Liquid discharge head and inkjet recording apparatus

Abstract

Provided is a liquid discharge head and an inkjet recording apparatus capable of suppressing a decrease in print quality. A liquid discharge head of an embodiment includes a substrate, an actuator, a manifold, a common electrode, an individual electrode, and a coating layer. The substrate is formed with an opening through which a liquid passes. The actuator is provided on a main surface of one side of the substrate and has a plurality of pressure chambers and a plurality of air chambers formed between the plurality of pressure chambers. The manifold is disposed on the other side of the substrate. The common electrode has an electrode portion formed on a surface of the actuator, a main surface of one side of the substrate, a main surface of the other side of the substrate, an inner surface of the opening, and a side surface of the substrate. The individual electrode has an electrode portion formed on a surface of the actuator and a main surface of one side of the substrate. The coating layer covers at least a portion of the main surface of one side of the substrate.

Description

Technical Field

[0001] Embodiments of the present invention relate to liquid ejection heads. Background Technology

[0002] Among liquid ejection heads, there are known liquid ejection heads that include an actuator that forms a plurality of partition walls at predetermined intervals and a pressure chamber between each partition wall. As a liquid ejection head, there are also known liquid ejection heads that employ an independent drive structure to achieve high-speed liquid ejection, the independent drive structure having a pressure chamber from which liquid is ejected from the nozzle and an air chamber from which no liquid is ejected.

[0003] In liquid ejector heads with independently driven structures, there are examples where the electrodes of the pressure chamber are bundled together on the central side of the substrate for common polarization, while the electrodes of the air chamber are led out to the opposite side as independent electrodes. For example, the common electrodes are formed on the surface of the substrate, the inner surface of the supply hole, and the back side of the substrate, and a coating is formed on the surface of the substrate.

[0004] In such liquid ejector heads, when ink containing components that dissolve electrodes is used, the common electrode on the back side of the substrate sometimes disappears, causing the surface and back electrodes to separate. In this case, the resistance of the common electrode increases, and when the liquid is ejected, a difference in the drive waveform occurs between the ends and the center of the column, resulting in poor printing quality such as dot diameter and straightness. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a liquid ejector head that can ensure high printing quality.

[0006] The liquid ejector head of this embodiment includes a substrate, an actuator, a manifold, a common electrode, individual electrodes, and a coating. The substrate has an opening for liquid to pass through. The actuator is disposed on a main surface of one side of the substrate and has multiple pressure chambers and multiple air chambers formed between the pressure chambers. The manifold is disposed on the other side of the substrate. The common electrode has electrode portions formed on the surface of the actuator, the main surface of one side of the substrate, the main surface of the other side of the substrate, the inner surface of the opening, and the side surface of the substrate. The individual electrodes have electrode portions formed on the surface of the actuator and the main surface of one side of the substrate. The coating covers at least a portion of the main surface of one side of the substrate. Attached Figure Description

[0007] Figure 1 This is a perspective view showing the structure of the liquid ejector head according to the first embodiment.

[0008] Figure 2 This is a bottom view showing the structure of the liquid ejector head according to the first embodiment.

[0009] Figure 3 This is a bottom view showing a portion of the structure of the liquid ejector head according to the first embodiment.

[0010] Figure 4 This is a perspective view showing the structure of the nozzle body of the liquid ejector according to the first embodiment.

[0011] Figure 5 This is a cross-sectional view showing the structure of the nozzle body according to the first embodiment.

[0012] Figure 6 This is a top view showing the structure of the nozzle body according to the first embodiment.

[0013] Figure 7 This is a cross-sectional view showing a portion of the structure of the nozzle body according to the first embodiment, with some parts omitted.

[0014] Figure 8 This is a cross-sectional view showing a portion of the structure of the nozzle body according to the first embodiment, with some parts omitted.

[0015] Figure 9 This is a cross-sectional view showing a portion of the structure of the nozzle body according to the first embodiment, with some parts omitted.

[0016] Figure 10 This is an explanatory diagram showing the structure of the liquid ejection device according to the first embodiment.

[0017] Symbol Explanation

[0018] 1. Liquid ejector head (inkjet head); 2. Liquid ejection device (inkjet recording device); 11. Printhead body; 12. Manifold unit; 13. Cooling flow path unit; 14. Circuit board; 15. Cover; 111. Board; 112. Frame; 113. Actuator; 114. Nozzle plate; 115. Surface; 116. Common liquid chamber; 117. Back side; 118. Individual electrode; 1181. First electrode section; 1182. Second electrode section; 1183. Third electrode section; 119. Common electrode; 1191. First electrode section; 1192. Second electrode section; 1 193. Third electrode section; 1194. Fourth electrode section; 1195. Fifth electrode section; 1196. Sixth electrode section; 1197. Seventh electrode section; 1198. Eighth electrode section; 121. Manifold; 1213. First cooling flow path; 122. Top plate; 123. Ink supply pipe; 124. Ink discharge pipe; 125. Cooling water supply pipe; 126. Cooling water discharge pipe; 142. Driver IC; 143. Printed wiring board; 151. Outer contour; 152. Mask; 1111. Supply port; 1112. Discharge port; 1113. Through hole ; 1114, End face; 1116, Connecting part; 1131, Pressure chamber; 1132, Air chamber; 1133, Piezoelectric element (driving element); 1134, Inclined surface; 1135, Liquid-proof wall; 1141, Nozzle; 1142, Nozzle array; 1161, First common liquid chamber; 1162, Second common liquid chamber; 1211, Supply flow path; 1312, Second cooling flow path; 133, Second cooling water supply pipe; 134, Second cooling water discharge pipe; 2001, Conveying path; 2111, Housing; 2112, Medium supply part; 2113, Image forming 2114. Medium discharge unit; 2115. Conveying device; 2116. Cooling device; 2117. Maintenance device; 2118. Control unit; 2120. Support unit; 2130. Nozzle unit; 2132. Supply tank; 2134. Pump; 2135. Connecting flow path; 21121. Paper feed box; 21141. Paper discharge tray; 21181. CPU; 21201. Conveyor belt; 21202. Support plate; 21203. Belt roller; 21211~21218. Guide plate pair; 21221~21228. Conveying roller; P. Paper. Detailed Implementation

[0019] Below, refer to Figures 1 to 9 The liquid ejector head 1 and the liquid ejection device 2 using the liquid ejector head 1 according to the first embodiment will be described. Figure 1 This is a perspective view showing the structure of the liquid ejector head 1 according to the first embodiment. Figure 2 This is a bottom view showing the structure of the liquid ejector head 1. Figure 3 This is a bottom view showing the structure of the liquid ejector head 1 with the nozzle plate 114 omitted. Figure 4 This is a perspective view showing the structure of the nozzle body 11 of the liquid ejector head 1. Figure 5 This is a cross-sectional view showing the structure of the nozzle body 11. Figure 6 This is a top view showing the structure of the substrate 111, actuator 113, multiple independent electrodes 118, and common electrode 119 of the nozzle body 11. Figure 7 This is a cross-sectional view showing the structure of the substrate 111, actuator 113, multiple independent electrodes 118, and common electrode 119 of the nozzle body 11. Figure 8 This is a cross-sectional view showing the structure of the substrate 111, actuator 113, and common electrode 119 of the nozzle body 11. Figure 9 This is a cross-sectional view showing the structure of the actuator 113, multiple independent electrodes 118, and common electrode 119 of the nozzle body 11. Figure 10 This is an explanatory diagram showing the structure of a liquid ejection device 2 using a liquid ejection head 1. It should be noted that, for illustrative purposes, the structure has been shown enlarged, reduced, or omitted as appropriate. In the diagrams, X, Y, and Z represent a first, second, and third mutually orthogonal directions, respectively. It should be noted that, in this embodiment, the directions are described based on the orientation of the parallel directions of the nozzle 1141 or pressure chamber 1131 of the liquid ejection head 1 along the X-axis, the extending direction of the pressure chamber 1131 along the Y-axis, and the ejection direction of the liquid along the Z-axis, but this is not a limitation.

[0020] Liquid ejector head 1 is, for example, located at Figure 10 The inkjet head shown is a shear-mode inkjet head of a liquid ejection device 2, such as an inkjet recording device. The liquid ejection head 1 has, for example, an independently driven structure that alternately includes a pressure chamber 1131 and an air chamber 1132. The liquid ejection head 1 is provided in a printhead unit 2130, which includes a supply tank 2132, which serves as a liquid receiving section, provided in the liquid ejection device 2.

[0021] The liquid nozzle 1 is supplied with ink, which is stored as liquid in the supply tank 2132. It should be noted that the liquid nozzle 1 can be a non-circulating nozzle that does not circulate the ink, or it can be a circulating nozzle that circulates the ink. In this embodiment, an example using a non-circulating nozzle will be described. Furthermore, the liquid nozzle 1 is connected to a cooling device 2116 provided in the liquid dispensing device 2, and is supplied with a cooling liquid (cooling water) for controlling the temperature of the ink.

[0022] like Figures 1 to 4As shown, the liquid nozzle 1 includes a nozzle body 11, a manifold unit 12, a cooling flow path unit 13, a circuit board 14, and a cover 15. For example, the liquid nozzle 1 is a side-firing, four-row integrated head with two sets of nozzle bodies 11 and each nozzle body 11 having a pair of actuators 113.

[0023] The nozzle body 11 sprays out liquid. For example... Figures 3 to 9 As shown, the nozzle body 11 includes a base plate 111, a frame 112, an actuator 113 having multiple pressure chambers 1131 and multiple air chambers 1132, and a nozzle plate 114.

[0024] The nozzle body 11 has a common liquid chamber 116 that communicates with the plurality of pressure chambers 1131 of the actuator 113. The primary side of the plurality of pressure chambers 1131 refers to the upstream side of the plurality of pressure chambers 1131 in the direction of liquid flow. The secondary side of the plurality of pressure chambers 1131 refers to the downstream side of the plurality of pressure chambers 1131 in the direction of liquid flow.

[0025] In addition, the nozzle body 11 has multiple independent electrodes 118 on the substrate 111 and the actuator 113 respectively driving multiple pressure chambers 1131 of the actuator 113, and a single or multiple common electrodes 119 that simultaneously drive multiple pressure chambers 1131.

[0026] In this embodiment, an example is used where the nozzle body 11 has two actuators 113, and the common liquid chamber 116 has one first common liquid chamber 1161 and two second common liquid chambers 1162. The common liquid chamber 116, for example, has a first common liquid chamber 1161 and a second common liquid chamber 1162. The first common liquid chamber 1161 communicates with the primary side opening (inlet of pressure chamber 1131) of the plurality of pressure chambers 1131 of the actuator 113, and the second common liquid chamber 1162 communicates with the secondary side opening (outlet of pressure chamber 1131) of the plurality of pressure chambers 1131 of the actuator 113.

[0027] The substrate 111 is formed into a rectangular plate shape from a ceramic material such as alumina. The substrate 111 has a surface 115 that forms one main surface of the grinding surface and a back surface 117 that forms another main surface. The substrate 111 is formed into a rectangular shape that is elongated in one direction (X direction). On the surface 115, which forms one side of the main surface of the substrate 111 and constitutes the grinding surface, a third electrode portion 1183 that is part of a plurality of independent electrodes 118 and a third electrode portion 1193 that is part of a single common electrode 119 are formed. A pair of actuators 113 are arranged on the surface 115 of the substrate 111 along the short side direction (Y direction) of the substrate 111. The substrate 111 has a single supply port 1111, a plurality of discharge ports 1112, and a plurality of through holes 1113. The supply port 1111, the discharge ports 1112, and the through holes 1113 are through holes that penetrate between the two main surfaces of the substrate 111. The supply port 1111 is an opening for ink to pass through and is formed on the substrate 111.

[0028] Additionally, a fifth electrode portion 1195 is formed on the end face 1114 along the length direction of the substrate 111, which becomes part of a single common electrode 119. The end face 1114 extends along the thickness direction (Z direction) of the substrate 111 and forms a side face portion that is continuous with the surface 115, which is the main surface of one side of the substrate 111, and the back face 117, which is the main surface of the other side.

[0029] The supply port 1111 is an inlet for supplying ink to the first common liquid chamber 1161. The supply port 1111 is a through-hole formed at the center of the short side of the substrate 111. The supply port 1111 extends along the length of the substrate 111. In other words, the supply port 1111 is, for example, an elongated hole extending in one direction along the length of both the actuator 113 and the first common liquid chamber 1161. The supply port 1111 is disposed between a pair of actuators 113 and opens at a position opposite to the first common liquid chamber 1161.

[0030] A fourth electrode portion 1194, which becomes part of the common electrode 119, is formed on the inner wall surface of the supply port 1111.

[0031] The outlet 1112 is the outlet for discharging ink. Multiple outlets 1112 are provided, for example, four. Each outlet 1112 is located, for example, between the first common liquid chamber 1161 and each second common liquid chamber 1162, and is adjacent to both ends of a pair of actuators 113 in the longitudinal direction. It should be noted that multiple outlets 1112 may also be provided in the second common liquid chamber 1162. An eighth electrode portion 1198, which becomes part of the common electrode 119, is formed on the inner wall surface of the outlet 1112.

[0032] The through-hole 1113 is a through-hole formed at both ends of the substrate 111 along its length and at a position further outward than the outlet 1112. The through-hole 1113 is located on the outer side of the frame 112 and opens at a position that is not opposite to the first common liquid chamber 1161 and the second common liquid chamber 1162 and is not in contact with the ink. A seventh electrode portion 1197, which becomes part of the common electrode 119, is formed on the inner wall surface of the through-hole 1113.

[0033] An actuator 113 and a frame 112 are provided on the substrate 111. The inner side of the frame 112 of the substrate 111 becomes a liquid receiving area for dispensing ink, and the outer side of the frame 112 becomes a mounting area for connecting various electronic components.

[0034] The frame 112 is fixed to one main surface of the substrate 111 by an adhesive or the like. The frame 112 surrounds the supply port 1111, multiple discharge ports 1112, and actuator 113 provided on the substrate 111.

[0035] For example, the frame 112 is formed in a rectangular frame shape, thereby forming an opening that is longer in one direction along the length of the frame 112. The frame 112 may also have a stepped structure with a portion of its surface recessed. A pair of actuators 113, a supply port 1111, and four discharge ports 1112 are arranged in the opening of the frame 112. The frame 112 is configured to surround the actuators 113 between the nozzle plate 114 and the base plate 111, and is capable of holding liquid inside.

[0036] A pair of actuators 113 are bonded to the surface 115 of the substrate 111. The pair of actuators 113 are arranged in two rows on the substrate 111 across the supply port 1111. The actuators 113 are formed as plates that are longer in one direction. The actuators 113 are disposed within the opening of the frame 112 and are bonded to the surface 115 of the substrate 111.

[0037] like Figures 5 to 9 As shown, the actuator 113 has, on its central side in the longitudinal direction, a plurality of pressure chambers 1131, equally spaced in the longitudinal direction, and air chambers 1132, equally spaced in the longitudinal direction, disposed between adjacent pressure chambers 1131. In other words, the actuator 113 has a plurality of pressure chambers 1131 and air chambers 1132 alternately arranged along the longitudinal direction. The plurality of pressure chambers 1131 and the plurality of air chambers 1132 extend in a direction intersecting the arrangement direction, for example, in the direction of the shorter side of the actuator 113.

[0038] The top surface of the actuator 113, which is the side opposite to the substrate 111, is bonded to the nozzle plate 114. The actuator 113 has a plurality of slots arranged at equal intervals along its length and perpendicular to the length direction. These slots form a plurality of pressure chambers 1131 and a plurality of air chambers 1132. In other words, the actuator 113 has a plurality of piezoelectric elements 1133 arranged at equal intervals along its length and serving as driving elements constituting the walls of the slots formed therebetween. The plurality of piezoelectric elements 1133 form a plurality of pressure chambers 1131 and a plurality of air chambers 1132 between adjacent piezoelectric elements 1133, and the volume of the pressure chambers 1131 changes when a driving voltage is applied.

[0039] The actuator 113, for example, has a width that gradually increases from the top side toward the substrate 111 in the short side direction. The cross-sectional shape of the actuator 113 along the direction orthogonal to the length direction (short side direction) is formed as a trapezoid. That is, the actuator 113 has an inclined surface 1134 that slopes toward the side portion in the short side direction. The side portion (inclined surface 1134) is disposed opposite to the first common liquid chamber 1161 and the second common liquid chamber 1162. A second electrode portion 1182 that is part of a plurality of independent electrodes 118 and a second electrode portion 1192 that is part of a single or multiple common electrodes 119 are formed on the inclined surface 1134.

[0040] As a specific example, the actuator 113 is formed by bonding two rectangular piezoelectric materials, each longer in one direction, together with their polarization directions opposite to each other. Here, the piezoelectric material is, for example, PZT (lead zirconate titanate). The actuator 113 is bonded to the surface 115 of the substrate 111 using, for example, a thermosetting epoxy adhesive. Furthermore, the actuator 113 is formed with an inclined surface 1134, for example, through machining. Simultaneously, the substrate 111 and the actuator 113 are ground, for example, on the surface 115 where multiple individual electrodes 118 and a common electrode 119 are patterned, to form a ground surface. Additionally, the actuator 113 is formed with multiple grooves, for example, through machining, and piezoelectric elements (driving elements) 1133 are formed as sidewalls separating adjacent grooves. These grooves form multiple pressure chambers 1131 and multiple air chambers 1132.

[0041] In addition, the actuator 113 includes a first electrode portion 1181 and a second electrode portion 1182 that are part of a plurality of independent electrodes 118, and a first electrode portion 1191 and a second electrode portion 1192 that are part of a single or a plurality of common electrodes 119.

[0042] During printing or other operations using the liquid ejector head 1, the pressure chamber 1131 deforms to eject ink from the nozzle 1141. The inlet of the pressure chamber 1131 opens into the first common liquid chamber 1161, and the outlet opens into the second common liquid chamber 1162. Ink flows into the pressure chamber 1131 from the inlet and flows out from the outlet. It should be noted that the pressure chamber 1131 can also have a structure where ink flows in from both openings, described as the inlet and outlet. First electrode portions 1181, which are part of a plurality of independent electrodes 118, are formed within the groove constituting the pressure chamber 1131.

[0043] like Figure 9 As shown, the air chamber 1132 is separated from the first common liquid chamber 1161 and the second common liquid chamber 1162 by being sealed at the inlet and outlet sides by a liquid-proof wall 1135 formed of photosensitive resin or the like. Specifically, the liquid-proof wall 1135 of the air chamber 1132 is formed by injecting ultraviolet-curable resin into the tank forming the air chamber 1132, and then using an exposure mask or the like to irradiate necessary portions, such as the two ends of the tank's inlet and outlet sides, with ultraviolet light. This liquid-proof wall 1135 prevents ink from entering the air chamber 1132. Furthermore, the air chamber 1132 is sealed by a nozzle plate 114, and no nozzle 1141 is provided. Therefore, ink does not flow into the air chamber 1132. A first electrode portion 1191, which is part of one or more common electrodes 119, is formed within the air chamber 1132.

[0044] The nozzle plate 114 is formed in a plate shape. The nozzle plate 114 is fixed to the main surface of the frame 112 on the side opposite to the base plate 111 by an adhesive or the like. The nozzle plate 114 has a plurality of nozzles 1141 formed at positions opposite to the plurality of pressure chambers 1131. In this embodiment, the nozzle plate 114 has two rows of nozzles 1141 arranged in one direction as a nozzle row 1142.

[0045] A first common liquid chamber 1161 is formed between the central sides of a pair of actuators 113, excluding the two ends, forming a flow path for ink flowing from the supply port 1111 to the openings (inlets) on the primary side of the plurality of pressure chambers 1131 of each actuator 113. The first common liquid chamber 1161 extends along the length of the actuator 113.

[0046] Second common liquid chambers 1162 are formed between each actuator 113 and the frame 112. The second common liquid chamber 1162 forms a flow path for ink flowing from the openings (outlets) on the secondary side of the plurality of pressure chambers 1131 to the discharge port 1112. The second common liquid chamber 1162 extends along the length of the actuator 113.

[0047] Multiple independent electrodes 118 individually apply driving voltages to multiple piezoelectric elements 1133, which are piezoelectric elements. The multiple independent electrodes 118 individually deform each pressure chamber 1131. The independent electrodes 118 are formed by wiring patterns formed on a substrate 111 and wiring patterns formed on an actuator 113. The independent electrodes 118 extend from either the pressure chamber 1131 or the air chamber 1132 to one side in the extending direction. In this embodiment, they extend from the pressure chamber 1131 to the region outside the pair of actuators 113.

[0048] As a specific example, such as Figures 7 to 9 As shown, multiple independent electrodes 118 are formed on the inner surface of each pressure chamber 1131, the inclined surface 1134 of the actuator 113, and the substrate 111. Specifically, the independent electrodes 118 are formed on the side of the piezoelectric body 1133 forming the pressure chamber 1131, and as part of the piezoelectric component constituting the bottom of the pressure chamber 1131. In addition, the independent electrodes 118 are formed, for example, on the inclined surface 1134 and the surface 115 of the substrate 111. The independent electrodes 118 extend from inside the pressure chamber 1131 toward the end of the substrate 111 in the short side direction, and the end of the independent electrode 118 is disposed at the connection portion 1116 of the substrate 111 that connects to the circuit board 14. That is, the individual electrodes 118 each have a first electrode portion 1181, a second electrode portion 1182, and a third electrode portion 1183. The first electrode portion 1181 is formed within a groove in the pressure chamber 1131 constituting the actuator 113, the second electrode portion 1182 is formed on the inclined surface 1134 of the actuator 113, and the third electrode portion 1183 is formed on the surface 115 of the substrate 111. The individual electrodes 118 are configured to be in close contact with the bottom of the pressure chamber 1131 and the surface of the piezoelectric member forming the piezoelectric body 1133. The individual electrodes 118 are formed, for example, from a nickel thin film. It should be noted that the individual electrodes 118 can also be formed from, for example, a thin film of gold or copper, and are not limited to a nickel thin film. The thickness of the individual electrodes 118 is, for example, 0.5 μm to 5 μm.

[0049] The common electrode 119 applies the same driving voltage to all of the plurality of piezoelectric elements 1133. The common electrode 119 causes the plurality of pressure chambers 1131 to deform simultaneously. The common electrode 119 is formed by wiring patterns formed on the substrate 111 and wiring patterns formed on the actuator 113. The common electrode 119 extends from the inner peripheral surface of the supply port 1111 of the substrate 111 to the wiring patterns of the piezoelectric elements 1133 forming the plurality of air chambers 1132. The common electrode 119 is connected to the circuit board 14. The common electrode 119 extends from one of the pressure chambers 1131 and the air chambers 1132 to the other side in the extending direction. In this embodiment, the common electrode 119 extends from the air chambers 1132 to the region between the pair of actuators 113. That is, the electrodes of the plurality of air chambers 1132 are bundled together on the central side of the substrate as the common electrode 119.

[0050] As a specific example, such as Figures 7 to 9 As shown, the common electrode 119 is formed on the inner surface of each air chamber 1132, the inclined surface 1134 of the actuator 113, and the area on the substrate 111 that avoids the individual electrodes 118. That is, the common electrode 119 is formed on the side of the piezoelectric body 1133 forming each air chamber 1132 and is part of the piezoelectric member constituting the bottom of the air chamber 1132. In addition, the common electrode 119 is disposed on the inclined surface 1134 from inside each air chamber 1132 toward the center of the substrate 111, and is formed on the surface 115 of the substrate 111 between the pair of actuators 113 and the inner peripheral surface of the supply port 1111. In addition, the common electrode 119 extends toward the end of the substrate 111 in the longitudinal direction and is also formed on the end face 1114 of the substrate 111 in the longitudinal direction (Y direction) and the back surface 117 of the substrate 111, which is the main surface opposite to the surface 115. For example, the common electrode 119 extends to the end of the short side of the substrate 111, and the end of the common electrode 119 is disposed in the connection portion 1116 of the substrate 111 that is connected to the circuit board 14.

[0051] In other words, the common electrode 119 is disposed on the central side of the substrate 111 in the short-side direction, and this central side is located between the connection portion 1116 formed on the end of the substrate 111 in the short-side direction and the pair of actuators 113. Furthermore, as... Figure 7 As shown, a portion of the common electrode 119, located at the center side of the short side of the substrate 111, is provided on the inner peripheral surface of the supply port 1111 in such a way that it extends in the thickness direction of the substrate 111 at the center side of the short side of the substrate 111. Additionally, a portion of the common electrode 119 extends from the center side of the short side of the substrate 111 onto the surface of the piezoelectric member forming each air chamber 1132. Furthermore, a portion of the common electrode 119 is also provided on the end face 1114 and the back face 117 in the length direction of the substrate 111.

[0052] That is, the common electrode 119 has: a first electrode portion 1191 formed in a groove constituting the air chamber 1132 of the actuator 113; a second electrode portion 1192 formed on the inclined surface 1134 of the actuator 113; a third electrode portion 1193 formed on the surface 115 of the substrate 111; a fourth electrode portion 1194 formed on the inner peripheral surface of the supply port 1111; a fifth electrode portion 1195 formed on the end face 1114 in the longitudinal direction of the substrate 111; a sixth electrode portion 1196 formed on the back surface 117 of the substrate 111; a seventh electrode portion 1197 formed on the inner peripheral surface of the through hole 1113; and an eighth electrode portion 1198 formed on the inner peripheral surface of the discharge port 1112. Each electrode portion 1191 to 1198 of the common electrode 119 is formed away from the individual electrode 118, other mounting components, etc. Each electrode portion 1191 to 1198 of the common electrode 119 may also be partially formed on the surface of the substrate 111 and the actuator 113.

[0053] In the common electrode 119, the third electrode portion 1193 on the surface 115 of the substrate 111 and the sixth electrode portion 1196 on the back surface 117 are connected by the fourth electrode portion 1194 in the supply port 1111, the fifth electrode portion 1195 on the end face 1114, the seventh electrode portion 1197 in the through hole 1113, and the eighth electrode portion 1198 in the discharge port 1112.

[0054] The common electrode 119 is configured to be in close contact with the bottom of the air chamber 1132 and the surface of the piezoelectric component forming the piezoelectric body 1133. The common electrode 119 is formed, for example, a nickel thin film. It should be noted that the common electrode 119 may also be formed of a thin film of, for example, gold or copper, and is not limited to a nickel thin film. The thickness of the common electrode 119 is, for example, 0.5 μm to 5 μm.

[0055] For example, the individual electrode 118 and the common electrode 119 are covered by a coating 120 inside the frame 112. Alternatively, the individual electrode 118 may also be covered on the lower surface of the frame 112 by an adhesive that bonds the frame 112 to the substrate 111.

[0056] Coating 120 is formed in a region within the housing 112 on the surface of the actuator 113 and the surface 115 of the substrate 111. Coating 120 covers the surface 115 of the substrate 111, including a region where at least a portion of the individual electrodes 118 and the common electrode 119 are formed. Coating 120 is, for example, a film formed by spraying, and is composed of, for example, a thermosetting epoxy adhesive. For example, the thickness of coating 120 is 5–30 μm. Coating 120 covers a portion of the inclined surface 1134 of the actuator 113 and the surface 115 of the substrate 111. As an example, coating 120 is formed on the surface 115 of the substrate 111 at least in the region surrounded by the housing 112. For example, coating 120 is formed in the region on the inner periphery of the housing 112 and the region directly below the housing 112. In other words, coating 120 is not formed in the mounting region outside the housing 112 and the back surface 117 of the surface 115.

[0057] The coating 120 is formed, for example, by applying a coating agent by spraying after forming an electrode by providing an actuator 113 on a substrate 111.

[0058] like Figure 1 , Figure 4 and Figure 5 As shown, the manifold unit 12 includes a manifold 121, a top plate 122, an ink supply pipe 123, an ink discharge pipe 124, and a cooling water supply pipe 125 and a cooling water discharge pipe 126, which are a pair of temperature-regulating pipes. It should be noted that the number of ink supply pipes 123, ink discharge pipes 124, cooling water supply pipes 125, and cooling water discharge pipes 126 can be appropriately set.

[0059] Manifold 121 is formed in a plate-like or block-like shape. For example... Figure 5 As shown, the manifold 121 includes: a supply flow path 1211, which is continuous with the supply port 1111 of the substrate 111 to form a liquid supply flow path; a discharge flow path, which is continuous with the discharge port 1112 of the substrate 111 to form a liquid discharge flow path; and a first cooling flow path 1213, which forms a flow path for cooling fluid. It should be noted that since the manifold 121 is connected to a pair of nozzle bodies 11, it has a pair of supply flow paths 1211 and a pair of discharge paths.

[0060] Manifold 121 is formed, for example, by assembling multiple manifold components into one piece, forming a supply flow path 1211, an exhaust flow path, and a first cooling flow path 1213.

[0061] One main surface of the manifold 121 is fixed to the back surface 117 of the substrate 111, which is the other side of the main surface. Additionally, a top plate 122 is fixed to the manifold 121 on the main surface opposite to the main surface on which the substrate 111 is fixed. Furthermore, an ink supply pipe 123, an ink discharge pipe 124, a cooling water supply pipe 125, and a cooling water discharge pipe 126 are fixed to the manifold 121 via the top plate 122.

[0062] The supply flow path 1211 is a flow path formed by holes and grooves in the manifold 121. The supply flow path 1211 fluidly connects the ink supply pipe 123 and the supply port 1111 of the substrate 111.

[0063] The discharge path is a flow path formed by holes and grooves in the manifold 121. The discharge path fluidly connects the ink discharge pipe 124 and the discharge port 1112 of the substrate 111.

[0064] The first cooling flow path 1213 is a flow path formed by holes and grooves in the manifold 121. The first cooling flow path 1213 fluidly connects the cooling water supply pipe 125 and the cooling water discharge pipe 126.

[0065] The first cooling flow path 1213 has openings at both ends that connect to a cooling water supply pipe 125 and a cooling water discharge pipe 126 provided on one main surface of the manifold 121. In addition, the first cooling flow path 1213 is configured to exchange heat with the substrate 111 fixed to the manifold 121.

[0066] The top plate 122 is disposed on the side of the manifold 121 opposite to the side on which the base plate 111 is disposed. The top plate 122 seals the supply flow path 1211, the discharge flow path, and the first cooling flow path 1213 by covering the manifold 121.

[0067] In addition, the top plate 122 has an opening that connects the pipes 123, 124, and 125 and connects the pipes 123, 124, and 125 with the flow paths 1211 and 1213.

[0068] The ink supply pipe 123 is connected to the supply flow path 1211. The ink discharge pipe 124 is connected to the discharge flow path. The cooling water supply pipe 125 and the cooling water discharge pipe 126 are connected to the primary and secondary sides of the first cooling flow path 1213, respectively.

[0069] In this embodiment, a pair of ink supply pipes 123 and a first cooling water discharge pipe 126 are arranged at one end of the manifold 121 along its length, and a pair of ink discharge pipes 124 and a first cooling water supply pipe 125 are arranged at the other end of the manifold 121 along its length.

[0070] The cooling flow path unit 13 has multiple second cooling flow paths 1312, a second cooling water supply pipe 133, and a second cooling water discharge pipe 134. Multiple openings 1314 are formed between the multiple second cooling flow paths 1312 in the cooling flow path unit 13. The cooling flow path unit 13 is connected to the cooling device 2116 of the liquid ejection device 2. The second cooling flow paths 1312 are longer in one direction (first direction X) and arranged in a direction orthogonal to the length direction of the second cooling flow paths 1312 (second direction Y).

[0071] As a specific example, in this embodiment, there are 4 rows of nozzles 1142, 4 actuators 113 (4 rows), and 4 driver ICs 142 (4 rows). Therefore, the cooling flow path unit 13 has three second cooling flow paths 1312, and two openings 1314 are formed between the second cooling flow paths 1312.

[0072] Multiple second cooling flow paths 1312 are connected to the second cooling water supply pipe 133 and the second cooling water discharge pipe 134.

[0073] The cooling flow path unit 13 has a portion of the driver IC 142 (described later) and the printed wiring board 143 arranged in a plurality of openings 1314. A plurality of second cooling flow paths 1312 are arranged opposite to the driver IC 142, which is a heat source, thereby cooling the driver IC 142.

[0074] like Figure 4 As shown, the circuit board 14 includes a driver IC 142 with one end connected to the connection portion 1116 of the board 111, and a printed wiring board 143.

[0075] The circuit board 14 drives the actuator 113 by applying a driving voltage to the wiring pattern of the actuator 113 using the driver IC 142, thereby increasing or decreasing the volume of the pressure chamber 1131, so that the droplets are ejected from the nozzle 1141.

[0076] The driver IC 142 is connected to a plurality of individual electrodes 118 and a common electrode 119 via an ACF (anisotropic conductive film) fixed to the connection portion of the substrate 111 by means such as thermoforming. It should be noted that the driver IC 142 can also be connected to the plurality of individual electrodes 118 and the common electrode 119 by other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste). For example, multiple driver ICs 142 are provided for a single nozzle body 11. In this embodiment, two driver ICs 142 are connected to one actuator 113. The driver IC 142 is, for example, a COF (chip-on-film) with a driver IC chip mounted on it.

[0077] The surface of the driver IC142 is in contact with the outer surface of the second cooling flow path 1312.

[0078] The printed wiring board 143 is a PWA (Printing Wiring Assembly) that carries various electronic components and connectors.

[0079] The cover 15, for example, has an outer contour 151 and a mask 152. The outer contour 151 covers the sides of a pair of nozzle bodies 11, the manifold unit 12 and the circuit board 14, and the mask 152 covers a portion of the nozzle plate 114 side of the pair of nozzle bodies 11.

[0080] The outer contour 151 exposes, for example, the ink supply pipe 123, ink discharge pipe 124, cooling water supply pipe 125 and cooling water discharge pipe 126 in the manifold unit 12, as well as the end of the circuit board 14, to the outside.

[0081] The mask 152 covers the portion of a pair of nozzle bodies 11 except for the area around the plurality of nozzles 1141 and the plurality of nozzles 1141 of the nozzle plate 114.

[0082] The liquid nozzle 1 thus configured has multiple independent electrodes 118 in the nozzle body 11 that can individually apply driving voltage to each piezoelectric element 1133, and a common electrode 119 that can apply driving voltage to all piezoelectric elements 1133.

[0083] Therefore, the liquid ejector head 1 can selectively, individually, or jointly drive multiple pressure chambers 1131. Furthermore, when a pressure chamber 1131 is driven, it undergoes shear-mode deformation, pressurizing the ink supplied to it. Thus, the liquid ejector head 1 can selectively eject the pressurized ink from a nozzle 1141 opposite the pressure chamber 1131.

[0084] In addition, the common electrode 119 is formed not only on the surface 115 of the actuator 113, the inclined surface 1134 of the actuator 113, and the inner surface of the air chamber 1132 of the substrate 111, but also on the inner peripheral surface of the supply port 1111 formed on the substrate 111.

[0085] Below, refer to Figure 10 The inkjet recording apparatus 2 having a liquid ejector head 1 will be described. The inkjet recording apparatus 2 includes a housing 2111, a media supply unit 2112, an image forming unit 2113, a media discharge unit 2114, a transport device 2115 as a support device, a maintenance device 2117, and a control unit 2118. Furthermore, the inkjet recording apparatus 2 includes a cooling device for adjusting the temperature of the ink supplied to the liquid ejector head 1.

[0086] The inkjet recording apparatus 2 is an inkjet printer that performs image forming processing on paper P by conveying, for example, paper P as a recording medium to be ejected, along a predetermined transport path 2001 from the media supply unit 2112 through the image forming unit 2113 to the media discharge unit 2114, and ejecting liquid such as ink.

[0087] The media supply unit 2112 includes multiple paper feed trays 21121. The image forming unit 2113 includes a support 2120 for supporting paper and multiple printhead units 2130 disposed opposite each other above the support 2120. The media discharge unit 2114 includes a paper discharge tray 21141.

[0088] The support portion 2120 includes: a conveyor belt 21201 arranged in a ring shape in a predetermined area for image formation; a support plate 21202 supporting the conveyor belt 21201 from the back side; and a plurality of belt rollers 21203 arranged on the back side of the conveyor belt 21201.

[0089] The printhead unit 2130 includes: a plurality of liquid ejector heads 1 serving as inkjet heads; a plurality of supply tanks 2132 serving as liquid tanks respectively mounted on each liquid ejector head 1; a pump 2134 for supplying ink; and a connection flow path 2135 connecting the liquid ejector head 1 and the supply tanks 2132.

[0090] In this embodiment, a liquid nozzle 1 with four colors—cyan, magenta, yellow, and black—is used as the liquid nozzle 1, and four color supply tanks 2132 are used to respectively contain inks of these colors. The supply tanks 2132 are connected to the liquid nozzle 1 via a connecting flow path 2135.

[0091] Pump 2134 is, for example, a liquid delivery pump composed of a piezoelectric pump. Pump 2134 is connected to control unit 2118 and is driven and controlled by control unit 2118.

[0092] The connecting flow path 2135 includes a supply flow path connected to the ink supply pipe 123 of the liquid nozzle 1. Additionally, the connecting flow path 2135 includes a recovery flow path connected to the ink discharge pipe 124 of the liquid nozzle 1. For example, when the liquid nozzle 1 is non-circulating, the recovery flow path is connected to the maintenance device 2117; when the liquid nozzle 1 is circulating, the recovery flow path is connected to the supply tank 2132.

[0093] The conveying device 2115 conveys paper P along a conveying path 2001 from the paper feed cassette 21121 of the media supply unit 2112 through the image forming unit 2113 to the paper discharge tray 21141 of the media discharge unit 2114. The conveying device 2115 includes multiple guide plates 21211-21218 arranged along the conveying path 2001, and multiple conveying rollers 21221-21228. The conveying device 2115 supports the paper P so that it can move relative to the liquid ejector head 1.

[0094] The cooling device 2116 includes a cooling water tank 21161, a cooling circuit 21162 such as piping or conduit for supplying cooling water, a pump for supplying cooling water, and a cooler for adjusting the temperature of the cooling water. The cooling device 2116 supplies cooling water from the cooling water tank 21161, which has been adjusted to a predetermined temperature by the cooler, to the second cooling water supply pipe 133 via the cooling circuit 21162, through the pump. Additionally, the cooling device 2116 recovers water discharged from the first cooling flow path 1213 and the second cooling flow path 1312 and from the second cooling water discharge pipe 134 back to the cooling water tank 21161 via the cooling circuit 21162. It should be noted that the cooler is, for example, a cooling device.

[0095] The maintenance device 2117, for example, draws in and recovers ink remaining on the outer surface of the nozzle plate 114 during maintenance. Additionally, in the case where the liquid nozzle 1 is non-circulating, the maintenance device 2117 recovers ink within the nozzle body 11 during maintenance. Such a maintenance device 2117 includes a tray or container for storing the recovered ink.

[0096] The control unit 2118 includes: a CPU 21181, which is an example of a processor; a memory such as ROM (Read-Only Memory) for storing various programs, RAM (Random Access Memory) for temporarily storing various variable data and image data; and an interface unit for inputting data from the outside and outputting data to the outside.

[0097] With the liquid ejector head 1 and inkjet recording apparatus 2 configured in this way, a high printing quality can be ensured because a common electrode 119 is also formed on the end face 1114 of the substrate 111. That is, in the liquid ejector head 1, the electrode portions 1193 and 1196 on the surface 115 side and the back side 117 side of the substrate 111 are connected through the electrode portion 1195 on the end face 1114. Therefore, even if the electrode is partially dissolved by the ink containing components that dissolve the electrode, the area of ​​the common electrode 119 can be ensured. For example, if the coating 120 is not formed on the back side 117 of the substrate 111, even if a portion of the common electrode 119 on the back side 117 of the substrate 111 disappears around the supply port 1111, the connection between the common electrode 119 on the surface 115 and the back side 117 is ensured by the electrode portion 1195 formed on the end face 1114 outside the area where the ink is disposed, thereby suppressing the increase in the resistance of the common electrode 119. Therefore, it can suppress the difference in drive waveform between the ends and the center of the column when the liquid is sprayed out, and can maintain the printing quality such as dot diameter and straightness.

[0098] Furthermore, a common electrode 119 is also provided on the inner circumferential surface of the liquid ejector head 1 at the supply port 1111, thereby ensuring the electrode surface area of ​​the common electrode 119 and reducing its resistance. Therefore, even when the spacing between the piezoelectric elements 1133 of the actuator 113 narrows, it is possible to suppress the difference in ejection performance between the central side and the end side in the arrangement direction of the nozzles 1141 of the nozzle body 11.

[0099] In addition, in the above embodiment, a common electrode 119 is also provided in the through hole 1113 formed on the outside of the frame 112 and in a part that does not come into contact with the ink. The connection between the common electrode 119 on the surface 115 and the back surface 117 can be ensured through the through hole 1113, thereby reducing the resistance of the common electrode 119.

[0100] It should be noted that the embodiments of the present invention are not limited to the structures described above. Several examples of embodiments are shown below. Furthermore, in the embodiments described below, the same symbols are used to denote the same structures as in the first embodiment described above, and detailed descriptions thereof are omitted.

[0101] For example, in the above example, the following example is shown: a supply port 1111, which serves as an elongated hole, is arranged between a pair of actuators 113, and discharge ports 1112 are respectively arranged at both ends of the pair of actuators 113 along their length. A through hole 1113 is arranged at the outermost end. However, this is not a limitation, and the shape, number, and arrangement of the supply port 1111, discharge port 1112, and through hole 1113 can be appropriately set. For example, it is also possible for the common electrode 119 not to be formed on the inner circumferential surface of the discharge port 1112. Alternatively, it is also possible for the through hole 1113 not to be present. Even in such an arrangement, the connection state of the common electrode 119 can be maintained by forming an electrode on the end face 1114.

[0102] For example, in the above example, an example is shown where an individual electrode 118 is formed in the pressure chamber 1131 and a common electrode 119 is formed in the air chamber 1132, but it is not limited to this. For example, it is also possible to have a structure where the common electrode 119 is formed in the pressure chamber 1131 and the individual electrode 118 is formed in the air chamber 1132.

[0103] For example, in the above example, the liquid nozzle 1 is described as having a structure with a pair of nozzle bodies 11, but it is not limited to this; it can also be configured to have only one nozzle body 11. Furthermore, the nozzle body 11 is described as having a structure with a pair of actuators 113, but it is not limited to this. For example, the nozzle body 11 can also be configured to have only one actuator 113.

[0104] Alternatively, the pressure chamber 1131 may have a throttling section at its inlet and outlet. For example, in another embodiment of the liquid nozzle, the pressure chamber 1131 may also have a throttling section at its inlet opening to the first common liquid chamber 1161 and / or its outlet opening to the second common liquid chamber 1162, which narrows the flow path by reducing the size of the opening. The throttling section is, for example, a protrusion or wall-like component formed of UV-curable resin that blocks part of the inlet and outlet, increasing the flow resistance at the inlet and outlet of the pressure chamber 1131.

[0105] Furthermore, the above example illustrates a non-circulating liquid nozzle 1, but the liquid nozzle 1 can also be a circulating nozzle.

[0106] Furthermore, in the above embodiment, as an example, an inkjet head is shown where one side of the pressure chamber 1131 is the supply side and the other side is the discharge side, and ink flows in from one side of the pressure chamber 1131 and flows out from the other side, but it is not limited to this. For example, it may also be a structure where a common chamber on both sides of the pressure chamber 1131 is the supply side and ink flows in from both sides. In addition, the supply side and the discharge side may be reversed, or it may be configured to be switchable.

[0107] Furthermore, while the above embodiments illustrate a side-firing inkjet head, the invention is not limited to this and can also be end-firing.

[0108] In addition, for example, the liquid ejected is not limited to ink for printing; it could also be a device that ejects a liquid containing conductive particles for forming wiring patterns on a printed wiring substrate.

[0109] Furthermore, while the above embodiments illustrate an example of using an inkjet head for liquid ejection devices such as inkjet printers, the invention is not limited to this and can also be used in applications such as 3D printers, industrial manufacturing machinery, and medical applications, enabling miniaturization, lightweighting, and cost reduction.

[0110] According to at least one embodiment described above, since a common electrode is formed on the end face of the substrate, high printing quality can be ensured.

[0111] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. A liquid ejector head, characterized in that, have: The substrate has openings for liquid to pass through; An actuator is disposed on a main surface of one side of the substrate and has a plurality of pressure chambers and a plurality of air chambers formed between the plurality of pressure chambers; A manifold is disposed on the other side of the substrate; A common electrode has an electrode portion formed on the surface of the actuator, a main surface on one side of the substrate, a main surface on the other side of the substrate, an inner surface of the opening, and an electrode portion on the side of the substrate. An independent electrode has an electrode portion formed on the surface of the actuator and on one side of the substrate. as well as A coating covering at least a portion of one side of the main surface of the substrate. The common electrode is a wiring pattern extending from the inner peripheral surface of the opening on the substrate to the piezoelectric body forming the plurality of air chambers. The common electrode is formed on the inner surface of each air chamber, the inclined surface of the actuator, and the area on the substrate that avoids the individual electrodes.

2. The liquid ejector head according to claim 1, characterized in that, It also has: A frame is disposed around the actuator on a main surface of one side of the substrate; and A nozzle plate, disposed on one side of the frame, has a nozzle communicating with the pressure chamber. The plurality of pressure chambers and the plurality of air chambers are arranged alternately in one direction and extend in directions intersecting the arrangement direction. The side surface of the substrate is the end face of the substrate in one direction, and the side surface of the substrate is disposed outside the frame.

3. The liquid ejector head according to claim 1, characterized in that, The opening is an elongated hole extending in one direction, penetrating the substrate, and has an inner peripheral surface continuous with the main surface of both the other side. The opening is a supply port for supplying liquid from the other side of the substrate to one side of the substrate. The manifold forms a flow path that communicates with the opening.

4. The liquid ejector head according to claim 2, characterized in that, The substrate also has a discharge port that extends through the substrate. A through-hole is formed on the substrate at a position further outward than the frame. The common electrode has at least one of an electrode portion formed on the inner wall of the through hole and an electrode portion formed on the inner wall of the outlet.

5. The liquid ejector head according to claim 3, characterized in that, A pair of actuators are disposed on the substrate. The supply port is provided in the area between the pair of actuators. The common electrode extends from the pair of actuators to the region between the pair of actuators. The independent electrode extends from the pair of actuators to the region outside the pair of actuators.

6. An inkjet recording device, characterized in that, A liquid nozzle is used, the liquid nozzle comprising: The substrate has openings for liquid to pass through; An actuator is disposed on a main surface of one side of the substrate and has a plurality of pressure chambers and a plurality of air chambers formed between the plurality of pressure chambers; A manifold is disposed on the other side of the substrate; A common electrode has an electrode portion formed on the surface of the actuator, a main surface on one side of the substrate, a main surface on the other side of the substrate, an inner surface of the opening, and an electrode portion on the side of the substrate. An independent electrode has an electrode portion formed on the surface of the actuator and on one side of the substrate. as well as A coating covering at least a portion of one side of the main surface of the substrate. The common electrode is a wiring pattern extending from the inner peripheral surface of the opening on the substrate to the piezoelectric body forming the plurality of air chambers. The common electrode is formed on the inner surface of each air chamber, the inclined surface of the actuator, and the area on the substrate that avoids the individual electrodes.

7. The inkjet recording apparatus according to claim 6, characterized in that, The liquid ejector head also features: A frame is disposed around the actuator on a main surface of one side of the substrate; and A nozzle plate, disposed on one side of the frame, has a nozzle communicating with the pressure chamber. The plurality of pressure chambers and the plurality of air chambers are arranged alternately in one direction and extend in directions intersecting the arrangement direction. The side surface of the substrate is the end face of the substrate in one direction, and the side surface of the substrate is disposed outside the frame.

8. The inkjet recording apparatus according to claim 6, characterized in that, The opening is an elongated hole extending in one direction, penetrating the substrate, and has an inner peripheral surface continuous with the main surface of both the other side. The opening is a supply port for supplying liquid from the other side of the substrate to one side of the substrate. The manifold forms a flow path that communicates with the opening.

9. The inkjet recording apparatus according to claim 7, characterized in that, The substrate also has a discharge port that extends through the substrate. A through-hole is formed on the substrate at a position further outward than the frame. The common electrode has at least one of an electrode portion formed on the inner wall of the through hole and an electrode portion formed on the inner wall of the outlet.

10. The inkjet recording apparatus according to claim 8, characterized in that, A pair of actuators are disposed on the substrate. The supply port is provided in the area between the pair of actuators. The common electrode extends from the pair of actuators to the region between the pair of actuators. The independent electrode extends from the pair of actuators to the region outside the pair of actuators.

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