Sheet drying device and image forming system including the same

Abstract

To provide a sheet drying device that can prevent a user from inserting a hand into a high-temperature drying unit and suffering a burn during jam processing in the drying unit and an image forming system including the same.SOLUTION: A sheet drying device comprises a conveyance unit, a drying unit, a main body frame that houses the conveyance unit and the drying unit, an exterior cover attached to the main body frame, an inner cover, a locking mechanism, a temperature detection sensor, and a control unit. The drying unit is disposed so as to face the conveyance unit and heats and dries a sheet on which an image has been formed with moisture-containing ink. The inner cover is disposed between the exterior cover and the drying unit so as to be openable and closable. The locking mechanism locks the inner cover in a closed state. The temperature detection sensor detects the temperature of the drying unit. The control unit locks the inner cover in the closed state by the locking mechanism until the temperature of the drying unit detected by the temperature detection sensor falls below a first temperature.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a sheet drying device for drying a sheet on which an image is printed by an inkjet recording device or the like, and an image forming system including the same.

Background Art

[0002] Conventionally, as a recording device such as a facsimile machine, a copying machine, or a printer, an inkjet recording device that discharges ink onto a sheet to form an image has been widely used. Further, a sheet drying device that heats and dries a sheet (paper) to which ink has been attached by an inkjet recording device is known.

[0003] In a sheet drying device, the drying unit may become hot in order to rapidly dry the ink. At this time, the paper may jam (paper clogging) near the drying unit, and if a user inserts a hand into the drying unit to process the jammed paper, there is a risk of burns.

[0004] As a method for suppressing burns to a user in a high-temperature part, for example, Patent Document 1 discloses a fixing device having a heating plate by a heater of an inkjet type image forming apparatus, and at least a pair of conveyance roller pairs installed on the downstream side in the paper conveyance direction of the heating plate, and a shielding plate disposed near the conveyance roller pair, the tip of which faces the nip position of the conveyance roller pair in a direction orthogonal to the paper conveyance direction and does not enter the paper conveyance path.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the configuration of Patent Document 1, as a measure to prevent burns due to contact with the high-temperature part, a shielding plate is provided to prohibit access to the high-temperature part. However, when processing jammed paper like in a drying device, it is necessary to enable access to the high-temperature part, and thus it was not possible to provide a shielding plate. Also, a method of providing an air layer between the high-temperature part and the place where the user touches to block heat can be considered, but there was a problem that it was difficult to provide an air layer in a device that requires access to the high-temperature part.

[0007] In view of the above problems, an object of the present invention is to provide a sheet drying device capable of preventing a user from inserting a hand into a high-temperature drying part and getting burned during jam processing in the drying part, and an image forming system including the same.

Means for Solving the Problems

[0008] A first configuration of the present invention to achieve the above object is a sheet drying device including a conveyance unit, a drying unit, a main body frame, an exterior cover, an inner cover, a lock mechanism, a temperature detection sensor, and a control unit. The conveyance unit conveys a sheet on which an image is formed with ink containing moisture. The drying unit is disposed opposite to the conveyance unit and heats and dries the sheet. The main body frame houses the conveyance unit and the drying unit. The exterior cover is attachably and detachably mounted on the main body frame. The inner cover is disposed between the exterior cover and the drying unit so as to be openable and closable, restricts access to the drying unit in the closed state, and allows access to the drying unit in the open state. The lock mechanism locks the inner cover in the closed state. The temperature detection sensor detects the temperature of the drying unit. The control unit controls the lock mechanism. The control unit locks the inner cover in the closed state by the lock mechanism until the temperature of the drying unit detected by the temperature detection sensor becomes less than a first temperature.

Effects of the Invention

[0009] According to the first configuration of the present invention, when the drying unit is at a temperature equal to or higher than the first temperature, the inner cover is in the locked state, so it is possible to reliably prevent a user from inserting a hand into the high-temperature drying unit and getting burned when a jam occurs in the drying unit or the like.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0011] [1. Configuration of an Image Forming System Including a Sheet Drying Device] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the internal configuration of an image forming system 200 including the sheet drying device 10 of the present invention. FIG. 2 is a side cross-sectional view around the drying section 40 of the sheet drying device 10 according to an embodiment of the present invention. With reference to FIGS. 1 and 2, an image forming system 200 composed of an image forming device 100 and a sheet drying device 10 will be described.

[0012] The image forming apparatus 100 is an inkjet recording type printer, and includes a paper feeding unit 2 disposed at the lower part of the image forming apparatus 100, an image forming unit 3 disposed above the paper feeding unit 2, and a paper feeding unit 4 that feeds the paper P accommodated in the paper feeding unit 2 to the image forming unit 3.

[0013] The image forming unit 3 includes a recording unit 3a having a plurality of recording heads and a printing conveyance unit 3b disposed opposite to the recording unit 3a. The printing conveyance unit 3b includes an endless printing conveyance belt 5 wound around a plurality of rollers including a driving roller. The paper P conveyed by the paper feeding unit 4 passes below the recording unit 3a in a state of being adsorbed and held on the printing conveyance belt 5 by a paper suction unit (not shown) provided inside the printing conveyance belt 5. The paper P on which a predetermined image is recorded by the image forming unit 3 is discharged from the discharge roller pair 6 and carried into the sheet drying device 10.

[0014] The sheet drying device 10 is disposed adjacent to the image forming apparatus 100 and dries the ink on the paper P discharged from the image forming apparatus 100. The sheet drying device 10 includes a first conveyance unit 20, a preliminary drying unit 30, a drying unit 40, a suction fan unit 50, and a second conveyance unit 70.

[0015] The first conveyance unit 20 includes a driving roller 21a, a driven roller 21b, and a conveyance belt 22. The conveyance belt 22 is wound around the driving roller 21a disposed on the downstream side with respect to the conveyance direction of the paper P (the direction from right to left in FIG. 1, hereinafter simply referred to as the conveyance direction) and the driven roller 21b disposed on the upstream side.

[0016] Paper suction parts 23a and 23b are disposed inside the conveyance belt 22. A number of suction holes (not shown) through which a suction air for adsorbing the paper P to the conveyance belt 22 by negative pressure suction by the paper suction parts 23a and 23b passes are formed in the conveyance belt 22.

[0017] Belt cooling fans 24 are arranged at two locations below the conveyor belt 22. Also, a belt temperature sensor 25 is arranged in contact with and separated from the lower surface of the conveyor belt 22. The belt cooling fan 24 blows cooling air onto the conveyor belt 22 when the temperature detected by the belt temperature sensor 25 reaches a predetermined temperature or higher.

[0018] The preliminary drying section 30 is arranged immediately downstream of the sheet inlet 61 in the conveying direction, and pre-dries the ink on the paper P conveyed from the sheet inlet 61. The preliminary drying section 30 includes a paper blowing fan 31 for blowing air onto the paper P from above and a paper blowing duct 32.

[0019] The drying section 40 is arranged adjacent to the downstream side of the preliminary drying section 30 in the conveying direction, and dries the ink on the paper P that has passed through the preliminary drying section 30. The drying section 40 includes two heating units 41 arranged so as to face the upper surface of the conveyor belt 22.

[0020] The suction fan unit 50 sucks the water vapor generated from the paper P passing through the drying section 40. The suction fan unit 50 includes a suction fan 51 that sucks the air containing water vapor in the drying section 40 and a separation fan 52 that blows separation air for separating the paper P from the conveyor belt 22. The suction fan unit 50 communicates with the space between the conveyor belt 22 and the heating unit 41 via the first duct 53 and communicates with the exhaust port 60 formed in the upper part of the sheet drying device 10 via the second duct 54.

[0021] Also, a plurality of outside air introduction fans 63 for taking in outside air are arranged at appropriate positions inside the sheet drying device 10. Sheet detection sensors 64 and 65 are arranged at the upstream and downstream parts of the first conveying section 20, respectively. The sheet detection sensors 64 and 65 detect that the paper P has passed through the sheet inlet 61 and the sheet outlet 62.

[0022] By the rotational drive of the drive roller 21a, the conveyor belt 22 rotates counterclockwise, causing the paper P carried in from the sheet inlet 61 to sequentially pass through the preliminary drying section 30 and the drying section 40, and be discharged outside the sheet drying device 10 from the sheet outlet 62, or carried into the second conveying section 70.

[0023] The second conveying section 70 is disposed below the drying section 40 and the preliminary drying section 30 with the first conveying section 20 interposed therebetween. The second conveying section 70 includes a reversing conveyance path 70a for reversing the front and back surfaces of the paper P with the dried ink, and a duplex conveyance path 70b for returning the paper P with the reversed front and back surfaces to the image forming apparatus 100 when performing duplex printing on the paper P.

[0024] An arc-shaped retracting path 71 is provided on the downstream side (the left side in FIG. 1) of the suction fan unit 50 with respect to the conveying direction. The retracting path 71 retracts and stocks the paper P (waste paper) that has become unnecessary due to printing defects or the like in the image forming apparatus 100.

[0025] [2. Configuration of Sheet Drying Device] FIG. 3 is an enlarged view of the drying section 40 in FIG. 2. The drying section 40 includes a heating unit 41 and a warm air fan 42 (see FIG. 2). Two sets of heating units 41 are arranged along the conveying direction (arrow X direction). The heating unit 41 includes a heater 43 and a reflector 44. The heating unit 41 is movable between a heating position (the position in FIG. 3) facing the conveyor belt 22 and a separated position (see FIG. 10) separated from the conveyor belt 22.

[0026] The heater 43 is rod-shaped and extends in the sheet width direction (the direction perpendicular to the paper surface in FIG. 3, hereinafter simply referred to as the width direction) that is horizontally orthogonal to the conveying direction. A plurality (12 in this embodiment) of heaters 43 are arranged in parallel along the conveying direction in the heating unit 41. In this embodiment, an infrared heater is used as the heater 43.

[0027] The reflector 44 is a U-shaped reflector in a side view that is arranged to surround each heater 43 from above. The infrared rays emitted from the heater 43 are reflected downward by the inner surface of the reflector 44 and irradiated onto the paper P carried and conveyed by the conveyor belt 22. As a result, the moisture in the ink on the paper P evaporates and dries, and the ink is fixed on the paper P.

[0028] The hot air fan 42 is arranged above the heating unit 41. More specifically, the hot air fan 42 is arranged to blow air upward toward the reflector 44. The air blown onto the reflector 44 by the hot air fan 42 is heated when passing through the gap of each reflector 44 to become hot air and flows into the gap (drying space) between the heating unit 41 and the conveyor belt 22.

[0029] If there is steam or water vapor in the gap between the heating unit 41 and the conveyor belt 22, the infrared rays emitted from the heater 43 and reflected by the reflector 44 will be absorbed by the steam or water vapor, and the drying ability of the ink on the paper P will be inhibited. Therefore, by blowing hot air into the gap between the heating unit 41 and the conveyor belt 22 by the hot air fan 42 to disperse and remove the steam or water vapor generated from the paper P, the drying property of the ink by the infrared rays can be maintained.

[0030] A first duct 53 for sucking the steam or water vapor generated from the paper P together with air is provided between the drying unit 40 and the suction fan unit 50. The first duct 53 extends from the gap between the heating unit 41 and the conveyor belt 22 to the suction fan 51 in the suction fan unit 50.

[0031] [3. Configuration of the Inner Cover and Lock Mechanism of the Sheet Drying Device] FIG. 4 is an external perspective view of the sheet drying device 10 of the present embodiment. FIG. 5 is an external perspective view of the sheet drying device 10 with the exterior cover removed from the state of FIG. 4.

[0032] As shown in Fig. 4, exterior covers 11a and 11b are provided on the front side of the sheet drying device 10. The exterior covers 11a and 11b are each pivotally supported at one end edge in the left - right direction on the main body frame 10a (see Fig. 5). More specifically, the exterior cover 11a is opened to the right with the right - hand edge as the pivot axis. The exterior cover 11b is opened to the left with the left - hand edge as the pivot axis.

[0033] As shown in Fig. 5, an inner cover 12 is provided inside the exterior covers 11a and 11b. The inner cover 12 is opened and closed in the vertical direction with the lower edge as the pivot axis. By closing the inner cover 12 as shown in Fig. 4, access to the pre - drying section 30 and the drying section 40 (see Fig. 2) is restricted. Inside the inner cover 12, a drying section temperature sensor 83 and a locking mechanism 75 are arranged.

[0034] The drying section temperature sensor 83 detects the temperature inside the drying section 40. The detection result is transmitted to the control unit 90 (see Fig. 7). The drying section temperature sensors 83 are provided at two locations facing the two heating units 41 (see Fig. 3) near the lower end of the inner cover 12.

[0035] Fig. 6 is a perspective view of the locking mechanism 75 of the inner cover 12. The locking mechanism 75 is provided at two locations on the left and right sides of the pivoting end side (upper end side) of the inner cover 12. The locking mechanism 75 has a locking arm 76, a solenoid 77, and a compression spring 78.

[0036] The locking arm 76 is pivotally supported with a swing axis 76a as the fulcrum. An engaging protrusion 76b is formed at the swinging end (left end in Fig. 6) of the locking arm 76. The solenoid 77 has a plunger 77a that can reciprocate in the vertical direction. The plunger 77a is connected to the end of the locking arm 76 on the side opposite to the engaging protrusion 76b with the swing axis 76a in between. The compression spring 78 is arranged between the locking arm 76 and the solenoid 77 with the plunger 77a inserted therein.

[0037] Figure 6 shows the locked state of the inner cover 12. The solenoid 77 is in a non-energized state and the plunger 77a protrudes from the solenoid 77. In this state, the lock arm 76 is biased in the counterclockwise direction by the biasing force of the compression spring 78, and the engagement protrusion 76b engages with the engagement hole 12a formed on the back side of the inner cover 12. Thereby, the opening of the inner cover 12 is restricted.

[0038] When the solenoid 77 is energized, the plunger 77a is drawn into the solenoid 77. As a result, the lock arm 76 swings in the clockwise direction against the biasing force of the compression spring 78, and the engagement between the engagement protrusion 76b and the engagement hole 12a is released. Thereby, the inner cover 12 can be opened.

[0039] A lock detection sensor 79 is disposed near the swing end of the lock arm 76. The lock detection sensor 79 is an optical (photointerrupter) sensor provided with a detection unit having a light emitting unit and a light receiving unit. In the state of Figure 6, the lock arm 76 does not block the detection unit of the lock detection sensor 79, and it is detected that the inner cover 12 is locked by the lock mechanism 75. When the lock arm 76 swings in the clockwise direction from the state of Figure 6 and blocks the detection unit of the lock detection sensor 79, it is detected that the locked state of the inner cover 12 has been released.

[0040] Figure 7 is a block diagram showing an example of the control path of the sheet drying device 10 of the present embodiment. Here, among the control paths of the sheet drying device 10, the parts necessary for the implementation of the present invention will be mainly described.

[0041] The control unit 90 includes at least a CPU (Central Processing Unit) 91 as a central processing unit, a ROM (Read Only Memory) 92 which is a read-only storage unit, a RAM (Random Access Memory) 93 which is a rewritable storage unit, a temporary storage unit 94 that temporarily stores data necessary for controlling each part of the sheet drying device 10, and a plurality (here, two) of I / F (interface) 96 that transmit control signals to each device within the sheet drying device 10 and receive input signals from the operation unit 80.

[0042] The ROM 92 stores data such as a control program for the sheet drying device 10 and numerical values necessary for control, which are not to be changed during the use of the sheet drying device 10. The RAM 93 stores necessary data generated during the control of the sheet drying device 10 and data temporarily required for the control of the sheet drying device 10. Further, in the RAM 93 (or ROM 92), the relationship between the printing rate of the image formed on the paper P and the arrangement of the reflector 44, which is used for the position control of the reflector 44, is also stored. The counter 95 accumulates and counts the number of sheets P carried in.

[0043] Also, the control unit 90 transmits a control signal from the CPU 91 to each part and device in the sheet drying device 10 through the I / F 96. Further, signals indicating the state and input signals from each part and device are transmitted to the CPU 91 through the I / F 96. Examples of the parts and devices controlled by the control unit 90 include the first conveyance unit 20, the preliminary drying unit 30, the drying unit 40, the suction fan unit 50, the second conveyance unit 70, the operation unit 80, the unit elevating mechanism 87, and the like.

[0044] The voltage control circuit 84 is connected to the fan drive voltage power supply 85 and the heater voltage power supply 86, and operates these power supplies according to an output signal from the control unit 90. These power supplies apply a predetermined voltage to the warm air fan 42 in the heating unit 41 by the control signal from the voltage control circuit 84, and to the heater 43 in the heating unit 41 by the heater voltage power supply 86, respectively.

[0045] The operation unit 80 is provided with a liquid crystal display unit 81 and LEDs 82 indicating various states. The user operates the stop / clear button of the operation unit 80 to stop the drying of the paper P, and operates the reset button to set various settings of the sheet drying device 10 to the default state. The liquid crystal display unit 81 is adapted to indicate the state of the sheet drying device 10, display the drying status of the paper P, and the number of sheets of the paper P carried in. Various settings of the sheet drying device 10 may be made from the input unit 101 of the image forming apparatus 100.

[0046] The unit elevating mechanism 87 moves the heating unit 41 in the drying unit 40 between a heating position (see FIG. 3) and a separated position (see FIG. 10). The unit elevating mechanism 87 is composed of a conventionally known driving mechanism such as a rack & pinion mechanism or a winding pulley and a wire.

[0047] In the present embodiment, based on the detection result of the drying unit temperature sensor 83, the lock mechanism 75 controls the inner cover 12 to be in a locked state and an unlocked state. More specifically, when the temperature of the drying unit 40 is equal to or higher than a predetermined temperature, the lock mechanism 75 locks the inner cover 12.

[0048] FIG. 8 is a flowchart showing an example of the lock and unlock control of the inner cover 12. With reference to FIGS. 1 to 7 as necessary, and FIGS. 9 and 10 described later, the lock and unlock operations of the inner cover 12 will be described along the steps of FIG. 8.

[0049] Before starting a printing job by the image forming apparatus 100, the control unit 90 turns on the power supply to the heater 43 of the drying unit 40 (step S1). Also, the drying unit temperature sensor 83 detects the temperature of the drying unit 40 (step S2). The detection result is transmitted to the control unit 90.

[0050] The control unit 90 determines whether or not the drying unit 40 has reached a predetermined temperature (for example, 42°C) or higher (step S3). If it has reached the predetermined temperature or higher (Yes in step S3), the inner cover 12 is locked by the locking mechanism 75 (step S4). Thereafter, a printing job by the image forming apparatus 100 is started, and the conveyance of the sheet P to the sheet drying apparatus 10 is started. Thereafter, the control unit 90 determines whether or not a jam (paper clogging) of the sheet P has occurred in the drying unit 40 (step S5).

[0051] FIG. 9 is a side cross-sectional view showing a state in which the sheet P is jammed in the drying unit 40 of the sheet drying apparatus 10. As shown in FIG. 9, when the sheet P jams between the heating unit 41 and the conveyance belt 22 of the drying unit 40, the sheet P does not reach the sheet detection sensor 65 (see FIG. 2). Therefore, if the sheet P is not detected by the sheet detection sensor 65 even after a predetermined time has elapsed after the sheet P has passed through the sheet detection sensor 64 (see FIG. 2), it is determined that a jam has occurred. If a jam of the sheet P has occurred (Yes in step S5), the control unit 90 turns off the power supply to the heater 43 (step S6).

[0052] Next, the control unit 90 determines whether or not the drying unit 40 has become lower than the predetermined temperature (for example, 42°C) (step S7). If it has become lower than the predetermined temperature (Yes in step S7), the locked state of the inner cover 12 by the locking mechanism 75 is released (step S8). At the same time, the heating unit 41 is raised to perform jam processing of the sheet P (step S9).

[0053] FIG. 10 is a view showing a state in which the heating unit 41 is raised from the state of FIG. 9 to a separated position. When the drying unit 40 becomes lower than the predetermined temperature, as shown in FIG. 9, the heating unit 41 is raised from the heating position to the separated position by the unit elevating mechanism 87. Thereby, the sheet P can be easily removed. When the jam processing of the sheet P is completed and the inner cover 12 is closed, the control unit 90 lowers the heating unit 41 again to the heating position by the unit elevating mechanism 87 (step S10).

[0054] Also, when there is no paper jam in the paper P at step S5 (No at step S5), the on state of the heater 43 is continued, and the printing job by the image forming apparatus 100 and the conveyance of the paper P to the sheet drying apparatus 10 are continued.

[0055] Thereafter, the control unit 90 determines whether the printing job has ended (step S11). When the printing job is continuing (No at step S11), it is determined whether the heater 43 is in the on state (step S12). When the heater 43 is in the off state at step S6 (No at step S11), the heater 43 is turned on again (step S13).

[0056] Then, it returns to step S2, and the following similar steps are repeated (steps S2 to S11). When the printing job has ended (Yes at step S11), the heater 43 is turned off and the process ends.

[0057] According to the configuration of the present embodiment, when the drying unit 40 is at a predetermined temperature or higher, the inner cover 42 is in a locked state, so it is possible to surely prevent a user from inserting a hand into the high-temperature drying unit 40 and getting burned when a jam occurs in the drying unit 40.

[0058] Also, when the drying unit 40 becomes lower than the predetermined temperature, by unlocking the inner cover 12 and simultaneously raising the heating unit 41 to the separated position, it becomes easy to remove the jammed paper P, and the jam processing time can be shortened.

[0059] Also, since the inner cover 12 restricts access to the drying unit 40 and the preliminary drying unit 30, access to locations other than the drying unit 40 and the preliminary drying unit 30 is possible even when the inner cover 12 is in the locked state. Therefore, when a paper jam occurs outside the drying unit 40 and the preliminary drying unit 30, the process can be performed immediately, and the jam processing time outside the drying unit 40 and the preliminary drying unit 30 can be shortened.

[0060] In the control example shown in FIG. 8, the heating unit 41 is raised (step S9) simultaneously with the unlocking of the inner cover 12 (step S8). However, the heating unit 41 may be raised before the unlocking of the inner cover 12. For example, the heating unit 41 may be raised to the separated position simultaneously with the detection of a jam in the sheet P. As a result, since the heating unit 41 has already been raised to the separated position at the time of unlocking the inner cover 12, the jam processing time can be shortened.

[0061] Further, in the control example shown in FIG. 8, when the temperature of the drying unit 40 becomes equal to or higher than a predetermined temperature (42°C), the inner cover 12 is locked, and when the temperature becomes lower than the predetermined temperature (42°C), the locked state is released. However, the threshold temperature (first temperature) for locking the inner cover 12 and the threshold temperature (second temperature) for releasing the locked state do not have to be the same.

[0062] For example, by setting the second temperature to a temperature lower than the first temperature (for example, 40°C), the safety during jam processing of the sheet P can be further enhanced. Also, by setting the second temperature to a temperature higher than the first temperature (for example, 45°C), the time until jam processing becomes possible can be shortened. Note that when the second temperature is set higher than the first temperature, it is necessary to set a temperature at which the user will not get burned.

[0063] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the occurrence of a jam is detected based on the detection timing of the sheet P by the sheet detection sensors 64 and 65, but a dedicated jam detection sensor may be arranged in the drying unit 40.

[0064] Further, in the above-described embodiment, as an example of the image forming system 200, a configuration in which the sheet drying device 10 is connected to the image forming apparatus 100, which is an inkjet printer, is shown. However, it goes without saying that the sheet drying device 10 can be used independently without being connected to the image forming apparatus 100.

Industrial Applicability

[0065] The present invention can be used in a sheet drying device for drying a sheet on which an image is printed by an inkjet recording device or the like. By using the present invention, it is possible to provide a sheet drying device and an image forming system including the same that can prevent a user from inserting a hand into a high-temperature drying unit and getting burned during jam processing or the like in the drying unit.

Explanation of Reference Numerals

[0066] 10 Sheet drying device 10a, 10b Exterior cover 12 Inner cover 20 First conveying unit (conveying unit) 22 Conveyor belt 30 Preliminary drying unit 40 Drying unit 41 Heating unit 42 Warm air fan 43 Heater 44 Reflector 50 Suction fan unit 61 Sheet inlet 62 Sheet outlet 64, 65 Sheet detection sensors 70 Second conveying unit 75 Lock mechanism 76 Lock arm 77 Solenoid 78 Compression spring 79 Lock detection sensor 83 Drying unit temperature sensor (temperature detection sensor) 86 Heater voltage power supply 87 Unit lifting mechanism 90 Control unit 100 Image forming device 200 Image forming system P Paper (sheet)

Claims

1. A conveying unit that conveys a sheet on which an image is formed with ink containing moisture; A drying unit that is disposed opposite to the conveying unit and heats and dries the sheet; A main body frame that houses the conveying unit and the drying unit; An openable and closable exterior cover attached to the main body frame; In a sheet drying device comprising: An inner cover that is disposed between the exterior cover and the drying unit so as to be openable and closable, restricts access to the drying unit in a closed state, and allows access to the drying unit in an open state; A locking mechanism that locks the inner cover in the closed state; A temperature detection sensor that detects the temperature of the drying unit; A control unit that controls the locking mechanism; Comprising: The control unit locks the inner cover in the closed state by the locking mechanism until the temperature of the drying unit detected by the temperature detection sensor becomes less than a first temperature. A sheet drying device characterized by this.

2. A heater disposed in the drying unit for heating the sheet; A heater voltage power source for energizing the heater. Comprising: The control unit: When power is supplied to the heater or when the temperature of the drying unit becomes equal to or higher than the first temperature, locks the inner cover in the closed state by the locking mechanism; When the temperature of the drying unit becomes a second temperature that is the same as or lower than the first temperature, releases the locked state of the inner cover by the locking mechanism. The sheet drying device according to Claim 1, characterized by this.

3. The drying unit: A heating unit that is disposed opposite to the conveying unit and is movable up and down between a heating position where the sheet is heated by the heater and a retracted position separated from the conveying unit; A unit lifting mechanism for lifting and lowering the heating unit; Comprising: When a jam of the sheet is detected between the conveying unit and the heating unit, the control unit, simultaneously with or until releasing the locked state of the inner cover, raises the heating unit from the heating position to the separated position by the unit lifting mechanism. The sheet drying device according to Claim 2, characterized by this.

4. An image forming device that forms an image using ink containing moisture on a sheet; The sheet drying device according to any one of Claims 1 to 3, connected to the downstream side of the image forming device in the conveying direction; An image forming system comprising:

Images