Inkjet head manufacturing method and inkjet head

Abstract

The invention provides a method for manufacturing an ink jet head and an ink jet head, wherein the ink jet head is less in deviation of ink ejection. A method for manufacturing an ink jet head in which a piezoelectric member is deformed by applying a voltage to the piezoelectric member, and ink is ejected by applying a pressure variation to the ink, corrects the distribution of the ejection speed of the ink by means of a configuration corresponding to the polarization characteristics of the piezoelectric member. The polarization characteristic may be a characteristic specified by residual polarization. As a result, the area of an electrode for applying a voltage to the piezoelectric element can be reduced as the remaining polarization of the piezoelectric element is large.

Description

Technical Field

[0001] The invention relates to a method for manufacturing an inkjet head and an inkjet head. Background Art

[0002] Conventionally, there is an inkjet head that ejects ink from a plurality of nozzles and lands the ink on a target medium. In this inkjet head, a problem arises with the variation in pressure applied to the ink ejected from each nozzle.

[0003] In a piezoelectric inkjet head, ink pressure is applied using deformation corresponding to the applied voltage to the piezoelectric component. In a piezoelectric inkjet head, variations in the characteristics of the piezoelectric component lead to variations in the applied ink pressure. Patent Document 1 discloses a technique for offsetting variations by varying the area of ​​electrodes (individual electrodes) located at locations overlapping the piezoelectric component, based on variations in the thickness of the piezoelectric component during manufacturing.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-156987.

[0005] However, even if the outer shapes of the piezoelectric components are made uniform, variations in pressure, that is, in ink ejection, still occur, and there is a demand to appropriately suppress these variations. Summary of the Invention

[0006] An object of the present disclosure is to provide a method for manufacturing an inkjet head and an inkjet head with less variation in ink ejection.

[0007] To achieve the above object, the invention described in claim 1 is a method for manufacturing an inkjet head that applies voltage to a piezoelectric element to deform the piezoelectric element, thereby applying pressure changes to the ink to cause it to be ejected.

[0008] The distribution of the ejection speed of the ink is corrected by a structure corresponding to the polarization characteristics of the piezoelectric member.

[0009] Furthermore, the invention described in claim 2 is a method for manufacturing the inkjet head described in claim 1,

[0010] The above-mentioned polarization characteristics are defined by the remanent polarization.

[0011] In addition, the invention described in claim 3 is the method for manufacturing the inkjet head described in claim 2,

[0012] The area of ​​the electrode for applying voltage to the piezoelectric component is reduced in a portion of the piezoelectric component where the residual polarization is larger.

[0013] In addition, the invention described in claim 4 is an inkjet head including a plurality of piezoelectric elements and a plurality of ink flow paths.

[0014] The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component.

[0015] The ink flow path includes a pressure chamber that is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink.

[0016] The electrode has an area corresponding to the polarization characteristics of the piezoelectric member in each of the piezoelectric elements.

[0017] In addition, the invention described in claim 5 is an inkjet head including a plurality of piezoelectric elements and a plurality of ink flow paths.

[0018] The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component.

[0019] The ink flow path includes a pressure chamber that is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink.

[0020] In each of the piezoelectric elements, the piezoelectric member has an area corresponding to the polarization characteristics of the piezoelectric member in a plan view along a stacking direction of the piezoelectric member and the electrodes.

[0021] In addition, the invention described in claim 6 is an inkjet head including a plurality of piezoelectric elements and a plurality of ink flow paths.

[0022] The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component.

[0023] The ink flow path includes a pressure chamber that is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink.

[0024] The pressure chambers have areas corresponding to polarization characteristics of the corresponding piezoelectric members in a plan view along a stacking direction of the piezoelectric members and the electrodes.

[0025] Furthermore, the invention according to claim 7 is the inkjet head according to any one of claims 4 to 6,

[0026] The above-mentioned polarization characteristics are characteristics defined by remanent polarization.

[0027] According to the present invention, there is an effect that an inkjet head with less variation in ink ejection can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A This is a cross-sectional view schematically showing the structure near a certain nozzle in a head chip of an inkjet head.

[0029] Figure 1B This is a diagram schematically showing the structure near a certain nozzle in a head chip of an inkjet head.

[0030] Figure 2 This is a diagram explaining the polarization characteristics of a piezoelectric component.

[0031] Figure 3A This is a diagram showing an example of deviation in remanent polarization.

[0032] Figure 3B Graphs showing experimental results of an example of correction of the electrode area with respect to the deviation of the remanent polarization.

[0033] Figure 4A It is a diagram showing an example of the charge amount and the ejection speed.

[0034] Figure 4B It is a graph showing experimental results of an example of correction of the charge amount and the ejection speed according to correction of the electrode area.

[0035] Figure 5 This is a graph showing the rate of change of ink ejection speed with respect to a change in a parameter related to offsetting a deviation in polarization characteristics as a relative change with respect to a reference parameter value.

[0036] Figure 6A This is a flowchart showing the procedure of design adjustment processing for manufacturing a head chip.

[0037] Figure 6B This is a flowchart showing the procedure of the head chip manufacturing process. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0039] Figure 1A as well as Figure 1B This diagram schematically illustrates the structure near a nozzle N in the head chip 10 of the inkjet head 1 according to this embodiment. In practice, the head chip 10 includes multiple nozzles N. The nozzles N are arranged on the bottom surface (the -Z side) of the head chip 10 at intervals corresponding to the resolution. The nozzles N may also be arranged two-dimensionally. Figure 1AA cross section of the head chip 10 parallel to the ink ejection direction is shown. The head chip 10 includes a flow path component 11, a vibrating portion 12 (piezoelectric element), and a nozzle plate 13. The nozzle plate 13 is located on the bottom surface (-Z side) and has a nozzle N. The flow path component 11 is composed of multiple stacked layers and has a hollow pressure chamber 111 inside. Below the pressure chamber 111 (-Z side), a common supply path 115 extends in the Y direction. Ink is supplied to each pressure chamber 111 via an upstream supply path 113 that branches from the common supply path 115 and extends in the Z direction. The pressure chamber 111 is connected to the nozzle N via a downstream supply path 114. The upper side (+Z side) of the pressure chamber 111 is covered by a vibrating plate 112. These pressure chambers 111, upstream supply path 113, and downstream supply path 114 are collectively referred to as the ink flow path for each nozzle N.

[0040] In addition, the ink flow path is not limited to the above-mentioned positional relationship. For example, the common supply path 115 and the upstream supply path 113 may be located above the pressure chamber 111 (on the +Z side), and the nozzle N may be directly connected to the bottom surface of the pressure chamber 111 (on the -Z side). The flow path component 11 has insulating properties and can be precisely processed, such as a glass substrate or a Si substrate, or a resin substrate such as polyimide. The components of multiple layers may also be different from each other. In addition, as long as they are separated from the vibration part 12, a portion may also include a conductor layer (SUS, etc.). The layer separated from the vibration part 12 is, for example, the nozzle plate 13, etc. In addition, the vibration plate 112 may also be used in conjunction with the lower electrode 122 of the vibration part 12. In this case, the material of the vibration plate 112 shall be based on the material of the lower electrode 122.

[0041] The vibrating portion 12 is located above the pressure chamber 111 across the vibrating plate 112, and is located within a range that at least partially overlaps the pressure chamber 111 when viewed from above. The vibrating portion 12 is bonded with a lower electrode 122, a piezoelectric component 121, and an upper electrode 123, overlapping each other in this order from the bottom (-Z side). The lower electrode 122 is bonded to the vibrating plate 112. The piezoelectric component 121 deforms in response to the potential difference between the lower electrode 122 and the upper electrode 123. This deformation causes the vibrating plate 112 to deform, changing the size (volume) of the pressure chamber 111 and thus fluctuating the ink pressure within the pressure chamber 111.

[0042] Although not particularly limited, the lower electrode 122 here is a common electrode, spanning between multiple groups of pressure chambers 111 and piezoelectric components 121 (for example, extending in the Y direction). A common potential, such as a ground potential, is applied to the lower side of each piezoelectric component 121 via the lower electrode 122. In addition, the upper electrode 123 is an independent electrode (the electrode disclosed in the present invention). By setting the upper electrode 123 to a potential (voltage) that is independently set, the piezoelectric component 121 is deformed according to the potential difference (applied voltage) with the lower electrode 122. The change pattern of the potential difference (voltage) is appropriately specified. Thus, the presence or absence of ink ejection from each nozzle N, the ejection amount, etc. corresponding to the deformation amount of the piezoelectric component 121 and the frequency of the periodic deformation, etc. are specified.

[0043] The piezoelectric component 121 is mainly a ferroelectric, such as lead zirconate titanate (PZT). The lower electrode 122 and the upper electrode 123 are not particularly limited as long as they are metals with high conductivity. For example, the lower electrode 122 and the upper electrode 123 can be selected from titanium, iridium, platinum, chromium, gold, etc. or a combination of these metals (alloys or multiple layers alone). The upper electrode 123 and the lower electrode 122 can also be made of different materials. The vibration part 12 is obtained by sequentially forming a three-layer film of the lower electrode 122, the piezoelectric component 121 and the upper electrode 123 on the vibration plate 112.

[0044] The vibration plate 112 is, for example, a thin elastically deformable Si substrate, etc. A portion of the vibration plate 112 faces the pressure chamber 111 and is vibrating, while the other portion is bonded and fixed to the flow path member 11 and the like.

[0045] For example, these structures of the head chip 10 can be obtained with high precision by a manufacturing method of a MEMS (Micro Electro Mechanical System) structure using a semiconductor process. The film formation of the piezoelectric component 121 can be achieved by, for example, a sputtering method or a sol-gel method. A conductor connected to the upper side of, for example, a through-hole (not shown) that passes through the flow path component 11 is connected to the lower electrode 122. The head chip 10 has a circuit component having a circuit (conductor) on the upper side above the flow path component 11. Each signal line of the circuit connects each upper electrode 123 and the above-mentioned through-hole to a connection terminal located on the circuit component. The connection terminal is connected to a circuit substrate (for example, an FPC (Flexible Printed Circuit)) having a driver IC that outputs the above-mentioned potential difference change pattern. The connection portion can also be connected using an anisotropic conductive film (ACF), anisotropic conductive paste (ACP), a silver paste, or the like.

[0046] Furthermore, the circuit component may include an ink supply path that connects the common supply path 115 to an ink reservoir located above the circuit component.

[0047] The inkjet head 1 of this embodiment includes, in addition to the head chip 10, circuit components, an ink reservoir, and a circuit substrate. Alternatively, the inkjet head 1 may share a common circuit substrate for multiple head chips 10, circuit components, and ink reservoirs. Furthermore, the inkjet head 1 may include components other than those described above, such as a heating unit (heater) for heating and maintaining the ink, and a temperature measuring unit (thermal resistor, etc.).

[0048] Figure 1B FIG. 1 shows a diagram of the vibration portion 12 viewed from above.

[0049] In this inkjet head 1, the vibrating portion 12 located on the vibrating plate 112 has different top-view dimensions (areas) of the lower electrode 122, the piezoelectric component 121, and the upper electrode 123 relative to the top-view area of ​​the invisible pressure chamber 111 located below the vibrating plate 112. The piezoelectric component 121 has a smaller top-view dimension than the lower electrode 122 located below. The upper electrode 123 has an even smaller top-view dimension than these lower electrodes and piezoelectric components. The lower electrode 122, which serves as a common electrode, has a larger top-view dimension than the pressure chamber 111. Here, the pressure chamber 111 has a larger top-view dimension than the piezoelectric component 121.

[0050] Alternatively, the lower electrode 122 may be an independent electrode for each pressure chamber 111 and piezoelectric element 121 pair. In this case, a voltage may be applied independently to the lower electrode 122, while a common voltage may be applied to the upper electrode 123. Alternatively, the pressure chamber 111 side of the lower electrode 122 may include a coating for ink, with the lower electrode 122 itself facing the pressure chamber 111 and also serving as the vibration plate 112.

[0051] While the top-view shapes of the lower electrode 122, piezoelectric element 121, upper electrode 123, and pressure chamber 111 are shown as rectangles, they are not limited to this. Their top-view shapes may also be circular, elliptical, rectangular with some or all corners chamfered, polygonal, or with chamfered corners. Furthermore, these shapes do not need to be similar to each other.

[0052] The area of ​​the upper electrode 123 in contact with the piezoelectric component 121, when viewed from above, corresponds to the amount of vibration of the piezoelectric component 121. Specifically, when the same voltage is applied, if the range of the piezoelectric component 121 within the electric field corresponding to that voltage varies, the amount of deformation of the piezoelectric component 121 as a whole also varies. This difference in the amount of deformation of the piezoelectric component 121 affects the amount (speed) of ink ejected. Therefore, the area of ​​the upper electrode 123, when viewed from above, is appropriately determined, as described below.

[0053] Furthermore, variations in the thickness and area of ​​the piezoelectric element 121 affect the ink ejection volume (speed). Therefore, these thickness and area must also be appropriately determined. Specifically, these variations can include the length of the shortest straight line connecting two points on the periphery of the piezoelectric element 121 and passing through the center, i.e., variations in the diameter of a circle, the minor diameter of an ellipse, the short side length of a cuboid, and so on.

[0054] By appropriately polarizing the piezoelectric element 121 in the Z direction, it deforms when a potential difference is generated between the upper electrode 123 and the lower electrode 122. This deformation occurs in a direction perpendicular to the Z direction, in this case, the X direction. However, since the lower electrode 122 is fixed to the vibration plate 112, deformation in the X direction is restricted, causing deformation between the upper electrode 123 and the free end, resulting in deflection. This causes the vibration plate 112 to vibrate in the Z direction, causing the volume of the pressure chamber 111 to fluctuate.

[0055] Even if the outer dimensions of the piezoelectric member 121 and the area of ​​the upper electrode 123 are made uniform, the amount of deformation of the piezoelectric member 121 varies. The inventors' research has revealed that the main cause of such variations is variations in the polarization characteristics of the piezoelectric member 121.

[0056] Figure 2 This is a diagram illustrating the polarization characteristics of the piezoelectric member 121 .

[0057] As described above, the piezoelectric element 121 uses a ferroelectric material and therefore has spontaneous polarization. That is, spontaneous polarization ±Pr exists in the piezoelectric element 121 even when no voltage is applied. The remanent polarization 2Pr is the difference between the spontaneous polarization ±Pr.

[0058] Furthermore, to invert the polarization of the piezoelectric element 121, the piezoelectric element 121 must be located within an electric field with an absolute value greater than the counterelectric field ±Ec. To deform the piezoelectric element 121, while the lower electrode 122 is at ground potential as described above, a voltage ±Vs is applied to the upper electrode 123. The voltage ±Vs is sufficient to produce an electric field ±Es with an absolute value greater than the counterelectric field ±Ec in the piezoelectric element 121. This voltage ±Vs is determined by the thickness of the piezoelectric element 121, that is, the distance between the upper electrode 123 and the lower electrode 122. This generates a polarization ±Ps with an absolute value greater than the spontaneous polarization ±Pr.

[0059] The polarization quantity [C] depends on the polarization P [C·m －2 ] The area of ​​the upper electrode 123 that the piezoelectric component 121 contacts [m 2 ]. That is, the deviation of the polarization ±Ps when a certain voltage ±Vs is applied leads to a deviation in the polarization amount. As a result, a deviation in the deformation amount occurs in the piezoelectric component 121. Such a deviation in polarization characteristics occurs under various conditions regardless of the manufacturing method, that is, the above-mentioned film forming method, and processing methods such as dry etching or annealing. Therefore, it is difficult to make the polarization characteristics completely consistent. On the other hand, the deviation in polarization characteristics roughly depends on the manufacturing device, etc. By finding out the dependence on the manufacturing device, etc. in advance through experiments, the deviation pattern of the polarization characteristics in the multiple piezoelectric components 121 in the inkjet head 1 obtained by the manufacturing device is determined. Therefore, contrary to the past, it is possible to intentionally make the top view area of ​​the above-mentioned upper electrode 123, the top view area of ​​the piezoelectric component 121, etc. different according to the deviation pattern. By appropriately distributing the top view area, the deviation in polarization characteristics can be offset.

[0060] Polarization ±Ps at a voltage ±Vs is related to spontaneous polarization ±Pr (remanent polarization 2Pr). Therefore, as polarization characteristics, spontaneous polarization ±Pr or remanent polarization 2Pr can be used instead of polarization ±Ps. Alternatively, the difference between polarization Ps and spontaneous polarization Pr (Ps - Pr) can be used as a polarization characteristic. Furthermore, electric field data such as the electric field resistance Ec can be used, for example, Ps / (Es - Ec) can also be used as a polarization characteristic.

[0061] The measurement of polarization can also be performed using well-known techniques, such as the Sawyer tower circuit. In this circuit, the piezoelectric component 121 is connected in series with a known large-capacity standard capacitor relative to an AC power supply. The large capacity mentioned here is sufficiently large compared to the capacitance of the piezoelectric component 121. The voltage of the standard capacitor becomes a value corresponding to the charge accumulated in the standard capacitor, that is, the integral value of the current flowing through the standard capacitor. Since the charge of the piezoelectric component 121 is equal to the charge of the standard capacitor, the relationship between the applied voltage of the AC power supply and the voltage of the standard capacitor corresponds to the relationship between the electric field E and the polarization P of the piezoelectric component 121. By obtaining the voltage of the standard capacitor while changing (scanning) the applied voltage of the AC power supply, the polarization Ps and spontaneous polarization Pr, as well as the anti-electric field Ec, etc. can be obtained. Alternatively, the residual polarization 2Pr can also be measured using a device sold on the market. As such a device, there are, for example, the ferroelectric characteristic evaluation system FCE10 series from Toyo Technica and various ferroelectric and piezoelectric testers from Radiant Technologies.

[0062] The remanent polarization 2Pr, a polarization characteristic, can be measured as long as power is supplied to the piezoelectric component 121. For example, it can be measured after forming the lower and upper electrodes on the chip on the wafer. Alternatively, it can be measured on a single chip cut from the wafer, or after assembling the inkjet head through the connector of the inkjet head.

[0063] Figure 3A as well as Figure 3B This is a diagram showing experimental results of an example of correction of the electrode area with respect to the deviation of the remanent polarization.

[0064] Here, an example of an inkjet head 1 having 200 nozzles N arranged therein is given. The inkjet head 1 shows a distribution in which the residual polarization 2Pr indicated by circles becomes smaller at both ends and becomes larger near the center. Figure 3A The distribution of the conventional example (before correction) is shown in . If the electrode area indicated by the square mark is constant, the charge amount of the piezoelectric component 121 generated by polarization when a certain voltage is applied depends on the residual polarization 2Pr, as shown by the diamond mark, and deviates in a manner such that it increases in the center and decreases at both ends.

[0065] In contrast, Figure 3B As shown in this modified embodiment, a structure in which the electrode area decreases in the center and increases at the ends can be employed to offset variations in the remanent polarization 2Pr. In other words, each electrode has an area corresponding to its polarization characteristics. As a result, the charge generated in the piezoelectric element 121 when a certain voltage is applied is substantially constant. Consequently, an inkjet head 1 can be obtained that suppresses variations in the ejection volume and ejection speed of the ejected ink.

[0066] Figure 4A as well as Figure 4B Graphs showing experimental results of measuring the ejection speed of ink droplets corresponding to the electrode areas before and after the correction, along with the charge amount.

[0067] exist Figure 4A In the conventional example (before correction) shown, the uneven charge level also causes significant variation in the ejection velocity (over 10%). The velocity of ink droplets ejected from the nozzles N in the channels near the center is significantly higher than the velocity of ink droplets ejected from the nozzles N in the channels near the ends. As a result, the ink droplets' landing positions on the medium also vary.

[0068] In contrast, in Figure 4B In this embodiment (after modification), as described above, charge variation is minimized. Consequently, variations in ejection velocity are also minimized, down to a few percent. As a result, ink droplets land on the medium with minimal unevenness, minimizing degradation in image quality.

[0069] Alternatively, instead of the electrode area, the top-view area of ​​the piezoelectric element 121 can be varied, primarily in terms of its width when viewed from above, i.e., the diameter of a circle, the length of the minor axis of an ellipse, or the length of its short side. In the case of an ellipse or a shape more complex than an ellipse, the shortest distance between two points connecting the periphery and passing through the center corresponds to the length of the short side. Alternatively, by varying the top-view area (volume) of the pressure chamber 111, the effect of variations in the deformation of the piezoelectric element 121 on the pressure fluctuations of the ink can be offset. In this case, as with the piezoelectric element 121, specifically, the width of the pressure chamber 111 when viewed from above, such as the length of its short side, or the shortest distance between two points connecting the periphery and passing through the center of the pressure chamber 111, can be varied. Furthermore, by varying structural parameters such as the electrode area of ​​the upper electrode 123, the top-view area of ​​the piezoelectric element 121, and the top-view area of ​​the pressure chamber 111, the resonant frequency of the ink can be altered. Since the shape was not originally designed to strictly match the resonant frequency of the ink, minor changes will not cause any problems. However, if the ink's resonant frequency deviates significantly from the ink ejection operating frequency, it becomes difficult to appropriately apply ink pressure fluctuations. Therefore, the amount of change in structural parameters should be sufficient as long as the resonant frequency deviation is within a reference range, for example, within ±10% of the reference frequency, and more preferably within ±5%.

[0070] Figure 5 This is a graph showing the rate of change of ink ejection speed with respect to changes in structural parameters related to offsetting variations in polarization characteristics, as a relative change with respect to a reference parameter value.

[0071] It is shown that the ink ejection speed changes in a positive correlation regardless of whether the electrode area, the plan view area of ​​the piezoelectric member, or the plan view area of ​​the pressure chamber is changed.

[0072] In addition, according to Figure 5 As can be seen, the relationship between the rate of change of each structural parameter and the change in ink ejection speed is not a linear relationship. The correspondence between the magnitude of the value maintaining the polarization characteristics and the amount of change (adjustment) in each structural parameter can be defined and stored in advance as a conversion table or the like. Correction of each structural parameter can be performed based on this conversion table.

[0073] By thus compensating for variations in polarization characteristics through correction of other structural parameters, the ink ejection speed (ejection volume) can be precisely uniformed. The degree of uniformity can be appropriately determined based on the required accuracy of the inkjet head 1. For example, the degree of uniformity can be within ±1% of the reference speed, and more preferably within ±0.1%.

[0074] Figure 6A as well as Figure 6B This is a flowchart showing the procedure of a method for manufacturing the inkjet head 1 (head chip 10 ) according to the present embodiment. Figure 6A It is the order of design adjustment processing, Figure 6B This is the sequence of the manufacturing process of the inkjet head 1. These processes may be performed by necessary devices or manual work, and some processes may be performed by different devices or different people.

[0075] exist Figure 6A In the design adjustment process shown, first, the distribution of polarization characteristics of a wafer obtained by a wafer manufacturing apparatus for manufacturing the head chip 10 is measured (step S1). The polarization characteristics are not particularly limited as described above, but are, for example, remanent polarization 2Pr.

[0076] The polarization characteristics of the positions corresponding to each nozzle N on the wafer are obtained, and the design of the dimensions of the pressure chamber 111, the piezoelectric component 121, or the upper electrode 123 are adjusted based on the polarization characteristics (step S2). The design data for the adjusted changes is stored (step S3). The design data mentioned here includes, for example, data on the coating range of the photosensitive component involved in photolithography and data on the mask range involved in etching. Then, the design adjustment process ends.

[0077] The above-mentioned polarization characteristic deviations barely change during wafer production under the same conditions using the same wafer manufacturing equipment. Therefore, design data that has undergone a single modification and adjustment can be reused multiple times. However, the design adjustment process can also be performed multiple times at appropriate intervals to update the design data.

[0078] exist Figure 6BIn the manufacturing process shown, the design change adjustment data described above is acquired (step S11). This change adjustment data is then used to create a head chip 10 having nonuniform physical dimensions corresponding to the polarization characteristics at each nozzle N position (step S12). A circuit board, ink reservoir, and other components are then mounted on the head chip 10 to produce the inkjet head 1 (step S13).

[0079] As described above, this embodiment is a method for manufacturing an inkjet head 1 that applies a voltage to a piezoelectric element 121 to deform the piezoelectric element 121, thereby applying pressure fluctuations to the ink and causing it to be ejected. In this manufacturing method, the ink ejection velocity distribution is corrected by a structure corresponding to the polarization characteristics of the piezoelectric element 121.

[0080] In this manner, the present manufacturing method corrects the distribution of ink ejection velocities that varies due to variations in the polarization characteristics of the piezoelectric member 121 involved in ejecting ink from each nozzle N through structural adjustments. Consequently, an inkjet head 1 can be obtained that can easily eject ink from each nozzle N with less variation without requiring adjustments such as drive control during ejection control.

[0081] Alternatively, the polarization characteristics can be defined by the remanent polarization 2Pr. In ferroelectrics, the polarization ±Ps at a certain voltage ±Vs is correlated with the remanent polarization 2Pr. Therefore, the remanent polarization 2Pr is a suitable value for characterizing the polarization characteristics of the piezoelectric component 121, which primarily uses ferroelectrics.

[0082] Furthermore, in this inkjet manufacturing method, the area of ​​the upper electrode 123, which applies voltage to the piezoelectric element 121, is reduced in portions of the piezoelectric element 121 where the remanent polarization 2Pr is greater. This adjusts the charge generated at each electrode so that it is uniform when the voltage is applied, thereby suppressing variations in the deformation of each pressure chamber 111. Consequently, variations in the ink ejection velocity are also reduced.

[0083] The inkjet head 1 of this embodiment includes multiple vibrating sections 12 each having a piezoelectric component 121 and an upper electrode 123 for applying a voltage to the piezoelectric component 121, and an ink flow path including a pressure chamber 111. The pressure chamber 111 deforms in response to the movement of the vibrating section 12, thereby applying pressure fluctuations to the ink. The upper electrode 123 on each vibrating section 12 has an area corresponding to the polarization characteristics of the piezoelectric component 121. In other words, this inkjet head 1 compensates for variations in polarization characteristics by adjusting the size of the upper electrode 123.

[0084] Such a structure can be easily adjusted by setting the etching range of the electrode layer, etc. Therefore, according to this embodiment, it is possible to obtain an inkjet head 1 that can easily and accurately eject ink with less variation.

[0085] Alternatively, in this inkjet head 1, the piezoelectric component 121 in each vibrating portion 12 may have an area corresponding to the polarization characteristics of the piezoelectric component 121 when viewed from above along the stacking direction of the piezoelectric component 121 and the upper electrode 123. In other words, this inkjet head 1 can also offset variations in polarization characteristics using the top-view area of ​​the piezoelectric component 121. This also allows for appropriate adjustment of the dimensions of the piezoelectric component 121 during the semiconductor manufacturing process. Therefore, according to this embodiment, an inkjet head 1 can be obtained that can easily suppress variations in ink ejection caused by variations in polarization characteristics, thereby achieving more uniform ink ejection.

[0086] Alternatively, in the inkjet head 1, the pressure chambers 111 may each have an area corresponding to the polarization characteristics of the corresponding piezoelectric component 121 when viewed from above along the stacking direction of the piezoelectric component 121 and the upper electrode 123. That is, the inkjet head 1 can also offset deviations in polarization characteristics by adjusting the top-view dimensions of the pressure chambers 111, for example, primarily the minor axis length and the minor side length. The dimensions of the pressure chambers 111 can also be appropriately changed during the semiconductor manufacturing process. Therefore, according to this embodiment, an inkjet head 1 can be obtained that can easily suppress deviations in ink ejection caused by the influence of deviations in polarization characteristics and achieve more uniform ink ejection.

[0087] Furthermore, in this inkjet head 1, the polarization characteristics can also be specified by the remanent polarization 2Pr. The remanent polarization 2Pr is a representative value that characterizes the polarization characteristics of a piezoelectric component, which is primarily a ferroelectric. Since the adjustment amount can be appropriately determined based on this value, this inkjet head 1 can achieve uniform ink discharge with further reduced variation in ink discharge.

[0088] In addition, the present disclosure is not limited to the above-described embodiment, and various modifications can be made.

[0089] For example, in the above embodiment, variations in ink ejection speed corresponding to variations in polarization characteristics are offset by adjusting the electrode area of ​​the upper electrode 123, the top-view area of ​​the piezoelectric element 121, or the top-view area of ​​the pressure chamber as structural parameters for each corresponding nozzle N. However, variations in ink ejection speed can also be offset by adjusting structural parameters other than these areas, such as size and shape.

[0090] In the above embodiment, the inkjet head 1 is described as ejecting ink using the piezoelectric component 121 vibrating in a flexural mode. However, the inkjet head can also eject ink using the deformation of the piezoelectric component vibrating in a shear mode. In this case, the dimensions of the pressure chamber, electrodes, and piezoelectric component can be determined based on the stacking direction of the pressure chamber, electrodes, and piezoelectric component.

[0091] Furthermore, in the above embodiment, the example of adjusting the size is described as primarily changing the shortest distance between two points on the periphery and passing through the center, such as the minor axis, or the shortest side, but the present invention is not limited to this. For example, the size (scale) may be changed without changing the shape, or the major axis or any other axial dimension may be changed.

[0092] Furthermore, the pressure chamber 111 that applies pressure fluctuations to the ink need only be located midway along the ink flow path and facing the vibration plate 112. In other words, the pressure chamber 111 need not have structural differences from the preceding and following ink flow paths, such as differences in flow path diameter or bends in the flow path direction.

[0093] Alternatively, the distribution information of the polarization characteristics of the wafer or the like may be obtained by simply obtaining information measured externally by another person.

[0094] In addition, the specific configurations, contents and order of processing operations shown in the above embodiments can be appropriately modified without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and their equivalents.

[0095] The present invention can be utilized in a method for manufacturing an inkjet head and an inkjet head.

[0096] Description of Reference Numerals

[0097] 1…inkjet head, 10…head chip, 11…flow path component, 111…pressure chamber, 112…vibration plate, 113…upstream supply path, 114…downstream supply path, 12…vibration portion, 121…piezoelectric component, 122…lower electrode, 123…upper electrode, 13…nozzle plate, N…nozzle.

Claims

1. A method for manufacturing an inkjet head, wherein a voltage is applied to a piezoelectric component to deform the piezoelectric component, thereby applying pressure changes to ink to eject the ink, wherein: The distribution of the ejection speed of the ink is corrected by a structure corresponding to the polarization characteristics of the piezoelectric member.

2. The method for manufacturing an inkjet head according to claim 1, wherein: The above-mentioned polarization characteristics are defined by the remanent polarization.

3. The method for manufacturing an inkjet head according to claim 2, wherein: The area of ​​the electrode for applying a voltage to the piezoelectric component is reduced as the portion of the piezoelectric component having a larger residual polarization is increased.

4. An inkjet head, wherein: Each of the plurality of piezoelectric elements and the plurality of ink flow paths is provided. The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component. The ink flow path includes a pressure chamber, and the pressure chamber is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink. The electrode has an area corresponding to the polarization characteristics of the piezoelectric member in each of the piezoelectric elements.

5. An inkjet head, wherein: Each of the plurality of piezoelectric elements and the plurality of ink flow paths is provided. The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component. The ink flow path includes a pressure chamber, and the pressure chamber is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink. In each of the piezoelectric elements, the piezoelectric member has an area corresponding to the polarization characteristics of the piezoelectric member in a plan view along a stacking direction of the piezoelectric member and the electrodes.

6. An inkjet head, wherein: Each of the plurality of piezoelectric elements and the plurality of ink flow paths is provided. The piezoelectric element includes a piezoelectric component and an electrode for applying a voltage to the piezoelectric component. The ink flow path includes a pressure chamber, and the pressure chamber is deformed according to the operation of the piezoelectric element to apply pressure changes to the ink. The pressure chambers have areas corresponding to polarization characteristics of the corresponding piezoelectric members in a plan view along a stacking direction of the piezoelectric members and the electrodes.

7. The inkjet head according to any one of claims 4 to 6, wherein: The above-mentioned polarization characteristics are characteristics defined by remanent polarization.

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