Conveyor and inkjet printer

Abstract

The present invention provides a transport device that can stably transport printed recording media while suppressing image distortion. [Solution] The conveying device comprises an endless belt having a plurality of suction holes penetrating its front and back surfaces, carrying a recording medium on its front surface, a drive roller for driving the endless belt, a driven roller for tensioning the endless belt together with the drive roller, a suction chamber positioned opposite the back surface of the endless belt and having a suction surface for sucking the recording medium through the suction holes, a suction pump connected to the suction chamber and creating a negative pressure state inside the suction chamber, and a conveying roller in contact with the surface of the endless belt, wherein the conveying roller has a through shaft extending in a direction along the axis of the drive roller and at least two rollers rotatably supported on the through shaft, each of which is movable along the through shaft and in contact with the surface of the endless belt outside the area facing the suction surface.

Description

Technical Field

[0001] The present invention relates to a conveying device and an inkjet printer.

Background Art

[0002] Conventionally, in an inkjet printer, in order to stably convey a recording medium, a conveying device is known that adsorbs and conveys the recording medium on the surface of an endless belt having a ventilation structure by making the space on the back side of the endless belt into a negative pressure state.

[0003] For example, Patent Document 1 discloses a printing apparatus including a head unit, an endless conveying belt provided on the downstream side in the printing medium conveying direction of the head unit and having a large number of small holes for adsorbing a printing medium by air negative pressure, a driving roller, a driven roller, a duct disposed directly below the inner peripheral surface of the endless conveying belt, and a suction fan.

[0004] However, in the conventional conveying device as described in Cited Document 1, suction force is generated only in the region above the duct in the endless conveying belt, and suction force is not generated in the region above the driving roller and the driven roller. Therefore, particularly when a relatively small-sized recording medium having a roller diameter close to that of the driving roller or the driven roller passes above the driving roller or the driven roller, sufficient conveying force cannot be ensured for the recording medium, and there is a problem that conveying failures such as being unable to be delivered to downstream processes (paper discharge, drying, etc.) occur. Here, it is also conceivable to provide a conveying roller in the conveying device that sandwiches and conveys the recording medium together with the endless conveying belt. However, in this case, there is a problem that image distortion occurs due to contact between the conveying roller and the printed ink unless the printed ink is sufficiently dried.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of an embodiment of the present invention is to provide a conveying device that can stably convey a recording medium after printing while suppressing image distortion. [Means for solving the problem]

[0006] A conveying device according to one embodiment of the present invention comprises an endless belt having a plurality of suction holes penetrating its front and back surfaces, carrying a recording medium on its front surface, a drive roller for driving the endless belt, a driven roller for tensioning the endless belt together with the drive roller, a suction chamber positioned opposite the back surface of the endless belt and having a suction surface for sucking the recording medium through the suction holes, a suction pump connected to the suction chamber and creating a negative pressure state inside the suction chamber, and a conveying roller in contact with the surface of the endless belt, wherein the conveying roller has a through shaft extending in a direction along the axis of the drive roller and at least two rollers rotatably supported on the through shaft, each of the rollers being movable along the through shaft and in contact with the surface of the endless belt outside the area facing the suction surface. [Effects of the Invention]

[0007] A transport device according to one embodiment of the present invention can stably transport a printed recording medium while suppressing image distortion. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an example of an inkjet printer for cut sheets according to this embodiment. [Figure 2] This is a front view showing an example of the configuration of the conveying device according to this embodiment. [Figure 3] This diagram illustrates the relationship between the transport device and the recording medium according to this embodiment. [Figure 4] This diagram illustrates the relationship between the transport device and the recording medium according to this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0010] The embodiments described below do not limit the present invention to those embodiments. The dimensions, materials, shapes, relative arrangements, etc., of the components described below are intended to be illustrative, and not to limit the scope of the present invention unless otherwise specified. In addition, the size and positional relationships of the members shown in the drawings may be exaggerated for clarity of explanation. In this specification, image formation, recording, printing, and printing are all synonymous.

[0011] <Inkjet printer> Figure 1 is a schematic diagram showing an example of an inkjet printer 100 for cut sheets according to this embodiment. As shown in Figure 1, the inkjet printer 100 of this embodiment includes an ink head 2 that ejects ink using an inkjet method and a transport device 6 that transports a recording medium 11.

[0012] Specifically, the inkjet printer 100 may include an image forming unit 1 having an ink head 2 and a transport device 6, a paper feeding unit 10 for feeding the stacked recording media 11 upstream of the recording media 11 in the transport direction of the image forming unit 1, and a resist adjustment unit 20 for performing resist correction of the recording media 11. The inkjet printer 100 may also include a drying unit 30 for drying the recording media 11 on which an image has been formed by the inkjet method, a paper discharge unit 40 for discharging the dried recording media 11, and a paper reversal transport unit 50 for further forming an image on the back surface of the recording media 11 downstream of the recording media 11 in the transport direction D1 of the image forming unit 1.

[0013] Next, a series of image forming operations for forming an image on the recording medium 11 using the inkjet printer 100 according to this embodiment will be described.

[0014] In Figure 1, the recording media 11, which are initially loaded onto the paper feeding unit 10, are separated and picked up one by one. The paper feeding unit 10 may, for example, have an air separation unit that uses air. The picked-up recording media 11 are transported toward the image forming unit 1 to the resist adjustment unit 20, which is downstream in the transport direction of the recording media 11.

[0015] The recording medium 11, transported from the paper feeding unit 10, reaches the resist adjustment unit 20. In the resist adjustment unit 20, the resist of the recording medium 11 is corrected by a resist roller 21 located inside. The recording medium 11, corrected in the resist adjustment unit 20, is transported to the image forming unit 1 at a predetermined timing.

[0016] The recording medium 11, which has been resist-corrected and transported to the image forming unit 1, is transported to the surface of the endless belt 61. The endless belt 61 has a plurality of suction holes, which will be described later, and the entire recording medium 11 can be held in close contact with the surface of the endless belt 61 by air suction from the back surface. The recording medium 11, which is held in close contact with the surface of the endless belt 61 by air suction, is then transported in the direction of the ink head 2 as the endless belt 61 rotates.

[0017] In the image forming unit 1, multiple ink heads 2 are arranged sequentially along the surface of an endless belt 61, each filled with ink of a predetermined color. Below each ink head 2 corresponding to a color, a recording medium 11 held on the surface of the endless belt 61 is transported, and at a predetermined timing, ink of each color is ejected from the nozzles of the ink heads 2, thereby forming an image on the surface of the recording medium 11.

[0018] The recording medium 11 on which the image has been formed by the image forming unit 1 is transported to the drying unit 30 by the transport device 6. The drying unit 30 is equipped with a drying unit 31, and as the recording medium 11 passes under this drying unit 31, the moisture in the ink evaporates, preventing the recording medium 11 from curling.

[0019] The recording medium 11 that has passed through the drying unit 30 is conveyed to the paper discharge unit 40 and stacked on the paper discharge unit 40 in an orderly alignment state. Further, a paper reversing conveyance unit 50 is provided with a paper reversing unit 51. During double-sided printing, the recording medium 11 is reversed here and then conveyed back to the image forming unit 1 again. After switching the conveyance direction of the recording medium 11 at the paper reversing unit 51, it is conveyed in the direction of the image forming unit 1 by the paper reversing conveyance unit 50.

[0020] Before the recording medium 11 reaches the endless belt 61 again, registration correction is performed by the registration roller 21. The recording medium 11 after registration correction is conveyed to the endless belt 61 and held on the surface of the endless belt 61 with the non-printed back side facing up. Then, in the image forming unit 1, an image is formed on the non-printed back side of the recording medium 11 held on the surface of the endless belt 61 by the ink head 2 in the same manner as described above.

[0021] The double-sided printed recording medium 11 that has passed through the drying unit 30 is conveyed to the paper discharge unit 40 in the same manner as in single-sided printing and stacked on the paper discharge unit 40 in an orderly alignment state.

[0022] In the example shown in FIG. 1, the inkjet printer 100 includes a paper feeding unit 10, a registration adjustment unit 20, an image forming unit 1, a drying unit 30, a paper discharge unit 40, and a paper reversing conveyance unit 50, but may further include other functional units. For example, it may include a pre-processing unit that performs pre-processing of image formation. The inkjet printer 100 may not include the registration adjustment unit 20 or the paper reversing conveyance unit 50.

[0023] The material of the recording medium 11 is not limited, and it may be any material to which ink can adhere temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc. The recording medium 11 may be used, for example, for film products, cloth products such as clothing, building materials such as wallpaper and floor materials, and leather products.

[0024] <Conveying device> Figure 2 is a front view showing an example of the configuration of the conveying device 6 according to this embodiment, and Figures 3 and 4 are diagrams for explaining the relationship between the conveying device 6 and the recording medium 11 according to this embodiment. Figures 3 and 4 show the conveying device 6 as viewed from a direction perpendicular to the conveying surface of the endless belt 61 (plan view).

[0025] As shown in Figures 1 and 2, the conveying device 6 comprises an endless belt 61, a drive roller 62, a driven roller 63, a suction chamber 64, a suction pump 65, and a conveying roller 66. The conveying device 6 may also be equipped with a motor (drive roller motor) 67 for driving the drive roller 62.

[0026] The drive roller 62 drives the endless belt 61, and the driven roller 63 tensions the endless belt 61 together with the drive roller. The endless belt 61 carries the recording medium 11 on the surface of the area tensioned between the drive roller 62 and the driven roller 63, and the surface moves as the drive roller 62 is driven by the motor 67 in the direction of the arrow in the figure, causing it to travel in the recording medium transport direction D1 (hereinafter sometimes referred to as "transport direction D1").

[0027] As shown in Figures 3 and 4, the endless belt 61 has a plurality of suction holes 61a that penetrate both the front and back surfaces. The number, shape, and size of the suction holes 61a are not limited to the examples shown in Figures 3 and 4, and any number, shape, and size can be selected depending on the magnitude of the negative pressure to be generated, for example. The plurality of suction holes 61a may be uniformly or unevenly distributed across the entire endless belt 61.

[0028] In the examples shown in Figures 3 and 4, the suction holes 61a are provided from one end to the other in the width direction of the endless belt 61 (along the axis of the drive roller 62 or driven roller 63). However, they may also be provided only in the area inside the two rollers 662 positioned in the width direction of the endless belt 61 as shown in Figure 4.

[0029] The endless belt 61 can be made of metal such as stainless steel.

[0030] The length of the endless belt 61 in the width direction only needs to be greater than or equal to the length of the recording medium 11 being transported in the width direction (along the axis of the drive roller 62 or driven roller 63).

[0031] The suction chamber 64 is located on the inside (back side) of the endless belt 61 between the drive roller 62 and the driven roller 63. The suction chamber 64 is positioned opposite the back surface of the endless belt 61 and has a suction surface 641 that contacts and sucks the recording medium 11 through the suction holes 61a. The suction surface 641 may have a ventilated configuration, for example, it may have openings, or it may have a mesh structure composed of multiple holes or linear members.

[0032] The suction pump 65 is connected to the suction chamber 64 and creates a negative pressure inside the suction chamber 64 by drawing suction. The negative pressure created by the suction pump 65 generates a suction airflow above the suction chamber 64 that flows into the chamber. Due to this suction airflow, the back surface (inner circumferential surface) of the endless belt 61 is attracted to the suction surface 641 of the suction chamber 64, and the endless belt 61 moves while sliding against the suction surface 641.

[0033] The suction airflow generated at the top of the suction chamber 64 also generates a suction airflow in the suction holes 61a formed in the endless belt 61. As a result, the recording medium 11, which has been transported from the resist adjustment unit 20 and placed on the surface of the endless belt 61, is attracted to the surface of the endless belt 61 by this suction airflow. The recording medium 11 is then printed on by the ink head 2 as it moves across the surface of the endless belt 61, and subsequently detaches from the surface of the endless belt 61 and is passed on to, for example, the drying unit 30.

[0034] Specifically, as shown in Figures 2 and 3, the endless belt 61 has a first region R1, a second region R2, and a third region R3. The second region R2 is the region facing the suction surface 641 and is the region where suction force acts. The first region R1 is the region extending from the upstream end of the second region R2 in the conveying direction D1 to the upstream end of the driven roller 63 and is the region where no suction force acts. The third region R3 is the region extending from the downstream end of the second region R2 in the conveying direction D1 to the downstream end of the drive roller 62 and is the region where no suction force acts.

[0035] The conveyor roller 66 contacts the surface of the endless belt 61. As shown in Figures 2 and 3, the conveyor roller 66 has a through shaft 661 extending in a direction along the axis of the drive roller 62, and at least two rollers 662 rotatably supported on the through shaft 661. Each roller 662 is movable along the through shaft 661 and contacts the surface of the endless belt 61 outside the area facing the suction surface 641. The rollers 662 may be manually movable or automatically movable.

[0036] As shown in Figure 3, when a relatively small recording medium 11 is carried on the surface of an endless belt 61, the position of each roller 662 can be adjusted by moving it along the axis 661 so that it contacts the margin W provided along the outer circumference of the printing area P on the recording medium 11. In the example shown in Figure 3, the positions of two rollers 662 are adjusted so that they contact the margin W located on both sides in the width direction of the recording medium 11. The printing area P refers to the area that has been printed by the ink head 2.

[0037] Furthermore, as shown in Figure 4, when a relatively large recording medium 11 is carried on the surface of the endless belt 61, each roller 662 is moved along the axis 661 from the position shown in Figure 3 to the outside in the width direction of the endless belt 61 so as to contact the margin W of the recording medium 11. This allows the position of the rollers 662 to be adjusted. In the example shown in Figure 4, the positions of the two rollers 662 are adjusted so as to contact the margin W located on both sides in the width direction of the recording medium 11.

[0038] Examples of relatively small recording media 11 include postcard-sized recording media. Examples of relatively large recording media 11 include B2-sized recording media.

[0039] As described above, the roller 662 is movable to a position that contacts the margin W according to the size of the recording medium 11 or the margin setting on the recording medium 11, and contacts only the margin W of the recording medium 11, allowing the recording medium 11 to be transported while being held between the roller 662 and the endless belt 61.

[0040] The roller 662 may be in contact with the surface of the endless belt 61 outside the region facing the suction surface 641 of the suction chamber 64. In the example shown in Figures 2 to 4, the roller 662 is in contact with the surface of the third region R3 of the endless belt 61, specifically, the roller 662 is positioned facing the drive roller 62 via the endless belt 61. The roller 662 may also be in contact with at least one of the surfaces of the first region R1 and the third region R3 of the endless belt 61.

[0041] The conveying device 6 may include an intermediate roller (not shown) positioned between the suction chamber 64 and the drive roller 62, which contacts the back surface of the endless belt 61. In this case, the roller 662 may be positioned opposite the intermediate roller via the endless belt 61. That is, the endless belt 61 has a fourth region R4, which is the region between the downstream end of the second region R2 in the conveying direction D1 and the tangent plane of the outer circumferential surface of the drive roller 62 at the upstream end of the drive roller 62, and the roller 662 may be in contact with the surface of the endless belt 61 in the fourth region R4.

[0042] In the examples shown in Figures 2 to 4, the ink head 2 is positioned opposite the second region R2 of the endless belt 61, but it may also be positioned upstream of the first region R1 of the endless belt 61 in the transport direction D1. When the ink head 2 is positioned opposite the second region R2 of the endless belt 61, that is, when printing is performed on the recording medium 11 in the second region R2, it is preferable that the roller 662 is in contact with the surface of the third region R3 of the endless belt 61. When the ink head 2 is positioned upstream of the first region R1 of the endless belt 61 in the transport direction D1, that is, when printing is performed on the recording medium 11 upstream of the first region R1 in the transport direction D1, the roller 662 may be in contact with the surface of the first region R1 of the endless belt 61.

[0043] The conveying device 6 may be equipped with two conveying rollers 66, where the roller 662 of one conveying roller 66 is in contact with the surface of the first region R1 of the endless belt 61, and the roller 662 of the other conveying roller 66 is in contact with the surface of the third region R3 of the endless belt 61.

[0044] In the direction along the axis of the through shaft 661, the length of the roller 662 should be approximately the same as the length of the margins W provided on both sides of the recording medium 11, and can be, for example, 3 mm or more and 10 mm or less.

[0045] The conveying device 6 may be equipped with a motor (motor for conveying rollers) M for driving the conveying rollers 66. The conveying rollers 66 may be driven by the driving force of the drive rollers 62, or they may be driven by a motor M separate from the motor 67.

[0046] As described above, the conveying device 6 comprises an endless belt 61 having a plurality of suction holes 61a and supporting the recording medium 11 on its surface, a drive roller 62, a driven roller 63, a suction chamber 64 having a suction surface 641, a suction pump 65, and a conveying roller 66. The conveying roller 66 has a through shaft 661 and at least two rollers 662, the rollers 662 are movable along the through shaft 661 and contact the surface of the endless belt 61 outside the area facing the suction surface 641.

[0047] With this configuration, the rollers 662 contact the surface of the endless belt 61 in areas where suction force does not act. As a result, even when the recording medium 11 is supported in that area, the recording medium 11 is held between the rollers 662 and the endless belt 61, ensuring sufficient transport force for the recording medium 11. The transport device 6 can ensure sufficient transport force even for relatively small recording mediums 11 that are close in size to the roller diameter of the drive roller 62 or driven roller 63, thereby suppressing transport defects such as inability to transfer to downstream processes (paper discharge, drying, etc.).

[0048] Furthermore, since the roller 662 is movable along the through axis 661, it can be moved to a position that avoids the printed area P of the recording medium 11 after printing and contacts only the margin W, depending on the size of the recording medium 11 or the margin setting on the recording medium 11. As a result, the transport device 6 can transport the recording medium 11 after printing stably while suppressing image distortion.

[0049] Furthermore, compared to a case where the conveying device 6 does not have conveying rollers 66, the area of ​​the region on which suction force acts in the endless belt 61 can be reduced, and the suction chamber 64 or suction pump 65 can be miniaturized, thus enabling energy savings.

[0050] Each roller 662 can be configured to contact the surface of the endless belt 61 (third region R3) in the transport direction D1 of the recording medium 11, in the region extending from the downstream end of the region facing the suction surface 641 to the downstream end of the drive roller 62. With this configuration, the transport device 6 is suitable for an inkjet printer in which the ink head 2 is positioned facing the second region R2 of the endless belt 61, that is, an inkjet printer in which printing on the recording medium 11 is performed in the second region R2.

[0051] Specifically, even if a normal transport roller is provided that contacts the first region R1, no image distortion occurs regardless of the roller's position because it is before printing on the recording medium 11. However, in the third region R3, since it is after printing on the recording medium 11, image distortion occurs if the roller comes into contact with the printed image. In the transport device 6 of this embodiment, each roller 662 can contact only the margin W of the printed recording medium 11 on the surface of the third region R3, so that the printed recording medium 11 can be transported stably while suppressing image distortion.

[0052] Furthermore, if a transport roller that contacts the second region R2 is provided, in order to avoid the roller contacting the printed image, it is necessary to divide the ink head and place the roller between the divided ink heads. In the transport device 6 of this embodiment, the ink head can be transported while suppressing image distortion of the printed recording medium 11 without having to rearrange the ink head.

[0053] The conveyor roller 66 can be configured to be positioned opposite the drive roller 62 via an endless belt 61. With this configuration, the drive roller 62 can also serve as the opposing member of the conveyor roller 66, and the conveying device 6 does not need to provide a dedicated opposing member, thus reducing the number of parts or the circumference of the endless belt 61, and thus reducing costs.

[0054] The endless belt 61 can be made of stainless steel. This increases the durability of the endless belt 61 against external forces and allows it to withstand high suction pressures.

[0055] The transport device 6 can be configured to include a motor M that drives the transport rollers 66. With this configuration, the transport device 6 can stably transport a wider variety of recording media, such as relatively thin recording media, after printing, while suppressing image distortion.

[0056] The inkjet printer 100 is for cut sheets and is equipped with the transport device 6 of this embodiment. With this configuration, the inkjet printer 100 can stably transport the printing medium 11 while suppressing image distortion.

[0057] Examples of the present invention are as follows: <Aspect 1> An endless belt having multiple suction holes penetrating the front and back surfaces, and supporting a recording medium on the front surface, A drive roller for driving the endless belt, A driven roller that tensions the endless belt together with the drive roller, A suction chamber is positioned opposite the back surface of the endless belt and has a suction surface that sucks the recording medium through the suction hole, A suction pump connected to the suction chamber and which creates a negative pressure state inside the suction chamber, The system includes a conveyor roller that contacts the surface of the endless belt, The conveying roller has a through shaft extending in a direction along the axis of the drive roller, and at least two rollers rotatably supported on the through shaft. Each of the rollers is a conveying device that is movable along the through shaft and contacts the surface of the endless belt outside the area facing the suction surface. <Aspect 2> The conveying device according to embodiment 1 is such that each roller contacts the surface of the endless belt in a region extending from the downstream end of the region facing the suction surface to the downstream end of the drive roller in the conveying direction of the recording medium. <Aspect 3> The conveying device according to embodiment 1 or 2, wherein each of the rollers is positioned opposite the drive roller via the endless belt. <Aspect 4> The conveying device is described in any one of embodiments 1 to 3, wherein the endless belt is made of stainless steel. <Aspect 5> The conveying device is one of any one of embodiments 1 to 4, which includes a motor for driving the conveying rollers. <Aspect 6> This is an inkjet printer for cut sheets equipped with a transport device as described in any one of embodiments 1 to 5. [Explanation of symbols]

[0058] 6. Conveying device 11 Recording media 61 Endless belt 61a Suction hole 62 drive rollers 63 Driven roller 64 Suction Chamber 65 Suction pump 66 Conveyor rollers 100 inkjet printers 641 Suction surface 661 axis 662 Koro D1 Recording medium transport direction M Motor P print area R1 1st area R2 2nd area R3 3rd area W margin [Prior art documents] [Patent Documents]

[0059] [Patent Document 1] Japanese Patent Publication No. 2010-52258

Claims

1. An endless belt having multiple suction holes penetrating the front and back surfaces, and supporting a recording medium on the front surface, A drive roller for driving the endless belt, A driven roller that tensions the endless belt together with the drive roller, A suction chamber is positioned opposite the back surface of the endless belt and has a suction surface that sucks the recording medium through the suction hole, A suction pump connected to the suction chamber and which creates a negative pressure state inside the suction chamber, The system includes a conveyor roller that contacts the surface of the endless belt, The conveying roller has a through shaft extending in a direction along the axis of the drive roller, and at least two rollers rotatably supported on the through shaft. Each of the rollers is movable along the through shaft and contacts the surface of the endless belt outside the area facing the suction surface.

2. The conveying device according to claim 1, wherein each of the rollers abuts the surface of the endless belt in a region extending from the downstream end of the region facing the suction surface to the downstream end of the drive roller in the conveying direction of the recording medium.

3. The conveying device according to claim 2, wherein each of the rollers is positioned opposite the drive roller via the endless belt.

4. The conveying device according to claim 3, wherein the endless belt is made of stainless steel.

5. The conveying device according to claim 4, further comprising a motor for driving the conveying roller.

6. An inkjet printer for cut sheets, equipped with a transport device according to any one of claims 1 to 5.

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