Drying apparatus, image forming apparatus

Abstract

To provide a drying apparatus and an image forming apparatus that can reliably protect users from dangers such as burns caused by heat when the inside of the apparatus is overheated by the heating section, thereby achieving a higher level of safety. [Solution] The recording device X1 includes a lock control unit 51 that controls the outer cover 27 to lock in the closed position based on a temperature abnormality signal from a temperature sensor 16, a lock control circuit 60 that outputs a drive signal to lock the outer cover 27 in the closed position when the temperature abnormality signal is input, a heater control unit 52 that controls the heater 12 to stop based on a cover open signal from a cover sensor 17 while the heater 12 is heating, and a heater control circuit 70 that outputs a stop signal to stop the heater 12 when the cover open signal is input.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a drying device for heating and drying a recording medium after image formation, and an image forming device including this drying device.

Background Art

[0002] Conventionally, an inkjet type image forming device including a sheet drying device that heats and dries a sheet after image formation with a heating unit such as a heater is known. The sheet drying device dries the ink on the sheet being conveyed by applying heat to the sheet being conveyed by, for example, a conveyance belt.

[0003] As this type of sheet drying device, when the temperature inside the housing exceeds a predetermined first temperature, an outer cover provided on the housing is locked and cannot be opened, and when a temperature below the first temperature is detected, the lock of the outer cover is released and it can be opened. A drying device configured as such has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the prior art, when the control unit that controls the locking of the outer cover becomes unstable in operation due to the influence of excessive heat from the heating unit, the outer cover may not be locked, exposing the user to danger.

[0006] An object of the present invention is to provide a drying device and an image forming device that can surely protect a user from dangers such as burns caused by heat and achieve higher safety when the inside of the device is excessively heated by a heating unit. [Means for solving the problem]

[0007] A drying apparatus according to one aspect of the present invention includes: a heating unit provided inside a housing for heating a recording medium after image formation; a temperature detection unit that outputs a temperature abnormality signal when the temperature inside the housing exceeds a predetermined set temperature; a cover member provided in the housing so as to be openable and closable; a locking mechanism having an actuator for locking the cover member in a closed position; a cover detection unit that detects the open state of the cover member and outputs a cover open signal indicating the open state; a lock control unit that drives the actuator based on the temperature abnormality signal from the temperature detection unit to lock the cover member in the closed position; a first protection circuit that outputs a drive signal to lock the cover member in the closed position when the temperature abnormality signal is input; a heating control unit that controls the heating unit to stop based on the cover open signal from the cover detection unit while the heating unit is heating; and a second protection circuit that outputs a stop signal to stop the heating unit when the cover open signal is input.

[0008] An image forming apparatus according to another aspect of the present invention comprises an image forming unit for forming an image on a recording medium, and a drying apparatus for drying the recording medium on which the image has been formed by the image forming unit. [Effects of the Invention]

[0009] According to the present invention, even if the inside of the device is excessively heated by the heating section, it is possible to reliably protect the user from dangers such as burns caused by heat, thereby achieving a higher level of safety. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram showing the configuration of the control unit of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 3]Figure 3 is a circuit diagram showing the configuration of a lock control circuit and a heater control circuit according to an embodiment of the present invention. [Figure 4] Figure 4 is a timing chart relating to the operation control of the cover lock when an abnormal temperature is detected during heating, according to an embodiment of the present invention. [Figure 5] Figure 5 is a timing chart relating to the operation control of the heater when the cover is opened during normal heating, according to an embodiment of the present invention. [Figure 6] Figure 6 is a timing chart relating to the operation control of the heater when an abnormal temperature is detected during heating, according to an embodiment of the present invention. [Figure 7] Figure 7 is a flowchart showing an example of a safety procedure performed by the control unit. [Figure 8] Figure 8 is a flowchart showing an example of a safety process performed by the control unit. [Modes for carrying out the invention]

[0011] 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.

[0012] First, with reference to Figure 1, an inkjet recording apparatus X1 (hereinafter abbreviated as "recording apparatus X1") according to an embodiment of the present invention will be described. Figure 1 is a diagram showing the configuration of the recording apparatus X1. Figure 1 shows the state in which the first transport unit 5 of the recording apparatus X1 is positioned at a recording position where printing by the recording unit 3 is possible. In addition, in Figure 1, the first transport unit 5 is shown by a dashed line when it is positioned at a retracted position at a predetermined distance below the recording position.

[0013] Recording device X1 is an example of an image recording device according to the present invention, and records an ink image on a sheet such as printing paper (an example of a recording medium according to the present invention) based on an inkjet recording method. As shown in Figure 1, recording device X1 includes a paper feed cassette 1, a paper feed unit 2, a recording unit 3 (an example of an image forming unit according to the present invention), a first transport unit 5, a lifting mechanism 6, a second transport unit 7, a heater 12 (an example of a heating unit according to the present invention), a maintenance unit 8, a temperature sensor 16 (an example of a temperature detection unit according to the present invention), a cover sensor 17 (an example of a cover detection unit according to the present invention), an outer cover 27 (an example of a cover member according to the present invention), a cover lock mechanism 40 (an example of a lock mechanism according to the present invention, see Figure 2), a control unit 50 (see Figure 2), a lock control circuit 60 (an example of a first protection circuit according to the present invention), a heater control circuit 70 (an example of a second protection circuit according to the present invention), and a housing 11 that houses or supports these.

[0014] The drying apparatus of the present invention is realized by the second transport unit 7, heater 12, control unit 50, lock control circuit 60, and heater control circuit 70.

[0015] Inside the housing 11, there are four transport paths 15 (15A, 15B, 15C, 15D). The first transport path 15A guides the sheet from the paper feed cassette 1 to the recording unit 3. The second transport path 15B guides the sheet from the second transport unit 7 to the output port 19. The third transport path 15C guides the sheet from the second transport unit 7 to the intermediate tray 13 for switchback, and is generally also called the switchback transport path. The fourth transport path 15D guides the sheet with recorded images from the intermediate tray 13 to the recording unit 3.

[0016] Furthermore, the transport path 15 is equipped with multiple sheet detection sensors 26 that detect the presence or absence of a sheet, the position of the sheet, and the leading or trailing end of the sheet.

[0017] The recording device X1 is a printer that executes printing processing based on input image data. Note that the image forming apparatus of the present invention is not limited to a printer that records an image on a sheet such as printing paper, and may be, for example, one that records an image on a flat surface such as an OHP sheet, cloth, or clothing.

[0018] The paper feeding unit 2 takes out sheets one by one from the paper feeding cassette 1 and feeds them to the first conveyance path 15A. The sheet fed to the first conveyance path 15A is conveyed to the registration roller pair 24 by the conveyance roller pair 23.

[0019] The registration roller pair 24 is provided in front of the recording unit 3. The registration roller pair 24 includes a driving roller and a driven roller that are pressed against each other, and conveys the sheet to the recording unit 3 at a predetermined conveyance timing (image writing timing).

[0020] On the downstream side of the registration roller pair 24 in the conveyance direction D1, the first conveyance unit 5 and the recording unit 3 are arranged.

[0021] The recording unit 3 has four line heads 31 (an example of a recording head) corresponding to each color of black, cyan, magenta, and yellow. Ink is supplied to the line head 31 through an ink tube from an ink tank (not shown). Note that the number of line heads 31 is not limited to the four described above, and it may have at least one. The line head 31 has a plurality of ink nozzles capable of discharging ink over 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.

[0022] The recording unit 3 forms an ink image on the sheet conveyed by the first conveyance unit 5. The recording unit 3 records an ink image on the sheet by discharging ink from the ink nozzles of each line head 31. As a method of discharging ink from the line head 31, for example, a piezo method of discharging ink using a piezo element or a thermal method of generating bubbles by heating to discharge ink is adopted.

[0023] The first transport unit 5 is located below the recording unit 3. The first transport unit 5 transports the sheet in the transport direction D1 while keeping the sheet facing 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 them. When the tension rollers 38 are driven to rotate, the paper transport belt 37 rotates, which enables the first transport unit 5 to transport the sheet in the transport direction D1.

[0024] The lifting mechanism 6 raises and lowers the first conveying unit 5 relative to the line head 31.

[0025] The maintenance unit 8 is positioned at a predetermined standby position (shown in Figure 1) downstream of the recording unit 3 in the transport direction D1 when not printing. 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 wipe unit 10, among others.

[0026] The second transport unit 7 is located downstream of the recording unit 3 in the transport direction D1. The second transport unit 7 transports the sheet on which the ink image has been recorded on its upper surface by the recording unit 3 in the transport direction D1. The second transport unit 7 includes a transport belt 7A 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 them. The sheet on which the ink image has been recorded on its upper surface by the recording unit 3 is transported in the transport direction D1 by the second transport unit 7 while being held on the upper surface of the transport belt 7A.

[0027] A drying heater 12 is provided above the second transport unit 7. The heater 12 heats the recording surface of the sheet after the ink image has been formed, drying the ink on the sheet. Specifically, the heater 12 is a heating device that supplies heat toward the image recording surface (upper surface) of the sheet on the transport belt 7A, heating the sheet and drying the ink image on the sheet. The heater 12 is, for example, an infrared heater or a halogen heater that emits infrared rays in response to power supply. The heating device used for the heater 12 is not limited.

[0028] When the sheet to be heated is transported onto the transport belt 7A of the second transport unit 7, the control unit 50 drives the heater 12 to start heating. Then, when the sheet is discharged from the transport belt 7A in the transport direction D1, the control unit 50 stops driving the heater 12.

[0029] A temperature sensor 16 is provided inside the housing 11 to detect the temperature inside the housing 11. The temperature sensor 16 is used to detect abnormal heating when the heater 12 is heating. In this embodiment, the temperature sensor 16 is located near the heater 12, and more specifically, it is positioned above the rear end of the conveying direction D1 of the conveying belt 7A.

[0030] The temperature sensor 16 outputs a temperature abnormality signal when the internal temperature of the housing 11 exceeds a predetermined set temperature. The set temperature is set to a temperature that can be judged as an abnormally heated state (abnormal temperature) by heating by the heater 12. As the temperature sensor 16, for example, a thermistor such as an NTC thermistor or CTR thermistor, which decreases in resistance when the set temperature is exceeded, can be used. Alternatively, as the temperature sensor 16, for example, a temperature sensor with a contact that turns off when the set temperature is exceeded may be used.

[0031] The sheet that has passed through the heater 12 is transported by the transport roller pair 25 to either the second transport path 15B or the third transport path 15C. For example, when the sheet is to be discharged from the discharge port 19, the sheet is transported to the second transport path 15B. On the other hand, when printing is to be done on the opposite side of the sheet, the sheet is transported to the third transport path 15C.

[0032] At the branching point between the second transport path 15B and the third transport path 15C, a flap (not shown) is provided to change the direction of sheet transport. This flap is displaced by the driving force of a solenoid or motor, thereby changing the direction of sheet transport.

[0033] An outer cover 27 is provided on one side of the housing 11 so as to be openable and closable. The outer cover 27 is a cover member for opening a vertically extending transport path, which is part of the third transport path 15C. The upper end of the outer cover 27 is rotatably supported by a support shaft 11A provided on the housing 11. The outer cover 27 is rotatable between a closed position that forms the vertical transport path and an open position that opens the vertical transport path. The closed position is the closed position shown by a solid line in Figure 1. The open position is the position when rotated from the closed position to the open position shown by a dotted line in Figure 1.

[0034] A cover sensor 17 is provided near the outer cover 27. The cover sensor 17 is a sensor for detecting the rotational state of the outer cover 27. The cover sensor 17 can be configured, for example, with a transmissive photointerrupter and a shielding portion provided on the outer cover 27. Alternatively, a reflective photointerrupter may be used as the cover sensor 17. When the outer cover 27 is in the closed position, the cover sensor 17 outputs a cover closed signal, which is a LOW level voltage signal indicating that the outer cover 27 is in a closed state. Furthermore, when the outer cover 27 is rotated outward from the closed position and opened, the cover sensor 17 outputs a cover open signal, which is a HIGH level voltage signal indicating that the outer cover 27 is in an open state.

[0035] In this embodiment, a configuration in which one outer cover 27 is provided on the housing 11 is illustrated, but the housing 11 may be provided with multiple covers. Furthermore, another inner cover may be provided inside the outer cover 27. In this case, a cover sensor for detecting the orientation of each cover is provided for each cover.

[0036] A cover lock mechanism 40 (see Figure 2) is provided in the housing 11. The cover lock mechanism 40 locks the outer cover 27 in the closed position. The cover lock mechanism 40 includes a lock hole provided in the outer cover 27, a lock member provided in the housing 11, and a solenoid 41 (an example of an actuator of the present invention) that operates the lock member. When the outer cover 27 is in the closed position, the lock member is inserted through the lock hole, thereby locking the outer cover 27 in the closed position and preventing it from rotating to the open position. The lock member is connected to a plunger of the solenoid 41, and the locking or unlocking of the outer cover 27 is controlled by the operation control 50 of the solenoid 41.

[0037] Next, referring to Figure 2, the configurations of the control unit 50, the lock control circuit 60, and the heater control circuit 70 of the recording device X1 will be described. Figure 9 is a block diagram showing the configuration of the control unit 50.

[0038] The control unit 50 comprehensively controls the recording device X1 and includes a CPU, ROM, and RAM. The control unit 50 is configured as a control board on which the CPU, ROM, RAM, etc., are mounted on a circuit 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 storage 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 comprehensively controls the recording device X1.

[0039] As shown in Figure 2, the control unit 50 includes various control processing units such as a lock control unit 51 and a heater control unit 52. Here, the lock control unit 51 is an example of a lock control unit of the present invention. The heater control unit 52 is an example of a heating control unit of the present invention.

[0040] The lock control unit 51 drives the solenoid 41 to control the locking of the outer cover 27. Specifically, the lock control unit 51 locks the outer cover 27 in the closed position when image forming processing is being performed in the recording device X1. Furthermore, when the image forming processing is completed, or when a paper jam occurs during the image forming processing, the lock control unit 51 releases the lock on the outer cover 27, allowing the outer cover 27 to rotate to the open position. Note that it is not always necessary to lock the outer cover 27 during the image forming processing.

[0041] Furthermore, the lock control unit 51 drives the solenoid 41 based on the abnormal temperature signal from the temperature sensor 16 to lock the outer cover 27 in the closed position. When the abnormal temperature signal is received while heating by the heater 12, the lock control unit 51 locks the outer cover 27 in the closed position for safety reasons to prevent it from being easily opened. Then, when the abnormal temperature signal is interrupted, the lock control unit 51 releases the lock on the outer cover 27.

[0042] The heater control unit 52 controls the heating of the heater 12. When a sheet to be heated is conveyed on the conveyor belt 7A, the heater control unit 52 drives the heater 12 to start heating. When the sheet is discharged from the conveyor belt 7A in the conveying direction D1, the heater control unit 52 stops driving the heater 12. If multiple sheets are conveyed continuously, the drying operation by heating the heater 12 continues until the last sheet is discharged. The conveying position of the sheet can be determined based on the detection signal from the sheet detection sensor 26 located in front of the conveyor belt 7A.

[0043] Furthermore, the heater control unit 52 controls the heating of the heater 12 to stop heating based on the cover open signal from the cover sensor 17 while the heater 12 is heating. Specifically, when the cover open signal is received while the heater 12 is heating, the heater control unit 52 stops heating the heater 12 for safety reasons, in order to protect the user from burns caused by heat.

[0044] The lock control circuit 60 is an electrical circuit composed of electronic components, as will be described later. The lock control circuit 60 can be composed of an integrated circuit such as an ASIC or LSI. When the temperature abnormality signal is input from the temperature sensor 16, the lock control circuit 60 outputs a voltage signal (drive signal) to lock the outer cover 27 into the closed position. Details of the lock control circuit 60 will be described later.

[0045] The heater control circuit 70 is an electrical circuit composed of electronic components, as will be described later. The heater control circuit 70 can be composed of an integrated circuit such as an ASIC or LSI. When the cover open signal is input, the heater control circuit 70 outputs a voltage signal (stop signal) to stop the heater 12. Details of the heater control circuit 70 will be described later.

[0046] Figure 3 is a circuit diagram showing the configuration of the lock control circuit 60 and the heater control circuit 70.

[0047] As shown in Figure 3, a P-channel type switching element Q11 (an example of the first switching unit of the present invention) is provided in the voltage supply line between the power supply Vo and the solenoid 41. The switching element Q11 is, for example, a P-channel type MOSFET. The switching element Q11 is mounted, for example, on the control board that constitutes the control unit 50. The source terminal of the switching element Q11 is connected to the power supply Vo, and the drain terminal of the switching element Q11 is connected to the input terminal of the solenoid 41.

[0048] The lock control circuit 60 includes an N-channel switching element Q12 (an example of the second switching section of the present invention) and a comparator U1 (an example of the first comparator of the present invention).

[0049] The switching element Q12 is, for example, an N-channel MOSFET. The drain terminal of the switching element Q12 is connected to the gate terminal of the switching element Q11, and the source terminal of the switching element Q12 is connected to ground potential.

[0050] Comparator U1 has an input terminal (non-inverting input terminal) V+, an input terminal (inverting input terminal) V-, a positive power supply terminal Vs+, a negative power supply terminal Vs-, and an output terminal Vout. Comparator U1 compares the voltages input to each input terminal, and if the input voltage of input terminal V- is smaller than the input voltage of input terminal V+ (reference voltage Vref), it outputs a predetermined first output voltage (HIGH level voltage) from output terminal Vout to the gate terminal of switching element Q12. This turns on switching element Q12, conduction occurs between the drain terminal and source terminal, and current flows from the drain terminal to the source terminal. On the other hand, if the input voltage of input terminal V- is larger than the input voltage of input terminal V+ (reference voltage Vref), it outputs a LOW level voltage from output terminal Vout to the gate terminal of switching element Q12. In this case, switching element Q12 remains in the off state.

[0051] In this embodiment, a predetermined reference voltage Vref is input to the input terminal V+ of the comparator U1.

[0052] When the temperature sensor 16 detects a temperature above the set temperature (abnormal temperature), the resistance value of the temperature sensor 16 decreases (see Figure 4(A)). In Figure 4, time T11 is the timing when the temperature sensor 16 detects an abnormal temperature above the set temperature. In this case, the input terminal V- of the comparator U1 receives a first input voltage, which is the power supply voltage Vo divided by the resistor R1. This first input voltage is smaller than the reference voltage Vref. In other words, when the temperature inside the housing 11 rises above the set temperature, the temperature sensor 16 inputs the first input voltage as the abnormal temperature signal to the input terminal V- of the comparator U1. As a result, the first output voltage at a predetermined voltage and a HIGH level is output from the output terminal Vout of the comparator U1 to the gate terminal of the switching element Q12 (see Figure 4(C)).

[0053] When the first output voltage is input to the gate terminal of switching element Q12, switching element Q12 turns ON (see Figure 4(D)). This causes conduction between the drain terminal and the source terminal, and current flows from the drain terminal to the source terminal. Also, as a result, the gate terminal of switching element Q11 becomes ground potential, so switching element Q11 turns ON (see Figure 4(E)), and conduction between the source terminal and the drain terminal of switching element Q11, and current flows from the source terminal to the drain terminal. As a result, the power supply voltage Vo is supplied to the solenoid 41, the solenoid 41 operates, and the outer cover 27 is locked in the closed position (Figure 4(F)). reference).

[0054] Furthermore, if the temperature sensor 16 detects a temperature below the set temperature, a voltage greater than the reference voltage Vref is input to the input terminal V- of the comparator U1. In this case, a LOW level voltage is output from the output terminal Vout of the comparator U1 to the gate terminal of the switching element Q12.

[0055] Furthermore, the first input voltage is also input to the lock control unit 51. In other words, when the temperature inside the housing 11 rises above the set temperature, the temperature sensor 16 inputs the first input voltage to the lock control unit 51 as a temperature abnormality signal. If the temperature sensor 16 detects a temperature below the set temperature, a voltage greater than the reference voltage Vref is input to the lock control unit 51 as a normal signal (non-abnormal signal).

[0056] When the first input voltage is received, the lock control unit 51 outputs a voltage signal approximately equal to the ground potential as a lock drive signal to the gate terminal of the switching element Q11 in order to operate the switching element Q11 (see Figure 4(B)). As a result, the switching element Q11 turns on (see Figure 4(E)), conduction occurs between the source terminal and the drain terminal of the switching element Q11, and current flows from the source terminal to the drain terminal. As a result, the power supply voltage Vo is supplied to the solenoid 41, the solenoid 41 operates, and the outer cover 27 is locked in the closed position.

[0057] As shown in Figure 3, a P-channel type switching element Q21 (an example of the third switching unit of the present invention) is provided in the voltage supply line between the power supply Vo and the heater 12. The switching element Q21 is, for example, a P-channel type MOSFET. The switching element Q21 is mounted, for example, on the control board that constitutes the control unit 50. The source terminal of the switching element Q21 is connected to the power supply Vo, and the drain terminal of the switching element Q21 is connected to the input terminal of the heater 12.

[0058] Furthermore, the control board is provided with a switching element Q22 (an example of the fourth switching section of the present invention). The switching element Q22 is an N-channel switching element, for example, an N-channel MOSFET. The drain terminal of the switching element Q22 is connected to the gate terminal of the switching element Q21, and the source terminal of the switching element Q22 is connected to ground potential.

[0059] The heater control circuit 70 includes at least an N-channel type switching element Q23 (an example of the fifth switching section of the present invention). The heater control circuit 70 further includes an N-channel type switching element Q24 (sixth switching section) and a comparator U2 (second comparator).

[0060] The switching elements Q23 and Q24 are, for example, N-channel type MOSFETs.

[0061] The drain terminal of switching element Q23 is connected to the gate terminal of switching element Q22, and the source terminal of switching element Q23 is connected to ground potential. In addition, the output signal of the cover sensor 17 (the cover open signal or the cover closed signal) is input to the gate terminal of switching element Q23. In other words, when the cover sensor 17 detects that the outer cover 27 is in the open position, it inputs the cover open signal at a HIGH level as the second input voltage to the gate terminal of switching element Q23 (see Figure 5(B)). In Figure 5, time T22 is the timing when it is detected that the outer cover 27 has been opened. As a result, switching element Q22 turns ON (see Figure 5(C)).

[0062] When switching element Q23 is turned ON, the gate terminal of switching element Q22 becomes ground potential, causing switching element Q22 to turn OFF (see Figure 5(D)). Also, the gate terminal of switching element Q21 becomes voltage higher than ground potential, causing switching element Q21 to turn OFF, and the source terminal and drain terminal no longer conduct (see Figure 5(E)). As a result, the power supply voltage Vo is no longer supplied to the heater 12, and the operation of the heater 12 stops (see Figure 5(F)).

[0063] When the cover sensor 17 detects that the outer cover 27 is in the closed position, a LOW level cover closed signal is input to the gate terminal of the switching element Q23 (see Figure 5(B)). In this case, the switching element Q23 remains in the off state (see Figure 5(C)). On the other hand, when the temperature sensor 16 detects a normal temperature, as will be described later, a LOW level voltage signal indicating the normal temperature is input from the output terminal Vout of the comparator U2 to the gate terminal of the switching element Q24 (see Figure 6(C)). In this case, the switching element Q24 remains in the off state (see Figure 6(D)). As a result, the switching element Q22 turns on (see Figure 6(E)) and the switching element Q21 turns on (see Figure 6(F)). This allows the power supply voltage Vo to the heater 12 to continue, and the heating control of the heater 12 continues (see Figure 6(G)).

[0064] Furthermore, the second input voltage is also input to the heater control unit 52. In other words, when the cover sensor 17 detects that the outer cover 27 is in the open position, it inputs the HIGH level cover open signal to the heater control unit 52 as the second input voltage. When the cover sensor 17 detects that the outer cover 27 is in the closed position, a LOW level cover closed signal is input to the heater control unit 52.

[0065] When the cover open signal is input, the heater control unit 52 outputs a voltage signal approximately equal to the ground potential as a heater stop signal to the gate terminal of the switching element Q22 in order to turn off the switching element Q22 (see Figure 5(A)). As a result, the gate terminal of the switching element Q22 becomes ground potential, so the switching element Q22 turns off (see Figure 5(D)), and furthermore, the switching element Q21 turns off (see Figure 5(E)), and the operation of the heater 12 stops (see Figure 5(F)).

[0066] When the heater control unit 52 drives the heater 12 to perform heating, it outputs a HIGH-level voltage signal as a heater drive signal to the gate terminal of the switching element Q22 in order to turn on the switching element Q22 (see Figure 5(A)). In Figure 5, time T21 is the timing when the heater drive signal is output. As a result, unless the switching elements Q23 and Q24 are turned on, the switching element Q22 is turned on (see Figure 5(D)), then the switching element Q21 is turned on (see Figure 5(E)), and the heater 12 operates and heating begins (see Figure 5(F)).

[0067] Comparator U2 has an input terminal (non-inverting input terminal) V+, an input terminal (inverting input terminal) V-, a positive power supply terminal Vs+, a negative power supply terminal Vs-, and an output terminal Vout. Comparator U2 compares the voltages input to each input terminal, and if the input voltage of input terminal V- is smaller than the input voltage of input terminal V+, it outputs a predetermined voltage output voltage from output terminal Vout to the gate terminal of switching element Q24. This turns on switching element Q24, conduction occurs between the drain terminal and source terminal, and current flows from the drain terminal to the source terminal. On the other hand, if input terminal V- is larger than input terminal V+, it outputs a LOW level voltage from output terminal Vout to the gate terminal of switching element Q24. In this case, switching element Q24 remains in the off state.

[0068] In this embodiment, a predetermined reference voltage Vref is input to the input terminal V+ of the comparator U2.

[0069] When the temperature sensor 16 detects a temperature above the set temperature (abnormal temperature), the input terminal V- of the comparator U2 receives the first input voltage, which is the voltage obtained by dividing the power supply voltage Vo by the resistor R1 and is smaller than the reference voltage Vref. In other words, when the temperature inside the housing 11 rises above the set temperature, the temperature sensor 16 inputs the first input voltage as the abnormal temperature signal to the input terminal V- of the comparator U2. As a result, the output voltage Vout of the comparator U2 outputs a HIGH level output voltage of a predetermined voltage to the gate terminal of the switching element Q24 (see Figure 6(C)).

[0070] When the output voltage is input to the gate terminal of switching element Q24, switching element Q24 turns ON (see Figure 6(D)), conduction occurs between the drain terminal and the source terminal, and current flows from the drain terminal to the source terminal. As a result, the gate terminal of switching element Q22 becomes ground potential (see Figure 6(E)), so switching element Q22 turns OFF, and furthermore, switching element Q21 also turns OFF (see Figure 6(F)). As a result, the operation of heater 12 stops (see Figure 6(F)).

[0071] [Safety procedures] The following describes an example of the safety processing procedure performed by the recording device X1, with reference to Figures 7 and 8. Note that the processing steps in the safety processing described below include those performed by the control unit 50 and those performed by the lock control circuit 60 or the heater control circuit 70. The safety processing shown in Figure 7 is initiated when the recording device X1 is waiting for a print instruction input (standby state).

[0072] As shown in Figure 7, in step S11, the control unit 50 determines whether the outer cover 27 is closed based on the output signal of the cover sensor 17.

[0073] If the outer cover 27 is closed, in the next step S12, the control unit 50 determines whether the inside of the housing 11 is at an abnormal temperature based on the output signal of the temperature sensor 16.

[0074] If an abnormal temperature is detected in step S12, the control unit 50 locks the outer cover 27 (S13), and then, after a predetermined time has elapsed, detects the temperature again based on the output signal of the temperature sensor 16 and determines whether the abnormal temperature has been resolved (S14). If the abnormal temperature has been resolved, the control unit 50 unlocks the outer cover 27 (S15) and performs the processing from step S12 onward.

[0075] Furthermore, if the temperature sensor 16 detects an abnormal temperature, regardless of the processing by the control unit 50, the first input voltage indicating the abnormal temperature is input to the lock control unit 51, and the lock control unit 51 locks the outer cover 27. Also, if the temperature sensor 16 detects a normal temperature, regardless of the processing by the control unit 50, a LOW-level voltage signal indicating the normal temperature is input to the lock control unit 51, and the lock control unit 51 unlocks the outer cover 27.

[0076] If the temperature is determined to be normal in step S12, in the next step S16, the control unit 50 determines whether a print command has been input. If a print command is input, in step S17, the control unit 50 drives the heater 12 in preparation for drying the ink image recorded on the sheet. Specifically, in order to drive the heater 12, the control unit 50 outputs a HIGH level voltage signal to the switching element Q22 as a heater drive signal. As a result, the switching element Q22 turns on (see Figure 5(D)), and then the switching element Q21 turns on (see Figure 5(E)), and the heater 12 starts operating and heating begins.

[0077] After the heater 12 has heated up, the control unit 50 determines in step S18 whether the inside of the housing 11 has reached an abnormal temperature. If it is determined that the inside of the housing 11 has reached an abnormal temperature, the control unit 50 locks the outer cover 27 (S20), stops the heater 12 from running (S21), and interrupts printing (S22). This completes the series of processes.

[0078] Furthermore, if the temperature sensor 16 detects an abnormal temperature, regardless of the processing by the control unit 50, the first input voltage indicating the abnormal temperature is input to the lock control unit 51, and the lock control unit 51 locks the outer cover 27. In addition, the first input voltage is input to the heater control circuit 70, and the heater control circuit 70 stops driving the heater 12.

[0079] On the other hand, if no abnormal temperature is detected in step S18, the processes from step S18 onward are repeated until printing is completed in the next step S19. When it is determined in step S19 that printing has been completed, the control unit 50 moves the process to the next step S23.

[0080] As shown in Figure 8, in the next step S23, the control unit 50, in the standby state after the completion of the printing process, again determines whether the inside of the housing 11 is at an abnormal temperature based on the output signal of the temperature sensor 16. If it is determined in step S23 that the temperature is abnormal, the control unit 50 locks the outer cover 27 (S24), and then, after a predetermined time has elapsed, it detects the temperature again based on the output signal of the temperature sensor 16 and determines whether the abnormal temperature has been resolved (S25). If the abnormal temperature has been resolved, the control unit 50 either repeatedly executes the processes from step S23 onward in the standby state of the recording device X1, or terminates the series of processes.

[0081] Furthermore, if an abnormal temperature is detected by the temperature sensor 16, the first input voltage indicating the abnormal temperature is input to the lock control unit 51, regardless of the processing performed by the control unit 50, and the lock control unit 51 locks the outer cover 27.

[0082] If the abnormal temperature is not resolved in step S25, the control unit 50 issues an error message indicating the temperature abnormality on the display unit of the recording device X1 (S226). After that, the series of processes ends.

[0083] As described above, in the recording device X1 of this embodiment, a lock control circuit 60 and a heater control circuit 70 configured as described above are provided, and a lock control unit 51 and a heater control unit 52 are provided in the control unit 50. Therefore, even if the inside of the housing 11 becomes excessively heated by the heater 12, the user can be reliably protected from dangers such as burns due to heat, thereby achieving a higher level of safety.

[0084] In other words, in the recording device X1 of this embodiment, when the temperature sensor 16 detects an abnormal temperature, the lock control unit 51 and the lock control circuit 60 lock the outer cover 27 for safety. Furthermore, even if the lock control unit 51 fails to output the lock drive signal due to a malfunction, the lock control circuit 60 will lock the outer cover 27. Also, even if the lock control circuit 60 malfunctions, the lock control circuit 60 will lock the outer cover 27.

[0085] Furthermore, if the cover sensor 17 detects that the outer cover 27 is open, the heater control unit 52 and the heater control circuit 70 will, for safety reasons, stop the heater 12. Also, even if the heater control unit 52 fails to output the heater stop signal due to a malfunction, the heater control circuit 70 will stop the heater 12. Also, even if the heater control circuit 70 malfunctions, the heater control unit 52 will stop the heater 12.

[0086] [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.

[0087] <Note 1> A heating unit is provided inside the housing to heat the recording medium after image formation, A temperature detection unit that outputs a temperature abnormality signal when the temperature inside the enclosure exceeds a predetermined set temperature, A cover member is provided on the housing so as to be openable and closable, A locking mechanism having an actuator for locking the cover member in the closed position, A cover detection unit detects the open state of the cover member and outputs a cover open signal indicating the open state, A lock control unit that controls the actuator to lock the cover member in the closed position based on the abnormal temperature signal from the temperature detection unit, A first protection circuit outputs a drive signal to lock the cover member in the closed position when the aforementioned temperature abnormality signal is input, A heating control unit that controls the stopping of the heating unit based on the cover open signal from the cover detection unit while heating is being performed by the heating unit, A drying apparatus comprising: a second protection circuit that outputs a stop signal to stop the heating unit when the cover open signal is input.

[0088] <Note 2> The system further comprises a P-channel type first switching unit, the source terminal of which is connected to the power supply and the drain terminal of which is connected to the voltage input terminal of the actuator, The first protection circuit is, The gate terminal of the first switching unit is connected to the drain terminal, and the source terminal is connected to the ground potential of the N-channel type second switching unit, It includes a first comparator that outputs a first output voltage of a predetermined voltage to the gate terminal of the second switching unit when a first input voltage equal to or greater than a reference voltage is input, When the temperature inside the housing exceeds the set temperature, the temperature detection unit inputs the first input voltage as a temperature abnormality signal to the input terminal of the first comparator and the lock control unit, respectively. The drying apparatus as described in Appendix 1, wherein the lock control unit outputs a drive signal to the gate terminal of the first switching unit to operate the first switching unit when the first input voltage is input.

[0089] <Note 3> A P-channel type third switching unit, in which the source terminal is connected to the power supply and the drain terminal is connected to the voltage input terminal of the heating unit, The system further comprises an N-channel type fourth switching unit, the gate terminal of the third switching unit being connected to a drain terminal and the source terminal being connected to ground potential, The 2nd protection circuit is, The fourth switching section has a drain terminal connected to its gate terminal and a fifth N-channel switching section whose source terminal is connected to ground potential. When the cover detection unit detects the open state of the cover member, it inputs a second input voltage of a predetermined voltage to the gate terminal of the fifth switching unit and the heating control unit, respectively, as the cover open signal. The drying apparatus according to Appendix 1 or 2, wherein the heating control unit outputs a drive signal to the gate terminal of the fourth switching unit to operate the fourth switching unit when the second input voltage is input.

[0090] <Note 4> An image forming unit that forms an image on a recording medium, An image forming apparatus comprising a drying device for drying the recording medium on which an image has been formed by the image forming unit, as specified in any of the appendices 1 to 3. [Explanation of Symbols]

[0091] X1: Inkjet recording device 1: Paper feed cassette 2:Paper feed section 3: Records Department 5: First transport unit 6: Lifting mechanism 7: Second transport unit 7A: Conveyor belt 11: Cabinet 11A: Support shaft 12: Heater 13: Intermediate tray 15: Conveyor path 15A: First transport path 15B: Second transport path 15C: Third transport route 15D: Fourth transport path 16: Temperature sensor 17: Cover Sensor 19: Outlet 23: Conveyor rollers 24: Resist Roller vs. 25: Conveyor rollers 26: Sheet detection sensor 27: Outer cover 31: Line Head 37: Paper transport belt 38: Tension Roller 40: Cover lock mechanism 41: Solenoid 50: Control Unit 51: Lock control unit 52: Heater control unit 60: Lock control circuit 70: Heater control circuit

Claims

1. A heating unit is provided inside the housing to heat the recording medium after image formation, A temperature detection unit that outputs a temperature abnormality signal when the temperature inside the enclosure exceeds a predetermined set temperature, A cover member is provided on the housing so as to be openable and closable, A locking mechanism having an actuator for locking the cover member in the closed position, A cover detection unit detects the open state of the cover member and outputs a cover open signal indicating the open state, A lock control unit that controls the actuator to lock the cover member in the closed position based on the abnormal temperature signal from the temperature detection unit, A first protection circuit that outputs a drive signal to lock the cover member in the closed position when the aforementioned temperature abnormality signal is input, A heating control unit that controls the stopping of the heating unit based on the cover open signal from the cover detection unit while heating is being performed by the heating unit, A drying apparatus comprising: a second protection circuit that outputs a stop signal to stop the heating unit when the cover open signal is input.

2. The system further comprises a P-channel type first switching unit, the source terminal of which is connected to the power supply and the drain terminal of which is connected to the voltage input terminal of the actuator, The first protection circuit is, The gate terminal of the first switching unit is connected to the drain terminal, and the source terminal is connected to the ground potential of the N-channel type second switching unit, It includes a first comparator that outputs a first output voltage of a predetermined voltage to the gate terminal of the second switching unit when a first input voltage equal to or greater than a reference voltage is input, When the temperature inside the housing exceeds the set temperature, the temperature detection unit inputs the first input voltage as a temperature abnormality signal to the input terminal of the first comparator and the lock control unit, respectively. The drying apparatus according to claim 1, wherein the lock control unit outputs a drive signal to the gate terminal of the first switching unit to operate the first switching unit when the first input voltage is input.

3. A P-channel type third switching unit, in which the source terminal is connected to the power supply and the drain terminal is connected to the voltage input terminal of the heating unit, The system further comprises an N-channel type fourth switching unit, the gate terminal of the third switching unit being connected to a drain terminal and the source terminal being connected to ground potential, The above 2 protection circuit is, The fourth switching section has a drain terminal connected to its gate terminal and a fifth N-channel type switching section whose source terminal is connected to ground potential. When the cover detection unit detects the open state of the cover member, it inputs a second input voltage of a predetermined voltage to the gate terminal of the fifth switching unit and the heating control unit, respectively, as the cover open signal. The drying apparatus according to claim 1 or 2, wherein the heating control unit outputs a drive signal to the gate terminal of the fourth switching unit to operate the fourth switching unit when the second input voltage is input.

4. An image forming unit that forms an image on a recording medium, An image forming apparatus comprising: a drying apparatus according to claim 1 for drying the recording medium on which an image has been formed by the image forming unit.

Images