JP5826377B2 - Liquid discharge head and recording apparatus using the same - Google Patents

Description

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

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

  In such an ink jet printing apparatus, a liquid discharge head for discharging liquid is mounted as a print head. This type of print head includes a heater as a pressurizing unit in an ink flow path filled with ink, heats and boiles the ink with the heater, pressurizes the ink with bubbles generated in the ink flow path, A thermal head system that ejects ink as droplets from the ink ejection holes, and a part of the wall of the ink channel filled with ink is bent and displaced by a displacement element, and the ink in the ink channel is mechanically pressurized, and the ink A piezoelectric method for discharging liquid droplets from discharge holes is generally known.

  In addition, such a liquid ejection head has a serial type that performs recording while moving the liquid ejection head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and is long in the main scanning direction. There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with the liquid discharge head fixed. The line type has the advantage that high-speed recording is possible because there is no need to move the liquid discharge head as in the serial type.

  Therefore, a long liquid discharge head in one direction is provided so as to cover the pressure chamber and a flow path member having discharge holes that connect the manifold and the manifold through a plurality of pressure chambers, respectively, as a common flow path. In addition, an actuator unit that includes a plurality of actuator units having a plurality of displacement elements is known (see, for example, Patent Document 1). In this liquid ejection head, pressurization chambers connected to a plurality of ejection holes are arranged in a matrix, and the displacement element of the actuator unit provided so as to cover it is displaced to eject ink from each ejection hole. Thus, printing is possible at a resolution of 600 dpi in the main scanning direction.

JP 2003-305852 A

  However, in the liquid discharge head described in Patent Document 1, the relationship between the manifold and the shape and arrangement of the individual electrodes of each displacement element has an effect, and the variation in discharge characteristics sometimes increases. In addition, when a wiring board that supplies a drive signal is connected to the piezoelectric actuator board (piezoelectric actuator unit), the parts that electrically connect the individual electrodes of the respective displacement elements and the wiring board are arranged at high density on the wiring board. Therefore, the wiring interval of the wiring board has to be narrowed or the wiring width has to be narrowed, so that the reliability has been lowered or it has become impossible to design with design rules that can be manufactured in the first place.

  Accordingly, it is an object of the present invention to provide a liquid discharge head that can reduce discharge variation and increase the reliability of a wiring board, and a recording apparatus using the liquid discharge head.

  The liquid discharge head of the present invention has a plurality of discharge holes, a plurality of pressurization chambers connected to the plurality of discharge holes, and one or a plurality of common flow channels connected to the plurality of pressurization chambers. A liquid discharge head comprising a flow path member, a piezoelectric actuator substrate stacked on the flow path member so as to cover the plurality of pressurizing chambers, and a wiring substrate, wherein the piezoelectric actuator substrate includes: One electrode, a piezoelectric body, and a plurality of second electrodes are laminated in this order from the flow path member side, and when the liquid discharge head is viewed in plan, each of the plurality of pressurizing chambers has two obtuse angle portions. And two acute angle portions, and at substantially equal intervals on a row along a diagonal line connecting the two obtuse angle portions and on a column along the diagonal line connecting the two acute angle portions, respectively. Arranged and said The flow path extends along the row direction and is connected to the pressurizing chambers arranged in a row on both sides of the common flow path, and each of the flow paths connected to the common flow path The pressurizing chamber has a first region that overlaps with the common flow channel and a second region that does not overlap with the common flow channel, and the plurality of second electrodes are respectively a plurality of the plurality of second electrodes. Is arranged so as to overlap with the pressurizing chamber, and is connected to the electrode main body housed inside the pressurizing chamber, one end of the electrode main body in the first region, and the other end of the electrode main body. The first extraction electrode drawn out of the pressurizing chamber and one end of the electrode are connected to the electrode body in the second region, and the other end is drawn out of the pressurizing chamber. And the second lead electrode is electrically connected to the wiring board. Together is either one of the poles of the first lead electrode and the second lead electrode in the row direction, and wherein it is connected to alternating.

  The recording apparatus of the invention includes the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the piezoelectric actuator substrate. .

  According to the present invention, the discharge variation can be reduced, the wiring interval of the wiring board can be increased, and the wiring width can be increased, so that the reliability of the wiring board can be increased.

1 is a schematic configuration diagram of a color inkjet 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. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. It is a longitudinal cross-sectional view along the VV line of FIG. (A) is an enlarged plan view of the liquid ejection head shown in FIGS. 2 to 5, and (b) is an enlarged plan view of a liquid ejection head according to another embodiment of the present invention. FIG. 6 is an enlarged plan view of a liquid ejection head according to another embodiment of the present invention. FIG. 6 is an enlarged plan view of the liquid ejection head shown in FIGS. It is the top view which expanded FIG. 6 (a) further.

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

  In the printer 1, a paper feed unit 114, a transport unit 120, and a paper receiver 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 and 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 can send out the uppermost print paper P among the print papers P stacked and stored in the paper storage case 115 one by one.

  Between the paper feed unit 114 and the transport unit 120, two pairs of feed rollers 118a and 118b and 119a and 119b are arranged 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 and further sent out to the transport unit 120.

  The transport unit 120 includes an endless 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 two belt rollers. Thus, the conveyor belt 111 is stretched without slack along two parallel planes each including a common tangent line of the two belt rollers. Of these two planes, the plane closer to the liquid ejection head 2 is a transport surface 127 that transports the printing paper P.

  As shown in FIG. 1, a conveyance motor 174 is connected to the belt roller 106. The transport motor 174 can rotate the belt roller 106 in the direction of arrow A. The belt roller 107 can rotate in conjunction with the transport belt 111. Therefore, the conveyance belt 111 moves along the direction of arrow A by driving the conveyance motor 174 and rotating the belt roller 106.

  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 two nip rollers are rotatably installed and rotate in conjunction with the conveyance 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 4-1, in which a large number of discharge holes for discharging liquid are provided.

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. Each liquid discharge head 2 is supplied with liquid from an external liquid tank (not shown). The liquid ejection holes 8 of each liquid ejection head 2 are open to the surface of the liquid ejection holes, and are in one direction (a direction parallel to the printing paper P and perpendicular to the conveyance direction of the printing paper P, and the longitudinal direction of the liquid ejection head 2. (Direction) at equal intervals, it is possible to print without gaps in one 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, droplets are 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 and 121b and 122a and 122b are arranged 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 out to the paper receiving unit 116 by the feed rollers 121a to 122b. In this way, the printed printing paper P is sequentially sent to the paper receiving unit 116 and stacked on the paper receiving unit 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 and a light receiving element, and can detect the leading end position 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 can control the liquid ejection head 2, the conveyance motor 174, and the like so that the conveyance of the printing paper P and the printing of the image are synchronized based on the detection result sent from the paper surface sensor 133.

  Next, the liquid discharge head 2 of the present invention will be described. FIG. 2 is a plan view of the head main body 2a. FIG. 3 is an enlarged view of the region surrounded by the alternate long and short dash line in FIG. 2, and is a plan view in which some of the flow paths are omitted for explanation. 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 squeezing 6, the discharge hole 8, the pressurizing chamber 10, and the like to be drawn by broken lines below the piezoelectric actuator substrate 21 are drawn by solid lines. FIG. 5 shows only one of the two extraction electrodes 25b. FIG. 5 is a longitudinal sectional view taken along line VV in 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 that is the first 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. FIG. 6A is an enlarged plan view of the liquid ejection head shown in FIGS.

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

  The flow path member 4 constituting the head body 2a includes a manifold 5, a plurality of pressurizing chambers 10 connected to the manifold 5, and a plurality of discharge holes 8 connected to the plurality of pressurizing chambers 10, respectively. The pressurizing chamber 10 opens to the upper surface of the flow path member 4, and the upper surface of the flow path member 4 is a pressurizing chamber surface 4-2. In addition, 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 21 is indicated by a dotted line so that the two signal transmission units 92 are connected to the piezoelectric actuator substrate 21. 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 displacement of the displacement element 30. Do not suppress. A large number of wirings 92b are arranged along the short direction of the head main body 2a in a region facing the piezoelectric actuator substrate 21 of the signal transmission unit 92, and the left and right portions of FIG. It is connected to. 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 wiring 92b has an electrode electrically connected to the piezoelectric actuator 21 on the side of the piezoelectric actuator substrate 21, and this electrode is disposed in a rectangular shape at the end of the signal transmission unit 92. 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.

  In addition, a driver IC is mounted on the signal transmission unit 92. 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 dissipated 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 piezoelectric actuator substrate 21 including a flat plate-like flow path member 4 and a displacement element 30 connected on the flow path member 4. The planar shape of the piezoelectric actuator substrate 21 is rectangular, and is arranged on the upper surface of the flow path member 4 so that the long side of the rectangle is along the longitudinal direction of the flow path member 4.

  Two manifolds 5 are formed inside the flow path member 4. The manifold 5 has an elongated shape that extends from one end side in the longitudinal direction of the flow path member 4 to the other end side, and the manifold opening 5a that opens to the upper surface of the flow path member 4 at both ends. Is formed. By supplying the liquid from both ends of the manifold 5 to the flow path member 4, it is possible to prevent the liquid from being insufficiently supplied. Further, as compared with the case where the liquid is supplied from one end of the manifold 5, the difference in pressure loss caused when the liquid flows through the manifold 5 can be reduced to about half, so that the variation in the liquid 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 completely separates the manifold 5 into a plurality of sub-manifolds 5b. By doing so, it is possible to provide the discharge hole 8 and a descender connected from the discharge hole 8 to the pressurizing chamber 10 so as to overlap with the partition wall 15 when seen in a plan view.

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

  The portion of the manifold 5 divided into a plurality of parts may be referred to as a sub-manifold 5b. In this embodiment, two manifolds 5 are provided independently, and openings 5a are provided at both ends. One manifold 5 is provided with seven partition walls 15 and divided into eight sub-manifolds 5b. The width of the sub-manifold 5b is larger than the width of the partition wall 15, so that a large amount of liquid can flow through the sub-manifold 5b. In addition, the length of the seven partition walls 15 becomes longer as they are closer to the center in the width direction. At both ends of the manifold 5, the ends of the partition walls 15 are closer to the ends of the manifold 5 as the partition walls 15 are closer to the center in the width direction. It ’s close. As a result, the flow resistance generated by the outer wall of the manifold 5 and the flow resistance generated by the partition wall 15 are balanced, and the individual supply flow that is the portion connected to the pressurizing chamber 10 in each sub-manifold 5b. The pressure difference of the liquid at the end of the region where the channel 14 is formed can be reduced. Since the pressure difference in the individual supply channel 14 leads to a pressure difference applied to the liquid in the pressurizing chamber 10, the discharge variation can be reduced if the pressure difference in the individual supply channel 14 is reduced.

  The flow path member 4 is formed by two-dimensionally expanding a plurality of pressurizing chambers 10. The pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape having two acute angle portions 10a and two acute angle portions 10b with rounded corners.

  The pressurizing chamber 10 is connected to one sub-manifold 5b through an individual supply channel 14. Along with one sub-manifold 5b, two pressurizing chamber rows 11, which are rows of pressurizing chambers 10 connected to the sub-manifold 5b, are provided on each side of the sub-manifold 5b, for a total of two rows. Yes. Accordingly, 16 rows of pressurizing chambers 11 are provided for one manifold 5, and 32 heads of pressurizing chambers 11 are provided in the entire head body 2a. The intervals in the longitudinal direction of the pressurizing chambers 10 in the respective pressurizing chamber rows 11 are the same, for example, 37.5 dpi.

  A dummy pressurizing chamber 16 is provided at the end of each pressurizing chamber row 11. The dummy pressurizing chamber 16 is connected to the manifold 5 but is not connected to the discharge hole 8. Further, outside the 32 pressurizing chamber rows 11, dummy pressurizing chamber rows in which dummy pressurizing chambers 16 are arranged in a straight line are provided. The dummy pressurizing chamber 16 is not connected to either the manifold 5 or the discharge hole 8. By these dummy pressurizing chambers, the structure (rigidity) around the pressurizing chamber 10 that is one inward from the end is close to the structure (rigidity) of the other pressurizing chambers 10, thereby reducing the difference in liquid ejection characteristics. it can. In addition, since the influence of the surrounding structure difference has a large influence on the pressurizing chambers 10 adjacent to each other in the length direction, the dummy pressurizing chambers are provided at both ends in the length direction. Since the influence in the width direction is relatively small, it is provided only on the side closer to the end of the head main body 21a. Thereby, the width | variety of the head main body 21a can be made small.

  The pressurizing chambers 10 connected to one manifold 5 are arranged at substantially equal intervals on the rows and on the columns along the row direction which is the longitudinal direction of the liquid discharge head 2 and the column direction which is the short direction. Has been placed. The row direction is a direction along a diagonal line connecting the obtuse corners 10b of the rhombus-shaped pressurizing chamber 10, and is also a direction formed by connecting the center of gravity of the pressurizing chamber 10 in which the obtuse angle portions 10b are arranged facing each other. . The rhombus shape of the pressurizing chamber 10 may have a side length different by about 10%. Further, the direction of the diagonal line connecting the obtuse angle portions 10b and the row direction are arranged in a state where the pressurizing chamber 10 is rotated in a plane, or the side length is different, so that an angle of about 10 degrees or less is formed. It may be attached. The column direction is a direction along a diagonal line connecting the acute angle portions 10a of the rhombus-shaped pressurizing chambers 10, and is also a direction formed by connecting the center of gravity of the pressurizing chambers 10 arranged with the acute angle portions 10a facing each other. . The direction of the diagonal line connecting the acute angle portions 10a and the row direction are at an angle of about 10 degrees or less because the pressurizing chamber 10 is arranged in a state of being rotated in a plane or the lengths of the sides are different. It may be. That is, the angle formed by the rhombic diagonal lines of the pressurizing chamber 10 with respect to the row direction and the column direction is small. By arranging the pressurizing chambers 10 in a lattice shape and arranging the rhombic pressurizing chambers 10 having such angles, crosstalk can be reduced. This is because the corners face each other in both the row direction and the column direction with respect to one pressurizing chamber 10, so that the flow path member is more than the case where the sides face each other. This is because vibration is difficult to be transmitted through 4. Here, by making the obtuse angle portions 10b face each other in the longitudinal direction, the density of the pressurizing chambers 10 in the longitudinal direction can be increased, whereby the density of the discharge holes 8 in the longitudinal direction can be increased. The liquid ejection head 2 with a resolution can be obtained. If the intervals between the pressurizing chambers 10 on the rows and columns are equal, the crosstalk can be reduced by eliminating the narrower intervals than others, but the intervals may differ by about ± 20%.

  When the pressurizing chambers 10 are arranged in a lattice shape and the piezoelectric actuator 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 an equal distance, the piezoelectric actuator substrate 21 can be hardly deformed when the individual electrodes 25 are formed. When the piezoelectric actuator substrate 21 and the flow path member 4 are joined, if this deformation is large, stress may be applied to the displacement element 30 near the outer side, resulting in variations in displacement characteristics. However, by reducing the deformation, The variation can be reduced. In addition, since the dummy pressurizing chamber row of the dummy pressurizing chamber 16 is provided outside the pressurizing chamber row 11 closest to the outer side, the influence of deformation can be made less susceptible. The pressurizing chambers 10 belonging to the pressurizing chamber row 11 are arranged at equal intervals, and the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals. The pressurizing chamber rows 11 are arranged at equal intervals in the short direction, and the columns of the individual electrodes 25 corresponding to the pressurizing chamber rows 11 are also arranged at equal intervals in the short direction. Thereby, it is possible to eliminate a portion where the influence of the crosstalk becomes particularly large.

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

  The pressurizing chambers 10 connected to one sub-manifold 5 b constitute two pressurizing chamber rows 11, and the discharge holes 8 connected to the pressurizing chambers 10 belonging to one pressurizing chamber row 11 are One pressurizing chamber row 11 is configured. The discharge holes 8 connected to the pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 open to different sides of the sub-manifold 5b. In FIG. 4, the partition wall 15 is provided with two pressurizing chamber rows 11, but the discharge holes 8 belonging to the respective pressurization chamber rows 11 are pressurized to the sub-manifold 5 b near the discharge holes 8. It is connected via the chamber 10. When the discharge hole 8 connected to the adjacent sub-manifold 5b via the pressurizing chamber row 11 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 the flow paths can be suppressed, the 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.

  In addition, 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. When the ratio of the overlapping area to the area of the pressurizing chamber 10 is 80% or more, and further 90% or more, the width of the liquid discharge head 2 can be further reduced. Further, the bottom surface of the pressurizing chamber 10 where the pressurizing chamber 10 and the sub-manifold 5b overlap is less rigid than the case where the pressurizing chamber 10 and the sub-manifold 5b do not overlap. There is a risk of variation. By making the ratio of the area of the pressurizing chamber 10 overlapping the sub-manifold 5b to the area of the entire pressurizing chamber 10 substantially the same in each pressurizing chamber 10, the rigidity of the bottom surface constituting the pressurizing chamber 10 is increased. Variations in ejection characteristics due to changes can be reduced. Here, “substantially the same” means that the difference in area ratio is 10% or less, particularly 5% or less.

  A plurality of pressurizing chambers are formed by a plurality of pressurizing chambers 10 connected to one manifold 5. Since there are two manifolds 5, there are two pressurizing chamber groups. The arrangement of the pressurizing chambers 10 related to ejection in each pressurizing chamber group is the same, and is arranged to be translated in the lateral direction. These pressurizing chambers 10 are arranged over almost the entire surface although there are portions where the gaps between the pressurizing chamber groups are slightly wide in the region facing the piezoelectric actuator substrate 21 on the upper surface of the flow path member 4. . That is, the pressurizing chamber group formed by these pressurizing chambers 10 occupies an area having almost 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 connected to the discharge hole 8 opened in the discharge hole surface 4-1 on the lower surface of the flow path member 4 extends from a corner portion of the pressurizing chamber 10 facing the corner portion where the individual supply flow path 14 is connected. ing. 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.

  In other words, when the discharge holes 8 are projected so as to be orthogonal to the virtual straight line parallel to the longitudinal direction of the flow path member 4, each manifold 5 is within the range of R of the virtual straight line shown in FIG. That is, 16 discharge holes 8 connected to, and a total of 32 discharge holes 8 are equally spaced by 1200 dpi. Thus, by supplying the same color ink to all the manifolds 5, an image can be formed with a resolution of 1200 dpi in the longitudinal direction as a whole. Further, one discharge hole 8 connected to one manifold 5 is equally spaced at 600 dpi within the range of R of the imaginary straight line. As a result, by supplying different colors of ink to the respective manifolds 5, it is possible to form two-color images with a resolution of 600 dpi in the longitudinal direction as a whole. In this case, if two liquid ejection heads 2 are used, an image of four colors can be formed at a resolution of 600 dpi, and printing accuracy is higher and printing settings are easier than using a liquid ejection head capable of printing at 600 dpi. Can be.

  Furthermore, a reservoir may be joined to the flow path member 4 in the liquid ejection head 2 so as to stabilize the liquid supply from the opening 5a of the manifold. The reservoir is provided with a flow path that branches the liquid supplied from the outside and is connected to the two openings 5a, so that the liquid can be stably supplied to the two openings. By making the flow path lengths after branching substantially equal, temperature fluctuations and pressure fluctuations of the liquid supplied from the outside are transmitted to the openings 5a at both ends of the manifold 5 with a small time difference. Variations in droplet ejection characteristics can be further reduced. By providing a damper 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.

  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 includes an individual electrode main body 25a that is slightly smaller than the pressurizing chamber 10 and has a shape substantially similar to the pressurizing chamber 10, and an extraction electrode 25b that is extracted from the individual electrode main body 25a. In the same manner as the pressurizing chamber 10, the individual electrode 25 constitutes an individual electrode row and an individual electrode group. One end of the extraction electrode 25b is connected to the individual electrode main body 25a, and the other end passes through the acute angle portion 10a of the pressurization chamber 10, and outside the pressurization chamber 10, two acute angle portions of the pressurization chamber 10 are provided. 10a is drawn to a region that does not overlap with the extended row of diagonal lines connecting 10a. Thereby, crosstalk can be reduced. The shape of the extraction electrode 25b will be described in detail later.

  A common electrode surface electrode 28 is formed on the upper surface of the piezoelectric actuator substrate 21 and is electrically connected to the common electrode 24 as a second electrode through a via hole. The common electrode surface electrodes 28 are formed in two rows along the longitudinal direction in the central portion of the piezoelectric actuator substrate 21 in the short direction, and are formed in one row along the short direction near the end in the longitudinal direction. ing. Although the illustrated common electrode surface electrode 28 is intermittently formed on a straight line, it may be formed continuously on a straight line.

  The piezoelectric actuator substrate 21 is formed by laminating and firing a piezoelectric ceramic layer 21a having a via hole, a common electrode 24, and a piezoelectric ceramic layer 21b, as will be described later, and then forming individual electrodes 25 and a common electrode surface electrode 28 in the same process. It is preferable to do this. The positional variation between the individual electrode 25 and the pressurizing chamber 10 greatly affects the ejection characteristics, and if the individual electrode 25 is formed and then fired, the piezoelectric actuator substrate 21 may be warped. When the 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 individual electrode 25 is formed after firing. Similarly, the surface electrode 28 for the common electrode may be warped, and if the 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. The surface electrode 28 is formed in the same process.

  Such a positional variation of via holes due to firing shrinkage that may occur when firing the piezoelectric actuator substrate 21 mainly occurs in the longitudinal direction of the piezoelectric actuator substrate 21, and therefore, a manifold having an even number of common electrode surface electrodes 28. 5, in other words, it is provided at the center in the short direction of the piezoelectric actuator substrate 21, and the common electrode surface electrode 28 has a long shape in the longitudinal direction of the piezoelectric actuator substrate 21. In addition, 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 this time, the connection is facilitated by forming the connection electrode 26 and the common electrode connection electrode on the extraction electrode 25b and the common electrode surface electrode 28 of the piezoelectric actuator substrate 21a, respectively, and connecting them. 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 in the longitudinal direction) ) Can be made stronger by the connection on the common electrode surface electrode 28, so that the signal transmission portion 92 can be made difficult to peel off 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 almost the same size and shape as the piezoelectric actuator substrate 21 as a group, and the displacement elements 30 of the corresponding piezoelectric actuator substrate 21 are displaced to displace the discharge holes 8 from the discharge holes 8. Droplets can be ejected.

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

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

  Third, there is a communication hole 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 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.

  The piezoelectric actuator substrate 21 has a laminated structure composed of two piezoelectric ceramic layers 21a and 21b which are piezoelectric bodies. 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 (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 therefrom. Yes. 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 almost 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 formed at a position avoiding the electrode group composed of the individual electrodes 25 on the piezoelectric ceramic layer 21b through a via hole formed in the piezoelectric ceramic layer 21b. Grounded and held at 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 volume of the pressurizing chamber 10 corresponding to the individual electrode 25 changes, and the liquid in the pressurizing chamber 10 is pressurized. Is added. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 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, a displacement element 30, which is a piezoelectric actuator having a unit structure as shown in FIG. 5, is added to each pressurizing chamber 10 in a laminate composed of two piezoelectric ceramic layers 21 a and 21 b. The piezoelectric actuator substrate 21 includes a plurality of displacement elements 30 as pressurizing portions. The diaphragm 21a is located directly above the pressure chamber 10, is formed by a common electrode 24, a piezoelectric ceramic layer 21b, and individual electrodes 25. Yes. 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 their original shapes 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. After that, 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. The pressure becomes positive and the pressure on the liquid rises, and droplets are ejected. That is, in order to discharge the droplet, 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 droplets can be discharged at a stronger pressure.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the ejection holes 8, that is, the droplet amount (volume) adjusted by the number of droplet ejections. For this reason, the number of droplet discharges corresponding to the designated gradation expression is continuously performed from the discharge holes 8 corresponding to the designated dot region. In general, when liquid ejection is performed continuously, it is preferable that the interval between pulses supplied to eject liquid droplets is AL. As a result, the period of the residual pressure wave of the pressure generated when discharging the previously discharged liquid droplet coincides with the pressure wave of the pressure generated when discharging the liquid droplet discharged later, and these are superimposed. Thus, the pressure for discharging the droplet can be amplified. In this case, it is considered that the speed of the liquid droplets ejected later increases, but this is preferable because the landing points of a plurality of liquid droplets are close.

  Here, in the head main body 2a, one sub-manifold 5a is connected to two pressurizing chamber rows 11 arranged on the left and right sides of the sub-manifold 5a in a plan view. The pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 have a first region 10-1 that overlaps the sub-manifold 5a and a second region 10-2 that does not overlap. With such an arrangement, the width of the sub-manifold can be increased to ensure the flow rate, and the length of the head body 2a in the short direction can be shortened.

  However, with such an arrangement, the ejection characteristics may vary depending on whether the extraction electrode 25b is extracted from the first region 10-1 of the pressurizing chamber 10 or the second region 10-2. is there. Due to the potential difference between the extraction electrode 25a and the common electrode 24, the influence of the piezoelectric deformation of the piezoelectric ceramic layer 21b between the extraction electrode 25a and the common electrode 24 is extracted from the first region 10-1, and the first sub manifold 5a is directly below. This is because the extraction electrode 25a-1 is different from the extraction electrode 25b-2 which is extracted from the second region 10-2 and does not have the sub-manifold 5a. For example, since the sub-manifold 5a directly under the structure is more easily deformed, the discharge conditions change more greatly from the ideal state due to the piezoelectric deformation directly under the extraction electrode 25b-1, and the discharge speed is reduced or discharged. The amount may be reduced.

  Therefore, as shown in FIG. 6A, the first electrode 25b is provided on the individual electrode 25, and one of them is drawn from the first region 10-1 of the pressurizing chamber 10 that overlaps the sub-manifold 5a. Discharge variation can be reduced by using the extraction electrode 25b-1 as the second extraction electrode 25b-2 that is extracted from the second acute angle portion of the pressurizing chamber 10 at a position where the other does not overlap the sub-manifold 5a. 6A also shows a wiring 92b of the signal transmission unit 92 which is a wiring board connected to the piezoelectric actuator 21. FIG. Since the lines in the figure are complicated, everything that is actually transmitted is shown as a solid line.

  A plurality of first extraction electrodes 25b-1 may be extracted from the first region 10-1. A plurality of second extraction electrodes 25b-2 may also be extracted from the second region 10-2. At that time, if the number of each is the same or the total area is the same, the difference in the influence of piezoelectric deformation hardly occurs, and the discharge variation can be reduced.

  In addition, the wiring 92b extends along the column direction, and a large number of wirings 92b are arranged in the row direction. In such a case, one of the two extraction electrodes 25b is electrically connected to the wiring 92b, and in the pressurizing chamber row 11, by alternately connecting the wiring 92b, the interval between the wirings 92 is increased. The width of the wiring 92b can be increased and the reliability can be increased.

  Seven wirings 92b are arranged between the connection electrode 26 at the position C1 and the connection electrode 26 at the position C3. Since the alternate connection is as described above, the arrangement is relatively generous. However, when the alternate arrangement is not performed, for example, the electrical connection is not the position of C2, but D1 which is the other extraction electrode 525b. If it carries out in the position of this, six wiring 92b will be arrange | positioned between the position of D1 and the position of C2, the width | variety of the wiring 92b will become narrow, and the space | interval of the wiring 92b will also become narrow. In such a design, the cost of the wiring board 92 is increased and the reliability is lowered. If the interval is too narrow, the design may not be possible. The alternate arrangement is particularly required in the wiring substrate 92 having the single layer 92b.

  6A, the connection electrode 26 is provided on the extraction electrode 25b that is electrically connected to the wiring 92b, and the dummy connection electrode is provided on the extraction electrode 25b that is not electrically connected to the wiring 92b. 27 is provided. Since the connection electrode 26 protrudes from the surface of the piezoelectric actuator substrate 21 and is a portion to which a force is applied when the piezoelectric actuator substrate 21 and the flow path member 4 are joined, a dummy connection electrode 27 having a similar shape is provided. As a result, the method of applying force can be made evenly and can be joined stably. Although the dummy connection electrode 27 may be provided at a place other than on the extraction electrode 25b, the provision of the dummy connection electrode 27 on the extraction electrode 25b suppresses a difference in thickness between the connection electrode 26 and the extraction electrode 25b. it can.

  FIGS. 6B and 7 are enlarged plan views of a liquid discharge head according to another embodiment of the present invention. The basic structure of the head main body is the same as that shown in FIGS. 2 to 5, and the individual electrodes 625 and 725 having differences will be illustrated and described.

  In FIG. 6B, the first and second extraction electrodes 625 b-1 and 625 b-2 extracted from the first region 10-1 and the second region 10-2 of the individual electrode 625 are either Are also drawn through the two acute angle portions of the pressurizing chamber 10, respectively. Here, the acute angle portion is a portion located between the straight sides of the rhombus-shaped pressurizing chamber 10 and being a corner between the two sides, or curved so as to round the corner. It is a part that is a curved line, and an angle formed by two sides is an acute angle (less than 90 degrees). It is only necessary that the extraction electrode 625b passes through the corner or a curved portion curved so as to round the corner. As shown in FIG. 9B, by bending the extraction electrode 625b before reaching the extreme end of the acute angle portion, the influence of crosstalk is reduced while reducing the displacement drop due to the piezoelectric deformation of the piezoelectric ceramic layer 21b immediately below the extraction electrode 625b. Can be reduced.

  In FIG. 7, the first extraction electrode 725 b-1 and the second extraction electrode 725 b-2 are substantially similar in shape to the pressurizing chamber 10 of the individual electrode 725, and the individual diamond-shaped individual having the same overall angle (inclination). It is pulled out in the row direction from the acute angle part of the electrode body. The acute angle portion of the individual electrode main body referred to here is the same as the acute angle portion of the pressurizing chamber 10 and is the extreme end in the longitudinal direction of the individual electrode main body that is substantially similar to the pressurizing chamber 10. In order to suppress a decrease in the amount of displacement due to the piezoelectric deformation immediately below the extraction electrode 725b, it is preferable to pull out from the acute angle portion of the pressurizing chamber 10. In this respect, the structure shown in FIGS. 6A and 6B, particularly the structure shown in FIG. On the other hand, in such a structure, since the length after being pulled out from the pressurizing chamber 10 becomes longer, the variation in the ejection characteristics affected by the piezoelectric deformation immediately below it increases. If the first extraction electrode 725b-1 and the second extraction electrode 725b-2 are extracted in the row direction from the acute angle portion of the individual electrode main body, the lengths of the first and second extraction electrodes 725b-1, 725b-2 are reduced. It can be shortened, and variation in ejection characteristics can be minimized. Next, crosstalk in the liquid discharge head 2 will be described in detail. As described above, the crosstalk in which the vibration of the pressurizing chamber 10 is transmitted through the flow path member 4 to the adjacent pressurizing chamber 10 is such that the rhombus-shaped pressurizing chamber 10 is in a lattice shape and the corners are opposed to each other. It can be reduced by arranging so as to.

  Crosstalk is further influenced by the arrangement of the extraction electrode 25b. In order to simplify the structure of the displacement element 30 or the manufacturing process of the piezoelectric actuator substrate 21, the piezoelectric ceramic layer 21b immediately below the extraction electrode 25b is polarized. When a voltage is applied to the individual electrode body 25a, the piezoelectric ceramic layer 21b is directly below the extraction electrode 25b. The piezoelectric ceramic layer 21 is also piezoelectrically deformed.

  The piezoelectric deformation of the piezoelectric ceramic layer 21 b immediately below the extraction electrode 25 b in the pressurizing chamber 10 affects the displacement amount of the displacement element 30. For example, when the piezoelectric ceramic layer 21b directly below the individual electrode body 25a is contracted in the plane direction and the displacement element 30 is bent and deformed toward the chamber 10, the piezoelectric ceramic layer 21b directly below the extraction electrode 25b in the pressurizing chamber 10 is also used. Since it contracts in the plane direction, the amount of displacement becomes small. By pulling out the extraction electrode 25b from the acute angle portion 10a of the pressurizing chamber 10b, the amount of decrease in displacement can be reduced. This is because, when the piezoelectric ceramic layer 21b immediately below the individual electrode main body 25a is deformed in the plane direction, the deformation occurs in the vicinity of the acute angle portion 10a. Therefore, even if the same deformation force is generated, the displacement amount of the displacement element 30 is Therefore, the decrease in the displacement amount as a result of combining with the displacement in the direction in which the displacement element 30 is originally deformed is reduced. On the other hand, when the extraction electrode 25b is pulled out in the middle of the rhombus-shaped side of the pressurizing chamber 10, the deformation of the portion is easy to displace the displacement element 30 and the displacement amount becomes large. The reduction in the displacement amount as a result of combining with the displacement in the direction to be deformed becomes large. For example, in the planar-shaped displacement element 30 shown in FIG. 8, when the extraction electrode 25b is extracted from the acute angle portion 10a, the displacement amount is reduced by about 1% when extracted from the middle of the side.

  In addition, since the piezoelectric ceramic layer 21b directly under the extraction electrode 25b drawn outside the pressurizing chamber 10 is also piezoelectrically deformed, the displacement of the adjacent displacement element 30 is affected. This influence is due to the transmission of vibrations, and since the piezoelectric ceramic layer 21b has a shape covering the plurality of pressurizing chambers 10, when the piezoelectric ceramic layer 21b directly below the extraction electrode 25b expands and contracts in the plane direction, This is due to stress applied to the piezoelectric ceramic layer 21b of the adjacent displacement element 30. The reduction of the crosstalk described below is particularly useful for the piezoelectric actuator substrate 21 in which the piezoelectric ceramic layer 21b is connected between the adjacent displacement elements 30.

  Next, the shape of the individual electrode 25 will be described using the individual electrode 25 on the lower center side in FIG. The extraction electrode 25b drawn from the acute angle portion 10a side of the individual electrode 25 needs to be pulled out to a position away from the pressurizing chamber 10 to some extent in order to secure a portion to be a terminal of a certain area for connection to the outside. is there. At this time, the other end portion of the extraction electrode 25b opposite to the one end portion connected to the individual electrode main body 25a is not overlapped with the row (imaginary line LB1) in which the diagonal line connecting the acute angle portions 10a is extended. Thus, since the distance between the adjacent displacement elements 30 on the acute angle portion 10a side can be increased, the crosstalk can be reduced. For this purpose, the extraction electrode 25b is bent and extracted from the column direction toward the row direction from when the extraction electrode 25b is extracted from the acute angle portion 10a. In FIG. 6, the extraction method of the extraction electrode 25b is bent by about 110 degrees, which is 90 degrees or more until the row direction is reached, but the bending angle may be smaller than 90 degrees or larger than 90 degrees. Also good.

  In particular, the extraction electrode 25b passes through the one acute angle portion 10a of the pressurization chamber 10 from which the extraction electrode 25b is extracted, and is on a virtual line LA1 parallel to a diagonal line connecting the obtuse angle portions 10b of the pressurization chamber 10 or the virtual line LA1. By disposing on the pressurizing chamber 10 side of the line LA1, the distance between the extraction electrode 25b and the pressurizing chamber 10 adjacent on the acute angle portion 10a side can be increased, so that the crosstalk can be reduced. More specifically, when the distance from the pressurizing chamber 10 adjacent on the acute angle portion 10a side is compared, the other end portion of the extraction electrode 25b (the leading end of the extraction electrode 25b, which is normally a terminal). When the same shape S (circular in this case) is arranged at the tip of the acute angle portion 10a, the entire extraction electrode 25b is arranged at the acute angle portion 10a rather than the portion closest to the pressurizing chamber 10 adjacent to the acute angle portion 10a of the shape S. Crosstalk can be reduced by making it farther from the pressurizing chamber 10 adjacent on the side. This is a state where the distance from the pressurizing chamber 10 adjacent to the extraction electrode 25b on the acute angle portion 10a side is larger than that in the case where a terminal is provided in the immediate vicinity of the acute angle portion 10a of the pressurizing chamber 10 (than LA2). In other words, the crosstalk can be reduced by setting the drawer closer to the pressure chamber 10 side.

  The extraction electrode 25b is formed in a region closer to the pressurization chamber 10 from which the extraction electrode 25b is extracted than the adjacent pressurization chamber 10 on the obtuse angle portion 10b side of the pressurization chamber 10 from which the extraction electrode 25b is extracted. By doing so, crosstalk with the displacement element 30 adjacent on the obtuse angle portion 10b side can be reduced. More specifically, the phantom line LB2 parallel to the diagonal line passing through the obtuse angle part 10b of the original pressurizing chamber 10 from which the extraction electrode 25b is drawn out and connecting the acute angle parts 10a, and the obtuse angle part When considering the virtual line LB3 parallel to the virtual line LB2 that passes through the obtuse angle part 10b of the adjacent pressurizing chamber 10 that faces 10b, the extraction electrode 25b is more than the virtual line LB4 in the middle of these virtual lines. That is, it is arranged in a region close to the pressurizing chamber 10 as the drawer.

  FIG. 9 is a plan view further enlarging FIG. The individual electrode 25, when viewed in plan, is an individual electrode body 25a housed in the pressurizing chamber 10 and the first and second lead electrodes 25b− that are led out of the pressurizing chamber 10 from the individual electrode 25a. 1, 25b-2.

  The individual electrode main body 25a has a rhombus shape having two acute angle portions 25aa and two obtuse angle portions 425ab. The line connecting the two acute angle portions 25aa of the individual electrode main body 25a coincides with the line connecting the two acute angle portions 10a of the pressurizing chamber 10 in angle and position. The line connecting the two obtuse angle portions 25ab of the individual electrode main body 25a coincides with the line connecting the two obtuse angle portions 10b of the pressurizing chamber 10 in angle and position. Thereby, the displacement amount of the displacement element 30 can be enlarged. The position of each line may be shifted by 10% or less of the maximum width of the pressurizing chamber 10, and the angle may be shifted by 10 degrees or less. Moreover, the amount of displacement can be increased by setting the area of the individual electrode body 25a to 50 to 90%, more preferably 60 to 80% of the area of the pressurizing chamber 10.

  The first and second extraction electrodes 25b-1 and 25b-2 (hereinafter sometimes collectively referred to as extraction electrodes 25b) are connected to the individual electrode main body 25a and one acute angle portion 25a. The connected portion is located at the acute angle portion 10 a of the pressurizing chamber 10. The extraction electrode 425b is bent outside the acute angle portion 10a (a region that does not overlap the pressurizing chamber 10), that is, bent at an angle greater than 90 degrees and less than 180 degrees, from which the connection electrode 26 or dummy connection is formed. Up to the end where the electrode 27 is formed is a straight linear portion 25ba. As a result, the end portion of the extraction electrode 425ba is closer to the individual electrode body 25a that is being extracted than the acute angle portion 10a of the pressurizing chamber 10 that is the extraction source in the column direction. Thereby, the distance with the other pressurization room 10 located in a line direction can be separated, and crosstalk can be reduced.

  Next, the angle of the linear portion 25ba will be described. Let C be the angle of the straight line 25ba (the virtual straight line LC is a line extended at the same angle as the straight line 25ba) and the virtual straight line LA3 extending in the row direction. The virtual straight lines extending two sides of the rhombus shape sandwiching the acute angle portion 425aa of the extraction electrode 425a to which the extraction electrode 25b is connected are LD1 and LD2, and the angle formed by these and the virtual line LA3 extending in the row direction. Are D1 and D2, respectively. The angles C, D1, and D2 are acute angles and are 90 degrees or less.

  The value of the angle D1 + the angle D2 is 90 degrees or more because the acute angle portion 25aa is an acute angle. The angle D1 and the angle D2 do not have to be the same. That is, the angle of the line connecting the rhombic acute angle portion 25aa and the line connecting the obtuse angle portion 25ab of the individual electrode main body 25a may be shifted from the row direction and column direction angles of the pressurizing chamber 10. If the angle deviation is 20 degrees or less, the pressure chambers 10 adjacent to each other in the column direction do not face each other, so that crosstalk can be reduced.

  By setting the angles D1 and D2 to 55 to 75 degrees, the size in the row direction can be reduced while increasing the amount of displacement. Therefore, the arrangement in the row direction can be made high density so as to increase the printing resolution. it can. By making the angle C smaller than the angles D1 and D2, the formation accuracy of the linear portion 25ba can be increased, and variations in ejection characteristics due to variations in formation position and resistance values that may occur due to variations in formation, and It is difficult to cause disconnection.

  The individual electrode 25 is preferably formed by firing a screen-printed conductor paste because it is inexpensive and increases productivity. Screen printing is performed by attaching a mesh woven in a grid of metal wires to a rectangular frame, forming an opening in the resist attached to the mesh, and extruding the conductive paste from the opening with a squeegee. To do. When such printing is performed, the thickness of the individual electrode 25 corresponding to the opening is increased in a lattice shape, or the outer periphery of the individual electrode 25 is slightly shifted in the lattice shape.

  In screen printing, if the length of contact between the printing object and the squeegee through the screen changes while the squeegee moves, or the position of the screen relative to the screen frame changes, the printing conditions change, and the printing state varies. Basically, the squeegee moves in parallel with the frame of the screen, and the print object has a small change in the width in the moving direction of the screen. In addition, when the printing is repeated when the angle of the grid-like mesh with respect to the frame of the screen is 0 degree, the influence of the screen being shifted in the printing direction due to the squeegee increases, so that the angle is given to some extent.

  In printing, the portion where the wire is present is printed by supplying the conductor paste from the surroundings without directly supplying the conductor paste. For this reason, when the angle of the outer periphery of the conductor pattern and the angle of the wire are close, and the position is also close, the conductor paste is supplied only from the wire side, so the shape of the conductor pattern is likely to vary. Therefore, it is preferable to adjust the mesh angle so that the printing accuracy of the outer periphery of the individual electrode main body 25a, which particularly requires positional accuracy, is improved.

  The mesh angle is preferably different so that the rhombus-shaped side angle of the individual electrode body 25a does not coincide with the angles D1 and D2. That is, the angles of the wires perpendicular to each other of the mesh are preferably larger than the angle (90-D1) and the angle (90-D2), and smaller than the angles D1 and D2, and preferably 45 degrees. The angle C of the linear portion 425ba is preferably increased so that the linear portion 25ba is separated from the adjacent pressurizing chamber 10 and the crosstalk is reduced. The linear portion 25ba may have a lower formation accuracy than the individual electrode main body 425a. Therefore, by setting the angle C to (90-D1) degrees and (90-D2) degrees or more, Crosstalk can be reduced. On the other hand, if it exceeds 45 degrees, the formation accuracy deteriorates. A more preferable range of the angle C is 5 degrees or more larger than (90-D1) degrees and (90-D2) degrees, and 5 degrees smaller than 45 degrees, and 95-D1 ≦ C and 95-D2 ≦. C, C ≦ 40 degrees.

  The liquid discharge head 2 as described above is manufactured as follows, for example. A tape composed 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 was printed on the surface of the fired piezoelectric actuator body by screen printing, and fired to form 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. Printing was performed while 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 was mounted by electrically flip-chip connecting the FPC to the FPC with solder, and then supplying a protective resin around the solder and curing it.

  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, whereby the liquid discharge head 2 is 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 portion 10-1 .. First region (region overlapping the common flow path)
10-2 .. Second area (area not overlapping with common flow path)
DESCRIPTION OF SYMBOLS 11 ... Pressurization room line 12 ... Individual flow path 14 ... Individual supply flow path 15 ... Bulkhead 21 ... Piezoelectric actuator substrate 21a ... Piezoelectric ceramic layer (vibration plate)
21b: Piezoelectric ceramic layer 24: Common electrode 25, 625, 725 ... Individual electrode 25a, 425a, 625a, 725a ... Individual electrode body 25aa ... (individual electrode body) acute angle portion 25ab .. Obtuse angle part (b) of individual electrode body 25b... Extraction electrode 25ba... Linear part 25b-1, 625b-1, 725b-1... First extraction electrode 25b-2, 625b-2, 725b-2 ... second extraction electrode 26,626,726 ... connection electrode 27,627,727 ... dummy connection electrode 28 ... surface electrode for common electrode 30 ... displacement element (pressurization) Part)
92 ... Signal transmission part (wiring board)
92b wiring

Claims (7)

A plurality of discharge holes, a plurality of pressurizing chambers connected to the plurality of discharge holes, and a flow path member having one or a plurality of common flow paths connected to the plurality of pressurization chambers;
A piezoelectric actuator substrate laminated on the flow path member so as to cover the plurality of pressurizing chambers;
A liquid discharge head comprising a wiring board,
In the piezoelectric actuator substrate, a first electrode, a piezoelectric body, and a plurality of second electrodes are laminated in this order from the flow path member side,
When the liquid discharge head is viewed in plan view,
Each of the plurality of pressurizing chambers has a rhombus shape having two obtuse angle parts and two acute angle parts, and connects the two acute angle parts on a line along a diagonal line connecting the two obtuse angle parts. Are arranged at substantially equal intervals on the rows along the diagonal line,
The common flow path extends along the row direction, and is connected to the pressurizing chamber arranged in a row on both sides of the common flow path,
Each of the pressurization chambers connected to the common flow path has a first region that overlaps with the common flow path and a second region that does not overlap with the common flow path,
The plurality of second electrodes are arranged so as to overlap with the plurality of pressurizing chambers, respectively, and an electrode body housed inside the pressurizing chamber and the electrode having one end portion in the first region The other end is connected to the main body, the other end is drawn to the outside of the pressurizing chamber, and the other end is connected to the electrode main body in the second region, the other end A second extraction electrode whose portion is extracted to the outside of the pressurizing chamber,
The wiring board is electrically connected to either the first extraction electrode or the second extraction electrode of the second electrode, and is alternately connected in the row direction. A liquid discharge head characterized by comprising: When the liquid discharge head is viewed in plan view,
2. The liquid ejection head according to claim 1, wherein the other end portions of the first and second extraction electrodes are extracted to a region that does not overlap the row.   The liquid discharge head according to claim 1, wherein the first and second extraction electrodes are extracted from the acute angle portion.   When the liquid discharge head is viewed in plan, the first and second extraction electrodes extend in the row direction from the one acute angle portion of the pressurizing chamber from which the extraction electrode is extracted, The other end is provided on a virtual line parallel to the row passing through the one acute angle part or on the pressurizing chamber side with respect to the virtual line. Liquid discharge head. When the liquid discharge head is viewed in plan, the electrode body has a rhombus shape, and the first and second extraction electrodes have linear portions extending from the outside of the acute angle portion to the other end portion. And the direction toward the other end of the linear portion is the direction toward the electrode body from which the extraction electrode is extracted in the column direction,
The angle formed between the linear portion and the row direction is C degrees, and the angle formed between each of the two sides of the second electrode sandwiching the portion from which the extraction electrode is drawn and the row direction is D1 degrees. The liquid discharge head according to claim 1, wherein 90−D1 ≦ C, 90−D2 ≦ C, and C ≦ 45 degrees when D2 and D2 degrees are set. When the liquid discharge head is viewed in plan view,
The shape of the electrode body is a rhombus shape similar to the pressurizing chamber, and the first extraction electrode and the second extraction electrode are extracted from the acute angle portion of the electrode body in the row direction. The liquid discharge head according to claim 1, wherein the liquid discharge head is a liquid discharge head.   A liquid discharge head according to claim 1, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the piezoelectric actuator substrate. Recording device.

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