Fixing protection circuit and method, and image forming apparatus

Abstract

The embodiment of the invention provides a fixing protection circuit, a fixing protection method and an image forming device. The fixing protection circuit comprises a temperature sensor, a first voltage dividing 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 dividing branch, the second end of the temperature sensor is grounded, and a first end of the first voltage dividing 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 from the input interface to the output interface after power-on; the second pin is used for respectively detecting an output signal of the comparator when the first pin is the input interface and the output interface; the controller is used for determining whether the comparator is abnormal according to the output signal of the comparator. No extra pin or circuit structure needs to be added, the pin utilization rate is improved, and the cost is saved.

Description

Technical Field

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

[0002] The fusing process of a laser printer is to fix the toner image formed on the printing paper on the paper by means of heating and pressure. This process is mainly completed by the fuser, which is usually composed of a heating roller and a pressure roller. Through the heating and pressure of the two rollers, the toner is melted and soaked into the paper, thus forming a permanent image on the paper.

[0003] In order to avoid overheating caused by abnormal fixing heating, 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, causing the switch tube or relay to be turned off, thereby achieving a hardware protection effect. However, if the comparator fails, it may cause the protection circuit to malfunction, and the hardware protection cannot be performed when the fixing temperature is too high, thereby reducing safety; it may also cause the hardware protection to continue to be turned on, causing the printer to continue to be in an abnormal state and unable to work normally. Summary of the invention

[0004] The embodiments of the present application provide a fixing protection circuit, method and image forming device, which are used to detect the abnormality of the comparator in time and avoid overheating caused by circuit abnormality.

[0005] In a first aspect, an embodiment of the present application provides a fixing protection circuit, comprising: a temperature sensor, a first voltage dividing branch, a comparator, and a controller;

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

[0007] 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;

[0008] 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.

[0009] In one embodiment, the fixing protection circuit further includes a second voltage dividing branch, a first end of the second voltage dividing branch is connected to the first power supply, a second end of the second voltage dividing branch is connected to the second input end of the comparator, and the second voltage dividing branch is used to generate a preset temperature.

[0010] In one embodiment, the controller is used to

[0011] When the first pin is an input interface and an 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 embodiment, the fixing protection circuit also includes a first switching device, a first end of the first switching device is connected to the second power supply and the second pin of the controller, a second end of the first switching device is connected to the fixing heater, and a third end of the first switching device is connected to the output end of the comparator; the first switching device is used to disconnect the fixing heater from the second power supply when the comparator is abnormal.

[0014] In a second aspect, an embodiment of the present application provides a fixing protection circuit, including a temperature sensor, a comparator, a controller, a first voltage dividing branch and a delay circuit;

[0015] The first end of the temperature sensor is connected to the first pin of the controller and the first input end 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 the first power supply;

[0016] 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;

[0017] 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 first input end of the comparator to ground for a preset time after power-on;

[0018] 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 according to the output signal of the comparator.

[0019] In one embodiment, the fixing protection circuit further includes a second voltage dividing branch, a first end of the second voltage dividing branch is connected to the first power supply, a second end of the second voltage dividing branch is connected to the second input end of the comparator, and the second voltage dividing branch is used to generate a preset temperature.

[0020] In one embodiment, the delay circuit includes a delay element and a second switch device;

[0021] 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 end of the second switch device, the first end of the second switch device is connected to the first input end of the comparator, and the second end of the second switch device is grounded.

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

[0023] In one embodiment, the fixing protection circuit further includes a first switch device, a first end of the first switch device is connected to the second power supply and the second pin of the controller, a second end of the first switch device is connected to the fixing heater, and a third end of the first switch device is connected to 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, an embodiment of the present application provides an image forming device, comprising any of the above-mentioned fixing protection circuits and a fixing heater, wherein the fixing protection circuit is connected to the fixing heater.

[0026] In a fourth aspect, an embodiment of the present application further provides a fixing detection method, which is applied to the above-mentioned fixing protection circuit, and the method includes:

[0027] detecting a first signal at an output terminal of the comparator via a second pin;

[0028] The first pin is configured from an input interface to an output interface or after being delayed by a delay circuit, the second signal at the output end of the comparator is detected again through the second pin;

[0029] If the first signal and the second signal are different, it is determined that the comparator is normal;

[0030] If the first signal and the second signal are the same, it is determined that the comparator is abnormal.

[0031] The embodiment of the present application provides a fixing protection circuit, method and image forming device, the fixing protection circuit includes: a temperature sensor, a first voltage-dividing 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 end of the comparator, the second end of the temperature sensor is connected to the second end of the first voltage-dividing branch, the second end of the temperature sensor is grounded, and the first end of the first voltage-dividing branch is connected to the first power supply; the second input end of the comparator is used to input a preset temperature, and the output end 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 respectively detect the output signal of the comparator when the first pin is an input interface and an output interface; the controller is used to determine whether the comparator is abnormal according to the output signal of the comparator. The present 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. The detection of comparator abnormality can be realized without adding additional pins or circuit structures, thereby improving pin utilization and saving costs; secondly, after the comparator detection is completed, the normal operation of the printer is not affected. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0033] Figure 1 A schematic diagram of the structure of the protection circuit provided in this application;

[0034] Figure 2 A structural schematic diagram of a fixing protection circuit provided in an embodiment of the present application;

[0035] Figure 3 A structural schematic diagram of a fixing protection circuit provided by another embodiment of the present application;

[0036] Figure 4 A schematic diagram of the structure of a delay element provided in one embodiment of the present application;

[0037] Figure 5 A flowchart of a fixing detection method provided in one embodiment of the present application;

[0038] Figure 6 A schematic diagram of the structure of the controller provided in this application.

[0039] Reference numerals:

[0040] 210, temperature sensor; 220, first voltage-dividing branch; 230, second voltage-dividing branch; 240, comparator; 250, first switch 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 above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

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

[0044] The fusing process of a laser printer is to fix the toner image formed on the printing paper on the paper by means of heating and pressure. This process is mainly completed by the fuser, which is usually composed of a heating roller and a pressure roller. Through the heating and pressure of the two rollers, the toner is melted and soaked into the paper, thus forming a permanent image on the paper.

[0045] In the process of conceiving and implementing this application, Figure 1 The structural diagram of the protection circuit provided in this application is as follows: Figure 1 As shown, in order to avoid overheating caused by abnormal fixing heating, a protection circuit needs to be set. The protection 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 signal output by the comparator also changes, causing the switch tube or relay to be turned off, thereby achieving the hardware protection effect. However, if the comparator fails, it may cause the protection circuit to fail, and the hardware protection cannot be performed when the fixing temperature is overheated, thereby reducing safety; it may also cause the hardware protection to continue to be turned on, causing the printer to continue to be in an abnormal state and unable to work normally.

[0046] Therefore, in order to make the printer work normally, it is necessary to confirm the comparator status when turning on the printer. 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 output terminal of the comparator. The switching circuit requires an additional pin to input a switching signal to detect abnormal conditions of the comparator. The inventor found that this embodiment requires the addition of additional circuits and pins, which will increase the cost of the printer.

[0047] In combination with the above embodiments, the present application provides a fixing protection circuit, including: a temperature sensor, a first voltage-dividing 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 end of the comparator, the second end of the temperature sensor is connected to the second end of the first voltage-dividing branch, the second end of the temperature sensor is grounded, and the first end of the first voltage-dividing branch is connected to the first power supply; the second input end of the comparator is used to input a preset temperature, and the output end 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 respectively detect the output signal of the comparator when the first pin is an input interface and an output interface; the controller is used to determine whether the comparator is abnormal according to the output signal of the comparator. The present 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. Without adding additional pins or circuit structures, the detection of comparator abnormality can be realized, the pin utilization rate is improved, and the cost is saved; secondly, after the detection of the comparator is completed, the normal operation of the printer is not affected.

[0048] like Figure 2 As shown, Figure 2 This is a structural schematic diagram of a fixing protection circuit provided in an embodiment of the present application, wherein the fixing protection circuit includes: a temperature sensor 210, a first voltage dividing branch 220, a comparator 240 and a controller; a first end of the temperature sensor 210 is connected to a first pin of the controller and a first input end of the comparator 240, a second end of the temperature sensor 210 is connected to a second end of the first voltage dividing branch 220, the second end of the temperature sensor 210 is grounded, and a first end of the first voltage dividing branch 220 is connected to a first power supply; a second input end of the comparator 240 is used to input a preset temperature, and an output end of the comparator 240 is connected to a 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; and the controller is used to determine whether the comparator 240 is abnormal based on the output signal of the comparator 240.

[0049] The temperature sensor 210 is used to detect the temperature of the fixing heater in real time. The present 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 the comparator 240 is detected by the second pin to determine the abnormality of the comparator 240, thereby avoiding the failure of the comparator 240 to protect the temperature of the fixing heater; and the self-test process of the comparator 240 can be completed after the power is turned on, thereby saving costs and improving pin utilization.

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

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

[0052] When the value of the first input terminal of the comparator 240 changes, the output signal of the comparator 240 changes accordingly, and it can be determined that the state of the comparator 240 is normal and normal printing work is performed; if the output signal of the comparator 240 does not change with the value of the first input terminal of the comparator 240, it is determined that there is an abnormality in the comparator 240 and normal printing work cannot be performed.

[0053] exist Figure 2 In the embodiment, the output signal of the comparator 240 is a level signal, and the second input end of the comparator 240 is used to input a preset value. When the first pin is an input interface, the first input end of the comparator 240 is connected to the first pin, and the current flow of the circuit is: first pin-thermistor-ground. Therefore, the first input end of the comparator 240 inputs the first voltage of the thermistor. If the first voltage is greater than the preset value, the output signal of the comparator 240 is a low level, the first switch device 250 is disconnected, and the second pin detects a high level; if the first pin is an output interface, at this time, the current flow of the circuit is: first power supply-first voltage dividing branch 220-second end of the thermistor-first input end of the comparator 240. After the voltage is divided by the first voltage dividing branch 220, the first voltage of the thermistor will decrease, and the first voltage input to the comparator 240 will also decrease, causing the first voltage to be less than the preset value, so that the output signal of the comparator 240 is a high level, the first switch device 250 is turned on, and the second pin will detect a low level. If the first pin is configured from an input interface to an output interface, and the second pin detects that the level remains unchanged, it proves that the comparator 240 is abnormal. At this time, the printer reports a fault and the printer cannot work normally.

[0054] In one embodiment, if Figure 2As shown, the fixing protection circuit also includes a second voltage dividing branch 230, a first end of the second voltage dividing branch 230 is connected to the first power supply, a second end of the second voltage dividing branch 230 is connected to the 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 terminal of the comparator 240 is a negative input terminal of the comparator 240 , and the second input terminal of the comparator 240 is a positive input terminal of the comparator 240 .

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

[0057] In one embodiment, the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are equal. 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 present application does not limit the resistance values.

[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 also includes a first switching device 250, a first end of the first switching device 250 is connected to the second power supply and the second pin of the controller, a second end of the first switching device 250 is connected to the fixing heater, and a third end of the first switching device 250 is connected to the 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 level, at this time, the opening 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 level, at this time, the first switch 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, the first pin and the second pin are both pins of the controller, and the power supply voltage of the controller is VCC. When the first pin is an input interface, the voltage of the first input terminal of the comparator 240 is VCC, and the voltage of the second input terminal of the comparator 240 is VCC*R4(R3+R4). The voltage of the second input terminal of the comparator 240 is less than the voltage of the first input terminal, so the output of the comparator 240 is a low level. When the first pin is an output interface, the second resistor R2 and the thermistor R are connected in parallel, so the voltage of the first input terminal of the comparator 240 is VCC*R0 / (R0+R1), R0 is the resistance of the second resistor R2 and thermistor R in parallel, and the voltage of the second input terminal of the comparator 240 is VCC*R4 / (R3+R4). The resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are set so that the voltage of the first input terminal of the comparator 240 is less than the voltage of the second input terminal of the comparator 240, and the output of the comparator 240 is a high level. Therefore, when the configuration of the first pin changes, the self-checking work of the comparator 240 can be automatically completed without affecting the use of the printer. This application does not need to use additional pins of the controller to detect the state of the comparator 240, and the detection can be completed on the basis of the existing pins, saving costs.

[0063] In one embodiment, when the comparator 240 confirms that it is normal, 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 switch device 250 is a switch type element such as a transistor, a MOS transistor, etc. In the embodiment of the present application, the first switch device 250 is an NPN transistor.

[0065] In one embodiment, if Figure 3 As shown, Figure 3 A structural schematic diagram of a fixing protection circuit provided by another embodiment of the present application. The fixing protection circuit includes a temperature sensor 210, a comparator 240, a controller, a first voltage-dividing 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 end of the comparator 240, the second end of the temperature sensor 210 is connected to the second end of the first voltage-dividing branch 220, the second end of the temperature sensor 210 is grounded, and the first end of the first voltage-dividing branch 220 is connected to the first power supply; the second input end of the comparator 240 is used to input a preset temperature, and the output end 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 preset time after power-on to control the first input end of the comparator 240 to be grounded; 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 according to the output signal of the comparator 240.

[0066] Specifically, when the fixing protection circuit is turned 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 down to the 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, the output level of the comparator 240 will not change after being delayed by the delay circuit. Therefore, the controller determines whether the output signal of the comparator 240 has changed through the second pin, and further determines whether the comparator 240 is abnormal. The present application only requires one pin and a delay circuit to complete the self-test process of the comparator 240, which is different from the conventional method. Figure 2 Embodiments of the present invention save the number of pins.

[0067] In one embodiment, if Figure 3 As shown, the delay circuit includes a delay element 260 and a second switch device; the first end of the delay element 260 is connected to the first power supply, the second end of the delay element 260 is connected to the control end of the second switch device, the first end of the second switch device is connected to the first input end 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 to protect the second switch device, stabilize circuit performance, and ensure that the second switch device operates under appropriate working conditions.

[0069] In one embodiment, the delay element 260 is a time relay or a photoelectric switch. Figure 4 As shown, Figure 4 A schematic diagram of the structure of a delay element 260 provided in an embodiment of the present application. Figure 4 The delay element 260 in is a time relay, which includes a coil and a switch. When the coil is not energized, no electromagnetic field force is generated, the switch is disconnected, and the relay is not turned on. When the coil is energized, the coil generates electromagnetic field force and the switch is turned on. In an embodiment of the present application, when the fixing protection circuit is turned on, no voltage passes through the coil of the relay, and the delay element 260 is turned off. After the second pin detects a high level for a few seconds, the coil is triggered by a high level trigger voltage, and the delay element 260 is turned on. After the second pin detects a low level, the delay element 260 coil loses voltage, and the delay element 260 is turned off again. The trigger voltage can be understood as a pulse voltage with low highs and lows. The trigger voltage of the coil can be supplied through the second pin, or it can be supplied through the printer power supply. There are many ways to convert the power supply voltage into a pulse voltage, which will not be described one by one here.

[0070] In one embodiment, the second switch device is a switch-type element such as a triode, a MOS tube, etc.

[0071] In one embodiment, the fixing protection circuit further includes a second voltage dividing branch 230, a first end of the second voltage dividing branch 230 is connected to the first power supply, a second end of the second voltage dividing branch 230 is connected to the 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 terminal of the comparator 240 is a negative input terminal of the comparator 240 , and the second input terminal of the comparator 240 is a positive input terminal of the comparator 240 .

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

[0074] In one embodiment, the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are equal. 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 present application does not limit the resistance values.

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

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

[0077] In one embodiment, the fixing protection circuit also includes a first switching device 250, a first end of the first switching device 250 is connected to the second power supply and the second pin of the controller, a second end of the first switching device 250 is connected to the fixing heater, and a third end of the first switching device 250 is connected to the 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.

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

[0079] An embodiment of the present application provides an image forming device, comprising any of the above-mentioned fixing protection circuits and a fixing heater, wherein the fixing protection circuit is connected to the fixing heater.

[0080] The present application also provides a fixing detection method, such as Figure 5 As shown, Figure 5 This is a flowchart of a fixing detection method provided in an embodiment of the present application. The method is applied to the above-mentioned fixing protection circuit, and the method includes the following steps:

[0081] Step S502: Detect a first signal at the output end of the comparator 240 through the second pin.

[0082] Step S504: configure the first pin from an input interface to an output interface or detect the second signal at the output end of the comparator 240 again through the second pin after delaying by the delay circuit.

[0083] Specifically, for Figure 2 In the embodiment of the present invention, the second pin detects a second signal when the first pin is configured from an input interface to an output interface. Figure 3 In the embodiment, the second pin detects the second signal after being delayed by the delay circuit.

[0084] Step S505: If the first signal and the second signal are different, it is determined that the comparator 240 is normal.

[0085] Step S506: If the first signal and the second signal are the same, determine that the comparator 240 is abnormal.

[0086] This application determines whether the fixing protection circuit is operating normally before the printer is turned on each time. After detecting an abnormality in the comparator 240, the printer stops printing, effectively avoiding over-temperature protection failure caused by a fault in the fixing protection circuit. The circuit of this application is simple and does not require additional pins, saving costs and resources.

[0087] Figure 6 A schematic diagram of the structure of the controller provided for this application, such as Figure 6As shown, the controller 50 provided in this embodiment includes: at least one processor 501 and a memory 502. Optionally, the device 50 further includes a communication component 503. The processor 501, the memory 502 and the communication component 503 are connected via a bus 504.

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

[0089] The specific implementation process of the processor 501 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0090] In the above embodiments, it should be understood that the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly implemented as a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0091] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (NVM), such as at least one disk storage.

[0092] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0093] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0094] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0095] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device 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 memory, 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 a 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 a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0097] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

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

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

[0100] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0101] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. 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, disk or optical disk and other media that can store program codes.

[0102] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A fixing protection circuit, characterized in that: include: A temperature sensor, a first voltage dividing 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 end of the comparator, the second end of the temperature sensor is connected to the second end of the first voltage dividing branch, the second end of the temperature sensor is grounded, and the first end of the first voltage dividing 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.

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

3. The fixing protection circuit according to claim 1, characterized in that: The controller is used to When the first pin is 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 does not change, it is determined that the comparator is abnormal.

4. A fixing protection circuit, characterized in that: It includes a temperature sensor, a comparator, a controller fixing protection circuit, a first voltage dividing branch and a delay circuit; The first end of the temperature sensor is connected to the first pin of the controller and the first input end of the comparator, the second end of the temperature sensor is connected to the second end of the first voltage dividing branch, the second end of the temperature sensor is grounded, and the first end of the first voltage dividing 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 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 a preset time after power-on to control the first input end of the comparator to be grounded; 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 according to the output signal of the comparator.

5. The fixing protection circuit according to claim 4, characterized in that: The fixing protection circuit also includes a second voltage dividing branch, a first end of the second voltage dividing branch is connected to the first power supply, a second end of the second voltage dividing branch is connected to the second input end of the comparator, and the second voltage dividing 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 end of the second switch device, the first end of the second switch device is connected to the first input end of the comparator, and the second end of the second switch 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 to 7, characterized in that: The fixing protection circuit further comprises a first switch device, a first end of the first switch device is connected to the second power supply and the second pin of the controller, a second end of the first switch device is connected to the fixing heater, and a third end of the first switch device is connected to the output end of the comparator; The first switch device is used to disconnect the fixing heater from the second power source when the comparator is abnormal.

9. An image forming device, characterized in that: The invention comprises a fixing protection circuit and a fixing heater as described in any one of claims 1 to 8, wherein the fixing protection circuit is connected to the fixing heater.

10. A fixing detection method, characterized in that: Applied to the fixing protection circuit according to any one of claims 1 to 8, the method comprises: detecting a first signal at an output terminal of the comparator via a second pin; The first pin is configured from an input interface to an output interface or after being delayed by a delay circuit, the second signal at the output end of the comparator is detected again through the second pin; If the first signal and the second signal are different, determining that the comparator is normal; If the first signal is identical to the second signal, it is determined that the comparator is abnormal.

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