JP2007076303A - Inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a head small-sized by reducing a cross talk in an inkjet head with a pressure chamber which is arranged with two trains being opposed. <P>SOLUTION: In forming one train of nozzle from two trains of pressure chamber, a relay passage is installed between the pressure chamber and a nozzle opening. Thereby, the stiffness of the center section between the pressure chamber trains is enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet head, and more particularly, to an ink jet head that includes pressure chambers arranged to face two rows and ejects ink with a drive element.

As a conventional inkjet head, there is a push type using a longitudinally vibrating piezoelectric vibrator (see, for example, Patent Document 1). In this head, a nozzle opening that ejects ink, a pressure chamber that is an ink reservoir communicating with the nozzle opening, a common ink chamber that supplies ink to each pressure chamber, a restrictor that connects the common ink chamber and each pressure chamber, A nozzle composed of a piezoelectric vibrator that pressurizes the liquid in the pressure chamber and a diaphragm that transmits the energy of the piezoelectric vibrator to the pressure chamber is arranged in a line. In recent years, due to improvements in head component manufacturing technology, the number of nozzles and the density of nozzles in ink jet heads have increased, and the distance between nozzles has become very narrow. As a result, there are the following problems.
(1) As the distance between adjacent nozzles decreases, the rigidity of the partition walls of the pressure chambers that form adjacent spaces decreases, and vibration interference with the adjacent nozzles occurs (hereinafter referred to as crosstalk).
(2) The piezoelectric vibrator array has a narrow pitch, and there is a limit to processing.

  In order to solve these problems, a two-row facing system is adopted in which two rows of pressure chambers are formed with respect to one nozzle row (see, for example, Patent Document 2). In this method, two rows of pressure chambers, restrictors, and common ink chambers are formed around the nozzle row. When the pressure chambers in one row communicate with the nozzles, the adjacent nozzles communicate with the other row alternately. If the nozzle pitch is set to Pn, the pressure chamber pitch Pc becomes Pc = 2 × Pn, which solves the above-mentioned problems such as crosstalk and processing limit.

Japanese Patent No. 3041952

Japanese Patent No. 2850762

  In the conventional ink jet head described above, the nozzle density can be improved. However, when the nozzle openings are arranged in a line at the center, the same number of communication holes connecting the nozzle openings and the pressure chambers are provided in a concentrated manner. , The rigidity of the central portion is reduced. Thereby, the vibration of one row is easily transmitted to the other row, and the crosstalk is large. In addition, since the pressure chamber, the restrictor, and the common ink chamber are arranged in two rows, the head width in the direction perpendicular to the nozzle row is increased, and the head size cannot be reduced. For this reason, it is not easy to arrange a large number of heads.

  An object of the present invention is to provide an inkjet head that can reduce the head size by increasing the rigidity of the central portion of the inkjet head having pressure chambers arranged in two rows so as to reduce crosstalk. .

  In order to achieve the above object, in the ink jet head of the present invention, a plurality of nozzle openings arranged in approximately one row, a first communication hole communicating with each of the nozzle openings, and a relay communicating with the communication hole A flow path, a second communication path communicating with the relay flow path, a pressure chamber communicating with the second communication path and provided with a drive element for pressurizing ink, and communicating with the pressure chamber; A restrictor for limiting the amount of ink to be supplied, and the pressure chambers are arranged as two pressure chamber rows so as to face each other through the nozzle opening rows, and between the pressure chamber rows. Is characterized in that a relay ink chamber having a partition wall is provided therein, and ink is supplied from a common ink chamber communicating with the relay ink chamber.

  In the ink jet head of the present invention, a plurality of nozzle openings arranged in two rows facing each other, a communication hole communicating with each of the nozzle openings, a driving element communicating with the communication hole and pressurizing ink And a restrictor for limiting the amount of ink supplied in communication with the pressure chamber, and the pressure chambers are arranged so as to face each other through the nozzle opening row. The pressure chamber rows are arranged opposite to each other, and a relay ink chamber having a partition is provided between the pressure chamber rows, and ink is supplied from a common ink chamber communicating with the relay ink chamber. It is the structure.

  Next, in the inkjet head of the present invention, the nozzle opening, the communication hole, the pressure chamber, the restrictor, and the relay ink chamber are integrally formed and formed by dry etching of Si. Yes.

  Furthermore, in the ink jet head of the present invention, one of the nozzle opening rows has a distance of 1/4 of the pitch of the pressure chambers in one direction with respect to the nozzle opening row direction from the center of the pressure chamber. The other nozzle opening row is displaced and is shifted by a quarter of the pitch of the pressure chambers, contrary to the arrangement direction of the nozzle openings.

  In the inkjet head of the present invention, in the nozzle opening row, the nozzle opening adjacent to the pressure chamber arranged on one side communicates with the pressure chamber arranged on the other side, and from the center of the pressure chamber, The pressure chambers are arranged with a distance of 1/4 of the pressure chamber pitch.

  In the ink jet head of the present invention, the cross-sectional area of the relay flow path is gradually reduced from the side communicating with the pressure chamber toward the nozzle opening.

  In the ink jet head of the present invention, the pressure chamber and the restrictor are disposed in an inclined state with respect to a direction orthogonal to the nozzle row, and the partition wall is not disposed in a central portion of the relay ink chamber. It is characterized by.

  In the ink jet head of the present invention, when forming one nozzle row from two pressure chamber rows, a relay flow path is provided between the pressure chamber and the nozzle opening to increase the rigidity of the central portion between the pressure chamber rows. Since the structure is adopted, the crosstalk can be reduced because the fluid vibration of the pressure chambers in one row is not easily transmitted to the pressure chambers in the other row.

  In addition, since the relay ink chamber is provided in the central portion of the plurality of pressure chambers arranged opposite to the two rows and the partition wall is provided in the central portion of the relay ink chamber, the fluid in the pressure chambers in one row is provided. Crosstalk can be reduced because the vibration does not affect the pressure chambers of the other row facing each other.

  As a result, high quality printing by stable ejection becomes possible. Further, in a head having one nozzle row, high resolution printing is easy if the head is arranged obliquely.

  In addition, since the nozzle opening, the pressure chamber, the restrictor, and the relay ink chamber are integrated and formed by Si dry etching, the ink flow path can be easily formed, and the nozzles can be arranged with high accuracy.

  Also, one nozzle opening row is arranged with a shift of 1/4 of the pitch between the pressure chambers in the nozzle opening row direction with respect to the center of the pressure chamber, and the other nozzle opening row is arranged at the same pitch in the opposite direction. Since they are displaced from each other, it is possible to realize a nozzle opening arrangement that is ½ of the pressure chamber pitch in the nozzle opening row orthogonal direction.

  Similarly, when one nozzle opening row is used for two rows of pressure chambers, the nozzle adjacent to one pressure chamber row is connected to the other pressure chamber row, and pressure is applied from the center of the pressure chamber. This can be realized by shifting the distance by 1/4 of the pitch of the chamber rows.

  In addition, since the cross-sectional area of the relay flow path is gradually reduced from the side communicating with the pressure chamber toward the nozzle, the ink flow becomes smooth and air bubbles can be easily discharged, thereby improving the initial ink filling property. .

  In addition, since the pressure chamber and the restrictor are disposed in an inclined state with respect to the direction orthogonal to the nozzle row, the head can be reduced in size while keeping the length of the pressure chamber constant. In particular, the width of the head can be reduced.

  Embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a case where a piezoelectric vibrator is used as a driving element will be described. However, in the present invention, any driving element may be used as long as ink in a pressure chamber can be ejected.

  The ink jet head according to the present embodiment is roughly divided into an ink flow path portion that controls the flow of ink and a drive portion that generates ink discharge energy, and each will be described in detail below.

  First, the ink flow path portion will be described in detail. FIG. 1 is an exploded perspective view of an inkjet head showing an embodiment of the present invention, and FIG. 2 is a sectional view of a nozzle. In the drawing, the ink flow path portion 28 is assembled by bonding by laminating the nozzle plate 7, the chamber plate 8, the diaphragm plate 2, and the housing 3. The chamber plate 8 includes a pressure chamber 11, a restrictor 12, a relay ink chamber 13, and a second communication hole 10. The diaphragm plate 2 includes a diaphragm 16 and a filter 17 that transmit the energy of the drive unit 4 to the pressure chamber 11 and also serve as a lid for the pressure chamber 11. The nozzle plate 7 includes a nozzle opening 9, a first communication hole 10, and a relay flow path 15.

  FIG. 5 is a diagram showing the configuration of the housing in the present embodiment. The housing 3 includes a through hole 18 into which the driving unit 4 is inserted, a common ink chamber 19 that supplies ink to the relay ink chamber 13, and an ink supply path 20 that supplies ink to the common ink chamber 19.

  The diaphragm plate 2 is formed by welding thermoplastic polyimide to stainless steel, and then etching the stainless steel portion to expose the diaphragm 16 and the filter 17 region. The diaphragm 16 is formed to be slightly wider than the area of the pressure chamber 11 at a portion that is one side surface of the pressure chamber 11. The thickness of stainless steel is 25 to 39 μm, and the thickness of polyimide is 15 to 25 μm. The filter 17 is provided so as to cover the relay ink chamber 13, and the filter hole is smaller than the nozzle opening diameter and is formed by laser processing. However, when the ink containing fine particles is used, the filter 17 is not provided, so that the filter 17 forming region can be cut out. With such a configuration, the ink supplied to the two rows of ink flow paths can be filtered by the filter 17 in one place.

  The housing 3 is formed by machining an Fe-42Ni alloy having the same thermal expansion coefficient as that of the chamber plate 1. The common ink chamber 19 is formed so as to go around the housing 3, and an ink supply path 20 for sending ink from the outside is provided in a portion corresponding to both ends of the nozzle row. The common ink chamber 19 is formed with substantially the same area as the relay ink chamber 13 of the chamber plate 1. Two through holes 18 into which the drive unit 4 is inserted are provided for each nozzle row so as to sandwich the common ink chamber 19, and are processed into a width that forms a certain gap with the drive unit 4. Since the width in the direction perpendicular to the nozzle row greatly affects the crosstalk, it is necessary to make it as narrow as possible. By providing the through holes 18 for each nozzle row in this way, the opening area in the nozzle row orthogonal direction can be made relatively narrow, and the influence of crosstalk can be reduced.

  The nozzle plate 7, the chamber plate 8, the diaphragm plate 2, and the housing 3 are joined with an adhesive. Each plate is joined with a film-like epoxy adhesive. The positioning of each plate is joined using the positioning pin hole 22.

  Next, the drive unit will be described in detail. In FIG. 1, the drive unit 4 has a configuration in which the same number of piezoelectric vibrators 21 as the nozzle openings 9 are bonded to an electrode-patterned base 5 and an electric signal is applied from the FPC 6 through the base 5. The piezoelectric vibrator 21 becomes an ink discharge energy generation source. In this embodiment, the d33 piezoelectric vibrator is used.

  FIG. 6 is a perspective view of the drive vibrator section in the present embodiment. Here, ceramic is used for the base 5, and the surface to which the piezoelectric vibrator 21 is attached is subjected to high-precision flatness processing, and the individual electrode pattern 23 is provided on one side of the side surface, On the opposite surface, the common electrode pattern 24 is patterned by screen printing. The piezoelectric vibrator 21 is adhesively bonded to the base 5 in a rod-like state, and is divided into strips according to the individual electrode pattern 23. Electrical connection between the piezoelectric vibrator 21 and the base 5 is conducted by applying a conductive adhesive 25.

  In this embodiment, the staggered arrangement can be easily accommodated by using the two drive units 4 described above.

  After the ink flow path section 1 and the drive section 4 are produced in separate steps, both are bonded with an adhesive. Here, the vibrator is positioned and joined so that the vibrator comes to the center of the pressure chamber 11 by an apparatus not shown.

  3A and 3B are top views of components of the ink jet head of the present invention. FIG. 3A is a pressure chamber side of the chamber plate, and FIG. 3B is a pressure chamber side of the nozzle plate. The dotted line in (a) indicates the position of the diaphragm. The nozzle plate 7 and the chamber plate 8 are formed by dry etching of Si.

  In FIG. 3A, the relay ink chamber 13 is disposed at the center of the chamber plate 8, and from there, the restrictor 12 and the pressure chamber 11 are disposed in this order. Since the through-hole is in the outermost part as described above, the rigidity of the chamber plate can be improved as compared with the case where the through-hole is formed in the central portion.

  In the ink jet head of the present invention, a partition wall 14 serving as a partition is provided at the center of the relay ink chamber 13. This is provided to reduce crosstalk by preventing fluid vibration in one row from reaching the other row via the relay ink chamber 13.

  In FIG. 3B, in the nozzle plate 7, the first communication hole 10 communicating with the nozzle opening 9 is disposed at the center, and the relay flow path 15 is provided in the second communication hole 10 of the pressure chamber 11 facing the nozzle plate 7. It arrange | positions so that the 1st communicating hole 10 of the nozzle opening 9 may be connected from the position corresponding to. And the cross-sectional area of the relay flow path 15 is formed so that it becomes narrow as it approaches the nozzle opening 9 side from the pressure chamber 11 side. As a result, the ink flows smoothly, bubbles can be easily discharged, and the initial filling property of the ink can be improved. The first communication hole 10 of the nozzle opening 9 is a perfect circle in the drawing, but may be an ellipse or a deformed circle. However, if it is too large, vibrations are easily transmitted to adjacent nozzles, so it is desirable to make it small.

  The nozzle openings 9 are arranged as follows. When the pitch between the pressure chambers 11 is Pc and the distance between the centers of the communication holes on the pressure chamber 11 side and the nozzle opening 9 side in the horizontal direction is L, first, the communication holes 10 on the opposing pressure chamber 11 side The center is arranged on a horizontal straight line. Next, the nozzle opening 9 communicating with the second communication hole 10 of the opposing pressure chamber 11 is similarly set so that one nozzle opening 9 becomes L = Pc / 4 with the above-mentioned straight line as a base line. The above-mentioned straight line is used as a base line and L = Pc / 4 is arranged on the opposite side. As a result, the pitch Pn of the nozzle openings 9 is Pn = 2 × Pc / 4 = Pc / 2.

  FIG. 4 is a top view of a chamber plate 8 according to another embodiment. In the arrangement of the pressure chambers 11, as shown in the figure, the rows of the pressure chambers 11 may be arranged in a staggered manner. In this case, since the fluid vibration of one row collides with the partition between the pressure chambers of the other row, the partition 14 is not necessary.

  In such a configuration, since the common relay ink chamber 13 can be used for the two nozzle rows, the head width in the direction perpendicular to the nozzle rows can be reduced. If configured as in the present embodiment, even if the pressure chambers 11 are arranged in two rows, the width in the direction perpendicular to the nozzle rows can be easily reduced as much as possible. In the zigzag arrangement, the partition walls 14 are eliminated, so that the width can be further reduced. Further, since the positions of the two pressure chambers 11 are relatively separated without changing the overall size of the inkjet head, the influence of crosstalk between the rows can be reduced.

  The ink ejection process according to the above-described configuration of the present invention will be described with reference to FIG. First, ink is sent from an ink tank (not shown) to the ink supply path 20 through a tube or the like, and the ink is stored in the common ink chamber 19 from the ink supply path 20. Ink is sent from the common ink chamber 19 to the relay ink chamber 13 through the filter 17, and the pressure chamber 11 is filled with ink via each restrictor 12. An electric signal from a drive circuit (not shown) is sent to the piezoelectric vibrator 21, the piezoelectric vibrator 21 is expanded and contracted to deform the diaphragm 16, and the ejection energy of the piezoelectric vibrator 21 is transmitted to the ink in the pressure chamber 11. Ink is ejected from the nozzle opening 9 from the second communication hole 10 of the chamber plate 8 through the relay flow path 15 and the first communication hole 10 of the nozzle plate 7.

  FIG. 7 is a cross-sectional view of the head in the second embodiment of the present invention. Here, the nozzle plate 7 and the chamber plate 8 are integrated, the nozzle opening 9, the first communication hole 26 of the nozzle plate 7, the second communication hole 10 of the chamber plate 8, the pressure chamber 11, and the relay. The ink chamber 13 and the partition wall 14 are integrally formed by Si dry etching. In order to integrally form in this way, the relay flow path 15 is not provided, and the nozzle opening rows are arranged at both ends of the nozzle plate 7 respectively. However, the rigidity of the members is high, so that crosstalk is reduced and the head is downsized. It is valid.

  FIG. 8 is a top view of the chamber plate 1 in the second embodiment. In the figure, a top view of the chamber plate 1 in FIG. 7 is shown. In one nozzle opening row, the nozzle opening 9 is shifted from the center of the pressure chamber 11 by Pc / 4 with respect to the pressure chamber pitch Pc on the adjacent nozzle opening side. The opposed nozzle opening rows are arranged on the opposite side with a shift of Pc / 4 pitch. As a result, the nozzle openings 9 in the other row are arranged between the nozzle openings in one row. Therefore, when the nozzle opening rows are arranged perpendicular to the printing direction, the nozzle opening pitch Pn = Pc / 2. The resolution can be doubled.

  In the configuration of the second embodiment, the number of plates is reduced, so that the assembly work time can be reduced, and the cavity portion is reduced, so that the rigidity of the plates is improved.

  FIG. 9 shows another embodiment of the chamber plate 1. Here, the restrictor 12 is formed to be inclined with respect to the longitudinal direction of the pressure chamber 11 and with respect to the longitudinal direction of the relay ink chamber 13. Thus, by making the restrictor 12 oblique, the width of the head can be made as small as possible. In this case, the restrictor 12 can be connected to the corners on the diagonal line of the pressure chamber 11 to prevent the ink flow from stagnation, and since the fluid vibration is not transmitted to the opposing pressure chamber, the restrictor 12 has a partition wall. Even if it is not, crosstalk can be reduced.

The exploded perspective view of the ink-jet head of the present invention Sectional view of the inkjet head of the present invention 2A and 2B are top views of the inkjet head component of the present invention, in which FIG. 1A shows the pressure chamber side of the chamber plate, and FIG. 2B shows the pressure chamber side of the nozzle plate. The top view of the chamber plate 1 in the 2nd Example of the inkjet head of this invention. The perspective view of the housing 3 in the inkjet head of this invention The perspective view of the drive part 4 in the inkjet head of this invention Head sectional view in the second embodiment of the ink jet head of the present invention. The top view of the chamber plate in the 2nd example of the ink-jet head of the present invention. Top view of another chamber plate in the second embodiment of the inkjet head of the present invention

Explanation of symbols

1 Chamber plate
2 Diaphragm plate
3 Housing
4 Drive unit
5 base
6 FPC
7 Nozzle plate
8 Chamber plate
9 nozzles
10 Chamber plate communication hole
11 Pressure chamber
12 restrictor
13 Common ink chamber
14 Bulkhead
15 Relay channel
16 Diaphragm
17 Filter
18 Drive through hole
19 Relay ink chamber
20 Ink supply path
21 Piezoelectric vibrator
22 Locating pin hole
23 Individual electrode pattern
24 Common electrode pattern Conductive adhesive Nozzle plate communication hole Nozzle Chamber plate Ink flow path

Claims (8)

  A plurality of nozzle openings arranged in approximately one row, a first communication hole communicating with each of the nozzle openings, a relay flow path communicating with the communication hole, and a second communication path communicating with the relay flow path A pressure chamber that is in communication with the second communication path and is provided with a drive element that pressurizes the ink; and a restrictor that is in communication with the pressure chamber and limits the amount of ink to be supplied; and The pressure chambers are arranged opposite to each other as two pressure chamber rows so as to face each other via the nozzle opening row, and a relay ink chamber having a partition wall is provided between the pressure chamber rows, An ink jet head, wherein ink is supplied from a common ink chamber communicating with the relay ink chamber.   A plurality of nozzle openings arranged opposite to each other in two rows, a communication hole communicating with each of the nozzle openings, a pressure chamber communicating with the communication hole and provided with a drive element for pressurizing ink; A restrictor for limiting the amount of ink supplied in communication with the pressure chambers, and the pressure chambers are arranged opposite to each other as two pressure chamber rows so as to face each other through the nozzle opening rows. An ink jet is characterized in that a relay ink chamber having a partition wall is provided between the pressure chamber rows, and ink is supplied from a common ink chamber communicating with the relay ink chamber. head.   The inkjet head according to claim 2, wherein the nozzle opening, the communication hole, the pressure chamber, the restrictor, and the relay ink chamber are integrally formed.   The inkjet head according to claim 3, wherein the nozzle opening, the communication hole, the pressure chamber, the restrictor, and the relay ink chamber are integrally formed by Si dry etching.   One of the nozzle opening rows is arranged such that the nozzle opening is shifted from the center of the pressure chamber by a distance of 1/4 of the pitch of the pressure chamber in one direction with respect to the nozzle opening row direction, and the other 3. The inkjet head according to claim 2, wherein the nozzle opening row is shifted by a quarter of the pitch of the pressure chambers in the direction opposite to the arrangement direction of the nozzle openings.   In the nozzle opening row, a nozzle opening adjacent to a pressure chamber arranged on one side communicates with a pressure chamber arranged on the other side, and from the center of the pressure chamber, 1 / of the pitch of the pressure chambers. The inkjet head according to claim 1, wherein the inkjet head is arranged so as to be shifted by a distance of four.   The inkjet head according to claim 1, wherein a cross-sectional area of the relay flow path is gradually reduced from the side communicating with the pressure chamber toward the nozzle opening. The said pressure chamber and the said restrictor are arrange | positioned in the state inclined with respect to the direction orthogonal to the said nozzle row, The said partition is not arrange | positioned in the center part of the said relay ink chamber. Inkjet head.

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