JP2023032310A - Liquid discharge head and method for manufacturing liquid discharge head - Google Patents

Abstract

To provide a liquid discharge head capable of securing stable discharge characteristics, and a method for manufacturing a liquid discharge head.SOLUTION: A liquid discharge head includes a plurality of pressure chambers, a plurality of dummy chambers, a common chamber, and a cover member. The pressure chambers communicate with nozzles for discharging a liquid. The dummy chambers are arranged among the plurality of pressure chambers. The common chamber communicates with both sides of the plurality of pressure chambers. The cover member has a hole part at a position covering an opening opened to the common chamber of the pressure chambers and the dummy chambers, and facing the pressure chambers.SELECTED DRAWING: Figure 6

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 in the flow path from the common liquid chamber to the nozzles, the greater the overshoot. If the overshoot is not 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 includes a plurality of pressure chambers, a plurality of dummy chambers, a common chamber, and a cover member. The pressure chamber communicates with a nozzle that ejects liquid. A dummy chamber is arranged between the plurality of pressure chambers. A common chamber communicates with both sides of the plurality of pressure chambers. The cover member covers openings of the pressure chamber and the dummy chamber that open to the common chamber, and has a hole at a position facing 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. 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. Sectional drawing which expands and shows a structure of one part of the same inkjet head. FIG. 2 is an enlarged perspective view showing the configuration of a part of the 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.

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 6. 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. 3, 4, and 5 are cross-sectional views enlarging a part of the structure of the inkjet head, and FIG. 6 is a perspective view showing a part of the structure of the inkjet head in an enlarged manner. 7 and 8 are explanatory diagrams of the manufacturing process of the ink jet head, showing the internal structure with the cover member 24 omitted. In the drawing, X, Y, and Z indicate the first direction, the second direction, and the 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 6, the inkjet head 10 is a so-called side shooter type share mode share wall type 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 dummy chambers 32 are alternately arranged. The dummy 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 FIG. 2, the actuator base 11 includes a substrate 21, a pair of actuators 22, and a cover member 24. As shown in FIG.

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 FIG. 2, 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.

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 is formed of two plate-like piezoelectric bodies made 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 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 actuator 22 is formed to have a trapezoidal cross section. The side portion 221 of the actuator 22 has inclined surfaces that are inclined with respect to the second direction and the third direction. That is, the actuator 22 is configured to have a trapezoidal cross-sectional view perpendicular to the second direction. The top of actuator 22 is glued to nozzle plate 12 . The actuator 22 includes multiple pressure chambers 31 and multiple dummy chambers 32 . The actuator 22 has a plurality of side wall portions 33 and has grooves forming the pressure chambers 31 and the dummy chambers 32 between the side wall portions 33 . In other words, the side wall portion 33 is formed as a driving element between the grooves forming the pressure chamber 31 and the dummy chamber 32 .

As shown in FIGS. 1 to 6 , the bottom surface of the groove and the main surface of the substrate 21 are connected by inclined side surfaces 221 . The pressure chambers 31 and the dummy chambers 32 are arranged alternately. The pressure chambers 31 and the dummy 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 .

The shape of the pressure chamber 31 and the shape of the dummy chamber 32 may be different. The side wall portion 33 is formed between the pressure chamber 31 and the dummy chamber 32 and deforms according to the drive signal to change the volume of the pressure chamber 31 .

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 . Therefore, the ink flows in from one end of the pressure chamber 31 and the ink flows out from the other end. The pressure chamber 31 has a constricted portion 240 whose openings at both ends in the second direction are partially closed by the cover member 24 to increase the flow path resistance.

One side of the dummy chamber 32 in the third direction is closed by the nozzle plate 12 joined to the top, and both sides in the second direction are closed by the cover member 24 .

The cover member 24 has a plate member 241 having a predetermined thickness. The plate member 241 is configured in a shape corresponding to the inclined side surface portion 221 of the actuator, such as a rectangular shape extending in the first direction. The plate member 241 is formed with a plurality of apertures 242 as apertures penetrating in the thickness direction. The cover members 24 are provided on both ends of the actuator 22 in the second direction, respectively, to block the opening of the dummy chamber 32 and partially block the opening of the pressure chamber. For example, the cover member 24 is made of a resin material such as PI (polyimide) or PET (polyethylene terephthalate). The grooves forming the pressure chambers 31 communicate with the first common chamber 271 and the second common chamber 272 through throttle holes 242 formed in the cover member 24 .

The cover member 24 closes part of the opening communicating with the first common chamber 271 and the second common chamber 272, which are common chambers at both ends of the pressure chamber 31, thereby forming a flow path perpendicular to the second direction of the pressure chamber 31. A constricted portion 240 is formed to increase the fluid resistance by reducing the cross-sectional area of .

The cover member 24 is joined to the inclined side portion 221 of the actuator 22 . Also, one edge of the cover member 24 may be joined to the substrate 21 .

Note that if the fluid resistance of the throttle portion 240 is too large, the ink replenishment to the pressure chamber 31 after the ejection of the ink droplets will be delayed, which will hinder the speeding up. Also, the bulge of the meniscus varies depending on the ink viscosity, ejection volume, drive frequency, and the like. Therefore, the thickness of the cover member 24 and the size and position of the throttle hole 242 of the throttle portion 240 are set so as to provide flow path resistance according to the ink replenishment conditions and the meniscus swelling characteristics.

Both ends of the plurality of dummy chambers 32 are closed by cover members 24, for example. That is, cover members 24 are arranged between the first common chamber 271 of the ink chamber 27 and the entrance of the dummy chamber 32 and between the exit of the dummy chamber 32 and the second common chamber 272, respectively. is separated from the ink chamber 27 . Therefore, the dummy chamber 32 constitutes an air chamber into which ink does not flow.

An electrode layer 34 is provided in each of the pressure chambers 31 and the dummy chambers 32 of the actuator base 11 . The electrode layer 34 is formed of, for example, a nickel thin film. The electrode layer 34 extends from the bottom of the groove to the substrate 21 and is connected to the pattern wiring 211 .

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. One nozzle 28 is arranged in each pressure chamber 31 in the central portion 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, the pressure chamber, and the discharge hole. For example, 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 in response to a signal input from a control unit of an inkjet printer, thereby causing the electrode layer 34 of the pressure chamber 31 and the dummy chamber to 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 dummy chamber 32 according to the drive signal, the volume of the pressure chamber 31 is changed.

Due to the shear mode deformation of the side wall portion 33, 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 .

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 .

As a method of manufacturing the inkjet head 10, a piezoelectric member forming a plurality of grooves is attached to a plate-like substrate 21 with an adhesive or the like, and the actuator is machined using a dicing saw, a slicer, or the like to have a predetermined outer shape. A base 11 is molded. 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 grooves forming the pressure chambers 31 and the dummy chambers 32 and on the surface of the substrate 21 . As a result, as shown in FIG. 7, the electrode layer 34 and the pattern wiring 211 are formed on the surface of the actuator base 11 at predetermined locations. Then, as shown in FIG. 8 , a thin flat plate member 241 constituting the cover member 24 is adhered to the side surface portion 221 of the actuator 22 . For example, the plate member 241 is made of a resin material such as PI or PET in a thin plate shape. Then, after the plate member 241 is joined, a hole is formed by laser processing at a predetermined portion of the plate member 241 covering the pressure chamber 31 to form a communication hole (throttle hole) 242 .

Further, 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 an adhesive sheet of thermoplastic resin.

Then, the assembled frame 13, the top portion 222 of the side wall portion 33 of the actuator 22, and the facing surface of the cover member 24 on the side of the nozzle plate 12 are polished so as to be flush with each other. Then, the nozzle plate 12 is adhered and attached to the facing surfaces of the polished top portion 222 of the side wall portion 33, the frame 13, and the cover member 24. As shown in FIG. At this time, positioning is performed so that the nozzle 28 faces the pressure chamber 31 . Further, as shown in FIG. 1, 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. 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 116 .

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 built inside the inkjet head 10 , the dummy chamber 32 , and the ink chamber 27 .

In this embodiment, there are four ink jet heads 10 of cyan, magenta, yellow, and black, and ink tanks 132 that respectively contain the inks of these colors. 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 dummy 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 dummy 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 above-described embodiments, it is possible to provide a liquid ejection head and a method for manufacturing the liquid ejection head that can ensure stable ejection characteristics. That is, in the inkjet head 10 according to the above-described embodiment, the pressure chambers 31 are provided with the cover members 24 so that the entrances and exits of the pressure chambers 31 are located closer to the inside of the pressure chambers 31 and than the first common chamber 271 and the second common chamber 272 . High flow resistance. As a specific example, the openings that open to the first common chamber 271 and the second common chamber 272 that are common chambers of the pressure chambers 31 are smaller than the flow channel 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. 9 shows Test Example 1 of the inkjet head 110 with the diaphragm (throttling portion 240) and Test Example 2 of the inkjet head 1010 without the diaphragm. FIG. 10 shows the frequency characteristics of an inkjet head 110 with an aperture according to Test Example 1, and FIG. 11 shows the frequency characteristics of an inkjet head 1010 without an aperture as Comparative Example 2. FIG. 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 of 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. 11, 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. 10, 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 nozzles increases from the common liquid, and the rise of the meniscus decreases.

FIG. 12 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. 12, when the meniscus state of the nozzle is at a low frequency, there is a 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. 13 shows a side shooter type inkjet head 110 having ink inlets and outlets at both ends as Test Example 1, and a share mode shared wall type end shooter type as Test Example 3 in which ink inlets and outlets are formed at one end and nozzles are formed at the other end. FIG. 3 is an explanatory diagram of an inkjet head 2010;

FIG. 14 is a diagram 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, each having a diaphragm. 15 shows the drive waveform, FIG. 16 shows the nozzle flow velocity vibration, FIG. 17 shows the ejection volume, and FIG. 18 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.

Generally, in a shared-mode shared-wall type ink jet head, for example, pressure chambers are composed of fine grooves formed in a piezoelectric body by a diamond cutter. Although it is difficult, according to the above embodiment, by attaching the plate member 241 to the actuator 22 and forming the communicating hole (aperture hole) 242 by laser processing, the number of processes is reduced, and fine processing can be performed only by laser drilling. Therefore, the aperture can be formed easily and inexpensively. Furthermore, since the hole diameter can be selected relatively freely by perforating by laser processing, it is also easy to freely design the fluid resistance of the aperture.

Moreover, the cover member 24 has a simple shape, can be manufactured at a low cost, and requires less manufacturing steps, which facilitates joining and positioning. PI, which is the material of the cover member 24, has good laser processability and excellent chemical resistance, so it is suitable for use as a part that comes into contact with ink.

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.

In the above embodiment, as an example, one side of the pressure chamber 31 is the supply side and the other side is the discharge side. It is not limited. 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 throttles at the inlet portions on both sides of the pressure chamber 31, the fluid resistance increases and the ejection efficiency can be improved.

Further, in the above-described embodiment, the cover member 24 in which the plate member 241 is formed with the plurality of aperture holes 242 serving as aperture apertures is illustrated, but the present invention is not limited to this. For example, the cover member 24 may form the narrowed portion 240 having a higher fluid resistance than the pressure chamber 31, and the narrowed opening may be formed of a plurality of slit-like openings.

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.

Although an example in which the thin plate member is made of a resin material such as PI has been shown in the above embodiment, the present invention is not limited to this. For example, it may be made by cutting mold parts made of ceramic materials such as zirconia and alumina, or machinable ceramics.

Further, in the above-described embodiment, the actuator base 11 having the laminated piezoelectric member including the piezoelectric member 131 on the substrate 21 is 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. Also, instead of using two piezoelectric members, one piezoelectric member may be used. The dummy room 32 may communicate with the first common room 271 and the second common room 272, which are common rooms. Also, the supply side and the discharge side may be reversed, or may be configured to be switchable.

For example, the liquid to be ejected is not limited to ink for printing, and may be a device that ejects 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 24... Cover member (wall part) 25... Supply hole, 26... discharge hole 27... ink chamber 31... pressure chamber 32... dummy chamber 33... side wall portion 34... electrode layer 51... film 52... drive IC chip 81... ink supply portion 82... ink discharge Part 100... Inkjet printer 111... Housing 112... Medium supply part 113... Image forming part 114... Medium discharge part 115... Conveying device 116... Control part 117... Support part 118... Conveying belt, DESCRIPTION OF SYMBOLS 119... Support plate, 120... Belt roller, 121... Guide plate pair, 122... Conveying roller, 130... Head unit, 132... Ink tank, 133... Connection channel, 134... Circulation pump, 211... Pattern wiring, 221... Side portion 222 Top portion 240 Throttle portion 241 Plate member 242 Throttle hole (communication hole) 271 First common chamber 272 Second common chamber.

Claims (5)

a plurality of pressure chambers communicating with nozzles for ejecting liquid;
a plurality of dummy chambers arranged between the plurality of pressure chambers;
a common chamber communicating with both sides of the plurality of pressure chambers;
a cover member that covers the openings of the pressure chamber and the dummy chamber that open to the common chamber, and has a throttle opening at a position facing the pressure chamber, the throttle port having a greater fluid resistance than the inside of the pressure chamber; Side shooter type liquid ejection head. an actuator having a plurality of grooves that form the pressure chamber and the dummy chamber, and a side wall formed between the grooves that changes the volume of the pressure chamber according to a drive signal;
The plurality of nozzles and the plurality of pressure chambers are arranged side by side in a first direction,
each of the pressure chambers extends in a second direction that intersects with the first direction;
A discharge direction of the liquid discharged from the nozzle intersects the first direction and the second direction, and
2. The liquid ejection head according to claim 1, wherein said cover member is joined to a side surface of said actuator. the nozzle is arranged at a position corresponding to the middle portion of the pressure chamber in the second direction;
The common chambers are arranged on one side and the other side of the pressure chambers in the second direction, respectively;
3. The liquid ejection head according to claim 2, wherein said cover members are arranged between said common chambers at both ends of said pressure chambers. 4. The liquid ejection head according to claim 1, wherein said cover member is made of a material containing polyimide. a plurality of pressure chambers communicating with nozzles for ejecting liquid; a plurality of dummy chambers arranged between the plurality of pressure chambers; and a common chamber communicating with both sides of the plurality of pressure chambers and the dummy chambers. covering the opening of the dummy chamber and the opening of the pressure chamber by attaching a plate member made of a resin material to a side portion of the actuator having the opening where the pressure chamber and the dummy chamber open,
A side-shooter type liquid discharger, in which a throttle port is formed by laser processing at a position of the plate member facing the pressure chamber so as to communicate the pressure chamber with the common chamber and to have a larger fluid resistance than the inside of the pressure chamber. How the head is made.

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