Liquid discharge head and liquid discharge apparatus

Abstract

A liquid ejection head and a liquid ejection apparatus having high mountability are disclosed. One embodiment relates to a liquid ejection head including a piezoelectric member, electrodes, and a wiring substrate. The piezoelectric member includes a plurality of piezoelectric elements formed of a piezoelectric material. The plurality of electrodes are formed on the piezoelectric elements. The wiring substrate is joined to the electrodes by solder. A melting point of the solder is 1 / 2 or less of a Curie point of the piezoelectric material.

Description

Technical Field

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

[0002] Piezoelectric actuators using piezoelectric materials such as PZT are used as drive sources for liquid ejection devices such as inkjet printer heads. In inkjet printer heads, it is known that multiple slots are formed in the piezoelectric material at fine intervals, and the actuator is constructed using segmented columnar elements. Although wiring is used to drive such actuators, it is difficult to apply high pressure during mounting due to the precision and fragility of the columnar piezoelectric elements. Therefore, the use of solder for mounting has been considered, but heating during mounting can lead to degradation of the piezoelectric material. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a liquid nozzle and a liquid spraying device with high installability.

[0004] One embodiment of the liquid ejector head includes a piezoelectric component, electrodes, and a wiring substrate. The piezoelectric component includes a plurality of piezoelectric elements formed of a piezoelectric material. A plurality of electrodes are formed on the piezoelectric elements. The wiring substrate is bonded to the electrodes by solder. The melting point of the solder is less than half the Curie point of the piezoelectric material.

[0005] One embodiment of the liquid ejection device includes the liquid ejection head described above. Attached Figure Description

[0006] Figure 1 This is a cross-sectional view showing the configuration of the inkjet head according to the embodiment.

[0007] Figure 2 This is a cross-sectional view showing the configuration of the same inkjet head.

[0008] Figure 3 This is a cross-sectional view showing a portion of the configuration of an FPC with the same inkjet head.

[0009] Figure 4 This is an explanatory diagram showing the correspondence between the types of solder and their melting points.

[0010] Figure 5 This is an explanatory diagram showing the manufacturing method of the same inkjet head.

[0011] Figure 6 This is an explanatory diagram showing the schematic configuration of the inkjet recording apparatus according to the embodiment.

[0012] Explanation of reference numerals in the attached figures

[0013] 1…Inkjet head, 10…Substrate, 20…Actuator section, 201…Layered piezoelectric components, 21…Driven piezoelectric element, 22…Non-driven piezoelectric element, 23…Gate, 26…Connection section, 30…Vibrating plate, 31…Pressure chamber, 32…Common chamber, 33…Connecting section, 34…Guide flow path, 35…Ink flow path, 40…Flow path components, 41…Peripheral wall section, 42…Partition wall section, 43…Guide wall, 50…Nozzle plate, 51…Nozzle, 60…Frame section, 70…Driver circuit, 71…FPC, 72…Driver IC, 73…Printed wiring board, 731…Head control circuit, 100…Inkjet recording device, 111…Housing, 112…Media supply unit, 113…Image forming unit, 114…Media discharge unit, 115…Conveying device, 117…Support unit, 118…Conveyor belt, 119…Support plate, 120…Belt roller, 121…Guide plate pair, 122…Conveying roller, 130…Head unit, 132…Ink cartridge, 133…Connecting flow path, 134…Supply pump, 116…Control unit, 1161…Control circuit, 211…Piezoelectric layer, 212…Dummy layer, 221…Internal electrode, 222…Internal electrode, 223…External electrode, 224…External electrode, 301…Vibration area, 302…Support area, 405…Flow path substrate. Detailed Implementation

[0014] The following is for reference Figures 1 to 6 The liquid ejection head, i.e., inkjet head 1, and the liquid ejection device, i.e., inkjet recording device 100, involved in the embodiments will be described. Figure 1 as well as Figure 2 This is a cross-sectional view showing the schematic configuration of the inkjet head 1. Figure 3 This is a cross-sectional view showing a partial configuration of the FPC. Figure 4 This is an explanatory diagram showing the correspondence between the types of solder and their melting points. Figure 5 This is an explanatory diagram showing the manufacturing method of the inkjet head. Figure 6 This is an explanatory diagram showing the schematic configuration of the inkjet recording device 100. Arrows X, Y, and Z in the diagram indicate three mutually orthogonal directions. For ease of explanation, the configuration has been appropriately enlarged, reduced, or omitted in each diagram.

[0015] like Figure 1 as well as Figure 2As shown, the inkjet head 1 includes a substrate 10, an actuator section 20, a flow path component 40, a nozzle plate 50 having multiple nozzles 51, a frame section 60 as a structural section, and a drive circuit 70. As an example, the inkjet head 1 includes two actuator sections 20 and two rows each of nozzle rows (X-direction) with multiple nozzles 51 arranged in a column direction, pressure chamber rows (X-direction) with multiple pressure chambers 31 arranged in a column direction, and element rows (X-direction) with multiple piezoelectric elements 21 and 22 arranged in a column direction. In this embodiment, an example is shown where the stacking direction of the multiple piezoelectric layers 211, the vibration direction of the piezoelectric elements 21, and the vibration direction of the vibrating plate 30 are all along the Z-direction.

[0016] The actuator section 20 is engaged with one side of the base 10. The actuator section 20 is, for example, disposed on the base 10. For example, two actuator sections 20 are arranged in a Y-direction. It should be noted that... Figure 1 , Figure 2 Only one actuator section 20 is shown in the image.

[0017] The actuator section 20 includes, for example, a plurality of driven piezoelectric elements 21 and a plurality of non-driven piezoelectric elements 22, which are composed of piezoelectric components and are arranged alternately along the column direction, and a connecting section 26 that integrally connects the plurality of piezoelectric elements 21 and 22 on the substrate 10 side.

[0018] In the actuator section 20, a plurality of driven piezoelectric elements 21 and a plurality of non-driven piezoelectric elements 22 are arranged in one direction at a certain interval.

[0019] As an example, the multiple driven piezoelectric elements 21 and the multiple non-driven piezoelectric elements 22 are all configured as cuboid columns with the same shape. The actuator section 20 is divided into multiple parts by multiple slots 23, and all the multiple driven piezoelectric elements 21 and non-driven piezoelectric elements 22 are arranged in the column direction with the same spacing through slots 23 of the same width.

[0020] For example, when a groove 23 is formed from one side of the stacked piezoelectric component 201 in the Z direction, the depth of the groove 23 is set to be shorter than the total length of the stacked piezoelectric component 201 in the Z direction, leaving a connecting portion 26, thereby enabling a shape in which one end is divided into multiple parts and the other end is connected.

[0021] For example, when viewed from above in the Z direction, the multiple driven piezoelectric elements 21 and the multiple non-driven piezoelectric elements 22 are respectively configured as rectangles with the short side direction along the column direction of the element column and the long side direction along the extension direction orthogonal to the column direction and the Z direction.

[0022] The drive piezoelectric elements 21 are arranged in the Z direction at positions opposite to the plurality of pressure chambers 31 formed in the flow path component 40. As an example, the center positions of the drive piezoelectric elements 21 in the column direction and the center positions of the pressure chambers 31 in the column direction and the extension direction are arranged in the Z direction.

[0023] The non-driven piezoelectric elements 22 are arranged in the Z direction at positions opposite to the plurality of partition portions 42 formed on the flow path member 40. As an example, the center positions of the column direction and the extension direction of the driven piezoelectric elements 21 and the center positions of the column direction and the extension direction of the partition portions 42 are arranged in the Z direction.

[0024] For example, the actuator section 20 pre-cuts a groove 23 from the end face opposite to the substrate 10 by cutting a stacked piezoelectric component that is bonded to the substrate 10. This forms a plurality of rectangular columnar piezoelectric elements at predetermined intervals. Furthermore, a plurality of driven piezoelectric elements 21 and a plurality of non-driven piezoelectric elements 22, which are provided with electrodes and arranged alternately, are formed on the formed columnar elements. The plurality of driven piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22 are arranged alternately side-by-side in the column direction, sandwiching the groove 23.

[0025] For example, the stacked piezoelectric component constituting the actuator section 20 is formed by stacking and sintering sheet-like piezoelectric materials.

[0026] The piezoelectric components constituting the driven piezoelectric element 21 and the non-driven piezoelectric element 22 are, for example, stacked piezoelectric components 201. The driven piezoelectric element 21 and the non-driven piezoelectric element 22 each have multiple stacked piezoelectric layers 211 and internal electrodes 221, 222 formed on the main surface of each piezoelectric layer 211. It should be noted that, as an example, the driven piezoelectric element 21 and the non-driven piezoelectric element 22 have the same stacked structure. Furthermore, the driven piezoelectric element 21 and the non-driven piezoelectric element 22 each have external electrodes 223, 224 formed on their surfaces.

[0027] The piezoelectric layer 211 is formed into a thin plate shape, for example, from a PZT (lead zirconate titanate) based or lead-free KNN (sodium potassium niobate) based piezoelectric ceramic material. Multiple piezoelectric layers 211 are stacked with their thickness direction along the stacking direction and bonded together. For example, in this embodiment, the thickness direction and stacking direction of the piezoelectric layers 211 are arranged along the vibration direction (Z direction).

[0028] The internal electrodes 221 and 222 are conductive films of a predetermined shape formed from conductive materials such as silver and palladium that can be sintered. The internal electrodes 221 and 222 are formed in predetermined areas on the main surface of each piezoelectric layer 211. The internal electrodes 221 and 222 are mutually distinct electrodes. For example, in the direction orthogonal to both the arrangement direction (X-direction) and the vibration direction (Z-direction) of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22, i.e., the extension direction (Y-direction), one internal electrode 221 is formed in a region reaching one end of the piezoelectric layer 211 but not reaching the other end. The other internal electrode 222 is formed in the extension direction in a region reaching the other end of the piezoelectric layer 211 but not reaching the other end. The internal electrodes 221 and 222 are respectively connected to external electrodes 223 and 224 formed on the sides of the piezoelectric elements 21 and 22.

[0029] Furthermore, the stacked piezoelectric component 201 constituting the driving piezoelectric element 21 and the non-driving piezoelectric element 22 also includes a dummy layer 212 at either or both of its ends on the substrate 10 side and the nozzle plate 50 side. The dummy layer 212 is made of the same material as the piezoelectric layer 211, for example. Since it has an electrode on only one side, it does not form an electric field and therefore does not deform. For example, the dummy layer 212 does not function as a piezoelectric element, but rather serves as a base for fixing the actuator part 20 to the substrate 10 or is worn away during or after assembly to meet precision requirements.

[0030] External electrodes 223 and 224 are formed on the surfaces of the plurality of driven piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22, and are configured such that the ends of the internal electrodes 221 and 222 are concentrated. For example, external electrodes 223 and 224 are formed on one end face and the other end face in the extension direction of the piezoelectric layer 211, respectively. External electrodes 223 and 224 are deposited using known methods such as plating or sputtering with Ni, Cr, Au, etc. External electrodes 223 and 224 are different electrodes. External electrodes 223 and 224 are respectively disposed on different side faces of the plurality of driven piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22.

[0031] In this embodiment, as an example, the external electrode 223 is used as a separate electrode, and the external electrode 224 is used as a common electrode. The external electrode 223, which serves as a separate electrode for a plurality of driven piezoelectric elements 21 and a plurality of non-driven piezoelectric elements 22, is formed on one side of the stacked piezoelectric component 201, i.e., the joint portion 27, and the electrode layers are arranged independently of each other by being divided by the groove 23. The electrode layers of the external electrode 224, which serves as the common electrode, are connected to each other, for example, on the other side of the stacked piezoelectric component 201, for example, grounded.

[0032] External electrodes 223 are connected to the drive circuit 70 via an FPC 71, which is a flexible substrate and serves as a wiring substrate, for example, on one side, i.e., the junction 27. For example, each external electrode 223 is configured to be connected to the control unit 116, which serves as the drive unit, via the FPC 71 and the drive IC 72 of the drive circuit 70, and can be driven and controlled by the control circuit 1161. It should be noted that the configuration of common electrodes and individual electrodes can also be reversed. It should also be noted that external electrodes 224 can be routed around to the side of the external electrode 223, i.e., the junction 27, and connected to the drive circuit 70 via the FPC 71.

[0033] The dummy layer 212 and the piezoelectric layer 211 are made of the same material. Since the dummy layer 212 has an electrode on only one side, it does not form an electric field and therefore will not deform. That is, the dummy layer 212 does not function as a piezoelectric element, but serves as a base for fixing or as a grinding material for grinding to meet the accuracy requirements during and after assembly.

[0034] A removal portion 25 having an inclined surface that is obliquely inclined relative to the stacking direction is formed on the end of the individual electrode side of the stacked piezoelectric component 201 constituting piezoelectric elements 21 and 22 on the side of the base 10. The removal portion 25 is configured as a chamfered portion with the corner cut into a conical shape, so that the region of the end of the piezoelectric element 21 on the side of the base 10 is recessed in a direction away from the FPC71.

[0035] The removal portion 25 extends in a planar direction along the stacking direction (i.e., the first direction) and the third direction (which is the arrangement direction of the pressure chambers). For example, the removal portion 25 is provided in the dummy layer 212. That is, in the piezoelectric element 21, a portion of the part that does not function as a piezoelectric body and does not deform is cut off and configured as an inclined surface. It should be noted that the removal portion 25 may also be located in the piezoelectric body layer 211, in which case it is positioned to avoid the internal electrodes 221, 222 and the external electrodes 223, 224.

[0036] In addition, the vibration direction of each piezoelectric element 21 and 22 is along the stacking direction, and is displaced in the d33 direction by applying an electric field.

[0037] As an example, each piezoelectric element 21 and 22 has 3 or more layers and less than 50 layers. The thickness of each layer is set to be more than 10 μm and less than 40 μm, and the product of the thickness and the total number of layers is set to be less than 1000 μm.

[0038] The piezoelectric element 21 is driven to vibrate by applying voltage to the internal electrodes 221 and 222 via the external electrodes 223 and 224. In this embodiment, the piezoelectric element 21 is driven to vibrate longitudinally along the stacking direction of the piezoelectric layer 211. The longitudinal vibration referred to here is, for example, "vibration in the thickness direction defined by the piezoelectric constant d33". The longitudinal vibration of the piezoelectric element 21 displaces the vibrating plate 30 and deforms the pressure chamber 31.

[0039] The flow path component 40 includes: a vibrating plate 30, which is disposed opposite to one side of the actuator section 20 in the deformation direction; and a flow path substrate 405, which is stacked on one side of the vibrating plate 30.

[0040] The vibrating plate 30 is disposed between the flow path substrate 405 and the actuator section 20 in the vibration direction. The vibrating plate 30 and the flow path substrate 405 together constitute the flow path component 40.

[0041] The vibrating plate 30 extends along a surface orthogonal to the vibration direction, i.e., the Z-direction, and engages with the surface of the piezoelectric layer 211 of the plurality of piezoelectric elements 21, 22 on the side of the vibration direction, i.e., the nozzle plate 50 side. The vibrating plate 30 is configured to be deformable, for example. The vibrating plate 30 engages with the driving piezoelectric element 21 and the non-driving piezoelectric element 22 of the actuator section 20 and the frame section 60. For example, the vibrating plate 30 has a vibration region 301 opposite to the piezoelectric elements 21, 22 and a support region 302 opposite to the frame section 60.

[0042] The vibration region 301 is, for example, a flat plate configured such that its thickness direction is the vibration direction of the piezoelectric layer 211. The vibrating plate 30 extends in the direction in which the plurality of driven piezoelectric elements 21 and the plurality of non-driven piezoelectric elements 22 are arranged. The vibrating plate 30 is, for example, a metal plate. The vibrating plate 30 has a plurality of vibration portions opposite to each pressure chamber 31 and capable of individual displacement. The vibrating plate 30 is formed by integrally connecting the plurality of vibration portions.

[0043] As an example, the vibrating plate 30 is constructed of nickel or SUS plate, with a thickness of 5 μm to 15 μm along the vibration direction. It should be noted that the vibration region 301 may also have creases or stepped differences formed in areas adjacent to or between adjacent vibration locations to facilitate displacement of multiple vibration locations. The vibration region 301 deforms by displacing the portion opposite to the driving piezoelectric element 21 through the elongation and compression of the driving piezoelectric element 21. For example, since the vibrating plate 30 requires an extremely thin and complex shape, it is formed using electroforming or similar methods. The vibrating plate 30 is bonded to the upper surface of the actuator section 20 by adhesive or the like.

[0044] The support region 302 is a plate-shaped component disposed between the frame portion 60 and the flow path substrate 405. The support region 302 has a connecting portion 33 having a through hole communicating with the common chamber 32.

[0045] For example, the connecting part 33 has a filter component with many fine holes through which liquid can pass as through holes.

[0046] The flow path substrate 405 is disposed between the nozzle plate 50 and the vibrating plate 30 in the vibration direction. The flow path substrate 405 is joined to one side of the vibrating plate 30 in the vibration direction.

[0047] The flow path substrate 405 includes: a peripheral wall portion 41 that engages with the outer edge of the vibrating plate 30; a plurality of partition wall portions 42 that separate a plurality of ink flow paths 35; and a guide wall 43 that forms a guide flow path 34. The flow path substrate 405 forms a predetermined ink flow path 35, which has: a plurality of pressure chambers 31 that are separated by the partition wall portions 42; and a guide flow path 34 that extends in a second direction from the plurality of pressure chambers 31 toward the connecting portion 33 and is separated by the partition wall portions 42.

[0048] Within the flow path substrate 405, a plurality of pressure chambers 31 arranged side-by-side in a third direction are separated by partitions 42. That is, the two sides of the pressure chambers 31 in the third direction are separated by partitions 42. Each pressure chamber 31 communicates with a nozzle 51 formed on a nozzle plate 50 disposed on one side. In addition, the pressure chambers 31 block the opposite side of the nozzle plate 50 by a vibrating plate 30.

[0049] Multiple pressure chambers 31 are spaces formed on one side of the vibration area 301 of the vibrating plate 30, and are connected to the common chamber 32 via the guide flow path 34 and the connecting portion 33. The multiple pressure chambers 31 are connected to the nozzles 51 formed on the nozzle plate 50. In addition, the pressure chambers 31 block the opposite side of the nozzle plate 50 through the vibrating plate 30.

[0050] Multiple pressure chambers 31 hold liquid supplied from a common chamber 32 through a guide flow path 34 and are deformed by the vibration of a vibrating plate 30 that forms part of the pressure chamber 31, thereby ejecting the liquid from the nozzle 51.

[0051] The partition wall 42 is a wall component that separates the multiple pressure chambers 31 arranged in parallel directions and the multiple guide flow paths 34 arranged in parallel directions, and constitutes the side portions of the pressure chambers 31 and the guide flow paths 34. The partition wall 42 is disposed opposite to the non-driven piezoelectric element 22 across the vibrating plate 30 and is supported by the non-driven piezoelectric element 22. Multiple partition wall 42s are provided at a spacing equal to the spacing between the multiple pressure chambers 31.

[0052] The nozzle plate 50 is configured, for example, as a square plate with a thickness of 10 μm to 100 μm formed of a metal such as SUS·Ni and a resin material such as polyimide. The nozzle plate 50 is disposed on one side of the flow path substrate 405 such that it covers the opening on one side of the pressure chamber 31.

[0053] Multiple nozzles 51 are arranged in a first direction, which is the same as the arrangement direction of the pressure chambers 31, thereby forming a nozzle array. For example, the nozzles 51 are arranged in two rows, and each nozzle 51 is respectively disposed at a position corresponding to the multiple pressure chambers 31 arranged in two rows. In this embodiment, the nozzles 51 are respectively disposed at the end of the pressure chamber 31 in the extending direction.

[0054] The frame portion 60 is a structure that is joined to the piezoelectric elements 21 and 22 and the vibrating plate 30. The frame portion 60 is disposed on the opposite side of the piezoelectric elements 21 and 22, the vibrating plate 30, and the flow path substrate 405, for example, in this embodiment, it is arranged adjacent to the actuator portion 20. The frame portion 60 forms the outer shell of the inkjet head 1. Additionally, the frame portion 60 may also form a liquid flow path internally. In this embodiment, the frame portion 60 is joined to the other side of the vibrating plate 30 and forms a common chamber 32 between it and the vibrating plate 30.

[0055] The common chamber 32 is formed inside the frame portion 60 and is connected to the pressure chamber 31 through the connecting portion 33 provided on the vibrating plate 30 and the guide flow path 34.

[0056] The driving circuit 70 includes an FPC71 (Flexible printed circuit board) with one end connected to external electrodes 223 and 224, a driving IC72 mounted on the FPC71, and a printed wiring board 73 mounted on the other end of the FPC71.

[0057] The drive circuit 70 applies a drive voltage to the external electrodes 223 and 224 via the drive IC 72 to drive the piezoelectric element 21, thereby increasing or decreasing the volume of the pressure chamber 31 and causing the droplets to be ejected from the nozzle 51.

[0058] The FPC71 is connected to multiple external electrodes 223 and 224. A COF (Chipon Film) with a driver IC72 mounted as an electronic component is used as the FPC71.

[0059] FPC71 is connected to one side of the laminated piezoelectric component 201, namely the joint 27. For example... Figure 3 As shown, the FPC71 includes a substrate layer 711, an electrode layer 712, a solder plating layer 713, an adhesive layer 714, and an insulating cover layer 715.

[0060] The base layer 711 is mainly composed of polyimide in a sheet shape of a specified thickness. The electrode layer 712 is made of a conductive material such as metal and is formed on the surface of the base layer 711 in a specified pattern. The electrode layer 712 is, for example, copper foil. On the surface of the electrode layer 712, a solder plating layer 713 is formed in a first region, which serves as the bonding region for bonding with the piezoelectric element 21. The solder plating layer 713 is formed to a thickness of 3 to 10 μm by solder plating. On the surface of the electrode layer 712, an insulating cover layer 715 is formed in a second region other than the bonding region, separated by an adhesive layer 714. Here, for example, one end of the FPC 71 in the first direction is designated as the first region, and the other end is designated as the second region.

[0061] The FPC71, with its first region having a solder plating layer 713, is aligned and heated against the side of the bonding portion 27 of one of the stacked piezoelectric components 201 constituting the piezoelectric elements 21 and 22, causing the solder in the solder plating layer 713 to melt, thereby electrically and mechanically connecting it to the external electrode 223. It should be noted that the FPC71 can also be connected to a portion of the external electrode 224 that wraps around the bonding portion 27. Heating can be performed using general heating tools, or by irradiating the substrate layer 711 of the FPC71 with an infrared laser. Although the method may vary depending on conditions such as component warping, bonding can be achieved, for example, by applying pressure of 100g to the solder.

[0062] Used in solder plating layer 713 Figure 4 Among the various solders shown, lead-free solders have a melting point of less than half the Curie point of the piezoelectric material and are above the highest reaching temperature of the joint 27. Here, the highest reaching temperature of the joint 27 is the highest value of the reaching temperature of the joint 27 that is conceived when the heating element of the piezoelectric element, the driver IC, etc., heats the joint 27 during driving and causes the temperature to rise. For example, the highest reaching temperature is a specified value based on the heating temperature of the driver IC 72. The mounting part becomes high temperature due to the heating of the piezoelectric element, the heat of the driver IC 72, and the insulation of the FPC 71. As an example, the temperature of the mounting part during printing when the duty ratio is 100% is set as the highest reaching temperature. Alternatively, the heating temperature of the heating element such as the driver IC 72 and the piezoelectric component 201 can also be set as the highest reaching temperature of the joint 27. As an example, solder with a melting point of 90°C or higher is preferred. The duty ratio is the ratio of the period of the driving signal (pulse signal) to the pulse width of the driving signal, and is expressed by the following formula.

[0063] Duty ratio = Pulse width of drive signal / Period of drive signal (pulse signal)

[0064] For example, as the solder constituting the solder plating layer 713, Sn-Bi-In with a melting point of 60-110°C, Sn-52In with a melting point of 118°C, Sn-58Bi with a melting point of 138°C, and In with a melting point of 156°C are used. For example, in an inkjet head of a stacked piezoelectric component 201 that uses piezoelectric materials, has a Curie point of 300°C, and a maximum temperature reached at the junction 27 of 82°C, Sn-In or Sn-Bi based solders are preferred.

[0065] For example, due to the difference between the total thickness of the insulating cover layer 715 and the adhesive layer 714 and the thickness of the solder plating layer 713, the thickness of the second region of FPC71 becomes greater than the thickness of the first region, forming a step difference on the surface of FPC71. The solder plating layer 713 is arranged opposite the bonding surface 27 and the insulating cover layer 715 is arranged opposite the removal portion 25.

[0066] The driver IC72 is connected to external electrodes 223 and 224 via FPC71. The driver IC72 is the electronic component used for ejection control.

[0067] The driver IC 72 generates control signals and drive signals to operate each drive piezoelectric element 21. Based on the image signal input from the control unit 116 of the inkjet recording apparatus 100 equipped with the inkjet head 1, the driver IC 72 generates control signals for controlling the timing of ink ejection and selecting the drive piezoelectric elements 21 for ink ejection. Additionally, the driver IC 72 generates a voltage, i.e., a drive signal, applied to the drive piezoelectric element 21 based on the control signal from the control unit 116. When the driver IC 72 applies the drive signal to the drive piezoelectric element 21, the drive piezoelectric element 21 is driven, causing the vibrating plate 30 to shift and the volume of the pressure chamber 31 to change. This causes pressure vibration in the ink filling the pressure chamber 31. Due to the pressure vibration, ink is ejected from the nozzle 51, which communicates with the pressure chamber 31. It should be noted that the inkjet head 1 can also achieve grayscale representation by changing the amount of ink droplets falling on a pixel. Alternatively, the inkjet head 1 can change the amount of ink droplets falling on a pixel by changing the number of ink ejections. Thus, the driver IC72 is an example of applying a drive signal to the application part of the drive piezoelectric element 21.

[0068] For example, the driver IC72 includes a data buffer, a decoder, and a driver. The data buffer stores the printed data in a time sequence according to the driving piezoelectric elements 21. The decoder controls the driver based on the printed data stored in the data buffer according to the driving piezoelectric elements 21. Based on the control of the decoder, the driver outputs a drive signal that actuates each driving piezoelectric element 21. The drive signal is, for example, a voltage applied to each driving piezoelectric element 21.

[0069] The printed wiring board 73 is a PWA (Printing Wiring Assembly) equipped with various electronic components and connectors, and has a head control circuit 731. The printed wiring board 73 is connected to the control unit 116 of the inkjet recording device 100.

[0070] In the inkjet head 1 configured as described above, an ink flow path is formed by a nozzle plate 50, a frame portion 60, a flow path substrate 405, and a vibrating plate 30. This ink flow path has multiple pressure chambers 31 communicating with the nozzles 51, multiple guide flow paths 34 communicating with the multiple pressure chambers 31 respectively, and a common chamber 32 communicating with the multiple guide flow paths 34. For example, the common chamber 32 communicates with the ink cartridge, and ink is supplied to each pressure chamber 31 through the common chamber 32. All driving piezoelectric elements 21 are connected by wiring in a manner that allows voltage to be applied. In the inkjet head 1, for example, when the control unit 116 of the inkjet recording device 100 applies a driving voltage to the electrodes 221 and 222 via the driving IC 72, the driving piezoelectric element 21 of the driven object vibrates, for example, in the stacking direction, i.e., in the thickness direction of each piezoelectric layer 211. That is, the driving piezoelectric element 21 vibrates longitudinally.

[0071] Specifically, the control unit 116 applies a driving voltage to the internal electrodes 221 and 222 of the driving piezoelectric element 21 of the driven object to selectively drive the driving piezoelectric element 21 of the driven object. Furthermore, the driving piezoelectric element 21 of the driven object combines deformation in the tensile direction with deformation in the compression direction, deforms the vibrating plate 30, and changes the volume of the pressure chamber 31, thereby guiding liquid from the common chamber 32 and ejecting the liquid from the nozzle 51.

[0072] An example of the manufacturing method of the inkjet head 1 according to this embodiment will be described. First, internal electrodes 221 and 222 are formed on a piezoelectric material formed into a sheet by printing process. In addition, multiple piezoelectric layers 211 having internal electrodes 221 and 222 are stacked, and then subjected to firing and electrode separation processes to form a stacked piezoelectric component 201.

[0073] Then, the stacked piezoelectric component 201, with internal electrodes 221 and 222 pre-formed, is disposed on the substrate 10. For example, in the case of two actuator sections 20, after the integrally formed stacked piezoelectric component 201 is joined to the substrate 10, it can be divided into two by groove processing or the like, or two stacked piezoelectric components 201 constituting the two actuator sections 20 can be prepared separately.

[0074] Next, external electrodes 223 and 224 are formed on the end faces of one and the other of the stacked piezoelectric components 201 through a printing process. Furthermore, a removal portion 25 is formed at the end of the component with the external electrode 223 as a separate electrode through a cutting process. Due to the formation of the removal portion 25, the electrode layer on the substrate 10 side of the external electrode 223 is removed. Furthermore, by forming multiple grooves 23 reaching the depth of the portion where the electrode is removed by the removal portion 25, one side of the stacked piezoelectric component 201 in the Z direction is divided into multiple parts. As described above, a stacked piezoelectric component 201 is formed with one end divided into multiple parts and the other end connected. At this time, multiple grooves 23 are simultaneously formed at predetermined intervals to divide the stacked piezoelectric component 201 into multiple parts, thereby forming multiple columnar elements arranged at the same interval as multiple piezoelectric elements 21 and 22. As described above, multiple driven piezoelectric elements 21 and non-driven piezoelectric elements 22 arranged at the same interval are formed.

[0075] Here, by setting the groove 23 to the depth reaching the removal portion 25 of the electrode layer, the electrode layers on the side where the removal portion 25 is located become separate and independent individual electrodes. On the other hand, the electrode layers on the side where the removal portion 25 is not formed constitute a common electrode in a region where the electrode layers are continuous on the substrate 10 side, which is closer to the bottom of the groove. Furthermore, the piezoelectric element 21 is subjected to electrode separation processing and is attached to the substrate 10 by adhesive or the like.

[0076] In the junction 27, the FPC 71, which serves as a control component and houses electronic components such as the driver IC 72, is connected to external electrodes 223 and 224, for example, via solder mounting. Furthermore, the printed wiring substrate 73, which has a head control circuit 731, is connected to the FPC 71.

[0077] Furthermore, in the actuator section 20, the vibrating plate 30, the flow path substrate 405 and the nozzle plate 50 are stacked and positioned with bonding materials spaced apart, and the frame section 60 is arranged on the outer periphery of the actuator section 20 to join these multiple components and complete the inkjet head 1.

[0078] The following is for reference Figure 6 An example of an inkjet recording apparatus 100 equipped with an inkjet head 1 will be described. The inkjet recording apparatus 100 includes a housing 111, a media supply unit 112, an image forming unit 113, a media discharge unit 114, a transport device 115, and a control unit 116.

[0079] The inkjet recording apparatus 100 is a liquid ejection device that ejects liquid such as ink onto the paper P as the ejection object, i.e., the printing medium, along a predetermined transport path R from the media supply unit 112 through the image forming unit 113 to the media discharge unit 114, thereby performing image forming processing on the paper P.

[0080] The housing 111 forms the outer perimeter of the inkjet recording device 100. A discharge port for discharging paper P to the outside is provided at a designated location on the housing 111.

[0081] The media supply unit 112 has multiple paper feed boxes and is configured to be stacked to hold multiple sheets of paper P of various sizes.

[0082] The media discharge section 114 is equipped with a paper discharge tray configured to hold the paper P discharged from the discharge port.

[0083] The image forming unit 113 includes a support portion 117 for supporting the paper P and a plurality of head units 130 disposed above the support portion 117.

[0084] The support portion 117 includes: a conveyor belt 118 formed in a loop in a predetermined area where image formation is performed; a support plate 119 supporting the conveyor belt 118 from the back side; and a plurality of belt rollers 120 disposed on the back side of the conveyor belt 118.

[0085] When an image is formed, the support portion 117 supports the paper P on the upper surface of the conveyor belt 118, i.e., the holding surface, and the conveyor belt 118 is conveyed at a predetermined time by the rotation of the belt roller 120, thereby conveying the paper P to the downstream side.

[0086] The head unit 130 includes: multiple (4-color) inkjet heads 1; ink cartridges 132, which serve as liquid containers, and are respectively mounted on each inkjet head 1; a connecting flow path 133 connecting the inkjet head 1 and the ink cartridge 132; and a supply pump 134.

[0087] In this embodiment, the inkjet head 1 has four colors: cyan, magenta, yellow, and black, and ink cartridges 132 that respectively contain ink of these colors. The ink cartridges 132 are connected to the inkjet head 1 via a connection flow path 133.

[0088] Additionally, a negative pressure control device, such as a pump (not shown), is connected to the ink cartridge 132. Furthermore, corresponding to the water head value of the inkjet head 1 and the ink cartridge 132, the negative pressure control device controls the negative pressure inside the ink cartridge 132, thereby causing the ink supplied to each nozzle 51 of the inkjet head 1 to form a meniscus of a predetermined shape.

[0089] The supply pump 134 is, for example, a liquid delivery pump configured as a piezoelectric pump. The supply pump 134 is provided in the supply flow path. The supply pump 134 is configured to be connected to the control circuit 1161 of the control unit 116 via wiring and can be controlled by the control unit 116. The supply pump 134 supplies liquid to the inkjet head 1.

[0090] The conveying device 115 conveys paper P along the conveying path R from the media supply unit 112 through the image forming unit 113 to the media discharge unit 114. The conveying device 115 includes a plurality of guide plate pairs 121 arranged along the conveying path R and a plurality of conveying rollers 122.

[0091] Each of the multiple guide plates 121 has a pair of plate components that are arranged opposite each other to clamp the paper P being conveyed, and guides the paper P along the conveying path R respectively.

[0092] The conveying roller 122 is driven to rotate under the control of the control unit 116, thereby feeding the paper P downstream along the conveying path R. It should be noted that sensors for detecting the conveying status of the paper are arranged at various points along the conveying path R.

[0093] The control unit 116 includes a control circuit 1161 such as a CPU (Central Processing Unit) that serves as a controller, a ROM (Read Only Memory) that stores various programs, a RAM (Random Access Memory) that temporarily stores various variable data, image data, etc., and an interface unit for inputting data from the outside and outputting data to the outside.

[0094] In the inkjet recording apparatus 100 configured as described above, the control unit 116, for example, when detecting a printing instruction given by the user operation input unit in the interface, drives the transport device 115 to transport the paper P and outputs a printing signal to the head unit 130 at a predetermined timing, thereby driving the inkjet head 1. As an ejection operation, the inkjet head 1 sends a drive signal to the drive IC 72 according to the image signal corresponding to the image data, applies a drive voltage to the internal electrodes 221, 222, and selectively drives the drive piezoelectric element 21 of the ejection object to vibrate longitudinally, for example, in the lamination direction, causing a change in the volume of the pressure chamber 31, thereby ejecting ink from the nozzle 51 and forming an image on the paper P held on the conveyor belt 118. In addition, as a liquid ejection operation, the control unit 116 supplies ink from the ink cartridge 132 to the common chamber 32 of the inkjet head 1 by driving the supply pump 134.

[0095] Here, the driving operation of the inkjet head 1 will be explained. The inkjet head 1 according to this embodiment includes driving piezoelectric elements 21 disposed opposite to the pressure chamber 31. These driving piezoelectric elements 21 are connected by wiring in a manner that allows voltage to be applied. The control unit 116 sends a driving signal to the driving IC 72 based on an image signal corresponding to image data, applying a driving voltage to the internal electrodes 221, 222 of the driving piezoelectric elements 21, selectively deforming the driving piezoelectric elements 21. Furthermore, the deformation in the tensile direction and the compression direction of the combined vibrating plate 30 causes a change in the volume of the pressure chamber 31, thereby causing liquid to be ejected.

[0096] For example, the control unit 116 alternately performs stretching and compression actions. In the inkjet head 1, when stretching is performed to increase the internal volume of the pressure chamber 31 of the object, the drive piezoelectric element 21 driving the object is contracted without deforming the drive piezoelectric element 21 outside the object. Conversely, in the inkjet head 1, when compression is performed to decrease the internal volume of the pressure chamber 31 of the object, the drive piezoelectric element 21 of the object is extended. It should be noted that the non-drive piezoelectric element 22 is not deformed.

[0097] According to the inkjet head 1 and inkjet recording device 100 described in the above embodiments, the FPC71 solder can be directly bonded to the electrodes of the piezoelectric component. That is, by setting the melting point of the solder to less than half the Curie point of the piezoelectric component, a reliable installation without degradation can be achieved. For example, generally, the degradation point of PZT is around half the Curie point, but by setting the melting point of the solder in the solder plating layer 713 of the FPC71 to less than half the Curie point of the piezoelectric material, degradation of the piezoelectric component can be prevented. In addition, for example, since electronic components such as the driver IC 72 mounted on the FPC71 and the piezoelectric element, as well as their surroundings, generate heat during operation, and the piezoelectric element itself also generates heat during driving, the joint 27, which serves as the solder mounting part, rises to, for example, 80°C to 90°C. Therefore, if the melting point of the solder is too low, the reliability during operation will decrease. In this embodiment, by setting the melting point of the solder above the highest temperature that is expected to be reached in the joint 27, it is possible to prevent the solder from melting during use and avoid poor installation (poor connection).

[0098] Therefore, since FPC solder can be directly mounted onto the piezoelectric structure without the need for pressure bonding, it is possible to mount the delicate and fragile piezoelectric element, which is divided by grooves, without damaging it. In particular, even in structures with weak bonding strength between the piezoelectric material and the electrode material, such as the laminated piezoelectric component 201, mounting can be performed without applying significant pressure.

[0099] It should be noted that the present invention is not directly limited to the above-described embodiments. During the implementation stage, the constituent elements can be modified and specified without departing from its spirit.

[0100] The specific materials and composition of the piezoelectric elements 21 and 22 in the above embodiments are not limited to the above content and can be appropriately changed.

[0101] Furthermore, although the piezoelectric element 21 is configured as a multilayered piezoelectric layer 211 and driven by longitudinal vibration (d33) in the stacking direction, it is not limited to this. For example, it is also possible to use a single-layered piezoelectric component to drive the piezoelectric element 21, or to use a method of driving by lateral vibration displaced in the d31 direction.

[0102] The arrangement of the nozzles 51 and pressure chambers 31 is not limited to the above-described embodiment. For example, the nozzles 51 may be arranged in two or more rows. Additionally, an air chamber, serving as a dummy chamber, may be formed between multiple pressure chambers 31. It is not limited to a circulating type; a non-circulating type inkjet head may also be used, or it is not limited to an end slide type; a side slide type inkjet head may also be applied.

[0103] Furthermore, although examples are shown where piezoelectric elements 21 and 22 have dummy layers 212 at both ends in the stacking direction, this is not a limitation. Dummy layers 212 may be present only on one side of piezoelectric elements 21 and 22, or piezoelectric elements 21 and 22 may not have dummy layers 212 at all. In addition, the configuration and positional relationship of various components, including the flow path component 40, the nozzle plate 50, and the frame portion 60, are not limited to the above examples and can be appropriately modified.

[0104] Furthermore, although an example of a heat source being the driver IC72 has been shown, it is not limited to this. For example, it could be a mounting component other than the driver IC72, or a peripheral component other than the driver IC72 in the actuator section 20, etc.

[0105] In addition, the sprayed liquid is not limited to ink for printing; for example, it can be a device that sprays liquid containing conductive particles for forming wiring patterns on a printed wiring substrate.

[0106] Furthermore, although examples of liquid ejection devices used in inkjet recording devices and the like have been shown in the above embodiments, they are not limited to this. For example, the inkjet head 1 can also be used in 3D printing, industrial manufacturing machines, and medical applications, and can be miniaturized, lightweight, and cost-effective.

[0107] According to at least one of the embodiments described above, the desired flow path shape can be easily set.

[0108] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. A liquid ejector head, characterized in that, have: A piezoelectric component comprising multiple piezoelectric elements formed of a piezoelectric material; Multiple electrodes are formed on the piezoelectric element; as well as The wiring substrate is bonded to the electrodes by solder. The melting point of the solder is less than half the Curie point of the piezoelectric material. The melting point of the solder is above the highest temperature reached at the joint where it is bonded to the wiring substrate. The maximum temperature reached is the temperature at which text is printed when the duty cycle in the joint portion bonded to the wiring substrate is 100%. The duty cycle is the ratio of the period of the driving signal to the pulse width of the driving signal, and is expressed by the following formula (1). Duty cycle = pulse width of drive signal / period of drive signal (1) The piezoelectric element includes a driven piezoelectric element and a non-driven piezoelectric element.

2. The liquid ejector head according to claim 1, characterized in that, The solder is lead-free.

3. The liquid ejector head according to claim 1, characterized in that, The piezoelectric component is a stacked piezoelectric component consisting of multiple piezoelectric body layers and multiple internal electrode layers. The wiring substrate is a flexible substrate that is directly bonded to the stacked piezoelectric component.

4. The liquid ejector head according to claim 3, characterized in that, The piezoelectric layer is made of piezoelectric ceramic material in the form of a thin plate.

5. The liquid ejector head according to claim 3, characterized in that, The stacking direction of the piezoelectric layer is the same as the vibration direction of the piezoelectric element.

6. The liquid ejector head according to claim 3, characterized in that, Grooves are formed in the stacked piezoelectric components.

7. The liquid ejector head according to claim 3, characterized in that, An external electrode is formed on the stacked piezoelectric component.

8. A liquid ejection device, characterized in that, It has a liquid ejector head as described in any one of claims 1 to 7.

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