JP2006327159A - Liquid jet head and liquid jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jet head which has an assembling time shortened by facilitating connection between a driving circuit and a piezoelectric element, and has also a yield improved, and to provide a liquid jet apparatus. <P>SOLUTION: The liquid jet head is equipped with a passage formation substrate 10 where pressure generation chambers 12 communicating with nozzle openings 21 for jetting liquid droplets are formed, piezoelectric elements 300 which are set via a diaphragm at one face side of the passage formation substrate 10 to cause a pressure change in the pressure generation chambers 12, and a protecting substrate 30 joined to the face of the piezoelectric element 300 side of the passage formation substrate 10. Moreover, a driving circuit 110 is equipped which is mounted on a rigid flexible wiring substrate 120 comprised of a rigid substrate 122 and a flexible substrate 121 stacked on the protecting substrate 30. A rigid region 122a with the rigid substrate 122 of the rigid flexible wiring substrate 120 is electrically connected to a leading line 90 led out on the passage formation substrate 10 from the piezoelectric element 300. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that eject liquid, and more particularly, to an ink jet recording head and an ink jet recording apparatus that eject ink droplets.

  A part of the pressure generating chamber communicating with the nozzle opening is constituted by a diaphragm, and the diaphragm is deformed by a piezoelectric element to pressurize ink in the pressure generating chamber and eject ink droplets from the nozzle opening. There are two types in practical use, one using a piezoelectric actuator in a longitudinal vibration mode that extends and contracts in the axial direction of the piezoelectric element and one using a piezoelectric actuator in a flexural vibration mode.

  For example, the latter actuator using the flexural vibration mode is formed by forming a uniform piezoelectric material layer over the entire surface of the diaphragm by a film forming technique, and generating pressure by lithography using this piezoelectric material layer. A device in which a piezoelectric element is formed so as to be separated into shapes corresponding to chambers and independent for each pressure generating chamber is known. Such piezoelectric elements can be arranged at a relatively high density.

  In addition, as an ink jet recording head, a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is defined, a piezoelectric element formed on one surface side of the flow path forming substrate, and a flow path forming substrate Some include a sealing substrate having a piezoelectric element holding portion that is bonded to a surface on the piezoelectric element side and seals the piezoelectric element (see, for example, Patent Document 1).

  In this ink jet recording head, a drive circuit is mounted on a sealing substrate, and the drive circuit and a lead-out wiring drawn out from the piezoelectric element onto the dew formation substrate are electrically connected via a connection wire such as a bonding wire. is doing.

  However, since the connection wiring for electrically connecting the lead-out wiring and the drive circuit is connected to the lead-out wiring and the drive circuit one by one by wire bonding, there is a problem that it takes time to connect and the yield is poor.

  Such a problem exists not only in an ink jet recording head that ejects ink droplets, but also in other liquid ejecting heads that eject droplets other than ink.

JP 2004-82722 A (Page 9, FIGS. 1 and 8)

  In view of such circumstances, it is an object of the present invention to provide a liquid ejecting head and a liquid ejecting apparatus in which a drive circuit and a piezoelectric element are easily connected to reduce assembly time and improve yield.

According to a first aspect of the present invention for solving the above problem, a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid droplets is formed, and a vibration plate is provided on one side of the flow path forming substrate. And a protective substrate bonded to the surface of the flow path forming substrate on the piezoelectric element side, and a rigid substrate on the protective substrate. And a flexible circuit board mounted on a rigid flexible wiring board, and a rigid region of the rigid flexible wiring board having the rigid board is provided from the piezoelectric element to the flow path. A liquid ejecting head is characterized in that the liquid ejecting head is electrically connected to a lead wiring drawn on a formation substrate.
In the first aspect, the rigid flexible wiring board can connect the drive circuit provided on the protective substrate to the lead-out wiring on the flow path forming substrate having a step with the protective substrate, and the rigid circuit board. Since the flexible wiring board and the lead wiring can be connected together, the connection time can be shortened and the manufacturing cost can be reduced. Further, by connecting the rigid region of the rigid flexible substrate to the lead-out wiring, the rigid substrate can buffer the difference in linear expansion of different materials, and the pitch deviation during mounting can be reduced.

According to a second aspect of the present invention, in the liquid jet head according to the first aspect, the driving circuit is mounted in a flexible region including only the flexible substrate of the rigid flexible wiring substrate. .
In the second aspect, the drive circuit can be mounted in the flexible region.

A third aspect of the present invention is the liquid ejecting head according to the first or second aspect, wherein the rigid substrate of the rigid flexible wiring substrate is connected to the lead-out wiring.
In the third aspect, by connecting a rigid substrate to the lead-out wiring, the rigid substrate can reduce the step between the surface of the flow path forming substrate and the surface of the protective substrate, thereby reducing the bending of the flexible substrate. It is possible to easily handle the rigid flexible wiring board.

According to a fourth aspect of the present invention, in the liquid jet head according to the first or second aspect, the flexible substrate is connected to the lead-out wiring in the lead-out wiring.
In the fourth aspect, the wiring structure of the rigid flexible wiring board can be simplified.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the lead-out wiring of the piezoelectric element and the rigid flexible wiring board are connected by thermal welding. In the head.
In the fifth aspect, the rigid flexible wiring board and the lead-out wiring can be electrically and reliably connected.

According to a sixth aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head according to any one of the first to fifth aspects.
In the sixth aspect, a liquid ejecting apparatus with improved manufacturing cost and reliability can be realized.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a perspective view of an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view and an enlarged cross-sectional view of the main part of the ink jet recording head according to Embodiment 1 of the present invention.

  As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110) in the present embodiment, and is made of silicon dioxide previously formed by thermal oxidation on both surfaces, with a thickness of 0.5 to A 2 μm elastic film 50 is formed.

  The flow path forming substrate 10 is anisotropically etched from the other direction side to form two rows of pressure generating chambers 12 defined by a plurality of partition walls 11 in the width direction. A communication portion 13 constituting a part of the reservoir 100 serving as a common ink chamber of the pressure generation chamber 12 is formed, and is connected to one end portion in the longitudinal direction of each pressure generation chamber 12 via the ink supply path 14. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13.

Further, on the opening surface side of the flow path forming substrate 10, on the side opposite to the ink supply path 14 of each pressure generating chamber 12 through a protective film or the like used as a mask when forming the pressure generating chamber 12. A nozzle plate 20 having a communicating nozzle opening 21 is fixed at room temperature via an adhesive, a heat-welded film, or the like. The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm, a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ⁻⁶ / ° C.] It consists of stainless steel (SUS). The nozzle plate 20 entirely covers one surface of the flow path forming substrate 10 on one surface, and also serves as a reinforcing plate that protects the silicon single crystal substrate from impact and external force.

  On the other hand, an elastic film 50 made of silicon dioxide and having a thickness of, for example, about 1.0 μm is formed on the side opposite to the opening surface of the flow path forming substrate 10. An insulator film 55 made of zirconium oxide or the like and having a thickness of, for example, about 0.4 μm is formed. Further, the insulator film 55 is made of platinum, iridium or the like and has a thickness of, for example, a lower electrode film 60 of about 0.2 μm and lead zirconate titanate (PZT) or the like. The piezoelectric element 300 is configured by laminating a 1.0 μm piezoelectric layer 70 and an upper electrode film 80 made of iridium or the like and having a thickness of, for example, about 0.05 μm. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. Further, here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the example described above, the elastic film 50, the insulator film 55, and the lower electrode film 60 function as a diaphragm.

  Here, each upper electrode film 80, which is an individual electrode of the piezoelectric element 300, is drawn from the vicinity of the end opposite to the ink supply path 14 as shown in FIG. A lead electrode 90 made of, for example, gold (Au) or the like is connected to the elastic film 50 in a region facing between the columns.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, that is, on the lower electrode film 60, the elastic film 50, and the lead electrode 90, a protection having a reservoir portion 31 constituting at least a part of the reservoir 100. The substrate 30 is bonded via an adhesive 34. In the present embodiment, the reservoir portion 31 is formed through the protective substrate 30 in the thickness direction and across the width direction of the pressure generation chamber 12. As described above, the communication portion 13 of the flow path forming substrate 10. The reservoir 100 is configured as a common ink chamber for the pressure generation chambers 12.

  A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The piezoelectric element holding portion 32 is formed to have a size that integrally covers the plurality of piezoelectric elements 300, and each piezoelectric element 300 is disposed in the piezoelectric element holding portion 32. Thereby, each piezoelectric element 300 is protected in a state hardly affected by the external environment. Note that the piezoelectric element holding portion 32 is not necessarily sealed.

  As such a protective substrate 30, it is preferable to use substantially the same material as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10 is used. The silicon single crystal substrate was used.

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end of the lead electrode 90 drawn from the upper electrode film 80 of each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  Further, a rigid flexible wiring board 120 on which a driving circuit 110 for driving the piezoelectric element 300 is mounted is fixed on the protective substrate 30, and a lead electrode that is a lead-out wiring led out from the driving circuit 110 and the piezoelectric element 300. 90 is electrically connected via a rigid flexible wiring board 120.

  Specifically, the rigid flexible wiring board 120 is configured by laminating a flexible flexible board 121 and a rigid rigid board 122 made of glass epoxy or the like. The rigid flexible wiring board 120 includes a drive circuit. A connection wiring 123 that electrically connects 110 and the lead electrode 90 is provided.

  The flexible substrate 121 is made of polyimide or the like having a size that covers the upper surface of the protective substrate 30.

  The rigid substrate 122 is fixed to the flexible substrate 121 in a region facing the through hole 33 of the protective substrate 30. In this embodiment, the rigid substrate 122 is provided on the lead electrode 90 side and the opposite side of the flexible substrate 121, and the flexible substrate 121 is sandwiched between the two rigid substrates 122. The rigid substrate 122 has a smaller area than the through hole 33 of the protective substrate 30, and the rigid substrate 122 can be inserted into the through hole 33.

  Such a rigid flexible wiring board 120 has a flexible flexible area 121 a composed only of the flexible board 121 and an inflexible rigid area 122 a composed of the flexible board 121 and the rigid board 122. Since the rigid flexible wiring board 120 is provided in a region where the rigid substrate 122 is opposed to the through hole 33 of the protective substrate 30, the rigid region 122 a where the rigid substrate 122 is provided is a lead electrode in the through hole 33. 90 is connected.

  Further, in the rigid flexible wiring board 120 of the present embodiment, the flexible region 121a composed only of the flexible substrate 121 in which the rigid substrate 122 is not provided is a region other than the region facing the through hole 33, The drive circuit 110 is mounted on a portion of the flexible region 121a that is bonded to the protective substrate 30. That is, the drive circuit 110 is fixed on the protective substrate 30 via the flexible substrate 121 of the rigid flexible wiring substrate 120. In the present embodiment, the region where the drive circuit 110 of the rigid flexible wiring board 120 is mounted is configured only by the flexible substrate 121, and the drive circuit 110 is mounted on the flexible region 121a. Instead, for example, a rigid board may be provided in a region where the drive circuit 110 of the rigid flexible wiring board 120 is mounted, and the drive circuit 110 may be mounted in the rigid region 122a.

  Here, the connection wiring 123 that actually connects the drive circuit 110 and the lead electrode 90 includes a flexible wiring 124 provided on the flexible substrate 121 and a rigid wiring 125 provided on the rigid substrate 122.

  The flexible wiring 124 is provided on the surface side of the flexible substrate 121 that is bonded to the protective substrate 30. The rigid wiring 125 is provided so as to penetrate the rigid substrate 122, and electrically connects the flexible wiring 124 and the lead electrode 90. The drive circuit 110 and the lead electrode 90 are electrically connected via the connection wiring 123.

  By using such a rigid flexible wiring board 120, there is a step between the protective substrate 30 to which the drive circuit 110 is fixed and the flow path forming substrate 10 on which the lead electrode 90 drawn from the piezoelectric element 300 is provided. Even so, both can be easily and reliably electrically connected without using a bonding wire or the like.

  As shown in FIG. 1, the flexible substrate 121 of the rigid flexible wiring substrate 120 is extended so as to be an external wiring to which an external drive signal or the like is input as it is. As a result, the step of connecting the external wiring becomes unnecessary, the work process can be simplified, and the number of parts can be reduced. Of course, external wiring may be connected to the rigid flexible wiring board 120, or external wiring may be connected to the drive circuit 110.

  Examples of the drive circuit 110 mounted on the rigid flexible wiring board 120 include a circuit board and a semiconductor integrated circuit (IC). The drive circuit 110 is mounted on such a rigid flexible wiring board 120 by flip chip mounting, for example. Further, as a method of mounting the drive circuit 110 on the rigid flexible wiring board 120, metal connection such as gold (Au) -gold (Au) connection, gold (Au) -tin (Sn) connection, ACF (anisotropic) Conductive paste), ACP (anisotropic conductive film), solder bump connection, or the like can be used.

  Further, the connection wiring 123 of the rigid flexible wiring board 120 and the lead electrode 90 can be connected by, for example, ACF or ACP. Such a connection between the rigid flexible wiring board 120 and the lead electrode 90 is performed by heating and welding the rigid flexible wiring board 120 to the lead electrode 90 with a predetermined pressure. For this reason, when the flexible substrate 121 is heated to the flow path forming substrate 10 or the protection substrate 30, a pitch shift at the time of mounting occurs due to a difference in linear expansion coefficient, but the rigid substrate 122 is formed in a region connected to the lead electrode 90. By providing the rigid region 122a, the rigid substrate 122 can buffer the difference in linear expansion, prevent pitch deviation during mounting, and improve reliability.

  Further, in the connection using the rigid flexible wiring board 120, there is no need to connect the lead electrode 90 and the drive circuit 110 with a connection wiring such as a bonding wire, and it is possible to prevent a connection failure and a decrease in yield due to wire bonding. .

  Furthermore, since the rigid flexible wiring board 120 can connect the drive circuit 110 and the lead electrode 90 together, so-called gang bonding, the manufacturing process can be simplified, the manufacturing time can be shortened, and the manufacturing cost can be reduced. can do.

  In addition, since the rigid flexible wiring board 120 of the present embodiment is provided with the rigid board 122 on the lead electrode 90 side of the flexible board 121, the bending amount of the flexible board 121 can be reduced depending on the thickness of the rigid board 122. it can. That is, it is not necessary to bend the flexible substrate 121 to the surface of the flow path forming substrate 10, the disconnection of the connection wiring 123 can be reliably prevented, and the rigid flexible wiring substrate 120 and the lead electrode 90 can be easily connected. Can be done.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and the sealing film 41 seals one surface of the reservoir portion 31. It has been stopped. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  An ink introduction port 44 for supplying ink to the reservoir 100 is formed on the compliance substrate 40 on the outer side of the central portion of the reservoir 100 in the longitudinal direction. Further, the protective substrate 30 is provided with an ink introduction path 35 that allows the ink introduction port 44 and the side wall of the reservoir 100 to communicate with each other.

  In such an ink jet recording head of this embodiment, ink is taken in from an ink introduction port 44 connected to an external ink supply means (not shown), and the interior is filled with ink from the reservoir 100 to the nozzle opening 21. In accordance with the recording signal from 110, a voltage is applied between each of the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the lower electrode film 60, and the piezoelectric layer 70 are bent and deformed. By doing so, the pressure in each pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle openings 21.

(Embodiment 2)
FIG. 3 is a cross-sectional view and an enlarged cross-sectional view of a main part of an ink jet recording head according to Embodiment 2 of the present invention.

  As shown in FIG. 3, the rigid flexible wiring board 120 </ b> A of this embodiment is configured by joining a rigid board 122 </ b> A to the opposite side of the flexible board 121 from the lead electrode 90. Further, a flexible wiring 124 is provided on the surface of the flexible substrate 121 opposite to the rigid substrate 122 </ b> A, and the flexible wiring 124 is directly connected to the lead electrode 90. That is, in this embodiment, the flexible wiring 124 is the connection wiring 123A.

  Even when such a rigid flexible wiring board 120A is used, the linear expansion difference of the flexible board 121 can be buffered by the rigid board 122A, and the occurrence of pitch deviation during mounting can be reduced.

(Other embodiments)
While the embodiments of the present invention have been described above, the basic configuration of the ink jet recording head is not limited to that described above. For example, in the first and second embodiments described above, the flexible wiring 124 is provided on the side of the flexible substrate 121 to be bonded to the protective substrate 30. However, the present invention is not limited to this, and for example, the drive circuit 110 of the flexible substrate 121. The flexible wiring 124 may be provided on the surface side on which is mounted. Of course, you may provide the flexible wiring 124 on both surfaces of the flexible substrate 121. FIG.

  Further, for example, in the first and second embodiments described above, the piezoelectric element holding part 32 is provided on the protective substrate 30 and the piezoelectric element 300 is formed in the piezoelectric element holding part 32. However, the present invention is not limited to this. The piezoelectric element holding portion 32 may not be provided on the protective substrate 30. In this case, the surface of the piezoelectric element 300 may be covered with a protective film made of an inorganic material such as alumina to prevent destruction of the piezoelectric layer 70 due to moisture (humidity). Of course, the piezoelectric element 300 covered with the protective film may be provided in the piezoelectric element holding portion 32.

  Further, for example, in the first and second embodiments described above, a thin film type ink jet recording head manufactured by applying film formation and lithography methods is taken as an example, but the present invention is of course not limited thereto. The present invention can also be applied to a thick film type ink jet recording head formed by a method such as attaching a green sheet.

  Further, such an ink jet recording head constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 4 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 4, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  In the above-described embodiment, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is intended for a wide range of liquid ejecting heads, and is a liquid that ejects liquids other than ink. Of course, the present invention can also be applied to an ejection head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (surface emitting displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 2 is a perspective view of a recording head according to Embodiment 1 of the invention. FIG. 3 is a cross-sectional view of the recording head according to the first embodiment of the invention. FIG. 6 is a cross-sectional view of a recording head according to Embodiment 2 of the invention. It is the schematic which shows an example of the recording device which concerns on one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board | substrate, 31 Reservoir part, 32 Piezoelectric element holding part, 40 Compliance board | substrate, 60 Lower electrode film, 70 Piezoelectric layer, 80 Upper electrode Membrane, 90 lead electrode, 100 reservoir, 110 drive circuit, 120 rigid flexible wiring substrate, 121 flexible substrate, 122 rigid substrate, 121a flexible region, 122a rigid region, 123 connection wiring, 300 piezoelectric element

Claims (6)

A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting droplets is formed, and a pressure change is generated in the pressure generating chamber provided on one side of the flow path forming substrate via a vibration plate. A rigid flexible wiring comprising: a piezoelectric element to be bonded; and a protective substrate bonded to a surface of the flow path forming substrate on the piezoelectric element side, wherein the rigid substrate and a flexible substrate are laminated on the protective substrate. A drive circuit mounted on a substrate is provided, and a rigid region having the rigid substrate of the rigid flexible wiring substrate is electrically connected to a lead-out wiring drawn out from the piezoelectric element onto the flow path forming substrate. A liquid ejecting head characterized by being made. The liquid ejecting head according to claim 1, wherein the driving circuit is mounted in a flexible region including only the flexible substrate of the rigid flexible wiring substrate. The liquid ejecting head according to claim 1, wherein the rigid board of the rigid flexible wiring board is connected to the lead-out wiring. The liquid ejecting head according to claim 1, wherein the flexible substrate is connected to the lead-out wiring in the lead-out wiring. 5. The liquid jet head according to claim 1, wherein the lead-out wiring of the piezoelectric element and the rigid flexible wiring board are connected by thermal welding. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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