LIQUID DISCHARGE HEAD AND LIQUID DISCHARGE DEVICE

Abstract

 According to one embodiment, a liquid discharge head includes a base, a piezoelectric body, a top plate, and an orifice plate. The base is composed of engineering ceramics. The piezoelectric body is disposed on one side of the base in a first direction, is composed of piezoelectric ceramics, and has a plurality of grooves forming a pressure chamber. The top plate is disposed on one side of the piezoelectric body in the first direction and is composed of machinable ceramics. The orifice plate is disposed to face the end surface on one side of the piezoelectric body and the top plate in a second direction different from the first direction. The orifice plate has a nozzle communicating with the pressure chamber. The end of the base on the orifice plate side is disposed at a position retracted from the orifice plate with respect to the end surface of the top plate and the piezoelectric body.

Description

FIELD

[0001] Embodiments described herein relate generally to a liquid discharge head and a liquid discharge device.

BACKGROUND

[0002] In a liquid discharge head such as a shared mode shared wall type inkjet head, a configuration in which a bottom plate, and a top plate that closes one of a plurality of grooves forming a pressure chamber are stacked on and joined to a piezoelectric member having the grooves which compose a pressure chamber is known. For example, in an inkjet head, an orifice plate is joined to the end surface of a stacked body in which a piezoelectric member composed of piezoelectric ceramics, a bottom plate, and a top plate are overlapped and joined. Since the bottom plate and the top plate configure a joint surface to be joined to the orifice plate, the bottom plate and the top plate need to form a same surface together with the piezoelectric member that also configures the joint surface. Therefore, it is desirable that the bottom plate, the top plate and the piezoelectric member have similar processing characteristics. On the other hand, if the bottom plate is formed of piezoelectric ceramics, it is not easy to ensure the required strength.

DESCRIPTION OF THE DRAWINGS

[0003] 

FIG. 1 is a perspective view illustrating a part of an inkjet head according to a first embodiment cut off;

FIG. 2 is a cross-sectional view of the inkjet head;

FIG. 3 is an explanatory diagram of the shape and operation of the inkjet head;

FIG. 4 is an explanatory diagram illustrating a method of manufacturing the inkjet head;

FIG. 5 is a table illustrating an example of machinable ceramics and a coefficient of thermal expansion;

FIG. 6 is an explanatory diagram illustrating an example of a material for machinable ceramics and the amount of warpage;

FIG. 7 is an explanatory diagram illustrating a configuration of an inkjet printer using the inkjet head, according to a second embodiment; and

FIG. 8 is an explanatory diagram illustrating a method of manufacturing an inkjet head according to another embodiment.

DETAILED DESCRIPTION

[0004] The problem to be solved by exemplary embodiments is to provide a liquid discharge head and a liquid discharge device having good workability.

[0005] In general, according to one embodiment, a liquid discharge head includes a base, a piezoelectric body, a top plate, and an orifice plate. The base is composed of engineering ceramics. The piezoelectric body is disposed on one side of the base in a first direction, is composed of piezoelectric ceramics, and has a groove forming a pressure chamber. The top plate is disposed on one side of the piezoelectric body in the first direction and is composed of machinable ceramics. The orifice plate is disposed to face the end surface on one side of the piezoelectric body and the top plate in a second direction different from the first direction. The orifice plate has a nozzle that communicates with the pressure chamber. The end of the base on the orifice plate side is disposed at a position retracted from the orifice plate with respect to the end surface of the top plate and the piezoelectric body.

[0006] Preferably, a coefficient of thermal expansion of the machinable ceramics may be a value between a coefficient of thermal expansion of the engineering ceramics and a coefficient of thermal expansion of the piezoelectric ceramics.

[0007] The coefficient of thermal expansion may be obtained according to JISR1618 ("Measuring method of thermal expansion of fine ceramics by thermomechanical analysis").

[0008] Preferably, the piezoelectric body may include at least one of PZT and KNN, and the engineering ceramics may include at least one of alumina, zirconia, mullite, cordierite, forsterite, and steatite.

[0009] Preferably, the top plate may be composed of a material having a coefficient of thermal expansion of 4 x 10^-6/K to 10 x 10^-6/K.

[0010] There is also provided a liquid discharge device comprising the liquid discharge head as described above, and a support unit that supports a print medium at a position facing the liquid discharge head.

[0011] Hereinafter, the configuration of the inkjet head 10 as the liquid discharge head according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view illustrating a part of the inkjet head according to the first embodiment cut off, and FIG. 2 is a cross-sectional view of the inkjet head. FIG. 3 is an explanatory diagram of the shape and operation of the inkjet head. For the sake of explanation in each figure, the configuration is enlarged, reduced or omitted as appropriate. In the figure, X, Y, and Z indicate three directions orthogonal to each other. For example, the Z axis is along the first direction, the Y axis is along the second direction, and the X axis is along the third direction.

[0012] An inkjet head 10 of the present embodiment is, for example, a so-called shear mode and shear wall type inkjet head.

[0013] As illustrated in FIGS. 1 to 3, the inkjet head 10 includes a base 20, a piezoelectric body 30, a top plate 40, a cover 50, and an orifice plate 60.

[0014] The base 20 is formed, for example, in the shape of a rectangular plate. The piezoelectric body 30 is disposed on one main surface of the base 20 in the first direction that is the stacking direction. Further, a wiring pattern is formed in a predetermined region on one main surface of the base 20. As an example, the piezoelectric body 30 is disposed in a region 21 on one side on one main surface, and the wiring pattern is formed in a region 22 on the other side. On the upper surface of the base 20, a drive circuit is connected to the wiring pattern by an FPC or the like. An ink port 23 through which ink can flow is formed at a predetermined location on the base 20. The ink port 23 is a through hole that penetrates the base 20 in the thickness direction along the first direction, and serves as an inlet for ink to flow into the common chamber 39 or an outlet for ink to be discharged from the common chamber 39.

[0015] As an example, the base 20 is configured to be larger than the size of the piezoelectric body 30, in the longitudinal direction along the arrangement direction of the nozzles 61. The piezoelectric body 30 is disposed and joined, in a region on one side of the second direction that is orthogonal to the arrangement direction of the nozzles 61 and the stacking direction, on the main surface of the base 20 on one side of the stacking direction. In the end surface 24 of the base 20 on one side in the second direction, the portion where the piezoelectric body 30 is not disposed at both ends in the third direction, which is the arrangement direction of the nozzles, protrudes to one side in the second direction from the central portion in the third direction in which the piezoelectric body 30 is disposed. That is, in the end surface 24 of the base 20 on one side in the second direction, a predetermined central region including at least a portion where the piezoelectric body 30 is disposed is retracted to the other side in the second direction from both ends. Further, the end surface 24 on one side in the second direction is retracted to the other side in the second direction, from the end surface of the piezoelectric body 30 and the top plate 40 on one side in the second direction, in a predetermined central region including at least a portion where the piezoelectric bodies 30 are stacked and disposed. The end surfaces of both ends of the base 20 may be disposed on the same surface as the piezoelectric body 30 and the top plate 40.

[0016] The base 20 is composed of engineering ceramics. The base 20 is made of a material that is harder and more rigid than the piezoelectric member forming the piezoelectric body 30. For example, the coefficient of thermal expansion of the engineering ceramics forming the base 20 is larger than that of the piezoelectric material forming the piezoelectric body 30. As the engineering ceramics forming the base 20, for example, alumina, zirconia, mullite, cordierite, forsterite, steatite, or the like is used. The coefficient of thermal expansion may be obtained according to JISR1618 ("Measuring method of thermal expansion of fine ceramics by thermomechanical analysis").

[0017] The piezoelectric body 30 is disposed on one side of the base 20 and is adhesively bonded to the base 20 by an adhesive layer. In the piezoelectric body 30, two piezoelectric members 31 and 32 having opposite polarization directions in the stacking direction are stacked and adhesively bonded by an adhesive layer. For example, as the adhesive, a heat adhesive that is cured by heat adhesion is used. The piezoelectric body 30 is formed into a predetermined shape and size by, for example, cutting, and is formed into the shape of a rectangular plate long in the third direction, which is the arrangement direction of the nozzles 61. The piezoelectric body 30 has a trapezoidal cross-sectional shape orthogonal to the third direction. In the piezoelectric body 30, the end surface on one side in the second direction forms a joint surface facing the orifice plate 60, and the side surface opposite to the joint surface, that is, the end surface on the other side in the second direction forms a tapered surface that is inclined with respect to the second direction, which is the extension direction of the groove 33. That is, one side surface of the piezoelectric body 30 has a tapered surface extending from the bottom surface of the groove 33 to the main surface of the base 20. As the piezoelectric material configuring the piezoelectric body 30, for example, a PZT (lead zirconate titanate)-based or lead-free KNN (potassium niobate)-based piezoelectric ceramic material is used.

[0018] The piezoelectric body 30 has a plurality of grooves 33. The plurality of grooves 33 extend along the second direction of the piezoelectric body 30 and are arranged side by side in the third direction. Each groove 33 has an elongated shape whose longitudinal direction is along the second direction. The groove 33 is a bottomed slit that opens on one end side in the second direction in which the orifice plate 60 is disposed and on one side in the first direction in which the top plate 40 is disposed. The plurality of grooves 33 arranged in the third direction are formed parallel to each other.

[0019] The plurality of grooves 33 are composed of a first groove 331 and a second groove 332 that are disposed alternately. The first groove 331 forms a pressure chamber 37 communicating with the nozzle 61 and the common chamber 39. The second groove 332 forms a closed dummy chamber 38.

[0020] The wall-shaped portion of the piezoelectric body 30 formed between the adjacent grooves 33 forms the stacked piezoelectric element 34 that is a driving portion of the pressure generating unit. In the piezoelectric body 30, a plurality of stacked piezoelectric elements 34 and grooves 33 are alternately arranged side by side in the first direction. The plurality of stacked piezoelectric elements 34 are continuous with each other by the piezoelectric members 32 forming the bottom of the groove 33. Each stacked piezoelectric element 34 is configured by stacking a pair of piezoelectric element portions 341 and 342 whose polarization directions in the stacking direction are opposite to each other.

[0021] Electrodes 36 are formed on the inner surface of the pressure chamber 37 formed of each groove 33 and the inclined surface portion of the piezoelectric body 30. The electrode 36 is led out from the inner surface of the groove 33 through the inclined surface portion, and is connected to the wiring pattern on the upper surface of the base 20.

[0022] The electrode 36 is formed by, for example, a vacuum vapor deposition method, an electroless nickel plating method, or the like. The electrode 36 may be formed together with the wiring pattern by a method such as a vacuum vapor deposition method or an electroless plating method at the same time, for example. The material of the electrode 36 is composed of a conductive material such as nickel, gold, and copper. The electrode 36 may be formed by stacking two or more types of conductive films.

[0023] The top plate 40 is composed of, for example, a square plate-shaped member. The top plate 40 is disposed to face the surface of the piezoelectric body 30 on one side in the stacking direction, and closes the opening on one side of the groove 33. The top plate 40 is composed of machinable ceramics.

[0024] As will be described later, the end surface of the top plate 40 on the orifice plate 60 side and the end surface of the piezoelectric body 30 on the orifice plate 60 side are cut and polished simultaneously to form a flush surface. The top plate 40 and the piezoelectric body 30 protrude from the base 20 toward the orifice plate 60, that is, on one side in the second direction. In other words, the base 20 is retracted to the other side in the second direction so as to be separated from the orifice plate 60 with respect to the piezoelectric structure 80 formed by stacking the top plate 40 and the piezoelectric body 30. That is, in the inkjet head 10, the end surface of the base 20 is disposed on the other side in the second direction from the end surfaces of the piezoelectric body 30 and the top plate 40. The end surface of the base 20 may or may not be orthogonal to the bottom surface of the base 20, and may or may not be parallel to the joint surface 81 formed of the piezoelectric body 30 and the top plate 40. For example, the end surface of the base 20 may be inclined or curved.

[0025] FIG. 5 is a table showing the coefficient of thermal expansion of major machinable ceramics. The coefficient of thermal expansion may be obtained according to JISR1618 ("Measuring method of thermal expansion of fine ceramics by thermomechanical analysis"). As illustrated in FIG. 5, Macerite HSP is 9.8 x 10^-6/K, Macor is 9.3 x 10^-6/K, Macerite SP is 9.2 x 10^-6/K, Photoveel is 7.8 x 10^-6/K, Photoveel L is 6.1 x 10^-6/K, Macerite ET is 5.8 x 10^-6/K, Macerite BT is 4.5 x 10^-6/K, and Macerite PN is 4.2 x 10^-6/K. For example, in the present embodiment, the top plate 40 is made of a material having a coefficient of thermal expansion of 4 to 10 x 10^-6/K. Specifically, Macerite, Macor, or Photoveel is used as the machinable ceramics forming the top plate 40. "Macerite" is a registered trademark for a machinable ceramics product by Krosaki Harima Corporation, Fukuoka, Japan. Macerite is comprised of a fluoro-phlogopite. "Macor" is a registered trademark for a machinable ceramics product by Corning Incorporated, Corning, NY, USA. Macor is a glass-ceramic. "Photoveel" is a registered trademark for a machinable ceramics product by Ferrotec Holdings Corporation, Tokyo, Japan. Photoveel is a glass matrix composite in which fluoro-phlogopites and zirconia microcrystals are uniformly precipitated.

[0026] The top plate 40 is overlapped and joined on the piezoelectric body 30 joined on the base 20. More preferably, as the material forming the top plate 40, machinable ceramics are used in which the coefficient of thermal expansion is a value between the coefficient of thermal expansion of the engineering ceramics forming the base 20 and the coefficient of thermal expansion of the piezoelectric ceramics. For example, if the piezoelectric body 30 is PZT and the base 20 is alumina, a coefficient of thermal expansion of 2 x 10^-6/K or more and 7.2 x 10^-6/K or less is selected.

[0027] FIG. 6 is a table which illustrates the amount of warpage of an assembly in which the piezoelectric body 30 is made of PZT, the base 20 is made of alumina, and three types of material including PZT and two types of Macerite (ET and SP) having different coefficients of thermal expansion are used for the top plate 40, and the top plate 40 is heat-bonded to the piezoelectric body 30 at the temperature of about 120°C. As illustrated in FIG. 6, the coefficient of thermal expansion of alumina is 7.2 x 10^-6/K, the coefficient of thermal expansion of PZT is 2 x 10^-6/K, the coefficient of thermal expansion of Macerite SP is 9.2 x 10^-6/K, the coefficient of thermal expansion of Macerite ET is 5.8 x 10^-6/K. If the top plate 40 is composed of Macerite ET, the amount of warpage is smaller than that of PZT and Macerite SP. Since the amount of warpage differs depending on the materials of the piezoelectric body 30 and the base 20, the material of the top plate 40 may be appropriately selected, and for example, a material that reduces warpage of the assembly may be selected.

[0028] The cover 50 integrally includes a rectangular cover plate 51 that is disposed to face one side of the top plate 40 in the stacking direction, and a cover frame 52 that extends from the side edge of the cover plate 51 toward the base 20. In the cover 50, the cover plate 51 is disposed on the top plate 40, and the end of the cover frame 52 is joined to one side of the base 20. The cover 50 covers a predetermined region of the base 20 on which the piezoelectric body 30 is disposed, and forms a common chamber 39 on the side of the piezoelectric body 30. The common chamber 39 communicates with the ink port 23 formed in the base 20 and the plurality of pressure chambers 37 of the piezoelectric body 30.

[0029] The orifice plate 60 is formed in the shape of a square plate having a thickness of about 10 to 100 µm. The orifice plate 60 is joined to a joint surface which is the side surface on one side of a stacked structure formed of the piezoelectric body 30 and the top plate 40. The orifice plate 60 is formed with a plurality of nozzles 61 penetrating in the thickness direction. The nozzles 61 are provided at positions corresponding to a plurality of pressure chambers 37 arranged every other nozzle. That is, the orifice plate 60 has a nozzle 61 communicating with the pressure chamber 37 and closes the side opening of the dummy chamber 38.

[0030] A predetermined gap is formed between the orifice plate 60 and the end surface of the base 20.

[0031] FIG. 4 is an explanatory diagram illustrating a method of manufacturing the inkjet head 10. Here, as an example, an example will be illustrated in which the two piezoelectric structures 80 configuring two inkjet heads 10 are integrally formed and then divided into two. The method of manufacturing the inkjet head 10 according to the present embodiment includes piezoelectric body forming process, bonding process, trapezoidal processing, groove processing, electrode processing, and top plate bonding process.

[0032] First, two plate-shaped piezoelectric members polarized in the plate thickness direction in advance are stacked such that the polarization directions are staggered, and the stacked body is cut to a desired width and length to form a piezoelectric part 300 in which two piezoelectric bodies 30 are integrally continuous (piezoelectric body forming process).

[0033] As the piezoelectric body bonding process, the piezoelectric part 300 is attached to the base part 200, that is a plate-shaped member in which the two bases 20 are continuous, with an adhesive or the like without any gap (Act 11). In the base part 200, two plate-shaped bases 20 are connected at both ends in the third direction, and a slit 201 in which the longitudinal direction is along the third direction and which penetrates in the thickness direction is formed in the central portion in the third direction. The slit 201 has a width twice the width of the step in the width direction that is the second direction, and forms a step with the piezoelectric body 30 if the base part 200 is divided into two bases 20 by a later division process.

[0034] Subsequently, as the trapezoidal processing, the base part 200 is processed into a trapezoidal shape such that the electrode 36 can be drawn out (Act 12). Further, as the groove processing, a plurality of grooves 33 are formed on the surface of the base part 200 provided with the piezoelectric part 300, by machining using a dicing saw, a slicer, or the like (Act 13).

[0035] Further, as the electrode processing, a conductive film such as an electrode 36 and a wiring pattern is formed by a vacuum vapor deposition method or the like (Act 13). After forming the electrodes by plating, unnecessary electrodes are removed by etching or laser patterning to form a desired electrode wiring connecting the pressure chamber and the end of the base.

[0036] Subsequently, as the top plate bonding process, the upper surface of the piezoelectric part 300 is covered with the top plate part 400, in which the two top plates 40 are integrally continuous, and heat-bonded via the adhesive layer (Act 14).

[0037] After that, as the division process, the piezoelectric structure part 800 in which the base part 200, the piezoelectric part 300, and the top plate part 400 are stacked and joined is divided into two by dicing, so that two piezoelectric structures 80 are completed (Act 15). The cut surface at the division is the nozzle joint surface 81. The nozzle joint surface 81 is at right angles or substantially at right angles to the bottom surface of the base 20 as the reference. If the squareness is insufficient by the cutting alone, or if the surface is rough, the cut surface may be further polished (Act 16).

[0038] The individual piezoelectric structure 80 configured as described above has a joint surface 81 formed by the end surfaces of the top plate 40 and the piezoelectric body 30. In the piezoelectric structure 80, the end surface 24 of the base 20 is disposed at a position separated from the position where the orifice plate 60 is disposed in the second direction with respect to the joint surface 81 composed of the side surfaces of the top plate 40 and the piezoelectric body 30. In other words, the joint surface 81 to be joined to the orifice plate 60 is formed by the side surfaces of the top plate 40 and the piezoelectric body 30, and does not include the surface of the base 20.

[0039] Then, the orifice plate 60 is adhered and attached to the side surfaces of the top plate 40 and the piezoelectric body 30. At this time, the nozzle 61 is disposed to face the first groove 331 forming the pressure chamber 37, and the second groove 332 forming the dummy chamber 38 is closed.

[0040] Further, the cover 50 is covered from one side of the piezoelectric structure 80, and the end surface of the cover frame 52 of the cover 50 is adhered and attached to the surface of the base 20. Thus, the inkjet head 10 illustrated in FIG. 1 is completed.

[0041] In the inkjet head 10 configured as described above, the pressure chamber is once opened from a stationary state to allow ink to flow in, and then the pressure chamber is reduced to pressurize and discharge the ink. Specifically, as illustrated in FIG. 3, when driving the material to be discharged from the nozzle 61, by the drive circuit applying a drive voltage to the drive element via the wiring pattern formed on the base 20, a potential difference is given to the electrodes 36 in the driving pressure chamber 37 and the electrodes 36 of both adjacent dummy chambers 38. Then, the pair of piezoelectric element portions 341 and 342 of the stacked piezoelectric element 34 are deformed in opposite directions to each other, and the driving element is bent and deformed due to the deformation of both piezoelectric elements. As an example, ink is guided into the pressure chamber 37 by first deforming the driving pressure chamber 37 in the opening direction to create a negative pressure in the pressure chamber 37 (ink inflow). Subsequently, the pressure chamber 37 is deformed in the closing direction and the inside of the pressure chamber 37 is pressurized (ink pressurization) to discharge ink droplets from the nozzle 61, and return the electrodes in the pressure chamber to the reference potential (ink column cutting).

[0042] According to the present embodiment, it is possible to provide an inkjet head 10 having good workability. Since the wall of the pressure chamber, which is the joint surface of the orifice plate 60 having the nozzles 61 is configured with machinable ceramics and the piezoelectric body, the wall can be easily processed, and the joint surface to be joined to the orifice plate 60 can be made on the same surface by machining. That is, since the joint surface is formed by the piezoelectric body 30 and the top plate 40 having the same processing characteristics, the processing conditions are facilitated, and the orifice plate 60 can be joined accurately and evenly. Further, by using a lead-free material for the base 20, it is possible to provide an inkjet head 10 suitable for the environment.

[0043] For example, among the three types of materials used in the present embodiment, alumina is very hard and the processing conditions are different. Therefore, if simultaneous processing is performed, the processed surface becomes rough, or there are many chippings and burrs, which makes processing difficult. For example, materials with different workability tend to have a step during processing. That is, the soft material may escape from the blade through the adhesive layer and return to its original state after processing, and the layer of the soft material protrude, or the layer of the soft material may be processed in large quantities and the layer of the hard material protrude. For example, even if polishing is performed, a step is generated due to a difference in the amount of polishing in the polishing, and it is not easy to eliminate the step. If a step is formed on the joint surface to be joined to the orifice plate 60 as described above, a gap is likely to occur if the orifice plate 60 is joined. On the other hand, in the present embodiment, the top plate 40 and the piezoelectric body 30 are made of materials having similar processing characteristics, and the joint surface is formed with these parts, so that a large step is unlikely to occur on the joint surface, and the orifice plate 60 can be joined without gap. Further, by retracting the end surface 24 of the base 20 from the joint surface 81, the restriction on material selection regarding the workability of the base 20 can be removed, and it becomes easy to ensure the strength in the material selection of the base 20, so that the inkjet head 10 can be made thinner and smaller.

[0044] Further, in the above embodiment, for example, by selecting machinable ceramics, a material with the coefficient of thermal expansion in the range of 4 to 10 x 10^-6/K, warpage and deformation after joining can be prevented. Therefore, even if a thermosetting adhesive is used, it is possible to prevent warpage and deformation after joining, and since it is easy to fix the material, it is easy to process during the dividing.

[0045] Further, in the above embodiment, by appropriately selecting the coefficient of thermal expansion of the machinable ceramics so as to minimize the warpage of the assembly, the adsorption to the device is possible during machining, and the configuration having higher workability can be achieved. For example, by selecting the material of the top plate 40 as the material having a coefficient of thermal expansion between the coefficient of thermal expansion of the piezoelectric body 30 and the coefficient of thermal expansion of the base 20, the warpage of the assembly can be reduced.

[0046] Further, for example, in the manufacturing process, in the case of a method of forming a step on the base after joining, if there is a large amount of warpage, in order to remove alumina, many PZTs are scraped due to warpage, resulting in a smaller joint surface of the orifice plate, but in the above embodiment, by adopting a configuration in which the warpage is small, it is easy to reduce the amount of PZT scraped and to ensure the joint surface of the orifice plate.

[Second Embodiment]

[0047] Hereinafter, an inkjet printer 100 as a liquid discharge device will be described with reference to FIG. 7. The inkjet printer 100 is a printer using the inkjet head 10 according to the first embodiment.

[0048] The inkjet printer 100 is a device that performs various processes such as image formation while conveying, for example, paper P, which is a print medium, along a predetermined conveyance path. The inkjet recording device 1 includes a housing 110, a paper feed cassette 111 as a paper supply unit, a paper discharge tray 112 as a discharge unit, a holding roller (drum) 113 as a support unit, a conveying device 114, and a reversing device 118.

[0049] The housing 110 forms the outer shell of the inkjet printer 100. The paper feed cassette 111 is provided inside the housing 110. The paper discharge tray 112 is provided on the upper part of the housing 110. The holding roller (drum) 113 holds the paper P on the outer surface and rotates. The conveying device 114 conveys the paper P along a predetermined conveyance path A formed from the paper feed cassette 111 through the outer circumference of the holding roller 113 to the paper discharge tray 112. The reversing device 118 reverses the front and back surfaces of the paper P peeled from the holding roller 113 and supplies the paper P onto the surface of the holding roller 113 again.

[0050] The conveying device 114 includes a plurality of guide members 121 to 125 and a plurality of conveying rollers 126 to 131 provided along the conveyance path A. As the conveying rollers, a pickup roller, a paper feed roller pair, a resist roller pair, a separation roller pair, a conveying roller pair, and a discharge roller pair are provided. These conveying rollers 126 to 131 are driven by a convey motor and rotate to feed the paper P to the downstream side along the conveyance path A.

[0051] Sensors S and the like for monitoring the paper convey status are disposed in various locations on the conveyance path A.

[0052] The holding roller 113 conveys the paper P by rotating while holding the paper P on its surface. The holding roller 113 supports the paper P, which is a print medium, at a position facing the inkjet head 10. Here, the holding roller 113 rotates clockwise in FIG. 12 to convey the paper P clockwise along the outer circumference.

[0053] A holding device 115, an image forming device 116, a static elimination peeling device 117, and a cleaning device 119 are provided in order from the upstream side to the downstream side in the outer circumference portion of the holding roller 113.

[0054] The holding device 115 includes a pressing roller 115a and a charging roller 115b. The pressing roller 115a presses against the outer surface of the holding roller 113. If electric power is supplied, the charging roller 115b generates (charges) an electrostatic force in the direction of adsorbing the paper P to the outer surface of the holding roller 113. The paper P is adsorbed to the holding roller 113 by the electrostatic force.

[0055] The image forming device 116 includes four inkjet heads 10 corresponding to four colors of cyan, magenta, yellow, and black, as a plurality of (four colors) inkjet heads 10 disposed to face the outer surface of the holding roller 113. The four inkjet heads 10 discharge ink onto the paper P from the nozzles 61 provided at a predetermined pitch to form an image on the paper P held on the outer surface of the holding roller 113. As each inkjet head 10, the inkjet head 10 described in the first embodiment is used.

[0056] The static elimination peeling device 117 includes a static elimination roller that removes static electricity from the paper P, and a peeling claw that peels the paper P from the holding roller 113.

[0057] The cleaning device 119 includes a cleaning member that cleans the holding roller 113 by rotating in contact with the holding roller 113.

[0058] The reversing device 118 reverses the paper P peeled from the holding roller 113 and supplies the paper P onto the surface of the holding roller 113 again. The reversing device 118 reverses the paper P by guiding and conveying the paper P along a predetermined reversing path for switching back the paper P in the reverse direction in the longitudinal direction.

[0059] In addition, the inkjet printer 100 includes a central processing unit (CPU) that is a controller, a ROM that stores various programs, a RAM that temporarily stores various variable data and image data, and an interface (I/F) for inputting data from the outside and outputting data to the outside.

[0060] For example, if the user instructs the printer to perform printing, the CPU of the inkjet printer 100 outputs a print signal to the drive circuit for the inkjet head 10. Thus, the inkjet head 10 is driven and an image is formed on the paper P.

[0061] The same effect as that of the first embodiment can be achieved even in the inkjet printer 100 configured as described above.

[0062] The exemplary embodiment is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof.

[0063] For example, in the above embodiment, as a method of manufacturing the inkjet head 10, an example in which a slit forming a step is formed in advance in the base part 200 is illustrated, but the exemplary embodiment is not limited to this. For example, as illustrated in FIG. 8, the base part 200 may not have a slit in advance and may be formed in a continuous plate shape over the entire length. In this case, after the piezoelectric part 300 is attached to the front side of the base part 200 at the central portion in the second direction, a part of the base part 200 and a part of the piezoelectric part 300 are scraped by being polished to a predetermined depth with a predetermined width from the back side of the base part 200, so that a groove 83 having a depth equal to or larger than the thickness of the base part 200 is formed. After that, two piezoelectric structures 80 having a step in which the end surface 24 of the base 20 retracts from the joint surface 81 are formed by cutting the piezoelectric structure part 800 into two at the line C passing through the center in the width direction of the groove 83.

[0064] For example, the specific configuration of the inkjet head 10, the shape of the flow path, the configuration and positional relationship of various components including the base 20, the piezoelectric body 30, the top plate 40, the cover 50, and the orifice plate 60 are not limited to the above-described examples, and can be changed as appropriate. Further, the arrangement of the nozzle 61 and the pressure chamber 37 is not limited to the above. For example, the nozzles 61 may be arranged in two or more rows. Further, two or more dummy chambers 38 may be arranged between the plurality of pressure chambers 37.

[0065] For example, the liquid to be discharged is not limited to the ink for printing, and for example, a device for discharging a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

[0066] Further, in the above embodiment, an example is shown in which the inkjet head 10 is used in a liquid discharge device such as an inkjet recording device 1, but the exemplary embodiment is not limited to this, for example, the inkjet head 10 can be used in a 3D printer, an industrial manufacturing machine, and a medical application, which can reduce the size, weight and cost.

[0067] According to at least one embodiment described above, it is possible to provide a liquid discharge head and a liquid discharge device having good workability.

[0068] 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 scope of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope of the inventions.

Claims

1. A liquid discharge head comprising:

a base that is composed of engineering ceramics;

a piezoelectric body that is disposed on one side of the base in a first direction, is composed of piezoelectric ceramics, and has a groove forming a pressure chamber;

a top plate that is disposed on one side of the piezoelectric body in the first direction and is composed of machinable ceramics; and

an orifice plate that is disposed to face an end surface on one side of the piezoelectric body and the top plate in a second direction different from the first direction, and has a nozzle communicating with the pressure chamber, wherein

the end of the base on the orifice plate side is disposed at a position retracted from the orifice plate with respect to the end surfaces of the top plate and the piezoelectric body.

2. The liquid discharge head according to claim 1, wherein
a coefficient of thermal expansion of the machinable ceramics is a value between a coefficient of thermal expansion of the engineering ceramics and a coefficient of thermal expansion of the piezoelectric ceramics.

3. The liquid discharge head according to claim 1 or 2, wherein

the piezoelectric body includes at least one of PZT and KNN, and

the engineering ceramics include at least one of alumina, zirconia, mullite, cordierite, forsterite, and steatite.

4. The liquid discharge head according to any one of claims 1 to 3, wherein the top plate is composed of a material having a coefficient of thermal expansion of 4 x 10^-6/K to 10 x 10^-6/K.

5. A liquid discharge device comprising:

the liquid discharge head according to any one of claims 1 to 4; and

a support unit that supports a print medium at a position facing the liquid discharge head.

Drawing