JP6166419B2 - 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, 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 piezoelectric actuator substrate having a plurality of displacement elements is laminated (see, for example, Patent Document 1). In this liquid discharge head body, liquid pressurizing chambers respectively connected to a plurality of liquid discharge holes are arranged in a matrix, and each liquid discharge head is displaced by displacing a displacement element of a piezoelectric actuator substrate provided so as to cover it. Ink can be ejected from the holes. There are four piezoelectric actuator boards, and four flexible wiring boards that transmit drive signals to them are drawn out alternately on the left and right sides of the liquid discharge head main body, and between the liquid discharge head main body and the housing. As described above, 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 wiring board, and the driver IC is sandwiched between the liquid discharge head main body and the casing, and is exhausted through the casing.

JP 2007-307801 A

However, in the liquid ejection head described in Patent Document 1, the heat of the driver IC is transmitted to the piezoelectric actuator substrate through the flexible wiring substrate, and the characteristics of the displacement element on the piezoelectric actuator substrate fluctuate due to the heat. The discharge characteristics such as the discharge amount sometimes fluctuated.

  More specifically, when used for printing or the like, the portion of the driver IC that processes the drive signal changes depending on the pattern to be printed, so that the temperature of a portion of the driver IC may be higher than that of the other portions. , Sometimes it was lower. On the flexible wiring board, wiring extending mainly in the direction from the driver IC toward the head body is arranged, so that when the temperature of a part of the driver IC becomes high, it is electrically connected to the driver IC. Since heat is transferred to the piezoelectric actuator substrate of the part through the wiring, the temperature of the part becomes high. As a result, the ejection characteristics of the portion fluctuate, and the printing accuracy may be lowered.

  Accordingly, an object of the present invention is to provide a liquid discharge head capable of reducing variations in the heat of a driver IC transmitted to a head body via a flexible wiring board depending on the location, and a recording apparatus using the same.

  The liquid ejection head of the present invention includes a head body that ejects liquid, a flexible wiring board that transmits a signal for controlling the head body, a driver IC that is mounted on the flexible wiring board, the driver IC, The flexible wiring board between the head main body and the heat wiring part attached so as to cross the flexible wiring board is provided.

  The recording apparatus of the present 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 head body.

  Since heat is transmitted in the direction in which the flexible wiring board intersects by the heat conducting portion, the heat transmitted from the driver IC to the head body via the flexible wiring board is less varied depending on the location, and variation in ejection characteristics can be reduced.

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 head main 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. 2 and is a diagram in which a part of the structure is omitted for explanation. 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 wiring board used for this invention, (b) is a top view of one Embodiment of the elastic board used for this invention.

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 the embodiment of the flexible wiring board used in the present invention on the side where the reinforcing plate 62 is attached, and FIG. 8B is an elasticity used in the present invention. It is a top view of one embodiment of a board.

The liquid discharge head 2 includes a (liquid discharge) head main body 2 a, a flexible wiring board 60, a driver IC (Integrated Circuit) 55 mounted on the flexible wiring board 60, and a heat conduction unit attached to the flexible wiring board 60. 66. The liquid discharge head 2 may further include a housing 90, and the head body 2a may include a reservoir 40. The casing 90 is made of metal or the like and has a polyhedral shape, and in the present embodiment, has a rectangular parallelepiped shape. The housing 90 includes a housing main body 90a including a top plate and end surfaces 90aa of the housing main body which are side surfaces at both ends in the longitudinal direction of the liquid discharge head 2, and a housing side plate 90b attached to the housing 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. This may be considered part of the housing 90. The casing body 90a is attached to the guide frame 84 with screws or the like at the top plate portion. The housing side plate 90b is attached to the housing body 90a from the side 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. This may also be considered part of the housing 90. 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 a liquid mist or the like does not easily enter the housing 90 beyond the connection substrate 80. An external connector 80a 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 wiring on this surface can be reduced, it is possible to suppress such wiring from being short-circuited by droplets. By inserting a resin or the like between the external connector 80a and the connection board 80, it is possible to suppress the occurrence of a short circuit near the through-hole on the lower side of the external connector 80a or 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 suppress 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. The reservoir 40 and the flow path member 4 are connected at both ends in the longitudinal direction, 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 mounted on the flexible wiring board 60 through the external connector 80a, the connection board 80, the internal connector 80b, the circuit board 82, and the flexible wiring board 60. The driver IC 55 performs signal processing, drives the displacement element 30 of the piezoelectric actuator substrate 21 through the flexible wiring substrate 60, and pressurizes the liquid in the flow path member 4, thereby discharging droplets. 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 wiring board 60 has a flexible belt-like shape, and has a metal wiring 61 inside. A part of the wiring 61 is exposed on the surface of the flexible wiring board 60, and the exposed wiring 61 The circuit board 82, the driver IC 55, and the piezoelectric actuator substrate 21 are electrically connected.

  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.

  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. In addition, a flexible wiring 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 wiring substrate 60 connected to the piezoelectric actuator substrate 21 is indicated by a dotted line so that the state in which the two flexible wiring substrates 60 are connected to the piezoelectric actuator substrate 21 can be seen. The electrode of the wiring 61 formed on the flexible wiring substrate 60 that is electrically connected to the piezoelectric actuator substrate 21 has a rectangular shape in the connection region 60b with the piezoelectric actuator substrate at one end of the flexible wiring substrate 60. Has been placed. The two flexible wiring boards 60 are connected so that their ends come to the center of the piezoelectric actuator board 21 in the short direction. The two flexible wiring boards 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 wiring board 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 the 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 strip-shaped flexible wiring board 60, and the drive signal generated by the driver IC 55 is connected to the other end. Is output to the piezoelectric actuator substrate 21. The number of the wirings 61 of the flexible wiring board 60 is several tens or more on the circuit board 82 side. The electrodes electrically connected to the connector 82a of the circuit board 82 of the flexible wiring board 60 are arranged in a line in the longitudinal direction of the head body 2a in the connection areas 60a with the four circuit boards. On the piezoelectric actuator substrate 21 side, the number of wirings 61 is several hundreds or more, or even one thousand or more, corresponding to each of the displacement elements 30.

  In FIG. 8A, a part of the wiring 61 is schematically shown and almost omitted. Of the wiring 61, the width of the signal wiring through which the drive signal flows is reduced to about 20 to 100 μm. For the ground wiring, etc., if the width of the flexible wiring board 60 on the side of the circuit board 82 of the driver IC 55 is curved and the width of the curved wiring is thicker than the surrounding area, the rigidity of the curved section is increased. The effect of pressing on the IC 55 side can be strengthened. The hatched portion of the wiring 61 in FIG. 60A exemplifies the wiring 61 that is wider than the surroundings.

The driver IC 55 generates heat when processing the drive signal. Since the driver IC 55 is pressed against the housing 90 by bending the elastic plate 96, the generated heat is mainly transmitted to the housing 90, further transmitted to the entire housing side plate 90b, and further spread to the entire housing 90. The heat is dissipated. 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.

  When the elastic plate 96 presses the plurality of driver ICs 55, the elastic plate 96 can be pressed almost uniformly against each driver IC when the elastic plate 96 has a branched shape as shown in FIG. 8B. . FIG. 8B is a side view of the elastic plate 96, and the lower side of the figure is bent in an L shape and attached to the reservoir 40. The upper side of the figure branches into four, which is the same as the number of driver ICs 55, and the four driver ICs 55 at the branch destination 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.

  In addition, when the heat conduction material is filled between the driver IC 55 and the housing 90, the area in contact with the heat conduction material increases, so that the heat conductivity becomes higher. 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 the case where such a heat conductive material is used, a heat conductive portion 66, which will be described in detail below, is provided at a portion extending from the portion where the driver IC 55 of the flexible wiring board 60 is mounted to the displacement element 30 side. If attached, it can suppress that a heat conductive material flows into the displacement element 30 side. Further, the cross-sectional shape of the frame 92 is a convex shape so as to play a role of suppressing flow.

  In the case where there are a plurality of driver ICs 55, the heat dissipating efficiency can be increased because the heat spreads more easily if the positions where the driver ICs 55 are in contact with the housing 90 are separated. In order to do so, the driver ICs 55 adjacent in the longitudinal direction of the head body 2a may be arranged at different distances from the head body 2a. More specifically, the driver ICs 55 may be alternately arranged in a staggered manner.

  The heat generated when the driver IC 55 processes the drive signal is transmitted to the piezoelectric actuator substrate 21 via the flexible wiring substrate 60. This can be reduced if the heat is exhausted to the housing 90 as described above, but some of this is also transmitted to the piezoelectric actuator substrate 21. Since the displacement element 30 has a certain temperature characteristic depending on the material of the piezoelectric ceramic layer 21b and the like, the discharge characteristic fluctuates when the heat is transmitted and the temperature rises. Even in other ejection methods, the heat generating part that generates pressure is considered to have a certain level of temperature characteristics.

In the driver IC 55, the portion that generates heat changes depending on the pattern to be printed and whether or not a specific function is used. For example, when printing a biased pattern, one driver IC 55 becomes hotter than the other driver IC 55, or a specific place of the driver IC 55 becomes hot. Conversely, if there is a part that is not operating locally, that part becomes low temperature. The wiring 61 formed on the flexible wiring board 60 mainly extends in the direction from the connector 82a of the circuit board to the head main body 2a, and in the same direction, but extends in the direction from the driver IC 55 to the head main body 2a. A plurality are arranged in a direction perpendicular to that direction. For this reason, when the temperature of a part of the driver IC 55 is increased, heat is easily transmitted to the part of the piezoelectric actuator substrate 21 to which the part is electrically connected, so that the temperature of the part increases.

  Therefore, the heat conductive portion 66 having high thermal conductivity is attached so as to intersect the flexible wiring board 60 between the driver IC 55 of the flexible wiring board 60 and the head substrate 2a. Crossing here means crossing in the wiring direction in which the wiring 61 extends. With such attachment, heat is easily transmitted in a direction intersecting with the wiring direction of the flexible wiring board, dependency can be reduced depending on the location of the heat transmitted from the driver IC 55, and variation in ejection characteristics can be reduced.

  Note that “to intersect” here means to be substantially perpendicular to the belt-like flexible wiring board 60 and substantially perpendicular to the wiring direction. The term “substantially orthogonal” may be within a range of about 90 ± 30 degrees, but if it is within a range of about 90 ± 5 degrees, the distance from the head main body 2a at the position where the temperature is equalized in the flexible wiring board 60 is determined. Since the difference is reduced, the temperature variation transmitted to the head main body 2a can be further reduced.

  It is preferable that the heat conducting portion 66 is attached to the flexible wiring board 60 in a range where at least the wiring 61 is formed, and further over the entire width of the flexible wiring board 60. Moreover, if the heat conduction part 66 is attached to both surfaces of the flexible wiring board 60 so as to sandwich the flexible wiring board 60, the effect of soaking can be further increased. Furthermore, if the second thermal heat conducting portion is provided between the driver IC 55 and the circuit board 82 of the flexible wiring board 60 so as to intersect the flexible wiring board 60, the temperature can be further equalized.

  The heat conduction part 66 is configured by a member having high heat conductivity such as metal. A rectangular, rod-like hard material may be used, but if a thin film-like flexible material is used in the form of a band, handling when assembling the liquid discharge head 2 becomes easy. If a copper product is used, it is easy to process into a film shape having high thermal conductivity and flexibility. For the same reason, it may be made of aluminum. In order to suppress a short circuit that may be caused by contact of the conductive member with another part, the film may be coated with a resin such as polyimide. What is necessary is just to attach the heat conductive part 66 to a flexible wiring board with a double-sided tape, an adhesive agent, etc.

  In the case where there are a plurality of driver ICs 55, the operation state may be different for each driver IC 55, so that a temperature difference is likely to occur. Further, when the planar shape of the driver IC 55 is long in one direction, a temperature difference is likely to occur in that direction. However, if the driver IC 55 is arranged so that the longitudinal direction of the driver IC 55 is along the heat conducting portion 66, the temperature can be more uniform. .

  If the heat conducting portion 66 is brought into contact with a portion where heat can be radiated, not only the temperature can be equalized, but also the heat transmitted to the head main body 2a can be reduced, so that fluctuations in ejection characteristics can be reduced. Heat can be effectively dissipated by bringing the heat conducting portion 66 into contact with a portion of the housing 90 that is away from the portion where the driver IC 55 is in contact. In order to make contact with the housing 90, for example, the heat conducting portion 66 is shaped so that the end of the intersecting portion of the heat conducting portion 66 that intersects the flexible wiring board 60 is extended, and the extension is made. What is necessary is just to make an edge part contact the housing | casing 90. FIG. In order to make contact, when the case side plate 90b is screwed, the case side plate 90b may be pinched between them. Further, the contact mentioned here includes attaching via an adhesive or the like.

Only one side may be brought into contact, but if it is placed on both sides, the amount of heat exhausted is approximately doubled, so heat can be exhausted more efficiently, and heat is exhausted from both ends of the region intersecting the flexible wiring board 60. Therefore, the temperature variation in the region intersecting with the flexible wiring board 60 can be further reduced.

  If the part in contact with the housing 90 is a surface different from the surface in contact with the driver IC 55, heat from the driver IC 55 is difficult to be transmitted, so heat can be efficiently exhausted. When the head main body 2a is long in one direction, it is preferable to arrange the flexible wiring board 60 along the longitudinal direction of the head main body 2a because space can be used efficiently. In that case, it is preferable that the driver IC 55 is brought into contact with the surface of the housing 99 along the longitudinal direction of the head main body 2a because the length of the flexible wiring board 60 can be shortened. In such a case, exhaust heat efficiency can be improved by bringing the heat conducting section 66 into contact with the surface located at the longitudinal end of the head body 2a. In this case, when performing multicolor printing or arranging a plurality of liquid ejection heads 2 in order to increase resolution and throughput, they are arranged close to each other in the lateral direction. Thermal efficiency is improved. In this embodiment, the surface located at the end in the longitudinal direction of the head main body 2a is the end surface 90aa of the housing main body.

  Further, the heat conducting unit 66 may be brought into contact with the housing 90. This is preferable because soaking can be achieved through the casing 90 having high thermal conductivity.

  Further, when the plurality of driver ICs 55 are arranged at positions with different distances from the head main body 2a, the flexible wiring board 60 has substantially the same length even if the distances to the positions at which the plurality of driver ICs 55 are arranged are different. If this is done, the amount of heat transferred can be made closer, which is preferable.

  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 the present embodiment, two manifolds 5 are provided independently, and openings 5a are provided at both ends. One manifold 5 is provided with seven partition walls 15 and 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. 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 wiring boards 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 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 flexible wiring board 60 (the front end and the end in the longitudinal direction of the piezoelectric actuator substrate 21). ) Can be strengthened by the connection on the common electrode surface electrode 28, so that the flexible wiring board 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 parts constituting the individual flow path 12 are close to each other in different positions. The manifold 5 and the discharge hole 8 are connected via the pressurizing chamber 10.

The holes formed in each plate will be described. These holes include the following. The first is the pressurizing chamber 10 formed in the cavity plate 4a. Second, the pressure chamber 10
It is a communicating hole which comprises the individual supply flow path 14 connected with the manifold 5 from the end of this. 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 wiring board 60. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 25 through the flexible wiring board 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 wiring board 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 wiring board 60 and the wires so that the potentials 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 unit. However, the present invention is not limited to this, and any other device that can pressurize the liquid in the liquid pressurizing chamber 10 is 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 wiring board 60a ... connection area with circuit board 60b ... connection area with piezoelectric actuator board 61 ... wiring (of flexible wiring board) 62 ... (first) reinforcing plate 64 ... Second reinforcing plate 66 ... Heat conduction part 80 ... Connection substrate 80a ... External connector (of connection substrate) 80b ... Internal connector (of connection substrate) 80c ... (Connection) Wiring 82 ... Circuit board 82a ... (Circuit board) connector 84 ... Guide frame 90 ... Housing 90a ... Housing body 90aa ... End face of housing body 90b ... -Housing side plate 92 ... Frame 94 ... Side plate 96 ... Elastic plate 98 ... Thermal insulation member

Claims (8)

A head body for discharging liquid;
A flexible wiring board for transmitting a signal for controlling the head body;
A driver IC mounted on the flexible wiring board;
A heat conducting portion attached to the flexible wiring board between the driver IC and the head body so as to intersect the flexible wiring board ;
Attached to the head body, the flexible wiring board, the driver IC, and a polyhedral housing in which the heat conducting unit is housed, and
The driver IC is in contact with the housing,
The liquid ejection head , wherein the heat conducting unit is in contact with a surface of the housing other than a surface with which the driver IC is in contact .   The liquid discharge head according to claim 1, wherein there are a plurality of the driver ICs, and the driver ICs are arranged along the heat conducting portion.   3. The liquid discharge head according to claim 1, wherein a shape of the driver IC is long in a direction along the heat conducting portion. A head body for discharging liquid;
A flexible wiring board for transmitting a signal for controlling the head body;
A driver IC mounted on the flexible wiring board;
A heat conducting portion attached to the flexible wiring board between the driver IC and the head body so as to intersect the flexible wiring board;
Attached to the head body, the flexible wiring board, the driver IC, and a polyhedral housing in which the heat conducting unit is housed, and
The heat conductive portion, the extend to both sides in the direction orthogonal to the flexible wiring board, a liquid discharge head you characterized in that the opposite ends is in contact with the housing. A head body for discharging liquid;
A flexible wiring board for transmitting a signal for controlling the head body;
A driver IC mounted on the flexible wiring board;
A heat conducting portion attached to the flexible wiring board between the driver IC and the head body so as to intersect the flexible wiring board;
Attached to the head body, the flexible wiring board, the driver IC, and a polyhedral housing in which the heat conducting unit is housed, and
The head main body is long in one direction, the driver IC is in contact with a surface along the one direction of the casing, and the heat conducting portion is located at an end portion in the one direction of the casing. liquid discharge head you characterized in that in contact with the plane to be. A head body for discharging liquid;
A flexible wiring board for transmitting a signal for controlling the head body;
A driver IC mounted on the flexible wiring board;
A heat conduction part attached to the flexible wiring board between the driver IC and the head body so as to intersect the flexible wiring board;
Said head body whereas long direction, the driver IC is more, the driver IC, which are adjacent to each other in the one direction, the liquid discharge head you characterized by being arranged at different distances from the head body . Liquid discharge head according to any one of claims 1 to 6, characterized in that said head body for discharging liquid by a piezoelectric element. To the liquid discharge head according to any one of claims 1 to 7 and a conveyance unit for conveying the recording medium to the liquid ejecting head, characterized by comprising a control section for controlling the head body Recording device.