JP2013103364A - Inkjet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet head capable of preventing the occurrence of a crosstalk at ejection of an ink droplet.SOLUTION: The inkjet head includes a plurality of drive columns arranged in parallel through a groove and functioning as a piezoelectric driving mechanism, and a plate having a plurality of diaphragms bonded to a pillar end surface of each drive column with adhesives. Then, the inkjet head vibrates a diaphragm to eject the ink droplet. The drive column includes a receiving means for receiving surplus adhesives generated when the diaphragm and the drive column are bonded to a pillar end. Accordingly, the wet spreading of the adhesives to the adjacent piezo element is prevented, and the adhesives are controlled so as to be wet and spread in a direction without an adjacent piezo element, and thereby the occurrence of the crosstalk is prevented.

Description

  The present invention relates to an ink jet head that prevents crosstalk from occurring when ink droplets are ejected.

  An ink jet head used in an ink jet printer is required to have high ejection efficiency in order to achieve high image quality.

  For this reason, it is adhered so that no gap is formed between the piezo element having the driving column and the diaphragm part which is bonded to the driving end surface of the driving column and discharges ink droplets, which constitutes the inkjet head, and It is important that the adhesive between the piezo element and the diaphragm protrudes and does not contact the adjacent drive column.

  FIG. 8 is a sectional view of a conventional inject head.

  In the figure, reference numeral 1 denotes an ink jet head, and ink is ejected from a nozzle 12. The diaphragm portion 5 of the flow path plate 2 having the nozzles 12 and the piezo element 3 are bonded.

  Conventionally, when the diaphragm portion 5 and the piezo element 3 are bonded to each other, a gap is generated by mixing a gap agent in the gap formed between them or increasing the amount of adhesive applied. We are taking such measures. For the latter, measures are taken such as optimizing the amount of the adhesive 17 and reducing the application area of the adhesive 17 with respect to the application region so that the adhesive does not protrude.

  FIG. 9 is a perspective view showing a basic configuration of an inkjet head in a conventional piezo method.

  In this figure, 6 is a partition wall of the diaphragm 4, 7 is a chamber plate forming a pressure chamber, 8 is a partition plate, 9 is a supply port plate, 10 is an ink pool plate, 11 is a nozzle plate, and 12 is a nozzle. , 13 is a pressure chamber, 14 is an ink pool, and 16 is an adhesive surface between the piezoelectric element and the diaphragm.

  The piezo element 3 is formed as a laminated piezo element divided at a pitch corresponding to each nozzle pitch. The inkjet head 1 is arranged in parallel via a groove 1A, and includes a piezo element 3 having a plurality of drive columns 3A that function as a piezoelectric drive mechanism, and a flow path plate 2 that is provided on the piezo element 3 and discharges ink. And. The flow path plate 2 includes a diaphragm 4 having a plurality of diaphragm portions 5 bonded to the column end surfaces of the respective drive columns with an adhesive.

  In Patent Document 1, the drive column 3A escapes from the center of the column toward the end in parallel to the groove direction as a storage means for storing excess adhesive when the diaphragm portion 5 and the drive column 3A are bonded. The groove 15 is formed, and this has a temporary effect in that the amount of the adhesive protruding is suppressed.

Japanese Patent Laid-Open No. 11-320875

  However, in the above-mentioned Patent Document 1, processing is performed on the bonding surface (driving end surface) of the driving column bonded to the diaphragm portion, and the amount of protruding adhesive is controlled, but the protruding direction cannot be controlled. There is a possibility that the adhesive protrudes at the time of adhesion and adheres to the adjacent drive column, and crosstalk occurs when ink droplets are ejected. Since the pitch of the drive pillars of the piezo element becomes increasingly shorter as the degree of integration increases, the possibility that crosstalk will occur is increasing.

  In light of the circumstances as described above, an object of the present invention is to provide an ink jet head that prevents occurrence of crosstalk during ink droplet ejection.

  In order to achieve the above object, an ink jet head according to the present invention includes a plurality of driving columns of a piezo element and a plate having a plurality of diaphragm portions bonded to the column end surfaces of the driving columns by an adhesive. In the inkjet head that ejects ink droplets by vibrating the diaphragm portion, the drive column is provided with a relief groove for excess adhesive on the bonding surface between the diaphragm portion and the drive column.

  According to the present invention, it is possible to prevent the excess adhesive from adhering to the adjacent drive column and causing crosstalk when ink droplets are ejected. Furthermore, the application amount of the adhesive can be increased as compared with the conventional case, and the adhesive can be bonded with high reliability.

Sectional drawing of the inkjet head in Embodiment 1 Sectional drawing of the longitudinal direction in the pressure chamber of the inkjet head of Embodiment 1 The top view of the diaphragm part which made the protrusion part in Embodiment 1 the top Sectional drawing in Embodiment 2 Sectional drawing of the longitudinal direction of the pressure chamber of the inkjet head of Embodiment 2 Sectional view in Embodiment 3 Sectional drawing of the longitudinal direction of the pressure chamber of the inkjet head of Embodiment 3 Sectional drawing which shows the adhesion state of a diaphragm part and a piezoelectric element with the conventional inkjet head A perspective view showing the basic configuration of a conventional piezo-type inkjet head

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

(Embodiment 1)
FIG. 1 is a cross-sectional view of the ink jet head in the first embodiment, and FIG. 2 is a longitudinal cross-sectional view of the pressure chamber of the ink jet head in the first embodiment.

  The appearance of the ink jet head 1 of the first embodiment is the same as the basic structure of the ink jet head in the conventional piezo method of FIG. 9, but the structure of the protruding portion 18 is different.

  1 corresponds to the AA cross section of FIG. 9, and FIG. 2 corresponds to the BB cross section of FIG. The drive column 3A is provided with a surplus adhesive relief groove 15 on the bonding surface between the diaphragm portion 5 and the drive column 3A, and the relief groove 15 formed on the drive column 3A is formed on the surface bonded to the diaphragm portion 5 on the diaphragm. It is parallel to the long side of the protruding portion 18 of the portion 5.

  The escape groove 15 is lower by about 10 μm to 50 μm than the adhesion surface 16 of the drive column 3A of the piezo element adhered to the diaphragm portion 5. The protruding portion 18 of the diaphragm portion 5 having a smaller width than the escape groove 15 corresponds to the escape groove 15, and the escape groove 15 and the projected portion 18 are connected by an adhesive 17.

  In FIG. 2, the protruding portion 18 has a height inclination with respect to the BB cross-sectional direction. The height of the center part of the protrusion part 18 is high with respect to the BB cross-section direction, and the height is lowered as it goes to the end of the protrusion part.

  Specifically, the height of the central portion of the protruding portion 18 is about 50 to 90% of the depth of the escape groove 15, and the height of the end of the protruding portion 18 is the depth of the escape groove 15. 20 to 50% of the height.

  In FIG. 1, an adhesive 17 is used to bond the diaphragm portion 5 and the driving column 3A. As the adhesive 17, a two-component room temperature curing epoxy adhesive or a thermosetting epoxy adhesive is used and applied to the adhesive surface 16 of the drive column 3 </ b> A. Since it is desirable that the adhesive 17 is an adhesive that allows the diaphragm portion 5 to follow the movement of the driving column 3A, a relatively high hardness of 80 to 95 (Shore A) after curing the adhesive is suitable. Yes.

  The adhesive is applied by screen printing or transfer. At the time of bonding between the driving column 3A and the diaphragm portion 5, the flow path plate 2 including the diaphragm portion 5 or the driving column 3A is pressurized to improve the adhesion, but the adhesive applied to the bonding surface 16 at the time of pressing. No. 17 forms a film having a thickness of about 2 μm to 4 μm at the interface between the adhesive surface 16 and the diaphragm portion 5 after curing. If the thickness of the interface film is 5 μm or more, depending on the hardness of the adhesive, the movement of the drive column 3A is absorbed, and pressure cannot be efficiently applied to the diaphragm portion 5, so the film is preferably as thin as possible. .

  Moreover, since adhesive force will weaken when too thin, as thickness of an adhesive agent, the thickness of about 2 micrometers-4 micrometers is desirable.

  FIG. 3 is a plan view of the diaphragm portion 5 with the protruding portion 18 facing upward. The short side of the protruding portion 18 of the diaphragm portion 5 is smaller than the width of the escape groove. When the length of the protruding portion 18 on the diaphragm 5 is reduced from the center of the protruding portion 18 to the end along the long side, the length of the short side can be reduced during assembly of the diaphragm portion and the piezoelectric element. Both become easy to fit.

  Further, when the center of the protruding portion is high and the thickness of the end portion is low, the adhesive spreads from the center to the outside, so that bubbles are difficult to enter. When bubbles enter, the vibration of the driving column 3A is absorbed and attenuated by the bubbles. Therefore, when the bubbles are difficult to enter, there is an effect that variations in vibration transmission are reduced.

  According to the present embodiment, the adhesive 17 protruding by pressurization flows into the escape groove 15 and is cured. Accordingly, the adjacent columns are not mechanically connected by the adhesive 17 flowing out from the end face of each drive column. Therefore, it is possible to prevent crosstalk from occurring when ink droplets are ejected.

  In addition, it is possible to prevent the discharged adhesive from flowing into the gap between the diaphragm portion 5 and the partition wall portion 6 and being cured, thereby suppressing the vibration operation of the diaphragm portion 5 and reducing the discharge efficiency.

  Furthermore, since the application amount of the adhesive 17 can be increased, the reliability of adhesion is improved. Further, even if the application of the adhesive 17 varies, the overflowing adhesive 17 can be released to the escape groove 15, so that the yield is improved when manufacturing the ink jet head.

(Embodiment 2)
4 is a cross-sectional view of the ink jet head in the second embodiment, and FIG. 5 is a longitudinal cross-sectional view of the pressure chamber of the ink jet head in the second embodiment.

  The appearance of the inkjet head 1 of the second embodiment is the same as the basic configuration of the inkjet head in the conventional piezo method of FIG. 9, but the structure of the protruding portion 18 is different. 4 corresponds to the AA cross section of FIG. 9, and FIG. 5 corresponds to the BB cross section of FIG.

  The configuration of the inkjet head 1 in the second embodiment is the same as that in the first embodiment. However, in the first embodiment, the protrusion 18 is inclined with respect to the BB cross-sectional direction, but not in the second embodiment. Instead, the escape groove 15 of the drive column 3A is inclined with respect to the BB cross-sectional direction.

  The depth is such that the depth of the central portion of the escape groove 15 is shallow with respect to the BB cross-sectional direction, and the depth becomes deeper toward the end of the escape groove 15. Specifically, the depth of the end of the escape groove 15 is about 1.25 to 2 times deeper than the center depth of the escape groove 15.

  By changing the depth of the escape groove 15 of the drive column 3A, it is possible to process through grinding, so that the depth of the groove can be made highly accurate. This effect is expected to reduce the variation in efficiency when transmitting vibrations to the diaphragm.

  According to the present embodiment, the adhesive 17 protruding by pressurization flows into the escape groove 15 and is cured. Accordingly, the adjacent columns are not mechanically connected by the adhesive 17 flowing out from the end face of each drive column. Therefore, it is possible to prevent crosstalk from occurring when ink droplets are ejected.

  In addition, it is possible to prevent the discharged adhesive from flowing into the gap between the diaphragm portion 5 and the partition wall portion 6 and being cured, thereby suppressing the vibration operation of the diaphragm portion 5 and reducing the discharge efficiency.

  Furthermore, since the application amount of the adhesive 17 can be increased, the reliability of adhesion is improved. Further, even if the application of the adhesive 17 varies, the overflowing adhesive 17 can be released to the escape groove 15, so that the yield is improved when manufacturing the ink jet head.

(Embodiment 3)
6 is a cross-sectional view of the ink jet head in the third embodiment, and FIG. 7 is a longitudinal cross-sectional view of the pressure chamber of the ink jet head in the third embodiment.

  The appearance of the inkjet head 1 of the third embodiment is the same as the basic configuration of the inkjet head in the conventional piezo method of FIG. 9, but the structure of the protruding portion 18 is different. 6 corresponds to the AA cross section of FIG. 9, and FIG. 7 corresponds to the BB cross section of FIG.

  The configuration of the inkjet head 1 in the third embodiment is the same as that in the first embodiment.

  The escape groove 15 of the driving column 3A is inclined with respect to the BB cross-sectional direction. The depth is such that the depth of the central portion of the escape groove 15 is shallow with respect to the BB cross-sectional direction, and the depth becomes deeper toward the end of the escape groove 15. Specifically, the depth of the end of the escape groove 15 is about 1.25 to 2 times deeper than the center depth of the escape groove 15.

  The protruding portion 18 is inclined at a height with respect to the BB cross-sectional direction. The height of the center part of the protrusion part 18 is high with respect to the BB cross-section direction, and the height is lowered as it goes to the end of the protrusion part. Specifically, the height of the central portion of the protruding portion 18 is about 50 to 90% of the depth of the escape groove 15 in the central portion of the drive column 3A, and the height of the end of the protruding portion 18 is The height is about 20 to 50% of the depth of the escape groove 15 at the center of the driving column 3A.

  According to the present embodiment, the adhesive 17 protruding by pressurization flows into the escape groove 15 and is cured. Accordingly, the adjacent columns are not mechanically connected by the adhesive 17 flowing out from the end face of each drive column. Therefore, it is possible to prevent crosstalk from occurring when ink droplets are ejected.

  In addition, it is possible to prevent the discharged adhesive from flowing into the gap between the diaphragm portion 5 and the partition wall portion 6 and being cured, thereby suppressing the vibration operation of the diaphragm portion 5 and reducing the discharge efficiency. Furthermore, since the application amount of the adhesive 17 can be increased, the reliability of adhesion is improved. Further, even if the application of the adhesive 17 varies, the overflowing adhesive 17 can be released to the escape groove 15, so that the yield is improved when manufacturing the ink jet head.

  Since the inkjet head of the present invention has high adhesion reliability, it is possible to discharge with high accuracy and high reliability. It is preferably used as an inkjet head for applying an organic light emitting material in manufacturing an organic EL display panel that requires high definition, a fluorescent material in manufacturing a plasma display, and a filter material in manufacturing a color filter for a liquid crystal display.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path plate 3A Drive pillar 5 Diaphragm part 6 Partition part 15 Escape groove 17 Adhesive 18 Protruding part

Claims (5)

In an inkjet head comprising a piezo element having a driving column, and a diaphragm portion bonded to the column end surface of the driving column with an adhesive,
The drive column is formed with a relief groove for escaping excess adhesive that may occur on the bonding surface between the diaphragm portion and the drive column,
An inkjet head characterized by the above. 2. The inkjet head according to claim 1, wherein the escape groove is parallel to a long side of a protruding portion of the diaphragm portion on a surface bonded to the diaphragm portion. The diaphragm portion has a protruding portion whose shorter side is shorter than the width of the relief groove formed on the driving column with respect to the surface bonded to the driving column, and the height of the protruding portion of the diaphragm portion. The inkjet head according to claim 1 or 2, wherein the height of the center protruding portion is high, and the height decreases as it goes to the end of the protruding portion of the diaphragm portion. 3. The ink jet head according to claim 1, wherein the drive column has a relief groove having a deeper depth at an end in a groove direction and a shallower depth with respect to a surface bonded to the diaphragm portion. The drive pillar according to any one of claims 1 to 3, wherein the depth of the escape groove is deeper at the end in the groove direction and shallow at the center with respect to the surface bonded to the diaphragm portion. The inkjet head as described.

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