Liquid discharge head and liquid discharge device

Abstract

To provide a liquid discharge head and a liquid discharge device which can suppress manufacturing cost.SOLUTION: A liquid discharge head includes a flow channel member, one or more diaphragms, an actuator part, and a nozzle plate. The flow channel member forms a plurality of pressure chambers and a flow channel communicating with the pressure chambers. The diaphragm includes a vibration part arranged so as to face the pressure chambers, and is joined to the flow channel member, and forms a wall on a side opposite to the discharge side of the pressure chamber in an opposite direction. The actuator part is arranged so as to face the diaphragms, and generates a pressure in the pressure chamber. The nozzle plate is arranged on a side opposite to the diaphragms in the opposite direction of the flow channel member, and includes a plurality of nozzles for discharging droplets. When the flow channel member and the diaphragms are viewed in the opposite direction, the contour of the diaphragm includes a pressure chamber formation region where the plurality of pressure chambers are formed, and is smaller than the contour of the flow channel member.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In a liquid ejection head such as an inkjet head, a method is used in which a diaphragm is deformed by using an actuator composed of a piezoelectric material such as PZT (lead zirconate titanate), and the pressure chamber facing the diaphragm is deformed to eject ink from a nozzle communicating with the pressure chamber. The liquid ejection head includes a plurality of actuators, a diaphragm that transmits vibrations from the actuators, and a flow path portion that forms a plurality of pressure chambers facing the diaphragm and flow paths communicating with the pressure chambers. In such an inkjet head, since the diaphragm needs to efficiently transmit the vibrations of the actuator to the pressure chamber, it needs to be made very thin. In addition, since the diaphragm is in direct contact with the ink, it is necessary to use a material with excellent ink resistance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a liquid ejection head and a liquid ejection device capable of suppressing manufacturing costs.

Means for Solving the Problems

[0005] The liquid ejection head according to the embodiment includes a flow path member, one or more diaphragm plates, an actuator unit, and a nozzle plate. The flow path member forms a plurality of pressure chambers and flow paths communicating with the pressure chambers. The diaphragm plate includes a vibration portion disposed to face the pressure chamber and is joined to the flow path member, and forms a wall on the side opposite to the ejection side of the pressure chamber in the facing direction. The actuator unit is disposed to face the diaphragm plate and generates pressure in the pressure chamber. The nozzle plate is disposed on the side opposite to the diaphragm plate in the facing direction of the flow path member, and includes a plurality of nozzles for ejecting droplets. When the flow path member and the diaphragm plate are viewed in the facing direction, the outer shape of the diaphragm plate includes a pressure chamber formation region where the plurality of pressure chambers are formed, and is smaller than the outer shape of the flow path member.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 7

Figure 8

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Figure 11

Best Mode for Carrying Out the Invention

[0007] Hereinafter, an inkjet head 1 which is a liquid ejection head according to the first embodiment and an inkjet recording apparatus 100 which is a liquid ejection apparatus will be described with reference to FIGS. 1 to 6. FIG. 1 is a cross-sectional view showing a partial configuration of the inkjet head 1 according to the first embodiment, and FIG. 2 is a cross-sectional view showing a partial configuration of the inkjet head 1. FIG. 3 is a plan view showing a partial configuration of the inkjet head 1, and shows the arrangement relationship between the flow path member 40 and the diaphragm 30. FIG. 4 is an enlarged cross-sectional view showing a partial configuration of the inkjet head 1. FIG. 5 is a plan view showing a partial configuration of the inkjet head 1, and shows the arrangement of the flow path member 40 and the actuator unit 20. Arrows X, Y, and Z in the figure respectively indicate three mutually orthogonal directions. In the present embodiment, X is the arrangement direction of the nozzles 51 and the pressure chambers 31, Y is the extending direction, and Z is the opposing direction and along the axial direction of the nozzles. For the sake of explanation in each figure, the configuration is appropriately shown enlarged, reduced, or omitted.

[0008] As shown in FIGS. 1 to 6, the inkjet head 1 includes an actuator unit 20, a diaphragm 30, a flow path member 40 (flow path member) that forms a plurality of pressure chambers 31 and a first common liquid chamber 32, a nozzle plate 50 as a nozzle member having a plurality of nozzles 51, a manifold 60 as a common member that forms a second common liquid chamber 33, and a drive circuit 70. As an example, the inkjet head 1 shows an example in which, in the present embodiment, the vibration direction of the piezoelectric element 21 and the vibration direction of the diaphragm 30 are respectively along the Z direction. In the present embodiment, on the back side of the nozzle plate 50, a flow path structure portion that forms an ink flow path 35 (flow path portion) in the inkjet head 1 is configured by the diaphragm 30 and the flow path member 40. The inkjet head 1 is of a circulation type that circulates liquid in a predetermined flow path.

[0009] For example, the inkjet head 1 is a four-column integrated structure head having four actuator units 20 and four nozzle rows respectively. In the inkjet head 1, the positions of the nozzles 51 in the four nozzle rows are shifted to different positions in the parallel direction. That is, in the four actuator units 20, the positions of the driving piezoelectric elements 21 and the non-driving piezoelectric elements 22 are slightly different in the parallel direction, and are arranged at shifted positions, for example, by 1 / 4 times the pitch of the nozzles 51. For the sake of explanation, FIG. 4 shows a cross section cut at the position passing through the four rows of nozzles 51.

[0010] The plurality of actuator units 20 include, for example, driving piezoelectric elements 21 (piezoelectric parts) as a plurality of actuators formed of a piezoelectric member and arranged alternately along the column direction, and a plurality of non-driving piezoelectric elements 22. In the present embodiment, the nozzles 51 are provided facing the center in the extending direction of the actuator unit 20, and the actuator unit 20 has a symmetrical structure with one side and the other side centered on the nozzle 51. For example, the actuator unit 20 is joined to a rectangular base.

[0011] In the actuator unit 20, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are arranged in parallel in the parallel direction at regular intervals. As an example, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are all configured in a columnar shape of a rectangular parallelepiped with the same outer shape. The actuator unit 20 is divided into a plurality by, for example, a plurality of grooves 23, and the plurality of driving piezoelectric elements 21 and non-driving piezoelectric elements 22 are arranged in the column direction at the same pitch by grooves 23 having the same width, for example.

[0012] For example, in a plan view seen from the Z direction which is the axial direction of the nozzle 51, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are each configured in a rectangular shape such that the short side direction is along the column direction of the element row and the long side direction is along the extending direction (Y direction) of the pressure chamber 31 orthogonal to the column direction and the stacking direction (Z direction).

[0013] The drive piezoelectric element 21 is arranged at positions respectively facing a plurality of pressure chambers 31 formed in the flow path member 40 in the Z direction. As an example, the central positions of the drive piezoelectric element 21 in the column direction and the extending direction, and the central positions of the pressure chamber 31 in the column direction and the extending direction are arranged side by side in the Z direction.

[0014] The non-drive piezoelectric element 22 is arranged at positions respectively facing the wall portions formed in the flow path member 40 in the Z direction. As an example, the central positions of the non-drive piezoelectric element 22 in the column direction and the extending direction, and the central positions of the wall portions in the column direction and the extending direction are arranged side by side in the Z direction.

[0015] For example, the laminated piezoelectric member constituting the actuator unit 20 is formed by laminating and sintering sheet-like piezoelectric materials. The actuator unit 20 forms a plurality of piezoelectric elements formed in a rectangular columnar shape at predetermined intervals by dicing the laminated piezoelectric member from one end face to form a groove 23. Then, electrodes and the like are provided on the formed plurality of columnar elements, and a plurality of drive piezoelectric elements 21 and a plurality of non-drive piezoelectric elements 22 arranged alternately are formed. The plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22 are arranged alternately in parallel with the groove 23 interposed therebetween in the column direction.

[0016] The piezoelectric members constituting the drive piezoelectric element 21 and the non-drive piezoelectric element 22 are, for example, laminated piezoelectric bodies. The drive piezoelectric element 21 and the non-drive piezoelectric element 22 include a plurality of laminated piezoelectric layers 211, and internal electrodes 221 and 222 formed on the main surfaces of the respective piezoelectric layers 211. As an example, the drive piezoelectric element 21 and the non-drive piezoelectric element 22 have the same laminated structure. The drive piezoelectric element 21 and the non-drive piezoelectric element 22 include external electrodes 223 and 224 formed on the surface.

[0017] The piezoelectric layer 211 is composed of a piezoelectric material such as a PZT (lead zirconate titanate) - based or lead-free KNN (sodium potassium niobate) - based material.

[0018] The internal electrodes 221 and 222 are conductive films formed of a fired conductive material such as silver palladium into a predetermined shape. The internal electrodes 221 and 222 are respectively connected to the external electrodes 223 and 224 formed on the side surfaces of the piezoelectric elements 21 and 22.

[0019] The external electrodes 223 and 224 are formed on the surfaces of the plurality of drive piezoelectric elements 21 and the plurality of non-drive piezoelectric elements 22, and are configured by gathering the ends of the internal electrodes 221 and 222.

[0020] In this embodiment, as an example, the external electrode 223 is an individual electrode and the external electrode 224 is a common electrode. The individual external electrodes 223 and 224 are connected to the control unit 150 via the drive IC 72 of the drive circuit 70 and are configured to be drive controllable. Note that the arrangement of the common electrode and the individual electrode may be reversed.

[0021] The drive piezoelectric element 21 vibrates when a voltage is applied to the internal electrodes 221 and 222 via the external electrodes 223 and 224. In this embodiment, the drive piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration mentioned here is, for example, "vibration in the thickness direction defined by the piezoelectric constant d33". The drive piezoelectric element 21 displaces the diaphragm 30 and deforms the pressure chamber 31 by longitudinal vibration. That is, the actuator unit 20 is disposed opposite to the diaphragm 30 and generates pressure in the pressure chamber 31.

[0022] The diaphragm 30 extends along a plane orthogonal to the Z direction, which is the vibration direction, and is joined to one side of the piezoelectric layers 211 of the plurality of piezoelectric elements 21 and 22 in the vibration direction, that is, the surface on the nozzle plate 50 side. The diaphragm 30 faces the plurality of nozzles 51 via the pressure chamber 31 in the Z direction, which is the vibration direction. The diaphragm 30 is configured to be deformable, for example. The diaphragm 30 is joined to the drive piezoelectric element 21 and the non-drive piezoelectric element 22 of the actuator unit 20.

[0023] In the inkjet head 1 according to this embodiment, two diaphragm plates 30 are provided for the four columns of actuator units 20. That is, the inkjet head 1, in which a pressure chamber forming portion RA facing the diaphragm plate 30 is configured by two columns of actuator units 20 that are divided into two in the Y direction, has two pressure chamber forming portions RA. The pressure chamber forming portion RA is a region where one or a plurality of columns of the actuator units 20 facing one diaphragm plate 30 are arranged, and in this embodiment, it is a portion surrounded by two columns of actuator units 20.

[0024] For example, the diaphragm plate 30 is arranged to overlap one side in the stacking direction of the flow path member 40 and constitutes a part of the ink flow path 35. For example, the diaphragm plate 30 has a vibration region 301 facing the pressure chamber forming portion RA constituted by the actuator unit 20 and a support region 302 joined to the flow path member 40 at the outer peripheral portion of the vibration region 301. For example, the vibration region 301 forms a wall on the side opposite to the discharge side of the pressure chamber 31 in the facing direction.

[0025] For example, when viewed from the stacking direction (facing direction), the diaphragm plate 30 includes two pressure chamber forming portions RA arranged to face each other, and is configured to be larger than, for example, the pressure chamber forming portion RA. For example, the outer shape of the diaphragm plate 30 is larger than the region where the pressure chamber row is formed and smaller than the outer shape of the flow path member 40. Each diaphragm plate 30 is configured such that the width in the Y direction orthogonal to the Z direction is larger than the width of the pressure chamber forming portion RA including two pressure chamber rows, and the length in the X direction is also longer than the length in the X direction of the pressure chamber forming portion RA.

[0026] The diaphragm plate 30 is configured to be smaller than the flow path member 40 when viewed from the Z direction.

[0027] The vibration region 301 is, for example, in a flat plate shape arranged such that the thickness direction is the vibration direction of the piezoelectric layer 211. The diaphragm plate 30 extends in the plane direction in the arrangement direction of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22. The diaphragm plate 30 is, for example, a metal plate. The diaphragm plate 30 has a plurality of vibration sites facing each pressure chamber 31 and displaceable individually. The diaphragm plate 30 is formed such that the plurality of vibration sites are integrally continuous.

[0028] As an example, the diaphragm 30 is made of nickel or a SUS plate, and the thickness dimension along the vibration direction is configured to be about 5 μm to 15 μm. Note that in the vibration region 301, a plurality of vibration sites may have folds or steps formed between the vibration sites and adjacent sites or between adjacent vibration sites so that the vibration sites are easily displaced. The vibration region 301 deforms when the portion facing the drive piezoelectric element 21 is displaced by the expansion and contraction of the drive piezoelectric element 21. For example, since the diaphragm 30 is very thin and requires a complex shape, it is formed by an electroforming method or the like. The diaphragm 30 is joined to the upper end surface of the actuator unit 20 by adhesion or the like.

[0029] The support region 302 is a plate-like member that is disposed to face the flow path member 40 in the stacking direction.

[0030] The flow path member 40 is joined to one side of the diaphragm 30.

[0031] As shown in FIGS. 1 to 3, the flow path member 40 may be composed of an integral member, or may be composed of a plurality of stacked flow path substrates. For example, according to the viscosity of the ink, the volume to be discharged, etc., a plurality of flow path substrates 401, 402 having openings or grooves, a nozzle plate 50, and a diaphragm 30 are combined and joined to form a desired ink flow path 35. The plurality of flow path substrates 401, 402 are arranged to overlap in the stacking direction, and a predetermined ink flow path 35 including a connection flow path 34 and a pressure chamber 31 is constituted by the openings or grooves formed in each of the flow path substrates 401, 402. As an example, the flow path substrates 401, 402 are stacked in order from the diaphragm 30 side, and the flow path substrate 402 is disposed to face the nozzle plate 50.

[0032] The flow path member 40 is disposed between the nozzle plate 50 and the diaphragm 30. The flow path member 40 is formed by laminating and joining a plurality of flow path substrates, and has a plurality of pressure chambers 31, a common liquid chamber 32, and a plurality of connection flow paths 34 leading from the common liquid chamber 32 to the pressure chambers 31 inside, thereby forming a predetermined ink flow path 35 (liquid chamber). In other words, the flow path member 40 is composed of a plurality of laminated flow path substrates, and includes a peripheral wall portion surrounding the plurality of pressure chambers 31, the plurality of connection flow paths 34, (liquid chamber), a plurality of wall portions separating the rows of the plurality of pressure chambers 31, a plurality of wall portions separating the plurality of connection flow paths 34, and a peripheral wall portion forming the common liquid chamber 32.

[0033] As shown in FIGS. 1 and 2, the flow path member 40 is disposed opposite to the diaphragm 30 in the lamination direction and joined to the diaphragm 30. The flow path member 40 includes a plurality of flow path substrates 401, 402 having an outer shape larger than that of the diaphragm 30. Each of the flow path substrates 401, 402 is made of a metal material including SUS430 or a resin material such as silicon as an example. Openings for forming the pressure chambers 31, the connection flow paths 34, and the common liquid chamber 32 are respectively formed in the flow path substrates 401, 402. As an example, openings for forming the pressure chambers 31 and the common liquid chamber 32 are formed in one flow path substrate 401, and openings for forming the pressure chambers 31, the connection flow paths 34, and the common liquid chamber 32 are formed in the other flow path substrate 402.

[0034] That is, in the flow path member 40, the plurality of pressure chambers 31, the connection flow paths 34, and the common liquid chamber 32 are formed by the openings of the plurality of flow path substrates 401, 402 arranged and communicating in the lamination direction.

[0035] The plurality of pressure chambers 31 are spaces formed on one side of the vibration region 301 of the diaphragm 30, and each pressure chamber 31 communicates with a nozzle 51 formed in the nozzle plate 50. Further, the opposite side of the nozzle plate 50 is blocked by the diaphragm 30.

[0036] The plurality of pressure chambers 31 communicate with a common liquid chamber 32 via connection channels 34. The pressure chambers 31 hold the liquid supplied through the common liquid chamber 32 and the connection channels 34, and deform due to the vibration of the diaphragm 30 forming part of the pressure chambers 31, thereby discharging the liquid from the nozzles 51.

[0037] The common liquid chamber 32 is a channel that communicates with the ends of the plurality of connection channels 34 in the flow direction. For example, the common liquid chamber 32 is formed on both sides of the row of pressure chambers 31 by a channel member 40.

[0038] The connection channels 34 communicate the respective pressure chambers 31 with the common liquid chamber 32 and extend in the Y direction which is the flow direction. The connection channels 34 on both sides are configured to have a smaller dimension in the width direction orthogonal to the extending direction which is the flow direction than the common liquid chamber 32 and the pressure chambers 31, and the channel cross-section is configured to be narrow.

[0039] Here, a partition wall portion that separates the plurality of pressure chambers 31, a side wall portion that separates the plurality of connection channels 34, and a peripheral wall portion are formed by the portions other than the openings of the respective flow base plates 401, 402.

[0040] The nozzle plate 50 is configured as a rectangular plate with a thickness of about 10 μm to 100 μm made of a metal such as SUS·Ni or a resin material such as polyimide. The nozzle plate 50 is disposed on one side of the flow path member 40 so as to cover the opening on one side of the pressure chamber 31. The nozzle plate 50 has a plurality of nozzles 51 for discharging liquid droplets. The plurality of nozzles 51 are holes that penetrate the nozzle plate 50 in the thickness direction. A plurality of nozzles 51 are arranged in the same first direction as the arrangement direction of the pressure chambers 31, forming a nozzle row. Each nozzle 51 is provided at a position corresponding to the plurality of pressure chambers 31 respectively.

[0041] The manifold 60 is a structure arranged on the outer peripheral part of the actuator part 20. For example, the manifold 60 constitutes the outer contour of the inkjet head 1. Further, the manifold 60 may form a liquid flow path inside. The manifold 60 forms a second common liquid chamber 33 that communicates with the common liquid chamber 32 of the flow path member 40. For example, the manifold 60 is arranged on the outer peripheral part of the diaphragm 30 and has a frame-shaped frame part 61 that is joined to the flow path member 40.

[0042] In the present embodiment, the frame part 61 is not joined to the diaphragm 30. For example, the frame part 61 forms the second common liquid chamber 33. That is, the manifold 60 has a part that is not joined to the diaphragm 30.

[0043] The second common liquid chamber 33 is a space that communicates with the first common liquid chamber 32 formed in the flow path member 40. The common liquid chamber 33 is formed inside the frame part 61 and communicates with the pressure chamber 31 through the first common liquid chamber 32 and the connection flow path 34.

[0044] Note that the manifold 60 may have a part provided in a region such as between a pair of actuator parts 20 as an example. In that case, the diaphragm 30 has an opening connected to the common liquid chamber 33 flow path formed in the manifold and may be joined to the manifold 60.

[0045] The drive circuit 70 includes a wiring film having one end connected to the external electrodes 223 and 224, a driver IC mounted on the wiring film, and a printed wiring board mounted on the other end of the wiring film.

[0046] The drive circuit 70 drives the piezoelectric element 21 by applying a drive voltage to the external electrodes 223 and 224 by the driver IC, increases and decreases the volume of the pressure chamber 31, and discharges liquid droplets from the nozzle 51.

[0047] The wiring film is connected to a plurality of external electrodes 223 and 224. For example, the wiring film is an ACF (anisotropic conductive film) fixed to the connection portions of the external electrodes 223 and 224 by thermocompression bonding or the like. The wiring film is, for example, a COF (Chip on Film) on which a driver IC is mounted.

[0048] The driver IC is connected to the external electrodes 223 and 224 via the wiring film. Note that the driver IC may be connected to the external electrodes 223 and 224 by other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste), instead of the wiring film.

[0049] The driver IC generates control signals and drive signals for operating each piezoelectric element 21. The driver IC generates control signals for control such as selecting the timing of discharging ink and the piezoelectric element 21 for discharging ink according to the image signal input from the control unit 150 of the inkjet recording apparatus 100. Further, the driver IC generates a voltage to be applied to the piezoelectric element 21 according to the control signal, that is, a drive signal (electrical signal). When the driver IC applies the drive signal to the piezoelectric element 21, the piezoelectric element 21 drives the diaphragm 30 to be displaced and change the volume of the pressure chamber 31. As a result, the ink filled in the pressure chamber 31 generates a pressure vibration. Due to the pressure vibration, the ink is discharged from the nozzle 51 provided in the pressure chamber 31. Note that the inkjet head 1 may be configured to realize gradation expression by changing the amount of ink droplets landing on one pixel. Further, the inkjet head 1 may be configured to change the amount of ink droplets landing on one pixel by changing the number of times of discharging ink. In this way, the driver IC is an example of an application unit that applies the drive signal to the piezoelectric element 21.

[0050] For example, the driver IC includes a data buffer, a decoder, and a driver. The data buffer stores the printing data for each piezoelectric element 21 in time series. The decoder controls the driver based on the printing data stored in the data buffer for each piezoelectric element 21. The driver outputs a drive signal for operating each piezoelectric element 21 based on the control of the decoder. The drive signal is, for example, a voltage applied to each piezoelectric element 21.

[0051] The printed wiring board is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted. The printed wiring board is connected to the control unit 150 of the inkjet recording apparatus 100.

[0052] In the inkjet head 1 configured as described above, a plurality of pressure chambers 31 communicating with the nozzles 51, connection channels 34 respectively communicating in the extending direction of the plurality of pressure chambers 31, and a common liquid chamber 32 that is part of the common channel are formed by the nozzle plate 50, the manifold 60, the channel member 40, and the diaphragm 30. The connection channels 34 are arranged on both sides of the pressure chamber 31 in the extending direction, and the common liquid chamber 32 is arranged continuously at the extending ends of the plurality of connection channels 34 on both sides.

[0053] The inkjet head 1 is of a circulating type. For example, the common liquid chamber 32 communicates with the cartridge, and the ink is supplied to each pressure chamber 31 through the common liquid chamber 32 on the inflow side. All the piezoelectric elements 21 are connected by wiring so that a voltage can be applied. In the inkjet head 1, when the control unit 150 applies a drive voltage to the electrodes 221 and 222 by the driver IC, the piezoelectric element 21 to be driven vibrates in the stacking direction, that is, in the thickness direction of each piezoelectric layer 211. That is, the piezoelectric element 21 vibrates longitudinally.

[0054] Specifically, the control unit 150 applies a driving voltage to the internal electrodes 221 and 222 of the piezoelectric element 21 to be driven, thereby selectively driving the piezoelectric element 21 to be driven. Then, by combining the deformation in the tensile direction and the deformation in the compression direction caused by the piezoelectric element 21 to be driven, the diaphragm 30 is deformed, and the volume of the pressure chamber 31 is changed, so as to guide the liquid from the first common liquid chamber 32 and discharge it from the nozzle 51.

[0055] The ink supplied to the pressure chamber 31 is discharged from the nozzle 51, and is also recovered into the cartridge through the other connection flow path 34 on the recovery side and the common liquid chamber 32.

[0056] In the inkjet head 1, with one side in the extending direction as the inflow side (supply side) and the other side as the outflow side (recovery side), the ink circulates in the ink flow path 35.

[0057] Hereinafter, an example of an inkjet recording apparatus 100 including the inkjet head 1 will be described with reference to FIG. 6. The inkjet recording apparatus 100 includes a housing 111, a medium supply unit 112, an image forming unit 113, a medium discharge unit 114, a conveyance device 115, and a control unit 150.

[0058] The inkjet recording apparatus 100 is a liquid discharge apparatus that performs an image forming process on the paper P by discharging a liquid such as ink while conveying the paper P as a printing medium to be discharged along a predetermined conveyance path A from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114.

[0059] The housing 111 constitutes the outer shell of the inkjet recording apparatus 100. A discharge port for discharging the paper P to the outside is provided at a predetermined position of the housing 111.

[0060] 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.

[0061] The medium discharge unit 114 includes a paper discharge tray configured to be able to hold the paper P discharged from the discharge port.

[0062] The image forming unit 113 includes a support unit 117 that supports the sheet P, and a plurality of head units 130 disposed to face the upper side of the support unit 117.

[0063] The support unit 117 includes a conveyance belt 118 provided in a loop shape in a predetermined region where image formation is performed, a support plate 119 that supports the conveyance belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyance belt 118.

[0064] During image formation, the support unit 117 supports the sheet P on the holding surface which is the upper surface of the conveyance belt 118, and conveys the sheet P to the downstream side by sending the conveyance belt 118 at a predetermined timing by the rotation of the belt roller 120.

[0065] The head unit 130 includes a plurality (4 colors) of inkjet heads 1, ink tanks 132 as liquid tanks respectively mounted on each inkjet head 1, a connection path 133 that connects the inkjet head 1 and the ink tank 132, and a supply pump 134.

[0066] In the present embodiment, there are provided four inkjet heads 1 of cyan, magenta, yellow, and black, and ink tanks 132 that respectively store the inks of these colors. The ink tanks 132 are connected to the inkjet heads 1 by connection paths 133.

[0067] Also, a negative pressure control device such as a pump (not shown) is connected to the ink tank 132. Then, corresponding to the head values of the inkjet head 1 and the ink tank 132, the inside of the ink tank 132 is negatively pressure-controlled by the negative pressure control device, so that the ink supplied to each nozzle 51 of the inkjet head 1 forms a meniscus of a predetermined shape.

[0068] The supply pump 134 is a liquid transfer pump composed of, for example, a piezoelectric pump. The supply pump 134 is provided in the supply flow path. The supply pump 134 is connected to the drive circuit of the control unit 150 by wiring and is configured to be controllable under the control of a CPU (Central Processing Unit). The supply pump 134 supplies liquid to the inkjet head 1.

[0069] The conveyance device 115 conveys the paper P along a conveyance path A that extends from the medium supply unit 112 through the image forming unit 113 to the medium discharge unit 114. The conveyance device 115 includes a plurality of pairs of guide plates 121 arranged along the conveyance path A and a plurality of conveyance rollers 122.

[0070] Each of the plurality of pairs of guide plates 121 includes a pair of plate members that are arranged opposite to each other with the conveyed paper P therebetween and guides the paper P along the conveyance path A.

[0071] The conveyance roller 122 is driven to rotate under the control of the control unit 150, thereby sending the paper P downstream along the conveyance path A. Note that sensors for detecting the conveyance state of the paper are arranged at various positions in the conveyance path A.

[0072] The control unit 150 includes a control circuit 151 such as a CPU which is a controller, a ROM (Read Only Memory) that stores various programs and the like, a RAM (Random Access Memory) that temporarily stores various variable data, image data, and the like, and an interface unit that inputs data from the outside and outputs data to the outside.

[0073] In the inkjet recording apparatus 100 configured as described above, when the control unit 150 detects a print instruction by the operation of the operation input unit at the interface, for example, it drives the conveyance device 115 to convey the paper P and outputs a print signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 1. As a discharge operation, the inkjet head 1 sends a drive signal to the driver IC according to an image signal corresponding to the image data, applies a drive voltage to the internal electrodes 221 and 222, selectively drives the piezoelectric element 21 to be discharged, vibrates vertically in the stacking direction, changes the volume of the pressure chamber 31, discharges the ink from the nozzle 51, and forms an image on the paper P held on the conveyance belt 118. Further, as a liquid discharge operation, the control unit 150 drives the supply pump 134 to supply ink from the ink tank 132 to the common liquid chamber 32 of the inkjet head 1.

[0074] Here, the drive operation for driving the inkjet head 1 will be described. The inkjet head 1 according to the present embodiment includes piezoelectric elements 21 disposed opposite to the pressure chamber 31, and these piezoelectric elements 21 are connected by wiring so that a voltage can be applied. The control unit 150 sends a drive signal to the driver IC according to an image signal corresponding to the image data, applies a drive voltage to the internal electrodes 221 and 222 of the piezoelectric element 21 to be driven, and selectively deforms the piezoelectric element 21 to be driven. Then, by combining the deformation in the tensile direction and the deformation in the compression direction of the diaphragm 30, the volume of the pressure chamber 31 is changed to discharge the liquid.

[0075] For example, the control unit 150 alternately performs a pulling operation and a compressing operation. In the inkjet head 1, when pulling to increase the internal volume of the target pressure chamber 31, the piezoelectric element 21 to be driven is contracted, and the driving piezoelectric elements other than the driving target are not deformed. Further, when compressing to decrease the internal volume of the target pressure chamber 31 in the inkjet head 1, the target driving piezoelectric element 21 is extended, and the non-driving piezoelectric element 22 is not deformed.

[0076] According to the inkjet head 1 and the inkjet recording apparatus 100 according to the above-described embodiment, the diaphragm 30 is made larger than the pressure chamber forming portion RA, which is the portion forming the pressure chamber, and smaller than the outer shape of the flow path member 40. Since the diaphragm 30 needs to efficiently transmit the vibration of the actuator to the pressure chamber, it needs to be very thin, and since it is a portion directly in contact with the ink, it is necessary to use a material such as palladium that has excellent ink resistance. Although expensive members are used, the structure is such that it is used only around the pressure chamber of the plate forming the pressure chamber, and the other portions are covered with separate members, thereby reducing the usage rate of expensive members and reducing the product cost. Also, by reducing the size of the diaphragm, it is possible to arrange it so as not to be joined to members such as a cover and a manifold that may be subjected to large stress.

[0077] Further, when there are a plurality of pressure chamber rows 310 and actuator portions 20, by dividing the diaphragm 30 into a plurality of pieces and arranging them oppositely, it becomes possible to further suppress the usage amount of the diaphragm 30 members. On the other hand, by using a common diaphragm 30 in the column direction, alignment is easier and manufacturing is easier compared to a configuration in which the diaphragms 30 are arranged for each individual pressure chamber 31, for example.

[0078] Note that the present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof.

[0079] For example, in the above-described embodiment, an example in which four rows of actuator portions and pressure chamber rows 310 are arranged is shown, but the present invention is not limited thereto. For example, the nozzles 51 and the pressure chambers 31 may have three rows or less, or five rows or more. Also, in the above-described first embodiment, an example in which two diaphragms 30 are provided for two rows out of four rows of actuator portions 20 is shown, but the present invention is not limited thereto.

[0080] [Second Embodiment] Next, the configuration of the inkjet head 1010 according to the second embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is an explanatory diagram showing the configuration of the diaphragm 30 and the flow path member 40 of the inkjet head 1010, and shows the arrangement of the flow path member 40 and the diaphragm 30. FIG. 8 is a cross-sectional view showing a part of the configuration of the inkjet head 1010. For example, the inkjet head 1010 according to the second embodiment includes one diaphragm 30 for four rows of actuator units 20 and pressure chamber rows 310. The inkjet head 1010 of the present embodiment is a four-row integrated structure head having four rows each of actuator units 20 and nozzle rows. In the inkjet head 1010, the positions of the nozzles 51 in the four nozzle rows are shifted to different positions in the parallel direction. That is, in the four rows of actuator units 20, the positions of the drive piezoelectric elements 21 and the non-drive piezoelectric elements 22 are arranged at slightly different positions in the parallel direction. For the sake of explanation, FIG. 8 shows a cross section cut at the positions passing through the four rows of nozzles 51.

[0081] In the inkjet head 1010, one diaphragm 30 is provided for the four rows of actuator units 20. That is, the pressure chamber forming portion RB facing the diaphragm 30 is constituted by the four actuator units 20, and the inkjet head 1 has one pressure chamber forming portion RB.

[0082] For example, the diaphragm 30 is arranged to overlap on one side in the stacking direction of the flow path member 40 and constitutes a part of the ink flow path 35. For example, the diaphragm 30 has a vibration region 301 facing the pressure chamber forming portion RB constituted by the actuator unit 20, and a support region 302 joined to the flow path member 40 at the outer peripheral portion of the vibration region 301. For example, the vibration region 301 forms a wall on the side opposite to the discharge side of the pressure chamber 31 in the facing direction.

[0083] For example, the diaphragm 30 is configured to be larger than the pressure chamber forming portions RB arranged opposite to each other when viewed from the stacking direction. That is, the diaphragm 30 is configured to be smaller than the flow path member 40 when viewed from the Z direction. For example, the outer shape of the diaphragm 30 is larger than the region where the pressure chamber rows are formed and smaller than the outer shape of the flow path member 40. Each diaphragm 30 is configured such that the width in the Y direction orthogonal to the Z direction is larger than the width of the pressure chamber forming portion RA having two pressure chamber rows, and the length in the X direction is also longer than the length in the X direction of the pressure chamber forming portion RB.

[0084] Other configurations are the same as those of the inkjet head 1 of the first embodiment.

[0085] Also in this embodiment, by making the diaphragm 30 larger than the pressure chamber forming portion RA which is the portion forming the pressure chamber and smaller than the outer shape of the flow path member 40, the usage rate of expensive members is reduced, and the product cost can be reduced.

[0086] [Third Embodiment] Hereinafter, the configuration of the inkjet head 1020 according to the third embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is an explanatory diagram showing a partial configuration of the inkjet head 1020, and FIG. 10 is a cross-sectional view showing a partial configuration of the inkjet head 1020. As shown in FIGS. 9 and 10, the inkjet head 1020 includes four diaphragms 30 for four rows of actuator portions 20 and pressure chamber rows 310, and one diaphragm 30 is provided for each row. The inkjet head 1020 of this embodiment is a four-row integrated structure head having four rows each of actuator portions 20 and nozzle rows. In the inkjet head 1020, the positions of the nozzles 51 in the four rows of nozzle rows are shifted to different positions in the parallel direction. That is, in the four rows of actuator portions 20, the positions of the driving piezoelectric elements 21 and the non-driving piezoelectric elements 22 are arranged at slightly different positions in the parallel direction.

[0087] In the inkjet head 1020, four diaphragm plates 30 are provided for the four columns of actuator units 20. That is, the inkjet head 1, in which a pressure chamber forming portion RC facing the diaphragm plate 30 is configured by one actuator unit 20, has four pressure chamber forming portions RC.

[0088] For example, the diaphragm plate 30 is disposed so as to overlap one side in the stacking direction of the flow path member 40 and constitutes a part of the ink flow path 35. For example, the diaphragm plate 30 has a vibration region 301 facing the pressure chamber forming portion RC constituted by the actuator unit 20, and a support region 302 joined to the flow path member 40 at the outer peripheral portion of the vibration region 301. For example, the vibration region 301 forms a wall on the side opposite to the discharge side of the pressure chamber 31 in the facing direction.

[0089] For example, when viewed from the stacking direction, the diaphragm plate 30 is configured to be larger than the pressure chamber forming portions RC arranged opposite to each other. That is, when viewed from the Z direction, the diaphragm plate 30 is configured to be smaller than the flow path member 40. For example, the outer shape of the diaphragm plate 30 is larger than the region where the pressure chamber rows are formed and smaller than the outer shape of the flow path member 40. Each diaphragm plate 30 is configured such that the width in the Y direction orthogonal to the Z direction is larger than the width of the pressure chamber forming portion RC including one pressure chamber row, and the length in the X direction is also longer than the length in the X direction of the pressure chamber forming portion RC.

[0090] Further, the diaphragm plate 30 is not joined to the frame portion 61 of the manifold 60 and does not face the common liquid chamber 33 formed in the frame portion 61. For example, the outer peripheral edge 303 of the diaphragm plate 30 is disposed at a distance from the frame portion 61.

[0091] In the present embodiment, the frame portion 61 is not joined to the diaphragm plate 30. For example, the frame portion 61 forms the second common liquid chamber 33. That is, the manifold 60 has a portion that is not joined to the diaphragm plate 30. Other configurations are the same as those of the first embodiment and the second embodiment.

[0092] Note that the manifold 60 may, in some cases, have a portion provided not only in the outer peripheral frame portion 61 but also in a region such as between the pair of actuator portions 20. In that case, the diaphragm 30 may have an opening connected to the common liquid chamber 33 flow path formed in the manifold and may be joined to the manifold 60.

[0093] Also in this embodiment, the diaphragm 30 is larger than the pressure chamber forming portion RA which is the portion forming the pressure chamber, smaller than the outer shape of the flow path member 40, reducing the usage rate of expensive members and lowering the product cost. Further, although the diaphragm is a thin film member and there is a risk of breakage when joined to a portion where a large stress is applied, the diaphragm 30 is joined to the flow path member 40 but is arranged not to be joined to the frame portion 61 forming the common liquid chamber 33. Since the diaphragm 30 is joined only to the actuator portion 20 other than the flow path member 40, it is possible to avoid applying a large stress and prevent breakage.

[0094] [Fourth Embodiment] Hereinafter, the configuration of the inkjet head 1020 according to the fourth embodiment will be described with reference to FIG. 11. For example, in the first embodiment described above, an example was shown in which the outer peripheral edge 303 of the diaphragm 30 is disposed inside the frame portion 61, but the present invention is not limited thereto. As a fourth embodiment, as shown in FIG. 11, for example, the diaphragm 30 and the manifold 60 may be disposed so as to partially overlap in the stacking direction. For example, in the inkjet head 1030 shown in FIG. 11 as the fourth embodiment, the outer peripheral edge 303 of the diaphragm 30 is disposed so as to partially overlap the manifold 60. A relief groove 601 for disposing the outer peripheral edge 303 of the diaphragm 30 is formed in the manifold 60. That is, a step is formed in the manifold 60 so that there is no step between the diaphragm 30 and the flow path member 40 and no leakage occurs. According to the present embodiment, the manifold 60 has a relief groove 601 which is a concave portion in which at least a part of the manifold 60 overlaps the diaphragm 30 in the stacking direction and in which a part of the diaphragm 30 is disposed. When the diaphragm 30 partially overlaps the manifold 60 as shown in FIG. 11, the bonding margin of the relief groove 601 between the manifold 60 and the diaphragm 30 is formed, and the manifold 60 and the diaphragm 30 are joined. According to the present embodiment, leakage due to interference between the manifold 60 and the diaphragm 30 can also be avoided.

[0095] For example, the specific configuration of the flow path member 40 is not limited to the above. For example, the flow path substrate may be composed of one member, or may be three or more members. Further, the shape of the opening in each flow path substrate is not limited to the above embodiment.

[0096] For example, in the fourth embodiment, an example where the diaphragm 30 partially overlaps with the manifold 60 as shown in FIG. 11 is shown, but the present invention is not limited to this. When the outer peripheral edge 303 of the diaphragm 30 does not overlap with the manifold 60, a relief groove 601 that retreats from the diaphragm 30 side may be formed in a part of the manifold 60. In this case, design errors can be tolerated and the design can be improved. Also, in the fourth embodiment, an example where the part where the diaphragm 30 partially overlaps with the manifold 60 is both end portions in the X direction or the Y direction is shown, but the present invention is not limited to this. For example, a configuration where any one of the edges in the X direction or the Y direction overlaps may be used.

[0097] For example, in the above embodiment, a configuration is adopted in which a plurality of layers of piezoelectric members are laminated and the piezoelectric element 21 is driven using longitudinal vibration (d33) in the lamination direction, but the present invention is not limited to this. For example, it is also applicable to a form in which the piezoelectric element 21 is composed of a single-layer piezoelectric member, and is also applicable to a form driven by transverse vibration (d31).

[0098] Also, the specific configurations of the piezoelectric elements 21 and 22, the shape of the flow path, and the configurations and positional relationships of various components including the flow path member 40, the nozzle plate 50, and the manifold 60 are not limited to the examples described above, and can be changed as appropriate. Also, the arrangement of the nozzles 51 and the pressure chambers 31 is not limited to the above. For example, two or more rows of nozzles 51 may be arranged. Also, a dummy chamber may be formed between a plurality of pressure chambers 31.

[0099] Also, the liquid to be discharged is not limited to the ink for printing, and for example, an apparatus that discharges a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be used.

[0100] Also, in the above embodiment, an example where the inkjet head 1 is used in a liquid discharge apparatus such as an inkjet recording apparatus is shown, but the present invention is not limited to this. For example, it can also be used in a 3D printer, an industrial manufacturing machine, and medical applications, and can be made smaller, lighter, and less costly.

[0101] According to at least one embodiment described above, cost reduction is possible.

[0102] In addition, although several embodiments of the present invention have been described, these embodiments are presented as examples 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 changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0103] 1, 1010, 1020, 1030... inkjet heads, 20... actuator section, 21... drive piezoelectric element, 22... non-drive piezoelectric element, 23... groove, 30... diaphragm, 31... pressure chamber, 32... first common liquid chamber, 33... second common liquid chamber, 34... connection flow path, 35... ink flow path, 40... flow path member, 50... nozzle plate, 51... nozzle, 60... manifold, 61... frame section, 70... drive circuit, 100... inkjet recording apparatus, 111... housing, 112... medium supply section, 113... image forming section, 114... medium discharge section, 115... conveyance device, 117... support section, 118... conveyance belt, 119... support plate, 120... belt roller, 121... pair of guide plates, 122... conveyance roller, 130... head unit, 132... ink tank, 133... connection path, 134... supply pump, 150... control section, 151... control circuit, 211... piezoelectric layer, 221... internal electrode 222... internal electrode, 223... external electrode, 224... external electrode, 301... vibration region, 302... support region, 303... outer peripheral edge, 310... pressure chamber row, 401... flow path substrate, 402... flow path substrate, 601... relief groove.

Claims

1. A flow path member that forms a plurality of pressure chambers and flow paths communicating with the pressure chambers, One or more diaphragm plates that are provided with a vibration part arranged to face the pressure chamber and are joined to the flow path member, and form a wall on the opposite side of the discharge side of the pressure chamber in the facing direction, An actuator part that is arranged to face the diaphragm plate and generates pressure in the pressure chamber, A nozzle plate that is arranged on the opposite side of the diaphragm plate in the facing direction of the flow path member and includes a plurality of nozzles for discharging droplets, A liquid discharge head in which, when the flow path member and the diaphragm plate are viewed in the facing direction, the outer shape of the diaphragm plate includes a pressure chamber formation region where the plurality of pressure chambers are formed and is smaller than the outer shape of the flow path member.

2. A common member that is arranged to face one side in the facing direction of the flow path member, forms a common liquid chamber communicating with the plurality of pressure chambers, and has a frame part arranged on the outer peripheral part of the diaphragm plate, The liquid discharge head according to claim 1, wherein the diaphragm plate is not joined to the frame part of the common member.

3. A common member that is arranged to face the flow path member and forms a common liquid chamber communicating with the plurality of pressure chambers, The liquid discharge head according to claim 1, wherein the common member has a recess where at least a part of the outer peripheral edge of the diaphragm plate overlaps in the lamination direction of the flow path member and the diaphragm plate, and the outer peripheral edge of the diaphragm plate is arranged.

4. The liquid discharge head according to claim 1, wherein the pressure chamber formation region is a region where one or a plurality of rows of actuator parts facing one diaphragm plate are arranged.

5. A liquid discharge device including the liquid discharge head according to any one of claims 1 to 4.

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