Sheet drying system

Abstract

The present invention provides a sheet drying system that can reliably prevent or extinguish a fire even if the control unit that controls the heating unit becomes uncontrollable due to excessive heat generated inside the device by the heating unit. [Solution] The sheet drying system 100 includes a heating unit 24 provided inside the housing 21 and having a heater for heating the sheet, a drying control unit 30 that controls heating by the heating unit 24, a temperature sensor 31 that detects temperature abnormalities inside the housing 21, a fire extinguishing unit 28 that supplies fire extinguishing agent into the housing 21, and a main control unit 11 that controls the drying control unit 30. The main control unit 11 controls the fire extinguishing unit 28 to supply fire extinguishing agent when a temperature abnormality is detected during heating control by the drying control unit 30.

Description

Technical Field

[0001] The present invention relates to a sheet drying system for drying a sheet having an image formed on its surface.

Background Art

[0002] A sheet after image formation, on which an image is formed on the surface based on an inkjet method by an image forming apparatus, is dried by a sheet drying apparatus. The sheet drying apparatus dries the ink on the sheet being conveyed, for example, by supplying heat from a heating unit such as a heater to the sheet being conveyed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional sheet drying apparatus, when a control unit that controls the heating unit becomes unstable in operation due to the influence of excessive heat, the heating by the heating unit cannot be emergently stopped. In this case, the risk of ignition inside the sheet drying apparatus increases, and there is a risk of exposing the user to danger.

[0005] An object of the present invention is to provide a sheet drying system capable of surely preventing ignition or extinguishing a fire even when a control unit that controls a heating unit becomes uncontrollable due to heat when the inside of the apparatus is excessively heated by the heating unit.

Means for Solving the Problems

[0006] A sheet drying system according to one aspect of the present invention is a sheet drying system for drying a sheet on which an image has been formed on its surface. The sheet drying system is provided inside a housing and includes a heating unit for heating the sheet, a first control unit for controlling heating by at least the heating unit, an abnormality detection unit for detecting abnormalities inside the housing, a fire extinguishing agent supply unit for supplying a fire extinguishing agent into the housing, and a second control unit for controlling at least the first control unit. When an abnormality is detected by the abnormality detection unit, the second control unit controls the fire extinguishing agent supply unit to supply the fire extinguishing agent.

[0007] An image forming apparatus according to another aspect of the present invention comprises the sheet drying apparatus. [Effects of the Invention]

[0008] According to the present invention, even if the heating control unit becomes uncontrollable when the inside of the device is excessively heated by the heating unit, it is possible to reliably prevent or extinguish a fire. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a sheet drying system according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram showing the configuration of a sheet drying system according to an embodiment of the present invention. [Figure 3] Figure 3 is a flowchart showing an example of a drying process procedure performed by the control unit of the sheet drying apparatus in a sheet drying system according to an embodiment of the present invention. [Figure 4] Figure 4 is a flowchart showing an example of the procedure for abnormal shutdown processing performed by the control unit of the image forming apparatus of the sheet drying system according to an embodiment of the present invention. [Figure 5] Figure 5 is a flowchart showing an example of the procedure for abnormal shutdown processing performed by the control unit of the image forming apparatus of the sheet drying system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below with reference to the attached drawings. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the present invention.

[0011] First, the configuration of the sheet drying system 100 according to an embodiment of the present invention will be described.

[0012] The sheet drying system 100 is a system configured to dry a sheet on which an image has been formed on its surface, and as shown in Figure 1, it comprises an image forming apparatus 1 that forms and outputs an image on the surface of a sheet, and a sheet drying apparatus 2 that dries the sheet on which the image has been formed by the image forming apparatus 1.

[0013] Image forming apparatus 1 is an inkjet printer that forms images on a sheet using an inkjet method. Image forming apparatus 1 may also be a fax machine, copier, or multifunction device capable of forming images using an inkjet method.

[0014] As shown in Figure 2, the image forming apparatus 1 comprises a main control unit 11 (an example of a second control unit of the present invention), an operation display unit 12, a paper feeding unit 13, and an image forming unit 14 (an example of an image forming unit of the present invention).

[0015] The paper feeding unit 13 supplies sheets on which images are formed to the image forming unit 14. The paper feeding unit 13 comprises one or more paper feed cassettes and a paper feeding unit for accommodating sheets. The paper feeding unit 13 takes a sheet from a pre-designated paper feed cassette and feeds it to the image forming unit 14.

[0016] The image forming unit 14 uses an inkjet method to form an ink image on a sheet supplied by the paper feeding unit 13. The image forming unit 14 is equipped with four line heads that eject C (cyan), M (magenta), Y (yellow), and K (black) inks toward the sheet. Each line head is provided with a recording head having multiple nozzles for ejecting ink, and ink is ejected from each nozzle based on the image data. After the ink image is formed by the image forming unit 14, the sheet is transported to the sheet drying unit 2 by transport rollers or the like within the image forming apparatus 1.

[0017] The operation display unit 12 is the user interface of the image forming apparatus 1. The operation display unit 12 comprises a display unit and an operation unit. The display unit displays various information in response to control instructions from the main control unit 11. For example, the display unit is a liquid crystal display. The operation unit inputs various information to the main control unit 11 in response to user operations. For example, the operation unit is a touch panel.

[0018] The main control unit 11 comprehensively controls the image forming apparatus 1 and includes a CPU, ROM, and RAM. The main control unit 11 is configured, for example, as a control board on which the CPU, ROM, and RAM are mounted on a circuit board, or as a control unit having the control board. The CPU is a processor that performs various arithmetic operations. The ROM is a non-volatile memory device in which information such as control programs for causing the CPU to perform various operations is stored in advance. The RAM is a volatile or non-volatile memory device used as a temporary memory (work area) for the various operations performed by the CPU. The CPU executes the various control programs stored in advance in the ROM. This controls the image forming apparatus 1.

[0019] The main control unit 11 is a control unit positioned higher than the drying control unit 30 provided in the sheet drying device 2, and controls the drying control unit 30. In the present embodiment, an abnormal stop process (see FIGS. 4 and 5) described later is executed by the main control unit 11. Note that the abnormal stop process may not be executed by the main control unit 11, and may be executed by, for example, another control unit provided in the image forming apparatus 1.

[0020] As shown in FIG. 1, the sheet drying device 2 includes a housing 21, a sheet conveyance unit 22, a conveyance control unit 23, a heating unit 24 (an example of the heating unit of the present invention), a heating control unit 25, a first shutter unit 26 (an example of the opening / closing unit of the present invention), a second shutter unit 27 (an example of the opening / closing unit of the present invention), a fire extinguishing unit 28 (an example of the fire extinguishing agent supply unit of the present invention), a power supply unit 29, and a drying control unit 30 (an example of the first control unit of the present invention).

[0021] The housing 21 is the housing of the sheet drying device 2. Each of the above-described components constituting the sheet drying device 2 is mounted inside the housing 21.

[0022] The housing 21 has a receiving port 211 for receiving the image-formed sheet conveyed from the image forming apparatus 1, and a discharge port 212 for discharging the sheet dried by the sheet drying device 2 to the outside. The receiving port 211 is formed on the side surface 21A adjacent to the image forming apparatus 1, and the discharge port 212 is formed on the side surface 21B opposite to the side surface 21A.

[0023] The sheet conveyance unit 22 conveys the sheet after ink image formation conveyed from the image forming apparatus 1 along the conveyance path X1. The conveyance path X1 is a path along a horizontal plane and is a conveyance path from the receiving port 211 to the discharge port 212 of the housing 21. In the sheet drying device 2, the sheet is conveyed in a posture along the horizontal plane.

[0024] The sheet conveyance unit 22 includes a conveyance belt 221, a drive roller 222, a driven roller 223, an upstream first conveyance roller pair 35, and a downstream second conveyance roller pair 36 and second conveyance roller pair 36.

[0025] The conveyor belt 221 transports the ink-image-formed sheets, which have been transported from the image forming apparatus 1, to the downstream side of the transport path X1.

[0026] The conveyor belt 221 is an endless belt. The conveyor belt 221 conveys the sheet along the conveyor path X1 while holding the sheet after the ink image has been formed on its upper outer peripheral surface. The conveyor belt 221 is stretched by a drive roller 222 and a driven roller 223. The drive roller 222 and the driven roller 223 are spaced apart along the conveyor path X1. Both the drive roller 222 and the driven roller 223 are hollow rollers. The conveyor belt 221 is tensioned in the direction along the conveyor path X1 by being stretched by the drive roller 222 and the driven roller 223.

[0027] The conveyor belt 221 has a plurality of ventilation holes that penetrate in the thickness direction. Inside the conveyor belt 221, there is a sheet adsorption device (not shown) that adsorbs the sheet to be dried onto the upper outer peripheral surface of the conveyor belt 221. For example, the conveyor belt 221 has a belt body formed in a mesh shape from a metal such as stainless steel, and a coating layer formed on the outer peripheral surface of the belt body. The coating layer is formed from a heat-resistant material such as silicon, polyimide, and fluororesin.

[0028] The drive roller 222 rotates by receiving driving force supplied from the motor 23A located in the housing 21. The motor 23A is driven and controlled by the conveyance control unit 23. When the motor 23A is driven to rotate, the conveyor belt 221 stretched over the drive roller 222 travels in the direction D1 shown in Figure 1. As a result, the sheet held on the outer surface of the conveyor belt 221 is conveyed along the conveyance path X1 toward the discharge port 212.

[0029] The transport control unit 23 is a motor driver that controls the operation of the motor 23A by outputting rotation drive signals and stop signals to the motor 23A based on control signals from the drying control unit 30.

[0030] The heating unit 24 is installed above the upper belt portion of the conveyor belt 221, facing the upper surface of the upper belt portion. The heating unit 24 is a heating device that heats the sheets conveyed by the conveyor belt 221.

[0031] The heating unit 24 includes, for example, a heater 24A that emits infrared rays in response to power supply, and a reflector (not shown) located above the heater 24A that reflects the infrared rays emitted from the heater 24A downwards. The heating unit 24 heats and dries the sheets conveyed by the conveyor belt 221 by supplying heat to the sheets from above the conveyor belt 221. The heating unit 24 is not limited to the above configuration, and only needs to be capable of heating the sheets conveyed by the conveyor belt 221.

[0032] The heater 24A of the heating unit 24 is controlled by the heating control unit 25. When the heater 24A is driven, heat is supplied to the sheet on the conveyor belt 221.

[0033] The heating control unit 25 controls the heating of the heating unit 24 by the heater 24A. The heating control unit 25 is a heater driver that controls the operation of the heater 24A by outputting heating drive signals and heating stop signals to the heater 24A based on control signals from the drying control unit 30.

[0034] The fire extinguishing unit 28 is a device that supplies a fire extinguishing agent into the housing 21, and includes a storage section 281 for storing the fire extinguishing agent, a shutter member 283 for opening and closing an opening 281A formed at the bottom of the storage section 281, a drive unit 284 such as a motor or solenoid that applies driving force to the shutter member 283 to operate it, and an electric ball valve 285 for opening and closing an opening 281B formed at the top of the storage section 281.

[0035] The shutter member 283 opens and closes the opening 281A and is supported so as to be movable between a closed position that closes the opening 281A and an open position that opens the opening 281A. The shutter member 283 is normally positioned in the closed position that closes the opening 281A, and when a malfunction occurs in the sheet drying device 2, the drive unit 284 is driven to move it from the closed position to the open position.

[0036] Furthermore, the electric ball valve 285 is normally positioned in a closed position that closes the opening 281B, and is rotated from the closed position to an open position that opens the opening 281B if an abnormality occurs in the sheet drying device 2.

[0037] In this embodiment, the drive unit 284 and the electric ball valve 285 are driven and controlled by the main control unit 11 of the image forming apparatus 1.

[0038] The first shutter section 26 is an opening and closing device that opens and closes the receiving port 211 of the housing 21, and the second shutter section 27 is an opening and closing device that opens and closes the discharge port 212 of the housing 21.

[0039] The first shutter section 26 includes a shutter member 261 that opens and closes the receiving opening 211, and a drive unit 262 such as a motor or solenoid that applies driving force to the shutter member 261 to cause it to open and close.

[0040] The second shutter section 27 includes a shutter member 271 that opens and closes the discharge port 212, and a drive unit 272 such as a motor or solenoid that applies driving force to the shutter member 271 to cause it to open and close.

[0041] In this embodiment, the drive unit 262 and the drive unit 272 are driven and controlled by the main control unit 11 of the image forming apparatus 1.

[0042] The power supply unit 29 is equipped with an AC / DC converter, a DC / DC converter, etc., which rectifies the commercial voltage supplied from an external source (e.g., AC100V) to convert it to DC24V, and then further controls the switching to convert it to an appropriate DC voltage for each part, which is then supplied to the drying control unit 30, the transport control unit 23, the heating control unit 25, etc. The power supply unit 29 is also equipped with circuit breakers such as power relays installed on the power line.

[0043] In this embodiment, the circuit breaker of the power supply unit 29 is controlled by the main control unit 11 of the image forming apparatus 1.

[0044] As shown in Figure 2, the sheet drying apparatus 2 further includes a temperature sensor 31 (an example of an abnormality detection unit of the present invention), a rotation detection sensor 32, and a sheet detection sensor 33.

[0045] The temperature sensor 31 is a temperature detection unit that detects the temperature (internal temperature) inside the housing 21. The temperature sensor 31 is, for example, a contact type or a non-contact type sensor. The temperature sensor 31 can detect, for example, the temperature of the air inside the housing 21 or the surface temperature of the conveyor belt 221. The temperature sensor 31 outputs a detection signal indicating the detected temperature to the main control unit 11 of the image forming apparatus 1. Based on the detection signal, the main control unit 11 determines whether the inside of the housing 21 is in an abnormal state or a normal state.

[0046] In this embodiment, when heating control is being performed by the drying control unit 30, if the main control unit 11 detects an abnormality based on the detection signal from the temperature sensor 31, the main control unit 11 controls the fire extinguishing unit 28 to supply the fire extinguishing agent in the containment section 281 into the housing 21.

[0047] Specifically, based on the detection signal from the temperature sensor 31, the main control unit 11 determines that the temperature inside the housing 21 is a predetermined first abnormal temperature (first abnormality), and outputs a heating stop signal to the drying control unit 30 of the sheet drying device 2, causing the heating control unit 25 to stop heating the heater 24A. Furthermore, based on the detection signal from the temperature sensor 31, the main control unit 11 determines that the temperature inside the housing 21 is a second abnormal temperature (second abnormality), which is higher than the first abnormal temperature, and controls the fire extinguishing unit 28 to supply the fire extinguishing agent in the housing 281 into the housing 21. In detail, the main control unit 11 operates the drive unit 284 to move the shutter member 283 from the initial closed position to the open position. In addition, the main control unit 11 outputs a drive signal to the electric ball valve 285, causing the electric ball valve 285 to operate from the closed position to the open position.

[0048] In this embodiment, a configuration including a temperature sensor 31 is illustrated, but the present invention is not limited to this configuration. Any sensor that can detect abnormalities inside the housing 21 may be used. For example, instead of the temperature sensor 31, a sensor that detects the amount of carbon dioxide inside the housing 21 or a sensor that detects smoke may be used. In this case, the main control unit 11 may determine whether ignition (abnormality) has occurred inside the housing 21 based on the detection signal from the sensor.

[0049] The rotation detection sensor 32 is a rotation detection unit that detects the rotation speed of the motor 23A. The rotation detection sensor 32 is, for example, a rotary encoder. The rotation detection sensor 32 outputs a detection signal indicating the detected rotation speed to the main control unit 11 of the image forming apparatus 1. Based on the detection signal, the main control unit 11 determines whether or not the motor 23A is being driven.

[0050] The sheet detection sensor 33 is a sheet detection unit that detects sheets being transported on the conveyor belt 221. The sheet detection sensor 33 is located on the upstream side of the sheet transport direction on the conveyor belt 221. When the sheet detection sensor 33 detects a sheet, it outputs a detection signal to the drying control unit 30. The drying control unit 30 determines that a sheet jam (sheet blockage) has occurred on the conveyor belt 221 if sheets have been detected for a predetermined set time or longer.

[0051] The drying control unit 30 comprehensively controls the sheet drying apparatus 2 and includes a CPU, ROM, and RAM. The drying control unit 30 is configured, for example, as a control board on which the CPU, ROM, and RAM are mounted on a circuit board, or as a control unit having the control board. The CPU is a processor that performs various arithmetic operations. The ROM is a non-volatile memory device in which information such as control programs for causing the CPU to perform various operations is stored in advance. The RAM is a volatile or non-volatile memory device used as a temporary memory (work area) for the various operations performed by the CPU. The CPU executes the various control programs stored in advance in the ROM. This controls the sheet drying apparatus 2.

[0052] The drying control unit 30 performs the sheet drying process (see Figure 3), which will be described later. However, the sheet drying process does not necessarily have to be performed by the drying control unit 30; for example, it may be performed by another control unit provided in the sheet drying apparatus 2.

[0053] However, if the drying control unit 30, which controls the heating control unit 25, becomes unstable due to excessive heat caused by an abnormal temperature inside the housing 21, it cannot immediately stop heating by the heater 24A. In this case, the risk of the sheet drying device 2 catching fire increases, potentially endangering the user.

[0054] In contrast, in this embodiment, the drying control unit 30 executes the sheet drying device described later (see Figure 3), and the main control unit 11 executes the abnormal stop processing described later (see Figures 4 and 5). Therefore, even if the drying control unit 30 becomes uncontrollable due to excessive heating inside the housing 21 by the heater 24A, ignition inside the housing 21 can be reliably prevented, and even if ignition occurs, it can be reliably extinguished.

[0055] [Sheet drying process] The following describes an example of the procedure for the sheet drying process performed by the drying control unit 30 of the sheet drying apparatus 2, with reference to Figure 3. The present invention can also be considered as an invention of a sheet drying method that performs one or more steps included in the sheet drying process. Here, Figure 3 is a flowchart showing an example of the procedure for the sheet drying process.

[0056] The sheet drying process is carried out by the drying control unit 30 executing a control program stored in ROM or internal memory.

[0057] Furthermore, the execution order of each step included in the sheet drying process described below may differ to the extent that similar effects are produced. In addition, each step of the sheet drying process described below may be executed by a processor corresponding to the drying control unit 30, which is the processing execution unit, or each step may be distributed and executed by a processor corresponding to the drying control unit 30 and other processors that operate in cooperation with said processor.

[0058] In step S11, the drying control unit 30 determines whether or not it has received a drying execution instruction (drying execution signal) from the main control unit 11. The drying execution instruction includes a set number indicating the number of sheets to be dried. Upon receiving the drying execution instruction, the drying control unit 30 outputs a motor drive signal to the conveying control unit 23 in the next step S12 to run the conveying belt 221 in order to execute the drying process in the sheet drying apparatus 2. In the next step S13, the drying control unit 30 outputs a heater drive signal to the heating control unit 25 to start heating with the heater 24A.

[0059] Subsequently, in step S14, the drying control unit 30 determines whether or not it has received an abnormal operation signal from the main control unit 11 indicating abnormal operation. The abnormal operation signal is transmitted from the main control unit 11 to the drying control unit 30 when the main control unit 11 determines that the motor 23A is not operating, or when it determines that the temperature inside the housing 21 is not rising.

[0060] Upon receiving the abnormal operation signal, the drying control unit 30 outputs an abnormal stop signal to the transport control unit 23 and the heating control unit 25, stopping the transport control unit 23 and the heating control unit 25 and interrupting the drying operation (S15). Subsequently, the series of sheet drying processes ends without the drying process being completed.

[0061] If the abnormal operation signal is not received, the drying control unit 30 determines in the next step S16 whether or not a sheet jam has occurred on the conveyor belt 221. If it is determined that a sheet jam has occurred, in step S17 the drying control unit 30 sends error information to the main control unit 11, and then in step S15 the drying operation is interrupted, and the series of sheet drying processes ends without the drying process being completed. When the main control unit 11 receives the error information, it interrupts the image forming process by the image forming apparatus 1 and outputs error information indicating that a sheet jam has occurred to the operation display unit 12 of the image forming apparatus 1 and the information processing device that inputs the image forming instruction to the image forming apparatus 1, thereby informing the user of the situation.

[0062] If it is determined in step S16 that no sheet jam has occurred, the drying control unit 30 determines in the next step S18 whether the number of sheets that have been dried has reached the set number. If the number of sheets that have been dried has reached the set number, the drying control unit 30 outputs a stop signal to the transport control unit 23 and the heating control unit 25, stopping the transport control unit 23 and the heating control unit 25 and ending the drying operation (S19). After that, it sends a drying completion signal to the main control unit 11 indicating that the drying process is complete, ending the series of sheet drying processes.

[0063] On the other hand, if the number of sheets that have been dried has not reached the set number, in the next step S21, the drying control unit 30 determines whether or not it has received a heating interruption instruction (heating interruption signal) from the main control unit 11. Upon receiving the heating interruption instruction, the drying control unit 30 outputs a heater drive signal to the heating control unit 25 in the next step S22 to stop heating by the heater 24A in order to interrupt the heating process in the sheet drying apparatus 2.

[0064] Subsequently, in step S23, upon receiving a heating restart instruction (heating restart signal) transmitted from the main control unit 11, the drying control unit 30 restarts heating of the heater 24A (S24) and executes the processes from step S16 onward. On the other hand, if the heating restart instruction is not received and time runs out, the series of sheet drying processes ends without the drying process of all sheets being completed.

[0065] [Abnormal Shutdown Processing] Next, with reference to Figures 4 and 5, an example of the procedure for abnormal shutdown processing performed by the main control unit 11 of the image forming apparatus 1 will be described. It should be noted that the present invention can also be considered as an invention of an abnormal shutdown method that performs one or more steps included in the abnormal shutdown processing. Here, Figures 4 and 5 are flowcharts illustrating an example of the procedure for the abnormal shutdown processing.

[0066] The aforementioned abnormal termination process is performed by the main control unit 11 executing a control program stored in ROM or internal memory, etc., which is then used by the drying control unit 30.

[0067] Furthermore, the execution order of each step included in the abnormal termination process described below may differ to the extent that similar effects are produced. In addition, each step of the abnormal termination process described below may be executed by the processor corresponding to the main control unit 11, which is the processing execution entity, or each step may be distributed and executed by the processor corresponding to the main control unit 11 and other processors that operate in cooperation with that processor.

[0068] In step S31, the main control unit 11 determines whether an image forming instruction (image forming process execution signal) has been input based on an instruction signal input by a user using the image forming apparatus 1, or an instruction signal transmitted from another information processing device. When the image forming instruction is input, the main control unit 11 transmits the drying execution instruction (drying execution signal) including the set number to the drying control unit 30 of the sheet drying apparatus 2 (S32). The set number is the same number as the number of sheets to be printed included in the image forming instruction.

[0069] In the next step S33, the main control unit 11 determines whether the sheet drying device 2 has started drying normally after the drying execution instruction has been sent.

[0070] Specifically, the main control unit 11 determines whether the temperature inside the housing 21 has risen based on the detection signal from the temperature sensor 31. For example, the main control unit 11 determines whether the temperature inside the housing 21 has exceeded a predetermined set temperature within a predetermined set time elapsed since the drying execution instruction was transmitted. If the temperature inside the housing 21 exceeds the set temperature, the main control unit 11 determines that the heating operation by the heater 24A of the heating unit 24 has started normally in the sheet drying apparatus 2.

[0071] Furthermore, the main control unit 11 determines whether or not the motor 23A is rotating based on the detection signal from the rotation detection sensor 32. For example, the main control unit 11 detects the rotation speed of the motor 23A at a predetermined set time elapsed since the drying execution instruction was transmitted, and determines whether or not the rotation speed exceeds a predetermined set rotation speed. If the rotation speed of the motor 23A exceeds the set rotation speed, the main control unit 11 determines that the sheet transport operation by the sheet transport unit 22 has started normally in the sheet drying device 2.

[0072] When the main control unit 11 determines that the heating operation has started normally and that the sheet transport operation has started normally, it determines that the sheet drying operation has started normally.

[0073] If the sheet drying operation does not start normally in step S33, that is, if the temperature inside the housing 21 does not exceed the set temperature before the predetermined set time has elapsed, or if the rotational speed of the motor 23A at the time the predetermined set time has elapsed does not exceed the set rotational speed, the main control unit 11 proceeds to the next step S34.

[0074] In step S34, the main control unit 11 transmits an abnormal stop signal to the drying control unit 30 of the sheet drying apparatus 2 in order to urgently stop the drying operation in the sheet drying apparatus 2. The main control unit 11 then interrupts the image forming process by the image forming apparatus 1 and outputs error information to the operation display unit 12 of the image forming apparatus 1 and the information processing device that inputs the image forming instruction to the image forming apparatus 1, indicating that the operation of the sheet drying apparatus 2 has been urgently stopped due to a malfunction of the heating unit 24 or the sheet transport unit 22, and notifies the user of this (S35). Subsequently, the series of abnormal stop processes ends without the drying process in the sheet drying apparatus 2 being completed.

[0075] On the other hand, if the sheet drying operation starts normally in step S33, the main control unit 11 proceeds to the next step S36. In step S36, the main control unit 11 determines whether or not it has received the drying completion signal from the drying control unit 30 of the sheet drying device 2. If the drying completion signal is received in step S36, the main control unit 11 outputs information indicating that the sheet drying has been completed to the operation display unit 12 or the like (S37), and the series of abnormal stop processes ends.

[0076] If the drying completion signal is not received in step S36, the main control unit 11 determines in the next step S38 whether the internal temperature inside the housing 21 is the first abnormal temperature based on the detection signal from the temperature sensor 31. The main control unit 11 determines that the internal temperature is the first abnormal temperature if the internal temperature inside the housing 21 is within a temperature range, for example, from a predetermined first set temperature to a second set temperature. In other words, the first abnormal temperature is a temperature within the temperature range. The first abnormal temperature is a threshold temperature used to determine that the temperature is abnormal enough that it does not cause the sheet drying device 2 to catch fire, but causes discoloration of the sheet being dried or deterioration of other surrounding components due to heat.

[0077] If, in step S38, the internal temperature is not determined to be the first abnormal temperature, the main control unit 11 executes the processing from step S36 onward.

[0078] In step S38, if the internal temperature is determined to be the first abnormal temperature, the main control unit 11 sends a heating interruption instruction (heating interruption signal) to the drying control unit 30 of the sheet drying apparatus 2 in order to stop the heating operation in the sheet drying apparatus 2 (S39). The main control unit 11 then interrupts the image forming process by the image forming apparatus 1 and outputs error information to the operation display unit 12 of the image forming apparatus 1 and the information processing device that inputs the image forming instruction to the image forming apparatus 1, indicating that the heating operation by the heating unit 24 has been stopped because the inside of the sheet drying apparatus 2 is in an overheated state, and notifies the user of this (S40).

[0079] Subsequently, in the next step S41, the main control unit 11 determines, based on the detection signal from the temperature sensor 31, whether the internal temperature inside the housing 21 has fallen below the first abnormal temperature. In other words, the main control unit 11 determines whether the internal temperature inside the housing 21 has fallen below the first set temperature. If the internal temperature inside the housing 21 has fallen below the first abnormal temperature, the main control unit 11 determines that the internal temperature inside the housing 21 has returned to a normal temperature at which the sheet drying operation is possible, and outputs normal recovery information to the operation display unit 12 or the like (S42). As a result, the normal recovery information output in step S42 is displayed on the operation display unit 12 of the image forming apparatus 1.

[0080] When the user confirms the normal recovery information displayed on the operation display unit 12, the user checks for sheet jam or other possible causes of the temperature abnormality in the sheet drying device 2, and after confirming that there are no abnormal causes or that the abnormal causes have been resolved, the user inputs an execution command to restart drying through the operation display unit 12. In step S43, the main control unit 11 determines whether or not an execution command to restart drying has been input.

[0081] In step S43, if it is determined that the instruction to restart drying has been received, the main control unit 11 then resumes the interrupted image forming process. The main control unit 11 also sends the instruction to restart heating (heating restart signal) to the drying control unit 30 of the sheet drying apparatus 2 to restart heating of the heater 24A (S44). After that, the main control unit 11 executes the processes from step S36 onward.

[0082] On the other hand, if the time runs out in step S43 without inputting the instruction to restart drying, the main control unit 11 terminates the series of abnormal stop processes without restarting the drying process and the image forming process.

[0083] If, in step S41, the internal temperature inside the housing 21 does not drop below the first abnormal temperature, the main control unit 11 performs the processing from step S45 onwards in Figure 5.

[0084] As shown in Figure 5, in step S45, the main control unit 11 determines whether the internal temperature inside the housing 21 is the second abnormal temperature based on the detection signal from the temperature sensor 31. The main control unit 11 determines that the internal temperature is the second abnormal temperature if, for example, the internal temperature inside the housing 21 is above the predetermined second set temperature. The second abnormal temperature is a threshold temperature used to determine whether the sheet drying apparatus 2 is in an abnormal state with a high risk of ignition, or has already ignited.

[0085] If, within the predetermined time elapsed in step S46, it is not determined that the internal temperature is the second abnormal temperature (Yes in S46), the main control unit 11 terminates the series of abnormal shutdown processes.

[0086] If the main control unit 11 determines in step S45 that the internal temperature is the second abnormal temperature, there are two possible causes. The first cause is that an abnormality occurred in the communication line connecting the main control unit 11 and the drying control unit 30, and the heating interruption instruction transmitted in step S39 was not transmitted to the drying control unit 30. The first cause is that, for example, the internal temperature of the housing 21 rose to the second abnormal temperature and damaged the communication line, or the communication line was burned out due to ignition. The second cause is that the heating interruption instruction was transmitted to the drying control unit 30, but the drying control unit 30 overheated due to the abnormal temperature inside the housing 21 or ignition, resulting in unstable operation or malfunction. In either case, it is difficult for the drying control unit 30 to control the stopping of the heater 24A, and if left unattended, there is a risk that the inside of the sheet drying device 2 will ignite or that the fire will spread.

[0087] In this embodiment, if the internal temperature is determined to be the second abnormal temperature in step S45, the main control unit 11 cuts off the power supply from the power supply unit 29 in the next step S47. Specifically, it outputs a power cut-off signal to the circuit breaker of the power supply unit 29, turning off the contacts of the circuit breaker. As a result, power is no longer supplied to the heater 24A of the heating unit 24, and the heating of the heater 24A is forcibly stopped. As a result, ignition inside the sheet drying device 2 is prevented.

[0088] Furthermore, in the next step S48, the main control unit 11 controls the fire extinguishing unit 28 to release the fire extinguishing agent in the storage section 281 into the housing 21. Specifically, the main control unit 11 drives the electric ball valve 285 of the fire extinguishing unit 28 to move the electric ball valve 285 to the open position, opening the opening 281B. In addition, the main control unit 11 drives the drive unit 284 of the fire extinguishing unit 28 to move the shutter member 283 from the closed position to the open position, opening the opening 281A. This prevents ignition inside the sheet drying device 2 even in a state where there is a risk of ignition due to overheating. Also, if ignition has already occurred, the released fire extinguishing agent can quickly extinguish the fire, preventing it from spreading.

[0089] Furthermore, in the next step S49, the main control unit 11 closes the inlet 211 and outlet 212 of the housing 21. Specifically, the main control unit 11 drives the drive unit 262 of the first shutter unit 26 and the drive unit 272 of the second shutter unit 27 to move the shutter member 261 to the closed position and the shutter member 271 to the closed position. As a result, the inlet 211 and outlet 212 are closed. Consequently, high-temperature air inside the housing 21 is no longer released to the outside through the inlet 211 and outlet 212. Also, if there is a fire inside the housing 21, the flames will not be released to the outside through the inlet 211 and outlet 212. In addition, if a fire extinguishing agent is released, it will not leak out from the inlet 211 and outlet 212, so the area around the sheet drying device 2 will not be contaminated with the fire extinguishing agent. Furthermore, in order to reliably prevent the fire extinguishing agent from leaking to the outside, the process in step S49 may be performed before the process in step S48.

[0090] Subsequently, in the next step S50, the main control unit 11 outputs error information to the operation display unit 12 of the image forming apparatus 1 and the information processing device that inputs image forming instructions to the image forming apparatus 1, including that the sheet drying device 2 is in an abnormal state that poses a risk of ignition and that fire extinguishing agent has been released, and notifies the user of this fact.

[0091] Furthermore, in the next step S51, the main control unit 11 outputs a message prompting the replenishment of the fire extinguishing agent in the storage unit 281 to the operation display unit 12 of the image forming apparatus 1 and to the information processing device that has input an image forming instruction to the image forming apparatus 1, and terminates the series of abnormal shutdown processes.

[0092] As described above, in the embodiment of the present invention, the sheet drying device (see Figure 3) is operated by the drying control unit 30, and the abnormal stop processing (see Figures 4 and 5) is performed by the main control unit 11. Therefore, even if the drying control unit 30 becomes inoperable due to excessive heating inside the housing 21 by the heater 24A, excessive heat generation or ignition inside the housing 21 can be prevented, and even if ignition occurs, it can be reliably extinguished.

[0093] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0094] <Note 1> A sheet drying system for drying a sheet on which an image has been formed on its surface, A heating unit is provided inside the housing to heat the sheet, At least a first control unit that controls heating by the heating unit, An abnormality detection unit for detecting abnormalities within the housing, The aforementioned housing includes a fire extinguishing agent supply unit that supplies fire extinguishing agent, It comprises at least a second control unit that controls the first control unit, The second control unit is: A sheet drying system that controls the fire extinguishing agent supply unit to supply the fire extinguishing agent when an abnormality is detected by the abnormality detection unit.

[0095] <Note 2> The sheet drying system as described in Appendix 1, wherein the second control unit outputs a heating stop signal to the first control unit when a predetermined first abnormality is detected by the abnormality detection unit, thereby stopping heating by the heating unit, and after the output of the heating stop signal, the abnormality detection unit detects a second abnormality which is more severe than the first abnormality, thereby controlling the fire extinguishing agent supply unit to supply the fire extinguishing agent.

[0096] <Note 3> The housing has an inlet for receiving the sheet and an outlet for discharging the sheet. The system further includes an opening / closing mechanism for opening and closing both or either of the aforementioned receiving port and the aforementioned discharge port. The second control unit is: The sheet drying system according to Appendix 2, wherein, if the second abnormality is detected by the abnormality detection unit after the output of the heating stop signal, the fire extinguishing agent supply unit is controlled to supply the fire extinguishing agent, and the opening / closing unit is controlled to close both or either of the receiving port and the discharge port.

[0097] <Note 4> The abnormality detection unit is a temperature detection unit that detects the temperature inside the housing, The sheet drying system according to Appendix 2 or 3, wherein the first abnormality is a predetermined first abnormal temperature, and the second abnormality is a second abnormal temperature higher than the first abnormal temperature.

[0098] <Note 5> The aforementioned sheet drying system is The apparatus comprises an image forming unit that forms an image on the surface of the sheet, and a sheet drying apparatus that includes a heating unit and an abnormality detection unit. The sheet drying system according to any one of the appendices 1 to 4, wherein the first control unit is provided in the sheet drying apparatus and the second control unit is provided in the image forming apparatus. [Explanation of symbols]

[0099] 1: Image forming apparatus 2: Sheet drying device 11: Main Control Unit 12: Operation display section 13:Paper feed section 14: Image forming unit 21: Cabinet 22: Sheet transport section 23: Transport Control Unit 23A: Motor 24: Heating unit 24A: Heater 25: Heating control unit 26: First shutter section 27: Second shutter section 28: Firefighting Unit 29:Power supply section 30: Drying control unit 31: Temperature sensor 32: Rotation detection sensor 33: Seat detection sensor 100: Sheet drying system 211:Intake port 212: Outlet 221: Conveyor belt 261: Shutter component 262: Drive unit 271: Shutter component 272: Drive unit 281: Containment Unit 281A:Aperture 281B:Aperture 283: Shutter component 284: Drive unit 285: Electric ball valve

Claims

1. A sheet drying system for drying a sheet on which an image has been formed on its surface, A heating unit is provided inside the housing to heat the sheet, At least a first control unit that controls heating by the heating unit, An abnormality detection unit for detecting abnormalities within the housing, The aforementioned housing includes a fire extinguishing agent supply unit that supplies fire extinguishing agent, It comprises at least a second control unit that controls the first control unit, The second control unit is, A sheet drying system that controls the fire extinguishing agent supply unit to supply the fire extinguishing agent when an abnormality is detected by the abnormality detection unit.

2. The sheet drying system according to claim 1, wherein the second control unit outputs a heating stop signal to the first control unit when a predetermined first abnormality is detected by the abnormality detection unit, causing the heating unit to stop heating, and after the output of the heating stop signal, the abnormality detection unit detects a second abnormality which is more severe than the first abnormality, and controls the fire extinguishing agent supply unit to supply the fire extinguishing agent.

3. The housing has an inlet for receiving the sheet and an outlet for discharging the sheet. The system further includes an opening / closing mechanism for opening and closing both or either of the aforementioned receiving port and the aforementioned discharge port. The second control unit is, The sheet drying system according to claim 2, wherein if the second abnormality is detected by the abnormality detection unit after the output of the heating stop signal, the fire extinguishing agent supply unit is controlled to supply the fire extinguishing agent, and the opening / closing unit is controlled to close both or either of the receiving port and the discharge port.

4. The abnormality detection unit is a temperature detection unit that detects the temperature inside the housing, The sheet drying system according to claim 2 or 3, wherein the first abnormality is a predetermined first abnormal temperature, and the second abnormality is a second abnormal temperature higher than the first abnormal temperature.

5. The aforementioned sheet drying system is The apparatus comprises an image forming unit that forms an image on the surface of the sheet, and a sheet drying apparatus that includes a heating unit and an abnormality detection unit. The sheet drying system according to claim 1 or 2, wherein the first control unit is provided in the sheet drying apparatus, and the second control unit is provided in the image forming apparatus.

Images