JP2013176881A - Liquid ejection head, and recording apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejection head with high connection reliability by means of a flexible substrate, and a recording apparatus using the liquid ejection head.SOLUTION: A liquid ejection head includes: a liquid ejection head body 2a including a plurality of ejection holes, a plurality of pressure chambers and a plurality of pressure parts; a circuit board 82; a belt-like flexible substrate 60, one end of which is electrically connected to the plurality of pressure parts, and the other end of which is electrically connected to the circuit board 82; a driver IC 55 mounted on the flexible substrate 60; and a housing 90. The driver IC 55 is pressurized to the inside of the housing 90, and the flexible substrate 60 includes a curved part 60a curved toward the inside of the housing 90 from the location on which the driver IC55 is mounted toward the other end side, besides, a reinforcing plate 62 is attached on the flexible substrate 60 to be positioned closer to the other end side than the curved part 60a.

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, in such a liquid discharge head, a serial type that performs recording while moving the liquid discharge head in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium, and main scanning from the recording medium There is a line type in which recording is performed on a recording medium conveyed in the sub-scanning direction with a liquid discharge head that is long in the direction 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.

  In order to print droplets at a high density in any of the serial type and line type liquid discharge heads, the density of the liquid discharge holes for discharging the droplets formed in the liquid discharge head must be increased. There is a need to.

  Therefore, the liquid discharge head main body is provided so as to cover the manifold (common flow path) and the flow path member having the liquid discharge holes connecting the manifold through the plurality of liquid pressurization chambers, respectively, and the liquid pressurization chamber. It is known that the actuator unit having a plurality of displacement elements is laminated (see, for example, Patent Document 1). In this liquid discharge head main body, the liquid pressurizing chambers respectively connected to the plurality of liquid discharge holes are arranged in a matrix shape, and the displacement elements of the actuator unit provided so as to cover the liquid pressurization chambers are displaced, so that each liquid discharge hole Ink can be discharged from. There are four actuator units, and the four flexible boards that transmit drive signals to them are alternately pulled out to the left and right of the liquid discharge head body, passing between the liquid discharge head body and the housing, It is connected to a connector disposed on the upper part of the liquid discharge head body. In addition, a driver IC is mounted on the flexible substrate, and the driver IC is sandwiched between the liquid discharge head main body and the housing, and is exhausted through the casing.

JP 2007-307801 A

However, in the liquid ejection head described in Patent Document 1, the flexible substrate on which the driver IC pressed against the housing is mounted is bent toward the inside of the housing when connected to the drive signal supply source. Become. Then, when the liquid discharge head is manufactured, the connection between the flexible substrate and the driver IC on the side where the flexible substrate is bent may be cut off.

  Accordingly, an object of the present invention is to provide a liquid discharge head having a high connection reliability by a flexible substrate and a recording apparatus using the same.

  A liquid discharge head according to the present invention includes a plurality of discharge holes, a plurality of pressurization chambers connected to the plurality of discharge holes, and a plurality of pressurization units that pressurize the liquid in the plurality of pressurization chambers, respectively. The discharge head main body, a circuit board to which signals for controlling the plurality of pressurizing units are input from the outside, and a strip shape, one end of which is electrically connected to the plurality of pressurizing units, and the other end A flexible board electrically connected to the circuit board, one or a plurality of driver ICs mounted on the flexible board, and attached to the liquid discharge head main body, and the circuit board and the flexible board inside A liquid discharge head including a substrate and a housing in which the driver IC is housed, wherein the driver IC is pressed against the inside of the housing; The board has a curved portion that is curved toward the inside of the housing from the portion where the driver IC is mounted toward the other end side, and the other end from the curved portion in the flexible substrate. A reinforcing plate is attached to the side.

  The flexible substrate is branched into a plurality at the branch portion on the other end side from the portion where the driver IC is mounted, and the reinforcing plate is attached to the driver IC side from the branch portion or the branch portion. It is preferable.

  It is preferable that the width of at least a part of the wiring of the flexible substrate is thick at the curved portion.

  A plurality of the driver ICs are pressed against the housing by an elastic plate, and the elastic plate is branched on the driver IC side in the same number as the driver IC side. It is preferable that each of the driver ICs is pressed against the casing.

  It is preferable that a heat conductive material is filled between the driver IC and the housing.

  The heat conductive material is fluid, the pressurizing portion is a displacement element, and the flexible substrate extends toward the displacement element from a portion of the housing where the driver IC is pressed. It is preferable that the housing has a concave portion or a convex portion so as to prevent the heat conductive material from flowing.

  Further, the recording apparatus of the present invention is connected to the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and the connection portion of the liquid discharge head, and And a controller for controlling the liquid discharge head body, which is electrically connected to the liquid discharge head body.

  According to the liquid ejection head of the present invention, the flexible board near the curved portion is pushed toward the part where the driver IC is mounted by the reinforcing plate, so the flexible board and the driver IC at that part are placed. Therefore, the connection reliability between the flexible board and the driver IC can be increased.

1 is a schematic configuration diagram of a printer that is a recording apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of a liquid discharge head body that constitutes the liquid discharge 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 a diagram in which a part of the structure is omitted for explanation. 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. FIG. 2 is a perspective view of the liquid ejection head in FIG. 1. FIG. 7 is a longitudinal sectional view of the liquid discharge head of FIG. 6 taken along line XX. (A) is a schematic plan view of one Embodiment of the flexible substrate used for this invention, (b) is a schematic plan view on the opposite side to (a), (c) is used for this invention. It is a top view of one Embodiment of the elastic board manufactured.

  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 ejection head 2 is arranged with a slight gap between the lower surface of the head main body 2 a 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 (liquid ejection) head body 2a. FIG. 3 is an enlarged view of a region surrounded by a one-dot chain line in FIG. 2, and is a plan view in which a part of the structure is omitted for explanation. 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 structure different from FIG. 3 is omitted for explanation. 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. Further, the discharge hole 8 in FIG. 4 is drawn larger than the actual diameter for easy understanding of the position. FIG. 5 is a longitudinal sectional view taken along line VV in FIG.

  FIG. 6 is a perspective view of the liquid discharge head of FIG. FIG. 7 is a vertical cross-sectional view of the liquid discharge head of FIG. 6 taken along the line XX. In FIG. 7, the internal structure of the flow path such as the flow path member 4 is omitted. FIG. 8A is a schematic plan view of a flexible substrate used in the present invention on a side where a reinforcing plate 62 is attached, and FIG. 8B is a schematic plan view on the side opposite to FIG. It is a figure and (c) is a top view of one Embodiment of the elastic board used for this invention.

  The liquid discharge head 2 includes a (liquid discharge) head body 2, a reservoir 40, a connection substrate 80, a circuit substrate 82, a flexible substrate 60, a driver IC (Integrated Circuit) 55 mounted on the flexible substrate 60, and a housing. A body 90. The housing 90 is made of metal or the like and has a rectangular parallelepiped shape. The casing 90 is composed of a casing main body 90a constituting the top plate and side surfaces on both ends in the longitudinal direction of the liquid discharge head 2, and a casing side plate 90b attached to the casing main body 90a. A hole is opened in the top plate portion of the housing main body 90a so that a signal can be input via the external connector 80a of the connection board.

  Between the housing 90 and the reservoir 40 is a frame 92 having a hole in the center on a flat plate. The casing body 90a is attached to the guide frame 88 with screws or the like at the top plate portion, and the chassis side plate 90b is attached to the casing body 90a from the sides with screws or the like. At this time, the driver IC 55 that has been previously pushed outward from the attachment position of the housing side plate 90b is pressed against the housing side plate 90b. An opening formed by the frame 92, the reservoir 40, and the flow path member 4 below the frame 92 is closed by attaching the side plate 94 with screws or the like. Between the above members, resin or the like is applied and cured as necessary, so that liquid mist does not easily enter the inside of the housing 90.

  The connection substrate 80 may not be provided, but is preferably provided so that liquid mist or the like does not enter the housing 90 beyond the connection substrate 80. An external connector 80a, which is a connection portion, connected to an external wiring is mounted on a surface (hereinafter sometimes referred to as an outer surface) of the connection substrate 80 facing the housing 90. The presence of the external connector 80a facilitates connection to the control unit 100. The external connector 80a is mounted through-hole and connected to the wiring 80c formed on the inner surface of the housing 90 of the connection substrate 80 (hereinafter sometimes referred to as the inner surface). Since the number of wirings can be reduced on this surface, it is possible to suppress such wiring from being short-circuited by droplets. By placing resin between the external connector 80a and the connection board 80, it is possible to suppress the occurrence of a short circuit in the vicinity of the lower part of the external connector 80a or the through hole on the outer surface side of the connection board 80.

  An internal connector 80 b is mounted on the wiring 80 c on the inner surface of the connection board 80. If the internal connector 80b is surface-mounted, the wiring on the outer surface of the connection substrate 80 can be reduced, so that it is possible to prevent such wiring from being short-circuited by droplets. The connection board 80 is electrically connected to the circuit board 82 by the internal connector 80b and is also mechanically fixed.

The reservoir 40 is provided with a reservoir channel. One end of the reservoir channel is opened to the outside of the liquid discharge head 2 as a liquid supply hole 40a. Further, the reservoir 40 is connected at both ends in the longitudinal direction of the flow path member 4, and the reservoir flow path is connected to the opening 5a of the manifold at both of them. That is, the liquid supplied from the liquid supply hole 40 a enters the reservoir flow path, branches inside, and is supplied to both ends of the manifold 5.

  Further, a part of the inner wall of the reservoir channel is a damper made of an elastically deformable material. Since the damper can be deformed in the direction facing the surface opposite to the reservoir flow path, the damper can be elastically deformed to change the volume of the reservoir flow path, and the liquid discharge amount increases rapidly. In this case, the liquid can be supplied stably. In addition, it is preferable to provide a filter in the reservoir flow path so that foreign matter contained in the liquid does not easily enter the flow path member 4 and can suppress non-ejection caused by clogging of foreign matter.

  In addition, an elastic plate 96 provided with a heat insulating member 98 and a guide frame 84 for fixing a circuit board 82 for processing a drive signal for discharging liquid from the housing 90a and the head body 2a are fixed to the reservoir 40. Has been. A drive signal sent from the control unit 100 via a signal cable (not shown) is an external connector 80a, a connection board 80, an internal connector 80b, a circuit board 82, a flexible board 60, and a driver IC 55 mounted on the flexible board 60. Then, a displacement element 30 of a piezoelectric actuator substrate 21 to be described later is driven to pressurize the liquid in the flow path member 4, thereby discharging a droplet. For example, the circuit board 82 may rectify the drive signal in addition to dividing the drive signal into the plurality of piezoelectric actuator boards 21. The flexible substrate 60 is a strip having flexibility, and has a metal wiring 61 inside, and a part of the wiring 61 is exposed on the surface of the flexible substrate 60, and the circuit substrate 82 is exposed by the exposed wiring. The driver IC 55 and the piezoelectric actuator substrate 21 are electrically connected.

  The driver IC 55 generates heat when processing the drive signal. Since the driver IC 55 is pressed against the housing 90 by deflecting the elastic plate 96, the generated heat is mainly transmitted to the housing 90, and further spreads quickly throughout the housing 90 and is radiated to the outside. If the driver IC 55 is flip-chip mounted and the surface opposite to the surface on which the electrodes are disposed is brought into contact with the housing 90, heat can be easily transmitted. The casing side plate 90b is preferably made uneven on the outer surface so as to promote heat dissipation. The heat insulating member 98 makes it difficult for heat to be transmitted to the reservoir. The heat insulating member 98 may also be made elastic to help press the driver IC 55 against the metal housing 90.

  In the case where the elastic plate 96 presses the plurality of driver ICs 55, the elastic plate 96 can be pressed almost evenly on each driver IC when the elastic plate 96 has a branched shape as shown in FIG. 8C. . FIG. 8C is a side view of the elastic plate 96, and the lower side of the figure is bent in an L shape and joined to the reservoir 40. The upper side of the figure branches into four, which is the same as the number of driver ICs, and the four driver ICs at the branch destinations can be pressed against the housing 90 respectively. Since the side joined to the reservoir 40 is integrated, it is preferable that the elastic plate for pressing the plurality of driver ICs 55 can be integrated into one and can be attached once. Even if there is a variation in the height of the driver IC 55 and its mounting portion, the driver IC 55 is pressed at the branching point, so that the pressing is partially insufficient and the heat conduction is unlikely to deteriorate.

Further, when the heat conduction material is filled between the driver IC and the housing 90, the area in contact with the heat conduction material is increased, so that the heat conductivity is further increased. Examples of the heat conductive material include thermally conductive high-viscosity grease and a resin containing a high heat conductive filler. The resin may have a certain degree of viscosity or may be cured. The heat conductive material having a fluid state is easier to increase the contact area, but there is a possibility that the heat conductive material flows during use to cause problems. For example, in the case of the displacement element 30 in which the pressurizing portion is displaced, there is a fear that the amount of displacement may be reduced if a fluid heat conductive material is attached to the displacement element 30. In such a case, if a concave portion or a convex portion is provided on the casing 90 on the side where the flexible substrate 60 extends to the displacement element 30 from the portion where the driver IC 55 is mounted, the heat conductive material is moved to the displacement element 30 side. Flow can be suppressed. The frame 92 is a convex portion that fulfills this role.

  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 includes a manifold 5, a plurality of pressure chambers 10 connected to the manifold 5, and a plurality of discharge holes 8 respectively connected to the plurality of pressure chambers 10. It opens to the upper surface of the path member 4, and the upper surface of the flow path member 4 serves as the 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.

  Further, a piezoelectric actuator substrate 21 including a displacement element 30 that is a pressurizing unit 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 pressurization chamber 10. . Further, a flexible substrate 60 for supplying a signal to each displacement element 30 is electrically connected to the piezoelectric actuator substrate 21. In FIG. 2, the outline of the vicinity of the flexible substrate 60 connected to the piezoelectric actuator substrate 21 is indicated by a dotted line so that the two flexible substrates 60 are connected to the piezoelectric actuator substrate 21. The electrode of the wiring 61 formed on the flexible substrate 60 that is electrically connected to the piezoelectric actuator substrate 21 is arranged in a rectangular shape in a connection region 60c with the piezoelectric actuator substrate at one end of the flexible substrate 60. ing. The two flexible substrates 60 are connected such that their ends come to the center of the piezoelectric actuator substrate 21 in the short direction. The two flexible substrates 60 extend from the central portion in the short direction toward the long side of the piezoelectric actuator substrate 21.

  A driver IC 55 is mounted on the flexible substrate 60. A drive signal for driving the displacement element 30 on the piezoelectric actuator substrate 21 is finally generated in the driver IC 55 based on an external signal. A signal for controlling generation of the drive signal is generated by the control unit 100 and input from the circuit board 82 side of one end of the belt-like flexible substrate 60, and the drive signal generated by the driver IC 55 is connected to the other end. Output to the piezoelectric actuator substrate 21.

  Since the driver IC 55 is pressed against the housing 90, the flexible substrate 60 is connected to the circuit board 82 inside the housing 90, so that the housing 90 is closer to the circuit board 82 than the portion where the driver IC 55 is mounted. It has a curved portion 60a that bends inside. A (first) reinforcing plate 62 is attached to the circuit board 82 side from the curved portion 60a. The flexible substrate 60 is pressed against the driver IC 55 side by the elasticity of the reinforcing plate 62 and the curved portion, so that it is difficult for stress to be peeled off to the curved portion 60a side of the connection between the flexible substrate 60 and the driver IC 55 side. , Can improve the reliability of the connection. For this purpose, the angle θ formed by the reinforcing plate 62 and the driver IC is made larger than 0 degree and smaller than 180 degrees. If θ is smaller than 90 degrees, the effect that the flexible substrate 60 is pressed against the driver IC 55 becomes stronger.

  The flexible board 60 is difficult to handle because the number of wirings on the pressure part side is several hundred or more, more than one thousand, and the width is 5 cm or more, but the reinforcing plate 62 is difficult to handle. Therefore, when the circuit board 82 side is attached, it becomes easy to handle the flexible board 60 integrally, and it is difficult to cause damage.

Since the wiring on the circuit board 82 side of the flexible substrate 60 is also several tens or more, if it is electrically connected continuously to one part, high formation accuracy and high thermal expansion coefficient matching are required. Therefore, it is preferable to make the connection divided into a plurality of parts (for example, connection with a plurality of connectors). In that case, the flexible substrate 60 is easier to handle if it is branched. In that case, by attaching the reinforcing plate 60a to the branching portion 60b that branches, or by attaching the reinforcing plate 60a to the driver IC 55 side from the branching portion 60b, the flexible substrate 60 can be prevented from tearing from the branching portion 60b or the progress of the splitting. In order to attach the reinforcing plate 62 to the branching portion 60b, after attaching the reinforcing plate 62, the flexible substrate 60 is cut together with the reinforcing plate 62 to form the branching portion 60, or the flexible substrate 60 is cut and the branching portion 60b is cut. After forming the reinforcing plate 62, the reinforcing plate 62 may be attached so as to cover it. When the reinforcing plate 62 and the branching portion 60b do not overlap, if the wiring 61 is not provided therebetween, disconnection can be suppressed even if the flexible substrate 60 is torn.

  A second reinforcing plate 64 is attached to a connection region 60d of the circuit board 82 which is an end portion electrically connected to the connector 82a of the circuit board 82 of the flexible board 60. The second reinforcing plate 64 is preferably attached to the same side as the first reinforcing plate 62 because the attaching process can be performed once. It is preferable that the electrodes in the connection region 60c with the piezoelectric actuator substrate and the connection region 60d with the circuit substrate are connected on the same surface, because the manufacture of the flexible substrate is simplified. The second reinforcing plate 64 is attached to the opposite side of the connection region 60d with the circuit board.

  FIG. 8B schematically shows a part of the wiring 61, but is almost omitted. The width of the signal wiring is reduced to about 20 to 100 μm. If the width of the ground wiring or the like is increased in the curved portion 60a from the periphery, the rigidity of the curved portion 60a is increased, and the effect of pressing the flexible substrate 60 toward the driver IC 55 can be increased. The hatched portion of the wiring 61 in FIG. 60B exemplifies the wiring 61 having a wider width than the surroundings.

  Next, the head main body 2a will be described. 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. The whole may be partitioned by the partition 15 including both ends. In that case, if 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 is provided from the opening 5a in the depth direction of the flow path member 4, the reservoir Connection with 40 becomes easy.

  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 rows of pressurizing chambers 11 which are rows of pressurizing chambers 10 connected to the sub-manifold 5b are provided, one on each side of the sub-manifold 5b. Yes. Accordingly, 16 rows of pressurizing chambers 11 are provided for one manifold 5, and 32 rows of pressurizing chamber rows 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. A dummy pressurizing chamber row in which dummy pressurizing chambers 16 are arranged in a straight line is provided outside the 32 pressurizing chamber rows 11. 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 the same direction as the diagonal line connecting the obtuse angle portions 10b of the rhombus-shaped pressurizing chamber 10, and the column direction is the same direction as the diagonal line connecting the acute angle portions 10a of the rhombus-shaped pressurizing chamber 10. That is, the rhombus-shaped diagonal line of the pressurizing chamber 10 is not in an angle with the rows and columns. 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 it is difficult for vibration to be transmitted through 4. In this case, the obtuse angle portions 10b are opposed to each other in the longitudinal direction so that the density of the pressurizing chamber 10 in the longitudinal direction can be increased, thereby increasing the density of the discharge holes 8 in the longitudinal direction. This is because a high-resolution liquid ejection head 2 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 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 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 rows of 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. Therefore, the accuracy of the installation angle of the liquid discharge head 2 with respect to the printer 1 and the use of a plurality of liquid discharge heads 2 are used. 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 discharge hole row 9 is configured. The discharge holes 8 connected to the pressurizing chambers 10 belonging to the two pressurizing chamber rows 11 are opened on different sides of the sub manifold 5b. In FIG. 4, the partition wall 15 is provided with two rows of discharge holes 9. The discharge holes 8 belonging to each of the discharge hole rows 9 are connected to the sub-manifold 5 b on the side close to the discharge holes 8 in the pressurizing chamber 10. Are connected through. If the discharge hole 8 connected to the adjacent sub-manifold 5b via the pressurizing chamber row 11 and the liquid discharge head 2 do not 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 an interval of 1200 dpi as a whole, while the pressurization chambers 10 are arranged in a lattice shape in which the intervals in the respective 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 via a via hole. The common electrode surface electrodes 28 are formed in two rows along the longitudinal direction at the central portion of the piezoelectric actuator substrate 21 in the lateral direction, and are formed in one row along the lateral 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 flexible substrates 60 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 that 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 flexible substrate 60 (the front end and the end in the longitudinal direction of the piezoelectric actuator substrate 21). Since the connection can be made stronger by the connection on the common electrode surface electrode 28, the flexible substrate 60 can be hardly peeled 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. As described above, 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, and the extraction electrode 25b extracted therefrom. 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. Further, the connection electrode 26 is electrically joined to an electrode provided on the flexible substrate 60. Although details will be described later, a drive signal is supplied to the individual electrode 25 from the control unit 100 through the flexible substrate 60. 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 flexible substrate 60 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 flexible substrate 60 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, and the pressure in the pressurizing chamber 10 is reduced by the volume reduction of 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.

  In the present embodiment, the displacement element 30 using piezoelectric deformation is shown as the pressurizing portion. However, the present invention is not limited to this, and any other device that can pressurize the liquid in the liquid pressurizing chamber 10 may be used. For example, the liquid in the liquid pressurizing chamber 10 may be heated and boiled to generate pressure, or may be one using MEMS (Micro Electro Mechanical Systems).

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... (Liquid discharge) head main body 4 ... Channel member 4a-l ... (Channel member) plate 5 ... Manifold 5, ... -Manifold 5a ... (manifold) opening 5b ... Sub-manifold 6 ... Squeeze 8 ... Discharge hole 9 ... Discharge hole row 10 ... Pressurizing chamber 11 ... Pressurizing chamber row DESCRIPTION OF SYMBOLS 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 30: Displacement element (pressure unit)
32 ... Individual channel 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 40 ... Reservoir 40a ... (Reservoir) liquid supply hole 55 ... Driver IC
60 ... flexible substrate 60a ... curved portion 60b ... branching portion 60c ... connection region with piezoelectric actuator substrate 60d ... connection region with circuit substrate 61 ... wiring (of flexible substrate) 62 ... (first) reinforcing plate 64 ... second reinforcing plate 80 ... connection board 80a ... (connecting board) external connector 80b ... (connection board) internal connector 80c ...・ Wiring (of connection board) 82... Circuit board 82 a... (Circuit board) connector 84... Guide frame 90. ..Frame 94 ... Side plate 96 ... Elastic plate 98 ... Heat insulation member

Claims (7)

A liquid discharge head body having a plurality of discharge holes, a plurality of pressurization chambers connected to the plurality of discharge holes, and a plurality of pressurization units that pressurize the liquid in the plurality of pressurization chambers, respectively.
A circuit board to which signals for controlling the plurality of pressurizing units are input from the outside;
A flexible substrate having a strip shape, one end electrically connected to the plurality of pressure units, and the other end electrically connected to the circuit board;
One or more driver ICs mounted on the flexible substrate;
A liquid discharge head that is attached to the liquid discharge head main body and includes a housing in which the circuit board, the flexible substrate, and the driver IC are housed;
The driver IC is pressed against the inside of the housing,
The flexible substrate has a curved portion that is curved toward the inside of the housing from a portion where the driver IC is mounted toward the other end side, and the flexible substrate is more flexible than the curved portion of the flexible substrate. A liquid discharge head, wherein a reinforcing plate is attached to the other end side.   The flexible substrate is branched into a plurality at the branch portion on the other end side from the portion where the driver IC is mounted, and the reinforcing plate is attached to the driver IC side from the branch portion or the branch portion. The liquid discharge head according to claim 1, wherein the liquid discharge head is provided.   The liquid discharge head according to claim 1, wherein a width of at least a part of the wiring of the flexible substrate is thick at the curved portion.   A plurality of the driver ICs are pressed against the housing by an elastic plate, and the elastic plate is branched on the driver IC side in the same number as the driver IC side. The liquid ejection head according to claim 1, wherein each of the driver ICs is pressed against the casing.   The liquid discharge head according to claim 1, wherein a heat conductive material is filled between the driver IC and the housing.   The heat conductive material is fluid, the pressurizing portion is a displacement element, and the flexible substrate extends toward the displacement element from a portion of the housing where the driver IC is pressed. The liquid discharge head according to claim 5, wherein the casing has a concave portion or a convex portion so as to prevent the flow of the heat conductive material.   The liquid discharge head according to any one of claims 1 to 6, a transport unit that transports a recording medium to the liquid discharge head, and the connection portion of the liquid discharge head, and connected via the connection substrate A recording apparatus comprising: a controller that controls the liquid discharge head main body and is electrically connected to the liquid discharge head main body.

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