JP2015006800A - Inkjet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet head capable of suppressing degradation in print quality.SOLUTION: An inkjet head includes: a piezoelectric member 13 that forms an ink pressure chamber 14; an electrode 16 arranged on a side surface of the piezoelectric member 13 opposed to the ink pressure chamber 14; a nozzle plate 20 adhesively bonded to an upper surface 13T of the piezoelectric member 13 near an opening of the ink pressure chamber 14 and including a nozzle hole 21 communicating with the ink pressure chamber 14; and a protection film 60 covering an upper surface 20T of the nozzle plate 20 spaced apart from the piezoelectric member 13, an inner wall 211 of the nozzle hole 21, an adhesion portion AP which is coupled to a lower surface 20B of the nozzle plate 20 in contact with the upper surface 13T of the piezoelectric member 13 and in which the piezoelectric member 13 adhesively bonded to the nozzle plate 20, and the electrode 16. The protection film 60 is locally thin at least around the nozzle hole 21 on the upper surface 20T of the nozzle plate 20.

Description

  Embodiments described herein relate generally to an inkjet head.

  In recent years, in an inkjet head, it is necessary to protect electrodes and the like from various inks in order to eject various inks such as conductive inks. Also, when ejecting special inks such as solvent-based inks, there is a problem that the adhesive that adheres the nozzle plate and the piezoelectric member is eroded by the ink, and it is necessary to protect the parts with poor ink resistance. .

  In response to such a demand, a technique for coating an electrode, a nozzle plate, and the like with a protective film formed of a polymer material has been studied. However, when the growth variation of the protective film occurs at the edge portion of the nozzle hole formed in the nozzle plate, there may be a problem that the ink ejection performance also varies.

  If the protective film grows abnormally at the edge of the nozzle hole, the ink droplet may be affected by the abnormal growth point when ink is ejected, and the print quality may be deteriorated. For example, when the ejection direction of the ink droplet is tilted, the dot position on the medium formed by the ink droplet may be displaced. Also, when the main ink droplet to be ejected has a tail and a minute ink droplet (satellite) has been generated, the satellite flies in a different direction from the main ink droplet and is formed by the main ink droplet In addition to the main dots that have been formed, fine dots formed by fine ink droplets may be printed on the medium.

Japanese Patent Laid-Open No. 2003-266691

  An object of the present embodiment is to provide an ink jet head capable of suppressing a decrease in print quality.

According to this embodiment,
A piezoelectric member that forms an ink pressure chamber; an electrode disposed on a side surface of the piezoelectric member that faces the ink pressure chamber; and an ink pressure that is adhered to an upper surface of the piezoelectric member on an opening side of the ink pressure chamber. A nozzle plate having a nozzle hole communicating with the chamber; an upper surface of the nozzle plate spaced from the piezoelectric member; an inner wall of the nozzle hole; and a lower surface of the nozzle plate in contact with the upper surface of the piezoelectric member. And a protective film covering the electrode, and at least the periphery of the nozzle hole is exposed from the protective film on the upper surface of the nozzle plate. An inkjet head is provided.

FIG. 1 is an exploded perspective view schematically showing the configuration of the ink jet head in the present embodiment. FIG. 2 is a cross-sectional view schematically showing a structure of a first configuration example including a main part and a nozzle plate constituting the ink jet head shown in FIG. FIG. 3 is a cross-sectional view schematically showing a structure of a second configuration example including a main part and a nozzle plate constituting the ink jet head shown in FIG. FIG. 4 is a cross-sectional view schematically showing a structure of a third configuration example including a main part and a nozzle plate constituting the ink jet head shown in FIG. FIG. 5 is a cross-sectional view schematically showing a structure of a fourth configuration example including a main part and a nozzle plate constituting the ink jet head shown in FIG. FIG. 6 is a cross-sectional view schematically showing the shape of the nozzle hole in which the nozzle plate of each configuration example shown in FIGS. 2 to 5 is formed. FIG. 7 is a cross-sectional view schematically showing a part of the manufacturing process of the ink jet head of the present embodiment. FIG. 8 is a diagram schematically showing the configuration of a vapor deposition polymerization apparatus for forming a protective film in the inkjet head of this embodiment. FIG. 9 is a cross-sectional view schematically showing a part of the manufacturing process of the ink jet head of the present embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to components that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is an exploded perspective view schematically showing the configuration of an inkjet head 1 in the present embodiment.

  That is, the inkjet head 1 includes a main part 10, a nozzle plate 20, a mask plate 30, and a holder 40. The inkjet head 1 has a substantially rectangular parallelepiped shape with the first direction X as a longitudinal direction. In the following description, a direction substantially orthogonal to the first direction X is referred to as a second direction Y, and a direction orthogonal to the XY plane is referred to as a third direction Z. The ink droplet ejection direction is the third direction Z.

  The main part 10 includes an insulating substrate 11, a frame body 12, a piezoelectric member 13, and the like.

  The insulating substrate 11 is made of ceramics such as alumina, for example, and is formed in a substantially rectangular plate shape extending along the first direction X. The insulating substrate 11 has an upper surface 11T on the side facing the nozzle plate 20 and a lower surface 11B on the side facing the holder 40. Such an insulating substrate 11 has an ink supply port 11in and an ink discharge port 11out. The ink supply port 11in and the ink discharge port 11out penetrate from the upper surface 11T to the lower surface 11B.

  The frame body 12 is made of metal, for example, and is formed in a rectangular frame shape. The frame body 12 is disposed on the upper surface 11T of the insulating substrate 11. The piezoelectric member 13 is made of, for example, PZT (lead zirconate titanate), and is disposed on the inner surface surrounded by the frame body 12 on the upper surface 11T of the insulating substrate 11. Each piezoelectric member 13 extends along a second direction Y substantially perpendicular to the first direction X. These piezoelectric members 13 are arranged along the first direction X. Between the pair of piezoelectric members 13 arranged along the first direction X, an ink pressure chamber 14 extending along the second direction Y is formed in a slit shape.

  In the illustrated example, two rows of piezoelectric members 13 arranged along the first direction X are formed. The plurality of ink supply ports 11in are arranged along the first direction X in the substantially central portion of the insulating substrate 11, that is, between the two rows of piezoelectric members 13. The plurality of ink discharge ports 11out are arranged along the first direction X in the peripheral portion of the insulating substrate 11, that is, between the piezoelectric member 13 and the frame body 12. With such a configuration, ink is supplied from each of the ink supply ports 11in toward the ink pressure chamber 14, and the ink that has passed through the ink pressure chamber 14 is discharged from each of the ink discharge ports 11out.

  The nozzle plate 20 is made of, for example, a resin such as polyimide, or a metal having heat resistance such as a nickel alloy or stainless steel, and is formed in a substantially rectangular plate shape extending along the first direction X. . The nozzle plate 20 is disposed above the main portion 10 along the third direction Z. The nozzle plate 20 has an upper surface 20T on the side facing the mask plate 30 and a lower surface 20B on the side facing the main portion 10. The lower surface 20B of the nozzle plate 20 is bonded to the frame body 12 and the piezoelectric member 13 with an adhesive (not shown).

  Such a nozzle plate 20 has a nozzle hole 21. Each nozzle hole 21 is formed to face the ink pressure chamber 14 and communicates with the ink pressure chamber 14. The plurality of nozzle holes 21 are arranged substantially along the first direction X, and form nozzle rows 211 and 212. In the illustrated example, two nozzle rows 211 and 212 are formed on the nozzle plate 20, but the nozzle row may be one row or three or more rows. Strictly speaking, the adjacent nozzle holes 21 may not be formed on the same straight line along the first direction X, but detailed description thereof is omitted here.

  The mask plate 30 is made of metal, for example, and is formed in a frame shape surrounding the nozzle plate 20. The mask plate 30 is disposed above the main part 10 along the third direction Z. The mask plate 30 has a quadrangular opening 30 </ b> H substantially equal to the outer diameter of the nozzle plate 20. The mask plate 30 and the frame 12 are bonded with an adhesive (not shown).

  The holder 40 is disposed below the main part 10 along the third direction Z. The holder 40 includes an ink introduction path 41 for introducing ink toward the ink supply port 11in, and an ink collection path 42 for collecting ink discharged from the ink discharge port 11out. Connected to the ink introduction path 41 is an introduction pipe 51 for introducing ink from an ink tank (not shown). A recovery pipe 52 for recovering ink to the ink tank is connected to the ink recovery path 42. The holder 40 has an upper surface 40T on the side facing the main portion 10. The upper surface 40T of the holder 40 and the lower surface 11B of the insulating substrate 11 are bonded with an adhesive (not shown).

  Examples of the adhesive that bonds the holder 40 and the insulating substrate 11, the adhesive that bonds the nozzle plate 20, the frame 12, and the piezoelectric member 13, and the adhesive that bonds the mask plate 30 and the frame 12 include, for example, A thermosetting resin such as an epoxy resin is applicable.

  FIG. 2 is a cross-sectional view schematically showing the structure of the first configuration example including the main part 10 and the nozzle plate 20 constituting the inkjet head 1 shown in FIG.

  That is, the piezoelectric members 13 are arranged at a predetermined interval on the upper surface 11T of the insulating substrate 11. Although detailed description is omitted, the piezoelectric member 13 is formed by stacking, for example, two piezoelectric members whose polarization directions are opposite to each other in the third direction Z. Such a piezoelectric member 13 has an upper surface 13T and a side surface 13S substantially perpendicular to the upper surface 11T of the insulating substrate 11.

  The ink pressure chamber 14 is formed between the piezoelectric members 13 adjacent to each other. In other words, the piezoelectric member 13 is disposed across the ink pressure chamber 14.

  The electrode 16 is disposed on each side surface 13S of the piezoelectric member 13. That is, the piezoelectric member 13 is sandwiched between the two electrodes 16. The electrode 16 is also disposed on the upper surface of the insulating substrate 11 located between the adjacent piezoelectric members 13. Such an electrode 16 is formed by, for example, nickel plating or copper plating.

  The nozzle plate 20 is bonded to the piezoelectric member 13. More specifically, the upper surface 13T of the piezoelectric member 13 and the lower surface 20B of the nozzle plate 20 are bonded with an adhesive. A nozzle hole 21 formed in the nozzle plate 20 communicates with the ink pressure chamber 14. The center of the nozzle hole 21 is located approximately in the middle between the adjacent piezoelectric members 13.

  In such a configuration, when a voltage having a reverse polarity is applied to each electrode 16 sandwiching the piezoelectric member 13, the piezoelectric member 13 is deformed and the volume of the ink pressure chamber 14 is changed (that is, the volume is expanded). Or shrink the volume). As the volume of the ink pressure chamber 14 changes, the ink introduced into the ink pressure chamber 14 is ejected from the nozzle hole 21.

  By the way, in the present embodiment, the inkjet head 1 includes a protective film 60 that covers the surface of the nozzle plate 20, the adhesive portion AP between the piezoelectric member 13 and the nozzle plate 20, and the electrode 16. The surface of the nozzle plate 20 includes the upper surface 20T, the lower surface 20B, and the inner wall 21I of the nozzle hole 21. The inner surface of the ink pressure chamber 14 is uniformly covered with the protective film 60.

  Such a protective film 60 is electrically insulating, and is formed using an organic material such as polyimide or parylene (polyparaxylylene). The protective film 60 is formed by a dry method such as a vapor deposition polymerization method.

  Here, the vapor deposition polymerization method means that a plurality of kinds of raw material monomers evaporated and activated by thermal energy are attached to the surface of a processing object for the purpose of forming the protective film 60, and the surface of the processing object In this polymerization method, a protective film 60 made of an organic polymer film is formed on the surface of the object to be processed by causing a polymerization reaction.

  With respect to such a protective film 60, at least a part of the protective film 60 is missing on the upper surface 20 </ b> T of the nozzle plate 20 at least around the nozzle hole 21. In the illustrated example, a recess 60 </ b> C is formed in the protective film 60 around the nozzle hole 21. More specifically, the thickness of the protective film 60 covering the upper surface 20T of the nozzle plate 20 is locally thin around the nozzle holes 21.

  For example, the protective film 60 is generally formed to have a first film thickness T1 (for example, about 5 μm), but the second film thickness T2 of the protective film 60 around the nozzle hole 21 is, for example, the adhesion portion AP. It is thinner than the first film thickness T1 of the protective film 60 immediately above. Such a region of the second film thickness T2, that is, the recess 60C is formed in a ring shape surrounding the nozzle hole 21, for example. Regarding the protective film 60, the region having the second film thickness T <b> 2 is connected to the region covering the inner wall 21 </ b> I of the nozzle hole 21. Here, the first film thickness T1 and the second film thickness T2 are lengths along the third direction Z.

  Such a first configuration example is applied to both the case where the nozzle plate 20 is made of resin and the case where it is made of metal.

  FIG. 3 is a cross-sectional view schematically showing the structure of the second configuration example including the main part 10 and the nozzle plate 20 constituting the inkjet head 1 shown in FIG.

  The second configuration example shown here is different from the first configuration example in that the periphery of the nozzle hole 21 is exposed from the protective film 60 on the upper surface 20T of the nozzle plate 20. That is, the second film thickness T2 of the protective film 60 around the nozzle hole 21 is zero with respect to the first film thickness T1 of the protective film 60 immediately above the adhesive portion AP. That is, around the nozzle hole 21, the protective film 60 is completely removed up to the upper surface 20T, and a step corresponding to the first film thickness T1 is formed. The region exposed from the protective film 60 is formed in, for example, a ring shape surrounding the nozzle hole 21. In addition, since it is the same as that of the 1st structural example about others, description is abbreviate | omitted.

  Such a second configuration example is applied to both the case where the nozzle plate 20 is made of resin and the case of being made of metal.

  FIG. 4 is a cross-sectional view schematically showing the structure of a third configuration example including the main part 10 and the nozzle plate 20 constituting the inkjet head 1 shown in FIG.

  The third configuration example shown here is different from the second configuration example in that the entire surface including the periphery of the nozzle hole 21 is exposed from the protective film 60 on the upper surface 20T of the nozzle plate 20. . That is, in the third configuration example, the protective film 60 is not formed on the upper surface 20T of the nozzle plate 20. In addition, since it is the same as that of the 1st structural example about others, description is abbreviate | omitted.

  Such a third configuration example is applied to both the case where the nozzle plate 20 is made of resin and the case where it is made of metal.

  FIG. 5 is a cross-sectional view schematically showing a structure of a fourth configuration example including the main part 10 and the nozzle plate 20 constituting the inkjet head 1 shown in FIG.

  The fourth configuration example shown here is different from the second configuration example in that a recess 20C is formed in the nozzle plate 20 exposed from the protective film 60. The depth d of the recess 20C from the upper surface 20T is within 10% of the thickness D of the nozzle plate 20 or within 5 μm. Such a recess 20 </ b> C is formed in a ring shape surrounding the nozzle hole 21, for example. The depth d and the thickness D here are lengths along the third direction Z. In addition, since it is the same as that of the 1st structural example about others, description is abbreviate | omitted.

  Such a fourth configuration example is applied particularly when the nozzle plate 20 is made of resin.

  Here, an example of the cross-sectional shape of the nozzle hole 21 formed in the nozzle plate 20 will be described.

  FIG. 6 is a cross-sectional view schematically showing the shape of the nozzle hole 21 in which the nozzle plate 20 of each configuration example shown in FIGS. 2 to 5 is formed.

  That is, the nozzle hole 21 has a spelled cross-sectional shape having a minimum diameter φ between the upper surface 20T and the lower surface 20B of the nozzle plate 20. That is, the inner wall 21 </ b> I of the nozzle hole 21 forms a reverse tapered portion 21 </ b> A on the upper surface 20 </ b> T side of the nozzle plate 20 and a forward tapered portion 21 </ b> B on the lower surface 20 </ b> B side of the nozzle plate 20.

  In addition, although not shown in figure, the nozzle hole 21 is circular in the XY plane, and the part used as the minimum diameter is also circular. The distance L along the third direction Z from the upper surface 20T to the position having the smallest diameter is about 10% of the thickness D of the nozzle plate 20. As an example of the dimensions of each part, the thickness D is 50 μm, the distance L is 5 μm, and the minimum diameter φ is 30 μm.

  In the fourth configuration example shown in FIG. 5, even when the depression 20C is formed on the upper surface 20T side of the nozzle plate 20, the depth d of the depression 20C is within 10% of the thickness D of the nozzle plate 20, or If it is within 5 μm, the minimum diameter φ of the nozzle hole 21 is maintained. For this reason, the occurrence of a problem that the minimum diameter is different for each nozzle hole 21 is prevented.

  The nozzle hole 21 having such a shape is often formed when the nozzle plate 20 is made of resin, but can also be formed when the nozzle plate 20 is made of metal.

  As another cross-sectional shape of the nozzle hole 21, although not shown, a cylindrical portion having a substantially uniform inner diameter is formed on the upper surface 20T side of the nozzle plate 20, and a forward tapered portion is formed on the lower surface 20B side of the nozzle plate 20. The formed shape is also applicable. Even in this case, in the configuration in which the recess 20C is formed on the upper surface 20T side of the nozzle plate 20 as in the fourth configuration example, the depth of the recess 20C may be within the length along the axial direction of the cylindrical portion. For example, the inner diameter of the cylindrical portion becomes the minimum diameter φ of the nozzle hole 21, and this minimum diameter is maintained.

  Next, the manufacturing method of the inkjet head 1 in this embodiment is demonstrated. Here, description will be made with reference to a cross-sectional view in the XZ plane.

  FIG. 7 is a cross-sectional view schematically showing a part of the manufacturing process of the inkjet head 1 of the present embodiment.

  First, as shown in FIG. 7A, after forming the piezoelectric member 13 on the upper surface 11T of the insulating substrate 11, the electrode 16 is formed on the side surface 13S of the piezoelectric member 13 and the upper surface 11T of the insulating substrate 11. . In the illustrated stage, the electrode 16 is not disposed on the upper surface 13 </ b> T of the piezoelectric member 13.

  Then, as shown in FIG. 7B, the piezoelectric member 13 and the nozzle plate 20 are bonded with an adhesive. The adhesive is, for example, an epoxy resin, and is applied to the upper surface 13T of the piezoelectric member 13. The nozzle plate 20 is made of polyimide, for example. In the illustrated example, no nozzle hole is formed in the nozzle plate 20 at the time of bonding, but the nozzle plate 20 in which the nozzle hole 21 is formed in advance may be bonded. In particular, when the nozzle plate 20 is made of metal, it is desirable that the nozzle holes 21 be formed in advance before bonding. As a method for forming the nozzle hole 21 in the nozzle plate 20, for example, a laser processing for irradiating laser light, a press processing, an electroforming, or the like can be applied.

  Here, a method for forming a nozzle hole 21 having a cross-sectional shape as shown in FIG. 6 by laser processing will be described.

  That is, the protective film 22 is affixed to the upper surface 20T of the nozzle plate 20. The protective film 22 is, for example, a polyethylene terephthalate (PET) film coated with an adhesive material. As an example of the thickness, the nozzle plate 20 has a thickness of about 50 μm, and the protective film 22 has a thickness of about 15 μm.

  The nozzle plate 20 to which such a protective film 22 is attached is placed on the upper surface 13T of the piezoelectric member 13 to which the adhesive is applied, with the lower surface 20B facing the piezoelectric member 13, and the adhesive is cured. By performing the above, the piezoelectric member 13 is bonded. At this time, since nozzle holes are not formed in the nozzle plate 20, precise alignment is not necessary.

  Subsequently, as shown in FIG. 7C, the laser beam LL shaped by the optical system OP of the hole processing device not described in detail is irradiated toward the nozzle plate 20 to form the nozzle hole 21. The laser beam LL is light having a wavelength in the ultraviolet region emitted from an excimer laser device, a YAG laser device, or the like, and is capable of removing the material of the nozzle plate 20. When such a laser beam LL passes through the telecentric optical system OP of the hole drilling device, the diameter gradually decreases to the condensing surface F in a cross section perpendicular to the traveling direction, and the diameter gradually increases from the condensing surface F. It is shaped so as to have a constricted beam shape.

  The reverse tapered portion 21A and the forward tapered portion 21B are formed by processing the condensing surface F of the laser beam LL having a constricted beam shape in this manner while being positioned inside the cross section of the nozzle plate 20. Then, the protective film 22 is peeled from the upper surface 20T of the nozzle plate 20.

  Thereby, as shown in FIG. 7D, the nozzle plate 21 is formed with a nozzle hole 21 having a hook-shaped cross-sectional shape. The nozzle hole 21 thus formed communicates with the ink pressure chamber 14.

  Subsequently, a protective film 60 is formed to cover the surface of the nozzle plate 20, the adhesive portion AP between the piezoelectric member 13 and the nozzle plate 20, and the electrode 16.

  FIG. 8 is a diagram schematically showing the configuration of the vapor deposition polymerization apparatus 100 for forming the protective film 60 in the inkjet head 1 of the present embodiment. Below, the schematic structure of the vapor deposition polymerization apparatus 100 and the work procedure of vapor deposition polymerization are demonstrated with reference to FIG.

  The vapor deposition polymerization apparatus 100 holds a processing object (in this embodiment, the nozzle plate 20 in which the nozzle holes 21 are formed and the piezoelectric member 13 are bonded) A intended for film formation by the vapor deposition polymerization method. A stage 118 is provided with a chamber 119 provided therein. The stage 118 is provided with a temperature adjustment mechanism (not shown) for adjusting the temperature of the processing object A.

  In the chamber 119, an indoor temperature control mechanism (not shown) for controlling the temperature in the chamber 119 is provided. Although not particularly illustrated, the chamber 119 is provided with a decompression mechanism for decompressing the inside of the chamber 119. This decompression mechanism may be a mechanism that forcibly exhausts the air in the chamber 119 to the outside of the chamber 119 by a fan or the like, for example.

  A mixing bowl 120 is provided above the chamber 119. The chamber 119 and the mixing bowl 120 are communicated with each other through a shower plate 121 in which a plurality of holes are formed.

  In addition, the vapor deposition polymerization apparatus 100 includes a plurality of evaporating soots 122 that hold raw material monomers to be attached to the processing object A. Although not particularly illustrated, each evaporating vessel 122 is provided with a heating mechanism for heating the raw material monomer. Further, each evaporating soot 122 is provided with a monomer introduction pipe 123 that allows each evaporating soot 122 and the mixing soot 120 to communicate with each other. Each monomer introduction pipe 123 is provided with a valve 124 for controlling the opening of each monomer introduction pipe 123. The monomer introduction tube 123 is closed by a valve 124 except when vapor deposition polymerization is performed.

  In forming the protective film 60, first, the processing object A intended for film formation by vapor deposition polymerization is attached to the stage 118. Note that masking is performed in advance on a portion of the processing object A that does not require the formation of the protective film 60 (for example, an electrode terminal).

  Next, the inside of the evaporating basket 122 is heated by a heating mechanism. The heated raw material monomer evaporates as a gas. When the raw material monomer is sufficiently vaporized, the valve 124 is opened and the monomer introduction pipe 123 is opened. Thereby, the vaporized raw material monomer is introduced into the mixing vessel 120 through the monomer introduction pipe 123. In the mixing tank 120, a mixed monomer in which various monomers are uniformly mixed is generated.

  In addition, the inside of the chamber 119 is decompressed by a decompression mechanism. The mixed monomer is introduced into the chamber 119 through the shower plate 121 due to a pressure difference between the mixing rod 120 and the chamber 119.

  The mixed monomer introduced into the chamber 119 adheres to a portion where the protective film 60 on the processing object A is desired to be formed. By controlling the processing object A and the temperature in the chamber 119, the raw material monomer attached to the processing object A starts to be polymerized. As a result, the target protective film 60 is formed on the portion (the surface of the nozzle plate 20, the adhesive portion AP between the piezoelectric member 13 and the nozzle plate 20, and the electrode 16) where the protective film 60 on the processing object A is to be formed. 60 is deposited.

  In such a vapor deposition polymerization method, a substance to be deposited is attached to the processing target A in a monomer unit and polymerized on the processing target A. Therefore, monomer molecules are formed even on the processing target A having a complicated shape. Since it goes around well, it is possible to form a film evenly on a fine part without being influenced by the shape of the processing object A. In addition, since the vapor deposition polymerization method has good adhesion and excellent throwing power, the base film treatment for the processing object A is performed by forming the protective film 60 using such a vapor deposition polymerization method. This can be made unnecessary.

  FIG. 9 is a cross-sectional view schematically showing a part of the manufacturing process of the inkjet head 1 of the present embodiment.

  As shown in FIG. 9A, when the protective film 60 is formed by the vapor deposition polymerization method, the surface of the nozzle plate 20 (that is, the upper surface 20T, the lower surface 20B, the inner wall 21I of the nozzle 21), the piezoelectric member 13 and the like. The adhesion part AP between the nozzle plate 20 and the electrode 16 are covered with a protective film 60. At this time, as shown in the figure, the protrusion 61 of the protective film 60 may be formed due to abnormal growth locally.

  Then, as shown in FIG. 9B, the laser beam LL is irradiated toward the nozzle plate 20, and at least around the nozzle hole 21, at least one of the protective films 60 covering the upper surface 20 </ b> T of the nozzle plate 20. Remove the part. Thereby, even if the protrusion 61 is formed on the protective film 60, the protrusion 61 is almost removed by the irradiation with the laser beam LL.

  The laser beam LL applied here is light having a wavelength in the ultraviolet region emitted from an excimer laser device, a YAG laser device, or the like, and is capable of removing an organic material that is a material of the protective film 60. Yes. At this time, the laser beam LL may be selectively irradiated toward the periphery of the nozzle hole 21, or the laser beam LL having a large diameter may be irradiated toward substantially the entire upper surface 20T of the nozzle plate 20. The entire upper surface 20T of the nozzle plate 20 may be scanned while irradiating the laser beam LL having a small diameter.

  The removal amount for removing the protective film 60 (or the depth of digging of the protective film 60 along the third direction Z) is adjusted by controlling the irradiation amount of the laser light LL to the protective film 60. The irradiation amount of the laser beam LL is controlled by the energy density per shot, the irradiation time, the number of shots, and the like.

  When the nozzle plate 20 is made of resin, if the irradiation amount of the laser beam LL is excessive, the protective film 60 on the upper surface 20T of the nozzle plate 20 is not removed, but the upper surface 20T to the lower surface 20B of the nozzle plate 20 is removed. It penetrates. For this reason, when the nozzle plate 20 is made of resin, the irradiation amount of the laser light LL is set so as not to penetrate from the upper surface 20T to the lower surface 20B of the nozzle plate 20.

  On the other hand, when the nozzle plate 20 is made of metal having sufficient heat resistance (or laser resistance) against the heat of the laser beam LL, the nozzle plate 20 itself even if the amount of laser beam irradiation is somewhat excessive. Is hardly removed, and the processing stops at the upper surface 20T of the nozzle plate 20. For this reason, when the nozzle plate 20 is made of metal, a necessary amount of the protective film 60 can be formed without strictly controlling the irradiation amount of the laser light LL, compared to the case where the nozzle plate 20 is made of resin. It can be removed.

  Regardless of the material of the nozzle plate 20, the irradiation amount of the laser light LL is set to the first irradiation amount necessary for removing the protective film 60 formed on the upper surface 20T of the nozzle plate 20 by the first film thickness T1. In this case, the protective film 60 is selectively removed by selectively irradiating the laser beam LL toward the periphery of the nozzle hole 21, and the nozzle plate 20 can be removed as in the second configuration example shown in FIG. 3. Of the upper surface 20T, the periphery of the nozzle hole 21 is exposed from the protective film 60.

  Similarly, regardless of the material of the nozzle plate 20, when the irradiation amount of the laser beam LL is set to the first irradiation amount, the upper surface 20T is applied to the entire upper surface 20T of the nozzle plate 20 by irradiating the laser beam LL with the laser beam LL. The covering protective film 60 is removed, and the entire upper surface 20T of the nozzle plate 20 is exposed from the protective film 60 as in the third configuration example shown in FIG.

  Regardless of the material of the nozzle plate 20, when the irradiation amount of the laser light LL is set smaller than the first irradiation amount, by selectively irradiating the laser light LL toward the periphery of the nozzle hole 21, The protective film 60 is selectively removed, and a recess 60 </ b> C is formed around the nozzle hole 21 in the protective film 60 covering the upper surface 20 </ b> T of the nozzle plate 20 as in the first configuration example shown in FIG. 2.

  When the nozzle plate 20 is made of resin and the irradiation amount of the laser beam LL is set larger than the first irradiation amount, the laser beam LL is selectively irradiated toward the periphery of the nozzle hole 21. The protective film 60 is selectively removed and a part of the upper surface 20T side of the nozzle plate 20 is also removed, and a recess 20C is formed on the upper surface 20T side of the nozzle plate 20 as in the fourth configuration example shown in FIG. It is formed.

  As described above, in the ink jet head 1 of the present embodiment, the electrode 16 and the bonding portion AP between the piezoelectric member 13 and the nozzle plate 20 formed in the ink pressure chamber 14 are covered with the protective film 60. For this reason, in the inkjet head 1 that discharges various inks, it is possible to protect the inferior ink resistance portions such as the electrode 16 and the adhesive that bonds the piezoelectric member 13 and the nozzle plate 20 with the protective film 60. Become.

  In other words, since the electrode 16 and the adhesive do not come into contact with ink, there is no need to consider ink resistance, and the number of selectable materials can be increased. In addition, it is not necessary to consider the influence on the electrode 16 and the adhesive, and various inks can be applied.

  In particular, as an adhesive for bonding the metal nozzle plate 20 in which the nozzle holes 21 are formed in advance to the piezoelectric member 13, a thermosetting type tends to be avoided. This is because misalignment is likely to occur due to thermal expansion of the nozzle plate 20 during thermosetting. For this reason, materials that can be selected as the adhesive are limited. Among these adhesives, considering ink resistance, further selectable materials are limited, but in this embodiment, the adhesive is protected by the protective film 60 and does not touch the ink. It is possible to relax restrictions on materials that can be selected as the adhesive.

  In addition, at least a part of the protective film 60 covering the upper surface 20T of the nozzle plate 20 is missing around the nozzle hole 21. This is because at least a part of the protective film 60 is removed by irradiating the laser beam LL after the process of forming the protective film 60. For this reason, in the process of forming the protective film 60, even if abnormal growth occurs in a part of the protective film 60 at the edge portion of the nozzle hole 21 and the protrusion 61 is formed, the process of removing the protective film 60 Thus, the protrusion 61 can also be removed.

  Therefore, the influence of abnormal growth of the protective film 60 can be reduced. As a result, it is possible to suppress the occurrence of inclination in the ejection direction of the ink ejected from the nozzle holes 21 and the occurrence of printing defects due to the occurrence of satellites, and it is possible to suppress the degradation of print quality.

  Although it depends on the size of the abnormally grown protrusion 61, it may not be completely removed by irradiation with the laser beam LL. Even in such a case, since the protrusion 61 becomes smooth and leveled, it is possible to reduce the influence when ink is ejected.

  In the first configuration example shown in FIG. 2, a recess 60 </ b> C is formed around the nozzle hole 21 in the protective film 60 covering the upper surface 20 </ b> T of the nozzle plate 20. In such a first configuration example, the protrusion 61 of the protective film 60 that has abnormally grown around the nozzle hole 21 in the process of forming the recess 60C can be removed. For this reason, the effect which suppresses a printing quality fall is acquired. Further, by limiting the region to be irradiated with the laser beam LL around the nozzle hole 21, the number of steps in the laser beam irradiation step can be reduced.

  In the second configuration example shown in FIG. 3 and the third configuration example shown in FIG. 4, at least the periphery of the nozzle hole 21 in the upper surface 20 </ b> T of the nozzle plate 20 is exposed from the protective film 60. In such a second configuration example, the protrusion 61 of the protective film 60 that has abnormally grown around the nozzle hole 21 in the process of removing the protective film 60 can be removed. In the second configuration example, as compared with the first configuration example, the removal rate of the protrusions 61 is increased, so that the influence of the protrusions 61 can be further reduced, and an effect of suppressing the print quality deterioration can be obtained. Further, in the third configuration example in which the region to be irradiated with the laser light LL is limited to the periphery of the nozzle hole 21, the region to be irradiated with the laser light LL is compared with the fourth configuration example in which the upper surface 20T of the nozzle plate 20 is substantially the whole. Thus, the number of processes in the laser light irradiation process can be reduced.

  In the fourth configuration example shown in FIG. 5, in addition to exposing the periphery of the nozzle hole 21 from the protective film 60, a recess 20 </ b> C is formed in the nozzle plate 20 exposed from the protective film 60. In such a fourth configuration example, the protrusion 61 of the protective film 60 that has abnormally grown around the nozzle hole 21 in the process of removing a part of the protective film 60 and the nozzle plate 20 can be removed. In the fourth configuration example, since the removal rate of the protrusions 61 is further increased as compared with the second and third configuration examples, the influence of the protrusions 61 can be further reduced, and the print quality deterioration is suppressed. An effect is obtained. Further, by limiting the region to be irradiated with the laser beam LL around the nozzle hole 21, the number of steps in the laser beam irradiation step can be reduced.

  As described above, according to the present embodiment, it is possible to provide an ink jet head capable of suppressing a decrease in print quality and a method for manufacturing the same.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit 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.

DESCRIPTION OF SYMBOLS 1 ... Inkjet head 10 ... Main part 11 ... Insulating substrate 11T ... Upper surface 13 ... Piezoelectric member 13T ... Upper surface 13S ... Side surface 14 ... Ink pressure chamber 16 ... Electrode 20 ... Nozzle plate 20T ... Upper surface 20B ... Lower surface 21 ... Nozzle hole 21I ... Inner wall 21A ... Reverse taper part 21B ... Forward taper part 60 ... Protective film 61 ... Projection AP ... Adhesion part 100 ... Deposition polymerization apparatus

Claims (3)

A piezoelectric member forming an ink pressure chamber;
An electrode disposed on a side surface of the piezoelectric member facing the ink pressure chamber;
A nozzle plate that is bonded to the upper surface of the piezoelectric member on the opening side of the ink pressure chamber and has a nozzle hole communicating with the ink pressure chamber;
An upper surface of the nozzle plate spaced from the piezoelectric member, an inner wall of the nozzle hole, and a lower surface of the nozzle plate contacting the upper surface of the piezoelectric member; an adhesive portion between the piezoelectric member and the nozzle plate; and A protective film covering the electrode,
The inkjet head according to claim 1, wherein at least the periphery of the nozzle hole is exposed from the protective film on the upper surface of the nozzle plate.   The inkjet head according to claim 1, wherein a recess is formed in the nozzle plate exposed from the protective film.   The inkjet head according to claim 2, wherein a depth of the recess is within 10% of a thickness of the nozzle plate.

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