A safety control system and an image forming apparatus

Abstract

This utility model discloses a safety control system and an image forming apparatus. The system includes a safety interlock module, a control module, and a time-delay switch module. When the safety interlock module is triggered, it outputs a first electrical signal. The control module is connected to the safety interlock module and is used to connect to a relay and a thyristor respectively. The control module is also used to cut off the power supply to the thyristor after receiving the first electrical signal. The time-delay switch module is connected to both the safety interlock module and the control module. The time-delay switch module is used to cut off the power supply to the control module after a delay upon receiving the first electrical signal. After the power supply to the control module is cut off, the relay stops working. This utility model ensures that the relay is turned off only after the thyristor has actually turned off, thus helping to prevent arcing of the relay when the power is cut off.

Description

Technical Field

[0001] This utility model relates to the field of image forming technology, and in particular to a safety control system and an image forming apparatus. Background Technology

[0002] Generally, image forming devices such as printers or other household appliances have safety interlock devices (safety interlock devices are devices that can prevent the removal of a dangerous area before the danger is eliminated, or can automatically eliminate a dangerous state once touched). For example, the front cover of a printer. When the user opens the front cover, in order to prevent the user from touching the live parts inside the printer, the safety interlock device will be triggered the moment the front cover is opened. The safety interlock device controls the disconnection of the electrical parts that can be touched by the user when the front cover is opened, thereby cutting off the power supply to the printer, causing the printer to exit the working mode, and preventing electric shock or heating accidents.

[0003] Printer hardware circuits typically use thyristors and relays for power control. In actual use, due to the characteristics of the thyristor itself, when the printer is powered off, the thyristor remains energized until it crosses zero. At this time, the relay is energized and turned off, which can easily cause arcing and sparking, affecting the lifespan of the relay and posing a safety hazard. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a safety control system and image forming device that helps prevent relay arcing when the power is cut off in the event of a safety incident.

[0005] According to a first aspect of the present invention, a safety control system is provided, comprising:

[0006] A safety interlock module, which outputs a first electrical signal when triggered;

[0007] The control module is connected to the safety interlock module and is used to connect to the relay and the thyristor respectively. The control module is also used to cut off the power supply to the thyristor after receiving the first electrical signal.

[0008] A time-delay switch module is connected to the safety interlock module and the control module respectively. The time-delay switch module is used to cut off the power supply to the control module after a delay when the first electrical signal is received.

[0009] The relay stops working after the power supply to the control module is cut off.

[0010] The safety control system of this utility model outputs a first electrical signal to the control module and the delay switch module when the safety interlock module is triggered. The control module first cuts off the power supply to the thyristor, and the delay switch module cuts off the power supply to the control module after a delay, so that the relay stops working. This ensures that the relay is turned off only after the thyristor is actually turned off, thereby helping to prevent the relay from arcing when the power is cut off.

[0011] In some embodiments, the delay switch module includes:

[0012] A switching circuit, which is connected to the control module;

[0013] The delay circuit is connected to the safety interlock module and the switching circuit respectively. The delay circuit is used to cut off the power supply to the control module through the switching circuit after a delay when the first electrical signal is received.

[0014] In some embodiments, the delay switch module further includes:

[0015] A power control circuit is provided, which is connected to the switching circuit and the control module respectively. The power control circuit is used to control the input voltage input to the switching circuit.

[0016] In some implementations, the delay circuit is an RC delay circuit.

[0017] In some embodiments, the switching circuit includes at least one of a MOSFET or a transistor.

[0018] In some implementations, the input terminal of the switching circuit is used to receive the input voltage, the output terminal of the switching circuit is connected to the control module, and the control terminal of the switching circuit is connected to the delay circuit.

[0019] If the switching circuit is a MOSFET, the drain of the MOSFET serves as the input terminal of the switching circuit, the source of the MOSFET serves as the output terminal of the switching circuit, and the gate of the MOSFET serves as the control terminal of the switching circuit.

[0020] In some embodiments, the control module includes:

[0021] A thyristor control circuit is provided, which is connected to the safety interlock module and is also used to connect to the thyristor. The thyristor control circuit is further used to cut off the power supply to the thyristor after receiving the first electrical signal.

[0022] In some implementations, the thyristor control circuit is also connected to the delay switch module.

[0023] In some embodiments, the control module includes:

[0024] A relay control circuit is provided, which is connected to the time delay switch module and is also used to connect to the relay. The relay control circuit is further used to stop the operation of the relay after the time delay switch module cuts off the power supply to the control module.

[0025] According to a second aspect of the present invention, an image forming apparatus is provided, comprising the security control system described in any one of the first aspects.

[0026] Compared with the prior art, the safety control system and image forming apparatus of this utility model output a first electrical signal to the control module and the delay switch module when the safety interlock module is triggered. The control module first cuts off the power supply to the thyristor, and the delay switch module cuts off the power supply to the control module after a delay, so that the relay stops working. This ensures that the relay is turned off after the thyristor is actually turned off, thereby helping to prevent the relay from arcing when the power is cut off. Attached Figure Description

[0027] Figure 1 This is a circuit diagram of a safety control system according to one embodiment of the present invention;

[0028] Figure 2 This is a circuit diagram of a safety control system with a power control circuit according to one embodiment of the present invention.

[0029] Figure 3 This is a diagram showing the relationship between the turn-off time of the relay and the thyristor and the mains power in one embodiment of this utility model.

[0030] Reference numerals: 10 for fixing module, 20 for heating control module, 21 for relay, 22 for silicon controlled rectifier (SCR), 30 for various sensors, 40 for safety control system, 410 for safety interlock module, 420 for control module, 421 for relay control circuit, 422 for SCR control circuit, 4221 for SCR control unit, 430 for delay switch module, 432 for switch circuit, 431 for delay circuit, and 433 for power control circuit. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings.

[0032] This invention provides an image forming apparatus for performing image forming operations, such as scanning, generating, printing, receiving, and sending image data. Examples of the image forming apparatus include printers, copiers, fax machines with scanning capabilities, and multi-function peripherals (MFPs) that perform the above functions in a single device. Figure 1 As shown, the image forming apparatus includes a fixing module 10, a heating control module 20, various sensors 30, and a safety control system 40. The fixing module 10 includes a heating element (not shown), which can be a ceramic plate heater or a lamp heater, etc. During the fixing stage, the image forming apparatus controls the heating element in the fixing module 10 to heat and melt the toner on the paper, thereby completing the fixing work.

[0033] like Figure 1 As shown, the fixing module 10 is connected to the first voltage input terminal through the heating control module 20. The first voltage input terminal supplies power to the fixing module 10. The heating control module 20 is used to connect or disconnect the fixing module 10 from the first voltage input terminal to control the power supply to the fixing module 10. In this embodiment, the first voltage is AC mains power. The first voltage input terminal includes a live wire L and a neutral wire N. The heating control module 20 includes a relay 21 and a thyristor 22. The fixing module 10 is connected to the live wire L and the neutral wire N of the first voltage input terminal through the relay 21 and the thyristor 22, respectively. When the relay 21 and the thyristor 22 are both turned on, the first voltage input terminal supplies power to the fixing module 10, so that the heating element of the fixing module 10 is heated.

[0034] like Figure 1 As shown, relay 21 enters the on state when maintaining power supply, correspondingly connecting the fuser module 10 and the live wire L; relay 21 enters the off state when power supply is cut off, correspondingly disconnecting the fuser module 10 from the live wire L. Similarly, thyristor 22 enters the on state when maintaining power supply, correspondingly connecting the fuser module 10 to the neutral wire N; thyristor 22 enters the off state when power supply is cut off, correspondingly disconnecting the fuser module 10 from the neutral wire N. Figure 3 As shown, when the thyristor 22 enters the off state (i.e. Figure 3Due to the characteristics of the thyristor (P1), the thyristor 22 does not actually turn off immediately. Instead, it only turns off when the AC mains power transitions from the positive half-cycle to the negative half-cycle, or from the negative half-cycle to the positive half-cycle, or from the positive half-cycle to the negative half-cycle. This disconnects the fuser module 10 from the neutral line N. During normal operation of the image forming apparatus, the fuser module 10 needs to be heated. When a safety incident occurs in the image forming apparatus, for safety reasons, the first voltage supplied to the fuser module 10 needs to be cut off, i.e., the connection between the fuser module 10 and the first voltage input terminal needs to be disconnected. Specifically, this is achieved by disconnecting the thyristor 22 and the relay 21. When the operating power supplied to the thyristor 22 and the relay 21 is cut off, both the thyristor 22 and the relay 21 simultaneously enter the off state (i.e., Figure 3 In P1), due to the characteristics of the thyristor, thyristor 22 can only be truly turned off when the positive half-cycle transitions to the negative half-cycle (i.e., ...). Figure 3 At this time, relay 21 is turned off while energized (i.e., relay 21 is connected to the live wire L and the neutral wire N), which can easily lead to arcing. Therefore, it is necessary to control the actual turn-off time of relay 21 to be later than the turn-off time of thyristor 22.

[0035] like Figure 1 As shown, the safety control system 40 includes a safety interlock module 410, a control module 420, and a time delay switch module 430.

[0036] like Figure 1 As shown, when the safety interlock module 410 is triggered, it outputs a first electrical signal. Specifically, the safety interlock module 410 can be a switch. The first terminal of the safety interlock module 410 is connected to the VCC terminal through a first resistor R1, and the second terminal of the safety interlock module 410 is grounded. When the safety interlock module 410 is not triggered, it is in the on state, and the first terminal of the safety interlock module 410 is pulled low as the output terminal. When the safety interlock module 410 is triggered, it is in the off state, and the first terminal of the safety interlock module 410 is pulled high as the output terminal, and the first terminal of the safety interlock module 410 outputs a first electrical signal. When the safety interlock module 410 is triggered, it indicates that a safety event has occurred in the image forming apparatus. For example, when the user opens the front cover of the image forming apparatus, the safety interlock module 410 changes from the on state to the off state.

[0037] like Figure 1As shown, the control module 420 is connected to the safety interlock module 410 and is used to connect to the relay 21 and the thyristor 22 respectively. The control module 420 is also used to cut off the power supply to the thyristor 22 after receiving the first electrical signal. During normal operation of the fixing module 10 of the image forming apparatus, the safety interlock module 410 is usually not triggered. At this time, the control module 420 does not cut off the power supply to the relay 21 and the thyristor 22. The relay 21 and the thyristor 22 are in the conducting state, so that the fixing module 10 is normally connected to the first voltage input terminal, thereby supplying power to the fixing module 10 and causing the heating element of the fixing module 10 to be heated. Heat; after the safety interlock module 410 is triggered, the control module 420 receives the first electrical signal output by the safety interlock module 410 and cuts off the power supply to the thyristor 22, causing the thyristor 22 to stop working and reducing the occurrence of safety accidents; however, due to the characteristics of the thyristor itself, after the control module 420 cuts off the power supply to the thyristor 22, the thyristor 22 will not immediately cut off the power supply, but will only cut off the power supply when the positive half cycle turns into the negative half cycle. If the power supply to the thyristor 22 is not completely cut off, the relay 21 may be turned off, which may cause the relay 21 to arc and spark. Therefore, it is necessary to delay the turn-off time of the relay 21.

[0038] The off-time of the delayed relay 21 can be achieved by delaying the disconnection of power supplied to the relay 21. For example... Figure 1As shown, the time-delay switch module 430 is connected to the safety interlock module 410 and the control module 420 respectively. The time-delay switch module 430 is used to cut off the power supply to the control module 420 after a delay upon receiving the first electrical signal. After cutting off the power supply to the control module 420, the relay 21 stops working. The time-delay switch module 430 is also used to connect to each of the sensors 30 and the second voltage input terminal, inputting a second voltage through the second voltage input terminal to supply power to each of the sensors 30 and the control module 420. The time-delay switch module 430 is used to control the connection or disconnection of each of the sensors 30 and the control module 420 with the second voltage input, thereby controlling the power supply to each of the sensors 30 and the control module 420. When the safety interlock module 410 is not triggered, the time-delay switch module 430... The second voltage input supplies power to each sensor 30 and control module 420, enabling them to operate normally. When the safety interlock module 410 is triggered, the delay switch module 430 receives the first electrical signal output by the safety interlock module 410 and delays before cutting off the power supply to each sensor 30 and control module 420, causing them to stop working. After the control module 420 stops working, the relay 21 and thyristor 22 it controls also stop working. Therefore, the delay time of the delay switch module 430 is greater than the positive or negative half-cycle of the mains power, ensuring that the turn-off time of the relay 21 is later than the actual turn-off time of the thyristor 22. Specifically, as shown... Figure 3 As shown, at point P1, a safety event occurs in the image forming apparatus, triggering the safety interlock module 410. This causes the first electrical signal to be simultaneously transmitted to the control module 420 and the delay switch module 430. Upon receiving the first electrical signal, the control module 420 immediately stops the operation of the thyristor 22. The delay switch module delays the first electrical signal. The specific delay time can be the positive half-cycle of the mains power, the negative half-cycle, or other preset times (e.g., if the positive half-cycle of the mains power is 10ms, the delay time can be 10ms or other preset times greater than 10ms). Since the delay time ensures that the thyristor 22 reaches the zero-crossing point (i.e., point P2), the thyristor 22 can be completely turned off and thus de-energized. At this time, the delay switch module 430 cuts off the power supply to the control module 420, causing the relay 21 to stop working at this time (i.e., point P3). This reduces the likelihood of relay arcing when the image forming apparatus is powered off due to the characteristics of the thyristor, thus reducing relay lifespan and improving product safety.

[0039] like Figure 1As shown, the delay switch module 430 includes a delay circuit 431 and a switch circuit 432. The switch circuit 432 is connected to the control module 420 and is also used to connect to each of the sensors 30 and the second voltage input terminal. The delay circuit 431 is connected to the safety interlock module 410 and the switch circuit 432 respectively. When the first electrical signal is received, the delay circuit 431 is used to cut off the power supply to the control module 420 and each of the sensors 30 after a delay through the switch circuit 432. When the safety interlock module 410 is not triggered, the switch circuit 432 is turned on to supply the second voltage to each of the sensors. Sensor 30 and control module 420; when safety interlock module 410 is triggered, delay circuit 431 receives the first electrical signal output by safety interlock module 410, delays the first electrical signal and transmits it to switch circuit 432. Switch circuit 432 disconnects the second voltage input terminal from each sensor 30 and control module 420 after receiving the delayed first electrical signal, thereby cutting off the power supply to each sensor 30 and control module 420. Control module 420 stops working, causing relay 21 to also stop working. Relay 21 enters the off state, and fixing module 10 and live wire L are disconnected.

[0040] like Figure 1 As shown, the delay circuit 431 can be an RC delay circuit. The delay circuit 431 includes a first resistor R1 and a first capacitor C1. The connection terminal of the first resistor R1 and the first capacitor C1 is connected to the safety interlock module 410. The first electrical signal output from the first terminal of the safety interlock module 410 is delayed by the delay circuit composed of the first resistor R1 and the first capacitor C1. The delay time of the delay circuit 431 can be set by adjusting / changing the values ​​of the first resistor R1 and the first capacitor C1. That is, the delay time can be made to be the positive half-cycle period of the mains power, the negative half-cycle period of the mains power, or other preset time by adjusting / changing the values ​​of the first resistor R1 and the first capacitor C1 to a suitable value.

[0041] like Figure 1As shown, the input terminal of the switching circuit 432 is connected to the second voltage input terminal through the second resistor R2 to receive the input voltage. The output terminal of the switching circuit 432 is connected to the control module 420 and each sensor 30. The control terminal of the switching circuit 432 is connected to the delay circuit 431. The switching circuit 432 includes at least one of a MOSFET and a transistor. If the switching circuit 432 is a MOSFET Q1, the drain of the MOSFET Q1 serves as the input terminal of the switching circuit 432, and the source of the MOSFET Q1 serves as the output terminal of the switching circuit 432. The gate of MOSFET Q1 serves as the control terminal of the switching circuit 432. The gate of MOSFET Q1 is connected to the connection terminal of the first resistor R1 and the first capacitor C1 in the delay circuit 431. When the gate of MOSFET Q1 receives the first electrical signal after being delayed by the delay circuit 431, it enters the off state, thereby cutting off the power supply to each sensor 30 and the control module 420. Each sensor 30 stops detecting, and the control module 420 stops working, causing the relay 21 to also stop working. The relay 21 enters the off state, and the fixing module 10 and the fire wire L are disconnected.

[0042] like Figure 1 As shown, the control module 420 includes a relay control circuit 421 and a thyristor control circuit 422. The relay control circuit 421 is connected to the time delay switch module 430 and to the relay 21. The relay control circuit 421 is also used to stop the operation of the relay 21 after the time delay switch module 430 (specifically the switch circuit 432) cuts off the power supply to the control module 420. The relay 21 enters the off state, and the fixing module 10 is disconnected from the live wire L.

[0043] like Figure 1As shown, the thyristor control circuit 422 is connected to the safety interlock module 410, the time delay switch module 430, and the thyristor 22. The thyristor control circuit 422 is used to cut off the power supply to the thyristor after receiving the first electrical signal. Specifically, the thyristor control circuit 422 includes a thyristor control unit 4221 and a control switch. The control switch can be a MOSFET Q2. The source of the MOSFET Q2 is grounded, and the gate of the MOSFET Q2 is connected to both the safety interlock module 410 and the time delay switch module 430. The drain of the MOSFET Q2 is connected to the enable terminal of the thyristor control unit 4221 through a third resistor R3. The enable terminal of the control unit 4221 receives the first enable signal through the fourth resistor. When the gate of MOSFET Q2 does not receive the first signal, MOSFET Q2 is turned off. The enable terminal of the SCR control unit 4221 normally receives the first enable signal, and the SCR control unit 4221 does not cut off the power supply to SCR 22. However, after the gate of MOSFET Q2 receives the first signal, MOSFET Q2 turns on, pulling the enable terminal of the SCR control unit 4221 low (the first enable signal is pulled low). The SCR control unit 4221 cuts off the power supply to SCR 22, SCR 22 stops working, and SCR 22 begins to enter the turn-off state (i.e., Figure 3 (P1 in the middle), and it is only actually turned off when the mains voltage drops to near zero voltage (i.e. Figure 3 In P2), the fixing module 10 and the zero line N are disconnected.

[0044] In one alternative implementation, such as Figure 2 As shown, the delay switch module 430 also includes a power control circuit 433. The power control circuit 433 is connected to the switch circuit 432, the control module 420, and each of the sensors 30. The power control circuit 433 is used to control the input voltage to the switch circuit 432. Specifically, the power control circuit 433 can be a MOSFET Q3. The drain of the MOSFET Q3 is connected to the second voltage input, the source of the MOSFET Q3 is connected to the control module 420 and each of the sensors 30, and the gate of the MOSFET Q3 receives the second enable signal through the second resistor R2. The gate of the MOSFET Q3 is also connected to the drain of the MOSFET Q1. The source of MOSFET Q1 is grounded. When the gate of MOSFET Q1 does not receive the first signal, MOSFET Q1 is turned off. The gate of MOSFET Q3 normally receives the second enable signal, and MOSFET Q3 is turned on. The second voltage input supplies power to the control module 420 and each sensor 30. After the gate of MOSFET Q1 receives the first signal, MOSFET Q1 is turned on, and the gate of MOSFET Q3 is pulled low (the first enable signal is pulled low). MOSFET Q3 is turned off, cutting off the power supply of the second voltage input to the control module 420. Through the power control circuit, the input of the second voltage becomes controllable, which can improve circuit safety.

[0045] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A safety control system, characterized in that, include: A safety interlock module, which outputs a first electrical signal when triggered; The control module is connected to the safety interlock module and is used to connect to the relay and the thyristor respectively. The control module is also used to cut off the power supply to the thyristor after receiving the first electrical signal. A time-delay switch module is connected to the safety interlock module and the control module respectively. The time-delay switch module is used to cut off the power supply to the control module after a delay when the first electrical signal is received. The relay stops working after the power supply to the control module is cut off.

2. The safety control system according to claim 1, characterized in that, The time delay switch module includes: A switching circuit, wherein the switching circuit is connected to the control module; The delay circuit is connected to the safety interlock module and the switching circuit respectively. The delay circuit is used to cut off the power supply to the control module through the switching circuit after a delay when the first electrical signal is received.

3. The safety control system according to claim 2, characterized in that, The time delay switch module also includes: A power control circuit is provided, which is connected to the switching circuit and the control module respectively. The power control circuit is used to control the input voltage input to the switching circuit.

4. The safety control system according to claim 2, characterized in that, The delay circuit is an RC delay circuit.

5. The safety control system according to claim 2, characterized in that, The switching circuit includes at least one of a MOSFET or a transistor.

6. The safety control system according to claim 5, characterized in that, The input terminal of the switching circuit is used to receive the input voltage, the output terminal of the switching circuit is connected to the control module, and the control terminal of the switching circuit is connected to the delay circuit. If the switching circuit is a MOSFET, the drain of the MOSFET serves as the input terminal of the switching circuit, the source of the MOSFET serves as the output terminal of the switching circuit, and the gate of the MOSFET serves as the control terminal of the switching circuit.

7. The safety control system according to claim 1, characterized in that, The control module includes: A thyristor control circuit is provided, which is connected to the safety interlock module and is also used to connect to the thyristor. The thyristor control circuit is further used to cut off the power supply to the thyristor after receiving the first electrical signal.

8. The safety control system according to claim 7, characterized in that, The thyristor control circuit is also connected to the delay switch module.

9. The safety control system according to claim 1, characterized in that, The control module includes: A relay control circuit is provided, which is connected to the time delay switch module and is also used to connect to the relay. The relay control circuit is further used to stop the operation of the relay after the time delay switch module cuts off the power supply to the control module.

10. An image forming apparatus, characterized in that, Includes the safety control system described in any one of claims 1-9.

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