JP2010082939A - Method for manufacturing liquid jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield by reducing the unevenness of displacement of a piezoelectric element. <P>SOLUTION: The piezoelectric element having a piezoelectric body and an electrode is formed in a substrate in which a pressure chamber communicating to a nozzle for discharging a liquid is formed (step S2). The capacitance and size of the above formed piezoelectric element are surveyed (step S4). The displacement amount of the above piezoelectric element is estimated from the survey result (step S6). Based on the estimated amount of displacement of the piezoelectric element, a correction value for the processing of changing the displacement amount of the piezoelectric element is determined (step S8). The unevenness of displacement amount between the piezoelectric elements is corrected by performing the above processing using the correction value (step S10). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid discharge head that can reduce variation in displacement of piezoelectric elements and improve yield.

  2. Related Art There is known an ink jet recording type image forming apparatus that records an image on a recording medium by ejecting ink onto the recording medium from a plurality of nozzles formed on a liquid discharge head. In the ink jet recording method, noise during recording operation is low, running cost is low, and high-resolution and high-quality image recording is possible. As an ink droplet ejection system, there is a piezoelectric system using displacement of a piezoelectric element.

  By the way, there is a problem that due to variations in the amount of displacement among the plurality of piezoelectric elements, variations in ejection occur between the plurality of nozzles, resulting in a decrease in yield. In order to solve such a problem, the capacitance of the piezoelectric element is measured, and based on the measured capacitance, the width of the pressure chamber, the thickness of the moisture-resistant protective film on the piezoelectric element, or the opening width can be changed. It has been proposed (Patent Document 1). Specifically, there is a correlation between the capacitance of the piezoelectric element and the amount of displacement, and the larger the capacitance, the larger the amount of displacement. Apply a correction to increase the size of the pressure chamber in the small part. Alternatively, the thickness of the moisture-resistant protective film in a portion with a large capacitance is increased, and the thickness of the moisture-resistant protective film in a portion with a small capacitance is decreased. Alternatively, the opening size of the moisture-resistant protective film in a portion with a large capacitance is reduced, and the opening size of the moisture-resistant protective film in a portion with a small capacitance is increased.

In addition, it has been proposed to form a large electrode once and then trim the electrode with a laser (Patent Documents 2 and 3).
JP 2008-114372 A JP 2002-307696 A JP 2004-291634 A

  However, since the actual variation in capacitance includes the effect of variations in the thickness of the piezoelectric body and the electrode size, it has been difficult to sufficiently correct the displacement of the piezoelectric element.

  In the invention described in Patent Document 1, although the capacitance of the piezoelectric element and the amount of displacement are certainly correlated, the difference in the shape size of the piezoelectric element such as the thickness of the piezoelectric body and the area of the electrode is sufficient for the correction value for processing. Therefore, it is difficult to sufficiently correct the displacement.

  Further, in the inventions described in Patent Documents 2 and 3, since the electrodes are once formed in a large size and then the electrodes are trimmed with a laser, it is generally necessary to rework all the elements, which requires man-hours. Further, since there is no feedback from the capacitance, the actual displacement variation is not so much.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of manufacturing a liquid discharge head that can reduce variation in displacement of piezoelectric elements and improve yield.

  To achieve the above object, the present invention provides a piezoelectric element forming step for forming a piezoelectric element having a piezoelectric body and an electrode on a substrate on which a pressure chamber communicating with a nozzle for discharging a liquid is formed. A measurement step for actually measuring the capacitance of the piezoelectric element and the size of the piezoelectric element; a displacement amount prediction step for predicting a displacement amount of the piezoelectric element from an actual measurement result of the measurement step; and a predicted displacement of the piezoelectric element. A correction value determining step for determining a correction value of a processing process for changing the displacement amount of the piezoelectric element based on the amount; and a variation of the displacement amount between the piezoelectric elements by performing the processing process using the correction value. And a processing step for correcting the liquid ejection head.

  According to this, as compared with the case of processing based only on the capacitance of the piezoelectric element, the variation in displacement between the piezoelectric elements is further reduced, and the discharge performance becomes uniform, thereby improving the yield.

  For example, a correction value for the opening area of the pressure chamber is determined in the correction value determination step, and the pressure chamber is formed in the substrate based on the correction value in the processing step.

  Further, for example, in the correction value determining step, at least one of the thickness of the protective film formed on the piezoelectric element and the opening area of the opening formed in the protective film is determined, and in the processing step The protective film is formed on the piezoelectric element based on the correction value.

  Further, for example, in the correction value determining step, the thickness of the liquid-resistant protective film formed in the pressure chamber is determined, and in the processing step, the pressure chamber is formed in the substrate, and based on the correction value. Then, the liquid-resistant protective film is formed in the pressure chamber.

  For example, the size of the piezoelectric element measured in the measuring step is at least one of the thickness of the piezoelectric body and the area of the electrode.

  In one aspect of the present invention, the first displacement characteristic information indicating the relationship between the capacitance and size of the piezoelectric element and the amount of displacement of the piezoelectric element, the measured capacitance of the piezoelectric element, and the measured Based on the size of the piezoelectric element, a displacement amount of the piezoelectric element is predicted, second displacement characteristic information indicating a relationship between the displacement amount of the piezoelectric element and the correction value, and the predicted displacement amount of the piezoelectric element Based on the above, the correction value is obtained.

  According to this, the correction value can be obtained accurately and easily.

  Further, the present invention provides a piezoelectric element forming step of forming a piezoelectric element having a piezoelectric body and an electrode on a substrate on which a pressure chamber communicating with a nozzle for discharging a liquid is formed, and a displacement amount of the formed piezoelectric element or A measurement step for actually measuring the displacement volume, a correction value determining step for determining a correction value for a processing process for changing the displacement amount of the piezoelectric element based on the actual measurement result of the measurement step, and the processing process using the correction value. And a processing step of correcting variation in the amount of displacement between the piezoelectric elements by performing the above.

  For example, in the correction value determination step, at least one of the thickness of the protective film formed on the piezoelectric element and the opening area of the opening formed in the protective film is determined, and in the processing step, The protective film is formed on the piezoelectric element based on the correction value.

  According to the present invention, variation in displacement of piezoelectric elements can be reduced, and yield can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is an overall configuration diagram illustrating an example (inkjet recording apparatus) of an image forming apparatus including a liquid ejection head to which the present invention is applied.

  An ink jet recording apparatus 100 shown in FIG. 1 is an image forming apparatus to which a two-liquid aggregation method for forming an image on a recording medium 114 made of a sheet using ink and a processing liquid is applied.

  The ink jet recording apparatus 100 mainly includes a paper supply unit 102 that supplies a recording medium 114, a permeation suppression layer forming unit 104 that applies a permeation suppression agent to the recording medium 114, and a process that applies a treatment liquid to the recording medium 114. On the recording medium 114, the liquid application unit 106, the ink droplet ejection unit (printing unit) 108 that ejects colored ink onto the recording medium 114, the drying unit 110 that dries the recording medium 114 on which the color ink has been ejected, The image forming apparatus includes a fixing unit 112 that fixes an image formed on the recording medium and a paper discharge unit 113 that conveys and discharges the recording medium 114 on which the image is formed.

  Although not shown in FIG. 1, the leading end of the recording medium 114 is placed on each of the impression cylinders 126 </ b> A to 126 </ b> E constituting the conveyance mechanism of the recording medium 114 and the transfer cylinders 124 </ b> A to 124 </ b> E provided adjacent thereto. One or a plurality of holding claws (grippers) to hold are formed, and the recording medium 114 is transferred between the holding claws of the impression cylinder and the transfer cylinder. Since a well-known thing should just be applied about the structure of a holding nail | claw, description is abbreviate | omitted here.

  The paper feed unit 102 is provided with a paper feed stand 120 on which the recording media 114 are stacked. A feeder board 122 is connected in front of the paper feed tray 120 (left side in FIG. 1), and the recording media 114 stacked on the paper feed tray 120 are sent to the feeder board 122 one by one in order from the top. The recording medium 114 sent to the feeder board 122 is transferred to the impression cylinder 126A of the permeation suppression layer forming unit 104 via the transfer cylinder 124A.

  The permeation suppression layer forming unit 104 applies a permeation suppression agent that suppresses permeation of water and a hydrophilic organic solvent contained in the treatment liquid and ink into the recording medium 114. As the permeation inhibitor, a resin in which a resin is dispersed in the form of an emulsion or a resin is dissolved is used. As the solvent, an organic solvent or water is used. As the organic solvent, methyl ethyl ketone, petroleum, and the like are preferably used. The temperature T1 of the recording paper is set higher than the minimum film forming temperature Tf1 of the resin. The difference between Tf1 and T1 is preferably about 10 to 20 ° C. As a result, a good film is immediately formed after the resin adheres to the recording medium 114, and the penetration of the ink and the treatment liquid solvent applied to the recording medium 114 into the recording medium 114 is suppressed well. Can do. Adjustment of the temperature of the recording medium 114 includes a method of installing a heating element such as a heater inside the pressure drum 126A, a method of applying hot air from the surface (upper surface) of the recording medium 114, heating using an infrared heater or the like. These may be combined.

  If the curling of the recording medium 114 is difficult to occur, the permeation suppression layer forming unit 104 can be omitted. For example, the application amount of the penetration inhibitor (including the case where the penetration inhibitor is not applied) may be controlled according to the type of the recording medium 114.

  In the permeation suppression layer forming unit 104, a sheet preheating unit 128 and a permeation suppression agent discharge are disposed at positions facing the surface of the pressure drum 126 A in order from the upstream side in the rotation direction (counterclockwise direction in FIG. 1) of the pressure drum 126 A. A head 130 and a permeation suppression agent drying unit 132 are provided.

  Each of the paper preheating unit 128 and the permeation suppression agent drying unit 132 is provided with a hot air dryer capable of controlling the temperature and the air volume within a predetermined range. When the recording medium 114 held on the impression cylinder 126A passes through a position facing the paper preheating unit 128 and the permeation suppression agent drying unit 132, air (hot air) heated by the hot air dryer is blown onto the recording medium 114. It has a configuration that can be.

  The permeation suppression agent ejection head 130 ejects a permeation suppression agent onto the recording medium 114 held by the impression cylinder 126A. Each of the ink ejection heads 140C, 140M, 140Y, The same configuration as 140K, 140R, 140G, 140B is applied.

  In this example, an inkjet head is applied as a means for applying a permeation inhibitor to the surface of the recording medium 114. However, the present invention is not limited to this. For example, various methods such as a spray method and a coating method may be applied. Is possible. Among these, a mode in which a permeation inhibitor is applied by an ink jet method as in this example is preferable, and only the ink droplet ejection positions by the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B and the periphery thereof are used. A permeation inhibitor can be selectively applied to the surface.

  A treatment liquid application unit 106 is provided following the permeation suppression layer forming unit 104. A transfer drum 124B is provided between the pressure drum 126A of the permeation suppression layer forming unit 104 and the pressure drum 126B of the treatment liquid applying unit 106 so as to be in contact therewith, and the recording held by the pressure drum 126A. The medium 114 is delivered to the impression cylinder 126B via the transfer cylinder 124B after the permeation inhibitor is applied.

  In the treatment liquid application unit 106, a sheet preheating unit 134 and a treatment liquid discharge head 136 are disposed at positions facing the surface of the pressure drum 126B in order from the upstream side in the rotation direction (counterclockwise direction in FIG. 1) of the pressure drum 126B. , And a processing liquid drying unit 138 are provided.

  Regarding each part of the processing liquid application unit 106 (the paper preheating unit 134, the processing liquid discharge head 136, and the processing liquid drying unit 138), the paper preheating unit 128 of the permeation suppression layer forming unit 104, the permeation suppression agent discharge head 130, and the like. Since the same configuration as that of the permeation suppression agent drying unit 132 is applied, the description thereof is omitted here. Of course, a configuration different from that of the permeation suppression layer forming unit 104 may be applied.

  In this example, the diameter of the impression cylinder 126B is 540 mm, and the treatment liquid is applied to the entire surface of the recording medium 114 with a thickness of 5 μm.

  The treatment liquid used in this example is contained in the ink ejected from the respective ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B toward the recording medium 114, which are disposed in the ink ejection unit 108 at the subsequent stage. It is the acidic liquid which has the effect | action which agglomerates the coloring material which is made.

  The treatment liquid drying unit 138 is provided with a hot air dryer capable of controlling the temperature and the air volume within a predetermined range, and the recording medium 114 held on the impression cylinder 126B faces the hot air dryer of the treatment liquid drying unit 138. When passing through the position, air heated by a hot air dryer (hot air) is sprayed onto the processing liquid on the recording medium 114.

  The temperature and air volume of the hot air dryer are such that the treatment liquid applied on the recording medium 114 is dried by the treatment liquid discharge head 136 disposed on the upstream side in the rotation direction of the impression cylinder 126 </ b> B, and a solid is formed on the surface of the recording medium 114. Or a semi-solid solution aggregation treatment agent layer (thin film layer in which the treatment liquid is dried) is set to such a value. In this example, drying is performed with hot air at 70 ° C. for 1 second.

  When an ink droplet is ejected in a state where a liquid layer (processing liquid layer) of the processing liquid exists on the surface of the recording medium 114, the ink color material (ink dot) floats and moves in the processing liquid layer. As a result, the image quality is degraded. Therefore, in the ink jet recording apparatus 100 shown in FIG. 1, in order to prevent image deterioration due to color material movement (dot floating), before the ink droplet is ejected onto the recording medium 114, the treatment liquid on the recording medium 114 is treated. Is dried to form a solid or semi-solid solution processing agent layer on the recording medium 114.

  As in this example, it is preferable that the recording medium 114 be preheated by the paper preheating unit 134 before the treatment liquid is applied onto the recording medium 114. In this case, the heating energy required for drying the treatment liquid can be kept low, and energy saving can be achieved.

  An ink droplet ejection unit 108 is provided following the treatment liquid application unit 106. A transfer drum 124C is provided between the pressure drum 126B of the treatment liquid application unit 106 and the pressure drum 126C of the ink droplet ejection unit 108 so as to be in contact therewith, and the recording medium held by the pressure drum 126B. 114 is transferred to the impression cylinder 126C via the transfer cylinder 124C after the treatment liquid is applied to form a solid or semi-solid coagulation treatment agent layer. At this time, a mode in which the treatment liquid layer (aggregation treatment agent layer) on the recording medium 114 is additionally dried (for example, heated at 60 ° C.) with the transfer cylinder 124C is also preferable.

  The ink droplet ejecting section 108 corresponds to the seven colors of CMYKRGB at positions facing the surface of the impression cylinder 126C in order from the upstream side in the rotation direction (counterclockwise direction in FIG. 1) of the impression cylinder 126C. Ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B are provided side by side.

  As each of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B, an ink jet recording head (ink jet head) is applied in the same manner as the permeation suppression agent discharge head 130 and the treatment liquid discharge head 136 described above. . That is, each of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B discharges the corresponding color ink droplets toward the recording medium 114 held by the impression cylinder 126C.

  The ink storage / loading unit (not shown) is configured to include ink tanks for storing inks respectively supplied to the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B. Each ink tank communicates with a corresponding head through a required flow path, and supplies a corresponding ink to each ink discharge head. The ink storage / loading unit includes notifying means (display means, warning sound generating means) for notifying when the remaining amount of liquid in the tank is low, and has a mechanism for preventing erroneous loading between colors. ing.

  Ink is supplied from each ink tank of the ink storage / loading unit to each of the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B, and 140C, 140M, 140Y, 140K, 140R, and 140G according to the image signal. , 140B, the corresponding color ink is ejected onto the recording medium 114.

  Each of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B has a length corresponding to the maximum width of the image forming area in the recording medium 114 held by the impression cylinder 126C, and its ink discharge surface 1 is a full-line head in which a plurality of nozzles for ink ejection (not shown in FIG. 1 and indicated by reference numeral 161 in FIG. 2) are arranged over the entire width of the image forming area. Each of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B is fixedly installed so as to extend in a direction orthogonal to the rotation direction of the impression cylinder 126C (the conveyance direction of the recording medium 114).

  According to the configuration in which a full line head having a nozzle row covering the entire width of the image forming area of the recording medium 114 is provided for each ink color, the recording medium 114 and each ink in the transport direction (sub-scanning direction) of the recording medium 114 The primary image is formed in the image forming area of the recording medium 114 by performing the operation of relatively moving the ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B once (that is, by one sub-scan). Can be recorded. As a result, printing can be performed at a higher speed than when a serial (shuttle) type head that reciprocates in the direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium 114 is applied. Can be improved.

  The ink jet recording apparatus 100 of this example is capable of recording up to a recording medium (recording paper) of a maximum half-size, and a drum having a diameter of 810 mm corresponding to a recording medium width of 720 mm is used as the impression cylinder 126C. The drum rotation peripheral speed at the time of ink ejection is 530 mm / sec. The ink ejection volumes of the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B are 2 pl, and the recording density is the main scanning direction (width direction of the recording medium 114) and the sub-scanning direction (recording medium 114). The transporting direction) is 1200 dpi.

  In this example, the configuration of seven colors of CMYKRGB is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are added as necessary. May be. For example, it is possible to add a head for ejecting light ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  A drying unit 110 is provided following the ink droplet ejection unit 108. A transfer drum 124D is provided between the pressure drum 126C of the ink ejection unit 108 and the pressure drum 126D of the drying unit 110 so as to be in contact therewith, and the recording medium 114 held by the pressure drum 126C is After each color ink is applied, the ink is transferred to the impression cylinder 126D via the transfer cylinder 124D.

  In the drying unit 110, hot air nozzle machines 141 and IR heaters 144 are alternately provided at positions facing the surface of the impression cylinder 126D from the upstream side in the rotation direction of the impression cylinder 126D (counterclockwise direction in FIG. 1). ing.

  When ink droplets are ejected onto the solid or semi-solid aggregation processing agent layer formed on the surface of the recording medium 114, ink aggregates (coloring material aggregates) are formed on the recording medium 114. As it is formed, the ink solvent separated from the color material spreads to form a liquid layer in which the aggregating agent is dissolved. In this way, the liquid component (solvent component) remaining on the recording medium 114 causes not only curling of the recording medium 114 but also image degradation. Therefore, in this example, after each corresponding color ink is ejected onto the recording medium 114 from each of the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B, the hot air nozzle unit 141 and the IR heater 144 ( The liquid component on the recording medium 114 is evaporated by an infrared heater.

  In this example, four hot air nozzle machines 141 and three IR heaters 144 are arranged along a direction orthogonal to the conveyance direction of the recording medium 114. When the recording medium 114 passes through the upper surface of the pressure drum 126D of the drying unit 110, hot air is blown from the hot air nozzle unit 141 toward the recording medium 114, and infrared rays are emitted from the IR heater 144 toward the recording medium 114. The For example, hot air of 70 ° C. is ejected from the hot air nozzle unit 141 at 10 m / sec, and infrared rays of 1000 ° C. are emitted from the IR heater 144. Thereby, the liquid moisture on the recording medium 114 evaporates, and the recording medium 114 is dried. The hot air nozzle unit 141 and the IR heater 144 will be described in detail later.

  A fixing unit 112 is provided following the drying unit 110. A transfer drum 124E is provided between the pressure drum 126D of the drying unit 110 and the pressure drum 126E of the fixing unit 112 so as to be in contact therewith. The recording medium 114 held on the impression cylinder 126D is transferred to the impression cylinder 126E via the transfer cylinder 124E.

  In the fixing unit 112, print detection is performed by reading the print result of the ink droplet ejection unit 108 at a position facing the surface of the pressure drum 126E sequentially from the upstream side in the rotation direction (counterclockwise direction in FIG. 1) of the pressure drum 126E. A portion 146 and heating rollers 148A and 148B are provided, respectively.

  The print detection unit 146 captures an image sensor (line sensor or the like) for imaging a printing result of the ink droplet ejection unit 108 (a droplet ejection result of each of the ink ejection heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B). In addition, it functions as a means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor.

  The heating rollers 148A and 148B are rollers whose temperature can be controlled within a predetermined range (for example, 100 ° C. to 180 ° C.), and heat the recording medium 114 sandwiched between the heating rollers 148A and 148B and the impression cylinder 126E. While pressing, the image formed on the recording medium 114 is fixed.

  In this example, the heating temperature of the heating rollers 148A and 148B is set to 110 ° C., and the surface temperature of the impression cylinder 126E is set to 60 ° C. The nip pressure of the heating rollers 148A and 148B is 1 MPa. The heating temperature of the heating rollers 148A and 148B is preferably set according to the glass transition temperature of the polymer fine particles contained in the treatment liquid or ink.

  Subsequent to the fixing unit 112, a paper discharge unit 113 is provided. The paper discharge unit 113 includes a paper discharge drum 150 that receives the recording medium 114 on which an image is fixed, a paper discharge tray 152 on which the recording medium 114 is loaded, and a sprocket and a paper discharge tray 152 provided on the paper discharge drum 150. And a paper discharge chain 154 provided with a plurality of paper discharge grippers.

  Next, the structure of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B disposed in the ink droplet ejection unit 108 will be described in detail. Since the structures of the ink discharge heads 140C, 140M, 140Y, 140K, 140R, 140G, and 140B are common, the ink discharge head (hereinafter referred to as “liquid discharge head” or simply referred to as “liquid discharge head” hereinafter) is represented by reference numeral 160. It may also be called “head”).

  2A is a perspective plan view showing an example of the structure of the head 160, FIG. 2B is an enlarged view of a part thereof, and FIG. 2C is a plan view showing another example of the structure of the head 160. FIG. 3 is a cross-sectional view (a cross-sectional view taken along line IV-IV in FIGS. 2A and 2B) showing a three-dimensional configuration of a part of the head 160. FIG.

  In order to increase the dot pitch formed on the recording medium 114, it is necessary to increase the nozzle pitch in the head 160. As shown in FIGS. 2A and 2B, the head 160 of this example includes a plurality of pressure chamber units 163 having nozzles 161 serving as ink droplet ejection ports and pressure chambers 162 corresponding to the nozzles 161. Substrate having nozzles arranged in a staggered matrix (two-dimensionally), and thereby projected substantially in a line along the head longitudinal direction (main scanning direction perpendicular to the recording medium conveyance direction) High density of the interval (projection nozzle pitch) is achieved.

  The form in which one or more nozzle rows are configured over a length corresponding to the entire width of the recording medium 114 in a direction substantially orthogonal to the conveyance direction of the recording medium 114 is not limited to this example. For example, instead of the configuration of FIG. 2A, as shown in FIG. 2C, short head blocks 160 ′ in which a plurality of nozzles 161 are two-dimensionally arranged are arranged in a staggered manner and connected. A line head having a nozzle row having a length corresponding to the entire width of the recording medium 114 may be configured. Although not shown, a line head may be configured by arranging short heads in a line.

  The pressure chamber 162 provided corresponding to each nozzle 161 has a substantially square planar shape, and is provided with a nozzle 161 and a supply port 164. Each pressure chamber 162 communicates with a common channel 165. The common channel 165 communicates with an ink supply tank (not shown) serving as an ink supply source, and ink is distributed and supplied to each pressure chamber 162 via the common channel 165.

  A diaphragm 250 constituting the top surface of the pressure chamber 162 is provided with a common electrode 260 (also referred to as a “lower electrode” in this example), a piezoelectric body 270, and an individual electrode 280 (main) via an insulator film 255. In the example, the piezoelectric element 300 including the “upper electrode” is joined, and by applying a driving voltage to the individual electrode 280, the piezoelectric element 300 is deformed and ink is ejected from the nozzle 161. When ink is ejected, new ink is supplied from the common channel 165 to the pressure chamber 162 through the supply port 164.

  On the piezoelectric element 300, a moisture-resistant protective film 200 made of an insulating material having moisture resistance is formed. The moisture-resistant protective film 200 covers the upper surface and side surfaces of the upper electrode 280 and the side surfaces of the piezoelectric body 270. Further, an opening 201 is formed in the moisture resistant protective film 200. Such a moisture-resistant protective film 200 can prevent damage to the piezoelectric element 300 due to moisture in the atmosphere. In addition, the opening 201 of the moisture-resistant protective film 200 can improve the ink ejection characteristics without hindering the displacement of the piezoelectric element 300.

  A liquid-resistant protective film 216 having liquid resistance is formed on the inner wall surfaces of the pressure chamber 162, the supply port 164, and the common flow path 165.

  In FIG. 3, a plurality of pressure chambers 162 and a plurality of piezoelectric elements 300 are formed, and a plurality of nozzle plates 220 on which a plurality of nozzles 161 are formed are fixed to a flow path forming substrate 210. A liquid discharge head 160 having a pressure chamber unit 163 is configured.

  As shown in FIG. 2B, the pressure chamber unit 163 having such a structure is constant along the row direction along the main scanning direction and the oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number of lattice patterns in an array pattern.

  That is, with the structure in which a plurality of pressure chamber units 163 are arranged at a constant pitch d along the direction of an angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 161 can be handled equivalently as a linear array with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  In the implementation of the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzle arrangement structures such as an arrangement structure having one nozzle row in the sub-scanning direction can be applied.

  Further, the application range of the present invention is not limited to a printing method using a line-type head, and a short head that is less than the length in the width direction (main scanning direction) of the recording medium 114 is scanned in the width direction of the recording medium 114. Printing in the width direction is performed, and when printing in one width direction is completed, the recording medium 114 is moved by a predetermined amount in a direction (sub-scanning direction) perpendicular to the width direction of the recording medium 114, and the recording medium 114 in the next printing area is moved. A serial method may be applied in which printing in the width direction is performed and printing is performed over the entire printing area of the recording medium 114 by repeating this operation.

  Next, the manufacturing method of the liquid discharge head according to the present invention will be described separately for the first embodiment and the second embodiment. In particular, the main part of the method for manufacturing a liquid ejection head according to the present invention, that is, a procedure for correcting displacement variation between piezoelectric elements 300 will be described.

(First embodiment)
FIG. 4 is a flowchart showing an exemplary flow of a displacement variation correction procedure in the first embodiment.

  In step S <b> 2, the piezoelectric element 300 is formed on the flow path forming substrate 210. As illustrated in FIG. 3, the piezoelectric element 300 includes a lower electrode 260, a piezoelectric body 270, and an upper electrode 280. A specific example of forming the piezoelectric element 300 will be described later. In this example, formation of the moisture-resistant protective film 200 on the piezoelectric element 300, formation of the pressure chamber 162, and formation of the liquid-resistant protective film 216 on the inner wall surface of the pressure chamber 162 are performed in step S10 described later.

  In step S4, a parameter that determines the amount of displacement of the piezoelectric element 300 is measured. In this example, not only the capacitance of the piezoelectric element 300 is measured, but also the size of the piezoelectric element 300 that causes variation in the deformation amount is measured. In the following, for convenience of explanation, a case will be described in which the capacitance of the piezoelectric element 300 and the thickness of the piezoelectric body 270 (hereinafter referred to as “piezoelectric body thickness”) are measured and the displacement variation is corrected based on these measurement results. Alternatively, the displacement variation may be corrected by measuring another size of the piezoelectric element 300 (for example, the area of the upper electrode 280).

  Examples of the method for measuring the thickness of the piezoelectric body include a method of measuring optically using a laser interferometer, a method of measuring mechanically using a step gauge, and the like.

  In step S6, a predicted value of the displacement amount of the piezoelectric element 300 is calculated based on the measurement result in step S4. In this example, the first displacement characteristic information indicating the correlation between the capacitance and size of the piezoelectric element 300 and the amount of displacement of the piezoelectric element 300 is used with the measurement result of the capacitance and the measurement result of the piezoelectric body thickness as parameters. Based on this, a predicted value of the displacement amount of the piezoelectric element 300 is calculated. For example, the amount of displacement is predicted using multiple regression analysis.

  The capacitance and the displacement amount have a correlation shown in FIG. 5, and the piezoelectric body thickness and the displacement amount have a correlation shown in FIG. Further, when the electrostatic capacity is an independent variable X1, the thickness of the piezoelectric body is an independent variable X2, and the displacement amount of the piezoelectric element 300 is a dependent variable Y, the displacement amount Y is expressed by Equation 1.

[Equation 1]
Y = a * X1 + b * X2 + C
Here, a and b are coefficients for the capacitance and the piezoelectric thickness, respectively. The coefficient a is determined from the correlation between the capacitance and the displacement shown in FIG. 5, and the coefficient b is determined from the correlation between the piezoelectric thickness and the displacement shown in FIG. C is a constant.

  FIG. 7 is an explanatory diagram showing the correlation between the displacement amount (theoretical value) predicted using Equation 1 and the actual value. According to experiments, the multiple correlation coefficient R was 0.9 or more.

  In step S8, the predicted value of the displacement amount of the piezoelectric element 300 obtained in step S6 is used as a parameter, based on the second displacement characteristic information indicating the correlation between the displacement amount of the piezoelectric element 300 and the machining correction value. Get the correction value. The processing correction value is a difference from a processing reference value applied to the flow path forming substrate 210 in order to correct the displacement variation in step S10. In the liquid discharge head 160 of the present example, the correction width includes the opening width of the pressure chamber 162, the width of the opening 201 of the moisture-resistant protective film 200, the thickness of the moisture-resistant protective film 200, and the liquid-resistant protective film 216 in the pressure chamber 162. There is thickness. FIG. 8A shows correlation data between the correction value of the opening width of the pressure chamber 162 and the amount of displacement of the piezoelectric element 300, and FIG. 8B shows the correction value of the width of the opening 201 of the moisture-resistant protective film 200. FIG. 8C shows correlation data between the correction value of the thickness of the moisture-resistant protective film 200 and the displacement amount of the piezoelectric element 300. FIG. Based on the correlation data of the item to be corrected, correction values (Wa, Wb, Wc) corresponding to the predicted displacement amount (Y) are acquired. The thickness of the liquid-resistant protective film 216 formed on the inner wall surface of the pressure chamber 162 may be acquired as a correction value.

  In step S10, the flow path forming substrate 210 is processed so as to have the correction value obtained in step S8. That is, processing is performed by changing the reference value by the correction value. In this example, the opening width of the pressure chamber 162, the opening width of the opening 201 of the moisture resistant protective film 200, or the thickness of the moisture resistant protective film 200 is corrected. The thickness of the liquid-resistant protective film 216 formed on the inner wall surface of the pressure chamber 162 may be corrected. A specific example of such processing will be described later.

  As described above, the case where the capacitance of the piezoelectric element 300 and the thickness of the piezoelectric body are measured and the variation in the displacement amount is corrected based on these measured values has been described as an example. The present invention can also be applied to the case where the area of the upper electrode 280 is measured and the displacement variation is corrected based on these measured values. The present invention can also be applied to the case where both the piezoelectric body thickness and the electrode area are measured together with the electrostatic capacity, and the displacement variation is corrected based on the measured values of the electrostatic capacity, the piezoelectric body thickness, and the electrode area. FIG. 9 is a graph showing the relationship between the electrode area and the amount of displacement.

  In addition, as a measuring method of an electrode area, the method of imaging with a digital camera and measuring by image processing is mentioned, for example.

  In other words, the present invention is based on not only the capacitance but also the size of the piezoelectric element 300 (for example, the thickness of the piezoelectric body and the electrode area) including the manufacturing variation that causes the variation in the displacement of the piezoelectric element 300. Correct the amount variation.

(Second Embodiment)
FIG. 10 is a flowchart showing a flow of an example of a displacement variation correction procedure in the second embodiment.

  Step S22 is the same as step S2 in the first embodiment.

  In step S24, the displacement amount or displacement volume of the piezoelectric element 300 is measured. In this example, the measurement of the capacitance of the piezoelectric element 300, the thickness of the piezoelectric body 270, and the area of the upper electrode 280 for predicting the displacement amount is not performed.

  As a method of measuring the displacement amount or displacement volume of the piezoelectric element 300, there is a method of measuring using a laser Doppler vibrometer. It is preferable to measure the displacement volume rather than the displacement amount. This parameter determines the actual discharge speed and discharge volume. For example, the displacement volume can be simply calculated by measuring the displacement at several points on the surface of the piezoelectric element 300 with a laser Doppler meter.

  Steps S26 and S28 are the same as steps S8 and S10 in the first embodiment, respectively.

[Manufacturing process]
Below, for easy understanding of the present invention, a case where the present invention is applied to a manufacturing method (hereinafter referred to as “conventional example”) described in Patent Document 1 (Japanese Patent Laid-Open No. 2008-114372) will be described. Note that the same points as in the conventional example are described in Patent Document 1 and will be described briefly, and points different from the conventional example will be described in detail.

  FIGS. 11 to 14 are process diagrams of the manufacturing process of the liquid ejection head 160 in the case where the displacement amount variation is corrected by the size of the pressure chamber 162.

  As shown in FIG. 11A, a diaphragm 250 made of a silicon dioxide film is formed on the surface of the flow path forming substrate 210. As shown in FIG. 11B, the diaphragm 250 is made of zirconium oxide. An insulator film 255 is formed, and a lower electrode 260 made of a conductor is formed on the insulator film 255 as shown in FIG. Next, as shown in FIG. 11D, a piezoelectric body 270 (piezoelectric layer) made of PZT (lead zirconate titanate) is formed, and as shown in FIG. The electrode 280 is formed and patterned to form the piezoelectric element 300 as shown in FIG. Next, as shown in FIG. 12C, after forming the protective film 200 over the entire surface of the flow path forming substrate 210, the protective film 200 is patterned into a predetermined shape to form the opening 201 and the like. As shown in FIG. 12D, the lead electrode 290 is formed over the entire surface of the flow path forming substrate 210.

  Next, as shown in FIG. 13A, the protective substrate 230 is bonded onto the flow path forming substrate 210 via an adhesive 235. Next, as shown in FIG. 13B, the flow path forming substrate 210 is thinned to a predetermined thickness. Next, as shown in FIG. 13C, a mask 252 is newly formed on the flow path forming substrate 210 and patterned into a predetermined shape. Then, as shown in FIG. 14A, the pressure chamber 162 corresponding to the piezoelectric element 300 and the like are formed by anisotropically etching (wet etching) the flow path forming substrate 210 through the mask 252. Next, as shown in FIG. 14B, a liquid-resistant protective film 216 is formed on the inner wall surface of the pressure chamber 162.

  In this example, as shown in FIG. 11D, after forming the piezoelectric body 270 on the flow path forming substrate 210, the thickness of the piezoelectric body 270 is measured. Also, as shown in FIG. 12B, after the upper electrode 280 is formed on the flow path forming substrate 210, the area of the upper electrode 280 is measured. Further, before the formation of the pressure chamber 162 (FIG. 14A), the capacitance of the piezoelectric body 270 of the piezoelectric element 300 is measured.

  In this example, the displacement amount of the piezoelectric element 300 is predicted based on the measured capacitance and at least one of the measured thickness of the piezoelectric body 270 and the area of the upper electrode 280. Based on the predicted amount of displacement, the width of the pressure chamber 162 (W1, W2 shown in FIG. 14A) is changed. When patterning the mask 252 as shown in FIG. 13C, the widths W1 and W2 of the pressure chamber 162 are changed by changing the opening area of the opening provided in the mask 252.

  Next, a case where the widths d1 and d2 of the openings 201 of the moisture-resistant protective film 200 on the piezoelectric element 300 are changed as shown in FIG. 15 will be described.

  In this example, the displacement amount of the piezoelectric element 300 is predicted based on the measured capacitance and at least one of the measured thickness of the piezoelectric body 270 and the area of the upper electrode 280. Based on the predicted amount of displacement, the widths d1 and d2 of the opening 201 of the moisture-resistant protective film 200 are changed.

  Next, as shown in FIG. 16, a case where the thicknesses t1 and t2 of the liquid-resistant protective film 216 in the pressure chamber 162 are changed will be described.

  In this example, the displacement amount of the piezoelectric element 300 is predicted based on the measured capacitance and at least one of the measured thickness of the piezoelectric body 270 and the area of the upper electrode 280. Based on the predicted displacement amount, the thicknesses t1 and t2 of the liquid-resistant protective film 216 in the pressure chamber 162 are changed.

  In the present invention, the processing for correcting the displacement amount of the piezoelectric element 300 includes changing the opening area of the pressure chamber 162, changing the thickness of the moisture-resistant protective film 200 on the piezoelectric element 300 or changing the opening area of the opening 201, and pressure. The present invention is not limited to the case where only one of the changes in the thickness of the liquid-resistant protective film 216 in the chamber 162 is changed. Based on the actually measured size of the piezoelectric element 300 (the thickness of the piezoelectric body 270, the electrode area, etc.), the correction target to be changed (the opening area of the pressure chamber 162, the thickness of the moisture resistant protective film 200 or the opening area of the opening 201, and the liquid resistance) The thickness of the protective film 216) may be selected, or all correction targets may be changed.

  Further, the measurement need not be performed for all the piezoelectric elements 300 on the flow path forming substrate 210. One or more piezoelectric elements 300 selected from a plurality of piezoelectric elements may be measured. Alternatively, the measurement may be performed for each of one or more piezoelectric elements 300 selected from each piezoelectric element group including a plurality of piezoelectric elements 300.

  Further, a correction value is calculated for each piezoelectric element 300, and the opening area of the plurality of pressure chambers 162, the thickness or opening width of the moisture-resistant protective film 200 on the plurality of piezoelectric elements 300, or the liquid resistance of the plurality of pressure chambers 162. When the thickness of the protective film 216 is changed for each piezoelectric element 300, the present invention is not limited. A correction value is calculated for each piezoelectric element group, and the opening area of the plurality of pressure chambers 162, the thickness or opening width of the moisture-resistant protective film 200 on the plurality of piezoelectric elements 300, or the liquid-resistant protective film of the plurality of pressure chambers 162 The thickness of 216 may be changed for each piezoelectric element group.

  The present invention is not limited to the examples described in the present specification and the examples illustrated in the drawings, and various design changes and improvements may be made without departing from the scope of the present invention. is there.

1 is an overall configuration diagram illustrating an example of an image forming apparatus including a liquid ejection head to which the present invention is applied. (A) Plane perspective view showing a structural example of the liquid ejection head, (b) is an enlarged view of (a), and (c) is a plan perspective view showing another structural example. Sectional view showing a three-dimensional configuration of a part of the liquid discharge head The flowchart which shows the flow of an example of the displacement amount variation | variation correction procedure of the piezoelectric element in 1st Embodiment. Graph showing the relationship between capacitance and displacement Graph showing the relationship between piezoelectric thickness and displacement Graph showing the relationship between the theoretical value and actual value of displacement (A) is a graph showing the relationship between the pressure chamber opening width and the displacement amount, (b) is a graph showing the relationship between the moisture resistant protective film opening width and the displacement amount, and (c) is a relationship between the moisture resistant protective film thickness and the displacement amount. Graph showing relationship Graph showing the relationship between electrode area and displacement The flowchart which shows the flow of an example of the displacement amount dispersion | variation correction procedure of the piezoelectric element in 2nd Embodiment. Step 1 of the first example of the manufacturing process of the liquid discharge head Step 2 of the first example of the manufacturing process of the liquid discharge head Process diagram 3 of the first example of the manufacturing process of the liquid discharge head 3 Step 4 of the first example of the manufacturing process of the liquid discharge head Process drawing used to explain the second example of the manufacturing process of the liquid discharge head Process drawing used to explain the third example of the manufacturing process of the liquid discharge head

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Inkjet recording apparatus, 160 ... Ink discharge head (liquid discharge head), 161 ... Nozzle, 162 ... Pressure chamber, 163 ... Liquid discharge element, 200 ... Moisture-resistant protective film, 201 ... Opening of moisture-resistant protective film, 210 ... Flow Path forming substrate, 216 ... Liquid-resistant protective film, 220 ... Nozzle plate, 250 ... Vibration plate, 260 ... Lower electrode (common electrode), 270 ... Piezoelectric body, 280 ... Upper electrode (individual electrode), 300 ... Piezoelectric element

Claims (8)

A piezoelectric element forming step of forming a piezoelectric element having a piezoelectric body and an electrode on a substrate on which a pressure chamber communicating with a nozzle for discharging liquid is formed;
A measurement step of actually measuring the capacitance of the formed piezoelectric element and the size of the piezoelectric element;
A displacement amount predicting step of predicting a displacement amount of the piezoelectric element from an actual measurement result of the measuring step;
A correction value determining step for determining a correction value of a machining process for changing the displacement amount of the piezoelectric element based on the predicted displacement amount of the piezoelectric element;
A processing step of correcting variation in displacement between the piezoelectric elements by performing the processing using the correction value;
A method for manufacturing a liquid discharge head, comprising: In the correction value determination step, a correction value of the opening area of the pressure chamber is determined,
The method of manufacturing a liquid ejection head according to claim 1, wherein the pressure chamber is formed in the substrate based on the correction value in the processing step. In the correction value determination step, at least one of a thickness of a protective film formed on the piezoelectric element and an opening area of an opening formed in the protective film is determined;
3. The method of manufacturing a liquid ejection head according to claim 1, wherein, in the processing step, the protective film is formed on the piezoelectric element based on the correction value. In the correction value determination step, determine the thickness of the liquid-resistant protective film formed in the pressure chamber,
4. The liquid processing apparatus according to claim 1, wherein, in the processing step, the pressure chamber is formed in the substrate, and the liquid-resistant protective film is formed in the pressure chamber based on the correction value. 5. 2. A method for manufacturing a liquid discharge head according to item 1.   5. The size of the piezoelectric element measured in the measuring step is at least one of a thickness of the piezoelectric body and an area of the electrode. 6. A manufacturing method of a liquid discharge head given in 2. Based on the first displacement characteristic information indicating the relationship between the capacitance and size of the piezoelectric element and the displacement amount of the piezoelectric element, the measured capacitance of the piezoelectric element, and the measured size of the piezoelectric element. Predicting the amount of displacement of the piezoelectric element,
The correction value is obtained based on second displacement characteristic information indicating a relationship between the displacement amount of the piezoelectric element and the correction value, and the predicted displacement amount of the piezoelectric element. 6. A method for manufacturing a liquid discharge head according to claim 1. A piezoelectric element forming step of forming a piezoelectric element having a piezoelectric body and an electrode on a substrate on which a pressure chamber communicating with a nozzle for discharging liquid is formed;
A measurement step of actually measuring the displacement amount or displacement volume of the formed piezoelectric element;
A correction value determining step for determining a correction value for processing for changing the displacement amount of the piezoelectric element based on the actual measurement result of the measuring step;
A processing step of correcting variation in displacement between the piezoelectric elements by performing the processing using the correction value;
A method for manufacturing a liquid discharge head, comprising: In the correction value determination step, at least one of a thickness of a protective film formed on the piezoelectric element and an opening area of an opening formed in the protective film is determined;
8. The method of manufacturing a liquid discharge head according to claim 7, wherein the protective film is formed on the piezoelectric element based on the correction value in the processing step.

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