Vehicle lamp protection circuit and vehicle lighting device

Abstract

According to the vehicle lamp protection circuit and the vehicle lighting device, the over-temperature recognition unit is arranged for monitoring the temperature, when the temperature exceeds a preset value, the provided protection signal state is turned over, the driving output state of the protection driving unit can be changed, a driving power source of a lamp panel can be cut off, the lamp panel is prevented from being burnt out under the high-temperature working condition, and the service life of the lamp panel is prolonged. And the protection driving unit takes a triode as a switch, and an emitting electrode of the triode is connected to a driving output end of the protection driving unit and is serially connected to a driving path of the lamp panel, so that the output current can be limited, and the overcurrent risk is reduced. The vehicle lamp protection circuit and the vehicle lighting device provided by the utility model can effectively turn off the driving of the lamp panel when the temperature exceeds a preset value, realize over-temperature protection, realize the limitation of the driving current through the triode, realize current-limiting protection at the same time, reduce the interference of the fluctuation of the driving voltage to the lighting, and prolong the service life of the lighting device. And the safety and the anti-interference capability of the automobile lamp can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle lighting, and particularly relates to a headlight protection circuit and a vehicle lighting device. Background Art

[0002] LED (light emitting diode) has many rare advantages. Compared with traditional halogen tungsten bulbs, it has the advantages of low power, long life, short response time, small volume, etc. With people's increasing recognition of LEDs, LEDs are increasingly used in automobiles.

[0003] However, compared with halogen tungsten bulbs that emit light by heat, the heat resistance of LEDs is significantly worse, and they are easily burned out under high-temperature conditions. In the prior art, the high-temperature protection measure for LED headlight circuits often adopts the method of reducing the output current. In this treatment method, the LED still has the risk of being burned out, and working at high temperature will also reduce the life of the headlight. If the LED is burned out, even if the temperature returns to normal, the circuit cannot work properly. If this occurs in the vehicle headlight, it will have a particularly obvious impact on vehicle safety and is not convenient for maintenance, which is not conducive to the application expansion of LEDs in vehicles. Summary of the Utility Model

[0004] Based on this, the purpose of the utility model is to provide a headlight protection circuit and a vehicle lighting device to improve the over-temperature protection effect of LED headlights, reduce the maintenance cost, and facilitate the application expansion of LEDs in vehicles.

[0005] On one hand, the utility model provides a headlight protection circuit, including: an over-temperature recognition unit and a protection driving unit, wherein,

[0006] The protection signal output end of the over-temperature recognition unit is connected to the control end of the protection driving unit, the driving output end of the protection driving unit is connected to the driving positive end of the lamp board, and the driving positive end of the lamp board is connected with an LED light source;

[0007] The protection driving unit includes a first resistor, a triode, and a second resistor connected in sequence between the power supply end and the ground of the protection driving unit. The collector of the triode is connected to the first resistor, the emitter of the triode is connected to the second resistor, the base of the triode is connected to the control end of the protection driving unit, and the emitter of the triode is also connected to the driving output end of the protection driving unit.

[0008] Optionally, the over-temperature recognition unit includes:

[0009] A comparator, the output end of the comparator is connected to the protection signal output end of the over-temperature recognition unit;

[0010] A third resistor and a fourth resistor connected in series between the power supply terminal and the ground terminal of the overtemperature recognition unit, and an intermediate node of the third resistor and the fourth resistor is connected to the non-inverting input terminal of the comparator;

[0011] A thermistor and a fifth resistor connected in series between the power supply terminal and the ground terminal of the overtemperature recognition unit, an intermediate node of the thermistor and the fifth resistor is connected to the inverting input terminal of the comparator, and the thermistor is a negative temperature coefficient thermistor.

[0012] Optionally, a sixth resistor is further connected between the output terminal and the non-inverting input terminal of the comparator.

[0013] Optionally, the triode is an NPN type switching triode.

[0014] Optionally, the protection and drive unit further includes a seventh resistor connected between the control terminal of the protection and drive unit and the base of the triode.

[0015] Optionally, the protection and drive unit further includes an eighth resistor connected between the base of the triode and the ground terminal of the protection and drive unit.

[0016] Optionally, the power supply terminal of the overtemperature recognition unit is connected in parallel with the power supply terminal of the protection and drive unit.

[0017] Optionally, the high-level bias terminal and the low-level bias terminal of the comparator are respectively connected to the power supply terminal and the ground terminal of the overtemperature recognition unit.

[0018] The present invention further provides a vehicle lighting device, which includes a lamp board and the above-mentioned vehicle lamp protection circuit, and the lamp board includes an LED light source.

[0019] The headlight protection circuit provided by the present utility model includes an over-temperature recognition unit and a protection driving unit. Among them, the protection signal output terminal of the over-temperature recognition unit is connected to the control terminal of the protection driving unit, and the driving output terminal of the protection driving unit is connected to the positive driving terminal of the lamp board. When the temperature exceeds the preset value, the output state of the protection signal output terminal of the over-temperature recognition unit flips, controlling the state flip of the protection driving unit; the protection driving unit includes a first resistor, a triode, and a second resistor connected in sequence between the power supply terminal and the ground. The collector of the triode is connected to the first resistor, the emitter of the triode is connected to the second resistor, the base of the triode is connected to the control terminal of the protection driving unit, and the emitter of the triode is also connected to the driving output terminal of the protection driving unit. When the control terminal is at a logic high level, the triode conducts, driving the lamp board to emit light. When the control terminal is at a logic low level, the triode turns off, disconnecting the driving power supply of the lamp board, avoiding the lamp board from being burned out in a high-temperature environment, and the triode can also limit the output current, reducing the risk of overcurrent. The headlight protection circuit provided by the present utility model can effectively turn off the driving of the lamp board when the temperature exceeds the preset value, realizing over-temperature protection, and can limit the driving current through the triode, simultaneously realizing current-limiting protection, reducing the interference of driving voltage fluctuations on lighting, and effectively improving the safety and anti-interference ability of the headlight. Brief Description of the Drawings

[0020] Figure 1 It is a schematic circuit structure diagram of the headlight protection circuit in the present utility model.

[0021] The following specific embodiments will further illustrate the present utility model in conjunction with the above-mentioned drawings. Specific Embodiments

[0022] For the convenience of understanding the present utility model, the present utility model will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present utility model are given in the drawings. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present utility model more thorough and comprehensive.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] In order to solve the problem that the over-temperature protection effect of LED headlights in the prior art is insufficient, which is not conducive to the expansion of LED applications in vehicles, the utility model provides a headlight protection circuit, which includes an over-temperature identification unit and a protection drive unit, wherein the protection signal output end of the over-temperature identification unit is connected to the control end of the protection drive unit, and the drive output end of the protection drive unit is connected to the drive positive end of the lamp board. When the temperature exceeds the preset value, the output state of the protection signal output end of the over-temperature identification unit is flipped, and the state of the protection drive unit is controlled to flip. After the state of the protection drive unit is flipped, the drive output is cut off, and the drive power supply of the lamp board is disconnected, thereby preventing the lamp board from continuing to work under high temperature dangerous conditions, and effectively reducing the risk of irreversible damage to the LED light source in the lamp board. After the temperature is restored, it can work again, thereby improving the practicality of the vehicle.

[0026] Specifically, such as Figure 1 As shown in FIG. 1 , the protection signal output terminal of the over-temperature identification unit 10 is connected to the control terminal of the protection drive unit 20, and the drive output terminal of the protection drive unit 20 is connected to the positive drive terminal of the light board 01. When the car light protection circuit is connected to the power supply VCC, when the temperature is normal, the drive output terminal of the protection drive unit 20 is valid and can drive the light board 01 to emit light.

[0027] In order to disconnect the driving power of the lamp board 01 when over-temperature occurs, in this embodiment, the protection driving unit 20 includes a first resistor R1, a transistor Q1, and a second resistor R2 which are sequentially connected between the power supply end of the protection driving unit 20 and the ground, the collector of the transistor Q1 is connected to the first resistor R1, the emitter of the transistor Q1 is connected to the second resistor R2, the base of the transistor Q1 is connected to the control end of the protection driving unit 10, and the emitter of the transistor Q1 is also connected to the driving output end of the protection driving unit 20.

[0028] When the temperature is lower than the preset value, the protection signal output by the over-temperature identification unit 10 is a logic high level, which can drive the transistor Q1 to turn on, thereby providing power output at the emitter of the transistor Q1 to drive the light board 01 to emit light.

[0029] ​​When the temperature is higher than the preset value, the protection signal output by the over-temperature recognition unit 10 is inverted to a logic low level. This protection signal can drive the triode Q1 to turn off, thereby disconnecting the power supply at the emitter of the triode Q1 and cutting off the power supply to the lamp board 01, preventing the LED light source in the lamp board 01 from continuing to work at high temperature, effectively reducing the risk of irreversible damage to the LED light source in the lamp board. After the temperature recovers, the protection signal output by the over-temperature recognition unit 10 returns to a logic high level, and the protection driving unit 20 resumes output, driving the lamp board 01 to resume lighting.

[0030] Among them, the triode can not only be used as a switch to control the power supply switch of the lamp board, but also limit the saturation current of the triode to simultaneously achieve current limiting protection of the lamp board, reduce the interference of driving voltage fluctuations on lighting, and effectively improve the safety and anti-interference ability of vehicle lamps.

[0031] Since the impedance of the triode in the working saturation state is extremely small, the first resistor R1 and the second resistor R2 can also be used to regulate the driving voltage and driving current of the lamp board 01, further reducing the risk of overvoltage and overcurrent.

[0032] To ensure the effectiveness of over-temperature recognition, in this embodiment, the over-temperature recognition unit 10 uses the comparator U1 as the main logic controller for operation. The output end of the comparator U1 is connected to the protection signal output end of the over-temperature recognition unit 10. The over-temperature recognition unit 10 is provided with a third resistor R3 and a fourth resistor R4 connected in series between its power supply terminal and the ground terminal in sequence. The middle node of the third resistor R3 and the fourth resistor R4 is connected to the non-inverting input terminal of the comparator U1 to obtain a reference voltage according to the voltage division of the power supply VCC; a thermistor TH and a fifth resistor R5 are also connected in series between the power supply terminal and the ground terminal of the over-temperature recognition unit 10 in sequence. The middle node of the thermistor TH and the fifth resistor R5 is connected to the inverting input terminal of the comparator U1 to provide a detection voltage that changes with temperature. The thermistor TH is a negative temperature coefficient thermistor.

[0033] When the temperature is lower than the preset value, as the temperature rises, the resistance value of the thermistor TH gradually decreases, and the detection voltage gradually increases. When the temperature exceeds the preset value, the detection voltage exceeds the reference voltage, and the protection signal output by the comparator U1 is inverted from a logic high level to a logic low level.

[0034] Among them, both the reference voltage and the detection voltage are obtained according to the voltage division of the power supply VCC. When the power supply VCC fluctuates, their voltage division ratio relationship remains unchanged, and the magnitude relationship remains unchanged, which can maintain the state of the protection signal, thereby effectively reducing the interference of power supply fluctuations on over-temperature recognition, improving the accuracy of over-temperature protection, and improving the working reliability of vehicle lamps.

[0035] To further improve the reliability of over-temperature recognition, in this embodiment, a sixth resistor R6 is also connected between the output terminal and the non-inverting input terminal of the comparator U1 to form a hysteresis comparator. When the temperature fluctuates greatly, the output can be maintained to avoid false triggering of over-temperature protection, effectively improving the accuracy of over-temperature protection and the working reliability of the vehicle lamp.

[0036] To enhance the driving ability of the driving protection unit 20 for the lamp board, in this embodiment, the triode Q1 is an NPN-type switching triode with stronger load-carrying capacity, which can be applied to the power requirements of various vehicle lights.

[0037] To improve the switching control reliability of the protection driving unit 20, in this embodiment, the protection driving unit 20 further includes a seventh resistor R7 connected between the control terminal of the protection driving unit 20 and the base of the triode Q1, which can be used as a current-limiting resistor to reduce the possibility of damage to the triode Q1 caused by pulses that may occur during circuit state changes.

[0038] To further reduce the risk of damage to the triode Q1, in this embodiment, the protection driving unit 20 further includes an eighth resistor R8 connected between the base of the triode Q1 and the ground terminal of the protection driving unit 20, which can be used for discharging pulsed current, reducing the interference of the pulsed current on the state of the triode Q1, and further improving the reliability of the protection driving.

[0039] In this embodiment, the power supply terminals of the over-temperature recognition unit 10 and the protection driving unit 20 are connected in parallel and share the power supply VCC, which can reduce the demand for the power supply and the circuit implementation cost.

[0040] The logic high level and logic low level provided by the comparator U1 need to be confirmed by external biasing. In this embodiment, the high-level biasing terminal and the low-level biasing terminal of the comparator U1 are respectively connected to the power supply terminal and the ground terminal of the over-temperature recognition unit 10, so that its logic level is the output voltage of the power supply VCC. The logic high level can also drive the triode Q1 after being divided by the seventh resistor R7 and the eighth resistor R8. The parameters of the seventh resistor R7 and the eighth resistor R8 can be specifically selected according to the saturation driving voltage of the triode Q1 and the configuration of the power supply VCC.

[0041] The present utility model also provides a vehicle lighting device, which includes a lamp board and the above-mentioned vehicle lamp protection circuit. The lamp board includes an LED light source, which can effectively improve the over-temperature protection effect on the LED light source, reduce the risk of damage to the LED light source, improve the working reliability of the vehicle LED lights, and further improve the application prospect of the LED in the vehicle.

[0042] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0043] The above-described embodiments merely represent several specific implementation manners of the present utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model shall be subject to the appended claims.

Claims

1. A vehicle lamp protection circuit, characterized in that: include: Over-temperature identification unit and protection drive unit, wherein, The protection signal output end of the over-temperature identification unit is connected to the control end of the protection driving unit, the driving output end of the protection driving unit is connected to the driving positive end of the lamp board, and the driving positive end of the lamp board is connected to the LED light source; The protection driving unit includes a first resistor, a transistor and a second resistor which are sequentially connected between the power supply end and the ground of the protection driving unit, the collector of the transistor is connected to the first resistor, the emitter of the transistor is connected to the second resistor, the base of the transistor is connected to the control end of the protection driving unit, and the emitter of the transistor is also connected to the driving output end of the protection driving unit.

2. The vehicle lamp protection circuit according to claim 1, characterized in that: The over-temperature identification unit comprises: A comparator, wherein an output end of the comparator is connected to a protection signal output end of the over-temperature identification unit; A third resistor and a fourth resistor are sequentially connected in series between the power supply terminal and the ground terminal of the over-temperature identification unit, and an intermediate node between the third resistor and the fourth resistor is connected to the non-inverting input terminal of the comparator; A thermistor and a fifth resistor are connected in series between the power supply terminal and the ground terminal of the over-temperature identification unit, and an intermediate node between the thermistor and the fifth resistor is connected to the inverting input terminal of the comparator. The thermistor is a negative temperature coefficient thermistor.

3. The vehicle lamp protection circuit according to claim 2, characterized in that: A sixth resistor is also connected between the output terminal and the non-inverting input terminal of the comparator.

4. The vehicle lamp protection circuit according to claim 1, characterized in that: The transistor is an NPN type switching transistor.

5. The vehicle lamp protection circuit according to claim 1, characterized in that: The protection driving unit further includes a seventh resistor connected between the control terminal of the protection driving unit and the base of the transistor.

6. The vehicle lamp protection circuit according to claim 1 or 5, characterized in that: The protection driving unit also includes an eighth resistor connected between the base of the transistor and the ground terminal of the protection driving unit.

7. The vehicle lamp protection circuit according to claim 1, characterized in that: The power supply terminal of the over-temperature identification unit is connected in parallel with the power supply terminal of the protection driving unit.

8. The vehicle lamp protection circuit according to claim 2, characterized in that: The high bias terminal and the low bias terminal of the comparator are respectively connected to the power supply terminal and the ground terminal of the over-temperature identification unit.

9. A vehicle lighting device, characterized in that: It comprises a lamp board and the vehicle lamp protection circuit according to any one of claims 1 to 8, wherein the lamp board comprises an LED light source.

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