Liquid discharge head and recording device

Abstract

This liquid discharge head comprises a pressure chamber, a vibration plate, a lower electrode, a piezoelectric body, and an upper electrode. The vibration plate is positioned on the pressure chamber. The lower electrode is positioned on the vibration plate. The piezoelectric body is positioned on the lower electrode. The upper electrode is positioned on the piezoelectric body. In a cross-sectional view, the end sections of the piezoelectric body include: a first portion that has a side surface inclined with respect to the surface of the lower electrode; and a second portion that is in contact with the first portion and the lower electrode and that has a side surface inclined with respect to the surface of the lower electrode. The inclination angle of the side surface of the second portion is smaller than the inclination angle of the side surface of the first portion.

Description

Liquid dispensing head and recording device

[0001] This disclosure relates to a liquid dispensing head and a recording device.

[0002] A liquid discharge head that discharges liquid toward a recording medium is known (see, for example, Patent Document 1). In Patent Document 1, the liquid discharge head discharges the liquid in the pressure chamber from a nozzle by driving a piezoelectric element located at the top of the pressure chamber to change the pressure inside the pressure chamber. The piezoelectric element has a lower electrode, a piezoelectric body located above the lower electrode, and an upper electrode located above the piezoelectric body.

[0003] Japanese Patent Publication No. 2008-227144

[0004] A liquid discharge head according to one aspect of the present disclosure comprises a pressure chamber, a diaphragm, a lower electrode, a piezoelectric element, and an upper electrode. The diaphragm is located above the pressure chamber. The lower electrode is located above the diaphragm. The piezoelectric element is located above the lower electrode. The upper electrode is located above the piezoelectric element. In cross-sectional view, the end of the piezoelectric element has a first portion whose side surface is inclined with respect to the surface of the lower electrode, and a second portion which is in contact with the first portion and the lower electrode, and whose side surface is inclined with respect to the surface of the lower electrode. The inclination angle of the side surface of the second portion is smaller than the inclination angle of the side surface of the first portion.

[0005] Figure 1 is a schematic side view showing a printer according to the first embodiment. Figure 2 is a schematic top view showing a printer according to the first embodiment. Figure 3 is an exploded perspective view showing the schematic configuration of the liquid ejection head in steps. Figure 4 is an exploded perspective view showing the schematic configuration of the line head unit in steps. Figure 5 is a cross-sectional view along the line A-A shown in Figure 3. Figure 6 is a perspective view showing the schematic configuration of a part of the channel group in the MEMS chip. Figure 7 is a cross-sectional view showing the detailed configuration of the actuator substrate. Figure 8 is a schematic top view showing the actuator substrate. Figure 9 is an enlarged view showing the area around the end of the piezoelectric body according to the first embodiment. Figure 10 is an enlarged view showing the area around the end of the piezoelectric body according to the second embodiment. Figure 11 is an enlarged view showing the area around the end of the piezoelectric body according to the third embodiment.

[0006] The following describes in detail, with reference to the drawings, embodiments for implementing the liquid discharge head and recording device according to this disclosure (hereinafter referred to as "Embodiments"). However, this disclosure is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the following embodiments, and redundant descriptions are omitted.

[0007] Furthermore, in the embodiments described below, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not require strict adherence to "constant," "orthogonal," "perpendicular," or "parallel" conditions. In other words, each of the above expressions allows for deviations such as manufacturing accuracy or installation accuracy.

[0008] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown with the positive Z axis pointing vertically upward.

[0009] (First Embodiment) <Printer Configuration> First, an overview of the printer 100, which is an example of a recording device according to the first embodiment, will be described with reference to Figures 1 and 2. Figure 1 is a schematic side view showing the printer 100 according to the first embodiment. Figure 2 is a schematic top view showing the printer 100 according to the first embodiment. The printer 100 according to the first embodiment is, for example, a color inkjet printer.

[0010] As shown in Figure 1, the printer 100 includes a paper feed roller 101, guide rollers 102A to 102C, multiple transport rollers 103, a recovery roller 104, a head case 105, multiple frames 106, multiple liquid discharge heads 1, a dryer 107, and a coating machine 109. Furthermore, the printer 100 includes a sensor unit 108 and a control unit 200.

[0011] The control unit 200 controls the paper feed roller 101, guide rollers 102A to 102C, multiple transport rollers 103, recovery roller 104, head case 105, multiple frames 106, multiple liquid discharge heads 1, dryer 107, sensor unit 108, and coating machine 109.

[0012] The printer 100 records images or characters on the printing paper P by depositing droplets of liquid onto the paper P. The printing paper P is an example of a recording medium. Before use, the printing paper P is wound around the paper feed roller 101. The printer 100 then transports the printing paper P from the paper feed roller 101 to the inside of the head case 105 via the guide roller 102A and the coating machine 109.

[0013] The coating machine 109 uniformly applies the coating agent to the printing paper P. This allows the printing paper P to undergo surface treatment, thereby improving the print quality of the printer 100.

[0014] The head case 105 houses multiple transport rollers 103, multiple frames 106, and multiple liquid discharge heads 1. Inside the head case 105, a space is formed that is isolated from the outside, except for parts that are connected to the outside, such as the area where the printing paper P enters and exits.

[0015] The internal space of the head case 105 is controlled by the control unit 200, as needed, by at least one of the control factors such as temperature, humidity, and atmospheric pressure. The transport roller 103 transports the printing paper P to the vicinity of the liquid discharge head 1 inside the head case 105.

[0016] The frame 106 is a rectangular flat plate and is positioned close above the printing paper P being transported by the transport roller 103. Also, as shown in Figure 2, the frame 106 is positioned so that its longitudinal direction is perpendicular to the transport direction of the printing paper P. Inside the head case 105, multiple (for example, four) frames 106 are positioned along the transport direction of the printing paper P.

[0017] Liquid, such as ink, is supplied to the liquid ejection head 1 from a liquid tank (not shown). The liquid ejection head 1 ejects droplets supplied from the liquid tank.

[0018] The control unit 200 controls the liquid ejection head 1 based on data such as images or characters, and ejects droplets toward the printing paper P. The distance between the liquid ejection head 1 and the printing paper P is, for example, about 0.5 to 20 mm.

[0019] The liquid dispensing head 1 is fixed to the frame 106. The liquid dispensing head 1 is fixed to the frame 106, for example, at both ends in the longitudinal direction. The liquid dispensing head 1 is positioned so that its longitudinal direction is perpendicular to the direction in which the printing paper P is transported.

[0020] In other words, the printer 100 according to the first embodiment is a so-called line printer in which the liquid ejection head 1 is fixed inside the printer 100. However, the printer 100 according to the first embodiment is not limited to a line printer, but may also be a so-called serial printer. A serial printer is a type of printer that alternately performs the operation of recording while moving the liquid ejection head 1 back and forth in a direction intersecting the transport direction of the printing paper P, for example, in a nearly perpendicular direction, and the transport of the printing paper P.

[0021] As shown in Figure 2, a unit formed by arranging multiple (for example, eight) liquid discharge heads 1 on a single frame 106 is also called a Line Head Unit (LHU). Figure 2 shows an example of a Line Head Unit 1A in which four liquid discharge heads 1 are positioned in a staggered pattern in front of the printing paper P in the transport direction, and four are positioned behind it. The liquid discharge heads 1 are positioned so that the centers of each liquid discharge head 1 do not overlap in the transport direction of the printing paper P.

[0022] The line head unit 1A is composed of multiple liquid ejection heads 1 located on a single frame 106. The four line head units 1A are positioned along the transport direction of the printing paper P. Liquid ejection heads 1 belonging to the same line head unit 1A are supplied with ink of the same color. As a result, the printer 100 can perform printing with four colors of ink using the four line head units 1A. The four line head units 1A may be arranged side by side to form a carriage, which is one example of the final form of the liquid ejection head 1.

[0023] The ink colors ejected from each line head unit 1A are, for example, magenta (M), yellow (Y), cyan (C), and black (K). The control unit 200 controls each line head unit 1A to eject multiple colors of ink onto the printing paper P, thereby enabling the printing of a color image on the paper P.

[0024] Furthermore, in order to treat the surface of the printing paper P, a coating agent may be dispensed onto the printing paper P from the liquid discharge head 1.

[0025] Furthermore, the number of liquid ejection heads 1 included in one line head unit 1A, or the number of line head units 1A installed in the printer 100, can be appropriately changed depending on the object to be printed or the printing conditions. For example, if the color to be printed on the printing paper P is a single color and the printing is limited to the area that can be printed with one liquid ejection head 1, then the number of liquid ejection heads 1 installed in the printer 100 may be as small as one.

[0026] The printed paper P, which has been processed inside the head case 105, is transported to the outside of the head case 105 by the transport roller 103, then transported by the guide roller 102B, and passes through the inside of the dryer 107. The dryer 107 dries the printed paper P. The printed paper P that has been dried in the dryer 107 is transported by the guide roller 102C and collected by the recovery roller 104.

[0027] In the printer 100, drying the printing paper P in the dryer 107 reduces the likelihood of the overlapping printing paper P sticking together or of undried liquid rubbing against each other in the recovery roller 104.

[0028] The sensor unit 108 is composed of a position sensor, a speed sensor, or a temperature sensor, etc. Based on the information from the sensor unit 108, the control unit 200 can determine the state of each part of the printer 100 and control each part of the printer 100.

[0029] The printer 100 described so far has shown the case where printing paper P is used as the printing target (i.e., recording medium), but the printing target in the printer 100 is not limited to printing paper P. For example, the printing target may be a roll of cloth or the like.

[0030] Alternatively, the printer 100 may transport the printing paper P on a conveyor belt instead of directly transporting it. By using a conveyor belt, the printer 100 can print on sheets of paper, cut cloth, wood, tiles, etc.

[0031] The printer 100 may also print wiring patterns for electronic devices by ejecting droplets containing conductive particles from the liquid ejection head 1. Alternatively, the printer 100 may produce chemical products by ejecting a predetermined amount of liquid chemical agent or droplets containing a chemical agent from the liquid ejection head 1 toward a reaction vessel or the like.

[0032] The printer 100 may also include a cleaning unit for cleaning the liquid ejection head 1. The cleaning unit cleans the liquid ejection head 1, for example, by wiping or capping.

[0033] Wiping is a process that removes liquid adhering to the liquid discharge head 1 by wiping the surface of the area where the liquid droplets are discharged with a flexible wiper, for example.

[0034] Further, the capping process is carried out as follows, for example. First, a cap is placed to cover the surface of the portion where the droplets are ejected (this is referred to as capping). As a result, a substantially sealed space is formed between the surface of the portion where the droplets are ejected and the cap.

[0035] Next, the ejection of droplets is repeated in such a sealed space. Thereby, it is possible to remove a liquid having a higher viscosity than the standard state or foreign matter that has clogged the ejection holes (nozzles) for ejecting the droplets.

[0036] <Configuration of the liquid ejection head in the line head unit> Subsequently, the configurations of the liquid ejection head 1 and the line head unit 1A according to the first embodiment will be described with reference to FIGS. 3 to 6. FIG. 3 is an exploded perspective view showing the schematic configuration of the liquid ejection head 1 step by step. FIG. 4 is an exploded perspective view showing the schematic configuration of the line head unit 1A step by step. FIG. 5 is a cross-sectional view taken along the line A-A shown in FIG. 3. FIG. 6 is a perspective view showing the schematic configuration of a part of the channel group in the MEMS chip 10.

[0037] The liquid ejection head 1 is assembled in the order of FIGS. 3(a) to 3(c). The line head unit 1A is assembled in the order of FIGS. 4(a) and 4(b) using the eight liquid ejection heads 1 shown in FIG. 3(c). As shown in FIG. 3(a), the liquid ejection head 1 has a MEMS (Micro Electro Mechanical Systems) chip 10 and a COF substrate (Chip on Film) 11 on a film. One end of the MEMS chip 10 is adhered to one end of the COF substrate 11. As a result, as shown in FIG. 3(b), the terminal 143 (see FIG. 5) disposed at one end of the MEMS chip 10 and the wiring (not shown) in the COF substrate 11 are connected, whereby the MEMS chip 10 is electrically connected to the COF substrate 11. Note that the MEMS chip 10 can also be referred to as a ejection chip or an individual flow path member.

[0038] The COF substrate 11 mounts the driving IC 111. The driving IC 111 can communicate with the control unit 200 wirelessly or by wire. Therefore, the driving IC 111 generates a driving signal based on the control signal transmitted from the control unit 200. Then, the driving IC 111 outputs the driving signal to an actuator substrate 3, which will be described later, in the MEMS chip 10 via the COF substrate 11. Thereby, the driving IC 111 can control the driving of the liquid ejection head 1.

[0039] Furthermore, as shown in FIG. 3(b), the liquid ejection head 1 has a manifold member 12. The constituent material of the manifold member 12 may be metal or resin.

[0040] The manifold member 12 may be composed of a plurality of layers of plates in a layer structure or may be a single layer of plate. Each plate has a base portion 12a and a protruding portion 12b. The protruding portion 12b is a portion protruding from the central region when the base portion 12a is divided into three in the longitudinal direction. The longitudinal direction of the base portion 12a is longer than the longitudinal direction of the MEMS chip 10. The manifold member 12 is joined to the MEMS chip 10 such that the base portion 12a is positioned above the MEMS chip 10. Thereby, as shown in FIG. 3(c), a super-small integrated module called a so-called front end module (Front End Module: FEM) is configured.

[0041] As an example of the layered structure of the manifold member 12, referring to Figure 5, which shows a cross-section along line A-A in Figure 3(c), the manifold member 12 has a structure in which the top layer plate 121a, the middle layer plate 121b, and the bottom layer plate 121c are stacked from top to bottom. The top layer plate 121a has a filter 121f. The upper part of the filter 121f is connected to the reservoir flow path of the reservoir member 14 (see Figure 4(b)). The filter 121f is located at the protruding portion 12b and filters out impurities from the liquid in the reservoir flow path. The top layer plate 121a has a flow path 121 through which the filtered liquid flows. The bottom layer plate 121c has a common flow path 123 along the longitudinal direction of the base portion 12a. The intermediate plate 121b is located between the uppermost plate 121a and the lowermost plate 121c, and has a hole 122 that connects the flow path 121 of the uppermost plate 121a with the common flow path 123.

[0042] As shown in Figure 4(a), eight front-end modules (FEMs) are arranged in a staggered pattern, and eight manifold members 12 are joined together in a line. This positions eight common channels 123 above the eight MEMS chips 10. Also, as shown in Figure 4(b), a nozzle cover 13 is joined below the eight MEMS chips 10, covering the eight MEMS chips 10. This covers and protects the eight MEMS chips 10. The longitudinal direction of the nozzle cover 13 is longer than the length of the eight manifold members 12. The nozzle cover 13 has eight rectangular openings 133. The openings 133 are positioned to correspond to the eight nozzles 41 (see Figure 5) of the eight MEMS chips 10, allowing liquid to be discharged from the eight nozzles 41.

[0043] Furthermore, the liquid discharge head 1 has a reservoir member 14 with a reservoir channel (not shown) inside. The longitudinal direction of the reservoir member 14 is longer than the length of the eight manifold members 12 on the line and is approximately equal to the length of the nozzle cover 13. The reservoir member 14 is joined to the eight manifold members 12 so as to be located above the eight manifold members 12. As a result, the reservoir channel is located on the common channel 123 of the eight manifold members 12.

[0044] The reservoir member 14 is an injection-molded product made of resin. Here, "made of resin" means that it is made of resin, and includes products that are mainly composed of resin and contain small amounts of impurities. The reservoir member 14 supplies liquid by dividing it from the reservoir channel to eight common channels 123.

[0045] Liquid supply ports 15 and liquid discharge ports 16 are located at both ends of the reservoir member 14 in the Y-axis direction. Liquid is supplied from the liquid supply ports 15 to the reservoir flow path within the reservoir member 14. The liquid discharge head 1 temporarily stores the liquid supplied to the reservoir member 14 in the reservoir flow path, supplies it to eight common flow paths 123 that branch off from the reservoir flow path, and discharges it from the nozzle 41 through the flow path in the MEMS chip 10 located below each common flow path 123. The liquid discharge head 1 discharges any liquid that was not supplied from the reservoir flow path of the reservoir member 14 to each common flow path 123 from the liquid discharge ports 16.

[0046] Furthermore, the liquid ejection head 1 may collect liquid from the liquid outlet 16 while printing is in progress. Doing so makes it less likely for air bubbles to accumulate in the reservoir flow path within the reservoir member 14. In addition, the temperature of the liquid ejection head 1 can be stabilized by supplying liquid adjusted to a constant temperature. The collected liquid may be passed through a filter or the like and then supplied back to the liquid ejection head 1. In other words, the liquid ejection head 1 may circulate the liquid. The supply and collection of liquid to and from the liquid ejection head 1, or the circulation of liquid, may be controlled by the control unit 200.

[0047] The above description shows an example of the configuration of the liquid discharge head 1. The configuration in Figure 4(b) may further include a circuit board, a heat sink for dissipating heat generated by the circuit board, cover members for the circuit board and heat sink, etc. For convenience, descriptions of these components have been omitted.

[0048] <Channel Group> The thickness direction of the MEMS chip 10 is defined as the Z-axis direction, and the positive Z-axis direction is defined as the vertically upward direction. The longitudinal direction (Y-axis direction) of the MEMS chip 10 is also called the row direction, and the short direction (X-axis direction) of the MEMS chip 10 is also called the column direction. In the example in Figure 5, the MEMS chips 10 located on both sides of line O show cross-sections of two channels arranged symmetrically with respect to line O.

[0049] A channel refers to a single unit configuration that includes a flow path extending from the supply path 51 through the connecting passage 52 and pressure chamber 131 to the nozzle 41, an actuator 30, and a diaphragm 38. A group of channels consisting of 100 to 2000 channels in the row direction and two channels arranged in the column direction is called a channel group 10a, 10b. Channel groups 10a and 10b are arranged symmetrically with respect to line O shown in Figure 5. However, the number of channel groups can be changed as appropriate.

[0050] The MEMS chip 10 has a substrate in which a support substrate 2, an actuator substrate 3, and a nozzle substrate 4 are stacked from top to bottom. However, the three substrates, the support substrate 2, the actuator substrate 3, and the nozzle substrate 4, may be integrated into a single unit. Alternatively, only the two substrates, the actuator substrate 3 and the nozzle substrate 4, may be integrated into a single unit.

[0051] The support substrate 2 has a supply passage 51. The actuator substrate 3 has a bonding layer 3a and a pressure chamber substrate 3b stacked from top to bottom. The bonding layer 3a has a communication passage 52, an actuator 30, and a diaphragm 38. The diaphragm 38 is positioned on the lower surface of the actuator 30. The area around the actuator 30, other than the lower surface, is covered by a space 132. The area around the actuator 30, other than the lower surface, is covered by a space 132. The pressure chamber substrate 3b has a pressure chamber 131. The nozzle substrate 4 has nozzles 41 for discharging liquid. The pressure chambers 131 are arranged in a row of 100 to 2000 units and in a column of 2 units, for a total of 200 to 4000 units. Corresponding to the pressure chambers 131, there are 100 to 2000 nozzles 41 in the row and 2 units in the column, for a total of 200 to 4000 nozzles 41, and the same number of supply passages 51 and communication passages 52 as there are nozzles 41. In this configuration, the supply passages 51, connecting passages 52, pressure chambers 131, and nozzles 41, arranged in two rows of 100 to 2000 each along the row direction according to this embodiment, form channel groups 10a and 10b. The common flow path 123 is a common flow path for 200 to 4000 channels and is connected to the 200 to 4000 supply passages 51, which are arranged in two rows of 100 to 2000 each, and supplies liquid to the 200 to 4000 nozzles 41. In the plan view of the actuator substrate 3 shown in Figure 9, parts of the channel groups 10a and 10b, which are arranged in two rows in the row direction, are shown within the frames, respectively.

[0052] The bottom plate 121c is located on the support substrate 2. The upper surface of the support substrate 2 forms the bottom of the common channel 123. However, the bottom plate 121c may have a bottom and the common channel 123 may be located inside it. In this case, a hole communicating with the supply channel 51 may be provided in the bottom of the bottom plate 121c. The supply channel 51 penetrates the support substrate 2 in the Z-axis direction.

[0053] The bonding layer 3a is bonded to the support substrate 2. The communication passage 52 penetrates the bonding layer 3a and is connected to the supply passage 51. The actuator substrate 3 includes a bonding layer 3a that is bonded to the first substrate, and the bonding layer 3a has a communication passage 52 that is connected to the supply passage 51 and supplies liquid to the nozzle 41.

[0054] The pressure chamber 131 is located below the actuator 30 and is connected to the communication passage 52, which connects the communication passage 52 to the nozzle 41. The pressure chamber 131 is a space enclosed by the diaphragm 38, the upper surface of the nozzle substrate 4, and the solid 39, and extends from a position below the communication passage 52 to a position above the nozzle 41.

[0055] Figure 6 is a perspective view showing a schematic configuration of a part of channel group 10a, with channel group 10b omitted. As shown in Figure 6, the actuator substrate 3 can be electrically connected to the outside through terminal 143 by electrical junctions 141 and 142 located at one end of channel group 10a. One end of channel group 10a is located on the opposite side of channel group 10b.

[0056] <Configuration of Actuator Substrate> The detailed configuration of the actuator substrate 3 will be described with reference to Figures 7 and 8. Figure 7 is a cross-sectional view showing the detailed configuration of the actuator substrate 3. Figure 8 is a schematic plan view showing the actuator substrate 3. Note that Figure 7 shows the configuration of channel group 10a, and the configuration of channel group 10b is omitted. Since the configuration of channel group 10a and the configuration of channel group 10b are the same, the explanation of the configuration of channel group 10b will be omitted.

[0057] The thickness (length in the Z-axis direction) of the support substrate 2 is, for example, 200 to 400 μm. The thickness (length in the Z-axis direction) of the actuator substrate 3 is, for example, 30 to 75 μm. The thickness (length in the Z-axis direction) of the nozzle substrate 4 is, for example, 75 to 150 μm. For convenience, the thickness of the actuator substrate 3 is given as being greater than the thickness of the nozzle substrate 4, but in reality, the thickness of the nozzle substrate 4 is greater than the thickness of the actuator substrate 3. The constituent materials of the support substrate 2, pressure chamber substrate 3b, and nozzle substrate 4 may be Si.

[0058] The bonding layer 3a has a bonding film 31, an actuator 30, and a diaphragm 38. The bonding film 31 is bonded to the support substrate 2 on the upper surface of the bonding layer 3a. The communication passage 52 penetrates the bonding film 31, and the side surface of the communication passage 52 is the SiO of the bonding film 31. ２The bonding film 31 is formed of Si. The connecting passage 52 is located below the supply passage 51 and communicates with the supply passage 51. The bonding of the support substrate 2 and the bonding film 31 may be done by room temperature direct bonding using intermolecular forces, adhesive bonding, or gold-gold bonding. The bonding of the pressure chamber substrate 3b and the nozzle substrate 4 may also be done by room temperature direct bonding. Since the pressure chamber substrate 3b and the nozzle substrate 4 are formed from the same constituent material, they are easy to bond, and other bonding methods may also be used.

[0059] The pressure chamber 131 is located below the communication passage 52 and communicates with the communication passage 52. The pressure chamber 131 has an inlet passage 53. The inlet passage 53 is the connection portion of the pressure chamber 131 that communicates with the communication passage 52 at the connection portion between the communication passage 52 and the pressure chamber 131. The connection portion between the communication passage 52 and the pressure chamber 131 is the portion where the bonding layer 3a and the pressure chamber substrate 3b are connected at the boundary between the bonding layer 3a and the pressure chamber substrate 3b. As a result, the bonding layer 3a and the pressure chamber substrate 3b communicate with each other.

[0060] The pressure chamber 131 is connected to the communication passage 52 by an inlet passage 53 and extends below the actuator 30 on the positive X-axis side. Furthermore, there is a one-to-one correspondence between the pressure chamber 131 of each channel and the actuator 30, forming a single hollow region 3A within the actuator substrate 3. Liquid is stored within the pressure chamber 131. Each channel's pressure chamber 131 corresponds one-to-one with the supply passage 51, the communication passage 52, and the nozzle 41, and liquid is supplied from the common passage 123 of the manifold member 12. The common passage 123 supplies liquid to 200 to 4000 channels.

[0061] The thickness of the bonding layer 3a may be several μm to 20 μm. The thickness of the pressure chamber substrate 3b may be 30 to 75 μm. Examples of materials used to construct the pressure chamber substrate 3b include Si.

[0062] For example, the depth (length in the Z-axis direction) of the supply passage 51 is equal to the thickness of the support substrate 2 and may be 200 to 400 μm. The depth (length in the Z-axis direction) of the communication passage 52 is equal to the length from the upper surface of the bonding film 31 to the lower surface of the diaphragm 38, i.e., the thickness of the bonding layer 3a and may be several μm to 20 μm. The depth (length in the Z-axis direction) of the pressure chamber 131 is equal to the thickness of the pressure chamber substrate 3b and may be 30 to 75 μm.

[0063] The solid core 39 is located around each hollow region 3A between the diaphragm 38 and the nozzle substrate 4, and has the function of separating each hollow region 3A from other hollow regions 3A. Examples of materials that make up the solid core 39 include silicon.

[0064] The diaphragm 38 is located above the pressure chamber 131 and above the solid 39. The diaphragm 38 has openings in parts corresponding to each pressure chamber 131. Liquid is supplied to the pressure chamber 131 from the common channel 123 through these openings. The openings in the diaphragm 38 form part of the communication passage 52.

[0065] The thickness of the diaphragm 38 may be, for example, 1 μm or more and 10 μm or less. The diaphragm 38 in this embodiment is a single layer, but is not limited to this. For example, the diaphragm 38 may have a multilayer structure. Also, the diaphragm 38 may have a multilayer structure locally, for example, only on the solid 39. That is, the thickness of the diaphragm 38 on the solid 39 may be thicker than the thickness of the diaphragm 38 on the pressure chamber 131. Examples of constituent materials for the diaphragm 38 are Si, SiO ２ These are some examples.

[0066] The actuator 30 is provided on a diaphragm 38 corresponding to the pressure chamber 131. The actuator 30 has a common electrode 35 (an example of a lower electrode), a piezoelectric element 36, and individual electrodes 37 (an example of an upper electrode). The actuator 30 is provided in a 1:1 relationship with the pressure chamber 131. The actuator 30 has the common electrode 35 located on the diaphragm 38 corresponding to the pressure chamber 131, the piezoelectric element 36 located on the common electrode 35, and the individual electrodes 37 located on the piezoelectric element 36, but is not limited to this. For example, the individual electrodes 37, piezoelectric element 36, and common electrode 35 may be provided on the diaphragm 38 in that order.

[0067] The common electrode 35 is provided across the actuators 30 of multiple channels in each channel group 10a, 10b in a plan view of the actuator substrate 3 shown in Figure 8, but is not limited to this. For example, the common electrode 35 may be provided individually corresponding to each actuator 30 of each channel. The thickness of the common electrode 35 may be, for example, 0.1 to 1 μm. The constituent material of the common electrode 35 may be, for example, a metallic material such as Pt.

[0068] The piezoelectric elements 36 are individually provided corresponding to each pressure chamber 131, but are not limited to this arrangement. For example, the piezoelectric elements 36 may be provided across multiple channel pressure chambers 131 in a plan view of the actuator substrate 3. In the piezoelectric element 36, the portion sandwiched between the individual electrodes 37 and the common electrode 35 is polarized in the thickness direction along the Z-axis. Therefore, for example, when a voltage is applied in the polarization direction of the piezoelectric element 36 by the individual electrodes 37 and the common electrode 35, the piezoelectric element 36 contracts in a direction along the diaphragm 38. This contraction causes the piezoelectric element 36 to displace so that it becomes convex toward the pressure chamber 131. Along with the displacement of the piezoelectric element 36, the diaphragm 38 located on the pressure chamber 131 also displaces. As a result, pressure is applied to the liquid in the pressure chamber 131. This causes the liquid to be discharged from the pressure chamber 131 through the nozzle 41.

[0069] The thickness of the piezoelectric element 36 may be 1 μm or more and 10 μm or less. The constituent material of the piezoelectric element 36 is, for example, Pb(Zr,Ti)O ３ System, NaNbo ３ system, BaTiO ３System, (BiNa)NbO ３ System, BiNaNB ５ O １５ Examples of the ceramic constituent material having ferroelectricity include systems such as this.

[0070] The individual electrodes 37 are provided individually corresponding to each pressure chamber 131. The thickness of the individual electrodes 37 may be 0.05 μm or more and 1 μm or less. Examples of the constituent material of the individual electrodes 37 include metal constituent materials such as Pt.

[0071] The electrical joints 141 and 142 shown in FIGS. 6 and 8 are located on the end portions in the X-axis direction on the actuator substrate 3. The tips of the electrical joints 141 and 142 are formed by a plurality of terminals 143. The plurality of terminals 143 are electrically connected to the actuator substrate 3.

[0072] As shown in FIG. 7, the bonding layer 3a has a diaphragm 38 located on the pressure chamber substrate 3b, an actuator 30 located on the diaphragm 38, an insulating film 33, and a bonding film 31. The insulating film 33 is located on at least a part of the actuator 30. The bonding film 31 is located on at least a part of the insulating film 33. The insulating film 33 is provided on the actuator 30 in order to prevent a short circuit between the actuators 30 of each channel and the actuators 30 of other channels or wirings such as the lead-out wiring 144.

[0073] The bonding film 31 is located under the support substrate 2 and bonds the support substrate 2 and the bonding layer 3a. The thickness of the bonding film 31 may be, for example, several μm to 20 μm. Also, examples of the constituent material of the bonding film 31 include materials such as SiO ２ and the like.

[0074] As shown in FIG. 7, under the bonding film 31, a protective layer 32, an insulating film 33, and a common electrode 35 are laminated in this order from above. The thickness of the protective layer 32 may be, for example, 0.1 to 1 μm. Also, examples of the constituent material of the protective layer 32 include materials such as SiN.

[0075] The thickness of the insulating film 33 may be, for example, 0.1 to 1 μm. Also, examples of the constituent material of the insulating film 33 include materials such as SiO ２These are some examples of materials.

[0076] The actuator 30 may have an adhesion layer between the common electrode 35 and the piezoelectric element 36, and between the individual electrodes 37 and the piezoelectric element 36. The thickness of the adhesion layer may be, for example, 0.05 μm. The constituent material of the adhesion layer may be, for example, a material such as SiN.

[0077] The protective layer 32 and the insulating film 33 are located on at least a portion of the actuator 30. The upper surface of the actuator 30 is exposed to the space 132, except for the outer periphery of the actuator 30.

[0078] The lead wires 144 are electrically connected to the individual electrodes 37 and are wires that extend from each individual electrode 37. In the example shown in Figure 7, the lead wires 144 are positioned between the protective layer 32 and the insulating film 33 and extend from the portion corresponding to the pressure chamber 131 to the portion corresponding to the solid 39. The thickness of the lead wires 144 may be, for example, 0.1 μm or more and 1 μm or less. The constituent material of the lead wires 144 may be, for example, Au.

[0079] The protective layer 32 protects the actuator 30 beneath the bonding film 31. The insulating film 33 is provided on the diaphragm 38 to cover the lead wiring 144 in order to reduce the possibility of corrosion of the lead wiring 144. The insulating film 33 is in close contact with the diaphragm 38, which generally corresponds to the solid 39 excluding the pressure chamber 131.

[0080] The bonding film 31, protective layer 32, insulating film 33, common electrode 35, individual electrode 37, and lead wiring 144 according to this embodiment may be deposited on each layer using the CVD method. By using the CVD method, the step coverage is improved, so the coverage of each layer and lead wiring 144 is improved, and the possibility of corrosion of each layer and lead wiring 144 can be further reduced. However, each layer and lead wiring 144 according to this embodiment may be deposited using the sputtering method, not limited to the CVD method. By using the sputtering method, particles that will become the constituent material of each layer and lead wiring 144 will adhere to the surface. Therefore, the adhesion between each layer and the diaphragm 38 and lead wiring 144 can be improved.

[0081] The wiring of the actuator substrate 3 according to this embodiment will be further described with reference to Figure 8. In a plan view, the actuator substrate 3 shown in Figure 8 shows a portion of the channel groups 10a and 10b arranged in two rows. 100 to 2000 lead wires 144 are located on each of the channel groups 10a and 10b.

[0082] The number of lead wires 144 on each channel group 10a, 10b may be set as appropriate. Each lead wire 144, when viewed from above, is connected to an individual electrode 37 corresponding to the pressure chamber 131 and is led out in the positive X-axis direction. The lead wire 144 led out from channel group 10b is connected to an electrical junction 142. The electrical junction 142 runs along the positive X-axis direction within the region of channel group 10a and is electrically connected to a terminal 143 of an individual terminal region 201 formed in the positive X-axis direction of channel group 10a. The lead wire 144 led out from channel group 10a in the positive X-axis direction is connected to an electrical junction 141. The electrical junction 141 runs along the positive X-axis direction and is electrically connected to a terminal 143 of an individual terminal region 201.

[0083] Therefore, each actuator 30 of channel groups 10a and 10b receives a drive signal from the drive IC 111 on the COF substrate 11 via terminals 143 through electrical junctions 141 and 142. Each individual electrode 37 of each actuator 30 is supplied with an individual drive potential via lead wiring 144 based on the drive signal (see Figure 5).

[0084] With this configuration, each actuator 30 of channel groups 10a and 10b receives a drive signal corresponding to a desired control signal from the control unit 200 (Figure 8(1)), and displaces the piezoelectric element 36 so that it protrudes toward the pressure chamber 131 according to the drive signal. As the piezoelectric element 36 is displaced, the diaphragm 38 located on the pressure chamber 131 is displaced, and pressure is applied to the liquid in the pressure chamber 131. As a result, liquid is discharged from each pressure chamber 131 through each nozzle 41. This causes the drive IC 111 to drive the liquid discharge head 1.

[0085] The common electrode 35 is electrically connected to the ground connection 145 of the ground region 202 via the common wiring 146 (Figure 8(2)). As a result, the common electrode 35 is supplied with ground potential. Ground potential means 0V. Note that the common wiring 146 is not shown in Figures 5 to 7.

[0086] <Configuration of Piezoelectric Body and Insulating Film> Next, the configuration of the piezoelectric body 36 and the insulating film 33 will be described with reference to Figure 9. Figure 9 is an enlarged view of the area around the end 36T of the piezoelectric body 36 according to the first embodiment. Figure 9 shows a cross-section of the piezoelectric body 36 perpendicular to the short direction (Y-axis direction). For convenience, the protective layer 32 is not shown in Figure 9. Here, the end 36T of the piezoelectric body 36 is, for example, the region closest to the positive Y-axis and the region closest to the negative Y-axis when the piezoelectric body 36 is divided into five equal regions in the short direction (here, the Y-axis direction). Furthermore, the end T of the piezoelectric body 36 may also include the region closest to the positive X-axis and the region closest to the negative X-axis when the piezoelectric body 36 is divided into ten equal regions in the longitudinal direction (here, the X-axis direction). Alternatively, the end 36T of the piezoelectric body 36 may be defined as the region of the piezoelectric body 36 that does not overlap with the individual electrodes 37 when viewed from above.

[0087] As shown in Figure 9, a common electrode 35 is located on the diaphragm 38, a piezoelectric element 36 is located on the common electrode 35, and individual electrodes 37 are located on the piezoelectric element 36.

[0088] The end portion 36T of the piezoelectric element 36 is inclined in stages toward the end portion of the common electrode 35 in a cross-sectional view. Specifically, the end portion 36T of the piezoelectric element 36 has a first portion 36a, a second portion 36b, and a third portion 36c in a cross-sectional view. The first portion 36a is the portion sandwiched above and below by the second portion 36b and the third portion 36c, the second portion 36b is the portion that contacts the first portion 36a and the common electrode 35, and the third portion 36c is the portion that contacts the first portion 36a and the individual electrode 37. The side surfaces of the first portion 36a, the second portion 36b, and the third portion 36c are inclined with respect to the surface of the common electrode 35. The inclination angle θ2 of the side surface of the second portion 36b is smaller than the inclination angle θ1 of the side surface of the first portion 36a. In other words, the end portion 36T of the piezoelectric element 36 is inclined in stages toward the end of the common electrode 35 such that the inclination angle θ2 of the side surface of the second portion 36b, which is closer to the end of the common electrode 35 than the first portion 36a, is minimized. The inclination angle θ1 of the side surface of the first portion 36a can be, for example, about 30° to 70°. In contrast, the inclination angle θ2 of the side surface of the second portion 36b can be, for example, about 5° to 20°. Here, the inclination angle of the side surface is the angle of the side surface of the piezoelectric element 36 when the cross-section of the piezoelectric element 36 perpendicular to the surface of the common electrode 35 is viewed from a direction perpendicular to the said cross-section. In the first embodiment, since the surface of the common electrode 35 is located in the XY plane, the cross-section perpendicular to the surface of the common electrode 35 is a plane that includes the Z axis. Figure 9 shows a cross-section of the XZ plane (a cross-section perpendicular to the short side direction (Y axis direction) of the piezoelectric element 36) among the planes that include the Z axis. Since the Y-axis direction is perpendicular to the cross-section of the XZ plane, the angle when viewing the cross-section of the XZ plane from the Y-axis direction becomes the inclination angle. Furthermore, the inclination angle is defined as the angle of the line connecting the start and end points of the part of interest with respect to the surface of the common electrode 35. For example, the second part 36b is defined as the angle of the line connecting the point where it touches the common electrode 35 to the point where it touches the first part 36a with respect to the surface of the common electrode 35. In other words, irregularities (e.g., surface roughness) between the point where the second part 36b touches the common electrode 35 and the point where it touches the first part 36a do not result in the inclination angle of the second part 36b.

[0089] In the first embodiment, the inclination angle θ2 of the side surface of the second portion 36b is smaller than the inclination angle θ1 of the side surface of the first portion 36a. This reduces the concentration of voltage from the individual electrodes 37 and the common electrode 35 to the end 36T of the piezoelectric element 36 (particularly the second portion 36b), and the amount of displacement at the end 36T of the piezoelectric element 36 is reduced. As a result, the liquid discharge head 1 is less susceptible to shear stress (for example, in the X-axis direction) acting on the piezoelectric element 36 from the common electrode 35.

[0090] On the other hand, in the first portion 36a as well, if the inclination angle θ1 of the side surface is small, the size of the piezoelectric body 36 may increase in the direction along the surface of the common electrode 35 (for example, in the X-axis direction) before the thickness of the piezoelectric body 36 reaches the specified thickness. Therefore, in the first embodiment, since the inclination angle θ1 of the side surface of the first portion 36a is larger than the inclination angle θ2 of the side surface of the second portion 36b, the thickness of the piezoelectric body 36 can be easily brought closer to the specified thickness compared to the case where the side surface of the end 36T of the piezoelectric body 36 is inclined at a constant angle with respect to the surface of the common electrode 35. Thus, the liquid discharge head 1 can reduce the possibility of the size of the piezoelectric body 36 increasing in the direction along the surface of the common electrode 35 (for example, in the X-axis direction). As a result, the liquid discharge head 1 can reduce the stress on the end 36T of the piezoelectric body 36 while reducing the increase in the size of the piezoelectric body 36.

[0091] Furthermore, as shown in Figure 9, the piezoelectric element 36 may have a buffer layer 361 and a piezoelectric layer 362. The buffer layer 361 is located on the common electrode 35. The buffer layer 361 has the function of controlling the crystal orientation of the piezoelectric layer 362 and reducing residual stress between the piezoelectric layer 362 and the common electrode 35. Examples of materials that make up the buffer layer 361 include oxides containing Sr and Ru, and oxides containing La and Ni.

[0092] The piezoelectric layer 362 is located on top of the buffer layer 361. The constituent material of the piezoelectric layer 362 is, for example, Pb(Zr,Ti)O ３ System, NaNbo ３ system, BaTiO ３ System, (BiNa)NboO ３ System, BiNaNB ５ O１５ Examples include ferroelectric ceramic constituent materials such as [specific type of ceramic material]. The piezoelectric layer 362 may consist of one layer or multiple layers.

[0093] The boundary 36B between the first portion 36a and the second portion 36b may be located within the thickness range of the buffer layer 361. That is, the inclination angle of the end portion 36T of the piezoelectric element 36 may change within the buffer layer 361. By having the boundary 36B located within the buffer layer 361, the thickness of the piezoelectric layer 362 located on top of the buffer layer 361 can be easily brought closer to a specified thickness. This reduces the possibility of the size of the piezoelectric element 36 increasing in the direction along the surface of the common electrode 35.

[0094] The buffer layer 361 may be thinner than the piezoelectric layer 362 and the common electrode 35. The thickness of the piezoelectric layer 362 may be, for example, 1 to 10 μm. The thickness of the common electrode 35 may be, for example, 0.1 to 1 μm. In contrast, the thickness of the buffer layer 361 may be, for example, 0.01 to 0.1 μm. Because the thickness of the buffer layer 361 is smaller than the thickness of the piezoelectric layer 362 and the common electrode 35, the boundary 36B between the first portion 36a and the second portion 36b is located within the relatively smaller buffer layer 361. Therefore, the possibility of the size of the piezoelectric body 36 increasing in the direction along the surface of the common electrode 35 can be further reduced.

[0095] Furthermore, the length l2 of the side surface of the second portion 36b in the direction along the surface of the common electrode 35 (here, the X-axis direction) may be smaller than the length l1 of the side surface of the first portion 36a in the direction along the surface of the common electrode 35. The length l1 of the side surface of the first portion 36a in the direction along the surface of the common electrode 35 may be, for example, 0.5 to 2 μm. In contrast, the length l2 of the side surface of the second portion 36b in the direction along the surface of the common electrode 35 may be, for example, 0.05 to 0.5 μm. By relatively reducing the length l2 of the side surface of the second portion 36b in the direction along the surface of the common electrode 35, the thickness of the piezoelectric element 36 can be easily brought closer to the specified thickness. Therefore, the liquid discharge head 1 can further reduce the possibility of the size of the piezoelectric element 36 increasing in the direction along the surface of the common electrode 35.

[0096] Furthermore, the surface roughness of the side surface of the first portion 36a may be greater than that of the side surface of the second portion 36b. This increases the surface area of ​​the end portion 36T of the piezoelectric element 36 between the individual electrodes 37 and the common electrode 35, thereby increasing the length of the current path between the individual electrodes 37 and the common electrode 35. Therefore, the liquid discharge head 1 can reduce the occurrence of short circuits between the individual electrodes 37 and the common electrode 35 via the end portion 36T of the piezoelectric element 36. In this specification, "surface roughness" refers to the maximum height roughness R based on JIS B0601:2013. Ｚ For example, it can be measured using a confocal laser microscope.

[0097] Furthermore, the sides of the first portion 36a, the second portion 36b, and the third portion 36c may have deposits containing the material of the piezoelectric element 36. The sides of the first portion 36a, the second portion 36b, and the third portion 36c are formed by etching the end portion 36T of the piezoelectric element 36. When etching the end portion 36T of the piezoelectric element 36, by-products or cuttings containing the material of the piezoelectric element 36 are deposited on the sides of the first portion 36a, the second portion 36b, and the third portion 36c, forming deposits containing the material of the piezoelectric element 36. As a result of these deposits, the surface area of ​​the end portion 36T of the piezoelectric element 36 between the individual electrodes 37 and the common electrode 35 is increased, and the length of the current path between the individual electrodes 37 and the common electrode 35 can be increased. Therefore, the liquid discharge head 1 can further reduce the occurrence of short circuits between the individual electrodes 37 and the common electrode 35 via the end portion 36T of the piezoelectric element 36. In this specification, "surface roughness" refers to the maximum height roughness R based on JIS B0601:2013, including the deposit containing the piezoelectric material 36. Ｚ That is the case.

[0098] Furthermore, the inclination angle θ3 of the side surface of the third portion 36c may be smaller than the inclination angle θ1 of the side surface of the first portion 36a. The inclination angle θ1 of the side surface of the first portion 36a can be, for example, about 30° to 70°. In contrast, the inclination angle θ3 of the side surface of the third portion 36c can be, for example, about 1° to 10°. By relatively reducing the inclination angle θ3 of the side surface of the third portion 36c that is in contact with the individual electrodes 37, the surface area of ​​the end 36T of the piezoelectric body 36 increases. When the surface area of ​​the end 36T of the piezoelectric body 36 increases, the adhesion between the insulating film 33 located on the end 36T of the piezoelectric body 36 and the end 36T of the piezoelectric body 36 improves.

[0099] Furthermore, the thickness t1 of the first portion 36a may be greater than the thickness t2 of the second portion 36b and the thickness t3 of the third portion 36c. By relatively increasing the thickness t1 of the first portion 36a, which has a relatively large inclination angle θ1, the thickness of the piezoelectric element 36 can be more easily brought closer to the specified thickness. Therefore, the liquid discharge head 1 can further reduce the possibility of the size of the piezoelectric element 36 increasing in the direction along the surface of the common electrode 35 (for example, in the X-axis direction).

[0100] Furthermore, the insulating film 33 is located on the common electrode 35, on the end 36T of the piezoelectric element 36, and on at least a portion of the individual electrodes 37. The insulating film 33 continuously covers the side surface of the second portion 36b and the common electrode 35. By continuously covering the side surface of the second portion 36b, which has a relatively small inclination angle θ2, and the common electrode 35 with the insulating film 33, the adhesion between the insulating film 33 and the common electrode 35 and the end 36T of the piezoelectric element 36 is improved.

[0101] (Second Embodiment) Figure 10 is an enlarged view showing the area around the end 36T of the piezoelectric element 36 according to the second embodiment. Figure 10 shows a cross-section of the piezoelectric element 36 perpendicular to the short direction (Y-axis direction). For convenience, the protective layer 32 is not shown in Figure 10.

[0102] As shown in Figure 10, the third portion 36c has an exposed region 36d on the surface 36c1 that contacts the individual electrode 37, which is exposed from the individual electrode 37 and connected to the side surface of the third portion 36c. In other words, the exposed region 36d is the region located between the individual electrode 37 and the side surface of the third portion 36c when viewed from above. The exposed region 36d is a flat surface that is not inclined with respect to the direction along the surface of the common electrode 35 (here, the X-axis direction). However, the exposed region 36d may be an inclined surface that is inclined with respect to the direction along the surface of the common electrode 35 (here, the X-axis direction). If the exposed region 36d is an inclined surface, the inclination angle of the exposed region 36d may be smaller than the inclination angle θ3 of the side surface of the third portion 36c.

[0103] Thus, the third portion 36c may have an exposed region 36d. This configuration increases the surface area of ​​the end portion 36T of the piezoelectric element 36. When the surface area of ​​the end portion 36T of the piezoelectric element 36 increases, the adhesion between the insulating film 33 located on the end portion 36T of the piezoelectric element 36 and the end portion 36T of the piezoelectric element 36 is improved.

[0104] (Third Embodiment) Figure 11 is an enlarged view of the area around the end 36T of the piezoelectric element 36 according to the third embodiment. Figure 11 shows a cross-section of the piezoelectric element 36 perpendicular to the short direction (Y-axis direction). For convenience, the protective layer 32 is not shown in Figure 11.

[0105] As shown in Figure 11, the first portion 36a has an exposed region 36e on the surface 36a1 that contacts the individual electrodes 37, which is exposed from the individual electrodes 37 and connected to the side surface of the first portion 36a. The exposed region 36e in the third embodiment is a flatter region with respect to the direction along the surface of the common electrode 35 (here, the X-axis direction) than the exposed region 36d in the second embodiment. Therefore, the third embodiment is an embodiment in which the inclination angle θ3 of the side surface of the third portion 36c in the second embodiment is smaller than the inclination angle θ2 of the side surface of the second portion 36b. Furthermore, the third embodiment may be an embodiment in which the inclination angle θ3 of the side surface of the third portion 36c in the embodiment shown in Figure 10 is set to 0°. In other words, the exposed region 36e may be a flat surface that is not inclined with respect to the direction along the surface of the common electrode 35 (here, the X-axis direction). In the third embodiment, because the exposed region 36e is flat, it is easier to make the thickness of the layer located on the exposed region 36e, for example, the insulating film 33, uniform.

[0106] The length l3 of the exposed region 36e in the direction along the surface of the common electrode 35 (here, in the X-axis direction) is greater than the sum of the length l2 of the side surface of the second portion 36b in the direction along the surface of the common electrode 35 and the length l1 of the side surface of the first portion 36a in the direction along the surface of the common electrode 35. For example, length l3 is five times or more the sum of length l2 and length l1. Furthermore, the length l3 of the exposed region 36e in the direction along the surface of the common electrode 35 may be greater than either the length l2 of the side surface of the second portion 36b in the direction along the surface of the common electrode 35, or the length l1 of the side surface of the first portion 36a in the direction along the surface of the common electrode 35. For example, length l3 is ten times or more the sum of length l2 and length l1. In an actuator 30 with this configuration, the distance between the individual electrodes 37 and the common electrode 35 along the side surface of the piezoelectric element 36 is longer compared to an actuator 30 in which the length l3 is smaller than the sum of the lengths l2 and l1, or either l2 or l1. Therefore, the possibility of electrical leakage between the individual electrodes 37 and the common electrode 35 can be reduced.

[0107] As described above, the liquid discharge head according to the embodiment (for example, liquid discharge head 1) comprises a pressure chamber (for example, pressure chamber 131), a diaphragm (for example, diaphragm 38), a lower electrode (for example, common electrode 35), a piezoelectric element (for example, piezoelectric element 36), and an upper electrode (for example, individual electrode 37). The diaphragm is located above the pressure chamber. The lower electrode is located above the diaphragm. The piezoelectric element is located above the lower electrode. The upper electrode is located above the piezoelectric element. In cross-sectional view, the end of the piezoelectric element (for example, end 36T) has a first portion (for example, first portion 36a) whose side surface is inclined with respect to the surface of the lower electrode, and a second portion (for example, second portion 36b) which is in contact with the first portion and the lower electrode and whose side surface is inclined with respect to the surface of the lower electrode. The inclination angle of the side surface of the second portion (for example, inclination angle θ2) is smaller than the inclination angle of the side surface of the first portion (for example, inclination angle θ1).

[0108] Therefore, according to the liquid discharge head of the embodiment, it is possible to reduce stress on the ends of the piezoelectric body while reducing the increase in the size of the piezoelectric body.

[0109] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Indeed, the embodiments described above can be embodied in a variety of forms. Furthermore, the embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0110] 1 Liquid discharge head 2 Support substrate 3 Actuator substrate 4 Nozzle substrate 10 MEMS chip 10a, 10b Channel group 12 Manifold member 30 Actuator 33 Insulating film 35 Common electrode 36 Piezoelectric element 36a First part 36b Second part 36B Boundary 36c Third part 36d Exposed area 36T End 37 Individual electrode 38 Diaphragm 100 Printer 131 Pressure chamber 200 Control unit

Claims

1. A liquid discharge head comprising: a pressure chamber; a diaphragm located above the pressure chamber; a lower electrode located above the diaphragm; a piezoelectric element located above the lower electrode; and an upper electrode located above the piezoelectric element, wherein, in cross-sectional view, the end of the piezoelectric element has a first portion whose side surface is inclined with respect to the surface of the lower electrode; and a second portion that is in contact with the first portion and the lower electrode, and whose side surface is inclined with respect to the surface of the lower electrode, and the inclination angle of the side surface of the second portion is smaller than the inclination angle of the side surface of the first portion.

2. The liquid dispensing head according to claim 1, wherein the piezoelectric material has a buffer layer located above the lower electrode and a piezoelectric layer located above the buffer layer, and the boundary between the first portion and the second portion is located within the buffer layer.

3. The liquid dispensing head according to claim 2, wherein the thickness of the buffer layer is smaller than the thickness of the piezoelectric layer and the thickness of the lower electrode.

4. The liquid dispensing head according to claim 1, wherein the length of the side surface of the second portion in the direction along the surface of the lower electrode is smaller than the length of the side surface of the first portion in the direction along the surface of the lower electrode.

5. In a cross-sectional view, the end of the piezoelectric element is in contact with the first portion and the upper electrode, and further has a third portion whose side surface is inclined with respect to the surface of the lower electrode, wherein the inclination angle of the side surface of the third portion is smaller than the inclination angle of the side surface of the first portion, as described in claim 1.

6. The liquid dispensing head according to claim 5, wherein the third portion has an exposed region on the surface in contact with the upper electrode that is exposed from the upper electrode and connected to the side surface of the third portion.

7. The liquid dispensing head according to claim 5, wherein the thickness of the first portion is greater than the thickness of the second portion and the thickness of the third portion.

8. The liquid dispensing head according to claim 1, wherein the surface roughness of the side surface of the first portion is greater than the surface roughness of the side surface of the second portion.

9. The liquid dispensing head according to claim 1, wherein the side surface of the first portion and the side surface of the second portion have deposits containing the piezoelectric material.

10. The liquid dispensing head according to claim 1, further comprising an insulating film located above the lower electrode, above the end of the piezoelectric body, and above at least a portion of the upper electrode, wherein the insulating film continuously covers the side surface of the second portion and the lower electrode.

11. A recording device comprising a liquid dispensing head according to any one of claims 1 to 10, and a control unit for controlling the liquid dispensing head.

Images