JP4548433B2 - Inkjet head - Google Patents

Description

  The present invention relates to an inkjet head that performs printing by discharging ink droplets.

  As an inkjet head that ejects ink droplets onto a recording medium, a flow path unit having a plurality of individual ink flow channels from a common ink chamber to a nozzle through a pressure chamber, and pressure for ejecting energy for ejecting ink droplets from the nozzle Some have actuators applied to the chamber. As an actuator, for example, a piezoelectric layer made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity is sandwiched between an individual electrode corresponding to each pressure chamber and a common electrode to which a ground potential is applied. Things are used. In such an actuator, the individual electrodes arranged on the surface may be short-circuited due to adhesion of ink droplets. In view of this, there has been known one in which a cover is mounted on a flow path unit so that ink droplets do not adhere to the actuator (for example, see Patent Document 1).

Japanese Patent Laying-Open No. 2005-169839 (FIG. 3)

  From the viewpoint of suppressing ink droplets from entering the ink jet head, it is preferable that the end face of the cover and the flow path unit are completely in close contact with each other. However, a gap may be generated between the end face of the cover and the flow path unit due to the influence of manufacturing errors of the cover. If a gap is generated between the end face of the cover and the flow path unit, ink droplets enter the ink jet head from this gap and cause the ink to adhere to the actuator. Furthermore, when this gap is large, it is difficult to seal the gap using a sealant.

  Therefore, an object of the present invention is to provide an inkjet head that can prevent ink droplets from entering the inkjet head.

  An ink jet head of the present invention is attached to a flow path unit having an ink discharge surface in which a plurality of ink discharge ports for discharging ink droplets are formed, and a mounting surface opposite to the ink discharge surface in the flow path unit. An actuator that generates ejection energy for ejecting ink droplets from the ink ejection port; a longitudinal direction of the flow path unit that extends along an outline of the flow path unit; and the attachment surface; The actuator between the flow path unit and at least one side wall member having a side wall abutting so as to intersect, and at least one side wall member connected to the side wall and facing the mounting surface; And a cover member disposed at a position sandwiching the side wall member. And the said cover member is arrange | positioned so that the said opposing wall of the said side wall member may be pressed toward the said flow path unit.

  According to the present invention, since the cover member is disposed so as to press the opposing wall, the end portion of the side wall is surely brought into contact with the mounting surface of the flow path unit. This makes it difficult for a gap to be formed between the attachment surface of the flow path unit and the side wall plate, and prevents ink droplets from entering and adhering to the actuator from between the attachment surface of the flow path unit and the side wall member. Can do. Therefore, even if there is an error in the positional relationship between the facing wall of the side wall member and the cover member due to manufacturing errors of the cover member or the side wall member, the cover member reliably presses the opposing wall. It is possible to reliably contact the end of this with the mounting surface of the flow path unit.

  In the present invention, it is preferable that the side wall member is elastically deformed between the cover member and the flow path unit. According to this, since the cover member presses the opposing wall so as to elastically deform, the side wall is biased toward the attachment surface of the flow path unit due to the elastic restoring force of the side wall member itself. Thereby, the edge part of a side wall member can be reliably contact | abutted by the attachment surface of a flow-path unit.

  The present invention further includes a driver IC for driving the actuator, the side wall member is formed of a metal material, and the driver IC and the side wall member are thermally coupled. Also good. According to this, since the side wall member also serves as a heat sink for cooling the driver IC, it is possible to reduce the size of the inkjet head.

  Furthermore, in this invention, it is preferable that the boundary area | region of the said attachment surface and the said side wall of the said side wall member is sealed with the potting agent. According to this, it is possible to reliably prevent ink splashes from entering between the flow path unit and the side wall member.

  In addition, in the present invention, a rib that protrudes toward the mounting surface is formed on a surface of the cover member that faces the mounting surface, and a tip of the rib is in contact with the counter wall. Good. According to this, the strength of the cover member can be increased.

  At this time, it is preferable that the tip of the rib has a contour with a curved cross section including an axis in the protruding direction of the rib. According to this, since the tip of the rib and the facing wall abut only in a very narrow range, the positional accuracy of the abutment position is increased, and the abutment force for each end of the rib is made uniform.

  Furthermore, in the present invention, it is more preferable that the tip of the rib is in contact with the vicinity of the tip of the opposing wall in the direction away from the side wall. According to this, since the side wall can be greatly elastically deformed by being pressed by the cover member, even if the positional relationship between the facing wall and the cover member is greatly different due to a manufacturing error of the cover member, etc. Can be reliably brought into contact with the opposing wall.

  In addition, in the present invention, it is more preferable that the side wall member is formed so that a region of the opposing wall that contacts the tip of the rib faces the actuator. According to this, it becomes difficult to produce a clearance gap between the flow path unit nearest to the actuator and the side wall member.

  In the present invention, the cover member has a cover side wall portion extending toward the vicinity of one end of the flow path unit in the short direction, and the cover side wall portion is opposed to the side wall. It is preferable that the wall is in contact with the surface opposite to the connected surface. According to this, the side wall member is prevented from being bent or inclined toward the outer side in the lateral direction, and the adhesion between the side wall member and the cover side wall portion is improved. Thereby, it becomes difficult to produce a clearance gap between a cover member and a side wall member, and it can suppress that an ink splash penetrate | invades in an inkjet head.

  In the present invention, the flow path unit has at least two grooves formed so as to extend from the mounting surface to the middle in the thickness direction of the flow path unit, and the side wall abuts on the mounting surface. It is preferable that the contact surface to be formed and the same number of protrusions as the grooves protruding from the contact surface are provided, and the protrusions are respectively fitted in the grooves. According to this, a side wall member becomes difficult to incline and position shift can be suppressed. For this reason, the side wall member can reliably receive the pressing force from the rib, and the gap is less likely to be generated between the flow path unit and the side wall member. Furthermore, since the attachment position of the side wall member to the flow path unit is clear and accurate, the ink jet head can be easily assembled.

  In the present invention, the side wall has a convex portion extending along the longitudinal direction of the flow path unit while projecting to the outside of the flow path unit with respect to the short side direction, and the mounting surface. You may contact | abut perpendicularly | vertically. According to this, since the strength of the side wall is improved, the pressing force from the cover member can be efficiently transmitted to the mounting surface of the flow path unit.

  Further, in the present invention, it is preferable that the two side wall members are provided, and the two side wall members are respectively disposed in the vicinity of one end and the other end of the flow path unit with respect to the short side direction. According to this, since the side wall members are disposed at both ends in the lateral direction, it is possible to more reliably suppress ink droplets from entering and adhering to the actuator as compared with the case where the sidewall members are disposed only at one side. .

  In the present invention, an ink reservoir that supplies ink to the flow path unit is installed between the flow path unit and the cover member, and the cover member and the ink reservoir are connected to the flow path unit. Each having a facing region facing each other with respect to at least one of the short direction and the longitudinal direction of the ink reservoir, wherein a plurality of recesses are formed in the facing region in the ink reservoir, and in the facing region in the cover member, It is preferable that a plurality of protrusions fitted in the recesses are formed. According to this configuration, since the cover member is securely fixed to the ink reservoir, the cover member reliably presses the side wall member. Therefore, a gap is less likely to occur between the attachment surface of the flow path unit and the side wall member.

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

  FIG. 1 is a schematic perspective view of an inkjet head 100 according to an embodiment of the present invention. FIG. 2 is a perspective view of the inkjet head 100 in a state where the head cover 110 and the heat sink 150 are removed. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. The ink jet head 100 is applied to any character / image recording apparatus using an ink jet system such as an ink jet printer. The inkjet head 100 has a shape that is long in one direction in a plan view. In this embodiment, the main scanning direction is a long direction in the plan view of the inkjet head 100, and the sub-scanning direction is a direction perpendicular to the main scanning direction in the plan view. The downward direction is the ejection direction of ink droplets ejected from the inkjet head 100, and the upward direction is the direction opposite to the downward direction.

  As shown in FIGS. 1 to 3, the inkjet head 100 includes a flow path unit 140 in which an opening of a nozzle (ink discharge port) 8 is formed on the lower surface (ink discharge surface) (see FIG. 9), and the flow path unit 140. An ink reservoir 130 for supplying ink to the head, a head cover (cover member) 110, a heat sink 150, and a control board 170. The control substrate 170, the ink reservoir 130, and the flow path unit 140 are stacked in order from the top to the bottom.

  The head cover 110 will be described with further reference to FIG. FIG. 4 is a perspective view of the head cover 110 viewed from the flow path unit 140 side. As shown in FIGS. 1 and 4, the head cover 110 has a substantially box shape opened downward, and is installed so as to cover the space on the flow path unit 140. An ink supply valve 111 is provided on the upper surface of the head cover 110, and ink is supplied to the ink reservoir 130 through the ink supply valve 111. Further, a large number of ribs 113 are formed on the inner wall surface of the head cover 110 facing the flow path unit 140 so as to have a substantially lattice shape. An actuator unit 120, which will be described later, is attached to the upper surface (attachment surface) of the flow path unit 140, and the rib 113 protrudes downward toward the attachment surface. By forming the rib 113, the rigidity of the head cover 110 is enhanced. Further, a tip end portion 113 a having a convex shape directed further downward is formed at the lower end portion of the rib 113. The distal end portion 113a has a contour with a curved cross section including an axis in the protruding direction of the rib 113.

  The head cover 110 includes side walls (cover side wall portions) 112 extending in the vertical direction toward both side edge portions in the short direction of the flow path unit 140. A rectangular opening 110 a extending in the main scanning direction is formed in the side wall 112. The opening 110a is a notch formed from the lower end of the side wall 112 to the vicinity of the center in the vertical direction. The opening 110 a is for exposing a flat protrusion (convex portion) 150 a formed on the heat sink 150 described later from the head cover 110.

  Four protrusions 114 are formed on the inner surface of the side wall 112. Two of the four protrusions 114 are formed on one side of the side wall 112, and the remaining two are formed on the other side of the side wall 112. FIG. 4 shows only two of the four protrusions 114. On the other hand, as shown in FIG. 2, four concave portions 131a are formed on the lower surface of the upper reservoir 131 described later. FIG. 2 shows only two of the four recesses 131a. These recesses 131 a are formed at positions corresponding to the protrusions 114. The head cover 110 is attached to the inkjet head 100 so that the four protrusions 114 are fitted in the four recesses 131a. As a result, the head cover 110 is fixed to the ink reservoir 130. The head cover 110 may be fixed to the ink reservoir 130 via an adhesive.

  As described above, as shown in FIG. 1, the head cover 110 includes a top plate provided with the ink supply valve 111, four side walls 112 extending downward from each side edge of the top plate, and the main scanning direction ( The inner space is partitioned in a substantially lattice shape by a plurality of ribs 113 formed on the inner side surface of the top plate. The openings 110a are formed in the two side walls 112 extending in the longitudinal direction. Further, a tapered tip portion 113 a projects further downward from the lower end surface of the rib 113 in the specific rib 113. In the present embodiment, as shown in FIG. 4, any of the tip portions 113a is formed on the lower end surface of the rib 113 extending in the main scanning direction.

  The heat sink 150 will be described with reference to FIGS. 1, 3, and 5. FIG. 5 is a side view of the heat sink 150. The heat sink 150 is a plate member made of aluminum metal, and includes a side wall 153 and two opposing walls 154. The side wall 153 has a substantially rectangular shape extending in the longitudinal direction of the flow path unit 140 and along the outline of the flow path unit 140. The lower end surface of the side wall 153 is in contact with the upper surface of the flow path unit 140 so as to intersect perpendicularly. A rectangular flat protrusion 150 a extending in the longitudinal direction of the flow path unit 140 is formed at the center of the side wall 153. As shown in FIG. 3, the flat protrusion 150 a protrudes outside the flow path unit 140 in the sub-scanning direction (short direction). The flat protrusion 150a is formed by, for example, pressing a metal flat plate. As described above, the flat protrusion 150 a is formed on the heat sink 150, thereby increasing the rigidity of the heat sink 150.

  As shown in FIG. 5, five protrusions 150b projecting downward are formed at the lower end of the side wall 153 so as to be arranged along the longitudinal direction. As will be described later, five concave portions 141 are formed in the vicinity of each end in the short direction of the flow path unit 140 (see FIG. 7). Then, the protrusions 150b are fitted in the recesses 141, respectively. Thereby, the heat sink 150 is erected from the upper surface of the flow path unit 140. At this time, the two heat sinks 150 are opposed to each other in the short direction of the flow path unit 140. As shown in FIG. 3, above the flat protrusion 150 a on the side wall 153, the outer surface of the side wall 153 (the surface opposite to the facing wall 154) and the inner surface of the side wall 112 of the head cover 110 are in contact.

  The facing wall 154 is connected to the upper end portion of the side wall 153 and extends inward from the connecting portion so as to face the actuator unit 120 attached to the upper surface of the flow path unit 140. And the front-end | tip part 113a of the rib 113 formed in the head cover 110 is pressing the edge part vicinity of the direction separated from the connection part in the opposing wall 154. FIG.

  Thereby, although not shown, the opposing wall 154 is elastically deformed in the direction of the arrow in the figure. The opposing wall 154 is displaced downward from the connecting portion with the side wall 153 as a starting point. Therefore, the pressing force from the rib 113 is broken down into two component forces. One component force acts to press the side wall 153 toward the flow path unit 140 (perpendicular to the mounting surface), and the other component force presses the side wall region 154 toward the side wall 112 of the head cover 110 (parallel to the mounting surface). Work to press against. At this time, since the outer side surface of the side wall 153 and the inner side surface of the side wall 112 are in contact with each other, the adhesion between the side wall 153 and the side wall 112 is improved. At the same time, the adhesion between the side wall 153 and the flow path unit 140 is also improved.

  As described above, the rib 113 (tip portion 113a) and the opposing wall 154 that is elastically deformed constitute a kind of urging means that urges the heat sink 150 in the protruding direction of the rib 113. Furthermore, in this embodiment, the head cover 110 as a cover member has a side wall 112 extending toward the mounting surface of the actuator unit 120 at the outer edge of the flow path unit 140 in the short direction. Further, the heat sink 150 is abutted against the tip 113a of the rib 113 and is deformed with at least the connecting portion between the opposing wall 154 and the side wall 153 as a fulcrum, and the side wall 153 is biased toward the mounting surface. Yes. In the heat sink 150, the vicinity of the connection portion between the facing wall 154 and the side wall 153 is supported in close contact with the inner side surface of the side wall 112 of the head cover 110.

  Furthermore, the contact position between the tip 113a of the rib 113 and the opposing wall 154 overlaps the actuator unit 120 in plan view. Thus, in the vicinity of the actuator unit 120, the adhesion of the heat sink 150 to the flow path unit 140 and the head cover 110 is high. Therefore, it is possible to reliably prevent an electrical failure (for example, a short circuit) caused by an ink droplet or ink mist entering.

  In this embodiment, the heat sink 150 made of aluminum metal is adopted. However, the material may be made of, for example, titanium metal, magnesium metal, or an alloy thereof, or an aluminum alloy. It may be.

  The inkjet head 100 is potted with gaps between the members so that the space surrounded by the head cover 110, the heat sink 150, the ink reservoir 130 (particularly, the reservoir base 132: described later), and the flow path unit 140 becomes a sealed space. It is sealed with an agent (only the material applied to the boundary region between the heat sink 150 and the flow path unit 140 is shown) 155. At this time, since the heat sink 150 is in contact with the flow path unit 140 and the head cover 110 with good adhesion, the potting agent does not enter the sealed space.

  The control board 170 controls the actuator unit 120, and is fixed above the ink reservoir 130 as shown in FIGS. Four connectors 170 a are fixed on the upper surface of the control board 170. The connector 170a is electrically connected to various processors and storage devices built on the control board 170. The four connectors 170a are arranged in two rows in a staggered manner in the main scanning direction.

  One end of the FPC 162 is connected to the side surface of each connector 170a. The FPC 162 is a flexible sheet-like member, and electrically connects the actuator unit 120 and the control board 170. A plurality of wirings 162 a are formed inside the FPC 162. As shown in FIG. 2, the FPC 162 is directed downward from the connector 170 a along the side surface of the ink reservoir 130, and is passed through a recess 133 b formed on the side surface of the ink reservoir 130. The other end of the FPC 162 is electrically connected to the actuator unit 120 in the recess 133b. A driver IC 160 is mounted on the FPC 162 and is electrically connected to the wiring 162a.

  The driver IC 160 is an IC chip that drives the actuator unit 120. Further, as shown in FIG. 3, the driver IC 160 is urged against the heat sink 150 together with the FPC 162 by a sponge 161 provided on the side surface of the ink reservoir 130 at a position facing the heat sink 150. A heat radiating sheet 156 is affixed at a position facing the driver IC 160 on the inner surface of the heat sink 150. The driver IC 160 is in close contact with the heat sink 150 via the heat dissipation sheet 156. As a result, the driver IC 160 and the heat sink 150 are thermally coupled.

  Next, the ink reservoir 130 will be described in detail with reference to FIGS. 2, 3, and 6. FIG. 6 is a longitudinal sectional view of the ink reservoir 130 showing cross sections along both the main scanning direction and the vertical direction. As shown in FIGS. 2, 3, and 6, the ink reservoir 130 has an upper reservoir 131, a reservoir base 132, and a lower reservoir 133 in order toward the flow path unit 140. All of the upper reservoir 131, the reservoir base 132, and the lower reservoir 133 have a rectangular shape in plan view, and their long sides are parallel to the main scanning direction.

  As shown in FIG. 6, an ink flow path 135 extending from an ink supply port 131 b formed on the upper surface of the upper reservoir 131 to an ink passage port 131 e formed on the lower surface of the upper reservoir 131 is provided in the upper reservoir 131. Is formed. The ink supply port 131 b is located near one end in the main scanning direction of the upper reservoir 131 and communicates with the ink supply valve 111 provided on the upper surface of the head cover 110. The ink passage port 131e is formed at the center of the upper reservoir 131 with respect to the main scanning direction and the sub-scanning direction. A part of the lower surface of the ink flow path 135 is made of a flexible film 131d. The lower surface of the film 131d faces the reservoir base 132 with a predetermined gap, and is disposed so as to be able to be displaced corresponding to the gap. Therefore, when the film 131d vibrates, the shock due to the pressure wave generated in the ink filled in the ink flow path 135 is absorbed. Further, a filter 131c having a plurality of fine holes is disposed in the ink flow path 135.

  Inside the reservoir base 132, an ink flow path 136 extending in the vertical direction from the ink passage port 131e to the ink passage port 132a formed on the lower surface of the reservoir base 132 is formed. In the lower reservoir 133, an ink flow path 137 is formed from the ink passage port 132a to a plurality of ink passage ports 133a formed on the lower surface of the lower reservoir 133. The ink passage port 133 a communicates with an ink supply port 140 a (described later) formed on the upper surface of the flow path unit 140.

  As described above, the ink supplied from the ink supply port 131 b flows into the flow path unit 140 through the ink flow paths 135 to 137 formed in the ink reservoir 130. The ink passes through the filter 131 c provided in the ink flow path 135 until it reaches the flow path unit 140. At that time, impurities in the ink are filtered by the filter 131c.

  Next, the flow path unit 140 and the actuator unit 120 will be described with reference to FIG. FIG. 7 is a plan view of the flow path unit 140. FIG. 8 is an enlarged plan view of a region surrounded by a one-dot chain line in FIG. For convenience of explanation, the actuator unit 120 is shown by a two-dot chain line in FIG. Moreover, the aperture 12 and the nozzle 8 etc. which are formed in the inside and the lower surface of the flow path unit 140 which should be originally shown by a broken line are shown by a solid line.

  As shown in FIG. 7, the flow path unit 140 has a rectangular shape in plan view, and its long side is parallel to the main scanning direction. An actuator unit 120 is attached to the upper surface of the flow path unit 140. The shape of the actuator unit 120 is a trapezoid, and the pair of parallel opposing sides are arranged so as to be parallel to the main scanning direction. Four actuator units 120 are arranged in a staggered pattern in the main scanning direction. In the four actuator units, the hypotenuses adjacent on the flow path unit 140 partially overlap in the sub-scanning direction.

  Further, five recesses (grooves) 141 extending from the upper surface of the flow path unit 140 to the middle in the thickness direction are formed in the vicinity of both ends in the short direction on the upper surface of the flow path unit 140. These recesses 141 are formed at positions corresponding to the five protrusions 150 b formed on the heat sink 150. Further, the recess 141 has a size and a shape that fits exactly with the protrusion 150 b of the heat sink 150. As shown in FIG. 7, each of the concave portions 141 is formed two by two corresponding to the bottom side of the actuator unit 120 (the longer parallel opposing side). Thereby, the side wall 153 is not laterally displaced by the pressing force applied by the rib 113 to the opposing wall 154 of the heat sink 150, and at least high adhesion between the heat sink 150 and the flow path unit 140 in the vicinity of the actuator unit 120 is ensured. .

  A manifold channel 5 that is a part of the ink channel is formed inside the channel unit 140. A plurality of ink supply ports 140a are formed on the upper surface of the flow path unit 140, and one end of the manifold flow path 5 communicates with each ink supply port 140a. A total of ten ink supply ports 140a are formed along the longitudinal direction of the flow path unit 140, five each. The ink supply port 140a is formed at a position that avoids an area where the four actuator units 120 are disposed.

  As shown in FIG. 8, a plurality of sub-manifold channels 5 a are branched from the manifold channel 5 formed in the channel unit 140. The flow path unit 140 has a pressure chamber group 9 in which a plurality of pressure chambers 10 are formed in a matrix. The pressure chamber 10 is a hollow region having a substantially rhombic planar shape. The pressure chamber 10 is formed so as to open on the upper surface of the flow path unit 140. These pressure chambers 10 are arranged over almost the entire surface of the upper surface of the flow path unit 140 facing the actuator unit 120.

  In the present embodiment, 16 rows of the pressure chambers 10 arranged in the longitudinal direction of the flow path unit 140 at equal intervals are arranged in parallel with each other in the lateral direction. The number of pressure chambers 10 included in each pressure chamber row is arranged so as to gradually decrease from the long side toward the short side corresponding to the outer shape of the actuator unit 120. The nozzle 8 is also arranged in the same manner.

  The cross-sectional structures of the flow path unit 140 and the actuator unit 120 will be described with reference to FIGS. FIG. 9 is a longitudinal sectional view taken along line IX-IX in FIG. FIG. 10 is an enlarged view of a region surrounded by a one-dot chain line in FIG.

  As shown in FIG. 9, the flow path unit 140 has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 22, a base plate 23, an aperture plate 24, a supply plate 25, manifold plates 26, 27 and 28, a cover plate 29 and a nozzle 8 plate 30 in order from the upper surface of the flow path unit 140. A large number of communication holes are formed in these plates. Each plate is aligned and stacked such that these communication holes communicate with each other to form the individual ink flow path 32 and the sub-manifold flow path 5a. As described above, a large number of individual ink flow paths 32 having the apertures 12, the pressure chambers 10, and the nozzles 8 are formed in the flow path unit 140. The lower surface of the flow path unit 140 is an ink ejection surface in which the nozzles 8 are opened. Each individual ink channel 32 communicates with the sub-manifold channel 5a. The ink supplied to the manifold channel 5 is supplied to each individual ink channel 32 through the sub-manifold channel 5a.

  As shown in FIG. 10, the actuator unit 120 has a laminated structure in which four piezoelectric layers 41, 42, 43, and 44 are laminated. These piezoelectric layers 41 to 44 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The actuator unit 120 includes a plurality of individual electrodes 35 and a common electrode 34 made of a metal material such as an Ag—Pd system. The individual electrode 35 is slightly smaller than the pressure chamber 10, has a shape substantially similar to the pressure chamber 10, and is disposed so as to be within a region facing the pressure chamber 10 on the upper surface of the actuator unit 120 ( (See FIG. 8). One end of the individual electrode 35 is drawn out of a region facing the pressure chamber 10 to form a land 36. The land 36 is made of gold containing glass frit, for example, and has a convex shape. The land 36 is electrically connected to the plurality of wirings 162a of the FPC 162, respectively.

  The common electrode 34 is interposed over almost the entire surface in the area between the piezoelectric layer 41 and the piezoelectric layer 42. That is, the common electrode 34 extends across all the pressure chambers 10 in the region facing the actuator unit 120. The common electrode 34 is grounded in a region not shown, and is held at the ground potential. The plurality of individual electrodes 35 and the common electrode 34 are arranged so as to sandwich only the uppermost piezoelectric layer 41. Only the region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric layer 41 is an active portion. That is, the actuator unit 120 has a so-called unimorph type configuration.

  Then, when a predetermined voltage pulse is selectively supplied from the driver IC 160 to the individual electrode 35 via the wiring 162a of the FPC 162, the region corresponding to the individual electrode 35 of the actuator unit 120 is deformed to correspond to the region. The volume of the pressure chamber 10 to be changed changes. As a result, a pressure wave is generated in the ink in the pressure chamber, and an ink droplet is ejected from the corresponding nozzle 8.

  According to the inkjet head 100 according to the present embodiment described above, the front end portion 113a of the head cover 110 abuts against the heat sink 150 on the opposing wall 154, so that the lower end surface of the side wall 153 of the heat sink 150 and the flow path unit 140 are reliably connected. Abut. Thereby, there is no gap between the flow path unit 140 and the side wall 153, and it is possible to prevent ink droplets from entering between the flow path unit 140 and the side wall 153 and adhering to the actuator unit 120. it can. Therefore, even if there is an error in the positional relationship between the front end portion 113a of the head cover 110 and the opposing wall 154 due to manufacturing errors of the head cover 110 or the heat sink 150, the front end portion 113a is surely brought into contact with the opposing wall 154. Thus, the side wall 153 can be reliably brought into contact with the mounting surface of the flow path unit 140.

  In addition, since the front end portion 113a of the head cover 110 presses the heat sink 150 at the opposing wall 154 so that the heat sink 150 is elastically deformed between the head cover 110 and the flow path unit 140, the elastic return force of the heat sink 150 itself. Therefore, the side wall 153 is urged toward the upper surface of the flow path unit 140. Thereby, the side wall 153 can be reliably brought into contact with the upper surface of the flow path unit 140.

  Further, since the driver IC 160 is in close contact with the metal heat sink 150 via the heat dissipation sheet 156, the driver IC 160 and the heat sink 150 are thermally coupled. Thus, since the heat sink 150 serves as both the side wall of the inkjet head 100 and the heat sink of the driver IC 160, the inkjet head 100 can be reduced in size.

  In addition, since the boundary region between the side wall 153 of the heat sink 150 and the upper surface of the flow path unit 140 is sealed by the potting agent 155, ink splashes enter between the flow path unit 140 and the lower end surface of the side wall 153. Can be surely prevented.

  Further, since the rib 113 is formed on the head cover 110, the rigidity of the head cover 110 is increased.

  Furthermore, since the tip 113a of the rib 113 that presses the opposing wall 154 has a contour with a curved section including the axis in the protruding direction of the rib 113, the tip 113a and the opposing wall 154 are in a very narrow range. Abuts only at. Thereby, the position accuracy of the contact position is increased, and the contact force for each tip 113a is made uniform.

  Further, since the tip 113a of the rib 113 formed on the head cover 110 presses the vicinity of the end of the facing wall 154 in the direction away from the connecting portion, the facing wall 154 is elastically deformed toward the flow path unit 140. . Thereby, even if the positional relationship between the facing wall 154 and the tip portion 113a differs greatly due to manufacturing errors of the head cover 110 and the heat sink 150, the tip portion 113a can be reliably brought into contact with the facing wall 154.

  Furthermore, since the opposing wall 154 pressed by the tip 113a of the rib 113 is opposed to the actuator unit 120, a gap is less likely to occur between the flow path unit 140 and the side wall 153 closest to the actuator unit 120.

  In addition, since the outer side surface of the side wall 153 and the inner side surface of the side wall 112 of the head cover 110 are in contact with each other, the side wall 153 is prevented from being bent outward and the side wall 153 and the side wall 112 are in close contact with each other. Improves. Thereby, ink splashes do not enter between the side wall 153 and the side wall 112. Further, since the side wall 112 restricts elastic deformation toward the outside of the side wall 153, the side wall 153 is urged toward the upper surface of the flow path unit 140 with a larger force. As a result, a gap is less likely to occur between the flow path unit 140 and the side wall 153.

  In addition, since the protrusion 150b of the heat sink 150 is fitted in the recess 141 formed on the upper surface of the flow path unit 140, the heat sink 150 is less likely to tilt, and displacement can be suppressed. For this reason, the heat sink 150 can reliably receive the pressing force from the tip portion 113a, and a gap is less likely to be generated between the flow path unit 140 and the heat sink 150. Furthermore, since the mounting position of the heat sink 150 to the flow path unit 140 becomes clear and accurate, the ink jet head 100 can be easily assembled.

  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. For example, in the above-described embodiment, the heat sink 150 is formed of a metal material and is configured to be thermally coupled to the driver IC 160, but the heat sink 150 may be formed of a member other than the metal material. Alternatively, the driver IC 160 may not be thermally coupled.

  In the above-described embodiment, the boundary region between the side wall 153 of the heat sink 150 and the upper surface of the flow path unit 140 is sealed with the potting agent 155, but is not sealed with the potting agent 155. Also good.

  Further, in the above-described embodiment, the opposing wall 154 is pressed against the tip end portion 113a of the rib 113 formed on the head cover 110, but the tip end portion 113a may not be formed on the rib, or the head cover. The rib does not need to be formed. In this case, the facing wall 154 only needs to be pressed by another part of the head cover.

  Further, in the above-described embodiment, the tip 113a of the rib 113 that presses the opposing wall 154 has a configuration in which the cross section including the axis in the protruding direction of the rib 113 has a curved contour. The shape may be arbitrary. For example, the tip may be rectangular.

  Furthermore, in the above-described embodiment, the tip portion 113a of the rib 113 presses the vicinity of the end portion in the direction away from the connecting portion in the opposing wall 154, but the tip portion 113a of the rib 113 is configured to press the opposing wall 154. The structure which presses arbitrary positions may be sufficient.

  In addition, in the above-described embodiment, the opposed wall 154 with which the tip 113a of the rib 113 abuts is configured to face the actuator unit 120, but the opposed wall may not be opposed to the actuator unit 120.

  In the above-described embodiment, the outer surface of the side wall 153 of the heat sink 150 and the inner surface of the side wall 112 of the head cover 110 are in contact with each other. However, the outer surface of the side wall 153 is in contact with members other than the side wall 112. The structure which may be sufficient, and the structure where the outer surface of the side wall 153 is not in contact with any member may be sufficient.

  Furthermore, in the above-described embodiment, the five protrusions 150b of the heat sink 150 are configured to fit into the recesses 141 formed on the upper surface of the flow path unit 140, respectively, but the number of protrusions of the heat sink is arbitrary. It may be a thing and the structure in which a heat sink does not have a projection part may be sufficient. In this case, the whole lower end part of the side wall region of the heat sink may be fitted in a groove formed on the upper surface of the flow path unit.

  In addition, in the above-described embodiment, the lower end surface of the side wall 153 of the heat sink 150 is in contact with the upper surface of the flow path unit 140 so as to intersect perpendicularly, but the lower end surface of the side wall region is the flow path unit. The configuration may be such that the top surface of 140 abuts at an angle other than perpendicular.

  In the above embodiment, the heat sink 150 is elastically deformed between the head cover 110 and the flow path unit 140 by the front end portion 113a of the head cover 110 pressing the heat sink 150 on the opposing wall 154. Although the tip 113a of the head cover 110 only contacts the heat sink 150 at the opposing wall 154, the heat sink 150 is not elastically deformed between the head cover 110 and the flow path unit 140. Good.

  Further, the above-described embodiment is configured such that the head cover 110 presses both the two heat sinks 150 toward the flow path unit 140. However, the head cover 110 may be configured to press only one of the heat sinks 150. Also in this case, it is possible to prevent ink droplets from entering between at least the heat sink 150 pressed by the head cover 110 and the flow path unit 140. Alternatively, only one heat sink 150 may be provided, and the head cover 110 may be configured to press the heat sink 150.

It is a schematic perspective view of the inkjet head by one Embodiment of this invention. It is a perspective view which shows the structure inside the inkjet head shown by FIG. It is sectional drawing along the III-III line | wire shown in FIG. FIG. 2 is a perspective view of the head cover shown in FIG. 1. FIG. 2 is a side view of the heat sink shown in FIG. 1. FIG. 2 is a longitudinal sectional view of an ink reservoir shown in FIG. 1. FIG. 2 is a plan view of the flow path unit shown in FIG. 1. FIG. 8 is an enlarged plan view of a region surrounded by an alternate long and short dash line in FIG. 7. It is a longitudinal cross-sectional view along the IX-IX line of FIG. FIG. 10 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Inkjet head 110 Head cover 110a Opening 112 Side wall 113 Rib 113a Tip part 120 Actuator unit 140 Flow path unit 141 Recess 150 Heat sink 150a Flat protrusion part 150b Protrusion part 153 Side wall 154 Opposite wall 155 Potting agent 160 Driver IC

Claims (13)

A flow path unit having an ink discharge surface on which a plurality of ink discharge ports for discharging ink droplets are formed;
An actuator for generating ejection energy for ejecting ink droplets from the ink ejection port, which is attached to an attachment surface opposite to the ink ejection surface in the flow path unit;
A side wall extending in the longitudinal direction of the flow path unit along the outline of the flow path unit and in contact with the attachment surface, and connected to the side wall and attached to the side wall At least one side wall member having an opposing wall facing the surface;
A cover member disposed at a position sandwiching the actuator and the side wall member with the flow path unit,
The inkjet head, wherein the cover member is disposed so as to press the opposing wall of the side wall member toward the flow path unit.   The inkjet head according to claim 1, wherein the side wall member is elastically deformed between the cover member and the flow path unit. A driver IC for driving the actuator;
The side wall member is formed of a metal material;
The inkjet head according to claim 1, wherein the driver IC and the side wall member are thermally coupled.   The inkjet head according to any one of claims 1 to 3, wherein a boundary region between the mounting surface and the side wall of the side wall member is sealed with a potting agent. A rib projecting toward the mounting surface is formed on a surface of the cover member facing the mounting surface,
The inkjet head according to any one of claims 1 to 4, wherein a tip of the rib is in contact with the opposing wall.   The inkjet head according to claim 5, wherein a tip of the rib has a contour with a curved cross section including an axis in a protruding direction of the rib.   The inkjet head according to claim 5 or 6, wherein a tip of the rib is in contact with a vicinity of a tip of the opposing wall in a direction away from the side wall.   The inkjet head according to any one of claims 5 to 7, wherein the side wall member is formed so that a region of the opposing wall that contacts the tip of the rib faces the actuator. The cover member has a cover side wall portion extending toward the vicinity of one end of the flow path unit in the short direction,
The inkjet head according to any one of claims 1 to 8, wherein the cover side wall portion is in contact with a surface of the side wall opposite to a surface to which the opposing wall is connected. The flow path unit has at least two grooves formed to extend from the mounting surface to the middle in the thickness direction of the flow path unit,
The side wall has an abutting surface that abuts on the mounting surface and the same number of protrusions as the grooves protruding from the abutting surface,
The inkjet head according to claim 1, wherein the protrusions are fitted in the grooves.   The side wall has a convex portion extending along the longitudinal direction of the flow path unit while projecting to the outside of the flow path unit with respect to the short side direction, and is in contact with the mounting surface perpendicularly. The inkjet head according to claim 1, wherein Two side wall members,
The inkjet head according to any one of claims 1 to 11, wherein the two side wall members are respectively disposed in the vicinity of one end and the other end of the flow path unit in the lateral direction. An ink reservoir for supplying ink to the flow path unit is installed between the flow path unit and the cover member;
The cover member and the ink reservoir each have opposing regions facing each other with respect to at least one of a short side direction and a long side direction of the flow path unit;
In the ink reservoir, a plurality of recesses are formed in the facing region,
The inkjet head according to claim 1, wherein a plurality of protrusions fitted into the recesses are formed in the facing region of the cover member.

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