JP2023109057A - Liquid discharge head and manufacturing method of the same - Google Patents

Abstract

To provide a liquid discharge head which can secure stable discharge characteristics, and to provide a manufacturing method of the liquid discharge head.SOLUTION: A liquid discharge head according to one embodiment is a share mode shared wall type and includes an actuator part and contraction parts. The actuator part is formed by a piezoelectric member and has a pressure chamber and an air chamber. The contraction parts are formed by piezoelectric members. The contraction parts are provided at an inlet and an outlet of the pressure chamber. The contraction part has contraction ports which communicate with the pressure chamber and increase fluid resistance of the pressure chamber.SELECTED DRAWING: Figure 5

Description

Embodiments of the present invention relate to a liquid ejection head and a method for manufacturing the liquid ejection head.

In recent years, there has been a demand for high productivity in inkjet heads, and increasing speed and increasing the amount of droplets have become issues. For example, a shared mode shared wall inkjet head has high power and is suitable for ejecting high-viscosity ink and ejecting large droplets. In the share mode share wall type ink jet head, the same driving column is shared by two pressure chambers, and 1/3 of the plurality of arranged chambers are commonly driven as pressure chambers at the same time, so-called three-cycle drive. . Also, an independent drive head has been developed in which both sides of the pressure chamber to be driven are used as dummy pressure chambers and two independent drive columns are used to drive one pressure chamber. For example, a structure has been developed in which a large number of grooves are formed in a piezoelectric body, the entrances and exits are closed every other one, the grooves in which the entrances and exits are not blocked are used as pressure chambers, and the closed grooves are used as air chambers, and are independently driven. ing.

In such an inkjet head, ink is replenished from the common liquid chamber to the pressure chamber after ink droplets are ejected. At this time, a phenomenon occurs in which the nozzle overshoots and the meniscus rises. The smaller the fluid resistance of the flow path from the common liquid chamber to the nozzles, the greater the overshoot. Unless the overshoot is suppressed, the meniscus cannot be discharged in a stable state. Therefore, in order to increase the speed of an inkjet head, it is required to quickly converge the swelling of the meniscus and ensure stable ejection characteristics.

JP-A-2008-94036

A problem to be solved by the present invention is to provide a liquid ejection head and a method for manufacturing the liquid ejection head that can ensure stable ejection characteristics.

A liquid ejection head according to one embodiment is of a share mode shared wall type, and includes an actuator section and a throttle section. The actuator section is composed of a piezoelectric member and has a pressure chamber and an air chamber. The throttle section is composed of a piezoelectric member. Throttles are provided at the inlet and outlet of the pressure chamber. The throttle portion has a throttle opening that communicates with the pressure chamber and increases the fluid resistance of the pressure chamber.

1 is a perspective view showing an inkjet head according to an embodiment; FIG. 1 is an exploded perspective view showing a configuration of part of an inkjet head according to an embodiment; FIG. FIG. 2 is an enlarged perspective view showing the configuration of a part of the inkjet head; Sectional drawing which expands and shows a structure of one part of the same inkjet head. Sectional drawing which expands and shows a structure of one part of the same inkjet head. Explanatory drawing of the manufacturing method of the same inkjet head. Explanatory drawing of the manufacturing method of the same inkjet head. FIG. 4 is an explanatory diagram of an inkjet head according to Test Example 1 and Test Example 2; 4 is a graph showing the ejection speed of the inkjet head according to Test Example 1. FIG. 9 is a graph showing the ejection speed of the inkjet head according to Test Example 2; 5 is a graph showing meniscus recovery characteristics of inkjet heads according to Test Examples 1 and 2; FIG. 4 is an explanatory diagram of an inkjet head of an end shooter according to Test Examples 1 and 3; 5 is a graph showing driving waveforms of inkjet heads according to Test Examples 1 and 3; 5 is a graph showing nozzle flow velocity vibrations of inkjet heads according to Test Examples 1 and 3. FIG. 5 is a graph showing ejection volumes of inkjet heads according to Test Examples 1 and 3. FIG. 5 is a graph showing meniscus recovery characteristics of inkjet heads according to Test Examples 1 and 3; 1 is a schematic diagram showing an inkjet printer according to an embodiment; FIG. FIG. 5 is an explanatory diagram of a method for manufacturing an inkjet head according to another embodiment; FIG. 5 is an explanatory diagram of a method for manufacturing an inkjet head according to another embodiment; FIG. 4 is an explanatory diagram of the method for manufacturing the inkjet head according to the embodiment; FIG. 4 is an explanatory diagram of the method for manufacturing the inkjet head according to the embodiment;

The configuration of an inkjet head 10, which is a liquid ejection head according to the first embodiment, will be described below with reference to FIGS. 1 to 5. FIG. FIG. 1 is a perspective view showing an inkjet head according to the first embodiment, and FIG. 2 is an exploded perspective view of part of the inkjet head. FIG. 3 is an enlarged perspective view showing a partial configuration of the inkjet head, and FIGS. 4 and 5 are enlarged sectional views showing a partial configuration of the inkjet head. 6 and 7 are explanatory diagrams of the manufacturing process of the inkjet head. In the drawing, X, Y, and Z indicate the first direction, second direction, and three directions orthogonal to each other, respectively. In the present embodiment, the orientation is such that the parallel direction of the nozzles 28 and the pressure chambers 31 of the inkjet head 10 is along the X axis, the extending direction of the pressure chambers 31 is along the Y axis, and the liquid ejection direction is along the Z axis. Although the description of the direction is described as a reference, it is not limited to this.

As shown in FIGS. 1 to 5, the inkjet head 10 is a so-called side shooter type shared mode shared wall inkjet head. The inkjet head 10 is a device for ejecting ink, and is mounted inside an inkjet printer, for example. For example, the inkjet head 10 is an independently driven inkjet head in which pressure chambers 31 and air chambers 32 are alternately arranged. The air chamber 32 is an air chamber to which ink is not supplied and does not have the nozzles 28 .

The inkjet head 10 has an actuator base 11 , a nozzle plate 12 and a frame 13 . The actuator base 11 is an example of a base material. An ink chamber 27 is formed inside the inkjet head 10 to which ink, which is an example of a liquid, is supplied.

Furthermore, the inkjet head 10 includes components such as a circuit board 17 that controls the inkjet head 10 and a manifold 18 that forms part of the path between the inkjet head 10 and the ink tank.

As shown in FIGS. 2 to 5, the actuator base 11 has a substrate 21 and a pair of actuators 22 .

The substrate 21 is formed in a rectangular plate shape from ceramics such as alumina. The substrate 21 has a flat mounting surface. A pair of actuators 22 are joined to the mounting surface of the substrate. A plurality of supply holes 25 and discharge holes 26 are formed in the substrate 21 .

As shown in FIGS. 2 and 3, pattern wiring 211 is formed on the substrate 21 of the actuator base 11 . The pattern wiring 211 is formed of, for example, a nickel thin film. The pattern wiring 211 has a common pattern or an individual pattern, and is configured in a predetermined pattern shape to be connected to the electrode layer 34 formed on the actuator 22 .

The supply holes 25 are arranged in the longitudinal direction of the actuators 22 between the pair of actuators 22 in the central portion of the substrate 21 . The supply hole 25 communicates with the ink supply portion of the manifold 18 . The supply hole 25 is connected to an ink tank via an ink supply section. The supply hole 25 supplies the ink in the ink tank to the ink chamber 27 .

The discharge holes 26 are arranged in two rows with the supply hole 25 and the pair of actuators 22 interposed therebetween. The discharge hole 26 communicates with the ink discharge portion of the manifold 18 . The discharge hole 26 is connected to the ink tank through the ink discharge portion. The discharge hole 26 discharges the ink in the ink chamber 27 to the ink tank. In addition, the discharge hole 26 may be configured to be opened during printing. Ink flows toward Alternatively, the discharge hole 26 may be configured to be opened only during maintenance and closed during printing, for example. In this case, a non-circulating system is used, and ink flows into each pressure chamber 31 from both sides.

A pair of actuators 22 are adhered to the mounting surface of the substrate 21 . A pair of actuators 22 are arranged in two rows on the substrate 21 with the supply hole 25 interposed therebetween.
Each actuator 22 includes an actuator member 201 (actuator section) provided in the center in the second direction, and a pair of diaphragm members 202 (diaphragm section) provided at both ends of the actuator member 201 in the second direction. .

Both the actuator member 201 and the diaphragm member 202 are composed of piezoelectric members. For example, the actuator member 201 and the throttle member 202 are composed of piezoelectric members each formed of two plate-shaped piezoelectric bodies formed of lead zirconate titanate (PZT), for example. The two piezoelectric bodies are bonded together so that their polarization directions are opposite to each other in the thickness direction. The actuator member 201 and the diaphragm member 202 may have different thickness ratios of the two laminated piezoelectric bodies.

As an example, the actuator member 201 has the same length in the first direction, which is the parallel direction of the pressure chambers 31, and the third direction, which is the stacking direction of the two piezoelectric bodies. The actuator members 201 are longer than the diaphragm members 202 in the second direction, which is the direction in which the pressure chambers 31 extend. Double or more.

The actuator 22 is adhered to the mounting surface of the substrate 21 with, for example, a thermosetting epoxy adhesive. As shown in FIG. 2, the actuators 22 are arranged in parallel in the ink chamber 27 corresponding to the nozzles 28 arranged in two rows. The actuator 22 divides the ink chamber 27 into a first common chamber 271 in which the supply hole 25 opens and two second common chambers 272 in which the discharge hole 26 opens.

The width of the actuator 22 in the lateral direction gradually increases from the top side toward the substrate side. The cross-sectional shape of the actuator 22 along the direction perpendicular to the longitudinal direction (transverse direction) is trapezoidal. The side portion 221 of the actuator 22 has inclined surfaces that are inclined with respect to the second direction and the third direction. The top of actuator 22 is glued to nozzle plate 12 .

The actuator 22 includes multiple pressure chambers 31 and multiple air chambers 32 formed in the actuator member 201 . That is, the actuator member 201 has a plurality of side wall portions 33 made of piezoelectric members, and grooves 2011 forming the pressure chambers 31 and the air chambers 32 between the side wall portions 33 . In other words, the side wall portion 33 is formed as a drive element between the grooves 2011 forming the pressure chamber 31 and the air chamber 32 .

The actuator 22 also includes a plurality of aperture openings 242 formed in the aperture member 202 . That is, the aperture member 202 has a plurality of side wall portions 241 made of piezoelectric members, and grooves 2021 forming aperture openings 242 between the side wall portions 241 . In other words, the side walls 241 are formed as drive elements between the grooves 2021 forming the apertures 242 .

As shown in FIGS. 1 to 5, the bottom surface of the groove 2021 and the main surface of the substrate 21 are connected by inclined side surfaces 221 . The pressure chambers 31 and the air chambers 32 are arranged alternately. The pressure chambers 31 and the air chambers 32 each extend in a direction intersecting the longitudinal direction of the actuator 22 and are arranged in parallel in a first direction (the X-axis in the figure) which is the longitudinal direction of the actuator 22 . In this embodiment, for example, the groove 2011 has a constant width in the X direction in the depth direction along the Z direction, and a rectangular cross section perpendicular to the Y direction, which is the extending direction. The depth dimensions of the grooves 2011 and 2021 may be different or the same.

The shape of the pressure chamber 31 and the shape of the air chamber 32 may be different. The side walls 33 and 241 are formed between the pressure chamber 31 and the air chamber 32 and deform in response to the drive signal to change the volume of the pressure chamber 31 .

Electrode layers 34 are provided on inner wall surfaces of the plurality of grooves 2011 and 2021 forming the pressure chamber 31 , the air chamber 32 , and the throttle port 242 of the actuator base 11 . The electrode layer 34 is formed of a conductive film such as a nickel thin film, for example. The electrode layer 34 extends from the inner surfaces of the grooves 2011 and 2021 onto the substrate 21 and is connected to the pattern wiring 211 . That is, the electrodes formed in the pressure chamber 31 and the air chamber 32 are connected to the electrodes formed in the throttle port 242 , and the throttle port 242 is driven in conjunction with the pressure chamber 31 and the air chamber 32 . For example, the electrode layer 34 is formed at least on the side surfaces of the side wall portion 33 , that is, on the side wall surfaces of the grooves 2011 and 2021 forming the pressure chamber 31 , the air chamber 32 and the throttle port 242 . The electrode layer 34 may be formed on the side and bottom surfaces of the grooves 2011 and 2021, for example.

The plurality of pressure chambers 31 communicate with the plurality of nozzles 28 of the nozzle plate 12 joined to the top. Both ends of the pressure chamber 31 in the second direction communicate with the ink chamber 27 . That is, one end opens to the first common chamber 271 of the ink chamber 27 and the other end opens to the second common chamber 272 of the ink chamber 27 . For example, the opening at one end of the pressure chamber 31 serves as an inlet through which ink flows in, and the opening at the other end serves as an outlet through which ink flows out. Alternatively, when ink flows in from both sides, the openings at both ends serve as ink inlets. A communication port of the pressure chamber 31 with the ink chamber 27 is formed with a throttle 240 having a throttle port 242 configured to have a higher fluid resistance than the inside of the pressure chamber 31 . As an example, in this embodiment, apertures 240 are formed at the openings at both ends of the pressure chamber 31 .

The diaphragm 240 is configured in a shape that narrows the opening of the pressure chamber 31 that communicates with the ink chamber 27 . As an example, the throttle 240 is formed of the throttle member 202 and communicates with the end portion of the pressure chamber 31 in the second direction. Configured. The groove width of the groove 2021 is smaller than the groove width of the groove 2011 in the X direction.

In other words, the groove 2011 that constitutes the pressure chamber 31 has throttle ports 242 that communicate the pressure chamber 31 with the first common chamber 271 and the second common chamber 272 at both ends in the second direction, which is the extending direction. be. The throttle opening 242 has a slit shape extending in the second direction (Y direction), which is the longitudinal direction of the pressure chamber 31 , and the third direction (Z direction), which is the depth direction of the pressure chamber 31 . The opening width in the first direction of the throttle port 242 is smaller than the width of the inside of the pressure chamber 31 in the first direction. That is, the throttles 240 that increase the flow path resistance are formed at the communication ports at both ends of the pressure chamber in the second direction. The depth dimension of the throttle opening 242 in the third direction, which is the depth direction, may be the same as or different from the dimension of the inside of the pressure chamber 31 in the third direction. As an example, the dimension of the throttle port 242 in the third direction is configured to be smaller than the dimension of the inside of the pressure chamber 31 in the third direction.

Note that if the fluid resistance of the throttle 240 is too large, the ink replenishment to the pressure chamber 31 after the ink droplets are ejected will be delayed, which will hinder the speedup. Also, the bulge of the meniscus varies depending on the ink viscosity, ejection volume, drive frequency, and the like. Therefore, the shape of the side wall portion 241 and the size and position of the throttle opening 242 of the throttle 240 are set so as to provide a flow path resistance corresponding to the ink replenishment conditions and the meniscus swelling characteristics. Note that the diaphragms 240 on both sides may have different configurations.

The air chamber 32 is closed on one side in the third direction by the nozzle plate 12 joined to the top. Further, both ends of the air chambers 32 in the second direction, for example, are closed by the cover portions 23 . That is, the cover portions 23 are arranged between the first common chamber 271 of the ink chamber 27 and the inlet of the air chamber 32 and between the outlet of the air chamber 32 and the second common chamber 272, respectively. is separated from the ink chamber 27 . Therefore, the air chamber 32 constitutes an air chamber into which ink does not flow.

For example, the cover portion 23 is formed by filling a groove 2021 formed in the diaphragm member 202 communicating with both ends of the air chamber 32 with a photosensitive resin and then curing the resin to close the entrance and exit of the air chamber 32 .

The nozzle plate 12 is formed of, for example, a rectangular polyimide film. The nozzle plate 12 faces the mounting surface of the actuator base 11 . A plurality of nozzles 28 are formed in the nozzle plate 12 so as to penetrate the nozzle plate 12 in the thickness direction.

The plurality of nozzles 28 are provided in the same number as the pressure chambers 31 and arranged to face the pressure chambers 31 respectively. A plurality of nozzles 28 are arranged along the first direction and arranged in two rows corresponding to the pair of actuators 22 . Each nozzle 28 is configured in a tubular shape with an axis extending in the third direction. For example, the nozzle 28 may have a constant diameter, or may have a shape that tapers toward the center or tip. The nozzles 28 are disposed in the middle of the extending direction of the pressure chambers 31 formed in the pair of actuators 22 and communicate with the pressure chambers 31 respectively. The nozzles 28 are arranged one by one at positions corresponding to between both ends of each pressure chamber 31, for example, at the center in the longitudinal direction.

The frame 13 is made of, for example, a nickel alloy and has a rectangular shape. The frame 13 is interposed between the mounting surface of the actuator base 11 and the nozzle plate 12 . The frame 13 is adhered to the mounting surface of the actuator base 11 and the nozzle plate 12 respectively. That is, the nozzle plate 12 is attached to the actuator base 11 via the frame 13 .

The manifold 18 is joined to the opposite side of the actuator base 11 from the nozzle plate 12 . Inside the manifold 18, an ink supply section, which is a flow path communicating with the supply hole 25, and an ink discharge section, which is a flow path which communicates with the discharge hole 26, are formed.

Circuit board 17 is a film carrier package (FCP). The circuit board 17 has a flexible resin film 51 on which a plurality of wirings are formed, and an IC 52 connected to the plurality of wirings of the film 51 . The IC 52 is electrically connected to the electrode layer 34 via the wiring of the film 51 and the pattern wiring 211 .

An ink chamber 27 surrounded by the actuator base 11, the nozzle plate 12, and the frame 13 is formed inside the inkjet head 10 configured as described above. That is, the ink chamber 27 is formed between the actuator base 11 and the nozzle plate 12 . For example, the ink chamber 27 is partitioned into three sections in the second direction by the two actuators 22, and includes two second common chambers 272 as common chambers in which the discharge holes 26 open, and a common chamber in which the supply holes 25 open. and a first common chamber 271 of . The first common chamber 271 and the second common chamber 272 communicate with the multiple pressure chambers 31 .

In the inkjet head 10 configured as described above, ink circulates between the ink tank and the ink chamber 27 through the supply hole 25 , the pressure chamber 31 and the discharge hole 26 . For example, in response to a signal input from a control unit of an inkjet printer, the drive IC 52 applies a drive voltage to the electrode layer 34 of the pressure chamber 31 via the wiring of the film 51, thereby causing the electrode layer 34 of the pressure chamber 31 and the air chamber 32 and the electrode layer 34, the side wall portion 33 is selectively subjected to shear mode deformation. By deforming the side wall portion 33 formed between the pressure chamber 31 and the air chamber 32 according to the drive signal, the volume of the pressure chamber 31 is changed. At this time, the side wall portion 241 of the diaphragm member 202 is also driven at the same time and deformed, thereby deforming the diaphragm opening 242 .

Due to the shear mode deformation of the side wall portions 33 and 241, the volume of the pressure chamber 31 provided with the electrode layer 34 increases and the pressure decreases. As a result, the ink in the ink chamber 27 flows into the pressure chamber 31 . Since the throttle port 242 communicating with the pressure chamber 31 is interlocked with the pressure chamber 31, when the volume of the pressure chamber 31 increases, the throttle port 242 also expands, promoting the inflow of ink.

With the volume of the pressure chamber 31 increased, the IC 52 applies a drive voltage of opposite potential to the electrode layer 34 of the pressure chamber 31 . As a result, the side wall portion 33 undergoes shear mode deformation, the volume of the pressure chamber 31 provided with the electrode layer 34 decreases, and the pressure increases. As a result, the ink in the pressure chamber 31 is pressurized and ejected from the nozzle 28 . Since the throttle port 242 is interlocked with the pressure chamber 31 , when the volume of the pressure chamber 31 is reduced, the throttle port 242 is also contracted to accelerate the pressure increase of the pressure chamber 31 .
Although residual vibration of the meniscus occurs after the end of driving, at this time, the throttle opening 242 has returned to the desired design size, and the fluid resistance is as designed. Therefore, it is possible to increase the ejection efficiency while suppressing the vibration of the meniscus.

A method of manufacturing the inkjet head 10 will be described with reference to FIGS. 6 and 7. FIG. First, grooves 2011 are formed in the actuator member 201 to form the pressure chambers 31 and the air chambers 32 . The grooves 2011 can be formed by machining using a dicing saw, a slicer, or the like. Subsequently, a pair of diaphragm members 202 are joined to both end portions of the actuator member 201 in the second direction, and grooves 2021 forming the diaphragm openings 242 are formed in the diaphragm members 202 . Then, it is attached to the substrate 21 with an adhesive agent or the like, and machined using a dicing saw, a slicer, or the like to form the actuator base 11 having a predetermined outer shape. For example, a block-shaped base member having a thickness corresponding to a plurality of sheets may be formed in advance and then divided to manufacture a plurality of actuator bases 11 having a predetermined shape.

Subsequently, the electrode layer 34 and the pattern wiring 211 are formed on the inner surfaces of the plurality of grooves 2011 and 2021 forming the pressure chamber 31 , the air chamber 32 , and the aperture 242 and on the surface of the substrate 21 . For example, the electrode layer 34 and the pattern wiring 211 can be formed by various methods such as forming an electrode film by electroless plating and then removing unnecessary portions of the electrode film by PEP (Photo Engraving Process). As described above, the electrode layer 34 and the pattern wiring 211 are formed at predetermined locations on the surface of the actuator base 11 .

Subsequently, the grooves 2021 extending to both ends of the air chamber 32 are closed by forming the cover portions 23 at predetermined locations. For example, among the plurality of grooves 2021 formed in the aperture member 202, the grooves 2021 communicating with the air chambers 32 are filled with a photosensitive resin, and the cover portion 23 is formed by curing the resin. As described above, the throttle 240 is formed at the entrance/exit of the pressure chamber 31, and the air chamber 32 closed by the cover portion 23 is formed.

Then, the actuator base 11 is assembled to the manifold 18, and the frame 13 is attached to one surface of the substrate 21 of the actuator base 11 with a thermoplastic resin adhesive sheet.

Then, the assembled frame 13 and the top portion of the side wall portion 33 of the actuator 22 are ground so that they are flush with each other. Then, the nozzle plate 12 is adhered to the polished surface of the top of the side wall portion 33 and the frame 13 . At this time, positioning is performed so that the nozzle 28 faces the pressure chamber 31 . Further, the inkjet head 10 is completed by connecting the driving IC chip 52 and the circuit board 17 to the pattern wiring 211 formed on the main surface of the substrate 21 via the flexible printed circuit board.

An example of an inkjet printer 100 including the inkjet head 10 will be described below with reference to FIG. FIG. 17 is an explanatory diagram showing the configuration of the inkjet printer 100. As shown in FIG. As shown in FIG. 17, the inkjet printer 100 includes a housing 111, a medium supply section 112, an image forming section 113, a medium discharge section 114, a conveying device 115, and a control section .

The inkjet printer 100 conveys a recording medium, such as paper P, which is an object to be ejected, along a predetermined conveyance path A from a medium supply unit 112 through an image formation unit 113 to a medium discharge unit 114, while feeding ink or the like. It is a liquid ejection device that performs an image forming process on a sheet of paper P by ejecting liquid.

A housing 111 constitutes an outer shell of the inkjet printer 100 . A discharge port for discharging the paper P to the outside is provided at a predetermined position of the housing 111 .

The medium supply unit 112 includes a plurality of paper feed cassettes, and is configured to be able to stack and hold a plurality of sheets of paper P of various sizes.

The medium ejection unit 114 includes a paper ejection tray configured to hold the paper P ejected from the ejection port.

The image forming section 113 includes a support section 117 that supports the paper P, and a plurality of head units 130 arranged above the support section 117 so as to face each other.

The support portion 117 includes a conveying belt 118 provided in a loop shape in a predetermined area for image formation, a support plate 119 supporting the conveying belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveying belt 118 . , provided.

During image formation, the support unit 117 supports the paper P on the holding surface, which is the upper surface of the transport belt 118, and feeds the transport belt 118 at a predetermined timing by the rotation of the belt roller 120, thereby moving the paper P downstream. carry to the side.

The head unit 130 includes a plurality of (four colors) inkjet heads 10, ink tanks 132 as liquid tanks mounted on each inkjet head 10, and a connection channel 133 connecting the inkjet heads 10 and the ink tanks 132. and a circulation pump 134 that is a circulation unit. The head unit 130 is a circulation type head unit that constantly circulates the liquid in the ink tank 132 , the pressure chamber 31 , the air chamber 32 , and the ink chamber 27 built inside the inkjet head 10 .

In this embodiment, the four-color inkjet heads 10 of cyan, magenta, yellow, and black, and the ink tanks 132 that contain the respective inks of these colors are provided. The ink tank 132 is connected to the inkjet head 10 by a connection channel 133 . The connection channel 133 includes a supply channel connected to the supply port of the inkjet head 10 and a recovery channel connected to the discharge port of the inkjet head 10 .

The ink tank 132 is also connected to a negative pressure control device such as a pump (not shown). The negative pressure control device controls the pressure inside the ink tank 132 according to the head value of the ink jet head 10 and the ink tank 132, so that the ink supplied to each nozzle 28 of the ink jet head 10 is formed into a predetermined shape. form a meniscus of .

The circulation pump 134 is, for example, a liquid feed pump configured by a piezoelectric pump. A circulation pump 134 is provided in the supply channel. The circulation pump 134 is connected to the drive circuit of the controller 116 by wiring, and is configured to be controllable under the control of a CPU (Central Processing Unit). A circulation pump 134 circulates the liquid in a circulation channel including the inkjet head 10 and the ink tank 132 .

The transport device 115 transports the paper P along the transport path A from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114 . The conveying device 115 includes a plurality of guide plate pairs 121 arranged along the conveying path A and a plurality of conveying rollers 122 .

The plurality of guide plate pairs 121 each include a pair of plate members arranged opposite to each other with the paper P being transported therebetween, and guide the paper P along the transport path A. As shown in FIG.

The transport rollers 122 are driven and rotated under the control of the control unit 116 to transport the paper P along the transport path A to the downstream side. Sensors for detecting the state of transport of the paper are arranged at various locations along the transport path A. FIG.

The control unit 116 includes a control circuit such as a CPU as a controller, a ROM (Read Only Memory) for storing various programs, and a 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.

In the inkjet printer 100 configured as described above, when the user detects a print instruction by operating the operation input unit at the interface, for example, the control unit 116 drives the transport device 115 to transport the paper P, and a predetermined By outputting a print signal to the head unit 130 at the timing of , the inkjet head 10 is driven. As an ejection operation, the inkjet head 10 sends a drive signal to the IC according to an image signal corresponding to image data, applies a drive voltage to the electrode layer 34 of the pressure chamber 31 via wiring, and selects the side wall portion 33 of the actuator 22 . Ink is ejected from the nozzles 28 by being driven statically to form an image on the paper P held on the conveying belt 118 . Further, as the liquid ejection operation, the control unit 116 drives the circulation pump 134 to circulate the liquid in the circulation channel passing through the ink tank 132 and the inkjet head 10 . By driving the circulation pump 134 , the ink in the ink tank 132 passes through the ink supply portion of the manifold 18 and flows from the supply hole 25 to the first common ink chamber 27 . chamber 271 is supplied. This ink is supplied to the plurality of pressure chambers 31 and the plurality of air chambers 32 of the pair of actuators 22 . Ink flows into the second common chamber 272 of the ink chamber 27 through the pressure chamber 31 and the air chamber 32 . This ink is discharged from the discharge hole 26 to the ink tank 132 through the ink discharge portion of the manifold 18 .

According to the embodiment described above, an inkjet head with high frequency characteristics can be provided. That is, the inkjet head 10 according to the above-described embodiment can easily form the restrictor 240 at the opening of the pressure chamber 31, which has a higher flow path resistance than the inside of the pressure chamber 31, the first common chamber 271, and the second common chamber 272. . The opening of the throttle 240 that opens to the first common chamber 271 and the second common chamber 272 , which are common chambers of the pressure chambers 31 , is smaller than the cross-sectional area of the pressure chambers 31 . Therefore, the rise of the meniscus is reduced when the ink jet head 10 ejects the liquid. Therefore, the meniscus recovers quickly, the influence on the next bullet can be reduced, and the ejection stability can be improved.

FIG. 8 shows Test Example 1 of the inkjet head 110 with an aperture (aperture 240) and Test Example 2 of the inkjet head 1010 without the aperture. FIG. 9 shows the frequency characteristics of the inkjet head 110 having an aperture according to Test Example 1, and FIG. 10 shows the frequency characteristics of the inkjet head 1010 having no aperture as Comparative Example 2. 10 and 11 show the relationship between the nozzle ejection speed and the frequency for 1 drop and 3 drop, respectively.

Here, in the inkjet head 110 according to Test Example 1, both sides in the second direction, which is the extending direction of the pressure chambers 31, communicate with the common chamber, and the nozzles 28 are opened in the middle part of the extending direction of the pressure chambers 31. It is a side shooter type.

As shown in FIG. 10, in the inkjet head 1010 according to Test Example 2, the ejection speed is flat in the low frequency region, but the ejection speed tends to decrease as the frequency increases. There is a difference in ejection speed. At 1 drop of the inkjet head 1010 according to Test Example 2, the ejection speed is flat up to 25 kHz, but the ejection speed tends to decrease as the frequency increases above 25 kHz. In addition, in the 3 drop of the inkjet head 1010 according to Test Example 2, the ejection speed is flat up to 15 kHz, but the ejection speed tends to decrease as the frequency increases above 15 kHz. Therefore, the landing position is deviated depending on the printing pattern. If there is such a large difference in the ejection speed, it takes a long time for the meniscus to subside, which causes deterioration in print quality, so high-speed driving is not possible.

On the other hand, as shown in FIG. 9, in the ink jet head 110 having the constricted portion, the ejection speed tends to be flat for both 1 drop and 3 drops. This is because the fluid resistance between the common liquid and the nozzles increases, and the rise of the meniscus decreases.

FIG. 11 shows simulation results of meniscus restoration in Test Example 1 in which a throttle is provided in the pressure chamber and Test Example 2 in which no throttle is provided. According to FIG. 11, when the meniscus state of the nozzle is at a low frequency, there is sufficient time from the ejection of an ink droplet to the ejection of the next ink droplet. Ejection is possible in this state. On the other hand, in the case of high frequency, the time from ejection of a dot (ink droplet) to ejection of the next bullet is short, so ejection of the next bullet starts before the meniscus returns. For this reason, in the case of the inkjet head 1010 having no aperture, the meniscus swells up after ejection, and the meniscus cannot be restored before the next ejection, resulting in a decrease in ejection speed. On the other hand, if the aperture is provided, the rise of the meniscus is reduced, so the meniscus recovers quickly and the influence on the next shot can be reduced. Therefore, from these simulation results, it can be said that providing a diaphragm between the pressure chamber 31 and the common chamber leads to an improvement in ejection stability of the inkjet head 110 .

FIG. 12 illustrates a side shooter type inkjet head 110 as Test Example 1 and a share mode shared wall type end shooter type inkjet head 2010 as Test Example 3 in which an ink inlet/outlet is formed at one end and nozzles are formed at the other end. It is a diagram.

13 to 16 are diagrams comparing the simulation characteristics of the end shooter type ink jet head 2010 as Test Example 3 and the side shooter type ink jet head 110 of Test Example 1 when each aperture is provided. 13 shows the drive waveform, FIG. 14 shows the nozzle flow velocity vibration, FIG. 15 shows the ejection volume, and FIG. 16 shows the meniscus recovery characteristic.

In addition, in the inkjet head 2010 according to Test Example 3, one end side of the second direction, which is the extending direction of the pressure chambers 31, communicates with the common chamber, the other end portion is closed, and the nozzle is opened at the end portion of the flow path. Shooter type. That is, the inkjet head 2010 constitutes a flow path that flows toward the nozzle 28 from one side in the second direction.

The end shooter type ink jet head 2010 supplying from one side as Test Example 3 and the side shooter type ink jet head 110 as Test Example 1 supplying from both sides have the same ejection volume, nozzle flow velocity vibration, and meniscus recovery characteristics. Since the drive voltage is the lowest in the configuration of the side shooter type with both-side supply, it can be said that the two-side supply is superior to the one-side supply from the viewpoint of drive efficiency. That is, the so-called side-shooter type inkjet head 110, which has a nozzle in the center of the pressure chamber and ink inlet/outlets at both ends, is superior in ejection efficiency to the end-shooter type inkjet head 2010. FIG.

In the inkjet head 10 according to the above-described embodiment, the diaphragm member 202 having the diaphragm opening 242 is made of a piezoelectric member, and is driven in conjunction with the pressure chambers 31 because the electrode layer 34 connected to the pressure chambers 31 is formed. be. Therefore, when the pressure chamber 31 is contracted and pressurized to eject ink, the throttle port 242 is also narrowed by simultaneous driving, promoting an increase in pressure in the pressure chamber. When the ejection is finished and the pressure chamber 31 is expanded from the contracted state, the throttle port 242 is also widened, so that rapid decompression can be suppressed and ink refilling is promoted. Although residual meniscus vibration occurs after the end of driving, the throttle opening 242 has returned to the desired design size at this time, and the fluid resistance is as designed. As described above, according to the inkjet head 10, the throttle port 242 operates in conjunction with the pressure chamber 31, so the ink ejection performance is improved.

In addition, in the inkjet head 10 according to the above-described embodiment, since the communication ports serving as the entrances and exits of the pressure chambers 31 are partially throttled, the volume of the pressure chambers 31 is reduced rather than the width of the pressure chambers 31 being reduced as a whole. easy to secure. Therefore, compared to a configuration in which the width of the pressure chamber is reduced as a whole, there are fewer restrictions on the size of the nozzles and droplets, making it easier to maintain ejection performance.

It should be noted that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the present invention at the implementation stage.

Also, the method of manufacturing the actuator is not limited to the above-described embodiments. For example, after the grooves 2011 and 2021 are formed in the actuator member 201 and the diaphragm member 202 respectively to form the cover portion 23, the surface facing the nozzle plate 12 may be polished to be the same surface. Further, after joining and assembling the diaphragm member 202 to the actuator member 201, the groove 2021 that becomes the diaphragm opening 242 may be formed after processing the outer shape into a trapezoidal shape.

For example, in the above-described embodiment, the actuator member 201 and the diaphragm member 202 are joined to each other and then adhered to the substrate 21. However, the present invention is not limited to this. The actuator member 201 and the aperture member 202 may be bonded to the substrate 21, respectively.

Also, the configuration of the actuator 22 is not limited to the above embodiment. In the above-described embodiment, an example in which the actuator 22 is formed by combining different members, that is, the actuator member 201 and the diaphragm member 202 which are separately configured has been shown, but the present invention is not limited to this. For example, the actuator 220 may be composed of one piezoelectric member 203 like the actuator 220 shown in FIGS. 19 to 21 as another embodiment. 19 to 21 are explanatory diagrams showing a method of manufacturing an actuator 220 according to another embodiment. In the actuator 220 according to this embodiment, the actuator section and the diaphragm section are integrally configured, and are configured by a common piezoelectric member 203 . In the actuator 220 according to the present embodiment, for example, a rectangular plate-shaped piezoelectric member 203 is formed with a concave portion 2031 forming a pressure chamber 31 and an air chamber 32 at a center portion in the second direction, and then, at both ends in the second direction. A groove 2032 is formed in the portion to be a throttle opening 242 having a width smaller than that of the recess 2031 . Specifically, as shown in FIG. 21, by ultrasonic machining using an ultrasonic tool S, a concave portion 2031 can be formed in the central portion of the piezoelectric member 203 . As described above, the pressure chamber 31 , the air chamber 32 , and the throttle port 242 can be sequentially formed in one piezoelectric member 203 .

Further, for example, the thickness ratio of the two piezoelectric bodies in the actuator member 201 and the diaphragm member 202 may be the same.

The depths of the grooves 2011 and recesses 2031 forming the pressure chamber 31 and the air chamber 32 may be different from the depths of the grooves 2011 and 2032 forming the throttle port 242 . Moreover, both the concave portion 2031 forming the pressure chamber 31 and the air chamber 32 and the groove 2032 forming the throttle port 242 may be formed by ultrasonic processing.

In the above embodiment, the diaphragms 240 on both sides may have different configurations. For example, by forming the throttle 240 in at least one communicating port of the pressure chamber 31 whose both sides communicate with the common chambers 271 and 272, the ejection performance is improved and the throttle 240 can be formed inexpensively and easily. is obtained.

Further, the cover portion 23 is formed inside the throttle port 242 communicating with the air chamber 32 and has a shape that fills the throttle port 242, but is not limited to this. For example, on the sides of the actuators 22 and 220 , the cover portion 23 that closes the air chamber 32 may be formed outside the throttle port 242 that communicates with the air chamber 32 .

In the above embodiment, an example in which the actuator 22 having a plurality of grooves is arranged on the main surface of the substrate 21 is shown, but the present invention is not limited to this. For example, an actuator may be provided on the end face of the substrate 21 . Also, the number of nozzle rows is not limited to that of the above embodiment, and may be configured to have one row or three or more rows.

Further, in the above-described embodiment, the actuator base 11 having the laminated piezoelectric member made of the piezoelectric member on the substrate 21 was illustrated, but the present invention is not limited to this. For example, the actuator base 11 may be formed only by a piezoelectric member without using a substrate. Further, each piezoelectric member may be composed of one piezoelectric body. The air chamber 32 may communicate with the first common chamber 271 and the second common chamber 272, which are common chambers. Also, the supply side and the discharge side may be reversed, or may be configured to be switchable.

In the above embodiment, as an example, one side of the pressure chamber 31 is the supply side, the other side is the discharge side, and the first common chamber fluid flows in from one side of the pressure chamber and flows out from the other side. Although an ink jet head of the type is exemplified, it is not limited to this. For example, it may be non-circulating. Further, for example, the common chambers on both sides of the pressure chamber 31 may be the supply side, and the configuration may be such that the fluid flows in from both sides. That is, the fluid may flow in from both sides of the pressure chamber 31 and flow out from the nozzle 28 arranged in the center of the pressure chamber 31 . Even in this case, by providing the throttles 240 at the communication ports serving as inlets on both sides of the pressure chamber 31, the fluid resistance is increased and the ejection efficiency can be improved. Also, the diaphragms 240 formed at both ends may have different configurations.

In the above embodiment, an example in which the throttles 240 are formed at both ends of the pressure chamber 31 in the extending direction is shown, but the present invention is not limited to this, and the pressure chamber 31 communicates with the common chambers 271 and 272 at both ends. The aperture 240 may be formed only on one of the entrances on both sides. For example, an aperture 240 having a higher fluid resistance than the inside of the pressure chamber 31 is formed at one end, and the other end has the same fluid resistance as the inside of the pressure chamber 31, such as the cross-sectional area of the inside of the pressure chamber 31. A configuration having the same cross-sectional area of the communication port may be used.

Further, for example, the liquid to be ejected is not limited to printing ink, and may be a device that ejects a liquid containing conductive particles for forming a wiring pattern of a printed wiring board.

In the above embodiments, the inkjet head is used in a liquid ejection device such as an inkjet printer. However, it is not limited to this, and can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications. It is possible to reduce the size, weight, and cost.

According to at least one embodiment described above, it is possible to provide a liquid ejection head and a method for manufacturing the liquid ejection head that can ensure stable ejection characteristics.

Additionally, while several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 10... Inkjet head 11... Actuator base 12... Nozzle plate 13... Frame 17... Circuit board 18... Manifold 21... Substrate 22... Actuator 201... Actuator member 202... Diaphragm member 203... Piezoelectric member , 25 Supply hole 26 Discharge hole 27 Ink chamber 31 Pressure chamber 32 Air chamber 33 Side wall 34 Electrode layer 51 Film 52 Drive IC chip 100 Inkjet printer Reference Signs List 111 housing 112 medium supply unit 113 image forming unit 114 medium discharge unit 115 transport device 116 control unit 117 support unit 118 transport belt 119 support plate 120 Belt roller 121 Guide plate pair 122 Carrying roller 130 Head unit 132 Ink tank 133 Connection channel 134 Circulation pump 211 Pattern wiring 221 Side surface 222 Top , 240... Aperture, 242... Aperture opening, 271... First common chamber, 27... Ink chamber, 272... Second common chamber.

Claims (5)

an actuator section made of a piezoelectric member and having a pressure chamber and an air chamber;
a throttling portion made of a piezoelectric member, provided at openings on both sides of the pressure chamber, and having throttling openings communicating with the pressure chamber and increasing fluid resistance of the pressure chamber;
A share mode shared wall liquid ejection head. electrodes are formed in the pressure chamber and the aperture;
the electrode of the pressure chamber and the electrode of the throttle opening are electrically connected;
The liquid ejection head according to claim 1. 3. The liquid ejection head according to claim 1, wherein said throttle section and said actuator section are made of different members. the actuator section is configured by stacking a plurality of piezoelectric bodies with a predetermined thickness ratio,
4. The liquid ejection head according to claim 3, wherein said throttle section is formed by laminating a plurality of piezoelectric bodies with a thickness ratio different from that of said actuator section. 3. The liquid ejection head according to claim 1, wherein said actuator section and said throttle section are integrally formed.