JP2007283729A - Manufacturing method of liquid injection head and image-forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a liquid injection head which minimizes a deterioration in a piezoelectric element. <P>SOLUTION: The manufacturing method of the liquid injection head includes the step of forming a lower electrode layer on a substrate, the step of forming a piezoelectric layer on the lower electrode layer, the step of etching for etching the substrate up to the lower electrode layer from the opposite to a substrate's surface which has the piezoelectric layer in a region narrower and within the region covered by the piezoelectric layer and, the step of heat treatment for performing a heat treatment of the piezoelectric layer after the completion of the etching step, the step of forming a diaphragm layer using an ink-resistant film from a material having an ink-resistant property, also to serve as a diaphragm, on the substrate's surface etched during the etching step, and the step of forming an upper electrode layer on the piezoelectric layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a liquid discharge head and an image forming apparatus including the liquid discharge head manufactured by the method of manufacturing a liquid discharge head, and more particularly to a manufacturing technique for manufacturing a liquid discharge head.

  An ink jet recording apparatus equipped with a head (liquid ejection head) that ejects ink droplets from nozzles communicating with a pressure chamber by changing the wall surface of the pressure chamber using displacement of a piezoelectric element and pressurizing ink in the pressure chamber. Are known.

  In recent years, heads used in ink jet recording apparatuses have been required to be highly integrated, and in order to achieve high integration of the heads and to ensure high reliability and high performance, various structures and manufacturing devices have been made. ing. For example, when a thin film piezoelectric element (piezoelectric actuator) is used as the ejection force generating element, the substrate (vibrating plate) is piezoelectrically formed by a thin film forming technique such as aerosol deposition (AD) method, sol-gel method, sputtering, CVD, or screen printing method. There is a method of forming (depositing) a body layer and an electrode.

  In Patent Document 1, a liquid having a step of forming a piezoelectric film in a state where an ink storage chamber and a vibration plate are bonded, and then crystallizing the piezoelectric film by subjecting the piezoelectric film to annealing treatment. A method for manufacturing a transfer device is disclosed. Specifically, since the piezoelectric film is formed in a highly rigid state in which the vibration plate is assembled to the ink storage portion, even when the thickness of the vibration plate is as thin as about 10 μm to 50 μm, A technique capable of sufficiently withstanding the impact force of the above is disclosed.

  Patent Document 2 discloses a method of providing an insulating layer for preventing diffusion between a diaphragm and a lower electrode in order to prevent lead (Pb) in a piezoelectric body from diffusing into a silicon substrate. .

Patent Document 3 discloses a method of forming a diaphragm from the pressure chamber side after forming a piezoelectric layer, paying attention to the fact that the material constituting the diaphragm diffuses into the piezoelectric body and lowers the piezoelectric characteristics. Has been.
JP 2005-35013 A JP 2005-168172 A JP 2004-9399 A

However, a piezoelectric material such as PZT (Pb (Zr · Ti) O ₃ , lead zirconate titanate) is formed on a diaphragm (substrate) using a metal containing iron or chromium such as stainless steel (SUS). When annealing is performed at a high temperature of 600 ° C. or higher, there is a problem that iron and chromium contained in the diaphragm diffuse into the piezoelectric body and deteriorate the performance of the piezoelectric body. When iron diffuses in the piezoelectric body, it causes deterioration in performance of the piezoelectric element such as a decrease in piezoelectric d constant and insulation performance.

  In the invention described in Patent Document 1, heat treatment (annealing) is performed for several hours in a high temperature atmosphere of 600 ° C. to 750 ° C. (AD method) and 600 ° C. to 1200 ° C. (sol-gel method). When the substrate is used, iron and chromium contained in the diaphragm are diffused into the piezoelectric element and the performance of the piezoelectric element is deteriorated. In addition, an annealing atmosphere is required for the piezoelectric element deposited by the AD method (aerosol deposition method), and the surface of the diaphragm that is annealed at the same time is oxidized, resulting in deterioration of the durability of the diaphragm. And the problem that the bondability with other members deteriorates occurs.

  In addition, the thinner the diaphragm, the better characteristics can be obtained, but it is difficult to perform processing using a stainless steel substrate having a thickness of 10 [μm] or less due to the problem of pinholes during rolling. . Further, when manufacturing a large liquid discharge head, it is necessary to make the thickness of the substrate uniform, but it is difficult to manufacture a large substrate with a thickness of 10 [μm] or less uniformly.

  In the invention described in Patent Document 2, in order to completely prevent the diffusion of Pb, it is necessary to increase the thickness of the insulating layer for preventing the diffusion. However, the vibration plate becomes thick and the displacement becomes small, and the characteristics as a liquid discharge head deteriorate.

  In the invention described in Patent Document 3, since the piezoelectric body is formed on the substrate at a high temperature, when the piezoelectric layer is formed, diffusion of the constituent material contained in the substrate from the substrate to the piezoelectric body, Diffusion of Pb or the like from the piezoelectric body to the substrate occurs, thereby deteriorating the characteristics of the piezoelectric body and reducing the adhesion between the piezoelectric body and the substrate.

  The present invention has been made in view of such circumstances, and prevents the diffusion of the constituent materials contained in the substrate from the substrate to the piezoelectric body and the diffusion of Pb and the like from the piezoelectric body to the substrate, and the performance of the piezoelectric body. An object of the present invention is to provide a method for manufacturing a highly reliable liquid discharge head without deterioration of the image quality, and to provide an image forming apparatus with a high yield.

  The invention described in claim 1 includes a lower electrode layer forming step of forming a lower electrode layer on a substrate, a piezoelectric layer forming step of forming a piezoelectric layer on the lower electrode layer, and a piezoelectric layer covering the lower electrode layer. An etching step for etching the substrate to the lower electrode layer from a surface opposite to the surface on which the piezoelectric layer of the substrate is formed in a region that is within the region that is narrower than the region, and the etching step After completion of the heat treatment step, the piezoelectric layer is heat-treated, and after completion of the heat treatment step, the substrate surface etched in the etching step is used both as an ink-resistant film made of an ink-resistant material and a vibration plate. A method for manufacturing a liquid discharge head, comprising: a diaphragm layer forming step for forming a diaphragm layer; and an upper electrode layer forming step for forming an upper electrode layer on the piezoelectric layer.

  According to a second aspect of the present invention, in the upper electrode layer forming step, the upper electrode layer to be formed is within a region where the substrate is etched by the etching step via the piezoelectric layer and the lower electrode layer. The method of manufacturing a liquid ejection head according to claim 1, wherein the region is the same as or narrower than the region.

  The invention described in claim 3 is characterized in that the piezoelectric layer forming method in the piezoelectric layer forming step is formed by an aerosol deposition method or a screen printing method. It is a manufacturing method of a head.

  According to a fourth aspect of the present invention, in the method for manufacturing a liquid ejection head according to any one of the first to third aspects, the method for forming the diaphragm layer in the diaphragm layer forming step is a CVD method. is there.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the diaphragm layer in the diaphragm layer forming step is made of a material made of SiCN, ZrO ₂ , or SiO _2. It is a manufacturing method of the liquid discharge head of description.

  According to the sixth aspect of the present invention, Sk is the thermal expansion coefficient of the material constituting the substrate, Ck is the thermal expansion coefficient of the material constituting the lower electrode layer, and the thermal expansion coefficient of the material constituting the piezoelectric layer. 6. The method of manufacturing a liquid discharge head according to claim 1, wherein when Pk is satisfied, Sk <Ck <Pk or Pk <Ck <Sk.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising the liquid discharge head manufactured by the method of manufacturing a liquid discharge head according to any one of the first to sixth aspects.

  According to the method of manufacturing a liquid discharge head according to the present invention, it is possible to prevent diffusion of atoms constituting the substrate from the substrate to the piezoelectric body and diffusion of atoms constituting the piezoelectric body from the piezoelectric body to the substrate. A highly reliable liquid discharge head can be manufactured without deteriorating the performance of the body or reducing the adhesion between the substrate and the piezoelectric body. Moreover, a thin diaphragm of 10 [μm] or less free from defects such as pinholes can be formed, and high displacement characteristics can be obtained as a piezoelectric actuator. Furthermore, the image forming apparatus having the liquid discharge head manufactured thereby has an ink resistant coating on the inner surface of the pressure chamber at the same time as the formation of the vibration plate. And reliable.

  Embodiments of the present invention will be described below.

[Liquid discharge head]
A method for manufacturing a liquid discharge head according to the present invention will be described with reference to FIGS.

  FIG. 1 shows the steps of a method for manufacturing a liquid discharge head according to the present invention. FIG. 2 shows a process flow.

  First, the lower electrode layer forming step of step 102 (S102) shown in FIG. 2 is performed. Specifically, as shown in FIG. 1A, a lower electrode layer 62 is formed on substantially the entire surface of one surface of a substrate 61 made of stainless steel processed to a thickness Ht: 100 [μm]. The lower electrode layer 62 is made of a material made of a metal such as Pt or Ir, and has a thickness of 0.1 to 3 [μm] by a technique such as sputtering, vacuum deposition, or screen printing. To form. The material constituting the substrate 61 may be a metal other than stainless steel or Si.

  Next, the piezoelectric layer forming step of Step 104 (S104) shown in FIG. 2 is performed. Specifically, as shown in FIG. 1B, a piezoelectric layer 63 is formed on the lower electrode layer 62 by an AD method or a screen printing method. In both the AD method and the screen printing method, a heat treatment (annealing treatment) is performed in a later heat treatment step. In the case of the screen printing method, 600 ° C. or less is required for drying the printed piezoelectric paste and improving adhesion. And calcining. Above 600 ° C., when the substrate 61 is made of stainless steel, Fe or the like diffuses from the substrate 61 to the piezoelectric layer 63, or Pb or the like diffuses from the piezoelectric layer 63 to the substrate 61. This is because the characteristic of 63 deteriorates.

  The piezoelectric layer 63 may be formed on substantially the entire surface of the lower electrode layer 62, but may be formed separately on the lower electrode layer 62 corresponding to each pressure chamber as shown in FIG. Good. By forming the piezoelectric layer 63 separately, the amount of displacement when a voltage is applied can be increased, crosstalk can be reduced, and there is an advantage that the substrate 61 is not warped by stress or the like. This is desirable. In the present embodiment, as shown in FIG. 1B, a pattern of the piezoelectric layer 63 having a square shape with a thickness Pt and a side width Pw is formed.

  Thereafter, the etching process of step 106 (S106) shown in FIG. 2 is performed. Specifically, as shown in FIG. 1C, a region serving as a pressure chamber is formed by etching on the surface of the substrate 61 opposite to the surface on which the piezoelectric layer 63 is formed.

  In the present embodiment, a resist is applied to the entire surface of the substrate 61 where the piezoelectric layer 63 is formed, or a resist is applied to both surfaces of the substrate 61. Specifically, the resist is applied by a technique such as spin coater or dip coating. Thereafter, pre-baking is performed, and exposure is performed by an exposure apparatus using a mask having a pressure chamber-shaped pattern formed on the surface of the substrate 61 opposite to the surface on which the piezoelectric layer 63 is formed, and development is performed. Thereby, the resist is removed only in the region where the pressure chamber is formed. Thereafter, in order to etch the resist-removed region of the substrate 61 on the resist-formed surface of the substrate 61, wet etching is performed by dropping an etching solution or immersing the substrate 61 in the etching solution. I do.

  As the solution used for wet etching, a ferric chloride solution is used when the substrate 61 is stainless steel, and a KOH (potassium hydroxide) solution is used when the substrate 61 is Si.

  As shown in FIG. 1C, the wet etching is performed until the substrate material in the region where the resist is not formed in the substrate 61 is completely removed. That is, the process is performed until the back surface of the lower electrode layer 62 formed on the opposite surface of the substrate 61 on which the resist is formed is completely exposed.

  Therefore, the width Hw of the region serving as the pressure chamber in the substrate 61 is narrower than the width Pw in which the piezoelectric layer 63 is formed, and the region in which the piezoelectric layer 63 is formed passes through the lower electrode layer 62. It is necessary to overlap the unetched region on both sides of the piezoelectric layer 63. This is because the lower electrode layer 62 is so thin that the piezoelectric layer 63 is formed to be narrower than the width Hw of the region serving as the pressure chamber in the substrate 61, that is, through the lower electrode layer 62. This is because when the substrate 61 and the piezoelectric layer 63 do not overlap, it is difficult to maintain the form after etching. Therefore, the width Pw of the piezoelectric layer 63 needs to be formed wider than the width Hw of the region serving as the pressure chamber formed in the substrate 61. In other words, the region where the substrate 61 is etched to form the pressure chamber is covered with the piezoelectric layer 63 via the lower electrode layer 62.

  In the present embodiment, the piezoelectric layer 63 is formed in a substantially square shape having a thickness Pt: 8 [μm] and a side width Pw: 300 [μm], and the pressure chamber has a width Hw of one side of the substrate 61. : Formed by etching a substantially square region of 250 [μm]. For this reason, the unetched region of the substrate 61 and the region where the piezoelectric layer 63 is formed are 25 [μm] on both sides in the peripheral portion of the piezoelectric layer 63, a total of 50 [μm], and the lower electrode layer. 62 is an overlapping structure.

  Note that it is desirable that the overlapping region between the substrate 61 and the piezoelectric layer 63 overlaps 5% or more of the width Hw of the piezoelectric layer 63 in view of form stability after etching. This is because if this width is too narrow, it will be difficult to maintain form stability. In the present embodiment, the width Pw of the piezoelectric layer 63 is 300 [μm], whereas the width of the overlapping region is 50 [μm]. Therefore, the piezoelectric layer 63 and the substrate 61 are etched. There is 16.7% overlap with the non-existing region.

  Thereafter, the heat treatment step of Step 108 (S108) shown in FIG. 2 is performed. Specifically, when the piezoelectric layer 63 is formed by the AD method, heat treatment (annealing) is performed at 700 ° C. or more, and when the piezoelectric layer 63 is formed by the screen printing method, heat treatment (annealing) is performed at 850 ° C. or more. This heat treatment has the effect of improving the crystallinity of the piezoelectric body of the piezoelectric layer 63 and improving the characteristics of the piezoelectric body. In general, the heat treatment temperature is 700 ° C. to 1000 ° C. in the case of the AD method, and about 850 ° C. to 1300 ° C. in the case of the screen printing method. A film formation method is selected in consideration of heat resistance.

Therefore, when the thermal expansion coefficient of the material forming the substrate 61 is Sk, the thermal expansion coefficient of the material forming the lower electrode layer 62 is Ck, and the thermal expansion coefficient of the material forming the piezoelectric layer 63 is Pk, Sk It is preferable that <Ck <Pk or Pk <Ck <Sk. That is, if the value of the coefficient of thermal expansion Ck of the material constituting the lower electrode layer 62 is significantly larger or smaller than both of the materials constituting the substrate 61 and the piezoelectric layer 63, the piezoelectric layer 63 is peeled off. Because it occurs. Therefore, it is preferable that the substrate 61, the lower electrode layer 62, and the piezoelectric layer 63 are made of materials in which the thermal expansion coefficient increases or decreases in this order. In the present embodiment, the substrate 61 is SUS304 (thermal expansion coefficient: 10.4 × 10 ⁻⁶ ), the lower electrode layer 62 is Pt (platinum, thermal expansion coefficient: 8.8 × 10 ⁻⁶ ), and the piezoelectric layer 63. Is made of PZT (lead zirconate titanate, thermal expansion coefficient: 8 × 10 ⁻⁶ ), and the relationship of Pk <Ck <Sk is established. In addition, when Si (thermal expansion coefficient: 2.8 × 10 ⁻⁶ ) is used for the substrate 61, by selecting the material of the lower electrode layer 62 and the piezoelectric layer 63 based on the relationship of the thermal expansion coefficient, It is possible to prevent the piezoelectric layer 63 from peeling off.

  In the present embodiment, the etching method of the substrate 61 by wet etching has been described. However, the etching can be performed by a dry etching method such as RIE as in the present embodiment.

Next, the diaphragm layer forming step of Step 110 (S110) shown in FIG. 2 is performed. Specifically, as shown in FIG. 1D, a vibration plate layer 64 that serves both as an ink-resistant film and a vibration plate is formed on the etched surface of the substrate 61. The diaphragm layer 64 serves as both a diaphragm and an ink-resistant film, and is formed thick on the surface of the lower electrode layer 62 and thin on the surface of the other substrate 61. Examples of the material constituting the diaphragm layer 64 include SiCN, SiO ₂ , and ZiO ₂ . When the substrate 61 is made of stainless steel, the ink-resistant film has an adverse effect on the ink when the substrate 61 and the ink come into contact with each other, and Fe (iron) contained in the substrate 61 dissolves in the ink. It is provided to prevent giving. For this reason, the diaphragm layer 64 needs to be a method that can be formed on all surfaces of the wall surface of the pressure chamber formed by etching the substrate 61. In this embodiment, the SiCN film is formed by the CVD method.

  Specifically, a method for forming a SiCN (silicon carbonitride) film by a plasma CVD method which is one of the CVD methods will be described.

In the vacuum chamber of the plasma CVD apparatus, the diaphragm 61 is installed on the etched surface of the substrate 61 and then evacuated. After evacuating the vacuum chamber to a predetermined pressure, a mixed gas of SiH ₄ (silane), NH ₃ (ammonia), and CH ₄ (methane) is introduced into the vacuum chamber. Thereafter, an RF electric field is applied to generate plasma. The RF power applied at this time is 500 [W], and the diaphragm 61 is heated to 350 [° C.]. The mixed gas of SiH ₄ (silane), NH ₃ (ammonia), and CH ₄ (methane) introduced into the vacuum chamber reacts in the plasma, and the resulting SiCN is formed on the diaphragm 61 as a film. The The pressure in the vacuum chamber at this time is 67 [Pa]. The SiCN film formed by this film forming method becomes a dense amorphous film. As a result, the SiCN film is formed on the lower electrode layer 62 as a film functioning as a vibration plate, 8 [μm], and the side surface of the pressure chamber formed by etching the substrate 61 functions as an ink-resistant layer. As a film to be formed, 2 [μm] is formed.

ZrO ₂ (zirconium oxide) can also be formed by the plasma CVD method, but the substrate temperature during film formation is 550 [° C.].

  Thereafter, an upper electrode layer forming step of step 112 (S112) shown in FIG. 2 is performed. Specifically, as shown in FIG. 1E, a conductive material such as Au (gold) is formed as the upper electrode layer 65 by sputtering. The width Cw in which the upper electrode layer 65 is formed is formed in a region that is the same as or narrower than the width Hw of the pressure chamber formed in the substrate 61 by etching. Specifically, the upper electrode layer 65 is interposed between the piezoelectric layer 63 and the lower electrode layer 62 so that the width Cw of the upper electrode layer 65 is 80% to 100% of the width Hw of the pressure chamber. It forms in the area | region which does not overlap with the area | region which is not etched.

  In this embodiment, the upper electrode layer 65 is formed in a square shape having a side width Cw of 225 [μm], and the width Hw of the pressure chamber formed by etching is 250 [μm]. %]. As described above, the upper electrode layer 65 is formed in a narrower region than the region where the pressure chambers are formed. In the region where the piezoelectric layer 63 and the substrate 61 overlap with the lower electrode layer 62, heat treatment is performed. In the process, the diffusion of atoms from the substrate 61 to the piezoelectric layer 63 or the diffusion of atoms from the piezoelectric layer 63 to the substrate 61 occurs, so that the piezoelectric layer 63 in this region is deteriorated in characteristics. Because. In particular, when stainless steel is used as the material of the substrate 61, Fe diffuses from the substrate 61 to the piezoelectric layer 63, and the piezoelectric layer 63 in this region has conductivity. This is because even if an electric field is applied to the lower electrode layer 62, a current flows, no displacement occurs, and the function as a piezoelectric element is not exhibited.

  Thereafter, the nozzle plate bonding step in step 114 (S114) shown in FIG. 2 is performed. Specifically, the nozzle plate 66 is bonded to the etched surface of the substrate 61 as shown in FIG. Thereby, the liquid discharge head is completed.

  In this embodiment, the upper electrode layer 65 is formed in step 112. However, the upper electrode layer 65 may be formed after the piezoelectric layer forming step in step 104. Specifically, between the piezoelectric layer forming process at step 104 and the etching process at step 106, between the etching process at step 106 and the heat treatment process at step 108, between the heat treatment process at step 108 and the diaphragm forming process at step 110. The upper electrode layer 65 can be formed at any time.

  In the liquid discharge head formed in this way, from the viewpoint of processing accuracy and cost, when Si (silicon) or stainless steel (SUS) is used as a substrate and the piezoelectric body is formed by the AD method and the screen printing method, the liquid discharge head has a high temperature ( 700 [° C.] or higher) is required. However, in the present invention, since the substrate 61 and the piezoelectric layer 63 overlap with each other at both ends of the piezoelectric layer 63 via the lower electrode layer 62, the piezoelectric body due to the diffusion of elements from the substrate 61 to the piezoelectric layer 63. It is possible to reduce the influence such as the characteristic deterioration of the layer 63.

  Furthermore, in the pressure chamber, in order to prevent adverse effects on the ink, it is necessary to form an ink-resistant film on the wall surface of the pressure chamber. In the present invention, the ink-resistant film and the vibration plate are simultaneously formed of the same material. Therefore, the process can be simplified and the cost can be reduced.

[Overall configuration of inkjet recording apparatus]
FIG. 5 is an overall configuration diagram showing an outline of an ink jet recording apparatus which is an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 5, the inkjet recording apparatus 10 includes a printing unit having a plurality of liquid ejection heads (hereinafter sometimes simply referred to as “heads”) 12K, 12C, 12M, and 12Y provided for each color of ink. 12, an ink storage / loading unit 14 that stores ink to be supplied to each of the heads 12 </ b> K, 12 </ b> C, 12 </ b> M, and 12 </ b> Y, a paper feeding unit 18 that supplies recording paper 16, and a decurl that removes curl from the recording paper 16 An adsorption belt that is disposed to face the processing unit 20 and the nozzle surfaces (ink ejection surfaces) of the heads 12K, 12C, 12M, and 12Y and conveys the recording paper 16 while maintaining the flatness of the recording paper 16 (recording medium). A conveyance unit 22, a print detection unit 24 that reads a printing result by the printing unit 12, and a paper discharge unit 26 that discharges printed recording paper (printed material) to the outside.

  In FIG. 5, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  In the case of an apparatus configuration using roll paper, a cutter 28 is provided as shown in FIG. 5, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is arranged on the print surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and faces at least the nozzle surfaces of the heads 12K, 12C, 12M, and 12Y and the sensor surface of the print detection unit 24. The part to be made is a flat surface.

  The belt 33 has a width that is wider than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 5, an adsorption chamber 34 is provided at a position facing the nozzle surface of the print unit 12 and the sensor surface of the print detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. Then, the suction chamber 34 is sucked by the fan 35 to be a negative pressure, whereby the recording paper 16 on the belt 33 is sucked and held. The power of the motor (not shown in FIG. 5 and indicated by reference numeral 88 in FIG. 9) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 rotates clockwise in FIG. , And the recording paper 16 held on the belt 33 is conveyed from left to right in the drawing.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blowing method of spraying clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the printing area, the roller comes into contact with the printing surface of the paper immediately after printing, so that the image blurs. There is a problem that it is easy. Therefore, as in this example, suction belt conveyance that does not contact the image surface in the printing region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  FIG. 6 is a principal plan view showing the periphery of the printing unit 12 of the inkjet recording apparatus 10.

  As shown in FIG. 6, the printing unit 12 is a so-called full-line type in which a line-type head having a length corresponding to the maximum paper width is arranged in a direction (main scanning direction) perpendicular to the paper feeding direction (sub-scanning direction). Has a head. Each of the heads 12K, 12C, 12M, and 12Y constituting the printing unit 12 has a plurality of ink discharge ports (nozzles) arranged over a length exceeding at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10. Line type head.

  Heads 12K, 12C, and 12M corresponding to the respective color inks in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side (left side in FIG. 6) along the conveyance direction of the recording paper 16. , 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the heads 12K, 12C, 12M, and 12Y while conveying the recording paper 16, respectively.

  Thus, according to the printing unit 12 in which the full line head that covers the entire area of the paper width is provided for each ink color, the operation of relatively moving the recording paper 16 and the printing unit 12 in the paper feeding direction is performed once. It is possible to record an image on the entire surface of the recording paper 16 only by performing it (that is, in one sub-scan). Thus, high-speed printing is possible and productivity can be improved as compared with a shuttle-type head in which the head reciprocates in the main scanning direction orthogonal to the paper feed direction.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a head for ejecting light-colored ink such as light cyan and light magenta.

  As shown in FIG. 5, the ink storage / loading unit 14 has tanks for storing inks of colors corresponding to the heads 12K, 12C, 12M, and 12Y, and each tank is connected via a pipe line (not shown). The heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means, etc.) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. is doing.

  The print detection unit 24 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the print unit 12, and checks for nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor. Function as.

  The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) of the heads 12K, 12C, 12M, and 12Y. The line sensor includes an R sensor row in which photoelectric conversion elements (pixels) provided with red (R) color filters are arranged in a line, a G sensor row provided with green (G) color filters, The color separation line CCD sensor includes a B sensor array provided with a blue (B) color filter. Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads the test patterns printed by the heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the paper can be prevented from coming into contact with ozone or other materials that cause dye molecules to break by pressurizing the paper holes by pressurization. Has the effect of improving.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. ing. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Configuration of liquid discharge head]
Next, the structure of the head will be described. Since the structures of the respective heads 12K, 12C, 12M, and 12Y for each color are common, the heads are represented by the reference numeral 50 in the following.

  FIG. 7A is a plan perspective view showing an example of the structure of the head 50, and FIG. 7B is an enlarged view of a part thereof. FIG. 7C is a perspective plan view showing another structural example of the head 50.

  In order to increase the dot pitch printed on the recording paper 16, it is necessary to increase the nozzle pitch in the head 50. As shown in FIGS. 7A to 7C, the head 50 of this example includes a nozzle 51 that is an ink droplet ejection hole, a pressure chamber (liquid chamber) 52 corresponding to each nozzle 51, and a supply port 54. A plurality of ink chamber units 53 composed of, for example, are arranged in a staggered matrix (two-dimensionally), and are thus arranged along the head longitudinal direction (main scanning direction orthogonal to the paper feed direction). In this way, the effective nozzle interval (projection nozzle pitch) is narrowed to achieve high density.

  The form in which one or more nozzle rows are formed in the main scanning direction substantially orthogonal to the paper feed direction over a length corresponding to the entire width of the recording paper 16 is not limited to this example. For example, instead of the configuration of FIG. 7 (a), as shown in FIG. 7 (c), short head blocks 50 ′ in which a plurality of nozzles 51 are arranged in a two-dimensional manner are arranged in a staggered manner and joined together. Thus, a line head having a nozzle row having a length corresponding to the entire width of the recording paper 16 may be configured.

  In this example, the planar shape of the pressure chamber 52 is a substantially square shape, but the planar shape of the pressure chamber 52 is not limited to a substantially square shape, and may be a substantially circular shape, a substantially elliptical shape, or a substantially parallelogram ( Various shapes such as diamonds can be applied. Further, the arrangement of the nozzles 51 and the supply ports 54 is not limited to the arrangement shown in FIGS. 7A to 7C, and the nozzles 51 may be arranged at a substantially central portion of the pressure chamber 52. The supply port 54 may be disposed on the side wall side.

  As shown in FIG. 7B, a large number are arranged in a lattice pattern in a constant array pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. Thus, the high-density nozzle head of this example is realized.

  That is, with a structure in which a plurality of ink chamber units 53 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 in the main scanning direction is d × cos θ. Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which the number of nozzle rows projected so as to be aligned in the main scanning direction is 2400 per inch (2400 nozzles / inch).

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example, and various nozzles such as an arrangement structure having one nozzle array in the sub-scanning direction and a structure having two staggered nozzle arrays are included. Arrangement structure can be applied.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and each block is sequentially driven from one side to the other, etc., and one line (in one row of dots) in the width direction (main scanning direction) of the recording medium Driving a nozzle that prints a line or a line composed of a plurality of rows of dots is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIGS. 7A to 7C, main scanning as described in the above (3) is preferable.

  On the other hand, by moving the above-described full line head and the recording paper 16 relative to each other, printing of one line (a line composed of a single line of dots or a line composed of a plurality of lines of dots) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning.

  In this embodiment, the full line head is exemplified, but the scope of application of the present invention is not limited to this, and a short head having a nozzle row having a length shorter than the width of the recording paper 16 is used as the width of the recording paper 16. The present invention is also applicable to a serial head that performs printing in the width direction of the recording paper 16 while scanning in the direction.

  As shown in FIGS. 7A to 7C, the pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and is formed at both corners on the diagonal line. The formed nozzle 51 and the supply port 54 are provided. Each pressure chamber 52 communicates with a common channel (not shown) (common liquid chamber) via a supply port 54. The common flow path communicates with an ink supply tank (not shown), and the ink supplied from the ink supply tank is distributed and supplied to each pressure chamber 52 via the common flow path.

[Structure of liquid discharge head]
Next, details of the structure of the liquid discharge head will be described with reference to FIG.

  FIG. 3 is a cross-sectional view showing a three-dimensional configuration of the ink chamber unit 53.

  As shown in FIG. 3, the ink chamber unit 53 is formed by a pressure chamber 52 that communicates with a nozzle 51 that discharges ink provided on a nozzle plate 66, and supplies ink through a supply port (not shown). It communicates with the common liquid chamber. One surface (the top surface in the figure) of the pressure chamber 52 is composed of a diaphragm 56 formed by a diaphragm layer 64, a lower electrode layer 62 is formed on the upper portion thereof, and a diaphragm 56 is further formed on the upper portion thereof. A piezoelectric layer 63 that is an ultrasonic wave generating element to be deformed is bonded, and an upper electrode layer 65 is formed on the upper surface of the piezoelectric layer 63. The lower electrode layer 62, the piezoelectric layer 63, and the upper electrode layer 65 form a piezoelectric element 58.

  The piezoelectric layer 63 is sandwiched between the lower electrode layer 62 and the upper electrode layer 65, and is deformed by applying a driving voltage between the lower electrode layer 62 and the upper electrode layer 65. The diaphragm 56 is deformed by the deformation of the piezoelectric layer 63, the volume of the pressure chamber 52 is reduced, the ink in the pressure chamber 52 is pressurized, and the ink is ejected from the nozzle 51. . When the voltage applied between the lower electrode layer 62 and the upper electrode layer 65 is released, the piezoelectric layer 63 returns to the original state, and the volume of the pressure chamber 52 is restored to the original size, which is not shown. New ink is supplied from the common liquid chamber to the pressure chamber 52 through a supply port (not shown). Further, in the diaphragm layer forming step, the ink-resistant layer 67 formed on the side surface of the pressure chamber 52 simultaneously with the formation of the diaphragm 56 prevents the material constituting the substrate 61 from being dissolved in the ink and adversely affecting it. Yes.

[Discharge recovery device]
FIG. 8 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink tank 90 is a base tank for supplying ink to the print head 50, and is installed in the ink storage / loading unit 14 described with reference to FIG. In the form of the ink tank 90, there are a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the ink remaining amount is low. When the ink type is changed according to the usage, the cartridge method is suitable. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink tank 90 in FIG. 8 is equivalent to the ink storage / loading unit 14 in FIG. 5 described above.

  As shown in FIG. 8, a filter 92 is provided in the middle of the conduit connecting the ink tank 90 and the print head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter of the print head 50 (generally, about 20 μm).

  Although not shown in FIG. 8, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the ink jet recording apparatus 10 is provided with a cap 94 as a means for preventing the nozzle from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 96 as a means for cleaning the nozzle surface 50A.

  The maintenance unit including the cap 94 and the cleaning blade 96 can be moved relative to the print head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the print head 50 as necessary. It has come to be.

  The cap 94 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The lifting mechanism is configured to cover the nozzle region of the nozzle surface 50 </ b> A with the cap 94 by raising the cap 94 to a predetermined raised position when the power is turned off or waiting for printing.

  The cleaning blade 96 is made of an elastic member such as rubber, and can slide on the ink discharge surface (nozzle surface 50A) of the print head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matters adhere to the nozzle surface 50A, the nozzle surface 50A is wiped by sliding the cleaning blade 96 on the nozzle surface 50A, thereby cleaning the nozzle surface 50A.

  During printing or standby, when a specific nozzle 51 is used less frequently and the ink viscosity in the vicinity of the nozzle 51 increases, preliminary ejection toward the cap 94 is performed to discharge the ink that has deteriorated due to the increased viscosity. Is done.

  That is, if the print head 50 does not discharge for a certain period of time, the ink solvent near the nozzle evaporates and the viscosity of the ink near the nozzle increases, and the discharge driving actuator (piezoelectric element 58) operates. Even so, ink is no longer discharged from the nozzle 51. Therefore, before this state is reached (within the viscosity range in which ink can be ejected by the operation of the piezoelectric element 58), the piezoelectric element 58 is operated toward the ink receiver, and the ink in the vicinity of the nozzle whose viscosity has increased is removed. “Preliminary discharge” is performed. Further, after the dirt on the nozzle surface 50A is cleaned by a wiper such as a cleaning blade 96 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from being mixed into the nozzle 51 by the wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  Further, when bubbles are mixed into the ink in the print head 50 (ink in the pressure chamber 52), the cap 94 is applied to the print head 50, and the ink in the pressure chamber 52 (ink containing the bubbles) is applied by the suction pump 97. The ink removed by suction is sent to the collection tank 98. This suction operation is also performed when the initial ink is loaded into the head or when the ink is used after being stopped for a long time, and the deteriorated ink solidified by increasing the viscosity is sucked and removed.

  Specifically, when air bubbles are mixed into the nozzle 51 or the pressure chamber 52 or the viscosity increase of the ink in the nozzle 51 exceeds a certain level, ink is ejected from the nozzle 51 in the preliminary ejection for operating the piezoelectric element 58. become unable. In such a case, an operation in which the cap 94 is applied to the nozzle surface 50 </ b> A of the print head 50 and ink or thickened ink mixed with bubbles in the pressure chamber 52 is sucked by the pump 97.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. The cap 94 described in FIG. 8 functions as a suction unit and can also function as a preliminary discharge ink receiver.

  Preferably, the inside of the cap 94 is divided into a plurality of areas corresponding to the nozzle rows by a partition wall, and each of the partitioned areas can be selectively sucked by a selector or the like.

[Explanation of control system]
FIG. 9 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The inkjet recording apparatus 10 includes a communication interface 70, a system controller 72, an image memory 74, a motor driver 76, a heater driver 78, a print control unit 80, an image buffer memory 82, a head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB (Universal serial bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. The image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the memory 74. The memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 is a control unit that controls the communication interface 70, the memory 74, the motor driver 76, the heater driver 78, and the like. The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and performs communication control with the host computer 86, read / write control of the memory 74, and the like, and controls the motor 88 and heater 89 of the transport system. A control signal to be controlled is generated.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives a heater 89 such as the post-drying unit 42 (shown in FIG. 5) in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from image data in the memory 74 in accordance with the control of the system controller 72, and the generated print control. A control unit that supplies signals to the head driver 84. Necessary signal processing is performed in the print control unit 80, and the ejection amount and ejection timing (droplet ejection control) of the ink droplets of the head 12 are performed via the head driver 84 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 9, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  The head driver 84 drives the piezoelectric elements 58 of the heads 12K, 12C, 12M, and 12Y of the respective colors based on the print data given from the print control unit 80. The head driver 84 may include a feedback control system for keeping the head driving conditions constant.

As described with reference to FIG. 5, the print detection unit 24 is a block including a line sensor. The print detection unit 24 reads an image printed on the recording paper 16 and performs necessary signal processing and the like to perform a print status (whether ejection is performed, droplet ejection). And the detection result is provided to the print control unit 80.
The print controller 80 performs various corrections on the head 50 based on information obtained from the print detector 24 as necessary.

  The system controller 72 and the print control unit 80 may be configured by one processor, a device in which the system controller 72, the motor driver 76, and the heater driver 78 are integrated, or the print control unit 80 and the head. A device in which a driver is integrated may be used.

  The liquid ejection head and the image forming apparatus according to the present invention have been described in detail above. The present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the scope of the present invention.

Process drawing of manufacturing method of liquid discharge head according to the present invention Flowchart of manufacturing method of liquid discharge head according to the present invention The top view of the state which formed the piezoelectric material layer in the manufacturing method of the liquid discharge head concerning this invention Sectional drawing of the liquid discharge head manufactured by the manufacturing method of the liquid discharge head concerning this invention 1 is an overall configuration diagram of an image forming apparatus according to the present invention. FIG. 3 is a plan view of the main part around the printing unit of the image forming apparatus according to the present invention. Plane perspective view showing a structural example of a liquid discharge head Configuration diagram showing outline of ink supply system of liquid discharge head 1 is a block diagram of a main part showing a system configuration example of an image forming apparatus according to the present invention.

Explanation of symbols

61 ... Substrate, 62 ... Lower electrode layer, 63 ... Piezoelectric layer, 64 ... Vibration plate layer, 65 ... Upper electrode layer, 66 ... Nozzle plate, Ht ... Substrate thickness, Pt ... Piezoelectric layer thickness, Pw ... Piezoelectric layer Width, Hw: Substrate etching width, Cw: Upper electrode layer width

Claims (7)

A lower electrode layer forming step of forming a lower electrode layer on the substrate;
A piezoelectric layer forming step of forming a piezoelectric layer on the lower electrode layer;
Etching in which the substrate is etched to the lower electrode layer from a surface opposite to the surface of the substrate where the piezoelectric layer is formed in a region that is within the region covered by the piezoelectric layer and is narrower than the region. Process,
A heat treatment step for heat-treating the piezoelectric layer after the etching step;
After the heat treatment step, a vibration plate layer forming step of forming a vibration plate layer that doubles as an ink resistant film made of a material having ink resistance and a vibration plate on the substrate surface etched in the etching step;
An upper electrode layer forming step of forming an upper electrode layer on the piezoelectric layer;
A method for manufacturing a liquid discharge head, comprising:   In the upper electrode layer forming step, the upper electrode layer to be formed is within the range of the region where the substrate is etched by the etching step via the piezoelectric layer and the lower electrode layer, and is the same as the region, or The method of manufacturing a liquid discharge head according to claim 1, wherein the region is narrower than the region.   3. The method of manufacturing a liquid ejection head according to claim 1, wherein the piezoelectric layer forming method in the piezoelectric layer forming step is formed by an aerosol deposition method or a screen printing method.   4. The method of manufacturing a liquid ejection head according to claim 1, wherein the diaphragm layer forming method in the diaphragm layer forming step is a CVD method. 5. The method of manufacturing a liquid ejection head according to claim 1, wherein the diaphragm layer in the diaphragm layer forming step is made of a material made of SiCN, ZrO ₂ , or SiO ₂ . When the thermal expansion coefficient of the material constituting the substrate is Sk, the thermal expansion coefficient of the material constituting the lower electrode layer is Ck, and the thermal expansion coefficient of the material constituting the piezoelectric layer is Pk,
Sk <Ck <Pk or Pk <Ck <Sk
The method of manufacturing a liquid discharge head according to claim 1, wherein:   An image forming apparatus comprising a liquid discharge head manufactured by the method of manufacturing a liquid discharge head according to claim 1.

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