JP2023114243A - Liquid discharge head - Google Patents

Abstract

To provide a liquid discharge head capable of securing stable discharge characteristics.SOLUTION: A liquid discharge head according to one embodiment includes: actuator members; common electrodes; individual electrodes; and a non-piezoelectric member. In the actuator member, piezoelectric materials which are polarized in directions opposite to each other are laminated. Further, the actuator member has multiple grooves forming multiple pressure chambers and multiple grooves forming multiple air chambers on one side surface and the bottom part side of the multiple grooves is connected. The multiple grooves forming the multiple air chambers are located adjacent to the multiple pressure chambers and have a larger dimension in a depth direction than the grooves forming the pressure chambers. The common electrodes are respectively formed on inner surfaces including bottom parts of the multiple air chambers. The individual electrodes are respectively formed on inner surfaces including bottom parts of the multiple pressure chambers. The non-piezoelectric member is disposed facing the one side surface of each actuator member.SELECTED DRAWING: Figure 7

Description

TECHNICAL FIELD Embodiments of the present invention relate to liquid ejection heads.

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, in a share-mode shared-wall type inkjet head, the same drive column is shared by two pressure chambers, and one-third of the plurality of arranged chambers are simultaneously driven as pressure chambers, so-called three-cycle drive. is. 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 number of grooves are formed in a piezoelectric member, 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, the vibrations generated when one pressure chamber is driven are transmitted to the ink in the other pressure chamber via the piezoelectric member, so that the speed and volume of ink droplets change due to the influence of the driving of adjacent pressure chambers. , so-called crosstalk occurs.

Japanese Patent Application Laid-Open No. 2015-189031

A problem to be solved by the present invention is to provide a liquid ejection head capable of ensuring stable ejection characteristics.

A liquid ejection head according to one embodiment includes an actuator member, a common electrode, individual electrodes, and a non-piezoelectric member. The actuator member is laminated with piezoelectric bodies polarized in opposite directions, and has a plurality of grooves forming a plurality of pressure chambers and a plurality of grooves forming a plurality of air chambers on one side surface. The bottom sides of the grooves are connected. The plurality of grooves forming the plurality of air chambers are adjacent to the plurality of pressure chambers and have a larger depth dimension than the grooves forming the pressure chambers. A common electrode is formed on the inner surface including the bottoms of the plurality of air chambers. Individual electrodes are formed on the inner surface including the bottoms of the plurality of pressure chambers. A non-piezoelectric member is arranged to face the one side surface of the actuator member.

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. 3 is a perspective view showing a part of the inkjet head of FIG. 2; Sectional drawing which expands and shows a structure of one part of the same inkjet head. FIG. 5 is a cross-sectional view of the inkjet head of FIG. 4 taken along line VV; FIG. 5 is a cross-sectional view of the inkjet head of FIG. 4 taken along line VI-VI; FIG. 3 is a partially enlarged cross-sectional view enlarging a part of the cross section of the inkjet head of FIG. 2 cut along VII-VII; FIG. 4 is an explanatory diagram showing the relationship between the depth of the air chamber and the amount of crosstalk in the inkjet head according to the embodiment; FIG. 4 is an explanatory diagram of the deformation amount in the driving state of the actuator in the same inkjet head and the inkjet head according to the comparative example. 1 is a schematic diagram showing an inkjet printer according to an embodiment; FIG. FIG. 4 is a perspective view showing a part of an inkjet head according to another embodiment; Sectional drawing which expands and shows a structure of one part of the same inkjet head. FIG. 13 is a cross-sectional view of the inkjet head of FIG. 12 taken along line XIII-XIII; FIG. 13 is a cross-sectional view of the inkjet head of FIG. 12 taken along line XIV-XIV;

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 8. 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 to 7 are enlarged sectional views showing a partial configuration 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 this embodiment, the direction in which the grooves forming the nozzles and the pressure chambers 31 and 32 are aligned is the X axis, the extension direction of the pressure chambers 31 and the air chambers 32 is the Y axis, and the liquid ejection direction is the Z axis. The directions are described based on the orientation along each axis, but are not limited to this.

The inkjet head 10 shown in FIGS. 1 to 7 is a so-called side shooter share mode 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 FIG. 2, the actuator base 11 includes a substrate 21 and a pair of actuator members 22. 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 actuator members 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 member 22 . For example, the pattern wiring 211 is formed at a position avoiding the supply hole 25 and the discharge hole 26 .

The supply holes 25 are arranged in the longitudinal direction of the actuator members 22 between the pair of actuator members 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 actuator members 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 such a configuration, the inkjet head 10 is of a circulation type, and ink flows from one side of each pressure chamber 31 where the supply holes 25 are located to the other side where the discharge holes 26 are located. Alternatively, for example, the ink discharge section may be opened only during maintenance and communicated with the ink supply section during printing. In such a configuration, the inkjet head 10 becomes a non-circulating type, and ink flows into each pressure chamber 31 from both sides.

A pair of actuator members 22 are adhered to the mounting surface of the substrate 21 . A pair of actuator members 22 are arranged in two rows on the substrate 21 with the supply hole 25 interposed therebetween. Each actuator member 22 is formed by two plate-like piezoelectric bodies 201 and 202 made of lead zirconate titanate (PZT), for example. The two piezoelectric bodies 201 and 202 are polarized such that their polarization directions are opposite to each other in the thickness direction. That is, the actuator member 22 is formed by laminating a pair of piezoelectric bodies 201 and 202, and is polarized in opposite directions in the lamination direction. The actuator member 22 is adhered to the mounting surface of the substrate 21 with, for example, a thermosetting epoxy adhesive. As shown in FIG. 2, the actuator members 22 are arranged in parallel in the ink chamber 27 corresponding to the nozzles 28 arranged in two rows. The actuator member 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 top of actuator member 22 is glued to nozzle plate 12 .

The actuator member 22 is composed of a laminated piezoelectric member in which a plurality of piezoelectric bodies 201 and 202 are laminated. Prepare in parallel. The plurality of piezoelectric bodies 201 and 202 are laminated with the thickness direction along the third direction, and are configured by being adhered to each other. Note that the laminated piezoelectric member is polarized during the manufacturing process.

The actuator member 22 has a plurality of grooves forming the pressure chambers 31 and the air chambers 32 extending in the first direction on one side surface in the third direction that is the depth direction, that is, one side surface facing the nozzle plate 12 . formed side by side. The actuator member 22 is formed in a comb shape in which one side of the laminated piezoelectric member is divided into a plurality of sections by a plurality of grooves, and the bottom sides of the plurality of grooves are integrally connected. The actuator member 22 is divided into a plurality of parts by forming a groove on one side surface by dicing, for example, and the other end side is connected, and the side wall 33 sandwiches the groove along the first direction indicated by X in the drawing. Multiple parallel arrangement.

The actuator member 22 has a plurality of side walls 33 and grooves forming pressure chambers 31 and air chambers 32 between the side walls 33 . In other words, the side walls 33 are formed as drive elements between the grooves forming the pressure chamber 31 and the air chamber 32 . The side wall 33 is formed between the pressure chamber 31 and the air chamber 32 and deforms according to the drive signal to change the volume of the pressure chamber 31 .

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

FIG. 4 is a partially enlarged sectional view of one of the actuator members 22 of the inkjet head 10 shown in FIG. FIG. 5 is a cross-sectional view of the grooves forming the pressure chambers 31 of the inkjet head 10 shown in FIG. 4, taken along line VV. 6 is a cross-sectional view taken along the line VI--VI of the groove forming the air chamber 32 of the inkjet head 10 shown in FIG.

As shown in FIGS. 2, 5 and 6, the bottom surface of the groove and the main surface of the substrate 21 are connected by inclined side surfaces 221 . A plurality of pressure chambers 31 and 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 member 22 and are arranged in parallel in a first direction (the X axis in the figure), which is the longitudinal direction of the actuator member 22 . In this embodiment, for example, the plurality of grooves forming the pressure chambers 31 and the air chambers 32 have a width dimension in the X direction that is constant in the depth direction along the Z direction, and a width dimension in the Y direction that is the extending direction of the grooves. The orthogonal cross section is configured in a rectangular shape.

The plurality of grooves arranged in the first direction are formed such that the depth DB of the grooves forming the air chamber 32 is deeper than the depth DA of the grooves forming the pressure chamber 31 . That is, of the pressure chambers 31 and the air chambers 32 that are open to the nozzle plate 12 side, the bottom of the groove that constitutes the air chamber 32 is deeper than the bottom of the groove that constitutes the pressure chamber 31 in the third direction, which is the depth direction. , and away from the nozzle plate 12 , i.e., on the inner side of the actuator member 22 . As an example, the depth DB of the air chamber 32 is deeper than the depth DA of the pressure chamber 31 by the distance between the pressure chambers 31 and 32 , that is, the thickness of the side wall 33 . In this embodiment, the depth DA of the pressure chamber 31 is 150 μm, and the depth DB of the air chamber 32 is 200 μm. The grooves forming the pressure chambers 31 and the grooves forming the air chambers 32 may have the same width dimension along the longitudinal direction and the dimension in the extending direction, or may be different. The bottom of the pressure chamber 31, the bottom of the air chamber 32, and the side wall 33 are composed of laminated piezoelectric members. That is, the pressure chambers 31 and the air chambers 32 have inner wall surfaces including their bottoms made of a piezoelectric member, and the nozzle plate 12, which is a non-piezoelectric member, is arranged in the opening on one side. are closed by cover portions 23, which are non-piezoelectric members.

Electrode layers 34 are provided on the inner wall surfaces of the pressure chambers 31 and the air chambers 32 of the actuator member 22 and on the side surface portion 221 respectively. 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 surface of the groove through the side surface 221 to the substrate 21 and is connected to the pattern wiring 211 . For example, the electrode layer 34 is formed on the inner surface of the groove including the bottom surface of the side wall 33 . As an example, the electrode layer 34 formed in the pressure chamber 31 constitutes an individual electrode, and the electrode layer 34 formed in the air chamber 32 constitutes a common electrode. The electrode layer 34 forming the individual electrode is formed on the inner surface including the bottom of the pressure chamber 31 , is led out from one side of the pressure chamber 31 in the extending direction to one side surface 221 , and is connected to the pattern wiring 211 . The electrode layer 34 forming the common electrode is formed on the inner surface including the bottom of the air chamber 32 , is led out from the other side to the other side surface portion 221 , and is connected to the pattern wiring 211 .

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. Also, the ink may flow from both ends of the pressure chamber 31 .

As shown in FIGS. 3 and 6, one side of the air chamber 32 in the third direction (Z direction) is closed by the nozzle plate 12 joined to the top. Further, both ends of the air chambers 32 in the second direction are closed by the cover portions 23, for example. That is, the cover portion 23 is arranged between the first common chamber 271 and the air chamber 32 of the ink chamber 27 and between the air chamber 32 and the second common chamber 272 , and both ends of the air chamber 32 are located between the ink chamber 27 and the ink chamber 27 . separated. Therefore, the air chamber 32 constitutes an air chamber into which ink does not flow.

For example, the cover portions 23 are provided at both ends in the Y direction, which is the extending direction of each air chamber 32 . The cover portion 23 is a partition that connects the ends of the side walls 33 and separates the common chambers 271 and 272 from the air chamber 32 .

The cover part 23 is a wall-shaped member that closes the end of the air chamber 32 . For example, the cover portion 23 connects end portions of a pair of side walls 33 forming both sides of the air chamber 32 . The cover portion 23 is made of a photosensitive resin material. For example, the cover portion 23 is molded into a predetermined shape by applying a photosensitive resin to both ends of the air chamber 32 and then curing the resin by exposure. For example, part of the cover portion 23 is arranged inside the air chamber 32 .

The nozzle plate 12 is a non-piezoelectric member and is formed of, for example, a polyimide rectangular 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 (X direction) and arranged in two rows corresponding to the pair of actuator members 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 actuator members 22 and communicate with the pressure chambers 31 respectively. A plurality of nozzles 28 are arranged at positions corresponding to between both ends of each pressure chamber 31, for example, one at 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.

The circuit board 17 shown in FIG. 1 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 a drive IC 52 connected to the plurality of wirings of the film 51 . The drive 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 (Y direction) by the two actuator members 22, and two second common chambers 272 serving as common chambers in which the discharge holes 26 open and the supply hole 25 are provided. and a first common room 271 as an open common room. 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, 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 sidewall 33 is selectively deformed in a shear mode. The side wall 33 is shear-deformed so that the cross-sectional shape of the laminated piezoelectric bodies is bent into a doglegged shape. By deforming the side wall 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.

Due to the shear mode deformation of the side wall 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 .

When the drive IC 52 applies a drive voltage with a reverse potential to the electrode layer 34 of the pressure chamber 31 while the volume of the pressure chamber 31 is increased, the side wall 33 undergoes shear mode deformation and the pressure chamber 31 provided with the electrode layer 34 is deformed. volume decreases and pressure increases. As a result, the ink in the pressure chamber 31 is pressurized and ejected from the nozzle 28 .

A method for manufacturing the inkjet head 10 will be described. First, a piezoelectric member forming a plurality of grooves is attached to a plate-shaped substrate 21 with an adhesive or the like, and mechanical processing is performed 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 grooves forming the pressure chambers 31 and the air chambers 32 and on the surface of the substrate 21 . 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, both ends of the air chamber 32 are closed by forming the cover portions 23 at the ends of the air chamber 32 . For example, the groove forming the air chamber 32 is filled with a photosensitive resin, and the target portion is cured to form the cover portion 23 . Alternatively, the cover portion 23 is formed by molding the photosensitive resin layer after curing the photosensitive resin.

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 actuator member 22 are polished so that the nozzle plate 12 side surface of the top portion of the side wall 33 becomes the same surface. Then, the nozzle plate 12 is adhered to the polished surface of the frame 13 at the top of the side wall 33 . At this time, positioning is performed so that the nozzle 28 faces the pressure chamber 31 . Furthermore, as shown in FIG. 1, the inkjet head 10 is completed by connecting the driving IC 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 , 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, the control unit 116 drives the conveying device 115 to convey the paper P when, for example, the interface unit detects a print instruction by the user operating the operation input unit, and a predetermined By outputting a print signal to the head unit 130 at the timing of , the inkjet head 10 is driven. In the ejection operation, the inkjet head 10 sends a drive signal to the drive IC 52 according to the image signal corresponding to the image data, and applies a drive voltage to the electrode layer 34 of the pressure chamber 31 through the wiring to push the side wall 33 of the actuator member 22. It is selectively driven to eject ink droplets from the nozzles 28 to form an image on the paper P held on the transport 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 of the pair of actuator members 22 . Ink flows through the pressure chamber 31 into the second common chamber 272 of the ink chamber 27 . 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 inkjet head 10 according to the above-described embodiment, so-called crosstalk can be suppressed, and it is easy to ensure stable ejection performance. That is, according to the inkjet head 10 of the above-described embodiment, since the air chamber 32 is formed deep, vibration transmission between the plurality of pressure chambers 31 can be suppressed. That is, by increasing the depth of the air chamber 32, it is possible to secure the distance between the vibrating portion of the side wall 33 of the piezoelectric member 20 and the connecting portion where the plurality of side walls 33 are connected. Transmission of vibration to 33 can be suppressed. Therefore, it is possible to suppress the so-called crosstalk in which the vibration of the side wall 33 when driving the pressure chamber 31 in the actuator member 22 is transmitted to the ink in another adjacent pressure chamber 31 and affects the pressure of the ink in the pressure chamber. , easy to maintain ejection performance.

FIG. 8 is a graph showing the relationship between the depth [μm] of the air chamber 32 and the crosstalk amount [%] in the inkjet head 10 . Here, the crosstalk amount indicates the ratio of the flow velocity amplitude generated in the adjacent nozzles 28 when the flow velocity amplitude generated in the nozzles 28 to be driven is 100%. FIG. 8 shows the amount of crosstalk when the depth of the air chamber 32 is changed from 150 μm to 300 μm when the depth of the pressure chamber 31 is 150 μm. It can be seen from FIG. 8 that the greater the depth of the air chamber 32, the smaller the amount of crosstalk.

FIG. 9 is an explanatory diagram showing deformation states of the sidewalls 33 during driving of the inkjet head 10 according to the present embodiment and the inkjet head 1010 according to Comparative Example 1. FIG. FIG. 9 shows the magnitude and direction of deformation of each part of the actuator member 22 by arrows. The direction of the arrow indicates the direction of deformation (displacement) at that position, and the size of the arrow indicates the amount of deformation (displacement). The inkjet head 1010 according to Comparative Example 1 is configured such that the depth of the air chamber 32 and the depth of the pressure chamber 31 are equal, and other configurations are similar to those of the inkjet head 10 . FIG. 9 shows the vibration state when the pressure chamber 311 on one side in the direction in which the grooves of the inkjet heads 10 and 1010 are arranged is driven and the pressure chamber 312 on the other side is not driven.

According to FIG. 9, in the inkjet head 1010 according to Comparative Example 1, although the pressure chambers 312 are not driven, the non-driven pressure chambers 312 are formed on the other side of the air chambers 32 in the direction in which the grooves are arranged. It can be seen that the side wall 33 is deformed and the operation of the pressure chamber 311 affects the pressure chamber 312 . On the other hand, in the inkjet head 10 according to the present embodiment, compared with the inkjet head 1010, deformation of the side wall 33 forming the non-driven pressure chamber 312 on the other side of the air chamber 32 in the groove alignment direction is suppressed. It can be seen that the operation of the pressure chamber 311 has little effect on the pressure chamber 312 .

That is, in the inkjet head 10 according to the present embodiment, the air chambers 32 are made deeper than the pressure chambers 31, thereby suppressing transmission of vibration to the adjacent pressure chambers 31. FIG.

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.

For example, the shape of the cover portion 23 is not limited to the above embodiment, and can be changed as appropriate. For example, although the cover part 23 is partially arranged inside the air chamber 32 in the example, it is not limited to this, and the entire cover part 23 may be arranged outside the air chamber 32, for example. Also, the cover portion 23 may be a plate-shaped member along the side surface of the actuator member 22 .

For example, as another embodiment of the inkjet head 110 shown in FIGS. 11 to 14, the cover portion 230 is formed in a concave shape. FIG. 11 is a perspective view showing part of an inkjet head according to another embodiment, and FIG. 12 is a cross-sectional view showing an enlarged configuration of part of the inkjet head. 13 is a cross-sectional view of the inkjet head of FIG. 12 taken along line XIII-XIII, and FIG. 14 is a cross-sectional view of the inkjet head of FIG. 12 taken along line XIV-XIV.

The cover part 230 according to the present embodiment is a wall-shaped member that passes through the outside of the end of the side wall 33 in the extending direction of the air chamber 32 and closes the end of the air chamber 32, and is U-shaped or U-shaped. It has a bent part that bends to For example, the cover portion 230 includes a pair of extension walls 231 extending in the extension direction of the air chamber 32 and a connection wall 232 connecting the pair of extension walls 231. A slit is provided between the pair of extension walls 231. It is formed in a concave shape with a shaped air layer 321 . The cover portion 230 is made of a photosensitive resin material. For example, the cover portion 230 is molded into a predetermined shape by applying a photosensitive resin to both ends of the air chamber 32 and then curing the resin by exposure. The extension wall 231 of the cover portion 230 absorbs the deformation of the side wall 33 , thereby reducing crosstalk via the cover portion 230 . That is, by forming the cover portion 230 into a shape that makes it difficult for vibrations to be transmitted between the side walls 33, it is possible to increase the effect of damping vibrations.

In the above-described embodiment, an example in which the actuator member 22 having a plurality of grooves is arranged on the main surface portion 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.

Moreover, in the above-described embodiment, the actuator base 11 having the laminated piezoelectric member made of a plurality of piezoelectric bodies 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. 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 ink flows in from one side of the pressure chamber and flows out from the other side. is exemplified, but 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 ink may flow in from both sides. That is, the ink 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 . Moreover, the shapes of the cover portions 23 formed at both ends may be different from each other.

Further, for example, the liquid to be ejected is not limited to printing ink, 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 capable of ensuring 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 their modifications 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, 110... Inkjet head 11... Actuator base 12... Nozzle plate 13... Frame 17... Circuit board 18... Manifold 21... Substrate 22... Actuator member 23... Cover part 231... Extension wall, 232... Connection wall 321... Air layer 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 100 Inkjet printer 111 Housing 112 Medium supply unit 113 Image forming unit 114 Medium discharge unit 115 Conveying device 116 Control unit 117 Supporting unit 118 Conveying belt , 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, 271 ... first common room, 272 ... second common room.

Claims (5)

Piezoelectric bodies polarized in opposite directions are laminated, and on one side surface, a plurality of grooves forming a plurality of pressure chambers and a plurality of grooves adjacent to the pressure chambers and forming the pressure chambers are formed in a depth direction. an actuator member having a plurality of grooves forming a plurality of air chambers having a large dimension of and to which the bottom sides of the plurality of grooves are connected;
individual electrodes formed on inner surfaces including bottoms of the plurality of pressure chambers;
a common electrode formed on an inner surface including the bottoms of the plurality of air chambers;
a non-piezoelectric member arranged opposite to the one side surface of the actuator member;
a liquid ejection head. 2. The liquid ejection head according to claim 1, further comprising a cover portion that closes an end portion in an extending direction that intersects with the depth direction of a groove that constitutes the air chamber among the plurality of grooves. the actuator member comprises a plurality of sidewalls arranged between the plurality of pressure chambers and the plurality of air chambers;
3. The liquid ejection head according to claim 2, wherein said non-piezoelectric member is a nozzle plate having a plurality of nozzles communicating with said pressure chambers. The cover portion extends from an end portion of the pair of side walls constituting both sides of the air chamber in an extending direction that intersects the depth direction of the groove and the alignment direction of the plurality of grooves. a pair of extending walls each extending to the outside of the groove, and a connecting wall connecting the extending walls outside the end of the side wall, closing the end of the groove of the air chamber. The liquid ejection head according to claim 3. 5. The liquid ejection head according to any one of claims 1 to 4, wherein the plurality of piezoelectric bodies of the actuator member are laminated in the depth direction of the groove and polarized in opposite directions to each other in the lamination direction.