkjet plotter, are not only printers for general consumers, but also, for example, formation of electronic circuits, manufacture of color filters for liquid crystal displays, or organic EL displays. It is also widely used for industrial applications such as manufacturing.

  The conventional printing apparatus includes a liquid ejection head, a transport unit that transports a recording medium to the liquid ejection head, and a control unit that controls the liquid ejection head, and printing is performed by driving the liquid ejection head. It has been broken.

  The liquid discharge head covers a plurality of pressure chambers, a flow path member having a plurality of discharge holes, a plurality of pressure chambers communicating with the plurality of discharge holes, and a manifold communicating with the plurality of pressure chambers. And a piezoelectric actuator substrate laminated on the flow path member. The manifold has a partition and a plurality of submanifolds partitioned by the partition. The piezoelectric actuator substrate has a first electrode, a piezoelectric layer, and a plurality of second electrodes laminated in this order from the flow path member side (see, for example, FIG. 6 of Patent Document 1). Then, the liquid ejection head displaces the piezoelectric layer corresponding to the pressurizing chamber of the piezoelectric actuator substrate, thereby ejecting ink from each ejection hole and printing on the recording medium.

JP 2005-59430 A

  In the ink jet head as described above, a piezoelectric layer corresponding to an adjacent pressurizing chamber is caused by displacing the piezoelectric layer corresponding to a certain pressurizing chamber as the pressurizing chambers are arranged with high density. The so-called crosstalk causes the possibility that the ink is discharged from an ejection hole that should not eject ink, or that the ink ejection amount may increase or decrease from the original ejection amount. It can happen.

  The liquid discharge head of the present invention includes a flow path member having a plurality of discharge holes, a plurality of pressurization chambers communicating with the plurality of discharge holes, and a manifold communicating with the plurality of pressurization chambers, And a piezoelectric actuator substrate laminated on the flow path member so as to cover the pressure chamber. The manifold includes a partition wall and a plurality of submanifolds partitioned by the partition wall. In the piezoelectric actuator substrate, the first electrode, the piezoelectric layer, and the plurality of second electrodes are stacked in this order from the flow path member side, and the first region and the sub-portions are located on the partition wall. A second region located on the manifold is provided. The second electrode includes a second electrode main body positioned above the pressurizing chamber, and a lead electrode drawn from the second electrode main body, and a pair provided on the second region. Each of the second electrodes has a first notch, and the first notches of the pair of second electrodes face each other.

The recording apparatus of the present invention includes the liquid discharge head described above, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the liquid discharge head.

  According to the present invention, the possibility of crosstalk can be reduced.

1 is a schematic configuration diagram of an ink jet printer that is a recording apparatus including a liquid ejection head according to an embodiment of the present invention. FIG. 2 is a plan view of a flow path member and a piezoelectric actuator constituting the liquid ejection head of FIG. 1. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2, and is an enlarged plan view in which some flow paths are omitted for explanation. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2, and is an enlarged plan view in which some flow paths are omitted for explanation. It is a longitudinal cross-sectional view along the II line | wire of FIG. FIG. 6 is an enlarged plan view of the liquid ejection head shown in FIGS. (A) is an enlarged plan view of a pressurizing chamber and individual electrodes constituting the liquid ejection head shown in FIG. 6, and (b) is an enlarged plan view showing a modification of (a). (A) is an enlarged plan view of a pressurizing chamber and individual electrodes constituting a liquid ejection head according to another embodiment, and (b) is an enlarged plan view showing a modification of (a). FIG. 7 is an enlarged plan view corresponding to FIG. 6 of a liquid ejection head according to still another embodiment. (A) is an enlarged plan view of a pressurizing chamber and individual electrodes constituting a liquid ejection head according to another embodiment, and (b) is an enlarged plan view showing a modification of (a). FIG. 7 is an enlarged plan view corresponding to FIG. 6 of a liquid ejection head according to still another embodiment.

  FIG. 1 is a schematic configuration diagram of a color inkjet printer (hereinafter referred to as printer 1) which is a recording apparatus including a liquid discharge head according to an embodiment of the present invention. The ink jet printer 1 has four liquid discharge heads 2. These liquid discharge heads 2 are arranged along the conveyance direction of the printing paper P, and the liquid discharge head 2 has a long and narrow shape in a direction from the front to the back of FIG. This long direction is sometimes called the longitudinal direction.

  In the printer 1, a paper feeding unit 114, a transport unit 120, and a paper receiving unit 116 are sequentially provided along the transport path of the printing paper P. In addition, the printer 1 is provided with a control unit 100 for controlling the operation of each unit of the printer 1 such as the liquid discharge head 2 or the paper feeding unit 114.

  The paper supply unit 114 includes a paper storage case 115 that can store a plurality of printing papers P, and a paper supply roller 145. The paper feed roller 145 feeds the uppermost print paper P among the print papers P stacked and stored in the paper storage case 115 one by one.

  Two pairs of feed rollers 118 a, 118 b, 119 a, and 119 b are arranged between the paper feed unit 114 and the transport unit 120 along the transport path of the printing paper P. The printing paper P sent out from the paper supply unit 114 is guided by these feed rollers 118 a, 118 b, 119 a, and 119 b and further sent out to the transport unit 120.

The transport unit 120 includes a transport belt 111 and two belt rollers 106 and 107. The conveyor belt 111 is wound around belt rollers 106 and 107. The conveyor belt 111 is adjusted to such a length that it is stretched with a predetermined tension when it is wound around the two belt rollers 106 and 107. Thus, the conveyor belt 111 is stretched without loosening along two parallel planes including the common tangent lines of the two belt rollers 106 and 107, respectively. Of these two planes, a plane close to the liquid ejection head 2 is a conveyance surface 127 that conveys the printing paper P.

  The belt roller 106 is connected to a conveyance motor 174 as shown in FIG. The conveyance motor 174 rotates the belt roller 106 in the direction of arrow A. Further, the belt roller 107 rotates in conjunction with the transport belt 111. Therefore, the conveyor belt 111 moves along the direction of arrow A by driving the conveyor motor 174 to rotate the belt rollers 106 and 107.

  In the vicinity of the belt roller 107, a nip roller 138 and a nip receiving roller 139 are arranged so as to sandwich the conveyance belt 111. The nip roller 138 is urged downward by a spring (not shown). A nip receiving roller 139 below the nip roller 138 receives the nip roller 138 biased downward via the conveying belt 111. The nip roller 138 and the nip receiving roller 139 are rotatably installed and rotate in conjunction with the transport belt 111.

  The printing paper P sent out from the paper supply unit 114 to the transport unit 120 is sandwiched between the nip roller 138 and the transport belt 111. As a result, the printing paper P is pressed against the transport surface 127 of the transport belt 111 and is fixed on the transport surface 127. The printing paper P is transported in the direction in which the liquid ejection head 2 is installed according to the rotation of the transport belt 111. The outer peripheral surface 113 of the conveyor belt 111 may be treated with adhesive silicon rubber. Thereby, the printing paper P can be securely fixed to the transport surface 127.

  The liquid discharge head 2 has a head body 2a at the lower end. The lower surface of the head body 2a is a discharge hole surface provided with a number of discharge holes 8 (see FIG. 4) for discharging liquid.

  A liquid (ink) of the same color is discharged from the discharge hole 8 provided in one liquid discharge head 2. Each liquid discharge head 2 is supplied with liquid from an external liquid tank (not shown). Since the ejection holes 8 of each liquid ejection head 2 are opened in the ejection hole surface and are arranged at equal intervals in the longitudinal direction, printing can be performed without gaps in the longitudinal direction. The colors of the liquid ejected from each liquid ejection head 2 are, for example, magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid discharge head 2 is arranged with a slight gap between the lower surface of the liquid discharge head main body 13 and the transport surface 127 of the transport belt 111.

  The printing paper P transported by the transport belt 111 passes through the gap between the liquid ejection head 2 and the transport belt 111. At that time, liquid is ejected from the head main body 2 a constituting the liquid ejection head 2 toward the upper surface of the printing paper P. As a result, a color image based on the image data stored by the control unit 100 is formed on the upper surface of the printing paper P.

A separation plate 140 and two pairs of feed rollers 121a, 121b, 122a, and 122b are disposed between the transport unit 120 and the paper receiver 116. The printing paper P on which the color image is printed is conveyed to the peeling plate 140 by the conveying belt 111. At this time, the printing paper P is peeled from the transport surface 127 by the right end of the peeling plate 140. Then, the printing paper P is sent to the paper receiving portion 116 by the feed rollers 121a, 121b, 122a, 122b. In this way, the printed printing paper P is sequentially supplied to the paper receiving unit 11.
6 and is stacked on the paper receiver 116.

  Note that a paper surface sensor 133 is installed between the liquid ejection head 2 and the nip roller 138 that are the most upstream in the transport direction of the printing paper P. The paper surface sensor 133 includes a light emitting element (not shown) and a light receiving element (not shown), and can detect the position of the leading edge of the printing paper P on the transport path. The detection result by the paper surface sensor 133 is sent to the control unit 100. The control unit 100 controls the liquid ejection head 2 or the conveyance motor 174 so that the conveyance of the printing paper P and the image printing are synchronized with each other based on the detection result sent from the paper surface sensor 133.

  Next, the liquid discharge head 2 will be described. FIG. 2 is a plan view of the head main body 2a. FIG. 3 is an enlarged view of a region surrounded by a one-dot chain line in FIG. FIG. 4 is an enlarged view of a region surrounded by a one-dot chain line in FIG. 2, and is a diagram in which a part of the flow paths different from FIG. In FIGS. 3 and 4, for easy understanding of the drawings, the aperture 6, the discharge hole 8, the pressurizing chamber 10, and the like that should be drawn by broken lines below the piezoelectric actuator substrate 21 are drawn by solid lines. FIG. 5 is a longitudinal sectional view taken along the line II of FIG. FIG. 6 is an enlarged plan view of the head main body 2a shown in FIGS. 2 to 5 and shows the relationship between the pressurizing chamber 10, the individual electrode 25 as the second electrode, and the connection electrode 26. FIG. Further, the discharge hole 8 in FIG. 4 is drawn larger than the actual diameter for easy understanding of the position.

  The liquid discharge head 2 includes a reservoir and a metal casing in addition to the head body 2a. Also. The head body 2a includes a flow path member 4 and a piezoelectric actuator substrate 21 on which a displacement element 30 (see FIG. 5) is formed.

  The flow path member 4 constituting the head body 2 a includes a manifold 5, a plurality of pressurizing chambers 10 connected to the manifold 5, and a plurality of discharge holes 8 respectively connected to the plurality of pressurizing chambers 10. Yes. The pressurizing chamber 10 opens to the upper surface of the flow path member 4, and the upper surface of the flow path member 4 is the pressurizing chamber surface. An opening 5a connected to the manifold 5 is provided on the upper surface of the flow path member 4, and liquid is supplied from the opening 5a.

  A piezoelectric actuator substrate 21 including a displacement element 30 is bonded to the upper surface of the flow path member 4, and each displacement element 30 is provided so as to be positioned on the pressurizing chamber 10. The piezoelectric actuator substrate 21 is connected to a signal transmission unit 92 such as an FPC (Flexible Printed Circuit) which is a wiring substrate for supplying a signal to each displacement element 30. In FIG. 2, the outline of the vicinity of the signal transmission unit 92 connected to the piezoelectric actuator substrate 21 is indicated by a dotted line so that the state where the two signal transmission units 92 are connected to the piezoelectric actuator substrate 21 can be seen.

  Since the signal transmission unit 92 is disposed along the piezoelectric actuator substrate 21 and the connection between the signal transmission unit 92 and the piezoelectric actuator substrate 21 is performed at a portion other than the pressurizing chamber 10, the signal transmission unit 92 is The displacement of the displacement element 30 is not suppressed. A large number of wires (not shown) are arranged along the short direction of the head main body 2a in the region of the signal transmission portion 92 facing the piezoelectric actuator substrate 21, and are shown on the left and right of FIG. It is connected to the part which is not.

The signal sent from the control unit 100 passes through another circuit board or the like as necessary, is transmitted to the signal transmission unit 92, and is supplied to the displacement element 30. The piezoelectric actuator substrate 21 side of the wiring of the signal transmission unit 92 is an electrode electrically connected to the piezoelectric actuator substrate 21, and the electrode is arranged in a rectangular shape at the end of the signal transmission unit 92. Yes. The two signal transmission portions 92 are connected so that their ends come to the center portion in the short direction of the piezoelectric actuator substrate 21. The two signal transmission portions 92 extend from the central portion toward the long side of the piezoelectric actuator substrate 21.

  The signal transmission unit 92 is mounted with a driver IC (not shown). The driver IC is mounted so as to be pressed against the metal casing, and the heat of the driver IC is transmitted to the metal casing and radiated to the outside. A drive signal for driving the displacement element 30 on the piezoelectric actuator substrate 21 is generated in the driver IC. A signal for controlling the generation of the drive signal is generated by the control unit 100 and input from the end of the signal transmission unit 92 opposite to the side connected to the piezoelectric actuator substrate 21. A circuit board or the like is provided in the liquid ejection head 2 between the control unit 100 and the signal transmission unit 92 as necessary.

  The head body 2 a has one flat channel member 4 and one piezoelectric actuator substrate 21. The planar shape of the piezoelectric actuator substrate 21 is rectangular, and is arranged on the upper surface of the flow path member 4 so that the long side of the rectangle is along the longitudinal direction of the flow path member 4.

  As shown in FIG. 2, two manifolds 5 are formed inside the flow path member 4. The manifold 5 has an elongated shape extending from one end side in the longitudinal direction of the flow path member 4 to the other end side, and the opening of the manifold 5 that opens to the upper surface of the flow path member 4 at both ends thereof. 5a is formed. By supplying the liquid from the opening 5 a of the manifold 5 to the flow path member 4, it is possible to prevent the liquid from being insufficiently supplied. In addition, since the difference in pressure loss that occurs when the liquid flows through the manifold 5 can be reduced by about half compared with the case where the liquid is supplied from one end of the manifold 5, the discharge amount of the liquid discharged from the plurality of discharge holes 8 and Variations in discharge speed (hereinafter sometimes referred to as discharge characteristics) can be reduced.

  In the manifold 5, at least a central portion in the length direction, which is a region connected to the pressurizing chamber 10, is partitioned by a partition wall 15 provided at an interval in the width direction. The partition wall 15 has the same height as the manifold 5 in the central portion in the length direction, which is a region connected to the pressurizing chamber 10, and partitions the manifold 5 into a plurality of sub-manifolds 5b. Therefore, the flow path member 4 is provided in the area where the partition wall 15 is provided, and a space is provided in the area where the sub-manifold 5b is formed so that liquid is supplied. By doing so, it is possible to provide a discharge hole 8 and a descender (not shown) serving as an individual flow path connected from the discharge hole 8 to the pressurizing chamber 10 so as to overlap the partition wall 15 when viewed in plan.

  As shown in FIG. 2, the whole of the manifold 5 excluding both ends is partitioned by a partition wall 15. In addition to this, one of the both end portions other than one end portion may be partitioned by the partition wall 15. Further, only the vicinity of the opening 5 a on the upper surface of the flow path member 4 is not partitioned, and the partition wall 15 may be provided between the opening 5 a and the depth direction of the flow path member 4. In any case, it is preferable that both ends of the manifold 5 are not partitioned by the partition wall 15 because the flow resistance is reduced and the supply amount of the liquid can be increased because there is a portion that is not partitioned.

  In the present embodiment, two manifolds 5 are provided independently, and openings 5a are provided at both ends. One manifold 5 is provided with seven partition walls 15, and one manifold 5 is divided into eight sub-manifolds 5b. The width of the sub-manifold 5b is larger than the width of the partition wall 15, so that a large amount of liquid can flow through the sub-manifold 5b. Further, the length of the seven partition walls 15 becomes longer as they are closer to the center in the short direction (row direction L2), and the partition walls 15 that are closer to the center in the short direction at both ends of the manifold 5 The end is close to the end of the manifold 5.

Thereby, the channel resistance generated by the outer wall of the manifold 5 and the channel resistance generated by the partition wall 15 can be made closer to each other, and the individual supply channel 14 connected to the pressurizing chamber 10 in each sub-manifold 5b. The pressure difference of the liquid at the end of the region where (see FIG. 5) is formed can be reduced. Since the pressure difference in the individual supply flow path 14 affects the pressure difference applied to the liquid in the pressurizing chamber 10, the pressure difference in the individual supply flow path 14 is reduced to be discharged from the plurality of discharge holes 8. Variations in the discharge characteristics of the liquid can be reduced.

  The flow path member 4 is formed by two-dimensionally expanding a plurality of pressurizing chambers 10. As shown in FIG. 3, the pressurizing chamber 10 is connected to one sub-manifold 5 b via the individual supply channel 14. Along with one sub-manifold 5b, two rows of pressurizing chambers 11a, which are rows of pressurizing chambers 10 connected to the sub-manifold 5b, are provided on each side of the sub-manifold 5b. . Accordingly, 16 pressurizing chamber columns 11a are provided for one manifold 5, and 32 pressurizing chamber columns 11a are provided in the entire head body 2a. The interval in the longitudinal direction of the pressurizing chamber 10 in each pressurizing chamber row 11a is the same, for example, 37.5 dpi. The intervals between the pressurizing chambers 10 in the column direction L1 and the row direction L2 are preferably equal intervals, but the intervals may be different by about ± 20%. The sub-manifold 5b may be completely partitioned into one tube. In that case, the manifold 5 is composed of one sub-manifold 5b and a partition wall 15.

  A dummy pressurizing chamber 16 is provided outside the pressurizing chamber column 11a in the row direction L2, and the dummy pressurizing chamber 16 forms a dummy pressurizing chamber column 16a linearly arranged in the column direction L1. Yes. In the dummy pressurizing chamber row 16a, dummy electrodes (not shown) that are not electrically connected to an external power source are respectively formed on the upper side and are connected to the manifold 5 but not to the discharge holes 8. Not.

  A dummy pressurizing chamber 16 is also provided outside the column direction L1 of the 32 pressurizing chamber columns 11a, and the dummy pressurizing chamber rows are arranged in a straight line in the row direction L2. 16b is provided. In the dummy pressurizing chamber row 16b, dummy electrodes are respectively formed above and are not connected to either the manifold 5 or the discharge hole 8. Because of the dummy pressurizing chamber 16, the rigidity around the pressurizing chamber 10 that is one inner side from the end is close to the rigidity of the pressurizing chamber 10 provided in another region. It is possible to reduce the difference in dispersion of the liquid ejection characteristics. An individual electrode 25 is formed on the dummy pressurizing chamber 16.

  The pressurizing chambers 10 connected to one manifold 5 are provided along the column direction L1 which is the longitudinal direction of the liquid discharge head 2, and are arranged at substantially equal intervals in the column direction L1 and the row direction L2, respectively. Yes. 2 to 4, the column direction L1 is a direction in which the partition wall 15 of the manifold 5 extends, and the row direction L2 is a direction orthogonal to the column direction L1. As shown in FIG. 6, the pressurizing chamber 10 has a substantially rhombus shape in plan view, and is rounded at corners. This is a hollow region having a substantially rhombic planar shape having two acute angle portions 10a and two acute angle portions 10b. The rhombus shape of the pressurizing chamber 10 may have a side length of each pressurizing chamber 10 different by about 10%.

  When the pressurizing chambers 10 are arranged in a grid pattern and the piezoelectric actuator substrate 21 is formed in a rectangular shape having outer sides along rows and columns, the piezoelectric actuator substrate 21 is formed on the pressurizing chamber 10 from the outer sides. Since the individual electrodes 25 are arranged at equal distances, the possibility that the piezoelectric actuator substrate 21 is deformed when the individual electrodes 25 are formed can be reduced.

When the piezoelectric actuator substrate 21 and the flow path member 4 are joined, if the deformation is large, stress is applied to the displacement element 30 near the outer side and the displacement characteristics may vary, but by reducing the deformation, The variation can be reduced. The pressurizing chambers 10 belonging to the pressurizing chamber row 11a are arranged at equal intervals in the column direction L1, and the individual electrodes 25 corresponding to the pressurizing chamber row 11a are also arranged at equal intervals in the column direction L1. The pressurizing chamber columns 11a are arranged at equal intervals in the row direction L2, and the columns of the individual electrodes 25 corresponding to the pressurizing chamber columns 11a are also arranged at equal intervals in the row direction L2. Thereby, it is possible to eliminate a portion where the influence of the crosstalk becomes particularly large.

  When the flow path member 4 is viewed in plan, the pressurizing chamber 10 belonging to one pressurizing chamber row 11a is arranged so as not to overlap with the pressurizing chamber 10 belonging to the adjacent pressurizing chamber row 11a in the row direction L1. By doing so, crosstalk can be suppressed. On the other hand, when the distance between the row directions L2 of the pressurizing chamber column 11a is increased, the width of the liquid discharge head 2 is increased. Therefore, the accuracy of the installation angle of the liquid discharge head 2 with respect to the printer 1 and the plurality of liquid discharge heads are increased. The influence of the accuracy of the relative position of the liquid ejection head 2 on the printing result when using 2 is increased. Therefore, by making the width of the partition wall 15 smaller than that of the sub-manifold 5b, the influence of the accuracy on the printing result can be reduced.

  The pressurizing chambers 10 connected to one sub-manifold 5b constitute two rows of pressurizing chambers 11a, and the discharge holes 8 connected from the pressurizing chambers 10 constituting one pressurizing chamber row 11a. Constitutes one discharge hole array 9. The discharge holes 8 connected to the pressurizing chambers 10 constituting the two pressurizing chamber rows 11a open to different sides of the sub-manifold 5b.

  As shown in FIG. 4, the partition wall 15 is provided with two rows of discharge hole arrays 9. The discharge holes 8 belonging to each of the discharge hole arrays 9 are connected to the sub-manifold 5 b near the discharge holes 8. They are connected via the pressure chamber 10. If the discharge hole 8 connected to the adjacent sub-manifold 5b via the pressurizing chamber row 11a and the liquid discharge head 2 are arranged so as not to overlap in the longitudinal direction, the pressurizing chamber 10 and the discharge hole 8 are connected. Since crosstalk between connected flow paths can be suppressed, crosstalk can be further reduced. If the entire flow path connecting the pressurizing chamber 10 and the discharge hole 8 is arranged so as not to overlap in the longitudinal direction of the liquid discharge head 2, the crosstalk can be further reduced.

  Further, the width of the liquid discharge head 2 can be reduced by arranging the pressurizing chamber 10 and the sub-manifold 5b so as to overlap each other in plan view. By setting the ratio of the area overlapping the sub-manifold 5b to the area of the pressurizing chamber 10 to be 80% or more, and further 90% or more, the width of the liquid discharge head 2 can be further reduced. That is, the pressurizing chamber 10 is provided from the region corresponding to the first region R1 to the region corresponding to the second region R2 as shown in FIG. Here, the first region R1 is a region located on the partition wall 15 of the flow path member 4, and the second region R2 is a region located on the manifold 5 (sub-manifold 5b) of the flow path member 4. is there.

  The rigidity of the area corresponding to the second area R2 of the pressurizing chamber 10 is lower than the rigidity corresponding to the first area R1, and the liquid discharged from the plurality of discharge holes 8 due to the difference. There is a possibility that the discharge characteristics of the ink may vary. By making the ratio of the area of the region corresponding to the second region R2 with respect to the entire area of the pressurizing chamber 10 substantially the same in each pressurizing chamber 10, the liquid ejection due to the difference in rigidity constituting the pressurizing chamber 10 Variations in characteristics can be reduced. Here, “substantially the same” means that the difference in area ratio is 10% or less, particularly 5% or less. Note that the region corresponding to the first region R1 of the pressurizing chamber 10 is a region of the pressurizing chamber 10 located on the first region R1 of the piezoelectric actuator substrate 21, and is in the second region R2 of the pressurizing chamber 10. The corresponding region is a region of the pressurizing chamber 10 located on the second region R2 of the piezoelectric actuator substrate 21.

A plurality of pressurizing chambers (not shown) are constituted by a plurality of pressurizing chambers 10 connected to one manifold 5, and since two manifolds 5 are formed, two pressurizing chamber groups are formed. ing. The arrangement of the pressurizing chambers 10 related to the discharge in each pressurizing chamber group is the same, and is arranged to be translated in the row direction L2. These pressurizing chambers 10 are arranged over substantially the entire surface in a region facing the piezoelectric actuator substrate 21 on the upper surface of the flow path member 4. In other words, the pressurizing chamber group formed by these pressurizing chambers 10 occupies a region having substantially the same size and shape as the piezoelectric actuator substrate 21. Further, the opening of each pressurizing chamber 10 is closed by bonding the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  A descender (individual flow channel 12) connected to the discharge hole 8 opened in the discharge hole surface on the lower surface of the flow channel member 4 from a corner portion opposed to the corner portion to which the individual supply flow channel 14 of the pressurizing chamber 10 is connected. ) Is growing. The descender extends in a direction away from the pressurizing chamber 10 in plan view. More specifically, the pressurizing chamber 10 extends away from the direction along the long diagonal line while being shifted to the left and right with respect to that direction. As a result, the discharge chambers 8 can be arranged at intervals of 1200 dpi as a whole, while the pressurization chambers 10 are arranged in a lattice pattern in which the intervals within the pressurization chamber rows 11 are 37.5 dpi. 11 indicates a third region R3, which is a region of the piezoelectric actuator substrate 21 located above the individual flow path 12 of the flow path member 4.

  In other words, when the discharge holes 8 are projected so as to be orthogonal to the virtual straight line parallel to the longitudinal direction of the flow path member 4, each manifold 5 is within the range of S of the virtual straight line shown in FIG. A total of 32 discharge holes 8 connected to each other are arranged at equal intervals of 1200 dpi. Thus, by supplying the same color ink to all the manifolds 5, an image can be formed with a resolution of 1200 dpi in the longitudinal direction as a whole. One discharge hole 8 connected to one manifold 5 is arranged at equal intervals of 600 dpi within the range of S of the imaginary straight line. As a result, by supplying different colors of ink to the respective manifolds 5, it is possible to form two-color images with a resolution of 600 dpi in the longitudinal direction as a whole. In this case, if two liquid ejection heads 2 are used, an image of four colors can be formed with a resolution of 600 dpi, the printing accuracy of the liquid ejection head 2 can be increased, and the liquid ejection head 2 can be easily set. can do.

  As shown in FIG. 5, the flow path member 4 included in the head body 2a has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 4a, a base plate 4b, an aperture plate 4c, a supply plate 4d, manifold plates 4e to j, a cover plate 4k, and a nozzle plate 4l in order from the upper surface of the flow path member 4. A number of holes are formed in these plates. Since the thickness of each plate is about 10 to 300 μm, the formation accuracy of the holes to be formed can be increased. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 12 and the manifold 5. In the head main body 2a, the pressurizing chamber 10 is on the upper surface of the flow path member 4, the manifold 5 is on the inner lower surface side, the discharge holes 8 are on the lower surface, and the parts constituting the individual flow path 12 are close to each other in different positions. The manifold 5 and the discharge hole 8 are connected via the pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. The first is a hole that becomes the pressurizing chamber 10 formed in the cavity plate 4a. Second, there is a communication hole that constitutes an individual supply channel 14 that is connected from one end of the pressurizing chamber 10 to the manifold 5. This communication hole is formed in each plate from the base plate 4b (specifically, the inlet of the pressurizing chamber 10) to the supply plate 4c (specifically, the outlet of the manifold 5). The individual supply flow path 14 includes a squeeze 6 that is formed in the aperture plate 4c and is a portion where the cross-sectional area of the flow path is small.

Third, there is a communication hole constituting a flow path communicating from the other end of the pressurizing chamber 10 to the discharge hole 8, and this communication hole is referred to as a descender (partial flow path) in the following description. The descender is
It is formed on each plate from the base plate 4b (specifically, the outlet of the pressurizing chamber 10) to the nozzle plate 4l (specifically, the discharge hole 8). The hole of the nozzle plate 41 is opened as a discharge hole 8 having a diameter of 10 to 40 μm, for example, which is open to the outside of the flow path member 4, and the diameter increases toward the inside. .

  Fourthly, communication holes constituting the manifold 5. The communication holes are formed in the manifold plates 4e to 4j. Holes are formed in the manifold plates 4e to 4j so that the partition walls 15 remain so as to constitute the sub-manifold 5b. The partition 15 in each manifold plate 4e-j cannot be held when the entire portion to be the manifold 5 is made a hole, so the partition 15 is connected to the outer periphery of each manifold plate 4e-j with a half-etched tab. To be.

  The first to fourth communication holes are connected to each other to form an individual flow path 12 from the liquid inflow port (outlet of the manifold 5) to the discharge hole 8 from the manifold 5. The liquid supplied to the manifold 5 is discharged from the discharge hole 8 through the following path. First, from the manifold 5, it enters the individual supply flow path 14 and reaches one end of the throttle 6. Next, it proceeds horizontally along the extending direction of the restriction 6 and reaches the other end of the restriction 6. From there, it reaches one end of the pressurizing chamber 10 upward. Furthermore, it progresses horizontally along the extending direction of the pressurizing chamber 10 and reaches the other end of the pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the discharge hole 8 opened in the lower surface.

  Since the manifold 5 is divided into a plurality of sub-manifolds 5b by the partition wall 15, the rigidity of the flow path member 4 is different between the region where the partition wall 15 of the manifold 5 is provided and the region where the sub-manifold 5b is provided. It will be. More specifically, the rigidity in the region where the partition wall 15 is provided is higher than the rigidity of the region where the sub-manifold 5b is provided.

  Further, the liquid discharge head 2 may join a reservoir (not shown) to the flow path member 4 in order to stabilize the supply of the liquid from the opening 5 a of the manifold 5. The reservoir branches the liquid supplied from the outside and is provided with a reservoir flow path connected to the two openings 5a of the manifold 5, so that the liquid can be stably supplied to the two openings of the flow path member 4. it can. Further, by making the flow path lengths after branching substantially the same, the temperature fluctuation or pressure fluctuation of the liquid supplied from the outside is transmitted to the openings 5a at both ends of the manifold 5 with a small time difference. Variations in the liquid ejection characteristics can be reduced. By providing a damper (not shown) in the reservoir, the liquid supply can be further stabilized. Further, a filter may be provided so as to prevent foreign matters in the liquid from moving toward the flow path member 4. Furthermore, a heater may be provided so as to stabilize the temperature of the liquid toward the flow path member 4.

  In the piezoelectric actuator substrate 21, the common electrode 24, the piezoelectric ceramic layer 21 b, and the individual electrode 25 are laminated in this order from the flow path member 4. The piezoelectric actuator substrate 21 and the flow path member 4 are joined. The piezoelectric actuator substrate 21 includes a first region R1 positioned on the partition wall 15 of the manifold 5, a second region R2 positioned on the sub-manifold 5b of the manifold 5, and a third region R3 ( 11).

As shown in FIG. 6, the individual electrodes 25 are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. The individual electrode 25 is smaller than the pressurizing chamber 10 and includes an individual electrode main body 25a located on the pressurizing chamber 10 and an extraction electrode 25b extracted from the individual electrode main body 25a. One end of the extraction electrode 25b is connected to the individual electrode main body 25a, and the other end is extracted so as not to overlap with the region Q on the column constituting the pressurizing chamber row 11b. Details of the individual electrode 25 will be described later.

  As shown in FIG. 3, on the upper surface of the piezoelectric actuator substrate 21, there are formed the individual electrodes 25, the common electrode 24 as the first electrode, and the common electrode surface electrode 28 electrically connected via the via hole. ing. The common electrode surface electrodes 28 are formed in two rows along the column direction L1 in the center of the piezoelectric actuator substrate 21 in the row direction L2, and the two rows of common electrode surface electrodes 28 are alternately arranged. . One column is formed along the row direction L2 near the end in the column direction L1. Although the illustrated common electrode surface electrode 28 is intermittently formed on a straight line, it may be formed continuously on a straight line.

  When manufacturing the piezoelectric actuator substrate 21, if there is a variation in position between the individual electrode 25 and the pressurizing chamber 10, the ejection characteristics may be greatly affected. Further, when the individual electrode 25 is formed and then fired, the piezoelectric actuator substrate 21 may be warped. When the warped piezoelectric actuator substrate 21 is joined to the flow path member 4, stress is applied to the piezoelectric actuator substrate 21, and the displacement may vary due to the influence. Therefore, the piezoelectric actuator substrate 21 is formed by laminating and firing the piezoelectric ceramic layer 21a having the via holes, the common electrode 24, and the piezoelectric ceramic layer 21b, and then forming the individual electrode 25 and the common electrode surface electrode 28 in the same process. Is preferred.

  Further, if the common electrode surface electrode 28 is formed at the same time as the individual electrode 25, the positional accuracy becomes higher and the process can be simplified. Therefore, the individual electrode 25 and the common electrode surface electrode 28 are formed in the same process. It is preferable. As shown in FIG. 3, a dummy electrode row 16c composed of a plurality of dummy electrodes 16 provided in the column direction L1 is provided at the center of the piezoelectric actuator substrate 21 in the row direction L2. By providing the dummy electrode row 16c, the behavior of the central portion in the row direction L2 of the piezoelectric actuator substrate 21 at the time of firing the individual electrode 25 can be brought close to other regions, and deformation of the piezoelectric actuator substrate 21 can be reduced. can do.

  Such positional variations of via holes due to firing shrinkage that may occur when firing the piezoelectric actuator substrate 21 mainly occur in the column direction L1 of the piezoelectric actuator substrate 21, and thus there are an even number of common electrode surface electrodes 28. In other words, in the center of the manifold 5, it is provided at the center of the piezoelectric actuator substrate 21 in the row direction L 2, and the common electrode surface electrode 28 has a long shape in the longitudinal direction of the piezoelectric actuator substrate 21. Thus, it is possible to prevent the via hole and the common electrode surface electrode 28 from being electrically connected due to misalignment.

  Two signal transmission portions 92 are arranged and bonded to the piezoelectric actuator substrate 21 from the two long sides of the piezoelectric actuator substrate 21 toward the center. At that time, the connection electrode 26 and the common electrode connection electrode (not shown) are formed and connected on the extraction electrode 25b and the common electrode surface electrode 28 of the piezoelectric actuator substrate 21, respectively, so that the connection is facilitated. can do. At this time, if the area of the common electrode surface electrode 28 and the common electrode connection electrode is made larger than the area of the connection electrode 26, the end of the signal transmission unit 92 (the end of the piezoelectric actuator substrate 21 and the end in the longitudinal direction of the piezoelectric actuator substrate 21). ) Can be strengthened by the connection on the common electrode surface electrode 28, and therefore, it is possible to reduce the occurrence of peeling of the signal transmission portion 92 from the end.

Further, the discharge hole 8 is arranged at a position avoiding the area facing the manifold 5 arranged on the lower surface side of the flow path member 4. Further, the discharge hole 8 is disposed in a region facing the piezoelectric actuator substrate 21 on the lower surface side of the flow path member 4. These discharge holes 8 occupy a region having substantially the same size and shape as the piezoelectric actuator substrate 21 as one group, and the displacement elements 30 of the corresponding piezoelectric actuator substrate 21 are displaced from the discharge holes 8. Liquid can be discharged.

  The piezoelectric actuator substrate 21 has a laminated structure composed of two piezoelectric ceramic layers 21a and 21b which are piezoelectric layers. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The thickness from the lower surface of the piezoelectric ceramic layer 21a of the piezoelectric actuator substrate 21 to the upper surface of the piezoelectric ceramic layer 21b is about 40 μm. Both of the piezoelectric ceramic layers 21 a and 21 b extend so as to straddle the plurality of pressure chambers 10. These piezoelectric ceramic layers 21a and 21b are made of, for example, a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator substrate 21 includes a common electrode 24 made of a metal material such as Ag—Pd and an individual electrode 25 made of a metal material such as Au. The individual electrode 25 includes the individual electrode main body 25a disposed at the position facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21 as described above, and the extraction electrode 25b extracted from the individual electrode main body 25a. . A connection electrode 26 is formed at a portion of one end of the extraction electrode 25 b that is extracted outside the region facing the pressurizing chamber 10. The connection electrode 26 is made of, for example, silver-palladium containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 26 is electrically joined to an electrode provided in the signal transmission unit 92. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 25 through the signal transmission unit 92. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 24 is formed over substantially the entire surface in the region between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 24 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 21. The thickness of the common electrode 24 is about 2 μm. The common electrode 24 is connected to the common electrode surface electrode 28 via a via hole formed in the piezoelectric ceramic layer 21b, and is grounded and held at the ground potential. The common electrode surface electrode 28 is connected to another electrode on the signal transmission unit 92 in the same manner as the large number of individual electrodes 25.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 25, the piezoelectric ceramic layer 21b sandwiched between the individual electrode 25 and the common electrode 24 is displaced, and corresponds to the individual electrode 25. The volume of the pressurizing chamber 10 is changed, and pressure is applied to the liquid in the pressurizing chamber 10. Thereby, the liquid is discharged from the corresponding liquid discharge port 8 through the individual flow path 12. That is, the portion of the piezoelectric actuator substrate 21 that faces each pressurizing chamber 10 corresponds to the individual displacement element 30 corresponding to each pressurizing chamber 10 and the liquid discharge port 8.

  That is, in the laminated body composed of the two piezoelectric ceramic layers 21a and 21b, the displacement element 30 which is a piezoelectric actuator having a unit structure as shown in FIG. The piezoelectric ceramic layer 21a, the common electrode 24, the piezoelectric ceramic layer 21b, and the individual electrodes 25 are formed directly above the pressurizing chamber 10, and the piezoelectric actuator substrate 21 includes a plurality of displacement elements 30 that are pressurizing portions. ing. In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 1.5 to 4.5 pl (picoliter).

The large number of individual electrodes 25 are individually electrically connected to the control unit 100 via the signal transmission unit 92 and wiring so that the potential can be individually controlled. When an electric field is applied to the piezoelectric ceramic layer 21b in the polarization direction by setting the individual electrode 25 to a potential different from that of the common electrode 24, a portion to which the electric field is applied functions as an active portion that is distorted by the piezoelectric effect. In this configuration, when the control unit 100 sets the individual electrode 25 to a predetermined positive or negative potential with respect to the common electrode 24 so that the electric field and the polarization are in the same direction, a portion sandwiched between the electrodes of the piezoelectric ceramic layer 21b. (Active part) contracts in the surface direction. On the other hand, the piezoelectric ceramic layer 21a, which is an inactive layer, is not affected by an electric field, so that it does not spontaneously shrink and tries to restrict deformation of the active portion. As a result, there is a difference in strain in the polarization direction between the piezoelectric ceramic layer 21b and the piezoelectric ceramic layer 21a, and the piezoelectric ceramic layer 21b is deformed so as to protrude toward the pressurizing chamber 10 (unimorph deformation).

In an actual driving procedure in the present embodiment, the individual electrode 25 is set to a potential higher than the common electrode 24 (hereinafter referred to as a high potential) in advance, and the individual electrode 25 is temporarily set to the same potential as the common electrode 24 every time there is a discharge request. (Hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to the original shape at the timing when the individual electrode 25 becomes low potential, and the volume of the pressurizing chamber 10 increases compared to the initial state (the state where the potentials of both electrodes are different). To do. At this time, a negative pressure is applied to the pressurizing chamber 10 and the liquid is sucked into the pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 25 is set to a high potential again, the piezoelectric ceramic layers 21 a and 21 b are deformed so as to protrude toward the pressurizing chamber 10, and the pressure in the pressurizing chamber 10 is reduced by the volume reduction of the pressurizing chamber 10. The pressure is increased to a positive pressure, and the liquid is discharged. That is, in order to discharge the liquid, a drive signal including a pulse based on a high potential is supplied to the individual electrode 25. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the orifice 6 to the discharge hole 8. According to this, when the inside of the pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid can be discharged at a stronger pressure.

  In gradation printing, gradation expression is performed by the number of liquids ejected continuously from the ejection holes 8, that is, the amount of liquid adjusted by the number of liquid ejections. For this reason, the number of times of liquid ejection corresponding to the designated gradation expression is continuously performed from the ejection holes 8 corresponding to the designated dot area. In general, when liquid ejection is performed continuously, it is preferable that the interval between pulses supplied to eject the liquid be AL. As a result, the period of the residual pressure wave of the pressure generated when discharging the previously discharged liquid and the pressure wave of the pressure generated when discharging the liquid to be discharged later coincide, and these are superimposed. The pressure for discharging the liquid can be amplified.

  Hereinafter, the individual electrode 25 will be described in detail with reference to FIG.

  The individual electrode 25 includes an individual electrode body 25a and an extraction electrode 25b. The individual electrode body 25 a is provided on the pressurizing chamber 10 and includes one acute angle portion 25 a 1, two obtuse angle portions 25 a 2, and a first cutout portion 27. The individual electrode main body 25a has a single acute angle portion 25a1 and two obtuse angle portions 25a2 in plan view, one acute angle portion 10a of the pressurizing chamber 10 provided below, and two obtuse angle portions 10b. The individual electrode main body 25 a is accommodated in the pressurizing chamber 10. The individual electrode main body 25a includes a first cutout portion 27 on the opposite side of the single acute angle portion 25a1.

  Moreover, since the individual electrode 25 is provided on the pressurizing chamber 10, most of the individual electrode 25 is disposed on the second region R2. The second region R2 is sandwiched between the first regions R1 in the row direction L2, and the paired individual electrodes 25 are arranged in the row direction L2 in the sandwiched second region R2, as indicated by a chain line in FIG. Are provided adjacent to each other.

  The pair of individual electrodes 25 are arranged such that the first cutout portions 27 face each other. Therefore, a sufficient distance between the pair of individual electrodes 25 can be ensured, and the possibility of crosstalk occurring between the pair of individual electrodes 25 can be reduced.

  The individual electrode body 25a has a shape substantially similar to that of the pressurizing chamber 10 and includes one acute angle portion 25a1, two obtuse angle portions 25a2, and a first cutout portion 27. The possibility of crosstalk can be reduced while ensuring the function of deforming and pressurizing.

  The extraction electrodes 25b are alternately extracted to the upper side and the lower side shown in FIG. 6 in the column direction L1. Therefore, the individual electrode 25 provided on the pressurizing chamber 10 constituting the pressurizing chamber row 11b1 is provided on the pressurizing chamber 10 constituting the pressurizing chamber row 11b2 with the extraction electrode 25b drawn upward. In the individual electrode 25, the extraction electrode 25b is extracted downward.

  The individual electrode 25 will be described in detail with reference to FIG. In FIGS. 7A and 7B, the shape of the individual electrode body 25a having a shape substantially similar to that of the pressurizing chamber 10, in other words, the shape of the individual electrode body 25a when not cut away by the first notch 27 is shown by a broken line. Yes.

  As shown in FIG. 7A, a virtual individual electrode body 25a having a shape substantially similar to that of the pressurizing chamber 10 in a plan view is indicated by a broken line. The virtual individual electrode main body 25 a includes two acute angle portions 25 a 1 and two obtuse angle portions 25 a 2, and is entirely provided on the pressurizing chamber 10 and stored in a region above the pressurizing chamber 10. Has been. Thus, by making the individual electrode body 25a indicated by the broken line substantially similar to the pressurizing chamber 10, for example, the individual electrode body 25a contracts the piezoelectric ceramic layer 21b immediately below the individual electrode body 25a in the surface direction. In addition, since the piezoelectric ceramic layer 21b near the outer periphery of the pressurizing chamber 10 located outside the individual electrode body 25a does not contract, the displacement amount increases, and the pressurizing chamber 10 can be sufficiently pressurized, and a plurality of discharges can be performed. A sufficient amount of liquid can be discharged from the holes 8.

  In the individual electrode main body 25 a, one acute angle portion 25 a 1 of the individual electrode main body 25 a indicated by a broken line is cut out by the first cutout portion 27 in order not to cause crosstalk in the adjacent individual electrode 25. Therefore, the individual electrode main body 25 a has one acute angle portion 25 a 1, two obtuse angle portions 25 a 2, and the first cutout portion 27. Note that one acute angle portion 25a1 and two obtuse angle portions 25a2 of the individual electrode main body 25a are substantially similar to the pressurizing chamber 10. Note that the substantially similar shape to the pressurizing chamber 10 means that 85% or more of the outer shape of the individual electrode main body 25a matches when overlapped with a figure similar to the outer shape of the pressurizing chamber 10.

  The first cutout portion 27 is formed on the one acute angle portion 25a1 side of the individual electrode main body 25a, and the individual electrode main body 25a has a first side 29 along the column direction L1 formed by the first cutout portion 27. I have. Therefore, the individual electrode body 25a has one acute angle portion 25a1, two obtuse angle portions 25a2, and a first side 29 (one side constituting the first cutout portion 27).

  The first side 29 is preferably provided along the column direction L1. By providing the first side 29 along the column direction, which is the direction in which the partition walls 15 extend, the distance between the individual electrodes 25 facing each other can be maintained, and crosstalk can be reduced.

  Further, the distance from the center of gravity of the individual electrode body 25a to the first side 29 is preferably shorter than the distance from the center of gravity of the individual electrode body 25a to the other acute angle portion 25a1. Thereby, the pressurization amount of the pressurizing chamber 10 can be secured while reducing the possibility that the individual electrode main body 25a is provided on the first region R1.

The separation distance between the first side 29 and the acute angle portion 25a1 of the individual electrode main body 25a before being cut out is 0.1 to 0.2 times the straight line connecting the acute angle portions 25a1 of the individual electrode main body 25a. preferable. Further, the distance between the first side 29 of one individual electrode 25 and the first side 29 of the other individual electrode 25 is 4.0 times or more the distance connecting the acute angle portions 10a of the pressurizing chamber 10 to each other. The distance between the obtuse angle portions 10b of the pressure chamber 10 is preferably 3.0 times or more.

  The first side 29 is preferably parallel to the column direction L1, but may be inclined ± 20 ° from the partition wall 15 from the column direction L1. Even in that case, a predetermined distance between the individual electrodes 25 can be provided, and crosstalk can be reduced.

  A modification of the liquid ejection head 2 will be described with reference to FIG.

  In the individual electrode 25 ′ constituting the liquid ejection head 2 ′, the shape of the first side 29 ′ is different from the shape of the first side 29 of the individual electrode 25 constituting the liquid ejection head 2. The other points are the same and will not be described.

  The individual electrode 25 ′ includes an individual electrode body 25 a and an extraction electrode 25 b, and the individual electrode body 25 a includes one acute angle portion 25 a 1, two obtuse angle portions 25 a 2, and a first side 29. . The first side 29 ′ of one individual electrode 25 is provided along the column direction L 1 and has a convex shape in which the first side 29 ′ protrudes toward the other individual electrode 25 in plan view. I am doing. Therefore, the connection between the first side 29 'and the outer periphery of the other region of the individual electrode main body 25a becomes gentle. Thereby, it is possible to reduce the possibility that stress is generated at a site where the first side 29 'is connected to the outer periphery of another region of the individual electrode body 25a, and the possibility that the individual electrode body 25a is peeled off from this site. Can be reduced.

  In addition, the first side 29 ′ has an arc shape in plan view because the central portion in the column direction L1 protrudes toward the other individual electrode 25, and the first side 29 ′ is in the column direction of the first side 29 ′. The center portion of L1 is the most protruding configuration. For this reason, when the liquid discharge head 2 ′ is manufactured, even if the individual electrode 25 ′ is misaligned, the possibility of crosstalk can be reduced.

In addition, it is preferable that the curvature of 1st edge | side 29 'is smaller than the curvature of the acute angle part 25a1 of the individual electrode main body 25a. By making the curvature of the first side 29 'smaller than the curvature of the acute angle portion 25a1 of the individual electrode main body 25a, the possibility of crosstalk can be reduced. In addition, it is preferable that the curvature of 1st edge | side 29 'is 1.0 (1 / mm) or less, and it is preferable that the curvature of the acute angle part 25a1 of the individual electrode main body 25a is 10.0 (1 / mm) or more. .

  The individual electrodes 225 constituting the liquid ejection head 200 according to another embodiment will be described with reference to FIG. In the individual electrode 225, one side 231 constituting the extraction electrode 225b is formed continuously with the first side 229 of the individual electrode 225.

  Since one side 231 constituting the extraction electrode 225b is formed continuously with the first side 229 of the individual electrode 225, the one side 231 constituting the extraction electrode 225b, the first side 229 of the individual electrode 225, It is possible to reduce the stress generated at the joint location. Thereby, the possibility that the extraction electrode 225b is disconnected from the individual electrode body 225a can be reduced. In the individual electrode 225, the example in which the one side 231 constituting the extraction electrode 225b and the first side 229 of the individual electrode 225 are joined in a bent state is shown, but the individual electrode 225 is joined in a curved state. Also good. By joining in a curved state, the stress can be further reduced.

A modification of the liquid discharge head 200 will be described with reference to FIG. The individual electrode 225 ′ of the liquid ejection head 200 ′ has a first side 229 ′ provided in parallel with the column direction L1, and one side 231 ′ constituting the extraction electrode 225b is formed continuously with the first side 229 ′. Has been. Since one side 231 ′ constituting the extraction electrode 225b is provided in parallel with the column direction L1, the one side 231 ′ and the first side 229 ′ constituting the extraction electrode 225b are provided on a straight line. Yes.

  Therefore, the junction part of 1 side 231 'and 1st side 229' which comprise the extraction electrode 225b will be formed on the same straight line as 1 side 231 'and 1st side 229' which comprise the extraction electrode 225b. Further, it is possible to further reduce the stress generated at the joint portion between the first side 231 ′ and the first side 229 ′ constituting the extraction electrode 225b.

  In addition, since the one side 231 ′ and the first side 229 ′ constituting the extraction electrode 225b are provided continuously and along the column direction L1, the individual sides adjacent to each other in the row direction L2 are provided. A separation distance between the electrodes 225 can be ensured, and crosstalk can be reduced.

  A liquid discharge head 300 according to another embodiment will be described with reference to FIGS. In the liquid discharge head 300, the individual electrode main body 325 a includes two obtuse angle portions 325 a 2, a first notch portion 327, and a second notch portion 333. The first cutout portion 327 is formed by cutting out one acute angle portion 325a1 by the first side 329. The second cutout 333 is formed by cutting out the other acute angle portion 325a1 by the second side 335. The second notch 333 is provided on the first region R1 side of the individual electrode main body 325a. Therefore, the individual electrode main body 325a is not formed in the first region R1.

  The discharge characteristics of the liquid discharged from the plurality of discharge holes 8 may vary depending on the difference in the area of the individual electrode main body 325a disposed on the first region R1, but the individual electrode main body 325a is different from the second region R2. Therefore, the difference in the area of the individual electrode main body 325a disposed on the first region R1 is eliminated, and variations in the liquid discharge amount and the discharge speed can be reduced.

  Furthermore, the second side 335 is preferably provided along the column direction L1. By providing the second side 335 along the column direction L1, which is the direction in which the partition 15 extends, the second side 335 and the partition 15 are provided in parallel. Therefore, the boundary between the second side 335 and the first region R is provided in parallel, and the possibility that the individual electrode main body 25 is provided on the first region R1 can be reduced.

  The separation distance between the second side 335 and the boundary between the first region R1 is preferably 0.4 mm or more. When the separation distance is 0.4 mm or more, the possibility that the individual electrode main body 325a is disposed on the first region R1 can be reduced even when stacking shift or deformation at the time of firing occurs. In addition, the separation distance between the second side 335 and the boundary between the first region R1 is 0.4 times or more the distance connecting the acute angle portions 310a of the pressurizing chamber 310, and the obtuse angle portions 310b of the pressurizing chamber 310 are separated from each other. It is preferable that the distance is not less than 0.8 times the connecting distance.

  In plan view, the first side 329 and the second side 335 may each have a convex shape that protrudes toward the acute angle portion 310 a of the pressurizing chamber 310. Even in this case, crosstalk between the individual electrodes 325 can be reduced, and variations in the liquid ejection characteristics can be reduced.

  Moreover, it is preferable that the area of the 2nd electrode main body 325a cut off by the 1st notch part 327 and the 2nd notch part 333 is substantially equivalent. That is, it is preferable that the lengths of the first side 329 and the second side 335 in the column direction L1 are substantially equal. Thereby, the crosstalk between the individual electrodes 325 constituting the pair of individual electrodes 325 can be reduced, and the crosstalk between the pair of adjacent individual electrodes 325 can also be reduced.

  FIG. 10B shows a liquid ejection head 300 ′ that is a modified example.

  Here, the pressurizing chamber 310 is formed by providing a hole in the cavity plate 4a (see FIG. 5). Therefore, the cavity plate 4a is provided in the vicinity of the acute angle portion 310a of the pressurizing chamber 310 so as to surround the acute angle portion 310a. Similarly, in the vicinity of the obtuse angle part 310b of the pressurizing chamber 310, the cavity plate 4a is provided so as to surround the obtuse angle part 310b. Thereby, the rigidity in the vicinity of the acute angle part 310a is higher than the rigidity in the vicinity of the obtuse angle part 310b.

  However, the liquid discharge head 300 is configured such that the extraction portion 325b ′ is extracted from the vicinity of the acute angle portion 325a1 of the individual electrode main body 325a. Therefore, since the portion of the extraction electrode 325b ′ located above the pressurizing chamber 310 passes only one acute angle portion 310a of the highly rigid pressurization chamber 310, the piezoelectric ceramic layer located below the extraction electrode 325b ′. The influence of the deformation of 21b on the deformation amount of the displacement element 30 located on the pressurizing chamber 310 can be reduced.

  The first side 331 ′ and the second side 333 ′ constituting the continuously formed extraction electrode 325 b ′ may have a convex shape that protrudes toward the first region R <b> 1 in plan view. In that case, it is possible to reduce the stress generated at the joint portion between the second side 333 ′ and the individual electrode main body 325a.

  A liquid ejection head 400 according to still another embodiment will be described with reference to FIG. The individual flow path 432 communicating with the pressurizing chamber 410 is schematically indicated by a broken line, and the third region R3 located above the individual flow path 432 of the piezoelectric actuator substrate (not shown) is indicated by a one-dot chain line. Yes.

  In the liquid discharge head 400, a flow path member (not shown) includes an individual flow path 432 communicating with a discharge hole (not shown) from a portion provided in the first region R1 of the pressurizing chamber 410. The actuator substrate includes a third region R3 located above the individual flow path 432. And the 2nd notch part 433 is provided in the 1st area | region R1 side of the separate electrode main body 425a, Therefore, the 2nd electrode main body 425a is not formed in 3rd area | region R3.

  As described above, the partition wall 15 of the manifold 5 is provided with the individual flow paths 432 communicating with the pressurizing chambers 410 respectively. The individual flow path 432 is provided inside the partition wall 15 and has a space for circulating a liquid. Therefore, the region of the partition wall 15 where the individual flow path 432 is provided is less rigid than the region of the partition wall 15 where the individual flow path 432 is not provided. The difference in rigidity of the flow path member due to the individual flow path 422 also affects the piezoelectric actuator substrate stacked on the flow path member.

  That is, the rigidity of the third region R3 located on the individual flow path 422 is lower than that of the first region R1 of the piezoelectric actuator substrate. Therefore, if the individual electrode main body 425a is also provided in the third region R3, there is a possibility that the liquid discharge amount or the discharge speed may vary due to the third region R3 having different rigidity.

  However, since the liquid ejection head 400 is provided with the second notch 433 on the first region R1 side of the individual electrode main body 425a and the second electrode main body 425a is not formed in the third region R3, the third region It is possible to reduce the possibility that the liquid discharge amount or the discharge speed varies due to R3.

Further, the individual flow path 422 needs to communicate from each pressurizing chamber 410 to a predetermined discharge hole (not shown), and the third region R3 provided around each pressurizing chamber 410 has a shape. Will be different. Therefore, in order to obtain a configuration that is not disposed on the third region R3, it is necessary to change the shape of the individual electrode main body 425a for each pressurizing chamber 410. The liquid ejection head 400 has a configuration in which the individual electrode main body 425a is not provided on the third region by the second notch 433, and the individual electrode main body 425a is not easily provided on the third region R3. It can be.

  In order to further reduce the variation in the liquid ejection characteristics, the extraction electrode 425b may not be provided on the third region R3. Thereby, the influence by deformation | transformation of the piezoelectric ceramic layer 21b located under the extraction electrode 425a can be reduced.

  The liquid discharge head 2 as described above is manufactured as follows, for example. A tape made of a piezoelectric ceramic powder and an organic composition is formed by a general tape forming method such as a roll coater method or a slit coater method, and a plurality of green sheets that become piezoelectric ceramic layers 21a and 21b after firing are produced. . An electrode paste to be the common electrode 24 is formed on a part of the green sheet by a printing method or the like. Further, a via hole is formed in a part of the green sheet as necessary, and a via conductor is filled in the via hole.

  Next, each green sheet is laminated to produce a laminate, and after pressure-contacting, the laminate is cut into a rectangular shape and further fired in a high-concentration oxygen atmosphere. An organic gold paste is printed on the surface of the fired piezoelectric actuator body by screen printing, and fired to form the individual electrodes 25. Screen printing uses a screen with a mesh attached at an angle of 45 degrees to the frame, places a rectangular piezoelectric actuator element parallel to the frame of the screen, and places the squeegee on the piezoelectric actuator element. Print by moving parallel to the longitudinal direction. Thereafter, the connection electrode 26 is printed using Ag paste and fired to produce the piezoelectric actuator substrate 21.

  Next, the flow path member 4 is produced by laminating plates 4a to 1l obtained by a rolling method or the like via an adhesive layer. Holes to be the manifold 5, the individual supply flow path 14, the pressurizing chamber 10, the descender, and the like are processed in the plates 4a to 4l into a predetermined shape by etching.

  These plates 4a to 4l are preferably formed of at least one metal selected from the group consisting of Fe-Cr, Fe-Ni, and WC-TiC, particularly when ink is used as a liquid. Since it is desired to be made of a material having excellent corrosion resistance against ink, Fe-Cr is more preferable.

  The piezoelectric actuator substrate 21 and the flow path member 4 can be laminated and bonded through, for example, an adhesive layer. A well-known adhesive layer can be used as the adhesive layer, but in order not to affect the piezoelectric actuator substrate 21 and the flow path member 4, an epoxy resin or a phenol resin having a thermosetting temperature of 100 to 150 ° C. It is preferable to use at least one thermosetting resin adhesive selected from the group of polyphenylene ether resins. By heating to the thermosetting temperature using such an adhesive layer, the piezoelectric actuator substrate 21 and the flow path member 4 can be heat-bonded.

  Next, in order to electrically connect the piezoelectric actuator substrate 21 and the control circuit 100, a silver paste is supplied to the connection electrode 26, an FPC which is a signal transmission unit 92 on which a driver IC is mounted in advance is placed, and heat is applied. In addition, the silver paste is cured and electrically connected. The driver IC is mounted by electrically flip-chip connecting to the FPC with solder, and then supplying a protective resin around the solder and curing.

  Subsequently, if necessary, the reservoir is bonded so that the liquid can be supplied from the opening 5a, the metal housing is screwed, and then the joint is sealed with a sealant or the like, whereby the liquid ejection head 2 is sealed. Can be produced.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... Head main body 4 ... Channel member 4a-l ... (channel member) plate 5 ... Manifold (common channel)
5a ... (manifold) opening 5b ... sub-manifold 6 ... squeezing 8 ... discharge hole 9 ... discharge hole row 10 ... pressurizing chamber 10a ... acute angle part 10b ... Obtuse angle part 11a ... pressurizing chamber row 11b ... pressurizing chamber row 12 ... individual channel 14 ... individual supply channel 15 ... partition 21 ... piezoelectric actuator substrate 21a ... piezoelectric Ceramic layer (diaphragm)
21b: Piezoelectric ceramic layer 24: Common electrode (first electrode)
25 ... Individual electrode (second electrode)
25a ... Individual electrode body 25a1 ... Acute angle part (individual electrode body) 25a2 (Individual electrode body) obtuse angle part 25b ... Extraction electrode 26 ... Connection electrode 27 ... First notch part 28 ..Surface electrode for common electrode 29 ... first side 30 ... displacement element (pressurizing part)
92 ... Signal transmission part (wiring board)

Claims (10)

A flow path member having a plurality of discharge holes, a plurality of pressurization chambers communicating with the plurality of discharge holes, and a manifold communicating with the plurality of pressurization chambers;
A piezoelectric actuator substrate laminated on the flow path member so as to cover the plurality of pressurizing chambers,
The manifold has a partition and a plurality of sub-manifolds partitioned by the partition,
In the piezoelectric actuator substrate, a first electrode, a piezoelectric layer, and a plurality of second electrodes are laminated in this order from the flow path member side, and the first region located on the partition and the sub manifold A second region located at
The second electrode includes a second electrode main body located above the pressurizing chamber, and an extraction electrode extracted from the second electrode main body;
Each of the pair of second electrodes provided on the second region has a first cutout, and the first cutouts of the pair of second electrodes face each other. Liquid discharge head.   2. The liquid ejection head according to claim 1, wherein the first electrode body includes the first cutout portion in a plan view and includes a first side along the partition wall.   The planar view of the pair of second electrodes, wherein the first side of one of the second electrodes has a convex shape protruding toward the other second electrode. Liquid discharge head.   The liquid ejection head according to claim 2, wherein the extraction electrode is formed continuously with the first side.   The second cutout portion is formed on the first region side of the second electrode body, and the second electrode body is not formed in the first region. Liquid discharge head.   6. The liquid ejection head according to claim 5, wherein the second cutout portion is formed in the second electrode main body and a second side along the partition is provided in a plan view.   The liquid ejection head according to claim 6, wherein the second side has a convex shape protruding toward the first region in a plan view. The flow path member includes a flow path communicating with the discharge hole from a portion provided in a region corresponding to the first region of the pressurizing chamber;
The piezoelectric actuator substrate further comprises a third region located above the flow path;
The liquid ejection head according to claim 5, wherein the second electrode main body is not formed in the third region. The pressurizing chamber has a rhombus shape having two obtuse angle portions and two acute angle portions, and one acute angle portion is disposed in a region corresponding to the first region;
The second electrode body includes two obtuse angle portions, the first cutout portion, and the second cutout portion;
9. The liquid ejection head according to claim 5, wherein the second cutout portion is disposed on the one acute angle portion side of the pressurizing chamber. A liquid discharge head according to any one of claims 1 to 9,
A transport unit for transporting a recording medium to the liquid discharge head;
And a controller that controls the liquid discharge head.

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