JP2007283757A - Piezoelectric actuator using aerosol deposition method, method for producing inkjet head and inkjet printer, and piezoelectric actuator inkjet head, and inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing technique of a piezoelectric actuator for an inkjet head capable of suppressing any degradation in printing quality due to thickness distribution as much as possible even when the thickness distribution occurs in the thin film layer formed on a substrate with the AD method. <P>SOLUTION: A piezoelectric material layer 31 is formed on a vibration plate 30 by jetting aerosol which contains particles of a piezoelectric material and a carrier gas, from a film forming nozzle to the vibration plate 30 while moving the film forming nozzle relative to the vibration plate 30 in a direction perpendicular to the scanning direction of the inkjet head 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a configuration and manufacturing technology of a piezoelectric actuator, an inkjet head having the piezoelectric actuator, and an inkjet printer.

  Some inkjet heads that eject ink from ejection nozzles include a piezoelectric actuator using a ferroelectric piezoelectric ceramic material such as lead zirconate titanate (PZT) as an actuator that applies ejection pressure to the ink. There is. A general piezoelectric actuator used in an ink jet head includes a substrate (also referred to as a diaphragm) that covers a pressure chamber containing ink, a piezoelectric material layer formed in a thin film on one surface of the substrate, and the piezoelectric material layer The electrode is configured to apply pressure to the ink in the pressure chamber by deforming the substrate using deformation of the piezoelectric material layer when the electric field is generated. Yes.

On the other hand, conventionally, as one method for forming a thin film on a flat substrate surface, an aerosol containing a particulate thin film material and a carrier gas is sprayed from a deposition nozzle toward the substrate, and the collision energy at that time There is known an aerosol deposition method (hereinafter referred to as AD method) in which particles are deposited on a substrate surface to form a film. Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-122341) discloses a method of forming a piezoelectric material layer such as a piezoelectric actuator in the form of a thin film on the surface of a substrate using this AD method. According to this method, while the film-forming nozzle having the slit is moved relative to the substrate, the aerosol containing the piezoelectric material particles and the carrier gas is sprayed from the slit to the substrate surface, so that the piezoelectric material particles are placed on the substrate. To deposit a thin film piezoelectric material layer on the substrate.
JP 2004-122341 A

  By the way, when forming a thin film layer on a substrate by the AD method, it is most common to spray aerosol while moving the film forming nozzle relative to the substrate in a predetermined direction. In this case, the film thickness of the thin film layer formed on the substrate is substantially constant with respect to the moving direction of the film forming nozzle. However, a large distribution of film thickness tends to occur in the direction (width direction) orthogonal to the moving direction of the film forming nozzle (see FIG. 10 of Patent Document 1). As a factor, first, since the flow velocity distribution of the aerosol sprayed from the slits is not uniform, there is a difference in the speed at which particles are deposited in the width direction of the formed belt-like thin film layer. Another factor is that the aerosol sprayed from the slit at a predetermined angle scrapes off a part of the film previously formed on the substrate, and as a result, the deposition of particles in the region is delayed. It has become.

  In a piezoelectric actuator for an ink jet head, if a film thickness distribution is generated in the piezoelectric material layer, the strength and rigidity of the electric field generated in the piezoelectric material layer vary depending on the location. As a result, the pressure applied to the ink varies, and accordingly, the droplet ejection characteristics (droplet velocity, droplet volume, etc.) of the plurality of ejection nozzles ejecting the droplets vary. As a result, the quality (printing quality) of an image or the like recorded on the recording medium is greatly reduced.

  An object of the present invention is to provide a piezoelectric actuator capable of suppressing deterioration in print quality due to the film thickness distribution as much as possible even when a film thickness distribution occurs in a thin film layer formed on a substrate by the AD method, and a piezoelectric actuator It is to provide an ink jet head and an ink jet printer which are used.

Means for Solving the Problems and Effects of the Invention

  According to the first aspect of the present invention, a plurality of pressure chambers each extending in a predetermined direction and arranged along a plane, and a plurality of ejections for ejecting ink respectively communicating with the plurality of pressure chambers. A plurality of thin films including a channel unit having a nozzle, a substrate disposed on one surface of the channel unit so as to cover the plurality of pressure chambers, and a piezoelectric material layer disposed on one surface of the substrate A method of manufacturing an inkjet head including a piezoelectric actuator having a layer, the method comprising: forming the plurality of thin film layers of the piezoelectric actuator on the substrate; and attaching a flow path unit to the substrate. In the step of forming the thin film layer, at least one thin film layer of the plurality of thin film layers is formed with a film forming nozzle having a slit formed in the slit width direction, and Manufacture of an ink jet head formed by ejecting an aerosol containing particles forming a thin film layer and a carrier gas from a slit of the film forming nozzle while moving relative to the substrate in a direction crossing the predetermined direction. A method is provided.

  When spraying aerosol, if the aerosol is sprayed while moving the deposition nozzle relative to the substrate in the slit width direction of the nozzle, the thin film layer deposited on the substrate is orthogonal to the relative movement direction of the nozzle. The film thickness distribution tends to occur in the direction, that is, in the width direction of the nozzle. However, in this manufacturing method, when the aerosol is ejected, the relative movement direction of the film forming nozzle intersects with a predetermined direction in which the pressure chamber extends (that is, the relative movement direction of the recording medium with respect to the inkjet head during recording). ing. Therefore, the arrangement direction of the plurality of dots formed on the recording medium by the plurality of ejection nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. Therefore, the influence of the film thickness distribution generated in the thin film layer on the variation in the size of a plurality of dots formed on the recording medium is reduced, and banding caused by the variation in the size of the dots is less noticeable. That is, deterioration in print quality due to banding is prevented.

  In the inkjet head manufacturing method of the present invention, the direction intersecting with the predetermined direction may be a direction orthogonal to the predetermined direction. In addition, the deposition nozzle may have a slit length such that an aerosol region sprayed from the slit to the substrate covers at least one pressure chamber.

  In the inkjet head manufacturing method of the present invention, the direction intersecting the predetermined direction may be a direction orthogonal to the relative movement direction of the recording medium with respect to the inkjet head during recording using the inkjet head. In this case, since the relative movement direction of the film forming nozzle is orthogonal to the relative movement direction of the manufactured inkjet head with respect to the recording medium, the film thickness distribution of the thin film layer has a plurality of dots formed on the recording medium. The influence on the variation in the size of the ink is further reduced, and the deterioration of the print quality due to the banding is surely prevented.

  In the method for manufacturing an inkjet head of the present invention, the plurality of ejection nozzles are arranged so as to form a plurality of dots arranged at equal intervals in one direction on the recording medium, respectively, The relative movement direction with respect to the substrate can be the arrangement direction of the plurality of dots. In this case, the direction in which the film thickness distribution is generated in the thin film layer is different from the arrangement direction of the dots formed on the recording medium by the plurality of jet nozzles, so that it is possible to prevent the print quality from being deteriorated due to banding.

  In the inkjet head manufacturing method of the present invention, the plurality of ejection nozzles may be arranged in at least one direction, and a relative movement direction of the film formation nozzle with respect to the substrate may be an arrangement direction of the plurality of ejection nozzles. In this case, since the direction of the film thickness distribution of the thin film layer is different from the direction in which dots are formed on the recording medium by the plurality of jet nozzles, deterioration in print quality due to banding is prevented.

  In the method for manufacturing an inkjet head according to the present invention, the plurality of ejection nozzles are arranged in a matrix along a first arrangement direction and a second arrangement direction that intersects the first arrangement direction. The relative movement direction with respect to the substrate may be an arrangement direction of the first arrangement direction and the second arrangement direction, which has a larger arrangement number of the ejection nozzles. When a plurality of ejection nozzles are arranged in two different directions, the arrangement direction with the larger number of ejection nozzles often corresponds to the arrangement direction of dots formed on the recording medium. . Accordingly, by making the relative movement direction of the film forming nozzle with respect to the substrate parallel to the arrangement direction with the larger number of arrangements, it is possible to prevent the print quality from being deteriorated due to banding.

  In the inkjet head manufacturing method of the present invention, in the aerosol injection, the film formation nozzle is relatively moved with respect to each of a plurality of regions of the substrate arranged in a relative movement direction of the recording medium with respect to the inkjet head. The aerosol can be sprayed. By doing so, since the aerosol is sprayed from the film forming nozzle to each of the plurality of regions, it becomes possible to form a thin film layer over a wide region of the substrate.

  In the inkjet head manufacturing method of the present invention, in the aerosol spraying step, an aerosol containing piezoelectric material particles and a carrier gas is sprayed from the slit of the film forming nozzle onto the substrate to form the piezoelectric material layer. obtain. When a film thickness distribution occurs in the piezoelectric material layer, the pressure applied to the ink in the pressure chamber varies depending on the difference in thickness, and the size of the dots formed on the recording medium by the ejection nozzle also changes. . However, according to this manufacturing method, the direction in which the film thickness distribution occurs in the piezoelectric material layer differs from the arrangement direction of the plurality of dots formed on the recording medium by the plurality of ejection nozzles. Is prevented as much as possible.

  In the ink jet head manufacturing method of the present invention, in the film forming step, the piezoelectric material layer may be formed on a surface of the substrate opposite to the flow path unit. According to this manufacturing method, since the piezoelectric material layer is located on the side opposite to the pressure chamber of the flow path unit, a piezoelectric actuator having a structure in which the piezoelectric material layer does not contact the ink can be obtained.

  In the ink jet head manufacturing method of the present invention, the ink jet head ejects ink from the plurality of ejecting nozzles to the recording medium conveyed in a direction orthogonal to the scanning direction while moving in a predetermined scanning direction. The relative movement direction of the film forming nozzle with respect to the substrate can be the conveyance direction of the recording medium. When the ink-jet head is a serial head, the arrangement direction of dots formed on the recording medium by the plurality of ejection nozzles when the head is scanned is the same (parallel) as the conveyance direction of the recording medium. According to this manufacturing method, since the relative movement direction of the film forming nozzle is the recording medium conveyance direction, the direction in which the film thickness distribution of the thin film layer is generated differs from the dot arrangement direction. Deterioration of print quality is surely prevented.

  In the inkjet head manufacturing method of the present invention, the inkjet head is a line-type inkjet head having a plurality of the ejection nozzles arranged at equal intervals in a direction orthogonal to a direction in which the recording medium is conveyed, The relative movement direction of the film formation nozzle with respect to the substrate may be the arrangement direction of the plurality of injection nozzles. When the inkjet head is a line-type head, the arrangement direction of dots formed on the recording medium by a plurality of ejection nozzles is often parallel to the arrangement direction of the ejection nozzles. And according to this manufacturing method, since the relative movement direction of the film formation nozzle is parallel to the arrangement direction of the injection nozzle, the direction in which the film thickness distribution of the thin film layer is generated and the dot arrangement direction are different. Deterioration of print quality due to banding is surely prevented.

  According to the second aspect of the present invention, a plurality of pressure chambers, a flow path unit having a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink onto a recording medium, and the plurality of the plurality of pressure chambers. An inkjet head comprising: a substrate disposed in the flow path unit so as to cover the pressure chamber; and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate; A method of manufacturing an ink jet printer having a moving device for moving the ink jet head in a direction of relative movement with respect to a recording medium, and forming the plurality of thin film layers of the piezoelectric actuator on the substrate; Producing an inkjet head by attaching a flow path unit to the substrate; and providing the moving device. In the step of forming the thin film layer, at least one thin film layer of the plurality of thin film layers is formed on the substrate in a direction crossing the slit width direction and the relative movement direction by using a film forming nozzle in which a slit is formed. There is provided an ink jet printer manufacturing method in which an aerosol containing particles forming a thin film layer and a carrier gas is ejected from a slit of the film forming nozzle while being relatively moved.

  According to this method for manufacturing an ink jet printer, the relative movement direction of the film forming nozzle in aerosol injection is not the same (parallel) as the relative movement direction of the ink jet head with respect to the recording medium, and these two directions intersect. The arrangement direction of dots formed on the recording medium by the plurality of ejection nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. For this reason, deterioration in print quality due to banding is prevented as much as possible.

  In the method of manufacturing an ink jet printer according to the present invention, the ink jet head may include a plurality of heads that respectively eject a plurality of types of inks having different colors. According to this manufacturing method, since the thin film layers of the piezoelectric actuators of a plurality of inkjet heads are all formed in the same process, the degree of variation in dot size among the plurality of heads becomes equal, and the dots are separated for each color. The size of will never change.

  According to the third aspect of the present invention, the substrate and the plurality of thin film layers including the piezoelectric material layer disposed on the substrate have a plurality of active portions extending in a predetermined direction on the piezoelectric material layer. A method of manufacturing a partitioned piezoelectric actuator, comprising: forming the piezoelectric material layer on the substrate; and forming a thin film layer other than the piezoelectric material layer on the substrate, The film-forming nozzle is formed by moving a film-forming nozzle having a slit formed in at least one of the thin-film layers relative to the substrate in the slit width direction and in a direction intersecting the predetermined direction. There is provided a method of manufacturing a piezoelectric actuator for injecting an aerosol containing particles forming the thin film layer and a carrier gas from the slit.

  According to this method of manufacturing a piezoelectric actuator, the relative movement direction of the film forming nozzle in aerosol injection intersects the direction in which the active portion extends (that is, the relative movement direction of the inkjet head including the piezoelectric actuator with respect to the recording medium). Therefore, the arrangement direction of dots formed on the recording medium by the plurality of jet nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. For this reason, when a piezoelectric actuator is used for an ink jet head, a decrease in print quality due to banding is prevented as much as possible.

  In the method for manufacturing a piezoelectric actuator of the present invention, the at least one thin film layer can be a piezoelectric material layer. Thereby, the inconvenience due to the difference in droplet ejection amount by the active part due to the thickness distribution of the active part can be solved. The thin film layer may include a metal plate and an insulating layer, and at least one layer may be an insulating layer. The active portion can be a portion of a piezoelectric material layer sandwiched between electrodes.

  According to a fourth aspect of the present invention, there is provided an inkjet head that ejects ink, each of which extends in a predetermined direction and is arranged along a plane, and a plurality of pressure chambers. A flow path unit having a plurality of ejection nozzles that respectively eject ink, a substrate disposed on one surface of the flow path unit so as to cover the plurality of pressure chambers, and disposed on one surface of the substrate A piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer formed, wherein at least one thin film layer of the plurality of thin film layers has a thickness uniformity in a direction intersecting the predetermined direction. An inkjet head having a higher thickness uniformity of the thin film layer in a direction perpendicular to the direction in which the ink is applied is provided.

  According to the inkjet head of the present invention, at least one thin film layer of the plurality of thin film layers has the predetermined direction (that is, a relative movement direction of the recording medium with respect to the inkjet head, for example, a scanning direction in the case of a serial inkjet head, In the case of a line type ink jet head, the uniformity of the thickness of the thin film layer in the direction intersecting the paper feed direction) is higher than the uniformity of the thickness of the thin film layer in the direction perpendicular to the intersecting direction. Is prevented.

  In the ink jet head according to the aspect of the invention, the at least one thin film layer moves the film forming nozzle in which the slit is formed relative to the substrate in the direction of the slit width and in a direction intersecting the predetermined direction. The film may be formed by spraying an aerosol containing particles forming the thin film layer and a carrier gas from the slit of the film forming nozzle. When the thin film layer is manufactured in this way, the arrangement direction of the dots formed on the recording medium by the plurality of jet nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. For this reason, deterioration in print quality due to banding is prevented.

  According to the fifth aspect of the present invention, a plurality of pressure chambers, a flow path unit having a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink onto the recording medium, and the plurality of the plurality of pressure chambers. An inkjet head comprising: a substrate disposed in the flow path unit so as to cover the pressure chamber; and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate; A moving device for moving the ink-jet head in the direction of relative movement with respect to the recording medium, wherein at least one thin film layer of the plurality of thin film layers has a thickness of the thin film layer in a direction intersecting the relative movement direction An ink jet printer is provided in which the uniformity of the thin film layer is higher than the uniformity of the thickness of the thin film layer in the direction orthogonal to the intersecting direction.

  According to the ink jet printer of the present invention, at least one thin film layer of the plurality of thin film layers has the relative movement direction, for example, a scanning direction in the case of a serial type ink jet head, and a paper feed in the case of a line type ink jet head. The uniformity of the thickness of the thin film layer in the direction intersecting the direction is higher than the uniformity of the thickness of the thin film layer in the direction orthogonal to the intersecting direction. For this reason, deterioration in print quality due to banding is prevented.

  In the ink jet printer according to the aspect of the invention, the at least one thin film layer may move the film forming nozzle in which the slit is formed relative to the substrate in the slit width direction and in a direction intersecting the relative movement direction. The film may be formed by spraying an aerosol containing particles forming the thin film layer and a carrier gas from the slit of the film forming nozzle. As a result, the direction in which dots are formed on the recording medium by the plurality of ejection nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. For this reason, deterioration in print quality due to banding is prevented.

  According to the sixth aspect of the present invention, there is provided a piezoelectric actuator used for discharging a liquid, comprising a substrate and a plurality of thin film layers including a piezoelectric layer disposed on the substrate, and a piezoelectric material A plurality of active portions extending in a predetermined direction are defined in the layer, and at least one thin film layer of the plurality of thin film layers intersects the thickness uniformity of the thin film layer in a direction intersecting the predetermined direction. A piezoelectric actuator having higher thickness uniformity of the thin film layer in a direction orthogonal to the direction is provided.

  According to the piezoelectric actuator of the present invention, at least one thin film layer of the plurality of thin film layers has a direction in which the active portion extends, for example, a scanning direction and a line when the piezoelectric actuator is used in a serial type ink jet head. When used in the case of a type inkjet head, the uniformity of the thickness of the thin film layer in the direction intersecting the paper feed direction is higher than the uniformity of the thickness of the thin film layer in the direction orthogonal to the intersecting direction. For this reason, deterioration in print quality due to banding is prevented.

  In the piezoelectric actuator according to the aspect of the invention, the at least one thin film layer may have a film forming nozzle having a slit formed in the width direction of the slit and in a direction intersecting the predetermined direction, particularly in a direction orthogonal to the substrate. Then, it is formed by injecting an aerosol containing particles forming the thin film layer and a carrier gas from the slit of the film forming nozzle while relatively moving. By forming the thin film layer in this way, the arrangement direction of dots formed on the recording medium by the plurality of jet nozzles is different from the direction in which the film thickness distribution is generated in the thin film layer. For this reason, deterioration in print quality due to banding is prevented as much as possible.

  Next, an embodiment of the present invention will be described. The present embodiment is an example in which the present invention is applied to a serial type ink jet head that records an image or the like by ejecting ink onto a recording sheet while moving in one direction.

  First, the configuration of an ink jet printer provided with a serial ink jet head will be briefly described. As shown in FIG. 1, an inkjet printer 100 includes a carriage 4 (moving device) that can move in the left-right direction in FIG. 1, and a serial type inkjet that is provided on the carriage 4 and ejects ink onto a recording sheet 7. A head 1 and a conveying roller 5 for feeding the recording paper 7 forward in FIG. 1 are provided. In FIG. 1, only one inkjet head 1 is shown, but actually, there are four inkjet heads 1 that eject ink of four colors (cyan, magenta, yellow, and black) onto the carriage 4, respectively. Is provided. That is, the ink jet printer 100 is a color ink jet printer capable of recording a color image on the recording paper 7.

  In the ink jet printer 100, the four ink jet heads 1 move in the left-right direction (scanning direction) integrally with the carriage 4, and recording is performed from the ejection nozzles 20 (see FIGS. 2 to 5) formed on the lower surface thereof. By alternately performing the operation of ejecting four colors of ink onto the paper 7 and the paper transporting operation in which the transport roller 5 feeds the recording paper 7 forward by a predetermined amount, desired characters and colors are applied to the recording paper 7. An image or the like can be recorded.

  Next, the inkjet head 1 will be described with reference to FIGS. The inkjet head 1 is disposed on the upper surface of the flow path unit 2 in which an ink flow path including the ejection nozzle 20 and the pressure chamber 14 is formed, and applies ejection pressure to the ink in the pressure chamber 14. The piezoelectric actuator 3 is provided.

  First, the flow path unit 2 will be described. As shown in FIGS. 4 and 5, the flow path unit 2 includes a cavity plate 10, a base plate 11, a manifold plate 12, and a nozzle plate 13, and these four plates 10 to 13 are joined in a stacked state. Yes. Among these, the cavity plate 10, the base plate 11 and the manifold plate 12 are stainless steel plates, and ink flow paths such as a manifold 17 and a pressure chamber 14 described later can be easily etched in these three plates 10-12. It can be formed. The nozzle plate 13 is formed of, for example, a polymer synthetic resin material such as polyimide, and is bonded to the lower surface of the manifold plate 12. Or this nozzle plate 13 may be formed with metal materials, such as stainless steel, similarly to the three plates 10-12.

  As shown in FIGS. 2 to 5, among the four plates 10 to 13, the uppermost cavity plate 10 extends along the scanning direction (predetermined direction) and along the plane. A plurality of arranged pressure chambers 14 are formed by holes penetrating the plate 10, and the plurality of pressure chambers 14 are respectively covered by a vibration plate 30 and a base plate 11 described later from above and below. The plurality of pressure chambers 14 are arranged in four rows in the paper feeding direction (vertical direction in FIG. 2). Furthermore, each pressure chamber 14 is formed in a substantially elliptical shape that is long in the scanning direction (left-right direction in FIG. 2) in plan view.

  As shown in FIG. 3, communication holes 15 and 16 are formed at positions where the base plate 11 overlaps both ends of the pressure chamber 14 in a plan view. Further, the manifold plate 12 has four manifolds 17 extending in the paper feeding direction (vertical direction in FIG. 2) so as to overlap with the communication hole 15 side portions of the pressure chambers 14 arranged in the paper feeding direction in plan view. Is formed. These four manifolds 17 communicate with an ink supply port 18 formed in a vibration plate 30 described later, and ink is supplied to the manifold 17 from an ink tank (not shown) via the ink supply port 18. Furthermore, a plurality of communication holes 19 that are continuous with the plurality of communication holes 16 are also formed at positions where the manifold plate 12 overlaps the ends of the plurality of pressure chambers 14 opposite to the manifold 17 in plan view.

  Further, a plurality of injection nozzles 20 are formed at positions where the nozzle plate 13 overlaps the plurality of communication holes 19 in plan view. As shown in FIG. 2, the plurality of injection nozzles 20 overlap with the end portions of the plurality of pressure chambers 14 arranged in four rows on the side opposite to the manifold 17, and in areas not overlapping with the four manifolds 17. Four nozzle rows 21a, 21b, 21c, and 21d are arranged in the paper feed direction (up and down direction in FIG. 2) at regular intervals and aligned in the scanning direction. These four nozzle rows 21a to 21d are each composed of the same number of jet nozzles 20, and the intervals (pitch P) of the jet nozzles 20 in the arrangement direction are all equal. Further, the four nozzle rows 21a to 21d are sequentially shifted to the downstream side in the paper feed direction (downward in FIG. 2) by P / 4. Accordingly, it is possible to form a plurality of dots arranged on the recording paper 7 at intervals of P / 4 in the paper feeding direction by the four nozzle rows 21a to 21d.

  As shown in FIG. 2, the plurality of injection nozzles 20 and the plurality of pressure chambers 14 corresponding to the plurality of injection nozzles 20 are arranged in the paper feed direction (first arrangement direction) as a result. At the same time, they are also arranged in a direction (second arrangement direction) intersecting with the paper feed direction at an angle θ, and arranged in a matrix along these two directions. However, the number of arrangements (10) of the injection nozzles 20 and the pressure chambers 14 in the first arrangement direction is larger than the number of arrangements (4) in the second arrangement direction, and the arrangement interval is small (arrangement density). Is high). That is, the first arrangement direction corresponds to the direction in which fine dot rows are formed on the recording paper 7.

  As shown in FIG. 4, the manifold 17 communicates with the pressure chamber 14 through the communication hole 15, and the pressure chamber 14 communicates with the injection nozzle 20 through the communication holes 16 and 19. As described above, a plurality of individual ink flow paths 25 extending from the manifold 17 to the ejection nozzle 20 through the pressure chamber 14 are formed in the flow path unit 2.

  Next, the piezoelectric actuator 3 will be described. As shown in FIGS. 2 to 5, the piezoelectric actuator 3 includes a metal diaphragm 30 (substrate) disposed on the upper surface of the flow path unit 2 and a plurality of pressure chambers 14 on the upper surface of the diaphragm 30. The piezoelectric material layer 31 (piezoelectric material layer) continuously formed and a plurality of individual electrodes 32 formed on the upper surface of the piezoelectric material layer 31 respectively corresponding to the plurality of pressure chambers 14. The piezoelectric material layer 31 and the individual electrode 32 are both thin film layers (thin film layers) having a thickness of about several μm to several tens of μm.

  The diaphragm 30 is a conductive plate made of a substantially rectangular metal material in plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. . The diaphragm 30 is disposed on the upper surface of the cavity plate 10 so as to cover the plurality of pressure chambers 14, and is joined to the cavity plate 10. The diaphragm 30 is always held at the ground potential, and is a common electrode that acts on the piezoelectric material layer 31 between the individual electrode 32 and the diaphragm 30 so as to face the plurality of individual electrodes 32 and in the thickness direction. Doubles as

  On the upper surface of the vibration plate 30, a piezoelectric material layer 31 mainly composed of lead zirconate titanate (PZT), which is a solid solution and is a ferroelectric substance, is formed of lead titanate and lead zirconate. The piezoelectric material layer 31 is continuously formed across the plurality of pressure chambers 14. The piezoelectric material layer 31 does not come into contact with the ink in the pressure chamber 14 because it is disposed on the upper surface of the vibration plate 30 (the surface on the side opposite to the flow path unit 2 (pressure chamber 14)). The piezoelectric material layer 31 is formed by an AD method in which an aerosol composed of very fine particles and a carrier gas is sprayed onto the substrate to deposit the particles. This will be described in detail later.

  On the upper surface of the piezoelectric material layer 31, a plurality of individual electrodes 32 having a substantially elliptical planar shape that is slightly smaller than the pressure chamber 14 are formed. These individual electrodes 32 are each formed at a position overlapping the central portion of the corresponding pressure chamber 14 in plan view. The individual electrode 32 is made of a conductive material such as gold, copper, silver, palladium, platinum, or titanium. Further, a plurality of contact portions 35 are drawn out from the left end portions of the plurality of individual electrodes 32 in FIG. The plurality of contact portions 35 are joined to contacts of a flexible wiring member (not shown) such as a flexible printed circuit (FPC), and the plurality of contact portions 35 are connected to the wiring portions 35. It is electrically connected to a driver IC (not shown) that selectively supplies a driving voltage to the plurality of individual electrodes 32 via a member. A region 31a of the piezoelectric material layer 31 that overlaps the individual electrode 32 becomes a region that is deformed by a driving voltage as will be described later, and this region 31 is referred to as an “active portion”). 3 shows the dimensions of the pressure chamber 14 (length 0.6 mm, width 0.25 mm) of the ink jet head used in this example, and the dimensions (length 0.5 mm, width) of the active portion 14a and the individual electrodes 32. An example of 0.16 mm) was shown.

  Next, the operation of the piezoelectric actuator 3 during ink ejection will be described. When a driving voltage is selectively applied to the plurality of individual electrodes 32 from the driver IC, the individual electrodes 32 above the piezoelectric material layer 31 to which the driving voltage is applied and the piezoelectric material layer 31 held at the ground potential are below. The potential of the diaphragm 30 as the common electrode on the side becomes different, and an electric field in the thickness direction is generated in the piezoelectric material layer 31, particularly the active portion 31 a, sandwiched between the individual electrode 32 and the diaphragm 30. Here, when the polarization direction of the piezoelectric material layer 31 is the same as the direction of the electric field, the piezoelectric material layer 31, particularly the active portion 31a, extends in the thickness direction, which is the polarization direction, and contracts in the horizontal direction. As the piezoelectric material layer 31 contracts and deforms, the diaphragm 30 is deformed so as to protrude toward the pressure chamber 14, so that the volume in the pressure chamber 14 is reduced and pressure is applied to the ink in the pressure chamber 14. The ink droplets are ejected from the ejection nozzle 20 that is applied and communicates with the pressure chamber 14.

  Next, a method for manufacturing the inkjet printer 100 will be described focusing on the manufacturing process of the inkjet head 1. FIG. 6 schematically shows the manufacturing process of the inkjet head 1. First, as shown in FIG. 6A, the four plates 10 to 13 constituting the flow path unit 2 and the vibration plate 30 of the piezoelectric actuator 3 are bonded by bonding, metal diffusion bonding, or the like (flow path unit). Installation step).

  Next, the piezoelectric actuator 3 is manufactured by the following steps. As shown in FIG. 6B, the piezoelectric material layer 31 is formed on the upper surface of the vibration plate 30 (the surface opposite to the joint surface with the flow path unit 2) by the AD method. That is, an aerosol containing ultrafine particles of piezoelectric material and a carrier gas is jetted toward the diaphragm 30 to collide at high speed, and particles are densely deposited on the upper surface of the diaphragm 30 to form a thin film piezoelectric material layer 31. Is formed (thin film formation step). Thereafter, as shown in FIG. 6C, a plurality of individual electrodes 32 and a plurality of contact portions 35 are formed on the upper surface of the piezoelectric material layer 31 by screen printing, sputtering, vapor deposition, or the like.

  In this way, four inkjet heads 1 for ejecting four colors of ink, respectively, are prepared, and a carriage 4 (moving device) is prepared, and these four inkjet heads 1 are respectively attached to the carriage 4 (see FIG. 1). Assemble. Then, various components such as the carriage 4 and the conveyance roller 5 are assembled in a printer frame (not shown), and the inkjet printer 100 is assembled.

  Furthermore, the film forming process of the piezoelectric material layer 31 by the AD method will be described in more detail among the manufacturing processes of the inkjet head 1 described above. FIG. 7 is a schematic configuration diagram of a film forming apparatus 50 for the piezoelectric material layer 31. The film forming apparatus 50 is connected to an aerosol generator 60 via an aerosol supply pipe 64 and a film forming nozzle 52 disposed in the film forming chamber 51 and a film forming chamber 51. A stage 53 for moving the diaphragm 30 in a predetermined direction is provided.

  The aerosol generator 60 generates an aerosol Z that is a mixture of an ultrafine particle (for example, a particle size of 1 μm or less) piezoelectric material and a carrier gas. The aerosol generator 60 includes an aerosol chamber 61 that can accommodate material particles M therein, and a vibration device 62 that is attached to the aerosol chamber 61 and vibrates the aerosol chamber 61. A gas cylinder G for introducing a carrier gas is connected to the aerosol chamber 61 via an introduction pipe 63. As the carrier gas, dry air, nitrogen gas, argon gas, oxygen gas, helium gas or the like is used. A film forming nozzle 52 and a stage 53 are installed in the film forming chamber 51, and the film forming chamber 51 is connected to a vacuum pump P through an exhaust pipe 54. A rectangular slit 55 (see FIG. 8) that is long in one direction and that opens toward the vibration plate 30 on the stage 53 is provided at the tip of the film forming nozzle 52. The stage 53 moves the diaphragm 30 in the slit width direction of the film forming nozzle 52 (horizontal direction in FIG. 7).

  Then, the film forming apparatus 50 reduces the pressure in the film forming chamber 51 with a vacuum pump and sprays the aerosol generated by the aerosol generator from the slit 55 of the film forming nozzle 52 toward the upper surface of the diaphragm 30. At the same time, the diaphragm 30 on the stage 53 is moved with respect to the film forming nozzle 52 (aerosol injection process), and the piezoelectric material layer 31 is formed in a predetermined region of the diaphragm 30.

  Further, the relative movement of the vibration plate 30 and the film forming nozzle 52 when the piezoelectric material layer 31 is formed will be described in detail. 8A and 8B show the positional relationship between the diaphragm 30 and the film forming nozzle 52 during film formation. As described above, the vibration plate 30 actually moves with respect to the film formation nozzle 52 together with the stage 53. However, in the following description, the film formation nozzle 52 moves with respect to the vibration plate 30 for convenience. It shall be.

  As shown in FIG. 8A, the film forming nozzle 52 injects aerosol onto the diaphragm 30 while moving in the width direction of the slit 55 with respect to the area on the upper surface of the diaphragm 30, and this area. Then, the piezoelectric material layer 31 is formed. Further, when it is necessary to form the piezoelectric material layer 31 in another region other than this region, as shown in FIG. The aerosol is sprayed while moving in the width direction of the slit 55 to form the piezoelectric material layer 31 in another region. The injection may be stopped before reaching the film forming nozzle 52 above the other region, and the injection may be resumed when the injection start position in another region is reached. 8C shows a region (hereinafter referred to as “injection region”) 30a on the substrate that is covered with the aerosol ejected from the film forming nozzle 52 in a stopped state. The ejection region 30a is rectangular, has a width of about 0.4 mm, and has a length that completely accommodates the two active portions 31a aligned in the scanning direction of the piezoelectric material layer 31. The ejection region 30a is The film forming nozzle 52 may be used so as to cover one active part 31a or three or more active parts 31a, and thus each of a plurality of regions on the upper surface of the diaphragm 30. On the other hand, it is possible to form the piezoelectric material layer 31 over a wide area of the upper surface of the vibration plate 30 by ejecting aerosol while relatively moving the film forming nozzle 52.

  Further, the piezoelectric material layer 31 may be formed by moving the film forming nozzle 52 once with respect to one area of the vibration plate 30, or a plurality of film forming nozzles 52 may be formed with respect to one area. The piezoelectric material layer 31 may be formed by rotating and rotating the piezoelectric material particles so as to be stacked in layers.

  By the way, as shown in FIG. 8, when the film-forming nozzle 52 for injecting aerosol is moved in the width direction of the slit 55 with respect to the diaphragm 30, the band-shaped piezoelectric material layer 31 is formed. The film thickness of 31 is substantially uniform in the longitudinal direction, that is, the moving direction of the film forming nozzle 52 (the front-rear direction in FIG. 8A). However, with respect to the width direction of the band-shaped piezoelectric material layer 31 (the direction orthogonal to the moving direction of the film forming nozzle 52: the left-right direction in FIG. 8A), the flow velocity distribution of the aerosol ejected from the slit 55 is not uniform. For this reason, the piezoelectric material layer 31 tends to have a film thickness distribution. If the film thickness distribution exists in the piezoelectric material layer 31 as described above, the strength and rigidity of the electric field generated in the piezoelectric material layer 31 vary depending on the location, so that the deformation amount of the piezoelectric material layer 31 and the diaphragm 30 varies. That is, variations in droplet ejection characteristics such as the velocity and volume of droplets ejected from the ejection nozzle 20 occur.

  Here, the influence of the film thickness distribution of the piezoelectric material layer 31 on the print quality varies greatly depending on the relative movement direction of the film forming nozzle 52 with respect to the vibration plate 30. For example, the moving direction of the film forming nozzle 52 when forming the piezoelectric material layer 31 is a direction orthogonal to the arrangement direction of the injection nozzles 20 (pressure chambers 14) as indicated by broken arrows in FIG. That is, it is assumed that the direction is parallel to the scanning direction of the inkjet head 1. In FIG. 9A, illustration of the individual electrode 32 disposed on the upper surface of the piezoelectric material layer 31 is omitted. In this case, as shown in FIG. 9C, the film thickness of the piezoelectric material layer 31 is substantially uniform with respect to the scanning direction of the inkjet head 1 parallel to the moving direction of the film forming nozzle 52. On the other hand, as shown in FIG. 9B, with respect to the arrangement direction of the injection nozzles 20 (pressure chambers 14) perpendicular to the moving direction of the film forming nozzles 52, there is a film thickness distribution (t1 to t1) in the piezoelectric material layer 31. t6) occurs.

  At this time, assuming that the drive voltages applied to the individual electrodes 32 are the same, a larger electric field acts on the thin portion of the piezoelectric material layer 31 than on the thick portion. In addition, the rigidity of the portion where the film thickness is thin is smaller than that of the portion where the film thickness is thick. For this reason, a portion with a small film thickness has a larger deformation amount than a portion with a large film thickness, and a large pressure is applied to the ink in the pressure chamber 14 corresponding to this portion. Therefore, relatively large droplets are ejected from the ejection nozzle 20 corresponding to the thin portion of the piezoelectric material layer 31.

  For example, the thickness of the diaphragm 30 is t0 = 15 μm, and the film thickness distribution shown in FIG. 9B of the piezoelectric material layer 31 formed on the upper surface of the diaphragm 30 is t1 = 11 μm, t2 = 13 μm. T3 = 14 μm, t4 = 12 μm, t5 = 9 μm, and t6 = 10 μm. In this case, the pressure applied to the ink in the pressure chamber 14 and the volume of the ejected ink droplet were determined by numerical analysis. The analysis results are shown in Table 1.

表１におけるノズルＡ〜ノズルＰは、図１０において、紙送り方向に関して間隔Ｐ／４を空けて順に配置されている１６個の噴射ノズル２０を示す。従って、これら１６個の噴射ノズル２０により、記録用紙７上に、紙送り方向に間隔Ｐ／４で並ぶ１６個のドットが形成される。なお、ｔ１は、ノズルＡの紙送り方向上流側の圧力室端の位置であり、ｔ１からｔ６は、それぞれ０．２５μｍの間隔で隔てられた位置を示している。表１に示すように、１６個のノズルＡ〜ノズルＰからそれぞれ噴射される液滴の体積は、圧電材料層３１の膜厚分布に応じて変化しており、膜厚が比較的大きい部分と対応するノズルＡ〜ノズルＨよりも、膜厚が比較的小さい部分と対応するノズルＩ〜ノズルＰの方が、噴射される液滴体積が大きくなっている。

In FIG. 10, nozzle A to nozzle P in Table 1 indicate 16 injection nozzles 20 arranged in order at intervals P / 4 in the paper feed direction. Accordingly, 16 dots are formed on the recording paper 7 by the 16 ejection nozzles 20 so as to be arranged at intervals P / 4 in the paper feeding direction. Note that t1 is the position of the pressure chamber end upstream of the paper feed direction of the nozzle A, and t1 to t6 indicate positions separated by an interval of 0.25 μm, respectively. As shown in Table 1, the volume of the liquid droplets ejected from each of the 16 nozzles A to P changes according to the film thickness distribution of the piezoelectric material layer 31, and the portion with a relatively large film thickness Compared with the corresponding nozzle A to nozzle H, the nozzle I to nozzle P corresponding to the portion having a relatively small film thickness has a larger droplet volume to be ejected.

  Further, the film thickness of the piezoelectric material layer 31 continuously changes in the paper feed direction. Corresponding to this continuous film thickness distribution, as shown in FIG. The size of the dots formed on it also changes continuously. Further, relatively small dot groups formed by the nozzle group consisting of nozzle A to nozzle H and relatively large dot groups formed by the nozzle group consisting of nozzle I to nozzle P are alternately arranged in the paper feed direction. become. Accordingly, the size of the dots formed on the recording paper 7 continuously changes over a long span (distance between the nozzle A and the nozzle P) in the paper feeding direction. Such a change in the size of the dots results in shading unevenness (banding) that can be clearly seen by the eyes when a large number of dot rows are arranged in the scanning direction, and the print quality is greatly reduced.

  Therefore, in the present embodiment, the movement direction of the film forming nozzle 52 when forming the piezoelectric material layer 31 is the arrangement of the injection nozzles 20 (pressure chambers 14) as shown by the broken arrows in FIG. The direction parallel to the direction is orthogonal to the scanning direction of the inkjet head 1 (the relative movement direction of the recording paper 7 with respect to the inkjet head 1 during recording (carriage scanning)). More specifically, the region A1 corresponding to the two pressure chamber rows on the one side in the scanning direction (left side in FIG. 11 (a)) of the diaphragm 30 and the other side in the scanning direction (right side in FIG. 11 (a)). The film forming nozzle 52 is moved in the arrangement direction of the pressure chambers 14 for each of the two areas in the scanning direction of the area A2 corresponding to the two pressure chamber arrays, and the two areas A1 and A2 are moved. A piezoelectric material layer 31 is formed respectively. The boundary of the piezoelectric material layer 31 formed in each of the two regions A1 and A2 is located between the second and third pressure chamber columns from the left in FIG. Does not overlap the pressure chamber 14.

  In this case, as shown in FIG. 11B, the film thickness of the piezoelectric material layer 31 is substantially uniform with respect to the paper feed direction which is parallel to the moving direction of the film forming nozzle 52. Accordingly, ink droplets of substantially the same size are ejected from the ejection nozzles 20 constituting the nozzle rows 21a to 21d.

  On the other hand, as shown in FIG. 11C, the film thickness distribution (t1 to t6) is present in the piezoelectric material layer 31 with respect to the scanning direction of the inkjet head 1, which is a direction orthogonal to the moving direction of the film forming nozzle 52. Arise. This film thickness distribution is substantially the same as the film thickness distribution of FIG. Here, when the piezoelectric material layer 31 is formed in each of the two regions A1 and A2 of the vibration plate 30, the moving speed of the film forming nozzle 52 (that is, the moving speed of the stage 53) and the injection of aerosol from the slit 55 If the film forming conditions such as the amount are the same, the film thickness distributions in these two regions A1 and A2 are almost equal.

  For this reason, the thickness of the piezoelectric material layer 31 in the region corresponding to the first pressure chamber row 21a from the left in FIG. 11A is different from the thickness of the region corresponding to the second pressure chamber row 21b. It becomes substantially equal to the thickness of the region corresponding to the third pressure chamber row 21c. Similarly, the thickness of the piezoelectric material layer 31 in the region corresponding to the second pressure chamber row 21b from the left is substantially equal to the thickness of the region corresponding to the fourth pressure chamber 21d. Accordingly, as shown in FIG. 12, the size of the dots formed by the first nozzle row 21a and the third nozzle row 21c is substantially equal, while the second nozzle row 21b and the fourth nozzle row 21c are substantially equal. The size of the dots formed by the nozzle row 21d is substantially equal. Further, as described above, the ejection nozzles 20 belonging to the four nozzle rows 21a to 21d are sequentially arranged with an interval of P / 4 with respect to the paper feed direction, so that these four rows of nozzle rows 21a. ˜21d, two types of dots Da and Db are alternately formed on the recording paper 7 in the paper feeding direction.

  The plurality of dots arranged in the paper feed direction as shown in FIG. 12 are alternately changed in size at very short intervals P / 4. That is, as compared with FIG. 10, the dot size changes in a very short span, and such a change in the dot size is not easily recognized by the eyes. Accordingly, uneven density (banding) in a recorded image or the like caused by a change in the size of the dots becomes inconspicuous, so that even if there is a film thickness distribution of the piezoelectric material layer 31, the print quality is deteriorated due to it. Is prevented.

  As described above, in the present embodiment, when the piezoelectric material layer 31 is formed, the relative movement direction of the film formation nozzle 52 with respect to the vibration plate 30 is the scanning direction (with respect to the inkjet head 1 of the recording paper 7 during recording). Perpendicular to the relative movement direction) and parallel to the arrangement direction of the injection nozzles 20 (the direction of the nozzle rows 21a to 21d). For this reason, the influence of the film thickness distribution generated in the piezoelectric material layer 31 on the variation in the size of dots formed in the paper feed direction on the recording paper 7 is reduced, and is caused by the variation in the size of the dots. Banding is less noticeable. That is, it is possible to prevent a decrease in print quality due to banding.

  The ink jet printer 100 according to the present embodiment is a color ink jet printer including four ink jet heads 1 that respectively eject four color inks. The piezoelectric material layers 31 of these four ink jet heads 1 are all formed by the same process. For this reason, the degree of variation in the size of the dots formed on the recording paper 7 is equal between the four inkjet heads 1 and the size of the dots does not change for each color.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

<Modification 1>
In the film forming process of the piezoelectric material layer 31 according to the embodiment, the boundary between the piezoelectric material layers 31 formed in the two regions A1 and A2 of the diaphragm 30 does not overlap with the pressure chamber 14, as shown in FIG. It was. That is, the regions A1 and A2 completely accommodate each active portion 31a partitioned on the piezoelectric material layer 31, and the boundary of the piezoelectric material layer 31 does not cross the active portion 31a (see FIG. 8C). ). However, the boundaries of the piezoelectric material layers 31 that are separately formed in the plurality of regions of the diaphragm 30 may overlap the pressure chamber 14.

  For example, as shown in FIG. 13A, as indicated by broken-line arrows with respect to three regions B1, B2, and B3 arranged in the scanning direction (left and right direction in FIG. 13A) on the upper surface of the diaphragm 30. In addition, the film forming nozzle 52 moves relative to the vibration plate 30 in the paper feeding direction (vertical direction in FIG. 13A), thereby forming the piezoelectric material layer 31 in each of the three regions B1, B2, and B3. . Here, the central region B2 partially overlaps with the central two pressure chamber rows of the four pressure chamber rows. That is, the boundary between the left region B1 and the central region B2 and the boundary between the central region B2 and the right region B3 overlap with the pressure chamber 14 (and the active portion). Also in the inkjet head 1A manufactured in this way, the influence of the film thickness distribution generated in the piezoelectric material layer 31 on the variation in the size of dots formed in the paper feed direction on the recording paper 7 is reduced. Disappears.

  More specifically, as shown in FIG. 13B, the film thickness of the piezoelectric material layer 31 in the paper feed direction is substantially uniform. On the other hand, a predetermined film thickness distribution occurs in each of the piezoelectric material layers 31 formed in the three regions B1, B2, and B3 in the scanning direction. In the first modification, since the boundaries of the regions B1, B2, and B3 overlap with the pressure chambers 14, the thicknesses of the piezoelectric material layers 31 corresponding to the four pressure chamber rows are different from each other. The ink droplet volumes ejected from the nozzle rows 21a to 21d are also different. Therefore, four types of sizes of dots are arranged in order in the paper feeding direction on the recording paper 7, and a variation in the size of the dots occurs to some extent. However, as compared with the case where the film forming nozzle 52 is moved in the scanning direction of the inkjet head 1 to form the piezoelectric material layer 31 (see FIG. 10), the span in which the dot size changes is sufficiently short. Banding due to dot size variation is less noticeable.

<Modification 2>
The arrangement of the injection nozzles 20 is not limited to the aspect described in the above embodiment. For example, as shown in FIG. 14, four nozzle rows 21a to 21d are arranged in the first nozzle row 21a, 3 from the left. In the order of the nozzle row 21c of the second row, the nozzle row 21b of the second row, and the nozzle row 21d of the fourth row in the order of the interval P / 4 to the downstream side (lower side in FIG. 14) in the paper feed direction (P is each nozzle row 21a) (Arrangement interval of the injection nozzles 20 to 21d) may be shifted. When manufacturing the inkjet head 1B having such a configuration, the piezoelectric material layer 31 is formed by relatively moving the film forming nozzle 52 in the paper feeding direction (the arrangement direction of the ejection nozzles 20). Then, the film thickness distribution of the piezoelectric material layer 31 is generated in the scanning direction, which is orthogonal to the arrangement direction of dots formed on the recording paper 7 with the interval P / 4. Therefore, the influence of this film thickness distribution on the variation in dot size is reduced, and banding due to the change in the dot size becomes inconspicuous.

<Modification 3>
In this example, as shown in FIG. 15A, there is one row of the injection nozzles 20 arranged in the paper feed direction and the row of the pressure chambers 14 corresponding thereto. When the inkjet head 1C having such a configuration is manufactured, as shown by a broken line arrow in FIG. 15A, the film formation nozzle 52 is moved in the paper feeding direction (the ejection nozzle 20 (the pressure chamber 14) with respect to the vibration plate 30. The piezoelectric material layer 31 is formed by relative movement in the arrangement direction). Then, as shown in FIG. 15B, since the film thickness of the piezoelectric material layer 31 in the arrangement direction of the injection nozzles 20 arranged in a row becomes substantially uniform, the volume of the droplets ejected from these injection nozzles 20 Does not vary. That is, since the size of the dots formed by one row of the injection nozzles 20 is substantially equal, banding itself does not occur. As shown in FIG. 15C, the piezoelectric material layer 31 has a film thickness distribution in the scanning direction. When the number of the injection nozzles 20 is one, this film thickness distribution is determined by the injection nozzles. It does not affect the variation of the 20 droplet volumes (dot size).

  A comparative example of Modification 3 will be described with reference to FIG. An inkjet head 201 shown in FIG. 21A is a serial type inkjet head that ejects ink onto a recording sheet (not shown) while moving in the left-right direction (scanning direction) in FIG. Note that the recording paper is conveyed in the vertical direction (paper feeding direction) in FIG. 21 orthogonal to the scanning direction. Further, in this inkjet head 201, as in the case of FIG. 15, a plurality of ejection nozzles 220 and a plurality of pressure chambers 214 communicating with the plurality of ejection nozzles 220 are each arranged in a line in the paper feed direction. Yes. A diaphragm 230 (substrate) is disposed so as to cover the plurality of pressure chambers 214, and a piezoelectric material layer 231 is disposed on the upper surface of the diaphragm 230. Further, a plurality of electrodes 232 for generating an electric field in the piezoelectric material layer 231 are provided in regions corresponding to the plurality of pressure chambers 214 on the upper surface of the piezoelectric material layer 231.

  In the inkjet head 201 shown in FIG. 21, the relative movement direction (broken arrow) of the film formation nozzle is parallel to the scanning direction when forming the piezoelectric material layer 231 disposed across the plurality of pressure chambers 214. In some cases, as shown in FIG. 21B, the piezoelectric material layer 231 has a film thickness distribution in a direction parallel to the arrangement direction of the injection nozzles 220 (pressure chambers 214). The pressure applied to the ink in each of the pressure chambers 214 varies greatly. That is, the film thickness distribution of the piezoelectric material layer 231 appears as it is as a variation in the size of a plurality of dots arranged in the paper feed direction (vertical direction in FIG. 21), and many such dot rows are arranged in the scanning direction. In this case, shading unevenness (banding) that can be seen at a glance occurs.

<Modification 4>
In this example, as shown in FIG. 16, the rows of injection nozzles 20 (pressure chambers 14) are disposed at a predetermined angle with respect to the scanning direction (intersect). In such an ink jet head 1D, dots arranged at equal intervals in the paper feed direction are formed by a plurality of ejection nozzles arranged in a direction inclined with respect to the scanning direction. When the inkjet head 1D is manufactured, the piezoelectric material layer 31 is formed by moving the film forming nozzle 52 relative to the vibration plate 30 in the paper feeding direction, as indicated by a broken line arrow in FIG. Then, since the film thickness distribution of the piezoelectric material layer 31 is generated in the scanning direction orthogonal to the arrangement direction of the dots formed on the recording paper 7, the influence of the film thickness distribution on the variation in dot size is reduced.

<Modification 5>
In this example, as shown in FIG. 17, when the inkjet head 1 </ b> E having a structure in which the rows of the ejection nozzles 20 (pressure chambers 14) are inclined at a predetermined angle with respect to the scanning direction, the film formation nozzle 52 is vibrated. The plate 30 is moved relative to the direction in which the ejection nozzles 20 (pressure chambers 14) are arranged (that is, the direction that intersects the scanning direction, which is the relative movement direction of the recording paper 7 with respect to the inkjet head 1E). In this case, the film thickness distribution of the piezoelectric material layer 31 is generated in a direction orthogonal to the arrangement direction of the ejection nozzles 20 (pressure chambers 14). The direction in which this film thickness distribution is generated is the dot formed on the recording paper 7. Since the direction is different from the arrangement direction (paper feeding direction), the influence of the film thickness distribution of the piezoelectric material layer 31 on the variation in dot size is reduced.

<Modification 6>
The piezoelectric material layer 31 is not necessarily formed on the surface of the vibration plate opposite to the flow path unit, and is formed on the surface of the vibration plate 30 on the flow path unit 2 side as in the inkjet head 1F shown in FIG. May be.

<Modification 7>
In the embodiment, the piezoelectric material layer 31 that is one of the thin film layers constituting the piezoelectric actuator 3 is formed by the AD method. However, a thin film layer other than the piezoelectric material layer 31 may be formed by the AD method. Good. For example, as in the inkjet head 1G shown in FIG. 19, the individual electrode 32 is disposed on the upper surface of the diaphragm 30 (the lower surface of the piezoelectric material layer 31), and the common electrode 34 is formed on the upper surface of the piezoelectric material layer 31 as a plurality of individual electrodes. On the other hand, the configuration of being opposed to each other in common has an advantage that wiring for supplying a driving voltage to the individual electrode 32 can be easily routed on the upper surface of the diaphragm 30. However, when the diaphragm 30 is a metal plate, it is necessary to provide an insulating layer 36 that insulates between the diaphragm 30 and the individual electrodes 32. The insulating layer 36 needs to have a certain degree of rigidity like the diaphragm 30 in order to reliably transmit the deformation of the piezoelectric material layer 31 to the ink in the pressure chamber. For example, an insulating material such as alumina or zirconia is used. It is made of a ceramic material.

  Here, the insulating layer 36 made of a ceramic material such as alumina can be formed by the AD method in the same manner as the film forming step of the piezoelectric material layer 31 described above. That is, the aerosol containing the fine particles of the ceramic material forming the insulating layer 36 and the carrier gas is transferred to the slit 55 of the film forming nozzle 52 while moving the film forming nozzle 52 having the slit 55 in a predetermined direction with respect to the vibration plate 30. Are sprayed onto the diaphragm 30 (see FIG. 8). At this time, as in the case where the piezoelectric material layer 31 is formed, the insulating layer 36 is likely to have a film thickness distribution in a direction perpendicular to the moving direction of the film forming nozzle 52. If there is this film thickness distribution, the rigidity of the insulating layer 36 varies, which affects the droplet ejection characteristics.

  Therefore, the film forming nozzle 52 is relatively moved with respect to the vibration plate 30 in the paper feeding direction (or a direction inclined at a predetermined angle with respect to the paper feeding direction as in the above-described modification 5 (see FIG. 17)). Let Then, the direction in which the film thickness portion is generated in the insulating layer 36 is different from the direction in which dots are arranged on the recording paper 7, and the influence of the film thickness distribution on the variation in dot size is reduced. Banding caused by the variation in height becomes inconspicuous.

  In the modified embodiment 7, both the insulating layer 36 and the piezoelectric material layer 31 may be formed by the above-described film forming process using the AD method, or the piezoelectric material layer 31 may be formed by a method other than the AD method. A film may be formed.

<Modification 8>
The above-described embodiment and its modification are examples in which the present invention is applied to a method for manufacturing a serial-type inkjet head, but the present invention can also be applied to a line-type inkjet head.

  As shown in FIG. 20, the line-type inkjet head 1H according to the modified embodiment 8 is fixedly provided to a printer frame (not shown). The line type ink jet head 1H is not moved by the carriage like the serial type ink jet head. Therefore, in the case of a line type ink jet head, the relative movement direction of the recording paper with respect to the ink jet head at the time of recording is the paper feed direction in which the paper is fed by a transport roller (moving device: see FIG. 1). In the inkjet head, the relative movement direction of the recording paper with respect to the inkjet head is the scanning direction). The inkjet head 1H includes a flow path unit 2H in which an ink flow path is formed, and a piezoelectric actuator 3H disposed on the upper surface of the flow path unit 2H.

  The flow path unit 2H has a plurality of jets arranged in four rows at equal intervals in the head longitudinal direction (vertical direction in FIG. 20) perpendicular to the paper feed direction (the horizontal direction in FIG. 20) in which the recording paper 7 is conveyed. The nozzle 20 and a plurality of pressure chambers 14 arranged in four rows corresponding to the plurality of injection nozzles 20 are provided. Ink is supplied to the plurality of pressure chambers 14 from the ink supply port 18 via the manifold 17. Since the structure of the individual ink flow path from the manifold to the ejection nozzle 20 via the pressure chamber 14 is substantially the same as in the above embodiment, detailed description thereof is omitted.

  The piezoelectric actuator 3H corresponds to the vibration plate 30 covering the plurality of pressure chambers 14, the piezoelectric material layer 31 disposed on the upper surface of the vibration plate 30, and the plurality of pressure chambers 14 on the upper surface of the piezoelectric material layer 31, respectively. And a plurality of individual electrodes 32 arranged. Since this piezoelectric actuator 3H has a configuration similar to that of the above-described embodiment, a detailed description thereof will be omitted.

  This line type ink jet head 1H ejects ink from a plurality of ejection nozzles 20 onto the recording paper 7 conveyed in the left-right direction in FIG. It is formed on the recording paper 7. When the piezoelectric material layer 31 of the piezoelectric actuator 3H is formed on the upper surface of the vibration plate 30 in the manufacturing process of the line type ink jet head 1H, the film formation nozzle 52 is indicated by a broken line arrow in FIG. The aerosol is ejected from the film forming nozzle 52 onto the diaphragm 30 while being moved relative to the diaphragm 30 in a direction parallel to the arrangement direction of the plurality of ejection nozzles 20 (direction orthogonal to the paper feed direction). Let At this time, a film thickness distribution is generated in the piezoelectric material layer 31 formed on the vibration plate 30 in the paper feed direction, which is a direction orthogonal to the moving direction of the film forming nozzle 52.

  However, since the direction in which the film thickness distribution occurs is orthogonal to the direction in which dots are formed on the recording paper 7 (the direction in which the ejection nozzles 20 are arranged), the film thickness distribution of the piezoelectric material layer 31 is the size of the dots. The influence on the variation in the thickness is small, and the banding caused by the variation is not noticeable.

  Although the present invention has been specifically described with the above-described embodiments and modifications, the present invention is not limited thereto, and includes those improvements and modifications that a person skilled in the art can think of. The structure, dimensions, and materials of the ink jet head are not limited to those shown in the above embodiment, and various types can be used. Although the case where the piezoelectric actuator is applied to the ink jet head has been described, the present invention is not limited to this and can be applied to various liquid ejection or liquid transport devices.

1 is a schematic configuration diagram of an inkjet printer according to an embodiment of the present invention. It is a top view of an inkjet head. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is the VV sectional view taken on the line of FIG. It is explanatory drawing of the manufacturing process of an inkjet head. It is a schematic block diagram of the film-forming apparatus. It is a figure which shows the positional relationship of the diaphragm and film-forming nozzle at the time of film-forming of a piezoelectric material layer, (a) is the positional relationship at the time of film-forming in the area | region with a diaphragm, (b) is another area | region of a diaphragm. (C) shows the relationship between the spray region and the active part. It is a figure which shows the film-forming state of a piezoelectric material layer when a film-forming nozzle is relatively moved in a direction parallel to the scanning direction, (a) is a plan view of the inkjet head, and (b) is viewed from the scanning direction. FIG. 4C is a side view of the piezoelectric actuator when viewed from the paper feeding direction. FIG. 10 is a plan view of an ink jet head having a piezoelectric material layer formed by the film forming process of FIG. 9 and a diagram showing dots formed on a recording paper by the ink jet head. It is a figure which shows the film-forming state of the piezoelectric material layer when the film-forming nozzle is relatively moved in a direction parallel to the paper feed direction, (a) is a plan view of the inkjet head, and (b) is seen from the scanning direction. FIG. 4C is a side view of the piezoelectric actuator when viewed from the paper feeding direction. FIG. 12A is a plan view of an ink jet head having a piezoelectric material layer formed by the film forming process of FIG. 11 and a diagram showing dots formed on a recording paper by the ink jet head. It is a side view of a piezoelectric actuator when viewed from the paper feed direction. It is a figure which shows the film-forming state of the piezoelectric material layer of the modification 1, (a) is a top view of an inkjet head, (b) is a side view of a piezoelectric actuator when it sees from a scanning direction, (c) is paper feeding It is a side view of a piezoelectric actuator when viewed from a direction. It is a top view of the inkjet head of the modification 2. It is a figure which shows the film-forming state of the piezoelectric material layer of the modification 3, (a) is a top view of a piezoelectric actuator (inkjet head), (b) is a side view of a piezoelectric actuator when it sees from a scanning direction, (c) ) Is a side view of the piezoelectric actuator as viewed from the paper feed direction. It is a top view of the inkjet head of the modification 4. It is a top view of the inkjet head of the modification 5. It is sectional drawing equivalent to FIG. 4 of the inkjet head of the modification 6. It is sectional drawing equivalent to FIG. 4 of the inkjet head of the modification 7. It is a top view of the line-type inkjet head of the modification 8. (A) is a plan view of an inkjet head having a piezoelectric material layer formed by relatively moving a film forming nozzle in a direction parallel to the scanning direction, and (b) is a piezoelectric actuator as viewed from the scanning direction. FIG.

Explanation of symbols

1, 1A to 1G Serial type inkjet head 1H Line type inkjet head 3, 3H Piezoelectric actuator 7 Recording paper 14 Pressure chamber 20 Injection nozzle 30 Diaphragm 31 Piezoelectric material layer 32 Individual electrode 36 Insulating layer 52 Film forming nozzle 53 Stage 55 Slit 100 Inkjet printer

Claims (25)

A plurality of pressure chambers each extending in a predetermined direction and arranged along a plane; a flow path unit having a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink; and the plurality of the plurality of pressure chambers An ink jet head comprising a substrate disposed on one surface of the flow path unit so as to cover the pressure chamber, and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate. A manufacturing method of
Forming the plurality of thin film layers of the piezoelectric actuator on the substrate;
Attaching a flow path unit to the substrate,
In the step of forming the thin film layer, at least one thin film layer of the plurality of thin film layers is formed with respect to the substrate in a direction crossing the slit width direction and the predetermined direction by using a film forming nozzle in which a slit is formed. The inkjet head manufacturing method is characterized by forming the film by ejecting an aerosol containing particles forming the thin film layer and a carrier gas from the slit of the film forming nozzle while relatively moving the film.   The method for manufacturing an ink jet head according to claim 1, wherein the direction intersecting the predetermined direction is a direction orthogonal to the predetermined direction.   2. The method of manufacturing an ink jet head according to claim 1, wherein the film forming nozzle has a slit length such that an area of aerosol sprayed from the slit to the substrate covers at least one pressure chamber.   2. The method of manufacturing an ink jet head according to claim 1, wherein the direction intersecting the predetermined direction is a direction orthogonal to a relative movement direction of the recording medium with respect to the ink jet head during recording using the ink jet head. The plurality of ejection nozzles are arranged so as to form a plurality of dots arranged at equal intervals in one direction on the recording medium, respectively.
The method of manufacturing an ink jet head according to claim 1, wherein a relative movement direction of the film forming nozzle with respect to the substrate is an arrangement direction of the plurality of dots. The plurality of spray nozzles are arranged in at least one direction,
2. The method of manufacturing an ink jet head according to claim 1, wherein a relative movement direction of the film forming nozzle with respect to the substrate is an arrangement direction of the plurality of ejection nozzles. The plurality of injection nozzles are arranged in a matrix along a first arrangement direction and a second arrangement direction that intersects the first arrangement direction,
The relative movement direction of the film forming nozzle with respect to the substrate is an arrangement direction of the first arrangement direction and the second arrangement direction, which has the larger arrangement number of the ejection nozzles. The manufacturing method of the inkjet head as described in any one of.   In the aerosol injection, the aerosol is injected while moving the film forming nozzle relative to each of a plurality of regions of the substrate arranged in a relative movement direction of the recording medium with respect to the inkjet head. Item 2. A method for manufacturing an inkjet head according to Item 1.   The said aerosol injection WHEREIN: The said piezoelectric material layer is formed by injecting the aerosol containing the particle | grains of a piezoelectric material and carrier gas from the slit of the said film-forming nozzle to the said board | substrate. A method for manufacturing an inkjet head.   The method of manufacturing an ink jet head according to claim 9, wherein the piezoelectric material layer is formed on a side of the substrate opposite to the flow path unit. The inkjet head is a serial inkjet head that ejects ink from the plurality of ejection nozzles to the recording medium that is transported in a direction orthogonal to the scanning direction while moving in a predetermined scanning direction.
The method of manufacturing an ink jet head according to claim 1, wherein a relative movement direction of the film forming nozzle with respect to the substrate is a conveyance direction of the recording medium. The inkjet head is a line-type inkjet head having a plurality of the ejection nozzles arranged at equal intervals in a direction orthogonal to the direction in which the recording medium is conveyed,
The method of manufacturing an ink jet head according to claim 1, wherein a relative movement direction of the film forming nozzle with respect to the substrate is an arrangement direction of the plurality of ejection nozzles. A flow path unit having a plurality of pressure chambers, a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink onto a recording medium, and the flow path unit so as to cover the plurality of pressure chambers An inkjet head having a substrate disposed on the substrate, and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate, and the inkjet head is moved relative to the recording medium. A method of manufacturing an ink jet printer having a moving device for moving in a direction,
Forming an inkjet head by forming the plurality of thin film layers of the piezoelectric actuator on the substrate and attaching a flow path unit to the substrate;
Providing the mobile device;
When forming the thin film layer, at least one thin film layer of the plurality of thin film layers is formed on the substrate in a direction crossing the slit width direction and the relative movement direction by using a film forming nozzle in which a slit is formed. A method for manufacturing an ink jet printer, comprising: forming an aerosol containing particles forming a thin film layer and a carrier gas from a slit of the film forming nozzle while being moved relative to each other.   The method of manufacturing an ink jet printer according to claim 13, wherein the ink jet head includes a plurality of heads that respectively eject a plurality of types of inks having different colors. A method for manufacturing a piezoelectric actuator having a substrate and a plurality of thin film layers including a piezoelectric material layer disposed on the substrate, wherein a plurality of active portions extending in a predetermined direction are defined in the piezoelectric material layer. ,
Forming the piezoelectric material layer on the substrate;
Forming a thin film layer other than the piezoelectric material layer on the substrate,
The film formation nozzle is formed by moving a film formation nozzle in which a slit is formed relative to the substrate in the slit width direction and in a direction intersecting the predetermined direction, at least one thin film layer of the plurality of thin film layers. A method for manufacturing a piezoelectric actuator, comprising: forming an aerosol containing particles forming a thin film layer and a carrier gas from a nozzle slit.   The method of manufacturing a piezoelectric actuator according to claim 15, wherein the at least one thin film layer is a piezoelectric material layer.   16. The method of manufacturing a piezoelectric actuator according to claim 15, wherein the thin film layer includes a metal plate and an insulating layer, and at least one layer is an insulating layer.   The method for manufacturing a piezoelectric actuator according to claim 15, wherein the active portion is a portion of a piezoelectric material layer sandwiched between electrodes. An inkjet head that ejects ink,
A plurality of pressure chambers each extending in a predetermined direction and arranged along a plane, and a flow path unit having a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink.
A substrate disposed on one surface of the flow path unit so as to cover the plurality of pressure chambers, and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate. ,
In at least one thin film layer of the plurality of thin film layers, the thickness uniformity of the thin film layer in the direction intersecting the predetermined direction is higher than the thickness uniformity of the thin film layer in the direction orthogonal to the intersecting direction. Inkjet head characterized.   The at least one thin film layer is moved from the slit of the film forming nozzle while moving the film forming nozzle in which the slit is formed relative to the substrate in the direction of the slit width and in a direction intersecting the predetermined direction. The inkjet head according to claim 19, wherein the inkjet head is formed by ejecting an aerosol containing particles forming the thin film layer and a carrier gas. A flow path unit having a plurality of pressure chambers, a plurality of ejection nozzles that respectively communicate with the plurality of pressure chambers and eject ink onto a recording medium, and the flow path unit so as to cover the plurality of pressure chambers An inkjet head comprising: a substrate disposed on the substrate; and a piezoelectric actuator having a plurality of thin film layers including a piezoelectric material layer disposed on one surface of the substrate;
A moving device for moving the inkjet head in a direction of relative movement with respect to the recording medium,
In at least one thin film layer of the plurality of thin film layers, the thickness uniformity of the thin film layer in the direction intersecting the relative movement direction is higher than the thickness uniformity of the thin film layer in the direction orthogonal to the intersecting direction. Inkjet printer characterized by.   The at least one thin film layer is moved from the slit of the film forming nozzle while moving the film forming nozzle in which the slit is formed relative to the substrate in the direction of the slit width and in a direction intersecting the relative movement direction. The inkjet printer according to claim 21, wherein the inkjet printer is formed by ejecting an aerosol containing particles forming the thin film layer and a carrier gas. A piezoelectric actuator used for discharging liquid,
A substrate,
A plurality of thin film layers including a piezoelectric material layer disposed on the substrate,
A plurality of active portions extending in a predetermined direction are defined in the piezoelectric material layer,
In at least one thin film layer of the plurality of thin film layers, the thickness uniformity of the thin film layer in the direction intersecting the predetermined direction is higher than the thickness uniformity of the thin film layer in the direction orthogonal to the intersecting direction. Characteristic piezoelectric actuator.   The at least one thin film layer is moved from the slit of the film forming nozzle while moving the film forming nozzle in which the slit is formed relative to the substrate in the width direction of the slit and in a direction intersecting the predetermined direction. The piezoelectric actuator according to claim 23, wherein the piezoelectric actuator is formed by injecting an aerosol containing particles forming a thin film layer and a carrier gas.   25. The piezoelectric actuator according to claim 24, wherein a direction intersecting with the predetermined direction is a direction orthogonal to the predetermined direction.

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