Liquid dispensing head

Abstract

To provide a liquid discharge head which can suppress deterioration of print quality.SOLUTION: A liquid discharge head includes a substrate, an actuator, a manifold, a common electrode, an individual electrode, and a coating layer. The substrate includes an opening passing a liquid therethrough. The actuator is provided on a main surface on 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 arranged on the other side of the substrate. The common electrode has electrode parts formed on the surface of the actuator, the main surface on the one side of the substrate, the main surface on the other side of the substrate, the inner surface of the opening, and the side face of the substrate. The individual electrode has the electrode parts formed on the surface of the actuator and the main surface on the one side of the substrate. The coating layer covers at least a part of the main surface on the one side of the substrate.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head.

Background Art

[0002] In a liquid ejection head, there is known a liquid ejection head provided with an actuator in which a plurality of partition walls are formed at a predetermined interval and pressure chambers are formed between the partition walls. As a liquid ejection head, there is also known a liquid ejection head using an independent drive structure having a pressure chamber for ejecting liquid from a nozzle and an air chamber for not ejecting liquid in order to increase the speed of liquid ejection.

[0003] In a liquid ejection head having an independent drive structure, there is an example in which electrodes of a pressure chamber are bundled on the central side of a substrate for common electrode polarization, and electrodes of an air chamber are drawn out to the opposite side as individual electrodes. For example, the common electrode is formed on the surface of the substrate, the inner surface of the supply hole, and the back surface of the substrate, and a coating layer is formed on the surface of the substrate.

[0004] In such a liquid ejection head, when, for example, ink containing a component that dissolves an electrode is used, the common electrode on the back surface of the substrate may disappear and the electrodes on the surface and the back surface may be separated. In this case, the common electrode resistance increases, and when liquid is ejected, a difference occurs in the drive waveform between the end portion and the central portion in a column, and printing quality such as dot diameter and linearity deteriorates.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem to be solved by the present invention is to provide a liquid ejection head capable of ensuring high printing quality.

Means for Solving the Problems

[0007] The liquid discharge head of the embodiment comprises a substrate, an actuator, a manifold, a common electrode, individual electrodes, and a coating layer. The substrate has an opening through which liquid passes. The actuator is provided on one main surface 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 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 layer covers at least a portion of the main surface of one side of the substrate. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing the configuration of a liquid dispensing head according to the first embodiment. [Figure 2] A bottom view showing the configuration of a liquid dispensing head according to the first embodiment. [Figure 3] A bottom view showing the configuration of the liquid discharge head according to the first embodiment, with some parts omitted. [Figure 4] A perspective view showing the configuration of the head body of the liquid discharge head according to the first embodiment. [Figure 5] A cross-sectional view showing the configuration of the head body according to the first embodiment. [Figure 6] A plan view showing the configuration of the head body according to the first embodiment. [Figure 7] A cross-sectional view showing the configuration of the head body according to the first embodiment, with some parts omitted. [Figure 8] A cross-sectional view showing the configuration of the head body according to the first embodiment, with some parts omitted. [Figure 9] A cross-sectional view showing the configuration of the head body according to the first embodiment, with some parts omitted. [Figure 10] An explanatory diagram showing the configuration of a liquid dispensing device according to the first embodiment. [Modes for carrying out the invention]

[0009] Below, a liquid discharge head 1 and a liquid discharge device 2 using the liquid discharge head 1 according to the first embodiment will be described with reference to Figures 1 to 9. Figure 1 is a perspective view showing the configuration of the liquid discharge head 1 according to the first embodiment, and Figure 2 is a bottom view showing the configuration of the liquid discharge head 1. Figure 3 is a bottom view showing the configuration of the liquid discharge head 1 with the nozzle plate 114 omitted. Figure 4 is a perspective view showing the configuration of the head body 11 of the liquid discharge head 1, and Figure 5 is a cross-sectional view showing the configuration of the head body 11. Figure 6 is a plan view showing the configuration of the substrate 111, actuator 113, multiple individual electrodes 118 and common electrode 119 of the head body 11. Figure 7 is a cross-sectional view showing the configuration of the substrate 111, actuator 113, multiple individual electrodes 118 and common electrode 119 of the head body 11. Figure 8 is a cross-sectional view showing the configuration of the substrate 111, actuator 113 and common electrode 119 of the head body 11. Figure 9 is a cross-sectional view showing the configuration of the actuator 113, multiple individual electrodes 118, and common electrode 119 of the head body 11. Figure 10 is an explanatory diagram showing the configuration of the liquid discharge device 2 using the liquid discharge head 1. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for explanatory purposes. In the figures, X, Y, and Z indicate the first, second, and third directions, respectively, which are orthogonal to each other. Note that in this embodiment, the directions are described based on the orientation in which the parallel direction of the nozzle 1141 and pressure chamber 1131 of the liquid discharge head 1 is along the X axis, the extension direction of the pressure chamber 1131 is along the Y axis, and the liquid discharge direction is along the Z axis, but the description of directions is not limited to this.

[0010] The liquid ejection head 1 is a shear-mode inkjet head provided in a liquid ejection device 2, such as the inkjet recording device shown in Figure 10. The liquid ejection head 1 has an independent drive structure, for example, that alternately includes a pressure chamber 1131 and an air chamber 1132. The liquid ejection head 1 is provided in a head unit 2130, which includes a supply tank 2132 as a liquid storage section provided in the liquid ejection device 2.

[0011] The liquid ejection head 1 is supplied with ink as liquid stored in the supply tank 2132. The liquid ejection head 1 may be a non-circulating head that does not circulate ink, or it may be a circulating head that circulates ink. In this embodiment, the liquid ejection head 1 will be described using an example of a non-circulating head. The liquid ejection head 1 is also connected to a cooling device 2116 provided in the liquid ejection device 2, and is supplied with a cooling liquid (cooling water) to control the temperature of the ink.

[0012] As shown in Figures 1 to 4, the liquid discharge head 1 comprises a head body 11, a manifold unit 12, a cooling channel unit 13, a circuit board 14, and a cover 15. For example, the liquid discharge head 1 is a side-chute type four-row integrated head having two sets of head bodies 11, each having a pair of actuators 113.

[0013] The head body 11 discharges liquid. As shown in Figures 3 to 9, the head body 11 comprises a substrate 111, a frame 112, an actuator 113 having a plurality of pressure chambers 1131 and a plurality of air chambers 1132, and a nozzle plate 114.

[0014] The head body 11 has a common liquid chamber 116 that communicates with multiple pressure chambers 1131 of the actuator 113. The primary side of the multiple pressure chambers 1131 is the upstream side of the multiple pressure chambers 1131 in the direction of liquid flow. The secondary side of the multiple pressure chambers 1131 is the downstream side of the multiple pressure chambers 1131 in the direction of liquid flow.

[0015] Furthermore, the head body 11 has a substrate 111 and an actuator 113, each having a plurality of individual electrodes 118 that drive a plurality of pressure chambers 1131 of the actuator 113, and one or more common electrodes 119 that drive the plurality of pressure chambers 1131 simultaneously.

[0016] In the example of this embodiment, an example in which the head 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 will be described. The common liquid chamber 116 has, for example, a first common liquid chamber 1161 that communicates with the primary-side openings (the inlets of the pressure chambers 1131) of a plurality of pressure chambers 1131 of the actuator 113, and a second common liquid chamber 1162 that communicates with the secondary-side openings (the outlets of the pressure chambers 1131) of the plurality of pressure chambers 1131 of the actuator 113.

[0017] The substrate 111 is formed in a rectangular plate shape from a ceramic material such as alumina, for example. The substrate 111 has a surface 115 which is one main surface constituting the polished surface, and a back surface 117 which is the other main surface. The substrate 111 is formed in a rectangular shape that is long in one direction (X direction), for example. On the surface 115 which is one main surface of the substrate 111 and constitutes the polished surface, a third electrode portion 1183 which is part of a plurality of individual electrodes 118 and a third electrode portion 1193 which is part of a single common electrode 119 are formed. On the surface 115 of the substrate 111, a pair of actuators 113 are provided side by side in 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 both main surfaces of the substrate 111. The supply port 1111 is an opening through which ink passes and is formed in the substrate 111.

[0018] Also, on an end face 1114 in the longitudinal direction of the substrate 111, a fifth electrode portion 1195 which is part of a single common electrode 119 is formed. The end face 1114 extends in the thickness direction (Z direction) of the substrate 111 and forms a side surface portion that is continuous with the surface 115 which is one main surface of the substrate 111 and the back surface 117 which is the other main surface.

[0019] 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 in the short side direction of the substrate 111. The supply port 1111 extends along the longitudinal direction of the substrate 111. In other words, the supply port 1111 is, for example, a long hole that is long in one direction along the longitudinal direction of the actuator 113 and the longitudinal direction of the first common liquid chamber 1161. The supply port 1111 is provided between the pair of actuators 113 and opens at a position facing the first common liquid chamber 1161.

[0020] A fourth electrode portion 1194 that forms part of the common electrode 119 is formed on the inner wall surface of the supply port 1111.

[0021] The discharge port 1112 is an outlet for discharging ink. A plurality of discharge ports 1112, for example, four discharge ports, are provided. Each discharge port 1112 is, for example, between the first common liquid chamber 1161 and each second common liquid chamber 1162 and adjacent to each of the longitudinal ends of the pair of actuators 113. Note that the plurality of discharge ports 1112 may be provided in the second common liquid chamber 1162. An eighth electrode portion 1198 that forms part of the common electrode 119 is formed on the inner wall surface of the discharge port 1112.

[0022] The through-hole 1113 is a through-hole formed at both longitudinal ends of the substrate 111 and outside the discharge port 1112. The through-hole 1113 is provided outside the frame 112 and opens at a position where the first common liquid chamber 1161 and the second common liquid chamber 1162 do not face each other and do not come into contact with the ink. A seventh electrode portion 1197 that forms part of the common electrode 119 is formed on the inner wall surface of the through-hole 1113.

[0023] The actuator 113 and the frame 112 are provided on the substrate 111. The inside of the frame 112 on the substrate 111 becomes a liquid contact region where ink is disposed, and the outside of the frame 112 becomes a mounting region where various electronic components can be connected.

[0024] The frame 112 is fixed to one main surface of the substrate 111 with adhesive or the like. The frame 112 surrounds the supply port 1111, the multiple discharge ports 1112, and the actuator 113 provided on the substrate 111.

[0025] For example, the frame 112 is formed in a rectangular frame shape, thereby forming a long opening in one direction along the longitudinal direction of the frame 112. The frame 112 may have a stepped structure in which part of its surface is 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 substrate 111, and to be able to hold liquid inside.

[0026] 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, with the supply port 111 in between. The actuators 113 are formed in a plate shape that is long in one direction. The actuators 113 are placed in the opening of the frame 112 and bonded to the surface 115 of the substrate 111.

[0027] As shown in Figures 5 to 9, the actuator 113 has a plurality of pressure chambers 1131 arranged at equal intervals in the longitudinal direction on the longitudinal center side, and air chambers 1132 arranged at equal intervals in the longitudinal direction and between adjacent pressure chambers 1131. In other words, the actuator 113 has a plurality of pressure chambers 1131 and air chambers 1132 arranged alternately along the longitudinal direction. The plurality of pressure chambers 1131 and air chambers 1132 extend in a direction intersecting the direction of arrangement, for example, in the short direction of the actuator 113.

[0028] The top surface of the actuator 113, which is the side opposite to the substrate 111, is bonded to the nozzle plate 114. The actuators 113 are arranged at equal intervals in the longitudinal direction, and multiple grooves are formed along a direction perpendicular to the longitudinal direction. The multiple grooves form multiple pressure chambers 1131 and multiple air chambers 1132. In other words, the actuator 113 has multiple piezoelectric elements 1133, which are driving elements that form walls that form grooves, arranged at equal intervals in the longitudinal direction. The multiple piezoelectric elements 1133 form multiple pressure chambers 1131 and multiple air chambers 1132 between adjacent piezoelectric elements 1133, and the volume of the pressure chambers 1131 is changed when a driving voltage is applied.

[0029] The actuator 113 has a width in the shorter direction that gradually increases from the top side toward the substrate 111 side. The cross-sectional shape of the actuator 113 along the direction perpendicular to the longitudinal direction (shorter direction) is formed as a trapezoid. That is, the actuator 113 has an inclined surface 1134 that slopes toward the side surface in the shorter direction. The side surface (inclined surface 1134) is positioned opposite the first common liquid chamber 1161 and the second common liquid chamber 1162. The inclined surface 1134 has a second electrode portion 1182 that becomes part of a plurality of individual electrodes 118, and a second electrode portion 1192 that becomes part of one or more common electrodes 119.

[0030] As a specific example, the actuator 113 is formed from a laminated piezoelectric member, which consists of two rectangular plates of piezoelectric material, each long in one direction, bonded together facing each other so that their polarization directions are opposite. Here, the piezoelectric material is, for example, PZT (lead zirconate titanate). The actuator 113 is bonded to the surface 115 of the substrate 111 with, for example, a thermosetting epoxy adhesive. The actuator 113 then forms an inclined surface 1134, for example, by machining. In addition, the substrate 111 and the actuator 113 are polished, for example, by polishing, so that the surface 115 on which the multiple individual electrodes 118 and common electrode 119 are patterned is polished and a polished surface is formed. Furthermore, the actuator 113 is formed by, for example, machining to create multiple grooves that form multiple pressure chambers 1131 and multiple air chambers 1132, and piezoelectric elements (driving elements) 1133 that serve as side walls separating adjacent grooves are formed.

[0031] Furthermore, the actuator 113 is formed with a first electrode portion 1181 and a second electrode portion 1182 which are part of a plurality of individual electrodes 118, and a first electrode portion 1191 and a second electrode portion 1192 which are part of one or more common electrodes 119.

[0032] The pressure chamber 1131 deforms during printing or other operations by the liquid ejection head 1, thereby ejecting ink from the nozzle 1141. The pressure chamber 1131 has an inlet that opens into the first common liquid chamber 1161 and an outlet that opens into the second common liquid chamber 1162. Ink flows into the pressure chamber 1131 from the inlet and flows out from the outlet. The pressure chamber 1131 may also be configured so that ink flows in from both openings described as the inlet and outlet. Within the grooves constituting the pressure chamber 1131, first electrode portions 1181, which become part of a plurality of individual electrodes 118, are formed.

[0033] As shown in Figure 9, the air chamber 1132 is separated from the first common liquid chamber 1161 and the second common liquid chamber 1162 by sealing its inlet and outlet sides with liquid-proof walls 1135 made of photosensitive resin or the like. Specifically, the liquid-proof walls 1135 of the air chamber 1132 are formed by injecting ultraviolet-curable resin into the groove forming the air chamber 1132, and then irradiating the necessary parts, for example, both ends (inlet and outlet sides of the groove) with ultraviolet light using an exposure mask or the like. Such liquid-proof walls 1135 prevent ink from entering the air chamber 1132. Furthermore, the air chamber 1132 is sealed by the nozzle plate 114, and no nozzle 1141 is placed inside it. Therefore, ink does not flow into the air chamber 1132. A first electrode portion 1191, which becomes part of one or more common electrodes 119, is formed inside the air chamber 1132.

[0034] The nozzle plate 114 is formed in a plate shape. The nozzle plate 114 is fixed to the main surface of the frame 112 opposite to the substrate 111 with an adhesive or the like. The nozzle plate 114 has a plurality of nozzles 1141 formed at positions opposite to a plurality of pressure chambers 1131. In this embodiment, the nozzle plate 114 has two rows of nozzle rows 1142 in which the plurality of nozzles 1141 are arranged in one direction.

[0035] The first common liquid chamber 1161 is formed between the central sides of a pair of actuators 113, excluding both ends, and constitutes the flow path for ink from the supply port 1111 to the primary side openings (inlets) of the multiple pressure chambers 1131 of each actuator 113. The first common liquid chamber 1161 extends along the longitudinal direction of the actuators 113.

[0036] The second common liquid chamber 1162 is formed between each actuator 113 and the frame 112. The second common liquid chamber 1162 forms the flow path for ink from the secondary openings (outlets) of the multiple pressure chambers 1131 to the discharge port 1112. The second common liquid chamber 1162 extends along the longitudinal direction of the actuator 113.

[0037] Multiple individual electrodes 118 apply individual drive voltages to multiple piezoelectric elements 1133, which are piezoelectric materials. Multiple individual electrodes 118 individually deform each pressure chamber 1131. The individual electrodes 118 are formed by wiring patterns formed on the substrate 111 and wiring patterns formed on the actuator 113. The individual electrodes 118 are drawn out from either the pressure chamber 1131 or the air chamber 1132 to one side in the extension direction. In this embodiment, they are drawn out from the pressure chamber 1131 to the area outside the pair of actuators 113.

[0038] As a specific example, as shown in Figures 7 to 9, multiple individual electrodes 118 are formed on the inner surface of each pressure chamber 1131, the inclined surface 1134 of the actuator 113, and on the substrate 111. Specifically, the individual electrodes 118 are formed on the side surface of the piezoelectric body 1133 that forms the pressure chamber 1131, and on a part of the piezoelectric member that constitutes the bottom of the pressure chamber 1131. In addition, the individual electrodes 118 are formed, for example, on the inclined surface 1134 and the surface 115 of the substrate 111. The individual electrodes 118 extend from inside the pressure chamber 1131 to the short-side end of the substrate 111, and their ends are positioned at the connection portion 1116 to which the circuit board 14 of the substrate 111 is connected. Specifically, each individual electrode 118 has a first electrode portion 1181 formed in a groove constituting the pressure chamber 1131 of the actuator 113, a second electrode portion 1182 formed on the inclined surface 1134 of the actuator 113, and a third electrode portion 1183 formed on the surface 115 of the substrate 111. The individual electrode 118 is provided so as 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 electrode 118 is formed of, for example, a nickel thin film. However, the individual electrode 118 is not limited to a nickel thin film; it may also be formed of, for example, a gold or copper thin film. The thickness of the individual electrode 118 is, for example, 0.5 μm to 5 μm.

[0039] The common electrode 119 applies the same driving voltage to all of the piezoelectric elements 1133. The common electrode 119 deforms the multiple pressure chambers 1131 simultaneously. The common electrode 119 is formed by a wiring pattern formed on the substrate 111 and a wiring pattern formed on the actuator 113. The common electrode 119 is a wiring pattern provided from the inner circumferential surface of the supply port 1111 of the substrate 111 across the piezoelectric elements 1133 that form the multiple air chambers 1132. The common electrode 119 is connected to the circuit board 14. The common electrode 119 is drawn out from either the pressure chamber 1131 or the air chamber 1132 to the other side in the extending direction. In this embodiment, the common electrode 119 is drawn out from the air chamber 1132 to the region between the pair of actuators 113. That is, the electrodes of the multiple air chambers 1132 are bundled together on the central side of the substrate to form the common electrode 119.

[0040] As a specific example, as shown in Figures 7 to 9, the common electrode 119 is formed on the inner surface of each air chamber 1132, the inclined surface 1134 of the actuator 113, and in areas on the substrate 111 that avoid the individual electrodes 118. That is, the common electrode 119 is formed on the side surface of the piezoelectric body 1133 that forms each air chamber 1132, and on a part of the piezoelectric member that constitutes the bottom of the air chamber 1132. In addition, the common electrode 119 is provided on the inclined surface 1134 extending from inside each air chamber 1132 toward the center of the substrate 111, and is also formed on the surface 115 of the substrate 111 between the pair of actuators 113 and on the inner circumferential surface of the supply port 1111. Furthermore, the common electrode 119 extends to the longitudinal end of the substrate 111 and is also formed on the longitudinal (Y-direction) end face 1114 of the substrate 111, and on the back surface 117, which is the main surface opposite to the surface 115 of the substrate 111. For example, the common electrode 119 extends to the short-side end of the substrate 111, and its end is positioned at the connection portion 1116 to which the circuit board 14 of the substrate 111 is connected.

[0041] In other words, the common electrode 119 is provided on the short-side central side of the substrate 111, between the connection portion 1116 formed at the short-side end of the substrate 111 and the pair of actuators 113. A portion of the common electrode 119 provided on the short-side central side of the substrate 111 is provided on the inner circumferential surface of the supply port 1111 on the short-side central side of the substrate 111, extending in the thickness direction of the substrate 111, as shown in Figure 7. Another portion of the common electrode 119 is provided on the surface of the piezoelectric members forming each air chamber 1132 from the short-side central side of the substrate 111. Furthermore, a portion of the common electrode 119 is provided on the longitudinal end face 1114 and the back surface 117 of the substrate 111.

[0042] In other words, 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 circumferential surface of the supply port 1111, a fifth electrode portion 1195 formed on the longitudinal end face 1114 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 circumferential surface of the through hole 1113, and an eighth electrode portion 1198 formed on the inner circumferential surface of the discharge port 1112. Each electrode portion 1191 to 1198 of the common electrode 119 is formed to avoid the individual electrodes 118 and other mounted components. Each electrode portion 1191 to 1198 of the common electrode 119 may be partially formed on the surface of the substrate 111 or the actuator 113.

[0043] In the common electrode 119, the third electrode portion 1193 on the front 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.

[0044] The common electrode 119 is provided so as to be in close contact with the bottom of the air chamber 1132 and the surface of the piezoelectric member forming the piezoelectric body 1133. The common electrode 119 is formed of, for example, a thin nickel film. However, the common electrode 119 is not limited to a thin nickel film; it may also be formed of, for example, a thin gold or copper film. The thickness of the common electrode 119 is, for example, 0.5 μm to 5 μm.

[0045] For example, the individual electrodes 118 and the common electrode 119 are covered by a coating layer 120 inside the frame 112. Alternatively, the individual electrodes 118 may be covered on the lower surface of the frame 112 with an adhesive used to bond the frame 112 to the substrate 111.

[0046] The coating layer 120 is formed on the surface of the actuator 113 and the surface 115 of the substrate 111 within the region of the frame 112. The coating layer 120 covers the surface 115 of the substrate 111, including the region where at least a portion of the individual electrodes 118 and the common electrode 119 are formed. The coating layer 120 is a film formed, for example, by a spray method, and is composed of, for example, a thermosetting epoxy adhesive. For example, the thickness of the coating layer 120 is 5 to 30 μm. The coating layer 120 covers the inclined surface 1134 of the actuator 113 and a portion of the surface 115 of the substrate 111. As an example, the coating layer 120 is formed on the surface 115 of the substrate 111 in a region surrounded by the frame 112. For example, the coating layer 120 is formed in the region on the inner circumference side of the frame 112 and in the region directly below the frame 112. In other words, the coating layer 120 is not formed on the mounting region outside the frame 112 or on the back surface 117 of the surface 115.

[0047] The coating layer 120 is formed, for example, by installing the actuator 113 on the substrate 111 to form electrodes, and then applying the coating agent by spraying.

[0048] As shown in Figures 1, 4, and 5, the manifold unit 12 comprises a manifold 121, a top plate 122, an ink supply pipe 123, an ink discharge pipe 124, and a pair of temperature control pipes, a cooling water supply pipe 125 and a cooling water discharge pipe 126. The number of ink supply pipes 123, ink discharge pipes 124, cooling water supply pipes 125 and cooling water discharge pipes 126 can be set as appropriate.

[0049] The manifold 121 is formed in the shape of a plate or a block. As shown in Figure 5, the manifold 121 includes a supply channel 1211 that is continuous with the supply port 1111 of the substrate 111 and forms a liquid supply channel, a discharge channel that is continuous with the discharge port 1112 of the substrate 111 and forms a liquid discharge channel, and a first cooling channel 1213 that forms a channel for cooling fluid. Since the manifold 121 is connected to a pair of head bodies 11, it has a pair of supply channels 1211 and a pair of discharge channels.

[0050] The manifold 121 is formed, for example, by assembling multiple manifold members together, and forms a supply channel 1211, a discharge channel, and a first cooling channel 1213.

[0051] One main surface of the manifold 121 is fixed to the back surface 117, which is the other main surface of the substrate 111. The top plate 122 is fixed to the main surface of the manifold 121 opposite to the main surface to which the substrate 111 is fixed. Furthermore, for example, 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.

[0052] The supply channel 1211 is a channel formed in the manifold 121 by holes or grooves. The supply channel 1211 fluidly connects the ink supply pipe 123 and the supply port 1111 of the substrate 111.

[0053] The discharge channel is a channel formed in the manifold 121 by holes or grooves. The discharge channel fluidly connects the ink discharge pipe 124 and the discharge port 1112 of the substrate 111.

[0054] The first cooling channel 1213 is a channel formed in the manifold 121 by holes or grooves. The first cooling channel 1213 fluidly connects the cooling water supply pipe 125 and the cooling water discharge pipe 126.

[0055] Both ends of the first cooling channel 1213 are openings that connect to a cooling water supply pipe 125 and a cooling water discharge pipe 126, which are provided on one main surface of the manifold 121. The first cooling channel 1213 is also formed to allow heat exchange with the substrate 111, which is fixed to the manifold 121.

[0056] The top plate 122 is provided on the side of the manifold 121 opposite to the side on which the substrate 111 is provided. By covering the manifold 121, the top plate 122 seals the supply channel 1211, the discharge channel, and the first cooling channel 1213.

[0057] Furthermore, the top plate 122 has openings for connecting the pipes 123, 124, and 125, and for connecting the pipes 123, 124, and 125 and the flow paths 1211 and 1213.

[0058] The ink supply pipe 123 is connected to the supply channel 1211. The ink discharge pipe 124 is connected to the discharge channel. 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 channel 1213.

[0059] In this embodiment, a pair of ink supply pipes 123 and a first cooling water discharge pipe 126 are arranged on one end of the manifold 121 in the longitudinal direction, and a pair of ink discharge pipes 124 and a first cooling water supply pipe 125 are arranged on the other end of the manifold 121 in the longitudinal direction.

[0060] The cooling channel unit 13 has a plurality of second cooling channels 1312, a second cooling water supply pipe 133, and a second cooling water discharge pipe 134. In the cooling channel unit 13, a plurality of openings 1314 are formed between the plurality of second cooling channels 1312. The cooling channel unit 13 is connected to the cooling device 2116 of the liquid discharge device 2. The second cooling channels 1312 are long in one direction (first direction X) and are arranged in a direction perpendicular to the longitudinal direction of the second cooling channels 1312 (second direction Y).

[0061] As a specific example, in this embodiment, there are four rows of nozzles 1142, four actuators 113 (four rows), and four driver ICs 142 (four rows). Therefore, the cooling flow channel unit 13 has three second cooling flow channels 1312, and two openings 1314 are formed between the second cooling flow channels 1312.

[0062] Multiple second cooling channels 1312 are connected to a second cooling water supply pipe 133 and a second cooling water discharge pipe 134.

[0063] The cooling channel unit 13 has multiple openings 1314 through which a portion of the driver IC 142 (described later) on the circuit board 14 and the printed wiring board 143 are placed, and multiple second cooling channels 1312 are positioned opposite the driver IC 142, which is a heat-generating element, thereby cooling the driver IC 142.

[0064] As shown in Figure 4, the circuit board 14 includes a driver IC 142, one end of which is connected to a connection portion 1116 of the board 111, and a printed wiring board 143.

[0065] The circuit board 14 drives the actuator 113 by applying a drive 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 and ejecting droplets from the nozzle 1141.

[0066] 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 thermocompression or the like. Alternatively, the driver IC 142 may be connected to the plurality of individual electrodes 118 and the common electrode 119 by other means such as ACP (anisotropic conductive paste), NCF (nonconductive film), and NCP (nonconductive paste). Multiple driver ICs 142 are provided for a single head body 11, for example. In this embodiment, two driver ICs 142 are connected to a single actuator 113. The driver IC 142 is, for example, a COF (Chip on Film) on which a driver IC chip is mounted.

[0067] The surface of the driver IC 142 is in contact with the outer surface of the second cooling channel 1312.

[0068] The printed wiring board 143 is a Printing Wiring Assembly (PWA) on which various electronic components and connectors are mounted.

[0069] The cover 15 includes, for example, an outer casing 151 that covers the sides of the pair of head bodies 11, the manifold unit 12 and the circuit board 14, and a mask plate 152 that covers a portion of the nozzle plate 114 side of the pair of head bodies 11.

[0070] The outer casing 151 exposes, for example, the ink supply pipe 123, ink discharge pipe 124, cooling water supply pipe 125, and cooling water discharge pipe 126 of the manifold unit 12, as well as the end of the circuit board 14, to the outside.

[0071] The mask plate 152 covers the portion of the pair of head bodies 11 excluding the multiple nozzles 1141 and the area around the multiple nozzles 1141 of the nozzle plate 114.

[0072] The liquid discharge head 1 configured in this way has a head body 11 which includes a plurality of individual electrodes 118 that can individually apply a driving voltage to each piezoelectric element 1133, and a common electrode 119 that can apply a driving voltage to all piezoelectric elements 1133.

[0073] Therefore, the liquid ejection head 1 can selectively, individually, or collectively drive multiple pressure chambers 1131. When a pressure chamber 1131 is driven, it undergoes shear-mode deformation, and the ink supplied into the pressure chamber 1131 is pressurized. Thus, the liquid ejection head 1 can selectively eject the pressurized ink from the nozzle 1141 facing the pressure chamber 1131.

[0074] In addition, the common electrode 119 is formed not only on the surface 115 of the actuator 113 on the substrate 111, the inclined surface 1134 of the actuator 113, and the inner surface of the air chamber 1132, but also on the inner circumferential surface of the supply port 1111 formed on the substrate 111.

[0075] The inkjet recording device 2 having a liquid ejection head 1 will be described below with reference to Figure 10. The inkjet recording device 2 comprises a housing 2111, a media supply unit 2112, an image forming unit 2113, a media discharge unit 2114, a transport device 2115 which is a support device, a maintenance device 2117, and a control unit 2118. The inkjet recording device 2 also includes a cooling device that adjusts the temperature of the ink supplied to the liquid ejection head 1.

[0076] The inkjet recording device 2 is an inkjet printer that performs image formation processing on paper P by transporting paper P, for example, 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 ejection unit 2114, while ejecting a liquid such as ink.

[0077] The media supply unit 2112 includes a plurality of paper feed cassettes 21121. The image forming unit 2113 includes a support unit 2120 for supporting paper and a plurality of head units 2130 positioned opposite each other above the support unit 2120. The media discharge unit 2114 includes a paper output tray 21141.

[0078] The support unit 2120 includes a conveyor belt 21201 provided in a loop shape in a predetermined area where image formation is performed, a support plate 21202 that supports the conveyor belt 21201 from the back, and a plurality of belt rollers 21203 provided on the back of the conveyor belt 21201.

[0079] The head unit 2130 comprises a liquid ejection head 1 which is a plurality of inkjet heads, a plurality of supply tanks 2132 which are liquid tanks mounted on each liquid ejection head 1, a pump 2134 which supplies ink, and a connecting channel 2135 which connects the liquid ejection head 1 and the supply tanks 2132.

[0080] In this embodiment, the liquid ejection head 1 comprises four liquid ejection heads 1 for cyan, magenta, yellow, and black, and four supply tanks 2132 each containing ink of one of these colors. The supply tanks 2132 are connected to the liquid ejection head 1 by a connecting channel 2135.

[0081] Pump 2134 is a liquid transfer pump, for example, a piezoelectric pump. Pump 2134 is connected to the control unit 2118 and is driven and controlled by the control unit 2118.

[0082] The connecting channel 2135 includes a supply channel connected to the ink supply pipe 123 of the liquid ejection head 1. The connecting channel 2135 also includes a recovery channel connected to the ink discharge pipe 124 of the liquid ejection head 1. For example, if the liquid ejection head 1 is a non-circulating type, the recovery circuit is connected to the maintenance device 2117, and if the liquid ejection head 1 is a circulating type, the recovery channel is connected to the supply tank 2132.

[0083] The transport device 2115 transports the paper P along a transport path 2001 from the paper feed cassette 21121 of the media supply unit 2112, through the image forming unit 2113, to the paper output tray 21141 of the media discharge unit 2114. The transport device 2115 comprises a plurality of guide plate pairs 21211 to 21218 and a plurality of transport rollers 21221 to 21228 arranged along the transport path 2001. The transport device 2115 supports the paper P so that it can move relative to the liquid discharge head 1.

[0084] The cooling system 2116 includes a cooling water tank 21161, a cooling circuit 21162 such as piping and tubes for supplying cooling water, a pump for supplying cooling water, and a cooler for adjusting the temperature of the cooling water. The cooling system 2116 supplies the 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 using water supplied by the pump. The cooling system 2116 also recovers the water discharged from the second cooling water discharge pipe 134 through the first cooling passage 1213 and the second cooling passage 1312 into the cooling water tank 21161 via the cooling circuit 21162. The cooler is, for example, a cooler.

[0085] The maintenance device 2117, for example, sucks up and recovers ink remaining on the outer surface of the nozzle plate 114 during maintenance. Furthermore, if the liquid discharge head 1 is a non-circulating type, the maintenance device 2117 recovers ink from within the head body 11 during maintenance. Such a maintenance device 2117 includes a tray or tank for storing the recovered ink.

[0086] The control unit 2118 includes a CPU 21181 as 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.

[0087] With the liquid ejection head 1 and inkjet recording device 2 configured in this way, a common electrode 119 is also formed on the end face 1114 of the substrate 111, thus ensuring high print quality. Specifically, in the liquid ejection head 1, the electrode portions 1193 and 1196 on the front surface 115 and back surface 117 sides of the substrate 111 are connected by the electrode portion 1195 on the end face 1114. Therefore, even if the electrodes are partially dissolved by the ink when using ink containing components that dissolve electrodes, the area of ​​the common electrode 119 can be secured. For example, if a coating layer 120 is not formed on the back surface 117 of the substrate 111, even if a part of the common electrode 119 on the back surface 117 of the substrate 111 disappears around the supply port 1111, the connection between the common electrode 119 on the front surface 115 and the back surface 117 is secured by the electrode portion 1195 formed on the end face 1114 located outside the area where the ink is distributed, thereby suppressing an increase in the resistance of the common electrode 119. Therefore, when dispensing liquid, it is possible to suppress differences in the drive waveform between the ends and the center of the row, thereby maintaining good print quality such as dot diameter and linearity.

[0088] Furthermore, by providing a common electrode 119 on the inner circumferential surface of the supply port 1111 in the liquid discharge head 1, the electrode surface area of ​​the common electrode 119 can be secured, and the resistance of the common electrode 119 can be reduced. Therefore, even if the spacing between the rows of piezoelectric elements 1133 of the actuator 113 becomes narrow, it is possible to suppress differences in discharge performance between the central side and the end side in the direction of the arrangement of the nozzles 1141 of the head body 11.

[0089] Furthermore, in the above embodiment, a common electrode 119 is also provided in a through-hole 1113 formed on the outside of the frame 112 in a part that does not come into contact with the ink. This ensures that the connection between the common electrode 119 on the surface 115 and the back surface 117 is secured via the through-hole 1113, thereby reducing the resistance of the common electrode 119.

[0090] It should be noted that the embodiments of the present invention are not limited to the configuration described above. Several examples of embodiments are shown below. In the embodiments described below, components similar to those in the first embodiment described above are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0091] For example, in the above example, a supply port 1111, which is an elongated hole, is arranged between a pair of actuators 113, discharge ports 1112 are arranged at both ends in the longitudinal direction of the pair of actuators 113, and a through-hole 1113 is arranged at the outer end. However, the example is not limited to this, and the shape, number, and arrangement of the supply port 1111, discharge port 1112, and through-hole 1113 can be set as appropriate. For example, a configuration in which a common electrode 119 is not formed on the inner circumferential surface of the discharge port 1112 is possible. Alternatively, a configuration without a through-hole 1113 is possible. Even in such configurations, the connection state of the common electrode 119 can be maintained by forming an electrode on the end face 1114.

[0092] For example, in the example described above, an example was shown in which individual electrodes 118 are formed in the pressure chamber 1131 and a common electrode 119 is formed in the air chamber 1132, but this is not the only example. For example, a configuration in which a common electrode 119 is formed in the pressure chamber 1131 and individual electrodes 118 are formed in the air chamber 1132 may also be used.

[0093] For example, in the above example, the liquid discharge head 1 was described as having a pair of head bodies 11, but it is not limited to this configuration, and may have a single head body 11. Also, the head body 11 was described as having a pair of actuators 113, but it is not limited to this configuration. For example, the head body 11 may have a single actuator 113.

[0094] Furthermore, the pressure chamber 1131 may be configured to include throttling at its inlet and outlet. For example, in another embodiment of the liquid discharge head, the pressure chamber 1131 may have throttling sections formed at its inlet opening to the first common liquid chamber 1161 and its outlet opening to the second common liquid chamber 1162, which reduce the size of the openings and narrow the flow path. The throttling sections are, for example, projections or wall-like members formed from ultraviolet-curing resin that block a portion of the inlet and outlet, thereby increasing the flow resistance at the inlet and outlet of the pressure chamber 1131.

[0095] Furthermore, although the example described above illustrates a non-circulating liquid discharge head 1, a circulating type is also acceptable.

[0096] Furthermore, in the above embodiment, as an example, an inkjet head is described in which 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. However, the invention is not limited to this. For example, the common chambers on both sides of the pressure chamber 1131 may be the supply side, and ink may flow in from both sides. Alternatively, the supply side and the discharge side may be reversed, or they may be configured to be switchable.

[0097] Furthermore, although a side-shooter type inkjet head was used as an example in the above embodiment, the invention is not limited to this, and an end-shooter type may also be used.

[0098] Furthermore, the liquid to be dispensed is not limited to printing ink; for example, it could be a device that dispenses a liquid containing conductive particles for forming wiring patterns on a printed circuit board.

[0099] Furthermore, while the above embodiment shows an example of the inkjet head being used in a liquid ejection device such as an inkjet printer, it is not limited to this, and can also be used in 3D printers, industrial manufacturing machinery, and medical applications, enabling miniaturization, weight reduction, and cost reduction.

[0100] According to at least one embodiment described above, since a common electrode is formed on the edge face of the substrate, high print quality can be ensured.

[0101] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0102] 1...Liquid ejection head (inkjet head), 2...Liquid ejection device (inkjet recording device), 11...Head body, 12...Manifold unit, 13...Cooling channel unit, 14...Circuit board, 15...Cover, 111...Substrate, 112...Frame, 113...Actuator, 114...Nozzle plate, 115...Front surface, 116...Common liquid chamber, 117...Back surface, 118...Individual electrodes, 1181...First electrode section, 1182...Second electrode section, 1183...Third electrode section, 119...Common electrode, 1191...First electrode Part, 1192...Second electrode part, 1193...Third electrode part, 1194...Fourth electrode part, 1195...Fifth electrode part, 1196...Sixth electrode part, 1197...Seventh electrode part, 1198...Eighth electrode part, 121...Manifold, 1213...First cooling channel, 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...Outlet, 152...Mask plate, 1111...Supply port, 1112...Discharge port, 1 113...Through-hole, 1114...End face, 1116...Connection part, 1131...Pressure chamber, 1132...Air chamber, 1133...Piezoelectric element (driving element), 1134...Inclined surface, 1135...Liquid-proof wall, 1141...Nozzle, 1142...Nozzle row, 1161...First common liquid chamber, 1162...Second common liquid chamber, 1211...Supply channel, 1312...Second cooling channel, 133...Second cooling water supply pipe, 134...Second cooling water discharge pipe, 2001...Conveyor path, 2111...Housing, 2112...Media supply section, 2113...Image forming section, 2114...Media Discharge unit, 2115...Conveyor device, 2116...Cooling device, 2117...Maintenance device, 2118...Control unit, 2120...Support unit, 2130...Head unit, 2132...Supply tank, 2134...Pump, 2135...Connecting channel, 21121...Paper feed cassette, 21141...Paper output tray, 21181...CPU, 21201...Conveyor belt, 21202...Support plate, 21203...Belt roller, 21211~21218...Guide plate pair, 21221~21228...Conveyor roller, P...Paper.

Claims

1. A substrate in which an opening for liquid to pass through is formed, An actuator provided on one main surface of the substrate, having a plurality of pressure chambers and a plurality of air chambers formed between the plurality of pressure chambers, A manifold is located on the other side of the aforementioned substrate, A common electrode having 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, Individual electrodes having electrode portions formed on the surface of the actuator and the main surface of one side of the substrate, A coating layer covering at least a portion of the main surface on one side of the substrate, A liquid dispensing head equipped with a liquid dispensing head.

2. A frame is arranged around the actuator on one main surface of the substrate, A nozzle plate is positioned on one side of the frame and has a nozzle that communicates with the pressure chamber, Equipped with, The multiple pressure chambers and the multiple air chambers are arranged alternately in one direction and extend in directions intersecting the direction of arrangement. The liquid dispensing head according to claim 1, wherein the side surface of the substrate is the end face of the substrate in the one direction and is located outside the frame.

3. The opening is an elongated hole extending in one direction, penetrating the substrate and having an inner circumferential surface continuous with the main surface on one side and the main surface on the other side, and is a supply port for supplying liquid from the other side of the substrate to the one side of the substrate. The liquid discharge head according to claim 1, wherein the manifold forms a flow path communicating with the opening.

4. The substrate further comprises an outlet that penetrates the substrate, A through-hole is formed on the substrate at a position outside the frame of the substrate, The liquid discharge head according to claim 2, wherein 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 discharge port.

5. A pair of actuators is provided on the substrate. The supply port is provided in the region between the pair of actuators. The common electrode is drawn from the pair of actuators into the region between the pair of actuators. The liquid dispensing head according to claim 3, wherein the individual electrodes are drawn out from the pair of actuators to a region outside the pair of actuators.

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