Light control circuit, LED system and vehicle

Abstract

The utility model relates to the field of electronic circuits, and provides a light control circuit, an LED system and a vehicle. The light control circuit comprises a micro-control unit, a driving unit and a constant-current control resistor; the micro-control unit is connected with the driving unit and is used for providing a PWM signal for the driving unit; the driving unit is connected with the LED lamp and is used for controlling the LED lamp to be turned on or turned off according to the PWM signal; and the constant current control resistor is used for controlling the current flowing through the LED lamp to be constant when the LED lamp is lightened.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit field especially relates to a light control circuit, a LED system and a vehicle. BACKGROUND

[0002] In the related art, LED constant current driving chips are generally used to solve the problem of brightness change of LED lamps caused by input change of vehicle power supply. However, the use of LED constant current driving chips to control LED light circuit has high cost and complex circuit, and the cost performance is not high in actual production and manufacturing. Therefore, it is necessary to provide a relatively low-cost and simple control circuit to control the LED light. SUMMARY

[0003] The utility model aims at at least in a certain extent solves one of the technical problems in the related art. Therefore, the first purpose of the utility model is to provide a light control circuit, the micro control unit of light control circuit only needs to connect the simple electronic components such as conventional resistance and triode, that is, the current of light control circuit can be kept constant when working, the manufacturing cost of light control circuit is reduced, the problem that the brightness of LED changes due to input change of power supply is avoided, and the service life of LED is prolonged.

[0004] The second purpose of the utility model is to provide a LED system.

[0005] The third purpose of the utility model is to provide a vehicle.

[0006] To achieve the above purpose, the first aspect of the utility model provides a light control circuit, which comprises a micro control unit, a driving unit and a constant current control resistance. The micro control unit is connected with the driving unit and is used to provide a PWM signal for the driving unit. The driving unit is connected with the LED lamp and is used to control the lighting or extinguishing of the LED lamp according to the PWM signal. The constant current control resistance is used to control the constant current flowing through the LED lamp when the LED lamp is lit.

[0007] In addition, the light control circuit according to the above embodiment of the utility model can also have the following additional technical features:

[0008] According to some embodiments of the utility model, drive unit includes first switch unit, first switch unit includes first NPN pipe, first resistance and second resistance, the base of first NPN pipe is connected with the output of microcontrol unit, the collector of first NPN pipe is connected with constant voltage source, the emitter of first NPN pipe is grounded, first resistance is arranged between the base of first NPN pipe and microcontrol unit, second resistance is arranged between the base of first NPN pipe and the emitter of first NPN pipe, wherein, when PWM signal is high level, first switch unit is turned on, when PWM signal is low level, first switch unit is cut off.

[0009] According to some embodiments of the utility model, third resistance and fourth resistance are arranged between the collector of first NPN pipe and constant voltage source.

[0010] According to some embodiments of the utility model, drive unit still includes second switch unit, second switch unit includes second PNP pipe, third resistance and fourth resistance, the base of second PNP pipe is connected with the collector of first NPN pipe, the collector of second PNP pipe is grounded, the emitter of second PNP pipe is connected with constant voltage source, third resistance is arranged between the base of second PNP pipe and constant voltage source, fourth resistance is arranged between the base of second PNP pipe and the collector of first NPN pipe, wherein, when first switch unit is turned on, constant voltage source provides on voltage for the base of second PNP pipe, and second PNP pipe is turned on.

[0011] According to some embodiments of the utility model, fifth resistance and sixth resistance are arranged between the collector of second PNP pipe and ground terminal.

[0012] According to some embodiments of the utility model, drive unit still includes third switch unit, third switch unit includes third NPN pipe, fifth resistance and sixth resistance, the base of third NPN pipe is connected with the collector of second PNP pipe, the collector of third NPN pipe is connected with the whole vehicle power supply of target vehicle, the emitter of third NPN pipe is grounded, fifth resistance is arranged between the base of third NPN pipe and the collector of second PNP pipe, sixth resistance is arranged between the base of third NPN pipe and the emitter of third NPN pipe, wherein, when second PNP pipe is turned on, the collector of second PNP pipe provides on voltage for the base of third NPN pipe, and third NPN pipe is turned on.

[0013] According to some embodiments of the utility model, LED lamp is arranged between the collector of third NPN pipe and the whole vehicle power supply of vehicle, the anode of LED lamp is connected with the input of whole vehicle power supply, and the cathode of LED lamp is connected with the collector of third NPN pipe.

[0014] According to some embodiments of the present application, the constant current control resistor is arranged between the emitter of the third NPN tube and the ground terminal.

[0015] According to the light control circuit, the micro control unit of the light control circuit only needs to be connected with conventional resistors and transistors and other electronic components, so that the current of the light control circuit can be kept constant during work, the manufacturing cost of the light control circuit is reduced, the problem that the brightness of the LED lamp changes due to the change of the power input is avoided, and the service life of the LED lamp is prolonged.

[0016] To achieve the above object, the second aspect of the present application provides an LED system, which comprises an LED lamp and a light control circuit.

[0017] To achieve the above object, the third aspect of the present application provides a vehicle, which comprises a vehicle power supply and an LED system.

[0018] The additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description.

[0020] Figure 1 The circuit diagram of the light control circuit provided by the embodiment of the present application.

[0021] Figure 2 The PWM signal schematic diagram provided by the embodiment of the present application.

[0022] Figure 3 The LED system structure schematic diagram provided by the present application.

[0023] Figure 4 The vehicle schematic diagram provided by the present application.

[0024] 10 - light control circuit; 300 - vehicle power supply; D1 - LED lamp; 100 - micro control unit; 200 - driving unit; 210 - first switch unit; 220 - second switch unit; 230 - third switch unit; Q1 - first NPN transistor; R1 - first resistor; R2 - second resistor; 11 - base of first NPN transistor; 12 - collector of first NPN transistor; 13 - emitter of first NPN transistor; Q2 - second PNP transistor; R3 - third resistor; R4 - fourth resistor; 21 - base of second PNP transistor; 22 - collector of second PNP transistor; 23 - emitter of second PNP transistor; Q3 - third NPN transistor; R5 - fifth resistor; R6 - sixth resistor; 31 - base of third NPN transistor; 32 - collector of third NPN transistor; 33 - emitter of third NPN transistor; R7 - constant current control resistor; 20 - LED system; 40 - vehicle. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with reference to the embodiments and the accompanying drawings.

[0026] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the common meanings by those skilled in the art. The terms "first", "second" and similar terms used in the present application do not indicate any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, without excluding other elements or objects. The terms "connect" or "connected" and similar terms do not mean physical or mechanical connection, but can include electrical connection, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to indicate relative positional relationship, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] As described in the background section, in order to ensure that the brightness of the LED lamp does not change with the input of the vehicle power supply, the LED constant current driving chip is generally used in the related art to control the LED light. This chip can control the current in the circuit to remain constant when the output voltage, inductance or input voltage changes, so as to keep the LED light constant. However, in actual application, the chip has high cost and complex design circuit, and the cost performance is low, which is not suitable for mass production.

[0028] The applicant finds that a conventional resistor and a triode can be used to build a control circuit without a chip during implementation of the utility model, and through three working states of the triode, constant current control of current flowing through the LED lamp is realized in combination with a control signal input by a micro control unit, so that the brightness of the LED lamp does not change when the input of the power supply of the whole vehicle changes, and meanwhile the brightness of the LED lamp light can be adjusted in combination with the characteristics of the PWM signal.

[0029] The technical scheme of the utility model will be further explained in detail through specific embodiments below.

[0030] Reference Figure 1 A circuit diagram of the light control circuit 10 provided by the utility model embodiment.

[0031] According to the light control circuit 10 provided by the utility model, the light control circuit 10 comprises a micro control unit 100, a driving unit 200 and a constant current control resistor R7. The micro control unit 100 is connected with the driving unit 200 and is used for providing a PWM signal for the driving unit 200; the driving unit 200 is connected with an LED lamp D1 and is used for controlling the lighting or extinguishing of the LED lamp D1 according to the PWM signal; and the constant current control resistor R7 is used for controlling the current flowing through the LED lamp D1 to be constant when the LED lamp D1 is lighted.

[0032] Specifically, one end of the micro control unit 100 (MCU) is connected with a constant voltage source VCC, and the other end is grounded, so that the control of the circuit can be realized through output of a PWM signal. The PWM signal is composed of a series of pulses, a clock signal with a fixed frequency is generated by an internal timer or a counter of the MCU, and then the clock signal is compared with a preset threshold value by using a logic circuit, so that the PWM signal is generated.

[0033] The driving unit 200 is composed of a triode and a resistor. In a cycle, when the PWM signal is at a high level, the driving unit 200 is turned on, and the LED lamp D1 is lighted; when the PWM signal is at a low level, the driving unit 200 is cut off, and the LED lamp D1 is extinguished, so that the LED lamp D1 is repeatedly controlled to be turned on and off. When the frequency of lighting and extinguishing of the LED lamp D1 exceeds 100 Hz, due to the visual persistence of the human eye, although the LED lamp D1 is actually lighted and extinguished continuously, the visual system of the human eye will average the rapidly changing light signal, so that the LED lamp D1 is perceived as constant brightness.

[0034] It should be noted that the voltage value of the constant voltage source VCC is generally 3.3V-5V, which can be set according to actual requirements.

[0035] ReferenceFigure 2 The PWM signal schematic diagram provided by the utility model embodiment.

[0036] It should be noted that the brightness of the LED lamp D1 can be adjusted by changing the duty cycle of the PWM signal. The duty cycle of the PWM signal is the ratio of the high level time to the whole cycle time in a pulse period, and the unit is % (0%~100%), for example, Figure 2 Figure 2 (a) represents a PWM signal with a 50% duty cycle, which means that the high level time accounts for 50% of the whole cycle, Figure 2 (a) represents a PWM signal with a 75% duty cycle, which means that the high level time accounts for 75% of the whole cycle.

[0037] By changing the duty cycle of the PWM signal, the effective voltage output can be adjusted. Under a fixed frequency, the greater the duty cycle, the higher the average voltage output, the greater the average current flowing through the LED lamp D1, and the brighter the LED lamp D1; the smaller the duty cycle, the lower the average voltage output, the smaller the average current flowing through the LED lamp D1, and the dimmer the LED lamp D1. Assuming that the duty cycle of the PWM signal is Ton, then the average current Iavg flowing through the LED lamp D1 in a pulse period can be represented as:

[0038] Iavg = ILED x Ton

[0039] ILED is the maximum current that can flow through the LED, and the value of the duty cycle Ton ranges from 0 to 1.

[0040] The constant current control resistor R7 is connected to the LED lamp D1 through the driving unit 200, which can control the current flowing through the LED lamp D1 to be consistent with the current flowing through the constant current control resistor R7, so that the current flowing through the LED lamp D1 remains constant when the input of the vehicle power supply 300 changes, thereby ensuring that the brightness of the LED lamp D1 remains unchanged.

[0041] As an optional embodiment, the driving unit 200 includes a first switching unit 210, which includes a first NPN transistor Q1, a first resistor R1, and a second resistor R2. The base 11 of the first NPN transistor is connected to the output of the micro control unit 100, the collector 12 of the first NPN transistor is connected to the constant voltage source VCC, and the emitter 13 of the first NPN transistor is grounded. The first resistor R1 is arranged between the base 11 of the first NPN transistor and the micro control unit 100, and the second resistor R2 is arranged between the base 11 of the first NPN transistor and the emitter 13 of the first NPN transistor. When the PWM signal is high, the first switching unit 210 is turned on, and when the PWM signal is low, the first switching unit 210 is turned off. ​

[0042] Specifically, the base 11 of the first NPN tube is connected with the output end of the micro control unit 100, for receiving the PWM signal sent by the control unit, the collector 12 of the first NPN tube is connected with the constant voltage source VCC, for providing the working voltage for the first NPN tube Q1, and the emitter 13 of the first NPN tube is grounded, for providing the low potential point for the first NPN tube Q1, so that the current can flow smoothly from the collector 12 to the emitter 13 of the first NPN tube, forming a complete current loop.

[0043] The first resistor R1 is arranged between the base 11 of the first NPN tube and the micro control unit 100, for limiting the current flowing through the base 11 of the first NPN tube, thereby protecting the first NPN tube Q1, and further guaranteeing the stability and reliability of the light control circuit 10; the emitter 13 of the first NPN tube and the base 11 of the first NPN tube are connected in parallel with the second resistor R2 to form a negative feedback loop, which can suppress the change of the current, thereby improving the stability of the light control circuit 10.

[0044] When the PWM signal is high, the voltage of the base 11 of the first NPN tube is high, the first NPN tube Q1 enters the saturation region, the internal resistance between the collector 12 and the emitter of the first NPN tube is minimum, the current of the collector 12 of the first NPN tube is large, and the output voltage is low, at this time, the first NPN tube Q1 can be regarded as the conduction state, allowing the current to pass through, and the first switch unit 210 is turned on; when the PWM signal is low, the voltage of the base 11 of the first NPN tube is low, the first NPN tube Q1 enters the cut-off region, the collector 12 and the emitter of the first NPN tube are equivalent to an open circuit, the current of the collector 12 of the first NPN tube is almost zero, and the output voltage is high, at this time, the first NPN tube Q1 can be regarded as the cut-off state, preventing the current from passing through, and the first switch unit 210 is cut off.

[0045] As an optional embodiment, the third resistor R3 and the fourth resistor R4 are arranged between the collector 12 of the first NPN tube and the constant voltage source VCC.

[0046] As an optional embodiment, the driving unit 200 further comprises a second switch unit 220, the second switch unit 220 comprising a second PNP tube Q2, a third resistor R3 and a fourth resistor R4; the base 21 of the second PNP tube is connected with the collector 12 of the first NPN tube, the collector 22 of the second PNP tube is grounded, and the emitter 23 of the second PNP tube is connected with the constant voltage source VCC; the third resistor R3 is arranged between the base 21 of the second PNP tube and the constant voltage source VCC, and the fourth resistor R4 is arranged between the base 21 of the second PNP tube and the collector 12 of the first NPN tube; wherein, when the first switch unit 210 is turned on, the constant voltage source VCC provides the base 21 of the second PNP tube with a turn-on voltage, and the second PNP tube Q2 is turned on.

[0047] Specifically, the base 21 of the second PNP tube is connected with the collector 12 of the first NPN tube, and the base 21 of the second PNP tube is further connected with the constant voltage source VCC through the third resistor R3; the current output by the constant voltage source VCC can flow through the third resistor R3 and further flow through the fourth resistor R4 to the collector 12 of the first NPN tube. The emitter 23 of the second PNP tube is connected with the constant voltage source VCC, and the current output by the constant voltage source VCC can also flow through the emitter 23 of the second PNP tube to the base 21 of the second PNP tube and the collector 22 of the second PNP tube. The collector 22 of the second PNP tube is grounded, which provides a low potential point for the second PNP tube Q2, so that the current can smoothly flow from the emitter 23 of the second PNP tube to the collector 22 of the second PNP tube, forming a complete current loop.

[0048] The fourth resistor R4 is arranged between the collector 12 of the first NPN tube and the base 21 of the second PNP tube, for shunting the current flowing through the base 21 of the second PNP tube, thereby protecting the second PNP tube Q2 and further ensuring the stability and reliability of the light control circuit 10; the emitter 23 of the second PNP tube and the base 21 of the second PNP tube are connected in parallel with the third resistor R3 to form a negative feedback loop, which can suppress the change of the current, thereby improving the stability of the light control circuit 10.

[0049] When the first switch unit 210 is turned on, the current of the base 21 of the second PNP tube can flow to the collector 12 of the first NPN tube, at this time the second switch unit 220 is turned on; when the first switch unit 210 is turned off, the current of the base 21 of the second PNP tube flows to the collector 12 of the first NPN tube to be turned off, at this time the second switch unit 220 is turned off.

[0050] As an optional embodiment, the fifth resistor R5 and the sixth resistor R6 are arranged between the collector 22 of the second PNP tube and the ground end.

[0051] As an optional embodiment, the driving unit 200 further comprises a third switching unit 230, the third switching unit 230 comprising a third NPN tube Q3, a fifth resistor R5 and a sixth resistor R6; the base 31 of the third NPN tube is connected with the collector 22 of the second PNP tube, the collector 32 of the third NPN tube is connected with the vehicle power supply 300 of the target vehicle, and the emitter 33 of the third NPN tube is grounded; the fifth resistor R5 is arranged between the base 31 of the third NPN tube and the collector 22 of the second PNP tube, and the sixth resistor R6 is arranged between the base 31 of the third NPN tube and the emitter 33 of the third NPN tube; wherein when the second PNP tube Q2 is turned on, the collector 22 of the second PNP tube provides a turn-on voltage for the base 31 of the third NPN tube, and the third NPN tube Q3 is turned on.

[0052] Specifically, the base 31 of the third NPN tube is connected with the collector 22 of the second PNP tube for receiving the current transmitted by the second PNP tube Q2. The collector 32 of the third NPN tube is connected with the vehicle power supply 300 of the target vehicle for receiving the input current provided by the vehicle power supply 300. The emitter 33 of the third NPN tube is grounded, which provides a low potential point for the third NPN tube Q3, so that the current can smoothly flow from the collector 32 of the third NPN tube to the emitter 33 of the third NPN tube, forming a complete current loop.

[0053] The fifth resistor R5 is arranged between the base 31 of the third NPN tube and the collector 22 of the second PNP tube for shunting the current flowing through the collector 32 of the third NPN tube, thereby protecting the third NPN tube Q3 and further ensuring the stability and reliability of the light control circuit 10; the emitter 33 of the third NPN tube and the base 31 of the third NPN tube are connected in parallel with the sixth resistor R6 to form a negative feedback loop, which can suppress the change of the current, thereby improving the stability of the light control circuit 10.

[0054] When the second switching unit 220 is turned on, the current of the collector 22 of the second PNP tube can flow to the base 31 of the third NPN tube, at which time the third switching unit 230 is turned on; when the second switching unit 220 is turned off, the current of the collector 22 of the second PNP tube is cut off to the base 31 of the third NPN tube, at which time the third switching unit 230 is turned off.

[0055] As an optional embodiment, the collector 32 of the third NPN tube is connected with the vehicle power supply 300; the anode of the LED lamp D1 is connected with the input end of the vehicle power supply 300, and the cathode of the LED lamp D1 is connected with the collector 32 of the third NPN tube.

[0056] As an optional embodiment, the constant current control resistor R7 is arranged between the emitter 33 of the third NPN tube and the ground end.

[0057] Specifically, when the third switch unit 230 is turned on, the current can be input from the vehicle power supply 300 input end to the anode of the LED lamp D1, flow to the collector 32 of the third NPN tube, further flow to the emitter 33 of the third NPN tube, and flow through the constant current control resistor R7 to the ground end.

[0058] Since the constant current control resistor R7 is connected with the emitter 33 of the third NPN tube, at this time, the LED lamp D1, the third NPN tube Q3 and the constant current control resistor R7 are connected in series. When the voltage of the vehicle power supply 300 input end changes, since the voltage of the constant voltage source VCC connected with the second PNP tube Q2 does not change, the voltage of the collector 22 of the second PNP tube, the fifth resistor R5 and the base 31 of the third NPN tube does not change, further, the voltage of the emitter 33 of the third NPN tube also does not change, that is, the current flowing through the constant current control resistor R7 does not change, therefore, the current value of the LED lamp D1, the third NPN tube Q3 and the constant current control resistor R7 connected in series does not change, that is, the brightness of the LED lamp D1 does not change, thereby realizing the function that when the vehicle power supply 300 input changes, the LED lamp D1 can be ensured not to be disturbed and the brightness remains unchanged.

[0059] It should be noted that the current flowing through the constant current control resistor R7 needs to be not greater than the breakdown current of the LED lamp D1.

[0060] As can be seen from the above, the light control circuit provided by the utility model, including micro control unit, drive unit and constant current control resistor, micro control unit is connected with drive unit, be used for providing PWM signal for drive unit, drive unit is connected with LED lamp, be used for according to PWM signal control LED lamp's lightening or extinguishing, constant current control resistor is used for controlling the current flowing through the LED lamp constant when the LED lamp lights up. The drive unit is composed of the switch unit formed by the triode and the resistor, and the on-off of the light control circuit is controlled according to the pulse signal output by the micro control unit, and the constant current control resistor is arranged on the light control circuit, so that the current of the light control circuit can be kept constant when working, the manufacturing cost of the light control circuit is reduced, and the problem that the brightness of the LED changes due to the change of the power input is avoided, and the service life of the LED is prolonged.

[0061] Based on the same utility model concept, corresponding to the light control circuit 10 provided by any of the above embodiments, the utility model further provides an LED system 20, which comprises an LED lamp D1 and a light control circuit 10, and the LED lamp D1 is connected with the light control circuit 10.

[0062] The LED system provided by the utility model, the switch unit is composed of the triode and the resistance, the on-off of the light control circuit is controlled according to the pulse signal outputted by the micro control unit, and the constant current control resistance is arranged on the light control circuit, so that the current of the light control circuit can be kept constant when working, the manufacturing cost of the light control circuit is reduced, the problem that the brightness of the LED lamp changes due to the change of power input is avoided, and the service life of the LED is prolonged.

[0063] Based on the same utility model concept, the utility model also provides a vehicle 40 corresponding to the LED system 20 provided by any of the above embodiments, the vehicle 40 includes a vehicle power supply 300 and the LED system 20, and the vehicle power supply 300 is connected with the LED system 20.

[0064] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the utility model should be understood as the usual meaning understood by the person skilled in the art to which the utility model belongs. The "first", "second" and similar words used in the embodiments of the utility model do not represent any order, quantity or importance, but are only used to distinguish different components. "Include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connection" or "connection" and similar words are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent the relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0065] Although the spirit and principles of the utility model have been described with reference to several specific embodiments, it should be understood that the utility model is not limited to the disclosed specific embodiments, and the division of aspects does not mean that the features in these aspects cannot be combined for benefit, but only for the convenience of expression. The utility model is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the appended claims. The scope of the appended claims is the broadest interpretation, so as to include all such modifications and equivalent structures and functions.

Claims

1. A light control circuit, characterized by, The micro control unit (100), the driving unit (200) and the constant current control resistance (R7) are connected; The micro control unit (100) is connected with the driving unit (200), and is used for providing a PWM signal for the driving unit (200); The driving unit (200) is connected with the LED lamp (D1), and is used for controlling the lighting or extinguishing of the LED lamp (D1) according to the PWM signal; The constant current control resistance (R7) is used for controlling the current flowing through the LED lamp (D1) to be constant when the LED lamp (D1) is lighted.

2. The light control circuit of claim 1, wherein, The driving unit (200) comprises a first switch unit (210), and the first switch unit (210) comprises a first NPN tube (Q1), a first resistance (R1) and a second resistance (R2). The base (11) of the first NPN tube is connected with the output end of the micro control unit (100), the collector (12) of the first NPN tube is connected with a constant voltage source, and the emitter (13) of the first NPN tube is grounded; the first resistance (R1) is arranged between the base (11) of the first NPN tube and the micro control unit (100), and the second resistance (R2) is arranged between the base (11) of the first NPN tube and the emitter (13) of the first NPN tube; wherein when the PWM signal is high level, the first switch unit (210) is turned on, and when the PWM signal is low level, the first switch unit (210) is turned off.

3. The light control circuit of claim 2, wherein, The third resistance (R3) and the fourth resistance (R4) are arranged between the collector (12) of the first NPN tube and the constant voltage source.

4. The light control circuit of claim 3, wherein, The driving unit (200) further comprises a second switch unit (220), and the second switch unit (220) comprises a second PNP tube (Q2), the third resistance (R3) and the fourth resistance (R4). The base (21) of the second PNP tube is connected with the collector (12) of the first NPN tube, the collector (22) of the second PNP tube is grounded, and the emitter (23) of the second PNP tube is connected with the constant voltage source; the third resistance (R3) is arranged between the base (21) of the second PNP tube and the constant voltage source, and the fourth resistance (R4) is arranged between the base (21) of the second PNP tube and the collector (12) of the first NPN tube; wherein when the first switch unit (210) is turned on, the constant voltage source provides a turn-on voltage for the base (21) of the second PNP tube, and the second PNP tube (Q2) is turned on.

5. The light control circuit of claim 4, wherein, The fifth resistance (R5) and the sixth resistance (R6) are arranged between the collector (22) of the second PNP tube and the ground end.

6. The light control circuit of claim 5, wherein, The driving unit (200) further comprises a third switch unit (230), and the third switch unit (230) comprises a third NPN tube (Q3), the fifth resistance (R5) and the sixth resistance (R6). The base electrode (31) of the third NPN transistor is connected with the collector electrode (22) of the second PNP transistor, the collector electrode (32) of the third NPN transistor is connected with the vehicle power supply (300) of the target vehicle, and the emitter electrode (33) of the third NPN transistor is grounded; the fifth resistor (R5) is arranged between the base electrode (31) of the third NPN transistor and the collector electrode (22) of the second PNP transistor, and the sixth resistor (R6) is arranged between the base electrode (31) of the third NPN transistor and the emitter electrode (33) of the third NPN transistor; when the second PNP transistor (Q2) is turned on, the collector electrode (22) of the second PNP transistor provides the base electrode (31) of the third NPN transistor with a turn-on voltage, and the third NPN transistor (Q3) is turned on.

7. The light control circuit of claim 6, wherein, The LED lamp (D1) is arranged between the collector electrode (32) of the third NPN transistor and the vehicle power supply (300); the anode of the LED lamp (D1) is connected with the input end of the vehicle power supply (300), and the cathode of the LED lamp (D1) is connected with the collector electrode (32) of the third NPN transistor.

8. The light control circuit of claim 6, wherein, The constant current control resistor (R7) is arranged between the emitter electrode (33) of the third NPN transistor and the ground end.

9. An LED system, characterized by The LED system (20) comprises an LED lamp (D1) and a light control circuit (10) as claimed in any one of claims 1 to 8, and the LED lamp (D1) is connected with the light control circuit (10).

10. A vehicle characterized by comprising: The LED system (20) comprises a vehicle power supply (300) and a light control circuit (10) as claimed in claim 9, and the vehicle power supply (300) is connected with the light control circuit (10).

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