JP2011152740A - Inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head which permits densification and miniaturization and manpower reduction to be realized at the same time and upper and lower pressure chambers to be operated independently by arranging a common wiring layer between the upper pressure chamber and the lower pressure chamber arranged one above the other in a two-stage structure. <P>SOLUTION: The inkjet head discharges ink from nozzles by a pressure generation means, and has a first layer 10 in which a first pressure chamber 11 is formed and which has a first pressure generation means arranged in a first vibration plate 13 forming part of the wall of the first pressure chamber 11, a second layer 20 in which a second pressure chamber 21 is formed and which has a second pressure generation means arranged in a second vibration plate 23 forming part of the wall of the second pressure chamber 21, and a wiring layer 30 in which wiring is formed to apply voltage to the first pressure generation means of the first layer 10 and the second pressure generation means of the second layer 20, respectively. The wiring layer 30 is arranged between the first layer 10 and the second layer 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink-jet head, and more particularly to an ink-jet head that achieves higher density and smaller size by three-dimensionally arranging pressure chambers in a plurality of layers.

  Inkjet printers capable of high-definition drawing are desired for light printing applications, and high integration of inkjet heads is a market need.

  The inkjet head uses a piezoelectric element such as PZT that converts electrical signals into mechanical energy as pressure generating means for ejecting ink from the nozzles, and a diaphragm formed on one surface of the pressure chamber is vibrated by the piezoelectric element. Thus, it is known that the ink in the pressure chamber is changed in pressure for discharging from the nozzle. Unlike the thermal method, which uses a heater that converts electrical signals into thermal energy to change the pressure for ejection to the ink in the pressure chamber, the pressure chamber needs to be large, so it is physically integrated. There is a limit.

  For this reason, conventionally, there has been proposed a technique that enables high-pressure integration of pressure chambers by stacking the pressure chambers in two stages in the vertical direction (Patent Documents 1, 2, and 3).

JP 2001-146010 A JP 2005-153001 A JP 2005-231258 A

  In the techniques described in Patent Documents 1 and 2, the pressure chambers are stacked in two upper and lower stages by stacking two layers in which the pressure chambers are arranged in a plane. Accordingly, wiring for applying a voltage to the piezoelectric elements provided in the pressure chambers of each layer is required for each layer. As a result, the number of steps for producing the ink jet head is increased and the yield is deteriorated, resulting in an increase in cost.

  In addition, the technique described in Patent Document 2 can reduce the number of piezoelectric elements with respect to the number of nozzles by arranging one piezoelectric element in common between two pressure chambers stacked in two upper and lower stages. When one of the two pressure chambers sharing the piezoelectric element is ejecting ink, the other cannot eject ink. That is, since the two pressure chambers that share the piezoelectric element cannot be operated independently, there is a problem of adversely affecting the droplet amount control.

  Therefore, the present invention can simultaneously increase the density and reduce the size and simplify the man-hours by arranging a common wiring layer between the pressure chambers arranged in two upper and lower stages. It is an object of the present invention to provide an ink jet head capable of operating a pressure chamber independently.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

The invention according to claim 1 is an ink jet head that discharges ink from a nozzle by pressure generating means,
A first layer having a first pressure chamber formed and having a first pressure generating means disposed on a first diaphragm forming a part of a wall surface of the first pressure chamber;
A second layer having a second pressure generating means disposed on a second diaphragm forming a second pressure chamber and forming a part of a wall surface of the second pressure chamber;
A wiring layer on which wirings for applying a voltage are respectively applied to the first pressure generating means of the first layer and the second pressure generating means of the second layer;
In the inkjet head, the wiring layer is disposed between the first layer and the second layer.

According to a second aspect of the present invention, the first pressure generating means is formed on the bottom surface of the first layer,
The inkjet head according to claim 1, wherein the second pressure generating unit is formed on a top surface of the second layer.

  According to a third aspect of the present invention, the wiring layer includes, on one surface, the first pressure generating unit of the first layer and the wiring for applying a voltage to the first pressure generating unit. A first electrical connection means for electrical connection, and the second surface generating means of the second layer on the other surface and the voltage for applying a voltage to the second pressure generating means 3. The ink jet head according to claim 1, further comprising a second electrical connection means for electrically connecting the wiring.

According to a fourth aspect of the present invention, the second layer has a nozzle plate in which nozzles are formed,
4. The ink jet head according to claim 1, further comprising an ink discharge channel that communicates the first pressure chamber and the nozzle across the second layer and the wiring layer. 5. It is.

The invention according to claim 5 has a common ink chamber for supplying ink to the first pressure chamber and the second pressure chamber in an upper layer of the first layer,
5. The ink supply flow path that communicates between the common ink chamber and the second pressure chamber across the first layer and the wiring layer. 6. It is an inkjet head of description.

  According to the present invention, by arranging a common wiring layer between the pressure chambers arranged in two upper and lower stages, it is possible to simultaneously achieve high density and miniaturization and simplification of man-hours. An ink jet head capable of operating the pressure chambers independently can be provided.

1 is a partial cross-sectional view showing a layer structure of an inkjet head according to the present invention The perspective view which looked at the ink jet head concerning the present invention from the nozzle side Plane perspective view showing arrangement of pressure chambers The figure explaining the production method of a wiring layer The figure explaining the production method of a wiring layer FIG. 6 illustrates a method for manufacturing an inkjet head

  The present invention is an ink jet head that discharges ink from a nozzle by a pressure generating means, in which a first pressure chamber is formed and disposed on a first diaphragm that forms a part of the wall surface of the first pressure chamber. A first layer having a first pressure generating means and a second pressure chamber are formed and disposed on a second diaphragm that forms part of the wall surface of the second pressure chamber. A second layer having second pressure generating means, and wiring for applying a voltage to each of the first pressure generating means of the first layer and the second pressure generating means of the second layer are formed. And the wiring layer is disposed between the first layer and the second layer.

  Since the first pressure chamber and the second pressure chamber are arranged in a matrix in the first layer and the second layer, respectively, the first pressure chamber and the second pressure chamber are arranged in two upper and lower stages. As a result, the density and size of the inkjet head can be reduced. The wiring for applying a voltage to the first pressure generating means of the first layer and the second pressure generating means of the second layer is formed in a common wiring layer, and this wiring layer is the first layer. And the second layer, the man-hours can be simplified as compared with the case where the wiring is formed in each layer. Moreover, according to the present invention, the first pressure chamber and the second pressure chamber are provided in the first pressure chamber and the second pressure chamber, respectively. Can be operated.

  As the pressure generating means, a piezoelectric element that is an electromechanical conversion element that converts an electrical signal into mechanical energy is used. In general, PZT is preferably used as such a piezoelectric element.

  In the first pressure chamber provided in the first layer, the bottom wall of the wall surface is the first diaphragm, and the first diaphragm is placed on the bottom surface (the outer surface of the first pressure chamber) of the first diaphragm. One pressure generating means is provided. Therefore, the first pressure generating means is formed on the bottom surface of the first layer. The second pressure chamber provided in the second layer has a ceiling wall of the wall surface as the second diaphragm, and the top surface of the second diaphragm (the outer surface of the second pressure chamber). ) Is provided with second pressure generating means. Therefore, the second pressure generating means is formed on the top surface of the second layer.

  In the ink jet head of the present invention, the surface where the nozzle opens is defined as the lower surface, and the opposite surface is defined as the upper surface. Accordingly, in the present invention, the lower wall and the surface when the nozzle is disposed so that the surface on which the nozzle is opened are referred to as the bottom wall and the bottom surface, respectively, and the upper wall and the surface are respectively the ceiling wall and the top surface. That's it.

  The wiring layer has, on one surface, first electrical connection means for electrically connecting the first pressure generating means of the first layer and the wiring for applying a voltage to the first pressure generating means. A second electrical connecting means for electrically connecting the second pressure generating means of the second layer and a wiring for applying a voltage to the second pressure generating means on the other surface have. The wiring layer is disposed so that the one surface faces the first layer and the other surface faces the second layer, and is laminated between the first layer and the second layer. In this laminated state, the first electrical connection means of the wiring layer is electrically connected to the first pressure generating means of the first layer, and the second electrical connection means of the wiring layer is the first It is electrically connected to the second pressure generating means of the two layers.

  In the present invention, the second layer has a nozzle plate. The nozzles respectively corresponding to the first pressure chamber and the second pressure chamber are formed on the nozzle plate constituting the bottom surface of the second layer (the surface on the side opposite to the stacked side of the first layer and the wiring layer). . For this reason, an ink discharge flow path for communicating the first pressure chamber of the first layer and the nozzle formed on the bottom surface of the second layer extends over the second layer and the wiring layer. It is formed so as to penetrate.

  Further, in the present invention, common ink is supplied to the first pressure chamber and the second pressure chamber on the upper layer of the first layer (the layer on the side opposite to the stacked side of the second layer and the wiring layer). It can have an ink chamber. In this case, an ink supply channel for communicating the common ink chamber and the second pressure chamber is formed across the first layer and the wiring layer.

  Next, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view showing a layer structure of an ink jet head according to the present invention, FIG. 2 is a perspective view of the ink jet head according to the present invention as viewed from the nozzle side, and FIG. 3 is a plan view showing an arrangement structure of pressure chambers. FIG.

  As shown in FIG. 1, the inkjet head 1 is formed by laminating a plurality of layers, and a first pressure chamber 11 and a second pressure chamber 21 into which ink is supplied are respectively laminated in a laminating direction. Are arranged three-dimensionally in two stages in the illustrated vertical direction.

  A large number of first pressure chambers 11 are formed in a matrix form in the left-right direction in FIG. 1 by being etched in the thickness direction of the Si (silicon) substrate 12. A part of the bottom wall 111 of the first pressure chamber 11 constitutes a thin-walled first diaphragm 13 by leaving the Si substrate 12 etched, and the bottom surface of the first diaphragm 13 ( On the outer surface of the first diaphragm 13, there is provided a piezoelectric element 14 that is a first pressure generating unit that applies pressure for ejection to the ink in the first pressure chamber 11. The piezoelectric element 14 has an upper electrode and a lower electrode (not shown).

  A top plate 16 made of a Si substrate is laminated on the upper surface of the Si substrate 12 via an adhesive layer 15 made of a photosensitive dry film. In the present embodiment, the first actuator layer 10 that is the first layer is configured by the Si substrate 12, the piezoelectric element 14, the adhesive layer 15, and the top plate 16. Therefore, the piezoelectric element 14 is disposed on the bottom surface of the first actuator layer 10.

  On the other hand, the second pressure chambers 21 are formed in a matrix form in the left-right direction in FIG. 1 by being etched in the thickness direction of the Si substrate 22. A part of the ceiling wall 211 of the second pressure chamber 21 constitutes a thin-walled second diaphragm 23 by leaving the Si substrate 22 etched, and the top surface of the second diaphragm 23 A piezoelectric element 24 as second pressure generating means for applying pressure for ejection to the ink in the second pressure chamber 21 is provided on the outer surface of the second diaphragm 23. The piezoelectric element 24 has an upper electrode and a lower electrode (not shown).

  As shown in FIG. 3, the first pressure chamber 11 and the second pressure chamber 21 are arranged so as to partially overlap each other in plan view. For this reason, the horizontal expansion of the 1st pressure chamber 11 and the 2nd pressure chamber 21 is suppressed, and density increase and size reduction are further exhibited.

  On the lower surface of the Si substrate 22, a nozzle plate 26 made of an Si substrate is laminated via an adhesive layer 25 made of a photosensitive dry film. In the present embodiment, the Si actuator 22, the piezoelectric element 24, the adhesive layer 25, and the nozzle plate 26 constitute the second actuator layer 20 that is the second layer. Accordingly, in the second actuator layer 20, the piezoelectric element 24 is disposed on the top surface.

  The wiring layer 30 is disposed between the first actuator layer 10 and the second actuator layer 20, and the first actuator layer 10 and the second actuator layer 20 are separated by adhesive layers 361 and 362 made of a photosensitive dry film. It is joined.

  In the wiring layer 30, wirings 321 and 322 for applying a voltage to the piezoelectric elements 14 and 24 are patterned on both surfaces of the Si substrate 31. One end of the wiring 321 is disposed immediately below the upper electrode (not shown) of each piezoelectric element 14 of the first actuator layer 10, and one end of the wiring 322 is the upper electrode (each of the piezoelectric elements 24 of the second actuator layer 20). The other end is electrically connected to a drive circuit (not shown) that outputs a predetermined voltage.

The wiring 321 is insulated from the upper surface of the Si substrate 31 by an insulating film (SiO ₂ film) 331, and the upper surface of the wiring 321 is also insulated by being covered with the insulating film 331. In a portion corresponding to one end of the wiring 321 in the insulating film 331, the insulating film 331 is partially removed to form a non-insulating portion 341, and one end of the wiring 321 is exposed toward the upper surface. A contact portion 351 made of low melting point solder is formed so as to protrude upward at one end of the wiring 321 facing the non-insulating portion 341, and the piezoelectric element of the first actuator layer 10 where the contact portion 351 is located above. The piezoelectric element 14 and the wiring 321 are electrically connected by bonding to the upper electrode 14 (not shown).

  Similarly, the wiring 322 is insulated from the lower surface of the Si substrate 31 by the insulating film 332, and the lower surface of the wiring 322 is also insulated by being covered with the insulating film 332. In a portion of the insulating film 332 corresponding to one end of the wiring 322, the insulating film 332 is partially removed to form a non-insulating portion 342, and one end of the wiring 322 is exposed toward the lower surface. A contact portion 352 made of low melting point solder is formed at one end of the wiring 322 facing the non-insulating portion 342 so as to protrude downward, and the piezoelectric element of the second actuator layer 20 where the contact portion 352 is located below. The piezoelectric element 24 and the wiring 322 are electrically connected by bonding to the upper electrode 24 (not shown).

  In this way, the wiring 321 for the piezoelectric element 14 of the first pressure chamber 11 and the wiring 322 for the piezoelectric element 24 of the second pressure chamber 21 are collectively formed on both surfaces of one Si substrate 31. Therefore, voltage application to the piezoelectric elements 14 and 24 can be performed by the common wiring layer 30, and the piezoelectric elements 14 and 24 are operated independently in the first pressure chamber 11 and the second pressure chamber 21. be able to.

  Nozzles 261 and 262 for discharging ink in the first pressure chamber 11 and the second pressure chamber 21 are formed in the nozzle plate 26.

  The nozzle 261 communicates with the inside of the first pressure chamber 11 by the ink discharge channel 41, and when the piezoelectric element 14 is driven, the ink in the first pressure chamber 11 passes through the ink discharge channel 41 to be a nozzle. The ink is discharged from H.261. Since the first pressure chamber 11 is provided in the uppermost first actuator layer 10, the ink discharge flow path 41 passes vertically through the bottom wall 111 and the wiring layer 30 of the first pressure chamber 11, and The nozzles 261 formed on the nozzle plate 26 are communicated with each other through the second actuator layer 20. Ink supply to the first pressure chamber 11 is performed via an inlet 161 formed in the top plate 16. A common ink chamber 50 (FIG. 2) for supplying ink to the first pressure chamber 11 and the second pressure chamber 21 in common is formed on the outside of the top plate 16. The ink chamber 50 is opened facing the interior.

  On the other hand, the nozzle 262 communicates with the inside of the second pressure chamber 21, and ejects ink in the second pressure chamber 21 from the nozzle 262 when the piezoelectric element 24 is driven. Since the second pressure chamber 21 is provided in the lowest second actuator layer 20, the ink supply flow path 42 for supplying ink from the common ink chamber 50 includes the first actuator layer 10 and the wiring layer. 30 is communicated with an inlet 162 penetrating up and down in the top plate 16. The inlet 162 is open facing the common ink chamber 50.

  The wirings 321 and 322 formed in the wiring layer 30 are pattern-formed at positions avoiding the ink discharge flow channel 41 and the ink supply flow channel 42.

  In FIG. 2, 51 is an inflow pipe for inflow of ink into the common ink chamber 50, and 52 is an outflow pipe for outflow of ink from the common ink chamber 50.

  Next, a method for manufacturing the inkjet head 1 will be described with reference to FIGS.

  In the first actuator layer 10 and the second actuator layer 20, the first diaphragm 13 of the first pressure chamber 11 is constituted by the bottom wall 111 of the first pressure chamber 11, and the second diaphragm 23 of the second pressure chamber 21. Is constituted by the ceiling wall 211 of the second pressure chamber 21 and can be manufactured through a conventionally known laminating process except that both are vertically symmetrical. Therefore, here, a method for manufacturing the wiring layer 30 which is a feature of the present invention will be described with reference to FIGS.

First, a Si substrate 31 having a predetermined thickness as a substrate of the wiring layer 30 is prepared (FIG. 4A), and an insulating film 33 made of SiO _{2 is} formed on one surface of the Si substrate 31 by a CVD (Chemical Vapor Deposition) method. (FIG. 4B).

  Next, after the resist 100 is coated on the upper surface of the insulating film 33, the resist 100 is patterned by exposure and development, and the resist 100 in the region 321a to be the wiring 321 is removed to expose the insulating film 33 (FIG. 4 ( c)), a metal material for forming the wiring 321, for example, Al is coated by sputtering or the like, and the metal film 32 is formed on the entire upper surface of the insulating film 33 and the resist 100 (FIG. 4D).

After the metal film 32 is formed, the resist 100 is removed, thereby forming a wiring 321 having a predetermined pattern on the upper surface of the insulating film 33 (FIG. 4E). Thereafter, an insulating film 33 made of SiO ₂ is further formed on the entire upper surface including the wiring 321 by the CVD method, and the wiring 321 is covered with the insulating film 33 (FIG. 4F).

  Next, after the resist 100 is again coated on the upper surface of the insulating film 33, the resist 100 is patterned by exposure and development processing, and a region 321 b corresponding to one end of the wiring 321, a region 321 c corresponding to the ink discharge channel 41, and The resist 100 in the region 321d corresponding to the ink supply flow path 42 is removed to expose the insulating film 33 (FIG. 4G), and the regions 321b to 321d are exposed by the RIE (Reactive Ion Etching) method. The insulating film 33 at the site is etched. Here, the wiring 321 is formed immediately below the region 321b, and the wiring 321 is not formed immediately below the region 321c and the region 321d, and directly covers the Si substrate 31 (FIG. 4H). ).

  Thereafter, when the resist 100 is removed, the wiring 321 covered with the insulating film 331 after etching is formed on one surface of the Si substrate 31, and one end of the wiring 321 is exposed by the non-insulating portion 341. Thereby, the wiring 321 for the piezoelectric element 14 of the first actuator layer 10 is formed on the Si substrate 31. Further, the surfaces of the Si substrate 31 are exposed in the regions 321c and 321d corresponding to the ink discharge flow channel 41 and the ink supply flow channel 42, respectively (FIG. 5A).

  Similarly, a non-insulating portion 342 and recessed regions 322c and 322d are formed in the insulating film 332 on the other surface of the Si substrate 31, respectively, and a wiring 322 having one end exposed in the non-insulating portion 342 is formed. (FIG. 5B).

Next, etching is performed on both surfaces by the RIE method, and part of the insulating films 331 and 332 and the Si substrate 31 are removed. By making the etching rate of SiO ₂ slower than Si, the Si substrate 31 can be deeper than the insulating films 331 and 332. As a result, the ink discharge flow channel 41 and the ink supply flow channel 42 are formed to penetrate each other (FIG. 5C).

  Thereafter, the adhesive layers 361 and 362 are further coated on the upper surface of the insulating film 331 and the lower surface of the insulating film 332, which are patterned by exposure and development processing, and correspond to the ink discharge flow channel 41 and the ink supply flow channel 42. The site to be removed is removed (FIG. 5D).

  Next, contact portions 351 and 352 are formed on the wirings 321 and 322 exposed to the non-insulating portions 341 and 342 by applying a low melting point solder paste (FIG. 5E). Thereby, the wiring layer 30 is produced.

  As shown in FIG. 6, the wiring layer 30 thus manufactured is positioned between the pair of crimping machines 200 and 200 in the order of the first actuator layer 10, the wiring layer 30, and the second actuator layer 20 from the top. Then, after the laminated arrangement, the crimping machines 200 and 200 are tightened to be laminated together and crimped. At this time, by applying heat with a heater (not shown), the contact portions 351 and 352 made of low melting point solder are melted and joined to the upper electrodes of the corresponding piezoelectric elements 14 and 24, respectively. The first actuator layer 10, the wiring layer 30, and the second actuator layer 20 are joined together by the adhesive layers 361 and 362 at the same time as the electrical connection between the corresponding wirings 321 and 322 is achieved.

  In the present invention, the contact portions 351 and 352 are not limited to the low melting point solder, but the first actuator layer 10, the wiring layer 30, and the second actuator layer 20 are laminated and integrated by using the low melting point solder as shown in the present embodiment. When the heat treatment is applied, heat and heat can be applied to obtain bonding and electrical connection between the piezoelectric elements 14 and 24 and the contact portions 351 and 352 at a time. Moreover, since the contact portions 351 and 352 can be simultaneously bonded to the piezoelectric element 14 of the first pressure chamber 11 and the piezoelectric element 24 of the second pressure chamber 21 in different layers, for example, when the contact portion of one layer is heated. In addition, the problem that the contact portion of the other layer melts can be avoided, and the manufacturing process can be simplified, which is preferable.

1: Inkjet head 10: First actuator layer 11: First pressure chamber 111: Bottom wall 12: Si substrate 13: First vibration plate 14: Piezoelectric element 15: Adhesive layer 16: Top plate 161, 162: Inlet 20: Second actuator layer 21: Second pressure chamber 211: Bottom wall 22: Si substrate 23: Second diaphragm 24: Piezoelectric element 25: Adhesive layer 26: Nozzle plate 261, 262: Nozzle 30: Wiring layer 31: Si substrate 32: Metal film 321, 322: Wiring 33, 331, 332: Insulating film 341, 342: Non-insulating part 351, 352: Contact part 361, 362: Adhesive layer 41: Ink ejection flow path 42: Ink supply flow Path 50: Common ink chamber 51: Inflow pipe 52: Outflow pipe

Claims (5)

An ink jet head that discharges ink from a nozzle by pressure generating means,
A first layer having a first pressure chamber formed and having a first pressure generating means disposed on a first diaphragm forming a part of a wall surface of the first pressure chamber;
A second layer having a second pressure generating means disposed on a second diaphragm forming a second pressure chamber and forming a part of a wall surface of the second pressure chamber;
A wiring layer on which wirings for applying a voltage are respectively applied to the first pressure generating means of the first layer and the second pressure generating means of the second layer;
The ink-jet head, wherein the wiring layer is disposed between the first layer and the second layer. The first pressure generating means is formed on the bottom surface of the first layer,
The inkjet head according to claim 1, wherein the second pressure generating unit is formed on a top surface of the second layer.   The wiring layer has a first surface for electrically connecting the first pressure generating means of the first layer and the wiring for applying a voltage to the first pressure generating means on one surface. Electrical connection means is provided, and on the other surface, the second pressure generating means of the second layer and the wiring for applying a voltage to the second pressure generating means are electrically connected. 3. The ink jet head according to claim 1, further comprising second electrical connection means. The second layer has a nozzle plate on which nozzles are formed,
4. The ink jet head according to claim 1, further comprising an ink discharge channel that communicates the first pressure chamber and the nozzle across the second layer and the wiring layer. 5. . A common ink chamber for supplying ink in common to the first pressure chamber and the second pressure chamber on an upper layer of the first layer;
5. The ink supply flow path that communicates between the common ink chamber and the second pressure chamber across the first layer and the wiring layer. 6. The inkjet head as described.

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