Patent Grant
11247463
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-045818, filed on Mar. 13, 2019, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a liquid discharge head, a method of manufacturing a liquid discharge head, and a liquid discharge apparatus.
As a liquid discharge head, a shear-mode shared-wall type liquid discharge head including a plurality of pressure chambers communicating with adjacent nozzles is known. In such a liquid discharge head, for example, a groove is formed at an end of a flat actuator substrate made of piezoelectric ceramics (e.g., PZT) to form a pressure chamber, and side plates are arranged on both sides of the actuator substrate to form a space serving as a common liquid chamber. The side plates are formed of a free-cutting ceramic (Macerite, Photoveel, or the like) of which workability is close to that of a piezoelectric ceramic PZT, and the actuator substrate is then polished together with the side plates to form a bonding surface that can be bonded to a nozzle plate.
Embodiments provide a liquid discharge head that can be easily manufactured, a method of manufacturing a liquid discharge head, and a liquid discharge apparatus.
In general, according to an embodiment, a liquid discharge head includes an actuator base, a case member, and a nozzle plate. The actuator base includes a plurality of grooves arranged in a first direction. Each of the grooves extends in a second direction crossing the first direction. The actuator base is formed of a piezoelectric ceramic material. The case member includes a frame portion spaced from the actuator base in the second direction. The frame portion having an end surface in a third direction orthogonal to the first and second direction that is level with an end surface of the actuator base in the third direction. The frame portion being formed of a ceramic material having aluminum titanate as a main component. The nozzle plate is contacting the end surface of the frame portion and the end surface of the actuator base.
Hereinafter, an inkjet head 1, which is a type of liquid discharge head, and an inkjet printer 100, which is type of a liquid discharge apparatus, will be described with reference to
The inkjet head 1 shown in
The inkjet head 1 includes an actuator base 10, a nozzle plate 20 having a plurality of nozzles 21, a cover plate 30, which is also referred to as a cover member, and a case member 40.
The actuator base 10 includes a substrate 12 and a laminated piezoelectric body 13, which is a piezoelectric section.
The substrate 12 is formed in a rectangular plate shape. The substrate 12 is preferably formed of PZT, ceramics, glass, free-cutting ceramics, or materials containing these materials.
The laminated piezoelectric body 13 is positioned at the end edge of the substrate 12 on the nozzle plate 20 side. The laminated piezoelectric body 13 is formed by laminating two piezoelectric members. The piezoelectric members are formed of, for example, a lead zirconate titanate (PZT)-based ceramic material. Additionally, as the piezoelectric member, a lead-free piezoelectric ceramic such as potassium sodium niobate (KNN) may be used in consideration of environment. The two piezoelectric members are polarized to have opposite polarization directions and bonded via an adhesive layer.
A groove row 14A including a plurality of grooves 14 aligned in a first direction is formed on an end surface of the laminated piezoelectric body 13 facing the nozzle plate 20. A shape along an XZ plane of the laminated piezoelectric body 13 is a comb teeth shape. A support-like portion formed between the grooves 14 adjacent to each other forms a laminated piezoelectric element 15 serving as a driving section that changes the volume of the grooves 14. In other words, in the laminated piezoelectric body 13, a plurality of the laminated piezoelectric elements 15 are aligned in the first direction and the groove 14 is formed between the laminated piezoelectric elements 15 adjacent to each other.
In the groove row 14A, a plurality of first grooves 14a forming pressure chambers C1, and a plurality of second grooves 14b forming air chambers C2 are alternately arranged in the first direction. The plurality of grooves 14 are arranged side by side in the first direction, extend along the second direction, and are arranged in parallel to one another. The grooves 14a and 14b are respectively formed over the entire length in the second direction of the actuator base 10. That is, the grooves 14a and 14b are open on the nozzle plate 20 side and the cover plate 30 side. On an inner bottom portion and both side surfaces of each of the grooves 14a and 14b, electrodes 16 are formed.
Both ends in the second direction of the first groove 14a are open on an inner side of a frame section 40a that is a first member to communicate with a common chamber C3. The nozzle 21 is provided at a position facing the first groove 14a. That is, the first groove 14a forms the pressure chamber C1 that communicates with the common chamber C3 and communicates with the nozzle 21.
Both end portions of the second grooves 14b in the second direction are covered by the cover plate 30 in the frame section 40a. The second groove 14b is closed to form the air chamber C2 separated from the common chamber C3 and the pressure chamber C1.
The laminated piezoelectric elements 15 are disposed among the plurality of grooves 14 on one end side of the actuator base 10. That is, the plurality of laminated piezoelectric elements 15 are arranged side by side in the first direction. Each laminated piezoelectric element 15 includes a first piezoelectric element 15a, and a second piezoelectric element 15b laminated on the first piezoelectric element 15a. One side end surface of the actuator base 10, which is the upper surface side in
The electrode 16 is a conductive film formed of a conductive material such as nickel. The electrode 16 is formed from a bottom portion of each of the grooves 14a and 14b to an upper surface of the substrate 12 and is connected to a wiring pattern 17. The electrode 16 is formed by, for example, a method such as a vacuum deposition method or an electroless nickel plating method. For example, with an electroless plating method, a metal film can be easily formed even in the fine groove 14. In the present embodiment, the material of the electrode 16 is nickel, but is not limited to thereto.
The electrode 16 may be formed of, for example, gold or copper. Alternatively, the electrode 16 may be a laminate of two or more conductive films.
The wiring pattern 17 is, for example, a conductive film formed of a conductive material such as nickel similarly to the electrode 16 and having a predetermined pattern shape. The wiring pattern 17 is formed on a pair of principal surfaces 10a and 10b of the actuator base 10. For example, the wiring pattern 17 is formed at the same time when the electrode 16 is formed by a method such as a vacuum deposition method or an electroless plating method. The portion on the other side of the substrate 12 in the Z direction is exposed outside a frame member. Therefore, a driving circuit can be connected to the wiring pattern 17 disposed in this portion by flexible printed circuit (FPC) or the like.
For example, the nozzle plate 20 is formed of a polyimide film having a thickness of 10 μm to 100 μm into a rectangular plate shape. In the nozzle plate 20, a nozzle array which has the plurality of nozzles 21 penetrating the nozzle plate in a thickness direction is formed. The nozzle plate 20 is disposed so as to face to cover the opening in the second direction of the groove row 14A on one end side of the actuator base 10. The nozzles 21 are provided at positions corresponding to the plurality of pressure chambers C1. That is, the nozzle plate 20 has a nozzle 21 communicating with a pressure chamber C1 formed by a first groove 14a, but the nozzle plate 20 covers (closes) the opening of the second groove 14b.
The cover plate 30 is formed of, for example, a dry film resist. Specifically, the cover plate 30 is formed using, for example, an epoxy resin-based photoresist as a permanent film (permanent resist). For example, the cover plate 30 has a film thickness of about 40 μm to 50 μm, and is provided on each of both end surfaces of the actuator base 10.
The cover plate 30 is a rectangular plate-like member with an edge portion on the nozzle plate side being formed in a comb teeth shape such that ends (Y-direction) of the first grooves 14a are open. In the edge portion of the cover plate 30, a plurality of cutout sections 31 are formed corresponding in position to grooves 14a. That is, the cover plate 30 has the plurality of cutout sections 31, and a plurality of cover pieces 32 alternating with the plurality of cutout sections 31. The end surface of the cover piece 32 on the nozzle plate side forms the nozzle facing surface 30c. The cutout section 31 is formed to penetrate the cover plate in a thickness direction of the cover plate 30, which is the Y axis direction. The cutout section 31 is disposed at a position corresponding to the first groove 14a. Therefore, both ends of each first groove 14a in the Y-direction are open inside of the frame section 40a and are not covered by a cover plate 30. Therefore, a pressure chamber C1 formed by the first groove 14a communicates with the common chamber C3 formed on the outer side of the cover plate 30. Liquid such as ink flows into the pressure chamber C1 through the cutout sections 31.
The cover piece 32 is disposed at a position corresponding to the second groove 14b. Therefore, the openings at the both ends of the second groove 14b in the Y-direction are closed off by cover pieces 32 of a cover plate 30 and the inflow of the ink is prevented for the second grooves 14b.
That is, the pressure chambers C1 communicating with the common chamber C3 and the closed air chambers C2 are alternately formed on one end side of the actuator base 10.
A case member 40 is integrally provided with the frame section 40a formed in a rectangular frame shape and a plate-like lid section 40b that closes an opening of the frame section 40a.
The frame section 40a is formed of a ceramic material having aluminum titanate as a main component. The frame section 40a surrounds the outer circumference of the actuator base 10 and covers the outer circumference of a part of the region of the actuator base 10. Specifically, the frame section 40a includes a pair of plate-like first frame pieces 41 joined to the end surface of the actuator base 10 in the first direction, and a pair of plate-like second frame pieces 42 arranged apart from each other by a predetermined distance on both the principal surfaces 10a and 10b, which are the outer surface of the actuator base 10.
The frame section 40a forms the common chamber C3 between the frame section 40a and the actuator base 10 covered by the cover plate 30. The common chamber C3 is formed on the inner side of the frame section 40a and the lid section 40b and communicates with the pressure chambers C1 through the cutout sections 31 of the cover plate 30.
The laminated piezoelectric body 13 extending in the first direction is disposed at the center of the common chamber C3 in the second direction. The frame section 40a plays a guide function for guiding liquid such as ink. An end surface, which is an opening edge, on one side of the frame section 40a on the upper side in
The nozzle facing surface 40c forms a flat plane along the XY plane. The nozzle facing surface 40c is flush with the nozzle facing surface 10c of the actuator base 10 and joined to the outer circumference of the nozzle plate 20. The lid section 40b is provided at an end edge, which is an opening edge, on the other side (the side opposite of the nozzle plate 20) of the frame section 40a on the lower side in
The lid section 40b is formed integrally with the frame section 40a. The lid section 40b is formed of, for example, a ceramic material having aluminum titanate, which is the same material as the frame section 40a, as a main component. The lid section 40b is a rectangular plate-like member having a supply port for causing ink to flow into the common chamber C3 from the outside and a discharge port for discharging the ink to the outside from the common chamber C3. A supply channel 133a is connected to the supply port and a collection channel 133b is connected to the discharge port. The lid section 40b closes one side of the opening of the frame section 40a to form the common chamber C3.
An actuator portion, which is a portion on the nozzle plate 20 side of the actuator base 10, is covered by the nozzle plate 20, the frame section 40a, and the lid section 40b. Various electronic components such as a driving circuit are mounted on the wiring patterns 17 in a portion extending to the outer side of the frame section 40a and the lid section 40b on the opposite side of the nozzle plate 20 in the actuator base 10.
The plurality of pressure chambers C1 communicating with the nozzles 21, the plurality of air chambers C2 closed by the cover plate 30, and the common chamber C3 communicating with the plurality of pressure chambers C1 are formed on the inside of the frame section 40a of the inkjet head 1 configured as described above. The inkjet head 1 circulates the ink in a channel passing through the pressure chambers C1 and the common chamber C3 formed on the inside.
A method of manufacturing an inkjet head 1 according to the present embodiment will be described with reference to
Specifically, an actuator base 10 without grooves 14 is formed first. For example, two plate-like piezoelectric members polarized in the plate thickness direction are laminated so that the polarization directions thereof are different, and the laminate is cut into a desired width and a desired length to form a laminated piezoelectric body 13.
Further, the laminated piezoelectric body 13 is attached to a plate-like substrate 12 formed of a material different from that of the piezoelectric member constituting the laminated piezoelectric body 13 with an adhesive or the like, and machined using a dicing saw or a slicer to form an actuator base 10 having a predetermined outer shape. For example, a block-like base member having a thickness of a plurality of sheets may be formed in advance and then separated to manufacture a plurality of actuator bases 10 having a predetermined shape.
Subsequently, as ACT 1, the first grooves 14a and the second grooves 14b are formed in the laminated piezoelectric body 13 of the actuator base 10 by machining. Further, conductive films such as the electrodes 16 and the wiring patterns 17 are formed at predetermined locations on the outer surface of the actuator base 10 including the inside of each of the grooves 14a and 14b by a vacuum deposition method or the like.
Subsequently, as ACT 2, a plate-like dry film resist 30A which becomes the cover plate 30 is attached to both surfaces of the actuator base 10. Specifically, for example, the plate-like dry film resist 30A is pressed against the both end surfaces of the actuator base 10 in the second direction and is thermally compressed by a heated roller at around 50° C.
Subsequently, as ACT 3, an exposure treatment is performed. Specifically, first, for example, a photomask having a negative pattern shape is disposed on the end surface of the actuator base 10 in an overlapped manner, and a prebaking treatment is performed at around 90° C. using the photomask. Thus, a predetermined portion not covered by the photomask of the dry film resist 30A is temporarily cured. Further, by immersing the dry film resist 30A in a special developer, the predetermined portion corresponding to the pattern shape of the photomask is dissolved to form openings which become the cutout sections 31. Further, by performing a post baking treatment at around 120° C., the dry film resist 30A is fully cured. By the above exposure and development, the dry film resist 30A is formed into a predetermined shape in which the plurality of cutout sections 31 and the convex cover pieces 32 are alternately arranged. For example, in the present embodiment, the cutout sections 31 are disposed at positions facing the first grooves 14a and the second grooves 14b are covered by the cover pieces 32.
Further, as ACT 4, the frame section 40a is disposed on the outer side of the cover plate 30 and the lid section 40b is disposed so as to cover the common chamber C3. The frame section 40a and the lid section 40b are assembled and joined by fixing to form a case member 40.
Next, as ACT 5, in a state in which the cover plate 30 and the case member 40 are joined to the actuator base 10, the nozzle facing surfaces 10c, 30c, and 40c of the actuator base 10, the cover plate 30, and the frame section 40a are polished to form flush polished surfaces 50c. At this time, since the frame section 40a has working properties close to those of the actuator base 10 in terms of workability, polishing can be performed at the same time and the nozzle facing surfaces 10c, 30c, and 40c of the actuator base 10, the cover plate 30, and the frame section 40a can be polished with high accuracy.
The nozzle plate 20 is attached by bonding so as to cover the grooves 14a and 14b. At this time, the nozzle plate 20 is attached so nozzles 21 are disposed so as to face the first grooves 14a and the second grooves 14b. Further, as shown in
The inkjet printer 100 is an example of a liquid discharge apparatus that discharges liquid, in this case ink, while conveying paper P, which is an example of a recording medium and a discharge target object, along a predetermined conveyance path A1 leading from the medium supplying section 112 to the medium discharging section 114 through the image forming section 113 to perform image formation processing on the paper P.
The medium supplying section 112 includes a plurality of paper feeding cassettes 112a. The medium discharging section 114 includes a paper discharge tray 114a. The image forming section 113 includes a supporting section 117 that supports paper and a plurality of head units 130 disposed above the supporting section 117 so as to face the supporting section 117.
The supporting section 117 includes a conveyance belt 118 provided in a loop shape in a predetermined region where image formation can be performed, a support plate 119 that supports the conveyance belt 118 from the rear side, and a plurality of belt rollers 120 provided on the rear side of the conveyance belt 118.
The head units 130 include a plurality of inkjet heads 1, a plurality of ink tanks 132 mounted on the inkjet heads 1, connection channels 133 that connect the inkjet heads 1 to the ink tanks 132, and circulation pumps 134, which are circulating sections. The head units 130 are circulation-type head units that circulate liquid.
In the present embodiment, the inkjet printer 100 includes the inkjet heads 1C, 1M, 1Y, and 1B of four colors of cyan, magenta, yellow, and black and includes ink tanks 132C, 132M, 132Y, and 132B as that respectively contain inks of these colors. The ink tanks 132 are connected to the inkjet heads 1 by the connection channels 133 (see
Negative-pressure control devices, such as pumps, are coupled to the ink tanks 132. Negative pressure control is performed in the ink tanks 132 by the negative-pressure control devices according to hydrostatic head values in the inkjet heads 1 and the ink tanks 132 to form ink (liquid) meniscuses having a predetermined shape at the nozzles of the inkjet heads 1.
The circulation pumps 134 are, for example, liquid feeding pumps such as piezoelectric pumps. The circulation pumps 134 are provided in the supply channels 133a. The circulation pumps 134 are connected to a driving circuit of the control section 116 by wires. A central processing unit (CPU) 116a is configured to control the circulation pumps 134. The circulation pumps 134 circulate liquid in the circulation channels including the inkjet heads 1 and the ink tanks 132.
The conveying device 115 conveys the paper P along the conveyance path A1 leading from the paper feeding cassettes 112a of the medium supplying section 112 to the paper discharge tray 114a of the medium discharging section 114 through the image forming section 113. The conveying device 115 includes a plurality of guide plate pairs 121a to 121h and a plurality of conveyance rollers 122a to 122h arranged along the conveyance path A1.
The control section 116 includes the CPU 116a, which is a controller, a read only memory (ROM) that stores various programs and the like, a random access memory (RAM) that temporarily stores various variable data, image data, and the like, and an interface section for inputting data from the outside and outputting data to the outside.
In the inkjet head 1 and the inkjet printer 100, the control section 116 applies, with the driving circuit, a driving voltage via the wiring patterns 17 when liquid is discharged from the nozzles 21. When a potential difference is applied to an electrode in the pressure chamber C1 to be driven by the application of the voltage and electrodes in the air chambers C2 on both sides of the pressure chamber C1, the first piezoelectric elements 15a and the second piezoelectric elements 15b are deformed in directions opposite to each other. Driving elements are bent and deformed by the deformation of both the piezoelectric elements. For example, as shown in
In the inkjet head 1 and the inkjet printer 100 according to the present embodiment, since the frame section 40a is formed of a material including aluminum titanate, the frame section can be polished together with the actuator base 10, and the inkjet head 1 can be more easily and inexpensively manufactured. A free-cutting ceramic is generally an expensive material and cannot be used f injection molding or the like, and the shape thereof is required to be formed by a cutting process, the inkjet head 1 is thus very expensive. Furthermore, since a moldable ceramic such as alumina has a hardness that is substantially different from that of PZT, the processing conditions are inherently and greatly different from each other. Thus when used as a frame, there may be a step height difference in the nozzle facing surface facing the nozzle plate 20, or a large amount of chippings can be generated in the PZT. Thus, when the nozzle plate 20 is bonded, gaps may be left, which causes ink leakage. In contrast, in the present embodiment, since the piezoelectric ceramic constituting the actuator base 10 and the aluminum titanate constituting the frame section 40a can be processed under the same processing conditions, the flush polished surfaces 50c can be formed by simultaneous polishing, and a gap can be prevented from being left when the nozzle plate 20 is bonded. In addition, since the cover plate 30 is very thin, there is little influence on the bonded surface. In addition, since the frame section is formed of aluminum titanate that can be injection-molded, processing can be performed at a low cost. Accordingly, the inkjet head 1 can be manufactured at a low cost by molding methods and then simultaneous polishing. Furthermore, since the processing accuracy of the nozzle facing surface can be improved, the sealability between the pressure chamber C1 and the common chamber C3 can be improved, and the liquid discharge performance can be improved for the inkjet head 1 according to the embodiment(s).
The possible embodiments are not limited to the above example embodiment details, and can be embodied by modifying the various components and/or elements without departing from the spirit of the present disclosure.
In the present embodiment, the inkjet head 1 of the so-called end shooter type was explained, but the present disclosure is not limited thereto. For example, the present disclosure may be applied to an inkjet head of a side shooter type. For example, a predetermined direction different from a surface facing a nozzle plate in a comb teeth-like actuator base with grooves open in two different directions may be closed by a plate-like member as a first member. In this case, the plate-like member is formed by molding ceramic material having aluminum titanate as a main component. Even in the present embodiment, by polishing the actuator base and the plate-like member at the same time to form flush polished surfaces, and joining the nozzle plate to the polished surfaces, the pressure chamber can be more easily formed at a low cost with high accuracy.
In the above embodiment, an example in which the actuator base 10 has the grooves 14a and 14b reaching to both ends in the second direction and the cover plate 30 is provided on both sides is shown, but the embodiments are not limited thereto. For example, the actuator base may have a configuration in which the first grooves 14a and the second grooves 14b are open on one side of the actuator base 10 and the cover plate 30 is disposed only on one side of the actuator base 10. Also in this case, the same effect as that of the above example embodiment can be obtained. A shape in which the frame section 40a surrounds the periphery of the end portion in which the grooves 14 are formed in the actuator base 10 is exemplified, but the present disclosure is not limited thereto.
An example in which the cover plate 30 was formed of a dry film resist and formed in a predetermined shape by exposure was explained, but the present disclosure is not limited thereto. For example, using the cover plate formed in a plate-like shape, the nozzle facing surface of the cover plate facing the nozzles may be polished together with the actuator base 10 and the frame section 40a.
In the example embodiment, the actuator base 10 including the laminated piezoelectric body 13 formed of a piezoelectric member on the substrate 12 was exemplified, but the present disclosure is not limited thereto. For example, the actuator base 10 may be formed using only a piezoelectric member without using the substrate 12. In addition, instead of using two piezoelectric members, one piezoelectric member may be used.
According to at least one embodiment described above, it is possible to provide an inkjet head and an inkjet device that are easily manufactured.
The liquid to be discharged is not limited to printing ink, but may be, for example, a liquid containing conductive particles for forming a wiring pattern of a printed wiring board.
In the example embodiment, the inkjet head is used for a liquid discharge apparatus such as an inkjet recording apparatus (printer) was explained, but the present disclosure is not limited thereto. For example, the inkjet head can be applied to a 3D printer, an industrial manufacturing machine, or a medical device, and miniaturization, light weight, and cost reduction can be achieved in such devices as well.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2019-045818 | Mar 2019 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20070216734 | Kitamura | Sep 2007 | A1 |
| 20100141711 | Koseki | Jun 2010 | A1 |
| 20180072058 | Miyazawa | Mar 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 1834782 | Sep 2007 | EP |
| 2000-168094 | Jun 2000 | JP |
| Entry |
|---|
| Extended European Search Report dated Jul. 13, 2020 mailed in corresponding European Patent Application No. 20157859.8, 8 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20200290354 A1 | Sep 2020 | US |
