JP6359367B2 - Inkjet head - Google Patents

Description

  Embodiments described herein relate generally to an inkjet head.

  A conventional piezoelectric drive type ink jet head is a PZT (lead zirconate titanate) substrate having an electrode formed on the inner surface of a groove forming an ink flow path and a head drive unit driven by applying a voltage to the electrode. And a nozzle plate provided with nozzles at positions corresponding to the grooves. After forming an epoxy adhesive on the nozzle plate, align the nozzle of the nozzle plate with the ink flow path and press the nozzle plate against the PZT substrate and the front surface of the plate that covers the ink flow path. Is attached.

  However, the nozzle plate is attached to the ink ejection surface of the smoothed laminated piezoelectric member using an adhesive via an organic protective film. For this reason, since the ink ejection surface of the laminated piezoelectric member is smooth, the nozzle plate is easily peeled off from the end portion of the ink ejection surface, and there is a problem that the ink ejection accuracy is lowered.

JP 2014-083694 A

  The problem to be solved by the present invention is to provide an ink jet head capable of preventing the nozzle plate attached to the ink ejection surface from peeling off.

  The ink jet head according to the embodiment includes a long laminated piezoelectric member attached to a bonded substrate with the polarization directions opposite to each other, and a groove serving as an ink flow path orthogonal to the longitudinal direction of the laminated piezoelectric member. A plurality of pressure chambers formed; an electrode formed in the pressure chamber; a frame member that surrounds the pressure chamber and attached to the substrate; and a nozzle that discharges the ink; A nozzle plate having the nozzle attached to the pressure chamber on the ink ejection surface and the frame member, and the laminated piezoelectric member has an ink ejection surface roughness of the pressure. With respect to the longitudinal direction of the chamber, the end side away from the nozzle was roughened from the portion where the nozzle was formed.

It is a perspective view which shows 1st Embodiment concerning an inkjet head. It is a perspective view which decomposes | disassembles and shows the principal part of an inkjet head. It is a front view of the principal part of FIG. 1 is a perspective view showing a state in which the main part is enlarged and partly cut away. It is sectional drawing along the Ia-Ib line | wire of FIG. 5 is an enlarged cross-sectional view showing the main part. It is sectional drawing along the IIa-IIb line | wire of FIG. It is a figure for demonstrating the formation area of the smooth surface part and rough surface part of an ink discharge surface. It is a top view of the principal part which shows 2nd Embodiment concerning an inkjet head.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

(First embodiment)
1 to 3 show a first embodiment of an inkjet head. FIG. 1 is a perspective view. FIG. 2 is an exploded perspective view showing a main part of the inkjet head 100. FIG. 3 is a front view of the main part of FIG.

  1 is a so-called side shooter type ink circulation type inkjet head. The ink jet head 100 includes an ink discharge unit 11, a pair of circuit modules 13, and a cover 12. The pair of circuit modules 13 are respectively attached to the ink ejection unit 11.

  The ink ejection unit 11 includes a manifold 21, a substrate 22, a frame member 23, and a nozzle plate 24. Further, the ink ejection unit 11 has an ink chamber 25 inside. The frame member 23 and the nozzle plate 24 are overlaid on the rectangular substrate 22. The ink chamber 25 is surrounded by the substrate 22, the frame member 23, and the nozzle plate 24, and is supplied with printing ink.

  As shown in FIG. 2, the manifold 21 has a pair of first surfaces 211, a pair of second surfaces 212, and a fitting portion 213. The pair of first surface 211 and second surface 212 are each formed flat. The second surface 212 is provided on the opposite side of the corresponding first surface 211. The flat fitting portion 213 is provided between the pair of first surfaces 211 and is recessed from the first surface 211 by the thickness of the substrate 22. The board 22 is fitted into the fitting portion 213.

  The substrate 22 has a plurality of ink supply ports 221 for supplying ink to the center in the longitudinal direction, and ink discharge ports 222 and 223 at left and right positions of the ink supply port 221 (see FIG. 3).

  The nozzle plate 24 is formed of a rectangular film made of polyimide, for example. The thickness of the nozzle plate 24 is, for example, 30 μm to 100 μm. The nozzle plate 24 has a plurality of nozzles 241 arranged so as to be substantially parallel to the longitudinal direction. The diameter of the nozzle 241 is, for example, 20 μm to 50 μm. The nozzle plate 24 is attached to the ink ejection surface 37 from which the ink is ejected on the upper surface of the laminated piezoelectric member 32 on which the frame member 23 and the piezoelectric member are laminated by an adhesive 63 (see FIG. 6). The nozzle plate 24 is disposed to face the substrate 22.

  As shown in FIG. 2, a pair of ink supply holes 26, a pair of ink discharge holes 27, and a pair of ink discharge holes 28 are formed in the fitting portion 213 of the manifold 21 in the longitudinal direction. An ink supply groove 29 is formed between the pair of ink supply holes 26. An ink discharge groove 30 is formed between the pair of ink discharge holes 27, and an ink discharge groove 31 is formed between the pair of ink discharge holes 28. The ink supply hole 26 is coupled to an ink supply path (not shown). The ink discharge grooves 30 and 31 are coupled to an ink discharge path (not shown).

  The ink supply port 221 and the ink supply groove 29 are formed at positions facing each other. Further, the ink discharge port 222 and the ink discharge groove 30 are formed at positions facing each other. The ink discharge port 223 and the ink discharge groove 31 are formed at positions facing each other. That is, when the substrate 22 is joined to the fitting portion 213, the ink supply port 221 and the ink supply groove 29 are in the form of communication holes. The ink discharge port 222 and the discharge groove 30 are in communication with each other, and the ink discharge port 223 and the ink discharge groove 31 are in the shape of a communication hole.

  The ink supply path and the ink discharge path are combined with an ink tank to constitute a circulation type ink jet head.

  The board | substrate 22 is formed in the rectangle with plate-shaped ceramics, such as an alumina, for example. The substrate 22 has a flat surface 224. When the substrate 22 is fitted into the fitting portion 213 of the manifold 21, the surface 224 is formed in the same plane as the first surface 211 of the manifold 21.

  FIG. 4 is a perspective view showing an enlarged main part of FIG. 1 and partially cut away. FIG. 5 is a cross-sectional view taken along line Ia-Ib in FIG. FIG. 6 is an enlarged cross-sectional view showing a main part of FIG.

  As shown in FIG. 4, a long pair of laminated piezoelectric members 32 and a plurality of wiring patterns 33 serving as a driving unit are attached to the surface 224 of the substrate 22. Each laminated piezoelectric member 32 is formed by bonding two piezoelectric plates 321 and 322 made of, for example, PZT so that their polarization directions are opposite to each other (see FIG. 6).

  The laminated piezoelectric member 32 has a trapezoidal cross section and is attached to the surface 224 of the substrate 22, and extends parallel to the longitudinal direction of the substrate 22. As shown in FIG. 5, one laminated piezoelectric member 32 is disposed between the ink supply port 221 and the ink discharge port 222. The other laminated piezoelectric member 32 is disposed between the ink supply port 221 and the ink discharge port 223.

  As shown in FIG. 6 in which the main part of FIG. 5 is enlarged, the laminated piezoelectric member 32 has a trapezoidal cross section to form a piezoelectric element oblique side 61. At this time, the surface of the lower substrate 22 of the piezoelectric element oblique side portion 61 is polished to form a concave smooth substrate polishing surface 62.

  A plurality of fine grooves extending in the direction (sub-scanning direction) intersecting the longitudinal direction (main scanning direction) from the opposite surface side attached to the substrate 22 are cut and formed in the laminated piezoelectric member 32, A plurality of elongated pressure chambers 34 arranged at equal intervals in the main scanning direction are formed. For example, the width of the pressure chamber 34 is about 80 μm to 100 μm and the depth is about 300 μm.

  As shown in FIG. 7 showing a cross section taken along the line IIa-IIb in FIG. 6, a plurality of pressure chambers 34 are formed in the laminated piezoelectric member 32, thereby partitioning the pressure chambers 34 adjacent in the main scanning direction. At the same time, a side wall 35 serving as a driving element is formed. The pressure chamber 34 and the side wall 35 are formed corresponding to the nozzle 241. That is, the pressure chambers 34 and the side walls 35 are formed at the same pitch as the nozzles 241.

  Further, an electrode 36 is provided on the surface of each side wall 35 of the laminated piezoelectric member 32 and the bottom of the pressure chamber 34 as shown in FIG. The electrode 36 is closely attached to the laminated piezoelectric member 32 in the pressure chamber 34. The electrode 36 is provided in close contact with the laminated piezoelectric member 32 in the pressure chamber 34. The electrode 36 is formed of, for example, a nickel thin film, but is not limited thereto, and may be formed of, for example, gold or copper. The thickness of the electrode 36 is, for example, 0.5 μm to 5 μm.

  The electrode 36 is electrically connected to the circuit module 13 (see FIG. 1) on which the driving IC 40 is mounted via the wiring pattern 33 formed on the piezoelectric element oblique side portion 61, the substrate polishing surface 62, and the substrate 22. Connection has been made. Further, an electrodeposition film 38 having a film thickness of, for example, about 10 μm is formed on the electrode 36 by an electrodeposition method and heated. The electrodeposition film 38 is excellent in adhesion to the electrode 36 and insulation characteristics.

  As shown in FIG. 5, the wiring pattern 33 and the flexible circuit board 41 are connected by thermocompression bonding, for example, by ACF (anisotropic conductive film). The wiring pattern 33 and the flexible circuit board 41 are not limited to ACF, but may be connected by other means such as ACP (anisotropic conductive paste), NCF (nonconductive film), and NCP (nonconductive paste). good.

  The driving IC 40 applies a voltage to the electrode 36 via the wiring pattern 33 based on a signal input from a control unit (not shown) of the inkjet printer 100. When a voltage is applied via the electrode 36, the laminated piezoelectric member 32 is deformed, and the volume of the pressure chamber 34 is expanded or reduced. The ink pressurized by the reduction is ejected from the nozzle 241 corresponding to the pressure chamber 34.

  In the inner region of the frame member 23, an organic protective film 39 is formed on the pressure chamber 34, the laminated piezoelectric member 32, the frame member 23, the electrodeposition film 38, and the substrate 22. The organic protective film 39 is cut outside the frame member 23 (see FIG. 6). The organic protective film 39 is insulative and is formed by, for example, a CVD (chemical vapor deposition) method, and the thickness thereof is, for example, 3 μm to 10 μm.

  The organic protective film 39 protects the electrode 36 from the ink supplied to the pressure chamber 34. The organic protective film 39 is formed of, for example, a paraxylylene polymer. Paraxylylene polymers are excellent in uniform coverage. The organic protective film 39 protects the electrode 36 from corrosive components in the aqueous ink.

  Specific examples of the paraxylene-based polymer include polychloroparaxylylene, polyparaxylylene, polydichloroparaxylylene, and the like. The organic protective film 39 is not limited to this, and may be formed of other insulating materials.

  As shown in FIG. 6, the ink discharge surface 37 of the laminated piezoelectric member 32 is formed with a smooth surface portion 37 a in which the surface roughness of the intermediate portion in the longitudinal direction of the pressure chamber 34 is smoothed. The ink ejection surfaces 37 at both ends of the smooth surface portion 37a are formed by rough surface portions 37b having a rough surface. The length of the ink ejection surface 37 is at most about 2 mm, for example.

  FIG. 8 is a diagram for explaining regions where the smooth surface portion 37a and the rough surface portion 37b are formed with respect to the nozzle 241 of the nozzle plate 24. FIG.

  The smooth surface portion 37a is formed as a smooth region 8A up to a position outside the nozzle 241 disposed on the inner side indicated by the straight lines L1 and L2. The rough surface portion 37b is formed as a rough region 8B outside the smooth surface portion 37a. Note that the roughness Ra of the smooth region 8A is, for example, 3 μm or less. The roughness Ra of the rough region 8B is, for example, 10 μm to 30 μm.

  The nozzle plate 24 is attached to the smooth surface portion 37 a, the rough surface portion 37 b of the laminated piezoelectric member 32, and the organic protective film 39 formed on the frame member 23 with an adhesive 63. The adhesive 63 on the rough surface portion 37b increases the adhesive area and improves the adhesive force as the surface is rough. The organic protective film 39 on the rough surface portion 37b is formed in a state along the shape of the rough surface portion 37b.

  As described above, the nozzle plate 24 having a thickness of micron order can be attached to the smooth surface portion 37a having a roughness Ra of 3 μm or less by the adhesive 63 without distortion. Thereby, the mounting accuracy of the nozzle plate 24 can be maintained, and a desired printing accuracy can be obtained.

  Further, since the nozzle plate 24 at the rough surface portion 37b has a roughness Ra of 10 μm to 30 μm, the area of the adhesive 63 is increased as compared with the smooth region 8A, and the adhesive force is improved. In the rough surface portion 37b, the adhesive force is improved by the increase in the bonding area of the adhesive 63, and the nozzle plate 24 can be prevented from coming off. Therefore, the nozzle plate 24 can reliably discharge ink from the nozzles 241 and can be reliably attached.

  In this embodiment, the roughness of the upper surface of the laminated piezoelectric member is roughened at a position far from the nozzles of the nozzle plate, so that ink can be reliably discharged from the nozzles, and the nozzle plate can be prevented from coming off. .

(Second Embodiment)
FIG. 9 is a top view of a main part showing a second embodiment of the inkjet head.

  In this embodiment, the rough surface 37b is a first rough surface region 8B1 closer to the smooth region 8A as the first rough surface portion 37b1, and the second rough surface region 8B2 far from the smooth region 8A is the second rough surface portion 37b2. It was.

  And the roughness of the 2nd rough surface part 37b2 was made rougher than the roughness of the 1st rough surface part 37b1. The roughness a of the second rough surface portion 37b2 is, for example, 10 μm to 30 μm, similarly to the rough surface portion 37b of the first embodiment. The roughness a of the first rough surface portion 37b1 is, for example, between the smooth surface portion 37a having a roughness a of 3 μm or less and the second rough surface portion 37b2 having a roughness a of 10 μm to 30 μm.

  Thus, the roughness of the first rough surface portion 37b1 is formed with a roughness close to the smooth surface portion 37a. For this reason, the shape of the nozzle plate 24 attached to the position of the first rough surface portion 37b1 is not easily affected by deformation due to the roughness of the first rough surface portion 37b1. Further, since the roughness of the first rough surface portion 37b1 is slightly rougher than that of the smooth surface portion 37a, the certainty of adhesion by the adhesive 63 can be improved.

  Furthermore, in the first embodiment, the smooth surface portion 37 a of the smooth surface portion 37 a is relatively wide in order for the attached nozzle plate 24 to suppress deformation due to the roughness of the ink discharge surface 37. On the other hand, in this embodiment, the first rough surface portion 37b1 whose roughness is close to the smooth surface portion 37a is formed adjacent to the smooth surface portion 37a. For this reason, the smooth surface portion 37a can be attached to the smooth surface portion 37a without deforming the nozzle plate 24 without widening the smooth region 8A. In addition, since the first rough surface region 8B1 and the second rough surface region 8B2 can be widened, the adhesion effect of the adhesive 63 to the nozzle plate 24 can be improved.

  In this embodiment, the roughness of the upper surface of the laminated piezoelectric member is made slightly rougher to a position close to the vicinity of the nozzle by gradually increasing the position far from the nozzle of the nozzle plate. As a result, the ink can be reliably discharged from the nozzles, and the nozzle plate can be prevented from coming off more reliably.

  Although several embodiments have been described, these embodiments have been 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, combinations, 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.

23 Frame member 24 Nozzle plate 32 Multilayer piezoelectric member 34 Pressure chamber 38 Electrodeposition film

Claims (4)

A long laminated piezoelectric member attached to the bonded substrate with the polarization directions of each other reversed, and
A plurality of pressure chambers formed by grooves perpendicular to the longitudinal direction of the laminated piezoelectric member and serving as ink flow paths;
An electrode formed in the pressure chamber;
A frame member surrounding the pressure chamber and mounted on the substrate;
A nozzle plate in which nozzles for discharging the ink are formed, and the nozzles are attached on the ink discharge surface of the laminated piezoelectric member and the frame member in correspondence with the pressure chambers;
With
The laminated piezoelectric member is an ink jet head in which the roughness of the ink discharge surface is made rougher on the end side away from the nozzle than the portion where the nozzle is formed in the longitudinal direction of the pressure chamber. The central portion where the nozzle is formed is a smooth surface portion, the end portion away from the nozzle is a rough surface portion,
The inkjet head according to claim 1, wherein the smooth surface portion is formed up to a position outside the nozzle position arranged on a straight line.   The inkjet head according to claim 2, wherein the rough surface portion has a smaller roughness on the smooth surface side and a larger opposite side. The pressure chamber and covers a portion of the inside of the frame member including the ink ejection surface, he said with a protective film formed along the roughness of the rough surface, according to claim 2 or 3 jet head according.

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