JP2008087179A - Ink-jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet head which prevents ink splashes from infiltrating to the interior thereof. <P>SOLUTION: According to the structure of the ink-jet head, a channel unit having a lower surface serving as an ink ejection surface, and an ink reserver inclusive of a metallic reserver base 132, are formed into a laminated body, and a head cover 110 is attached to an upper surface of the reserver base 132. Then projections 115 projecting downward are formed on each of side walls 113a, 113b extending in a lateral direction of the head cover 110, and the projections 115 are fitted into recesses 135 formed in an upper surface of the reserver base 132. Further a contact surface 115a on an external peripheral surface of each projection 115, facing outward with respect to a longitudinal direction of the head cover 110, makes contact with a contact surface 135a on the internal peripheral surface of each recess 135, facing inward with respect to the longitudinal direction of the head cover 110. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inkjet head that ejects ink droplets.

  Some inkjet heads that eject ink droplets onto a recording medium have a metallic head body having a plurality of individual ink flow paths from a common ink chamber to a nozzle through a pressure chamber. An actuator that applies ejection energy for ejecting ink droplets from the nozzles to the pressure chamber is attached to the head body. 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. Therefore, there is known a method in which a resin cover is mounted on the head body so that ink droplets do not adhere to the actuator (see, for example, Patent Document 1). The boundary between the cover and the head main body is sealed with a potting agent.

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

  However, since the resin cover has a larger linear expansion coefficient than the metal head main body, the cover expands larger than the head main body when the temperature of the surrounding atmosphere increases by driving the ink jet head. At this time, in particular, the positional relationship between the cover and the head main body in the longitudinal direction changes, and part of the sealing agent applied to the boundary peels off, and ink droplets easily enter the ink jet head. Sometimes.

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

  The inkjet head of the present invention has a discharge surface on which a plurality of discharge ports for discharging ink are formed, and includes a flow path body including a metal plate, and a surface opposite to the discharge surface of the flow path body. And a cover member made of a non-metallic material attached to the metal plate. The cover member has at least a pair of first contact surfaces facing away from each other in the longitudinal direction and at least a pair of metal plates facing away from each other and inward with respect to the longitudinal direction. And the pair of first contact surfaces are in contact with different second contact surfaces.

  According to the present invention, since the linear expansion coefficient of the cover member is larger than that of the metal plate, the cover member tends to expand in the longitudinal direction at a higher expansion rate than the metal plate when the temperature of the surrounding atmosphere increases. At this time, since the first contact surface and the second contact surface are in contact, the second contact surface restricts the first contact surface from spreading outward in the longitudinal direction. Thereby, it can suppress that the positional relationship regarding the longitudinal direction of a cover member and a metal plate changes. For this reason, it becomes difficult to peel off the sealing agent that seals the gap formed between the cover member and the metal plate, and ink droplets can be prevented from entering the inkjet head.

  In the present invention, the cover member is formed with a convex portion projecting toward the metal plate, and a concave portion into which the convex portion is fitted is formed on the metal plate, and the first contact surface May be formed on the outer peripheral surface facing the outer side of the convex portion, and the second contact surface may be formed on the inner peripheral surface facing the inner side of the concave portion. According to this, the cover member is firmly attached to the metal plate by fitting the convex portion and the concave portion. In addition, the first contact surface and the second contact surface can be brought into firm contact.

  In the present invention, the metal plate is formed with a convex portion protruding toward the cover member, and the second contact surface is formed on an outer peripheral surface facing the inside of the convex portion. Also good. According to this, the second contact surface can be easily formed on the metal plate.

  At this time, it is preferable that the convex portion is formed by press molding. According to this, the second contact surface can be more easily formed on the metal plate.

  Furthermore, in this invention, it is preferable that the said 1st contact surface is formed in the outer surface of the both walls extended in the said transversal direction of the said cover member. According to this, it can suppress efficiently that the positional relationship regarding the longitudinal direction of a cover member and a metal plate changes.

  At this time, the two first contact surfaces are arranged along the short direction of the cover member, and between the first contact surfaces with respect to the short direction on the inner side surfaces of the both walls, respectively. It is preferable that a third contact surface is formed so as to be disposed, and a fourth contact surface in contact with the third contact surface is formed on the metal plate. According to this, when both the walls extending in the short direction of the cover member are restricted from expanding along the longitudinal direction, the two walls can be prevented from bending inward. .

  Furthermore, at this time, the metal plate is formed with a convex portion projecting toward the cover member, and the fourth contact surface is formed on an outer peripheral surface facing the outside of the convex portion. More preferred. According to this, the fourth contact surface can be easily formed on the metal plate.

  In the present invention, the cover member is preferably made of a non-metallic material having a linear expansion coefficient of 40 (1 / K) or less. Furthermore, it is preferable that the cover member is made of a glass reinforced resin. According to this, the thermal expansion coefficient of the cover member can be reduced.

  In the present invention, it is even more preferable to further include a sealing agent that seals a boundary between the cover member and the metal plate. According to this, it is possible to reliably prevent ink droplets from entering the ink jet head.

<First Embodiment>
Hereinafter, a first embodiment according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view of an inkjet head 1 according to an embodiment of the present invention. FIG. 2 is a perspective view of the inkjet head 1 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 inkjet head 1 is applied to any character / image recording apparatus using an inkjet method such as an inkjet printer. The inkjet head 1 has a shape that is long in one direction in plan view.

  In the recording apparatus, the inkjet head 1 is disposed so as to face a sheet (recording medium) conveyed by a conveying mechanism. The inkjet head 1 is a line head having a long rectangular parallelepiped shape, and its longitudinal direction is fixed in the main scanning direction. The transport mechanism includes a transport belt that transports the paper, and transports the paper fed from the paper feed mechanism to the area facing the inkjet head 1. The ink-jet head 1 has a printing region that extends over almost the entire length in the width direction of the transport belt, and four ink jet heads 1 are provided along the transport direction of the paper. Each inkjet head 1 ejects ink droplets of different colors and can perform color printing composed of yellow, cyan, magenta, and black. Based on the image data from the outside, the transport mechanism sends the paper to the area opposite to the inkjet head 1, and each inkjet head 1 ejects ink droplets in accordance with this timing. The sheet on which the image is formed in this way is further transported and accommodated in a subsequent discharge unit.

  In the present embodiment, the main scanning direction is a long direction in a plan view of the inkjet head 1, and the sub-scanning direction is a direction perpendicular to the main scanning direction in a plan view. The downward direction is the ejection direction of the ink droplets ejected from the inkjet head 1, and the upward direction is the direction opposite to the downward direction.

  As shown in FIGS. 1 to 3, the inkjet head 1 includes a flow path unit 140 having a nozzle opening formed on the lower surface (ink ejection surface), an ink reservoir 130 that supplies ink to the flow path unit 140, and a head cover. (Cover member) 110, two heat sinks 150, and control board 170. The control board 170, the ink reservoir 130, and the flow path unit 140 are stacked in order from the top to the bottom.

  Inside the channel unit 140, a channel including a common ink chamber and a number of individual ink channels from the common ink chamber to the nozzle through the pressure chamber is formed. Four actuator units 120 that can selectively apply ejection energy to ink in a number of pressure chambers are attached to the upper surface of the flow path unit 140 in order to eject ink droplets from the nozzles. The actuator unit 120 is a unimorph type actuator including a piezoelectric layer sandwiched between a large number of individual electrodes and a common electrode arranged to face the pressure chamber. This piezoelectric layer is made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity. Further, the individual electrode and the common electrode are made of a metal material such as an Ag-Pd system. The individual electrode is electrically connected to the corresponding wiring 162a of the FPC 162 via a land made of gold containing glass frit on the upper surface of the actuator unit 120. When a predetermined voltage pulse is supplied from the driver IC 160 to the individual electrode via the wiring 162a of the FPC 162, the area corresponding to the individual electrode of the actuator unit 120 is deformed, and the volume of the pressure chamber facing the area changes. To do. As a result, a pressure wave (discharge energy) is generated in the ink in the pressure chamber, and ink droplets are discharged from the corresponding nozzles.

  In the ink reservoir 130, an upper reservoir 131, a metal reservoir base (metal plate) 132, and a lower reservoir 133 are stacked in order toward the flow path unit 140. An ink flow path 135 is formed inside the upper reservoir 131. The ink channel 135 communicates with the ink supply valve 111 and also communicates with the channel unit 140 through an ink channel (not shown) formed in the reservoir base 132. 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. For this reason, 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.

  As shown in FIG. 3, the lower reservoir 133 is joined to the flow path unit 140, but a recess 133 b is partially formed on the boundary surface between them. The recesses 133b are respectively arranged corresponding to the actuator units 120, and the actuator unit 120 is attached to the surface of the flow path unit 140 in a gap created by the recesses 133b. As described above, the flow path body of the inkjet head 1 is configured to include the ink reservoir 130 and the flow path unit 140, and one end thereof communicates with the ink supply valve 111 and the other end reaches the nozzle. An ink flow path is formed. The ink supplied from the ink supply valve 111 flows into the flow path unit 140 through the ink flow path 135 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.

  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.

  One end of the FPC 162 is electrically connected to the side surface of each connector 170a. The FPC 162 is a flexible sheet-like member, on which a plurality of wirings 162a are formed and a driver IC 160 is mounted. On the other hand, the other end (the terminal of the wiring 162 a) of the FPC 162 is electrically connected to the individual electrode of the actuator unit 120 in the recess 133 b of the ink reservoir 130.

  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. The heat sink 150 is a metallic plate-like member such as aluminum or stainless steel, and a heat dissipating sheet 157 is attached to the inner surface of the heat sink 150 at a position facing the driver IC 160. The driver IC 160 is in close contact with the heat sink 150 via the heat dissipation sheet 157, and the driver IC 160 and the heat sink 150 are thermally coupled. As a result, heat generated by the driver IC 160 is radiated through the heat sink 150.

  The head cover 110 will be described with reference to FIGS. 1, 3, and 4. FIG. FIG. 4A is a partial top view of the vicinity of each end in the longitudinal direction of the inkjet head 1 as viewed from above. FIG. 4B is a partial cross-sectional view of the inkjet head 1 taken along the line IVB-IVB along the longitudinal direction shown in FIG. FIG. 4C is a partial cross-sectional view of the inkjet head 1 with respect to the IVC-IVC line along the short direction shown in FIG. In FIG. 4, only the head cover 110 and the reservoir base 132 are shown.

  As shown in FIGS. 1 and 3, the head cover 110 is formed by molding a glass reinforced resin having a linear expansion coefficient of 40 (1 / K) or less, and has a substantially box shape that opens downward. Yes. The head cover 110 forms a sealed space together with the heat sink 150 described above, and houses the FPC 162 and the control board 170 on which the actuator unit 120, the ink reservoir 130, and the driver IC 160 are mounted. The head cover 110 is attached to the upper surface of the reservoir base 132 at both ends in the longitudinal direction, with the opposite side walls 112 sandwiching the heat sink 150 between the head cover 110 and the flow path unit 140, respectively. An ink supply valve 111 is provided on the top surface of the head cover 110, and ink is supplied from the outside.

  Further, each side wall 112 extending in the longitudinal direction of the head cover 110 is formed with a rectangular opening 110a extending in the main scanning direction. The opening 110 a is a notch formed from the lower end of the side wall 112 to the vicinity of the center in the vertical direction, and is used to expose a flat protrusion 150 a formed on the heat sink 150 described later from the head cover 110. A concave portion 112 a is formed inside each side wall 112 so that the thickness thereof is stepped, and the upper end portion of the heat sink 150 is in contact with the step portion inside the side wall 112. As a result, the heat sink 150 is sandwiched between the side wall 112 and the flow path unit 140.

  As shown in FIG. 4, three convex portions 115 projecting further downward are formed at the lower end portions of the side walls 113a and 113b extending in the short direction. On the other hand, a total of six rectangular recesses 135 are formed in each of the side walls 113a and 113b at positions facing the respective protrusions 115 on the upper surface of the reservoir base 132. And each convex part 115 is each fitted with the corresponding recessed part 135, respectively. At this time, the contact surface (first contact surface) 115a facing the outer side in the longitudinal direction of the head cover 110 on the outer peripheral surface of the convex portion 115 and the inner side in the longitudinal direction of the head cover 110 on the inner peripheral surface of the concave portion 135 are directed. The contact surface (second contact surface) 135a is in contact. As described above, the head cover 110 has three pairs of contact surfaces 115a (formed on the outer surfaces of the side walls 113a and 113b) opposite to each other in the longitudinal direction and facing outward, and the reservoir base 132 is provided. , And three pairs of contact surfaces 135a facing inwardly and inwardly with respect to the longitudinal direction. Each contact surface 115a is in contact with a different contact surface 135a.

  Further, the lower end surfaces of the side walls 113a and 113b excluding the convex portion 115 are in contact with the upper surface of the reservoir base 132, and the gap between the head cover 110 and the reservoir base 132 is sealed with a potting agent (sealing agent) 156. .

  In the present embodiment, the heat sink 150 is a plate member made of aluminum metal, and has a substantially rectangular shape extending in the longitudinal direction of the flow path unit 140. As shown in FIG. 3, a rectangular flat protrusion 150 a extending in the longitudinal direction of the flow path unit 140 is formed at the center of the heat sink 150. The flat protrusion 150a 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 150a is formed on the heat sink 150, whereby the rigidity of the heat sink 150 is enhanced. Moreover, since the surface area becomes large, it contributes to the improvement of the heat dissipation characteristic.

  At the lower end of the heat sink 150, protrusions 150b projecting downward are formed so as to be arranged along the longitudinal direction. A recess 141 is formed on the upper surface of the flow path unit 140, and the protrusion 150 b fits into the recess 141, so that the heat sink 150 is erected in the vicinity of each end in the short direction on the upper surface of the flow path unit 140. Has been. At this time, the lower end surface of the heat sink 150 excluding the projecting portion 150b is in close contact with the upper surface of the flow path unit 140 and is also thermally coupled.

  Further, the gap between the heat sink 150 and the side wall 112 when viewed from the outside of the inkjet head 1 and the gap between the heat sink 150 and the flow path unit 140 are sealed with a potting agent 155. Further, as described above, the gap between the head cover 110 and the reservoir base 132 is sealed with the potting agent 156. For this reason, the space surrounded by the head cover 110, the heat sink 150, and the flow path unit 140 is a sealed space. Thereby, it is possible to prevent ink droplets from entering the sealed space.

  According to the present embodiment described above, since the linear expansion coefficient of the head cover 110 is larger than that of the reservoir base 132 that is a metal plate, the temperature of the surrounding atmosphere is increased, so that the head cover 110 is longitudinally expanded at a higher expansion rate than the reservoir base 132. Try to expand in the direction. At this time, the contact surface 115a formed on the outer peripheral surface facing the outer side of the convex portion 115 of the head cover 110 and the contact surface 135a formed on the inner peripheral surface facing the inner side of the concave portion 135 of the reservoir base 132 contact each other. Therefore, the contact surface 135a restricts the contact surface 115a from spreading outward in the longitudinal direction. Thereby, it is suppressed that the positional relationship in the longitudinal direction between the head cover 110 and the reservoir base 132 changes. For this reason, the potting agent 156 that seals the gap formed between the head cover 110 and the reservoir base 132 is difficult to peel off, and ink droplets can be prevented from entering the sealed space. Note that the amount of expansion also differs between the side wall 112 and the heat sink 150. However, since the thermal expansion of the head cover 110 is regulated in this way, a change in the positional relationship between the head cover 110 and the heat sink 150 is also suppressed.

  Furthermore, the form in which the convex portion 115 and the concave portion 135 are fitted is effective in preventing the potting agent 156 from peeling even when the ambient temperature is low. At this time, the head cover 110 tends to shrink larger in the longitudinal direction. However, the inner peripheral surface of the convex portion 115 and the outer peripheral surface of the concave portion 135 come into contact with each other, and the contraction of the head cover 110 is restricted.

  Further, since the convex portion 115 of the head cover 110 and the concave portion 135 of the reservoir base 132 are fitted, the head cover 110 can be firmly attached to the reservoir base 132. Furthermore, the contact surface 115a and the contact surface 135a can be firmly contacted.

  In addition, since the contact surface 115a is formed on the outer peripheral surface of the convex portion 115 and the contact surface 135a is formed on the inner peripheral surface of the concave portion 135, the contact surface 115a and the contact surface 135a can be easily formed. Can do.

  Further, since the contact surface 115a is formed on the outer surface of the side walls 113a and 113b extending in the short direction of the head cover 110, it is possible to efficiently change the positional relationship in the longitudinal direction between the head cover 110 and the reservoir base 132. Can be suppressed.

  Furthermore, since the head cover 110 is formed of a glass reinforced resin having a linear expansion coefficient of 40 (1 / K) or less, the thermal expansion coefficient of the head cover 110 can be suppressed.

<Second Embodiment>
Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 5A is a partial top view of the vicinity of each end in the longitudinal direction of the inkjet head according to the second embodiment as viewed from above. FIG. 5B is a partial cross-sectional view of the ink jet head taken along the line VB-VB along the longitudinal direction shown in FIG. In FIG. 5, only the head cover 210 and the reservoir base 232 are shown. Since the second embodiment is different from the first embodiment only in the head cover 210 and the reservoir base 232, only the head cover 210 and the reservoir base 232 will be described below. The description is omitted.

  The head cover 210 is formed by molding a glass reinforced resin having a linear expansion coefficient of 40 (1 / K) or less, and has side walls 112 extending in the longitudinal direction and side walls 213a and 213b extending in the short direction. ing. As shown in FIG. 5, the head cover 210 is attached to the upper surface of the reservoir base 232. The lower end surfaces of the side walls 213 a and 213 b are in contact with the upper surface of the reservoir base 232. On the upper surface of the reservoir base 232, two convex portions 235 and one convex portion 236 are formed in the vicinity of both ends in the longitudinal direction. These convex portions 235 and 236 are in a symmetrical positional relationship, two convex portions are on the outer side in the longitudinal direction, and one convex portion 236 is on the inner side. They are separated from each other by the thickness of the head cover 210 in the longitudinal direction. In the lateral direction, the two convex portions 235 are on both ends, and the single convex portion 236 is in the center.

  The contact surface (second contact surface) 235a formed on the outer peripheral surface facing inward with respect to the longitudinal direction of each convex portion 235 is a contact surface (first contact surface) on the outer surface of each side wall 213a, 213b of the head cover 210. ) Is in contact with each of 215a. The contact surface 215 a is located in the vicinity of both ends in the short direction of the head cover 210 corresponding to the convex portion 235. Further, a contact surface (fourth contact surface) 236a formed on the outer peripheral surface facing outward in the longitudinal direction of each convex portion 236 is a contact surface (third contact surface) on the inner surface of each side wall 213a, 213b of the head cover 210. ) Is in contact with each of 215b. The contact surface 215 b is located at the center in the short direction of the head cover 210 corresponding to the convex portion 236. Thus, the head cover 210 has two pairs of contact surfaces 215a that are opposite to each other and outward in the longitudinal direction and a pair of contact surfaces 215b that are opposite to each other and inward in the longitudinal direction. ing. In addition, two contact surfaces 215a corresponding to the side walls 213a and 213b are arranged along the short direction of the head cover 210, and are arranged between the two contact surfaces 215a in the short direction. A contact surface 215b is formed. In addition, the reservoir base 232 has two pairs of contact surfaces 235a facing in the opposite directions and inward with respect to the longitudinal direction, and a pair of contact surfaces 236a facing in the opposite directions and outward with respect to the longitudinal direction. Yes. Each contact surface 215a is in contact with a different contact surface 235a.

  Further, a gap between the head cover 210 and the reservoir base 232 is sealed with a potting agent (sealing agent) 156. Thereby, it is possible to reliably prevent ink droplets from entering the inkjet head 1.

  According to the present embodiment described above, since the linear expansion coefficient of the head cover 210 is larger than that of the reservoir base 232 that is a metal plate, the temperature of the surrounding atmosphere increases, so that the head cover 210 is longer in the longitudinal direction than the reservoir base 232 with a higher expansion rate. Try to expand in the direction. At this time, the contact surface 215a formed on the outer surface of the side walls 213a and 213b of the head cover 210 and the contact surface 235a formed on the outer peripheral surface facing the inside of the convex portion 235 of the reservoir base 132 are in contact with each other. The contact surface 235a restricts the contact surface 215a from spreading outward in the longitudinal direction. Thereby, it is suppressed that the positional relationship in the longitudinal direction between the head cover 210 and the reservoir base 232 changes. This makes it difficult for the potting agent 156 that seals the gap formed between the head cover 210 and the reservoir base 232 to peel off, and prevents ink droplets from entering the inkjet head. On the other hand, when the ambient temperature is lowered, the contact surface 215b of the head cover 210 and the contact surface 236a of the convex portion 236 come into contact with each other, and the same effect can be obtained with respect to the peeling of the potting agent 156.

  Moreover, since the convex part 235 and the convex part 236 are formed by press molding, the contact surfaces 215 a and 215 b can be easily formed on the reservoir base 232.

  Further, two contact surfaces 215a are arranged on the outer side surfaces of the side walls 213a and 213b, and the inner sides of the side walls 213a and 213b are arranged between the two contact surfaces 215a with respect to the short side direction of the head cover 210. Since the contact surface 215b is arranged on the side surface and each contact surface 215b is in contact with the contact surface 236a of each convex portion 236, the contact surface 235a is about to spread outward in the longitudinal direction. When regulating, the side walls 213a and 213b can be prevented from being bent inward.

  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 first and second embodiments described above, the contact surfaces 115a and 215a that are restricted from spreading outward in the longitudinal direction of the head covers 110 and 210 extend in the short direction of the head covers 110 and 210. The side walls 113a, 113b, 213a, and 213b are formed on the outer side surfaces, but such a contact surface may be formed on the side walls extending in the longitudinal direction of the head cover.

  In the first embodiment, the head cover 110 has three pairs of contact surfaces 115a that are restricted from spreading outward in the longitudinal direction. In the second embodiment, The head cover 210 is configured to have two pairs of contact surfaces 215a that are restricted from spreading outward in the longitudinal direction, but the four or more pairs of contacts in which the head cover faces away from each other and outward in the longitudinal direction. The structure which has a surface may be sufficient, and the structure from which the number of the contact surface which faces one outer side regarding the longitudinal direction differs from the contact surface which faces the other outer side may be sufficient.

  Furthermore, in the first and second embodiments described above, the head covers 110 and 210 are formed of a glass reinforced resin having a linear expansion coefficient of 40 (1 / K) or less, but the head cover is made of another non-metal. The structure formed with a material may be sufficient.

1 is a schematic perspective view of an ink jet head according to a first embodiment of the present 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 partially enlarged view of the ink jet head shown in FIG. 1. It is the elements on larger scale of the inkjet head of 2nd Embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2a Ink discharge surface 110 Head cover 112 Side wall 113a, 113b Side wall 115 Convex part 115a Contact surface 120 Actuator unit 130 Ink reservoir 131 Upper reservoir 132 Reservoir base 133 Lower reservoir 135 Recess 135a Contact surface 140 Flow path unit 150 Heat sink 155, 156 Potting agent 210 Head cover 213a, 213b Side wall 215a Contact surface 215b Contact surface 232 Reservoir base 235 Projection 235a Contact surface 236 Projection 236a Contact surface

Claims (10)

A flow path body having a discharge surface on which a plurality of discharge ports for discharging ink are formed and including a metal plate;
A cover member made of a non-metallic material attached to the metal plate so as to cover a surface of the flow path body opposite to the discharge surface;
The cover member has at least a pair of first contact surfaces that are opposite to each other in the longitudinal direction and facing outward;
The metal plate has at least a pair of second contact surfaces opposite to each other and inward with respect to the longitudinal direction;
The pair of first contact surfaces are in contact with different second contact surfaces. A convex part that protrudes toward the metal plate is formed on the cover member, and a concave part in which the convex part is fitted to the metal plate is formed,
The first contact surface is formed on an outer peripheral surface facing the outer side of the convex portion, and the second contact surface is formed on an inner peripheral surface facing the inner side of the concave portion. The inkjet head according to claim 1. The metal plate is formed with a convex portion protruding toward the cover member,
The inkjet head according to claim 1, wherein the second contact surface is formed on an outer peripheral surface facing an inner side of the convex portion.   The inkjet head according to claim 3, wherein the convex portion is formed by press molding.   The inkjet head according to claim 1, wherein the first contact surface is formed on an outer surface of both walls of the cover member extending in the short direction. The two first contact surfaces are arranged along the short direction of the cover member, and are arranged between the first contact surfaces on the inner side surfaces of the both walls with respect to the short direction. The third contact surface is formed as follows,
The inkjet head according to claim 5, wherein a fourth contact surface in contact with the third contact surface is formed on the metal plate. The metal plate is formed with a convex portion protruding toward the cover member,
The inkjet head according to claim 6, wherein the fourth contact surface is formed on an outer peripheral surface facing the outside of the convex portion.   The inkjet head according to claim 1, wherein the cover member is made of a nonmetallic material having a linear expansion coefficient of 40 (1 / K) or less.   The inkjet head according to claim 8, wherein the cover member is made of a glass reinforced resin.   The inkjet head according to claim 1, further comprising a sealant that seals a boundary between the cover member and the metal plate.

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