JP4968269B2 - Liquid discharge head and manufacturing method thereof - Google Patents

Description

  The present invention relates to a liquid discharge head that discharges liquid and a method of manufacturing the same.

  As an inkjet head that ejects ink droplets onto a recording medium such as printing paper, a flow path unit in which a number of individual ink flow paths including pressure chambers communicating with nozzles that eject ink droplets are formed, and the surface of the flow path unit And an actuator unit that adds ink droplet ejection energy to the pressure chamber by changing the volume of each pressure chamber. The actuator unit has a piezoelectric sheet straddling a large number of pressure chambers, a large number of individual electrodes arranged to face each pressure chamber on the surface of the piezoelectric sheet, and a large number of individual electrodes via the piezoelectric sheet. And a common electrode disposed on the substrate (see, for example, Patent Document 1).

JP 2008-143126 A (FIG. 1)

  In the step of fixing the actuator unit on the surface of the flow path unit, the pressurizing member pressurizes the actuator unit toward the surface of the flow path unit in a state where the actuator unit is disposed on the surface of the flow path unit. At this time, a region of the pressurizing member that is not in contact with the actuator unit is curved in the pressurizing direction starting from a corner of the actuator unit. For this reason, stress concentrates on the corner of the actuator unit, and the actuator unit may be damaged.

  The objective of this invention is providing the liquid discharge head which can suppress that an actuator unit breaks, and its manufacturing method.

The liquid discharge head of the present invention includes a common liquid chamber to which liquid is supplied, a flow path unit in which a plurality of individual liquid flow paths are formed from the outlet of the common liquid chamber to the nozzle through the pressure chamber, and the flow An actuator unit that is fixed to the surface of the path unit and discharges liquid from the nozzle, and the piezoelectric layer, the individual electrodes arranged on the piezoelectric layer, and the piezoelectric layer sandwiched between the individual electrodes And an actuator unit having electrodes. On the surface of the flow path unit, the planar shape has a size and shape that can accommodate the actuator unit, and a recess whose depth is more than half of the thickness of the actuator unit is formed. The pressure chamber is formed on the bottom surface of the recess, the actuator unit is fixed so as to face the pressure chamber, and a pair of pressurizing members are attached to the bottom surface of the recess via an adhesive. The actuator unit is fixed to the bottom surface of the depression by pressing while sandwiching the surface of the actuator unit disposed on the surface and the surface of the flow path unit opposite to the surface where the depression is formed. , At least a part of the area of the pressure member that pressurizes the actuator unit that is not in contact with the actuator unit, So as to be supported on the edge of the recess-side surface of the Kiryuro unit and the actuator unit is the recess is formed so as to approximately 10μm protrude from the surface of the channel unit.

A method for manufacturing a liquid discharge head according to the present invention includes: a common liquid chamber to which liquid is supplied; and a flow path unit in which a plurality of individual liquid flow paths are formed from an outlet of the common liquid chamber to a nozzle through a pressure chamber. An actuator unit fixed to the surface of the flow path unit and for discharging liquid from the nozzle, wherein the piezoelectric layer is disposed between the piezoelectric layer, the individual electrode disposed on the piezoelectric layer, and the individual electrode. A method of manufacturing a liquid discharge head having an actuator unit having a common electrode to be sandwiched, the surface of the flow path unit having a size and shape that can accommodate the actuator unit on the surface, The flow path unit is formed such that a recess having a depth smaller than the thickness of the actuator unit and the pressure chamber disposed on the bottom surface of the recess are formed. A channel unit manufacturing step of manufacturing a and the actuator unit manufacturing step of manufacturing the actuator unit, the bottom surface of the recess, and a fixing step of fixing the actuator unit to face the pressure chamber. In the fixing step, the pair of pressure members includes a surface of the actuator unit disposed on a bottom surface of the recess via an adhesive and a surface opposite to the surface of the flow path unit on which the recess is formed. By pressing while pinching, the actuator unit is fixed to the bottom surface of the recess, and at least a part of the region of the pressurizing member that pressurizes the actuator unit is not in contact with the actuator unit. It is supported by the edge part of the said depression side of the surface.

  According to the present invention, since the actuator unit is fixed in the recess formed on the surface of the flow path unit, when the actuator unit is fixed to the flow path unit, it is in contact with the actuator unit of the pressure member that presses the actuator unit. At least a portion of the unexposed area is supported by the edge of the depression. For this reason, it is suppressed that the said area | region curves in the press direction from the corner | angular part of an actuator unit, and the stress which acts on the said corner | angular part is relieved. Thereby, it can suppress that an actuator unit is damaged.

In the method for manufacturing a liquid discharge head according to the present invention, the fixing step includes a sandwiching step of sandwiching the actuator unit and the flow path unit stacked with the adhesive between the pair of pressure members, and the actuator unit. And an adhesive curing step of curing the adhesive by heating and pressurizing the flow path unit to a predetermined temperature, and the pressure member on the actuator unit side is not in contact with the actuator unit The partial region is opposed to the edge of the surface of the flow path unit on the depression side in the clamping step, and a larger pressing force than the clamping step is applied to the pressurizing member in the curing step. It is preferable to be applied to and supported by the edge portion on the depression side.

  In the liquid discharge head manufacturing method of the present invention, in the flow path unit manufacturing step, the pressure chamber that opens to the bottom surface of the recess, a wall that defines the pressure chamber, and an edge on the opening side of the wall It is preferable that a plurality of escape recesses are formed to escape inclusions interposed between the actuator unit and the wall portion, which are disposed in a region excluding the portion.

  According to these, inclusions that are impurities adhering to the surface fixed to the flow path unit of the actuator unit can escape to the recess, so that when the actuator unit is pressurized toward the flow path unit, It is possible to prevent the stress from being partially concentrated. Thereby, it can suppress that an actuator unit is damaged.

In the present invention, in the curing step, when the actuator unit and the flow path unit are heated to the predetermined temperature, the temperature is raised to the predetermined temperature before the adhesive is completely cured, and at the predetermined temperature. It is preferable that a pressing force larger than that in the clamping step is applied to the pressing member. Further, a pressing force larger than that in the sandwiching step may be applied until the adhesive is completely cured. Further, the pressure member on the actuator unit side includes a metal pressure jig and an elastic member sandwiched between the pressure jig and the actuator unit, and the actuator unit and the flow path in the curing step When the unit is pressurized at the predetermined temperature, the elastic member may be supported by an edge on the depression side. In the fixing step, the pressure member may heat the actuator unit. Further, in the flow path unit manufacturing process, the recess may be formed with a depth of half or more of the thickness of the actuator unit. At this time, in the curing step, the actuator unit may be fixed so as to protrude about 10 μm from the surface of the flow path unit.

In the present invention, before Kiryuro unit manufacturing step, the escape recess may be formed by sandblasting. In addition, in the flow path unit manufacturing process, the relief recess may be formed by etching. According to these, the escape recess can be efficiently formed.

  According to the present invention, since the actuator unit is fixed in the recess formed on the surface of the flow path unit, when the actuator unit is fixed to the flow path unit, it is in contact with the actuator unit of the pressure member that presses the actuator unit. At least a portion of the unexposed area is supported by the edge of the depression. For this reason, it is suppressed that the said area | region curves in the press direction from the corner | angular part of an actuator unit, and the stress which acts on the said corner | angular part is relieved. Thereby, it can suppress that an actuator unit is damaged.

1 is a cross-sectional view of an inkjet printer according to an embodiment of the present invention. It is sectional drawing along the width direction of the inkjet head shown in FIG. It is sectional drawing regarding the III-III line | wire shown in FIG. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG. It is sectional drawing of the VV line shown in FIG. It is a figure for demonstrating the actuator unit shown in FIG. It is a top view of the plate used as the surface of the flow-path unit shown in FIG. It is sectional drawing of the VIII-VIII line shown in FIG. FIG. 8 is a partially enlarged plan view of the bottom surface of the recess shown in FIG. 7. It is process drawing which concerns on the manufacturing method of the inkjet head shown in FIG. It is a fragmentary sectional view of an actuator unit and a channel unit in the fixing process shown in FIG. It is a figure for demonstrating a modification. It is a figure for demonstrating a modification. It is a figure for demonstrating a modification.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the internal configuration of an ink jet printer according to a preferred embodiment of the present invention. As shown in FIG. 1, the ink jet printer 101 has a rectangular parallelepiped housing 1a. In addition, a paper discharge unit 31 is provided at the top of the housing 1a. Furthermore, the inside of the housing 1a is divided into three spaces A, B, and C in order from the top. In the space A, four inkjet heads 1 and a transport unit 20 that respectively eject magenta, cyan, yellow, and black inks are arranged. Spaces B and C are spaces in which a paper feed unit 1b and an ink tank unit 1c that can be attached to and detached from the housing 1a are arranged. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction.

  Inside the ink jet printer 101, a paper transport path for transporting the paper P from the paper feed unit 1b toward the paper discharge unit 31 is formed (thick arrow in FIG. 1). The sheet feeding unit 1 b includes a sheet feeding tray 23 that can store a plurality of sheets P, and a sheet feeding roller 25 attached to the sheet feeding tray 23. The paper feed roller 25 sends out the uppermost paper P among the plurality of papers P stacked and stored in the paper feed tray 23. The paper P delivered by the paper feed roller 25 is guided to the guides 27 a and 27 b and is fed to the transport unit 20 while being sandwiched by the feed roller pair 26.

  The transport unit 20 includes two belt rollers 6, 7, an endless transport belt 8 wound so as to be bridged between both rollers 6, 7, and a tension roller 10. The tension roller 10 applies tension to the conveyor belt 8 by being urged downward in the lower loop of the conveyor belt 8 while being in contact with the inner peripheral surface thereof. The belt roller 7 is a driving roller, and rotates clockwise in FIG. 1 when a driving force is applied from the transport motor M through two gears. The belt roller 6 is a driven roller, and rotates clockwise in FIG. 1 as the conveyor belt 8 travels as the belt roller 7 rotates.

  The outer peripheral surface 8a of the conveyor belt 8 is subjected to silicone treatment and has adhesiveness. A nip roller 4 is disposed at a position facing the belt roller 6 with the conveyance belt 8 interposed therebetween on the paper conveyance path. The nip roller 4 presses the sheet P sent out from the sheet feeding unit 1 b against the outer peripheral surface 8 a of the transport belt 8. The paper P pressed against the outer peripheral surface 8a is conveyed rightward in FIG. 1 while being held on the outer peripheral surface 8a by the adhesive force.

  Further, a peeling plate 5 is provided at a position facing the belt roller 7 with the conveyance belt 8 interposed therebetween on the paper conveyance path. The peeling plate 5 peels the paper P held on the outer peripheral surface 8a of the transport belt 8 from the outer peripheral surface 8a. The paper P peeled off from the outer peripheral surface 8a by the peeling plate 5 is conveyed while being guided by the guides 29a and 29b and sandwiched between the two pairs of feed rollers 28, and discharged from an opening 30 formed in the upper part of the housing 1a. It is discharged to the part 31.

  The four inkjet heads 1 each extend along the main scanning direction, are arranged in parallel in the sub-scanning direction, and are supported by the housing 1 a via the frame 3. That is, the ink jet printer 101 is a line type color ink jet printer in which an ejection region extending in the main scanning direction is formed. The lower surface of each inkjet head 1 is an ejection surface 2a from which ink droplets are ejected.

  A platen 19 is disposed in the loop of the conveyor belt 8 so as to face the four inkjet heads 1. The upper surface of the platen 19 is in contact with the inner peripheral surface of the upper loop of the conveyor belt 8 and supports it from the inner peripheral side of the conveyor belt 8. Thereby, the outer peripheral surface 8a of the upper loop of the conveying belt 8 and the lower surface of the inkjet head 1, that is, the discharge surface 2a are parallel to each other, and between the discharge surface 2a and the outer peripheral surface 8a of the conveying belt 8. A slight gap is formed. The gap constitutes a part of the paper transport path. When the paper P conveyed while being held on the outer peripheral surface 8a of the conveyor belt 8 passes immediately below the four heads 1, ink of each color is sequentially ejected from each head 1 toward the upper surface of the paper P. A desired color image is formed on the paper P.

  Each inkjet head 1 is connected to an ink tank 49 in an ink tank unit 1c mounted in the space C. That is, the ink ejected by the corresponding inkjet head 1 is stored in each of the four ink tanks 49. Then, ink is supplied from each ink tank 49 to the inkjet head 1 via a tube (not shown) or the like.

  Next, the inkjet head 1 will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view along the sub-scanning direction that is the width direction of the inkjet head 1. FIG. 3 is a cross-sectional view of the ink-jet head 1 taken along the line III-III shown in FIG. In FIG. 3, the lower housing 82 is omitted.

  As shown in FIG. 2, the inkjet head 1 includes a reservoir body 71, a head body 2 including a flow path unit 9 and an actuator unit 21, one end connected to the actuator unit 21, and a driver IC 52 mounted thereon. It has a COF (Chip On Film: flat flexible substrate) 50 and a control substrate 54 connected to the other end of the COF 50. The inkjet head 1 is a laminated structure in which the reservoir unit 71 is laminated on the flow path unit 9 with the actuator unit 21 interposed therebetween, and the control substrate 54 is disposed on the reservoir unit 71. Furthermore, the inkjet head 1 includes an upper casing 81 and a lower casing 82 that form a box surrounding the reservoir unit 71 and the flow path unit 9, and a head cover 55 that surrounds the control substrate 54 above the upper casing 81. have.

  The reservoir unit 71 is fixed to the upper surface of the head body 2 and supplies ink to the head body 2. The reservoir unit 71 includes four plates 91 to 94 that are aligned and stacked with each other, and an ink inflow channel (not shown), an ink reservoir 72, and 10 inks are provided therein. The outflow channels 73 are formed so as to communicate with each other. In FIG. 2, only one ink outflow channel 73 appears. Ink from the ink tank 49 flows into the ink inflow channel. The ink reservoir 72 temporarily stores the ink flowing from the ink inflow channel. The ink outflow channel 73 communicates with an ink supply port 105 b formed on the upper surface of the channel unit 9. Ink from the ink tank 49 flows into the ink reservoir 72 through the ink inflow channel, passes through the ink outflow channel 73, and is supplied into the channel unit 9 from the ink supply port 105b.

  Further, a recess 94 a is formed on the lower surface of the plate 94. The recess 94 a forms a gap 90 with the upper surface of the flow path unit 9. In the gap 90, four actuator units 21 fixed to the upper surface of the flow path unit 9 are arranged in a staggered manner at equal intervals along a center line extending in the longitudinal direction with respect to the laminate (inkjet head 1). Yes. In addition, the gap 90 has four openings 90 a formed on the side surface of the stacked body so as to be alternately arranged along the longitudinal direction of the reservoir unit 71 with the center line interposed therebetween.

  Further, the lower surface of the plate 94 has a convex portion (a portion other than the concave portion 94 a) bonded to the flow path unit 9. The reservoir 72 and the ink supply port 105b communicate with each other through an ink outflow channel 73 formed in the convex portion.

  The vicinity of one end of the COF 50 is connected to the upper surface of the actuator unit 21. Further, the COF 50 extends from the upper surface of the actuator unit 21 in the horizontal direction, passes through the opening 90a, and is then bent so as to be bent at a substantially right angle upward. It passes through a notch 53 formed in the wall surface and is drawn above the reservoir unit 71. Further, the COF 50 extends to the left in FIG. 2 above the reservoir unit 71, and is then pulled out from the slit 81 a formed in the upper housing 81 to the upper housing 81. The other end of the COF 50 is connected to the control board 54 via the connector 54a above the upper casing 81. A driver IC 52 mounted in the middle of the COF 50 is attached to the upper surface of the reservoir unit 71, and the driver IC 52 and the reservoir unit 71 are thermally coupled. As a result, the heat generated from the driver IC 52 is transmitted to the reservoir unit 71 and the internal ink is warmed and the viscosity of the ink is suppressed from increasing.

  The control board 54 is disposed above the upper casing 81 and controls driving of the actuator unit 21 via the driver IC 52 of the COF 50. The driver IC 52 generates a drive signal for driving the actuator unit 21. The control board 54 is provided with a plurality of electronic components, and when the ink is contaminated, an electrical failure such as a short circuit occurs. However, as shown in FIG. 2, the control board 54 is disposed in the space between the upper housing 81 and the head cover 55, and is protected from the ingress of ink and ink mist from the outside.

  Further, the head body 2 will be described with reference to FIGS. FIG. 4 is an enlarged view of a region surrounded by a one-dot chain line in FIG. In FIG. 4, for convenience of explanation, the pressure chamber 110, the aperture 112, and the nozzle 108 that are to be drawn by broken lines below the actuator unit 21 are drawn by solid lines. FIG. 5 is a partial cross-sectional view taken along line VV shown in FIG. 6A is an enlarged cross-sectional view of the actuator unit 21, and FIG. 6B is a plan view showing individual electrodes arranged on the surface of the actuator unit 21 in FIG. 6A.

  As shown in FIG. 3, the head body 2 includes a flow path unit 9 and four actuator units 21 fixed to the upper surface 9 a of the flow path unit 9. As shown in FIGS. 3 and 4, the flow path unit 9 has an ink flow path including a pressure chamber 110 and the like formed therein. The actuator unit 21 includes a plurality of actuators corresponding to the pressure chambers 110, and has a function of selectively giving ejection energy to the ink in the pressure chambers 110.

  The flow path unit 9 has a rectangular parallelepiped shape that has substantially the same planar shape as the plate 94 of the reservoir unit 71. On the upper surface 9a of the flow path unit 9, four recesses 122a arranged in a staggered manner and at equal intervals along a center line extending in the longitudinal direction are formed, and the actuator unit 21 is fixed in each recess 122a. (See FIG. 7). Details of the recess 122a will be described later. Further, a total of ten ink supply ports 105 b are opened on the upper surface 9 a of the flow path unit 9 corresponding to the ink outflow flow path 73 (see FIG. 2) of the reservoir unit 71. As shown in FIGS. 3 and 5, a manifold channel 105 communicating with the ink supply port 105 b and a sub-manifold channel 105 a branched from the manifold channel 105 are formed inside the channel unit 9. As shown in FIGS. 4 and 5, a discharge surface 2a in which a large number of nozzles 108 are arranged in a matrix is formed on the lower surface of the flow path unit 9. A large number of pressure chambers 110 are also arranged in a matrix like the nozzles 108 on the fixed surface of the actuator unit 21 in the flow path unit 9.

  In the present embodiment, 16 rows of pressure chambers 110 arranged in the longitudinal direction of the flow path unit 9 at equal intervals are arranged in parallel to each other in the width direction. The number of pressure chambers 110 included in each pressure chamber row corresponds to the outer shape (trapezoidal shape) of an actuator unit 21 described later, from the long side (lower base side) to the short side (upper base side). It arrange | positions so that it may decrease gradually toward it. The nozzle 108 is also arranged in the same manner.

  As shown in FIG. 5, the flow path unit 9 includes nine metal plates 122 to 130 made of stainless steel. By laminating these plates 122 to 130 while being aligned with each other, the nozzle 108 in the flow path unit 9 passes from the manifold flow path 105 to the sub manifold flow path 105a and from the outlet of the sub manifold flow path 105a through the pressure chamber 110. A large number of individual ink channels 132 are formed.

  The ink flow in the flow path unit 9 will be described. As shown in FIGS. 3 to 5, the ink supplied from the reservoir unit 71 into the flow path unit 9 through the ink supply port 105 b is distributed from the manifold flow path 105 to the sub-manifold flow path 105 a. The ink in the sub-manifold channel 105a flows into each individual ink channel 132 and reaches the nozzle 108 through the aperture 112 and the pressure chamber 110 functioning as a throttle.

  Next, the actuator unit 21 will be described. As shown in FIG. 6A, the actuator unit 21 includes three piezoelectric sheets 141 to 143 made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity. An individual electrode 135 is formed at a position facing the pressure chamber 110 on the upper surface of the uppermost piezoelectric sheet 141. A common electrode 134 formed on the entire surface of the sheet is interposed between the uppermost piezoelectric sheet 141 and the lower piezoelectric sheet 142. As shown in FIG. 6B, the individual electrode 135 has a substantially rhombic planar shape similar to the pressure chamber 110. In plan view, most of the individual electrodes 135 are in the region of the pressure chamber 110. One of the acute angle portions of the substantially rhomboid individual electrode 135 extends outside the pressure chamber 110, and an individual bump 136 electrically connected to the individual electrode 135 is provided at the tip thereof.

  The common electrode 134 is equally grounded in the region corresponding to all the pressure chambers 110. On the other hand, the individual electrode 135 is electrically connected to each output terminal of the driver IC 52 via the COF 50, and a drive signal from the driver IC 52 is selectively supplied. The common electrode 134 is connected to a common electrode bump formed on the upper surface of the piezoelectric sheet 141 through a through hole. Further, the common electrode bump is connected to the control substrate 54 via the COF 50.

  Here, a driving method of the actuator unit 21 will be described. The piezoelectric sheet 141 is polarized in the thickness direction. When an electric field is applied in the polarization direction to the piezoelectric sheet 141 by setting the individual electrode 135 to a potential different from that of the common electrode 134, the electric field application portion of the piezoelectric sheet 141 functions as an active portion that is distorted by the piezoelectric effect. That is, in the actuator unit 21, a portion sandwiched between the individual electrode 135 and the pressure chamber 110 functions as an individual actuator, and a plurality of actuators corresponding to the number of the pressure chambers 110 are formed. For example, if the polarization direction is the same as the electric field application direction, the active portion contracts in a direction (plane direction) perpendicular to the polarization direction. That is, the actuator unit 21 uses the upper one piezoelectric sheet 141 away from the pressure chamber 110 as a layer including an active portion, and the lower two piezoelectric sheets 142 and 143 close to the pressure chamber 110 as inactive layers. It is a so-called unimorph type actuator. As shown in FIG. 6A, since the piezoelectric sheets 141 to 143 are fixed to the upper surface of the plate 122 that partitions the pressure chamber 110, the electric field application portion of the piezoelectric sheet 141 and the piezoelectric sheets 142 and 143 below the electric field applying portion. If there is a difference in the strain in the plane direction, the entire piezoelectric sheets 141 to 143 are deformed so as to be convex toward the pressure chamber 110 (unimorph deformation). As a result, pressure (discharge energy) is applied to the ink in the pressure chamber 110, and an ink droplet is discharged from the nozzle 108.

  In the present embodiment, a predetermined potential is applied to the individual electrode 135 in advance, and the individual electrode 135 is once set to the ground potential every time there is an ejection request, and then the individual electrode 135 is again set to the predetermined potential at a predetermined timing. A drive signal for applying a potential is output from the driver IC 52. In this case, the piezoelectric sheets 141 to 143 return to the original state at the timing when the individual electrode 135 becomes the ground potential, and the volume of the pressure chamber 110 increases as compared with the initial state (a state in which a voltage is applied in advance). Ink is sucked from the manifold channel 105 a into the individual ink channel 132. After that, at the timing when a predetermined potential is applied to the individual electrode 135 again, the piezoelectric sheets 141 to 143 are deformed so that the portions facing the active region protrude toward the pressure chamber 110, and the ink is reduced due to the volume reduction of the pressure chamber 110. The pressure increases, and ink is ejected from the nozzle 108.

  Next, the positional relationship between the flow path unit 9 and the actuator unit 21 will be described in detail with reference to FIGS. FIG. 7 is a plan view of the plate 122 serving as the upper surface 9 a of the flow path unit 9. 8 is a cross-sectional view taken along line VIII-VIII shown in FIG. FIG. 8 shows a state in which the actuator unit 21 is fixed in the recess 122a. In addition, the pressure chamber 110 is schematically depicted so as to continuously appear in the cross section. FIG. 9 is a partially enlarged plan view of the bottom surface 122b of the recess 122a shown in FIG.

  As shown in FIGS. 3 and 7, the recess 122a formed in the upper surface 9a of the flow path unit 9 has a trapezoidal shape with a plane size that can accommodate the actuator unit 21, and the bottom surface 122b is heated. The actuator unit 21 is fixed via a curable adhesive. Further, as shown in FIG. 8, the depth of the recess 122 a is smaller than the thickness of the actuator unit 21. For this reason, the actuator unit 21 protrudes from the upper surface 9a of the flow path unit 9 (plate 122). In the present embodiment, the protruding height of the actuator unit 21 from the upper surface 9a is not more than half of the thickness of the actuator unit 21, and is about a quarter of the thickness. The actuator unit 21 has a thickness of about 40 μm, and about 10 μm protrudes from the upper surface 9a.

  As shown in FIGS. 7 to 9, a plurality of pressure chambers 110 defined by the walls 110 a are opened on the bottom surface 122 b of the recess 122 a, and the actuator unit 21 (individual electrode 135) is opened in the pressure chamber 110. It is fixed so as to face. An annular groove 122c extending along the outer shape of the actuator unit 21 is formed further inside the region supporting the edge of the actuator unit 21 on the bottom surface 122b.

  A plurality of escape recesses 122d are formed in the region excluding the edge 110b on the opening side of the pressure chamber 110 in the wall 110a and the region supporting the edge of the actuator unit 21 on the bottom surface 122b. The relief recess 122d is a narrow groove formed in a comb-like shape extending in the vertical direction in FIG. Thereby, the inclusions that are about to intervene between the actuator unit 21 and the wall portion 110a can escape into the escape recess 122d and the annular groove 122c. The inclusions are impurities (foreign matter) adhering to the surface of the actuator unit 21 in the actuator manufacturing process for manufacturing the actuator unit 21. In addition, since the relief portion 122d is not formed in the edge portion 110b on the opening side of the pressure chamber 110 in the wall portion 110a, thermosetting adhesion is performed in a fixing step (described later) for fixing the actuator unit 21 to the bottom surface 122b. It is possible to prevent the agent from flowing into the pressure chamber 110. Further, even if a foreign object is sandwiched between the actuator unit 21 and the wall portion 110a, the actuator unit 21 does not suffer from problems such as local stress concentration and cracks.

  A method for manufacturing the inkjet head 1 will be described with reference to FIG. FIG. 10 is a process diagram according to the method for manufacturing the inkjet head 1. As shown in FIG. 10, the method for manufacturing the inkjet head 1 includes a flow path unit manufacturing process, an actuator unit manufacturing process, and a fixing process. In the flow path unit manufacturing process, first, the above-described plates 122 to 130 are formed by etching. At this time, a recess 122a is formed on the upper surface of the plate 122, and an annular groove 122c, a pressure chamber 110, and an escape recess 122d are formed on the bottom surface 122b of the recess 122a. And these plates 122-130 are joined with an adhesive agent, aligning each other, and the flow path unit 9 is formed.

  Note that a plurality of etching processes are performed for processing the plate 122. In the first etching process, a resist is applied to the entire surface of the plate 122. On one surface of the plate 122, the resist is exposed, leaving a portion where the actuator unit 21 is disposed. After the exposure, the unexposed portion of the resist is peeled off by the developer, and the exposed portion becomes an etching mask. In this state, the plate 122 is etched. The etching depth is about 30 μm. Thereafter, the mask is removed with a stripping solution to complete the first etching process. Thereby, the original shape of the recess 122a is formed.

  Subsequently, in the second etching process, a resist is again applied to the entire surface of the plate 122. On the surface where the recess 122a is formed, the resist is exposed, leaving a portion where the annular groove 122c and the relief recess 122d are formed. After the exposure, the unexposed portion of the resist is peeled off by the developer, and the exposed portion becomes an etching mask. In this state, the plate 122 is etched. The etching depth is about 1 μm. Thereafter, the mask is removed with a stripping solution, and the second etching process is completed. As a result, an annular groove 122c and an escape recess 122d are formed on the bottom surface of the recess 122a.

  Further, in the final etching process, a resist is applied again on the entire surface of the plate 122. On the surface opposite to the surface where the recess 122a is formed, the resist is exposed, leaving a portion where the pressure chamber 110 is formed. After the exposure, the unexposed portion of the resist is peeled off by the developer, and the exposed portion becomes an etching mask. In this state, the plate 122 is etched. The etching depth is a depth that penetrates the bottom of the recess 122a. Thereafter, the mask is removed with a stripping solution to complete the last etching process. As a result, the pressure chamber 110 is formed on the bottom surface of the recess 122a.

  In the actuator unit manufacturing process, the individual sheets 135 are arranged on the upper surface of the piezoelectric sheet 141, and the green sheets that become the piezoelectric sheets 141 to 143 are arranged so that the common electrode 134 is arranged between the piezoelectric sheets 141 and 142. Are sequentially laminated to form the actuator unit 21. Here, each electrode is formed by a screen printing method.

  Next, the fixing process will be described with reference to FIG. FIG. 11 is a partial cross-sectional view of the actuator unit 21 and the flow path unit 9 in the fixing process. As shown in FIG. 11, in the fixing step, first, the actuator unit 21 having the lower surface coated with a thermosetting adhesive is disposed on the bottom surface 122b of the recess 122a. At this time, the individual electrode 135 is disposed to face the pressure chamber 110. Then, the surface of the actuator unit 21 and the discharge surface 2a of the flow path unit 9 (the surface opposite to the surface on which the recess 122a is formed) are pressurized while being sandwiched between a pair of pressure members. One pressure member 60 includes a metal pressure jig 61 attached to an actuator (not shown), and an elastic member 62 fixed to the surface of the pressure jig 61 close to the actuator unit 21. . When sandwiched, the elastic member 62 faces the edge of the upper surface 9a of the flow path unit 9 on the side of the recess 122a. The pressurizing member 60 is provided with a heater (not shown) so that the actuator unit 21 can be pressurized while being heated. The other pressing member (not shown) is in contact with the ejection surface 2a. A heater is also attached to the other pressure member.

  In this state, the actuator unit 21 is heated while being pressurized toward the bottom surface 122b until the region of the pressure member 60 that is not in contact with the actuator unit 21 is supported by the edge of the recess 122a. Thereby, the thermosetting adhesive is cured and the actuator unit 21 is fixed to the bottom surface 122b.

  In the present embodiment, first, when the pair of pressure members are sandwiched to the extent that they are in contact with the actuator unit 21 and the flow path unit 9, both are heated to a predetermined temperature. In this state, a large pressing force is not applied, and the elastic member 62 is separated from the upper surface 9a at the edge of the upper surface 9a on the recess 122a side. The pair of pressure members may be heated to a predetermined temperature in advance. By this heat treatment, the adhesive begins to cure, but the heating conditions are adjusted so that the actuator unit 21 and the flow path unit 9 reach a predetermined temperature before being completely cured. Thereby, the actuator unit 21 and the flow path unit 9 are in a state of extending according to their respective thermal expansion coefficients. Here, a large pressure is applied.

  At this time, the area of the pressure member 60 that pressurizes the actuator unit 21 that is not in contact with the actuator unit 21 tends to bend in the pressing direction starting from the corner of the actuator unit 21, but the area is the edge of the recess 122a. Therefore, the bending of the pressure member 60 is suppressed. In FIG. 11, both end regions of the pressure member 60 that are not in contact with the actuator unit 21 are curved downward, but the actual degree of bending is as shown in FIG. 11. It is much smaller. Furthermore, the degree of bending is much smaller than when the actuator unit 21 is disposed on the upper surface 9a, and the stress applied to the corners is also small. Therefore, damage such as chipping and cracking does not occur at the corners. Further, since the annular groove 122c and the escape recess 122d are formed at the bottom of the recess 122a so as to avoid the opening of the pressure chamber 110, a foreign object is trapped when the actuator unit 21 is disposed in the recess 122a. However, the foreign matter enters the annular groove 122c and the escape recess 122d. As a result, the actuator unit 21 is not damaged due to the presence of foreign matter.

  If the pressurization is continued, the adhesive is completely cured. At this time, the applied pressure is released and the laminate is cooled at a predetermined speed. This completes the fixing process. In addition, when a laminated body is cooled, a compressive stress will arise in the actuator unit 21 corresponding to the difference in the thermal expansion coefficient of the actuator unit 21 and the flow path unit 9, and a discharge characteristic will improve.

  Thereafter, the COF 50 is connected to the actuator unit 21, and various electrical components including the reservoir unit 71, the control board 54, the upper casing 81, the lower casing 82, and the head cover 55 are assembled to complete the inkjet head 1.

  As described above, according to the ink jet head 1 according to the present embodiment, since the actuator unit 21 is fixed in the recess 122a formed in the upper surface 9a of the flow path unit 9, the actuator unit 21 is passed through the flow path in the fixing process. When fixing to the unit 9, the area | region which is not in contact with the actuator unit 21 in the pressurization member 60 which pressurizes the actuator unit 21 is supported by the edge of the hollow 122a. For this reason, bending in the pressing direction starting from the corner of the actuator unit 21 is suppressed, and stress acting on the corner is alleviated. Thereby, it is possible to prevent the actuator unit 21 from being damaged.

  In addition, since a plurality of escape recesses 122d are formed on the bottom surface 122b of the recess 122a, inclusions that are about to intervene between the actuator unit 21 and the wall portion 110a can escape into the escape recess 122d. For this reason, in the fixing step, when the actuator unit 21 is pressurized toward the bottom surface 122b, it is possible to prevent stress from being partially concentrated on the actuator unit 21, and to prevent the actuator unit 21 from being damaged. Can do.

  Furthermore, since the relief recess 122d is not formed in the region supporting the edge of the actuator unit 21 on the bottom surface 122b of the recess 122a, the edge of the actuator unit 21 is reliably supported and the actuator unit 21 is damaged. Can be further suppressed.

  In addition, since a plurality of escape recesses 122d are formed in a comb-like shape on the bottom surface 122b of the recess 122a, the inclusions to be interposed between the actuator unit 21 and the wall portion 110a are efficiently contained in the escape recess 122d. I can escape well.

  Furthermore, in the flow path unit forming step, the escape recess 122d is formed by etching, and therefore the escape recess 122d can be efficiently formed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. In the above-described embodiment, the plurality of escape recesses 122d are formed on the bottom surface 122b of the recess 122a. However, the escape recesses 122d may not be formed.

  In the above-described embodiment, the plurality of relief recesses 122d are formed in a comb-teeth shape on the bottom surface 122b of the recess 122a. However, as shown in FIG. 12, a plurality of relief recesses that are narrow grooves are provided. 222d may be formed in a mesh shape (lattice shape). Further, as shown in FIG. 13, a plurality of escape recesses 322d having a circular opening may be formed so as to be uniformly distributed on the bottom surface 122b, or a substantially rectangular opening as shown in FIG. A plurality of relief recesses 322d having the shape may be formed in a staggered matrix so as to be uniformly distributed on the bottom surface 122b. As described above, as long as irregularities are formed on the bottom surface 122b, the shape may be arbitrary.

  Furthermore, in the above-described embodiment, the relief recess 122d is formed by etching, but may be formed by other processing methods such as sandblasting.

  In the embodiment described above, the actuator unit 21 is a unimorph type actuator, but the configuration of the actuator may be arbitrary. For example, the actuator unit may be a stacked actuator that uses longitudinal vibration.

  The recording head according to the present invention is not limited to the line type, and can also be applied to a serial type recording head in which the head reciprocates and a recording head that discharges liquid other than ink. Further, the present invention is not limited to a printer, and can be applied to a facsimile, a copier, and the like.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Head main body 2a Discharge surface 9 Flow path unit 9a Upper surface 21 Actuator unit 60 Pressurizing member 61 Pressurizing jig 62 Elastic member 101 Inkjet printer 110 Pressure chamber 110a Wall portion 110b Edge portion 122 Plate 122a Depression 122b Bottom surface 122c Groove 122d relief recess

Claims (12)

A common liquid chamber to which liquid is supplied, a flow path unit in which a plurality of individual liquid flow paths are formed from the outlet of the common liquid chamber to the nozzle through the pressure chamber, and is fixed to the surface of the flow path unit, An actuator unit that discharges liquid from the nozzle, the actuator unit including a piezoelectric layer, individual electrodes arranged on the piezoelectric layer, and a common electrode that sandwiches the piezoelectric layer between the individual electrodes. A method for manufacturing a liquid ejection head, comprising:
On the surface of the flow path unit, the planar shape has a size and a shape that can accommodate the actuator unit, and a depth is smaller than a thickness of the actuator unit, and a bottom surface of the recess is disposed. A flow path unit manufacturing process for manufacturing the flow path unit so that the pressure chamber is formed;
An actuator unit manufacturing process for manufacturing the actuator unit;
A fixing step of fixing the actuator unit on the bottom surface of the depression so as to face the pressure chamber ;
In the fixing step,
A pair of pressurizing members pressurize the surface of the actuator unit disposed on the bottom surface of the recess and an opposite surface to the surface of the flow path unit on which the recess is formed via an adhesive. By fixing the actuator unit to the bottom of the recess,
At least a part of a region of the pressure member that pressurizes the actuator unit that is not in contact with the actuator unit is supported by an edge of the surface of the flow path unit on the depression side. Manufacturing method.   The fixing step includes
  A sandwiching step of sandwiching the actuator unit and the flow path unit stacked via the adhesive with the pair of pressure members;
  A curing step of an adhesive that cures the adhesive by heating and pressurizing the actuator unit and the flow path unit to a predetermined temperature,
  The pressurizing member on the actuator unit side is opposed to the part of the area that is not in contact with the actuator unit, spaced apart from the dent on the surface of the flow path unit in the clamping step, 2. The method of manufacturing a liquid ejection head according to claim 1, wherein in the curing step, a pressing force larger than that in the sandwiching step is applied to the pressure member and supported by the edge portion on the depression side.   In the curing step, when the actuator unit and the flow path unit are heated to the predetermined temperature, the temperature is raised to the predetermined temperature before the adhesive is completely cured, and at the predetermined temperature from the clamping step. The method of manufacturing a liquid ejection head according to claim 2, wherein a larger pressing force is applied to the pressing member.   4. The method of manufacturing a liquid ejection head according to claim 2, wherein a pressing force larger than that in the sandwiching step is applied until the adhesive is completely cured.   The pressure member on the actuator unit side includes a metal pressure jig, an elastic member sandwiched between the pressure jig and the actuator unit, and the actuator unit and the flow path unit in the curing step. 5. The method of manufacturing a liquid ejection head according to claim 2, wherein when the pressure is applied at the predetermined temperature, the elastic member is supported by an edge portion on the depression side. 6. The method of manufacturing a liquid ejection head according to claim 2, wherein, in the fixing step, the pressure member heats the actuator unit. 7.   The liquid discharge head manufacturing method according to claim 1, wherein in the flow path unit manufacturing step, the recess is formed with a depth of half or more of a thickness of the actuator unit. Method.   8. The method of manufacturing a liquid ejection head according to claim 7, wherein in the curing step, the actuator unit is fixed so as to protrude from the surface of the flow path unit by about 10 [mu] m. In the flow path unit manufacturing process, the actuator disposed in a region excluding the pressure chamber opening in the bottom surface of the recess, a wall portion defining the pressure chamber, and an edge portion on the opening side of the wall portion. method for manufacturing a liquid discharge head according to any one of claims 1-8, wherein a plurality of relief recesses are formed to release the inclusions interposed between the unit and the wall portion. The method for manufacturing a liquid discharge head according to claim 9 , wherein in the flow path unit manufacturing step, the escape recess is formed by sandblasting.   The method for manufacturing a liquid discharge head according to claim 9, wherein in the flow path unit manufacturing step, the relief recess is formed by etching. A common liquid chamber to which liquid is supplied, and a flow path unit in which a plurality of individual liquid flow paths from the outlet of the common liquid chamber to the nozzle through the pressure chamber are formed,
An actuator unit that is fixed to the surface of the flow path unit and discharges liquid from the nozzle, and sandwiches the piezoelectric layer between the piezoelectric layer, the individual electrode disposed on the piezoelectric layer, and the individual electrode And an actuator unit having a common electrode
On the surface of the flow path unit, the planar shape has a size and shape that can accommodate the actuator unit, and a recess whose depth is more than half of the thickness of the actuator unit is formed. ,
The pressure chamber is formed on the bottom surface of the recess, and the actuator unit is fixed to face the pressure chamber ,
A pair of pressurizing members pressurize the surface of the actuator unit disposed on the bottom surface of the recess and an opposite surface to the surface of the flow path unit on which the recess is formed via an adhesive. The actuator unit is fixed to the bottom surface of the recess,
The actuator unit is configured such that at least a part of a region of the pressure member that pressurizes the actuator unit that is not in contact with the actuator unit is supported by an edge of the surface of the flow path unit on the depression side. The liquid discharge head is characterized in that the recess is formed so as to protrude about 10 μm from the surface of the flow path unit .

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