JP2016052723A - Ink jet head and ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head suppressed in reduction in driving efficiency of a driving element, and to provide an ink jet recording device.SOLUTION: An ink jet head 21 includes: a nozzle 101 discharging ink; a base material having a pressure chamber 201 storing the ink and communicating with the nozzle; a vibration plate 104 having a first surface 104a blocking up the pressure chamber 201 and a second surface 104b located at a side opposite to the first surface 104a; a driving element 102 deforming the vibration plate 104 when voltage is applied thereon, and mounted on the second surface 104b of the vibration plate 104 varying the cubic capacity of the pressure chamber 201; and a protection film 110 on which the driving element 102 is not mounted and which is arranged on the second surface 104b of the vibration plate 104. In addition, the protection film 110 is fitted so as to lie at least at the outside of a region where the driving element 102 is located, and cover part of the pressure chamber 201 across the vibration plate 104.SELECTED DRAWING: Figure 3

Description

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

  The ink jet head has, for example, a diaphragm having a pressure chamber for containing ink, and a driving element attached to one end of the pressure chamber. In addition, nozzles for ejecting ink are also formed on the diaphragm. Then, the vibration plate is deformed by using the driving element, and ink is ejected by utilizing the change in pressure in the pressure chamber. A protective film is provided on the surface of the diaphragm having the drive element in order to protect the drive element from corrosion due to ink or moisture in the air.

JP2013-208900A

  However, when the drive element is covered with a protective film, the operation of the drive element is suppressed, and the drive efficiency may be reduced.

  Therefore, development of an ink jet head and an ink jet recording apparatus that can suppress a decrease in driving efficiency is desired.

  An inkjet head according to an embodiment includes a nozzle that ejects ink, a base material that contains ink and has a pressure chamber that communicates with the nozzle, a first surface that closes the pressure chamber, and a side opposite to the first surface. And a driving element provided on the second surface of the diaphragm that deforms the diaphragm when a voltage is applied to change the volume of the pressure chamber, and the driving element. Has a protective film disposed on the second surface of the diaphragm not provided. In addition, the protective film is provided so as to cover at least a part of the pressure chamber on the outside of a region where the drive element is present and sandwiching the diaphragm.

FIG. 1 is a schematic diagram illustrating an inkjet printer according to the first embodiment. FIG. 2 is a perspective view showing the ink jet head according to the first embodiment. FIG. 3 is a cross-sectional view of the inkjet head of FIG. 2 taken along F4-F4. FIG. 4 is a cross-sectional view showing a state in which the first insulating film is provided in the manufacturing process of the ink jet head according to the first embodiment. FIG. 5 is a cross-sectional view showing a state in which the wiring portion of the common electrode is provided in the manufacturing process of the ink jet head according to the first embodiment. FIG. 6 is a cross-sectional view showing a state in which the second insulating film is provided in the manufacturing process of the ink jet head according to the first embodiment. FIG. 7 is a cross-sectional view showing a state in which a protective film is provided in the manufacturing process of the ink jet head of the first embodiment. FIG. 8 is a cross-sectional view showing a state in which nozzles and openings are provided in the manufacturing process of the ink jet head of the first embodiment. FIG. 9 is a cross-sectional view showing a second embodiment of the inkjet head. FIG. 10 is a cross-sectional view showing a third embodiment of the inkjet head. FIG. 11 is a cross-sectional view showing a fourth embodiment of the inkjet head.

  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 schematic 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 conveyance roller is driven and rotated by a motor to convey 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 (not shown) formed on the surface of the frame. This 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 color images by, for example, ejecting 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, for example, by 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 a perspective view showing one inkjet head 21 included in the image forming apparatus 16. FIG. 3 is a cross-sectional view showing a part of the inkjet head 21 along the line F4-F4 of FIG. FIG. 2 is a perspective view of the inkjet head 21 as viewed from the holding roller 13 side to show the nozzle plate 100.

  The ink jet printer 1 includes a plurality of ink tanks 23 and a plurality of control units 24 connected to a plurality of ink jet heads 21. 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.

  As shown in FIG. 2, the inkjet head 21 includes a nozzle plate 100, a pressure chamber structure 200, and an ink flow path structure 300. The inkjet head 21 is connected to the ink tank 23 and the control unit 24.

  The ink jet head 21 fills the pressure chamber 201 of the pressure chamber structure 200 with the ink supplied from the ink tank 23 via the ink flow path structure 300. The inkjet head 21 forms an image on the recording paper P by ejecting the ink in the pressure chamber 201 as ink droplets from a plurality of nozzles 101 formed on the nozzle plate 100. For example, the plurality of nozzles 101 are arranged in two rows on the nozzle plate 100. The distance between the centers of adjacent nozzles 101 of the nozzle plate 100 is, for example, 340 μm in the longitudinal direction and 240 μm in the short direction.

  The ink flow path structure 300 includes an ink supply port 302, an ink flow path 301, and an ink discharge port 303. Ink is supplied to the inkjet head 21 through the ink supply port 302 and flows into the pressure chambers 201 from the ink flow path 301. Ink that does not flow into the pressure chamber 201 passes through the ink flow path 301 and is discharged from the ink discharge port 303 to the ink tank 23. The ink-jet head 21 circulates ink between the ink tank 23 and the ink flow path 301 to keep the temperature of the ink constant, and suppress the deterioration of the ink due to heat.

  As illustrated in FIG. 3, the nozzle plate 100 includes a plurality of driving elements 102 that are driving units, a first insulating film 105, a protective film 110, and an ink repellent film 112 on a vibration plate 104. The diaphragm 104 is deformed in the thickness direction by the operation of the driving element 102. The ink jet head 21 ejects ink supplied to the nozzles 101 by a pressure change generated in the pressure chamber 201 of the pressure chamber structure 200 due to the deformation of the vibration plate 104.

  The plurality of drive elements 102 are arranged corresponding to the plurality of nozzles 101. In other words, the drive element 102 is positioned concentrically with 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 base material 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, 525 μm. The thickness of the pressure chamber structure 200 is, for example, in the range of 100 to 775 μm.

The diaphragm 104 is formed integrally with the pressure chamber structure 200, for example. When the silicon wafer as the pressure chamber structure 200 is heat-treated in an oxygen atmosphere, a SiO ₂ (silicon oxide) film is formed on the surface of the silicon wafer. The diaphragm 104 of this embodiment is a SiO ₂ (silicon oxide) film having a thickness of 4 μm on the surface of a silicon wafer formed by heat treatment in an oxygen atmosphere. The vibration plate 104 may be formed by forming a SiO ₂ (silicon oxide) film on the silicon wafer surface by a CVD method (chemical vapor deposition method).

The diaphragm 104 is a layer between the driving element 102 and the pressure chamber 201 and may be formed of a laminated film including a plurality of layers. The film thickness of the diaphragm 104 is preferably in the range of 1 to 50 μm. The diaphragm 104 may be made of a semiconductor material such as SiN (silicon nitride), Al ₂ O ₃ (aluminum oxide), or the like, instead of the SiO ₂ (silicon oxide) film.

  The pressure chamber structure 200 is formed using a silicon wafer. The pressure chamber structure 200 having a thickness of 525 μm has a warp reduction film 202 that is a warp reduction layer on the opposite surface separated from the diaphragm 104. The pressure chamber structure 200 penetrates the warp reduction film 202 to reach the diaphragm 104 and forms a plurality of pressure chambers 201 communicating with the nozzle 101. Here, in the pressure chamber structure 200, the side on which the vibration plate 104 is disposed is the first surface 200a, and the side on which the warp reduction film 202 is disposed is the second surface 200b.

  The pressure chamber 201 is a circular hole. 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 plurality of pressure chambers 201 are arranged corresponding to the plurality of nozzles 101. In other words, the pressure chamber 201 is formed concentrically with the corresponding nozzle 101. The nozzles 101 communicate with the corresponding pressure chambers 201, respectively. The pressure chamber 201 is connected to the outside of the inkjet head 21 through the nozzle 101.

  The ink flow path structure 300 is formed in a rectangular plate shape, for example. The thickness of the ink flow path structure 300 is, for example, 4 mm. The material of the ink flow path structure 300 is stainless steel. Note that the material of the ink flow path structure 300 may be formed of other materials such as ceramics or resin. The ceramics used are, for example, nitrides, carbides or oxides such as alumina ceramics, zirconia, silicon carbide, silicon nitride. The resin used is, for example, a plastic material such as ABS, polyacetal, polyamide, polycarbonate or polyethersulfone. The material of the ink flow path structure 300 is 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 warp reduction film 202 of the pressure chamber structure 200 is bonded to the ink flow path structure 300 with, for example, an epoxy adhesive. The pressure chamber 201 of the pressure chamber structure 200 communicates with the ink flow path 301 of the ink flow path structure 300 on the warp reduction film 202 side.

  The ink flow path 301 is a groove formed on the surface of the ink flow path structure 300 on the side bonded to the pressure chamber structure 200. The depth of the ink flow path 301 is 2 mm, for example.

  The ink supply port 302 opens at one end of the ink flow path 301. The ink supply port 302 is connected to the ink tank 23 via, for example, a tube. The ink tank 23 is connected to the plurality of pressure chambers 201 via the ink flow path 301.

  The ink in the ink tank 23 flows into the ink flow path 301 through the ink supply port 302. The ink supplied to the ink flow path 301 is supplied to the plurality of pressure chambers 201. 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.

  As shown in FIG. 3, the shape of the hole of the pressure chamber 201 is preferably larger in size L (depth) than in size D (diameter). By setting the shape of the pressure chamber 201 to depth L> diameter D, it is possible to delay the pressure relating to the ink in the pressure chamber 201 from escaping to the ink flow path 301. The inkjet head 21 includes a separate plate (not shown) between the pressure chamber 201 and the ink channel 301 so that the pressure applied to the ink in the pressure chamber 201 does not escape to the ink channel 301. The structure to do may be sufficient.

As the warp reduction film 202, for example, a SiO ₂ (silicon oxide) film having a thickness of 4 μm formed on the surface of the silicon wafer by heating the silicon wafer in an oxygen atmosphere is used. Further, the warp reduction film 202 can be formed by forming a SiO ₂ (silicon oxide) film on the surface of a silicon wafer by a CVD method (chemical vapor deposition method).

  The warp reduction film 202 functions to reduce warpage of the silicon wafer. The warp reduction film 202 reduces the warpage of the silicon wafer due to a difference in film stress between the pressure chamber structure 200 and the diaphragm 104, a difference in film stress between various constituent films of the drive element 102 described later, and the like. The warp reduction film 202 reduces the warp of the ink jet head 21 when a constituent member of the ink jet head 21 is formed using a film forming process.

  The material and thickness of the warp reduction film 202 may be different from those of the diaphragm 104. However, if the warp reduction film 202 is made of the same material as the diaphragm 104 and has the same film thickness, the film stress of the diaphragm 104 and the film stress of the warp reduction film 202 on both sides of the silicon wafer are the same. If the warp reduction film 202 is made of the same material as the diaphragm 104 and has the same film thickness, the warp generated in the inkjet head 21 can be more effectively reduced.

  Next, the nozzle plate 100 will be described in detail. As shown in FIG. 3, the nozzle plate 100 includes the nozzle 101 and the driving element 102, the diaphragm 104, the first insulating film 105, the plurality of wiring electrodes 108, the shared electrode 109, and the second insulating film. 106, a protective film 110, and an ink repellent film 112.

  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 a surface opposite to the first surface 104a.

  The plurality of wiring electrodes 108 are formed on the second surface 104 b of the diaphragm 104. As shown in FIGS. 2 and 3, each of the plurality of wiring electrodes 108 includes a terminal portion 108a, a wiring portion (first lead wiring) 108b, and an electrode portion (first electrode) 108c. The terminal portions 108 a of the plurality of wiring electrodes 108 are positioned at one end of the diaphragm 104 in the short direction and are arranged along the longitudinal direction of the diaphragm 104. The distance between each terminal part 108a is 170 micrometers, for example.

  The shared electrode 109 includes two terminal portions 109a, a plurality of wiring portions (second lead wires) 109b, and a plurality of electrode portions (second electrodes) 109c. The wiring portion 109b is an example of a lead wiring. The two terminal portions 109 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 108 a of the plurality of wiring electrodes 108 are arranged between the two terminal portions 109 a of the shared electrode 109.

  The plurality of wiring electrodes 108 are, for example, thin films of Pt (platinum) and Al (aluminum). The terminal portion 109a and the wiring portion 109b of the shared electrode 109 are, for example, Ti (titanium) and Al thin films. The electrode portion 109c of the shared electrode 109 is a Pt thin film. The plurality of wiring electrodes 108 and the common electrode 109 are made of 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 thicknesses of the plurality of wiring electrodes 108 and the shared electrode 109 are, for example, 0.5 μm. The film thicknesses of the plurality of wiring electrodes 108 and the common electrode 109 are generally in the range of 0.01 to 1 μm. The width of the wiring portions 108b and 109b of the plurality of wiring electrodes 108 and the shared electrode 109 is, for example, 80 μm.

  As shown in FIG. 3, 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 corresponding pressure chamber 201.

  The plurality of drive elements 102 each have an electrode portion 108 c of the wiring electrode 108, an electrode portion 109 c of the shared electrode 109, and a piezoelectric film 111. The electrode part 108c of the wiring electrode 108 is an example of a first electrode and is also referred to as a lower electrode. The electrode portion 109c of the shared electrode 109 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 108 c of the wiring electrode 108 is on the second surface 104 b of the diaphragm 104. The electrode part 108 c is formed in an annular shape surrounding the nozzle 101. The electrode part 108 c is located concentrically with the nozzle 101. The outer diameter of the electrode part 108c is, for example, 133 μm. The inner diameter of the electrode portion 108c is, for example, 30 μm. For this reason, the electrode part 108 c is separated from the nozzle 101.

  The wiring part 108 b of the wiring electrode 108 is formed on the second surface 104 b of the diaphragm 104. As shown in FIG. 2, the wiring part 108 b connects the electrode part 108 c and the terminal part 108 a of the corresponding driving element 102. The plurality of wiring portions 108 b extend in parallel along the short direction of the nozzle plate 100. Some wiring parts 108b pass between the drive elements 102 arranged side by side.

  As shown in FIG. 3, the piezoelectric film 111 surrounds the nozzle 101 and is formed in an annular shape having approximately the same size as the electrode portion 108 c of the wiring electrode 108. The piezoelectric film 111 is formed slightly smaller than the electrode portion 108c of the wiring electrode 108, but may be larger than the electrode portion 108c. The piezoelectric film 111 is located concentrically with the nozzle 101. The piezoelectric film 111 covers the electrode portion 108 c of the wiring electrode 108.

In the present embodiment, the piezoelectric film 111 is a film of lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT). The piezoelectric film 111 is not limited to this, and for example, PTO (PbTiO ₃ : lead titanate), PMNT (Pb (Mg1 / 3Nb2 / 3) O ₃ —PbTiO ₃ ), PZNT (Pb (Zn1 / 3Nb2 / ₃ ) ) O ₃ —PbTiO ₃ ), ZnO and AlN may be used to form the piezoelectric material.

  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 part 109 c of the shared electrode 109 surrounds the nozzle 101 and is formed in an annular shape having approximately the same size as the electrode part 108 c of the wiring electrode 108 and the piezoelectric film 111. The electrode portion 109 c of the shared electrode 109 is formed slightly smaller than the piezoelectric film 111, but may be larger than the piezoelectric film 111. The electrode portion 109 c is located concentrically with the nozzle 101. The electrode portion 109 c covers the piezoelectric film 111. In other words, the electrode portion 109c 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 108 c of the wiring electrode 108 and the electrode portion 109 c of the shared electrode 109. In other words, the electrode portions 108 c and 109 c of the wiring electrode 108 and the shared electrode 109 overlap the piezoelectric film 111. The piezoelectric film 111 insulates between the two electrode portions 108c and 109c. The electrode part 109 c of the shared electrode 109 faces the electrode part 108 c of the wiring electrode 108 with the piezoelectric film 111 interposed therebetween.

  The electrode portion 109 c of the shared electrode 109 forms the outer surface 102 a of the drive element 102. The outer surface 102 a is one surface of the drive element 102 on the side separated from the diaphragm 104. In other words, the outer surface 102 a is a surface on 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 first insulating film 105 covers the second surface 104 b of the vibration plate 104, the surface 102 a of the drive element 102, and the wiring part 108 b of the wiring electrode 108. The first insulating film 105 has a plurality of holes that expose the terminal portions 108 a of the plurality of wiring electrodes 108.

The first insulating film 105 is formed by, for example, SiO _2. The first insulating film 105 may be formed of other materials such as SiN (silicon nitride), for example. The first insulating film 105 has a substantially uniform thickness on the second surface 104 b of the diaphragm 104, the outer surface 102 a of the drive element 102, and the wiring part 106 b of the wiring electrode 108. The thickness of the first insulating film 105 is 1 μm. The first insulating film 105 has a thickness of approximately 0.1 μm to 5 μm. Note that the thickness of the first insulating film 105 may be partially different.

  The first insulating film 105 has a plurality of contact portions 113. The contact portion 113 is a hole provided in a part of the first 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 109 c of the shared electrode 109. The contact portion 113 is disposed closer to the outer periphery of the electrode portion 109c than the center between the inner periphery and the outer periphery of the annular electrode portion 109c.

  The two terminal portions 109 a and the plurality of wiring portions 109 b of the shared electrode 109 are on the surface 105 a of the first insulating film 105. In other words, the terminal portion 109 a and the wiring portion 109 b of the shared electrode 109 are on the first insulating film 105. The surface 105 a of the first insulating film 105 is a surface opposite to the side away from the diaphragm 104.

  As shown in FIG. 2, the plurality of wiring portions 109b of the shared electrode 109 extend from the corresponding electrode portion 109c of the driving element 102 and the two terminal portions 109a. The plurality of wiring portions 109 b extend in parallel to each other along the short direction of the nozzle plate 100.

  The plurality of wiring portions 109 b are combined at the other end portion in the short 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 109a and the plurality of electrode portions 109c are connected by the plurality of wiring portions 109b.

  As shown in FIG. 3, the wiring portion 109 b of the shared electrode 109 is provided on the surface 105 a of the first insulating film 105 that covers the driving element 102. One end of the wiring portion 109 b is connected to the electrode portion 109 c of the shared electrode 109 through the contact portion 113. In other words, the contact portion 113 is a portion where the first insulating film 105 is partially removed in order to connect the wiring portion 109b to the electrode portion 109c.

  The first insulating film 105 separates the wiring portion 109 b of the shared electrode 109 and the electrode portion 108 c of the wiring electrode 108. The first insulating film 105 prevents the wiring electrode 108 and the shared electrode 109 from being electrically connected.

  The second insulating film 106 is on the wiring portion 109 b of the shared electrode 109 and the surface 105 a of the first insulating film 105 and covers the wiring portion 109 b of the shared electrode 109. For example, the second insulating film 106 prevents adhesion of ink or moisture in the air, and prevents the wiring portion 109b from being corroded, deteriorated, and deteriorated in performance.

The second insulating film 106 is made of, for example, SiO ₂ . The second insulating film 106 may be formed of other materials such as SiN (silicon nitride), for example. The thickness of the second insulating film 106 is 1 μm. The thickness of the second insulating film 106 is approximately in the range of 0.1 μm to 5 μm. Note that the thickness of the second insulating film 106 may be partially different.

  The protective film 110 is on the second surface 104 b of the diaphragm 104. The protective film 110 is made of, for example, photosensitive polyimide such as Photo Nice (registered trademark) manufactured by Toray Industries, Inc. That is, the protective film 110 is formed of a material different from that of the first insulating film 105 and the second insulating film 106. The protective film 110 is not limited to this, and may be formed of other resin materials. Resin materials that can be used as the protective film 110 are plastic materials such as other types of polyimide, ABS, polyacetal, polyamide, polycarbonate, and polyethersulfone.

  The material of the protective film 110 is selected in consideration of heat resistance, insulation, thermal expansion coefficient, smoothness, and ink wettability. Note that the insulation of the material of the protective film 110 affects the degree of ink alteration when the drive element 102 is driven when the ink jet printer 1 uses ink with high conductivity.

  The protective film 110 covers a region other than the region where the driving element 102 is present on the second surface 104 b of the diaphragm 104. The protective film 110 adheres to the diaphragm 104 and prevents the diaphragm 104 from buckling. That is, the protective film 110 supports the bending deformation of the vibration plate 104 by the drive element 102 and prevents the vibration plate 104 from being damaged. Specifically, the protective film 100 is disposed so as to cover a part of the pressure chamber 201 with the diaphragm 104 interposed therebetween. In other words, the protective film 100 is provided so as to protrude from the edge of the pressure chamber 201 to the inside of the pressure chamber 201. Accordingly, when the diaphragm 104 is deformed in conjunction with driving of the drive element 102, the diaphragm 104 is prevented from being deformed and damaged.

The material of the protective film 110 is different 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 110 is 4 GPa. That is, the Young's modulus of the protective film 110 is smaller than the Young's modulus of the diaphragm 104.

  The protective film 110 has a plurality of holes exposing the plurality of terminal portions 108a of the wiring electrode 108 and the plurality of terminal portions 109a of the shared electrode 109, respectively.

  The thickness of the protective film 110 other than the portion where the drive element 102, the wiring electrode 108, and the shared electrode 109 are present is about 4 μm. The thickness of the protective film 110 is generally in the range of 1 to 50 μm. The thickness of the protective film 110 is a distance from the second surface 104 b of the diaphragm 104 to the surface 110 a of the protective film 110.

  The protective film 110 has an opening (removal part, recess) 115 where the protective film 110 is not provided on the driving element 102. The outer diameter of the opening 115 is substantially the same as the outer diameter of the driving element 102. In other words, the protective film 110 is not formed on the driving element 102.

  The opening 115 surrounds the corresponding nozzle 101. The opening 115 is arranged concentrically with 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 the first insulating film 105 on the driving element 102 and the second insulating film 106 on the wiring part 109 b of the shared electrode 109.

  The ink repellent film 112 covers the protective film 110 and the first insulating film 105 and the second insulating film 106 located in the opening 115. The ink repellent film 112 is formed of a liquid repellent silicone-based liquid repellent material or a fluorine-containing organic material (for example, Cytop (registered trademark) of Asahi Glass Co., Ltd.).

  The surface 112 a of the ink repellent film 112 forms the surface of the nozzle plate 100. The surface 112 a of the ink repellent film 112 is located on the opposite side of the protective film 110, the first insulating film 105, and the second insulating film 106 separated from the vibration plate 104.

  The thickness of the ink repellent film 112 other than the portion where the drive element 102, the shared electrode 109, and the wiring electrode 108 are present is, for example, 1 μm. The thickness of the ink repellent film 112 is, for example, in the range of 0.01 to 10 μm. The thickness of the ink repellent film 112 in the portion where the drive element 102 is provided is thinner than the other portions. The thickness of the ink repellent film 112 may be constant.

  Ink ejection stability may be reduced when ink adheres to the vicinity of the nozzle 101. The ink repellent film 112 suppresses ink from adhering to the surface of the nozzle plate 100.

  The nozzle 101 passes through the vibration plate 104, the drive element 102, and the ink repellent film 112. In other words, the nozzle 101 is formed of the vibration plate 104, the driving element 102, and the ink repellent film 112. Since the vibration plate 104 has ink affinity (lyophilic property), the meniscus of the ink stored in the pressure chamber 201 is kept in the nozzle 101.

  As shown in FIG. 2, the control unit 24 is connected to the terminal unit 108a of the wiring electrode 108 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 109a of the shared electrode 109 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 108. The wiring electrode 108 is used as an individual electrode for operating the plurality of driving elements 102 independently.

  When the driving element 102 extends in a direction orthogonal to the electric field direction, the vibration plate 104 bends 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, the diaphragm 104 is curved in a direction in which the volume of the pressure chamber 201 is increased.

  When the opening 115 is not formed in the nozzle plate 100, the driving element 102 is covered with the first insulating film 105, the second insulating film 106, and the protective film 110. In this case, the deformation of the driving element 102 is greatly inhibited as compared with the case where the opening 115 is formed. In other words, the opening 115 reduces the film stress of the protective film 110 that hinders the deformation of the drive element 102.

  When the driving element 102 extends in a direction orthogonal to the electric field direction, the diaphragm 104 can be bent more greatly so that the volume of the pressure chamber 201 is reduced by reducing the film stress. On the other hand, when the driving element 102 contracts in a direction perpendicular to the electric field direction, the diaphragm 104 can be greatly curved in a direction in which the volume of the pressure chamber 201 is expanded.

For example, the inkjet head 21 discharges ink as follows.
A print instruction signal is input to the control unit 24 by a user operation. The control unit 24 transmits a signal to the plurality of drive elements 102 based on the print instruction. In other words, the control unit 24 selectively applies a drive voltage to the electrode unit 108 c of the wiring electrode 108.

  When a driving voltage is applied to the electrode portion 108 c of the wiring electrode 108, a potential difference is generated between the electrode portion 108 c of the wiring electrode 108 and the electrode portion 109 c of the common electrode 109. As a result, a drive voltage in the same direction as the polarization direction is applied to the piezoelectric film 111 of the drive element 102. The drive element 102 expands and contracts in a direction orthogonal to the electric field direction. The drive element 102 operates in a bending mode (bending vibration).

  As described above, the drive element 102 changes the volume of the pressure chamber 201 by deforming the diaphragm 104 when a voltage is applied. That is, when the drive element 102 extends in a direction perpendicular to the electric field direction, the diaphragm 104 is deformed in a direction that increases the volume of the pressure chamber 201. As a result, negative pressure is generated in the ink stored in the pressure chamber 201. As a result, the ink flows from the ink flow path 301 into the pressure chamber 201.

  On the other hand, when the drive element 102 contracts in a direction orthogonal to the electric field direction, the diaphragm 104 is deformed in a direction that reduces the volume of the pressure chamber 201. Thereby, the ink in the pressure chamber 201 is pressurized. A part of the ink pressurized by the deformation of the vibration plate 104 in this way is ejected from the nozzle 101.

  By providing the opening 115 in the protective film 110 as in this embodiment, the film stress due to the drive element 102 that inhibits the deformation of the diaphragm 104 can be reduced. Thus, by reducing the film stress of the protective film 110 applied to the driving element 102, the voltage required for ink ejection can be lowered. For this reason, the inkjet head 21 of this embodiment can discharge ink efficiently.

  Further, as shown in FIG. 3, the thickness H2 from the second surface 104b of the diaphragm 104 located at the opening 115 to the surface 112a of the ink repellent film 112 on the driving element 102 is It is thinner than the thickness H1 from the second surface 104b of the diaphragm 104 on the outside to the surface 112a of the ink repellent film 112 with the protective film 110 interposed therebetween. In other words, the region of the opening 115 is depressed more than other regions.

  The surface of the nozzle plate 100 is periodically wiped by a wiping blade (not shown) in order to clean the attached ink. Since the region of the opening 115 is depressed more than the other regions, the wiping blade is not directly caught by the driving element 102. Therefore, according to the ink jet head 21 of the present embodiment, the damage due to the wiping blade coming into contact with the driving element 102 is unlikely to occur. In other words, the opening 115 suppresses damage to the drive element 102 when the surface of the nozzle plate 100 is cleaned by the wiping blade.

  Next, an example of a method for manufacturing the inkjet head 21 will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the first insulating film 105 is formed.

First, the diaphragm 104 (SiO ₂ film) 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. The SiO ₂ film can be formed by other methods such as a CVD method.

  The silicon wafer forming the pressure chamber structure 200 is a single large disk. The pressure chamber structure 200 is cut into a plurality of pieces from the silicon wafer. One pressure chamber structure 200 may be formed from one rectangular silicon wafer.

  The silicon wafer is repeatedly heated in the manufacturing process of the inkjet head 21 to form a thin film. The silicon wafer used for forming the pressure chamber structure 200 has heat resistance, and is smoothed by mirror polishing according to SEMI (Semiconductor Equipment and Materials International) standard.

  Next, a metal film for forming the wiring electrode 108 is formed on the second surface 104b of the vibration plate 104 (see FIG. 4). The wiring electrode 108 is formed by sequentially forming a Ti film and a Pt film using a sputtering method. 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 of the wiring electrode 108 may be formed by other manufacturing methods such as vapor deposition and plating.

  Then, a piezoelectric film 111 is formed on the metal film that forms the wiring electrode 108 (see FIG. 4). The piezoelectric film 111 is formed by, for example, an RF magnetron sputtering method. The temperature of the silicon wafer at this time is 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.

  The piezoelectric film 111 after the heat treatment 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 metal film of Pt (platinum) / Ti (titanium) that forms the electrode portion 109c of the shared electrode 109 is formed on the piezoelectric film 111 (FIG. 4). 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.

  The electrode portion 109c and the piezoelectric film 111 are patterned by etching the metal film and the piezoelectric film. The patterning is performed by creating an etching mask on the metal film and removing the metal film and the piezoelectric film other than the portion where the etching mask is applied by etching. The metal film and the piezoelectric film are patterned together. Note that the metal film and the piezoelectric film 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.

  The wiring electrode 108 is formed by patterning. In the patterning, an etching mask is formed on the piezoelectric film 111 and the electrode portion 109c of the shared electrode 109 and the metal film (Pt / Ti) below the piezoelectric film 111, and the metal other than the portion where the etching mask is applied. This is done by removing the film 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.

  And the nozzle 101 is formed in the center of the electrode part 108c, 109c of the wiring electrode 108 and the shared electrode 109, and the piezoelectric material film 111 (refer FIG. 4). A portion where the electrode portions 108 c and 109 c and the piezoelectric film 111 are not formed is formed at a position concentric with the centers of the electrode portions 108 c and 109 c and the piezoelectric film 111. In other words, a portion where the diaphragm 104 is exposed is formed at a position concentric with the centers of the electrode portions 108 c and 109 c and the piezoelectric film 111.

  As shown in FIG. 4, the first insulating film 105 is formed on the second surface 104 b of the vibration plate 104, the wiring portion 108 b of the wiring electrode 108, and the driving element 102. The first insulating film 105 is formed by a CVD method that can realize good insulating properties at low temperature. The method for forming the first insulating film 105 is not limited to this, and the first insulating film 105 may be formed by other methods such as sputtering or vapor deposition.

  The first insulating film 105 is formed on the entire second surface 104b of the diaphragm on which the driving element 102 is disposed, and then patterned. Since the first insulating film 105 forms the nozzle 101, a portion of the film located concentrically with the center of the driving element 102 is removed. The contact portion 113 is formed on a part of the first insulating film 105 that covers the driving element 102 (see FIG. 5). The patterning is performed by etching the first insulating film 105 that is not covered with the etching mask. 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. 5 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the wiring portion 109b of the shared electrode 109 is formed. On the first insulating film 105, a metal film for forming the terminal portion 109a (see FIG. 2) of the shared electrode 109 and the wiring portion 109b is formed. The metal film is formed by, for example, a sputtering method. Pt (platinum) / Ti (titanium), Ti (titanium) / Al (aluminum) thin film can be used as the material of the metal film forming the shared electrode 109. The film thickness of Ti is, for example, 0.1 μm, and the film thickness of Al or Ti is, for example, 0.4 μm. The metal film may be formed by other manufacturing methods such as vacuum deposition and plating. The wiring part 109 b is connected to the electrode part 109 c through the contact part 113 provided in the first insulating film 105.

  As shown in FIG. 5, the terminal portion 109a (see FIG. 2) and the wiring portion 109b are formed by patterning the metal film. The patterning is performed by creating an etching mask on the metal film and etching the metal film other than the portion covered with the etching mask. 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.

  FIG. 6 is a cross-sectional view showing the inkjet head 21 in the manufacturing process in which the second insulating film 106 is formed. As shown in FIG. 6, the second insulating film 106 is formed on the wiring portion 109 b of the shared electrode 109. The second insulating film 106 is formed by a CVD method that can realize good insulating properties at low temperature. The second insulating film 106 is not limited to this, and may be formed by other methods such as sputtering or vapor deposition.

  The second insulating film 106 is formed on the second surface 104b of the diaphragm on which the first insulating film 105 is formed, and then patterned. The second insulating film 106 is formed so as to cover the wiring portion 109b of the shared electrode 109, and other portions are removed. The patterning is performed by creating an etching mask on the second insulating film 106 and etching the second insulating film 106 other than the portion covered with the etching mask. 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.

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 is a SiO ₂ film except portions covered with the etching mask is performed by etching. The etching mask is formed by applying 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 110 is formed. The protective film 110 is formed on the diaphragm 104, the first insulating film 105, and the second insulating film 106 by a spin coating method (spin coating).

  Specifically, the protective film 110 covers the second surface 104b of the diaphragm 104, the first insulating film 105, and the second insulating film 106 with a solution containing a polyimide precursor. Next, the silicon wafer is rotated to smooth the surface of the solution containing the polyimide precursor covering the second surface 104b. Then, the silicon wafer is baked for a predetermined time. The polyimide precursor is heat-polymerized and the solvent is removed by baking to form the protective film 110 (polyimide). The method for forming the protective film 110 is not limited to spin coating. The protective film 110 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.
The protective film 110 is patterned to form the nozzle 101 and the opening 115, and expose the terminal portion 108a of the wiring electrode 108 and the terminal portion 109a of the shared electrode 109 (opening 115). The patterning is performed according to a procedure corresponding to the material of the protective film 110.

  First, the case where the protective film 110 is formed of non-photosensitive polyimide such as Semicofine (registered trademark) manufactured by Toray Industries, Inc. will be described. In this case, first, as described above, a solution containing a polyimide precursor is formed by spin coating, and thermal polymerization and solvent removal are performed by baking to form a protective film 110 of non-photosensitive polyimide. Thereafter, an etching mask is formed on the non-photosensitive polyimide film, and patterning is performed by etching the polyimide film other than the portion covered with the etching mask. The etching mask is formed by applying a photosensitive resist on the non-photosensitive polyimide film, pre-baking, exposure using the etching mask on which a desired pattern is formed, development, and post-baking.

  Next, the case where the protective film 110 is formed of photosensitive polyimide such as Photo Nice (registered trademark) manufactured by Toray Industries, Inc. will be described. First, as described above, the solution is formed into a film by a spin coating method and then pre-baked. Thereafter, patterning is performed through an exposure using an etching mask and a development process. In the case of positive photosensitive polyimide, the etching mask opens a portion corresponding to the nozzle 101, the opening 115, the terminal portion 108a of the wiring electrode 108, and the terminal portion 109a of the common electrode 109 (light is transmitted). Be placed. On the other hand, in the case of negative photosensitive polyimide, the etching mask is arranged so that the portions corresponding to the nozzle 101, the opening 115, the terminal portion 108a of the wiring electrode 108, and the terminal portion 109a of the common electrode 109 are shielded from light. . Thereafter, the silicon wafer is post-baked to form the protective film 110.

  Next, a cover tape (not shown) is affixed on the protective film 110. 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.

  As the patterning method, for example, vertical deep dry etching called Deep-RIE dedicated to a silicon substrate can be used. As a result, the portion of the silicon wafer not covered with the etching mask 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 SF 6 gas used for forming the pressure chamber 201 does not exert an etching action on the SiO _{2 of the} diaphragm 104 and the polyimide of the protective film 110. Therefore, the progress of dry etching of the silicon wafer forming 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, the manufacturing process of the inkjet head 21 includes the process of forming the pressure chamber 201 in the pressure chamber structure 200 from the process of forming the drive element 102 and the nozzle 101 on the vibration plate 104. The manufacturing process includes techniques such as a film forming technique, a photolithography etching technique, and a spin coating method. The nozzle 101, the driving element 102, and the pressure chamber 201 are precisely and easily formed on one silicon wafer.

Subsequently, the ink flow path structure 300 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 110 so as to cover the terminal portion 108 a of the wiring electrode 108 and the terminal portion 109 a of the common electrode 109. The cover tape is made of resin and can be easily detached from the protective film 110. The cover tape prevents the ink-repellent film 112 and dust from adhering to the terminal portion 108 a of the wiring electrode 108 and the terminal portion 109 a of the common electrode 109.

  Next, the ink repellent film 112 is formed on the surface of the protective film 110 opposite to the diaphragm 104 and the opening 115 (FIG. 3). The ink repellent film 112 is formed by spin-coating a liquid ink repellent film material on the protective film 110 or the like. When forming the ink repellent film, positive pressure air is injected into the inkjet head 21 from the ink supply port 302. The positive pressure air is discharged from the nozzle 101 connected to the ink flow path 301. Thereby, the liquid ink repellent film material is applied to the surface of the protective film 110 and the like, but the ink repellent film material is prevented from adhering to the inner peripheral surface of the nozzle 101. The cover tape is peeled off from the protective film 110 after the ink repellent film 112 is formed.

  Then, the plurality of inkjet heads 21 formed on one silicon wafer as described above are divided. The inkjet head 21 is mounted inside the inkjet printer 1. For example, the control unit 24 is connected to the terminal unit 108a of the wiring electrode 108 via a flexible cable. Furthermore, the ink supply port 302 and the ink discharge port 303 of the ink flow path structure 300 are connected to the ink tank 23 via a tube or the like.

  As described above, in the first 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 ink jet printer 1 of the first embodiment, the protective film 110 is not provided in the region where the driving element 102 is disposed by providing the opening 115 in the protective film 110. For this reason, the film stress of the protective film 110 that hinders the deformation of the drive element 102 is removed. Therefore, the drive element 102 can deform the diaphragm 104 with a small force, and can suppress a decrease in drive efficiency of the inkjet head 21.

  Further, the nozzle 101 of the inkjet head 21 is formed on the vibration plate 104, and the protective film 110 is not provided inside the driving element 102. For this reason, it can suppress that the shape of the nozzle 101 becomes nonuniform. That is, it is possible to suppress the occurrence of non-uniform shapes and positions in part of the nozzle 101 provided on the vibration plate 104 and part of the nozzle 101 provided on the protective film 110. Accordingly, the uniformity of the shape of the nozzle 101 is improved, and the landing position accuracy of the ink droplets between the plurality of nozzles 101 is improved.

  According to the present embodiment, the driving element 102 is covered with the first insulating film 105 and the ink repellent film 112. For this reason, even if the opening 115 is provided, the driving element 102 is prevented from being corroded, deteriorated, and deteriorated in performance due to external factors such as ink and moisture in the air.

  Further, the protective film 110 can be disposed inside the pressure chamber 201 with the diaphragm 104 interposed therebetween, thereby preventing the diaphragm 104 from being damaged due to the bending vibration of the drive element 102.

Next, second to fourth embodiments will be described with reference to FIGS. 9 to 11.
Note that, in a plurality of embodiments disclosed below, components having the same functions as those of the inkjet printer 1 of the first embodiment are denoted by the same reference numerals. Further, the description of the constituent elements may be partially or entirely omitted.

  FIG. 9 is a cross-sectional view showing a part of an inkjet head 21A according to the second embodiment. The inkjet head 21 </ b> A is different from the inkjet head 21 of the first embodiment in that a protective film 110 is provided on a part of the nozzle 101. Other configurations are the same as those of the inkjet head 21 of the first embodiment.

  The ink jet head 21 </ b> A has a cylindrical protective film 110 on the outer peripheral portion of the nozzle 101 and on the inner peripheral portion of the driving element 102. Thus, by providing the protective film 110 inside the drive element 102, it is possible to further suppress the drive element 102 from being corroded, deteriorated, and deteriorated in performance due to external factors such as ink and moisture in the air.

  FIG. 10 is a cross-sectional view showing a part of an inkjet head 21B according to the third embodiment. The protective film 110 of the inkjet head 21B is not in contact with the outer peripheral portion 102c of the drive element 102. In other words, the inkjet head 21 </ b> B of the present embodiment has a gap 116 between the side surface 110 c on the driving element 102 side of the protective film 110 and the outer peripheral portion 102 c of the driving element 102.

  The gap 116 is provided concentrically with the nozzle 101 and is formed in an annular shape surrounding the drive element 102. The width of the gap 116 is, for example, about 5 μm. The gap 116 is formed at the same time when the opening 115 and the nozzle 101 are formed in the protective film 110.

  In the ink jet head 21 </ b> B of the third embodiment, the driving element 102 is disposed away from the protective film 110 by providing the gap 116. The drive element 102 is arranged with the protective film 110 and the gap 116 interposed therebetween, thereby improving drive efficiency. Specifically, since the protective film 110 is formed of a resin such as polyimide, the coefficient of thermal expansion is larger than that of other members. For this reason, the protective film 110 that has returned to room temperature after firing has a residual stress in the tensile direction. For this reason, when the driving element 102 and the protective film 110 are in contact, the residual stress in the tensile direction of the protective film 110 acts on the driving element 102.

  On the other hand, in the third embodiment, the drive element 102 is disposed with the protective film 110 and the gap 116 interposed therebetween. For this reason, the tensile stress which acts on the drive element 102 from the protective film 110 is lost. Therefore, in the inkjet head 21 </ b> B of the third embodiment, the drive efficiency is further improved because the deformation of the drive element 102 is not hindered by the residual stress of the protective film 110.

  In addition, lead zirconate titanate (PZT), which is a material of the piezoelectric film 111 constituting the driving element 102, is liable to break against tensile stress. In contrast, the inkjet head 21B of the present embodiment has a gap 116 between the drive element 102 and the protective film 110 so that the drive element 102 and the protective film 110 do not contact with each other. The durability of the element 102 is improved. Therefore, the durability of the inkjet head 21B is improved.

  FIG. 11 is a cross-sectional view showing a part of an inkjet head 21C according to the fourth embodiment. The inkjet head 21 </ b> C of the fourth embodiment is different from the inkjet head 21 </ b> B of the third embodiment in that a protective film 110 is formed on the inner peripheral side of the drive element 102.

  According to the inkjet head 21 </ b> C of the fourth embodiment, the nozzle 101 is formed by the diaphragm 104 and the protective film 110. Since the ink jet head 21 </ b> C has the protective film 110 around the nozzle 101, the ink does not directly touch the insulating film 105. For this reason, the ink jet head 21 </ b> C can prevent a short circuit of the circuit due to the ink by having the protective film 110 even when a gap or the like is generated in the insulating film 105.

  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 shape of the driving element 102 is not limited to a circle and a rhombus, and may be another shape such as an ellipse or a rectangle. Further, the opening 115 may be exposed without being covered with the ink repellent film 112.

  In the above embodiment, the diaphragm 104 is formed on the pressure chamber structure 200. Alternatively, the diaphragm 104 is formed as an oxide of the material of the pressure chamber structure 200 by oxidizing the surface of the pressure chamber structure 200. However, a part of the material of the pressure chamber structure 200 may be used as the diaphragm. For example, the driving element 102 is formed on the first surface 200a of the pressure chamber structure 200, and a hole that does not penetrate the pressure chamber structure 200 is formed at a position corresponding to the pressure chamber 201 from the second surface 200b. A thin layer remains on the first surface 200a side of the pressure chamber structure 200, and this portion operates as a diaphragm.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Housing | casing, 11 ... Paper feed cassette, 12 ... Paper discharge tray, 13 ... Holding roller, 14 ... Conveyance apparatus, 15 ... Holding apparatus, 16 ... Image forming apparatus, 17 ... Static elimination peeling apparatus, DESCRIPTION OF SYMBOLS 18 ... Reversing device, 19 ... Cleaning device, 19a ... Cleaning member, 21, 21A, 21B, 21C ... Inkjet head, 23 ... Ink tank, 24 ... Control part, 100 ... Nozzle plate, 101 ... Nozzle, 102 ... Drive element, DESCRIPTION OF SYMBOLS 102a ... Outer surface, 104 ... Diaphragm, 104a ... 1st surface, 104b ... 2nd surface, 105 ... 1st insulating film, 106 ... 2nd insulating film, 108 ... Wiring electrode, 108a ... Terminal part, 108b ... Wiring Part (first lead wiring), 108c... Electrode part (first electrode), 109... Shared electrode, 109a... Terminal part, 109b .. wiring part (second lead wiring), 109 DESCRIPTION OF SYMBOLS ... Electrode part (2nd electrode), 110 ... Protective film, 110a ... Surface, 110c ... Side surface on the drive terminal side, 111 ... Piezoelectric film, 112 ... Ink-repellent film, 112a ... Surface, 116 ... Gap, 200 ... Pressure chamber Structure 200a ... first surface 200b ... second surface 201 ... pressure chamber 202 ... warp reduction film 300 ... ink flow channel structure 301 ... ink flow channel 302 ... ink supply port 303 ... Ink outlet.

Claims (5)

A nozzle for ejecting ink;
A substrate containing ink and having a pressure chamber communicating with the nozzle;
A diaphragm having a first surface that closes the pressure chamber, and a second surface opposite to the first surface;
A driving element provided on the second surface for deforming the diaphragm when a voltage is applied and changing a volume of the pressure chamber;
A protective film disposed on the second surface where the driving element is not provided;
The ink jet head according to claim 1, wherein the protective film is provided at least outside a region where the driving element is located so as to cover a part of the pressure chamber with the diaphragm interposed therebetween.   The inkjet head according to claim 1, wherein a gap is provided between the protective film and the driving element.   The inkjet head according to claim 1, wherein a thickness of the protective film is larger than a thickness of the driving element. The drive element includes a piezoelectric body, a first electrode connected to the piezoelectric body and located on the second surface of the diaphragm, and a second electrode facing the first electrode with the piezoelectric body interposed therebetween. Including
The first electrode includes a first lead wire, the second electrode includes a second lead wire, and the drive element, the first lead wire, and the second lead wire are insulated by an insulating film. The inkjet head according to any one of claims 1 to 3, wherein the inkjet head is characterized by the following. The inkjet head according to any one of claims 1 to 4,
An ink tank for supplying ink to the pressure chamber;
A transport unit that transports a recording medium to a position where ink is ejected from the inkjet head;
An ink jet recording apparatus comprising:

Images