Image formation device

Abstract

To suppress lowering of accuracy of a distance between a recording head and a conveyance surface of a belt.SOLUTION: An image formation device 1 has: a belt unit 2200 including an endless belt 25 for carrying a sheet S on a conveyance surface 25a, and conveying the sheet S, and a platen unit 26 which is provided on the inner peripheral surface side of the belt 25 and slidably supports the belt 25; a recording head 10; and a seating surface 200, wherein the belt unit 2200 has a support structure 100 which is arranged on the seating surface 200, and includes recording head support parts 34a and 34b for receiving a load from the recording head 10 and supporting the recording head 10, and platen unit support parts 33a and 33d which are provided separately from the recording head support parts 34a and 34b so that the platen unit 26 does not receive the load from the recording head 10, and support the platen unit 26.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, such as a printing machine, a copying machine, or a printer, which forms an image using an inkjet method. [Background technology]

[0002] Conventionally, there are inkjet-type image forming devices (inkjet recording devices) that eject ink droplets onto a recording medium such as recording paper or a resin sheet to record images such as characters or pictures. One such image forming device is a line-head type inkjet recording device that ejects different colored droplets from multiple recording heads in conjunction with the transport of the recording medium, while the recording heads are stationary relative to the image forming device body, to record a color image on the recording medium. Another known line-head type inkjet recording device transports the recording medium relative to the recording heads using an endless print belt. This print belt is stretched over multiple tension rollers, and the recording medium is attracted to and transported on a transport surface formed between the tension rollers upstream and downstream of the multiple recording heads in the direction of rotation of the print belt.

[0003] In such image forming apparatuses, the distance between the print head (more specifically, the fine nozzles of the print head that eject ink) and the transport surface of the print belt must be controlled with high precision. For example, air currents are generated as the print belt transports the recording medium. As a result, when ink droplets are ejected from the print head onto the recording medium, some of the ink droplets may become mist and reach the recording medium. In this case, if the distance between the print head and the transport surface of the print belt is large, the position where the mist of ink reaches the recording medium may be significantly different from the position where the non-misted ink reaches the recording medium, which may result in an image defect. Therefore, it is desirable to keep the distance between the print head and the transport surface of the print belt as close as possible. On the other hand, if the distance between the print head and the transport surface of the print belt is too close, the recording medium being transported by the print belt may collide with the print head, which may cause a malfunction of the print head.

[0004] Patent document 1 proposes a configuration for positioning the recording head relative to the platen plate using gap adjustment sections attached at both ends to a head holding section that holds the recording head and a platen plate that slidably supports a print belt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-157574 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-described conventional configuration, the platen plate may be deformed by the load applied from the recording head to the platen plate, making it difficult to maintain an appropriate distance between the recording head and the conveying surface of the print belt.

[0007] In order to maintain the distance between the print head and the conveying surface of the print belt with high precision, the print head may be pressed against a member that positions it. In this case, the pressure may be as high as 800 N, particularly in a line-head inkjet recording device with multiple print heads, which can exacerbate the above-mentioned problem.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to prevent a decrease in the accuracy of the distance between the recording head and the transport surface of the print belt. [Means for solving the problem]

[0009] The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention is an image forming apparatus comprising: a belt unit including an endless belt that carries a sheet on a transport surface and transports it, and a platen unit that is provided on the inner peripheral surface of the belt and slidably supports the belt, a recording head that is provided opposite the platen unit across the belt and ejects a recording liquid onto the sheet transported by the belt, and a seat on which the belt unit and the recording bed are placed, the belt unit having a support structure that is disposed on the seat and includes: a recording head support portion that supports the recording head by receiving a load from the recording head, and a platen unit support portion that is provided separately from the recording head support portion and supports the platen unit so that the platen unit does not receive the load from the recording head. [Effects of the Invention]

[0010] According to the present invention, it is possible to prevent a decrease in the accuracy of the distance between the recording head and the transport surface of the print belt. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view of a print module. [Figure 3] FIG. 2 is a schematic perspective view of a platen unit. [Figure 4] FIG. 2 is a schematic perspective view for explaining a positioning structure of a recording head. [Figure 5] FIG. 2 is a schematic cross-sectional view of a portion of a print module. [Figure 6] FIG. 2 is a schematic perspective view of a configuration of a part of a print module. [Figure 7] FIG. 2 is a schematic perspective view of a frame of the print belt unit. [Figure 8] FIG. 2 is a schematic perspective view of a frame of the print belt unit supporting the platen unit. [Figure 9] 10A and 10B are schematic cross-sectional views showing the effects of the embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view of another example of a print module. [Figure 11] FIG. 10 is a schematic perspective view of another example of the frame of the print belt unit. [Figure 12] FIG. 2 is a perspective view of the vicinity of a gap adjustment portion. [Figure 13] FIG. 4 is a schematic diagram showing a control configuration of a gap adjustment unit. DETAILED DESCRIPTION OF THE INVENTION

[0012] The image forming apparatus according to the present invention will be described in more detail below with reference to the drawings.

[0013] <Image forming device> First, the overall configuration of the image forming apparatus of this embodiment will be described. The image forming apparatus of this embodiment is a line-head type inkjet recording apparatus that uses an inkjet system. FIG. 1 is a schematic cross-sectional view showing the overall configuration of the inkjet recording apparatus 1 of this embodiment. This inkjet recording apparatus 1 is a sheet-fed inkjet recording apparatus that uses two liquids, a reaction liquid and ink, as recording liquids to form an ink image on a sheet S, such as cut plain paper, which is a recording medium (recording material, paper), and outputs a recorded product.

[0014] In the following description, the inkjet recording apparatus 1 is assumed to be installed on a horizontal surface. With respect to the inkjet recording apparatus 1 and its elements, the front side of the paper in FIG. 1 is the "front" side, the back side of the paper in FIG. 1 is the "rear" side, the right side in FIG. 1 is the "right" side, the left side in FIG. 1 is the "left" side, the top side in FIG. 1 is the "up" side, and the bottom side in FIG. 1 is the "down" side. The front-to-back direction is perpendicular to the left-to-right direction and the up-to-down direction. When the inkjet recording apparatus 1 is installed on a horizontal surface, the up-to-down direction is parallel to the direction of gravity (vertical direction). However, with respect to the inkjet recording apparatus 1 and its elements, up-to-down does not mean just above or just below, but also includes above and below with respect to a horizontal plane passing through the element or position of interest.

[0015] In the following description, the sheet S may be referred to as paper, but the sheet S may also be formed from materials other than paper or materials containing materials other than paper (such as synthetic paper or film formed using synthetic resin, or metal-deposited paper having a metal layer). For convenience, the recording liquid such as a reaction liquid or ink may be simply referred to as "ink," but it may be any liquid such as a reaction liquid used to record an image.

[0016] The inkjet recording apparatus 1 has modules (sheet processing sections) including a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a paper discharge stacking module 7000. A cut sheet S supplied from the paper feed module 1000 is transported along a transport path, processed in each module, and guided to the paper discharge stacking module 7000.

[0017] The paper feed module 1000 includes three storage cabinets 1100a, 1100b, and 1100c that store sheets S, and a housing 1200 that houses these. Each of the storage cabinets 1100a, 1100b, and 1100c is configured to be able to be pulled out toward the front of the housing 1200. The sheets S are fed one by one from each of the storage cabinets 1100a, 1100b, and 1100c by a separation belt and a transport roller, and are transported to the print module 2000. The number of storage cabinets 1100a, 1100b, and 1100c is not limited to three, and may be one, two, four, or more.

[0018] The print module 2000 includes a registration correction unit (pre-imaging registration correction unit) 2400, a print belt unit 2200 as a belt conveying device, a recording unit 2300, and a housing 2500 that houses these components. The sheet S conveyed from the paper feed module 1000 to the print module 2000 has its tilt and position corrected by the registration correction unit 2400 and is then conveyed to the print belt unit 2200. The recording unit 2300 is positioned opposite the print belt unit 2200 across the conveyance path of the sheet S. The recording unit 2300 performs recording processing (image formation, printing, and character printing) on ​​the sheet S conveyed by the print belt unit 2200 from above using a recording head 10 to form an image on the sheet S. The sheet S is attracted and conveyed by the print belt 25 of the print belt unit 2200, ensuring clearance with the recording head 10. The print belt unit 2200 transports the sheet S from right to left. The recording unit 2300 has multiple line-type recording heads 10 arranged along the transport direction of the sheet S. In this embodiment, the recording unit 2300 has eight line-type recording heads 10 (10a-10h) corresponding to four colors (Y (yellow), M (magenta), C (cyan), and Bk (black), as well as three special colors (white and neon colors) and reactive liquids (FIG. 2). The number of colors and the number of recording heads 10 are not limited to eight. The inkjet method for the recording heads 10 can be a method using a heating element, a piezoelectric element, an electrostatic element, or a MEMS element. Each color of ink is supplied to the corresponding recording head 10 from an ink tank provided in the print module 2000 via an ink tube. The sheet S on which the recording process has been performed by the recording unit 2300 is transported by the print belt unit 2200 and passes through an in-line scanner (not shown) arranged downstream of the recording unit 2300 in the transport direction of the sheet S. The inkjet recording apparatus 1 can correct the print image based on the misalignment and color density of the image formed on the sheet S detected by the in-line scanner.

[0019] The drying module 3000 includes a decoupling unit 3200, a drying belt unit 3300, a hot air blowing unit 3400, and a housing 3500 that houses these components. The drying module 3000 reduces the liquid content of the ink applied to the sheet S by the recording unit 2300, improving the fixation of the ink to the sheet S. After the sheet S has been recorded by the recording unit 2300 of the print module 2000, it is transported to the decoupling unit 3200 located within the drying module 3000. The decoupling unit 3200 transports the sheet S by using air pressure from above and friction with the belt 3200a of the decoupling unit 3200. The decoupling unit 3200 loosely holds the sheet S on the belt 3200a while transporting it, thereby preventing the sheet S from shifting as the ink image forms on the print belt 25 of the print belt unit 2200. The sheet S transported from the decoupling section 3200 to the drying belt unit 3300 is attracted and transported by the belt 3300a of the drying belt unit 3300. At the same time, hot air is blown from a hot air blowing section 3400 arranged above the belt 3300a of the drying belt unit 3300, drying the ink-coated surface of the sheet S. In addition to the method of blowing hot air, other drying methods can be used, such as irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.) or conducting heat transfer by contact with a heating element. These methods may be used in any combination.

[0020] The fixing module 4000 includes a fixing belt unit 4100 and a housing 4300 that houses the fixing belt unit 4100. The fixing module 4000 fixes ink to the sheet S by passing the sheet S, which has been transported from the drying module 3000, between a heated upper belt unit 4100a and a heated lower belt unit 4100b.

[0021] The cooling module 5000 includes multiple cooling units 5100 and a housing 5200 that houses them. The cooling module 5000 cools the high-temperature sheet S that has been transported from the fixing module 4000 to the cooling module 5000. The cooling unit 5100 is configured to cool the sheet S by drawing in outside air into a cooling box with a fan to increase the pressure inside the cooling box and blowing air from nozzles formed in a transport guide onto the sheet S. The cooling units 5100 are arranged on both sides of the transport path of the sheet S, allowing the sheet S to be cooled from both sides. The cooling module 5000 also includes a switching unit that switches the transport path of the sheet S. This switching unit can switch the transport path of the sheet S depending on whether the sheet S is to be transported to the inversion module 6000 or to a duplex transport path used for duplex printing. During double-sided printing, the sheet S is transported to a double-sided transport path provided below the cooling module 5000, and further transported along double-sided transport paths provided in the fixing module 4000, drying module 3000, print module 2000, and paper feed module 1000. As a result, the sheet S is transported again to the registration correction unit 2400, print belt unit 2200, and recording unit 2300 of the print module 2000, where it is subjected to recording processing by the recording unit 2300. Note that the double-sided transport path of the fixing module 4000 is provided with a first reversing unit 4200 that reverses the sheet S, so that during double-sided printing, the sheet S can be reversed and then transported again to the recording unit 2300.

[0022] The reversing module 6000 has a second reversing unit 6400 and a housing 6500 that houses the second reversing unit 6400. The reversing module 6000 can reverse the front and back of the sheet S transported from the cooling module 5000 to the reversing module 6000, and can freely change the front and back and the orientation of the leading and trailing ends in the transport direction of the sheet S discharged from the reversing module 6000.

[0023] The discharge stacking module 7000 has a top tray 7200, a stacking section 7500, and a housing 7600 in which these are provided. The discharge stacking module 7000 aligns the sheets S transported from the reversing module 6000 to the discharge stacking module 700, and can discharge and stack the sheets onto the top tray 7200, or can stack the sheets onto the stacking section 7500 and store them.

[0024] <Print Module> Next, the print module 2000 in the inkjet recording apparatus 1 of this embodiment will be further described.

[0025] 2 is a schematic cross-sectional view of the print module 2000. The print module 2000 is an image forming unit that performs a recording process from above on a sheet S transported by a print belt unit 2200 using a recording head 10 of a recording unit 2300 to form an image (ink image) on the sheet S. The print module 2000 is provided with a print belt unit 2200 that transports the sheet S by suction and adsorption so that the transport behavior of the sheet S directly below the recording head 10 is stable. The print belt unit 2200 has a plurality of tension rollers 21 to 24, a print belt 25, a platen unit 26, and a suction device 27.

[0026] In this embodiment, the print belt (conveyor belt) 25, which is an endless belt, is stretched around four tension rollers, namely, first, second, third, and fourth tension rollers 21, 22, 23, and 24, and tensioned with a predetermined tension. The first tension roller 21 is a drive roller that rotates (circulates) the print belt 25 in the counterclockwise direction indicated by the arrow R1 in the figure. The second tension roller 22 is a tension roller that is biased from the inner peripheral surface of the print belt 25 toward the outer peripheral surface thereof by a biasing mechanism (not shown) as a biasing means, and applies a force to the print belt 25 to tension it. The third tension roller 23 is a steering roller that is movable at one end in the direction of its rotation axis and tiltable so that its rotation axis is inclined relative to the rotation axes of the other tension rollers. The print belt unit 2200 is configured so that tilting of the steering roller 23 can correct the running position of the print belt 25 in the width direction (a direction substantially perpendicular to the surface movement direction) (suppressing meandering). The first tension roller 21 is driven to rotate by a driving force transmitted from a motor, which is a drive source provided in a belt drive unit (not shown) serving as a driving means provided in the print belt unit 2200. The second, third, and fourth tension rollers 22, 23, and 24 are driven to rotate in accordance with the rotation of the print belt 25. The first, second, third, and fourth tension rollers 21, 22, 23, and 24 are rotatably supported at both ends of their respective rotation axes by support side plates 38 (FIG. 6) that constitute the print belt unit 2200. The support side plates 38 are attached to a frame 100 (FIG. 6) of the print belt unit 2200, which will be described later. The number of rollers over which the print belt 25 is stretched is not limited to four, but may be two, three, or four or more.

[0027] Of the surfaces of the print belt 25 formed by the first to fourth tension rollers 21 to 24, the sheet S is carried and transported on a transport surface 25a, which is the outer surface of the print belt 25 stretched between the first tension roller 21 and the fourth tension roller 24. That is, the print belt 25 carries and transports the sheet S on the transport surface 25a directly below and facing the recording head 10. A platen unit 26 is provided on the inner peripheral surface of the print belt 25 as a belt support section that slidably supports the print belt 25 while applying suction. The platen unit 26 slidably supports the inner peripheral surface of the print belt 25 between the fourth tension roller 24 and the first tension roller 21 in the rotation direction (travel direction) of the print belt 25, i.e., the inner peripheral surface of the print belt 25 corresponding to the transport surface 25a. In particular, in this embodiment, the platen unit 26 (more specifically, the sliding surface 261 described later) is disposed so as to be able to come into contact with the print belt 25 over the entire area from a position facing the most upstream recording head 10a (more specifically, its nozzles) to a position facing the most downstream recording head 10h (more specifically, its nozzles) in the movement direction (left-right direction, running direction) of the transport surface 25a of the print belt 25. Also, in this embodiment, the platen unit 300 is disposed so as to be able to come into contact with the print belt 25 over at least the entire area in the width direction (front-rear direction) of the print belt 25 that can support the sheet S.

[0028] In this embodiment, the print belt 25 is made of PET (polyethylene terephthalate), which is a resin material. In this embodiment, the surface resistivity of the print belt 25 is 1×10 10 The resistance is about Ω / □. In this embodiment, the print belt 25 has a size in the width direction (a direction substantially perpendicular to the moving direction of the surface) set so that a B3 size (364 mm x 515 mm) sheet S can be fed transversely (conveyed in a direction with the short side along the conveying direction). The resin material constituting the print belt 25 is not limited to PET, and other resin materials such as polyimide and polycarbonate may also be used. The print belt 25 is not limited to being made of resin, and may be made of metal.

[0029] 3 is a schematic perspective view of the platen unit 26. The platen unit 26 has a predetermined length in the longitudinal direction along the left-right direction and in the width direction along the front-rear direction, and has a predetermined height in the up-down direction, and is formed in a box shape as a whole. That is, the platen unit 26 has a front wall portion 260a and a rear wall portion 260b extending in the left-right direction, a right wall portion 260c and a left wall portion 260d extending in the front-rear direction, and a bottom wall portion 260e (the bottom wall portion 260e is indicated by a dashed line). The front wall portion 260a, the rear wall portion 260b, the right wall portion 260c, the left wall portion 260d, and the bottom wall portion 260e are connected to each other to form a platen unit frame (suction box) 260 as a holder.

[0030] The platen unit 26 is also provided with a sliding surface (platen member, platen plate) 261 that slidably supports the print belt 25, forming the side surface of the upper part of the platen unit frame 260. This sliding surface 261 is provided with a number of upper openings (intake openings) 262, which are openings. The bottom wall portion 260e of the platen unit frame 260 is also provided with lower openings (exhaust openings) 263, which are openings. In this embodiment, the bottom wall portion 260e is provided with a plurality of lower openings 263. Note that substantially the entire lower portion (bottom) of the platen unit 26 may be formed as lower openings.

[0031] A suction device 27 is connected to a lower opening 263 of the platen unit 26. As shown in FIG. 2, in this embodiment, the suction device 27 is disposed below the lower opening 263 of the platen unit 26 on the inner circumferential surface side of the print belt 25. The suction device 27 includes a suction fan that operates to suck air from the inside of the box-shaped platen unit 26 through the lower opening 263. During recording (image formation), the suction device 27 sucks air out of the lower opening 263, creating a negative pressure inside the platen unit 26. As a result, the print belt 25 on the sliding surface 261 of the platen unit 26 is sucked through the upper opening 262 and adhered to the sliding surface 261. Furthermore, the print belt 25 has a large number of suction holes 25b (see the schematic enlarged plan view in FIG. 2) with a diameter of, for example, about 0.3 mm, bored all around the circumference. As a result, the sheet S transported by the print belt 25 is sucked by the suction holes 25b and is adsorbed to the transport surface 25a of the print belt 25. The suction device 27 is configured to exhaust air to the outside of the print belt unit 2200 via a duct (not shown), and further to the outside of the housing 2500 of the print module 2000. Note that the source of the suction force of the suction device 27 is not limited to a fan, and may be, for example, a vacuum pump.

[0032] The platen unit 26 is also provided with a front right support receiving portion 264a, a front left support receiving portion 264b, a rear right support receiving portion 264c, and a rear left support receiving portion 264d as support receiving portions (supported portions). In this embodiment, two support receiving portions, the front right support receiving portion 264a and the front left support receiving portion 264b, are provided on the outer surface of the front wall portion 260a of the platen unit 26 so as to protrude toward the front side. In addition, two support receiving portions, the rear right support receiving portion 264c and the rear left support receiving portion 264b, are provided on the outer surface of the rear wall portion 260b of the platen unit 26 so as to protrude toward the rear side. In this embodiment, the front right support receiving portion 264a and the rear right support receiving portion 264c, and the front left support receiving portion 264b and the rear left support receiving portion 264d are provided at approximately the same positions in the left-right and up-down directions. In this embodiment, the support receiving portions 264a to 264d are formed of members having a substantially U-shaped cross section that is open downward. As will be described in detail later, the platen unit 26 is supported by a frame 100 (described later) of the print belt unit 2200 at the support receiving portions 264a to 264d (FIG. 8).

[0033] <Recording head positioning> Next, the positioning structure of the recording head 10 relative to the print belt unit 2200 in the inkjet recording apparatus 1 of this embodiment will be described. Figure 4 is a schematic perspective view for explaining the positioning structure of the recording head 10. Note that in this embodiment, eight recording heads 10 are provided, but the positioning structure is substantially the same for all of the recording heads 10. Therefore, the positioning structure will be described by focusing on one representative recording head 10.

[0034] The recording head 10 is supported by three positioning balls 50a, 50b, and 50c that serve as positioning members provided on a frame 100 (described later) of the print belt unit 2200. The front positioning ball (first positioning ball) 50a is provided on a front beam portion 28a that constitutes the frame 100 (described later) (FIG. 7). The rear two positioning balls (second and third positioning balls) 50b and 50c are provided on a rear beam portion 28b that constitutes the frame 100 (described later) (FIG. 7). A conical recess 11 that narrows in diameter toward the top is provided at the bottom of the recording head 10, where the front first positioning ball 50a abuts. A second positioning ball 50b is provided at a position facing the first positioning ball 50a in the front-to-rear direction. A V-shaped groove 12, whose width in the left-right direction decreases toward the top, is provided at the bottom of the recording head 10 where the second positioning ball 50b abuts. A third positioning ball 50c is provided to the left of the rear second positioning ball 50b. A substantially horizontal flat portion 13 is provided at the bottom of the recording head 10 where the third positioning ball 50c abuts.

[0035] Furthermore, the recording head 10 is pressed downward with a force of about 100 N by a pressure unit (pressure mechanism) 14 as a pressure means so as to be pressed against the three positioning balls 50a, 50b, and 50c. The pressure unit 14 is configured to have, for example, a spring or the like which is a pressure member (biasing member) as a pressure means (biasing means).

[0036] With this configuration, the recording head 10 can be positioned with high precision without any play in the vertical, horizontal, or front-to-rear directions.

[0037] On the other hand, since the total pressure applied by the eight recording heads 10 is approximately 800 N, the components for positioning the recording heads 10 in the print belt unit 2200 must be designed so that the distance between the recording heads 10 and the conveying surface 25a of the print belt 25 is not affected even when such a load is applied.

[0038] As mentioned above, in the past, there was a configuration in which the print head was positioned relative to the platen plate, but in this configuration, the platen plate may be deformed by the load applied from the print head to the platen plate, making it difficult to maintain an appropriate distance between the print head and the transport surface of the print belt.

[0039] Therefore, in this embodiment, the print belt unit 2200 is configured so that the pressure of the recording head 10 is received by a frame 100 (described later) that is independent of the platen unit 26 (the recording head 10 is positioned relative to the frame 100). Also, in this embodiment, the print belt unit 2200 is configured so that the platen unit 26 is separately supported by the frame 100. This makes it possible to prevent a decrease in the accuracy of the distance between the recording head 10 and the transport surface 25a of the print belt 25. This will be explained in more detail below.

[0040] <Print belt unit frame structure> Next, the frame (support structure) 100 of the print belt unit 2200 in the inkjet recording apparatus 1 of this embodiment will be described. Fig. 5 is a schematic cross-sectional view showing the configuration of a portion of the print module 2000. Fig. 6 is a schematic perspective view showing the configuration of a portion of the print module 2000. Fig. 7 is a schematic perspective view of the frame 100. Fig. 8 is a schematic perspective view of the frame 100 and the platen unit 26.

[0041] First, we will explain the configuration of the frame body 100. In this embodiment, the frame body 100 has a front beam portion 28a and a rear beam portion 28b, which are beam portions (beam members), and a front right pillar portion 29a, a front left pillar portion 29b, and a rear pillar portion 29c, which are pillar portions (column members).

[0042] The front beam portion 28a and the rear beam portion 28b are provided at both ends of the print belt 25 in the width direction. The front beam portion 28a and the rear beam portion 28b extend in the left-right direction (substantially parallel in this embodiment), i.e., in the direction of movement of the transport surface 25a of the print belt 25. The front beam portion 28a is located on the front side, and the rear beam portion 28b is located on the rear side. A front positioning block 51a and a rear positioning block 51b are fixed to the upper surface 34a of the front beam portion 28a and the upper surface 34b of the rear beam portion 28b, respectively, as recording head support portions. Retaining holes 52a and 52b for retaining positioning balls 50 are provided on the upper surfaces of the front positioning block 51a and the rear positioning block 51b, respectively. The positioning balls 50 are positioned in the front-rear and left-right directions by fitting into the retaining holes 52a and 52b provided at predetermined positions. The front beam portion 28a and the rear beam portion 28b support the recording head 10 via the positioning balls 50. The front beam section 28a and the rear beam section 28b require sufficient rigidity. In this embodiment, the front beam section 28a and the rear beam section 28b are each configured as a substantially rectangular prism-shaped member having a cross section substantially perpendicular to the axial direction (left-right direction) of approximately 50 mm × 30 mm. In this embodiment, this prism-shaped member is formed by welding two sheet metal parts, each made of 2.0 mm thick sheet metal and processed so that the cross section substantially perpendicular to the axial direction has a substantially U-shape, with the open sides facing each other (see the AA cross section in Figure 7).

[0043] Two pillars, a front right pillar 29a and a front left pillar 29b, are connected to the lower part of the front beam section 28a, and one pillar, a rear pillar 29c, is connected to the lower part of the rear beam section 28b. The front right pillar 29a, the front left pillar 29b, and the rear pillar 29c each extend along the direction of gravity (substantially parallel in this embodiment), that is, in a direction intersecting (substantially perpendicular in this embodiment) the front beam section 28a and the rear beam section 28b. The front right pillar 29a is located on the right side, and the front left pillar 29b is located on the left side. The rear pillar 29c is located between the front right pillar 29a and the front left pillar 29b in the left-right direction (substantially in the center in this embodiment). The front right pillar 29a, the front left pillar 29b, and the rear pillar 29c need to have sufficient rigidity. In this embodiment, the front right pillar portion 29a, the front left pillar portion 29b, and the rear pillar portion 29c are each made of sheet metal parts that are processed so that the cross section that is approximately perpendicular to the axial direction (vertical direction) is approximately U-shaped (see Figure 7).

[0044] In this embodiment, support wheels (wheels, casters) 30a, 30b, and 30c are provided at the lower ends of the front right pillar 29a, the front left pillar 29b, and the rear pillar 29c, respectively. The support wheels 30a, 30b, and 30c are placed on the substantially horizontal upper surface of the table 200, which is fixed so as not to move relative to the housing 2500 of the print module 2000. In this embodiment, the support wheels 30a, 30b, and 30c are configured to move the frame 100 in the front-to-rear direction. This makes it possible to pull the print belt unit 2200 forward relative to the table 200 (housing 2500) for maintenance, for example, or to adjust the position of the print belt unit 2200 in the front-to-rear direction. However, the present invention is not limited to this configuration, and the frame 100 does not necessarily need to be provided with wheels 30. In this case, the front right pillar portion 29a, the front left pillar portion 29b, and the rear pillar portion 29c are in direct contact with the table 200. The print belt unit 2200 may be configured to be able to move integrally with the recording portion 2300 (recording head 10) in a state where it is arranged. Here, in the print module 2000, the parts other than the elements that can move together with the frame body 100, such as the housing 2500 and the table 200, are also referred to as the "print module main body."

[0045] In this way, in this embodiment, the frame 100 is configured to contact the table 200 (print module body) at three points: the support wheels 30a, 30b, and 30c. This allows the frame 100, despite its high rigidity, to be supported by the table 200 (print module body) without any play.

[0046] On the other hand, since the frame 100 is supported at two points on the front side but one point on the rear side, it is conceivable that the rear side may be twisted in the vertical direction around the support point depending on the rigidity of the beams, etc. Therefore, in this embodiment, as shown in Fig. 7, the frame 100 has, as reinforcing members, a right extension 31a, a left extension 31b, a right connection portion (right connection plate) 32a, and a left connection portion (left connection plate) 32b.

[0047] That is, the right extension 31a and the left extension 31b are connected to the lower part of the rear beam section 28b. The right extension 31a is disposed in a position facing the front right pillar section 29a in the longitudinal direction, and the left extension 31b is disposed in a position facing the left pillar section 29b in the longitudinal direction. The front right pillar section 29a and the right extension 31a are connected by a right connection section 32a. The front left pillar section 29b and the left extension 31b are connected by a left connection section 32b. Neither the right extension 31a nor the left extension 31b is in contact with the table 200. In this manner, the frame 100 is configured to suppress twisting of the rear side by connecting the front side, which is supported at two points, and the rear side, which is supported at one point. In this embodiment, the front right pillar section 29a, the front left pillar section 29b, the rear pillar section 29c, and the right extension 31a and the left extension 31b have substantially the same configuration. The presence or absence of support rings 30a, 30b, 30c differentiates the functions of the front right pillar portion 29a, the front left pillar portion 29b, and the rear pillar portion 29c, and the right extension portion 31a and the left extension portion 31b. Support rings are not provided at the lower ends of the right extension portion 31a and the left extension portion 31b. By using the same parts in this manner, an increase in the number of part types is suppressed. In addition, in this embodiment, the right connection portion 32a and the left connection portion 32b are each configured as a plate-shaped member formed from sheet metal.

[0048] The connecting portions of the various parts (beams, pillars, extensions, and connections) that make up the frame 100 are fixed by any fixing means such as fastening or welding (a combination of multiple means is also possible).

[0049] In this way, the print belt unit 2200 is configured to receive the pressure of the recording head 10 (position the recording head 10 relative to the frame 100) by the frame 100 configured as described above, which is independent of the platen unit 26.

[0050] In this embodiment, the right connecting portion 32a and the left connecting portion 32b are provided only on one side surface of the front right pillar portion 29a and the front left pillar portion 29b in the left-right direction, respectively. However, additional connecting portions 37a and 37b (shown by dashed lines in FIG. 7 ) may be provided on the other side surface. A bottom plate 36 ( FIG. 7 ) may be provided to connect at least two (or all) of the front right pillar portion 29a, the front left pillar portion 29b, the rear pillar portion 29c, the right extension portion 31a, and the left extension portion 31b. The number of pillar portions constituting the frame 100 is not limited to that of this embodiment. For example, four or more pillar portions may be provided when a separate mechanism for suppressing rattle is provided. For example, when four pillar portions are provided, pillar portions similar to the rear pillar portion 29c of this embodiment may be provided instead of the right extension portion 31a and the left extension portion 31b of this embodiment, and the rear pillar portion 29c of this embodiment may not be provided. Furthermore, depending on the rigidity of the beam portion, at least some of the extension portion, connection portion, and bottom plate may not be provided. The shapes of the components (beam portion, pillar portion, extension portion, connection portion) constituting the frame body 100 are not limited to those in this embodiment. For example, the pillar portion is not limited to a columnar (rod-shaped) member, but may be a member of another form, such as a wall-shaped member. The connection portion is not limited to a plate-shaped member, but may be a member of another form, such as a columnar (rod-shaped) member. At least some of the components (beam portion, pillar portion, extension portion, connection portion) constituting the frame body 100 in this embodiment may be integrally formed. For example, the beam portion and the pillar portion may be integrally formed as a wall-shaped member. For example, the extension portion and the connection portion may be integrally formed as a wall-shaped member.

[0051] Next, the support structure of the platen unit 26 will be described. The platen unit 26 is disposed between the beam portion 28a and pillar portions 29a, 29b on both ends of the print belt 25 in the width direction and the beam portion 28b and pillar portion 29c. In this embodiment, the front beam portion 28a is provided with two support shafts, a front right support shaft 33a and a front left support shaft 33b, as platen unit support portions (FIG. 7). In this embodiment, the front right support shaft 33a and the front left support shaft 33b are provided so as to protrude toward the platen unit 26 from a side surface 35a on the platen unit 26 side (rear side) extending in the left-right direction of the front beam portion 28a. In addition, the rear beam portion 28b is provided with two support shafts, a rear right support shaft 33c and a rear left support shaft 33d, as platen unit support portions (FIG. 7). In this embodiment, the rear right support shaft 33c and the front left support shaft 33d are provided so as to protrude toward the platen unit 26 from a side surface 35b of the rear beam portion 28a on the platen unit 26 side (front side), which extends in the left-right direction. In this embodiment, the support shafts 33a, 33b, 33c, and 33d are each formed of a cylindrical member extending in the front-rear direction. As described above, the platen unit 26 is provided with a front right support receiving portion 264a, a front left support receiving portion 264b, a rear right support receiving portion 264c, and a rear left support receiving portion 264d as support receiving portions (FIG. 3). The support shafts 33a, 33b, 33c, and 33d of the frame 100 support the support receiving portions 264a, 264b, 264c, and 264d of the platen unit 26, respectively. In this manner, the platen unit 26 is supported by the frame 100. In this embodiment, the platen unit 26 is supported by the frame 100 such that the support receiving portions 264a to 264d of the platen unit 26 are placed on the support shafts 33a to 33d of the frame 100, respectively. That is, in this embodiment, the support shafts 33a to 33d enter the support receiving portions 264a to 264d, which have a generally U-shaped cross section, from the lower openings and come into contact with the support receiving portions 264a to 264d. In this way, the platen unit 26 is supported by the frame 100 via the support receiving portions 264a to 264d and the support shafts 33a to 33d.

[0052] In this way, the print belt unit 2200 is configured to receive the pressure of the recording head 10 and to support the platen unit 26 separately by the frame 100 which is independent of the platen unit 26 .

[0053] The print belt unit 2200 may have a gap adjustment unit that adjusts the distance between the print head 10 and the platen unit 26 (the conveyance surface 25a of the print belt 25) by raising and lowering the platen unit 26. This gap adjustment unit may be configured to raise and lower the platen unit support unit, for example. For example, the support shafts 33a-33d serving as the platen unit support unit may be eccentric shafts, and an actuator such as a motor may rotate the support shafts 33a-33d. Instead of the support shafts 33a-33d, an eccentric cam may be used as the platen unit support unit. The gap adjustment unit raises and lowers the platen unit 26 depending on the thickness of the sheet S being conveyed, for example, to maintain a substantially constant distance (print gap) between the surface of the sheet S and the print head 10. This allows for stable image quality regardless of the thickness of the sheet S. A more specific example of the gap adjustment unit will be described in Example 2.

[0054] <Effects> Next, the effects of this embodiment will be described. The left diagram of Fig. 9 is a schematic cross-sectional view showing a partial configuration of the print module 2000 when the recording head 10 is not pressed against the frame 100. The right diagram of Fig. 9 is a schematic cross-sectional view showing a partial configuration of the print module 2000 when the recording head 10 is pressed against the frame 100. Note that in Fig. 9, deformation of the frame 100 is exaggerated for the sake of explanation.

[0055] When the recording head 10 is pressed against the frame 100, the beams 28a, 28b and pillars 29a-29c below the pressure applying portion are compressed in the vertical direction. This compression also reduces the height of the support shafts 33a-33d supporting the platen unit 26 from the table 200 (print module body) (changing from h to h' in FIG. 9). Even when the recording head 10 is pressed against the frame 100, the platen unit 26 receives no pressure and is therefore not deformed. Due to this effect, the distance (g in FIG. 9) between the recording head 10 and the transport surface 25a of the print belt 25 remains almost unchanged before and after the recording head 10 is pressed against the frame 100.

[0056] In this embodiment, the recording head 10 is pressed against the frame 100 by the pressure unit 14. As described above, in this case, the pressure tends to be large, especially in a configuration where a large number of recording heads 10 are provided, and therefore the effect of this embodiment is particularly pronounced. However, the present invention is not limited to this configuration. In conventional configurations, depending on the weight of the recording head, even if the recording head is not pressed against the platen plate by the pressure unit, the platen plate may deform, making it difficult to properly maintain the distance between the recording head and the conveying surface of the print belt. Therefore, the present invention is also effective in a configuration in which the recording head 10 is not pressed against the frame 100 by the pressure unit 14 (a configuration in which the recording head 10 is pressed against the frame 100 by its own weight).

[0057] As described above, the image forming apparatus (inkjet recording apparatus) 1 of this embodiment includes a belt unit (print belt unit) 2200 including an endless belt (print belt) 25 that carries and conveys the sheet S on a conveying surface 25a, a platen unit 26 that is provided on the inner peripheral surface of the belt 25 and slidably supports the belt 25, a recording head 10 that is provided opposite the platen unit 26 across the belt 25 and that ejects a recording liquid onto the sheet S conveyed by the belt 25, and a recording bed 10 that is provided between the belt unit 2200 and the recording bed 1. The belt unit 2200 has a support structure (frame) 100 disposed on the seat 200, the support structure 100 including recording head support portions (upper surfaces of the beam portions 28a, 28b) 34a, 34b that support the recording head 10 by receiving a load from the recording head 10, and platen unit support portions (support shafts) 33a-33d that are provided separately from the recording head support portions 34a, 34b and support the platen unit 26 so that the platen unit 26 is not subjected to a load from the recording head 10. The belt unit 2200 may be provided with an adjustment portion that moves the platen unit 26 to change the distance between the conveyance surface 25a and the recording head 10. In this embodiment, the support structure 100 is in contact with the seat 200 via wheels (support wheels) 30a-30c and is movable relative to the seat 200 by the wheels 30a-30c. In this embodiment, the image forming apparatus 1 also includes a plurality of recording heads 10a to 10h. The image forming apparatus 1 also includes a pressure unit 14 that applies pressure to the recording heads 10 toward the support structure 100. In this embodiment, the support structure 100 includes recording head support units 34a and 34b, beam units 28a and 28b that extend along the direction of movement of the transport surface 25a, and pillar units 29a to 29c that are provided between the beam units 28a and 28b and the seat surface 200 and support the beam units 28a and 28b relative to the seat surface 200. In this embodiment, the beam units 28a and 28b are provided with platen unit support units 33a to 33d. In this case, the beam units 28a and 28b may be provided with an adjustment unit that moves the platen unit 26 to change the distance between the transport surface 25a and the recording heads 10.In this embodiment, the pillar portions 29a to 29c are in contact with the seat surface 200 via the wheels 30a to 30c, and the support structure 100 is movable relative to the seat surface 200 by the wheels 30a to 30c.

[0058] In this embodiment, in particular, the support structure 100 includes a first beam portion (front beam portion) 28a that is disposed on one end side in the width direction of the belt 25, has a recording head support portion 34a, and extends along the moving direction of the conveying surface 25a, a second beam portion (rear beam portion) 28b that is disposed on the other end side in the width direction of the belt 25, has a recording head support portion 34b, and extends along the moving direction of the conveying surface 25a, and a second beam portion (rear beam portion) 28b that is disposed between the first beam portion 28a and the seat surface 200 at one end side of the first beam portion 28a in the moving direction of the conveying surface 25a, and is disposed between the first beam portion 28a and the seat surface 200. a first pillar portion (front right pillar portion) 29a that supports the beam portion 28a; a second pillar portion (front left pillar portion) 29b that is provided between the first beam portion 28a and the seat surface 200 on the other end side of the first beam portion 28a in the movement direction of the conveying surface 25a and supports the first beam portion 28a relative to the seat surface 200; and a third pillar portion 29c that is provided between the second beam portion 28a and the seat surface 200 between the first pillar portion 29a and the second pillar portion 29b in the movement direction of the conveying surface 25a and supports the second beam portion 28b relative to the seat surface 200. In this embodiment, the support structure 100 has a first extension portion 31a connected to one end of the second beam portion 28b in the movement direction of the transfer surface 25a and extending toward the seat surface 200, a second extension portion 31b connected to the other end of the second beam portion 28b in the movement direction of the transfer surface 25a and extending toward the seat surface 200, a first connection portion 32a connected to the first pillar portion 29a and the first extension portion 31a, and a second connection portion 32b connected to the second pillar portion 29b and the second extension portion 31b. In this embodiment, the platen unit support portions 33a to 33d are provided on the first beam portion 28a and the second beam portion 28b, respectively. In this case, the first beam portion 28a and the second beam portion 28b may each be provided with an adjustment portion that moves the platen unit 26 so as to change the distance between the transport surface 25a and the recording head 10.In addition, in this embodiment, the first pillar portion 29a, the second pillar portion 29b, and the third pillar portion 29c are in contact with the seat surface 200 via wheels 30a, 30b, and 30c, respectively, and the support structure 100 is movable relative to the seat surface 200 by the wheels 30a, 30b, and 30c.

[0059] As described above, according to this embodiment, even if a load from the recording head 10 is applied to the print belt unit 2200, it is possible to appropriately maintain the distance between the recording head 10 and the transport surface 25a of the print belt 25. In other words, according to this embodiment, it is possible to prevent the accuracy of the distance between the recording head 10 and the transport surface 25a of the print belt 25 from decreasing.

[0060] [Example 2] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of the image forming apparatus of embodiment 1, and detailed explanations thereof will be omitted.

[0061] Fig. 10 is a schematic cross-sectional view showing the configuration of a part of the print module 2000 in the inkjet recording apparatus 1 of this embodiment. Fig. 11 is a schematic perspective view of the frame 100 in the inkjet recording apparatus 1 of this embodiment.

[0062] This embodiment differs from the first embodiment in the locations where support shafts 33a to 33d that support the platen unit 26 are provided. In the first embodiment, the support shafts 33a to 33d are provided on the beam portions 28a and 28b. In contrast, in this embodiment, as shown in Figures 10 and 11, the support shafts 33a to 33d are provided on the pillar portions 29a and 29b and the extension portions 31a and 31b. That is, in this embodiment, the front right support shaft 33a is provided on the front right pillar portion 29a, the front left support shaft 33b is provided on the front left pillar portion 29b, the rear right support shaft 33c is provided on the right extension portion 31a, and the rear left support shaft 33d is provided on the left extension portion 31b. In addition, in this embodiment, as shown in FIG. 11, support plates 39 are attached to the front right pillar portion 29a, the front left pillar portion 29b, the right extension portion 31a, and the left extension portion 31b to support each support shaft (only the support plates 39 of the right extension portion 31a and the left extension portion 31b are shown).

[0063] In this embodiment, the front right support receiving portion 264a, the front left support receiving portion 264b, the rear right support receiving portion 264c, and the rear left support receiving portion 264d are provided on the bottom of the platen unit 26, but they may also be provided on the side portions of the platen unit 26 as in the first embodiment. In addition, in a configuration in which the extensions 31a and 31b are not provided, the platen unit support portions (support shafts, etc.) may be provided on the rear pillar portion 29c. Furthermore, some of the platen unit support portions (support shafts, etc.) may be provided on the beam portion, and other parts of the platen unit support portions (support shafts, etc.) may be provided on the pillar portion or the extension portion.

[0064] In the configuration of this embodiment, the support shafts 33a to 33d are moved further downward than in the configuration of embodiment 1, which provides more space around the support shafts 33a to 33d, thereby providing an advantage in that, for example, there are fewer design constraints regarding the gap adjustment unit described in embodiment 1.

[0065] Note that when the recording head 10 is pressed against the frame 100, the fluctuation in the distance (g in FIG. 10) between the recording head 10 and the conveying surface 25a of the print belt 25 may be larger in this embodiment than in the first embodiment. This is because the deformation of the beam portions 28a and 28b is superimposed on the deformation of the pillar portions 29a, 29b, and 29c. However, if the rigidity of the beam portions 28a and 28b is sufficiently high, the fluctuation in this distance can be sufficiently suppressed. For example, in this embodiment, as in the first embodiment, the front beam portion 28a and the rear beam portion 28b are each formed of a substantially rectangular prism-shaped member having a cross section approximately perpendicular to the axial direction (left-right direction) of approximately 50 mm × 30 mm. Also, in this embodiment, as in the first embodiment, the prism-shaped member is formed by welding two sheet metal parts each having a thickness of 2.0 mm and machined so that the cross section approximately perpendicular to the axial direction is approximately U-shaped, with the openings facing each other. For example, when such beam portions 28a and 28b are used, even if the recording head 10 applies a pressure of about 800 N to the frame 100, the variation in the distance between the recording head 10 and the conveyance surface 25a of the print belt 25 is about 5 μm or less. For example, this level of variation is often sufficient for the accuracy required of the inkjet recording device 1.

[0066] Next, an example of a gap adjustment unit will be described. Fig. 12 is a schematic perspective view of an example of a gap adjustment unit 40 provided on the pillar portions 29a, 29b and the extension portions 31a, 31b. Fig. 13 is a schematic diagram showing an example of the control configuration of the gap adjustment unit 40. In this example, the four gap adjustment units 40 provided on the pillar portions 29a, 29b and the extension portions 31a, 31b have the same configuration, so the description will focus on one gap adjustment unit 40. Note that Fig. 12 shows the front right pillar portion 29a, and for convenience, the support plate 39 is omitted from the illustration.

[0067] In this example, the gap adjustment unit 40 includes an eccentric cam 41 that functions as a platen unit support unit and as an elevation operating unit that raises and lowers the platen unit 26, a drive shaft 42 that transmits a rotational driving force to the eccentric cam 41, and a drive unit 43 that rotationally drives the drive shaft. In this example, the eccentric cam 41 and at least a portion of the drive shaft 42 are disposed within the pillar portion 29a. The drive shaft 42 is rotatably supported by the pillar portion 29a and a support plate 39 (not shown in FIG. 12). The eccentric cam 41 supports each of the support receiving portions 264a, which have a generally U-shaped cross section, by inserting it into the lower opening. The drive unit includes a drive source such as a motor and a drive transmission member (such as a gear or a belt) that transmits the driving force from the drive source to the drive shaft 42. For example, the platen unit 26 can be raised and lowered by synchronously rotating the eccentric cams 41 of the gap adjustment units 40 by the same phase via the drive shafts 42 of the respective drive units 43. The operation of the drive units 43 can be controlled by a control unit (control circuit) 60 that controls the operation of the print module 2000 or the inkjet recording apparatus 1. The control unit 60 includes a CPU (arithmetic processing unit) as an arithmetic processing means, a storage unit such as a ROM or RAM as a storage unit, and an input / output unit that exchanges signals between the control unit 60 and external devices. An operation unit 61 provided in the inkjet recording apparatus 1 is also connected to the control unit 60. The operation unit 61 includes an input unit that can input information related to print settings to the control unit 60 based on an operation by an operator, and a display unit that displays information to the operator under the control of the control unit 60.

[0068] For example, the phase of the eccentric cam 41 corresponding to the distance between the recording head 10 and the platen unit 26 (the transport surface 25a of the print belt 25) can be preset and stored in the memory of the control unit 60 depending on the type (thickness, etc.) of the sheet S. Furthermore, for example, prior to printing, information regarding the type of sheet S to be used for printing is input to the control unit 60 from the operation unit 61 based on an operation by an operator. Based on the input information regarding the type of sheet S, the control unit 60 rotates each eccentric cam 41 using the drive unit 43 of the gap adjustment unit 40 in accordance with the settings previously stored in the memory, thereby positioning the eccentric cam 41 at a predetermined phase. As a result, each eccentric cam 41 acts on each support receiving portion 264a to 264d, raising or lowering the platen unit 26 to a predetermined height. As a result, the distance between the recording head 10 and the platen unit 26 (the transport surface 25a of the print belt 25) can be adjusted to a predetermined distance.

[0069] The gap adjustment unit 40 may be capable of adjusting the distance between the recording head 10 and the platen unit 26 (transport surface 25a of the print belt 25) to any distance within a predetermined range in accordance with information input from the operation unit 61 to the control unit 60. Furthermore, the control unit 60 may be configured to control the operation of the gap adjustment unit 40 based on operations on an external device such as a personal computer connected to the inkjet recording apparatus 1, instead of or in addition to operations on the operation unit 61. Furthermore, the gap adjustment unit 40 is not limited to a configuration in which it is operated by an actuator, and may be configured to be operated manually by an operator.

[0070] As described above, in this embodiment, the pillar portions 29a and 29b are provided with the platen unit support portions 33a and 33b. In this case, the pillar portions 29a and 29b may be provided with adjustment portions (gap adjustment portions) 40 that move the platen unit 26 so as to change the distance between the transport surface 25a and the recording head 10. In this embodiment, particularly, the platen unit support portions 33a to 33d are provided on the first pillar portion (front right pillar portion) 29a, the second pillar portion (front left pillar portion) 29b, the first extension portion (right extension portion) 31a, and the second extension portion (left extension portion) 31b, respectively. In this case, the first pillar portion 29a, the second pillar portion 29b, the first extension portion 31a, and the second extension portion 31b may be provided with adjustment portions 40 that move the platen unit 26 so as to change the distance between the transport surface 25a and the recording head 10, respectively. The adjustment unit 40 can be configured to move the platen unit 26 by moving the platen unit support parts 33a to 33d so as to change the distance between the transport surface 25a and the recording head 10. For example, the adjustment unit 40 can be configured to move the platen unit 26 by rotating eccentric rotors (eccentric cams, eccentric shafts, etc.) that constitute the platen unit support parts 33a to 33d.

[0071] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained, and, for example, the degree of freedom in designing the gap adjusting portion 40 can be improved. [Explanation of symbols]

[0072] 10. Recording head 25 Printed Belt 26 Platen unit 27 Suction device 28a, 28b Beam section 29a~29c Pillar section 30a~30c support wheel 31a, 31b extension 32a, 32b connection 33a~33d Support shaft 100 frame 200 tables 261 Sliding surface 264a~264d Support part 2000 Print Module 2200 Print Belt Unit 2300 Recording Department S seat

Claims

1. a belt unit including an endless belt that carries and transports a sheet on a transport surface, and a platen unit that is provided on an inner peripheral surface side of the belt and slidably supports the belt; a recording head that is disposed opposite the platen unit across the belt and that ejects a recording liquid onto a sheet that is conveyed by the belt; a seat for placing the belt unit and the recording bed; and an image forming apparatus characterized in that the belt unit has a support structure that is placed on the seat surface and includes: a recording head support portion that receives a load from the recording head and supports the recording head; and a platen unit support portion that is provided separately from the recording head support portion and supports the platen unit so that the platen unit does not receive the load from the recording head.

2. The support structure includes: a beam portion provided with the recording head support portion and extending along the moving direction of the transport surface; a pillar portion provided between the beam portion and the seat surface and supporting the beam portion with respect to the seat surface; 2. The image forming apparatus according to claim 1, further comprising:

3. 3. The image forming apparatus according to claim 2, wherein the platen unit support portion is provided on the beam portion or the pillar portion.

4. 4. The image forming apparatus according to claim 3, wherein an adjustment unit is provided on the beam portion or the pillar portion on which the platen unit support portion is provided, the adjustment unit moving the platen unit so as to change the distance between the transport surface and the recording head.

5. 5. The image forming apparatus according to claim 4, wherein the adjustment section moves the platen unit by moving the platen unit support section so as to change the distance between the transport surface and the recording head.

6. 6. The image forming apparatus according to claim 5, wherein the adjustment section moves the platen unit by rotating an eccentric rotor that constitutes the platen unit support section.

7. 3. The image forming apparatus according to claim 2, wherein the pillar portion is in contact with the seat surface via wheels, and the support structure is movable relative to the seat surface by the wheels.

8. The support structure includes: a first beam portion disposed at one end side in the width direction of the belt, the first beam portion having the recording head support portion and extending along the moving direction of the conveying surface; a second beam portion disposed on the other end side of the belt in the width direction, the second beam portion having the recording head support portion and extending along the moving direction of the conveying surface; a first pillar portion provided between the first beam portion and the seat surface on one end side of the first beam portion in the movement direction of the conveying surface, the first pillar portion supporting the first beam portion relative to the seat surface; a second pillar portion provided between the first beam portion and the seat surface on the other end side of the first beam portion in the movement direction of the conveying surface, the second pillar portion supporting the first beam portion relative to the seat surface; a third pillar portion provided between the second beam portion and the seat surface, between the first pillar portion and the second pillar portion in the movement direction of the conveying surface, and supporting the second beam portion with respect to the seat surface; 2. The image forming apparatus according to claim 1, further comprising:

9. The support structure includes: a first extension portion connected to the second beam portion at one end side of the second beam portion in the moving direction of the conveying surface and extending toward the seat surface; a second extension portion connected to the second beam portion at the other end side of the second beam portion in the moving direction of the conveying surface and extending toward the seat surface; a first connection portion connected to the first pillar portion and the first extension portion; a second connection portion connected to the second pillar portion and the second extension portion; 9. The image forming apparatus according to claim 8, further comprising:

10. 9. The image forming apparatus according to claim 8, wherein the platen unit support portion is provided on each of the first beam portion and the second beam portion.

11. 11. The image forming apparatus according to claim 10, wherein the first beam section and the second beam section are each provided with an adjustment section that moves the platen unit so as to change the distance between the transport surface and the recording head.

12. 10. The image forming apparatus according to claim 9, wherein the platen unit support portions are provided on the first pillar portion, the second pillar portion, the first extension portion, and the second extension portion, respectively.

13. 13. The image forming apparatus according to claim 12, wherein the first pillar portion, the second pillar portion, the first extension portion, and the second extension portion are each provided with an adjustment portion that moves the platen unit so as to change the distance between the transport surface and the recording head.

14. 14. The image forming apparatus according to claim 11, wherein the adjustment unit moves the platen unit by moving the platen unit support unit so as to change the distance between the transport surface and the recording head.

15. 15. The image forming apparatus according to claim 14, wherein the adjustment section moves the platen unit by rotating an eccentric rotor that constitutes the platen unit support section.

16. 10. The image forming apparatus according to claim 8, wherein the first pillar portion, the second pillar portion, and the third pillar portion are each in contact with the seat surface via wheels, and the support structure is movable relative to the seat surface by the wheels.

17. 2. The image forming apparatus according to claim 1, wherein the belt unit is provided with an adjustment section that moves the platen unit so as to change the distance between the transport surface and the recording head.

18. 2. The image forming apparatus according to claim 1, wherein the support structure is in contact with the seat surface via wheels and is movable relative to the seat surface by the wheels.

19. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises a plurality of the recording heads.

20. 20. The image forming apparatus according to claim 1, further comprising a pressure unit that presses the recording head toward the support structure.

Images