JP5388834B2 - 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, a liquid discharge head that is long in one direction is covered with a manifold (common flow path) and a flow path member having a liquid discharge hole that connects the manifold through a plurality of liquid pressurization chambers, respectively, and the liquid pressurization chamber. There is known a structure in which an actuator unit having a plurality of displacement elements provided in is laminated (see, for example, Patent Document 1). In this liquid ejection head, the liquid pressurizing chambers connected to the plurality of liquid ejection holes are arranged in a matrix, and the displacement elements of the actuator unit provided so as to cover the chambers are displaced so that each liquid ejection chamber Ink is ejected and printing is possible at a resolution of 600 dpi in the main scanning direction.

  In addition, as a reservoir channel that is used by being overlapped with such a channel member, a second dew member is known in which etched metal plates are stacked and a channel is provided inside (see FIG. For example, see Patent Document 2.) Then, the flexible flat cable through which the signal for driving the piezoelectric actuator flows is taken out between the flow path member and the reservoir flow path member to the long side of the liquid ejection head.

JP 2003-305852 A JP 2004-114415 A

  However, in the liquid ejection head described in Patent Document 2, stress is applied from the flow path member and the reservoir flow path member to the piezoelectric actuator due to a temperature change, and the applied stress causes the characteristics of the piezoelectric element to fluctuate. There has been a problem that the discharge characteristics of the liquid droplets discharged from the holes are changed.

  Such a liquid discharge head may be heated to stabilize the viscosity of the liquid to be discharged. Further, in the manufacturing process of the liquid discharge head, it is conceivable to bond the piezoelectric actuator and the flow path member with a thermosetting resin. In any case, there is a difference in coefficient of thermal expansion between the piezoelectric actuator and the flow path member, and the piezoelectric actuator receives stress from the flow path member if the temperature differs between the manufacturing process and the usage environment. In a reservoir such as a head, the way in which stress is applied differs depending on the part of the piezoelectric actuator, so that the liquid ejection characteristics may vary depending on the part of the piezoelectric actuator.

  Accordingly, an object of the present invention is to provide a liquid discharge head having a small difference in discharge characteristics depending on the portion of the piezoelectric actuator, and a recording apparatus using the liquid discharge head.

  The liquid discharge head according to the present invention includes a liquid discharge hole surface in which a plurality of liquid discharge holes are open, a plurality of liquid pressurization chambers connected to the plurality of liquid discharge holes, and a liquid in the plurality of liquid pressurization chambers. And a plurality of liquid pressurizing chambers, each having a flat plate-like flow passage member having a liquid pressurizing chamber surface facing the liquid discharge hole surface and having a liquid pressurizing chamber surface facing the liquid discharge hole surface. A flat plate-like piezoelectric actuator laminated on the surface of the liquid pressurizing chamber, a signal transmission unit for transmitting a signal for driving the piezoelectric actuator, a recess in which the piezoelectric actuator is housed, and the A connection surface having a liquid relay hole connected to the liquid introduction hole, a reservoir channel connected to the liquid introduction hole, a through hole penetrating upward from the connection surface and passing through the signal transmission unit; And having a reservoir flow path member laminated on the liquid pressurizing chamber surface, and the connection surface when viewed from a direction orthogonal to the liquid pressurizing chamber surface, The flow path member and the joint portion of the reservoir flow path member surround the piezoelectric actuator.

  When viewed from a direction orthogonal to the liquid pressurizing chamber surface, the piezoelectric actuator has a quadrangular shape having two opposite sides parallel to the one direction, and the flow path member extends from the two sides. It is preferable that the distance to the junction of the reservoir channel member is the same.

  The flow path member and the piezoelectric actuator are bonded via a thermosetting resin, the flow path member and the reservoir flow path member are bonded via a thermosetting resin, and the piezoelectric actuator is thermally expanded. It is preferable that the coefficient is smaller than any of the flow path member and the reservoir flow path member.

The difference in thermal expansion coefficient between the flow path member and the reservoir flow path member is preferably 2 × 10 ⁻⁶ / ° C. or less.

  The reservoir channel member is formed by joining a plurality of members, and the through hole is preferably provided at a boundary between the plurality of members.

  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 signal transmission unit, and controls the piezoelectric actuator and the transport unit. It is characterized by having a control part which performs.

  According to the driving method of the liquid discharge head of the present invention, the liquid discharge hole surface in which the plurality of liquid discharge holes are opened, the plurality of liquid pressurizing chambers connected to the plurality of liquid discharge holes, and the plurality of liquids, respectively. A flow path member having a liquid pressurization chamber surface facing the liquid discharge hole surface, which is open in a liquid introduction hole of a manifold for supplying a liquid to the pressurization chamber, and long in one direction, and the plurality A plate-like piezoelectric actuator laminated on the surface of the liquid pressurizing chamber so as to cover the liquid pressurizing chamber, a signal transmission unit for transmitting a signal for driving the piezoelectric actuator, and the piezoelectric actuator. A connecting surface having a recess and a liquid relay hole connected to the liquid introduction hole, a reservoir flow path connected to the liquid introduction hole, and the signal transmission unit passing through the connection surface upward. And a reservoir channel member in which the connection surface is stacked on the surface of the liquid pressurizing chamber, and a direction perpendicular to the surface of the liquid pressurizing chamber When viewed from the above, since the joint portion of the flow path member and the reservoir flow path member surrounds the periphery of the piezoelectric actuator, the piezoelectric actuator, the flow path member, and Since the stress applied due to the difference in thermal expansion coefficient with the reservoir channel member is nearly constant, the variation in ejection characteristics due to the portion of the piezoelectric actuator is reduced.

  When viewed from a direction orthogonal to the liquid pressurizing chamber surface, the piezoelectric actuator has a quadrangular shape having two opposite sides parallel to the one direction, and the flow path member extends from the two sides. When the distance to the joint portion of the reservoir flow path member is the same, the stress applied to the two outer sides of the piezoelectric actuator, which is easily influenced by the surroundings, becomes close, so the fluctuation of the discharge characteristics due to the part of the piezoelectric actuator Is less.

  The flow path member and the piezoelectric actuator are bonded via a thermosetting resin, the flow path member and the reservoir flow path member are bonded via a thermosetting resin, and the piezoelectric actuator is thermally expanded. When the coefficient is smaller than both of the flow path member and the reservoir flow path member, since the compression pressure is applied to the piezoelectric actuator after bonding by thermosetting, the number of the piezoelectric actuators is very large. It is difficult to cause drive deterioration in which the displacement characteristics change when driven a number of times. When such compressive stress is applied, the stress applied to the piezoelectric actuator is made uniform as described above.

When the difference in coefficient of thermal expansion between the flow path member and the reservoir flow path member is 2 × 10 ⁻⁶ / ° C. or less, the liquid discharge head is not easily deformed so as to bend after bonding by thermosetting. Therefore, it is possible to suppress the stress generated by the deformation of the piezoelectric actuator.

  The reservoir channel member is formed by joining a plurality of members, and when the through-hole is provided at a boundary of the plurality of members, the assembly is performed so as to sandwich the signal transmission unit when assembled. The trouble of passing the signal transmission part through the through hole can be eliminated.

  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 signal transmission unit, and controls the piezoelectric actuator and the transport unit. By providing the control unit that performs the above-described operation, there is little variation in ejection characteristics due to the portion of the piezoelectric actuator, so that a good image can be obtained by printing.

1 is a schematic configuration diagram of a printer that is a recording apparatus according to an embodiment of the present invention. (A) is a top view of the flow path member and piezoelectric actuator which comprise the liquid discharge head of FIG. 1, (b) is a top view of a reservoir flow path member. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. It is a longitudinal cross-sectional view along the VV line of FIG. 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. FIG. 2 is a longitudinal sectional view of a head body constituting the liquid ejection head of FIG. It is a top view of the plate which comprises a reservoir flow path. It is a top view of the reservoir channel member which constitutes the liquid discharge head of other embodiments of the present 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 are fixed to the printer 1. The liquid discharge head 2 has an elongated shape in a direction from the front to the back in FIG.

  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 four liquid discharge heads 2 are arranged close to each other along the conveyance direction by the conveyance belt 111. Each liquid discharge head 2 has a head body 13 at the lower end. A number of liquid ejection holes 8 for ejecting liquid are provided on the lower surface of the head body 13 (see FIG. 4).

  Liquid droplets (ink) of the same color are ejected from the liquid ejection holes 8 provided in one liquid ejection head 2. Since the liquid ejection holes 8 of each liquid ejection head 2 are arranged at equal intervals 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), Printing can be performed without gaps in one direction. The colors of the liquid ejected from each liquid ejection head 2 are magenta (M), yellow (Y), cyan (C), and black (K), respectively. Each liquid ejection head 2 is disposed with a slight gap between the lower surface of the head body 13 and the transport surface 127 of the transport belt 111.

  The printing paper P transported by the transport belt 111 passes through the gap between the liquid ejection head 2 and the transport belt 111. At that time, droplets are ejected from the head main body 13 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. 6 is a perspective view of the liquid discharge head 2. The liquid discharge head 2 includes a liquid discharge head main body 13 and a housing 90. The casing 90 is made of metal, and a hole 99 through which a signal cable for transmitting a driving signal is partially opened. In the example of FIG. 6, a hole 99 is opened in a part of the upper surface, and a signal cable (not shown) through which a drive signal connected to the control unit 100 is transmitted passes through the hole 99 and is closed with a resin lid or the like. Can be removed. A liquid introduction hole 41b is opened in the liquid ejection head 2, and the liquid ejected from the liquid introduction hole 41b is supplied.

  FIG. 7 is a cross-sectional view of the liquid ejection head 2 shown in FIG. The liquid discharge head body 13 includes the flow path member 4, the reservoir flow path member 40, the piezoelectric actuator unit 21, the signal supply unit 92, and the driver IC 55. A reservoir channel member 40 is overlaid on the liquid discharge head body 13, and a frame 96 to which a heat insulating elastic member 97 is attached and a substrate 94 on which a connector 95 is mounted are fixed to the reservoir channel member 40. Has been. The frame 96 is not connected in the cross-sectional view of FIG. 7, but is fixed at a portion other than this cross-section. A drive signal sent from the control unit 100 to the substrate 94 via a signal cable (not shown) is sent to the signal transmission unit 92 via the connector 95. The driver IC 55 mounted on the signal transmission unit 92 processes the drive signal, and the processed drive signal drives the liquid ejection element 50 of the piezoelectric actuator unit 21 (described later) through the signal transmission unit 92, so that the inside of the flow path member 4. By pressurizing the liquid, droplets are ejected. For example, the substrate 94 may divide the ejection signal into a plurality of driver ICs 55 or rectify the ejection signal. However, the substrate 94 is not provided, and the signal cable from the control unit 100 is directly connected to the signal transmission unit 92. You may make it connect. The signal transmission unit 92 is a flexible belt-like shape, and has a metal wiring inside, and a part of the wiring is exposed on the surface of the signal transmission unit 92, and the connector 95, The driver IC 55 and the piezoelectric actuator unit 21 are electrically connected.

  At this time, the distances A1 and A2 between the two opposite sides parallel to the longitudinal direction of the liquid discharge head 13 of the piezoelectric actuator 21 and the portion where the flow path member 4 and the reservoir flow path 40 are joined are the same. Therefore, the stress caused by the difference in thermal expansion coefficient applied to the two sides of the piezoelectric actuator 21 becomes the same, and the fluctuation of the liquid ejection characteristics due to the part of the piezoelectric actuator 21 can be reduced. Here, the same distance means that the difference is within 10%.

  The driver IC 55 generates heat when performing the above-described drive signal processing. When this heat is transmitted to the flow path member 4, a temperature difference occurs between the flow path member 4 and the liquid inside the flow path member 4. Since the viscosity of the liquid changes as the temperature changes, even if the pressure from the pressurizing means is constant, the discharge speed and amount of the droplets change. If the speed and amount of the ejected droplets change, the landing position on the printing paper P shifts, and the size of the pixels formed by the spreading of the droplets after landing changes, so the accuracy of the printed image is low. May be. However, since the driver IC 55 is pressed by the heat insulating elastic member 97 via the signal transmission unit 92 and pressed against the metal casing 90, the generated heat is mainly transmitted to the casing 90, and further the casing. It spreads quickly throughout the body 90 and is radiated to the outside.

  FIG. 8 is a longitudinal sectional view of the reservoir channel member 40. The reservoir channel member 40 is formed in a number larger than the number of liquid introduction holes 41b connected to an external liquid tank (not shown) and the ink supply ports 41b, and the liquid relays connected to the liquid introduction ports 5b of the channel member 4 respectively. It has a port 41 a, an internal reservoir channel 41 that guides ink supplied from the liquid supply port 41 b to the ink relay port 41 a, and an air chamber 45.

  The reservoir channel member 40 is configured by laminating a plurality of rectangular flat plates (plates) 40 a to 40 h and a film that becomes the deformable damper 43. One surface of the damper 43 faces the reservoir channel 41, and the other surface faces the air chamber 45. Furthermore, the air chamber is connected to the outside through the opening 45a. As a result, the volume of the reservoir channel 41 is changed by the deformation of the damper 43, and the liquid can be stably supplied when the liquid discharge amount suddenly increases.

  Next, the head main body 13 constituting the liquid discharge head of the present invention will be described. 2A is a top view showing the flow path member 4 and the piezoelectric actuator 21 in the head main body 13 shown in FIG. 1, and FIG. 2B is a reservoir flow path member 40. The reservoir channel 41 in the reservoir channel 40 is omitted. Further, the position where the piezoelectric actuator 21 is accommodated is shown. The piezoelectric actuator 21 is connected to a flexible flat cable which is a signal supply 92 described later, and a reservoir flow path member is laminated on the flow path member 4 to form the head body 13.

  FIG. 3 is an enlarged top view of a region surrounded by a one-dot chain line in FIG. 2A, and is a part of the head main body 13. FIG. 4 is an enlarged perspective view of the same position as in FIG. 3, in which some of the flow paths are omitted so that the position of the liquid discharge holes 8 can be easily understood. 3 and 4, in order to make the drawings easy to understand, the liquid pressurizing chamber 10 (liquid pressurizing chamber group 9), the squeezing 12, and the liquid discharge holes which are to be drawn by broken lines below the piezoelectric actuator unit 21. 8 is drawn with a solid line. FIG. 5 is a longitudinal sectional view taken along line VV in FIG.

  The head body 13 has a flat plate-like flow path member 4 and a piezoelectric actuator unit 21 and a reservoir flow path 40 on the flow path member 4. The piezoelectric actuator unit 21 has a trapezoidal shape, and is disposed on the upper surface of the flow path member 4 so that a pair of parallel opposing sides of the trapezoid is parallel to the longitudinal direction of the flow path member 4. Further, two piezoelectric actuator units 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator units 21 adjacent to each other on the flow path member 4 partially overlap in the short direction of the flow path member 4. In the area printed by driving the overlapping piezoelectric actuator unit 21, the droplets ejected by the two piezoelectric actuator units 21 are mixed and landed.

  A manifold 5 that is a part of the liquid flow path is formed inside the flow path member 4. The manifold 5 has an elongated shape extending along the longitudinal direction of the flow path member 4, and an opening 5 b of the manifold 5 is formed on the upper surface of the flow path member 4. A total of ten openings 5 b are formed along each of two straight lines (imaginary lines) parallel to the longitudinal direction of the flow path member 4. The opening 5b is formed at a position that avoids a region where the four piezoelectric actuator units 21 are disposed. The manifold 5 is supplied with liquid from a liquid tank (not shown) through the opening 5b.

  The manifold 5 formed in the flow path member 4 is branched into a plurality of branches (the manifold 5 at the branched portion is sometimes referred to as a sub-manifold 5a, and the manifold 5 from the opening 5b to the sub-manifold 5a is referred to as a liquid supply path). 5c). The liquid supply path 5 c connected to the opening 5 b extends along the oblique side of the piezoelectric actuator unit 21 and is disposed so as to intersect with the longitudinal direction of the flow path member 4. In a region sandwiched between two piezoelectric actuator units 21, one manifold 5 is shared by adjacent piezoelectric actuator units 21, and the sub-manifold 5 a branches off from both sides of the manifold 5. These sub-manifolds 5 a extend in the longitudinal direction of the head main body 13 adjacent to each other in regions facing the piezoelectric actuator units 21 inside the flow path member 4. That is, both ends of the sub-manifold 5a are connected to the liquid supply path 5c.

  The flow path member 4 has four liquid pressurizing chamber groups 9 in which a plurality of liquid pressurizing chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The liquid pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The liquid pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These liquid pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator unit 21. Accordingly, each liquid pressurizing chamber group 9 formed by these liquid pressurizing chambers 10 occupies a region having almost the same size and shape as the piezoelectric actuator unit 21. Further, the opening of each liquid pressurizing chamber 10 is closed by adhering the piezoelectric actuator unit 21 to the upper surface of the flow path member 4.

  In the present embodiment, as shown in FIG. 3, the manifold 5 branches into four rows of E1-E4 sub-manifolds 5a arranged in parallel with each other in the short direction of the flow path member 4, and each sub-manifold The liquid pressurizing chambers 10 connected to 5a constitute a row of liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the four rows are arranged in parallel to each other in the short direction. Yes. Two rows of liquid pressurizing chambers 10 connected to the sub-manifold 5a are arranged on both sides of the sub-manifold 5a.

  As a whole, the liquid pressurizing chambers 10 connected from the manifold 5 constitute rows of the liquid pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the rows are 16 rows parallel to each other in the short direction. It is arranged. The number of liquid pressurizing chambers 10 included in each liquid pressurizing chamber row is arranged so as to gradually decrease from the long side toward the short side corresponding to the outer shape of the displacement element 50 that is a piezoelectric actuator. Has been. The liquid discharge holes 8 are also arranged in the same manner. As a result, it is possible to form an image with a resolution of 600 dpi in the longitudinal direction as a whole.

  That is, when the liquid discharge hole 8 is projected so as to be orthogonal to a virtual straight line parallel to the longitudinal direction of the flow path member 4, each sub-manifold 5a is connected to the range R of the virtual straight line shown in FIG. Two liquid discharge holes 8, that is, a total of 16 liquid discharge holes 8 are equally spaced at 600 dpi. Moreover, the individual flow paths 32 are connected to the sub manifolds 5a at intervals corresponding to 150 dpi on average. This is because the individual flow paths 32 connected to the sub-manifolds 5a are not necessarily connected at equal intervals when the liquid ejection holes 8 for 600 dpi are divided and connected to the four sub-manifolds 5a. The individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm intervals if 150 dpi) in the extending direction of 5a, that is, the main scanning direction.

  Individual electrodes 35 to be described later are formed at positions facing the liquid pressurizing chambers 10 on the upper surface of the piezoelectric actuator unit 21. The individual electrode 35 is slightly smaller than the liquid pressurizing chamber 10, has a shape substantially similar to the liquid pressurizing chamber 10, and fits in a region facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. Is arranged.

  A large number of liquid discharge holes 8 are formed in the liquid discharge surface on the lower surface of the flow path member 4. These liquid discharge holes 8 are arranged at a position avoiding a region facing the sub-manifold 5 a arranged on the lower surface side of the flow path member 4. Further, these liquid discharge holes 8 are arranged in a region facing the piezoelectric actuator unit 21 on the lower surface side of the flow path member 4. These liquid discharge holes occupy an area having almost the same size and shape as the piezoelectric actuator unit 21 as one group, and the liquid discharge holes 8 are displaced by displacing the displacement elements 50 of the corresponding piezoelectric actuator units 21. Droplets can be discharged from The arrangement of the liquid discharge holes 8 will be described in detail later. The liquid discharge holes 8 in each region are arranged at equal intervals along a plurality of straight lines parallel to the longitudinal direction of the flow path member 4.

  The flow path member 4 included in the head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are a cavity plate 22, a base plate 23, an aperture (squeezing) plate 24, supply plates 25 and 26, manifold plates 27, 28 and 29, a cover plate 30 and a nozzle plate 31 in order from the upper surface of the flow path member 4. is there. A number of holes are formed in these plates. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 32 and the sub-manifold 5a. As shown in FIG. 5, the head main body 13 has a liquid pressurizing chamber 10 on the upper surface of the flow path member 4, the sub-manifold 5a on the inner lower surface side, and the liquid discharge holes 8 on the lower surface. Each portion constituting the path 32 is disposed close to each other at different positions, and the sub manifold 5 a and the liquid discharge hole 8 are connected via the liquid pressurizing chamber 10.

  The holes formed in each plate will be described. These holes include the following. First, the liquid pressurizing chamber 10 formed in the cavity plate 22. Second, there is a communication hole that forms a flow path that connects from one end of the liquid pressurizing chamber 10 to the sub-manifold 5a. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the liquid pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub manifold 5a). The communication hole includes the aperture 12 formed in the aperture plate 24 and the individual supply flow path 6 formed in the supply plates 25 and 26.

  Third, there is a communication hole that constitutes a flow channel that communicates from the other end of the liquid pressurizing chamber 10 to the liquid discharge hole 8, and this communication hole is referred to as a descender (partial flow channel) in the following description. . The descender is formed on each plate from the base plate 23 (specifically, the outlet of the liquid pressurizing chamber 10) to the nozzle plate 31 (specifically, the liquid discharge hole 8).

  Fourthly, there is a communication hole constituting the sub-manifold 5a. The communication holes are formed in the manifold plates 27 to 29. Depending on the position of the sub-manifold 5a, the manifold plate 29 may have a portion where no hole is formed, whereby the cross-sectional area of the sub-manifold 5a is changed.

  Such communication holes are connected to each other to form an individual flow path 32 from the liquid inflow port (the outlet of the submanifold 5a) from the submanifold 5a to the liquid discharge hole 8. The liquid supplied to the sub manifold 5a is discharged from the liquid discharge hole 8 through the following path. First, from the sub-manifold 5a, it passes through the individual supply flow path 6 and reaches one end of the aperture 12. Next, it proceeds horizontally along the extending direction of the aperture 12 and reaches the other end of the aperture 12. From there, it reaches one end of the liquid pressurizing chamber 10 upward. Further, the liquid pressurizing chamber 10 proceeds horizontally along the extending direction of the liquid pressurizing chamber 10 and reaches the other end of the liquid pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the liquid discharge hole 8 opened on the lower surface.

  Similarly to the channel member 4, the reservoir channel member 40 is obtained by a rolling method or the like, processed into a predetermined shape by etching, and laminated and bonded together with the damper 43 on the plates 40a to 40g. A chamber 45, an air chamber opening 45a, and a recess 47 for accommodating the piezoelectric actuator are provided.

  As shown in FIG. 5, the piezoelectric actuator unit 21 has a laminated structure including two piezoelectric ceramic layers 21a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The total thickness of the piezoelectric actuator unit 21 is about 40 μm. Each of the piezoelectric ceramic layers 21a and 21b extends so as to straddle the plurality of liquid pressurizing chambers 10 (see FIG. 3). The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator unit 21 includes a common electrode 34 made of a metal material such as Ag—Pd and an individual electrode 35 made of a metal material such as Au. As described above, the individual electrode 35 is disposed at a position facing the liquid pressurizing chamber 10 on the upper surface of the piezoelectric actuator unit 21. One end of the individual electrode 35 is drawn out of a region facing the liquid pressurizing chamber 10 to form a connection electrode 36. The connection electrode 36 is made of, for example, silver-palladium containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 36 is electrically joined to an electrode provided in an FPC (Flexible Printed Circuit) that is the signal transmission unit 92. Although details will be described later, a drive signal is supplied from the control unit 100 to the individual electrode 35 through the signal transmission unit 92. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 34 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 34 extends so as to cover all the liquid pressurizing chambers 10 in the region facing the piezoelectric actuator unit 21. The thickness of the common electrode 34 is about 2 μm. The common electrode 34 is grounded in a region not shown, and is held at the ground potential. In the present embodiment, a surface electrode (not shown) different from the individual electrode 35 is formed on the piezoelectric ceramic layer 21b at a position avoiding the electrode group composed of the individual electrodes 35. The surface electrode is electrically connected to the common electrode 34 through a through-hole formed in the piezoelectric ceramic layer 21b, and, like the large number of individual electrodes 35, another electrode on the signal transmission unit 92. Connected with.

  As shown in FIG. 5, the common electrode 34 and the individual electrode 35 are disposed so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is referred to as an active portion, and the piezoelectric ceramic in that portion is polarized. In the piezoelectric actuator unit 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 21b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator unit 21 has a so-called unimorph type configuration.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 35, pressure is applied to the liquid in the liquid pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are discharged from the corresponding liquid discharge ports 8 through the individual flow paths 32. That is, the portion of the piezoelectric actuator unit 21 that faces each liquid pressurizing chamber 10 corresponds to an individual displacement element 50 (actuator) corresponding to each liquid pressurizing chamber 10 and the liquid discharge port 8. That is, in the laminated body composed of two piezoelectric ceramic layers, the displacement element 50 which is a piezoelectric actuator having a unit structure as shown in FIG. The diaphragm 21a, the common electrode 34, the piezoelectric ceramic layer 21b, and the individual electrodes 35 positioned immediately above the chamber 10 are formed. The piezoelectric actuator unit 21 includes a plurality of displacement elements 50 that are pressurizing portions. . In the present embodiment, the amount of liquid ejected from the liquid ejection port 8 by one ejection operation is about 5 to 7 pl (picoliter).

  The large number of individual electrodes 35 are individually electrically connected to the control unit 100 via the signal transmission unit 92 and wiring so that the potential can be individually controlled.

  In the piezoelectric actuator unit 21 in the present embodiment, when an electric field is applied in the polarization direction to the piezoelectric ceramic layer 21b by setting the individual electrode 35 to a potential different from that of the common electrode 34, the portion to which this electric field is applied is piezoelectric. It works as an active part that is distorted by the effect. At this time, the piezoelectric ceramic layer 21b expands or contracts in the thickness direction, that is, the stacking direction, and tends to contract or extend in the direction perpendicular to the stacking direction, that is, the surface direction, due to the piezoelectric lateral effect. On the other hand, since the remaining piezoelectric ceramic layer 21a is an inactive layer that does not have a region sandwiched between the individual electrode 35 and the common electrode 34, it does not spontaneously deform. In other words, the piezoelectric actuator unit 21 uses the upper piezoelectric ceramic layer 21b (that is, the side away from the liquid pressurizing chamber 10) as a layer including the active portion and the lower side (that is, close to the liquid pressurizing chamber 10). This is a so-called unimorph type configuration in which the piezoelectric ceramic layer 21a on the side) is an inactive layer.

  In this configuration, when the control unit 100 sets the individual electrode 35 to a predetermined positive or negative potential with respect to the common electrode 34 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 liquid pressurizing chamber 10 (unimorph deformation). .

  The actual driving procedure in the present embodiment is such that the first electrode V1V (volt, which may be omitted hereinafter) is set in advance so that the individual electrode 35 has a higher potential than the common electrode 34, and every time there is a discharge request. The individual electrode 35 and the common electrode 34 are once set to a low potential, for example, the same potential by applying a second voltage lower than the first voltage V1, and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to the original shape at the timing when the individual electrode 35 becomes low potential, and the volume of the liquid pressurizing chamber 10 is compared with the initial state (the state where the potentials of both electrodes are different). To increase. At this time, a negative pressure is applied to the liquid pressurizing chamber 10 and the liquid is sucked into the liquid pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to protrude toward the liquid pressurizing chamber 10, and the volume of the liquid pressurizing chamber 10 is reduced so that the inside of the liquid pressurizing chamber 10 Becomes a positive pressure, the pressure on the liquid rises, and droplets are ejected. That is, a drive signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the manifold 5 to the liquid discharge hole 8 in the liquid pressurizing chamber 10. According to this, when the inside of the liquid pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplet can be ejected with a stronger pressure.

  In gradation printing, gradation expression is performed by the number of droplets ejected continuously from the liquid 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 specified gradation expression is continuously performed from the liquid discharge hole 8 corresponding to the specified 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 discharged later increases, but this is preferable because the landing points of a plurality of liquid droplets are close.

  When the liquid discharge head 2 is viewed from a direction orthogonal to the liquid pressurizing chamber surface 4b, it is important that the joint portion of the flow path member 4 and the reservoir flow path member 40 surrounds the periphery of the piezoelectric actuator 21. is there. The liquid ejection head 2 needs a signal transmission unit 92 that transmits a signal for driving the piezoelectric actuator 21. If the signal transmission unit 92 is taken out from the opening on the side surface of the liquid ejection head 2, the piezoelectric actuator in that portion is used. The stress due to the difference in thermal expansion coefficient applied to is reduced. Therefore, the periphery of the piezoelectric actuator 21 is surrounded by the flow path member 4 and the reservoir flow path member 40, and the signal transmission unit 92 passes through the through hole 49 that vertically penetrates the reservoir flow path member and is located above the liquid ejection head 2. To take out. By doing so, it is possible to suppress the occurrence of problems such as a short circuit due to a part of the ejected droplets becoming mist and reaching the piezoelectric actuator 21 and the signal transmission unit 62 from the side surface of the liquid ejection head 2.

  Such a configuration is useful for reducing fluctuations in the liquid ejection characteristics depending on the portion of the piezoelectric actuator 21 when there is a temperature difference between the environment in which the liquid ejection head 2 is assembled and the usage environment. This is because the piezoelectric actuator 21 is laminated on the liquid pressurizing chamber surface 4 b so as to cover the plurality of liquid pressurizing chambers 10, so that the piezoelectric ceramic layer 21 b of the displacement element 50 is between the displacement elements 50. This is because stress is received from the layer 21b. In particular, the flow path member 4, the reservoir flow path member, and the piezoelectric actuator 21 are joined with a thermosetting resin, and are suitable for use in an environment of room temperature to about 60 ° C. First, a resin that can be bonded at room temperature does not have sufficient resistance to ink, and is preferably bonded with a thermosetting resin.

  Further, if the striking operation is performed too much, the piezoelectric ceramic layer 21b of the liquid ejection element 50 may be extended, and as a result, there is a risk that the drive deterioration in which the discharge characteristics fluctuate may occur. It is preferable to apply a compressive stress to the piezoelectric ceramic layer 21b. And, as a method for realizing it, the flow path member 4 and the reservoir flow path member are made to have a higher thermal expansion history than the piezoelectric actuator 21 and bonded at a high temperature. Some use stress caused by differences in thermal expansion coefficients. In such a case, it is desirable that compressive stress be uniformly applied to the piezoelectric actuator 21, and it is effective to apply the above-described structure.

In order to adjust the compressive stress applied to the piezoelectric actuator 21, it is preferable that the flow path member 4 and the reservoir flow path member 40 are laminated with plates of different materials. This is because it is difficult to achieve a desired thermal expansion coefficient with one kind of material that can be etched and is resistant to the ink used. The flow path member 4 and the reservoir flow path member 40 are each preferably a plate having a high coefficient of thermal expansion and a plate having a low coefficient of thermal expansion. The thermal expansion coefficients of the flow path member 4 and the reservoir flow path member 40 are preferably 2 × 10 ^{−6 to} 6 × 10 ⁻⁶ / ° C. larger than that of the piezoelectric actuator 21. Moreover, it is preferable that the difference in thermal expansion coefficient between the flow path member 4 and the reservoir flow path member 40 is 2 × 10 ⁻⁶ / ° C. or less so that no warpage occurs.

  FIG. 10 is a plan view of a reservoir channel member 240 that can be used in another liquid discharge head of the present invention. The reservoir channel member 240 is externally the same as the reservoir channel member 40 shown in FIG. The reservoir channel member 240 is formed by bonding and laminating plates 240a to 240g similar to the plates 40a to 40g, and bonding rectangular parallelepiped members 240h and i to the side surfaces thereof. The plates 240a to 240g are narrower than the plates 240a to 240g, the through holes 249 are not formed, and the concave portions to be the through holes 249 are formed. The through hole 249 is constituted by the concave portion and the side surfaces of the members 240h and i. By doing so, it is possible to eliminate the trouble of passing the signal transmission part 92 through the through hole 249 by assembling the signal transmission part 92 so as to be sandwiched therebetween. In addition, after the driver IC 55 is mounted on the signal transmission unit 92, it is particularly effective when the through hole 249 is not passed.

  The liquid discharge head 2 as described above is manufactured as follows, for example.

  A tape composed of a piezoelectric ceramic powder and an organic composition is formed by a general tape forming method such as a roll coater method or a slit coater method, and a plurality of green sheets that become piezoelectric ceramic layers 21a and 21b after firing are produced. . An electrode paste to be the common electrode 34 is formed on a part of the green sheet by a printing method or the like. Further, a via hole is formed in a part of the green sheet as necessary, and a via conductor is filled in the via hole.

  Next, each green sheet is laminated to produce a laminate, and pressure adhesion is performed. The laminated body after pressure contact is fired in a high-concentration oxygen atmosphere, and then the individual electrode 35 is printed on the surface of the fired body using an organic gold paste. After firing, the connection electrode 36 is printed using an Ag paste. And the piezoelectric actuator unit 21 is produced by baking.

  Next, the flow path member 4 is produced by laminating plates 22 to 31 obtained by a rolling method or the like via an adhesive layer. Holes to be the manifold 5, the individual supply flow path 6, the liquid pressurizing chamber 10, the descender, and the like are processed in the plates 22 to 31 into a predetermined shape by etching.

  These plates 22 to 31 are preferably formed of at least one metal selected from the group consisting of Fe—Cr, Fe—Ni, and WC—TiC, particularly when ink is used as a liquid. Since it is desired to be made of a material having excellent corrosion resistance against ink, Fe-Cr is more preferable.

  Similarly, the reservoir channel member 40 is prepared by laminating and bonding plates 40a to 40g having various holes and a resin film to be the damper 43.

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

  Next, in order to electrically connect the piezoelectric actuator unit 21 and the control circuit 100, a silver paste is supplied to the connection electrode 36, an FPC which is a signal transmission unit 92 on which a driver IC 55 is mounted in advance is placed, and heat is applied. In addition, the silver paste is cured and electrically connected. The driver IC 55 was mounted by electrically flip chip connecting to the signal transmission unit 92 with solder, and then supplying a protective resin around the solder and curing it.

  Subsequently, the reservoir channel member 40 and the channel member 4 can be laminated and bonded via an adhesive layer, for example. A well-known adhesive layer can be used as the adhesive layer, but in order not to affect the piezoelectric actuator unit 21 and the flow path member 4, an epoxy resin, phenol resin, polyphenylene having a thermosetting temperature of 100 to 150 ° C. It is preferable to use at least one thermosetting resin adhesive selected from the group of ether resins. By heating to the thermosetting temperature using such an adhesive layer, the reservoir flow path member 40 and the flow path member 4 can be heat-bonded.

  Subsequently, the heat insulating elastic member 95 is attached to a predetermined position of the frame 96 with resin or the like. A board 94 on which a connector 295 is mounted in advance is sandwiched between a frame 96 attached with rubber as the heat insulating elastic member 95 and the reservoir channel member 40, and the frame 96 and the reservoir channel member 40 are joined with screws. 94 was fixed.

  Further, the signal transmission unit 92 is turned up and passed through the through hole 49 of the reservoir channel, and then one end of the signal transmission unit 92 is inserted into the connector 95 and fixed. Thereafter, the casing 90 is fitted, and the casing 90 is fixed to the frame 96 with screws, whereby the liquid ejection head 2 can be manufactured.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Channel member 4a ... Liquid discharge hole surface 4b ... Liquid pressurization chamber surface 5 ... Manifold 5a ... Sub manifold 5b ... -Manifold opening (liquid introduction hole)
5c ... Liquid supply path 6 ... Individual supply flow path 8 ... Liquid discharge hole 9 ... Liquid pressurization chamber group 10 ... Liquid pressurization chamber 11a, b, c, d ... Liquid Pressurizing chamber row 12 ... Squeeze 15a, b, c, d ... Liquid discharge hole row 21 ... Piezoelectric actuator unit 21a ... Piezoelectric ceramic layer (vibrating plate)
21b: Piezoelectric ceramic layer 22-31: Plate 32 ... Individual flow path 34 ... Common electrode 35 ... Individual electrode 36 ... Connection electrode 40 ... Back end (Reservoir flow path member )
40a to 40g ... Plate 41 ... Reservoir channel 41a ... Liquid relay hole 41b ... Liquid introduction hole in reservoir channel 42 ... Damper 45 ... Air chamber 45a ... Air chamber opening 47 ... Recessed portion for accommodating piezoelectric actuator 49 ... Through hole through which signal transmission part passes 50 ... Displacement element (piezoelectric actuator)
53 ... Filter 90 ... Housing 92 ... Flexible flat cable 93 ... Reservoir channel member 94 ... Substrate 95 ... Connector 96 ... Frame 97 ... Thermal insulating elastic member 99 ... Hole

Claims (6)

  A liquid discharge hole surface in which a plurality of liquid discharge holes are opened, a plurality of liquid pressurization chambers connected to the plurality of liquid discharge holes, and a liquid introduction hole of a manifold for supplying liquid to the plurality of liquid pressurization chambers The liquid pressurization is provided so as to cover the plurality of liquid pressurization chambers and a flat plate-like channel member having a liquid pressurization chamber surface facing the liquid discharge hole surface. It is connected to a flat plate-like piezoelectric actuator laminated on the chamber surface, a signal transmission unit for transmitting a signal for driving the piezoelectric actuator, a recess in which the piezoelectric actuator is accommodated, and the liquid introduction hole. A connection surface having a liquid relay hole, a reservoir channel connected to the liquid introduction hole, a through hole penetrating upward from the connection surface and passing through the signal transmission unit, and the connection Is a liquid discharge head comprising a reservoir flow path member stacked on the liquid pressurization chamber surface, and when viewed from a direction orthogonal to the liquid pressurization chamber surface, A liquid discharge head, wherein a joint portion of a reservoir channel member surrounds the periphery of the piezoelectric actuator.   When viewed from a direction orthogonal to the liquid pressurizing chamber surface, the piezoelectric actuator has a quadrangular shape having two opposite sides parallel to the one direction, and the flow path member extends from the two sides. The liquid discharge head according to claim 1, wherein the distance to the joint portion of the reservoir channel member is the same.   The flow path member and the piezoelectric actuator are bonded via a thermosetting resin, the flow path member and the reservoir flow path member are bonded via a thermosetting resin, and the piezoelectric actuator is thermally expanded. The liquid ejection head according to claim 1, wherein a coefficient is smaller than any of the flow path member and the reservoir flow path member. The liquid discharge head according to claim 3, wherein a difference in thermal expansion coefficient between the flow path member and the reservoir flow path member is 2 × 10 ⁻⁶ / ° C. or less.   The liquid discharge head according to claim 1, wherein the reservoir channel member is formed by joining a plurality of members, and the through hole is provided at a boundary between the plurality of members. .   The liquid ejection head according to claim 1, a conveyance unit that conveys a recording medium to the liquid ejection head, and the signal transmission unit, wherein the piezoelectric actuator and the conveyance unit are connected to each other. A recording apparatus comprising a control unit for controlling.

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