Over-temperature protection circuit and over-temperature protection method

Abstract

The invention relates to an over-temperature protection circuit and an over-temperature protection method, and a main control circuit which is used for generating a heating control instruction according to the definition of a display module. The power management circuit is used for generating a first driving signal corresponding to the heating control instruction according to the heating control instruction and transmitting the first driving signal to the first input end of the logic circuit; the hysteresis circuit is used for generating a second driving signal according to the temperature change trend of the heating module and a preset temperature threshold value corresponding to the temperature change trend, and transmitting the second driving signal to the second input end of the logic circuit; the logic circuit is used for generating a heating control signal according to the first driving signal and the second driving signal so as to turn on or turn off the heating module; dynamic regulation and control of the on-off state of the heating module are achieved, the risk that the heating module is overheated and damaged due to the fact that a fixed heating mode is adopted is effectively avoided, and the safety and reliability of the heating process of the heating module are improved.

Description

Technical Field

[0001] The present application relates to the technical field of protection circuits, and in particular to an over-temperature protection circuit and an over-temperature protection method. Background Art

[0002] With the continuous progress and development of modern electronic devices, the requirements for display module performance are getting higher and higher. Especially in low temperature environments, in order to ensure the clarity and response speed of the display module, the module often needs to be heated. However, traditional heating control methods often use fixed heating modes, which can easily cause overheating and damage to the heating module, affecting the overall performance and life of the device.

[0003] With regard to the risk of overheating and damage of the heating module in the prior art, no effective solution has been proposed so far. Summary of the invention

[0004] Based on this, it is necessary to provide an over-temperature protection circuit and an over-temperature protection method to address the above technical problems.

[0005] In a first aspect, the present application provides an over-temperature protection circuit, the over-temperature protection circuit comprising a main control circuit, a power management circuit, a hysteresis circuit and a logic circuit;

[0006] The control end of the main control circuit is connected to the control end of the power management circuit; the main control circuit is used to generate a heating control instruction according to the definition of the display module;

[0007] The output end of the power management circuit is connected to the first input end of the logic circuit; the power management circuit is used to generate a first drive signal corresponding to the heating control instruction according to the heating control instruction, and transmit the first drive signal to the first input end of the logic circuit;

[0008] The output end of the hysteresis circuit is connected to the second input end of the logic circuit; the hysteresis circuit is used to generate a second drive signal according to the temperature change trend of the heating module and the preset temperature threshold corresponding to the temperature change trend, and transmit the second drive signal to the second input end of the logic circuit;

[0009] The output end of the logic circuit is used to be connected to the enable end of the heating module; the logic circuit is used to generate a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module.

[0010] In one embodiment, the output end of the hysteresis circuit is connected to the monitoring end of the main control circuit; the hysteresis circuit is also used to feed back the second drive signal to the monitoring end of the main control circuit, so that the main control circuit updates the heating control instruction according to the second drive signal.

[0011] In one embodiment, the hysteresis circuit includes a thermistor and a non-inverting Schmitt comparator circuit;

[0012] The first external power supply is connected to the in-phase input terminal of the in-phase Schmitt comparator circuit through the thermistor; the second external power supply is connected to the inverting input terminal of the in-phase Schmitt comparator circuit; the output terminal of the in-phase Schmitt comparator circuit is respectively connected to the second input terminal of the logic circuit and the monitoring terminal of the main control circuit;

[0013] The thermistor is arranged within a preset space range of the heating module.

[0014] In one embodiment, the in-phase Schmitt comparator circuit includes: a hysteresis comparator, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor;

[0015] One end of the first resistor is connected to the first external power supply, and the other end of the first resistor is grounded through the thermistor and the second resistor in sequence;

[0016] One end of the third resistor is connected to the connection point of the first resistor and the thermistor, and the other end of the third resistor is connected to the non-inverting input end of the hysteresis comparator;

[0017] One end of the fourth resistor is connected to the second external power supply, and the other end of the fourth resistor is connected to the inverting input end of the hysteresis comparator;

[0018] One end of the fifth resistor is connected to a connection point between the fourth resistor and the inverting input terminal of the hysteresis comparator, and the other end of the fifth resistor is grounded;

[0019] One end of the sixth resistor is connected to a connection point between the third resistor and the non-inverting input end of the hysteresis comparator, and the other end of the sixth resistor is connected to an output end of the hysteresis comparator;

[0020] One end of the seventh resistor is connected to a third external power supply, and the other end of the seventh resistor is connected to a connection point between the sixth resistor and the output end of the hysteresis comparator;

[0021] The output end of the hysteresis comparator is connected to the second input end of the logic circuit and the monitoring end of the main control circuit respectively.

[0022] In one embodiment, the main control circuit includes a main controller and a data conversion circuit;

[0023] The control end of the main controller is connected to the control end of the power management circuit via the data conversion circuit;

[0024] The output end of the hysteresis circuit is connected to the monitoring end of the main controller via the data conversion circuit.

[0025] In one embodiment, the logic circuit includes an AND gate circuit;

[0026] The first input end of the AND gate circuit is connected to the output end of the power management circuit, the second input end of the AND gate circuit is connected to the output end of the hysteresis circuit, and the output end of the AND gate circuit is used to connect to the enable end of the heating module.

[0027] In a second aspect, the present application further provides an over-temperature protection method, which is applied to the over-temperature protection circuit described in any one of the embodiments of the first aspect above, and the method includes:

[0028] The main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction;

[0029] The hysteresis circuit generates a second driving signal according to the temperature change trend of the heating module and a preset temperature threshold corresponding to the temperature change trend;

[0030] The logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module.

[0031] In one embodiment, the first driving signal includes a first on signal and a first off signal; the heating control instruction includes a heating on instruction and a heating off instruction; the main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction, including:

[0032] Real-time detection of the clarity of the display module by the main control circuit;

[0033] If the definition of the display module is less than a preset definition threshold, a heating start instruction is generated to drive the power management circuit to generate a first start signal corresponding to the heating start instruction;

[0034] If the definition of the display module is greater than or equal to a preset definition threshold, a heating shutdown instruction is generated to drive the power management circuit to generate a first shutdown signal corresponding to the heating shutdown instruction.

[0035] In one embodiment, the second driving signal includes a second on signal and a second off signal; the hysteresis circuit generates the second driving signal according to the temperature change trend of the heating module, including:

[0036] In the case where the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to the first temperature threshold, a second turn-on signal is generated; if the temperature of the heating module is greater than the first temperature threshold, a second turn-off signal is generated;

[0037] In the case where the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to a second temperature threshold, a second shutdown signal is generated; if the temperature of the heating module is less than the second temperature threshold, a second start signal is generated;

[0038] The first temperature threshold is greater than the second temperature threshold, and the first temperature threshold is less than the maximum limit temperature of the heating module.

[0039] In one embodiment, the hysteresis circuit includes a thermistor and a common-phase Schmidt comparator circuit; when the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to a first temperature threshold, a second turn-on signal is generated; if the temperature of the heating module is greater than the first temperature threshold, a second turn-off signal is generated, including:

[0040] When the temperature change trend of the heating module is a temperature rising trend, the resistance value of the thermistor decreases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage falling trend;

[0041] In the case where the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage decreasing trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is greater than or equal to a first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second start signal;

[0042] If the voltage at the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than the first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal.

[0043] In one embodiment, when the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to a second temperature threshold, a second shutdown signal is generated; if the temperature of the heating module is less than the second temperature threshold, a second start signal is generated, including:

[0044] When the temperature change trend of the heating module is a temperature decreasing trend, the resistance value of the thermistor increases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increasing trend;

[0045] In the case where the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage rising trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than or equal to a second voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal;

[0046] If the voltage at the in-phase input terminal of the in-phase Schmitt comparator circuit is greater than a second voltage threshold, the output terminal of the in-phase Schmitt comparator circuit outputs a second start signal;

[0047] The second voltage threshold is greater than the first voltage threshold.

[0048] In one embodiment, the second driving signal includes a second on signal and a second off signal; the method further includes:

[0049] The main control circuit monitors the second driving signal output from the output end of the hysteresis circuit in real time at a preset time period;

[0050] When the heating control instruction is a heating on instruction, if the output end of the hysteresis circuit outputs a second shutdown signal, the heating on instruction is updated to a heating off instruction to drive the power management circuit to generate a first shutdown signal corresponding to the heating off instruction.

[0051] In one embodiment, the first driving signal includes a first on signal and a first off signal; the second driving signal includes a second on signal and a second off signal; the heating control signal includes a heating on signal and a heating off signal; the logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module, including:

[0052] Generate a heating start signal according to the first start signal and the second start signal to turn on the heating module;

[0053] or,

[0054] A heating shutoff signal is generated according to the first shutoff signal and / or the second shutoff signal to shut off the heating module.

[0055] The above-mentioned over-temperature protection circuit and over-temperature protection method, the over-temperature protection circuit includes a main control circuit, a power management circuit, a hysteresis circuit and a logic circuit. The main control circuit can dynamically adjust the heating control instruction according to the clarity of the display module, and then control the power management circuit to generate a corresponding first drive signal; the hysteresis circuit can dynamically adjust the second drive signal according to the temperature change trend of the heating module and the corresponding preset temperature threshold; further, the logic circuit receives two drive signals from the power management circuit and the hysteresis circuit, and can accurately generate the corresponding heating control signal through logical judgment to accurately turn on or off the heating module; based on this, the dynamic regulation of the on and off state of the heating module is realized, which effectively avoids the risk of overheating and damage of the heating module due to the use of a fixed heating mode, and improves the safety and reliability of the heating process of the heating module. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 is a schematic structural diagram of an over-temperature protection circuit in one embodiment;

[0058] Figure 2 is a schematic structural diagram of an over-temperature protection circuit in another embodiment;

[0059] Figure 3 A schematic diagram of the relationship between the voltage at the non-inverting input terminal and the output terminal of a non-inverting Schmitt comparator circuit in one embodiment;

[0060] Figure 4 is a schematic structural diagram of a hysteresis circuit in one embodiment;

[0061] Figure 5 is a schematic structural diagram of an over-temperature protection circuit in another embodiment;

[0062] Figure 6 Schematic diagram of a flow chart of an over-temperature protection method in an embodiment.

[0063] Description of Reference Numerals

[0064] 100, main control circuit; 200, power management circuit; 300, hysteresis circuit; 400, logic circuit; 110, main controller; 120, data conversion circuit. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0067] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0068] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0069] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least part of an element” means part or all of an element.

[0070] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0071] With the continuous progress and development of modern electronic equipment, more and more camera products have integrated heating functions to adapt to various environmental conditions, but the heating function must meet strict safety standards; traditional heating control methods often use fixed heating modes, which can easily cause overheating and damage to the heating module, affecting the overall performance and life of the device. To this end, this embodiment provides an over-temperature protection circuit to prevent equipment failure or safety hazards caused by overheating of the heating module.

[0072] In one embodiment, Figure 1 As shown, Figure 1 Schematic diagram of the structure of an over-temperature protection circuit in an embodiment; the over-temperature protection circuit includes a main control circuit 100, a power management circuit 200, a hysteresis circuit 300 and a logic circuit 400;

[0073] The control end of the main control circuit 100 is connected to the control end of the power management circuit 200; the main control circuit 100 is used to generate a heating control instruction according to the definition of the display module;

[0074] The output end of the power management circuit 200 is connected to the first input end of the logic circuit 400; the power management circuit 200 is used to generate a first drive signal EN1 corresponding to the heating control instruction according to the heating control instruction, and transmit the first drive signal EN1 to the first input end of the logic circuit 400;

[0075] The output end of the hysteresis circuit 300 is connected to the second input end of the logic circuit 400; the hysteresis circuit 300 is used to generate a second drive signal EN2 according to the temperature change trend of the heating module and the preset temperature threshold corresponding to the temperature change trend, and transmit the second drive signal EN2 to the second input end of the logic circuit 400;

[0076] The output end of the logic circuit 400 is used to connect to the enable end of the heating module (not shown in the figure); the logic circuit 400 is used to generate a heating control signal EN3 according to the first drive signal EN1 and the second drive signal EN2 to turn on or off the heating module.

[0077] Among them, the main control circuit 100 may include but is not limited to a main controller; wherein, the main controller may include but is not limited to an electronic control unit (ECU); the main control circuit 100 is used to detect the clarity of the display module in real time, and generate corresponding heating control instructions according to the clarity of the display module and transmit them to the power management circuit 200; wherein, the clarity of the display module can be determined by an image processing method in the prior art, which is not specifically limited here; the display module may include but is not limited to a lens.

[0078] Among them, the power management circuit 200 may, but is not limited to, include a power management integrated circuit (Power Management Integrated Circuit, PMIC); the power management circuit 200 is used to convert the heating control instruction into a corresponding first drive signal EN1; the first drive signal EN1 is a logic level signal; the first drive signal EN1 includes a first turn-on signal and a first turn-off signal; wherein the first turn-on signal is a high level signal; and the first turn-off signal is a low level signal.

[0079] In an exemplary embodiment, the definition of the display module is detected in real time by the main control circuit 100; if the definition of the display module is less than the preset definition threshold, a heating on instruction is generated to drive the power management circuit 200 to generate a first on signal corresponding to the heating on instruction, i.e., a high level signal; if the definition of the display module is greater than or equal to the preset definition threshold, a heating off instruction is generated to drive the power management circuit 200 to generate a first off signal corresponding to the heating off instruction, i.e., a low level signal. It should be noted that the preset definition threshold needs to be set according to the actual application requirements of the display module and is not specifically limited here.

[0080] Among them, the hysteresis circuit 300 is used to generate a second driving signal EN2 according to the temperature change trend of the heating module and the preset temperature threshold corresponding to the temperature change trend; wherein the heating module at least includes a heating wire, which is used to prevent frost, ice or condensation on the surface of the display module, ensuring that the display module can still maintain good clarity under various severe weather conditions; the temperature change trend of the heating module includes a temperature decreasing trend and a temperature increasing trend; the temperature decreasing trend refers to the process in which the temperature gradually decreases from a higher value to a lower value within a certain time range; the temperature increasing trend refers to the process in which the temperature gradually increases from a lower value to a higher value within a certain time range.

[0081] Among them, the preset temperature threshold includes a first temperature threshold and a second temperature threshold; the first temperature threshold is greater than the second temperature threshold, and the first temperature threshold is less than the maximum limit temperature of the heating module to ensure the safety of the heating module; wherein the maximum limit temperature of the heating module refers to the highest temperature that the heating module can reach under normal working conditions.

[0082] It should be noted that the temperature rising trend corresponds to the first temperature threshold, and the temperature falling trend corresponds to the second temperature threshold; the first temperature threshold and the second temperature threshold need to be set according to the actual performance of the hysteresis circuit 300, and no specific limitation is made here.

[0083] The second driving signal EN2 is a logic level signal; the second driving signal EN2 includes a second on signal and a second off signal; the second on signal is a high level signal; and the second off signal is a low level signal.

[0084] In an exemplary embodiment, when the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to the first temperature threshold, the hysteresis circuit 300 generates a second start signal; if the temperature of the heating module is greater than the first temperature threshold, the hysteresis circuit 300 generates a second shutdown signal. When the temperature change trend of the heating module is a temperature falling trend, if the temperature of the heating module is greater than or equal to the second temperature threshold, the hysteresis circuit 300 generates a second shutdown signal; if the temperature of the heating module is less than the second temperature threshold, the hysteresis circuit 300 generates a second start signal. It should be noted that the output end of the hysteresis circuit 300 outputs the second start signal by default.

[0085] It can be understood that based on the hysteresis circuit 300, the frequent switching problem caused by the continuous fluctuation of the temperature of the heating module near the first temperature threshold or the second temperature threshold can be effectively prevented, thereby effectively improving the stability and anti-interference ability of the over-temperature protection circuit.

[0086] The logic circuit 400 is used to perform logic judgment on the first driving signal EN1 and the second driving signal EN2 to generate a corresponding heating control signal EN3 to turn on or off the heating module. The heating control signal EN3 is a logic level signal, and the heating control signal EN3 includes a heating on signal and a heating off signal; wherein the heating on signal is a high level signal; and the heating off signal is a low level signal.

[0087] In an exemplary embodiment, when the first drive signal EN1 is a first turn-on signal and the second drive signal EN2 is a second turn-on signal, the logic circuit 400 generates a heating turn-on signal, i.e., a high-level signal, based on the first turn-on signal, i.e., a high-level signal, and the second turn-on signal, i.e., a high-level signal, to turn on the heating module; when the first drive signal EN1 is a first turn-off signal, and / or the second drive signal EN2 is a second turn-off signal, the logic circuit 400 generates a heating turn-off signal, i.e., a low-level signal, based on the first turn-off signal, i.e., a low-level signal, and / or the second turn-off signal, i.e., a low-level signal, to turn off the heating module.

[0088] For example, in practical applications, the example of turning on the heating module when the display module surface is frosted is used for explanation. When the main control circuit 100 detects that the display module surface is frosted and the clarity of the display module is less than the preset clarity threshold, the main control circuit 100 generates a heating start instruction to drive the power management circuit 200 to generate a first start signal corresponding to the heating start instruction, that is, a high-level signal; at this time, since the output end of the hysteresis circuit 300 outputs the second start signal, that is, a high-level signal by default, the logic circuit 400 generates a heating start instruction according to the first start signal and the second start signal to turn on the heating module; during the heating process of the heating module, The temperature change trend of the heating module is a rising trend, and the temperature of the heating module is always less than or equal to the first temperature threshold. At this time, the hysteresis circuit 300 keeps generating the second turn-on signal until the main control circuit 100 detects that the clarity of the display module is greater than or equal to the preset clarity threshold. The main control circuit 100 generates a heating shutdown instruction to drive the power management circuit 200 to generate a first shutdown signal, i.e., a low-level signal, corresponding to the heating shutdown instruction; the logic circuit 400 generates a heating shutdown instruction according to the first shutdown signal, i.e., a low-level signal, and the second turn-on signal, i.e., a high-level signal, to turn off the heating module, thereby realizing the heating and defrosting function of the display module.

[0089] In this embodiment, the main control circuit 100 can dynamically adjust the heating control instruction according to the clarity of the display module, thereby controlling the power management circuit 200 to generate the corresponding first drive signal EN1; the hysteresis circuit 300 can dynamically adjust the second drive signal EN2 according to the temperature change trend of the heating module and the corresponding preset temperature threshold; further, the logic circuit 400 receives two drive signals from the power management circuit 200 and the hysteresis circuit 300, and can accurately generate the corresponding heating control signal EN3 through logical judgment to accurately turn on or off the heating module; based on this, the dynamic regulation of the on-off state of the heating module is realized, effectively avoiding the risk of overheating and damage to the heating module due to the use of a fixed heating mode, and improving the safety and reliability of the heating process of the heating module. In addition, based on the hysteresis circuit 300, the frequent switching problem caused by the temperature fluctuation of the heating module near the threshold can be effectively prevented, and the stability and anti-interference ability of the over-temperature protection circuit are effectively improved.

[0090] In one embodiment, Figure 2 As shown, Figure 2 It is a structural diagram of an over-temperature protection circuit in another embodiment; the output end of the hysteresis circuit 300 is connected to the monitoring end of the main control circuit 100; the hysteresis circuit 300 is also used to feed back the second drive signal EN2 to the monitoring end of the main control circuit 100, so that the main control circuit 100 updates the heating control instruction according to the second drive signal EN2.

[0091] It can be understood that by connecting the output end of the hysteresis circuit 300 to the monitoring end of the main control circuit 100, the second drive signal EN2 can be monitored in real time through the main control circuit 100, so that when the main control circuit 100 fails to detect the clarity of the display module in time, the heating control instruction can be updated in time according to the second drive signal EN2.

[0092] In an exemplary embodiment, the main control circuit 100 monitors the second driving signal EN2 outputted from the output terminal of the hysteresis circuit 300 in real time at a preset time period; when the heating control instruction is a heating on instruction, if the output terminal of the hysteresis circuit 300 outputs a second off signal, the heating on instruction is updated to a heating off instruction to drive the power management circuit 200 to generate a first off signal corresponding to the heating off instruction. It should be noted that the preset time period is less than the cooling time of the heating module to ensure that the heating control instruction is updated before the output terminal of the hysteresis circuit 300 switches from the second off signal to the second on signal.

[0093] By way of example, in practical applications, the example of turning on the heating module during the heating process is used for explanation; after turning on the heating module, the temperature change trend of the heating module is a temperature rising trend, and the temperature of the heating module is less than or equal to the first temperature threshold, and the hysteresis circuit 300 generates a second turn-on signal; during the heating process, if the main control circuit 100 cannot timely and accurately detect the clarity of the display module, the main control circuit 100 detects in real time the second drive signal EN2 output from the output end of the hysteresis circuit 300, and can timely update the heating control instruction to turn off the display module; specifically, it is determined whether the second drive signal EN2 is a second turn-off signal. If the output end of the hysteresis circuit 300 outputs the second turn-off signal, the heating turn-on instruction is updated to a heating turn-off instruction to drive the power management circuit 200 to generate a first turn-off signal corresponding to the heating turn-off instruction; and then the logic circuit 400 generates a heating turn-off instruction according to the first turn-off signal and the second turn-off signal to turn off the heating module.

[0094] It can be understood that if the heating start instruction is not updated to the heating shutdown instruction in time when the second shutdown signal is output at the output end of the hysteresis circuit 300, the hysteresis circuit 300 will dynamically adjust the second drive signal EN2 according to the temperature change trend and the corresponding preset temperature threshold, so that the turning on and off of the heating module enters a cyclic state.

[0095] It should be noted that, based on the first temperature threshold and the second temperature threshold, there is no risk of overheating damage even if the heating module is turned on and off in a cycle. In this embodiment, by outputting a second shutoff signal at the output end of the hysteresis circuit 300, the heating on instruction is updated to the heating off instruction, which can ensure that the heating module remains in the off state to meet the user's heating demand for the display module.

[0096] In this embodiment, by feeding back the second drive signal EN2 to the monitoring end of the main control circuit 100, even if the main control circuit 100 cannot detect the change in clarity of the display module in time during the heating process of the heating module, the heating control instruction can be adjusted in time through the second drive signal EN2 to ensure the stable operation of the over-temperature protection circuit.

[0097] In one embodiment, the hysteresis circuit 300 includes a thermistor and a non-inverting Schmitt comparator circuit;

[0098] The first external power source is connected to the in-phase input terminal of the in-phase Schmitt comparator circuit through the thermistor; the second external power source is connected to the inverting input terminal of the in-phase Schmitt comparator circuit; the output terminal of the in-phase Schmitt comparator circuit is respectively connected to the second input terminal of the logic circuit 400 and the monitoring terminal of the main control circuit 100;

[0099] The thermistor is arranged within a preset space range of the heating module.

[0100] The first external power source is a DC power source, and is used to provide an operating voltage for the thermistor and the in-phase Schmidt comparator circuit. It should be noted that the specific voltage value of the first external power source needs to be set according to the actual performance of the in-phase Schmidt comparator circuit, and is not specifically limited here.

[0101] The resistance of the thermistor changes with temperature; the thermistor is used to reflect the temperature change of the heating module in the in-phase Schmidt comparator circuit to generate an accurate second drive signal. The thermistor is set within the preset spatial range of the heating module to ensure that the thermistor is in direct contact with or close to the heating module so as to timely and accurately sense the temperature change of the heating module; the preset spatial range needs to be set according to the actual physical position of the heating module and is not specifically limited here.

[0102] The in-phase Schmitt comparator circuit has a hysteresis characteristic, which is used to prevent the voltage at the in-phase input terminal of the in-phase Schmitt comparator circuit from fluctuating slightly near the threshold, resulting in frequent switching of the second drive signal EN2 at the output terminal.

[0103] Wherein, the second external power supply is a DC power supply; the second external power supply is used to provide a fixed reference voltage for the inverting input terminal of the in-phase Schmitt comparator circuit. The output terminal of the in-phase Schmitt comparator circuit will output a corresponding high-level signal or a low-level signal according to the voltage relationship between the in-phase input terminal and the inverting input terminal. It should be noted that the specific voltage value of the second external power supply needs to be set according to the actual performance of the in-phase Schmitt comparator circuit, and is not specifically limited here.

[0104] In an exemplary embodiment, see Figure 3 , the voltage at the non-inverting input terminal of the non-inverting Schmidt comparator circuit is recorded as Vin; based on Ohm's law, when the temperature change trend of the heating module is a temperature rising trend, the resistance value of the thermistor decreases, and the voltage change trend of the non-inverting input terminal of the non-inverting Schmidt comparator circuit is a voltage falling trend; when the voltage change trend of the non-inverting input terminal of the non-inverting Schmidt comparator circuit is a voltage falling trend, if the voltage Vin at the non-inverting input terminal of the non-inverting Schmidt comparator circuit is greater than or equal to the first voltage threshold V TL , the output terminal of the in-phase Schmitt comparator circuit outputs a second start signal, i.e., a high level signal; if the voltage Vin at the in-phase input terminal of the in-phase Schmitt comparator circuit is less than the first voltage threshold V TL , the output end of the in-phase Schmitt comparator circuit outputs a second shutdown signal, that is, a low level signal.

[0105] Based on Ohm's law, when the temperature change trend of the heating module is a temperature decreasing trend, the resistance value of the thermistor increases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increasing trend; when the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increasing trend, if the voltage Vin of the in-phase input terminal of the in-phase Schmidt comparator circuit is less than or equal to the second voltage threshold V TH , the output terminal of the in-phase Schmitt comparator circuit outputs a second shutdown signal, i.e., a low level signal; if the voltage Vin at the in-phase input terminal of the in-phase Schmitt comparator circuit is greater than the second voltage threshold V TH , then the output terminal of the in-phase Schmitt comparator circuit outputs a second start signal, i.e., a high level signal; wherein the second voltage threshold V TH Greater than the first voltage threshold V TL It should be noted that the second voltage threshold V TH And the first voltage threshold V TL , which is determined by the performance of the in-phase Schmitt comparator circuit and is not specifically limited here.

[0106] In this embodiment, based on the hysteresis characteristics of the in-phase Schmitt comparator circuit, by setting the first voltage threshold V TL And the second voltage threshold V TH , which can effectively prevent the voltage Vin at the non-inverting input terminal of the non-inverting Schmitt comparator circuit from exceeding the first voltage threshold V TL Or the second voltage threshold V TH At the same time, based on the thermistor, the temperature change of the heating module can be timely and accurately sensed, and the temperature change of the heating module can be reflected in the in-phase Schmitt comparator circuit to generate an accurate second drive signal.

[0107] In one embodiment, Figure 4 As shown, Figure 4 Schematic diagram of the structure of a hysteresis circuit in an embodiment; the in-phase Schmidt comparator circuit includes: a hysteresis comparator U1, a first resistor R6, a second resistor R7, a third resistor R1, a fourth resistor R4, a fifth resistor R5, a sixth resistor R2 and a seventh resistor R3;

[0108] One end of the first resistor R6 is connected to the first external power supply VDD1, and the other end of the first resistor R6 is connected to the ground through the thermistor RNTC and the second resistor R7 in sequence;

[0109] One end of the third resistor R1 is connected to the connection point of the first resistor R6 and the thermistor RNTC, and the other end of the third resistor R1 is connected to the non-inverting input terminal of the hysteresis comparator U1;

[0110] One end of the fourth resistor R4 is connected to the second external power supply VDD2, and the other end of the fourth resistor R4 is connected to the inverting input end of the hysteresis comparator U1;

[0111] One end of the fifth resistor R5 is connected to a connection point of the fourth resistor R4 and the inverting input terminal of the hysteresis comparator U1, and the other end of the fifth resistor R5 is grounded;

[0112] One end of the sixth resistor R2 is connected to a connection point of the third resistor R1 and the non-inverting input end of the hysteresis comparator U1, and the other end of the sixth resistor R2 is connected to an output end of the hysteresis comparator U1;

[0113] One end of the seventh resistor R3 is connected to the third external power supply VCC, and the other end of the seventh resistor R3 is connected to the connection point of the sixth resistor R2 and the output end of the hysteresis comparator U1;

[0114] The output terminal of the hysteresis comparator U1 is connected to the second input terminal of the logic circuit 400 and the monitoring terminal of the main control circuit 100 respectively.

[0115] The first external power source VDD1 is grounded via the first resistor R6, the thermistor RNTC and the second resistor R7, and is used to provide a voltage V+ to the non-inverting input terminal of the hysteresis comparator U1, V+≠Vin, Vin is the voltage value at the connection point of the thermistor, the first resistor R6 and the third resistor R1, and the specific calculation formula of Vin is as follows:

[0116]

[0117] According to the above formula, when the resistance of the thermistor RNTC decreases, the voltage value of Vin decreases as the resistance of the thermistor RNTC decreases, and the voltage V+ at the non-inverting input terminal of the hysteresis comparator U1 decreases as the voltage value of Vin decreases; when the resistance of the thermistor RNTC increases, the voltage value of Vin increases as the resistance of the thermistor RNTC increases, and the voltage V+ at the non-inverting input terminal of the hysteresis comparator U1 increases as the voltage value of Vin increases.

[0118] The fourth resistor R4 and the fifth resistor R5 are both voltage-dividing resistors, which are used to form a voltage-dividing circuit to divide the second external power source VDD2 so as to provide a reference voltage Vref to the inverting input terminal of the hysteresis comparator U1.

[0119] The third resistor R1 , the sixth resistor R2 and the seventh resistor R3 are used to implement the hysteresis function of the hysteresis comparator.

[0120] The third external power source VCC is a DC power source, which provides a pull-up power source for the seventh resistor R3.

[0121] It should be noted that the hysteresis comparator U1 has a first voltage threshold V TL And the second voltage threshold V TH ; Wherein, the first voltage threshold V TL , is the voltage value of Vin when the voltage value V+ of the non-inverting input terminal of the hysteresis comparator U1 is just greater than the voltage value Vref of the inverting input terminal of the hysteresis comparator U1; the second voltage threshold V TH , is the voltage value of Vin when the voltage value V+ at the non-inverting input terminal of the hysteresis comparator U1 is just less than the voltage value Vref at the inverting input terminal of the hysteresis comparator U1.

[0122] Based on the first voltage threshold V TL And the second voltage threshold V TH , when Vin continues to increase until it is greater than the second voltage threshold V TH When Vin decreases continuously until it is less than the first voltage threshold V TL When the hysteresis comparator U1 outputs a low level signal, the first voltage threshold V TL is less than the second voltage threshold V TH Based on this, the hysteresis function of the hysteresis comparator U1 can be realized.

[0123] It should be noted that the corresponding resistance values ​​of the first resistor R6, the second resistor R7, the third resistor R1, the fourth resistor R4, the fifth resistor R5, the sixth resistor R2 and the seventh resistor R3 need to be set according to the actual requirements of the in-phase Schmidt comparator circuit, and are not specifically limited here. The specific voltage values ​​corresponding to the first external power supply VDD1, the second external power supply VDD2 and the third external power supply VCC need to be set according to the actual performance of the in-phase Schmidt comparator circuit, and are not specifically limited here.

[0124] In this embodiment, based on the hysteresis comparator U1 and the thermistor RNTC, the temperature change of the heating module can be accurately reflected in the in-phase Schmidt comparator circuit, which lays a foundation for realizing the dynamic adjustment of the second driving circuit EN2.

[0125] In one embodiment, Figure 5 As shown, Figure 5 It is a structural diagram of an over-temperature protection circuit in another embodiment; the main control circuit 100 includes a main controller 110 and a data conversion circuit 120;

[0126] The control end of the main controller 110 is connected to the control end of the power management circuit 200 via the data conversion circuit 120;

[0127] The output terminal of the hysteresis circuit 300 is connected to the monitoring terminal of the main controller 110 via the data conversion circuit 120 .

[0128] Among them, the main controller 110 may include but is not limited to an ECU; the data conversion circuit 120 may include but is not limited to a serializer and a deserializer; the power management circuit 200 may include but is not limited to a PMIC. The main controller 110 is used to generate a heating control instruction according to the clarity of the display module and transmit it to the data conversion circuit 120; the data conversion circuit 120 is used to convert the heating control instruction into a data format supported by the power management circuit 200; and is also used to convert the second drive signal output from the output end of the hysteresis circuit 300 into a data format supported by the main controller 110. It should be noted that the communication method between the main controller 110 and the data conversion circuit 120 may include but is not limited to a serial communication protocol (Inter-Integrated Circuit, IIC), which is not specifically limited here.

[0129] It should be noted that since the main controller 110 cannot communicate directly with the power management circuit 200, the heating control instructions generated by the main controller 110 need to be encoded and packaged through the data conversion circuit 120 and then transmitted to the power management circuit 200 to achieve communication between the main controller 110 and the power management circuit 200; similarly, the hysteresis circuit 300 cannot communicate directly with the main controller 110, and the second drive signal needs to be processed by the data conversion circuit 120 and then fed back to the main controller 110 to achieve real-time monitoring of the second drive signal.

[0130] In this embodiment, based on the data conversion circuit 120, data communication between the main controller 110 and the power management circuit 200 and the hysteresis circuit 300 can be achieved, which lays a foundation for achieving precise control of the heating module.

[0131] In one embodiment, the logic circuit 400 includes an AND gate circuit;

[0132] The first input terminal of the AND gate circuit is connected to the output terminal of the power management circuit 200 , the second input terminal of the AND gate circuit is connected to the output terminal of the hysteresis circuit 300 , and the output terminal of the AND gate circuit is used to connect to the enable terminal of the heating module.

[0133] Exemplarily, based on the AND gate circuit, when the output end of the power management circuit 200 outputs a first turn-on signal and the output end of the hysteresis circuit 300 outputs a second turn-on signal, a heating turn-on signal can be generated to turn on the heating module; when the output end of the power management circuit 200 outputs a first turn-off signal and / or the output end of the hysteresis circuit 300 outputs a second turn-off signal, a heating turn-off signal can be generated to turn off the heating module.

[0134] In this embodiment, based on the AND gate circuit, by performing logic judgment on the first driving signal EN1 and the second driving signal EN2, the third driving signal EN3 can be accurately generated, so as to accurately control the start and stop of the heating module.

[0135] In a specific embodiment, Figure 4 For example, assuming that the third external power supply VCC = 3.3V, the first external power supply VDD1 = 1.8V, the second external power supply VDD2 = 3.3V, the third resistor R1 = 1.5kΩ, the sixth resistor R2 = 10kΩ, the seventh resistor R3 = 10kΩ, the fourth resistor R4 = 20kΩ, and the fifth resistor R5 = 10KΩ, then the reference voltage Vref corresponding to the inverting input terminal of the hysteresis comparator U1 = 1.1V, and further, the second voltage threshold V TH =1.265V, the first voltage threshold V TL=0.935V, the hysteresis voltage is 0.33V; when the voltage change trend of Vin is a voltage increase trend, and increases to greater than 1.265V, the second drive signal is a second turn-on signal, that is, a high-level signal; when the voltage change trend of Vin is a voltage decrease trend, and decreases to less than 0.935V, the second drive signal is a second turn-off signal, that is, a low-level signal.

[0136] In one embodiment, Figure 6 As shown, Figure 6 : is a flow chart of an over-temperature protection method in an embodiment; the over-temperature protection method in this embodiment is applied to the over-temperature protection circuit recorded in any one of the above embodiments, and the over-temperature protection method includes the following steps:

[0137] In step S601 , the main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction.

[0138] Among them, the heating control instruction includes a heating on instruction and a heating off instruction; the first drive signal includes a first on signal and a first off signal; the heating on instruction corresponds to the first on signal; and the heating off instruction corresponds to the first off signal.

[0139] Step S602: The hysteresis circuit generates a second driving signal according to the temperature change trend of the heating module and a preset temperature threshold corresponding to the temperature change trend.

[0140] The temperature change trend of the heating module includes a temperature drop trend and a temperature rise trend. The preset temperature threshold includes a first temperature threshold and a second temperature threshold; the first temperature threshold is greater than the second temperature threshold, and the first temperature threshold is less than the maximum temperature limit of the heating module to ensure the safety of the heating module. It should be noted that the temperature rise trend corresponds to the first temperature threshold, and the temperature drop trend corresponds to the second temperature threshold.

[0141] The second driving signal includes a second on signal and a second off signal.

[0142] In step S603 , the logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module.

[0143] Among them, the heating control signal includes a heating on signal and a heating off signal; the heating module can be turned on by the heating on signal; the heating module can be turned off by the heating off signal.

[0144] It should be noted that the specific structures of the main control circuit, the hysteresis circuit and the logic circuit have been recorded in the above embodiments and will not be repeated here.

[0145] It should be noted that the output end of the hysteresis circuit outputs the second start signal, ie, a high level signal, by default.

[0146] By way of example, in actual application, the case where the heating module needs to be turned on due to frost on the surface of the display module is used as an example for explanation. When frost on the surface of the display module is detected by the main control circuit and the clarity of the display module is less than a preset clarity threshold, the main control circuit generates a heating turn-on instruction to drive the power management circuit to generate a first turn-on signal, i.e., a high-level signal, corresponding to the heating turn-on instruction. Since the output end of the hysteresis circuit outputs a second turn-on signal, i.e., a high-level signal by default, the logic circuit generates a heating turn-on instruction according to the first turn-on signal and the second turn-on signal to turn on the heating module. During the heating process of the heating module, the temperature change trend of the heating module is a temperature rising trend, and the temperature of the heating module is always less than or equal to the first temperature threshold, and the hysteresis circuit keeps generating the second turn-on signal until the main control circuit detects that the clarity of the display module is greater than or equal to the preset clarity threshold, and the main control circuit generates a heating turn-off instruction to drive the power management circuit to generate a first turn-off signal corresponding to the heating turn-off instruction. The logic circuit generates a heating turn-off instruction according to the first turn-off signal and the second turn-on signal to turn off the heating module.

[0147] In this embodiment, the main control circuit can dynamically adjust the heating control instructions according to the clarity of the display module, and then control the power management circuit to generate a corresponding first drive signal; the hysteresis circuit can dynamically adjust the second drive signal according to the temperature change trend of the heating module and the corresponding preset temperature threshold; further, the logic circuit receives two drive signals from the power management circuit and the hysteresis circuit, and can accurately generate the corresponding heating control signal through logical judgment to accurately turn on or off the heating module, thereby realizing dynamic regulation of the on and off state of the heating module, effectively avoiding the risk of overheating and damage of the heating module due to the use of a fixed heating mode, and improving the safety and reliability of the heating process of the heating module.

[0148] In one embodiment, the first driving signal includes a first on signal and a first off signal; the heating control instruction includes a heating on instruction and a heating off instruction; the main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction, including the following steps:

[0149] Step 1: Detect the clarity of the display module in real time through the main control circuit.

[0150] Step 2: If the definition of the display module is less than a preset definition threshold, a heating start instruction is generated to drive the power management circuit to generate a first start signal corresponding to the heating start instruction.

[0151] Step 3: If the definition of the display module is greater than or equal to a preset definition threshold, a heating shutdown instruction is generated to drive the power management circuit to generate a first shutdown signal corresponding to the heating shutdown instruction.

[0152] Exemplarily, the clarity of the display module is detected in real time by the main control circuit, and it is determined whether the clarity of the display module is less than a preset clarity threshold; if the clarity of the display module is less than the preset clarity threshold, a heating turn-on instruction is generated to drive the power management circuit to generate a first turn-on signal corresponding to the heating turn-on instruction; if the clarity of the display module is greater than or equal to the preset clarity threshold, a heating turn-off instruction is generated to drive the power management circuit to generate a first turn-off signal corresponding to the heating turn-off instruction.

[0153] It should be noted that based on the logical judgment function of the logic circuit, during the heating process of the heating module, even if the main control circuit cannot normally monitor the second driving signal output by the output end of the hysteresis circuit, it can ensure that the heating module is shut down in time by detecting the clarity of the display module to avoid overheating and damage to the heating module.

[0154] In this embodiment, the main control circuit detects the clarity of the display module in real time, and can accurately turn on or off the heating module to ensure the reliability of the heating function of the heating module.

[0155] In one embodiment, the second driving signal includes a second on signal and a second off signal; the hysteresis circuit generates the second driving signal according to the temperature change trend of the heating module, including the following steps:

[0156] Step 1: when the temperature change trend of the heating module is an upward trend, if the temperature of the heating module is less than or equal to the first temperature threshold, a second start signal is generated; if the temperature of the heating module is greater than the first temperature threshold, a second shutdown signal is generated.

[0157] Step 2, when the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to the second temperature threshold, a second shutdown signal is generated; if the temperature of the heating module is less than the second temperature threshold, a second start signal is generated.

[0158] Among them, the first temperature threshold is greater than the second temperature threshold, and the first temperature threshold is less than the maximum limit temperature of the heating module; wherein the maximum limit temperature of the heating module refers to the highest temperature that the heating module can reach under normal working conditions.

[0159] Exemplarily, when the over-temperature protection circuit is normal, the heating module in the heating process is taken as an example for explanation. During the heating process of the heating module, the power management circuit generates a first start signal. At this time, the temperature change trend of the heating module is a rising temperature trend, and the temperature of the heating module is less than or equal to the first temperature threshold. The hysteresis circuit generates a second start signal; the clarity of the display module is detected in real time by the main control circuit. When the clarity of the display module is greater than or equal to the preset clarity threshold, the main control circuit controls the power management circuit to generate a first shutdown signal to shut down the heating module.

[0160] Furthermore, when the second drive signal is a second shutdown signal and the temperature change trend of the heating module is a temperature decrease trend, if the temperature of the heating module is greater than or equal to the second temperature threshold, the hysteresis circuit continues to generate a second shutdown signal; as the temperature of the heating module continues to decrease until the temperature of the heating module is less than the second temperature threshold, a second start signal is generated; it should be noted that when the hysteresis circuit generates the second start signal, it is necessary to determine whether to turn on or off the heating module based on the state of the first drive signal, and the specific process will not be repeated here.

[0161] In this embodiment, by setting two different temperature thresholds, namely the first temperature threshold and the second temperature threshold, it is possible to ensure more stable control of the working state of the heating module, reduce the impact of temperature fluctuations on the working state of the heating module, and improve the reliability and safety of the heating module.

[0162] In one embodiment, the hysteresis circuit includes a thermistor and a common-phase Schmidt comparator circuit; when the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to a first temperature threshold, a second turn-on signal is generated; if the temperature of the heating module is greater than the first temperature threshold, a second turn-off signal is generated, including the following steps:

[0163] Step 1: When the temperature change trend of the heating module is a temperature rising trend, the resistance value of the thermistor decreases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage falling trend.

[0164] It can be understood that the resistance of the thermistor will decrease as the temperature increases; when the temperature change trend of the heating module is an upward trend, the resistance of the thermistor decreases. Based on Ohm's law, the voltage at the non-inverting input terminal of the non-inverting Schmidt comparator circuit will decrease as the resistance of the thermistor decreases.

[0165] Step 2, when the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage decreasing trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is greater than or equal to the first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second start signal.

[0166] Step 3: If the voltage at the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than the first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal.

[0167] For example, see Figure 3 , take the heating module just turned on as an example to explain, after the heating module is turned on, the temperature change trend of the heating module is a temperature rising trend, the resistance value of the thermistor decreases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage falling trend. At this time, if the voltage Vin of the in-phase input terminal of the in-phase Schmidt comparator circuit is greater than or equal to the first voltage threshold V TL , the output terminal of the in-phase Schmitt comparator circuit outputs a second start signal, i.e., a high level signal. As the voltage Vin of the in-phase input terminal of the in-phase Schmitt comparator circuit decreases, if the voltage of the in-phase input terminal of the in-phase Schmitt comparator circuit decreases to less than the first voltage threshold V TL , the output end of the in-phase Schmitt comparator circuit outputs a second shutdown signal, that is, a low level signal.

[0168] Preferably, when the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to the second temperature threshold, a second shutdown signal is generated; if the temperature of the heating module is less than the second temperature threshold, a second start signal is generated, including the following steps:

[0169] Step 1: When the temperature change trend of the heating module is a temperature decreasing trend, the resistance value of the thermistor increases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increasing trend.

[0170] Step 2, when the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage rising trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than or equal to the second voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal.

[0171] Step 3: If the voltage at the non-inverting input terminal of the non-inverting Schmitt comparator circuit is greater than the second voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second start signal.

[0172] The second voltage threshold is greater than the first voltage threshold.

[0173] For example, see Figure 3, taking the heating module being turned off after being turned on for a period of time as an example, after the heating module is turned on for a period of time and then turned off, the temperature change trend of the heating module is a temperature decrease trend, the resistance value of the thermistor increases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increase trend. At this time, if the voltage Vin at the in-phase input terminal of the in-phase Schmidt comparator circuit is less than or equal to the second voltage threshold V TH , the output terminal of the in-phase Schmitt comparator circuit outputs a second shutdown signal, i.e., a low level signal. As the voltage Vin at the in-phase input terminal of the in-phase Schmitt comparator circuit increases, if the voltage Vin at the in-phase input terminal of the in-phase Schmitt comparator circuit increases to a value greater than the second voltage threshold V TH , the output end of the in-phase Schmitt comparator circuit outputs a second start-up signal, that is, a high-level signal.

[0174] In this embodiment, the temperature change of the heating module can be timely and accurately sensed through the thermistor, and the temperature change of the heating module can be reflected in the in-phase Schmidt comparator circuit to generate an accurate second driving signal.

[0175] In one embodiment, the second driving signal includes a second on signal and a second off signal; the over-temperature protection method further includes the following steps:

[0176] Step 1: monitor the second driving signal output from the output end of the hysteresis circuit in real time at a preset time period through the main control circuit.

[0177] The preset time period is shorter than the cooling time of the heating module to ensure that the heating control instruction is updated before the output of the hysteresis circuit switches from the second shutdown signal to the second startup signal.

[0178] Step 2, when the heating control instruction is a heating on instruction, if the output end of the hysteresis circuit outputs a second shutdown signal, the heating on instruction is updated to a heating off instruction to drive the power management circuit to generate a first shutdown signal corresponding to the heating off instruction.

[0179] It should be noted that in actual applications, the possible faults of the over-temperature protection circuit include a first fault, a second fault and a third fault; among them, the first fault refers to the main control circuit being unable to detect the clarity of the display module, but being able to normally monitor the second drive signal output from the output end of the hysteresis circuit; the second fault refers to the main control circuit being able to normally detect the clarity of the display module, but being unable to normally monitor the second drive signal output from the output end of the hysteresis circuit; the third fault refers to the main control circuit being unable to normally detect the clarity of the display module, and being unable to normally monitor the second drive signal output from the output end of the hysteresis circuit.

[0180] Exemplarily, taking the heating module in the heating process as an example, during the heating process, the power management circuit generates a first start signal, the temperature change trend of the heating module is a temperature rise trend, and the temperature of the heating module is less than or equal to the first temperature threshold, the hysteresis circuit generates a second start signal, and the heating module remains turned on; at this time, regardless of the first fault, the second fault or the third fault of the over-temperature protection circuit, the safety of the over-temperature protection circuit can be ensured, as follows:

[0181] If there is a first fault in the main control circuit, as the temperature of the heating module continues to rise, when the main control circuit detects that the output end of the hysteresis circuit outputs a second shutdown signal, the heating start instruction is updated to a heating shutdown instruction to control the power management circuit to generate a first shutdown signal, so as to shut down the heating module in time.

[0182] If the main control circuit has a second fault, as the temperature of the heating module continues to rise, the clarity of the display module can be detected in real time. When the clarity of the display module is greater than or equal to a preset clarity threshold, a first shutdown signal is generated to shut down the heating module in time.

[0183] If the main control circuit has a third fault, as the temperature of the heating module continues to rise until the temperature of the heating module is greater than the first temperature threshold, the output end of the hysteresis circuit outputs a second shutdown signal to shut down the heating module; after the heating module is shut down, the power management circuit keeps outputting the first start signal, and the temperature of the heating module begins to drop, that is, the temperature change trend of the heating module is a temperature drop trend, and the temperature of the heating module is greater than or equal to the second temperature threshold, and the output end of the hysteresis circuit outputs a second shutdown signal until the temperature of the heating module drops to less than the second temperature threshold, and the output end of the hysteresis circuit outputs a second start signal; since the power management circuit always keeps outputting the first start signal, the heating module is turned on again, and the cycle is repeated in sequence, that is, the heating module enters a cycle state of turning on and off; it should be noted that since the first temperature threshold is less than the maximum limit temperature of the heating module, there is no risk of overheating damage to the heating module when the heating module enters a cycle state of turning on and off.

[0184] In this embodiment, when different faults occur in the main control circuit, the normal operation of the heating module can be ensured through a variety of ways, thereby further improving the safety and reliability of the heating module.

[0185] In one embodiment, the first driving signal includes a first on signal and a first off signal; the second driving signal includes a second on signal and a second off signal; the heating control signal includes a heating on signal and a heating off signal; the logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module, including:

[0186] Generate a heating start signal according to the first start signal and the second start signal to start the heating module;

[0187] or,

[0188] A heating shutoff signal is generated according to the first shutoff signal and / or the second shutoff signal to shut off the heating module.

[0189] Exemplarily, when the first drive signal is a first turn-on signal and the second drive signal is a second turn-on signal, the logic circuit generates a heating turn-on signal, i.e., a high-level signal, according to the first turn-on signal, i.e., a high-level signal, and the second turn-on signal, i.e., a high-level signal, to turn on the heating module; when the first drive signal is a first turn-off signal, and / or the second drive signal is a second turn-off signal, the logic circuit generates a heating turn-off signal, i.e., a low-level signal, according to the first turn-off signal, i.e., a low-level signal, and / or the second turn-off signal, i.e., a low-level signal, to turn off the heating module.

[0190] In this embodiment, based on the logic circuit receiving two drive signals from the power management circuit and the hysteresis circuit, the corresponding heating control signal can be accurately generated through logical judgment to accurately turn on or off the heating module.

[0191] The above-mentioned over-temperature protection method can dynamically adjust the heating control instructions according to the clarity of the display module through the main control circuit, and then control the power management circuit to generate a corresponding first drive signal; through the hysteresis circuit according to the temperature change trend of the heating module and the corresponding preset temperature threshold, the second drive signal can be dynamically adjusted; further, the logic circuit receives two drive signals from the power management circuit and the hysteresis circuit, and can accurately generate the corresponding heating control signal through logical judgment to accurately turn on or off the heating module, based on which the dynamic regulation of the on and off state of the heating module is realized, effectively avoiding the risk of overheating and damage of the heating module due to the use of a fixed heating mode, and improving the safety and reliability of the heating process of the heating module.

[0192] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0193] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An over-temperature protection circuit, characterized in that: The over-temperature protection circuit includes a main control circuit, a power management circuit, a hysteresis circuit and a logic circuit; The control end of the main control circuit is connected to the control end of the power management circuit; the main control circuit is used to generate a heating control instruction according to the definition of the display module; The output terminal of the power management circuit is connected to the first input terminal of the logic circuit; The power management circuit is used to generate a first drive signal corresponding to the heating control instruction according to the heating control instruction, and transmit the first drive signal to the first input terminal of the logic circuit; The output end of the hysteresis circuit is connected to the second input end of the logic circuit; the hysteresis circuit is used to generate a second drive signal according to the temperature change trend of the heating module and the preset temperature threshold corresponding to the temperature change trend, and transmit the second drive signal to the second input end of the logic circuit; The output end of the logic circuit is used to be connected to the enable end of the heating module; the logic circuit is used to generate a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module.

2. The over-temperature protection circuit according to claim 1, characterized in that: The output end of the hysteresis circuit is connected to the monitoring end of the main control circuit; the hysteresis circuit is also used to feed back the second drive signal to the monitoring end of the main control circuit, so that the main control circuit updates the heating control instruction according to the second drive signal.

3. The over-temperature protection circuit according to claim 2, characterized in that: The hysteresis circuit includes a thermistor and a common-phase Schmidt comparator circuit; The first external power supply is connected to the in-phase input terminal of the in-phase Schmitt comparator circuit through the thermistor; the second external power supply is connected to the inverting input terminal of the in-phase Schmitt comparator circuit; the output terminal of the in-phase Schmitt comparator circuit is respectively connected to the second input terminal of the logic circuit and the monitoring terminal of the main control circuit; The thermistor is arranged within a preset space range of the heating module.

4. The over-temperature protection circuit according to claim 3, characterized in that: The in-phase Schmitt comparator circuit comprises: a hysteresis comparator, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; One end of the first resistor is connected to the first external power supply, and the other end of the first resistor is grounded through the thermistor and the second resistor in sequence; One end of the third resistor is connected to the connection point of the first resistor and the thermistor, and the other end of the third resistor is connected to the non-inverting input end of the hysteresis comparator; One end of the fourth resistor is connected to the second external power supply, and the other end of the fourth resistor is connected to the inverting input end of the hysteresis comparator; One end of the fifth resistor is connected to a connection point between the fourth resistor and the inverting input terminal of the hysteresis comparator, and the other end of the fifth resistor is grounded; One end of the sixth resistor is connected to a connection point between the third resistor and the non-inverting input end of the hysteresis comparator, and the other end of the sixth resistor is connected to an output end of the hysteresis comparator; One end of the seventh resistor is connected to a third external power supply, and the other end of the seventh resistor is connected to a connection point between the sixth resistor and the output end of the hysteresis comparator; The output end of the hysteresis comparator is connected to the second input end of the logic circuit and the monitoring end of the main control circuit respectively.

5. The over-temperature protection circuit according to claim 1, characterized in that: The main control circuit includes a main controller and a data conversion circuit; The control end of the main controller is connected to the control end of the power management circuit via the data conversion circuit; The output end of the hysteresis circuit is connected to the monitoring end of the main controller via the data conversion circuit.

6. The over-temperature protection circuit according to claim 1, characterized in that: The logic circuit includes an AND gate circuit; The first input end of the AND gate circuit is connected to the output end of the power management circuit, the second input end of the AND gate circuit is connected to the output end of the hysteresis circuit, and the output end of the AND gate circuit is used to connect to the enable end of the heating module.

7. An over-temperature protection method, characterized in that: The over-temperature protection circuit applied to any one of claims 1 to 6, the method comprising: The main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction; The hysteresis circuit generates a second driving signal according to the temperature change trend of the heating module and a preset temperature threshold corresponding to the temperature change trend; The logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module.

8. The method according to claim 7, characterized in that The first driving signal includes a first on signal and a first off signal; the heating control instruction includes a heating on instruction and a heating off instruction; the main control circuit generates a heating control instruction according to the definition of the display module to drive the power management circuit to generate a first driving signal corresponding to the heating control instruction, including: Real-time detection of the clarity of the display module by the main control circuit; If the definition of the display module is less than a preset definition threshold, a heating start instruction is generated to drive the power management circuit to generate a first start signal corresponding to the heating start instruction; If the definition of the display module is greater than or equal to a preset definition threshold, a heating shutdown instruction is generated to drive the power management circuit to generate a first shutdown signal corresponding to the heating shutdown instruction.

9. The method according to claim 7, characterized in that: The second driving signal includes a second on signal and a second off signal; The hysteresis circuit generates a second driving signal according to the temperature change trend of the heating module, including: In the case where the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to the first temperature threshold, a second turn-on signal is generated; if the temperature of the heating module is greater than the first temperature threshold, a second turn-off signal is generated; In the case where the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to a second temperature threshold, a second shutdown signal is generated; if the temperature of the heating module is less than the second temperature threshold, a second start signal is generated; The first temperature threshold is greater than the second temperature threshold, and the first temperature threshold is less than the maximum limit temperature of the heating module.

10. The method according to claim 9, characterized in that The hysteresis circuit includes a thermistor and an in-phase Schmidt comparator circuit; when the temperature change trend of the heating module is a temperature rising trend, if the temperature of the heating module is less than or equal to a first temperature threshold, a second start signal is generated; If the temperature of the heating module is greater than the first temperature threshold, a second shutdown signal is generated, including: When the temperature change trend of the heating module is a temperature rising trend, the resistance value of the thermistor decreases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage falling trend; In the case where the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage decreasing trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is greater than or equal to a first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second start signal; If the voltage at the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than the first voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal.

11. The method according to claim 10, characterized in that In the case where the temperature change trend of the heating module is a temperature decreasing trend, if the temperature of the heating module is greater than or equal to a second temperature threshold, a second shutdown signal is generated; If the temperature of the heating module is lower than the second temperature threshold, a second start signal is generated, including: When the temperature change trend of the heating module is a temperature decreasing trend, the resistance value of the thermistor increases, and the voltage change trend of the in-phase input terminal of the in-phase Schmidt comparator circuit is a voltage increasing trend; In the case where the voltage change trend of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is a voltage rising trend, if the voltage of the non-inverting input terminal of the non-inverting Schmitt comparator circuit is less than or equal to a second voltage threshold, the output terminal of the non-inverting Schmitt comparator circuit outputs a second shutdown signal; If the voltage at the in-phase input terminal of the in-phase Schmitt comparator circuit is greater than a second voltage threshold, the output terminal of the in-phase Schmitt comparator circuit outputs a second start signal; The second voltage threshold is greater than the first voltage threshold.

12. The method according to claim 8, characterized in that The second driving signal includes a second on signal and a second off signal; the method further includes: The main control circuit monitors the second driving signal output from the output end of the hysteresis circuit in real time at a preset time period; When the heating control instruction is a heating on instruction, if the output end of the hysteresis circuit outputs a second shutdown signal, the heating on instruction is updated to a heating off instruction to drive the power management circuit to generate a first shutdown signal corresponding to the heating off instruction.

13. The method according to claim 7, characterized in that The first driving signal includes a first on signal and a first off signal; the second driving signal includes a second on signal and a second off signal; the heating control signal includes a heating on signal and a heating off signal; The logic circuit generates a heating control signal according to the first driving signal and the second driving signal to turn on or off the heating module, including: Generate a heating start signal according to the first start signal and the second start signal to turn on the heating module; or, A heating shutoff signal is generated according to the first shutoff signal and / or the second shutoff signal to shut off the heating module.

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