Vehicle LED lamp brightness adaptive control method based on drive control circuit

Abstract

The invention discloses a vehicle LED lamp brightness self-adaptive control method based on a drive control circuit. The method comprises the steps that a heat attenuation compensation module monitors the brightness of all LED loads; a constant current driving module adjusts the current of each group of LED loads according to the brightness value monitored by the thermal attenuation compensation module; a step of monitoring output information of all the fault detection modules by an on-off control module; and outputting a low level or a high level to the control end of the LED power supply module by the on-off control module. By adopting the method, the current can be adaptively adjusted according to the brightness fluctuation of the LED; different requirements can be directly matched, a modularized development mode is realized, the development period can be greatly shortened, and the development cost is reduced; the driving control circuit completely adopts discrete components to realize all functions, the cost is low, heating positions are dispersed, the heat dissipation design difficulty is low, the heat dissipation processing cost is low, meanwhile, the number of LED loads is not limited by channels of chips, and flexible expansion can be realized according to requirements.

Description

Technical Field

[0001] This invention relates to the field of vehicle lighting control methods, specifically to an adaptive brightness control method for automotive LED lights based on a drive control circuit. Background Technology

[0002] With technological advancements, automotive lighting systems widely adopt LED light assemblies to achieve more diverse lighting effects and aesthetic designs. For exterior automotive lights such as reversing lights, fog lights, and position lights, regulations stipulate brightness requirements not only for the initial illumination and after 30 minutes of illumination, but also that they must either have a "one-off-all" function (i.e., if one LED turns off, all other LEDs turn off), or a function that ensures the overall brightness of the light system does not decrease if some LEDs turn off, by increasing the brightness of other LEDs.

[0003] Due to limitations in design principles, the circuits for the two functions mentioned above cannot be shared or modularized, resulting in poor versatility, long development cycles, and high development costs.

[0004] Furthermore, for existing circuits with the aforementioned two functions, due to the thermal decay of LEDs, a larger current is required to maintain a constant overall brightness of the lamp when the LED temperature rises. However, existing circuits do not have the function of adaptively adjusting the current based on LED brightness fluctuations. Moreover, existing circuits that allow some LEDs to be turned off while others are brightened to maintain the overall brightness of the lamp are mostly built using LED driver chips. Not only are LED driver chips expensive, but heat dissipation is also concentrated at the LED driver chip, making heat dissipation design difficult and costly. Additionally, the number of LEDs driven in existing circuits depends entirely on the number of channels in the LED driver chip, resulting in poor scalability.

[0005] Solving these problems is now a top priority. Summary of the Invention

[0006] To address the technical problems of existing automotive LED lamp driver control circuits, such as poor versatility, inability to achieve modular development, high cost, lack of LED thermal decay brightness compensation function, and concentrated heat generation, this invention provides an adaptive brightness control method for automotive LED lamps based on a driver control circuit.

[0007] The technical solution is as follows:

[0008] The first aspect of this application relates to an adaptive brightness control method for automotive LED lights based on a drive control circuit. The drive control circuit includes a power supply, an LED power module, a constant current drive module, a thermal decay compensation module, a brightness control module, at least one set of LED loads, and fault detection modules corresponding to each LED load. The voltage input terminal of the LED power module is connected to the power supply. The constant current drive module, thermal decay compensation module, brightness control module, and each fault detection module are all connected to the voltage input terminal of the LED power module. The positive terminals of each set of LED loads are all connected to the voltage output terminal of the LED power module. The constant current drive module is also connected to the negative terminals of all LED loads. The thermal decay compensation module is connected to the constant current drive module and is adjacent to all LED loads. The input terminal of each fault detection module is connected to the negative terminal of the corresponding LED load. The output terminal of each fault detection module is connected to the input terminal of the brightness control module. The output terminal of the brightness control module is connected to the control terminal of the LED power module.

[0009] The adaptive brightness control method for automotive LED lights includes the following steps:

[0010] S1. The thermal decay compensation module monitors the brightness of all LED loads: If the brightness value monitored by the thermal decay compensation module is less than the minimum compliance value, proceed to step S2; if the brightness value monitored by the thermal decay compensation module is greater than the maximum compliance value, proceed to step S3; if the brightness value monitored by the thermal decay compensation module is greater than or equal to the minimum compliance value and less than or equal to the maximum compliance value, proceed to step S4.

[0011] S2. The constant current drive module increases the current of each group of LED loads according to the brightness value monitored by the thermal decay compensation module, and returns to step S1.

[0012] S3. The constant current drive module reduces the current of each group of LED loads according to the brightness value monitored by the thermal decay compensation module, and returns to step S1.

[0013] S4. The on / off control module monitors the output information of all fault detection modules: if not all fault detection modules output fault information, proceed to step S5; if all fault detection modules output fault information, proceed to step S6.

[0014] S5. The on / off control module outputs a low level to the control terminal of the LED power module, the LED power module supplies power to all LED loads, and returns to step S1.

[0015] S6, the on / off control module outputs a high level to the control terminal of the LED power module, and the LED power module stops supplying power to all LED loads.

[0016] The above-mentioned adaptive brightness control method for automotive LED lights based on drive control circuits has achieved the following technical effects:

[0017] 1. The thermal decay compensation module can monitor the overall brightness of automotive LED lights online, and together with the constant current drive module, it can adaptively adjust the current according to the brightness fluctuation of the LED, so that the brightness of the lamp remains basically constant and is not affected by the thermal decay of the LED.

[0018] 2. The drive control circuit, while meeting regulatory requirements, possesses excellent versatility, directly matching different needs and enabling modular development. This significantly shortens the development cycle and reduces development costs. For example, it can use only one set of LED loads, consisting of multiple LEDs connected in series. When the fault detection module detects a fault in any LED, it can send a high-level signal to the control terminal of the LED power module through the on / off control module, thus achieving the function of turning off all LEDs when one LED fails. Alternatively, it can use multiple sets of LED loads, each with its own fault detection module. This allows the LEDs that are not faulty to continue lighting even when not all sets of LED loads fail. Furthermore, by using a thermal decay compensation module in conjunction with a constant current drive module, the brightness of the LEDs that are not faulty can be improved, ensuring that the overall brightness of the automotive LED lights remains essentially unchanged.

[0019] 3. The drive control circuit uses discrete components to implement all functions, without using DC-DC converters and driver chips. This not only reduces costs, but also makes the heat dissipation locations extremely dispersed, making heat dissipation design simple and heat dissipation costs low. At the same time, the number of LED loads is not limited by the chip channels and can be flexibly expanded according to needs, further reducing design difficulty and production costs. Attached Figure Description

[0020] Figure 1 A flowchart of an adaptive brightness control method for automotive LED lights;

[0021] Figure 2 This is a schematic block diagram of the drive control circuit in Example 3;

[0022] Figure 3 This is a circuit diagram of the drive control circuit in Example 1;

[0023] Figure 4 This is a circuit diagram of the drive control circuit in Example 2. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0025] Example 1:

[0026] like Figure 2 and Figure 3As shown, a drive control circuit mainly includes a power supply 1, an LED power module 2, a thermal decay compensation module 7, a brightness control module 8, at least one set of LED loads 3, and a fault detection module 5 corresponding to each set of LED loads 3. The voltage input terminal of the LED power module 2 is connected to the power supply 1, and the positive terminal of each set of LED loads 3 is connected to the voltage output terminal of the LED power module 2.

[0027] The constant current drive module 4 is connected to the voltage output terminal of the LED power module 2. At the same time, the constant current drive module 4 is also connected to the negative terminal of each group of LED loads 3, thereby stabilizing the current of each group of LED loads 3 and thus stabilizing the brightness value of each group of LED loads 3.

[0028] Specifically, the constant current drive module 4 includes a Zener diode D20 and NPN transistors Q1 whose collectors are connected to the negative terminals of the corresponding LED loads 3. The emitters of each NPN transistor Q1 are connected in series with a corresponding resistor R2 and then grounded. The bases of all NPN transistors Q1 are connected to the common terminal of the negative terminal of the Zener diode D20 and the resistor R1. The other end of the resistor R1 is connected to the voltage output terminal of the LED power module 2. The reference terminal of the Zener diode D20 is connected to the common terminal of the emitter of any NPN transistor Q1 and the corresponding resistor R2. The positive terminal of the Zener diode D20 is grounded. By setting the Zener diode D20, its output is always a constant value. Therefore, the voltage of the LED load 3 is the Zener diode D20's regulated voltage divided by the resistance of the resistor R2, thus stabilizing the current and consequently stabilizing the brightness of all LEDs.

[0029] In this embodiment, the thermal decay compensation module 7 is connected to the constant current drive module 4, and the thermal decay compensation module 7 is adjacent to each LED load 3. The thermal decay compensation module 7 is used to adjust the current of each LED load 3 according to the brightness of each LED load 3 through the constant current drive module 4 to realize the adaptive adjustment function of the current magnitude, so that the brightness of the lamp is not affected by the thermal decay of the LED and remains basically constant, thus compensating for the problem of brightness reduction caused by LED thermal decay.

[0030] Specifically, the thermal decay compensation module 7 includes a PNP transistor Q4, a three-terminal adjustable shunt regulator D5, a first operational amplifier IC2A, a second operational amplifier IC2B, and a photodiode D4 adjacent to all LED loads 3. The anode and cathode of the photodiode D4 are connected to the inverting and non-inverting input terminals of the first operational amplifier IC2A, respectively. A resistor R18 is connected in series between the inverting and non-inverting input terminals of the first operational amplifier IC2A, and a capacitor C3 is also connected in series between the inverting and non-inverting input terminals of the first operational amplifier IC2A. The non-inverting input and negative power supply terminal of operational amplifier IC2A are both grounded. A resistor R19 is connected in series between the inverting input and output terminals of the first operational amplifier IC2A. A capacitor C1 is also connected in series between the inverting input and output terminals of the first operational amplifier IC2A. The output terminal of the first operational amplifier IC2A is connected in series with a resistor R17 and then connected to the inverting input terminal of the second operational amplifier IC2B. The positive power supply terminal of the first operational amplifier IC2A is connected to the voltage input terminal of LED power module 2. A resistor R20 is also connected in series with the positive power supply terminal of the first operational amplifier IC2A before connecting to a three-terminal converter. The negative terminal of the shunt regulator D5 is connected to ground, and the positive terminal of the three-terminal adjustable shunt regulator D5 is grounded. The common terminal of the negative terminal of the three-terminal adjustable shunt regulator D5 and resistor R20 is connected in series with resistors R21 and R22, and then grounded. The common terminal of resistors R21 and R22 is connected to the reference voltage terminal of the three-terminal adjustable shunt regulator D5. The reference voltage terminal of the three-terminal adjustable shunt regulator D5 is connected in series with resistor R23, and then connected to the non-inverting input terminal of the second operational amplifier IC2B. The common terminal of the non-inverting input terminal of the second operational amplifier IC2B and resistor R23 is connected in series with resistor R24, and then grounded. A resistor R16 is connected in series between the inverting input and output of the second operational amplifier IC2B. A capacitor C2 is also connected in series between the inverting input and output of the second operational amplifier IC2B. The output of the second operational amplifier IC2B is connected to the base of a PNP transistor Q4 after a resistor R15 is connected in series. The common terminal of the base of the PNP transistor Q4 and the resistor R15 is connected in series with a resistor R14 and then grounded. The emitter of the PNP transistor Q4 is connected to the common terminal of the cathode of the Zener diode D20 and the resistor R1. The collector of the PNP transistor Q4 is connected in series with a resistor R13 and then grounded.

[0031] When the light intensity received by photodiode D4 decreases, the transimpedance amplifier composed of the first operational amplifier IC2A will output an amplified voltage. This voltage is then amplified by the error amplifier composed of the second operational amplifier IC2B, and compared with the reference voltage, thus increasing the output voltage value. When the base current I of the PNP transistor Q4... B When the current increases, the collector current I of the PNP transistor Q4... C The current decreases, thereby reducing the base current I of the NPN transistor Q1. B This increases, and consequently increases the collector current I of the NPN transistor Q1.C The collector current I of NPN transistor Q1 C After the increase, the current of each LED load 3 group increases, thereby improving the brightness of the LED and compensating for the decrease in brightness value caused by LED thermal decay.

[0032] Therefore, by adding a thermal decay compensation module 7 composed of a PNP transistor Q4, a three-terminal adjustable shunt regulator D5, a first operational amplifier IC2A, a second operational amplifier IC2B, and a photodiode D4, not only can the current of each LED load 3 remain constant with almost no temperature drift when the ambient temperature changes, resulting in extremely stable LED brightness, but the accuracy of the current value from lighting to a stable state is also extremely high, with virtually no error. By setting the maximum current value required at high temperatures and the parameters of each component in the temperature compensation circuit, the brightness of the LED when it is first lit can also be accurately set, thus achieving the current compensation function. Furthermore, the thermal decay compensation module 7 can compensate for the current when lighting to a stable state, and the derating range is adjustable, solving the problem of regulatory failure caused by the light emission decay of the LED itself during the regulatory certification of the lamp.

[0033] The input terminals of each fault detection module 5 are connected to the negative terminal of the corresponding LED load 3, and the output terminals of each fault detection module 5 are connected to the input terminals of the on / off control module 8.

[0034] Specifically, each fault detection module 5 includes a first comparator IC1A and a second comparator IC1B. The negative input terminal of the first comparator IC1A and the positive input terminal of the second comparator IC1B are both connected to the negative terminal of the corresponding LED load 3. The positive input terminal of the first comparator IC1A is connected to the common terminal of the corresponding resistors R7 and R8. The negative input terminal of the second comparator IC1B is connected to the common terminal of the corresponding resistors R3 and R4. The other ends of resistors R8 and R3 are both connected to the voltage input terminal of the LED power supply module 2. The resistor R7... The other end of the circuit is grounded, as is the other end of resistor R4. The output of the first comparator IC1A and the output of the second comparator IC1B are connected to the anodes of diode D2 and diode D1, respectively. The common terminal of the first comparator IC1A and diode D2 is connected in series with the corresponding resistor R6 and then connected to the voltage input terminal of LED power module 2. The common terminal of the second comparator IC1B and diode D1 is connected in series with the corresponding resistor R5 and then connected to the voltage input terminal of LED power module 2. The cathodes of diode D2 and diode D1 are both connected to the input terminal of the on / off control module 8.

[0035] Taking an example where each LED load 3 consists of two LEDs connected in series with their positive and negative terminals. Assuming the forward voltage drop of the LED is 2.5V and the input voltage of LED load 3 is 12V, then the input voltage at the negative input terminal (pin 2) of the first comparator IC1A and the positive input terminal (pin 5) of the second comparator IC1B is 7V. By setting the resistance values ​​of resistors R3 and R4, the comparison voltage at the negative input terminal (pin 6) of the second comparator IC1B is set to 8V. By setting the resistance values ​​of resistors R7 and R8, the comparison voltage at the positive input terminal (pin 3) of the first comparator IC1A is set to 3V. Therefore, there are three possible scenarios:

[0036] Case 1: When all LEDs of LED load 3 are working normally, as can be seen from the above comparison voltage, the output terminal (pin 7) of the second comparator IC1B outputs a low level, the output terminal (pin 1) of the first comparator IC1A also outputs a low level, and diodes D1 and D2 are not conducting, thus outputting a low level to the on / off control module 8.

[0037] Case 2: When LED load 3 has an open circuit, the input voltage between the positive input terminal (pin 5) of the second comparator IC1B and the negative input terminal (pin 2) of the first comparator IC1A is approximately 0V. Based on the above comparison voltage, the output terminal (pin 7) of the second comparator IC1B outputs a low level, and the output terminal (pin 1) of the first comparator IC1A outputs a high level. Diode D2 is turned on, thus outputting a high level to the on / off control module 8.

[0038] Case 3: When LED load 3 has an LED short circuit, the input voltage between the positive input terminal (pin 5) of the second comparator IC1B and the negative input terminal (pin 2) of the first comparator IC1A is about 10V. As can be seen from the above comparison voltage, the output terminal (pin 7) of the second comparator IC1B outputs a high level, the output terminal (pin 1) of the first comparator IC1A outputs a low level, the diode D1 is turned on, and thus outputs a high level to the on / off control module 8.

[0039] The output terminal of the on / off control module 8 is connected to the control terminal of the LED power module 2. The on / off control module 8 is used to send different level signals (high level or low level) to the control terminal of the LED power module 2 when all fault detection modules 5 detect fault information and when not all fault detection modules 5 detect fault information.

[0040] Specifically, the on / off control module 8 includes an NPN transistor Q2 and MOS transistor conversion circuits corresponding to each fault detection module 5. The collector of the NPN transistor Q2 is connected to the voltage input terminal of the LED power module 2 via a series resistor R9. The common terminal of the collector of the NPN transistor Q2 and the resistor R9 is connected to the control terminal of the LED power module 2. The emitter of the NPN transistor Q2 is grounded. The base of the NPN transistor Q2 is connected to the ground via a series resistor R10 and a resistor R11. Each MOS transistor conversion circuit includes a MOS transistor Q3 and a diode D3. The gate of each MOS transistor Q3 is simultaneously connected to the cathode of the corresponding diode D1 and the cathode of the corresponding diode D2 in the fault detection module 5. The source of each MOS transistor Q3 is grounded. The drain of each MOS transistor Q3 is connected to the voltage input terminal of the LED power module 2 via a series resistor R12. The anode of each diode D3 is connected to the common terminal of the drain of the corresponding MOS transistor Q3 and the resistor R12. The cathodes of all diodes D3 are simultaneously connected to the common terminal of the resistors R10 and R11.

[0041] Taking a set of LED load 3 as an example, the LED load 3 is composed of multiple LEDs with positive and negative terminals connected in series. The positive terminal of the first LED is connected to the voltage output terminal of the LED power module 2, and the negative terminal of the last LED is connected to the negative input terminal of the first comparator IC1A, the positive input terminal of the second comparator IC1B, and the constant current drive module 4.

[0042] When all LEDs are working normally, the fault detection module 5 outputs a low level to the gate of MOSFET Q3, so MOSFET Q3 is not conducting. It outputs a high level to the anode of diode D3, so diode D3 conducts. It outputs a high level to the base of NPN transistor Q2, so NPN transistor Q2 conducts. This outputs a low level to the control terminal of LED power module 2, and the voltage output terminal of LED power module 2 supplies power to LED load 3 normally.

[0043] When any LED malfunctions, the fault detection module 5 outputs a high level to the gate of MOSFET Q3, turning MOSFET Q3 on. This outputs a low level to the anode of diode D3, de-conducting diode D3. Consequently, it outputs a low level to the base of NPN transistor Q2, de-conducting NPN transistor Q2. This, in turn, outputs a high level to the control terminal of LED power module 2, stopping the voltage output of LED power module 2 from supplying power to LED load 3. Therefore, it achieves a "one LED malfunctions, all LEDs malfunction" function.

[0044] Taking a setup with two sets of LED loads 3 as an example, each set of LED loads 3 consists of one or more LEDs connected in series with positive and negative terminals. The positive terminals of the LEDs at the beginning of the set are all connected to the voltage output terminal of the LED power module 2, and the negative terminals of the LEDs at the end of the set are respectively connected to the negative input terminal of the first comparator IC1A, the positive input terminal of the second comparator IC1B, and the constant current drive module 4.

[0045] When both sets of LED loads 3 are working normally, the two fault detection modules 5 output a low level to the gate of the corresponding MOSFET Q3 in the MOSFET conversion circuit. Both MOSFETs Q3 are not conducting, and both output a high level to the anode of the corresponding diode D3. Both diodes D3 are conducting, and output a high level to the base of the NPN transistor Q2. The NPN transistor Q2 is conducting, and thus outputs a low level to the control terminal of the LED power module 2. The voltage output terminal of the LED power module 2 supplies power to the two sets of LED loads 3 normally.

[0046] When one set of LED loads 3 fails while the other set of LED loads 3 is functioning normally, the fault detection module 5 corresponding to the faulty set of LED loads 3 outputs a high level to the gate of MOSFET Q3, causing MOSFET Q3 to conduct. This outputs a low level to the anode of the corresponding diode D3, causing diode D3 to de-conduct. Conversely, the fault detection module 5 corresponding to the functioning set of LED loads 3 outputs a low level to the gate of MOSFET Q3, causing MOSFET Q3 to de-conduct. This outputs a high level to the anode of the corresponding diode D3, causing diode D3 to conduct. Therefore, a high level is output to the base of NPN transistor Q2, causing NPN transistor Q2 to conduct. This, in turn, outputs a low level to the control terminal of LED power module 2, allowing the voltage output of LED power module 2 to supply power normally to the set of LED loads 3 that did not fail.

[0047] When both sets of LED loads 3 fail, the fault detection module 5 corresponding to both sets of LED loads 3 outputs a high level to the gate of the corresponding MOSFET Q3. Both MOSFETs Q3 are turned on, and both output a low level to the anode of the corresponding diode D3. Both diodes D3 are not turned on, and output a low level to the base of the NPN transistor Q2. The NPN transistor Q2 is not turned on, and thus outputs a high level to the control terminal of the LED power module 2. The voltage output terminal of the LED power module 2 stops supplying power to the two sets of LED loads 3.

[0048] Therefore, when multiple LED loads 3 are used, since each LED load 3 is equipped with a separate fault detection module 5, it is possible to keep the LED loads 3 that have not failed lit even when not all LED loads 3 have failed. Moreover, the brightness of the LED loads 3 that have not failed can be improved by the thermal decay compensation module 7 in conjunction with the constant current drive module 4, so as to achieve the function of not reducing the overall brightness of the lamp.

[0049] As can be seen from the two examples above, the circuit in this embodiment, while meeting regulatory requirements, not only has excellent versatility and can directly match different needs, realizing a modular development approach, which can significantly shorten the development cycle and reduce development costs; but also, by adding a thermal decay compensation module 7, in conjunction with a constant current drive module 4, it can adaptively adjust the current magnitude according to the brightness fluctuations of the LED, so that the brightness of the lamp is not affected by the thermal decay of the LED; at the same time, without using DC-DC and driver chips, all functions are implemented entirely with discrete components, which reduces costs, makes the heat dissipation location extremely dispersed, reduces the difficulty of heat dissipation design, and reduces the cost of heat dissipation treatment. Furthermore, the number of LED loads is not limited by the chip channels and can be flexibly expanded according to needs, further reducing design difficulty and production costs.

[0050] Furthermore, power supply 1 is preferably connected to the voltage input terminal of LED power supply module 2 via anti-reverse filtering module 6. By adding anti-reverse filtering module 6, damage caused by reverse polarity connection of the power supply can be prevented, and electromagnetic interference in the power line can be filtered out, ensuring safe and stable operation of the equipment.

[0051] Example 2:

[0052] Please see Figure 2 and Figure 4 The main structure of this embodiment is exactly the same as that of embodiment 1, except that the on / off control module 8 is different.

[0053] The on / off control module 8 includes a decoding chip. Each input pin of the decoding chip is connected to the cathode of diode D1 and the cathode of diode D2 of each fault detection module 5, meaning that each fault detection module 5 independently corresponds to one input pin of the decoding chip. Simultaneously, the output pin of the decoding chip is connected to the control terminal of the LED power module 2, and the voltage input terminal of the decoding chip is connected to the voltage input terminal of the LED power module 2.

[0054] Taking a set of LED load 3 as an example, the LED load 3 is composed of multiple LEDs with positive and negative terminals connected in series. The positive terminal of the first LED is connected to the voltage output terminal of the LED power module 2, and the negative terminal of the last LED is connected to the negative input terminal of the first comparator IC1A, the positive input terminal of the second comparator IC1B, and the constant current drive module 4.

[0055] When all LEDs are working normally, the fault detection module 5 outputs a low level to the decoding chip, the decoding chip outputs a low level to the control terminal of the LED power supply module 2, and the voltage output terminal of the LED power supply module 2 supplies power to the LED load 3 normally.

[0056] When any one LED fails, the fault detection module 5 outputs a high level to the decoding chip, which in turn outputs a high level to the control terminal of the LED power supply module 2. The voltage output of the LED power supply module 2 then stops supplying power to the LED load 3. Therefore, this achieves the function of turning off all LEDs when one fails.

[0057] Taking a setup with two sets of LED loads 3 as an example, each set of LED loads 3 consists of one or more LEDs connected in series with positive and negative terminals. The positive terminals of the LEDs at the beginning of the set are all connected to the voltage output terminal of the LED power module 2, and the negative terminals of the LEDs at the end of the set are respectively connected to the negative input terminal of the first comparator IC1A, the positive input terminal of the second comparator IC1B, and the constant current drive module 4.

[0058] When both sets of LED loads 3 are working normally, the two fault detection modules 5 output a low level to the corresponding input pin of the decoding chip, the decoding chip outputs a low level to the control terminal of the LED power module 2, and the voltage output terminal of the LED power module 2 supplies power to the two sets of LED loads 3 normally.

[0059] When one set of LED loads 3 fails and the other set of LED loads 3 is normal, the set of LED loads 3 that fails outputs a high level to the corresponding input pin of the decoding chip; the set of LED loads 3 that is normal outputs a low level to the corresponding input pin of the decoding chip. Therefore, the decoding chip outputs a low level to the control terminal of the LED power module 2, and the voltage output terminal of the LED power module 2 supplies power to the set of LED loads 3 that has not failed.

[0060] When both sets of LED loads 3 fail, the fault detection modules 5 corresponding to the two sets of LED loads 3 output high level to the corresponding input pins of the decoding chip, and the decoding chip outputs high level to the control terminal of the LED power module 2. The voltage output terminal of the LED power module 2 stops supplying power to the two sets of LED loads 3.

[0061] In general, the decoding chip outputs a low level to the control terminal of the LED power module 2 as long as not all input pins are at a high level. The decoding chip only outputs a high level to the control terminal of the LED power module 2 when all input pins are at a high level.

[0062] Example 3:

[0063] like Figure 1 As shown, a method for adaptive brightness control of automotive LED lights based on the drive control circuit of Embodiment 1 or Embodiment 2 includes the following steps:

[0064] S1, Thermal decay compensation module 7 monitors the brightness of all LED loads 3:

[0065] If the brightness value detected by the thermal decay compensation module 7 is less than the minimum compliant value, it means that the brightness of the automotive LED light is less than the regulatory requirement, and then proceed to step S2;

[0066] If the brightness value detected by the thermal decay compensation module 7 is greater than the maximum compliant value, it means that the brightness of the automotive LED light is greater than the regulatory requirement, and then proceed to step S3;

[0067] If the brightness value detected by the thermal decay compensation module 7 is greater than or equal to the minimum compliant value and less than or equal to the maximum compliant value, it indicates that the brightness of the automotive LED lights meets the regulatory requirements, and then proceed to step S4.

[0068] S2. The constant current drive module 4 increases the current of each group of LED loads 3 according to the brightness value monitored by the thermal decay compensation module 7, and returns to step S1.

[0069] Specifically, when the light intensity received by photodiode D4 decreases, the transimpedance amplifier composed of the first operational amplifier IC2A will output an amplified voltage. This voltage is then amplified by the error amplifier composed of the second operational amplifier IC2B, and compared with the reference voltage, thus increasing the output voltage value. When the base current I of the PNP transistor Q4... B When the current increases, the collector current I of the PNP transistor Q4... C The current decreases, thereby reducing the base current I of the NPN transistor Q1. B This increases, and consequently increases the collector current I of the NPN transistor Q1. C The collector current I of NPN transistor Q1 C After the increase, the current of each LED load 3 increases, thereby improving the brightness of the LEDs and compensating for the decrease in brightness caused by LED thermal decay. After completion, return to step S1.

[0070] S3. The constant current drive module 4 reduces the current of each group of LED loads 3 according to the brightness value monitored by the thermal decay compensation module 7, and returns to step S1. Its specific working principle is the opposite of step S2, and will not be described in detail here.

[0071] S4. The on / off control module 8 monitors the output information of all fault detection modules 5: if not all fault detection modules 5 output fault information, proceed to step S5; if all fault detection modules 5 output fault information, proceed to step S6.

[0072] S5. The on / off control module 8 outputs a low level to the control terminal of the LED power module 2, the LED power module 2 supplies power to all LED loads 3, and returns to step S1.

[0073] S6, the on / off control module 8 outputs a high level to the control terminal of the LED power module 2, and the LED power module 2 stops supplying power to all LED loads 3.

[0074] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A brightness self-adaptive control method for vehicle LED lamp based on driving control circuit, characterized in that, The drive control circuit comprises a power supply, an LED power module, a constant current drive module, a thermal decay compensation module, an on-off control module, at least one group of LED loads, and a fault detection module corresponding to each LED load, respectively; the voltage input end of the LED power module is connected to the power supply; the constant current drive module, the thermal decay compensation module, the on-off control module, and each fault detection module are all connected to the voltage input end of the LED power module; the anode of each group of LED loads is connected to the voltage output end of the LED power module; the constant current drive module is further connected to the cathode of all LED loads; the thermal decay compensation module is connected to the constant current drive module and is adjacent to all LED loads; the input end of each fault detection module is connected to the cathode of the corresponding LED load; the output end of each fault detection module is connected to the input end of the on-off control module; and the output end of the on-off control module is connected to the control end of the LED power module. The brightness self-adaptive control method of the vehicle LED lamp comprises the following steps: S1, the thermal decay compensation module monitors the brightness of all LED loads: if the monitored brightness value is less than the compliance minimum value, step S2 is entered; if the monitored brightness value is greater than the compliance maximum value, step S3 is entered; if the monitored brightness value is greater than or equal to the compliance minimum value and less than or equal to the compliance maximum value, step S4 is entered; S2, the constant current drive module increases the current of each group of LED loads according to the brightness value monitored by the thermal decay compensation module, and returns to step S1; S3, the constant current drive module reduces the current of each group of LED loads according to the brightness value monitored by the thermal decay compensation module, and returns to step S1; S4, the on-off control module monitors the output information of all fault detection modules: if not all fault detection modules output fault information, step S5 is entered; if all fault detection modules output fault information, step S6 is entered; S5, the on-off control module outputs a low level to the control end of the LED power module, the LED power module supplies power to all LED loads, and returns to step S1; S6, the on-off control module outputs a high level to the control end of the LED power module, and the LED power module stops supplying power to all LED loads.

2. The method of claim 1, wherein, The fault detection module comprises a first comparator IC1A and a second comparator IC1B, the negative input end of the first comparator IC1A and the positive input end of the second comparator IC1B are connected to the negative pole of the corresponding LED load, the positive input end of the first comparator IC1A is connected to the common end of the corresponding resistor R7 and resistor R8, the negative input end of the second comparator IC1B is connected to the common end of the corresponding resistor R3 and resistor R4, the other end of the resistor R8 and the other end of the resistor R3 are connected to the voltage input end of the LED power module, the other end of the resistor R7 and the other end of the resistor R4 are connected to the ground, the output end of the first comparator IC1A and the output end of the second comparator IC1B are connected to the anode of the corresponding diode D2 and the anode of the diode D1 respectively, the common end of the first comparator IC1A and the diode D2 is connected to the voltage input end of the LED power module through the corresponding resistor R6, the common end of the second comparator IC1B and the diode D1 is connected to the voltage input end of the LED power module through the corresponding resistor R5, the cathode of the diode D2 and the cathode of the diode D1 are connected to the input end of the bright-out control module.

3. The method for adaptive control of brightness of LED lamp for vehicle according to claim 2, characterized in that, The bright-out control module comprises an NPN type triode Q2 and a MOS tube conversion circuit corresponding to each fault detection module, the collector of the NPN type triode Q2 is connected to the voltage input end of the LED power module through the resistor R9, the common end of the collector of the NPN type triode Q2 and the resistor R9 is connected to the control end of the LED power module, the emitter of the NPN type triode Q2 is connected to the ground, the base of the NPN type triode Q2 is connected to the ground through the resistor R10 and the resistor R11 in sequence, the MOS tube conversion circuit comprises a MOS tube Q3 and a diode D3, the gate of the MOS tube Q3 is connected to the cathode of the diode D1 and the cathode of the diode D2 of the corresponding fault detection module, the source of the MOS tube Q3 is connected to the ground, the drain of the MOS tube Q3 is connected to the voltage input end of the LED power module through the corresponding resistor R12, the anode of the diode D3 is connected to the common end of the drain of the corresponding MOS tube Q3 and the resistor R12, the cathodes of all diodes D3 are connected to the common end of the resistor R10 and the resistor R11.

4. The method of claim 2, wherein the step of controlling the brightness of the LED light is performed by a microcontroller. The bright-out control module comprises a decoding chip, each input pin of the decoding chip is connected to the cathode of the diode D1 and the cathode of the diode D2 of each fault detection module in sequence, the output pin of the decoding chip is connected to the control end of the LED power module, and the voltage input end of the decoding chip is connected to the voltage input end of the LED power module.

5. The method of claim 3 or 4, wherein the method further comprises: The LED load is provided with a group, which is composed of a plurality of LEDs connected in sequence in positive and negative poles, the positive pole of the LED at the head end is connected to the voltage output end of the LED power module, and the negative pole of the LED at the tail end is connected to the negative input end of the first comparator IC1A, the positive input end of the second comparator IC1B and the constant current driving module.

6. The method of claim 3 or 4, wherein The LED load is provided with at least two groups, each of which is composed of at least one LED connected in series with positive and negative poles, the positive pole of the first end LED of each group is connected to the voltage output end of the LED power module, and the negative pole of the tail end LED is connected to the negative input end of the corresponding first comparator IC1A, the positive input end of the second comparator IC1B and the constant current driving module respectively.

7. The method of claim 1, wherein the method further comprises: The constant current driving module comprises a voltage stabilizing diode D20 and NPN triodes Q1 with the collectors connected to the negative poles of the corresponding LED loads, the emitters of the NPN triodes Q1 are connected to the ground in series with the corresponding resistors R2, the bases of all the NPN triodes Q1 are connected to the negative pole of the voltage stabilizing diode D20 and the common end of the resistor R1, the other end of the resistor R1 is connected to the voltage output end of the LED power module, the reference pole of the voltage stabilizing diode D20 is connected to the emitter of any NPN triode Q1 and the common end of the corresponding resistor R2, and the positive pole of the voltage stabilizing diode D20 is connected to the ground.

8. The method of claim 7, wherein the step of determining the brightness of the LED light is performed by the microcontroller. The heat decay compensation module comprises a PNP type transistor Q4, a three-terminal adjustable shunt regulator D5, a first operational amplifier IC2A, a second operational amplifier IC2B and a photosensitive diode D4 close to all LED loads, the anode and cathode of the photosensitive diode D4 are connected to the reverse input end and same direction input end of the first operational amplifier IC2A respectively, a resistor R18 is connected between the reverse input end and same direction input end of the first operational amplifier IC2A, a capacitor C3 is also connected between the reverse input end and same direction input end of the first operational amplifier IC2A, the same direction input end of the first operational amplifier IC2A is grounded, a resistor R19 is connected between the reverse input end and output end of the first operational amplifier IC2A, a capacitor C1 is also connected between the reverse input end and output end of the first operational amplifier IC2A, the output end of the first operational amplifier IC2A is connected to the reverse input end of the second operational amplifier IC2B through a resistor R17, the positive power supply end of the first operational amplifier IC2A is connected to the voltage input end of the LED power module, the positive power supply end of the first operational amplifier IC2A is connected to the negative pole of the three-terminal adjustable shunt regulator D5 through a resistor R20, the positive pole of the three-terminal adjustable shunt regulator D5 is grounded, the negative pole of the three-terminal adjustable shunt regulator D5 is connected to the common end of the resistor R20, the common end of the resistor R21 and the resistor R22 in turn, and then grounded, the common end of the resistor R21 and the resistor R22 is connected to the reference voltage end of the three-terminal adjustable shunt regulator D5, the reference voltage end of the three-terminal adjustable shunt regulator D5 is connected to the same direction input end of the second operational amplifier IC2B through a resistor R23, the same direction input end of the second operational amplifier IC2B is connected to the common end of the resistor R23 and the resistor R24, and then grounded, a resistor R16 is connected between the reverse input end and output end of the second operational amplifier IC2B, a capacitor C2 is also connected between the reverse input end and output end of the second operational amplifier IC2B, the output end of the second operational amplifier IC2B is connected to the base of the PNP type transistor Q4 through a resistor R15, the base of the PNP type transistor Q4 is connected to the common end of the resistor R14 and the resistor R1 through the resistor R13, and then grounded, the emitter of the PNP type transistor Q4 is connected to the negative pole of the voltage stabilizing diode D20 and the common end of the resistor R1.

9. The method for adaptive control of brightness of LED lamp for vehicle according to claim 1, characterized in that, The power supply is connected to the voltage input end of the LED power module through the anti-reverse filtering module.

Images