Fixing protection circuit, method and image forming apparatus

Abstract

The embodiment of the application provides a fixing protection circuit, a method and an image forming device, the fixing protection circuit comprises a temperature sensor, a first voltage division branch, a comparator and a controller; a first end of the temperature sensor is connected with a first pin of the controller and a first input end of the comparator, a second end of the temperature sensor is connected with a second end of the first voltage division branch, the second end of the temperature sensor is grounded, and a first end of the first voltage division branch is connected with a first power supply; a second input end of the comparator is used for inputting a preset temperature, and an output end of the comparator is connected with a second pin of the controller; the controller is used for configuring the first pin as an output interface from an input interface after power-on; the second pin is used for detecting an output signal of the comparator when the first pin is the input interface and the output interface respectively; and the controller is used for determining whether the comparator is abnormal according to the output signal of the comparator. The application does not need to increase an additional pin or circuit structure, improves the utilization rate of the pin, and saves the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image forming, in particular to a fixing protection circuit, method and image forming device. BACKGROUND

[0002] The fixing process of a laser printer is to fix the carbon powder image formed on the printing paper on the paper by heating and pressing. This process is mainly completed by a fixing device, which is usually composed of a heating roller and a pressing roller. Through the heating and pressing action of the two rollers, the carbon powder is melted and immersed into the paper, thereby forming a permanent image on the paper.

[0003] In order to avoid temperature overhigh caused by fixing heating abnormality, a protection circuit needs to be set. The protection circuit in the prior art uses a comparator. When the comparison relationship between the temperature signal and the reference level changes, the signal output by the comparator also changes, so that the switch tube or the relay is turned off, thereby realizing the hardware protection effect. However, if the comparator fails, the protection circuit may fail to execute the hardware protection when the fixing temperature is too high, thereby reducing the safety; and the hardware protection may be continuously turned on, so that the printer is continuously in an abnormal state and cannot work normally. SUMMARY

[0004] The fixing protection circuit, method and image forming device provided by the embodiments of the present application can detect the abnormality of the comparator in time and avoid overtemperature caused by circuit abnormality.

[0005] In a first aspect, the embodiments of the present application provide a fixing protection circuit, comprising: a temperature sensor, a first voltage division branch, a comparator and a controller.

[0006] The first end of the temperature sensor is connected with the first pin of the controller and the first input end of the comparator, the second end of the temperature sensor is connected with the second end of the first voltage division branch, the second end of the temperature sensor is grounded, and the first end of the first voltage division branch is connected with a first power supply;

[0007] The second input end of the comparator is used for inputting a preset temperature, and the output end of the comparator is connected with the second pin of the controller;

[0008] The controller is used for configuring the first pin as an output interface after power-on; the second pin is used for detecting the output signal of the comparator when the first pin is an input interface and an output interface respectively; and the controller is used for determining whether the comparator is abnormal according to the output signal of the comparator.

[0009] In one of the embodiments, the fixing protection circuit further comprises a second voltage division branch, the first end of the second voltage division branch is connected with the first power supply, the second end of the second voltage division branch is connected with the second input end of the comparator, and the second voltage division branch is used for generating the preset temperature.

[0010] In one of the embodiments, the controller is configured to

[0011] When the first pin is the input interface and the output interface, if the output signal of the comparator changes, it is determined that the comparator is normal.

[0012] If the output signal of the comparator does not change, it is determined that the comparator is abnormal.

[0013] In one of the embodiments, the fixing protection circuit further comprises a first switching device, a first end of the first switching device is connected with the second power supply and the second pin of the controller, a second end of the first switching device is connected with the fixing heater, and a third end of the first switching device is connected with the output end of the comparator; the first switching device is configured to disconnect the fixing heater from the second power supply when the comparator is abnormal.

[0014] In a second aspect, the embodiments of the present application provide a fixing protection circuit, comprising a temperature sensor, a comparator, a controller, a first voltage division branch and a delay circuit.

[0015] A first end of the temperature sensor is connected with a first pin of the controller and a first input end of the comparator, a second end of the temperature sensor is connected with a second end of the first voltage division branch, the second end of the temperature sensor is grounded, and a first end of the first voltage division branch is connected with a first power supply.

[0016] A second input end of the comparator is configured to input a preset temperature, and an output end of the comparator is connected with a second pin of the controller.

[0017] A first end of the delay circuit is connected with the first power supply, and a second end of the delay circuit is grounded; the delay circuit is configured to control the first input end of the comparator to be grounded after being powered on for a preset time.

[0018] The second pin of the controller is configured to detect the output signal of the comparator, and the controller is configured to determine whether the comparator is abnormal according to the output signal of the comparator.

[0019] In one of the embodiments, the fixing protection circuit further comprises a second voltage division branch, a first end of the second voltage division branch is connected with the first power supply, and a second end of the second voltage division branch is connected with a second input end of the comparator; the second voltage division branch is configured to generate the preset temperature.

[0020] In one of the embodiments, the delay circuit comprises a delay element and a second switching device.

[0021] A first end of the delay element is connected with the first power supply, a second end of the delay element is connected with a control end of the second switching device, a first end of the second switching device is connected with the first input end of the comparator, and a second end of the second switching device is grounded.

[0022] In one of the embodiments, the delay element is a time relay or a photoelectric switch.

[0023] In one of the embodiments, the fixing protection circuit further comprises a first switch device, a first end of the first switch device is connected with the second power supply and the second pin of the controller, a second end of the first switch device is connected with the fixing heater, and a third end of the first switch device is connected with the output end of the comparator.

[0024] The first switch device is used to disconnect the fixing heater from the second power supply when the comparator is abnormal.

[0025] In a third aspect, the embodiments of the present application provide an image forming apparatus, comprising the fixing protection circuit and the fixing heater as any of the above.

[0026] In a fourth aspect, the embodiments of the present application further provide a fixing detection method applied to the fixing protection circuit, the method comprising:

[0027] detecting a first signal at the output end of the comparator through the second pin;

[0028] configuring the first pin as an output interface from an input interface or delaying through the delay circuit, and then detecting a second signal at the output end of the comparator through the second pin again;

[0029] if the first signal and the second signal are different, determining that the comparator is normal;

[0030] if the first signal and the second signal are the same, determining that the comparator is abnormal.

[0031] The fixing protection circuit, method and image forming device provided by the embodiment of the application, the fixing protection circuit comprises a temperature sensor, a first voltage division branch, a comparator and a controller; a first end of the temperature sensor is connected with a first pin of the controller and a first input end of the comparator, a second end of the temperature sensor is connected with a second end of the first voltage division branch, the second end of the temperature sensor is grounded, and a first end of the first voltage division branch is connected with a first power supply; a second input end of the comparator is used for inputting a preset temperature, and an output end of the comparator is connected with a second pin of the controller; the controller is used for configuring the first pin as an output interface from an input interface after power-on; the second pin is used for detecting an output signal of the comparator when the first pin is the input interface and the output interface respectively; and the controller is used for determining whether the comparator is abnormal according to the output signal of the comparator. The application detects the output signal of the comparator through the second pin by configuring the interface of the first pin, if the output signal of the comparator changes when the first pin is configured as the output interface from the input interface, it is proved that the comparator is normal, and if the output signal of the comparator does not change, it is proved that the comparator is abnormal. The application can realize the detection of the abnormality of the comparator without adding additional pins or circuit structures, improves the utilization rate of the pins and saves the cost, and does not affect the normal work of the printer after the detection of the comparator is completed. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0033] Figure 1 The structure schematic diagram of the protection circuit provided by the application is shown in the figure.

[0034] Figure 2 The structure schematic diagram of the fixing protection circuit provided by the embodiment of the application is shown in the figure.

[0035] Figure 3 The structure schematic diagram of the fixing protection circuit provided by another embodiment of the application is shown in the figure.

[0036] Figure 4 The structure schematic diagram of the delay element provided by the embodiment of the application is shown in the figure.

[0037] Figure 5 The flow chart of the fixing detection method provided by the embodiment of the application is shown in the figure.

[0038] Figure 6 The structure schematic diagram of the controller provided by the application is shown in the figure.

[0039] Reference signs:

[0040] 210 Temperature sensor; 220 First voltage divider branch; 230 Second voltage divider branch; 240 Comparator; 250 First switching device; 260 Delay element; R1 First resistor; R2 Second resistor; R3 Third resistor; R4 Fourth resistor; R5 Fifth resistor; R6 Sixth resistor; R7 Seventh resistor.

[0041] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0042] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0043] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0044] The fusing process of a laser printer fixes the toner image formed on the printing paper onto the paper by heating and pressurizing it. This process is mainly completed by the fuser, which typically consists of a heating roller and a pressure roller. Through the heating and pressurizing action of the two rollers, the toner melts and penetrates into the paper, thereby forming a permanent image on the paper.

[0045] In the process of conceiving and implementing this application Figure 1 A schematic diagram of the protection circuit provided in this application is shown below. Figure 1 As shown, to prevent overheating caused by abnormal fixing heating, a protection circuit is required. This circuit includes a comparator, chip control pin 1, and chip control pin 2. When the comparison relationship between the temperature signal and the reference level changes, the comparator output signal also changes, causing the switching transistor or relay to turn off, thus achieving hardware protection. However, if the comparator malfunctions, the protection circuit may fail, preventing hardware protection from being executed when the fixing temperature exceeds the limit, thereby reducing safety. It may also cause the hardware protection to remain on, keeping the printer in an abnormal state and unable to function properly.

[0046] Therefore, to ensure the printer functions properly, the comparator's status needs to be checked upon power-on. In one embodiment, a switching circuit and a judgment circuit are added to the protection circuit. The switching circuit is connected to the two input terminals of the comparator, and the judgment circuit is connected to the comparator's output terminal. The switching circuit requires an additional pin to input a switching signal to detect any abnormalities in the comparator. The inventors found that this embodiment requires additional circuitry and pins, which increases the cost of the printer.

[0047] Based on the above embodiments, this application provides a fixing protection circuit, including: a temperature sensor, a first voltage divider branch, a comparator, and a controller; the first end of the temperature sensor is connected to the first pin of the controller and the first input terminal of the comparator, the second end of the temperature sensor is connected to the second end of the first voltage divider branch, the second end of the temperature sensor is grounded, and the first end of the first voltage divider branch is connected to a first power supply; the second input terminal of the comparator is used to input a preset temperature, and the output terminal of the comparator is connected to the second pin of the controller; the controller is used to configure the first pin from an input interface to an output interface after power-on; the second pin is used to detect the output signal of the comparator when the first pin is an input interface and an output interface, respectively; the controller is used to determine whether the comparator is abnormal based on the output signal of the comparator. This application controls the interface configuration of the first pin and detects the output signal of the comparator through the second pin. If the output signal of the comparator changes when the first pin is configured from an input interface to an output interface, it proves that the comparator is normal; if the output signal of the comparator does not change, it proves that the comparator is abnormal. Comparator abnormality detection can be achieved without adding additional pins or circuit structures, improving pin utilization and saving costs; secondly, the normal operation of the printer is not affected after the comparator detection is completed.

[0048] like Figure 2 As shown, Figure 2 This is a schematic diagram of a fixing protection circuit provided in an embodiment of this application. The fixing protection circuit includes: a temperature sensor 210, a first voltage divider branch 220, a comparator 240, and a controller. The first end of the temperature sensor 210 is connected to the first pin of the controller and the first input terminal of the comparator 240. The second end of the temperature sensor 210 is connected to the second end of the first voltage divider branch 220. The second end of the temperature sensor 210 is grounded. The first end of the first voltage divider branch 220 is connected to a first power supply. The second input terminal of the comparator 240 is used to input a preset temperature. The output terminal of the comparator 240 is connected to the second pin of the controller. The controller is used to configure the first pin from an input interface to an output interface after power-on. The second pin is used to detect the output signal of the comparator 240 when the first pin is an input interface and an output interface, respectively. The controller is used to determine whether the comparator 240 is abnormal based on the output signal of the comparator 240.

[0049] Temperature sensor 210 is used to detect the temperature of the fuser heater in real time. This application controls the interface configuration of the first pin. If the first pin is configured from an input interface to an output interface, the output signal of comparator 240 is detected through the second pin to determine the abnormal condition of comparator 240, so as to avoid the comparator 240 failing to protect the temperature of the fuser heater. Moreover, the comparator 240 can complete the self-test process after power-on, saving costs and improving pin utilization.

[0050] In one embodiment, the temperature sensor 210 is a thermistor.

[0051] In one embodiment, the controller is configured to determine that comparator 240 is normal if the output signal of comparator 240 changes when the first pin is an input interface and an output interface; and determine that comparator 240 is abnormal if the output signal of comparator 240 remains unchanged.

[0052] When the value of the first input terminal of comparator 240 changes, the output signal of comparator 240 changes accordingly, which indicates that comparator 240 is in a normal state and can perform normal printing. If the output signal of comparator 240 does not change with the value of the first input terminal of comparator 240, it indicates that comparator 240 is in an abnormal state and cannot perform normal printing.

[0053] exist Figure 2 In this embodiment, the output signal of comparator 240 is a level signal, and the second input terminal of comparator 240 is used to input a preset value. When the first pin is an input interface, the first input terminal of comparator 240 is connected to the first pin, and the current flow of the circuit is: first pin - thermistor - ground. Therefore, the first input terminal of comparator 240 is the first voltage of the thermistor. If the first voltage is greater than the preset value, the output signal of comparator 240 is low, the first switch device 250 is turned off, and the second pin detects a high level. If the first pin is an output interface, the current flow of the circuit is: first power supply - first voltage divider branch 220 - second terminal of the thermistor - first input terminal of comparator 240. After the voltage is divided by the first voltage divider branch 220, the first voltage of the thermistor will decrease, and the first voltage input to comparator 240 will also decrease, causing the first voltage to be less than the preset value, so that the output signal of comparator 240 is high, the first switch device 250 is turned on, and the second pin will detect a low level. If the level of the second pin remains unchanged when the first pin is configured as an output pin from the input interface, it indicates that the comparator 240 is malfunctioning. In this case, the printer will report a fault and will not be able to work normally.

[0054] In one embodiment, such as Figure 2As shown, the fixing protection circuit further comprises a second voltage dividing branch 230, a first end of the second voltage dividing branch 230 is connected with the first power supply, a second end of the second voltage dividing branch 230 is connected with a second input end of the comparator 240, and the second voltage dividing branch 230 is used to generate a preset temperature.

[0055] Optionally, the first input end of the comparator 240 is a negative input end of the comparator 240, and the second input end of the comparator 240 is a positive input end of the comparator 240.

[0056] In one embodiment, the first voltage dividing branch 220 comprises a first resistor R1 and a second resistor R2, and the second voltage dividing branch 230 comprises a third resistor R3 and a fourth resistor R4. A first end of the first resistor R1 is connected with the first power supply, a second end of the first resistor R1 is connected with a first end of the second resistor R2 and a first end of the temperature sensor 210, a second end of the second resistor R2 is connected with a second end of the temperature sensor 210, and the second end of the second resistor R2 is grounded. A first end of the third resistor R3 is connected with the first power supply, a second end of the third resistor R3 is connected with the second input end of the comparator 240 and a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is grounded. The first power supply is a power supply voltage VCC of the circuit.

[0057] In one embodiment, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 have the same resistance. In other embodiments, the resistance of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 can be selected according to actual conditions, and the application does not limit the resistance.

[0058] In one embodiment, the voltage of the first power supply is 5V or 3.3V.

[0059] In one embodiment, the controller is a control chip.

[0060] In one embodiment, the fixing protection circuit further comprises a first switching device 250, a first end of the first switching device 250 is connected with the second power supply and a second pin of the controller, a second end of the first switching device 250 is connected with the fixing heater, and a third end of the first switching device 250 is connected with an output end of the comparator 240; the first switching device 250 is used to disconnect the fixing heater from the second power supply when the comparator 240 is abnormal.

[0061] In one embodiment, when the comparator 240 is abnormal, the output signal of the comparator 240 is low, at this time, the light emitting device is disconnected, and the second power supply stops supplying power to the fixing heater. If the comparator 240 is normal, the output signal of the comparator 240 is high, at this time, the first switching device 250 is turned on, and the second power supply supplies power to the fixing heater, so that the printer can work normally.

[0062] Specifically, both the first and second pins are controller pins, and the controller's power supply voltage is VCC. When the first pin is an input interface, the voltage at the first input terminal of comparator 240 is VCC, and the voltage at the second input terminal of comparator 240 is... The voltage at the second input terminal of comparator 240 is less than the voltage at the first input terminal, therefore the output of comparator 240 is low. When the first pin is the output interface, the second resistor R2 and the thermistor R are connected in parallel, therefore the voltage at the first input terminal of comparator 240 is... R0 is the resistance of the second resistor R2 and the thermistor R connected in parallel, and the voltage at the second input terminal of comparator 240 is... The resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are set such that the voltage at the first input terminal of comparator 240 is less than the voltage at the second input terminal of comparator 240, resulting in a high-level output from comparator 240. Therefore, when the configuration of the first pin changes, the comparator 240 can automatically complete its self-test without affecting the printer's operation. This application eliminates the need for additional pins on the controller to detect the comparator 240's status; the detection can be performed using existing pins, saving costs.

[0063] In one embodiment, when comparator 240 confirms that the printer is working properly, the output interface of the first pin can be reconfigured as an input interface without affecting the normal operation of the printer.

[0064] In one embodiment, the first switching device 250 is a switching element such as a transistor or a MOSFET. In the embodiments of this application, the first switching device 250 is an NPN transistor.

[0065] In one embodiment, such as Figure 3 As shown, Figure 3 This is a schematic diagram of a fixing protection circuit provided in another embodiment of this application. The fixing protection circuit includes a temperature sensor 210, a comparator 240, a controller, a first voltage divider branch 220, and a delay circuit. The first end of the temperature sensor 210 is connected to the first pin of the controller and the first input terminal of the comparator 240. The second end of the temperature sensor 210 is connected to the second end of the first voltage divider branch 220 and is grounded. The first end of the first voltage divider branch 220 is connected to a first power supply. The second input terminal of the comparator 240 is used to input a preset temperature, and the output terminal of the comparator 240 is connected to the second pin of the controller. The first end of the delay circuit is connected to the first power supply, and the second end of the delay circuit is grounded. The delay circuit is used to delay the grounding of the first input terminal of the comparator 240 by a preset time after power-on. The second pin of the controller is used to detect the output signal of the comparator 240, and the controller is used to determine whether the comparator 240 is abnormal based on the output signal of the comparator 240.

[0066] Specifically, when the fixing protection circuit is powered on, the voltage at the first input terminal of the comparator 240 is greater than the voltage at the second input terminal of the comparator 240, and the comparator 240 outputs a low level; after being delayed by the delay circuit, the voltage at the first input terminal of the comparator 240 is pulled to ground, at this time, the voltage at the second input terminal of the comparator 240 is greater than the voltage at the first input terminal, and the comparator 240 outputs a high level. If the comparator 240 is abnormal, after being delayed by the delay circuit, the output level of the comparator 240 does not change, so the controller determines whether the output signal of the comparator 240 changes through the second pin, and further determines whether the comparator 240 is abnormal. The self-checking process of the comparator 240 can be completed by using only one pin and a delay circuit in the present application, compared with the prior art, the number of pins is saved. Figure 2

[0067] In one of the embodiments, as shown in Figure 3 , the delay circuit comprises a delay element 260 and a second switch device; the first end of the delay element 260 is connected with the first power supply, the second end of the delay element 260 is connected with the control end of the second switch device, the first end of the second switch device is connected with the first input terminal of the comparator 240, and the second end of the second switch device is grounded.

[0068] Optionally, a seventh resistor R7 is further connected between the second end of the delay element 260 and the control end of the second switch device. The seventh resistor R7 is used for protecting the second switch device and stabilizing the performance of the circuit, so as to ensure that the second switch device operates under suitable working conditions.

[0069] In one of the embodiments, the delay element 260 is a time relay or a photoelectric switch. As shown in Figure 4 , the structure schematic diagram of the delay element 260 provided by one of the embodiments of the present application is shown in Figure 4 . Figure 4 In the embodiment, when the fixing protection circuit is powered on, the coil of the relay has no voltage passing through, and the delay element 260 is off; after the second pin detects a high level for several seconds, the coil is triggered by a trigger voltage with a low-high-low pulse, the delay element 260 is turned on, and after the second pin detects a low level, the coil of the delay element 260 loses voltage, and the delay element 260 is closed again. The trigger voltage can be understood as a pulse voltage with low-high-low. The trigger voltage of the coil can be supplied through the second pin or the power supply of the printer, wherein there are many ways to convert the power supply voltage into a pulse voltage, which will not be described here.

[0070] ​In one of the embodiments, the second switch device is a triode, a MOS tube or other switch type element.

[0071] In one of the embodiments, the fixing protection circuit further comprises a second voltage dividing branch 230, a first end of the second voltage dividing branch 230 is connected with the first power supply, a second end of the second voltage dividing branch 230 is connected with a second input end of the comparator 240, and the second voltage dividing branch 230 is used to generate a preset temperature.

[0072] Optionally, the first input end of the comparator 240 is a negative input end of the comparator 240, and the second input end of the comparator 240 is a positive input end of the comparator 240.

[0073] In one of the embodiments, the first voltage dividing branch 220 comprises a first resistor R1 and a second resistor R2, and the second voltage dividing branch 230 comprises a third resistor R3 and a fourth resistor R4. A first end of the first resistor R1 is connected with the first power supply, a second end of the first resistor R1 is connected with a first end of the second resistor R2 and a first end of the temperature sensor 210, a second end of the second resistor R2 is connected with a second end of the temperature sensor 210, and the second end of the second resistor R2 is grounded. A first end of the third resistor R3 is connected with the first power supply, a second end of the third resistor R3 is connected with the second input end of the comparator 240 and a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is grounded. The first power supply is a power supply voltage VCC of the circuit.

[0074] In one of the embodiments, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 have equal resistance values. In other embodiments, the resistance values of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 can be selected according to actual conditions, and the application does not limit the resistance values.

[0075] In one of the embodiments, the voltage of the first power supply is 5V or 3.3V.

[0076] In one of the embodiments, the controller is a control chip.

[0077] In one of the embodiments, the fixing protection circuit further comprises a first switch device 250, a first end of the first switch device 250 is connected with a second power supply and a second pin of the controller, a second end of the first switch device 250 is connected with the fixing heater, a third end of the first switch device 250 is connected with an output end of the comparator 240, and the first switch device 250 is used to disconnect the fixing heater from the second power supply when the comparator 240 is abnormal.

[0078] Specifically, the delay circuit is initially in an off state, the voltage at the first input end of the comparator 240 is greater than the voltage at the second input end, the output level of the comparator 240 is low, the first switch device is off, and the second pin detects a high level; after a preset time, the delay circuit is turned on, the first input end of the comparator 240 is pulled low to the ground, and the voltage at the second input end of the comparator 240 is greater than the voltage at the first input end. If the state of the comparator 240 is normal, the output level of the comparator 240 will change to high, the first switch device 250 is turned on, and the second pin detects a low level. If the level does not change, the fixing protection unit is abnormal.

[0079] An image forming apparatus is provided in an embodiment of the present application, which comprises the fixing protection circuit and the fixing heater as any of the above.

[0080] An image forming apparatus is provided in an embodiment of the present application, which comprises the fixing protection circuit and the fixing heater as any of the above. Figure 5 Figure 5 A flow chart of a fixing detection method is provided in an embodiment of the present application. The method is applied to the fixing protection circuit as above, and comprises the following steps:

[0081] In step S502, the first signal at the output end of the comparator 240 is detected through the second pin.

[0082] In step S504, the first pin is configured as an output interface through the input interface or after being delayed by the delay circuit, and the second signal at the output end of the comparator 240 is detected again through the second pin.

[0083] Specifically, for the embodiment in the fixing protection circuit, the second pin detects the second signal when the first pin is configured as an output interface through the input interface. For the embodiment in the fixing protection circuit, the second pin detects the second signal after being delayed by the delay circuit. Figure 2 Figure 3

[0084] In step S505, if the first signal and the second signal are different, it is determined that the comparator 240 is normal.

[0085] In step S506, if the first signal and the second signal are the same, it is determined that the comparator 240 is abnormal.

[0086] The present application determines whether the fixing protection circuit is normal before the printer is started each time, and stops the printing work of the printer after detecting that the comparator 240 is abnormal, thereby effectively avoiding the failure of the over-temperature protection caused by the failure of the fixing protection circuit. The circuit of the present application is simple, does not need to increase an additional pin, and saves cost and resources.

[0087] Figure 6 A structure diagram of a controller is provided in the present application, as shown in Figure 6 ​​​As shown, the controller 50 provided by the embodiment includes at least one processor 501 and a memory 502. Optionally, the device 50 further includes a communication component 503. Wherein, the processor 501, the memory 502 and the communication component 503 are connected through a bus 504.

[0088] In the implementation process, the at least one processor 501 executes the computer execution instructions stored in the memory 502, so that the at least one processor 501 executes the above-mentioned method.

[0089] The specific implementation process of the processor 501 can refer to the above-mentioned method embodiment, which has similar implementation principles and technical effects, and will not be described here in detail.

[0090] In the above-mentioned embodiment, it should be understood that the processor can be a central processing unit (English: Central Processing Unit, for short: CPU), and can also be other general-purpose processors, digital signal processors (English: Digital Signal Processor, for short: DSP), application specific integrated circuits (English: Application Specific Integrated Circuit, for short: ASIC) and the like. The general-purpose processor can be a microprocessor, or the processor can be any conventional processor, etc. The steps of the method disclosed in combination with the application can be directly embodied as hardware processor execution, or executed by hardware and software modules in the processor.

[0091] The memory can contain a high-speed memory (Random Access Memory, RAM), and can also include a non-volatile memory (Non-volatile Memory, NVM), for example, at least one disk memory.

[0092] The bus can be an industry standard architecture (Industry Standard Architecture, ISA) bus, a peripheral component interconnect (Peripheral Component, PCI) bus or an extended industry standard architecture (Extended Industry Standard Architecture, EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, the bus in the drawings of the present application does not limit only one bus or one type of bus.

[0093] The present application also provides a computer program product, comprising a computer program, which is executed by a processor to realize the above-mentioned method.

[0094] The application further provides a computer readable storage medium, and the computer readable storage medium stores computer execution instructions.

[0095] The readable storage medium can be implemented by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0096] An exemplary readable storage medium is coupled to the processor, so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (ASIC). Of course, the processor and the readable storage medium can also exist as discrete components in the device.

[0097] The division of units is only a logical function division, and in actual implementation, there can be another division mode, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0098] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment.

[0099] In addition, the functional units in each embodiment of the application can be integrated into one processing unit, or each unit can be physically present separately, or two or more units can be integrated into one unit.

[0100] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the parts of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the embodiments of the method of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0101] It can be understood by those skilled in the art that all or part of the steps of the above-mentioned method embodiments can be completed by program instruction related hardware. The aforementioned program can be stored in a computer readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk, and various media that can store program codes.

[0102] Finally, it should be noted that: those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application that follow the general principles of the present application and include common knowledge or conventional technical means in the art that are not disclosed in the present application, and is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. A fixing protection circuit, characterized in that, include: Temperature sensor, first voltage divider branch, comparator and controller; The first end of the temperature sensor is connected to the first pin of the controller and the first input terminal of the comparator. The second end of the temperature sensor is connected to the second end of the first voltage divider branch. The second end of the temperature sensor is grounded. The first end of the first voltage divider branch is connected to the first power supply. The second input terminal of the comparator is used to input a preset temperature, and the output terminal of the comparator is connected to the second pin of the controller; The controller is used to configure the first pin from an input interface to an output interface after power-on; the second pin is used to detect the output signal of the comparator when the first pin is an input interface and an output interface, respectively; the controller is used to determine whether the comparator is abnormal based on the output signal of the comparator.

2. The fixing protection circuit according to claim 1, characterized in that, The fixing protection circuit further includes a second voltage divider branch, the first end of which is connected to the first power supply, and the second end of which is connected to the second input terminal of the comparator. The second voltage divider branch is used to generate a preset temperature.

3. The fixing protection circuit according to claim 1, characterized in that, The controller is used for When the first pin is both an input interface and an output interface, if the output signal of the comparator changes, it is determined that the comparator is normal. If the output signal of the comparator remains unchanged, the comparator is determined to be faulty.

4. A fixing protection circuit, characterized in that, Includes a temperature sensor, comparator, controller fixing protection circuit, first voltage divider branch, and delay circuit; The first end of the temperature sensor is connected to the first pin of the controller and the first input terminal of the comparator. The second end of the temperature sensor is connected to the second end of the first voltage divider branch. The second end of the temperature sensor is grounded. The first end of the first voltage divider branch is connected to the first power supply. The second input terminal of the comparator is used to input a preset temperature, and the output terminal of the comparator is connected to the second pin of the controller; The first terminal of the delay circuit is connected to the first power supply, and the second terminal of the delay circuit is grounded; the delay circuit is used to control the first input terminal of the comparator to be grounded after a preset time delay following power-on. The second pin of the controller is used to detect the output signal of the comparator, and the controller is used to determine whether the comparator is abnormal based on the output signal of the comparator.

5. The fixing protection circuit according to claim 4, characterized in that, The fixing protection circuit further includes a second voltage divider branch, the first end of which is connected to the first power supply, and the second end of which is connected to the second input terminal of the comparator. The second voltage divider branch is used to generate a preset temperature.

6. The fixing protection circuit according to claim 4, characterized in that, The delay circuit includes a delay element and a second switching device; The first end of the delay element is connected to the first power supply, the second end of the delay element is connected to the control terminal of the second switching device, the first end of the second switching device is connected to the first input terminal of the comparator, and the second end of the second switching device is grounded.

7. The fixing protection circuit according to claim 6, characterized in that, The delay element is a time relay or a photoelectric switch.

8. The fixing protection circuit according to any one of claims 4-7, characterized in that, The fixing protection circuit further includes a first switching device, the first end of which is connected to the second power supply and the second pin of the controller, the second end of which is connected to the fixing heater, and the third end of which is connected to the output of the comparator. The first switching device is used to disconnect the fixing heater from the second power supply when the comparator malfunctions.

9. An image forming apparatus, characterized in that, It includes a fixing protection circuit and a fixing heater as described in any one of claims 1-8, wherein the fixing protection circuit is connected to the fixing heater.

10. A fixing detection method, characterized in that, The method, applied to the fixing protection circuit according to any one of claims 1-8, comprises: The first signal at the comparator output is detected via the second pin. The first pin is configured from an input interface to an output interface or delayed by a delay circuit, and the second signal at the comparator output is detected again through the second pin. If the first signal and the second signal are different, the comparator is determined to be normal; If the first signal and the second signal are the same, the comparator is determined to be faulty.

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