JP2007106016A - Inkjet head and is manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove air bubbles accumulated in a bent part certainly and easily, even in case an inkjet head is constructed so that an ink flows bending into a pressure chamber almost orthogonally from a communicating hole in a cavity unit. <P>SOLUTION: The inkjet head 1 is designed in such a way that the pressure chamber 24, covered by an actuator 21, allows the ink to flow along the actuator 21 toward one end 24b connected with a nozzle 23 from the other end 24a connected with the communicating hole 28, and that the communicating hole 28 is formed almost at right angles with the ink flowing direction in the pressure chamber 24 and also in an opposite direction to the actuator 21. Further, the ink passing through the communicating hole 28, is bent in its flow almost orthogonally at one end of the pressure chamber 24. Besides, a recessed part 50 is formed, at each pressure chamber 24, in the region of the actuator 21 corresponding with the communicating hole 28, in order to widen a section S1 at right angles with the flow of the ink at one end 24a of the pressure chamber 24. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head, and more particularly to an inkjet head having a cavity unit configured to supply ink to a pressure chamber that receives discharge pressure through a communication hole, and a method for manufacturing the inkjet head.

  In recent ink jet heads, the miniaturization has been promoted, and the applicant of the present invention has also disclosed a plurality of thin plates with a cavity unit having an ink flow path in the ink jet head as disclosed in Patent Document 1, for example. By stacking and configuring, the entire head is made thinner.

  As the plurality of plates of the cavity unit, a plate in which a plurality of nozzles are formed, a plate in which a pressure chamber for each nozzle is formed, and a common ink chamber in which ink supplied from an ink supply source is temporarily stored are formed. A plate, a plate in which communication holes for distributing the ink in the common ink chamber to the respective pressure chambers (described as communication passage 38 in Patent Document 1) are formed. An actuator that applies discharge pressure to the ink filled in the pressure chamber is stacked on the cavity unit so as to cover the pressure chamber.

In such a thin cavity unit, in order to effectively utilize the thickness dimension of the entire cavity unit and secure an ink flow path necessary for ejection, the ink flow path is disposed inside the cavity unit in the plate stacking direction ( (Thickness direction) or extends parallel to the surface direction of each plate. Specifically, the pressure chamber that receives the discharge pressure from the actuator is placed on the back plate facing the actuator, the nozzle is placed on the front plate, and the common ink chamber is placed on the intermediate plate in the stacking direction. Yes. Then, after the ink is supplied to the common ink chamber, as shown schematically in FIG. 8A, the ink advances through the communication hole 28 along the plate stacking direction to the one end 24a of the pressure chamber 24. The flow direction at one end 24a of the pressure chamber 24 is bent at a substantially right angle and proceeds to the other end 24b of the pressure chamber 24 along the surface of the actuator 21, and the flow direction at the other end 24b again at a substantially right angle. It is configured to bend and reach the nozzle provided on the front side of the cavity unit.
Japanese Patent Laying-Open No. 2005-41047 (see FIGS. 4 and 5)

  By the way, in the ink jet head, if bubbles are mixed into the ink inside the cavity unit, ink ejection failure is caused. Therefore, the ink is forcibly sucked (or pressurized) from the nozzle side of the cavity unit, and the bubbles are discharged together with the ink. The maintenance (purge process) for discharging is performed.

  However, as described above, if the ink flow path is configured to bend at a substantially right angle, bubbles are stagnated at the bent portion, and the stagnant bubbles merge with bubbles that come later and grow into large bubbles. Easy to do. In particular, the pressure chamber needs to increase the rate of change of the cross-sectional area accompanying the operation of the actuator in order to give a large discharge pressure to the ink, and the width facing the actuator (W in the plan view of FIG. 8C). Is preferably a flat cross-sectional shape having a large depth and a small depth (vertical direction in FIG. 8A). Further, the plate in which the communication hole is formed is preferably a plate thicker than the plate forming the pressure chamber in order to give rigidity to the entire cavity unit, and a communication hole that is smaller than the thickness is formed. Therefore, the communication hole has a diameter approximately equal to its thickness. For this reason, as shown in FIG. 8 (b), since the bubble A which has grown greatly inside the communication hole 28 is spherical, it is difficult to enter the pressure chamber 24 having a depth smaller than the diameter of the bubble. It stagnates on the ceiling surface of 24. As a result, the substantial cross-sectional area of the flow path toward the pressure chamber 24 is limited, the amount of ink supplied to the pressure chamber 24 is reduced, and printing failure occurs.

  In order to remove the bubbles, it is necessary to perform a purging process in which a pressure is applied to the ink to cause a flow from the communication hole 28 to the pressure chamber 24. As shown in FIG. Since W is sufficiently larger than the diameter L of the communication hole 28, the ink flow due to the purge process escapes in the width direction of the pressure chamber 24, and the bubble A cannot be pushed. For this reason, unless the purge process is performed by applying a large pressure on the ink to deform the spherical shape of the bubble A into a flat shape, the bubbles cannot be reliably removed, and wasteful ejection of ink accompanying the purge process, There has been a problem that the purge processing pump is also increased in size.

  The present invention solves the above-described problem, and in the structure in which the ink flows while bending at a substantially right angle from the communication hole of the cavity unit into the pressure chamber, the bubbles accumulated in the bent portion are removed. It is an object of the present invention to provide an ink jet head capable of easily and reliably performing the same and a manufacturing method thereof.

  In order to achieve the above object, an ink jet head according to a first aspect of the present invention includes a pressure chamber provided corresponding to each of a plurality of nozzles that eject ink, and a method for distributing ink to the plurality of pressure chambers. A cavity unit in which a common ink chamber, a communication hole for connecting the common ink chamber and the pressure chamber are formed, and the cavity unit is mounted so as to cover one side of the pressure chamber to fill the pressure chamber. An actuator for applying a discharge pressure to the ink, and the pressure chamber is formed to flow ink along the actuator from one end connected to the communication hole to the other end connected to the nozzle, and the communication The hole is formed in a direction substantially perpendicular to the direction of ink flow in the pressure chamber and in a direction facing the actuator, and the ink passing through the communication hole passes through the communication hole. An ink-jet head configured to bend the flow direction at one end of the force chamber at a substantially right angle, wherein the actuator portion corresponding to the communication hole is perpendicular to the ink flow at one end of the pressure chamber. A concave portion is formed for each of the pressure chambers so as to widen the cross-sectional area in any direction.

  According to a second aspect of the present invention, in the ink jet head according to the first aspect, the cavity unit includes a plate that forms the pressure chamber, a plate that forms the communication hole, and a plate that forms the common ink chamber. The actuator is laminated on a plate forming the pressure chamber on a side opposite to the plate forming the communication hole.

  According to a third aspect of the present invention, in the ink jet head according to the first or second aspect, of the cross sections in the direction perpendicular to the ink flow, the cross section of one end of the pressure chamber is more than the cross section of the communication hole. The cross-sectional area is small and flat.

  According to a fourth aspect of the present invention, in the ink jet head according to the first or second aspect, the concave portion formed in the actuator is formed in a curved shape inside.

  According to a fifth aspect of the present invention, there is provided an ink jet head manufacturing method according to the first aspect, wherein the actuator is a piezoelectric actuator formed by firing a piezoelectric ceramic material. The recess is formed by removing the piezoelectric ceramic from the fired piezoelectric actuator.

  According to a sixth aspect of the present invention, there is provided a method of manufacturing an ink jet head according to the first aspect, wherein the actuator is formed by stacking piezoelectric ceramic material sheets and integrating them by firing. The concave portion is formed by providing a depression by pressing with a convex member in a portion where the concave portion is to be formed in the sheet surface of the piezoelectric ceramic material before firing. It is a feature.

  According to a seventh aspect of the present invention, there is provided an ink jet head manufacturing method according to the first aspect, wherein the actuator is formed by stacking piezoelectric ceramic material sheets and integrating them by firing. The concave portion is formed by patterning a resin material on a portion where the concave portion is to be formed on the sheet surface of the piezoelectric ceramic material before firing, and removing the resin material by the firing. It is characterized by that.

  According to the first aspect of the present invention, the concave portion is provided on the actuator side so as to widen the cross-sectional area perpendicular to the ink flow at one end of the pressure chamber, and the internal space of the bent portion is widened. When the ink flows from the hole to the pressure chamber while bending at a substantially right angle, the bubbles easily pass. As a result, even if the bubbles caught in the bent portion grow large, if a purge process is performed to forcibly discharge the bubbles from the nozzle together with the ink during maintenance, the bubbles will easily flow to the pressure chamber side. Therefore, it is possible to prevent ink ejection failure.

  Further, since the recess is provided on the actuator side, the internal space of the bent portion can be expanded without changing the design shape of the communication hole and the pressure chamber.

  According to the second aspect of the present invention, since the cavity unit is formed by laminating a plurality of plates each having an ink flow path formed therein, the cavity unit having a complicated and finely shaped ink flow path therein. It can be easily and thinly configured.

  According to the third aspect of the present invention, at the bent portion where the ink flows into the pressure chamber from the communication hole, the cross-sectional area decreases before and after the bending, and the cross-sectional shape further increases the flatness. The spherical bubbles in the structure have a structure that hardly flows into the pressure chamber from the communication hole. However, by providing the recess as described in claim 1, the shape of the communication hole and the pressure chamber is not changed. However, it is possible to make it easier for the bubbles to flow into the pressure chamber.

  According to invention of Claim 4, since the inner side of a recessed part is spherical shape, there exists an effect that it becomes difficult to catch a bubble inside a recessed part.

  According to the fifth aspect of the present invention, since the piezoelectric actuator is used as the actuator, the recess having the desired shape can be easily formed by removing the fired piezoelectric ceramic.

  According to the invention described in claim 6, the piezoelectric actuator material is formed using a piezoelectric ceramic material sheet (generally called a green sheet) as the actuator, and the piezoelectric ceramic material sheet before firing is Since it is soft, it is possible to easily press and form a depression on this sheet, and a concave portion having a desired shape can be easily formed by a convex member.

  According to the seventh aspect of the present invention, a piezoelectric actuator material is formed using a piezoelectric ceramic material sheet (generally called a green sheet) as the actuator, and the piezoelectric ceramic material sheet before firing is used. When the resin material is patterned at the site where the recess is formed, and the piezoelectric ceramic material sheet is baked and integrated together with the resin material, the resin material is removed in the firing step. The pattern remains as a recess. Therefore, the shape of the concave portion can be set only by changing the pattern of the resin material, and the resin material can be removed without using any special process by using the baking process.

  Below, basic embodiment of this invention is described using FIGS. 1-7.

  FIG. 1 is a perspective view of a cavity unit 20, a piezoelectric actuator 21, and a flexible flat cable 22 in an inkjet head 1 according to an embodiment of the present invention. A plate-type piezoelectric actuator 21 is provided on a cavity unit 20 composed of a plurality of plates. A flexible flat cable 22 for connection to an external device is overlapped and bonded to the upper surface of the plate-type piezoelectric actuator 21. Then, it is assumed that ink is ejected downward from the nozzle 23 opened on the lower surface side of the cavity unit 20 (see FIG. 3).

  As shown in FIG. 2, the cavity unit 20 includes a total of seven thin plates including a nozzle plate 30, a spacer plate 31, two manifold plates 33a and 33b, a supply plate 34, a base plate 35, and a cavity plate 36. It has a structure in which it is overlapped with an adhesive.

  In the embodiment, each of the plates 30 to 36 has a thickness of about 40 to 150 μm, the nozzle plate 30 is made of a synthetic resin such as polyimide, and the other plates 31 to 36 are made of 42% nickel alloy steel plate. The nozzle plate 30 is provided with a large number of ink discharge nozzles 23 having a minute diameter (about 25 μm) at minute intervals. The nozzles 23 are arranged in two rows parallel to the long side direction (X direction) of the nozzle plate 30.

  In the cavity plate 36, as shown in FIG. 2, a plurality of pressure chambers 24 are arranged in two rows parallel to the long side of the cavity plate 36 (the X direction). In the embodiment, each of the pressure chambers 24 is formed in an elongated shape in plan view and penetrates the plate thickness of the cavity plate 36 so that the longitudinal direction thereof is along the short side direction (Y direction) of the cavity plate 36. . A communication hole 28 is connected to one longitudinal end 24 a of each pressure chamber 24, and the one end 24 a communicates with the common ink chamber 25 through the communication hole 28 and the connection flow path 29. The other end 24 b in the longitudinal direction of each pressure chamber 24 is connected to the base plate 35, the supply plate 34, the two manifold plates 33 a and 33 b, and the through-passage 26 formed in the spacer plate 31. The nozzles 23 communicate with the nozzles 23.

  As shown in FIG. 4, the pressure chamber 24 has a width dimension W and a depth dimension D. As described above, the pressure chamber 24 is formed through the thickness of the cavity plate 36. The depth dimension D of the cavity plate 36 is the same as the thickness dimension T 1 of the cavity plate 36. The cross-sectional area S1 perpendicular to the ink flow in the pressure chamber 24 is determined by the width dimension W and the depth dimension D (see FIGS. 4 and 5A). The pressure chamber 24 needs to have a large change rate of the cross-sectional area accompanying the operation of the actuator in order to give a large discharge pressure to the ink, and is set to a relationship of W> D. Specifically, the width dimension W is , Approximately 250 μm to 300 μm, and the depth dimension D is approximately 40 μm to 60 μm.

  The base plate 35 adjacent to the lower surface of the cavity plate 36 has a communication hole 28 connected to one end 24 a of each pressure chamber 24, and ink flows toward the actuator 21 in the communication hole 28. The base plate 35 is preferably a plate (thickness dimension T2) thicker than the cavity plate 36 in order to give rigidity to the entire cavity unit. Since it is difficult to drill the communication hole 28 smaller than the thickness T2, the communication hole 28 has a diameter 2R of the thickness. Specifically, the thickness dimension T2 and the diameter 2R are both approximately 100 μm to 150 μm. As shown in FIG. 4, the communication hole 28 has a circular shape in a plan view with a radius R, and a cross-sectional area perpendicular to the ink flow is formed in S2. The cross-sectional area S2 is formed larger than the cross-sectional area S1 of the one end 24a of the pressure chamber 24.

  The supply plate 34 adjacent to the lower surface of the base plate 35 is provided with a connection channel 29 for supplying ink from the common ink chamber 25 to the pressure chambers 24. Each connection channel 29 includes an inlet hole into which ink enters from the common ink chamber 25, an outlet hole that opens to face the communication hole 28, and an inlet hole and an outlet hole. And a throttle portion formed with a reduced cross-sectional area so as to have the largest flow path resistance. One end of the connection channel 29 communicates with the common ink chamber 25, and the other end communicates with the pressure chamber 24 through the communication hole 28. In order to discharge ink from the nozzle 23, the throttle portion prevents the ink from moving backward toward the common ink chamber 25 when the pressure chamber 24 receives discharge pressure, and efficiently advances the ink toward the nozzle 23. It is provided to make it happen.

  The two manifold plates 33a and 33b are formed with two common ink chambers 25 extending through the plate thickness so as to extend along each row of the nozzles 23 along the long side direction (X direction). ing. That is, as shown in FIGS. 2 and 3, two manifold plates 33a and 33b are stacked, and the upper surface thereof is covered with the supply plate 34, and the lower surface is covered with the spacer plate 31, so that a total of two common plates are used. An ink chamber (manifold chamber) 25 is formed. Each common ink chamber 25 overlaps with a part of the pressure chamber 24 and extends in the row direction of the pressure chambers 24 (row direction of the nozzles 23) when viewed in plan from the stacking direction of the plates.

  In addition, as shown in FIG. 2, two ink supply ports 40 are formed in the end portions on one short side of the cavity plate 36, the base plate 35, and the supply plate 34 so as to correspond to the upper and lower positions. Has been. Ink from the ink supply source communicates with the one end portion of the common ink chamber 25 from these ink supply ports 40. In addition, a filter body 40a is attached to the ink supply port 40 with an adhesive or the like.

  In the ink flow path in the cavity unit 20, after ink is supplied from the ink supply port 40 to the common ink chamber 25, as shown in FIG. 3, the ink flows through the connection flow path 29 of the supply plate 34 and the communication hole 28 of the base plate 35. The pressure is distributed and supplied to each pressure chamber 24. Then, the ink passes through the through passage 26 from each pressure chamber 24 and reaches the nozzle 23 corresponding to the pressure chamber 24.

  On the other hand, the piezoelectric actuator 21 has a flat shape having a size extending over all the pressure chambers 24 and a direction perpendicular to the flat direction, similar to the known one disclosed in JP-A-4-341853. And a plurality of electrode layers disposed on the flat surface of the plurality of ceramic layers. Here, an appropriate number of sheet surfaces among a plurality of piezoelectric ceramic material sheets (green sheets) formed by mixing ceramic powder, binder and solvent into a flat shape so that the thickness of each sheet is about 30 μm. The piezoelectric actuator 21 is formed by forming an electrode layer with a conductive paste on the substrate by a printing method or the like, and laminating and firing the plurality of green sheets. Thereby, each green sheet becomes a ceramic layer of a sintered body.

  As the electrode layer, an electrode layer for each electrode formed for each pressure chamber 24 and an electrode layer for a common electrode formed across the plurality of pressure chambers 24 make a pair in the stacking direction of the ceramic layers. And a layer of a surface electrode 46 disposed on the uppermost surface and electrically connected to the flexible flat cable 22 (see FIG. 1). In the piezoelectric actuator 21 provided with the electrode layer in this manner, as is well known, by applying a high voltage between the individual electrode and the common electrode, the portion of the ceramic layer sandwiched between the two electrodes is polarized and activated. Formed as part.

  The piezoelectric actuator 21 thus formed is fixed on the cavity plate 36 so as to cover the pressure chambers 24 with the individual electrodes corresponding to the pressure chambers 24. By selectively applying a drive voltage between the individual electrode and the common electrode, a portion of the ceramic layer sandwiched between the two electrodes is deformed to cause a volume change in the pressure chamber 24. As a result, a discharge pressure is applied to the ink in the pressure chamber, and the ink is discharged from the nozzle 23.

  In the piezoelectric actuator 21, a recess is formed in the surface of the piezoelectric actuator facing the communication hole 28 for each pressure chamber 24 so as to widen the cross-sectional area S <b> 1 in the direction substantially perpendicular to the ink flow direction at the one end 24 a of the pressure chamber 24. 50 is formed (see FIGS. 5A and 5B and FIG. 6C). The recess 50 is formed larger than the upper end opening of the communication hole 28 in plan view (in a direction perpendicular to the wide surface of each plate), and partially overlaps the bottom surface of the pressure chamber 24 toward the other end 24b. It is formed so as to protrude from 28. The ceiling surface of the recess 50 is formed in a shape that descends continuously or stepwise toward the other end 24b side of the pressure chamber 24. The other end 24b extends from the cross-sectional area S2 of the communication hole 28 to the one end 24a of the pressure chamber 24. The cross-sectional area perpendicular to the ink flow toward the side is prevented from changing suddenly. In this embodiment, the recess 50 is a part of a spherical surface, and the recess 50 is provided at a position where it does not interfere with the electrode inside the piezoelectric actuator 21.

  As the manufacturing method of the recess 50, the piezoelectric actuator 21 described above is formed by integrally laminating and firing piezoelectric ceramic material sheets, and then, as shown in FIG. The portion where the recess 50 is to be formed can be formed by removing. As a processing method, laser processing or ultrasonic processing can be applied. FIG. 7A schematically shows a state in which the ultrasonic processing tool 53 is in contact with the surface of the ceramic layer.

  As another manufacturing method of the recess 50, as shown in FIG. 7B, the piezoelectric actuator 21 is fired and the green sheets 54 of the piezoelectric ceramic material are laminated (the sheet surface is soft). In this case, the concave portion 50 may be formed in the piezoelectric actuator 21 by pressing the convex member 51 to provide a depression and then firing the depression.

  As another manufacturing method of the recess 50, as shown in FIG. 7 (c), the piezoelectric actuator 21 is fired and the piezoelectric ceramic material green sheets 54 are laminated as described above (see FIG. 7C). In a state where the sheet surface is soft), a substantially spherical pattern of the resin material 52 may be formed while being pressed, and then the resin material 52 may be removed for manufacturing. Since the green sheet 54 is soft, a depression can be easily formed by pressing the resin material 52 when forming a pattern, and at the same time, the resin material 52 can be embedded in the depression. Since the evaporation temperature of the resin material 52 is generally lower than the baking temperature of the green sheet 54, the resin material 52 is evaporated by the process of baking and integrating the stacked green sheets 54 to form the piezoelectric actuator 21. The recess is removed and the recess 50 remains. In this method, since the firing process of the green sheet 54 is used to remove the resin material 52, it is not necessary to add a special removal process.

  In the ink jet head 1 configured as described above, the ink flowing into the pressure chamber 24 ascends the communication hole 28, hits the piezoelectric actuator 21, and changes its direction at a substantially right angle. It flows toward the other end of 24. At this time, the cross-sectional area S1 of the one end 24a of the pressure chamber 24 is smaller than the cross-sectional area S2 of the communication hole 28, and the depth dimension D of the pressure chamber is sufficiently smaller than the diameter 2R of the communication hole 28. When the bubble grows larger than the depth dimension D inside 28, in the conventional state where the recess 50 is not provided, the bubble remains inscribed in the inner wall of the communication hole 28 and is maintained stably as it is. Therefore, it becomes difficult to flow into the pressure chamber 24, and even if a large pressure is applied during the purge process, it cannot be discharged.

  However, in the present embodiment, the recess 50 is formed in the portion of the piezoelectric actuator 21 corresponding to the one end 24 a of the pressure chamber 24. Therefore, a rapid change in the cross-sectional area is mitigated at a portion where the ink bends and flows from the communication hole 28 to the pressure chamber 24, and the ceiling surface of the recess 50 is further cross-sectional area of the one end 24 a of the pressure chamber 24. When the ink is sucked (or pressurized) by the purge process, the bubbles are brought together with the ink flow. It is quickly discharged from the nozzle 23 through the pressure chamber 24 and the through passage 26.

  In the above embodiment, the case where the inkjet head is disposed horizontally so that the nozzle 23 faces downward and bubbles rise vertically upward from the communication hole 28 has been described. Even in the case where the head is arranged, if ink is sucked (or pressurized) by the purge process, the same effect can be obtained because ink and bubbles flow in the same manner.

  As described above, in the present embodiment, by providing the recess 50, the bubbles contained in the ink can be surely and easily discharged, so that ejection failure from the nozzle can be prevented in advance. Further, since the bubbles can be discharged easily, that is, in a short time, the amount of ink ejected together with the bubbles in the purge process can be suppressed, and wasteful consumption of ink can be prevented. Furthermore, since the pressure of the pump used for the purging process can be reduced, the pump capacity can be lowered and the cost of parts can be reduced.

  In particular, as in the present embodiment, when the plate of the cavity unit 20 is made of metal, the recesses and through holes for forming the ink flow path are often processed by a wet etching method. In the wet etching method, since etching proceeds in the plate surface direction at the same speed as the plate thickness direction, it is extremely difficult to process a recess or a through hole having an inner diameter smaller than the plate thickness. Therefore, if the thickness T2 of the base plate 35 in which the communication hole 28 is formed is increased in order to increase the rigidity of the entire cavity unit 20, the radius R and the cross-sectional area S2 of the communication hole 28 must be increased. On the other hand, in the cavity plate 36 having the pressure chamber 24, the plate thickness T1 is reduced in order to increase the change rate of the cross-sectional area of the pressure chamber 24 due to the operation of the actuator, and is perpendicular to the ink flow in the pressure chamber 24. The cross section has a flat shape. Therefore, for these reasons, from the communication hole 28 to the one end 24a of the pressure chamber, the cross-sectional area is small and flat while bending at a substantially right angle. However, as in the present invention, the piezoelectric actuator 21 side By providing the recess 50 in the air bubble, it is possible to easily remove bubbles without changing the design shape of the pressure chamber 24 and the communication hole 28.

  In the above embodiment, a piezoelectric actuator is exemplified, but any actuator that can form the recess 50 at a position facing the communication hole may be used, and the actuator can be applied to other driving systems such as static electricity.

1 is a perspective view of an inkjet head according to an embodiment of the present invention. It is a disassembled perspective view of an inkjet head. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1. It is a disassembled perspective view of the principal part of a cavity unit. (A) is a longitudinal cross-sectional view of the principal part of a cavity unit, (b) is a bottom view of a piezoelectric actuator. (A) is the VIa-VIa line expanded sectional view of Fig.5 (a), (b) is a typical top view of a communicating hole, (c) is the VIc-VIc line expanded sectional view of Fig.5 (a). (A) is a schematic diagram showing a state in which the concave portion is ultrasonically processed, (b) is a schematic diagram showing a state in which the concave portion is formed with a convex member, and (c) shows a state in which the concave portion is formed with a resin material pattern. It is a schematic diagram. (A) (b) And (c) is a schematic diagram which shows the flow of the ink of the conventional cavity unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 20 Cavity unit 21 Piezoelectric actuator 22 Flexible flat cable 23 Nozzle 24 Pressure chamber 24a One end part 24b Other end part 25 Common ink chamber 26 Through-passage 28 Communication hole 29 Connection flow path 30 Nozzle plate 35 Base plate 36 Cavity plate 50 Recessed part

Claims (7)

A pressure chamber provided corresponding to each of a plurality of nozzles for discharging ink, a common ink chamber for distributing ink to the plurality of pressure chambers, and a communication hole connecting the common ink chamber and the pressure chamber A cavity unit, and an actuator that is attached to the cavity unit so as to cover one side of the pressure chamber and applies discharge pressure to the ink filled in the pressure chamber.
The pressure chamber is formed to flow ink along the actuator from one end connected to the communication hole to the other end connected to the nozzle, and the communication hole is substantially the same as the direction of ink flow in the pressure chamber. An ink jet head that is formed at a right angle and in a direction facing the actuator, and is configured to bend the direction in which the ink passing through the communication hole flows at one end of the pressure chamber at a substantially right angle,
A concave portion is formed for each pressure chamber so as to widen a cross-sectional area in a direction perpendicular to the ink flow at one end of the pressure chamber at a portion of the actuator corresponding to the communication hole. Inkjet head.   The cavity unit is formed by stacking a plate that forms the pressure chamber, a plate that forms the communication hole, and a plate that forms the common ink chamber, and the actuator is formed on the plate that forms the pressure chamber. 2. The ink jet head according to claim 1, wherein the ink jet head is laminated on a side opposite to a plate forming the communication hole.   The cross section of one end of the pressure chamber out of the cross section perpendicular to the ink flow is smaller than the cross section of the communication hole, and is formed flat. The inkjet head as described.   The inkjet head according to claim 1, wherein the concave portion formed in the actuator is formed in a curved shape on the inside. The inkjet head according to any one of claims 1 to 4,
The method of manufacturing an ink jet head, wherein the actuator is a piezoelectric actuator formed by firing a piezoelectric ceramic material, and the recess is formed by removing the piezoelectric ceramic from the fired piezoelectric actuator. . The inkjet head according to any one of claims 1 to 4,
The actuator is a piezoelectric actuator formed by laminating sheets of piezoelectric ceramic material and integrated by firing, and the concave portion is convex to a portion where the concave portion is to be formed in the sheet surface of the piezoelectric ceramic material before firing. A method for manufacturing an ink jet head, characterized in that the ink jet head is formed by providing depressions by pressing with a mold member. The inkjet head according to any one of claims 1 to 4,
The actuator is a piezoelectric actuator formed by laminating sheets of piezoelectric ceramic material and integrated by firing, and the concave portion is formed of a resin in a portion where the concave portion is to be formed on the sheet surface of the piezoelectric ceramic material before firing. A method of manufacturing an ink-jet head, comprising forming a pattern of a material and removing the resin material by baking.

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