Head unit and inkjet recording device equipped with same

Abstract

To provide a head unit configured such that a plurality of recording heads can be replaced individually and positions of the recording heads can be adjusted easily, and an inkjet recording device.SOLUTION: The head unit comprises recording heads, a head-side frame, a unit frame, a first head mount member, a second had mount member, a head angle adjustment mechanism, and an energizing member. The unit frame holds the recording heads at both side surfaces of a main frame in a flat plane shape standing along a width direction that is orthogonal to a conveying direction of a recording medium. The energizing member energizes the first head mount member or the second head mount member toward the main frame. The relationship between pressing force acting on the head-side frame from the energizing member and reaction of pressing force applied to the first head mount member or the second head mount member from the energizing member is established between the first head mount member or the second head mount member and the head-side frame.SELECTED DRAWING: Figure 18

Description

[Technical field]

[0001] The present invention relates to a head unit mounted on an inkjet recording apparatus and an inkjet recording apparatus equipped with the same, and more particularly to a mounting structure for a recording head to the head unit. [Background technology]

[0002] A head unit mounted on an inkjet recording device includes a recording head having multiple nozzles that eject ink onto a recording medium such as paper, and records an image on the recording medium. In a so-called line head type printer in which the recording head is arranged so that the ink ejection nozzles are arranged across the entire width of the recording medium, a head unit in which multiple recording heads are unitized for each color is used.

[0003] For example, Patent Documents 1 and 2 disclose a head assembly (head unit) of an inkjet recording device that includes three recording heads connected to a base member of the head assembly by using a connecting member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-121514 A [Patent Document 2] JP 2020-116844 A Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, when a malfunction occurs while a user is using an inkjet recording device and it becomes necessary to replace the recording head, it is difficult to replace only the malfunctioning recording head, even though in most cases only one recording head in the head unit malfunctions. Therefore, there is a problem that the entire head unit must be replaced, which incurs extra costs. In addition, it is necessary to easily and reliably adjust the position of each recording head relative to the unit frame that holds the recording heads.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above problems, an object of the present invention is to provide a head unit and an inkjet recording apparatus in which a plurality of recording heads can be individually replaced and in which the positions of the recording heads relative to the unit frame can be easily adjusted. [Means for solving the problem]

[0007] In order to solve the above problems, the first configuration of the present invention is a head unit including a recording head, a head side frame, a unit frame, a first head mounting member, a second head mounting member, a head angle adjustment mechanism, and a biasing member. The recording head has a plurality of nozzles that eject ink onto a recording medium. The head side frame constitutes the recording head. The unit frame holds one or more recording heads on each of both sides of a flat main frame that stands along a width direction perpendicular to the conveying direction of the recording medium. The first head mounting member is fixed to the main frame and has a support shaft that swingably supports one end of the head side frame in the width direction. The second head mounting member is fixed to the main frame and supports the other end of the head side frame in the width direction. The head angle adjustment mechanism adjusts the horizontal angle of the recording head relative to the unit frame by changing the horizontal position of the head side frame relative to the second head mounting member. The biasing member is disposed between the head side frame and the first head mounting member and the second head mounting member, and biases the first head mounting member or the second head mounting member toward the main frame. The relationship between the pressing force acting on the head side frame from the biasing member and the force applied from the biasing member to the first head mount member or the second head mount member as a reaction to the pressing force is completed between the first head mount member or the second head mount member and the head side frame. Effect of the Invention

[0008] According to the first configuration of the present invention, by using unit frames holding one or more recording heads on each side of a flat main frame standing along a width direction perpendicular to the transport direction of the recording medium, it is possible to easily replace only the recording head that needs to be replaced. Also, a biasing member is provided to position the head-side frame relative to the first head mount member and the second head mount member, and the relationship between the pressing force acting on the head-side frame from the biasing member and the force applied from the biasing member to the first head mount member or the second head mount member as a reaction to the pressing force is completed between the first head mount member or the second head mount member and the head-side frame, so distortion of the main frame can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a printer as an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 2] Plan view of the recording unit of the printer [Diagram 3] A side view of a recording head constituting a line head of a recording unit. [Figure 4] A plan view of the recording head as seen from the ink ejection surface side. [Diagram 5] Plan cross-sectional view of the head unit seen from above [Figure 6] FIG. 3 is a perspective view of a unit frame that constitutes the head unit; [Figure 7] A perspective view of a main frame constituting the unit frame. [Figure 8] FIG. 13 is a perspective view of a first reinforcing member that constitutes the unit frame; [Figure 9] FIG. 13 is a perspective view of a second reinforcing member that constitutes the unit frame; [Figure 10] FIG. 13 is a perspective view showing a state in which a first reinforcing member is attached to a bending portion on the rotation fulcrum side of the main frame; [Figure 11] FIG. 13 is a perspective view showing a state in which a first reinforcing member is attached to a bent portion on a rotation end side of the main frame; [Figure 12]FIG. 2 is a plan view showing the configuration of the engagement portion between the rotation support side of the unit frame and the main body frame of the printer, viewed from above. [Figure 13] FIG. 13 is a perspective view showing the configuration of a unit angle adjustment section provided on the rotation end side of the unit frame; [Figure 14] FIG. 3 is a perspective view of a head-side frame constituting a recording head; [Figure 15] Partially enlarged view of the bottom of the end of the head frame on the side of the pivot point [Figure 16] FIG. 13 is a perspective view of a first head mount member disposed on the rotation fulcrum side of the head-side frame; [Figure 17] FIG. 13 is a perspective view showing a configuration of a connecting portion between the rotation fulcrum side of the head side frame and the unit frame. [Figure 18] A side cross-sectional view of the connection between the rotation support point side of the head side frame and the unit frame, taken in a direction perpendicular to the longitudinal direction. [Figure 19] FIG. 13 is a perspective view of a second head mount member disposed on the rotation end side of the head-side frame; [Figure 20] FIG. 13 is a perspective view showing a state in which a leaf spring is attached to a second head mount member disposed on the rotation end side of the head-side frame; [Figure 21] FIG. 13 is a perspective view showing a configuration of a connecting portion between the rotation fulcrum side of the head side frame and the unit frame. [Figure 22] FIG. 1 is a side cross-sectional view of a connecting portion between the rotating end side of the head side frame and the unit frame, taken in a direction perpendicular to the longitudinal direction, and including a head angle adjustment mechanism. [Diagram 23] FIG. 1 is a side cross-sectional view of a connecting portion between the rotating end side of the head side frame and the unit frame, taken in a direction perpendicular to the longitudinal direction, and including a leaf spring. [Figure 24] A side cross-sectional view of the connection portion between the rotating end side of the head side frame and the unit frame taken along the longitudinal direction. [Diagram 25] FIG. 11 is a perspective view showing a connection state between the rotation end side of the head side frame and the second head mount member; [Figure 26] FIG. 13 is a perspective view showing a state in which a sliding plate is attached to a sliding portion of a second head mount member; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram showing the general configuration of a printer 100 as an inkjet recording device according to one embodiment of the present invention. The printer 100 is equipped with a paper feed cassette 2 which is a paper storage section. The paper feed cassette 2 is located at the bottom inside the printer main body 1. Inside the paper feed cassette 2, paper P, which is an example of a recording medium, is stored.

[0011] A paper feeder 3 is disposed downstream of the paper feed cassette 2 in the paper transport direction, i.e., above the right side of the paper feed cassette 2 in Fig. 1. The paper feeder 3 separates and sends out the paper P one by one toward the upper right of the paper feed cassette 2 in Fig. 1.

[0012] The printer 100 has a first paper transport path 4a inside. The first paper transport path 4a is located in the upper right corner, which is the paper feed direction, of the paper feed cassette 2. The paper P sent out from the paper feed cassette 2 is transported vertically upward along the side of the printer body 1 by the first paper transport path 4a.

[0013] A pair of registration rollers 13 is provided at the downstream end of the first paper transport path 4a in the paper transport direction. Furthermore, a first transport unit 5 and a recording unit 9 are arranged immediately downstream in the paper transport direction of the pair of registration rollers 13. The paper P sent out from the paper feed cassette 2 reaches the pair of registration rollers 13 through the first paper transport path 4a. The pair of registration rollers 13 corrects skewed feed of the paper P and sends the paper P toward the first transport unit 5 (particularly the first transport belt 8 described later) in time with the ink ejection operation performed by the recording unit 9.

[0014] The paper P sent to the first transport unit 5 by the pair of registration rollers 13 is transported by the first transport belt 8 to a position facing the recording unit 9 (particularly recording heads 17a to 17c described below). An image is recorded on the paper P by ejecting ink from the recording unit 9 onto the paper P. At this time, the ejection of ink from the recording unit 9 is controlled by a control device 120 inside the printer 100.

[0015] In the paper transport direction, a second transport unit 12 is disposed downstream of the first transport unit 5 (on the left side in FIG. 1). The paper P on which an image has been recorded by the recording unit 9 is sent to the second transport unit 12. The ink ejected onto the surface of the paper P is dried while passing through the second transport unit 12.

[0016] In the paper transport direction, a decurler unit 14 is provided downstream of the second transport unit 12 and near the left side surface of the printer body 1. The paper P from which the ink has been dried by the second transport unit 12 is sent to the decurler unit 14, where any curls in the paper P are straightened out.

[0017] In the paper transport direction, a second paper transport path 4b is provided downstream of the decurler unit 14 (upper in FIG. 1). If double-sided recording is not performed, the paper P that has passed through the decurler unit 14 passes through the second paper transport path 4b and is discharged to a paper discharge tray 15a provided outside the left side of the printer 100. A sub-discharge tray 15b is provided below the paper discharge tray 15a to discharge unnecessary paper P (broken paper) that has experienced printing defects or the like.

[0018] A reversing transport path 16 for double-sided recording is provided at the top of the printer body 1, above the recording unit 9 and the second transport unit 12. When double-sided recording is performed, after recording on one side (first side) of the paper P is completed and the paper P passes through the second transport unit 12 and the decurler unit 14, it is sent to the reversing transport path 16 via the second paper transport path 4b.

[0019] After being sent to the reversing transport path 16, the transport direction of the paper P is then switched so that recording can be performed on the other side (second side) of the paper P. The paper P then passes over the top of the printer body 1 and is transported to the right side, passes through the pair of registration rollers 13, and is sent again to the first transport unit 5 with the second side facing up. In the first transport unit 5, the paper P is transported to a position facing the recording section 9, and an image is recorded on the second side by ink ejection from the recording section 9. After double-sided recording, the paper P passes through the second transport unit 12, the decurler section 14, and the second paper transport path 4b in that order, and is discharged to the paper discharge tray 15a.

[0020] In addition, a maintenance unit 19 and a cap unit 20 are disposed below the second transport unit 12. The maintenance unit 19 moves horizontally below the recording unit 9 when performing purging, wipes off ink extruded from the ink ejection ports of the recording head, and collects the wiped ink. Purging refers to the operation of forcibly pushing out ink from the ink ejection ports of the recording head in order to expel thickened ink, foreign matter, and air bubbles from the ink ejection ports. The cap unit 20 moves horizontally below the recording unit 9 when capping the ink ejection surface of the recording head, and then moves further upward to be attached to the underside of the recording head.

[0021] 2 is a plan view of the recording unit 9. The recording unit 9 includes a head housing 10 and line heads 11Y, 11M, 11C, and 11K. The line heads 11Y to 11K are held in the head housing 10 at a height that forms a predetermined gap (for example, 1 mm) with respect to the conveying surface of an endless first conveyor belt 8 that is stretched around a plurality of rollers including a drive roller 6a, a driven roller 6b, and a tension roller (not shown). The drive roller 6a drives the first conveyor belt 8 in the conveying direction of the paper P (the direction of the arrow A).

[0022] Each of the line heads 11Y to 11K has a plurality of (three in this example) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered pattern along the paper width direction (arrow BB' direction) perpendicular to the paper transport direction (arrow A direction). The recording heads 17a to 17c have a plurality of ink ejection openings 18 (nozzles). The ink ejection openings 18 are arranged at equal intervals in the width direction of the recording head, that is, the paper width direction (arrow BB' direction). From the line heads 11Y to 11K, inks of yellow (Y), magenta (M), cyan (C), and black (K) are ejected toward the paper P transported by the first transport belt 8 through the ink ejection openings 18 of the recording heads 17a to 17c.

[0023] Fig. 3 is a side view of the recording heads 17a to 17c constituting the line heads 11Y to 11K of the recording unit 9, and Fig. 4 is a plan view of the recording heads 17a to 17c as viewed from the ink ejection surface F1 side. Since the recording heads 17a to 17c have the same shape and configuration, Figs. 3 and 4 show the recording heads 17a to 17c in a single drawing. As shown in Figs. 3 and 4, the ink ejection surface (nozzle surface) F1 of the recording heads 17a to 17c is provided with a plurality of nozzle regions Ra to Rd (four blocks in this case) in which a large number of ink ejection ports 18 (see Fig. 2) are arranged. The ink ejection surface F1 is formed of, for example, SUS (stainless steel).

[0024] The recording heads 17a to 17c constituting each of the line heads 11C to 11K are supplied with four colors (cyan, magenta, yellow, and black) of ink for each of the line heads 11C to 11K from a liquid supply mechanism (not shown).

[0025] Each of the recording heads 17a to 17c ejects ink from an ink ejection port 18 toward the paper P, which is adsorbed and held on the conveying surface of the first conveyor belt 8 and conveyed, in response to a control signal from a control device 120 (see FIG. 1) and image data received from an external computer. As a result, a color image is formed on the paper P on the first conveyor belt 8 by overlapping four colors of ink: cyan, magenta, yellow, and black. In addition, a cleaning liquid supply unit 30 that supplies cleaning liquid is provided at one end of the recording heads 17a to 17c in the longitudinal direction (arrow BB' direction) perpendicular to the paper conveying direction (arrow A direction). The cleaning liquid supply unit 30 has a number of cleaning liquid supply ports 30a formed therein.

[0026] In the printer 100, when printing starts after a long period of inactivity and between printing operations, in order to clean the ink ejection surfaces F1 of the recording heads 17a to 17c, ink is extruded (purged) from the ink ejection ports 18 of all of the recording heads 17a to 17c, cleaning liquid is supplied from the cleaning liquid supply port 30a to the cleaning liquid supply surface F2, and a recovery operation of the recording heads 17a to 17c is performed in which the ink ejected onto the ink ejection surface F1 is wiped off together with the cleaning liquid by a wiper (not shown) in preparation for the next printing operation. The ink and cleaning liquid wiped off from the ink ejection surface F1 are collected by an ink receiver (not shown).

[0027] Next, the configuration of the head unit 51 of the printer 100 will be described. Fig. 5 is a plan cross-sectional view of the head unit 51 as viewed from above. Fig. 6 is a perspective view of a unit frame 52 that constitutes the head unit 51. Fig. 7 is a perspective view of a main frame 53 that constitutes the unit frame 52. The head unit 51 includes recording heads 17a to 17c and a unit frame 52 that holds the recording heads 17a to 17c in a detachable manner.

[0028] The recording heads 17a to 17c are arranged in a staggered pattern along the paper width direction (arrow BB' direction) on both side surfaces of the unit frame 52. More specifically, the recording heads 17a and 17c are held on the upstream side of the unit frame 52 with respect to the paper transport direction (arrow A direction), and the recording head 17b is held on the downstream side.

[0029] The unit frame 52 has a main frame 53, a first reinforcing member 55, and a second reinforcing member 57. As shown in FIG. 7, the main frame 53 has a flat body portion 53a extending in the up-down direction and the paper width direction and facing the side surfaces of the recording heads 17a to 17c, and bent portions 53b formed by bending both ends of the body portion 53a in the paper width direction at a right angle. A first head mount member 80a and a second head mount member 80b that support the recording heads 17a to 17c are fixed to the body portion 53a at predetermined positions. The first head mount member 80a and the second head mount member 80b are aluminum blocks formed by aluminum die casting.

[0030] The first head mount member 80a has a support shaft boss 81 (see FIG. 16) that supports one longitudinal end (the end in the direction of arrow B') of each of the recording heads 17a to 17c so that the recording heads 17a to 17c can rotate in the horizontal direction. The support structure of the first head mount member 80a for the recording heads 17a to 17c will be described later.

[0031] The second head mount member 80b supports the other longitudinal end (end in the direction of arrow B) of each of the recording heads 17a to 17c. The head angle adjustment mechanism 60 adjusts the horizontal angles (alignment adjustment) of each of the recording heads 17a to 17c relative to the unit frame 52 by moving the ends (ends in the direction of arrow B) of the recording heads 17a to 17c in the directions Ra or Rb relative to the unit frame 52. The detailed configuration of the head angle adjustment mechanism 60 will be described later.

[0032] Furthermore, one end of the head unit 51 in the longitudinal direction (the end in the direction of arrow B') is supported so as to be rotatable in the horizontal direction relative to a main body frame 101 (see FIG. 12) of the printer 100. A unit angle adjustment mechanism 110 (see FIG. 13) that adjusts the angle of the head unit 51 relative to the main body frame 101 is disposed at the other end of the head unit 51 in the longitudinal direction (the end in the direction of arrow B).

[0033] 8 and 9 are perspective views of a first reinforcing member 55 and a second reinforcing member 57, which respectively constitute the unit frame 52. The first reinforcing member 55 is formed by bending a metal plate into a predetermined shape, and has a side wall portion 55a, a bottom surface portion 55b, a first connecting piece 55c, and a second connecting piece 55d.

[0034] The side wall portion 55a is fixed to the main body portion 53a of the main frame 53. The bottom surface portion 55b is horizontally extended from the lower end portion of the side wall portion 55a to one side (the front side in FIG. 8) and has first engagement protrusions 56a, 56b, a second engagement protrusion 56c, and a unit positioning hole 59. The first engagement protrusions 56a, 56b protrude from the side edges of one side (the left side in FIG. 8) and the other side (the right side in FIG. 8) of the bottom surface portion 55b, respectively, and the second engagement protrusion 56c protrudes from the lower end portion of the side wall portion 55a through an opening 55e to the opposite side to the bottom surface portion 55b (the rear side in FIG. 8). The unit positioning hole 59 engages with the support shaft 101a (see FIG. 12) of the main body frame 101 when the first reinforcing member 55 is attached to the fulcrum side (the left side in FIG. 6) of the unit frame 52.

[0035] The first connecting piece 55c and the second connecting piece 55d are horizontally extended from the upper end of the side wall portion 55a to one side (the front side in FIG. 8) and the other side (the rear side in FIG. 8), respectively. The first connecting piece 55c and the second connecting piece 55d are formed with screw holes 58a for fixing a flow path structure (not shown) for supplying liquid such as ink and cleaning liquid to the recording heads 17a to 17c to the unit frame 52 with screws. A first engagement hole 55f is formed at the ridge between the side wall portion 55a and the second connecting piece 55d, which engages with a positioning protrusion 53c (see FIG. 7) formed at the upper end of the main frame 53.

[0036] The second reinforcing member 57 is formed by bending a metal plate into a predetermined shape, and has a support portion 57a ​​and an upper surface portion 57b. The support portion 57a ​​is fixed to a body portion 53a of the main frame 53. The support portion 57a ​​is formed with a screw hole 58b for fixing to the body portion 53a. The upper surface portion 57b is horizontally extended from an upper end portion of the support portion 57a, and is formed with a screw hole 58a for fixing a flow path structure (not shown) to the unit frame 52 with a screw. A second engagement hole 57c that engages with a positioning protrusion 53d (see FIG. 7) formed on the upper end portion of the main frame 53 is formed on the ridge portion between the support portion 57a ​​and the upper surface portion 57b.

[0037] 10 and 11 are perspective views showing a state in which the first reinforcing member 55 is attached to the bent portion 53b on the rotation fulcrum side (left side in FIG. 6) and the rotation end side (right side in FIG. 6) of the main frame 53. As shown in FIG. 10, on the rotation fulcrum side of the main frame 53, the first reinforcing member 55 is positioned with respect to the main frame 53 by engaging the positioning protrusion 53c with the first engagement hole 55f of the first reinforcing member 55.

[0038] As a result, the side edge on one side (left side in FIG. 8) of the side wall portion 55a of the first reinforcing member 55 is disposed along the ridge line L1, which is the bent portion between the main body portion 53a and the bent portion 53b. Also, the side edge on one side (left side in FIG. 8) of the bottom surface portion 55b is disposed along the inner surface of the bent portion 53b. Then, the first engaging protrusion 56a of the first reinforcing member 55 is engaged with the engaging hole 53e formed in the bent portion 53b, and the second engaging protrusion 56c is engaged with the engaging hole 53e (see FIG. 7) formed in the main body portion 53a. In this state, the side wall portion 55a is fixed to the main body portion 53a with a screw to complete the attachment of the first reinforcing member 55.

[0039] As shown in FIG. 11, at the rotation end side of the main frame 53, the first reinforcing member 55 is positioned relative to the main frame 53 by engaging the positioning protrusion 53c with the first engagement hole 55f of the first reinforcing member 55. As a result, the other side (right side in FIG. 8) edge of the side wall portion 55a of the first reinforcing member 55 is arranged along the ridge line L1, which is the bent portion between the main body portion 53a and the bent portion 53b. Also, the other side (right side in FIG. 8) edge of the bottom surface portion 55b is arranged along the inner surface of the bent portion 53b. Then, the first engagement protrusion 56b of the first reinforcing member 55 is engaged with the engagement hole 53e formed in the bent portion 53b, and the second engagement protrusion 56c is engaged with the engagement hole 53e (see FIG. 7) formed in the main body portion 53a. In this state, the side wall portion 55a is fixed to the main body portion 53a with a screw to complete the attachment of the first reinforcing member 55.

[0040] In this embodiment, the ridge line L1, which is the bent portion between the main body portion 53a and the bent portion 53b of the main frame 53, and the ridge line L2, which is the bent portion between the side wall portion 55a and the bottom surface portion 55b of the first reinforcing member 55, are assembled so as to be perpendicular to each other. Also, the first engagement protrusions 56a, 56b and the second engagement protrusions 56c formed on the bottom surface portion 55b of the first reinforcing member 55 are inserted into the engagement holes 53e of the main frame 53. This can increase the rigidity of both ends of the assembled unit frame 52 in the vertical and width directions.

[0041] Moreover, by attaching the first reinforcing members 55 of the same shape to the rotation fulcrum side and the rotation end side of the main frame 53, it is possible to prevent erroneous attachment compared to attaching different members, improving the ease of attachment. In addition, the number of members can be reduced, making it easier to manage the members.

[0042] Fig. 12 is a plan view seen from above of the configuration of the engagement portion between the rotation fulcrum side (left side in Fig. 6) of the unit frame 52 and the main body frame 101 of the printer 100. As shown in Fig. 12, on the rotation fulcrum side of the unit frame 52, the unit positioning hole 59 of the first reinforcing member 55 engages with the support shaft 102 of the main body frame 101. In addition, a pressing member 103 is disposed adjacent to the unit frame 52 on the main body frame 101. The pressing member 103 is biased by two coil springs 104 in a direction approaching the unit frame 52.

[0043] With this configuration, the unit frame 52 is pressed toward the rotation end side (arrow B direction) by the pressing member 103, and two adjacent sides of the pentagonal (home base shaped) unit positioning hole 59, sandwiching the apex therebetween, are pressed against the support shaft 102. Therefore, the unit frame 52 can be easily and reliably positioned in the longitudinal direction (arrow BB' direction).

[0044] Fig. 13 is a perspective view showing the configuration of a unit angle adjustment mechanism 110 provided on the rotation end side of the unit frame 52. The unit angle adjustment mechanism 110 is disposed close to the side surface on the rotation end side of the unit frame 52, and includes an angle adjustment member 111, a compression spring 112, and an operating member 113. In addition, the unit frame 52 is biased in the Ra direction around the support shaft 102 (see Fig. 12) by a biasing mechanism (not shown).

[0045] The angle adjustment member 111 is a rod-shaped member extending horizontally, and has an adjustment rotation shaft 111a and a head contact portion 111b. A compression spring 112 biases the angle adjustment member 111 in a clockwise direction around the adjustment rotation shaft 111a. The operating member 113 is rotatably supported by the main body frame 101, and moves in a direction to contact or move away from one end of the angle adjustment member 111 by rotating it in the forward or reverse direction.

[0046] When the operation member 113 is rotated forward and moved in a direction approaching the angle adjustment member 111, one end of the angle adjustment member 111 is pressed, and the angle adjustment member 111 rotates counterclockwise against the biasing force of the compression spring 112. As a result, the unit frame 52 is pressed by the head contact portion 111b and rotates in the Rb direction against the biasing force of the biasing mechanism. On the other hand, when the operation member 113 is rotated backward and moved in a direction away from the angle adjustment member 111, the angle adjustment member 111 rotates clockwise due to the biasing force of the compression spring 112. As a result, the head contact portion 111b moves in a direction away from the unit frame 52, and the unit frame 52 rotates in the Ra direction due to the biasing force of the biasing mechanism.

[0047] FIG. 14 is a perspective view of the head-side frame 70 constituting the recording heads 17a to 17c. The head-side frame 70 is formed by bending a metal plate into a U-shape in cross section, and has a flat portion 70a extending in the paper width direction (arrow BB' direction) and side portions 70b, 70c rising from the longitudinal side edges of the flat portion 70a. The head-side frame 70 is supported by the unit frame 52 so as to be rotatable in the horizontal direction with one longitudinal side (the rear left side in FIG. 14) as a rotation fulcrum and the other side (the front right side in FIG. 14) as a rotation end. A first adjustment screw 61 is screwed into the rotation end side of the side portion 70c to adjust the angle of the head-side frame 70 in the horizontal direction (Ra, Rb direction) relative to the unit frame 52.

[0048] Fig. 15 is a partial enlarged view of the rotation fulcrum side of the head-side frame 70 viewed from below. As shown in Fig. 15, a hexagonal head positioning hole 71 and an adjustment screw mounting hole 72 into which height adjustment screws 75a and 75b (described later) are screwed are formed at the end of the rotation fulcrum side of the flat portion 70a.

[0049] FIG. 16 is a perspective view of the first head mount member 80a disposed on the rotation fulcrum side of the head-side frame 70. The first head mount member 80a has a support shaft boss 81 and screw holes 83a to 83c. The support shaft boss 81 is inserted into the head positioning hole 71 of the head-side frame 70 to serve as the rotation fulcrum of the head-side frame 70. A screw 77a (see FIG. 18 for both) for fixing the leaf spring 76 to the first head mount member 80a is fastened into the screw hole 83a. A screw (not shown) for fixing the first head mount member 80a to the main frame 53 is fastened into the screw hole 83b (see FIG. 18). The screw hole 83c is formed along the axis center of the support shaft boss 81, and a head fixing pin 73 (see FIG. 18) for fixing the recording heads 17a to 17c is fastened into the screw hole 83a.

[0050] FIG. 17 is a perspective view showing the configuration of the connecting portion between the rotation fulcrum side of the head side frame 70 and the unit frame 52. FIG. 18 is a side cross-sectional view of the connecting portion between the rotation fulcrum side of the head side frame 70 and the unit frame 52 cut in a direction perpendicular to the longitudinal direction. As shown in FIG. 17 and FIG. 18, the support shaft boss 81 of the first head mount member 80a is inserted from above the head positioning hole 71 of the head side frame 70. In addition, the head fixing pin 73 is fastened from below the head side frame 70 through the head positioning hole 71. A head fixing spring 74 is sandwiched between the head fixing pin 73 and the head side frame 70. As a result, the head side frame 70 is pressed against the first head mount member 80a by the biasing force of the head fixing spring 74.

[0051] Furthermore, height adjustment screws 75a, 75b are screwed into the adjustment screw mounting holes 72 of the head-side frame 70 from below. When the height adjustment screws 75a, 75b are rotated in the forward direction (clockwise direction), the height adjustment screws 75a, 75b protrude upward and push up the lower surface of the first head mount member 80a. As a result, the head-side frame 70 moves downward against the biasing force of the head fixing spring 74. When the height adjustment screws 75a, 75b are rotated in the reverse direction (counterclockwise direction), the height adjustment screws 75a, 75b retract downward, and the head-side frame 70 moves upward due to the biasing force of the head fixing spring 74.

[0052] Furthermore, a leaf spring 76 is attached to the side surface of the first head mount member 80a opposite the main frame 53. The upper end of the leaf spring 76 is fixed to the first head mount member 80a with a screw 77a, and the lower end of the leaf spring 76 abuts against the inner surface of the side surface portion 70b of the head-side frame 70. As a result, the head-side frame 70 is urged in a direction away from the main frame 53 by the urging force of the leaf spring 76, and the positional relationship between the unit frame 52 and the head-side frame 70 in the transport direction (direction of arrow A) can be maintained constant.

[0053] At this time, a pressing force F1 acts on the head-side frame 70 from the leaf spring 76, and a force F1' is applied from the leaf spring 76 to the first head mount member 80a as a reaction to the pressing force F1. In other words, the force relationship of action and reaction is completed between the first head mount member 80a and the head-side frame 70, and the force of the leaf spring 76 does not act directly on the main frame 53. Therefore, deformation of the main frame 53 can be suppressed.

[0054] FIG. 19 is a perspective view of the second head mount member 80b disposed on the rotation end side of the head side frame 70. FIG. 20 is a perspective view showing a state in which the leaf spring 76 is attached to the second head mount member 80b. The second head mount member 80b has a sliding portion 82 and screw holes 83a to 83c. The sliding portion 82 is an L-shaped portion in a side view that is integrally formed below the second head mount member 80b, and the second adjustment screw 62 is screwed into the vertical portion of the L-shape. The sliding portion 82 slides along the flat portion 70a when adjusting the angle of the head side frame 70 by the first adjustment screw 61 (see FIG. 14) and the second adjustment screw 62. Engagement claws 82a for attaching a sliding plate 90 (see FIG. 25) are formed on both ends of the sliding portion 82 in the longitudinal direction.

[0055] A screw 77a for fixing the leaf spring 76 to the second head mount member 80b is fastened into the screw hole 83a (see FIG. 23). A screw 77b for fixing the second head mount member 80b to the main frame 53 (see FIG. 23) is fastened into the screw hole 83b. The screw hole 83c is formed in the center of the lower surface of the sliding part 82, and a head fixing pin 73 for fixing the recording heads 17a to 17c (see FIG. 23) is fastened into the screw hole 83c.

[0056] Fig. 21 is a perspective view showing the configuration of the connecting portion between the rotating end side of the head side frame 70 and the unit frame 52. Figs. 22 and 23 are side cross-sectional views of the connecting portion between the rotating end side of the head side frame 70 and the unit frame 52, cut in a direction perpendicular to the longitudinal direction. Figs. 22 and 23 are cross-sectional views including the head angle adjustment mechanism 60 and the leaf spring 76, respectively. Fig. 24 is a side cross-sectional view of the connecting portion between the rotating end side of the head side frame 70 and the unit frame 52, cut along the longitudinal direction.

[0057] 21 to 24, a head fixing pin 73 is fastened to a screw hole 83c of the second head mount member 80b, passing through an elongated head positioning hole 78 formed in the head side frame 70. A head fixing spring 74 is sandwiched between the head fixing pin 73 and the head side frame 70. As a result, the head side frame 70 is pressed against the second head mount member 80b by the biasing force of the head fixing spring 74.

[0058] Furthermore, a height adjustment screw 75c is screwed into the head-side frame 70 from below. When the height adjustment screw 75c is rotated in the forward direction (clockwise direction), the height adjustment screw 75c protrudes upward and pushes up the lower surface of the second head mount member 80b. As a result, the head-side frame 70 moves downward against the biasing force of the head fixing spring 74. When the height adjustment screw 75c is rotated in the reverse direction (counterclockwise direction), the height adjustment screw 75c retreats downward, and the head-side frame 70 moves upward due to the biasing force of the head fixing spring 74.

[0059] The height and vertical angle of the recording heads 17a to 17c can be adjusted by individually adjusting the height adjustment screws 75a, 75b (see FIG. 18) on the rotation fulcrum side of the head-side frame 70 and the height adjustment screw 75c. Note that, while two height adjustment screws 75a, 75b are provided on the rotation fulcrum side of the head-side frame 70, only the height adjustment screw 75c is provided on the rotation end side of the head-side frame 70. This is because the flat portion 70a of the head-side frame 70 comes into contact with the tips of the height adjustment screws 75a to 75c, thereby positioning the head-side frame 70 on a plane including the tips (three points) of the height adjustment screws 75a to 75c.

[0060] A head angle adjustment mechanism 60 is provided between the head side frame 70 and the second head mount member 80b. The head angle adjustment mechanism 60 is composed of a first angle adjustment screw 61 and a second angle adjustment screw 62. The first angle adjustment screw 61 is provided on the surface of the side surface portion 70c of the head side frame 70 that faces the sliding portion 82 of the second head mount member 80b. The first angle adjustment screw 61 penetrates the side surface portion 70c in the vertical direction and is capable of reciprocating along the conveying direction (arrow A direction) perpendicular to the support shaft boss 81. The first angle adjustment screw 61 is composed of a set screw with a hexagonal hole or a slot at the end, for example.

[0061] The second angle adjustment screw 62 is provided on the surface of the sliding part 82 of the second head mount member 80b that faces the side part 70c of the head-side frame 70. The second angle adjustment screw 62 passes vertically through the sliding part 82 and is capable of reciprocating movement along the conveyance direction (direction of arrow A) perpendicular to the support shaft boss 81. The second angle adjustment screw 62 is configured, for example, as a set screw with a hexagonal hole or a slot provided at the end.

[0062] The first angle adjustment screw 61 and the second angle adjustment screw 62 are disposed at positions opposing each other in the transport direction (arrow A direction) perpendicular to the support shaft boss 81. More specifically, the first angle adjustment screw 61 and the second angle adjustment screw 62 are disposed at positions opposing each other in the longitudinal direction (paper width direction, arrow BB' direction) and the up-down direction of the head unit 51, and the first angle adjustment screw 61 and the second angle adjustment screw 62 reciprocate on the same axis.

[0063] According to the above configuration, when assembling the head unit 51, the second angle adjustment screw 62 of the second head mount member 80b is adjusted to a predetermined position in advance. Then, after adjusting the first angle adjustment screw 61 of each of the recording heads 17a to 17c to a predetermined position, the recording heads 17a to 17c are mounted on the unit frame 52. As a result, when replacing any of the recording heads 17a to 17c, the replacement work is completed by simply removing the recording head 17a to 17c that needs to be replaced and then mounting the new recording head 17a to 17c whose first angle adjustment screw 61 has been adjusted on the unit frame 52 whose second angle adjustment screw 62 has already been adjusted. Therefore, alignment adjustment with respect to the unit frame 52 can be easily performed when replacing the recording heads 17a to 17c.

[0064] Furthermore, a leaf spring 76 is attached to the side surface of the second head mount member 80b opposite the main frame 53. The upper end of the leaf spring 76 is fixed to the second head mount member 80b with a screw 77a, and the lower end of the leaf spring 76 abuts against the inner surface of the side surface portion 70b of the head-side frame 70. As a result, the head-side frame 70 is urged in a direction away from the main frame 53 (in a direction approaching the sliding portion 82) by the urging force of the leaf spring 76, and the contact state of the first angle adjustment screw 61 and the second angle adjustment screw 62 can be maintained.

[0065] At this time, as shown in Fig. 23, a pressing force F1 acts on the head-side frame 70 from the leaf spring 76, and a force F1' is applied from the leaf spring 76 to the second head mount member 80b as a reaction to the pressing force F1. Also, a pressing force F2 acts on the first angle adjustment screw 61 (side surface portion 70c) from the second angle adjustment screw 62, and a force F2' is applied from the first angle adjustment screw 61 to the second angle adjustment screw 62 (second head mount member 80b) as a reaction to the pressing force F2. In other words, the force relationship of action and reaction is completed between the second head mount member 80b and the head-side frame 70, and the force of the leaf spring 76 does not directly act on the main frame 53. Therefore, deformation of the main frame 53 can be suppressed.

[0066] Fig. 25 is a perspective view showing a connected state between the rotating end side of the head side frame 70 and the second head mount member 80b. Fig. 26 is a perspective view showing a state in which a sliding plate 90 is attached to the sliding part 82 of the second head mount member 80b. As shown in Fig. 25, the head side frame 70 is biased upward by the head fixing spring 74, and the tip of the height adjustment screw 75c is pressed against the lower surface of the sliding part 82.

[0067] If the sliding load between the height adjustment screw 75c and the sliding portion 82 is large, the second head mount member 80b will not move smoothly during alignment adjustment of the recording heads 17a to 17c by the head angle adjustment mechanism 60, impeding the alignment adjustment. Therefore, as shown in Figures 25 and 26, a sliding plate 90 is attached to the underside of the sliding portion 82 of the second head mount member 80b.

[0068] The sliding plate 90 is a sheet metal member made of, for example, SUS (stainless steel), and both ends in the longitudinal direction are bent upward. A pair of engaged parts 90a consisting of rectangular openings are formed at the bent parts. The sliding plate 90 is attached to the lower surface of the sliding part 82 by engaging the engaging claws 82a of the sliding part 82 with the engaged parts 90a. The sliding plate 90 is attached to the second head mount member 80b with a play in the vertical direction, and the sliding plate 90 is structured so that it is in close contact with the lower surface of the sliding part 82 by attaching the head fixing pin 73 and the head fixing spring 74. The material of the sliding plate 90 is not limited to SUS (stainless steel), and may be any material that has greater slidability and rigidity than the second head mount member 80b.

[0069] Providing the sliding plate 90 on the sliding portion 82 can prevent the second head mount member 80b from being scratched or dented due to contact with the height adjustment screw 75c. Furthermore, the sliding of the height adjustment screw 75c and the sliding plate 90 during alignment adjustment of the recording heads 17a to 17c by the head angle adjustment mechanism 60 reduces the sliding load between the height adjustment screw 75c and the sliding portion 82, improving the tracking ability of the second head mount member 80b. Therefore, alignment adjustment can be performed smoothly and accurately.

[0070] Also, because the sliding plate 90 is attached to the second head mount member 80b with some backlash (play), the sliding plate 90 can be easily attached to the second head mount member 80b regardless of the component tolerances of the second head mount member 80b and the sliding plate 90, improving the ease of assembly. Furthermore, by providing the engaging claws 82a on the second head mount member 80b side and the engaged parts 90a on the sliding plate 90 side, the sliding plate 90 is held without falling off the second head mount member 80b when the head fixing pins 73 and head fixing springs 74 are removed and the recording heads 17a to 17c are replaced individually.

[0071] According to the configuration of this embodiment, the head unit 51 includes a plurality of (three in this embodiment) recording heads 17a to 17c arranged side by side on both sides of the unit frame 52. With this configuration, for example, when it becomes necessary to replace one recording head 17a, the other two recording heads 17b and 17c can be continuously used without replacement. Therefore, it is possible to realize a reduction in cost of the head unit 51.

[0072] Furthermore, a leaf spring 76 is attached to the side surface of the first head mount member 80a and the second head mount member 80b opposite the main frame 53, to maintain a constant positional relationship between the unit frame 52 and the head-side frame 70 in the transport direction (direction of arrow A). At this time, a pressing force F1 acts on the head-side frame 70 from the leaf spring 76, and a force F1' is applied from the leaf spring 76 to the first head mount member 80a or the second head mount member 80b as a reaction to the pressing force F1, so that a force relationship of action and reaction is completed between the first head mount member 80a or the second head mount member 80b and the head-side frame 70. As a result, the force of the leaf spring 76 does not act directly on the main frame 53, so deformation of the main frame 53 can be suppressed.

[0073] Furthermore, by mounting the sliding plate 90 on the sliding portion 82 of the second head mount member 80b, it is possible to prevent the second head mount member 80b from being scratched or dented by the height adjustment screw 75c. Furthermore, the sliding load between the height adjustment screw 75c and the sliding portion 82 is reduced by the sliding of the height adjustment screw 75c and the sliding plate 90 during alignment adjustment of the recording heads 17a to 17c, so that the alignment adjustment can be performed smoothly and accurately.

[0074] The printer 100 also includes a head unit 51 having the above-described configuration that records an image on the paper S. With this configuration, the printer 100 allows only the recording heads 17a to 17c that have developed a malfunction to be individually replaced, resulting in a configuration that reduces costs.

[0075] In addition, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, a configuration in which three recording heads 17a to 17c are attached to one head unit 51 has been described, but a configuration in which two or four or more recording heads are attached to the head unit 51 may also be used. [Industrial Applicability]

[0076] The present invention can be used in a head unit having a detachable recording head, and in an inkjet recording apparatus such as an inkjet printer having a head unit. [Explanation of symbols]

[0077] 5 First belt conveyor 8 First conveyor belt 9. Recording Section 17a~17c Recording head 51 Head Unit 52 Unit Frame 53 Mainframe 55 First reinforcing member 57 Second reinforcing member 60 Head angle adjustment mechanism 61 First angle adjustment screw 62 Second angle adjustment screw 70 Head side frame 70a flat area 70b, 70c side part 73 Head fixing pin 74 Head fixing spring 75a~75c Height adjustment screw 76 Leaf spring (biasing member) 80a first head mounting member 80b second head mount member 81 Pivot boss 82 Sliding part 82a Engagement claw 90 Sliding plate 90a Engaged part 100 Printers (inkjet recording devices) P Paper (recording medium)

Claims

1. a recording head having a plurality of nozzles for ejecting ink onto a recording medium; a head side frame constituting the recording head; a unit frame for holding one or more recording heads on both side surfaces of a flat main frame standing upright along a width direction perpendicular to a conveying direction of the recording medium; a first head mount member fixed to the main frame and having a support shaft for swingably supporting one end of the head side frame in the width direction; a second head mount member fixed to the main frame and supporting the other end of the head side frame in the width direction; a head angle adjustment mechanism that adjusts a horizontal angle of the recording head with respect to the unit frame by changing a horizontal position of the head side frame with respect to the second head mounting member; In a head unit comprising: a biasing member is disposed between the head side frame and the first head mount member and between the head side frame and the second head mount member, the biasing member biasing the first head mount member or the second head mount member toward the main frame, A head unit characterized in that the relationship between the pressing force acting on the head side frame from the biasing member and the force applied from the biasing member to the first head mount member or the second head mount member as a reaction to the pressing force is completed between the first head mount member or the second head mount member and the head side frame.

2. the head-side frame has a U-shape in cross section and includes a flat portion extending in the width direction and a pair of side portions rising from side edges in the longitudinal direction of the flat portion, The head unit according to claim 1, characterized in that the biasing member is a leaf spring having one end fixed to the first head mounting member or the second head mounting member and the other end pressed against the inner surface of the side portion of the head side frame opposite the main frame.

3. a head fixing spring that biases the head side frame in a direction approaching the first head mounting member or the second head mounting member; the flat portion of the head side frame is pressed against the first head mount member and the second head mount member by the biasing force of the head fixing spring, and the flat portion slides along a sliding portion of the second head mount member when the angle of the recording head is adjusted by the head angle adjustment mechanism; 3. The head unit according to claim 2, wherein a sliding plate having greater slidability and rigidity than the second head mount member is disposed on the lower surface of the sliding portion on which the flat portion slides.

4. the head side frame is provided with a height adjustment screw that changes a vertical position of the head side frame relative to the second head mount member by reciprocating in a direction toward or away from the first head mount member or the second head mount member, 4. The head unit according to claim 3, wherein the height adjustment screw is pressed against the second head mount member by the head fixing spring via the sliding plate.

5. A head unit as described in claim 3 or claim 4, characterized in that the sliding portion is provided with an engaging claw that engages with an engaged portion formed on the sliding plate, and when the head side frame is removed, the sliding plate is held on the sliding portion by engagement between the engaging claw and the engaged portion.

6. The head angle adjustment mechanism includes: a first angle adjustment screw provided on a surface of the second head mount member facing the side surface portion and reciprocating in a direction toward and away from the side surface; a second angle adjustment screw provided on a surface of the side portion facing the second head mount member and reciprocating in a direction toward and away from the second head mount member; Equipped with 6. The head unit according to claim 2, wherein the first angle adjustment screw and the second angle adjustment screw reciprocate on the same axis.

7. An inkjet recording apparatus comprising the head unit according to any one of claims 1 to 6.

Images