Electronic apparatus

Abstract

To provide an electronic apparatus that can prevent lock of a cover part from being released when the temperature inside a housing is high.SOLUTION: An image forming apparatus comprises: a fixing device; a cover member that is provided so as to be able to open and close an opening of a housing that accommodates the fixing device; a plunger that is provided movable between a lock position where it locks the cover member in a closed state and a release position where it releases the lock of the cover member; a solenoid 32 that moves the plunger from the lock position to the release position when supplied with power; a CPU 21 that controls the presence or absence of the power supply to the solenoid 32; and a cut-off circuit 47 that is provided separate from the CPU 21, and restricts the power supply to the solenoid 32 when the temperature inside the housing exceeds a threshold.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to electronic devices. [Background technology]

[0002] There are known electronic devices such as printers that include a heating unit that heats a heating target such as a sheet after an image is formed on it. Also, there is known a related technique of electronic devices that can restrict user access to the inside of the device when the device is in a high temperature state (see Patent Document 1).

[0003] Specifically, the electronic device according to the related art includes a cover unit, a lock unit, a solenoid, and a processor. The cover unit is provided so as to be openable and closable relative to an opening of a housing that houses the heating unit. The lock unit is provided so as to be movable between a lock position that locks the cover unit in a closed state and an unlock position that unlocks the cover unit. The solenoid moves the lock unit from the lock position to the unlock position in response to power supply. The processor supplies power to the solenoid when the temperature inside the housing is equal to or lower than a predetermined threshold, and does not supply power to the solenoid when the temperature inside the housing exceeds the threshold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-272292 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the electronic devices related to the above-mentioned related technologies, due to a malfunction caused by the processor going out of control, etc., power may be supplied to the solenoid and the cover part may be unlocked even when the temperature inside the housing exceeds the threshold value.

[0006] An object of the present invention is to provide an electronic device that can prevent a cover part from being unlocked when the temperature inside the housing is high. [Means for solving the problem]

[0007] The electronic device according to the present invention comprises a heating unit, a cover unit, a lock unit, a drive source, a processor, and a power supply limiting unit. The heating unit heats a heating target. The cover unit is provided so as to be openable and closable relative to an opening of a housing that houses the heating unit. The lock unit is provided so as to be movable between a lock position that locks the cover unit in a closed state and an unlock position that unlocks the cover unit. The drive source moves the lock unit from the lock position to the unlock position in response to power supply. The processor controls whether or not power is supplied to the drive source. The power supply limiting unit is provided separately from the processor, and limits power supply to the drive source when the temperature inside the housing exceeds a predetermined threshold. Effect of the Invention

[0008] According to the present invention, it is possible to prevent the cover from being unlocked when the temperature inside the housing is high. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a system configuration of the image forming apparatus according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a side view showing the configuration of a cover member of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of a cover member and a solenoid of the image forming apparatus according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a circuit diagram showing the configuration of a drive unit of the image forming apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] [Configuration of image forming apparatus 100] First, a configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 4. In Figure 4, a plunger 32A disposed at the lock position P1 is indicated by a dashed line.

[0012] The image forming apparatus 100 is a multifunction machine having multiple functions such as a scanning function for reading an image of an original document, a printing function for forming an image based on image data on a sheet, a fax function, and a copy function. The image forming apparatus 100 is an example of an electronic device of the present invention. The electronic device of the present invention may be an image forming device such as a printer, a fax machine, or a copy machine. The electronic device of the present invention is not limited to an image forming device, and may be a washing machine, a cooking device, or the like.

[0013] As shown in FIGS. 1 and 2, an image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a sheet conveying unit 4, an operation display unit 5, a storage unit 6, and a control unit .

[0014] The ADF 1 transports documents to be read by the scanning function, and includes a document setting section, a plurality of transport rollers, a document holder, and a paper ejection section.

[0015] The image reading unit 2 realizes the scanning function. The image reading unit 2 includes a document table, a light source, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device).

[0016] 1, the image forming unit 3 includes a photoconductor drum 11, a charging roller 12, an optical scanning device 13, a developing device 14, a toner container 15, a transfer roller 16, a cleaning device 17, a fixing device 18, and a paper discharge tray 19.

[0017] Photoconductor drum 11 is provided so as to be rotatable in the direction of the arrow shown in Fig. 1. Charging roller 12 is provided in contact with the circumferential surface of photoconductor drum 11 and charges the circumferential surface of photoconductor drum 11. Optical scanning device 13 irradiates the circumferential surface of photoconductor drum 11 charged by charging roller 12 with light based on image data. An electrostatic latent image is formed on the circumferential surface of photoconductor drum 11 by optical scanning device 13.

[0018] The developing device 14 uses toner to develop the electrostatic latent image formed on the circumferential surface of the photoreceptor drum 11. A toner container 15 supplies toner to the developing device 14. A transfer roller 16 transfers the electrostatic latent image (toner image) developed by the developing device 14 onto a sheet transported by the sheet transport unit 4. A cleaning device 17 cleans the circumferential surface of the photoreceptor drum 11 after the toner image has been transferred by the transfer roller 16.

[0019] The fixing device 18 heats the sheet onto which the toner image has been transferred by the transfer roller 16, and fixes the toner image onto the sheet. For example, the fixing device 18 includes a fixing roller and a pressure roller. The fixing roller heats the sheet onto which the toner image has been transferred. The fixing roller is heated by a heater provided inside the fixing roller. The pressure roller is provided in contact with the fixing roller, and pressurizes the sheet passing through a nip portion formed between the fixing roller and the pressure roller. The fixing device 18 is an example of a heating section of the present invention. Also, the sheet on which an image is formed by the image forming section 3 is an example of a heating target of the present invention.

[0020] The sheet on which the toner image has been fixed by the fixing device 18 is discharged onto a paper discharge tray 19.

[0021] The sheet transport unit 4 transports a sheet on which an image is formed by the image forming unit 3. The sheet transport unit 4 includes a paper feed cassette, a pickup roller, a paper feed roller, and a plurality of transport rollers.

[0022] The operation display unit 5 is a user interface of the image forming apparatus 100. The operation display unit 5 includes a display unit and an operation unit. The display unit displays various information in response to control instructions from the control unit 7. For example, the display unit is a flat panel display such as a liquid crystal display. The operation unit inputs various information to the control unit 7 in response to user operations. For example, the operation unit includes hard keys and a touch panel.

[0023] The storage unit 6 is a non-volatile storage device. For example, the storage unit 6 is a non-volatile memory such as a flash memory. The storage unit 6 may be a solid state drive (SSD) or a hard disk drive (HDD).

[0024] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 2, the control unit 7 includes a CPU 21, a ROM 22, and a RAM 23. The CPU 21 is a processor that executes various arithmetic processing. The ROM 22 is a non-volatile storage device in which information such as a control program for causing the CPU 21 to execute various processing is stored in advance. The RAM 23 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for various processing executed by the CPU 21. The CPU 21 performs overall control of the image forming apparatus 100 by executing various control programs stored in advance in the ROM 22.

[0025] The image forming apparatus 100 includes a housing 100A (see FIG. 1) that houses an image forming unit 3 and a sheet transport unit 4. The housing 100A is formed in a substantially rectangular parallelepiped shape. The ADF 1 and the image reading unit 2 are provided on the upper side of the housing 100A. A rectangular opening 100B (see FIG. 3) is formed on the side (or rear) of the housing 100A.

[0026] The image forming apparatus 100 also includes a cover member 31 (see FIGS. 3 and 4), a solenoid 32 (see FIG. 4), and a drive unit 33 (see FIG. 5).

[0027] The cover member 31 is formed in a rectangular flat plate shape corresponding to the size of the opening 100B. The cover member 31 is provided so as to be openable and closable with respect to the opening 100B. Specifically, the cover member 31 is attached to the edge of the opening 100B via a pair of hinges 31A shown in FIG. 3. The cover member 31 is supported by the pair of hinges 31A so as to be swingable along a swing direction D1 shown in FIG. 4. Thereby, the cover member 31 changes state between a closed state in which the opening 100B is closed and an open state in which the opening 100B is opened. The cover member 31 is opened and closed during maintenance of the image forming apparatus 100 or when dealing with a paper jam that has occurred inside the housing 100A. The cover member 31 is an example of a cover portion of the present invention.

[0028] The cover member 31 extends from the pivot axis of the cover member 31 in a direction perpendicular to the pivot axis. As shown in Fig. 3 and Fig. 4, a grip portion 31B is formed at the tip of the cover member 31 in the extending direction from the pivot axis, which is gripped by the hand of the user of the image forming apparatus 100 when the cover member 31 is opened or closed. The grip portion 31B is formed on the surface (front surface) of the cover member 31 that faces the outside of the housing 100A when the cover member 31 is in the closed state.

[0029] As shown in Fig. 4, a claw portion 31C is provided at the tip end of the cover member 31 in the extension direction. The claw portion 31C is formed on a surface (rear surface) of the cover member 31 that faces the inside of the housing 100A when the cover member 31 is in the closed state. The claw portion 31C protrudes from the rear surface of the cover member 31 in a direction perpendicular to the rear surface, and is formed so that the protruding end is bent toward the extension direction. A recess is formed between the rear surface of the cover member 31 and the protruding end of the claw portion 31C into which the plunger 32A (see Fig. 4) of the solenoid 32 can be inserted.

[0030] The solenoid 32 is provided near the edge of the opening 100B on the inner surface of the housing 100A. The solenoid 32 includes a rod-shaped plunger 32A (see FIG. 4). The solenoid 32 can move the plunger 32A forward and backward along the direction in which the plunger 32A extends. The solenoid 32 is disposed at a position where the plunger 32A can be inserted into and removed from the recess in the cover member 31 in the closed state.

[0031] The plunger 32A is inserted into the recess, thereby restricting the cover member 31 from changing from the closed state to the open state. In other words, the cover member 31 is locked in the closed state. The plunger 32A is removed from the gap, thereby releasing the lock on the cover member 31. The position inside the recess is a lock position P1 (see FIG. 4) for locking the cover member 31 in the closed state. The position retreated from the lock position P1 along the advancement / retraction direction of the plunger 32A is a release position P2 (see FIG. 4) for releasing the lock on the cover member 31. The plunger 32A is provided to be movable between the lock position P1 and the release position P2. The plunger 32A is an example of a locking section of the present invention.

[0032] In response to the supply of power, the solenoid 32 moves the plunger 32A from a lock position P1 (see FIG. 4) to a release position P2 (see FIG. 4). The solenoid 32 is an example of a drive source of the present invention.

[0033] Specifically, the solenoid 32 is a self-holding solenoid incorporating a permanent magnet. The solenoid 32 moves the plunger 32A from either the lock position P1 or the release position P2 to the other in response to power supply. After power supply is stopped, the solenoid 32 holds the plunger 32A at the lock position P1 or the release position P2.

[0034] More specifically, the solenoid 32 includes a first terminal 32B (see FIG. 5), a power terminal 32C (see FIG. 5), and a second terminal 32D (see FIG. 5). When a current flows between the power terminal 32C and the first terminal 32B, the solenoid 32 moves the plunger 32A from the lock position P1 (see FIG. 4) to the release position P2 (see FIG. 4). When a current flows between the power terminal 32C and the second terminal 32D, the solenoid 32 moves the plunger 32A from the release position P2 to the lock position P1.

[0035] The solenoid 32 is not limited to a self-retaining solenoid. That is, the solenoid 32 may move the plunger 32A from the release position P2 to the lock position P1 in response to the power supply being stopped. The locking portion of the present invention is not limited to the plunger 32A, but may be a rod-shaped member that moves between the lock position P1 and the release position P2 in conjunction with the advancement and retreat of the plunger 32A. The driving source of the present invention is not limited to a solenoid, but may be a motor, etc.

[0036] The drive unit 33 drives the solenoid 32 .

[0037] [Configuration of drive unit 33] Next, the configuration of the drive unit 33 will be described with reference to Fig. 5. In Fig. 5, the first control signal S11 and the second control signal S12 output from the CPU 21 are indicated by dashed lines with arrows.

[0038] As shown in FIG. 5, the drive unit 33 includes a power supply 41, a first drive circuit 42, a second drive circuit 43, a temperature detection unit 44, a reference voltage generation unit 45, a comparator 46, and a cutoff circuit 47.

[0039] The power supply 41 outputs a DC voltage power to be supplied to the solenoid 32. The power supply 41 is electrically connected to the power supply terminal 32C of the solenoid 32 via a cutoff circuit 47.

[0040] The first drive circuit 42 can switch between conduction and interruption of a first current path that runs from the power source 41 through the power terminal 32C and the first terminal 32B of the solenoid 32 to ground. Specifically, the first drive circuit 42 includes a first switching element such as a transistor that is provided in a section of the first current path from the first terminal 32B to ground. The first switching element makes the first current path conductive while a first control signal S11 output from the CPU 21 is being input. Furthermore, the first switching element interrupts the first current path when the input of the first control signal S11 is stopped.

[0041] The second drive circuit 43 can switch between conduction and interruption of a second current path that runs from the power source 41 through the power terminal 32C and the second terminal 32D of the solenoid 32 to the ground. Specifically, the second drive circuit 43 includes a second switching element such as a transistor that is provided in a section of the second current path from the second terminal 32D to the ground. The second switching element conducts the second current path while a second control signal S12 output from the CPU 21 is being input. Moreover, the second switching element interrupts the second current path when the input of the second control signal S12 is stopped.

[0042] The temperature detection unit 44 detects the temperature inside the housing 100A. For example, the temperature detection unit 44 is a thermistor provided inside the housing 100A. The temperature detection unit 44 outputs an electrical signal having a voltage corresponding to the temperature inside the housing 100A. The electrical signal output from the temperature detection unit 44 is input to the CPU 21 and an inverting input terminal of a comparator 46.

[0043] When the cover member 31 is in the open state, the CPU 21 restricts the driving of the fixing device 18 (see FIG. 1). In other words, when the cover member 31 is in the open state, the image forming process using the image forming unit 3 including the fixing device 18 is not executed. The CPU 21 can determine whether the cover member 31 is in the open state by using an opening / closing sensor (not shown) that can detect the opening / closing state of the cover member 31.

[0044] Furthermore, when the fixing device 18 is driven, the CPU 21 locks the cover member 31 in the closed state. Specifically, the CPU 21 outputs the second control signal S12 to make the second current path conductive. This causes a current to flow between the power terminal 32C and the second terminal 32D, and the solenoid 32 moves the plunger 32A from the release position P2 to the lock position P1. That is, the cover member 31 is locked. This limits the user's access to the inside of the housing 100A, which becomes hot due to the drive of the fixing device 18. Furthermore, the CPU 21 stops outputting the second control signal S12 after the cover member 31 is locked.

[0045] Furthermore, when the driving of the fixing device 18 is finished and the temperature inside the housing 100A drops below a predetermined threshold, the CPU 21 unlocks the cover member 31. Specifically, the CPU 21 outputs a first control signal S11 to make the first current path conductive. This causes a current to flow between the power terminal 32C and the first terminal 32B, and the solenoid 32 moves the plunger 32A from the lock position P1 to the unlock position P2. That is, the cover member 31 is unlocked. Therefore, the restriction on access to the inside of the housing 100A is lifted. Furthermore, the CPU 21 stops outputting the first control signal S11 after the cover member 31 is unlocked.

[0046] The threshold value is set in consideration of the maximum temperature of the environment in which the image forming apparatus 100 is installed and the safety of a user who accesses the inside of the housing 100A. The CPU 21 can determine the temperature inside the housing 100A based on the electrical signal output from the temperature detection unit 44.

[0047] The CPU 21 controls whether or not power is supplied to the solenoid 32. The CPU 21 is an example of a processor of the present invention.

[0048] However, in conventional electronic devices, due to malfunction caused by runaway of the CPU 21 or noise, etc., the first electrical path may become conductive and the cover member 31 may be unlocked even if the temperature inside the housing 100A exceeds the threshold value.

[0049] In contrast, in the image forming apparatus 100 according to the embodiment of the present invention, as described below, it is possible to prevent the cover member 31 from being unlocked when the temperature inside the housing 100A is high.

[0050] The reference voltage generating unit 45 generates and outputs a reference voltage to be input to the non-inverting input terminal of the comparator 46 .

[0051] The comparator 46 outputs an electrical signal according to a comparison result between the voltage of the electrical signal output from the temperature detection unit 44 and the reference voltage output from the reference voltage generation unit 45. Specifically, when the voltage of the electrical signal output from the temperature detection unit 44 is lower than the reference voltage, the comparator 46 outputs a high-level electrical signal. On the other hand, when the voltage of the electrical signal output from the temperature detection unit 44 is higher than the reference voltage, the comparator 46 outputs a low-level electrical signal.

[0052] In image forming apparatus 100, the reference voltage is set so that when the temperature inside housing 100A is equal to or lower than the threshold, a high-level electrical signal is output from comparator 46, and when the temperature inside housing 100A exceeds the threshold, a low-level electrical signal is output from comparator 46. In other words, the reference voltage is set based on the voltage of the electrical signal output from temperature detection unit 44 when the temperature inside housing 100A is at the threshold.

[0053] The interrupting circuit 47 is provided in a common current path between the power source 41 and the power source terminal 32C of the solenoid 32. The common current path is a current path common to the first current path and the second current path. The interrupting circuit 47 can switch the common current path between conduction and interruption. Specifically, the interrupting circuit 47 includes a third switching element such as a transistor provided in the common current path. The third switching element makes the common current path conductive when the signal level of the electrical signal output from the comparator 46 is at a high level. Moreover, the third switching element interrupts the common current path when the signal level of the electronic signal output from the comparator 46 is at a low level.

[0054] That is, when the temperature inside the housing 100A exceeds the threshold value, the cutoff circuit 47 limits the power supply to the solenoid 32. The cutoff circuit 47 is an example of a power supply limiting unit of the present invention that is provided separately from the processor (CPU 21).

[0055] In this way, in the image forming apparatus 100, the cutoff circuit 47 provided separately from the CPU 21 limits the power supply to the solenoid 32 when the temperature inside the housing 100A exceeds the threshold. This prevents the cover member 31 from being unlocked even if the first control signal S11 is output due to a malfunction caused by runaway of the CPU 21, noise, or the like, even though the temperature inside the housing 100A exceeds the threshold. Therefore, it is possible to prevent the cover member 31 from being unlocked when the temperature inside the housing 100A is high.

[0056] The interrupter circuit 47 may be provided in a section of the first current path that is different from the common current path.

[0057] Furthermore, the blocking circuit 47 may be provided in the transmission path of the first control signal S11.

[0058] The present invention may also be applied to a drying device that heats and dries a sheet on which an ink image has been formed by an inkjet method. [Explanation of symbols]

[0059] 1 ADF 2 Image reading unit 3. Image forming section 4 Sheet transport section 5 Operation display section 6 Memory section 7 Control section 11 Photoconductor drum 12 Charging roller 13 Optical scanning device 14 Developing device 15 Toner Container 16 Transfer roller 17 Cleaning equipment 18 Fixing device 19 Output tray 21 CPU 31 Cover member 32 Solenoid 32A Plunger 33 Drive unit 41 Power supply 42 First drive circuit 43 Second drive circuit 44 Temperature detection section 45 Reference voltage generator 46 Comparator 47 Breaking Circuit 100 Image forming device 100A housing 100B opening

Claims

1. A heating unit that heats a heating target; A cover portion that is provided so as to be openable and closable relative to an opening of a housing that accommodates the heating portion; a locking portion that is movable between a locking position that locks the cover portion in a closed state and an unlocking position that unlocks the cover portion; a drive source that moves the lock portion from the lock position to the release position in response to power supply; A processor that controls whether or not power is supplied to the driving source; a power supply limiting unit that is provided separately from the processor and limits power supply to the drive source when a temperature inside the housing exceeds a predetermined threshold; An electronic device comprising:

2. The drive source is a solenoid that holds the lock portion at the release position after power supply is stopped.

2. The electronic device according to claim 1.

3. An image forming unit that forms an image on a sheet, the heating target is the sheet on which an image is formed by the image forming unit, 3. The electronic device according to claim 1 or 2.

Images