JP6025622B2 - Ink jet head, ink jet recording apparatus, and method of manufacturing ink jet head - Google Patents

Description

  Embodiments described herein relate generally to an inkjet head, an inkjet recording apparatus, and an inkjet head manufacturing method.

  The so-called on-demand ink jet recording method is a method in which ink droplets are ejected from nozzles in accordance with image signals to form an image with ink droplets on recording paper. The on-demand ink jet recording system includes a heating element type and a piezoelectric element type.

  In the heating element type, a heating element in the ink flow path generates bubbles in the ink. Ink droplets pushed by the bubbles are ejected from the nozzles. On the other hand, in the piezoelectric element type, the piezoelectric element (piezo element) is deformed to cause a pressure change in the ink stored in the ink chamber. Thereby, the pressurized ink droplet is ejected from the nozzle.

  An inkjet head as an example of a piezoelectric element type has a drive element (piezoelectric element, actuator) that pressurizes ink. The drive element includes, for example, a piezoelectric film and metal electrode films formed on both surfaces of the piezoelectric film.

  The ink jet head has a pressure chamber for containing ink. There is a diaphragm to which the drive element is attached at one end of the pressure chamber. There is a nozzle plate with nozzles at the other end of the pressure chamber.

  When a drive waveform (voltage) is applied to the two electrode films, an electric field in the same direction as the polarization direction is applied to the piezoelectric film through the electrode films. Thereby, the drive element expands and contracts in a direction orthogonal to the electric field direction. The diaphragm is deformed using this expansion and contraction. When the diaphragm is deformed, a pressure change occurs in the ink in the pressure chamber, and an ink droplet is ejected from the nozzle.

Japanese Patent No. 4844717

  For example, by covering the drive element with a film, the drive element is protected from corrosion, deterioration, and performance degradation due to ink or moisture in the air. However, when such a film contacts the drive element, deformation of the drive element is hindered.

  The problem to be solved by the present invention is to provide an ink jet head, an ink jet recording apparatus, and a method for manufacturing the ink jet head that can suppress a decrease in driving efficiency.

An ink jet head according to one embodiment includes a base material, a diaphragm, a nozzle, a drive element, an insulating film, and an insulating protective film. The substrate has a pressure chamber for containing ink. The diaphragm has a first surface that closes the pressure chamber, and a second surface that is on the opposite side of the first surface. The nozzle passes through the first surface and the second surface of the diaphragm. The drive element is on the second surface of the diaphragm, and changes the volume of the pressure chamber by deforming the diaphragm when a voltage is applied. The insulating film covers the second surface of the diaphragm and the driving element. The protective film is provided on the insulating film and has a concave portion that is a space portion in a portion corresponding to a part of the insulating film on the driving element.

1 is a cross-sectional view illustrating an ink jet printer according to a first embodiment. 1 is a perspective view illustrating an image forming apparatus according to a first embodiment. FIG. 2 is a plan view showing the ink jet head of the first embodiment. FIG. 3 is a cross-sectional view illustrating a part of the ink jet head according to the first embodiment. 1 is a cross-sectional view illustrating an ink jet head on which an insulating film according to a first embodiment is formed. FIG. 3 is a cross-sectional view illustrating an inkjet head in which a wiring portion of a common electrode according to the first embodiment is formed. FIG. 3 is a cross-sectional view illustrating the inkjet head on which the protective film according to the first embodiment is formed. FIG. 3 is a cross-sectional view illustrating the inkjet head in which the nozzle and the opening according to the first embodiment are formed. Sectional drawing which shows a part of inkjet head which concerns on 2nd Embodiment. Sectional drawing which shows a part of inkjet head which concerns on 3rd Embodiment. Sectional drawing which shows the modification of the inkjet head of 3rd Embodiment.

  The first embodiment will be described below with reference to FIGS. 1 to 8. Note that one or more examples of other expressions may be attached to each element capable of a plurality of expressions. However, this does not deny that a different expression is given for an element to which no other expression is attached, and does not restrict other expressions not illustrated. Each drawing schematically shows an embodiment, and the size of each element shown in the drawing may differ from the explanation of the embodiment.

  FIG. 1 is a cross-sectional view showing an ink jet printer 1 according to the first embodiment. The ink jet printer 1 is an example of an ink jet recording apparatus. The ink jet recording apparatus is not limited to this, and may be another apparatus such as a copying machine.

  As shown in FIG. 1, the inkjet printer 1 performs various processes such as image formation while conveying a recording paper P that is a recording medium, for example. The ink jet printer 1 includes a housing 10, a paper feed cassette 11, a paper discharge tray 12, a holding roller (drum) 13, a conveying device 14, a holding device 15, an image forming device 16, and a static elimination device 17. And a reversing device 18 and a cleaning device 19.

  The paper feed cassette 11 accommodates a plurality of recording papers P and is disposed in the housing 10. The paper discharge tray 12 is at the top of the housing 10. The recording paper P on which an image is formed by the ink jet printer 1 is discharged to the paper discharge tray 12.

  The transport device 14 has a plurality of guides and a plurality of transport rollers arranged along a path along which the recording paper P is transported. The transport roller is driven by a motor and rotates to transport the recording paper P from the paper feed cassette 11 to the paper discharge tray 12.

  The holding roller 13 has a cylindrical frame formed of a conductor and a thin insulating layer formed on the surface of the frame. The frame is grounded (ground connection). The holding roller 13 conveys the recording paper P by rotating while holding the recording paper P on the surface thereof.

  The holding device 15 holds the recording paper P carried out of the paper feed cassette 11 by the transport device 14 by adsorbing it on the surface (outer peripheral surface) of the holding roller 13. The holding device 15 presses the recording paper P against the holding roller 13 and then attracts the recording paper P to the holding roller 13 by electrostatic force due to charging.

  The image forming apparatus 16 forms an image on the recording paper P held on the outer surface of the holding roller 13 by the holding device 15. The image forming apparatus 16 includes a plurality of inkjet heads 21 that face the surface of the holding roller 13. The plurality of inkjet heads 21 form images by ejecting, for example, four colors of ink of cyan, magenta, yellow, and black onto the recording paper P, respectively.

  The neutralization peeling device 17 peels the recording paper P on which the image is formed from the holding roller 13 by neutralizing the recording paper P. The neutralization peeling device 17 supplies electric charges to neutralize the recording paper P, and inserts a claw between the recording paper P and the holding roller 13. As a result, the recording paper P is peeled off from the holding roller 13. The recording paper P peeled off from the holding roller 13 is transported by the transport device 14 to the paper discharge tray 12 or the reversing device 18.

  The cleaning device 19 cleans the holding roller 13. The cleaning device 19 is downstream of the static elimination device 17 in the rotation direction of the holding roller 13. The cleaning device 19 brings the cleaning member 19 a into contact with the surface of the rotating holding roller 13 and cleans the surface of the rotating holding roller 13.

  The reversing device 18 reverses the front and back surfaces of the recording paper P peeled from the holding roller 13 and supplies the recording paper P onto the front surface of the holding roller 13 again. The reversing device 18 reverses the recording paper P by, for example, conveying the recording paper P along a predetermined reversing path for switching back the recording paper P in the front-rear direction.

  FIG. 2 is an exploded perspective view showing one inkjet head 21 included in the image forming apparatus 16. FIG. 3 is a plan view showing the inkjet head 21. 4 is a cross-sectional view showing a part of the inkjet head 21 along the line F4-F4 of FIG. 2 and 3 show various elements which are originally hidden for the sake of explanation by solid lines.

  As shown in FIG. 2, the ink jet printer 1 includes a plurality of ink tanks 23 connected to a plurality of ink jet heads 21 and a plurality of control units 24. The inkjet head 21 is connected to an ink tank 23 that stores ink of a corresponding color.

  The inkjet head 21 forms characters and images by ejecting ink droplets onto the recording paper P held by the holding roller 13. The inkjet head 21 includes a nozzle plate 100, a pressure chamber structure 200, a separate plate 300, and an ink flow path structure 400. The pressure chamber structure 200 is an example of a base material.

  The nozzle plate 100 is formed in a rectangular plate shape. The nozzle plate 100 is formed as an integral structure on the pressure chamber structure 200. The nozzle plate 100 includes a plurality of nozzles (orifices and ink ejection holes) 101 and a plurality of driving elements (piezoelectric elements and actuators) 102.

  The plurality of nozzles 101 are circular holes. The diameter of the nozzle 101 is 20 μm, for example. The nozzles 101 are arranged in two rows along the longitudinal direction of the nozzle plate 100. The nozzles 101 in one row and the nozzles 101 in the other row are alternately arranged in the longitudinal direction of the nozzle plate 100. That is, the plurality of nozzles 101 are arranged in a staggered manner (alternately). Thereby, the plurality of drive elements 102 are arranged with higher density.

  In the longitudinal direction of the nozzle plate 100, the distance between the centers of adjacent nozzles 101 is, for example, 340 μm. In the short direction of the nozzle plate 100, the distance between the two rows of the nozzles 101 is, for example, 240 μm.

  The plurality of drive elements 102 are arranged corresponding to the plurality of nozzles 101. In other words, the drive element 102 is located on the same axis as the corresponding nozzle 101. The drive element 102 is formed in an annular shape and surrounds the corresponding nozzle 101. The drive element 102 is not limited to this, and may be, for example, an annular shape (C-shape) with a part opened.

  The pressure chamber structure 200 is formed in a rectangular plate shape using a silicon wafer. The pressure chamber structure 200 is not limited to this, and may be another semiconductor such as silicon carbide (SiC) or a germanium substrate. The substrate is not limited to this, and may be formed of other materials such as ceramics, glass, quartz, resin, or metal. The ceramics used are, for example, alumina ceramics, zirconia, silicon carbide, silicon nitride or nitrides, carbides or oxides such as barium titanate. The resin used is, for example, a plastic material such as ABS (acrylonitrile butadiene styrene), polyacetal, polyamide, polycarbonate, or polyethersulfone. The metal used is, for example, aluminum or titanium. The thickness of the pressure chamber structure 200 is, for example, 725 μm. The thickness of the pressure chamber structure 200 is, for example, in the range of 100 to 775 μm.

  As shown in FIG. 4, the pressure chamber structure 200 includes a first surface 200 a, a second surface 200 b, and a plurality of pressure chambers (ink chambers) 201. The first and second surfaces 200a and 200b are flattened. The second surface 200b is located on the opposite side of the first surface 200a. The nozzle plate 100 is fixed to the first surface 200a.

  The plurality of pressure chambers 201 are circular holes. The diameter of the pressure chamber 201 is, for example, 190 μm. The shape of the pressure chamber 201 is not limited to this. The pressure chamber 201 penetrates the pressure chamber structure 200 in the thickness direction and opens in the first and second surfaces 200a and 200b, respectively. The plurality of pressure chambers 201 that open to the first surface 200 a are closed by the nozzle plate 100.

  The plurality of pressure chambers 201 are arranged corresponding to the plurality of nozzles 101. In other words, the pressure chamber 201 is located on the same axis as the corresponding nozzle 101. For this reason, the corresponding nozzle 101 communicates with the pressure chamber 201. The pressure chamber 201 is connected to the outside of the inkjet head 21 via the nozzle 101.

  The separate plate 300 is formed in a rectangular plate shape with, for example, stainless steel. The thickness of the separate plate 300 is, for example, 200 μm. The separate plate 300 is bonded to the second surface 200b of the pressure chamber structure 200 with, for example, an epoxy adhesive. For this reason, the pressure chamber 201 opened to the second surface 200 b is closed by the separate plate 300.

  The separate plate 300 has a plurality of ink stops 301. The ink diaphragm 301 is a circular hole. The diameter of the ink diaphragm 301 is, for example, 50 μm. The diameter of the ink restrictor 301 is ¼ or less of the diameter of the pressure chamber 201.

  The ink restrictor 301 is disposed corresponding to the plurality of pressure chambers 201. In other words, the ink restrictor 301 is located on the same axis as the corresponding pressure chamber 201. For this reason, the corresponding ink diaphragm 301 opens in the pressure chamber 201.

  The ink flow path structure 400 is formed in a rectangular plate shape using, for example, stainless steel. The thickness of the ink flow path structure 400 is, for example, 4 mm. The material of the ink flow path structure 400 and the separate plate 300 is not limited to stainless steel. For example, you may form with other materials like ceramics or resin. The ceramics used are, for example, alumina ceramics, zirconia, silicon carbide, nitrides such as silicon nitride, carbides or oxides. The resin used is, for example, a plastic material such as ABS, polyacetal, polyamide, polycarbonate, or polyethersulfone. The materials of the separate plate 300 and the ink flow path structure 400 are selected in consideration of the difference in expansion coefficient from the nozzle plate 100 so as not to affect the generation of pressure for ejecting ink.

  The ink flow path structure 400 is bonded to the separate plate 300 by, for example, an epoxy adhesive. The separate plate 300 is sandwiched between the pressure chamber structure 200 and the ink flow path structure 400. As shown in FIG. 2, the ink flow path structure 400 includes an ink flow path 401, an ink supply port 402, and an ink discharge port 403.

  The ink flow path 401 is a groove formed on the surface of the ink flow path structure 400 that is bonded to the separate plate 300. The depth of the ink flow path 401 is 2 mm, for example. The ink flow path 401 surrounds the plurality of ink restrictors 301. In other words, the plurality of ink restrictors 301 are open to the ink flow path 401.

  The ink supply port 402 opens at one end of the ink flow path 401. The ink supply port 402 is connected to the ink tank 23 through, for example, a tube. The ink tank 23 is connected to the plurality of pressure chambers 201 via the ink flow path 401.

  The ink in the ink tank 23 flows into the ink flow path 401 through the ink supply port 402. The ink supplied to the ink flow path 401 is supplied to the plurality of pressure chambers 201 through the plurality of ink restrictors 301. The ink restrictor 301 makes the flow path resistance of the ink flowing into the plurality of pressure chambers 201 approximately the same. The ink filled in the pressure chamber 201 also flows into the nozzle 101 that opens in the pressure chamber 201. The ink jet printer 1 keeps the ink in the nozzle 101 by keeping the ink pressure at an appropriate negative pressure. The ink causes a meniscus in the nozzle 101 and is maintained so as not to leak from the nozzle 101.

  The ink discharge port 403 opens at the other end of the ink flow path 401. The ink discharge port 403 is connected to the ink tank 23 through, for example, a tube. The ink in the ink flow path 401 that has not flowed into the pressure chamber 201 is discharged to the ink tank 23 through the ink discharge port 403. In this way, ink circulates between the ink tank 23 and the ink flow path 401. As the ink circulates, the temperature of the inkjet head 21 and the ink is kept constant, and, for example, the quality of the ink due to heat is suppressed.

  Next, the nozzle plate 100 will be described in detail. As shown in FIG. 4, the nozzle plate 100 includes the nozzle 101 and the driving element 102, the diaphragm 104, the insulating film 105, the plurality of wiring electrodes 106, the shared electrode 107, the protective film 108, and the repellent film. And an ink film 109. The insulating film 105 and the protective film 108 are an example of an insulating part.

The diaphragm 104 is formed in a rectangular plate shape by, for example, SiO ₂ (silicon dioxide) formed on the first surface 200a of the pressure chamber structure 200. In other words, the diaphragm 104 is an oxide film of the pressure chamber structure 200 that is a silicon wafer. The diaphragm 104 is formed of other materials such as single crystal Si (silicon), Al ₂ O ₃ (aluminum oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zirconium oxide), or DLC (Diamond Like Carbon). May be. The thickness of the diaphragm 104 is, for example, 4 μm. The thickness of the diaphragm 104 is generally in the range of 1 to 50 μm.

  The diaphragm 104 has a first surface 104a and a second surface 104b. The first surface 104 a is fixed to the pressure chamber structure 200 and closes the plurality of pressure chambers 201. The second surface 104b is located on the opposite side of the first surface 104a.

  The plurality of wiring electrodes 106 are formed on the second surface 104 b of the diaphragm 104. As shown in FIGS. 3 and 4, each of the plurality of wiring electrodes 106 includes a terminal portion 106a, a wiring portion 106b, and an electrode portion 106c. The terminal portions 106 a of the plurality of wiring electrodes 106 are located at one end in the short direction of the diaphragm 104 and are arranged along the longitudinal direction of the diaphragm 104. The distance between each terminal part 106a is 170 micrometers.

  The shared electrode 107 includes two terminal portions 107a, a plurality of wiring portions 107b, and a plurality of electrode portions 107c. The wiring portion 107b is an example of a lead wiring. The two terminal portions 107 a are located at one end of the diaphragm 104 in the short direction and are disposed at both ends of the diaphragm 104 in the longitudinal direction. The terminal portions 106 a of the plurality of wiring electrodes 106 are arranged between the two terminal portions 107 a of the shared electrode 107.

  The plurality of wiring electrodes 106 are, for example, thin films of Pt (platinum) and Al (aluminum). The terminal portion 107a and the wiring portion 107b of the shared electrode 107 are, for example, Ti (titanium) and Al thin films. The electrode part 107c of the shared electrode 107 is a thin film of Pt. Note that the plurality of wiring electrodes 106 and the common electrode 107 include Ni (nickel), Cu (copper), Al (aluminum), Ag (silver), Ti (titanium), W (tungsten), Mo (molybdenum), Au ( It may be formed of other materials such as gold.

  The thickness of the plurality of wiring electrodes 106 and the shared electrode 107 is, for example, 0.5 μm. The film thicknesses of the plurality of wiring electrodes 106 and the common electrode 107 are generally in the range of 0.01 to 1 μm. The width of the wiring portions 106b and 107b of the plurality of wiring electrodes 106 and the shared electrode 107 is, for example, 80 μm.

  As shown in FIG. 4, the drive element 102 is on the second surface 104 b of the diaphragm 104. The drive element 102 generates a pressure for ejecting ink droplets from the corresponding nozzle 101 in the ink in the corresponding pressure chamber 201.

  The plurality of drive elements 102 each include an electrode portion 106 c of the wiring electrode 106, an electrode portion 107 c of the shared electrode 107, and a piezoelectric film 111. The electrode portion 106c of the wiring electrode 106 is an example of a first electrode and is also referred to as a lower electrode. The electrode portion 107c of the shared electrode 107 is an example of a second electrode and is also referred to as an upper electrode. The piezoelectric film 111 is an example of a piezoelectric body.

  The electrode portion 106 c of the wiring electrode 106 is on the second surface 104 b of the diaphragm 104. The electrode part 106 c is formed in an annular shape surrounding the nozzle 101. The electrode part 106 c is located on the same axis as the nozzle 101. The outer diameter of the electrode portion 106c is, for example, 133 μm. The inner diameter of the electrode part 106c is, for example, 30 μm. For this reason, the electrode part 106 c is separated from the nozzle 101.

  The wiring part 106 b of the wiring electrode 106 is formed on the second surface 104 b of the diaphragm 104. As shown in FIG. 3, the wiring part 106 b connects the electrode part 106 c and the terminal part 106 a of the corresponding driving element 102. The plurality of wiring portions 106 b extend in parallel along the short direction of the nozzle plate 100. Some wiring parts 106b pass between the drive elements 102 arranged side by side.

  As shown in FIG. 4, the piezoelectric film 111 surrounds the nozzle 101 and is formed in an annular shape having approximately the same size as the electrode portion 106 c of the wiring electrode 106. The piezoelectric film 111 is formed slightly smaller than the electrode portion 106c of the wiring electrode 106, but may be larger than the electrode portion 106c. The piezoelectric film 111 is located on the same axis as the nozzle 101. The piezoelectric film 111 covers the electrode portion 106 c of the wiring electrode 106.

The piezoelectric film 111 is a film of lead zirconate titanate (PZT) which is a piezoelectric material. The piezoelectric film 111 is not limited to this, and for example, PTO (PbTiO ₃ : lead titanate), PMNT (Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ ), PZNT (Pb (Zn ₁ )) _{/ 3 Nb 2/3) O 3 -PbTiO} 3), ZnO, and it may be formed by a variety of piezoelectric material such as AlN.

  The thickness of the piezoelectric film 111 is, for example, 2 μm. The thickness of the piezoelectric film is determined by, for example, piezoelectric characteristics and dielectric breakdown voltage. The thickness of the piezoelectric film is generally in the range of 0.1 μm to 5 μm.

  The piezoelectric film 111 generates polarization in the thickness direction. When an electric field in the same direction as the polarization direction is applied to the piezoelectric film 111, the piezoelectric film 111 expands and contracts in a direction orthogonal to the direction of the electric field. In other words, the piezoelectric film 111 contracts or expands in a direction (in-plane direction) orthogonal to the film thickness.

  When a ferroelectric material such as PZT is used as the piezoelectric film 111, polarization inversion occurs by applying an electric field opposite to the polarization direction. Therefore, it is possible to apply an electric field substantially only in the same direction as the polarization direction. By applying the electric field, the piezoelectric film 111 extends in the film thickness direction and is orthogonal to the film thickness (in-plane Direction).

  The electrode portion 107 c of the shared electrode 107 surrounds the nozzle 101 and is formed in an annular shape having approximately the same size as the electrode portion 106 c of the wiring electrode 106 and the piezoelectric film 111. The electrode portion 107 c of the shared electrode 107 is formed slightly smaller than the piezoelectric film 111, but may be larger than the piezoelectric film 111. The electrode part 107 c is located on the same axis as the nozzle 101. The electrode part 107 c covers the piezoelectric film 111. In other words, the electrode part 107 c is provided on the ejection side (side facing the ink jet head 21) of the piezoelectric film 111.

  The piezoelectric film 111 is interposed between the electrode portion 106 c of the wiring electrode 106 and the electrode portion 107 c of the shared electrode 107. In other words, the electrode portions 106 c and 107 c of the wiring electrode 106 and the shared electrode 107 overlap the piezoelectric film 111. The piezoelectric film 111 insulates between the two electrode portions 106c and 107c. The electrode portion 107 c of the shared electrode 107 faces the electrode portion 106 c of the wiring electrode 106 with the piezoelectric film 111 interposed therebetween.

  The electrode part 107 c of the shared electrode 107 forms the outer surface 102 a of the drive element 102. The outer surface 102 a is one surface of the driving element 102 facing the opposite side of the diaphragm 104. In other words, the outer surface 102 a faces the ejection side of the drive element 102. The outer surface 102 a is a surface that is substantially parallel to the second surface 104 b of the diaphragm 104.

  The insulating film 105 covers the second surface 104 b of the vibration plate 104, the surface of the driving element 102, and the wiring part 106 b of the wiring electrode 106. The insulating film 105 has a plurality of holes that expose the terminal portions 106 a of the plurality of wiring electrodes 106.

Insulating film 105 is formed by, for example, SiO _2. The insulating film 105 may be formed of other materials such as SiN (silicon nitride), for example. The insulating film 105 has a substantially uniform thickness on the second surface 104 b of the vibration plate 104, the surface of the drive element 102, and the wiring portion 106 b of the wiring electrode 106. The thickness of the insulating film 105 is 1 μm. The thickness of the insulating film 105 is approximately in the range of 0.1 μm to 5 μm. Note that the thickness of the insulating film 105 may be partially different.

  The insulating film 105 has a plurality of contact portions 113. The contact portion 113 is a hole provided in a part of the insulating film 105 on the outer surface 102 a of the corresponding driving element 102. The contact portion 113 is formed in a circular shape with a diameter of 20 μm, for example. The contact part 113 exposes a part of the electrode part 107 c of the shared electrode 107. The contact portion 113 is disposed closer to the outer periphery of the electrode portion 107c than the center between the inner periphery and the outer periphery of the annular electrode portion 107c.

  The two terminal portions 107 a and the plurality of wiring portions 107 b of the shared electrode 107 are on the surface 105 a of the insulating film 105. In other words, the terminal portion 107 a and the wiring portion 107 b of the shared electrode 107 are on the insulating film 105. The surface 105 a of the insulating film 105 faces in the opposite direction of the diaphragm 104.

  As shown in FIG. 3, the plurality of wiring portions 107b of the shared electrode 107 extend from the electrode portion 107c of the corresponding driving element 102 and the two terminal portions 107a, respectively. The plurality of wiring portions 107 b extend in parallel along the short direction of the nozzle plate 100.

  The plurality of wiring portions 107 b are combined at the other end portion in the short side direction of the nozzle plate 100 to form a portion extending along the longitudinal direction of the nozzle plate 100. For this reason, the two terminal portions 107a and the plurality of electrode portions 107c are connected by the plurality of wiring portions 107b.

  As shown in FIG. 4, the wiring portion 107 b of the shared electrode 107 passes through the surface 105 a of the insulating film 105 that covers the driving element 102. One end of the wiring portion 107 b is connected to the electrode portion 107 c of the shared electrode 107 through the contact portion 113. In other words, the contact portion 113 is a portion where the insulating film 105 is partially removed in order to connect the wiring portion 107b to the electrode portion 107c.

  The insulating film 105 separates the wiring portion 107 b of the shared electrode 107 and the electrode portion 106 c of the wiring electrode 106. The insulating film 105 prevents the wiring electrode 106 and the shared electrode 107 from being electrically connected.

  The protective film 108 is on the second surface 104 b of the diaphragm 104. The protective film 108 is formed of, for example, a photosensitive polyimide such as Photo Nice (registered trademark) manufactured by Toray Industries, Inc. That is, the protective film 108 is different from the insulating film 105 and is formed of an insulating material. The protective film 108 is not limited to this, and may be formed of other insulating materials such as resin or ceramics. Resins used are plastic materials such as other types of polyimide, ABS, polyacetal, polyamide, polycarbonate, and polyethersulfone. The ceramics used are, for example, nitrides such as zirconia, silicon carbide, silicon nitride, barium titanate, or oxides. Further, the protective film 108 may be formed of a metal material as long as it has an insulating property with respect to the driving element 102 and the shared electrode 107. The metal material is, for example, aluminum, SUS, or titanium.

  The material of the protective film 108 is selected in consideration of heat resistance, insulation, thermal expansion coefficient, smoothness, and ink wettability. When the ink jet printer 1 uses ink having high conductivity, the insulating property of the material can affect the degree of ink deterioration when the drive element 102 is driven.

  The protective film 108 covers the second surface 104 b of the diaphragm 104, the surface 105 a of the insulating film 105, and the wiring portion 107 b of the shared electrode 107. In other words, the protective film 108 covers the driving element 102 and the wiring part 106 b of the wiring electrode 106 from above the insulating film 105. The protective film 108 protects the driving element 102, the wiring electrode 106, and the shared electrode 107 from, for example, ink or moisture in the air. The protective film 108 has a plurality of holes exposing the plurality of terminal portions 106 a and 107 a of the wiring electrode 106 and the common electrode 107.

The material of the protective film 108 differs from the material of the diaphragm 104 in Young's modulus. The Young's modulus of SiO ₂ forming the diaphragm 104 is 80.6 GPa. On the other hand, the Young's modulus of the polyimide forming the protective film 108 is 4 GPa. That is, the Young's modulus of the protective film 108 is smaller than the Young's modulus of the diaphragm 104.

  The surface 108a of the protective film 108 is formed to be roughly smooth, but has minute irregularities. For example, in the portion where the driving element 102 is provided, the surface 108a of the protective film 108 is raised as compared with other portions. The surface 108 a of the protective film 108 is located on the opposite side of the surface fixed to the diaphragm 104.

  The thickness of the protective film 108 other than the portion where the driving element 102, the wiring electrode 106, and the shared electrode 107 are present is about 4 μm. The thickness of the protective film 108 is approximately in the range of 1 to 50 μm. The thickness of the protective film 108 is the distance from the second surface 104 b of the diaphragm 104 to the surface 108 a of the protective film 108. The thickness of the protective film 108 formed on the driving element 102 is about 2.5 μm. The thickness of the protective film 108 is a distance from the surface 105 a of the insulating film 105 on the driving element 102 to the surface 108 a of the protective film 108.

  The protective film 108 has a plurality of openings (removal portions, recesses) 115. The opening 115 is provided on the corresponding driving element 102. The opening 115 is a hole formed in an annular shape smaller than the driving element 102. In other words, the inner peripheral diameter of the opening 115 is larger than the inner peripheral diameter of the drive element 102. The diameter of the outer periphery of the opening 115 is smaller than the diameter of the outer periphery of the drive element 102. The opening 115 is not limited to this, and may be, for example, a plurality of holes arranged rotationally symmetrically with the nozzle 101 as an axis.

  The opening 115 surrounds the corresponding nozzle 101. The opening 115 is arranged on the same axis as the corresponding nozzle 101. In other words, the opening 115 is formed in a rotationally symmetric shape with the central axis of the nozzle 101 as an axis.

  The opening 115 exposes a part of the insulating film 105 on the driving element 102. In other words, the insulating film 105 on the outer surface 102 a of the driving element 102 is partially exposed by the opening 115.

  The protective film 108 covers the end portion near the inner periphery and the end portion near the outer periphery of the outer surface 102 a of the drive element 102 from above the insulating film 105. The protective film 108 also covers the contact portion 113. Further, the protective film 108 also covers the wiring portion 107 b of the shared electrode 107 that passes through the insulating film 105 on the outer surface 102 a of the driving element 102.

  Since the opening 115 is provided, a portion of the driving element 102 where the insulating film 105 covers the driving element 102 and the protective film 108 does not exist is generated. In other words, a thin portion (thin portion) is formed on the driving element 102 in an insulating portion (insulating portion) formed by the insulating film 105 and the protective film 108. In other words, the driving element 102 includes a portion covered with the insulating film 105 and the protective film 108 and a portion covered with the insulating film 105. In addition, the said insulation part should just have insulation with the member to contact | connect, and is not restricted to what was formed with the insulating material.

  The ink repellent film 109 covers the protective film 108 and a part of the insulating film 105 exposed by the opening 115. The ink repellent film 109 also covers the inner peripheral surface of the opening 115. The ink repellent film 109 is formed of a silicone-based liquid repellent material or a fluorine-containing organic material having liquid repellency, such as Cytop (registered trademark) of Asahi Glass Co., Ltd. The ink repellent film 109 may be formed of other materials.

  The ink repellent film 109 is exposed without covering the protective film 108 around the terminal portion 106 a of the wiring electrode 106 and the terminal portion 107 a of the shared electrode 107. The surface 109 a of the ink repellent film 109 forms the surface of the nozzle plate 100. The surface 109 a of the ink repellent film 109 is located on the opposite side of the surface fixed to the protective film 108.

  The thickness of the ink repellent film 109 other than the portion where the drive element 102, the shared electrode 107, and the wiring electrode 106 are present is, for example, 1 μm. The thickness of the ink repellent film 109 is, for example, in the range of 0.01 to 10 μm. The thickness of the ink repellent film 109 in the portion where the driving element 102 is provided is thinner than the other portions. The thickness of the ink repellent film 109 may be constant.

  If the ink droplets ejected by the nozzle 101 adhere to the vicinity of the nozzle 101, there is a possibility that the stability of ink ejection is lowered. The ink repellent film 109 suppresses ink droplets from adhering to the surface of the nozzle plate 100.

  The nozzle 101 passes through the vibration plate 104, the protective film 108, and the ink repellent film 109. In other words, the nozzle 101 is formed on the vibration plate 104, the protective film 108, and the ink repellent film 109. Since the vibration plate 104 and the protective film 108 have ink affinity (liquid affinity), the meniscus of the ink stored in the pressure chamber 201 is kept in the nozzle 101. A part of the protective film 108 is interposed between the nozzle 101 and the inner peripheral surface of the driving element 102.

  As illustrated in FIG. 2, the control unit 24 is connected to the terminal unit 106 a of the wiring electrode 106 via, for example, a flexible cable. The control unit 24 is, for example, an IC that controls the inkjet head 21 or a microcomputer that controls the inkjet printer 1. On the other hand, the terminal portion 107a of the shared electrode 107 is connected to, for example, GND (ground ground = 0V).

  The control unit 24 transmits a signal for driving the corresponding driving element 102 to the plurality of wiring electrodes 106. The wiring electrode 106 is used as an individual electrode for operating the plurality of driving elements 102 independently.

  The inkjet head 21 performs printing (image formation) as follows, for example. A print instruction signal is input to the control unit 24 by a user operation. The control unit 24 applies signals to the plurality of drive elements 102 based on the print instruction. In other words, the control unit 24 applies a driving voltage to the electrode part 106 c of the wiring electrode 106.

  When a signal is applied to the electrode portion 106 c of the wiring electrode 106, a potential difference is generated between the electrode portion 106 c of the wiring electrode 106 and the electrode portion 107 c of the common electrode 107. As a result, an electric field in the same direction as the polarization direction is applied to the piezoelectric film 111, and the drive element 102 expands and contracts in a direction orthogonal to the electric field direction.

  In such a nozzle plate 100, when the drive element 102 extends in a direction orthogonal to the electric field direction, the diaphragm 104 bends so as to reduce the volume of the pressure chamber 201. On the contrary, when the driving element 102 is contracted in a direction orthogonal to the electric field direction, the diaphragm 104 is curved so as to increase the volume of the pressure chamber 201. At this time, the insulating film 105 and the protective film 108 inhibit the bending.

  More specifically, as shown in FIG. 4, the drive element 102 is sandwiched between the diaphragm 104, the insulating film 105, and the protective film 108. For this reason, when the driving element 102 extends in a direction orthogonal to the electric field direction, a force is applied to the diaphragm 104 to deform into a concave shape with respect to the pressure chamber 201 side. In other words, the diaphragm 104 tends to bend in a direction that increases the volume of the pressure chamber 201. On the other hand, the insulating film 105 and the protective film 108 are subjected to a force that deforms into a convex shape with respect to the pressure chamber 201 side. In other words, the insulating film 105 and the protective film 108 tend to bend in a direction that reduces the volume of the pressure chamber 201.

  On the other hand, when the driving element 102 is contracted in a direction orthogonal to the electric field direction, a force is applied to the diaphragm 104 so as to deform into a convex shape with respect to the pressure chamber 201 side. In other words, the diaphragm 104 tends to bend in a direction that reduces the volume of the pressure chamber 201. In addition, the insulating film 105 and the protective film 108 are subjected to a force that deforms into a concave shape with respect to the pressure chamber 201 side. In other words, the insulating film 105 and the protective film 108 tend to bend in a direction that increases the volume of the pressure chamber 201.

  As described above, the diaphragm 104, the insulating film 105, and the protective film 108 tend to bend in opposite directions. That is, the insulating portion formed by the insulating film 105 and the protective film 108 generates a force (film stress) that hinders the deformation of the diaphragm 104 by the driving element 102.

The amount of deformation of the member is affected by the Young's modulus and the thickness of the member. The polyimide forming the protective film 108 has a Young's modulus smaller than that of SiO ₂ forming the diaphragm 104. For this reason, the protective film 108 has a larger deformation amount for the same force than the diaphragm 104. Furthermore, the insulating film 105 is thinner than the diaphragm 104. For this reason, the amount of deformation of the insulating film 105 with respect to the same force is larger than that of the diaphragm 104.

  Furthermore, by providing the opening 115, a thin portion where the protective film 108 does not exist is formed on the driving element 102. For this reason, the film stress generated by the insulating film 105 and the protective film 108 is reduced.

  When the driving element 102 extends in a direction perpendicular to the electric field direction by reducing the film stress generated by the insulating film 105 and the protective film 108, the vibration plate 104 can be bent so as to reduce the volume of the pressure chamber 201. . On the contrary, when the driving element 102 is contracted in a direction orthogonal to the electric field direction, the diaphragm 104 can be bent so as to expand the volume of the pressure chamber 201.

  As described above, the drive element 102 operates in the bending mode (bending vibration). The drive element 102 changes the volume of the pressure chamber 201 by deforming the diaphragm 104 when a voltage is applied.

  First, the drive element 102 increases the volume of the pressure chamber 201 by deforming the diaphragm 104. As a result, a negative pressure is generated in the ink stored in the pressure chamber 201, and the ink flows from the ink flow path 401 into the pressure chamber 201.

  Next, the drive element 102 reduces the volume of the pressure chamber 201 by deforming the diaphragm 104. Thereby, the ink in the pressure chamber 201 is pressurized. The positive pressure applied to the ink is confined in the pressure chamber 201 by the ink restrictor 301 without escape to the ink flow path 401. Thereby, the pressurized ink is ejected from the nozzle 101.

  The greater the difference in Young's modulus between the diaphragm 104 and the protective film 108, the lower the voltage at which ink can be ejected, and the ink jet head 21 can eject ink efficiently. Furthermore, the greater the difference in thickness between the insulating portion formed by the insulating film 105 and the protective film 108 and the diaphragm 104, the lower the voltage at which ink can be ejected, and the inkjet head 21 ejects ink efficiently. it can.

Next, an example of a method for manufacturing the inkjet head 21 will be described. First, an SiO ₂ film as the diaphragm 104 is formed over the entire first surface 200a of the pressure chamber structure 200 (silicon wafer) before the pressure chamber 201 is formed. The SiO ₂ film is formed by, for example, a thermal oxide film method. Note that the SiO ₂ film may be formed by other methods such as a CVD method.

  The silicon wafer forming the pressure chamber structure 200 is a single large disk. A plurality of pressure chamber structures 200 are later cut from the silicon wafer. However, the present invention is not limited to this, and one pressure chamber structure 200 may be formed from one rectangular silicon wafer.

  The silicon wafer is repeatedly heated and a thin film is formed in the manufacturing process of the inkjet head 21. For this reason, the silicon wafer has heat resistance, conforms to SEMI (Semiconductor Equipment and Materials International) standard, and is smoothed by mirror polishing.

  Next, a metal film for forming the wiring electrode 106 is formed on the second surface 104 b of the vibration plate 104. First, a Ti film and a Pt film are sequentially formed by sputtering. The film thickness of Pt is, for example, 0.45 μm, and the film thickness of Ti is, for example, 0.05 μm. The metal film may be formed by other manufacturing methods such as vapor deposition and plating.

  Next, the piezoelectric film 111 is formed on the metal film that forms the wiring electrode 106. The piezoelectric film 111 is formed by, for example, an RF magnetron sputtering method. At this time, the temperature of the silicon wafer is set to 350 ° C., for example. After the film formation, the piezoelectric film 111 is heat treated at 650 ° C. for 3 hours in order to impart piezoelectricity to the piezoelectric film 111. Thereby, the piezoelectric film 111 has good crystallinity and good piezoelectric performance. The piezoelectric film 111 may be formed by other manufacturing methods such as CVD (chemical vapor deposition), sol-gel method, AD method (aerosol deposition method), and hydrothermal synthesis method.

  Next, a Pt metal film for forming the electrode portion 107 c of the shared electrode 107 is formed on the piezoelectric film 111. The metal film is formed by, for example, a sputtering method. The metal film may be formed by other manufacturing methods such as vacuum deposition and plating.

  Next, the electrode part 107c of the shared electrode 107 and the piezoelectric film 111 are patterned by etching the metal film and the piezoelectric film 111. The patterning is performed by creating an etching mask on the metal film and removing the metal film and the piezoelectric film 111 other than the etching mask by etching. The metal film and the piezoelectric film 111 are patterned at a time. The metal film and the piezoelectric film 111 may be individually patterned. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  Next, the wiring electrode 106 is formed by patterning. In the patterning, an etching mask is formed on the piezoelectric film 111 and the electrode portion 107c of the shared electrode 107 and the metal film (Pt / Ti) under the piezoelectric film 111, and the metal film other than the etching mask is formed on the metal film. It is performed by removing by etching. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  The nozzle 101 is formed at the center between the electrode portions 106 c and 107 c of the wiring electrode 106 and the common electrode 107 and the piezoelectric film 111. Therefore, a portion of the electrodes 106 c and 107 c and the center of the piezoelectric film 111 that is concentric with the metal film and the piezoelectric film 111 is formed. Thus, the drive element 102 is formed on the second surface 104b of the diaphragm 104. By the patterning, the diaphragm 104 is exposed except for the terminal portion 106a, the wiring portion 106b, and the driving element 102 of the wiring electrode 106.

  FIG. 5 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the insulating film 105 is formed. As shown in FIG. 5, an insulating film 105 is formed on the second surface 104 b of the diaphragm 104, the wiring portion 106 b of the wiring electrode 106, and the driving element 102. The insulating film 105 is formed by a CVD method that can realize good insulating properties at low temperature. The insulating film 105 is not limited to this, and may be formed by other methods such as sputtering or evaporation.

  The insulating film 105 is patterned after film formation. In order to form the nozzle 101, a portion without the insulating film 105 concentric with the center of the driving element 102 is formed. At the same time, the contact portion 113 is formed. The diameter of the portion without the insulating film 105 is, for example, 25 μm. The patterning is performed by removing the insulating film 105 other than the etching mask by etching. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, fixing, and post-baking.

  FIG. 6 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the wiring portion 107b of the shared electrode 107 is formed. On the insulating film 105, a metal film for forming the terminal portion 107a and the wiring portion 107b of the shared electrode 107 is formed. The metal film is, for example, a Ti (titanium) / Al (aluminum) thin film formed by a sputtering method. The film thickness of Ti is, for example, 0.1 μm, and the film thickness of Al is, for example, 0.4 μm. The metal film may be formed by other manufacturing methods such as vacuum deposition and plating. The metal film is connected to the electrode portion 107 c of the shared electrode 107 through the contact portion 113.

  As shown in FIG. 6, the metal film is patterned to form the terminal portion 107a and the wiring portion 107b of the shared electrode 107. The patterning is performed by creating an etching mask on the metal film and removing the metal film other than the etching mask by etching. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

Next, the SiO ₂ film that forms the vibration plate 104 is patterned to form part of the nozzle 101. Patterning is made an etching mask on the SiO ₂ film performs SiO ₂ film other than the etching mask by removing by etching. The etching mask is formed by application of a photosensitive resist on the vibration plate 104, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  FIG. 7 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the protective film 108 is formed. A protective film 108 is formed on the diaphragm 104, the insulating film 105, and the terminal portion 107a and the wiring portion 107b of the common electrode 107 by a spin coating method (spin coating). That is, the protective film 108 that covers the insulating film 105 is formed. First, the second surface 104b of the diaphragm 104 and the insulating film 105 are covered with a solution containing a polyimide precursor. Next, the silicon wafer is rotated to smooth the solution surface. The protective film 108 is formed by performing thermal polymerization and solvent removal by baking.

  The method for forming the protective film 108 is not limited to spin coating. The protective film 108 may be formed by other methods such as CVD, vacuum deposition, or plating.

  FIG. 8 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the nozzle 101 and the opening 115 are formed. By patterning the protective film 108, the nozzle 101 and the opening 115 are formed, and the terminal portion 106a of the wiring electrode 106 and the terminal portion 107a of the common electrode 107 are exposed. The patterning is performed by a procedure corresponding to the material of the protective film 108.

  The case where the protective film 108 is formed of non-photosensitive polyimide such as Semico Fine (registered trademark) manufactured by Toray Industries, Inc. will be described. First, a solution containing a polyimide precursor is formed into a film by a spin coating method, subjected to thermal polymerization and solvent removal by baking, and then fired and molded. Thereafter, an etching mask is formed on the non-photosensitive polyimide film, and the polyimide film other than the etching mask is removed by etching to perform patterning. The etching mask is formed by application of a photosensitive resist on the non-photosensitive polyimide film, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

  The case where the protective film 108 is formed of, for example, photosensitive polyimide such as Photo Nice (registered trademark) manufactured by Toray Industries, Inc. will be described. First, the solution is deposited by spin coating and then pre-baked. Thereafter, patterning is performed through exposure using a mask and a development process. In the case of positive photosensitive polyimide, the mask has openings corresponding to the nozzle 101, the opening 115, the terminal portion 106a of the wiring electrode 106, and the terminal portion 107a of the common electrode 107 (light is transmitted). In the case of negative photosensitive polyimide, the mask shields light from portions corresponding to the nozzle 101, the opening 115, the terminal portion 106 a of the wiring electrode 106, and the terminal portion 107 a of the common electrode 107. Thereafter, post-baking is performed, and the protective film 108 is fired.

  Next, a cover tape is attached on the protective film 108. The cover tape is, for example, a back surface protective tape for chemical mechanical polishing (CMP) of a silicon wafer. The pressure chamber structure 200 to which the cover tape is attached is turned upside down to form a plurality of pressure chambers 201 in the pressure chamber structure 200. The pressure chamber 201 is formed by patterning.

  For example, an etching mask is formed on the pressure chamber structure 200 that is a silicon wafer, and vertical deep dry etching called Deep-RIE dedicated to a silicon substrate is performed (for example, see International Publication No. 2003/030239). Thereby, the portion of the silicon wafer that is not etched is removed, and the pressure chamber 201 is formed. The etching mask is formed by application of a photosensitive resist, pre-baking, exposure using a mask on which a desired pattern is formed, development, and post-baking.

The SF6 gas used for the etching does not exert an etching action on the SiO _{2 of the} diaphragm 104 and the polyimide of the protective film 108. Therefore, the progress of dry etching of the silicon wafer that forms the pressure chamber 201 stops at the vibration plate 104. In other words, the diaphragm 104 functions as a stop layer for the etching.

  Note that for the above-described etching, various methods such as a wet etching method using a chemical solution and a dry etching method using plasma may be used. Further, the etching method and etching conditions may be changed depending on the material. After the etching process using each photosensitive resist film is completed, the remaining photosensitive resist film is removed with a solution.

  As described above, from the process of forming the drive element 102 and the nozzle 101 on the diaphragm 104 to the process of forming the pressure chamber 201 in the pressure chamber structure 200, the film formation technique, the photolithography etching technique, and the spin coating are performed. Done by law. For this reason, the nozzle 101, the drive element 102, and the pressure chamber 201 are precisely and easily formed on one silicon wafer.

  Next, the separate plate 300 and the ink flow path structure 400 are bonded to the pressure chamber structure 200. That is, the separate plate 300 to which the ink flow path structure 400 is bonded is bonded to the pressure chamber structure 200 with an epoxy adhesive.

  Next, a cover tape is attached to a part of the protective film 108 so as to cover the terminal portion 106 a of the wiring electrode 106 and the terminal portion 107 a of the common electrode 107. The cover tape is made of resin and can be easily detached from the protective film 108. The cover tape prevents dust and ink repellent film 109 from adhering to the terminal portion 106 a of the wiring electrode 106 and the terminal portion 107 a of the common electrode 107.

  Next, an ink repellent film 109 is formed on the protective film 108. The ink repellent film 109 is formed by spin coating a liquid ink repellent film material on the protective film 108. At this time, positive pressure air is injected from the ink supply port 402. Accordingly, positive pressure air is discharged from the nozzle 101 connected to the ink flow path 401. When a liquid ink repellent film material is applied in this state, the ink repellent film material is suppressed from adhering to the inner peripheral surface of the nozzle 101. After the ink repellent film 109 is formed, the cover tape is peeled off from the protective film 108.

  Next, the silicon wafer is divided to form a plurality of inkjet heads 21. The inkjet head 21 is mounted inside the inkjet printer 1. The control unit 24 is connected to the terminal unit 106a of the wiring electrode 106 via, for example, a flexible cable. Furthermore, the ink supply port 402 and the ink discharge port 403 of the ink flow path structure 400 are connected to the ink tank 23 through, for example, a tube.

  As described above, in this embodiment, the nozzle plate 100 is formed on the pressure chamber structure 200. However, instead of creating the nozzle plate 100 on the pressure chamber structure 200, a part of the pressure chamber structure 200 may be used as the diaphragm 104. For example, the drive element 102 is formed on one surface of the pressure chamber structure 200, and a hole corresponding to the pressure chamber 201 is formed from the other surface side. The hole does not penetrate the pressure chamber structure 200. A thin layer remains on one surface side of the pressure chamber structure 200, and this portion operates as the diaphragm 104.

  According to the inkjet printer 1 of the first embodiment, by providing the opening 115, a portion where the protective film 108 does not exist is formed on the drive element 102. For this reason, the film stress of the protective film 108 which inhibits the deformation of the diaphragm 104 by the drive element 102 is reduced. In other words, a thin portion is provided in the insulating portion formed by the insulating film 105 and the protective film 108 on the driving element 102. For this reason, the film stress of the said insulation part which inhibits the deformation | transformation of the diaphragm 104 by the drive element 102 reduces. Therefore, the diaphragm 104 can be deformed with a small force of the drive element 102, and a decrease in the drive efficiency of the inkjet head 21 can be suppressed.

  The driving element 102 is covered with an insulating film 105. Thereby, even if the opening 115 is provided, the driving element 102 is suppressed from being corroded, deteriorated, and deteriorated in performance due to external factors such as ink and moisture in the air.

  The protective film 108 covers the wiring portion 107 b of the shared electrode 107, thereby preventing the wiring portion 107 b from being exposed through, for example, the opening 115. Thereby, it is suppressed that the wiring part 107b is corroded, deteriorated, and deteriorated in performance due to an external factor.

  Next, a second embodiment will be described with reference to FIG. Note that, in a plurality of embodiments disclosed below, the same reference numerals are given to components having the same functions as those of the inkjet printer 1 of the first embodiment. Further, the description of the components may be partially or entirely omitted.

  FIG. 9 is a cross-sectional view showing a part of the inkjet head 21 according to the second embodiment. In the second embodiment, the protective film 108 has a thin portion 121 instead of the opening 115.

  The thin portion 121 is a part of the protective film 108 thinner than other portions on the driving element 102. That is, on the drive element 102, the thickness of the thin portion 121 is, for example, 1 μm, and the thickness of the other portions is 2.5 μm as described above. The thin portion 121 forms a recess in the surface 108 a of the protective film 108.

  The thin portion 121 is provided on the same axis as the nozzle 101 and is formed in an annular shape surrounding the nozzle 101. In addition, the shape of the thin part 121 is not restricted to this. The inner diameter of the thin portion 121 may be smaller than the inner diameter of the drive element 102. The outer diameter of the thin portion 121 may be larger than the outer diameter of the drive element 102.

  The thin portion 121 is formed by etching using halftone exposure (half etching), for example. For this reason, the thin portion 121 is formed simultaneously with the nozzle 101.

  According to the inkjet head 21 of the second embodiment, by providing the thin portion 121, the film stress of the protective film 108 that inhibits the deformation of the diaphragm 104 by the drive element 102 is reduced. Therefore, the diaphragm 104 can be deformed with a small force of the drive element 102, and a decrease in the drive efficiency of the inkjet head 21 can be suppressed.

  Note that when the thin portion 121 is provided as in the second embodiment, the insulating film 105 may not be provided. In this case, the wiring electrode 106 and the shared electrode 107 are separated by, for example, the piezoelectric film 111 to prevent a short circuit.

  Next, a third embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a cross-sectional view showing a part of the inkjet head 21 according to the third embodiment. As shown in FIG. 10, in the inkjet head 21 according to the third embodiment, the nozzle 101 and the diaphragm 104 are arranged on opposite sides of the pressure chamber structure 200.

  The first surface 104 a of the diaphragm 104 is fixed to the first surface 200 a of the pressure chamber structure 200. On the second surface 104 b of the vibration plate 104, the driving element 102, the insulating film 105, the wiring electrode 106, the common electrode 107, and the protective film 108 are provided. The protective film 108 has an opening 115 as in the first embodiment.

  The nozzle plate 500 is fixed to the second surface 200 b of the pressure chamber structure 200. That is, the nozzle plate 500 faces the vibration plate 104. The nozzle plate 500 is formed in a rectangular plate shape with polyimide, for example. The material of the nozzle plate 500 is not limited to this.

  The nozzle plate 500 has a plurality of nozzles 101. The nozzle 101 communicates with the corresponding pressure chamber 201. The nozzle 101 is disposed on the same axis as the corresponding pressure chamber 201.

  FIG. 11 is a cross-sectional view showing a modification of the ink jet head 21 of the third embodiment. As shown in FIG. 11, the nozzle 101 may be disposed outside the region facing the drive element 102.

  Also in the inkjet head 21 of the third embodiment, by providing the opening 115, the film stress of the protective film 108 that inhibits the deformation of the diaphragm 104 by the drive element 102 is reduced. Therefore, the diaphragm 104 can be deformed with a small force of the drive element 102, and a decrease in the drive efficiency of the inkjet head 21 can be suppressed.

  According to at least one inkjet head described above, the protective film has an opening that exposes a part of the insulating film on the driving element. Thereby, the film stress of a protective film can be reduced and the drive efficiency of an inkjet head can be improved.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

For example, the inkjet head 21 may not have the separate plate 300.
By adjusting the specifications of the ink jet head 21 and the diameter and depth of the pressure chamber 201, the ink jet head 21 that does not have the separation plate 300 can also eject ink. In such an ink jet head 21, the accuracy of adhesive bonding of the pressure chamber structure 200, the separate plate 300, and the ink flow path structure 400 is about 0.2 mm. For this reason, the bonding is performed more easily and in a short time.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] A diaphragm having a base material having a pressure chamber for containing ink, a first surface closing the pressure chamber, and a second surface opposite to the first surface, and the vibration A drive element on the second surface of the plate that changes the volume of the pressure chamber by deforming the diaphragm when a voltage is applied; the second surface of the diaphragm; An insulating film that covers the driving element; and an insulating protective film that is on the insulating film and has an opening that exposes a part of the insulating film on the driving element. An inkjet head characterized by the above.
[2] A lead wire on the insulating film is further provided, and the driving element is opposed to the first electrode on the second surface of the diaphragm and the first electrode, and the lead is provided. A second electrode connected to the wiring; and a piezoelectric body interposed between the first electrode and the second electrode; and the insulating film includes a part of the second electrode. The inkjet head according to [1], wherein the inkjet head has a contact portion through which the lead wire connected to the second electrode is exposed, and the protective film covers the lead wire.
[3] The inkjet head according to [1] or [2], wherein the protective film and the insulating film are formed of different materials.
[4] The inkjet head according to any one of [1] to [3], an ink tank that is connected to the pressure chamber and contains ink, and a control unit that applies a voltage to the drive element; An ink jet recording apparatus comprising:
[5] A diaphragm is formed on one surface of the base material, and a driving element is formed on one surface of the diaphragm facing in the opposite direction of the base material to deform the diaphragm when a voltage is applied. And forming an insulating film covering the one surface of the diaphragm and the driving element, forming a protective film covering the insulating film, and forming the insulating film on the driving element on the protective film A method for manufacturing an ink jet head, wherein an opening for exposing a part of a film is formed by etching.
[6] A base material having a pressure chamber for containing ink, a diaphragm for closing the pressure chamber, and the diaphragm on the diaphragm when the voltage is applied to deform the diaphragm. At least one of a drive element that changes volume, an insulating portion that covers the diaphragm and the drive element and has a thinner portion on the drive element than the other portions, and the diaphragm and the protective film. A nozzle plate having a nozzle communicating with the pressure chamber.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 21 ... Inkjet head, 23 ... Ink tank, 24 ... Control part, 100, 500 ... Nozzle plate, 101 ... Nozzle, 102 ... Drive element, 104 ... Diaphragm, 104a ... First surface, 104b ... Second surface, 105 ... insulating film, 106 ... wiring electrode, 106c ... electrode part, 107 ... shared electrode, 107b ... wiring part, 107c ... electrode part, 108 ... protective film, 111 ... piezoelectric film, 113 ... contact part 115 ... Opening part, 121 ... Thin wall part, 200 ... Pressure chamber structure, 201 ... Pressure chamber.

Claims (5)

A substrate having a pressure chamber for containing ink;
A diaphragm having a first surface that closes the pressure chamber, and a second surface opposite to the first surface;
A nozzle penetrating the first surface and the second surface of the diaphragm;
A driving element that is on the second surface of the diaphragm and changes the volume of the pressure chamber by deforming the diaphragm when a voltage is applied;
An insulating film covering the second surface of the diaphragm and the drive element;
An insulating protective film having a concave portion which is a space portion in a portion corresponding to a part of the insulating film on the driving element and on the driving element;
An ink jet head comprising: Further comprising a lead wiring on the insulating film;
The drive element includes: a first electrode on the second surface of the diaphragm; a second electrode facing the first electrode and connected to the lead wiring; and the first electrode A piezoelectric body interposed between the second electrodes,
The insulating film has a contact portion that exposes a part of the second electrode and through which the extraction wiring connected to the second electrode passes.
The protective film covers the lead-out wiring;
The inkjet head according to claim 1.   The inkjet head according to claim 1, wherein the protective film and the insulating film are formed of different materials. An inkjet head according to any one of claims 1 to 3,
An ink tank connected to the pressure chamber and containing ink;
A controller for applying a voltage to the drive element;
An ink jet recording apparatus comprising: A diaphragm is formed on one side of the substrate,
On one surface of the diaphragm facing in the opposite direction of the substrate, a drive element is formed that deforms the diaphragm when a voltage is applied,
Forming a nozzle penetrating the diaphragm;
Forming an insulating film covering the one surface of the diaphragm and the drive element;
Forming a protective film covering the insulating film;
A recess that is a space portion is formed by etching in a portion corresponding to a part of the insulating film on the driving element in the protective film.
A method of manufacturing an ink-jet head.

Images