JP2012187714A - Droplet ejection head, image forming apparatus, and method of manufacturing droplet ejection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet ejection head having nozzles arranged at high density capable of improving ejection efficiency and image quality.SOLUTION: The droplet ejection head includes: a nozzle plate including a plurality of nozzles for ejecting droplets of a recording liquid used for image forming; a channel plate forming a plurality of pressurizing chambers communicating with the respective nozzles; a vibration plate 3 configuring one wall face of each pressurizing chamber and having diaphragm parts disposed thereon; and a piezoelectric element for generating energy to pressurize each pressurizing chamber. Each diaphragm part 51 includes an island part 51b for transmitting energy to the pressurizing chamber by abutting on the piezoelectric element, and first thin parts 51c, 51d provided around the island part 51b for facilitating deformation of a portion corresponding to the pressurizing chamber. Each island part 51b is provided with a slit-shaped second thin part 51e not abutting on the piezoelectric element, and extending parallel to a direction orthogonal to the alignment direction of the nozzles.

Description

  The present invention relates to a droplet discharge head that discharges recording droplets used for image formation, an image forming apparatus, and a method for manufacturing a droplet discharge head.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, a plotter, or a complex machine of these, a recording composed of a liquid droplet ejection head (liquid ejection head) that ejects liquid droplets (for example, ink droplets) of recording liquid used for image formation. An ink jet recording apparatus or the like is known as an image forming apparatus using a head. This liquid discharge recording type image forming apparatus means that ink droplets from an inkjet head are transported on paper (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected to a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). A serial type image forming apparatus that forms an image by ejecting droplets while the inkjet head moves in the main scanning direction, and a line type head that forms images by ejecting droplets without moving the inkjet head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar one, but includes an image given to a three-dimensionally formed image, and an image formed by three-dimensionally modeling a solid itself.

  In recent droplet discharge heads, a technology for realizing high image quality without increasing the number of nozzles and increasing the number of heads is already known. However, in conventional high-density nozzle heads, it is difficult to secure the diaphragm diaphragm thin wall width in the nozzle arrangement direction, and it is difficult to increase the displacement of the diaphragm. There was a problem that the width of the partition wall defining the pressure chamber was reduced and the discharge efficiency was lowered and the image quality was lowered due to increased crosstalk. In addition, the residual pressure vibration in the pressure chamber immediately after ejecting a relatively large amount of droplets affects the ejection speed and direction of the next droplet, resulting in streaks and unevenness in the printed image. There was a problem that the image quality deteriorated.

  In Patent Document 1, for the purpose of obtaining high responsiveness and high stability of an ink jet head, a thin portion that can be elastically deformed by pressure during ejection is provided in a pressure chamber, and an opposing wall is provided in a region facing the thin portion. A configuration in which the thin portion abuts against the opposing wall is disclosed. In this configuration, the rigidity of the pressure chamber is reduced after ink discharge and the residual pressure vibration is alleviated, but the rigidity of the pressure chamber is not reduced during ink discharge and the ink discharge efficiency is not reduced. However, the above-described problem of lowering the discharge efficiency due to the higher nozzle density cannot be solved.

  The present invention has been made in view of the above circumstances, and in a droplet discharge head having a high-density nozzle, the displacement of the diaphragm is increased, and by suppressing crosstalk and residual vibration in the pressure chamber, the discharge efficiency and It is an object of the present invention to provide a droplet discharge head, an image forming apparatus, and a method for manufacturing the droplet discharge head that can improve image quality.

  In order to achieve such an object, a liquid droplet ejection head according to the present invention includes at least a nozzle plate including a plurality of nozzles for ejecting liquid droplets of a recording liquid used for image formation, and a pressurized liquid communicating with each of the nozzles. A flow path plate that forms a plurality of chambers, a diaphragm that constitutes one wall surface of the pressurizing liquid chamber, and in which a diaphragm portion is disposed, and a piezoelectric element that generates energy for pressurizing the pressurizing liquid chamber. It is a droplet discharge head, and the diaphragm part is in contact with the piezoelectric element to transmit the energy to the pressurized liquid chamber, and the portion corresponding to the pressurized liquid chamber is easily deformed around the island part. The island portion is provided with a slit-like second thin portion that does not contact the piezoelectric element and extends in a direction perpendicular to the nozzle arrangement direction. It is characterized by that.

  An image forming apparatus according to the present invention includes the above-described droplet discharge head according to the present invention.

  The method for manufacturing a droplet discharge head according to the present invention is a method for manufacturing the droplet discharge head according to the present invention, wherein the first resist film is formed on the substrate as a step of forming a diaphragm constituting the droplet discharge head. A step of applying, a step of exposing the first resist film using the first optical mask to form a first film altered portion, and a step of applying a second resist film on the first resist film And a step of exposing the second resist film using the second optical mask to form a second film alteration portion, and the first resist film and the second resist film with respect to the first resist film and the second resist film. Removing the portion other than the first resist portion and the second resist portion, on the substrate, being thicker than the thickness of the first resist film and thinner than the combined thickness of the first resist film and the second resist film, Step of forming nickel electroformed layer, first resist portion and second resist The first resist portion corresponds to at least the first thin portion and the second thin portion, and the second resist portion corresponds to at least the second thin portion. It is characterized by.

  According to the present invention, in a droplet discharge head having a high density nozzle, it is possible to improve the discharge efficiency and image quality by expanding the displacement of the diaphragm and suppressing crosstalk and residual vibration in the pressure chamber.

It is a disassembled perspective view explaining the liquid chamber structure of the droplet discharge head which concerns on one Embodiment of this invention. It is a liquid chamber longitudinal cross-sectional view explaining the liquid chamber structure of the droplet discharge head which concerns on one Embodiment of this invention. FIG. 3 is a cross-sectional view in the lateral direction of the liquid chamber for explaining the liquid chamber structure of the droplet discharge head (in the case of a bi-pitch structure) according to an embodiment of the present invention. FIG. 5 is a cross-sectional view in the lateral direction of the liquid chamber for explaining the liquid chamber structure of the droplet discharge head (in the case of a normal pitch structure) according to an embodiment of the present invention. It is a nozzle surface direction top view of the diaphragm which comprises the droplet discharge head of a prior art. It is a nozzle surface direction top view of a diaphragm which constitutes a droplet discharge head concerning one embodiment of the present invention. It is sectional drawing of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. It is sectional drawing explaining the transition at the time of the behavior of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. It is sectional drawing explaining the transition of the formation process of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. It is sectional drawing which shows another shape of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. It is sectional drawing which shows another shape of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. It is sectional drawing which shows another shape of the diaphragm part of the diaphragm which concerns on one Embodiment of this invention. 1 is a schematic configuration diagram illustrating an overall configuration of a mechanism unit of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a plan view illustrating a main part of a mechanism unit of the image forming apparatus according to the embodiment of the present invention. 1 is a schematic configuration diagram of an entire mechanism unit of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of a recording head of an image forming apparatus according to an embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the accompanying drawings.

First, an outline of the present invention will be described. The present invention provides a liquid chamber configuration in which a slit-shaped second thin portion is provided in a direction perpendicular to the nozzle arrangement direction in a part of a thick portion (island) that comes into contact with a piezoelectric element among diaphragm portions of a diaphragm. It is characterized by. With this feature, the effect of absorbing the pressure fluctuation in the individual liquid chamber and the crosstalk with the adjacent nozzle can be obtained by the elastic deformation of the second thin portion, and the discharge efficiency and the image quality can be improved. Further, according to the present invention, the thick portion group divided by the second thin portion is located at the outermost edge, and the surface in contact with the piezoelectric element is inclined so as to be lowered in the outer edge direction, and the fluctuation amount due to the inclination Is more than the driving displacement amount of the piezoelectric element.
Due to this feature, the thickest part of the outermost edge is inclined by being pushed by the piezoelectric element when the piezoelectric element is driven, and the bottom surface of the thicker part on the pressure chamber side is displaced toward the outer edge of the diaphragm. Even in a high-density head that cannot be sufficiently secured, the first thin portion is not loosened and the displacement of the piezoelectric element is not limited. Therefore, the thick portion can be displaced by the original displacement amount of the piezoelectric element. At the same time, the second thin-walled portion is pulled to increase the rigidity. Therefore, even if the second thin-walled portion is provided in the thick-walled portion, the discharge efficiency does not decrease. Such features of the present invention will be described below in detail with reference to the drawings.

  An example of the droplet discharge head of this embodiment will be described with reference to FIGS. 1 is an exploded perspective view of the droplet discharge head of the present embodiment, FIG. 2 is a sectional view of the droplet discharge head of the present embodiment along the longitudinal direction of the liquid chamber, and FIG. 3 is a bi-pitch structure. FIG. 4 is a cross-sectional explanatory view along the short side direction of the liquid chamber of the liquid droplet ejection head of the present embodiment. FIG. 4 is an explanatory view of the cross section along the short side direction of the liquid chamber of the liquid droplet discharge head according to the present embodiment. It is.

  The liquid discharge head of the present embodiment includes a flow path plate 1 that is a flow path forming member made of, for example, a silicon member, and a nozzle plate 2 that is made of a metal member that is a nozzle forming member joined to the upper surface of the flow path plate 1. A nozzle 3 that has a diaphragm 3 made of a metal member joined to the lower surface of the flow path plate 1 and discharges liquid droplets (droplets of recording liquid used for image formation, for example, ink droplets) by these members is a communication path. A pressure liquid chamber 6 (pressure chamber; also simply referred to as “liquid chamber”), a fluid resistance portion 7, and an introduction portion 8 that communicates with the liquid chamber 6 via the fluid resistance portion 7. A recording liquid (for example, ink) is supplied from a common liquid chamber 10 formed in a frame member 17 to be described later to the introduction portion 8 through a supply port 9 formed in the diaphragm 3.

  And it drives via the island part formed in the diaphragm 3 corresponding to each pressurized liquid chamber 6 to the surface outside (surface opposite to the liquid chamber 6) of the diaphragm 3 which forms the wall surface of the liquid chamber 6 An upper end surface of a laminated piezoelectric element 12 (also simply referred to as “piezoelectric element”) as an element (actuator means, pressure generating means) is joined. Further, the lower end surface of the multilayer piezoelectric element 12 is joined to the base member 13.

  Here, the piezoelectric element 12 is formed by alternately laminating piezoelectric material layers 21 and internal electrodes 22a and 22b, and the internal electrodes 22a and 22b are respectively drawn out to the end faces and connected to the end face electrodes (external electrodes) 23a and 23b. Then, a voltage is applied to the end face electrodes 23a and 23b to cause displacement in the stacking direction.

  The FPC cable 15 is connected to the piezoelectric element 12 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. A drive circuit (driver IC) (not shown) for selectively applying a drive waveform to each piezoelectric element 12 is mounted on the FPC cable 15.

  In the lateral direction of the liquid chamber (the direction in which the nozzles 4 are arranged), as shown in FIG. 3, a bi-pitch structure in which the piezoelectric elements 12 and the column portions 12A are alternately arranged can be used, or as shown in FIG. Thus, it can also be set as the normal pitch structure which does not provide the support | pillar part 12. FIG.

  In the liquid droplet ejection head of this embodiment, the ink in the liquid chamber 6 is pressurized using the displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 12, and the liquid droplet ejection direction is the recording liquid in the liquid chamber 6. The liquid droplets are ejected by a side shooter method that is different from the flow direction. By adopting the side shooter method, the size of the piezoelectric element 12 becomes substantially the size of the head, and the miniaturization of the piezoelectric element 12 can be directly linked to the miniaturization of the head, and the head can be easily miniaturized. The invention is not limited to this form.

  Further, a frame member 17 formed by injection molding with an epoxy resin or polyphenylene sulfite is joined to the outer peripheral side of the actuator portion composed of the piezoelectric element 12, the base member 13, the FPC 15, and the like.

  The frame member 17 is formed with the common liquid chamber 10 and a supply port 19 for supplying recording liquid from the outside to the common liquid chamber 10. It is connected to a recording liquid supply source such as a recording liquid cartridge.

  Here, the flow path plate 1 is formed with through-holes serving as the communication passages 5, pressurized liquid chambers 6, fluid resistance portions 7, communication portions 8, and the like by anisotropic etching of silicon. . The pressurized liquid chambers 6 are separated from each other by a partition wall 6a.

  The nozzle plate 2 forms a nozzle hole that becomes the nozzle 4 by nickel (Ni) electroforming. The nozzle 4 of the nozzle plate 2 is formed with a hole having a diameter of 10 to 35 μm, for example, and is bonded to the flow path plate 1 with an adhesive. Then, a water repellent treatment is applied to the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 2.

  The diaphragm 3 is formed by nickel electroforming (for example, two or more layers). As shown in FIG. 5, the diaphragm 3 is provided with a diaphragm portion 51. The diaphragm portion 51 includes first thin portions 51c and 51d for facilitating deformation of a portion corresponding to the pressurized liquid chamber 6, and an island portion 51b for joining to the piezoelectric element 12 in the central portion. . The first thin portions 51c and 51d include an island portion 51b when viewed from the direction in which the nozzle 4 is formed (nozzle surface direction). In addition, the structure of the diaphragm part 51 shown in FIG. 5 is used by a prior art. In the present embodiment, in the configuration shown in FIG. 5, the island portion 51 b is provided with a second thin portion. This will be described later with reference to FIG.

  The piezoelectric element 12 is formed by dividing a laminated piezoelectric element member by joining a base member 13 and then performing groove processing with a dicing saw or the like. The column portion 12A when the bi-pitch structure shown in FIG. 3 is used is a piezoelectric element member formed by grooving, but only functions as a column because no drive voltage is applied.

  When the droplet discharge head according to the present embodiment configured as described above is driven by, for example, a pushing method, the plurality of piezoelectric elements 12 are driven at 20 to 50 V according to an image recorded from a control unit (not shown). By selectively applying the pulse voltage, the piezoelectric element 12 to which the pulse voltage is applied is displaced to deform the vibration plate 3 in the direction of the nozzle plate 2, and the liquid chamber 6 changes its volume (volume) in the liquid chamber 6. A liquid droplet is discharged from the nozzle 4 of the nozzle plate 2 by pressurizing the liquid. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, the application of voltage to the piezoelectric element 12 is turned off, so that the diaphragm 2 returns to the original position and the liquid chamber 6 has the original shape, so that further negative pressure is generated. At this time, the recording liquid is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  Here, an example of the diaphragm unit 51 in the liquid droplet ejection head of the present embodiment will be described with reference to FIGS.

  FIG. 6 is a plan view of the diaphragm 3 viewed from the piezoelectric element bonding surface direction. As shown in FIG. 6, in the present embodiment, in the diaphragm portion 51 arranged in the nozzle arrangement direction on the diaphragm 3, the island portion 51 b that contacts the piezoelectric element 12 does not contact the piezoelectric element 12, In addition, a slit-like second thin portion 51e extending in parallel over the entire length of the island portion 51b is provided in a direction orthogonal to the nozzle arrangement direction. By forming such a second thin portion 51e, as shown in FIG. 8, the second thin portion 51e is bent before and after driving, and the pressure fluctuation in the liquid chamber 6 can be efficiently attenuated. Thereby, crosstalk with an adjacent nozzle can also be suppressed. On the other hand, since the second thin portion 51e is tensioned in the pulling direction due to the displacement of the piezoelectric element 12 during driving, the rigidity is increased and the effect is almost the same as that of the thick portion. As a result, during driving, the discharge efficiency equivalent to that formed by the thick portion can be achieved, and before and after driving, the thin portion area facing the liquid chamber 6 can be gained to quickly attenuate the pressure fluctuation.

  Further, as shown in FIG. 7, the thick part 51f at the outermost edge position (on both outer sides of the slit-like second thin part) of the island part 51 partitioned by the second thin part 51e is as shown in FIG. The surface in contact with the piezoelectric element 12 is preferably inclined so as to be lowered in the outer edge direction. By tilting in this way, as shown in FIG. 8, the thick portion 51f is inclined outward during driving and the second thin portion can be more efficiently stretched, so that the rigidity of the second thin portion is further increased. be able to. In addition, since the first thin portion is displaced in the contracting direction, even in a high-density nozzle head in which the width of the first thin portion cannot be sufficiently taken, the first thin portion has a piezoelectric element. Does not hinder driving. Specifically, in the configuration having only the first thin part and the thick part, if the first thin part region is narrow, the first thin part cannot be extended by the displacement of the piezoelectric element, and the piezoelectric element is sufficiently displaced. Can not do it. On the other hand, with such an inclined configuration, the first thin-walled portion is bent due to the inclination of the thick-walled portion 51f during driving, and the displacement of the piezoelectric element can be allowed to a greater extent by the extension of the bent portion. Thereby, sufficient discharge efficiency can be obtained even in a high-density nozzle head.

  At this time, it is preferable that the piezoelectric element 12 and the diaphragm 3 are bonded and held by bonding with the island portion 51b, and the piezoelectric element 12 and the thick portion 51f are not bonded. Even if the tip is bonded, the bonding point is transformed into a fulcrum and the above effect is obtained, but the thick part 51f can be moved more easily by adopting a configuration that can slide on the piezoelectric element without bonding, The above effects can be enhanced.

  Further, the thickness of the first thin portion 51c, 51d and the second thin portion 51e may be different depending on the priority characteristics, and if priority is given to suppression of pressure fluctuation, the second thin portion 51e is replaced with the first thin portion 51e. If it is thinner than the one thin portion 51c, 51d and priority is given to improving the discharge efficiency, it may be formed thicker. However, preferably, the second thin portion 51e is formed with the same thickness as the first thin portions 51c and 51d, and the second thin portion 51e is on the same plane as the first thin portions 51c and 51d. It is good to arrange. By forming in this way, the first thin portions 51c and 51d and the second thin portion 51e can be formed in the same process, and can be formed at the same cost as a normal diaphragm.

  In the slit corresponding to the second thin portion 51e, the width of the opening on the piezoelectric element 12 side is preferably smaller than the width of the opening on the pressurized liquid chamber 6 side. By doing in this way, the rigidity of a thick part can be improved, ensuring a large joint area with a piezoelectric element and ensuring a wide thin part area.

  FIG. 8 is a cross-sectional view for explaining the behavior of the diaphragm portion 51 before and after ejection in the present embodiment. FIG. 8 shows the behavior of the diaphragm portion 51 before, during, and immediately after driving the piezoelectric element 12. In FIG. 8, illustration of each part constituting the diaphragm part 51 is omitted, but it is the same as that shown in FIG. 7.

  First, although not shown, for example, the behavior of the diaphragm portion 51 of the prior art shown in FIG. 5 will be described. In the configuration of the diaphragm 3 shown in FIG. 5, the pressurized liquid chamber 6 is pressurized by the piezoelectric element 12 being displaced in the nozzle surface direction by the drive displacement amount 80a. In such a state where the diaphragm portion 51 is displaced by 80a in the nozzle surface direction by the piezoelectric element 12, the tension of the first thin portion 51d is increased. In particular, in a high-density nozzle head as in the prior art, the width of the first thin portion 51d (see, for example, 81d in FIG. 8) is small due to space limitations, and is about 10 μm at most. Therefore, in the driving state (droplet discharge state) of the piezoelectric element 12, the increase in tension of the first thin portion 51d is also significant when the width is small, and the discharge efficiency is reduced because the displacement of the piezoelectric element 12 is suppressed. It contributes to the decline.

  On the other hand, according to the present embodiment, as shown in FIG. 8, the thick part 51f is pushed by the piezoelectric element 12 when the piezoelectric element 12 is driven (during droplet discharge), and the contact point 51h is centered. The pressure chamber side bottom surface of the incline portion 51f is displaced by Δ = 81d−82d toward the outer edge of the diaphragm 51. As a result, the thin-walled portion 51d is loosened and the rigidity is lowered, and the displacement of the piezoelectric element 12 and the diaphragm 51 is increased by 80c. At the same time, the second thin-walled portion 51e is pulled and the rigidity is increased. Can be prevented from decreasing. In addition, the second thin portion 51e is elastically deformed immediately after discharge, so that pressure vibration in the pressure chamber can be absorbed, and relatively stable discharge is possible immediately after a large amount of discharge is performed in a relatively unit time. It becomes.

  As described above, according to the droplet discharge head of this embodiment, at least a nozzle plate including a plurality of nozzles that discharge droplets used for image formation, and a plurality of pressurized liquid chambers communicating with each of the nozzles. A droplet discharge head comprising: a flow path plate to be formed; a vibration plate that constitutes one wall surface of a pressurized liquid chamber; and a diaphragm in which a diaphragm portion is disposed; and a piezoelectric element that generates energy to pressurize the pressurized liquid chamber The diaphragm part includes an island part that contacts the piezoelectric element and transmits energy to the pressurized liquid chamber, and an island part viewed from the direction in which the nozzle is formed, and corresponds to the pressurized liquid chamber. A slit that extends in parallel over the entire length of the island portion in a direction perpendicular to the nozzle arrangement direction and does not contact the piezoelectric element on the island portion. First Wherein the thin portion of the is provided. Thereby, the 2nd thin part functions as an individual liquid chamber damper, and can absorb pressure fluctuation. In other words, the elastic deformation of the second thin portion provides the effect of absorbing the pressure fluctuation in the individual liquid chamber and the crosstalk with the adjacent nozzle, and the discharge efficiency and the image quality can be improved.

  Further, in the droplet discharge head of the present embodiment, the thick part located at the outermost edge among the island parts separated by the second thin part is inclined so that the surface in contact with the piezoelectric element is lowered in the outer edge direction. The variation amount at both ends of the thick wall portion due to the inclination is not less than the drive displacement amount of the piezoelectric element. In addition, the thick portion is pushed by the piezoelectric element when the piezoelectric element is driven, and is inclined in the nozzle arrangement direction when viewed from the direction orthogonal to the nozzle arrangement direction, and the thick portion located at the outermost edge is added. Displacement of the bottom surface of the pressurized fluid chamber in the outer edge direction of the diaphragm portion causes the first thin portion to contract and the rigidity to decrease, and the second thin portion to expand and the rigidity to increase. With such a feature, the second thin portion is pulled to increase the rigidity, and an effect of preventing the discharge efficiency from being lowered by the second thin portion is obtained. That is, it is possible to prevent the liquid chamber from being lowered in rigidity by the second thin portion during droplet discharge, and to increase the discharge efficiency by increasing the PZT displacement.

  In the droplet discharge head of this embodiment, the thick part located at the outermost edge among the island parts separated by the second thin part is not bonded to the piezoelectric element. With this feature, it is possible to realize cost reduction by saving the adhesive and to easily perform the above-described inclination of the thick portion.

  In the droplet discharge head of this embodiment, the second thin portion has the same thickness as the first thin portion. This feature facilitates processing and realizes cost reduction.

  In the droplet discharge head of this embodiment, the second thin portion is arranged on the same plane as the first thin portion. Due to this feature, machining can be facilitated, cost can be reduced, and the degree of freedom of the machining method can be expanded.

  Next, a method for forming the diaphragm portion 51 of the diaphragm 3 (one embodiment of the method for manufacturing a droplet discharge head of the present invention) will be described with reference to FIG.

  First, as shown in FIG. 9A, a first resist film 91b to be a first resist portion is uniformly applied on the wafer substrate 91a by spin coating or the like (step S1). Here, the wafer substrate 91a indicates the first layer of the diaphragm 3 formed in advance on the base substrate by a similar nickel electroforming method or the like.

  As shown in FIG. 9A, the first resist film 91b is exposed by the first mask 91c, and the regions corresponding to the first thin portion 51d and the second thin portion 51e are cured, and FIG. ), A first film alteration portion (first resist portion) 92a is formed (step S2).

  Usually, the film of the uncured portion is removed at this stage, but the removal is not performed here. As shown in FIG. 9B, the second resist is formed on the first resist film 91b by spin coating or the like again. A film 92b is applied (step S3).

  As shown in FIG. 9B, the second resist film 92b is exposed by the second mask 92c, the region corresponding to the second thin portion 51e is cured, and the second resist film 92b is cured as shown in FIG. A second film alteration portion (second resist portion) 93a is formed (step S4). Here, as shown in FIG. 10 (a), if 92a is offset from 93a by a predetermined amount 95a, the bonding area is expanded without impairing the function as shown in FIGS. 10 (b) and 10 (c). You can also

  With respect to the first resist film 91b and the second resist film 92b, portions other than the film altered portion (resist portion) are removed, as shown in FIG. 9D (step S5).

  Nickel electroforming is performed to form an electroformed layer 94a having a thickness of 93b or more and 93c or less as shown in FIGS. 9 (e) and 9 (f) (step S6).

  Finally, as shown in FIG. 9G, the resists 92a and 93a are dissolved and removed (step S7), and the surface is coated with polyimide bake or the like (step S8). Thus, the diaphragm 3 having the diaphragm 51 is completed. To do.

  It is also possible to form the diaphragm 51 other than the shape shown in FIG. 9G by using the method for forming the diaphragm 51 described in FIG. This example will be described with reference to FIGS.

  In the example of FIG. 11, in the diaphragm part 51 formed in the diaphragm 3, the case where the 2nd thin part 51e is made into one place (upper figure) thru | or three places (lower figure) is shown. If the thick part 51f is arranged symmetrically with respect to the central axis of the island part 51b, the function of the diaphragm part 51 described with reference to FIGS. 7, 8, and 9 (g) is satisfied. However, in the case where there are a plurality of second thin portions 51e (the lower figure), the central thin portion 51g has a smaller increase in rigidity than the thin portion 51e at the end even during discharge. While the function increases, the discharge efficiency decreases.

  In the example of FIG. 12, in the diaphragm portion 51 formed on the diaphragm 3, the second thin portion 51 e extends in parallel to the longitudinal direction of the island portion 51 b and has an annular shape in which both ends are further connected. (Upper and lower figures). The upper figure shows a case where one annular thin part is formed, and the lower figure shows a case where a plurality of annular thin parts are formed. Thereby, the rigidity reduction of the island part 51b by slit-like 2nd thin part 51e installation can be prevented. Further, by arbitrarily arranging a plurality of thin portions 51g in the short direction of the island portion 51b (see the following figure), the pressure fluctuation absorbing function, that is, the compliance value can be adjusted. However, as described above, the thin portion 51g has a relatively small increase in rigidity even during ejection.

  Next, an example of an image forming apparatus including the droplet discharge head according to the present embodiment will be described with reference to FIGS. FIG. 13 is a schematic configuration diagram for explaining the overall configuration of the mechanism section of the apparatus, and FIG. 14 is an explanatory plan view of the main part of the mechanism section.

  This image forming apparatus is a serial type image forming apparatus, and a carriage 233 is slidably held in the main scanning direction by main and slave guide rods 231 and 232 which are guide members horizontally mounted on the left and right side plates 221A and 221B. The main scanning motor that does not perform moving scanning in the direction indicated by the arrow (carriage main scanning direction) via the timing belt.

  The carriage 233 includes the above-described droplet discharge head of the present embodiment for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). A recording head 234 composed of a liquid discharge head unit in which an electric circuit board for supplying a drive signal and a tank for storing ink to be supplied to the head are integrated, and a nozzle array composed of a plurality of nozzles in a sub-scanning direction perpendicular to the main scanning direction And are mounted with the ink droplet ejection direction facing downward.

  The recording head 234 is configured by attaching liquid discharge head units 234a and 234b each having two nozzle rows to one base member, and one nozzle row of one head 234a receives black (K) droplets. The other nozzle row ejects cyan (C) droplets, the other nozzle row of the other head 234b ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. To do. Here, a configuration in which droplets of four colors are ejected in a two-head configuration is used, but it is also possible to arrange four nozzle rows per head and eject each of the four colors with one head.

  Further, the ink of each color is replenished and supplied from the ink cartridge 210 of each color to the tank 235 of the recording head 234 via the supply tube 236 of each color.

  On the other hand, as a paper feeding unit for feeding the paper 242 stacked on the paper stacking unit (pressure plate) 241 of the paper feed tray 202, a half-moon roller (feeding) that separates and feeds the paper 242 one by one from the paper stacking unit 241. A separation pad 244 made of a material having a large coefficient of friction is provided opposite to the sheet roller 243 and the sheet feeding roller 243, and the separation pad 244 is urged toward the sheet feeding roller 243 side.

  In order to feed the sheet 242 fed from the sheet feeding unit to the lower side of the recording head 234, a guide member 245 for guiding the sheet 242, a counter roller 246, a conveyance guide member 247, and a tip pressure roller. And a conveying belt 251 which is a conveying means for electrostatically attracting the fed paper 242 and conveying it at a position facing the recording head 234.

  The conveyor belt 251 is an endless belt, and is configured to wrap around the conveyor roller 252 and the tension roller 253 so as to circulate in the belt conveyance direction (sub-scanning direction). In addition, a charging roller 256 that is a charging unit for charging the surface of the transport belt 251 is provided. The charging roller 256 is disposed so as to come into contact with the surface layer of the conveyor belt 251 and to rotate following the rotation of the conveyor belt 251. The transport belt 251 rotates in the belt transport direction when the transport roller 252 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 242 recorded by the recording head 234, a separation claw 261 for separating the paper 242 from the transport belt 251, a paper discharge roller 262, and a paper discharge roller 263 are provided. A paper discharge tray 203 is provided below the paper discharge roller 262.

  A double-sided unit 271 is detachably attached to the back surface of the apparatus main body. The duplex unit 271 takes in the paper 242 returned by the reverse rotation of the transport belt 251, reverses it, and feeds it again between the counter roller 246 and the transport belt 251. The upper surface of the duplex unit 271 is a manual feed tray 272.

  Further, a maintenance / recovery mechanism 281 that is a head maintenance / recovery device according to the present invention includes a recovery means for maintaining and recovering the nozzle state of the recording head 234 in the non-printing area on one side of the carriage 233 in the scanning direction. Is arranged. The maintenance / recovery mechanism 281 includes a cap member (hereinafter referred to as “cap”) 282a and 282b (hereinafter referred to as “cap 282” when not distinguished) and a nozzle surface for capping each nozzle surface of the recording head 234. A wiper blade 283 that is a blade member for discharging, a blank discharge receiver 284 that receives a droplet when performing a blank discharge that discharges a droplet that does not contribute to recording in order to discharge the thickened recording liquid, and the like. .

  Further, in the non-printing area on the other side in the scanning direction of the carriage 233, there is an empty space for receiving a liquid droplet when performing an empty discharge for discharging a liquid droplet that does not contribute to the recording in order to discharge the recording liquid thickened during the recording. A discharge receiver 288 is disposed, and the idle discharge receiver 288 is provided with an opening 289 along the nozzle row direction of the recording head 234 and the like.

  In this image forming apparatus configured as described above, the sheets 242 are separated and fed one by one from the sheet feeding tray 202, and the sheet 242 fed substantially vertically upward is guided by the guide 245, and is conveyed to the conveyor belt 251 and the counter. It is sandwiched between the rollers 246 and conveyed, and further, the leading end is guided by the conveying guide 237 and pressed against the conveying belt 251 by the leading end pressing roller 249, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately applied to the charging roller 256, that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 251 alternates, that is, in the sub-scanning direction that is the circumferential direction. , Plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 242 is fed onto the conveyance belt 251 charged alternately with plus and minus, the sheet 242 is attracted to the conveyance belt 251, and the sheet 242 is conveyed in the sub scanning direction by the circumferential movement of the conveyance belt 251.

  Therefore, by driving the recording head 234 according to the image signal while moving the carriage 233, ink droplets are ejected onto the stopped paper 242 to record one line, and after the paper 242 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 242 has reached the recording area, the recording operation is finished and the paper 242 is discharged onto the paper discharge tray 203.

  As described above, in this image forming apparatus, since the droplet discharge head according to the above-described embodiment is provided as a recording head, reliability is improved.

  Next, another example of the image forming apparatus including the droplet discharge head according to the present embodiment will be described with reference to FIG. FIG. 15 is a schematic configuration diagram of the entire mechanism unit of the apparatus.

  This image forming apparatus is a line type image forming apparatus, has an image forming unit 402 and the like inside the apparatus main body 401, and can supply a large number of recording media (sheets) 403 on the lower side of the apparatus main body 401. A paper tray 404 is provided, a sheet 403 fed from the sheet feeding tray 404 is taken in, a required image is recorded by the image forming unit 402 while the sheet 403 is conveyed by the conveying mechanism 405, and then the side of the apparatus main body 401. The paper 403 is discharged to a paper discharge tray 406 attached to the printer.

  Also, a duplex unit 407 that can be attached to and detached from the apparatus main body 401 is provided, and when performing duplex printing, the sheet 403 is conveyed into the duplex unit 407 while being transported in the reverse direction by the transport mechanism 405 after one-side (front) printing is completed. Then, the other side (back side) is sent back to the transport mechanism 405 as the printable side, and the paper 403 is discharged to the paper discharge tray 406 after the other side (back side) printing is completed.

  Here, the image forming unit 402, for example, discharges liquid droplets of each color of yellow (Y), magenta (M), cyan (C), and black (K) according to four line-type liquids according to the present embodiment. Each recording head 411 includes recording heads 411y, 411m, 411c, and 411k (hereinafter referred to as “recording head 411” when colors are not distinguished), which are configured by integrating a droplet discharge head and a sub-tank that supplies ink to the liquid discharge head. Is attached to the head holder 413 with the nozzle surface on which nozzles for discharging droplets are formed facing downward.

  As shown in FIG. 16, one recording head 411 has a predetermined positional relationship between a plurality of (six in this example) droplet discharge heads 501 </ b> A to 501 </ b> F according to this embodiment integrated with a sub-tank. However, it can also be constituted by a single full-line type droplet discharge head.

  In addition, a maintenance / recovery mechanism 412y, 412m, 412c, 412k (referred to as “maintenance / recovery mechanism 412” when colors are not distinguished) corresponding to each recording head 411 is provided to maintain and recover the performance of the head. During the head performance maintenance operation such as wiping processing, the recording head 411 and the maintenance / recovery mechanism 412 are relatively moved so that the capping member constituting the maintenance / recovery mechanism 412 faces the nozzle surface of the recording head 411.

  The paper 403 in the paper feed tray 404 is separated one by one by a paper feed roller (half-moon roller) 421 and a separation pad (not shown) and fed into the apparatus main body 401, and is registered along the guide surface 423 a of the transport guide member 423. It is sent between 425 and the conveyor belt 433, and is sent to the conveyor belt 433 of the conveyor mechanism 405 via the guide member 426 at a predetermined timing.

  The conveyance guide member 443 is also formed with a guide surface 423 b for guiding the paper 403 sent out from the duplex unit 407. Further, a guide member 427 for guiding the sheet 403 returned from the transport mechanism 405 to the duplex unit 407 during duplex printing is also provided.

  The conveyance mechanism 405 includes an endless conveyance belt 433 that is stretched between a conveyance roller 431 that is a driving roller and a driven roller 432, a charging roller 434 that charges the conveyance belt 433, and an image forming unit 402. A platen member 435 that maintains the flatness of the conveyance belt 433 at the opposite portion, a pressing roller 436 that presses the paper 403 fed from the conveyance belt 433 against the conveyance roller 431 side, and other recording liquid that is attached to the conveyance belt 433, although not shown. It has a cleaning roller made of a porous material or the like, which is a cleaning means for removing (ink). As the transport mechanism, for example, a mechanism that sucks the recording medium onto the transport belt by air suction can be used.

  On the downstream side of the transport mechanism 405, a paper discharge roller 438 and a spur 439 for sending the paper 403 on which an image is recorded to the paper discharge tray 406 are provided.

  In the image forming apparatus configured as described above, the conveyance belt 433 moves in the direction indicated by the arrow and is charged by contact with the charging roller 434 to which a high applied voltage is applied. When 403 is fed, the sheet 403 is electrostatically attracted to the conveyance belt 433. In this way, the sheet 403 that is strongly adsorbed to the transport belt 433 is calibrated for warpage and unevenness, and forms a highly flat surface.

  Then, the paper 403 is moved around the conveyor belt 433 and droplets are ejected from the recording head 411, whereby a required image is formed on the paper 403, and the paper 403 on which the image has been recorded is the paper discharge roller 438. As a result, the paper is discharged to the paper discharge tray 406.

  As described above, since the image forming apparatus includes the droplet discharge head according to the present embodiment, the discharge efficiency and the image quality can be improved, and the reliability of the image formation is improved.

  In the above embodiment, an image forming apparatus having a printer configuration has been described as an example. However, the present invention is not limited to this, and as described above, the image forming apparatus can be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. In addition, as described above, the present invention can also be applied to an image forming apparatus using a liquid other than the narrowly defined ink or a fixing processing liquid.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above description, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Flow path plate 2 Nozzle plate 3 Vibrating plate 4 Nozzle 5 Communication path 6 Pressurized liquid chamber 6a Bulkhead 7 Fluid resistance part 8 Introduction part 9 Supply port 10 Common liquid chamber 12 Stacked piezoelectric element 12A Strut part 13 Base member 15 FPC cable 17 Frame member 19 Supply port 21 Piezoelectric material layer 22a, 22b Internal electrode 23a, 23b End face electrode 51 Diaphragm part 51b Island part 51c, 51d First thin part 51e Second thin part 51f Thick part 51h Contact point 81g Inclination amount 91a Wafer substrate 91b First resist film 91c First mask 92a First film altered portion (resist portion)
92b Second resist film 92c Second mask 93a Second film altered portion (resist portion)
93b Height (thickness) of the first membrane alteration part
93c Combined height (thickness) of the first and second membrane affected parts
94a Electroformed layer

JP 2003-127372 A

Claims (11)

At least a nozzle plate including a plurality of nozzles for discharging droplets of a recording liquid used for image formation, a flow path plate for forming a plurality of pressurized liquid chambers communicating with each of the nozzles, and the pressurized liquid chamber A droplet discharge head comprising a diaphragm having a single wall surface and a diaphragm portion disposed thereon, and a piezoelectric element that generates energy for pressurizing the pressurized liquid chamber,
The diaphragm part is
An island that contacts the piezoelectric element and transmits the energy to the pressurized liquid chamber;
A first thin portion that facilitates deformation of a portion corresponding to the pressurized liquid chamber around the island portion;
In the island part,
2. A liquid droplet ejection head, comprising: a slit-like second thin portion extending in parallel in a direction orthogonal to the nozzle arrangement direction without contacting the piezoelectric element.   2. The droplet discharge head according to claim 1, wherein the slit-shaped second thin portion is formed over the entire length of the island portion.   The thick part located at the outermost edge among the island parts separated by the second thin part has a surface in contact with the piezoelectric element inclined in a direction away from the piezoelectric element in an outer edge direction. Item 3. The droplet discharge head according to Item 1 or 2.   The thick part is pressed by the piezoelectric element when the piezoelectric element is driven, and is inclined in the nozzle arrangement direction when viewed from the direction orthogonal to the nozzle arrangement direction, and is located at the outermost edge. As the bottom surface of the pressurized liquid chamber side is displaced in the outer edge direction of the diaphragm portion, the first thin portion contracts and the rigidity decreases, and the second thin portion expands and the rigidity increases. The droplet discharge head according to claim 3.   The thick part located in the outermost edge among the said island parts isolate | separated by the said 2nd thin part is not adhere | attached on the said piezoelectric element, The any one of Claim 1 to 4 characterized by the above-mentioned. Droplet discharge head.   6. The liquid droplet ejection head according to claim 1, wherein the second thin portion has the same thickness as the first thin portion.   The liquid droplet ejection head according to claim 1, wherein the second thin portion is disposed on the same plane as the first thin portion.   8. The droplet discharge head according to claim 1, wherein the diaphragm is made of two or more layers of electroformed nickel.   9. The slit corresponding to the second thin portion has a width of the piezoelectric element side opening that is smaller than a width of the pressurizing liquid chamber side opening. 9. The droplet discharge head described in 1.   An image forming apparatus comprising the droplet discharge head according to claim 1. A method for manufacturing a droplet discharge head according to any one of claims 1 to 9,
As a process of forming a diaphragm constituting the droplet discharge head,
Applying a first resist film on the substrate;
Exposing the first resist film using a first optical mask to form a first film altered portion;
Applying a second resist film on the first resist film;
Exposing the second resist film using a second optical mask to form a second film altered portion;
Removing the portions other than the first resist portion and the second resist portion with respect to the first resist film and the second resist film;
Forming a nickel electroformed layer on the substrate that is thicker than the first resist film and thinner than the combined thickness of the first resist film and the second resist film;
Removing the first resist portion and the second resist portion,
The first resist portion corresponds to at least the first thin portion and the second thin portion,
The method of manufacturing a droplet discharge head, wherein the second resist portion corresponds to at least the second thin portion.

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