Inkjet head and image formation device

Abstract

The present invention provides an inkjet head and an image formation device that make it possible to discharge ink of a plurality of colors without an increase in head size. This inkjet head comprises: a head chip that has formed therein a plurality of individual supply flow paths which individually supply ink to a plurality of nozzles and that has a shear-mode type piezoelectric element which changes the pressure in the individual supply flow paths; and a partition member that has a damper function and that has formed therein a common supply flow path which communicates with the plurality of individual supply flow paths and through which ink flows and a division unit which divides the plurality of individual supply flow paths and the plurality of nozzles into a plurality of regions.

Description

Technical Field

[0001] The present disclosure relates to an inkjet head and an image forming apparatus.Background Art

[0002] In the related art, there are known inkjet image forming apparatuses that form an image on a recording medium, such as a sheet, by discharging ink onto the recording medium from a plurality of nozzles arranged in an inkjet head. Among such inkjet image forming apparatuses, there is an inkjet image forming apparatus capable of handling inks of a plurality of colors with a single inkjet head (for example, see Patent Literature (hereinafter referred to as "PTL") 1). In an inkjet head that handles inks of a plurality of colors, the inks of the plurality of colors are discharged by arranging a plurality of head chips each of which discharges ink of a single color.Citation ListPatent Literatures

[0003] PTL 1 Japanese Patent Application Laid-Open No. 2012-061719Summary of InventionTechnical Problem

[0004] Incidentally, in a case where a plurality of head chips each of which discharges ink of a single color is arranged in one inkjet head to enable inks of a plurality of colors to be discharged, nozzle alignment is required such that the nozzles of the respective head chips are appropriately arranged. However, in order to align the positions of the nozzles, it is necessary to perform position adjustment with high accuracy, and an adjustment margin of the head chip is required. That is, in this case, there is a problem in that the size of the inkjet head increases.

[0005] An object of the present disclosure is to provide an inkjet head and an image forming apparatus that make it possible to discharge inks of a plurality of colors without an increase in head size.Solution to Problem

[0006] An inkjet head according to the present disclosure includes: a head chip that includes a plurality of individual supply flow paths formed in the head chip and a shear-mode type piezoelectric element, where the plurality of individual supply flow paths individually supplies ink to a plurality of nozzles and the shear-mode type piezoelectric element changes pressure in the plurality of individual supply flow paths; and a partition member which has a damper function and in which a common supply flow path and a division unit are formed, where the common supply flow path is a common supply flow path which communicates with the plurality of individual supply flow paths and through which the ink circulates, and the division unit divides the plurality of individual supply flow paths and the plurality of nozzles in a plurality of regions.

[0007] In addition, the image forming apparatus according to the present disclosure includes the inkjet head described above.Advantageous Effects of Invention

[0008] According to the present disclosure, it is possible to discharge inks of a plurality of colors without an increase in head size.Brief Description of the Drawings

[0009] Fig. 1 is a schematic diagram illustrating an exemplary configuration of an inkjet printer according to the present embodiment; Fig. 2 is a block diagram illustrating a main part of a control system of the inkjet printer according to the present embodiment; Fig. 3 is a perspective view of an exemplary appearance of the inkjet head of Fig. 1; Fig. 4 is a cross-sectional diagram schematically illustrating an exemplary configuration of the head of Fig. 3 in a case where the head of Fig. 3 is cut along a plane perpendicular to the X axis; Fig. 5 is an exploded perspective diagram provided for describing the inner configuration of the head of Fig. 3; Fig. 6 is a perspective view of an exemplary appearance of a partition member of Fig. 4; Fig. 7 is an exploded perspective view of an exemplary configuration of the partition member of Fig. 6; Fig. 8 is a cross-sectional diagram schematically illustrating a cross section of the partition member of Fig. 6 obtained by cutting the partition member of Fig. 6 along a line segment A-A (a plane perpendicular to the X axis); Fig. 9 is a perspective view of the cross section of the partition member illustrated in Fig. 8 as viewed from the X-axis direction; Fig. 10 is a bottom view of the partition member when viewed from the bottom surface side; Fig. 11 is an enlarged view of a portion indicated by a reference sign C in Fig. 10 in an enlarged manner; Fig. 12 is a perspective view of the vicinity of the portion indicated by the reference sign C in Fig. 10 as viewed from the Z-axis direction; Fig. 13 is a partial cross-sectional diagram schematically illustrating a cross section of the partition member of Fig. 6 in a case where the partition member of Fig. 6 is cut along the line segment A-A (the plane perpendicular to the X axis) and a line segment B-B (a plane perpendicular to the Y axis); Fig. 14 is a cross-sectional diagram schematically illustrating a cross section of the partition member of Fig. 6 in a case where the partition member of Fig. 6 is cut along the line segment B-B (the plane perpendicular to the Y axis); Fig. 15 is a front view of the partition member of Fig. 6 when viewed from the front; and Fig. 16 is an enlarged view of a portion indicated by a reference sign D in Fig. 15 in an enlarged manner. Description of Embodiments

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the following embodiment, and various modifications can be made without departing from the spirit of the present disclosure. In addition, in each drawing, components denoted by the same reference signs are the same or equivalent components, which is common throughout the specification.

[0011] An embodiment of the present disclosure will be described with reference to the accompanying drawings. The image forming apparatus according to the present embodiment is, for example, an inkjet printer, and forms an image on a recording medium such as sheet by discharging droplets of ink onto the recording medium. Hereinafter, an inkjet printer, which is an exemplary image forming apparatus, will be described as an example.[Configuration of Inkjet Printer 100]

[0012] Fig. 1 is a schematic diagram illustrating an exemplary configuration of an inkjet printer 100 according to the present embodiment. Fig. 2 is a block diagram illustrating a main part of a control system of the inkjet printer 100 according to the present embodiment. As illustrated in Figs. 1 and 2, the inkjet printer 100 includes a conveyance unit 10, a supply unit 20, a discharge unit 30, an ink supply unit 40, an image forming unit 50, an image reading unit 60, an operation display unit 70, an input / output interface 80, and a control unit 90.

[0013] The conveyance unit 10 includes a plurality of members related to conveyance, such as a conveyance belt 11, a drive roller 12, and a driven roller 13. The conveyance unit 10 conveys a recording medium M through a conveyance operation of the plurality of members such as the conveyance belt 11. Specifically, in the conveyance unit 10, the conveyance belt 11 is stretched around the drive roller 12 and the driven roller 13, and is driven by rotationally driving the drive roller 12. Accordingly, the recording medium M supplied from the supply unit 20 is conveyed to the image forming unit 50 in a state of being placed on a conveyance surface 11a of the conveyance belt 11, an image is formed (printed) on the recording medium M at the image forming unit 50, and then the recording medium M is conveyed to the discharge unit 30.

[0014] As the recording medium M, it is possible to use various media on which ink discharged from an inkjet head 55 to be described below can be fixed. The recording medium M is, for example, a medium such as sheet-like paper, textile (fabric), or resin. Note that, the recording medium M is not limited to a sheet-like medium, but may be a medium such as roll-shaped paper, fabric, or resin.

[0015] Here, as an example, the conveyance unit 10 that conveys the recording medium M by the conveyance belt 11 is exemplified. However, the conveyance unit 10 may have a configuration in which the recording medium M is conveyed not only by the conveyance belt 11, but also by drums and rollers.

[0016] The supply unit 20 includes a supply load unit 21 and a supply conveyance unit 22. The supply load unit 21 loads and stores a plurality of recording media M. The supply conveyance unit 22 conveys and supplies the recording medium M from the supply load unit 21 to the conveyance unit 10. The supply load unit 21 is configured to be raisable and lowerable, and when the topmost recording medium M is conveyed to the conveyance unit 10 by the supply conveyance unit 22, the supply load unit 21 is raised such that the recording medium M that becomes, after the above-mentioned conveyance, the topmost recording medium M can be conveyed to the supply conveyance unit 22.

[0017] The discharge unit 30 includes a discharge load unit 31 and a discharge conveyance unit 32. The discharge load unit 31 loads and stores a plurality of recording media M. The discharge conveyance unit 32 conveys the recording medium M, which has been discharged from the conveyance unit 10, to the discharge load unit 31. The discharge load unit 31 is configured to be raisable and lowerable, and when the recording medium M is conveyed from the discharge conveyance unit 32 to the discharge load unit 31, the discharge load unit 31 is lowed.

[0018] The supply conveyance unit 22 and the discharge conveyance unit 32 include, for example, a plurality of rollers, and rotate the rollers to convey the recording medium M. The supply conveyance unit 22 and the discharge conveyance unit 32 may be formed of not only rollers, but also belts, and may also be configured by a combination of rollers and belts.

[0019] Note that, in a case where a roll-shaped medium is used as the recording medium M, an unwinding roller in which the roll-shaped medium is stored in a wound state is used instead of the supply load unit 21. In addition, a winding roller that winds a roll-shaped medium is used instead of the discharge load unit 31. The roll-shaped medium is conveyed to the conveyance unit 10 by rotating the unwinding roller, and is wound up around the winding roller by rotating the winding roller.

[0020] In addition, a post-processing apparatus that performs post-processing on the recording medium M on which an image has been formed by the image forming unit 50 may be provided between the conveyance unit 10 and the discharge unit 30. One example of the post-processing apparatus is a fixing apparatus that fixes ink on the recording medium M. For example, in a case where an ultraviolet curable ink is used as the ink, a fixing apparatus that fixes the ink on the recording medium M by irradiating the recording medium M with ultraviolet rays is used. In addition, for example, in a case where a water-based ink or a solvent ink is used as the ink, a fixing apparatus which fixes the ink on the recording medium M by a method such as drying is used. Further, as the post-processing apparatus, an apparatus other than a fixing apparatus, for example, a cutting apparatus that cuts the recording medium M into a desired length, or the like, may also be used.

[0021] The ink supply unit 40 is an apparatus that is connected to the image forming unit 50 via a flow path 42, which is an ink supply route, to supply ink to the image forming unit 50. In the present embodiment, the ink supply unit 40 is configured to supply inks of a plurality of colors to the image forming unit 50. In particular, in this example, the ink supply unit 40 is configured to supply inks of two colors to the image forming unit 50.

[0022] The ink supply unit 40 includes main tanks 41a and 41b, and members (not illustrated) related to the supply of ink (for example, a pump, a valve, and the like). The main tank 41a stores ink to be supplied to a first sub-tank 52a-1 at room temperature. The main tank 41b stores ink to be supplied to a first sub-tank 52a-2 at room temperature. The ink supply unit 40 supplies ink from the main tanks 41a and 41b to the first sub-tanks 52a-1 and 52a-2, respectively, via flow paths 42a and 42b by using a pump or the like (not illustrated).

[0023] The image forming unit 50 includes a carriage 51, the first sub-tanks 52a-1 and 52a-2, second sub-tanks 52b-1 and 52b-2, flow paths 53a-1, 53a-2, 53b-1, 53b-2, 53c-1, and 53c-2, a head drive unit 54, an inkjet head (hereinafter referred to as "head" as appropriate) 55, and the like.

[0024] Note that, the inkjet printer 100 according to the present embodiment causes the image forming unit 50 as a single body to discharge inks of two colors. For this reason, although the ink supply units 40 and the image forming units 50 for two colors are illustrated in Fig. 1 in order to simplify the drawing, the ink supply unit 40 and the image forming unit 50 are disposed according to the number of colors to be used. For example, in a case where four colors of yellow (Y), magenta (M), cyan (C), and black (K) are used, the ink supply units 40 and the image forming units 50 corresponding to the four colors are disposed, and the image forming units 50 are arranged so as to be side by side at predetermined intervals along a conveyance direction T.

[0025] In the present embodiment, in a case where a plurality of the ink supply units 40 and a plurality of the image forming units 50 are disposed, at least one ink supply unit 40 for two colors and at least one image forming unit 50 for the two colors may be disposed. In this case, for the remaining colors, for example, the ink supply unit(s) 40 for one color and the image forming unit(s) 50 for one color may be disposed.

[0026] Specifically, for example, in a case where the above-described four colors of YMCK are used, two ink supply units 40 corresponding to any two colors and two image forming units 50 corresponding to the two colors may be disposed. In addition, for example, one ink supply unit 40 corresponding to two colors and one image forming unit 50 corresponding to the two colors as well as two ink supply units 40 corresponding to one color and two image forming units 50 corresponding to the one color may be disposed.

[0027] In addition, a plurality of the second sub-tanks 52b-1 and 52b-2 and a plurality of the inkjet heads 55 are connected in a tree shape on the downstream side of the first sub-tanks 52a-1 and 52a-2 (illustration is omitted), but one of each is illustrated in Fig. 1 to simplify the drawing.

[0028] The carriage 51 is a housing that internally holds the first sub-tanks 52a-1 and 52a-2, the second sub-tanks 52b-1 and 52b-2, the flow paths 53a-1, 53a-2, 53b-1, 53b-2, 53c-1, and 53c-2, the head drive unit 54, the head 55, devices and members necessary for image formation, and the like.

[0029] The first sub tanks 52a-1 and 52a-2 are connected to the downstream side of the main tank 41. The first sub-tank 52a-1 stores the ink, which has been supplied from the main tank 41a, in the carriage 51. The ink in the first sub tank 52a-1 is supplied to the second sub tank 52b-1 via the flow path 53a-1, which is an ink supply route, by using a pump (not illustrated) or the like in the carriage 51.

[0030] The first sub-tank 52a-2 stores the ink, which has been supplied from the main tank 41b, in the carriage 51. The ink in the first sub tank 52a-2 is supplied to the second sub tank 52b-2 via the flow path 53a-2, which is an ink supply route, by using a pump (not illustrated) or the like in the carriage 51.

[0031] Although illustration is omitted, a plurality of the second sub-tanks 52b-1 is connected to the downstream side of the first sub-tank 52a-1. The second sub-tank 52b-1 stores the ink, which has been supplied from the first sub-tank 52a-1, in the carriage 51. The ink in the second sub-tank 52b-1 is supplied to a manifold 56a of the head 55, which will be described later, via the flow path 53b-1, which is an ink supply route, by using a pump or the like (not illustrated) in the carriage 51. In addition, the ink supplied to the manifold 56a is returned to the second sub-tank 53c-1 via the flow path 52b-1. That is, the flow paths 53b-1 and 53c-1 form a circulation flow path through which the ink circulates between the second sub-tank 52b-1 and the manifold 56a.

[0032] In addition, although illustration is omitted, a plurality of the second sub-tanks 52b-2 is connected to the downstream side of the first sub-tank 52a-2. The second sub-tank 52b-2 stores the ink, which has been supplied from the first sub-tank 52a-2, in the carriage 51. The ink in the second sub-tank 52b-2 is supplied to a manifold 56b of the head 55, which will be described later, via the flow path 53b-2, which is an ink supply route, by using a pump or the like (not illustrated) in the carriage 51. In addition, the ink supplied to the manifold 56b is returned to the second sub-tank 53c-2 via the flow path 52b-2. That is, the flow paths 53b-2 and 53c-2 form a circulation flow path through which the ink circulates the ink between the second sub-tank 52b-2 and the manifold 56b.

[0033] The head drive unit 54 outputs a drive voltage corresponding to image data of an image to be formed to a piezoelectric element 58 of the head 55, which will be described later, based on the control of the control unit 90 to be described later. The piezoelectric element 58 is driven by the drive voltage from the head drive unit 54 to cause ink in an amount corresponding to image data to be discharged from nozzles 59a and 59b of the head 55, which will be described later.

[0034] A plurality of the heads 55 is connected to the downstream sides of a plurality of the second sub-tanks 52b-1 and 52b-2, respectively. That is, although not illustrated, the plurality of second sub-tanks 52b-1 and 52b-2 and the plurality of heads 55 are connected in a tree shape to the downstream sides of the first sub-tanks 52a-1 and 52a-2.

[0035] The head 55 includes the manifolds 56a and 56b, individual supply flow paths 57a and 57b as a pressure chamber, the piezoelectric element 58, the nozzles 59a and 59b, and the like. The head 55 includes a plurality of the nozzles 59a and 59b, and the individual supply flow paths 57a and 57b, and the piezoelectric elements 58 are provided according to the number of nozzles 59a and 59b, respectively.

[0036] Note that, in the following description, the individual supply flow paths 57a and 57b may be simply referred to as the "individual supply flow path 57" in a case where it is not particularly necessary to distinguish therebetween. In addition, in the same manner for the nozzle 59, the nozzles 59a and 59b may be simply referred to as the "nozzle 59" in a case where it is not particularly necessary to distinguish therebetween.

[0037] The manifold 56a communicates with a plurality of individual supply flow paths 57a, and the ink that has been supplied to the manifold 56a is supplied to the individual supply flow paths 57a. The manifold 56b communicates with a plurality of individual supply flow paths 57b, and the ink that has been supplied to the manifold 56b is supplied to the individual supply flow paths 57b.

[0038] Each of the individual supply flow paths 57a and 57b is a space in which ink to be discharged is stored, and the piezoelectric element 58 is provided at a wall surface thereof. One end of the nozzle 59a communicates with the individual supply flow path 57a, and the other end thereof is an open end. In addition, one end of the nozzle 59b communicates with the individual supply flow path 57b, and the other end thereof is an open end.

[0039] A drive voltage from the head drive unit 54 is applied to the piezoelectric element 58. When the drive voltage from the head drive unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 is deformed according to the applied drive voltage, and the individual supply flow path 57 is deformed. Then, due to the deformation of the individual supply flow path 57, the pressure applied to the ink, which is in the individual supply flow path 57 and supplied to the nozzle 59, changes.

[0040] Accordingly, when the drive voltage from the head drive unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 and the individual supply flow path 57 are deformed, thereby making a pressure change in the ink in the individual supply flow path 57. As a result, the ink in the individual supply flow path 57 is discharged from the nozzle 59. In this way, by droplets of the ink being discharged from the nozzle 59, an image is formed on the recording medium M to be conveyed.

[0041] In the carriage 51, the head 55 may be configured to be of a single-pass (one pass) method in which image formation is performed by scanning once, or may be configured to be of a scanning (multi-pass) method in which image formation is performed by a plurality times of scanning. In the case of the single-pass method, the heads 55 in a number for the image formation width are disposed in the carriage 51 in the width direction of the recording medium M (the direction orthogonal to the conveyance direction T of the recording medium M).

[0042] The image reading unit 60 is disposed on the downstream side of the image forming unit 50 in the conveyance direction T of the recording medium M, and reads an image, such as a predetermined pattern image, formed on the recording medium M that is conveyed by the conveyance belt 11. The image reading unit 60 outputs a reading result of the predetermined pattern image to the control unit 90. The control unit 90 changes image forming conditions, for example, the image forming position, driving conditions of the head 55, and the like, based on the reading result.

[0043] In addition, although illustration is omitted, the inkjet printer 100 includes a maintenance unit which performs maintenance such as cleaning of the head 55.

[0044] The operation display unit 70 is, for example, a flat panel display such as a liquid crystal or organic electro luminescence (EL) display with a touch screen. The operation display unit 70 displays an operation menu for the user, information on image data, various states of the inkjet printer 100, and the like. In addition, the operation display unit 70 includes a plurality of keys and receives various input operations from the user.

[0045] The input / output interface 80 mediates transmission and reception of data exchanged between an external apparatus 200 and the control unit 90. The input / output interface 80 is constituted by, for example, various serial interfaces, various parallel interfaces, or a combination thereof.

[0046] The external apparatus 200 is, for example, a personal computer, a facsimile machine, or the like, and supplies a print job, image data, and the like to the control unit 90 via the input / output interface 80.

[0047] The control unit 90 includes a central processing unit (CPU) 91, a random access memory (RAM) 92, a read only memory (ROM) 93, and a storage unit 94.

[0048] The CPU 91 reads various control programs and setting data stored in the ROM 93, stores the read control programs and setting data in the RAM 92, and executes the programs to carry out various calculation processing. For example, the control unit 90 generates a drive signal for an image to be formed based on image data received from the input / output interface 80, and outputs the drive signal to the head 55.

[0049] The RAM 92 provides a working memory space for the CPU 91 and stores temporary data. Note that, the RAM 92 may include a non-volatile memory.

[0050] The ROM 93 stores various control program to be executed by the CPU 91, setting data, and the like. Note that, a rewritable non-volatile memory such as an electrically erasable programmable read only memory (EEPROM) or a flash memory may be used instead of the ROM 93.

[0051] The storage unit 94 stores print jobs and image data associated with the print jobs, which are input from the external apparatus 200 via the input / output interface 80. As the storage unit 94, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive (HDD) is used, and a dynamic random access memory (DRAM) or the like may also be used in combination.

[0052] The storage unit 94 stores print jobs and image data associated with the jobs, which are input from the external apparatus 200 via the input / output interface 80. As the storage unit 94, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive (HDD) is used, and a dynamic random access memory (DRAM) or the like may also be used in combination.

[0053] Each of the conveyance unit 10, the supply unit 20, the discharge unit 30, the ink supply unit 40, the image forming unit 50, the image reading unit 60, the operation display unit 70, the input / output interface 80, and the like is connected to the control unit 90. The control unit 90 integrally controls the entire operation of the inkjet printer 100. The conveyance unit 10, the supply unit 20, the discharge unit 30, the ink supply unit 40, the image forming unit 50, the image reading unit 60, the operation display unit 70, the input / output interface 80, and the like are controlled by the control unit 90 to execute predetermined processing.

[0054] Under the control of the control unit 90, the inkjet printer 100 having the above-described configuration feeds the recording medium M from the supply unit 20 to the conveyance unit 10, causes the image forming unit 50 to perform drawing on the recording medium M to be conveyed to the conveyance unit 10, and conveys the recording medium M, on which an image has been formed, to the discharge unit 30.[Configuration of Inkjet Head 55]

[0055] Next, the configuration of the head 55 will be described. The configuration to be described here is the configuration of the head 55 as a single body. Note that, the configurations of all of the heads 55 in the inkjet printer 100 may be the same, or the inkjet printer 100 may include a head 55 having a configuration different from the configuration described below.

[0056] Fig. 3 is a perspective view of an exemplary appearance of the inkjet head 55 of Fig. 1. In Fig. 3, in order to facilitate understanding of the configuration of the head 55, a hidden configuration is indicated by the broken lines. Note that, hereinafter, a description will be made on the assumption that the longitudinal direction of the head 55 is the X-axis direction, the shorter direction of the head 55 is the Y-axis direction, and the height direction of the head is the Z-axis direction. In addition, for each portion constituting the head 55, the surface on the upper side of the paper surface in the Z-axis direction may be referred to as the "upper surface", and the surface on the lower side of the paper surface in the Z-axis direction may be referred to as the "lower surface". The X-axis direction, the Z-axis direction, and the Y-axis direction correspond to the "first direction", the "second direction", and the "third direction" in the present disclosure, respectively.

[0057] As illustrated in Fig. 3, the head 55 includes a housing 101 and an exterior member 102 which is fitted to the housing 101 on the lower surface side of the housing 101. Inside the housing 101 and the exterior member 102, main constituent elements of the head 55 are housed.

[0058] An inlet 103 and an outlet 104 are disposed at the exterior member 102. Since inks of two colors are handled by the head 55 as a single body in the present embodiment, inlets 103a and 103b are included as the inlet 103, and outlets 104a and 104b are included as the outlet 104 in this example.

[0059] The inlets 103a and 103b are ink supply ports through which ink is supplied from the outside. Different inks of colors are supplied through the inlet 103a and the inlet 103b, respectively. The outlets 104a and 104b are ink discharge ports from which ink is discharged to the outside. Different inks of colors are discharged from the outlet 104a and the outlet 104b.

[0060] In addition, inside the exterior member 102, the manifold 56a connected to the inlet 103a and the manifold 56b connected to the inlet 103b are provided. Further, the exterior member 102 is provided with a plurality of attachment holes 105 for attaching the inkjet head 55 to the base portion of the carriage 51.(Inner Configuration of Inkjet Head 55)

[0061] Fig. 4 is a cross-sectional diagram schematically illustrating an exemplary configuration of the head 55 of Fig. 3 in a case where the head 55 of Fig. 3 is cut along a plane perpendicular to the X axis. Fig. 5 is an exploded perspective diagram provided for describing the inner configuration of the head 55 of Fig. 3. As illustrated in Figs. 4 and 5, the head 55 includes the manifold 56a and 56b, a head chip 110, a nozzle plate 120, and a partition member 130.(Nozzle Plate 120)

[0062] The nozzle plate 120 is formed in the shape of, for example, a flat plate, and is disposed on the lower surface side of the head chip 110 such that the plate surface of the nozzle plate 120 is orthogonal to the Z axis. At the nozzle plate 120, a plurality of nozzles 59 each of which is a hole penetrating the nozzle plate 120 in the Z-axis direction is formed so as to form a row along the X axis. Ink droplets are discharged to the outside in the Z-axis direction through the nozzles 59.(Head Chip 110)

[0063] The head chip 110 is configured to include an insulating member 111 and the piezoelectric element 58. The insulating member 111 is formed in the shape of, for example, a flat plate, and is disposed such that the plate surface of the insulating member 111 is orthogonal to the Z axis. In addition, the piezoelectric element 58 is disposed on the lower surface of the insulating member 111. Then, the nozzle plate 120 described above is disposed on the lower surface side of the piezoelectric element 58 of the head chip 110 formed as described above.

[0064] The insulating member 111 is a wiring board, and the flexible wiring 112 is connected thereto. The insulating member 111 is electrically connected to the head drive unit 54 via a flexible wiring 112, and receives a drive voltage signal from the head drive unit 54. In the insulating member 111, flow paths are formed each of which penetrates the insulating member 111 in the Z-axis direction. For example, glass is used as the insulating member 111.

[0065] At the piezoelectric element 58, a plurality of individual supply flow paths 57 each of which penetrates the piezoelectric element 58 in the Z-axis direction and communicates with the corresponding nozzle 59 is formed so as to form a row along the X axis. The piezoelectric element 58 is electrically connected to the head drive unit 54 by electrodes (not illustrated), the insulating member 111, and the flexible wiring 112.

[0066] The piezoelectric element 58 is driven in response to a driving voltage signal applied from the head drive unit 54 via the electrodes, the insulating member 111, and the flexible wiring, thereby repeatedly causing shear-mode type displacement at the partition wall of the individual supply flow path 57. Thus, the pressure in ink in the individual supply flow path 57 changes, and the ink is discharged from the nozzle 59 according to the pressure change. That is, the head 55 according to the present embodiment is an inkjet head that performs shear-mode type ink discharge.

[0067] The piezoelectric element 58 is, for example, a ceramic piezoelectric material (a member that is deformed in response to voltage application). As the piezoelectric material, for example, lead zirconate titanate (PZT), lithium niobate, barium titanate, lead titanate, lead metaniobate, or the like is used.(Partition Member 130)

[0068] The partition member 130 is disposed to divide the plurality of individual supply flow paths 57 in the head chip 110 in a plurality of regions in order to discharge inks of a plurality of colors from the head 55. The partition member 130 is bonded to the head chip 110 with an adhesive or by welding, for example. In a case where the partition member 130 and the head chip 110 are bonded to each other with an adhesive, for example, as the adhesive, an adhesive that is cured approximately at a temperature of 40°C to 60°C is used.

[0069] Fig. 6 is a perspective view of an exemplary appearance of the partition member 130 of Fig. 4. Fig. 7 is an exploded perspective view of an exemplary configuration of the partition member 130 of Fig. 6. Fig. 8 is a cross-sectional diagram schematically illustrating a cross section of the partition member 130 of Fig. 6 obtained by cutting the partition member 130 of Fig. 6 along a line segment A-A (a plane perpendicular to the X axis). Note that, in Fig. 8, in order to facilitate the description of the partition member 130, a state in which the partition member 130 is stacked on the head chip 110 is illustrated.

[0070] As illustrated in Fig. 6, the partition member 130 is formed in the shape of, for example, a flat plate. The partition member 130 includes common supply flow paths 131a and 131b. The common supply flow paths 131a and 131b are provided so as to communicate the manifolds 56a and 56b with the individual supply flow paths of the head chip 110. Inks of different colors circulate in the common supply flow path 131a and the common supply flow path 131b, respectively.

[0071] As illustrated in Fig. 7, the partition member 130 is formed, for example, by stacking a plurality of plate-shaped members formed in a flat plate shape. Specifically, the partition member 130 is configured by stacking a first plate-shaped member 133, a damper member 134, a second plate-shaped member 135, and a third plate-shaped member 136 in this order. The first plate-shaped member 133, the damper member 134, the second plate-shaped member 135, and the third plate-shaped member 136 are bonded, for example, by diffusion bonding or with an adhesive.

[0072] In the first plate-shaped member 133, first flow paths 1301a and 1301b, second flow paths 1302a and a 1302b, and a division unit 1330 are formed.

[0073] The first flow paths 1301a and 1301b penetrate the first plate-shaped member 133 in the Z-axis direction, respectively, and are formed so as to be along the both ends of the first plate-shaped member 133 in directions parallel to the X axis, respectively. The second flow paths 1302a and 1302b penetrate the first plate-shaped member 133 in the Z-axis direction, respectively, and are formed in directions parallel to the X axis of the first plate-shaped member 133 so as to be along the first flow paths 1301a and 1301b, respectively.

[0074] The division unit 1330 is provided for dividing flow paths through which inks of a plurality of colors handled by one head 55 circulate. That is, the division unit 1330 divides the plurality of nozzles 59 and the plurality of individual supply flow paths 57, which communicates with the plurality of nozzles 59 and individually supplies the ink, in a plurality of regions. In the present embodiment, the division unit 1330 divides a region including the plurality of nozzles 59 and the plurality of individual supply flow paths 57 into a first nozzle region including the nozzle 59a and the individual supply flow path 57a and a second nozzle region including the nozzle 59b and the individual supply flow path 57b.

[0075] The division unit 1330 is formed between the second flow path 1302a and the second flow path 1302b by forming the second flow paths 1302a and 1302b. The division unit 1330 is formed in the first plate-shaped member 133 in the X-axis direction in its entirety.

[0076] The damper member 134 is a plate-shaped member that functions as a damper that attenuates a pressure change in ink that occurs when the ink is discharged, and suppresses adverse effects on the ink discharge from other nozzle 59. In the damper member 134, third flow paths 1303a and 1303b are formed. The third flow path 1303a and 1303b penetrate the damper member 134 in the Z-axis direction, respectively, and are formed so as to be along the both ends of the damper member 134 in directions parallel to the X axis, respectively. When the damper member 134 is stacked on the first plate-shaped member 133, the damper member 134 shields the openings on the upper surface sides of the second flow paths 1302a and 1302b of the first plate-shaped member 133.

[0077] In the second plate-shaped member 135, fourth flow paths 1304a and 1304b and fifth flow paths 1305a and 1305b are formed. The fourth flow paths 1304a and 1304b penetrate the second plate-shaped member 135 in the Z-axis direction, respectively, and are formed so as to be along the both ends of the second plate-shaped member 135 in directions parallel to the X axis, respectively. The fifth flow paths 1305a and 1305b penetrate the second plate-shaped member 135 in the Z-axis direction, respectively, and are formed in directions parallel to the X-axis of the second plate-shaped member 135 so as to be along the fourth flow paths 1304a and 1304b.

[0078] When the second plate-shaped member 135 is stacked on the damper member 134, the openings of the fifth flow paths 1305a and 1305b on the lower surface sides thereof are shielded by the damper member 134. Thus, air chambers 1350a and 1350b, which are sealed spaces, are formed between the second plate-shaped member 135 and the damper member 134.

[0079] In the third plate-shaped member 136, sixth flow paths 1306a and 1306b are formed. The sixth flow paths 1306a and 1306b penetrate the third plate-shaped member 136 in the Z-axis direction, respectively, and are formed so as to be along the both ends of the third plate-shaped member 136 in directions parallel to the X-axis, respectively.

[0080] When the respective members are stacked in the partition member 130, the first flow path 1301a, the third flow path 1303a, the fourth flow path 1304a, and the sixth flow path 1306a are connected to and communicate with each other, and thus, a common supply flow path 131a is formed in the partition member 130. In addition, in the partition member 130, the first flow path 1301b, the third flow path 1303b, the fourth flow path 1304b, and the sixth flow path 1306b are connected to and communicate with each other, and thus a common supply flow path 131b is formed in the partition member 130.

[0081] Here, in the head 55 having the above-described configuration, the nozzle 59a and the nozzle 59b are formed such that the center-to-center distance between the nozzle 59a and the nozzle 59b (see Fig. 4) is equal to or less than 5 mm. The center-to-center distance is the distance between the nozzle 59a and the nozzle 59b disposed on the innermost sides in the Y-axis direction, with the division unit 1330 of the partition member 130 as the center.[Structure of Partition Member 130]

[0082] Next, a specific structure of the partition member 130 will be described.(Stepped Portion 1331)

[0083] Fig. 9 is a perspective view of the cross section of the partition member 130 illustrated in Fig. 8 as viewed from the X-axis direction. As illustrated in Fig. 9, a stepped portion 1331 including a first stepped portion 1331a and a second stepped portion 1331b is formed at the division unit 1330 formed in the first plate-shaped member 133 of the partition member 130.

[0084] The first stepped portion 1331a is a stepped portion formed on the upper surface side of the first plate-shaped member 133 at the division unit 1330. The second stepped portion 1331b is a stepped portion formed so as to protrude from the first stepped portion 1331a toward the lower surface side of the first plate-shaped member 133. The second stepped portion 1331b is formed such that in the cross-sectional shape of the division unit 1330 in a case where the division unit 1330 is cut along a plane perpendicular to the X axis, the length of the side of the second stepped portion 1331b in the Y-axis direction is shorter than the length of the side of the first stepped portion 1331a in the Y-axis direction.

[0085] That is, the stepped portion 1331 is formed such that in the cross-sectional shape of the division unit 1330 in a case where the division unit 1330 is cut along the plane perpendicular to the X axis, the length of the side of the stepped portion 1331 in the Y-axis direction is shorter stepwise from the upper surface side of the first plate-shaped member 133 toward the lower surface side of the first plate-shaped member 133. By forming the stepped portion 1331 at the division unit 1330 in the above-described manner, it is possible to suppress the spread of an adhesive to the flow path side due to the surface tension of the stepped portion 1331 when the partition member 130 and the head chip 110 are bonded to each other with the adhesive.

[0086] Note that, in this example, the sides of the second stepped portion 1331b in the up-down direction in the cross section of the division unit 1330 in a case where the division unit 1330 is cut along the plane perpendicular to the X axis are formed in directions parallel to the Z-axis, but the present disclosure is not limited thereto, and for example, the sides of the second stepped portion 1331b in the up-down direction in the cross section of the division unit 1330 in a case where the division unit 1330 is cut along the plane perpendicular to the X axis may also be formed, for example, in a tapered shape from the upper surface side toward the lower surface side.(Outflow Suppression Unit 1332)

[0087] Fig. 10 is a bottom view of the partition member 130 when viewed from a bottom surface side. Fig. 11 is an enlarged view of a portion indicated by a reference sign C in Fig. 10 in an enlarged manner. Fig. 12 is a perspective view of the vicinity of the portion indicated by reference sign C in Fig. 10 as viewed from the Z-axis direction. As illustrated in Figs. 10 to 12, outflow suppression units 1332 are formed on the bottom surface of the partition member 130 (the first plate-shaped member 133).

[0088] The outflow suppression unit 1332 is a partition which is on a bonding surface when the head chip 110 and the partition member 130 are bonded to each other and suppresses an outflow of an adhesive to a flow path. In regions of the first plate-shaped member 133 in the X-axis direction where the first flow paths 1301a and 1301b and the second flow paths 1302a and 1302b are not formed, the outflow suppression units 1332 are formed on the outer periphery of the division unit 1330 with a predetermined gap between the outflow suppression units 1332. In addition, the outflow suppression units 1332 are also formed with a predetermined gap therebetween from the both ends of the first plate-shaped member 133 in directions parallel to the X-axis direction to the inner sides thereof in the Y-axis direction.

[0089] An adhesive is applied to this gap when the head chip 110 and the partition member 130 are bonded to each other, and the formation of the outflow suppression unit 1332 in this manner makes it possible to suppress an outflow of the adhesive into a space that serves as an ink flow path.(Beam 1333 and Strut 1334)

[0090] Fig. 13 is a partial cross-sectional diagram schematically illustrating a cross section of the partition member 130 in a case where the partition member 130 of Fig. 6 is cut along the line segment A-A (the plane perpendicular to the X axis) and a line segment B-B (a plane perpendicular to the Y axis). As illustrated in Figs. 10 and 13, a beam 1333 and a strut 1334 are formed on the bottom surface of the partition member 130 (the first plate-shaped member 133).

[0091] The beams 1333 are formed to extend in the X-axis direction between the first flow path 1301a and the second flow path 1302a and between the first flow path 1301b and the second flow path 1302b in the first plate-shaped member 133. That is, the beams 1333 is formed on the inner sides of the common supply flow paths 131a and 131b in the Y-axis direction. In addition, the beam 1333 is formed so as to protrude entirely downward in the Z-axis direction. The height of the beam 1333 (the length thereof in the Z-axis direction) is shorter than the length between the bottom surface of the first plate-shaped member 133 and the upper surface of the head chip 110 (the insulating member 111) when the head chip 110 and the partition member 130 are bonded to each other.

[0092] The struts 1334 are formed side by side at predetermined intervals in the X-axis direction so as to protrude downward in the Z-axis direction from the beams 1333. The height of the strut 1334 (the length thereof in the Z-axis direction) is such a height that the strut 1334 comes into contact with the head chip 110 when the partition member 130 and the head chip 110 are bonded to each other.

[0093] By forming the beams 1333 and the struts 1334 in this manner, it is possible to appropriately support the partition member 130 when the head chip 110 and the partition member 130 are bonded to each other. In addition, by forming the beams 1333 and the struts 1334 on the inner sides of the common supply flow paths 131a and 131b in the Y-axis direction, it is possible to appropriately support the damper member 134 which is held between the first plate-shaped member 133 and the second plate-shaped member 135 when the partition member 130 is manufactured by bonding each member.(Bonding of Each Member in Partition Member 130)

[0094] Fig. 14 is a cross-sectional diagram schematically illustrating a cross section of the partition member 130 of Fig. 6 in a case where the partition member 130 of Fig. 6 is cut along the line segment B-B (the plane perpendicular to the Y axis). As illustrated in Fig. 14, an adhesive is applied to the inner periphery surfaces of the common supply flow paths 131a and 131b in the partition member 130. At this time, the adhesive is preferably applied to, of the inner periphery surfaces of the common supply flow paths 131a and 131b, surfaces that extend in the X-axis direction and are on the inner side of the partition member 130 in the Y-axis direction.

[0095] In this way, the adhesive is applied to the inner periphery surfaces of the common supply flow paths 131a and 131b, thereby reinforcing the bonding of each member constituting the partition member 130. For this reason, each member can be bonded more reliably.(Hole Portions 132a and 132b)

[0096] Fig. 15 is a front view of the partition member 130 of Fig. 6 when viewed from the front. Fig. 16 is an enlarged view of a portion indicated by a reference sign D in Fig. 15 in an enlarged manner. As illustrated in Figs. 6, 15, and 16, hole portions 132a and 132b penetrating the partition member 130 (the third plate-shaped member 136) in the Z-axis direction are formed in the partition member 130 (the third plate-shaped member 136). The hole portion 132a is provided so as to communicate the air chamber 1350a formed inside the partition member 130 with the outside. In addition, the hole portion 132b is provided so as to communicate the air chamber 1350b with the outside.

[0097] The hole portions 132a and 132b are filled, for example, by bonding, welding, taping, or the like when the head 55 is manufactured. Thus, the air chambers 1350a and 1350b that have been sealed are formed in the partition member 130.

[0098] Here, in a case where the hole portions 132a and 132b are filled, it is necessary to prevent an adhesive or the like from falling into the air chamber 1350a and 1350b. For this reason, it is preferable that the hole portions 132a and 132b be formed in consideration of the viscosity of the adhesive or the like such that the hole portions 132a and 132b have, for example, a diameter (hole diameter) equal to or less than 0.6 mm.

[0099] In addition, when the heights of the air chambers 1350a and 1350b (the lengths thereof in the Z-axis direction) are not constant in a nozzle region which is a region in which the respective nozzles 59a and 59b are formed, the damper function by the damper sheet 134 does not appropriately function. For this reason, it is preferable that the hole portions 132a and 132b be formed at positions deviated from the nozzle region in the X-axis direction such that the damper function appropriately functions even in a case where the heights of the air chambers 1350a and 1350b are not constant when the hole portions 132a and 132b are filled.

[0100] As described above, the head 55 according to the present embodiment includes: the head chip 110 including the piezoelectric element 58 of a shear-mode type; and the partition member 130 having a damper function in which the division unit 1330 that divides the plurality of nozzles 59 in a plurality of regions is formed. In the head 55 as such, an ink flow path in the head chip 110 is divided into a plurality of regions by the partition member 130. For this reason, inks of a plurality of colors can be handled by one head chip 110. Accordingly, the head 55 according to the present embodiment is capable of discharging inks of a plurality of colors without an increase in head size.

[0101] The disclosure of Japanese Patent Application Laid-Open No. 2023-088571, filed on May 30, 2023 including the specification, drawings and abstract, is incorporated herein by reference in its entirety.Reference Signs List

[0102] 10 Conveyance unit 20 Supply unit 30 Discharge unit 40 Ink supply unit 50 Image forming unit 55 Inkjet head 56a, 56b Manifold 57, 57a, 57b Individual supply flow path 58 Piezoelectric element 59, 59a, 59b Nozzle 100 Inkjet printer 101 Housing 102 Exterior member 103, 103a, 103b Inlet 104, 104a, 104b Outlet 105 Attachment hole 110 Head chip 111 Insulating member 112 Flexible wiring 120 Nozzle plate 130 Partition member 131a, 131b Common supply flow path 132a, 132b Hole portion 133 First plate-shaped member 134 Damper member 135 Second plate-shaped member 136 Third plate-shaped member 1301a, 1301b First flow path 1302a, 1302b Second flow path 1303a, 1303b Third flow path 1304a, 1304b Fourth flow path 1305a, 1305b Fifth flow path 1306a, 1306b Sixth flow path 1330 Division unit 1331 Stepped portion 1331a First stepped portion 1331b Second stepped portion 1332 Outflow suppression unit 1333 Beam 1334 Strut 1350a, 1350b Air chamber

Claims

1. An inkjet head, comprising: a head chip that includes: a plurality of individual supply flow paths formed in the head chip; and a shear-mode type piezoelectric element, the plurality of individual supply flow paths individually supplying ink to a plurality of nozzles, the shear-mode type piezoelectric element changing pressure in the plurality of individual supply flow paths; and a partition member having a damper function, the partition member being a partition member in which a common supply flow path and a division unit are formed, the common supply flow path being a common supply flow path which communicates with the plurality of individual supply flow paths and through which the ink circulates, the division unit dividing the plurality of individual supply flow paths and the plurality of nozzles in a plurality of regions.

2. The inkjet head according to claim 1, wherein the division unit includes a stepped portion having a side in a cross-sectional shape of the division unit in a case where the division unit is cut along a plane perpendicular to a first direction, the side being a side in a third direction perpendicular to the first direction and a second direction and having a length that is shorter stepwise from an upper side in the second direction toward a lower side in the second direction, the second direction being a vertical direction perpendicular to the first direction.

3. The inkjet head according to claim 2, wherein the stepped portion is formed in a tapered shape from the upper side in the second direction toward the lower side in the second direction.

4. The inkjet head according to claim 1, wherein the partition member includes an outflow suppression unit formed on a bonding surface when the partition member and the head chip are bonded to each other, the outflow suppression unit suppressing an outflow of an adhesive to a flow path.

5. The inkjet head according to claim 4, wherein a plurality of the outflow suppression units is formed on an outer periphery of the division unit with a predetermined gap between the plurality of outflow suppression units.

6. The inkjet head according to claim 1, wherein: the partition member includes a beam formed in the partition member, the beam extending in a first direction and protruding downward in a second direction which is a vertical direction perpendicular to the first direction, and a strut formed in the partition member, the strut protruding downward in the second direction from the beam.

7. The inkjet head according to claim 6, wherein the beam is formed on an inner side of the common supply flow path in a third direction perpendicular to the first direction and the second direction.

8. The inkjet head according to claim 1, wherein the common supply flow path of the partition member includes an inner periphery surface to which an adhesive is applied.

9. The inkjet head according to claim 1, wherein: the partition member includes a plurality of plate-shaped members and a damper member, the plurality of plate-shaped members and the damper member being stacked, the damper member being disposed so as to be held between the plurality of plate-shaped members, and a hole portion formed at an upper surface of the partition member in a second direction, the hole portion communicating with an air chamber formed by the damper member and the plurality of plate-shaped members, the second direction being a vertical direction.

10. The inkjet head according to claim 9, wherein the hole portion is formed, in a third direction perpendicular to the second direction, at a position deviated from the plurality of regions in which the plurality of nozzles is formed.

11. The inkjet head according to claim 9, wherein the hole portion has a diameter equal to or less than 0.6 mm.

12. The inkjet head according to claim 1, wherein: the partition member is formed by stacking a plurality of plate-shaped members and a damper member, the damper member being disposed so as to be held between the plurality of plate-shaped members, and the plurality of plate-shaped members and the damper member are bonded by diffusion bonding.

13. The inkjet head according to claim 1, wherein: the partition member is formed by stacking a plurality of plate-shaped members and a damper member, the damper member being disposed so as to be held between the plurality of plate-shaped members, and the plurality of plate-shaped members and the damper member are bonded with an adhesive.

14. The inkjet head according to claim 1, wherein in a third direction perpendicular to a first direction and a second direction, a distance between a nozzle, which is among the plurality of nozzles, is in one region among the plurality of divided regions, and is closest to another region among the plurality of divided region, and a nozzle, which is among the plurality of nozzles, is in the other region, and is closest to the one region, is equal to or less than 5 mm, the second direction being a vertical direction perpendicular to the first direction.

15. The inkjet head according to claim 1, wherein the head chip and the partition member are bonded to each other with an adhesive that is cured at 40°C to 60°C.

16. An image forming apparatus, comprising the inkjet head according to claim 1.

Images