JP2012056172A - Liquid droplet injection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid droplet injection head configured to suppress deterioration in ejection efficiency of a pressure chamber, even if a displacement transmitted from a vibrating plate to a protective film is interrupted by the wall of the pressure chamber.SOLUTION: In the liquid droplet injection head, the protective film for protecting against penetration of the liquid into a driving unit configured to pressurize the pressure chamber is provided between the pressure chamber and the driving unit, and also, a groove or channel acceleration unit having different film thickness according to the position of the protective film is formed, accordingly, the liquid in the pressure chamber is injected with sufficient ejection efficiency.

Description

  The present invention relates to a liquid droplet ejecting head that ejects liquid droplets using displacement generated by driving a piezoelectric element.

  2. Description of the Related Art Conventionally, there is a liquid droplet ejecting head that includes a drive unit and a pressure chamber. The drive unit includes a piezoelectric element and a diaphragm. A displacement is generated by driving the piezoelectric element, and the displacement is transmitted to the diaphragm. The diaphragm transmits the displacement generated in the piezoelectric element to the pressure chamber and changes the volume in the pressure chamber. The droplet ejecting head is a mechanism for ejecting droplets in the pressure chamber when the volume in the pressure chamber is changed. As an example of a droplet ejecting head, Patent Document 1 describes a droplet ejecting head having a configuration in which a vibration plate that transmits a displacement generated by driving a piezoelectric element is provided to face a pressure chamber. The diaphragm is a metal film that is resistant to the liquid in the pressure chamber in order to prevent the printing characteristics of the liquid droplet ejecting head from changing due to the ink in the pressure chamber coming into contact with the diaphragm. A protective film is provided.

JP 2009-148985 A

  However, the protective film in the droplet ejecting head described in Patent Document 1 is made of a hard metal film, and is provided on the entire surface of the diaphragm facing the pressure chamber. In that case, the displacement of the protective film is limited at the corners between the partition wall defining the pressure chamber and the diaphragm. Further, the displacement transmitted from the diaphragm to the protective film is also hindered by the partition that partitions the pressure chamber. Therefore, since the displacement transmitted to the diaphragm is inhibited by driving the piezoelectric element, there is a problem in that the ejection performance of the droplet due to the volume change of the pressure chamber is lowered and the ejection efficiency is poor.

  The present invention has been made to solve the above-described problems, and suppresses the influence of the partition walls defining the pressure chamber against the displacement transmitted from the driving piezoelectric element to the protective film, thereby reducing the liquid droplets in the pressure chamber. An object of the present invention is to provide a liquid droplet ejecting head that suppresses a decrease in the discharge efficiency.

  In order to achieve this object, a liquid droplet ejecting head according to claim 1 is provided with a pressure chamber connectable to a liquid supply source, a drive unit provided opposite to the pressure chamber and pressurizing the pressure chamber; A first region corresponding to the opposing drive unit and the pressure chamber; and a second region corresponding to the pressure chamber and surrounding the first region, wherein the liquid in the pressure chamber is A protective film that prevents penetration into the drive unit, and the protective film has a thickness of a film outside a region where the drive unit is perpendicularly projected with respect to a surface facing the pressure chamber. A thin portion that is thinner than the thickness of the film in the region is formed.

  Further, in the liquid droplet ejecting head according to claim 2, in the second region, the thin portion is between the surface on the driving unit side and the surface on the pressure chamber side in the first region of the protective film. The thin portion has a film thickness that prevents liquid from penetrating into the driving portion.

  The liquid droplet ejecting head according to claim 3, wherein the pressure chamber includes a discharge port for discharging a liquid supplied from the liquid supply source, and the protective film includes the first region in the second region. A groove having the thin portion is formed on the discharge port side from the region.

  According to a fourth aspect of the present invention, in the liquid droplet ejecting head, the groove of the protective film is inclined with respect to the pressurizing direction of the driving unit.

  Further, in the liquid droplet ejecting head according to claim 5, the pressure chamber includes a supply port to which a liquid is supplied from the liquid supply source, and a discharge port for discharging the liquid. A flow path promoting portion is formed such that the film thickness in one region gradually decreases from the supply port toward the discharge port.

  The liquid droplet ejecting head according to claim 1, wherein the protective film is provided in a first region where the protective film is provided corresponding to the driving unit and the pressure chamber facing each other, and in the region around the first region corresponding to the pressure chamber. The second region is formed to have a different film thickness. With the configuration in which the thickness of the protective film in the second region is thinner than that in the first region, the displacement transmitted from the driving unit to the protective film is less likely to be inhibited by the end of the pressure chamber, and the driving The displacement of the portion can be efficiently reflected in the droplet ejection performance.

  According to a second aspect of the present invention, the protective film is formed with a predetermined film thickness in order to protect the liquid from penetrating the driving unit. The displacement transmitted from the driving unit to the protective film is more easily inhibited by the end of the pressure chamber as the protective film is thicker. In the protective film, the thickness of the thin-walled portion is a thickness that prevents liquid from penetrating into the driving unit. Accordingly, the driving unit is prevented from being short-circuited and the displacement of the driving unit is prevented from being obstructed by the end of the pressure chamber as much as possible, and the displacement of the driving unit is efficiently discharged. It can be reflected in performance.

  According to a third aspect of the present invention, a discharge port for discharging a liquid is provided in the pressure chamber, and a groove is formed on the discharge port side of the protective film. When the displacement of the driving unit is transmitted to the protective film, the wall on the first region side of the groove is displaced. When the groove is deformed, it acts as a pump for discharging the gas and liquid existing around the groove from the pressure chamber, thereby efficiently reflecting the displacement generated by the driving unit in the droplet discharge performance. Can be made.

  According to a fourth aspect of the present invention, the groove is inclined with respect to the pressurizing direction of the driving unit. Since the groove is inclined, the liquid flows in a direction different from the pressurizing direction of the driving unit, and the liquid is discharged toward the discharge port provided in the pressure chamber. Thereby, the gas and liquid existing around the groove can be efficiently discharged from the pressure chamber in consideration of the pressurizing direction of the driving unit.

  According to a fifth aspect of the present invention, there is formed a flow path promoting portion in which the protective film gradually becomes thinner from the supply port provided in the pressure chamber toward the discharge port. The displacement transmitted from the drive unit by the flow channel promoting unit is converted into a force in a direction that takes into account the flow channel direction of the liquid flowing from the supply port side to the discharge port side, so that liquid is discharged from the supply port. It is easy to flow to the outlet and can be efficiently discharged from the discharge port.

1 is an exploded perspective view of a piezoelectric inkjet head 1 in Embodiment 1. FIG. 2 is a partial cross-sectional view of the piezoelectric inkjet head 1. FIG. 2 is a diagram illustrating a configuration of an ink permeation protective film 20 of the piezoelectric inkjet head 1 according to Embodiment 1. FIG. 6 is a diagram illustrating a configuration of an ink permeation protective film 120 according to Embodiment 2. FIG. FIG. 6 is a diagram illustrating a configuration of an ink permeation protection film 220 according to a third embodiment. FIG. 6 is a diagram illustrating a configuration of an ink permeation protective film 320 according to a fourth embodiment. It is a figure which shows the modification of the said piezoelectric inkjet 1 of this Embodiment 1. FIG.

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

<Embodiment 1>
The overall configuration of the piezoelectric inkjet head 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is an exploded perspective view of the piezoelectric inkjet head 1. FIG. 2 is a partial cross-sectional view of the piezoelectric inkjet head 1 shown in FIG. The left-right direction, the up-down direction, and the front-rear direction in Embodiment 1 are defined as shown in FIG. The piezoelectric inkjet head 1 includes a cavity unit 10, an actuator 30, and a flexible wiring material 40. As shown in FIG. 1, the piezoelectric inkjet head 1 has a structure in which the actuator 30 is stacked on the cavity unit 10 in an upward direction, and the flexible wiring member 40 is stacked on the actuator 30.

  As shown in FIG. 2, the cavity unit 10 includes a nozzle plate 11, a spacer plate 12, a manifold 13, a supply plate 14, a base plate 15, and a cavity plate 16. The nozzle plate 11 is provided with a number of nozzle openings 17 on the front, rear, left and right. The manifold 13 is provided with a large number of ink chambers 18 serving as ink flow paths in the front, rear, left and right directions. In addition, the cavity plate 16 is provided with a number of pressure chambers 19 that are partitioned in the left-right and front-rear directions by partition walls. Each of the nozzle plate 11, the spacer plate 12, the manifold 13, the supply plate 14, and the base plate 15 is formed with many through holes at substantially the same position in the left-right direction. In the cavity plate 16, as shown in FIG. 1, a plurality of rows in which the pressure chambers 19 are arranged in the left-right direction are arranged in four rows in the front-rear direction. In addition, each of the ink chamber 18, the hole, and the nozzle port 17 is provided so as to correspond to one pressure chamber 19.

  The numerous holes formed in each of the plates 12 to 15 correspond to positions where the numerous nozzle openings 17 of the nozzle plate 11 are formed, and are formed in the upward direction of the nozzle openings 17. Each of the plurality of pressure chambers 19 is arranged corresponding to each one of the nozzle ports 17, and one of the pressure chambers 19 and one of the nozzle ports 17 has the holes. It is communicated through.

  Further, the supply plate 14 and the base plate 15 are formed with a number of through passages penetrating at positions different from the holes. One ink chamber 18 is arranged corresponding to one pressure chamber 19 and communicates with one through passage. With this configuration, ink is supplied from a liquid supply source such as an ink cartridge (not shown) to the ink chamber 18, passes through the pressure chamber 19 through the through passage, passes through the hole, and passes through the hole from the nozzle port 17. The ink jet head 1 can be ejected outside.

  The cavity unit 10 is formed by sequentially laminating a nozzle plate 11, a spacer plate 12, a manifold 13, a supply plate 14, and a base plate 15. At this time, each of the plates 11 to 15 is arranged so that each of the penetrated holes is in the same position in the upward direction, and each one of the nozzle ports 17 and each of the one pressure chamber 19 are communicated. So that they are positioned. Further, the supply plate 14 and the base plate 15 are positioned so that the ink chamber 18 and the pressure chamber 19 communicate with each other through the through passage. The base plate 15 is joined to a cavity plate 16 formed on the actuator 30 side after an ink permeation protection film 20 is provided in the pressure chamber 19 as will be described later. A supply port 27 is provided at a position where the pressure chamber 19 communicates with the ink chamber 18. In the cavity unit 10, the pressure chamber 19 is disposed below the individual electrode 31 so as to correspond to the arrangement of the individual electrode 31 when an individual electrode 31 described later is vertically projected downward from the upper surface side. The upper surface of the cavity plate 16 is joined to the actuator 30.

  The actuator 30 includes eight piezoelectric sheet layers 35 made of a piezoelectric ceramic material such as lead zirconate titanate (PZT). Between the piezoelectric sheet layers 35, the individual electrodes 31 or the common electrodes 32 are laminated so as to be alternately arranged in the upward direction. As shown in FIG. 2, the individual electrodes 31 and the common electrodes 32 are alternately arranged so as to face each other across the seven piezoelectric sheet layers 35 excluding the uppermost piezoelectric sheet layer 35. The Each of the piezoelectric sheet layers 35 has a thickness of about 30 μm and is disposed in common with the plurality of pressure chambers 19.

  As shown in FIG. 1, surface electrodes 33 and 34 are formed on the uppermost surface of the actuator 30. The surface electrodes 33 and 34 are formed corresponding to the individual electrode 31 and the common electrode 32 shown in FIG. The surface electrodes 33 and 34 shown in FIG. 1 are electrically connected to the individual electrode 31 and the common electrode 32 through a conductive material filled in a through hole (not shown) of the actuator 30. The lowermost surface of the actuator 30 is joined to the upper surface of the cavity plate 16 with an adhesive or the like. At this time, as described above, the actuator 30 is joined so that the individual electrode 31 is arranged in parallel with the pressure chamber 19 in the vertical direction.

  In the actuator 30, a plurality of the individual electrodes 31 are formed in four rows in the left-right direction of the front / rear / left / right plane, and a plurality of individual electrodes 31 are arranged in such a manner that their long sides face each other. The cavity unit 10 and the actuator 30 are joined in such an arrangement that the pressure chamber 19 and the individual electrode 31 correspond to each other one to one. Further, the flexible wiring member 40 is placed on the upper surface of the actuator 30.

  The flexible wiring member 40 is provided with a wiring pattern for transmitting a control signal from the outside. Specifically, the individual terminals 41 are arranged corresponding to the surface electrodes 33, and the common terminals 42 are arranged corresponding to the surface electrodes 34. Further, the driving IC chip 43 that houses the driving circuit mounted on the flexible wiring member 40, the wiring 44 extending from the driving IC chip 43, and the common potential conductor formed along the outer periphery of the flexible wiring member 40. 45 is arranged. In the flexible wiring member 40, the wiring 44 and the common potential conducting wire 45 are electrically connected to the actuator 30 by being connected to the terminals 41 and 42, respectively.

  The drive IC chip 43 of the flexible wiring member 40 applies a voltage having a predetermined potential difference between the individual electrode 31 and the common electrode 32 to the cavity unit 10 and moves the corresponding upper surface of the pressure chamber 19 up and down. Displace selectively in the direction. When the internal volume of the pressure chamber 19 changes and decreases due to the displacement generated by driving the driving IC chip 43, the ink existing in the pressure chamber 19 is ejected from the nozzle port 17. In the first embodiment, a positive potential is applied to the individual electrode 31 and a ground potential is applied to the common electrode 32.

  When a voltage is applied between the individual electrode 31 and the common electrode 32, an electroosmosis phenomenon in which ink existing in the pressure chamber 19 penetrates into the actuator 30 occurs. Depending on the strength of the voltage applied between the electrodes 31 and 32, the electroosmosis phenomenon of ink may occur, and the actuator 30 may be short-circuited. In the first embodiment, in order to prevent a short circuit of the actuator 30 due to the electroosmosis phenomenon of ink, the pressure chamber 19 of the cavity unit 10 is provided on the lowermost surface of the actuator 30 corresponding to the individual electrode 31. Inside, the ink permeation protective film 20 is formed. Hereinafter, the configuration of the ink permeation protective film 20 will be described in detail.

  FIG. 3 shows the pressure chamber 19 of the cavity unit 10 and a part of the individual electrode 31 and the common electrode 32 of the actuator 30 joined to the upper surface of the cavity plate 16 according to the first embodiment. FIG. 3 is a diagram showing an arrangement relationship with a piezoelectric sheet layer and a structure inside the pressure chamber. As shown in FIG. 3, the ink permeation protective film 20 is formed on the lowermost surface of the actuator 30 in a region inside the pressure chamber 19 by a coating forming method described later.

  FIG. 3A is a top view showing the arrangement relationship between the individual electrode 31 and the pressure chamber 19. FIG. 3B is a cross-sectional view showing the shape of the ink permeation protective film 20 corresponding to the arrangement of the individual electrodes 31 and the pressure chambers 19 shown in FIG. In the first embodiment, the individual electrodes 31 are provided one by one corresponding to the one pressure chamber 19. The individual electrode 31 is positioned substantially at the center of the left and right front and back planes in the pressure chamber 19 when vertically projected from above the individual electrode 31 downward to the pressure chamber 19. Provided in an embodiment.

  The ink permeation protection film 20 has a one-layer structure including an upper protection part 21 and a lower protection part 22, and prevents ink from penetrating into the actuator 30. The upper protective portion 21 of the ink permeation protective film 20 provided on the upper surface of the pressure chamber 19 disposed below the piezoelectric sheet layer 35 has a substantially uniform thickness over the entire surface. The thickness of the upper protection portion 21 in the vertical direction is the thinnest thickness necessary to prevent the ink existing in the pressure chamber 19 from being electro-osmotic into the actuator 30. In the first embodiment, the thickness of the upper protective portion 21 is about 1 μm or less. Further, the ink permeation protection film 20 has a lower protection part 22 below the upper protection part 21. The lower protective part 22 has a thickness that is substantially equal to the thickness of the upper protective part 21 at its thickest part. The ink permeation protection film 20 is formed of a silica-based oxide film, a silica-based nitride film, a DLC (Diamond Like Carbon) film, or the like. Specifically, SiO2, SiN, SiCN or the like is used.

  In the first embodiment, the ink permeation protection film 20 is configured such that the upper protection portion 21 and the lower protection portion 22 are formed in one layer. Then, a partial removal process is performed on the formed lower protective part 22 as described later. Further, the covering formation of each of the protection portions 21 and 22 may be performed in two steps, that is, the upper protection portion 21 and the lower protection portion 22. In that case, the upper protection part 21 is first formed by covering, and then the lower protection part 22 is formed by covering the upper protection part 21.

  The ink permeation protective film 20 has a lower region 25A and an outer region 25B on the left and right front and back planes. The lower region 25A is a region corresponding to a region where the individual electrode 31 is provided when vertically projected from above the individual electrode 31 to the lower direction of the pressure chamber 19, and the outer region 25B is the lower region. This is a partition side region that divides the pressure chamber 19 from 25A. In the lower protection part 22, an inverted V-shaped groove 23 having a thin part 50 at the center is formed in the outer region 25B. Further, in the pressure chamber 19, in a region below the region where the lower protective portion 22 is provided, along the partition wall that defines the pressure chamber 19, the same as the upper protective portion 21 and the lower protective portion 22. The ink permeation protective film is formed. With this configuration, it is possible to prevent a possibility that the ink in the pressure chamber 19 is electroosmotic along the partition wall and the actuator 30 is short-circuited. The lower area 25A in the first embodiment is an example of the first area of the present invention, and the outer area 25B is an example of the second area of the present invention.

  The ink permeation protection film 20 is first formed in a state where the cavity plate 16 is joined corresponding to the actuator 30. The ink permeation protection film 20 is formed in the pressure chamber 19 on the lowermost surface of the actuator 30 by a predetermined coating forming method. Examples of the coating formation method include chemical vapor deposition (plasma, heat, light and laser CVD), sputtering (direct current, high frequency, magnetron and ion sputtering), and physical vapor deposition (vacuum and low pressure atmosphere deposition). Law).

  In the first embodiment, the actuator 30 to which the cavity unit 10 is bonded is filled with a predetermined gas, which is a raw material, in one CVD apparatus (not shown) by a plasma CVD method, and the upper protection unit 21 and the lower protection are made. A method of covering and forming the ink permeation protective film 20 including the portion 22 is used. At this time, the ink permeation protective film 20 is also formed on the partition walls defining the pressure chamber 19. Further, the groove 23 is formed by partially removing the lower protective portion 22 of the formed ink permeation protective film 20 by a plasma etching method, a laser processing method, or the like. As a result, the ink permeation protection film 20 having the groove 23 is formed in the pressure chamber 19 on the lowermost surface of the actuator 30 and on the partition that partitions the pressure chamber 19.

  After the ink permeation protection film 20 is formed, the base plate 15, the supply plate 14, the manifold 13, the spacer plate 12, and the nozzle plate 11 are stacked below the cavity plate 16. The plates 11 to 15 are joined in order so that the nozzle port 17 of the nozzle plate 11 is penetrated from the pressure chamber 19 of the cavity plate 16. Thereby, the piezoelectric inkjet head 1 is formed.

<Operation>
A state change of the pressure chamber 19 in which the ink permeation protective film 20 is formed when the piezoelectric inkjet head 1 is used will be described. As shown in FIG. 2, the pressure chamber 19 is connected to the supply port 27 below the left end through the through passage through which ink is supplied from the ink chamber 18, and from the nozzle port 17 below the right end. The holes for ejecting ink are communicated. With this configuration, the ink flows from the right direction to the left direction in the pressure chamber 19. When the actuator 30 is driven, a downward displacement is generated in the individual electrode 31. The displacement of the individual electrode 31 is transmitted to the upper surface of the pressure chamber 19 through the piezoelectric sheet layer 35 provided on the lowermost surface of the actuator 30. When the displacement is transmitted to the pressure chamber 19, the lower region 25A of the ink permeation protection film 20 provided in the pressure chamber 19 corresponding to the individual electrode 31 is displaced downward. The pressure chamber 19 is pressurized by the downward displacement of the ink permeation protection film 20 that occurs in the individual electrode 31. The pressurized pressure chamber 19 causes the ink present in the pressure chamber 19 to be ejected from the nozzle port 17 by reducing the volume.

  The displacement generated in the individual electrode 31 is transmitted radially in the ink permeation protective film 20. Specifically, the displacement from the individual electrode 31 is transmitted to the lower region 25A of the upper protective part 21, and the lower region 25A of the upper protective part 21 is transferred to the lower region 25A of the lower protective part 22. Reportedly. Further, the displacement is transmitted to the outer region 25 </ b> B of the upper protection portion 21 in a direction from the lower region 25 </ b> A toward the partition that partitions the pressure chamber 19. Displacement is transmitted to the outer region 25 </ b> B of the lower protective part 22, particularly from the lower region 25 </ b> A of the lower protective part 22. When the lower surface of the lower region 25 </ b> A of the lower protection part 22 is displaced downward, the volume in the pressure chamber 19 is changed, and ink staying in the pressure chamber 19 is ejected from the nozzle port 17. Is done.

  Further, the outer region 25B of the lower protective part 22 is formed with the groove 23 having the thin part 50 in which the thickness of the lower protective part 22 is thinner than that of the lower region 25A. The groove 23 includes an inner wall 23A on the lower region 25A side with the thin portion 50 in the center, and an outer wall 23B on the partition wall side.

  In particular, in the manufacturing process, the piezoelectric inkjet 1 is likely to have foreign matters when the flexible wiring member 40 is placed on the upper surface of the actuator 30. Due to the foreign matter, a crack is generated in the piezoelectric sheet 35. Cracks are likely to occur in the surface electrodes 33 and 34 and the lower region 25A of the individual electrode 31 existing in the region below the surface electrode. In particular, the lower region 25A is likely to occur near the center. Therefore, by setting the thickness of the protective film in the lower region 25A of the ink permeation protective film 20 to be thicker than that of the outer region 25B, the effect of preventing the electrical permeation of ink into the actuator 30 can be enhanced. it can.

  Further, due to the configuration in which the groove 23 having the thin portion 50 is formed in the outer region 25B of the lower protection portion 22, the displacement in the direction toward the partition wall transmitted from the lower region 25A can be reduced. It is transmitted to the wall 23A and not transmitted to the outer wall 23B. Due to the thin portion 50, the displacement from the individual electrode 31 is not transmitted to the partition wall defining the pressure chamber 19 in the lower protection portion 22, so that the displacement is not hindered by the partition wall. The displacement of the electrode 31 can be efficiently reflected in the ink ejection.

  The upper protection portion 21 of the ink permeation protection film 20 is configured to prevent the actuator 30 from being short-circuited due to the electroosmosis phenomenon of ink. Further, the lower protection part 22 has a thickness of about 1 μm in the lower region 25A. The groove 23 in the outer region 25B of the lower protection part 22 is provided with the thin part 50 having a thickness of about 0 μm or more and about 0.5 μm or less. In the lower protection part 22, the outer region 25 </ b> B has a structure that is thinner than the lower region 25 </ b> A, so that the displacement transmitted from the individual electrode 31 is hindered by the partition that partitions the pressure chamber 19. In this case, the ink in the pressure chamber 19 can be efficiently discharged from the nozzle port 17.

  Further, in the lower protective part 22, the inner wall 23 </ b> A of the groove 23 can be displaced in the direction of the partition wall defining the pressure chamber 19. On the other hand, the outer wall 23 </ b> B of the groove 23 is fixed to a partition partitioning the pressure chamber 19. When the individual electrode 31 is driven and displacement is transmitted to the ink permeation protection film 20, the outer wall 23 </ b> B of the groove 23 is not displaced, and the inner wall 23 </ b> A is in a direction to partition the pressure chamber 19. Displace. As a result, the width in the left-right direction between the walls 23A and 23B of the groove 23 of the lower protective portion 22 is contracted. The ink and gas staying between the two inner walls 23A and the outer wall 23B of the groove 23 are moved into the nozzle opening when the individual electrode 31 is driven and the width of the groove 23 is contracted. The momentum flowing toward 17 increases. The groove 23 plays a role like a pump when the width is contracted, and ink discharged from the nozzle port 17 is controlled by controlling the flow of ink and gas existing in the pressure chamber 19. The amount of ink increases, and ink ejection performance is improved.

  Hereinafter, Embodiments 2 to 5 of the present invention will be described with reference to the drawings. The second to fifth embodiments are different from the first embodiment in the shape and structure of the ink permeation protective film provided in the pressure chamber and the change in the shape of the ink permeation protective film when the individual electrode 31 is driven. Embodiments 2 to 5 are the same as those in Embodiment 1 except for the configuration other than the ink permeation protective film. Therefore, only different configurations will be described in detail, and the same configurations as those in Embodiment 1 will be described. Omitted. Specific configurations of Embodiments 2 to 5 will be described in order.

<Embodiment 2>
FIG. 4 is a diagram showing an outline of the ink permeation protective film 120 provided on the upper surface of the pressure chamber 19 in the second embodiment. FIG. 4A is a top view showing the arrangement relationship between the individual electrode 31 and the pressure chamber 19. 4B is a longitudinal sectional view showing the shape of the ink permeation protective film 120 corresponding to the arrangement of the individual electrodes 31 and the pressure chambers 19 shown in FIG. As shown in FIG. 4B, the ink permeation protection film 120 has an upper protection part 121 on the upper surface of the pressure chamber 19 disposed below the piezoelectric sheet layer 35, and further includes the upper protection part. The lower protection part 122 is formed below the 121. The arrangement and configuration of the actuator 30 provided corresponding to the pressure chamber 19 are the same as those in the first embodiment. Further, the ink in the pressure chamber 19 flows from the left to the right as in the case of the first embodiment. The upper protective part 121 and the lower protective part 122 are formed by the same coating formation method as the upper protective part 21 and the lower protective part 22 of the first embodiment described above. The ink permeation protection film 120 has a lower region 125A and an outer region 125B. The lower region 125A is a region corresponding to a region where the individual electrode 31 is provided when the pressure chamber 19 is vertically projected downward from the upper side of the individual electrode 31 to the pressure chamber 19. The outer region 125B is a partition side region that partitions the pressure chamber 19 from the lower region 125A.

  In the second embodiment, the thickness of the upper protective portion 121 of the ink permeation protective film 120 is the most necessary for preventing the ink in the pressure chamber 19 from electrically penetrating into the actuator 30. Thin thickness. The thickest part of the lower protective part 122 has a thickness equal to that of the upper protective part 121. The lower protective part 122 is different from the first embodiment in the shape of the outer region 125B.

  The upper protective part 121 is formed with the same thickness in the vertical direction in the region inside the pressure chamber 19, but the lower protective part 122 has an inclined part 123 that is inclined with respect to the upper surface of the pressure chamber 19. Provided. The inclined portion 123 is provided in the outer region 125B of the lower protective portion 122, and an inclined surface is formed so as to have a film thickness on the lower region 125A side and a thin film on the partition wall side that defines the pressure chamber 19. The The inclined portion 123 of the lower protective portion 122 has the largest thickness on the lower region 125A side, and is gradually formed thinner toward the partition wall side that defines the pressure chamber 19, and the pressure chamber 19 is The thinnest portion 150 is provided at the position adjacent to the partition wall to be partitioned. The lower region 125A is provided with a thickness of about 1 μm, and the outer region 125B constituting the thin portion 150 is provided with a thickness of about 0 μm or more and less than about 1 μm. The lower protective part 122 of the outer region 125B is provided so as to be gradually thinner toward, for example, a partition wall that partitions the pressure chamber 19. The inclined portion 123 is formed after the upper protective portion 121 and the lower protective portion 122 of the ink permeation protective film 120 are covered with the actuator 30 in the same manner as the formation procedure of the groove 23 of the first embodiment. The film is partially removed by a plasma etching method, a laser processing method, or the like. When the inclined portion 123 is formed, the ink permeation protection film 120 that is formed so as to cover the partition walls that define the pressure chamber 19 is also removed.

  The displacement generated in the individual electrode 31 is transmitted to the lower protective part 122 through the upper protective part 121. The lower area 125A of the lower protection part 122 transmits the displacement transmitted from the upper protection part 121 to the outer area 125B, and the inclination angle of the inclined part 123 is changed. When the angle of inclination of the inclined part 123 is changed, the volume of the pressure chamber 19 changes, and in particular, ink and gas staying in the lower periphery of the inclined part 123 are flowed downward. Since the outer region 125B of the lower protective part 122 includes the thin part 150 having a thickness smaller than that of the lower region 125A, the displacement is transmitted to the inclined part 123 but not to the partition wall. With this configuration, the displacement of the lower protective portion 122 in the outer region 125 </ b> B can be efficiently reflected in the ink ejection without being obstructed by the partition walls defining the pressure chamber 19.

  When the individual electrode 31 is driven, the volume of the pressure chamber 19 changes due to the displacement of the inclined portion 123. The ink that is present in the pressure chamber 19 is improved in its fluidity by the displacement of the inclined portion 123. Since the inclined portion 123 functions as a pump that moves to the nozzle port 17 side by being displaced, the momentum of ink flowing in the pressure chamber 19 is improved, and the nozzle port 17 As a result, the amount of ink and the gas flowing in the direction increase, and the ink ejection performance is improved.

<Embodiment 3>
FIG. 5 is a cross-sectional view schematically showing the ink permeation protective film 220 provided on the upper surface of the pressure chamber 19 in the third embodiment. FIG. 5A is a top view showing the arrangement relationship between the individual electrode 31 and the pressure chamber 19. FIG. 5B is a longitudinal sectional view showing the shape of the ink permeation protective film 220 corresponding to the arrangement of the individual electrodes 31 and the pressure chambers 19 shown in FIG. As shown in FIG. 5B, the ink permeation protection film 220 includes an upper protection part 221 on the upper surface of the pressure chamber 19 disposed below the piezoelectric sheet layer 35, and the upper protection part 221. A lower protective part 222 is provided below the lower part. The arrangement and configuration of the actuator 30 provided corresponding to the pressure chamber 19 are the same as those in the first embodiment. The ink in the pressure chamber 19 flows in the same direction as in the first embodiment. The upper protection part 221 and the lower protection part 222 are formed by the same coating formation method as the upper protection part 21 and the lower protection part 22 of the first embodiment described above. The ink permeation protection film 220 has a lower region 225A and an outer region 225B. The lower region 225A is a region corresponding to a region where the individual electrode 31 is provided when the pressure chamber 19 is vertically projected from the upper side of the individual electrode 31 downward, and the lower region 225B is This is an area on the partition side that divides the pressure chamber 19 from the lower area 225A.

  In the third embodiment, the upper protective part 221 is formed to have the same thickness in the vertical direction in the region inside the pressure chamber 19. The thickness of the upper protection part 221 is the thinnest thickness necessary for preventing the ink in the pressure chamber 19 from electroosmotically passing through the actuator 30. The lower protective part 222 is formed in the approximate center of the pressure chamber 19 with the same thickness as the upper protective part 221 and slightly larger than the lower region 225A. The outer region 225 </ b> B is formed with an ink permeation protection film similar to the upper protection part 21 and the lower protection part 22 along the partition walls that define the pressure chamber 19. A groove 223 is formed around the lower protective part 222 and between the lower protective part 222 and the partition wall in the outer region 225B. In the third embodiment, the groove 223 is formed by coating the upper protection portion 221 and the lower protection portion 222 after the covering of the upper protection portion 221 and the lower protection portion 222 in the same manner as the formation procedure of the groove 23 in the first embodiment. It is formed by partial removal by laser processing or the like. In addition, the said groove | channel 223 in this Embodiment 3 is an example of the thin part of this invention.

  When the displacement generated in the individual electrode 31 is transmitted to the ink permeation protection film 220, the lower region 225A of the upper protection part 221 is displaced downward. The displacement transmitted by the upper protection unit 221 is transmitted to the lower protection unit 222. In the lower protection part 22, the displacement from the individual electrode 31 is not transmitted to the partition walls defining the pressure chamber 19 by the groove 223, so that the displacement is not hindered by the partition walls, and the individual electrode The displacement of 31 can be efficiently reflected in the ink ejection.

  Since the groove 223 is provided in the outer region 225B of the lower protective part 222, the displacement transmitted from the lower region 222A of the lower protective part 222 is transmitted to the partition and is inhibited. Without being reflected in the ink ejection efficiently.

  In addition, since the partition wall defining the pressure chamber 19 is fixed, the groove 223 sandwiched between the lower protection member 222 and the partition wall partitioning the pressure chamber 19 due to the displacement of the lower protection member 222. The width of becomes narrower. The groove 223 formed in the outer region 225B is contracted in width corresponding to the displacement of the individual electrode 31 and functions like a pump, and causes ink and gas to flow downward. As a result, the momentum at which the ink and gas staying inside the groove 223 flow is improved, and the ink ejection performance toward the nozzle port 17 is improved.

<Embodiment 4>
FIG. 6 is a diagram showing an outline of the ink permeation protective film 320 formed in the pressure chamber 19 in the fourth embodiment. FIG. 6A is a top view showing the arrangement relationship between the individual electrode 31 and the pressure chamber 19. FIG. 6B is a longitudinal sectional view showing the shape of the ink permeation protective film 20 corresponding to the arrangement of the individual electrodes 31 and the pressure chambers 19 shown in FIG. As shown in FIG. 6B, the ink permeation protection film 320 has an upper protection part 321 on the upper surface of the pressure chamber 19 disposed below the piezoelectric sheet layer 35, and the upper protection part 321. The lower protective portion 322 is provided below the lower portion. The arrangement and configuration of the actuator 30 provided corresponding to the pressure chamber 19 are the same as those in the first embodiment. The ink in the pressure chamber 19 flows in the same direction as in the first embodiment. The upper protection part 321 and the lower protection part 322 are formed by the same method as the upper protection part 21 and the lower protection part 22 of the first embodiment described above. The ink permeation protection film 320 has a lower region 325A and an outer region 325B. The lower region 325A is a region corresponding to a region where the individual electrode 31 is provided when the pressure chamber 19 is vertically projected from the upper side of the individual electrode 31 downward, and the outer region 325B is This is a partition side region that divides the pressure chamber 19 from the lower region 325A.

  In the ink permeation protection film 320, the upper protection part 321 is formed with the thinnest thickness necessary for preventing the ink in the pressure chamber 19 from being electrically permeated into the actuator 30. . In the lower protection part 322, the flow path promoting part 323 having a slope with respect to the upper surface of the pressure chamber 19 is formed in the lower area 325A, and no film is formed in the outer area 325B. Inside the pressure chamber 19, a supply port 27 is provided in the right direction, and the nozzle port 17 is communicated in the left direction. The supplied ink flows from the right direction to the left direction. The flow path promoting portion 323 has a thickness in the vertical direction of the lower protective portion 322 at an arbitrary position in the pressure chamber 19 that is the thickest on the supply port 27 side of the pressure chamber 19 and on the nozzle port 17 side. It is formed so as to be thinnest. For example, the slope is formed so as to gradually become thinner from the upstream supply port 27 side in the ink flow direction toward the downstream nozzle port 17 side.

  In the fourth embodiment, the flow path promoting portion 323 is formed by removing unnecessary portions after the upper protective portion 321 and the lower protective portion 322 of the ink permeation protective film 320 are formed. Processing to leave the shape of the flow path promoting portion 323 is performed. Specifically, a region in the vicinity of the partition wall defining the pressure chamber 19 of the lower protective portion 322 is partially removed by a plasma etching method, a laser processing method, or the like. When forming the flow path promoting part 323, the ink permeation protection film 320 formed on the partition walls defining the pressure chamber 19 is removed.

  In the lower protective part 322, the flow path promoting part 323 is provided in the lower region 325A. In the outer region 325 </ b> B, the lower protection part 322 is not formed, and the thin part 350 including only the upper protection part 321 is provided. The lower protective part 22 is not provided in the outer region 325B, and the thin part 350 is formed, so that the displacement from the individual electrode 31 is transmitted to the partition walls defining the lower pressure chamber 19. Therefore, the displacement of the individual electrode 31 can be efficiently reflected in the ink ejection without being disturbed by the partition wall.

  In the third embodiment, the upper protection part 321 is formed to have the same thickness in the vertical direction in the region inside the pressure chamber 19. The thickness of the upper protection portion 321 is the thinnest thickness necessary for preventing the ink in the pressure chamber 19 from electroosmotically passing through the actuator 30. The lower protection part 322 is formed in the middle of the pressure chamber 19 with the same thickness as the upper protection part 321 and slightly larger than the lower region 325A. The thin portion 350 is formed around the lower protective portion 322 and between the lower protective portion 322 and the partition in the outer region 325B. In the third embodiment, the groove 323 is formed after the upper protective portion 321 and the lower protective portion 322 are formed by coating, similarly to the formation procedure of the groove 23 in the first embodiment. It is formed by partial removal by laser processing or the like.

  When the displacement generated in the individual electrode 31 is transmitted to the ink permeation protection film 320, the lower region 325A of the upper protection portion 221 is displaced downward. The displacement transmitted by the upper protection part 321 is transmitted to the lower protection part 322. In the lower protection part 322, the displacement from the individual electrode 31 is not transmitted to the partition walls that define the pressure chamber 19 by the groove 323, so that the displacement is not hindered by the partition walls, and the individual electrode The displacement of 31 can be efficiently reflected in the ink ejection.

  When the displacement generated in the individual electrode 31 is transmitted to the ink permeation protection film 320, the lower region 325A of the upper protection portion 321 is displaced downward. The displacement of the upper protection part 321 is transmitted to the lower protection part 322, and the flow path promoting part 323 is displaced downward. When the ink permeation protection film 320 is displaced downward, the volume of the pressure chamber 19 decreases. At this time, since the flow path promoting portion 323 is displaced downward, the ink staying below the flow path promoting portion 323 moves in the pressure chamber 19. Since the flow path promoting portion 323 has a slope shape in consideration of the ink flow direction, the ink existing below the flow path promoting portion 323 flows from the supply port 27 side to the nozzle port 17 side. The ink in the pressure chamber 19 can be efficiently ejected easily.

(Modification)
In the first embodiment, each of the individual electrodes 31 corresponds to each of the pressure chambers 19 and is provided on the inner side of the partition that partitions the pressure chambers 19. The arrangement and configuration of 31 are not limited to this. For example, as shown in FIG. 7A, when the vertical projection is performed downward from the upper side of the individual electrode 31 to the lower side of the pressure chamber 19, a part of the individual electrode 131 may partition the pressure chamber 19. The form arrange | positioned in the state overlaid above may be sufficient. In the first to fourth embodiments, the ink permeation protective film is configured by one layer including the upper protective part and the lower protective part. However, the upper protective part and the lower protective part are included. May be formed of two layers including two films having the same thickness, and a groove or a slope may be formed in the lower protective layer.

  In the first embodiment, each film of the ink permeation protective film 20 is formed by a vapor deposition method using a plasma CVD method as an example, but may be formed by a known vapor deposition method, coating, baking, or the like.

  In the first to fourth embodiments, the ink permeation protective film has been described with a configuration in which a groove is provided in the outer region, or a configuration in which a slope is provided in the lower region, but the ink ejection efficiency in the pressure chamber 19 is improved. The structure to improve is not restricted to this. For example, as shown in FIG. 7B, when vertically projecting from the upper side of the individual electrode 31 downward, a slope 523 is provided in a lower region 525A corresponding to the region where the individual electrode 31 is provided, Furthermore, a groove 524 having a thin portion 550 whose thickness in the vertical direction is thinner than that of the lower region 525A may be provided in an outer region 525B on the partition wall side that partitions the pressure chamber 19 from the lower region 525A. Even when the slope 523 and the groove 524 are disposed in combination, the ink ejection efficiency can be improved.

  In particular, the configuration in which the ink permeation protective film is formed in a slope shape converts the vertical force transmitted from the individual electrode 31 into a vertical force, and the force generated in the individual electrode 31 is used to discharge ink. Can be reflected efficiently. Moreover, although the groove | channel formed in this Embodiment 1 or 3 is the structure each formed in an outer area | region, you may be provided in the position which deviates from the center of the said individual electrode 31 in a lower area | region. Further, as in the present embodiment, a configuration in which a plurality of grooves formed on both the left and right sides around the lower region is not essential. When the groove is provided on the discharge port 17 side in the pressure chamber 19, the contribution ratio to the discharge efficiency is better than when the groove is provided only on the supply port 27 side.

DESCRIPTION OF SYMBOLS 1 Piezoelectric inkjet head 10 Cavity unit 17 Nozzle port 19 Pressure chamber 20, 120, 220, 320, 520 Ink permeation protection film 21, 121, 221, 321 Upper protection part 22, 122, 222, 322 Lower protection part 23 Groove 30 Actuator 31 Individual electrode 50, 150, 350, 550 Thin part 123 Inclined part 150 Thin part 223 Groove part 323 Flow path promoting part

Claims (5)

A pressure chamber connectable to a liquid source;
A drive unit provided facing the pressure chamber and pressurizing the pressure chamber;
A first region corresponding to the opposing drive unit and the pressure chamber; and a second region corresponding to the pressure chamber and surrounding the first region, wherein the liquid in the pressure chamber is A protective film that prevents penetration into the drive unit;
With
The droplet ejecting head according to claim 1, wherein a thin-walled portion is formed in the protective film in the second region, the thickness of which is smaller than the thickness of the film in the first region. In the second region of the protective film, the thin portion is formed in a region corresponding to a space between the surface on the drive unit side and the surface on the pressure chamber side in the first region of the protective film,
The liquid droplet ejecting head according to claim 1, wherein the thin portion has a film thickness that prevents liquid from penetrating into the driving portion. The pressure chamber includes a discharge port for discharging the liquid supplied from the liquid supply source,
3. The liquid droplet ejecting head according to claim 1, wherein a groove having the thin portion is formed in the protective film in the second region on the discharge port side from the first region.   The droplet ejecting head according to claim 3, wherein the groove of the protective film is inclined with respect to a pressing direction of the driving unit. The pressure chamber includes a supply port through which liquid is supplied from the liquid supply source, and a discharge port through which liquid is discharged.
The flow path promoting portion is formed on the protective film so that the film thickness in the first region gradually decreases from the supply port toward the discharge port. The droplet jet head according to any one of the above.