Sheet drying device and image forming apparatus

Abstract

To provide a sheet drying device capable of preventing a sheet from being damaged by heat, and an image forming apparatus.SOLUTION: The recording device X1 includes a second conveying unit 7, a heater 12, and a sheet-cooling unit 14, and the sheet-cooling unit 14 includes a metallic upper roller 141 supported so as to be capable of changing its posture between a contact position capable of coming into contact with an upper surface of the sheet conveyed by the second conveying unit 7 and a retreat position retreating from the upper surface of the sheet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet drying device and an image forming apparatus. [Background technology]

[0002] Inkjet image forming apparatuses have been known that include a sheet drying device that heats and dries a sheet after ink images have been formed on it using a heater or the like. The sheet drying device dries the ink on the sheet while it is being transported, for example, by applying heat to the sheet while it is being transported by a transport belt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-121194 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a jam occurs in the feed path of the next sheet while the heater is heating and drying the sheet, the heater stops the heating operation. However, even if the heater is stopped, the sheet may be overheated by residual heat from the heater, causing discoloration or burning of the sheet during transport.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet drying device and an image forming apparatus that can prevent damage to a sheet due to heat. [Means for solving the problem]

[0006] A sheet drying device according to one aspect of the present invention includes a sheet conveying section having a conveying belt and conveying a sheet after ink image formation that is held on the upper surface of the conveying belt, a heater disposed opposite the upper surface of the conveying belt and heating the sheet held on the conveying belt, and a first metallic roller body supported so that its position can be changed between a contact position where it can contact the upper surface of the sheet conveyed by the sheet conveying section and a retracted position where it is retracted from the upper surface of the sheet.

[0007] An image forming apparatus according to another aspect of the present invention includes an image forming unit that forms an ink image on a sheet, and the sheet drying device that dries the sheet on which the ink image has been formed by the image forming unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent damage to the sheet due to heat. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of a cooling roller unit according to an embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating an example of a procedure of the seat cooling process executed by the control unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of the present invention, and does not limit the technical scope of the present invention.

[0011] First, an inkjet recording apparatus X1 (hereinafter abbreviated as "recording apparatus X1") according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 shows a state in which a first transport unit 5 of the recording apparatus X1 is disposed at a recording position where printing can be performed by the recording unit 3. In Fig. 1, the first transport unit 5 is shown by a dashed line when it is disposed at a retracted position a predetermined distance below the recording position.

[0012] 1, recording device X1 is an example of an image recording device according to the present invention, and records an ink image on a sheet based on an inkjet recording method. Recording device X1 includes a paper feed cassette 1, a paper feed section 2, a recording section 3 (an example of an image forming section according to the present invention), a first transport unit 5, an elevating mechanism 6, a second transport unit 7 (an example of a sheet transport section according to the present invention), a heater 12 (an example of a heating section according to the present invention), a sheet cooling unit 14, a maintenance unit 8, a control section 90 (see FIG. 3), and a housing 11 that houses or supports these components.

[0013] The second conveying unit 7, the heater 12, and the sheet cooling unit 14 constitute the sheet drying device of the present invention.

[0014] Four transport paths 15 (15A, 15B, 15C, 15D) are provided inside the housing 11. The first transport path 15A guides a sheet from the paper feed cassette 1 to the recording unit 3. The second transport path 15B guides a sheet from the second transport unit 7 to the discharge port 17. The third transport path 15C guides a sheet from the second transport unit 7 to the intermediate tray 13 for switchback, and is generally also referred to as a switchback transport path. The fourth transport path 15D guides a sheet on which an image has been recorded from the intermediate tray 13 to the recording unit 3. The second transport path 15B, the third transport path 15C, and the fourth transport path 15D are examples of downstream transport paths in the present invention.

[0015] Further, the conveying path 15 is provided with a plurality of sheet detection sensors 61 (an example of a sheet detection unit of the present invention) that detect the presence or absence of a sheet and detect the leading or trailing edge of a sheet.

[0016] The recording device X1 is a printer that executes printing processing based on input image data. Note that the image forming device of the present invention is not limited to printers that record images on sheets based on an inkjet recording method, but can also be applied to copiers, facsimile machines, multifunction machines, and the like that have a printing function.

[0017] The paper feed cassette 1 is provided at the bottom of the housing 11. The paper feed cassette 1 stores sheets to be printed by the recording device X1. The sheets are sheet-like recording media, such as so-called printing paper. Of course, the sheets are not limited to printing paper, and may be recording media such as overhead projector sheets or cloth.

[0018] The paper feed unit 2 is a feeding mechanism including a pickup roller 21 and a feeding roller 22. A retard roller 221 is provided in a position facing the feeding roller 22. The pickup roller 21 picks up sheets one by one from the paper feed cassette 1. The feeding roller 22 feeds the sheets picked up by the pickup roller 21 to the first conveying path 15A.

[0019] A pair of conveying rollers 23 for conveying a sheet is provided at an appropriate position in the first conveying path 15A. The pair of conveying rollers 23 includes a drive roller and a driven roller that are pressed against each other. The pair of conveying rollers 23 conveys the sheet fed to the first conveying path 15A toward the pair of registration rollers 24.

[0020] The pair of registration rollers 24 is provided in front of the recording unit 3. The pair of registration rollers 24 includes a drive roller and a driven roller that are pressed against each other. The pair of registration rollers 24 transports the sheet to the recording unit 3 at a predetermined transport timing (image writing start timing).

[0021] A first transport unit 5 and a recording unit 3 are disposed downstream of the pair of registration rollers 24 in the transport direction D1.

[0022] The recording unit 3 has a plurality of line heads 31 corresponding to the colors black, cyan, magenta, and yellow, and a head frame 35 that supports them. The head frame 35 is supported by the housing 11. In this embodiment, the recording unit 3 has four line heads 31 corresponding to the four colors described above. Note that the number of line heads 31 is not limited to the four described above, and it is sufficient that the recording unit 3 has at least one.

[0023] The line head 31 is a so-called line-head type recording head. In other words, the recording device X1 is a so-called line-head type inkjet recording device. The line head 31 is long in a width direction (a direction perpendicular to the paper surface of FIG. 1) perpendicular to the sheet conveyance direction D1, and specifically, the width of the line head 31 corresponds to the width of the widest sheet to be conveyed. In other words, the line head 31 has a plurality of ink nozzles capable of ejecting ink across the entire width of the sheet. Therefore, the line head 31 can record an ink image on the sheet without scanning in the width direction.

[0024] The line heads 31 are spaced apart at predetermined intervals along the sheet transport direction D1. The lower surface of each line head 31 is an ink ejection surface. A large number of ink nozzles for ejecting ink are provided on the ink ejection surface.

[0025] The recording unit 3 records an image on a sheet transported by the first transport unit 5. The recording unit 3 records an image on a sheet by ejecting ink from the ink nozzles of each line head 31. The ink ejection method of the line head 31 may be, for example, a piezo method that uses a piezo element to eject ink, or a thermal method that generates bubbles by heating to eject ink.

[0026] The recording device X1 is equipped with ink tanks (not shown) containing ink corresponding to the respective colors of black, cyan, magenta, and yellow. The ink tanks are connected to the respective line heads 31 by ink tubes (not shown). The line heads 31 are replenished with ink from the corresponding ink tanks through the ink tubes.

[0027] The first transport unit 5 is disposed below the recording unit 3. The first transport unit 5 transports the sheet in the transport direction D1 while making the sheet face the ink ejection surface of the line head 31. Specifically, the first transport unit 5 includes a paper transport belt 37 on which the sheet is placed, a plurality of tension rollers 38 that tension the paper transport belt 37, and a unit frame (not shown) that supports these.

[0028] The distance between the paper transport belt 37 and the ink ejection surface is adjusted so that the gap between the surface of the sheet and the ink ejection surface during image recording is, for example, 1 mm.

[0029] When the tension roller 38 is rotated by a driving force transmitted from a driving unit such as a motor, the paper conveying belt 37 rotates. This enables the first conveying unit 5 to convey the sheet in the conveying direction D1. When the sheet supplied from the paper feeding unit 2 reaches the first conveying unit 5, the sheet is conveyed by the first conveying unit 5 toward the second conveying unit 7 via the recording unit 3. Note that the first conveying unit 5 may be provided with a suction unit (not shown) that sucks air through a number of through holes formed in the paper conveying belt 37 in order to attract the sheet to the paper conveying belt 37.

[0030] The lifting mechanism 6 is provided below the first transport unit 5. The lifting mechanism 6 supports the first transport unit 5 from below and raises and lowers the first transport unit 5 up and down relative to the line head 31. That is, the lifting mechanism 6 moves the first transport unit 5 up and down, thereby moving the first transport unit 5 and the line head 31 closer and farther apart. Specifically, the lifting mechanism 6 moves the first transport unit 5 between a recording position (position indicated by a solid line in FIG. 1) where printing by the recording unit 3 is possible, and a retracted position (position indicated by a dashed line in FIG. 1) that is a predetermined distance below the recording position.

[0031] The retracted position is the position where the first transport unit 5 is lowest in the vertical direction and is farthest from the line head 31. When the first transport unit 5 is in the retracted position, it becomes possible to remove sheets remaining in the first transport unit 5. Furthermore, when the first transport unit 5 is in the retracted position, it becomes possible for the maintenance unit 8 to move into the space that is vacant below the recording unit 3.

[0032] The maintenance unit 8 is disposed at a predetermined standby position (the position shown in FIG. 1) when not printing. The standby position is a position determined below the second transport unit 7, downstream of the recording unit 3 in the transport direction D1. The maintenance unit 8 is a mechanism for maintaining or restoring the ejection performance of the line head 31, and includes a cap unit 9 and a wiping unit 10. With the maintenance unit 8 disposed in the space below the recording unit 3, the capping operation that covers the ink nozzles on the ink ejection surface by the cap unit 9 and the wiping operation by the wipe unit 10 become possible.

[0033] As shown in FIG. 1, the second transport unit 7 is provided downstream of the recording unit 3 in the transport direction D1. The second transport unit 7 transports a sheet on which an ink image has been recorded by the recording unit 3 in the transport direction D1. As shown in FIG. 2, the second transport unit 7 includes a transport belt 7A (an example of a transport belt of the present invention) on which the sheet is placed, a pair of tension rollers 7B and 7C that tension the transport belt 7A, and a frame that supports these. The sheet on which the ink image has been recorded by the recording unit 3 is transported in the transport direction D1 by the second transport unit 7 while being held on the top surface of the transport belt 7A.

[0034] As shown in FIG. 1, a drying heater 12 is provided above the second conveying unit 7. The heater 12 is a heating device that supplies heat toward the image recording surface (upper surface) of the sheet on the conveying belt 7A to heat the sheet, thereby drying the ink image on the sheet. The heater 12 is, for example, an infrared heater that emits infrared rays in response to power supply. When a sheet to be heated is conveyed onto the conveying belt 7A of the second conveying unit 7, the control unit 90 drives the heater 12 to start heating. Then, when the sheet is discharged from the conveying belt 7A in the conveying direction D1, the control unit 90 stops driving the heater 12.

[0035] 1, a sheet cooling unit 14 is provided downstream in the conveying direction D1 from the second conveying unit 7. The sheet cooling unit 14 has an upper roller 141 (an example of a first roller body of the present invention) whose posture can be changed between a predetermined contact position and a predetermined retracted position, and a drive roller 142 (an example of a second roller body of the present invention) that contacts the roller surface of the upper roller 141 and drives it to rotate.

[0036] The contact position is a position where the roller surface of the upper roller 141 can come into contact with the upper surface of the sheet being transported by the second transport unit 7. The retracted position is a position where the roller surface of the upper roller 141 retracts upward from the upper surface of the sheet.

[0037] 2, the upper roller 141 is formed to have a length equal to or greater than the width of the maximum sheet that can be conveyed by the second conveying unit 7, more specifically, approximately the same length as the width of the conveying belt 7A. The drive roller 142 is also formed to have the same length as the upper roller 141.

[0038] With the upper roller 141 disposed at the contact position, when the driving roller 142 is rotationally driven by a driving force transmitted from a driving unit such as a motor, the upper roller 141 is rotated accordingly.

[0039] In this embodiment, both the upper roller 141 and the drive roller 142 are made of metal. At least the outer surfaces of the upper roller 141 and the drive roller 142 are made of a metal with good thermal conductivity (for example, aluminum, copper, iron, etc.). It is desirable that both the upper roller 141 and the drive roller 142 are made of metal, but it is sufficient that at least the upper roller 141 is made of metal.

[0040] 2, the upper roller 141 is supported by a support mechanism 18 so as to be rotatable between the contact position and the retracted position. The support mechanism 18 includes a support shaft 181, a pair of arm units 182 attached to both ends of the support shaft 181, a gear 183 attached to one end of the support shaft 181, and a motor 185 having an output gear 184 meshed with the gear 183. The arm unit 182 extends from the support shaft 181 to the upstream side in the conveying direction D1, and the upper roller 141 is rotatably supported at its extending end.

[0041] The motor 185 is driven and controlled by the control unit 90, which will be described later, so that the upper roller 141 can rotate between the contact position and the retracted position. When the recording device X1 is operating normally, the upper roller 141 is located at the retracted position. On the other hand, when an abnormality occurs in the recording device X1 and the heating process by the heater 12 is interrupted, the upper roller 141 is located at the contact position.

[0042] The sheet that has passed through heater 12 is transported to either second transport path 15B or third transport path 15C. For example, when the sheet is to be discharged from discharge port 17, the sheet is transported to second transport path 15B. On the other hand, when printing is to be performed on the opposite side of the sheet, the sheet is transported to third transport path 15C.

[0043] 1, a flap 19 for changing the conveyance direction of a sheet is provided at the branch point between the second conveyance path 15B and the third conveyance path 15C. The conveyance direction of the sheet is changed by displacing this flap 19 under the driving force of a solenoid or a motor. Specifically, the control unit 90 controls the driving of a drive unit such as a solenoid or a motor, thereby switching the conveyance destination of the sheet to the second conveyance path 15B or the third conveyance path 15C.

[0044] The second transport path 15B is a path that extends straight from the second transport unit 7 to the left in FIG. 1, and reaches the discharge port 17 formed on the left side surface of the housing 11 in FIG.

[0045] In Figure 1, the third conveying path 15C extends upward along the left side of the housing 11, bends to the right near the top of the housing 11, extends toward the right side of the housing 11, curves downward near the front of the right side of the housing 11, and reaches the intermediate tray 13.

[0046] When double-sided recording is not performed on the sheet, the sheet is conveyed to the second conveying path 15B and discharged from the discharge port 17, which is the exit of the second conveying path 15B, onto a paper discharge tray (not shown).

[0047] An intermediate tray 13 is provided in the upper part of the housing 11, between the recording unit 3 and the third conveying path 15C. The intermediate tray 13 is a sheet support unit that temporarily evacuates the sheet when a switchback operation is performed to turn the sheet over.

[0048] When double-sided recording is performed on a sheet, the sheet with an image recorded on its first side (image recording side) is transported to the third transport path 15C. Once the sheet has been sent into the third transport path 15C, it is further transported downstream in the transport direction by a plurality of transport roller pairs 25 provided in the third transport path 15C. The transport roller pair 25 includes a drive roller 25A and a driven roller 25B that are pressed against each other. During transport by the transport roller pair 25, the drive roller 25A comes into contact with the non-image recording side, and the driven roller 25B comes into contact with the image recording side.

[0049] A pair of transport rollers 28 is provided near the entrance of the intermediate tray 13. The pair of transport rollers 28 includes a drive roller 28A and a driven roller 28B that are pressed against each other. During transport by the pair of transport rollers 28, the drive roller 28A contacts the non-image recording surface, and the driven roller 28B contacts the image recording surface. The pair of transport rollers 28 transports the sheet from the third transport path 15C to the intermediate tray 13. Thereafter, the operation of the pair of transport rollers 28 is temporarily stopped, and then the rotation direction of the drive roller 28A is reversed. This allows the sheet to be turned over, and also allows the sheet on the intermediate tray 13 to be transported to the fourth transport path 15D.

[0050] The fourth transport path 15D extends from the intermediate tray 13 to the right, bends downward, and then curves back to the left at an angle of approximately 180 degrees to reach the pair of registration rollers 24.

[0051] A pair of transport rollers 29 is provided in the fourth transport path 15D. The pair of transport rollers 29 includes a drive roller 29A and a driven roller 29B that are pressed against each other. During transport by the pair of transport rollers 29, the drive roller 29A contacts the non-image recording side, and the driven roller 29B contacts the image recording side. When the inverted sheet is sent into the fourth transport path 15D, the pair of transport rollers 29 transports the sheet further downstream in the transport direction until it reaches the pair of registration rollers 24. The inverted sheet is then transported again to the first transport unit 5 with the second side, on which an image is not recorded, facing upward. This allows the recording unit 3 to record an ink image on the second side.

[0052] Incidentally, if the next sheet to be printed becomes jammed in the first conveying path 15A or between the recording unit 3 and the first conveying unit 5 while the heater 12 is heating and drying the sheet, the heating operation by the heater 12 is stopped for safety reasons. However, even if the heater 12 is stopped, the sheet that has been heated by the residual heat from the heater 12 may become overheated, and the sheet in the second conveying unit 7 may become discolored or burn.

[0053] In contrast, in this embodiment, even if the heating operation on the sheet is interrupted due to a sheet jam or the like, the sheet is cooled by the sheet cooling unit 14, so it is possible to prevent damage to the sheet due to heat.

[0054] [Configuration of control unit 90] Next, the configuration of the control unit 90 will be described with reference to FIG.

[0055] The control unit 90 controls the recording device X1 in an overall manner, and as shown in FIG. 3, includes a CPU 91, a ROM 92, and a RAM 93. The CPU 91 is a processor that executes various types of arithmetic processing. The ROM 92 is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 91 to execute various types of processing. The RAM 93 is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 91. The CPU 91 executes the various control programs that are stored in advance in the ROM 92. This results in overall control of the recording device X1.

[0056] 3, the control unit 90 includes various control processing units such as a position control unit 94 and a transport control unit 95. The sheet drying apparatus of the present invention includes the control unit 90 including the position control unit 94 and the transport control unit 95, in addition to the second transport unit 7, the heater 12, and the sheet cooling unit 14. Here, the position control unit 94 is an example of a roller position control unit of the present invention, and the transport control unit 95 is an example of a transport control unit of the present invention.

[0057] A control program for causing the CPU 91 to function as the above-mentioned position control unit 94 and transport control unit 95 is stored in advance in the ROM 92 of the control unit 90. The CPU 91 then executes the control program stored in the ROM 92 to function as the above-mentioned position control unit 94 and transport control unit 95.

[0058] The control program may be recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and may be read from the recording medium and stored in a non-volatile storage device such as a flash memory provided in the recording device X1.

[0059] In this embodiment, when the sheet detection sensor 61 detects a sheet for a predetermined period of time or longer, the control unit 90 determines that a sheet jam has occurred at the position of the sheet detection sensor 61 that detected the state. In this case, the control unit 90 stops the transport of all sheets in the recording device X1. Also, in this case, if the heater 12 is heating, the control unit 90 stops the heating and interrupts the heating operation.

[0060] The position control unit 94 controls the position of the upper roller 141 of the sheet cooling unit 14. Specifically, the position control unit 94 controls the driving of the motor 185 to hold the upper roller 141 at the retracted position during the heating operation by the heater 12. Furthermore, the position control unit 94 controls the driving of the motor 185 to move the upper roller 141 from the retracted position to the contact position when the heating operation by the heater 12 is interrupted.

[0061] The conveyance control unit 95 controls the conveyance of the sheet by the second conveyance unit 7. Specifically, when the heating operation by the heater 12 is interrupted, the conveyance control unit 95 resumes the conveyance of the sheet by the second conveyance unit 7 and conveys the heated sheet.

[0062] Furthermore, when the heating operation by the heater 12 is interrupted, the transport control unit 95 drives and rotates the drive roller 142 of the sheet cooling unit 14.

[0063] In this embodiment, when the sheet detection sensor 61 detects that there is no sheet in the second conveying path 15B, the conveying control unit 95 conveys the sheet and the driving roller 142 is driven to rotate.

[0064] [Sheet cooling process] An example of the procedure of the seat cooling process executed by the control unit 90 will be described below with reference to Fig. 4. Note that the present invention can also be understood as an invention of a seat cooling process that executes one or more steps included in the seat cooling process. Here, Fig. 4 is a flowchart showing an example of the procedure of the seat cooling process.

[0065] The control unit 90 executes a control program stored in the ROM 92 or the like, thereby carrying out the sheet cooling process.

[0066] The steps included in the seat cooling process described below may be executed in a different order as long as the same operational effect is achieved. Furthermore, the seat cooling process described below may be executed by a processor corresponding to the control unit 90, which is the main processor executing the process, or may be executed in a distributed manner by the processor corresponding to the control unit 90 and another processor operating in cooperation with the processor.

[0067] In step S11, the control unit 90 determines whether a sheet jam has occurred in the recording apparatus X1. If it is determined that a sheet jam has occurred, the control unit 90 stops the conveyance of all sheets (S12).

[0068] In the next step S13, the control unit 90 determines whether a heating operation is being performed on the sheet on which the ink image is formed. That is, it determines whether the heater 12 is being driven. If the heater 12 is being driven, the control unit 90 stops the driving of the heater 12 and interrupts the heating operation by the heater 12 (S14). Note that if the heater 12 is being driven, the series of processes ends.

[0069] In step S15, the control unit 90 determines whether or not a sheet is present in the second conveying path 15B downstream of the second conveying unit 7. If no sheet is present in the second conveying path 15B, the control unit 90 moves the upper roller 141 of the sheet cooling unit 14 from the retracted position to the contact position (S16). The control unit 90 also drives and rotates the drive roller 142 of the sheet cooling unit 14 (S17). Thereafter, the control unit 90 resumes sheet conveyance by the second conveying unit 7 (S18). As a result, the sheet on the conveying belt 7A passes through the nip portion between the upper roller 141 and the drive roller 142, and is conveyed to the second conveying path 15B.

[0070] When the sheet is discharged from the conveyor belt 7A, the upper roller 141 is returned to the original retracted position, and the conveyance by the second conveying unit 7 and the rotational driving of the drive roller 142 are stopped, thereby completing the series of processes.

[0071] As described above, in the embodiment of the present invention, the sheet cooling process described above is performed, so that when the sheet that has been heated by the residual heat of the heater 12 on the conveyor belt 7A passes through the nip portion between the upper roller 141 and the drive roller 142, the heat of the sheet is absorbed by the upper roller 141 and the drive roller 142. In other words, the sheet is cooled by the upper roller 141 and the drive roller 142. This makes it possible to prevent discoloration or scorching of the sheet due to the residual heat of the heater 12.

[0072] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0073] <Appendix 1> a sheet conveying section having a conveying belt and configured to convey a sheet on an upper surface of the conveying belt after ink image formation; a heater provided opposite to an upper surface of the conveyor belt and configured to heat a sheet held by the conveyor belt; a first roller body made of metal that is supported so as to be able to change its position between a contact position where it can come into contact with an upper surface of a sheet conveyed by the sheet conveying unit and a retracted position where it retracts from the upper surface of the sheet; A sheet drying device comprising:

[0074] <Appendix 2> 2. The sheet drying device according to claim 1, wherein the first roller body is provided downstream of the sheet conveying section in a sheet conveying direction.

[0075] <Appendix 3> 3. The sheet drying device according to claim 1, wherein the first roller body has a length substantially equal to the width of the conveyor belt.

[0076] <Appendix 4> The sheet drying device according to any one of appendixes 1 to 3, further comprising a roller position control unit that holds the first roller body at the retracted position during a heating operation by the heater and moves the first roller body to the contact position when the heating operation by the heater is interrupted.

[0077] <Appendix 5> 5. The sheet drying device according to claim 4, further comprising a conveyance control unit that causes the sheet conveying unit to convey the sheet when the heating operation by the heater is interrupted.

[0078] <Appendix 6> a second roller body that contacts a surface of the first roller body located at the contact position and rotates the first roller body, thereby causing the first roller body to rotate; 6. The sheet drying device according to claim 5, wherein the transport control unit drives the second roller body when the heating operation by the heater is interrupted.

[0079] <Appendix 7> a downstream conveyance path that guides the sheet heated by the heater downstream of the first roller body in a sheet conveyance direction; a sheet detection unit that detects the presence or absence of a sheet in the downstream conveying path, The sheet drying device described in Appendix 6, wherein the conveying control unit drives the second roller body when the heating operation by the heater is interrupted and the sheet detection unit detects that there is no sheet in the downstream conveying path.

[0080] <Appendix 8> an image forming unit that forms an ink image on a sheet; a sheet drying device according to any one of appendices 1 to 7, which dries a sheet on which an ink image has been formed by the image forming unit; An image forming apparatus comprising: [Explanation of symbols]

[0081] X1: Inkjet recording device 1: Paper cassette 2:Paper feed section 3: Recording section 5: First transport unit 6: Lifting mechanism 7: Second transport unit 8: Maintenance unit 9: Cap unit 10: Wipe unit 12: Heater 13: Intermediate tray 14: Seat cooling unit 15: Transport path 18:Support mechanism 21: Pickup roller 22: Feed roller 23: Transport roller pair 24: Registration roller pair 25: Transport roller pair 28: Transport roller pair 29: Transport roller pair 31: Line Head 35: Head frame 37: Paper transport belt 61: Sheet detection sensor 90: Control unit 94: Position control section 95: Transport control unit 141: Upper roller 142: Drive roller 181: Support shaft 182: Arm section 183: Gear 184: Output gear 185: Motor 221: Retard roller

Claims

1. a sheet conveying section having a conveying belt and configured to convey a sheet on an upper surface of the conveying belt after ink image formation; a heater provided opposite to an upper surface of the conveyor belt and configured to heat a sheet held by the conveyor belt; a first roller body made of metal that is supported so as to be able to change its position between a contact position where it can come into contact with an upper surface of a sheet conveyed by the sheet conveying unit and a retracted position where it retracts from the upper surface of the sheet; A sheet drying device comprising:

2. The sheet drying device according to claim 1 , wherein the first roller body is provided downstream of the sheet conveying section in a sheet conveying direction.

3. The sheet drying device according to claim 1 or 2, wherein the first roller body has a length substantially equal to a width of the conveyor belt.

4. 3. The sheet drying device according to claim 1, further comprising a roller position control unit that holds the first roller body at the retracted position during a heating operation by the heater and moves the first roller body to the contact position when the heating operation by the heater is interrupted.

5. The sheet drying device according to claim 4 , further comprising a conveyance control unit that controls the sheet conveyance unit to convey the sheet when the heating operation by the heater is interrupted.

6. a second roller body that contacts a surface of the first roller body located at the contact position and rotates the first roller body, thereby causing the first roller body to rotate; The sheet drying device according to claim 5 , wherein the transport control unit drives the second roller body when the heating operation by the heater is interrupted.

7. a downstream conveyance path that guides the sheet heated by the heater downstream of the first roller body in a sheet conveyance direction; a sheet detection unit that detects the presence or absence of a sheet in the downstream conveying path, The sheet drying device according to claim 6, wherein the conveying control unit drives the second roller body when the heating operation by the heater is interrupted and the sheet detection unit detects that there is no sheet in the downstream conveying path.

8. an image forming unit that forms an ink image on a sheet; the sheet drying device according to claim 1 or 2, which dries a sheet on which an ink image has been formed by the image forming unit; An image forming apparatus comprising:

Images