JP2005262643A - Inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head that is free from a discharge error and is long-life by strengthening the fastening of the relay member and a vibrating plate. <P>SOLUTION: The inkjet head is composed of an ink chamber communicating with an ink channel, a plurality of nozzles communicating with the ink chamber, a vibrating plate forming a part of the ink chamber and a piezoelectric vibrator provided in the position of the vibration plate opposite to the ink chamber. In the inkjet head varying the internal pressure of the ink chamber by expansion and contraction parallel with the polarization direction of the piezoelectric vibrator and discharging the ink from the nozzles, the vibrating plate is structured of a plurality of layers of an organic and inorganic substances, and the inorganic substance layer of the vibrating plate and a driving section are fastened together. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inkjet head used in an inkjet printer, and more particularly to an on-demand inkjet head.

  Various types of on-demand inkjet heads have been developed because the ink ejection mechanism is simple and the cost is low. In particular, the method of pressurizing the ink chamber with a stick-like piezoelectric vibrator and ejecting ink has a feature that the amount of ink can be adjusted by driving control of the piezoelectric vibrator and high-definition printing can be performed. In order to fabricate this type of head, first, a square bar-shaped or plate-shaped piezoelectric element is attached to a support substrate, and a plurality of stick-shaped piezoelectric elements are formed so as to correspond one-to-one to each ink chamber by dicing. Is divided into piezoelectric vibrators. Each of the divided piezoelectric vibrators is bonded to a vibration plate so as to correspond to each ink chamber. Piezoelectric vibrators are usually about 0.1 mm wide × 1.5 mm long × 2.2 mm high and are arranged at a pitch of about 0.68 mm.

  However, in recent years, there has been a trend toward higher integration, and a pitch of 0.254 mm or less has been seen. Further, as the integration becomes higher, the positional accuracy between the piezoelectric vibrator and the ink chamber greatly affects the variation in the ink ejection speed. In order to improve the positional accuracy, for example, it has been proposed to bond an ink chamber and a relay member positioned with high accuracy to the tip of the piezoelectric vibrator (see, for example, Patent Document 1). According to this method, as shown in FIG. 11, even if the position of the piezoelectric vibrator is slightly deviated from the ink chamber, pressure can be applied to the same position and the same area of the diaphragm via the relay member. Variations can be minimized.

  In the case of a highly integrated head, it is necessary to reduce mutual interference between nozzles, that is, crosstalk. Crosstalk is caused by the vibration of the flow path that occurs when the piezoelectric vibrator is driven. To reduce this vibration, it is necessary to increase the rigidity of the flow path and the compliance of the diaphragm. Therefore, recently, high rigidity silicon is processed to form a flow path, and a material having a low elastic modulus is often used for the diaphragm. Examples of the material for the diaphragm include polysulfone, polyester, and polyimide.

  Furthermore, a method of forming a diaphragm by coating a metal plate with a resin and then etching the metal has been proposed (see, for example, Patent Document 2). According to this method, it is possible to improve the bonding strength with the piezoelectric vibrator by leaving a metal protrusion at the center of the diaphragm. However, when assembling, there is a problem that the protrusion is detached from the center of the ink chamber due to a difference in thermal expansion with other components, resulting in an ink speed or more.

Japanese Patent Laid-Open No. 2004-001436

JP-A-11-198368

  The adhesion area of the piezoelectric vibrator or relay member to the diaphragm is very small, making it difficult to ensure the adhesion strength. If the diaphragm is made of resin, the adhesion strength is further reduced, and the head has a short life. It becomes.

  As can be seen in Japanese Patent No. 293368 and Patent Document 1 above, there is a method of forming an adhesive escape hole in the relay member or vibrator to increase the bonding area, but it is thick between the relay member and the diaphragm. An adhesive layer or an air layer is formed, which significantly impedes vibration transmission of the piezoelectric vibrator.

  Further, in Japanese Patent No. 3041952 (FIG. 22c), there is a figure in which an elastic material is sealed around the vibrator. In this case, although the life of the head can be extended, the compliance of the diaphragm is lowered and the crosstalk is reduced. Will increase.

  Further, in the method as described in Patent Document 2, the protrusions are detached from the center of the ink chamber due to a difference in thermal expansion with other components during assembly, resulting in an ink speed or more and variations.

  An object of the present invention is to provide a long-life inkjet head capable of eliminating such drawbacks of the prior art, strengthening the fixing strength between the relay member and the diaphragm, and withstanding long-time vibration.

  To achieve the above object, the present invention provides an ink chamber that communicates with an ink flow path, a plurality of nozzles that communicate with the ink chamber, a diaphragm that forms part of the ink chamber, and an ink chamber of the diaphragm. In the ink jet head that changes the pressure in the ink chamber by expansion and contraction parallel to the polarization direction of the piezoelectric vibrator and ejects ink from the nozzle, the diaphragm It is composed of a plurality of layers of an organic material and an inorganic material, and the inorganic material layer of the diaphragm is fixed to the piezoelectric vibrator.

  The diaphragm is characterized by depositing an inorganic layer on an organic film.

  The present invention is configured as described above, and since the inorganic layer and the piezoelectric vibrator or the relay member are bonded, the bonding strength is improved, and a high-quality, long-life inkjet head can be obtained.

  Next, the best mode for carrying out the ink jet head according to the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of an inkjet head 1 according to this embodiment, and FIG. 2 is an exploded perspective view of the inkjet head.

  As shown in FIG. 2, the ink jet head 1 is roughly composed of a drive unit 50 and a flow path unit 51.

  The flow path portion 51 includes an orifice plate 5 having a nozzle 10, a chamber plate 6 having an ink chamber 11, a diaphragm plate 7 having a vibration plate 12, a reinforcing plate 2 for reinforcing the flow path, and the like.

  The drive unit 50 includes a relay member 8 corresponding to the ink chamber 11, the piezoelectric vibrator 9, the support substrate 3, and the like. The piezoelectric vibrator 9 is bonded to the end of the support substrate 3.

  The ink jet head includes an ink chamber 11 that communicates with an ink flow path, a plurality of nozzles 10 that communicate with the ink chamber 11, a vibration plate 12 that forms part of the ink chamber 11, and an ink chamber of the vibration plate 12. 11 is a mechanism for ejecting ink from the nozzle 10 by changing the pressure in the ink chamber by expansion and contraction parallel to the polarization direction of the piezoelectric vibrator 9. ing.

  FIG. 3 is a perspective view of a drive unit in the ink jet head of this embodiment. The support substrate 3 is made of an electrically insulating ceramic such as alumina or zirconia, for example. As shown in FIG. 3, the piezoelectric vibrator 9 is obtained by grooving a laminated piezoelectric element 23 having a piezoelectric constant d33.

  Here, FIG. 4 shows a sectional view of the vicinity of the diaphragm 12 of the diaphragm plate 7 according to the present invention.

  The diaphragm plate 7 used in the present embodiment is composed of three layers: a diaphragm 12, a thick portion 26, and an inorganic layer 28. In the present embodiment, polyimide film 21 is used for diaphragm 12, SUS 304 is used for thick portion 26, and aluminum is used for inorganic layer 28.

  A method for manufacturing the diaphragm plate 7 will be described below.

  First, a polyimide film 21 having a thickness of 15 μm having a thermoplastic polyimide layer on one side and a rolled stainless steel plate 29 having a thickness of 25 μm are heated at a temperature of about 350 ° C. using a laminator 27 as shown in FIG. Crimp. Masking is performed on the two-layer plate, and unnecessary portions of stainless steel are etched.

  Only the diaphragm 12 portion of the diaphragm plate 7 thus obtained was exposed by masking, and an aluminum layer having a thickness of about 500 nm was deposited by sputtering.

  FIG. 6 shows a state diagram of the sputter deposition.

  The power during sputtering was about 1 kW.

  As shown in FIG. 7, the sputter deposition forms a mixed layer 30 between the polyimide film 21 and the aluminum layer 31, so that the adhesion strength of the aluminum layer 31 is very high.

  FIG. 8 is a cross-sectional view of the bonding portion between the diaphragm 12 and the piezoelectric vibrator 9.

  FIG. 9 is a cross-sectional view of the bonding portion between the diaphragm 12 and the relay member 8.

  The polyimide film 21 is excellent in corrosion resistance to various inks, but the adhesion strength with the adhesive is weak and has become a starting point for adhesion peeling.

  8 and 9, since the aluminum layer 31 and the piezoelectric element 9 or the relay member 8 are bonded, the bonding strength is greatly improved. If a silane coupling agent or the like is used at the time of bonding, the compatibility between the adhesive and the material to be bonded is further improved and effective.

  FIG. 10 shows the conventional diaphragm plate 7, that is, the one having no inorganic layer 28 and the diaphragm plate 7 according to the embodiment of the present invention, that is, having the aluminum layer 31 as the inorganic layer 28, but the adhesive strength with the relay member. FIG. As shown in FIG. 10, the peel strength was 0.40 kg / cm with the aluminum layer and 0.14 kg / cm without the aluminum layer, respectively. By having the aluminum layer 31, it was possible to obtain an adhesive strength more than twice.

1 is a perspective view of an inkjet head according to an embodiment of the present invention. It is a disassembled perspective view of the inkjet head. It is a perspective view of the drive part in the ink jet head. It is sectional drawing of a diaphragm plate. It is a figure which shows the lamination process of a diaphragm and a thick part. It is a figure which shows sputter vapor deposition. It is a figure which shows the interface of a polyimide film and an aluminum layer. It is sectional drawing which shows the adhesion part of a diaphragm and a piezoelectric vibrator. It is sectional drawing which shows the adhesion part of a diaphragm and a relay member. It is the graph which compared the prior art and the example of this invention about the adhesive strength of a diaphragm and a relay member. It is a structure sectional view of the ink jet head by a prior art.

Explanation of symbols

1: inkjet head, 2: reinforcing plate, 3: support substrate, 4: FPC, 5: orifice plate, 6: chamber plate, 7: diaphragm plate, 8: relay member, 9: piezoelectric vibrator, 10: nozzle, 11 : Ink chamber, 12: diaphragm, 13a: individual electrode, 14: conductive member, 21: polyimide film, 22: adhesive, 23: laminated piezoelectric element, 26: thick part, 27: laminator, 28: inorganic substance Layer: 29: stainless steel plate, 30: mixed layer, 31: aluminum layer, 50: drive unit, 51: flow channel unit, 104: support base, 105: piezoelectric vibrator, 107: relay member, 107a: protrusion, 110 : Diaphragm plate, 111: Chamber plate, 112: Orifice plate, 113: Reference pin, 123: Reference hole, 124: Ink chamber, 125: Vibration plate, 26: adhesive escape hole, 127: thick portion of the diaphragm, 128: adhesive 129: a nozzle.

Claims (2)

An ink chamber communicating with the ink flow path, a plurality of nozzles communicating with the ink chamber, a vibration plate forming a part of the ink chamber, and a piezoelectric vibrator provided at a position facing the ink chamber of the vibration plate An ink jet head that changes ink chamber pressure by expansion and contraction parallel to the polarization direction of the piezoelectric vibrator, and discharges ink from the nozzle.
The diaphragm is composed of a plurality of layers of an organic material and an inorganic material, and the inorganic layer of the diaphragm and the piezoelectric vibrator are fixed to each other. 2. The ink jet head according to claim 1, wherein the diaphragm is formed by depositing an inorganic layer on an organic film.

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