A heating control system for a full liquid crystal instrument of an automobile in a low temperature environment

Abstract

The application discloses a kind of low-temperature environment under the heating control system of automobile full liquid crystal instrument, it is related to vehicle-mounted electronic equipment technical field, and the temperature of automobile full liquid crystal instrument display screen is automatically controlled by pure hardware circuit;When liquid crystal screen ambient temperature is at normal temperature state, heating module does not heat;When liquid crystal screen ambient temperature is lower than preset starting heating temperature point, start heating;Heating analysis module is used to heat analysis according to PT1 temperature and liquid crystal screen ambient temperature, and heating compensation value WB is calculated, and the output power of heating module is determined as PW according to heating compensation value WB;Constant temperature heating control is realized;When liquid crystal screen ambient temperature reaches preset stop heating temperature point or PT1 temperature reaches set value, heating module is closed by heating control module, avoid PT1 temperature too high and lead to burnout;The application has the advantages of simple and efficient circuit, reliable novelty, small size, low cost, easy to realize.

Description

Technical Field

[0001] This invention relates to the field of automotive electronic equipment technology, specifically a heating control system for a fully digital instrument cluster in a low-temperature environment. Background Technology

[0002] Currently, the operating temperature of the LCD screens used in automotive full LCD instrument panels is -20℃, with a minimum of -30℃. This is due to the characteristics of the liquid crystal materials within the LCD screen. When the operating temperature of the LCD screen is below -30℃, the activity of the liquid crystal materials decreases, and the performance deteriorates. Since the operating temperature requirement for automobiles is -40℃, and the operating temperature requirement for special vehicles is even higher, reaching -45℃ to -50℃, the limitations of material technology itself make it difficult to achieve breakthroughs in the application of full LCD instrument panels in low-temperature environments.

[0003] To ensure the LCD screen continues to function in low-temperature environments, such as -40°C, it needs to be heated. Existing heating methods involve using the LCD screen's built-in IC temperature sensor to collect the IC temperature and determining whether to heat the screen based on this temperature. However, because the IC temperature rises more slowly than the LCD screen surface temperature, this lag means that the LCD screen cannot refresh normally when the temperature drops, and the heating module continues to operate when the temperature rises, potentially causing the LCD screen to burn out. To address these shortcomings, this invention proposes a heating control system for automotive full LCD instrument panels in low-temperature environments. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a heating control system for automotive full LCD instrument panels in low-temperature environments. The system employs a novel polyimide heating film, a semiconductor N-type MOS transistor switch, an NTC temperature sensor, and a comparator temperature control to effectively control the temperature of the LCD screen. This allows the automotive full LCD instrument panel to operate normally and reliably at low temperatures, meeting the requirements for rapid and safe constant-temperature heating control of the LCD screen itself in environments as low as -50℃. Automatic temperature control of the automotive full LCD instrument panel display is achieved through a purely hardware circuit, realizing constant-temperature heating and controlling the difference between the heating start temperature and the heating stop temperature, ensuring that the internal liquid crystal of the full LCD instrument panel operates within a specified temperature range. This system has the advantages of simple and efficient circuitry, reliability, novelty, small size, low cost, and ease of implementation.

[0005] To achieve the above objectives, an embodiment of the first aspect of the present invention provides a heating control system for an automotive full LCD instrument panel in a low-temperature environment, comprising a heating module, a heating power output module, an electric heating film temperature sensor, an LCD screen ambient temperature sensor, a heating analysis module, a heating control module, a circuit protection module, and a database.

[0006] The heating module is a polyimide heating film PT1; the electrothermal film temperature sensor is used to detect the temperature of PT1 and transmit the PT1 temperature to the heating control module and the heating analysis module; the LCD screen ambient temperature sensor is used to detect the LCD screen ambient temperature and transmit the LCD screen ambient temperature to the heating control module and the heating analysis module.

[0007] The heating control module is used to control the heating module to turn on or off; specifically:

[0008] When the ambient temperature of the LCD screen is at room temperature, the heating module does not heat; when the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module is turned on by the heating control module; when the ambient temperature of the LCD screen reaches the preset stopping heating temperature, the heating module is turned off by the heating control module; when the PT1 temperature reaches the set value, the heating module is turned off by the heating control module.

[0009] When the heating module is turned on, the heating analysis module is used to perform heating analysis based on the PT1 temperature and the ambient temperature of the LCD screen, calculate the heating compensation value WB, and determine the output power of the heating module as PW based on the heating compensation value WB; the heating power output module is used to control the heating module to heat with the output power PW to achieve constant temperature heating control.

[0010] Furthermore, the specific analysis steps of the heating analysis module are as follows:

[0011] When the heating module is turned on, the temperature of PT1 and the ambient temperature of the LCD screen are obtained and marked as W1 and W2 respectively; the preset start heating temperature point is set as N1 and the preset stop heating temperature point is set as N2;

[0012] If W2≤N1, the formula for calculating the heating compensation value is as follows:

[0013]

[0014] Where a1 and a2 are coefficient factors, and WB is the heating compensation value; if W2 > N1, then the formula is used. The heating compensation value WB is calculated.

[0015] Furthermore, the output power of the heating module is determined to be PW based on the heating compensation value WB. Specifically, the database stores a mapping table between the range of heating compensation values ​​and the output power threshold. The corresponding heating compensation value range is determined based on the heating compensation value WB, and then the corresponding output power threshold is determined based on the heating compensation value range and marked as PW.

[0016] Furthermore, the heating power output module is a heating power output circuit composed of resistor R8 and power MOSFET Q1; the electric heating film temperature sensor is a negative temperature coefficient thermistor NTC2; the LCD screen ambient temperature sensor is a negative temperature coefficient thermistor NTC1; the heating control module is a heating control loop composed of two sets of operational amplifiers U1A and U1B; and the circuit protection module includes a resettable fuse F1 and a silicon rectifier diode D1.

[0017] Furthermore, apart from NTC2 and PT1, all other components are surface-mounted on the PCB, which is installed 1 cm away from the back of the car's full LCD instrument panel.

[0018] Furthermore, the LCD screen does not heat up at room temperature; its specific working principle is as follows:

[0019] When the ambient temperature of the LCD screen detected by NTC1 is higher than the preset starting heating temperature, the resistance of NTC1 is small, resulting in a high voltage division value between NTC1 and R5. The voltage at pin 2 of the inverting input of U1A is higher than that at pin 3 of the non-inverting input. Pin 1 of U1A, pin 5 of U1B, and pin 7 of the output of U1B are low. The gate of Q1 is low, Q1 is turned off, and the heating module PT1 does not heat up.

[0020] Furthermore, when the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module is activated. The specific working principle is as follows:

[0021] When the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the resistance of NTC1 increases, causing the voltage division value between NTC1 and R5 to decrease. The voltage at pin 2 of the inverting input of U1A is lower than the voltage at pin 3 of the non-inverting input, REF1. Pin 1 of U1A outputs a high level, which is sent to pin 5 of the non-inverting input of U1B through R6. U1B outputs a high level. The gate of Q1 is high, Q1 is turned on, and the heating module PT1 starts heating.

[0022] Furthermore, the feature is that, when the ambient temperature of the LCD screen reaches the preset stop heating temperature point, the heating module is turned off. The specific working principle is as follows:

[0023] When the ambient temperature of the LCD screen is heated to the point that the voltage division value of NTC1 and R5 is higher than the voltage REF1 at pin 3 of the U1A op-amp, the voltage REF1 is the voltage division value of R1 and R4. Since pin 1 of U1A is high at this time and R3 is not connected in parallel with R4, the output of pin 1 of comparator U1A is low, pins 5 and 7 of U1B and the gate of Q1 are low, Q1 is turned off, and the heating module PT1 stops heating.

[0024] Furthermore, the heating module shuts off when the PT1 temperature reaches the set value; specifically:

[0025] When the temperature of PT1 reaches the set value, the resistance of NTC2 decreases. When the voltage division value between R6 and NTC2, i.e., the voltage at the non-inverting input of pin 5 of U1B, is lower than the voltage at the inverting input of pin 6 (REF2), pin 7 outputs a low level, and the heating module PT1 stops heating.

[0026] Furthermore, in the circuit, the ambient temperature reference voltage at the non-inverting input of operational amplifier U1A is obtained by using a resistor divider, with R1 being the upper voltage divider resistor and R4 being the lower voltage divider resistor. A differential setting resistor R3 is added between the non-inverting input and the output input. By changing the resistance value of R3, the temperature difference between the starting temperature heating point and the stopping temperature heating point can be adjusted.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. In this invention, when the ambient temperature of the LCD screen is at room temperature, the heating module does not heat; when the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module is turned on by the heating control module; the heating analysis module is used to perform heating analysis based on the PT1 temperature and the ambient temperature of the LCD screen; the PT1 temperature and the ambient temperature of the LCD screen are obtained and marked as W1 and W2 respectively; the preset starting heating temperature is set as N1, the preset stopping heating temperature is set as N2, and the heating compensation value WB is calculated; the output power of the heating module is determined as PW based on the heating compensation value WB; the heating power output module is used to control the heating module to heat with the output power PW to achieve constant temperature heating control; when the ambient temperature of the LCD screen reaches the preset stopping heating temperature or the PT1 temperature reaches the set value, the heating module is turned off by the heating control module; this invention realizes the automatic heating control operation of the automotive full LCD instrument LCD screen in a low-temperature environment, without the need for complex microprocessors or single-chip microcomputer control, and is completed by pure hardware circuits, which has the advantages of low cost, easy implementation, and reduced technical difficulty of heating control.

[0029] 2. In this invention, the ambient temperature reference voltage at the non-inverting input of operational amplifier U1A is determined by a resistor divider, with R1 as the upper divider resistor and R4 as the lower divider resistor. A differential setting resistor R3 is added between the non-inverting input and the output. When the circuit operates with the output of pin 1 of U1A low, R3 and R4 are connected in parallel, causing the REF1 voltage to decrease. When the output of pin 1 of U1A is high, R3 is effectively disconnected from R4, causing the REF1 voltage to increase. Due to the clever addition of R3, the ambient reference voltage at pin 3 of the U1A comparator is actually two different reference voltage values. Adjusting the resistance of R3 can adjust the temperature difference between the starting and stopping heating points, enabling heating to start and stop within a specified temperature range. This avoids frequent fluctuations around a certain temperature point, preventing the heating module from constantly opening and closing, thus ensuring reliable and stable heating control. This solves the technical problem of traditional analog circuits being unable to separate the temperature control points of the starting and stopping heating points, as well as the technical problem of frequent opening and closing oscillations around the heating point. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a system block diagram of a heating control system for a fully digital instrument cluster in a low-temperature environment, according to the present invention.

[0032] Figure 2 This is a circuit diagram of a heating control system for a fully digital instrument cluster in a low-temperature environment, according to the present invention. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] like Figures 1 to 2 As shown, a heating control system for a fully digital instrument cluster in a low-temperature environment includes a heating module, a heating power output module, an electric heating film temperature sensor, an ambient temperature sensor for the LCD screen, a heating analysis module, a heating control module, a circuit protection module, and an automotive LCD screen.

[0035] The heating module is a polyimide heating film PT1. The heating power output module is connected to the heating module and is used to control the output power of the heating module. During the heating process, the output power of the heating module is controlled according to the temperature of PT1 to achieve constant temperature heating control.

[0036] The LCD screen ambient temperature sensor is used to detect the ambient temperature of the LCD screen and transmit the ambient temperature to the heating control module and the heating analysis module; the electrothermal film temperature sensor is used to detect the temperature of the polyimide heating film PT1 and transmit the temperature of PT1 to the heating control module and the heating analysis module;

[0037] The heating control module is used to control the heating module to turn on or off; specifically:

[0038] When the ambient temperature of the LCD screen is at room temperature, the heating module does not heat up; room temperature is represented by the temperature range from the preset start heating temperature point to the preset stop heating temperature point.

[0039] When the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module is turned on by the heating control module; when the ambient temperature of the LCD screen reaches the preset stopping heating temperature, the heating module is turned off by the heating control module.

[0040] When the temperature of PT1 reaches the set value, the heating module is turned off by controlling the heating module.

[0041] The heating analysis module is used to perform heating analysis based on the PT1 temperature and the ambient temperature of the LCD screen to obtain the output power of the heating module; the specific analysis steps are as follows:

[0042] When the heating module is turned on, the temperature of PT1 and the ambient temperature of the LCD screen are obtained and marked as W1 and W2 respectively; the preset start heating temperature point is set as N1 and the preset stop heating temperature point is set as N2;

[0043] If W2≤N1, the formula for calculating the heating compensation value is as follows:

[0044]

[0045] Where a1 and a2 are coefficient factors, and WB is the heating compensation value;

[0046] If W2 > N1, then use the formula The heating compensation value WB is calculated.

[0047] The output power of the heating module is determined to be PW based on the heating compensation value WB; specifically:

[0048] The database stores a mapping table between heating compensation value range and output power threshold; the corresponding heating compensation value range is determined based on the heating compensation value WB, and then the corresponding output power threshold is determined based on the heating compensation value range and marked as PW;

[0049] The heating analysis module is used to share the output power PW to the heating power output module, and the heating power output module is used to control the heating module to heat with the output power PW to achieve constant temperature heating control.

[0050] Among them, such as Figure 2 As shown, the system is controlled by a pure hardware circuit. The heating power output module is a heating power output circuit composed of resistor R8 and power MOSFET Q1; the electric heating film temperature sensor is a negative temperature coefficient thermistor NTC2; the LCD screen ambient temperature sensor is a negative temperature coefficient thermistor NTC1; the heating control module is a heating control loop composed of two sets of operational amplifiers U1A and U1B; the circuit protection module includes a self-resetting fuse F1 and a silicon rectifier diode D1; F1 is a self-resetting fuse to realize the short-circuit self-resetting protection function; D1 is a reverse connection protection diode to prevent the heater from working when the power supply is reversed; except for NTC2 and PT1, all these components are surface-mounted on the PCB, and the PCB is installed 1 cm away from the back of the car's full LCD instrument panel.

[0051] The specific working principle of the heating control loop is as follows:

[0052] S1: LCD screen does not heat at room temperature: At room temperature, the ambient temperature of the LCD screen detected by NTC1 is higher than the preset starting heating temperature. The resistance of NTC1 is small, which makes the voltage division value between NTC1 and R5 higher. The voltage of pin 2 of the inverting input of U1A is higher than that of pin 3 of the non-inverting input. Pin 1 of U1A, pin 5 of U1B, and pin 7 of the output of U1B are low. The gate of Q1 is low, Q1 is turned off, and the heating module PT1 does not heat.

[0053] S2: When the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module PT1 starts heating: When the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the resistance of NTC1 increases, causing the voltage division value between NTC1 and R5 to decrease. This voltage is lower than the voltage REF1 at pin 3 of the non-inverting input of U1A (at this time, the voltage REF1 is the voltage division value between R1 and (R4*R3 / R4+R3), because pin 1 of U1A is low). The comparator pin 1 outputs a high level, and this high level is sent to pin 5 of the non-inverting input of U1B through R6. U1B outputs a high level; the gate of Q1 is high, Q1 is turned on, and the heating module PT1 starts heating.

[0054] S3: When the ambient temperature of the LCD screen reaches the preset stop heating temperature, the heating module PT1 stops heating: When the ambient temperature of the LCD screen is heated to the point where the voltage division value of NTC1 and R5 is higher than that of pin 3 REF1 of U1A op-amp (at this time, the voltage of REF1 is the voltage division value of R1 and R4, because pin 1 of U1A is high at this time, and R3 is not connected in parallel with R4); the output of pin 1 of comparator U1A is low, pins 5 and 7 of U1B and the gate of Q1 are low, Q1 is turned off, and the heating module PT1 stops heating;

[0055] S4: When the temperature of PT1 reaches the set value, the heating module PT1 stops heating: During the heating process, that is, when pin 1 of U1A is at a high level, NTC2 detects the temperature of the heating module PT1. When the temperature of the heating module PT1 reaches the set value, the resistance of NTC2 decreases. When the voltage division value of R6 and NTC2, that is, the voltage at the non-inverting terminal of pin 5 of U1B, is lower than the voltage at the inverting terminal REF2 at pin 6, pin 7 outputs a low level, turning off the heating module;

[0056] This invention enables automatic heating control of the full LCD instrument panel in automobiles in low-temperature environments. It does not require complex microprocessors or microcontrollers and is completed by pure hardware circuits. It has the advantages of low cost, ease of implementation, and reduced technical difficulty in heating control.

[0057] In this embodiment, the ambient temperature reference voltage at the non-inverting input of operational amplifier U1A is divided by resistors, with R1 as the upper voltage divider and R4 as the lower voltage divider. A differential setting resistor R3 is added between the non-inverting input and the output. When the circuit operates with the output of pin 1 of U1A low, R3 and R4 are connected in parallel, causing the REF1 voltage to decrease. When the output of pin 1 of U1A is high, R3 is effectively disconnected from R4, causing the REF1 voltage to increase. Due to the clever addition of R3, the ambient reference voltage at pin 3 of the U1A comparator is actually two different reference voltage values. Adjusting the resistance of R3 can adjust the temperature difference between the starting and stopping heating points, enabling heating to start and stop within a specified temperature range. This avoids frequent fluctuations around a certain temperature point, preventing the heating module from constantly opening and closing, thus ensuring reliable and stable heating control. This solves the technical problem that traditional analog circuits cannot separate the temperature control points of the starting and stopping heating points, as well as the technical problem of frequent opening and closing oscillations around the heating point.

[0058] The above formulas are all numerical calculations after removing dimensions. The formulas are obtained by software simulation based on a large amount of data and are closest to the real situation. The preset parameters and preset thresholds in the formulas are set by those skilled in the art according to the actual situation or obtained by simulation based on a large amount of data.

[0059] Working principle of the invention:

[0060] A heating control system for a fully digital instrument cluster in a low-temperature environment includes: an ambient temperature sensor for detecting the ambient temperature of the LCD screen; a temperature sensor for detecting the temperature of the polyimide heating film PT1; when the ambient temperature of the LCD screen is at room temperature, the heating module does not heat; when the ambient temperature of the LCD screen is lower than a preset starting heating temperature, the heating module is activated by a heating control module; a heating analysis module performs heating analysis based on the PT1 temperature and the ambient temperature of the LCD screen; the PT1 temperature and the ambient temperature of the LCD screen are acquired and labeled as W1 and W2 respectively; the preset starting heating temperature is set to N1; and a preset stop heating temperature is set. The hot temperature point is N2, and the heating compensation value WB is calculated. Based on the heating compensation value WB, the output power of the heating module is determined to be PW. The heating power output module is used to control the heating module to heat at the output power PW to achieve constant temperature heating control. When the ambient temperature of the LCD screen reaches the preset stop heating temperature point or the PT1 temperature reaches the set value, the heating module is controlled to shut down through the heating control module. This invention realizes the automatic heating control operation of the automotive full LCD instrument LCD screen in low-temperature environments. It does not require complex microprocessors or single-chip microcomputer control, but is completed by pure hardware circuits. It has the advantages of low cost, easy implementation, and reduced technical difficulty of heating control.

[0061] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A heating control system for a fully digital instrument cluster in a low-temperature environment, characterized in that, It includes a heating module, a heating power output module, an electric heating film temperature sensor, an LCD screen ambient temperature sensor, a heating analysis module, a heating control module, a circuit protection module, and a database; The heating module is a polyimide heating film PT1; the electrothermal film temperature sensor is used to detect the temperature of PT1 and transmit the PT1 temperature to the heating control module and the heating analysis module; the LCD screen ambient temperature sensor is used to detect the LCD screen ambient temperature and transmit the LCD screen ambient temperature to the heating control module and the heating analysis module. The heating control module is used to control the heating module to turn on or off; specifically: When the ambient temperature of the LCD screen is at room temperature, the heating module does not heat; when the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the heating module is turned on by the heating control module; when the ambient temperature of the LCD screen reaches the preset stopping heating temperature, the heating module is turned off by the heating control module; when the PT1 temperature reaches the set value, the heating module is turned off by the heating control module. When the heating module is turned on, the heating analysis module is used to perform heating analysis based on the PT1 temperature and the ambient temperature of the LCD screen, calculate the heating compensation value WB, and determine the output power of the heating module as PW based on the heating compensation value WB. The heating power output module is used to control the heating module to heat with an output power PW, thereby achieving constant temperature heating control. The heating power output module is a heating power output circuit composed of resistor R8 and power MOSFET Q1; the electric heating film temperature sensor is a negative temperature coefficient thermistor NTC2; the LCD screen ambient temperature sensor is a negative temperature coefficient thermistor NTC1; the heating control module is a heating control loop composed of two sets of operational amplifiers U1A and U1B; the circuit protection module includes a resettable fuse F1 and a silicon rectifier diode D1. Except for NTC2 and PT1, all other components are surface-mounted on the PCB, which is installed 1 cm away from the back of the car's full LCD instrument panel. The LCD screen does not heat up at room temperature. Its specific working principle is as follows: When the ambient temperature of the LCD screen detected by NTC1 is higher than the preset starting heating temperature, the resistance of NTC1 is small, resulting in a high voltage division value between NTC1 and R5. The voltage at pin 2 of the inverting input of U1A is higher than that at pin 3 of the non-inverting input. Pin 1 of U1A, pin 5 of U1B, and pin 7 of the output of U1B are low. The gate of Q1 is low, Q1 is turned off, and the heating module PT1 does not heat up. When the ambient temperature of the LCD screen is lower than the preset initial heating temperature, the heating module is activated. The specific working principle is as follows: When the ambient temperature of the LCD screen is lower than the preset starting heating temperature, the resistance of NTC1 increases, causing the voltage division value between NTC1 and R5 to decrease. The voltage at pin 2 of the inverting input of U1A is lower than the voltage at pin 3 of the non-inverting input, REF1. Pin 1 of U1A outputs a high level, which is sent to pin 5 of the non-inverting input of U1B through R6. U1B outputs a high level. The gate of Q1 is high, Q1 is turned on, and the heating module PT1 starts heating. When the ambient temperature of the LCD screen reaches the preset stop heating temperature, the heating module shuts off. The specific working principle is as follows: When the ambient temperature of the LCD screen is heated to the point that the voltage division value of NTC1 and R5 is higher than the voltage REF1 at pin 3 of the U1A op-amp, the voltage REF1 is the voltage division value of R1 and R4. Since pin 1 of U1A is high at this time and R3 is not connected in parallel with R4, the output of pin 1 of comparator U1A is low, pins 5 and 7 of U1B and the gate of Q1 are low, Q1 is turned off, and the heating module PT1 stops heating. The heating module shuts off when the PT1 temperature reaches the set value; specifically: When the temperature of PT1 reaches the set value, the resistance of NTC2 decreases. When the voltage division value between R6 and NTC2, i.e., the voltage at the non-inverting input of pin 5 of U1B, is lower than the voltage at the inverting input of pin 6, REF2, pin 7 outputs a low level, and the heating module PT1 stops heating. In the circuit, the ambient temperature reference voltage at the non-inverting input of operational amplifier U1A is obtained by using a resistor divider. R1 is the upper voltage divider resistor, and R4 is the lower voltage divider resistor. A differential setting resistor R3 is added between the non-inverting input and the output input. By changing the value of R3, the temperature difference between the starting temperature heating point and the stopping temperature heating point can be adjusted.

2. The automotive full LCD instrument heating control system under low-temperature environment according to claim 1, characterized in that, The specific analysis steps of the heating analysis module are as follows: When the heating module is turned on, the temperature of PT1 and the ambient temperature of the LCD screen are acquired and marked as W1 and W2 respectively; the preset start heating temperature point is set as N1 and the preset stop heating temperature point is set as N2; If W2≤N1, the formula for calculating the heating compensation value is as follows: Where a1 and a2 are coefficient factors, and WB is the heating compensation value; if W2 > N1, then the formula is used. The heating compensation value WB is calculated.

3. The automotive full LCD instrument heating control system under low-temperature environment according to claim 2, characterized in that, The output power of the heating module is determined to be PW based on the heating compensation value WB. Specifically, the database stores a mapping table between the heating compensation value range and the output power threshold. The corresponding heating compensation value range is determined based on the heating compensation value WB, and then the corresponding output power threshold is determined based on the heating compensation value range and marked as PW.

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