Image forming device

Abstract

To provide an image forming device that can suppress a sheet conveyed by a re-conveying part from causing printing jam in a machine of the image forming device and from dropping off in the machine of the image forming device even at the time of stopping a printing operation.SOLUTION: An image forming device comprises: a conveying part 20 that has an endless conveying belt 223, and conveys a sheet P while placing the sheet on an upper-side placement surface 223a of the conveying belt 223; an image forming part 30 that forms an image on a surface of the sheet P conveyed by the conveying part 20; a re-conveying part 50 that receives the sheet P from the conveying part 20 on the downstream side of the image forming part 30 and re-conveys the sheet P to the upstream side of the image forming part 30 of the conveying part 20; a lower-side suction part 55 that adsorbs the sheet P onto a lower-side placement surface 223b of the conveying belt 223; and a sheet holding part 56 that holds the sheet P separated from the lower-side placement surface 223b of the conveying belt 223 accompanying stopping of suction motion of the lower-side suction part 55, at the time of stopping printing operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Conventionally, among image forming devices such as copiers and printers, there are known ones capable of double-sided printing, in which an image is formed on one side of a sheet of paper, and then the sheet is transported back to the image forming section without being ejected, and an image is formed on the other side (see, for example, Patent Document 1).

[0003] In this type of image forming device capable of double-sided printing, a re-conveying section is generally provided, separate from a conveying section that conveys paper to the image forming section, that reverses the conveying direction of the paper conveyed from the conveying section, turns the paper over relative to the conveying section, and then sends it again to the upstream side of the image forming section from the conveying section. In this image forming device, the conveying direction of the paper is divided by a branching member provided downstream of the conveying section, and when an image is formed on only one side, the paper is divided into an output tray once the image has been formed on one side, and when an image is formed on both sides, the paper is divided into the re-conveying section and conveyed again to the image forming section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-144830 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in image forming apparatuses according to the prior art, a method is adopted in which the transport path of a re-conveyance unit that returns paper that has been printed on one side to the upstream side of the image forming unit in the transport path of the transport unit is configured with a large number of guide rollers or the like (see re-conveyance unit 50 in FIG. 3 described later). However, if the long transport path of the re-conveyance unit is configured with components separate from the components of the transport unit, it leads to an increase in the size of the image forming apparatus and an increase in the production cost of the image forming apparatus.

[0006] Therefore, the inventors of the present application have considered using the endless conveyor belt that constitutes the conveyance path of the conveyor unit to also constitute the conveyance path of the re-conveyor unit (see re-conveyor unit 50 in FIG. 1 , described later). Specifically, the conveyance path of the conveyor unit is constituted by the upper support surface of the conveyor belt, and the conveyance path of the re-conveyor unit is constituted by the lower support surface of the conveyor belt (the lower support surface moves in the opposite direction from the upper support surface). By adopting this structure, it is not necessary to provide a separate conveyor belt for the re-conveyor unit in addition to the conveyor belt for the conveyor unit, which prevents the image forming apparatus from becoming larger and reduces the manufacturing cost of the image forming apparatus. Additionally, this structure simplifies the structure of the re-conveyor unit, thereby improving the stability of paper conveyance.

[0007] However, if the conveyance belt that constitutes the conveyance path of the conveyance unit also constitutes the conveyance path of the re-conveyance unit, the paper conveyed by the re-conveyance unit will continue to be conveyed to the downstream process by the conveyance belt even when the printing operation is stopped. As a result, the paper conveyed by the re-conveyance unit may collide with other paper in the downstream process (e.g., paper on which an image has been formed previously and that is in the heating unit or reversing unit in the re-conveyance unit), causing a print jam inside the image forming device, or the paper may fall off in the conveyance path of the downstream process due to misalignment in the downstream process. Such situations require users to perform the cumbersome task of removing the paper from the image forming device, necessitating ingenuity in the product design of image forming devices.

[0008] In general, in an image forming device, the conveying belt that constitutes the conveying section is controlled to continue operating even when a printing stop command is issued in order to prevent the paper being conveyed to the conveying section from colliding with the image forming section such as an inkjet head, and the above-mentioned situation is caused by the operation of this conveying belt.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an image forming device that can prevent paper being transported by the re-transport section from causing a print jam inside the image forming device or falling off inside the image forming device, even when printing operation is stopped. [Means for solving the problem]

[0010] The present disclosure mainly solves the above-mentioned problems by: a conveying section having an endless conveying belt and configured to convey a sheet-shaped recording medium by placing it on an upper side of the conveying belt; an image forming unit that forms an image on the surface of the recording medium conveyed by the conveying unit; a re-conveying unit that receives the recording medium from the conveying unit downstream of the image forming unit, places the recording medium on a lower placement surface of the conveying belt, conveys the recording medium in a direction opposite to the conveying direction of the conveying unit, and sends the recording medium again to the upstream side of the image forming unit from the conveying unit; a first suction unit that adsorbs the recording medium conveyed by the re-conveyance unit onto the lower placement surface of the conveyance belt; a recording medium holding section disposed below the lower placement surface of the conveyor belt, the recording medium being released from the lower placement surface of the conveyor belt as the first suction section stops its suction operation when the printing operation is stopped, and the recording medium being held in a state in which the recording medium can be re-adsorbed onto the lower placement surface of the conveyor belt when the first suction section resumes its suction operation; The image forming apparatus includes: [Effects of the Invention]

[0011] According to the image forming device of the present disclosure, even when printing operations are stopped, it is possible to prevent the paper being transported by the re-transporting section from causing a print jam inside the image forming device or falling off inside the image forming device. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram showing the main functional configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 3] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a conventional technique. [Figure 4] FIG. 1 is a diagram illustrating an example of the configuration of a paper holding unit of an image forming apparatus according to an embodiment of the present invention. [Figure 5] 1 is a flowchart showing an operation when a printing operation of an image forming apparatus according to an embodiment of the present invention is stopped; [Figure 6] FIG. 10 is a diagram showing a schematic configuration of an image forming apparatus according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted.

[0014] [Overall configuration of image forming device] The configuration of an image forming apparatus according to one embodiment of the present invention (hereinafter referred to as "image forming apparatus 1") will be described below with reference to Figures 1 and 2. The image forming apparatus 1 according to this embodiment is an inkjet type image forming apparatus.

[0015] Fig. 1 is a diagram showing a schematic configuration of image forming apparatus 1. Fig. 2 is a block diagram showing the main functional configuration of image forming apparatus 1. In Fig. 1, the upward direction in the drawing corresponds to the vertically upward direction when image forming apparatus 1 is in use, and the downward direction in the drawing corresponds to the vertically downward direction when image forming apparatus 1 is in use.

[0016] Fig. 3 is a diagram showing a schematic configuration of an image forming apparatus 1a according to the prior art, and is presented here for the convenience of explanation to enable comparison between the configuration of the image forming apparatus 1 according to this embodiment and the configuration of the image forming apparatus 1a according to the prior art.

[0017] The image forming apparatus 1 includes a paper feed section 10, a conveying section 20, an image forming section 30, a fixing section 40, a re-conveying section 50, a paper discharge section 60, and a control section 100.

[0018] Under the control of the control unit 100, the image forming apparatus 1 transports paper P stored in the paper feed unit 10 to the image forming unit 30 using the transport unit 20, and the image forming unit 30 ejects ink onto the paper P to form an image. The image forming apparatus 1 transports the paper P on which the image has been formed to the fixing unit 40, fixes the image on the paper P, and then transports the paper P to the paper discharge unit 60. Furthermore, when double-sided printing is to be performed on the paper P, the image forming apparatus 1 transports the paper P that has been printed on one side and is transported by the transport unit 20 again to the upstream side of the image forming unit 30 in the transport unit 20 using the re-transport unit 50.

[0019] In this embodiment, paper P such as plain paper or coated paper is shown as an example of a recording medium on which an image is formed by the image forming device 1, but in addition to paper, various sheet-like recording media such as fabric or sheet-like resin, on whose surface ink can be fixed, can also be used as the recording medium to which the image is applied.

[0020] The paper feed unit 10 has a paper feed tray 11 that stores paper sheets P, and a supply unit 12 that supplies paper sheets P from the paper feed tray 11 to the conveyance unit 20. In the paper feed unit 10, the supply unit 12 conveys the paper sheets P stacked in the paper feed tray 11, thereby supplying the paper sheets P to the conveyance unit 20.

[0021] The transport unit 20 includes an aligner unit 21, a transport path unit 22, a branching unit 23, a heating unit 24, and an upper suction unit 25.

[0022] The aligner unit 21 adjusts the position of the paper P supplied from the paper supply unit 10 in the width direction on the transport path unit 22 .

[0023] The transport path section 22 constitutes a transport path from when the paper P is supplied from the paper feed section 10 to when it passes through the image forming section 30 and is discharged to the paper discharge section 60. The transport path section 22 is constituted by an endless transport belt 223 stretched over a driven roller 221 and a drive roller 222 that are arranged in parallel at a predetermined distance. In the transport path section 22, the drive roller 222 is rotated at a predetermined speed by the rotational drive of a sub-scanning motor (not shown), thereby rotating the transport belt 223. By this operation, the paper P placed on the upper placement surface 223a of the transport belt 223 is transported in the direction of arrow A.

[0024] Here, the front side of the conveyor belt 223 is a placement surface on which the paper P is placed in close contact, and the conveyor belt 223 has an upper placement surface 223a located above the driven roller 221 and the drive roller 222, and a lower placement surface 223b located below the driven roller 221 and the drive roller 222. When the conveyor belt 223 rotates, the upper placement surface 223a of the conveyor belt 223 moves in the direction of arrow A, and the lower placement surface 223b of the conveyor belt 223 moves in the direction of arrow B, which is opposite to the direction of arrow A.

[0025] In the image forming apparatus 1 according to this embodiment, the upper side loading surface 223a of the conveying belt 223 forms part of the conveying path section 22 of the conveying section 20, and the lower side loading surface 223b of the conveying belt 223 forms part of the re-conveying path section 51 of the re-conveying section 50.

[0026] Hereinafter, when referring to the "conveying direction," it means the direction of arrow A in the conveying path section 22, and it means the direction of arrow B in the re-conveying path section 51. Furthermore, when referring to the "upstream side" and the "downstream side," it means the "upstream side" and the "downstream side" based on the "conveying direction" of the conveying path section 22 and the re-conveying path section 51, respectively.

[0027] In addition, the conveying belt 223 (including the upper side loading surface 223a and the lower side loading surface 223b) is provided with openings (not shown) to allow the air sucked by the upper side suction section 25 and the lower side suction section 55 to pass through.

[0028] In FIG. 1, the conveying path section 22 uses separate conveying belts at the image forming section 30 and at the fixing section 40, but these may be configured with a single conveying belt.

[0029] The branching processing unit 23 is disposed downstream of the conveying path unit 22 in the conveying direction (direction of arrow A) of the fixing unit 40, and distributes the paper P conveyed to the conveying unit 20 to either the printed paper output tray 61 of the paper output unit 60, the unsuccessfully printed paper output tray 62 of the paper output unit 60, or the re-conveying unit 50. The branching processing unit 23 is configured, for example, by a branching member (for example, a claw member) that can distribute the conveying direction of the paper P.

[0030] The branching processing unit 23 operates under the control of the control unit 100. For example, in the single-sided printing mode, the branching processing unit 23 forms an image on one side of the paper P, and then sends the paper P to the printed paper output tray 61. In the double-sided printing mode, the branching processing unit 23 first forms an image on one side of the paper P, and then sends the paper P to the re-conveying unit 50, and then, after images are formed on both sides of the paper P, sends the paper P to the printed paper output tray 61. In the paper output mode, the branching processing unit 23 sends the paper P transported by the transporting unit 20 to the failed print paper output tray 62 of the paper output unit 60.

[0031] The heating unit 24 is disposed upstream of the conveying path unit 22 in the conveying direction (direction of arrow A) of the image forming unit 30, and heats the printing surface (i.e., the upper surface) of the paper P fed to the paper feed unit 10. The heating unit 24 is configured, for example, by a heating roller that heats the paper P while applying pressure to it.

[0032] The upper suction section 25 (corresponding to the "second suction section" of the present invention) adsorbs the paper P, which is placed on and transported on the upper loading surface 223a of the transport belt 223, to the upper loading surface 223a of the transport belt 223. The upper suction section 25 is configured by, for example, an air suction mechanism arranged inside the upper loading surface 223a of the transport belt 223.

[0033] The operation of the upper suction unit 25 is controlled under the control of the control unit 100. The upper suction unit 25 is typically controlled to maintain an ON state not only during printing operation but also when printing operation is stopped (for example, during an emergency stop based on a user command). This is because the image forming apparatus 1 controls the operation of the conveyor belt 223 so that it continues to operate even when printing operation is stopped. That is, the image forming apparatus 1 is configured such that the upper suction unit 25 maintains an ON state even when printing operation is stopped, thereby preventing the paper P conveyed by the conveyor unit 20 from colliding with the image forming unit 30, such as an inkjet head.

[0034] The image forming unit 30 is disposed opposite the upper placement surface 223a of the conveyor belt 223, and forms an image on the surface of the paper P conveyed by the conveyor unit 20. The image forming unit 30 has a plurality of (four in this case) head units 31, and is disposed so as to be spaced a predetermined distance from the upper placement surface 223a of the conveyor belt 223 in the conveyance path unit 22. The four head units 31 are configured to be able to eject different types of ink, and in this case, the ink ejected by each of the four head units 31 corresponds to one of four colors of ink: yellow (Y), magenta (M), cyan (C), and black (K).

[0035] The head unit 31 forms an image by, for example, a single-pass method in which ink is sequentially ejected at predetermined intervals to different positions in the transport direction in accordance with the transport of the paper P. Note that the image forming unit 30 is not limited to the single-pass method, and may be one that forms an image by a scanning method using a carriage that can scan in the width direction of the paper P.

[0036] The fixing unit 40 is disposed downstream in the conveying direction (direction of arrow A) of the image forming unit 30 on the conveying path unit 22. The fixing unit 40 irradiates the paper P placed on the conveying belt 223 with activation energy light such as ultraviolet light, thereby curing and fixing the ink ejected onto the paper P.

[0037] The re-conveying unit 50 is a conveying unit that switches the conveying direction of the paper P conveyed from the conveying unit 20 to the opposite direction (the direction of arrow B) and sends it again to the upstream side of the image forming unit 30 of the conveying unit 20 in order to form an image on the back side of the paper P that has already been printed on one side during double-sided printing. The re-conveying unit 50 is configured so that the image forming apparatus 1 can convey the paper P to the image forming unit 30 twice in total, once when printing on the front side and once when printing on the back side, from the time when a single paper P is supplied to the image forming unit 30 until it is discharged.

[0038] The re-conveying section 50 includes a re-conveying path section 51 , a reversing section 52 , a back-side steering section 53 , a heating section 54 , a lower-side suction section 55 , and a paper holding section 56 .

[0039] The re-conveying path section 51 constitutes a re-conveying path for re-conveying the paper P that has passed through the image forming section 30 in the conveying path section 22 to the upstream side of the image forming section 30 in the conveying path section 22.

[0040] In the image forming apparatus 1 according to this embodiment, at least a part of the re-conveying path section 51 is configured by the lower side mounting surface 223b of the conveyor belt 223. That is, in the image forming apparatus 1 according to this embodiment, the conveyor belt 223 that configures the conveying path of the conveying section 20 is also used to configure the conveying path of the re-conveying section 50.

[0041] For example, the re-conveying path section 51 according to the present embodiment is provided so as to branch off from the conveying path section 22 at the position of the branching processing section 23 (the downstream end position of the conveying path section 22), and is configured to pass through the lower side loading surface 223b of the conveying belt 223, the back steering section 53, the inverting section 52, and the heating section 54 in this order, and then merge with the conveying path section 22 on the upstream side of the aligner section 21. That is, the paper P conveyed through the re-conveying path section 51 is conveyed by the conveying belt 223 (lower side loading surface 223b), and then delivered from the conveying belt 223 (lower side loading surface 223b) to the back steering section 53, the inverting section 52, the heating section 54, and the conveying path section 22 in this order.

[0042] Of the re-conveying path section 51, the paths between the lower side loading surface 223b of the conveying belt 223, the back steering section 53, the inversion section 52, and the heating section 54 are each composed of a conveying roller, a conveying roller, a conveying belt, or the like.

[0043] At the downstream end of the lower loading surface 223b of the conveying belt 223, a belt bending portion 223c is provided for separating the paper P conveyed to the lower loading surface 223b of the conveying belt 223 from the conveying belt 223.

[0044] The reversing unit 52 is provided in the re-conveying path 51 near the junction of the re-conveying path 51 and the conveying path 22. The reversing unit 52 guides the paper P being conveyed along the re-conveying path 51 toward the reversing unit 52 and switches back the paper P, thereby reversing the front and back of the paper P. As a result, the paper P is conveyed to the junction with the conveying path 22 with the back side, on which no image is formed, facing the image forming unit 30.

[0045] The back surface steering unit 53 adjusts the widthwise position of the paper P being transported along the re-transport path unit 51. The back surface steering unit 53 is disposed, for example, in the re-transport path unit 51, downstream of the path formed by the lower-side placement surface 223b of the transport belt 223 and upstream of the reversing unit 52.

[0046] The heating unit 54 is disposed in the re-conveyance path 51 downstream of the reversing unit 52 in the conveyance direction (the direction of arrow B), and heats the back surface (the surface on which no image is formed) of the paper P being conveyed through the re-conveyance path 51. The heating unit 54 is configured, for example, by a heating roller that heats the paper P while applying pressure to it.

[0047] In the image forming apparatus 1a according to the conventional technology, the re-conveying path portion 51a of the re-conveying unit 50 is not configured using the lower side mounting surface 223b of the conveyor belt 223, but is configured by a plurality of rollers 51a provided continuously from one end side to the other end side of the re-conveying path portion 51 (see FIG. 3). Therefore, the image forming apparatus 1a according to the conventional technology has a larger configuration than the image forming apparatus 1 according to this embodiment.

[0048] However, in the image forming apparatus 1 according to this embodiment, the re-conveying path section 51a of the re-conveying section 50 is configured using the lower-side loading surface 223b of the conveying belt 223, and therefore the re-conveying section 50 needs to be equipped with a lower-side suction section 55 and a paper holding section 56. The detailed configurations of the lower-side suction section 55 and the paper holding section 56 will be described later.

[0049] The paper output section 60 is a section where the paper P that has passed through the image forming section 30 and the fixing section 40 by the conveying section 20 is output, and has a printed paper output tray 61 on which the paper P is placed, and an unsuccessfully printed paper output tray 62 on which paper P that has not been printed is placed. The sorting of paper from the conveying section 20 to the printed paper output tray 61 or the unsuccessfully printed paper output tray 62 is performed by the branching processing section 23 of the conveying section 20.

[0050] The control unit 100 includes a CPU 101 (Central Processing Unit), a RAM 102 (Random Access Memory), a ROM 103 (Read Only Memory), and a storage unit 104. The CPU 101 reads a program corresponding to the processing content from the ROM 103, loads it into the RAM 102, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the loaded program. At this time, various data stored in the storage unit 104 is referenced. The storage unit 104 is configured, for example, with a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0051] The control unit 100 generates print data that defines, for example, the amount of ink ejected for each of the four head units 31, and issues operation instructions to drivers (not shown) that control the operation of the four head units 31. The control unit 100 then controls the operation of the four head units 31 so that ink is ejected sequentially at predetermined intervals at different positions in the transport direction as the paper P is transported.

[0052] Furthermore, the control unit 100 controls the operation of the drive roller 222 that rotates the conveyor belt 223, other conveyor rollers (for example, conveyor rollers of the aligner unit 21 and the back surface steering unit 53), etc., in order to control the conveyance of the paper P by the conveyance unit 20 and the re-conveyance unit 50. The control unit 100 also controls the operation of the branching unit 23, and performs a process of allocating the conveyance destination of the paper P.

[0053] In addition, the control unit 100 controls the on / off operation of the upper suction unit 25 and the lower suction unit 55, and controls the adsorption state of the paper P to the upper loading surface 223a of the conveying belt 223 and the adsorption state of the paper P to the lower loading surface 223b of the conveying belt 223 (described later with reference to Figure 5).

[0054] The control unit 100 has modes in which the image forming apparatus 1 operates, for example, a single-sided printing mode, a double-sided printing mode, and a paper ejection mode.

[0055] In the single-sided printing mode, the control unit 100 transports the paper P using the transport unit 20, forms an image on one side of the paper P using the image forming unit 30, and then sends the paper P to the printed paper output tray 61 using the branching processing unit 23.

[0056] In the double-sided printing mode, the control unit 100 sends out the paper P, which has been printed on one side, from the transport unit 20 to the re-transport unit 50, and re-transports the paper P upside down to the upstream side of the image forming unit 30, where the image forming unit 30 performs printing processing again on the paper P. Then, the control unit 100 sends out the paper P, which has been printed on both sides, to the printed paper output tray 61 using the branching processing unit 23.

[0057] In addition, in the paper discharge mode, the control unit 100 operates the conveying unit 20 and the re-conveying unit 50 to send the paper P present in the conveying unit 20 and / or the re-conveying unit 50 to the failed printing paper discharge tray 62 of the paper discharge unit 60 without performing printing processing by the image forming unit 30.

[0058] [Detailed Configuration of Re-conveyance Unit 50 (Lower Suction Unit 55 and Paper Holding Unit 56)] The following describes in detail the configuration of the lower suction unit 55 and the paper holding unit 56 of the re-conveyance unit 50. Note that FIG.

[0059] The lower suction section 55 (corresponding to the "first suction section" of the present invention) adsorbs the paper sheet P placed on the lower loading surface 223b of the conveyor belt 223 and conveyed thereon to the lower loading surface 223b of the conveyor belt 223. In other words, the lower suction section 55 prevents the paper sheet P placed on the lower loading surface 223b of the conveyor belt 223 and conveyed thereon from falling off the lower loading surface 223b during conveyance. The lower suction section 55 is configured, for example, by an air suction mechanism disposed inside the lower loading surface 223b of the conveyor belt 223.

[0060] The lower suction unit 55 is controlled to operate independently of the upper suction unit 25 under the control of the control unit 100. The lower suction unit 55 is typically controlled to switch from an ON state to an OFF state when the printing operation is stopped (for example, in the event of an emergency stop based on a user command) (described later with reference to FIG. 5).

[0061] The paper holding section 56 (corresponding to the "recording medium holding section" of the present invention) is disposed below the lower loading surface 223b of the conveying belt 223, and temporarily holds the paper P that detaches from the lower loading surface 223b of the conveying belt 223 when the lower suction section 55 is turned off when the printing operation stops (for example, when an emergency stop is caused by a stop command from the user).

[0062] The paper holding unit 56 is configured, for example, by a plate member extending in the extension direction of the lower placement surface 223b of the conveyor belt 223, at a position facing the lower suction unit 55, a predetermined distance below the lower placement surface 223b of the conveyor belt 223 (see FIG. 4). The plate member configuring the paper holding unit 56 is arranged, for example, so that its own plate surface is approximately parallel to the lower placement surface 223b, and holds the paper P that leaves the lower placement surface 223b of the conveyor belt 223 when the printing operation is stopped, in a position facing the lower placement surface 223b of the conveyor belt 223. Note that the paper holding unit 56 may be configured by a belt material or a roll support material instead of a plate member.

[0063] As a result, when the printing operation is resumed and the lower suction unit 55 is turned on, the paper P held by the paper holding unit 56 is re-adsorbed to the lower loading surface 223b of the conveyor belt 223 and is conveyed again along the re-conveyance path unit 51. Note that the paper holding unit 56 is disposed away from the lower loading surface 223b of the conveyor belt 223, and is therefore configured not to come into contact with the paper P conveyed to the lower loading surface 223b of the conveyor belt 223 during normal printing operations. In other words, the paper holding unit 56 is disposed so that the image formed on the front side of the paper P will not be deteriorated due to friction with the paper holding unit 56.

[0064] Furthermore, the paper holding unit 56 preferably has an opening 56a that allows the passage of air sucked by the lower suction unit 55 (see FIG. 4). This prevents the paper holding unit 56 from interfering with the suction action of the lower suction unit 55.

[0065] Moreover, the paper holding unit 56 is preferably disposed opposite the lower suction unit 55 so as to cover the entire area where the lower suction unit 55 applies suction force to the paper P (see FIG. 1). This allows the paper holding unit 56 to reliably hold the paper P that leaves the lower loading surface 223b of the conveyor belt 223 when the lower suction unit 55 is turned off.

[0066] Furthermore, the paper holding unit 56 preferably has a variable mechanism that changes the distance (i.e., the distance in the vertical direction) between itself and the lower placement surface 223b of the conveyor belt 223. This makes it possible to adjust the height position of the paper holding unit 56 according to the thickness of the paper P, and prevents the paper P that is placed on the lower placement surface 223b of the conveyor belt 223 and conveyed during normal times (i.e., during printing operation) from rubbing against the paper holding unit 56, thereby preventing the image formed on the paper P from deteriorating in quality.

[0067] The control unit 100 according to this embodiment controls the operation of each unit when the printing operation is stopped (for example, when an emergency stop is performed based on a user command) in consideration of the above-described configuration of the image forming apparatus 1. Specifically, the control unit 100 continues the conveying operation of the conveyor belt 223 even when the printing operation is stopped. The control unit 100 is configured to switch the suction operation of the lower suction unit 55 from ON to OFF while keeping the suction operation of the upper suction unit 25 ON even when the printing operation is stopped, and then, when the printing operation is resumed, switch the suction operation of the lower suction unit 55 from OFF to ON while keeping the suction operation of the upper suction unit 25 ON.

[0068] First, the reason why the control unit 100 keeps the conveying operation of the conveyor belt 223 in a state in which it continues even when the printing operation is stopped is that if the paper P being conveyed by the conveying unit 20 is stopped directly below the image forming unit 30 (i.e., the inkjet head, etc.), the paper P may collide with the image forming unit 30 and damage the image forming unit 30 due to the paper P rising up as the conveying unit 20 accelerates when the conveying operation is resumed. Note that, in order to keep the conveying operation of the conveyor belt 223 in a state in which it continues even when the printing operation is stopped, the control unit 100 keeps the suction operation of the upper suction unit 25 in an on state even when the printing operation is stopped.

[0069] On the other hand, due to the conveying operation of the conveying belt 223, the paper P being conveyed by the re-conveying section 50 will be conveyed even while the printing operation is stopped, and there is a risk that it will collide with other paper in the downstream process, causing a print jam inside the image forming device 1, or that it will fall off in the conveying path of the downstream process due to misalignment in the downstream process.

[0070] Therefore, to avoid such a situation, when the printing operation is stopped, the control unit 100 switches the suction operation of the lower suction unit 55 from on to off, and temporarily removes the paper P that is placed on the lower placement surface 223b of the conveyor belt 223 and is conveyed from the lower placement surface 223b of the conveyor belt 223 and holds it in the paper holding unit 56. Then, when the printing operation is subsequently restarted, the control unit 100 switches the suction operation of the lower suction unit 55 from off to on, and again adsorbs the paper P that is held by the paper holding unit 56 to the lower placement surface 223b of the conveyor belt 223, and conveys it by the re-conveyance unit 50.

[0071] Fig. 5 is a flowchart showing the operation of the image forming apparatus 1 when the printing operation is stopped. Here, the operation of the image forming apparatus 1 when a command to stop the printing operation is received from the user will be described. Note that the flowchart in Fig. 5 shows a process that is executed in order by the control unit 100, for example, in accordance with a computer program.

[0072] In step S1, the control unit 100 determines whether or not a command to stop printing has been issued from the user. If a command to stop printing has been issued from the user (S1: YES), the control unit 100 proceeds to step S2, and if a command to stop printing has not been issued from the user (S1: NO), the control unit 100 ends the series of processes in the flowchart of FIG.

[0073] In step S2, the control unit 100 stops the operation of the image forming unit 30.

[0074] In step S3, the control unit 100 stops the operation of the paper feed unit 10.

[0075] In step S4, the control unit 100 stops the re-conveying operation of the re-conveying unit 50. Note that in this step S4, the control unit 100 stops the conveying operations in the reversing unit 52, the back surface steering unit 53, and the heating unit 54, but does not stop the conveying operation in the conveyor belt 223, allowing it to continue.

[0076] In step S5, the control unit 100 stops the suction operation of the lower suction unit 55. As a result, the paper sheet P that is placed on and transported on the lower loading surface 223b of the transport belt 223 is released from the lower loading surface 223b of the transport belt 223 and is temporarily held by the paper holding unit 56. In step S5, the control unit 100 does not stop the suction operation of the upper suction unit 25 but continues it.

[0077] In step S6, the control unit 100 waits for a command to cancel the print operation stop from the user (S6: NO). If a command to cancel the print operation stop from the user is received (S6: YES), the control unit 100 proceeds to step S7.

[0078] In step S7, the control unit 100 resumes the suction operation of the lower suction unit 55. As a result, the paper sheet P held by the paper holding unit 56 is re-adsorbed to the lower placement surface 223b of the conveyor belt 223.

[0079] In step S8, the control unit 100 restores the re-conveying operation of the re-conveying unit 50. As a result, the sheet P in the re-conveying path 51 is transported upstream of the conveying path 22 of the conveying unit 20. That is, in step S7, the sheet P that was re-adsorbed to the lower-side placement surface 223b of the conveying belt 223 as the suction operation of the lower-side suction unit 55 was restored is re-conveyed upstream of the conveying path 22 of the conveying unit 20.

[0080] In step S9, the control unit 100 transports the paper P in the re-conveying path section 51 (i.e., the paper P whose conveying was resumed in step S8 and which was transported to the upstream side of the conveying path section 22 of the conveying unit 20) to the failed printing paper output tray 62.

[0081] Note that if the printing operation is temporarily stopped during printing, there is a possibility that wrinkles or image degradation may have occurred on the paper P in the re-conveyance path section 51. Therefore, in step S9, after the re-conveyance operation of the re-conveyance section 50 is resumed, the image forming apparatus 1 according to this embodiment is configured to re-convey the paper P in the re-conveyance path section 51 toward the conveyance section 20, and then convey the paper P to the failed print paper output tray 62 without having an image formed on the back side by the image forming section 30. However, the image forming apparatus 1 does not necessarily need to convey the paper P in the re-conveyance path section 51 to the failed print paper output tray 62; the paper P may be re-conveyed toward the conveyance section 20, have an image formed on the back side by the image forming section 30, and then convey the paper P to the printed paper output tray 61.

[0082] In step S10, the control unit 100 restores the operation of the paper feed unit 10.

[0083] In step S11, the control unit 100 resumes the operation of the image forming unit 30.

[0084] By performing the above-described processing, the image forming apparatus 1 according to this embodiment discharges the paper P being transported on the lower loading surface 223b of the conveying belt 223 to the paper discharge section 60 without dropping it into the image forming apparatus 1, even when the printing operation of the image forming apparatus 1 is stopped.

[0085] [effect] As described above, the image forming apparatus 1 according to this embodiment: a conveying section (corresponding to the conveying section 20 in the above embodiment) that has an endless conveying belt and that places a sheet-like recording medium (e.g., paper P) on an upper side placement surface of the conveying belt and conveys the recording medium; an image forming unit (corresponding to the image forming unit 30 in the above embodiment) that forms an image on the surface of the recording medium transported by the transport unit; a re-conveying unit (corresponding to the re-conveying unit 50 in the above embodiment) that receives the recording medium from the conveying unit downstream of the image forming unit, places the recording medium on a lower placement surface of the conveying belt, conveys the recording medium in a direction opposite to the conveying direction of the conveying unit, and sends the recording medium again to the upstream side of the image forming unit from the conveying unit; a first suction unit (corresponding to the lower suction unit 55 in the above embodiment) that adsorbs the recording medium conveyed by the re-conveyance unit onto the lower placement surface of the conveyance belt; a recording medium holding section (corresponding to paper holding section 56 in the above embodiment) that is disposed below the lower loading surface of the conveyor belt and that holds the recording medium, which has been released from the lower loading surface of the conveyor belt as the first suction section stops its suction operation when the printing operation is stopped, in a state in which it can be re-adsorbed onto the lower loading surface of the conveyor belt when the first suction section resumes its suction operation; Equipped with.

[0086] Therefore, according to the image forming device 1 of this embodiment, even when the printing operation is stopped, it is possible to prevent the paper P being transported by the re-transporting section 50 from causing a print jam inside the image forming device 1 or falling off inside the image forming device 1.

[0087] (Variation) FIG. 6 is a diagram showing a schematic configuration of an image forming apparatus 1 according to a modified example.

[0088] The image forming apparatus 1 of this modified example differs from the configuration of the image forming apparatus 1 shown in Figure 1 in that it has a position detection unit 70 that detects the position of the paper P placed on the lower side loading surface 223b of the conveying belt 223 and conveyed.

[0089] The position detection unit 70 is, for example, a media sensor that can detect the passage of the paper P transported on the re-transport path unit 51, and is provided at two positions corresponding to the upstream end and downstream end of the paper holding unit 56.

[0090] The position detection unit 70 detects whether the paper P being transported on the re-transport path unit 51 is present in a position facing the paper holding unit 56. That is, when the suction operation of the lower suction unit 55 is switched from on to off during printing stoppage, and the paper P being placed on the lower placement surface 223b of the transport belt 223 and transported is released from the lower placement surface 223b of the transport belt 223, the position detection unit 70 detects the position of the paper P so that the paper P is securely held by the paper holding unit 56.

[0091] In the image forming apparatus 1 according to this modification, the control unit 100 controls the timing of switching on / off the suction operation of the lower suction unit 55 based on the detection result of the position detection unit 70.

[0092] Specifically, when the printing operation is stopped, the control unit 100 acquires the detection results from the position detection unit 70 and sequentially recognizes the position of the paper P placed on the lower placement surface 223b of the conveyor belt 223 and being conveyed. Then, in step S5 of the operation of the flowchart in Figure 5, when the control unit 100 turns off the suction operation of the lower suction unit 55, the control unit 100 switches the suction operation of the lower suction unit 55 from on to off at the timing when the paper P conveyed by the re-conveyance unit 50 is in a position facing the paper holding unit 56. As a result, the paper P that has detached from the lower placement surface 223b of the conveyor belt 223 as a result of the suction operation of the lower suction unit 55 being turned off is reliably held by the paper holding unit 56.

[0093] As described above, according to the image forming apparatus 1 of this modified example, when the printing operation is stopped, it is possible to reliably prevent the paper P that is placed on the lower side loading surface 223b of the conveying belt 223 and transported from falling inside the image forming apparatus 1.

[0094] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Industrial Applicability]

[0095] According to the image forming device of the present disclosure, even when printing operations are stopped, it is possible to prevent the paper being transported by the re-transporting section from causing a print jam inside the image forming device or falling off inside the image forming device. [Explanation of symbols]

[0096] 1. Image forming device 10 Paper feed section 20 Conveying section 21 Aligner section 22 Conveying path section 23 Branching section 24 Heating section 25 Upper side suction part (second suction part) 30 Image forming unit 31 Head Unit 40 Fixing section 50 Re-feeding section 51 Re-transport path section 52 Reversal section 53 Back steering part 54 Heating section 55 Lower side suction part (1st suction part) 56 Paper holding unit (recording medium holding unit) 56a opening 60 Paper output section 61 Printed paper output tray 62 Printing failure paper output tray 70 Position detection unit 100 control section 223 Conveyor Belt 223a Upper side mounting surface 223b Lower side mounting surface P Paper (recording medium)

Claims

1. a conveying section having an endless conveying belt and configured to convey a sheet-shaped recording medium by placing it on an upper side of the conveying belt; an image forming unit that forms an image on the surface of the recording medium conveyed by the conveying unit; a re-conveying unit that receives the recording medium from the conveying unit downstream of the image forming unit, places the recording medium on a lower placement surface of the conveying belt, conveys the recording medium in a direction opposite to the conveying direction of the conveying unit, and sends the recording medium again to the upstream side of the image forming unit from the conveying unit; a first suction unit that adsorbs the recording medium conveyed by the re-conveyance unit onto the lower placement surface of the conveyance belt; a recording medium holding section disposed below the lower placement surface of the conveyor belt, the recording medium being released from the lower placement surface of the conveyor belt as the first suction section stops its suction operation when the printing operation is stopped, and the recording medium being held in a state in which the recording medium can be re-adsorbed onto the lower placement surface of the conveyor belt when the first suction section resumes its suction operation; An image forming apparatus comprising:

2. the recording medium holding section is spaced downward from the lower-side loading surface of the conveyor belt, extends along the extending direction of the lower-side loading surface at a position facing the first suction section, and is configured by a member that can hold the recording medium that has left the lower-side loading surface of the conveyor belt in a position facing the lower-side loading surface of the conveyor belt. The image forming apparatus according to claim 1 .

3. the member constituting the recording medium holding unit is a plate member or a belt member; The image forming apparatus according to claim 2 .

4. the members constituting the recording medium holding unit are arranged to cover the entire area where the first suction unit applies suction force to the recording medium; 4. The image forming apparatus according to claim 2 or 3.

5. the recording medium holding unit has an opening that allows air sucked by the first suction unit to pass through; The image forming apparatus according to claim 1 .

6. the recording medium holding unit has a variable mechanism that varies the distance between the recording medium holding unit and the lower placement surface of the conveyor belt; The image forming apparatus according to claim 1 .

7. a second suction unit that adsorbs the recording medium onto the upper loading surface of the conveyor belt; a control unit that independently controls on / off of the first suction unit and the second suction unit, the control unit, when the printing operation is stopped, switches the suction operation of the first suction unit from on to off while keeping the suction operation of the second suction unit on, and, when the printing operation is resumed, switches the suction operation of the first suction unit from off to on while keeping the suction operation of the second suction unit on. The image forming apparatus according to claim 1 .

8. a position detection unit that detects the position of the recording medium being transported to the re-transport unit; the control unit switches the suction operation of the first suction unit from on to off at a timing when the position detection unit detects that the recording medium is present at a position facing the recording medium holding unit while the printing operation is stopped. The image forming apparatus according to claim 7 .

9. the re-conveying unit has a reversing unit that switches back the recording medium placed on the lower placement surface of the conveyor belt and conveyed, thereby reversing the recording medium with respect to the conveying unit, and then sends the recording medium again to the upstream side of the image forming unit of the conveying unit. The image forming apparatus according to claim 1 .

10. the image forming unit forms an image on the surface of the recording medium by an inkjet printing method; The image forming apparatus according to claim 1 .

Images