Protect circuits and lights

Abstract

The present invention relates to a protection circuit and a vehicle lamp, comprising: an LED stepping position module, comprising a stepping position resistor connected to a main circuit, wherein when the stepping position resistor is operating normally, the protection circuit provides a first control current to the main circuit; an open circuit protection module, connected to the main circuit and the stepping position resistor, the open circuit protection module is used to detect whether the stepping position resistor is open circuited, and when the stepping position resistor is open circuited, the second control current is provided to the main circuit, and the second control current is less than the first control current; and a short circuit protection module, wherein the stepping position resistor is connected to the main circuit through the short circuit protection module, the short circuit protection module is used to detect whether the stepping position resistor is short circuited, and when the stepping position resistor is short circuited, the connection between the stepping position resistor and the main circuit is disconnected. The above protection circuit and vehicle lamp can keep the LED on and reduce the brightness when the stepping position resistor is open circuit fault or short circuit fault, thereby ensuring the safety of nighttime driving and giving the driver a fault warning.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle lamp control, and in particular to a protection circuit and a vehicle lamp. Background Art

[0002] The car lights include an LED light board and an LDM (constant current control module for LED lighting and signal lights) that controls the LED on the LED light board for display. Usually, the corresponding step resistor Rbin is set on the LED light board according to the power demand of the LED to control the display brightness level of the LED. When the LED is connected to the LDM, the LDM will read the voltage or current value on the step resistor Rbin on the LED light board to determine the magnitude of the current output by the LDM to the LED light board. Since the step resistor Rbin is installed on the LED light board and the detection circuit of the step resistor Rbin is located in the LDM, the two need to be connected through a connector and a wiring harness to work. However, inside the car body, the connector will have poor contact, and the wiring harness will also have the risk of short-circuiting to the ground, causing the step resistor Rbin to be open or short-circuited to the ground.

[0003] The types of LDM's perception and actions on the step resistor Rbin include: the larger the step resistor Rbin, the smaller the output power, the smaller the step resistor Rbin, the greater the output power, that is, the size of the step resistor Rbin is inversely proportional to the output power. Therefore, when the step resistor Rbin is open, the LDM has no output, so that the LED goes out; when the step resistor Rbin is short-circuited to the ground, the LDM will output overpower, causing the LED to overheat and burn. For nighttime driving, the sudden shutdown of lighting and signal lights will cause great safety problems. Summary of the invention

[0004] Based on this, it is necessary to provide a protection circuit and car light to address the problem in traditional technology that when the size of the dividing resistor Rbin is inversely proportional to the output power of the LDM, the open circuit and short circuit failure of the dividing resistor Rbin to the ground will make the LED unable to display, thus posing a threat to the driver's safety.

[0005] A protection circuit, comprising:

[0006] The LED stepping module comprises a stepping resistor connected to the main circuit, and when the stepping resistor works normally, the protection circuit provides a first control current for the main circuit;

[0007] an open circuit protection module connected to the main circuit and the step resistor, the open circuit protection module being used to detect whether the step resistor is open circuited, and to provide a second control current for the main circuit when the step resistor is open circuited, the second control current being smaller than the first control current; and

[0008] A short-circuit protection module, wherein the step-level resistor is connected to the main circuit via the short-circuit protection module, and the short-circuit protection module is used to detect whether the step-level resistor is short-circuited, and to disconnect the step-level resistor from the main circuit when the step-level resistor is short-circuited.

[0009] In one embodiment, the LED stepping module further includes a first voltage-dividing resistor, the first voltage-dividing resistor and the stepping resistor are sequentially connected in series between a power supply and a ground terminal, and the main circuit is connected between the first voltage-dividing resistor and the stepping resistor.

[0010] In one embodiment, the open circuit protection module includes an open circuit protection resistor connected in parallel to both ends of the step resistor.

[0011] In one embodiment, the short circuit protection module includes:

[0012] a short-circuit detection unit connected to the step-by-step resistor, the short-circuit detection unit being used to detect whether the step-by-step resistor is short-circuited, and outputting a conduction signal when the step-by-step resistor is short-circuited; and

[0013] A short-circuit switch unit, wherein the first electrical connection end of the short-circuit switch unit is connected to the main circuit, the second electrical connection end of the short-circuit switch unit is connected to the step-position resistor, the control end of the short-circuit switch unit is connected to the short-circuit detection unit, and after the control end of the short-circuit switch unit receives the conduction signal, the first electrical connection end of the short-circuit switch unit and the second electrical connection end of the short-circuit switch unit are conductively connected.

[0014] In one embodiment, the short circuit detection unit includes a comparator and a voltage divider unit, the voltage divider unit is used to provide a comparison voltage for the comparator, the same-direction input terminal of the comparator is connected to the step resistor, the reverse input terminal of the comparator is connected to the voltage divider unit, and the output terminal of the comparator is connected to the short circuit switch unit.

[0015] In one embodiment, the comparator includes an operational amplifier and a pull-up resistor, the same-direction input terminal of the operational amplifier is connected to the step resistor, the reverse input terminal of the operational amplifier is connected to the voltage divider unit, the output terminal of the operational amplifier is connected to the short-circuit switch unit, and the output terminal of the operational amplifier is also connected to the power supply through the pull-up resistor.

[0016] In one of the embodiments, the short-circuit switch unit includes a transistor, the collector of the transistor is connected to the main circuit, the emitter of the transistor is connected to the step resistor, and the base of the transistor is connected to the short-circuit detection unit.

[0017] In one of the embodiments, a short-circuit self-recovery module is further included, which is connected to the step-by-step resistor and the short-circuit protection module. The short-circuit self-recovery module is used to detect whether the short-circuit fault of the step-by-step resistor is restored after the short-circuit protection module detects that the step-by-step resistor is short-circuited, and after the short-circuit fault of the step-by-step resistor is restored, control the reconnection between the step-by-step resistor and the main circuit through the short-circuit protection module.

[0018] In one embodiment, the short-circuit self-recovery module includes a self-recovery switch unit and a fourth voltage-dividing resistor, the first electrical connection end of the self-recovery switch unit is connected to the power supply, the second electrical connection end of the self-recovery switch unit is connected to the step-position resistor through the fourth voltage-dividing resistor, and the control end of the self-recovery switch unit is connected to the short-circuit protection module.

[0019] In one embodiment, a short circuit self-recovery module is also included; the short circuit protection module includes:

[0020] a short circuit detection unit connected to the step resistor, the short circuit detection unit being used to detect whether the step resistor is short-circuited, outputting a first connection signal when the step resistor is operating normally and outputting a second connection signal when the step resistor is short-circuited; and

[0021] A short-circuit selection unit, wherein the first electrical connection end of the short-circuit selection unit is connected to the main circuit, the second electrical connection end of the short-circuit selection unit is connected to the short-circuit self-recovery module, the third electrical connection end of the short-circuit selection unit is connected to the gear-shift resistor, and the control end of the short-circuit switch unit is connected to the short-circuit detection unit; after the control end of the short-circuit selection unit receives the first connection signal, the third electrical connection end of the short-circuit selection unit and the first electrical connection end of the short-circuit selection unit are connected and the third electrical connection end of the short-circuit selection unit and the second electrical connection end of the short-circuit selection unit are disconnected; after the control end of the short-circuit selection unit receives the second connection signal, the third electrical connection end of the short-circuit selection unit and the second electrical connection end of the short-circuit selection unit are connected, the short-circuit self-recovery module supplies power to the branch where the gear-shift resistor is located, and the third electrical connection end of the short-circuit selection unit and the first electrical connection end of the short-circuit selection unit are disconnected.

[0022] A vehicle lamp comprises a main circuit, an LED, an LED lamp board and a protective short circuit as described in any of the above items, wherein the LED and the step-position resistors are both arranged on the LED lamp board, and the main circuit is also connected to the LED, and the main circuit is used to control the LED for display according to the first control current or the second control current provided by the protection circuit.

[0023] The above-mentioned protection circuit and car light provide a first control current to the main circuit when the step-position resistor is working normally, and the main circuit controls the display brightness level of the LED in the LED light board according to the first control current; when the step-position resistor is open-circuited, the open-circuit protection module provides a second control current to the main circuit, and the main circuit controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced compared to when the step-position resistor is working normally; when the step-position resistor is short-circuited, the short-circuit protection module disconnects the connection between the step-position resistor and the main circuit, and then the open-circuit protection module provides a second control current to the main circuit, and the main circuit controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced compared to when the step-position resistor is working normally. When the step-position resistor is open-circuited or short-circuited, the LED can continue to display and the brightness can be reduced, thereby ensuring the safety of night driving and giving the driver a fault warning. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 FIG. 4 is a structural block diagram of a protection circuit in an embodiment.

[0025] Figure 2 FIG. 4 is a circuit diagram of a protection circuit in an embodiment.

[0026] Figure 3 FIG. 4 is a circuit diagram of a protection circuit in another embodiment. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] In the description of the present application, it should be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, it should be noted that when an element is referred to as being "formed on another element", it may be directly connected to the other element or there may be a centered element at the same time. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centered element at the same time. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element.

[0029] Figure 1 FIG. 1 is a structural block diagram of a protection circuit in an embodiment. Figure 1 As shown, the protection circuit includes an LED stepping module 110 , an open circuit protection module 120 and a short circuit protection module 130 .

[0030] The LED step module 110 includes a step resistor ( Figure 1 (not shown). When the step resistors work normally, the protection circuit provides the first control current to the main circuit 200. The main circuit 200 is a circuit for constant current control of LEDs in the LDM, and the main circuit 200 controls the display brightness level of the LEDs in the LED light board according to the first control current.

[0031] The open circuit protection module 120 is connected to the main circuit 200 and the step resistor, and the open circuit protection module 120 is used to detect whether the step resistor is open. For example, the step resistor is detected by detecting the voltage across the step resistor, the resistance size, etc. When the step resistor is open, the open circuit protection module 120 provides a second control current to the main circuit 200, and the second control current is less than the first control current. At this time, the main circuit 200 controls the display brightness level of the LED in the LED light board according to the second control current, and because the second control current is less than the first control current, the display brightness of the LED decreases.

[0032] The step resistor is connected to the main circuit 200 through the short-circuit protection module 130. The short-circuit protection module 130 is used to detect whether the step resistor is short-circuited, for example, by detecting the voltage across the step resistor, the resistance, etc. to detect whether the step resistor is short-circuited to the ground. The short-circuit protection module 130 disconnects the connection between the step resistor and the main circuit 200 when the step resistor is short-circuited. At this time, the open-circuit protection module 120 provides the main circuit 200 with a second control current. The main circuit 200 controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the display brightness of the LED decreases.

[0033] The above-mentioned protection circuit provides a first control current to the main circuit 200 when the step resistor is working normally, and the main circuit 200 controls the display brightness level of the LED in the LED light board according to the first control current; when the step resistor is open-circuited, the open-circuit protection module 120 provides a second control current to the main circuit 200, and the main circuit 200 controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced relative to when the step resistor is working normally; when the step resistor is short-circuited, the short-circuit protection module 130 disconnects the connection between the step resistor and the main circuit 200, and then the open-circuit protection module 120 provides a second control current to the main circuit 200, and the main circuit 200 controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced relative to when the step resistor is working normally, so that when the step resistor is open-circuited or short-circuited, the LED can continue to display and reduce the brightness, thereby ensuring the safety of night driving and giving the driver a fault warning.

[0034] Figure 2 FIG. 1 is a circuit diagram of a protection circuit in an embodiment. Figure 2 As shown, the LED level module 110 includes a first voltage-dividing resistor R1 and a level-dividing resistor Rbin, which are connected in series between a power supply and a ground terminal, and the main circuit 200 is connected between the first voltage-dividing resistor R1 and the level-dividing resistor Rbin.

[0035] In one embodiment, the open circuit protection module 120 includes an open circuit protection resistor R2 connected in parallel to both ends of the step resistor Rbin. When the step resistor Rbin is working normally, the resistance value between the M point and the ground terminal is equal to the resistance value of the step resistor Rbin and the open circuit protection resistor R2 connected in parallel, and the current flowing from the M point into the main circuit 200 is the first control current. When the step resistor Rbin has an open circuit fault, the resistance value between the M point and the ground terminal is equal to the resistance value of the open circuit protection resistor R2, and the resistance value between the M point and the ground terminal increases compared to the normal working of the step resistor Rbin, so that the current flowing from the M point into the main circuit 200 at this time, that is, the second control current, is less than the first control current, so that the LED display brightness is reduced.

[0036] In other embodiments, the open circuit protection module 120 includes an open circuit detection unit, an open circuit switch unit, and a second control current generating unit. The open circuit detection unit is connected to the step resistor and is used to detect whether the step resistor Rbin is open circuit. The open circuit switch unit is connected between the main circuit 200 and the second control current generating unit. When the step resistor Rbin works normally, the open circuit switch unit disconnects the connection between the main circuit 200 and the second control current generating unit, and the resistance value between the M point and the ground terminal is equal to the resistance value of the step resistor Rbin, and the first control current is input from the M point to the main circuit 200. When the step resistor Rbin fails to open circuit, the open circuit switch unit controls the conduction between the main circuit 200 and the second control current generating unit, and the second control current output by the second control current generating unit is input from the M point to the main circuit 200.

[0037] In one embodiment, the short circuit protection module 130 includes a short circuit detection unit and a short circuit switch unit. The short circuit detection unit is connected to the step resistor, and the short circuit detection unit is used to detect whether the step resistor is short-circuited, and output a conduction signal when the step resistor is short-circuited. The first electrical connection end of the short circuit switch unit is connected to the main circuit 200, the second electrical connection end of the short circuit switch unit is connected to the step resistor, and the control end of the short circuit switch unit is connected to the short circuit detection unit. After the control end of the short circuit switch unit receives the conduction signal, the first electrical connection end of the short circuit switch unit and the second electrical connection end of the short circuit switch unit are connected.

[0038] Exemplarily, the short circuit detection unit includes a comparator and a voltage divider unit. The voltage divider unit is used to provide a comparison voltage for the comparator. The same-direction input terminal of the comparator is connected to the dividing resistor Rbin, the reverse input terminal of the comparator is connected to the voltage divider unit, and the output terminal of the comparator is connected to the short circuit switch unit.

[0039] Specifically, the comparator includes an operational amplifier U1 and a pull-up resistor R9. The same-direction input terminal of the operational amplifier U1 is connected to the step resistor Rbin, the reverse input terminal of the operational amplifier U1 is connected to the voltage divider unit, the output terminal of the operational amplifier U1 is connected to the short-circuit switch unit, and the output terminal of the operational amplifier U1 is also connected to the power supply through the pull-up resistor R9. The voltage divider unit includes a second voltage divider resistor R6 and a third voltage divider resistor R7 connected in series between the power supply and the ground terminal, and the reverse input terminal of the operational amplifier U1 is connected between the second voltage divider resistor R6 and the third voltage divider resistor R7 so ​​that the voltage at point L is the reference voltage Vth. The short-circuit switch unit includes a transistor Q1. The collector of the transistor Q1 is connected to the main circuit 200, the emitter of the transistor Q1 is connected to the step resistor Rbin, and the base of the transistor Q1 is connected to the output terminal of the operational amplifier U1 in the short-circuit detection unit.

[0040] The comparator compares the voltage input at the same direction input terminal, i.e., the voltage at point N, with the voltage Vth at the reverse input terminal. When the step resistor Rbin works normally, the voltage at point N is Vbin>Vth>Vgnd, where Vgnd is the voltage at the ground terminal. The output terminal of the comparator outputs a high level, the collector and emitter of the transistor Q1 are connected, the step resistor Rbin is connected to the circuit and works normally, and the main circuit 200 controls the LED to display according to the first control current. When the step resistor Rbin is short-circuited to the ground, the voltage at point N is Vbin=Vgnd<Vth, where Vgnd is the voltage at the ground terminal. The output terminal of the comparator outputs a low level, the collector and emitter of the transistor Q1 are disconnected, and the step resistor Rbin is disconnected from the main circuit 200. At this time, the open circuit protection module 120 detects that the step resistor Rbin is open, and provides the second control current to the main circuit 200. The main circuit 200 controls the LED to display according to the second control current, and the LED display brightness is reduced.

[0041] In one embodiment, the protection circuit further includes a short-circuit self-recovery module 140. The short-circuit self-recovery module 140 is connected to the step resistor and the short-circuit protection module 130. The short-circuit self-recovery module 140 is used to detect whether the short-circuit fault of the step resistor Rbin is restored after the short-circuit protection module 130 detects that the step resistor Rbin is short-circuited, and after the short-circuit fault of the step resistor Rbin is restored, the short-circuit protection module 130 controls the step resistor Rbin and the main circuit 200 to be reconnected, so that the main circuit 200 still controls the LED to display normally according to the first control current after the short-circuit fault of the step resistor Rbin is restored.

[0042] Exemplarily, the short-circuit self-recovery module 140 includes a self-recovery switch unit and a fourth voltage-dividing resistor R4. The first electrical connection end of the self-recovery switch unit is connected to the power supply, the second electrical connection end of the self-recovery switch unit is connected to the step resistor Rbin through the fourth voltage-dividing resistor R4, and the control end of the self-recovery switch unit is connected to the short-circuit protection module 130. The self-recovery switch unit may include a transistor Q2 and a pull-up resistor R8. The collector of the transistor Q2 is connected to the step resistor Rbin through the fourth voltage-dividing resistor R4, the emitter of the transistor Q2 is connected to the power supply, and the base of the transistor Q2 is connected to the power supply through the pull-up resistor R8 and is connected to the output end of the operational amplifier U1.

[0043] When the step resistor Rbin is short-circuited, the comparator outputs a low level, the transistor Q2 is turned on, and the power supply supplies power to the step resistor Rbin through the transistor Q2 and the fourth voltage-dividing resistor R4. When the short-circuit fault of the step resistor Rbin has not been restored, the voltage Vbin at point N is still equal to the voltage Vgnd at the ground terminal, the comparator still outputs a low level, and the transistor Q1 is still in the off state for short-circuit protection. When the step resistor Rbin returns to normal, the addition of the transistor Q2 and the fourth voltage-dividing resistor R4 will make the voltage Vbin at point N higher than the reference voltage Vth at point L again, the comparator flips to output a high level, the transistor Q1 is turned on, the step resistor Rbin is reconnected to the main circuit 200 for normal operation, and at the same time the transistor Q2 is turned off, and the transistor Q2 and the fourth voltage-dividing resistor R4 no longer affect the step resistor Rbin. In addition, when the circuit is powered on, since the transistor Q1 is not turned on, the dividing resistor Rbin cannot be normally connected, resulting in the circuit not starting. Therefore, the circuit corresponding to the transistor Q2 and the fourth voltage-dividing resistor R4 can still ensure that the circuit starts normally when powered on.

[0044] Figure 3 FIG. 2 is a circuit diagram of a protection circuit in another embodiment. Figure 3 As shown, the protection circuit includes not only the LED stepping module 110 and the open circuit protection module 120 , but also a short circuit protection module 150 and a short circuit self-recovery module 160 .

[0045] The short circuit protection module 150 includes a short circuit detection unit and a short circuit selection unit. The short circuit selection unit can be a two-choice switch S1 such as an electrically controlled mechanical switch or an electronic switch. The short circuit detection unit is connected to the step resistor Rbin. The short circuit detection unit is used to detect whether the step resistor Rbin is short-circuited. When the step resistor Rbin is operating normally, the short circuit detection unit outputs a first connection signal and when the step resistor Rbin is short-circuited, the short circuit detection unit outputs a second connection signal. The circuit structure of the short circuit detection unit in this embodiment can be the same as Figure 2 The circuit structure of the short circuit detection unit is the same and will not be described here. When the step resistor Rbin works normally, the short circuit detection unit can output a low level as the first connection signal, and when the step resistor Rbin is short-circuited, the short circuit detection unit can output a high level as the second connection signal.

[0046] The first electrical connection terminal A of the short circuit selection unit is connected to the main circuit 200, the second electrical connection terminal B of the short circuit selection unit is connected to the short circuit self-recovery module 160, the third electrical connection terminal X of the short circuit selection unit is connected to the step resistor Rbin, and the control terminal Sel of the short circuit selection unit is connected to the short circuit detection unit. After the control terminal Sel of the short circuit selection unit receives the first connection signal, the third electrical connection terminal X of the short circuit selection unit and the first electrical connection terminal A of the short circuit selection unit are connected, and the third electrical connection terminal X of the short circuit selection unit and the second electrical connection terminal B of the short circuit selection unit are disconnected; after the control terminal Sel of the short circuit selection unit receives the second connection signal, the third electrical connection terminal X of the short circuit selection unit and the second electrical connection terminal B of the short circuit selection unit are connected, so that the short circuit self-recovery module 160 supplies power to the branch where the step resistor Rbin is located, and the third electrical connection terminal X of the short circuit selection unit and the first electrical connection terminal A of the short circuit selection unit are disconnected.

[0047] Exemplarily, the short-circuit self-recovery module 160 may include a resistor R10 , one end of which is connected to a power source, and the other end of which is connected to a binning resistor Rbin.

[0048] The above protection circuit sets an open circuit protection resistor R2 as an internal equivalent sub-level resistor inside the LDM. When the external sub-level resistor Rbin works normally, the internal equivalent sub-level resistor R2 is connected in parallel with the external sub-level resistor Rbin to obtain a total resistance value to set the output power required by the LED. When the external sub-level resistor Rbin is open-circuited or short-circuited to the ground, the external sub-level resistor Rbin is disconnected from the main circuit 200, and the output power is set separately according to the resistance value of the internal equivalent sub-level resistor R2. The external sub-level resistor Rbin is powered and maintained by an additional circuit ( Figure 2 In the embodiment, the short circuit self-recovery module 140 is Figure 3 In the embodiment, the short circuit self-recovery module 160 enables the external gear resistor Rbin to automatically recover to normal operation after the short circuit fault is removed. The access circuit of the external gear resistor Rbin and the additional power supply maintenance circuit are mutually exclusive and will not interfere with each other.

[0049] The present application also provides a vehicle lamp. The vehicle lamp includes a main circuit 200, an LED, an LED lamp board, and a protective short circuit as in any of the above embodiments. The LED and the step resistor are both arranged on the LED lamp board, and the main circuit 200 is also connected to the LED. The main circuit 200 is used to control the LED to display according to the first control current or the second control current provided by the protection circuit.

[0050] The above-mentioned headlight provides a first control current to the main circuit 200 when the step resistor Rbin is working normally, and the main circuit 200 controls the display brightness level of the LED in the LED lamp board according to the first control current; when the step resistor Rbin is open-circuited, the open-circuit protection module 120 provides a second control current to the main circuit 200, and the main circuit 200 controls the display brightness level of the LED in the LED lamp board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced compared to when the step resistor Rbin is working normally; when the step resistor Rbin is short-circuited, the LED brightness is reduced. When a circuit fault occurs, the short-circuit protection module 130 disconnects the connection between the step resistor Rbin and the main circuit 200, and then the open-circuit protection module 120 provides a second control current to the main circuit 200. The main circuit 200 controls the display brightness level of the LED in the LED light board according to the second control current. Since the second control current is less than the first control current, the brightness of the LED is reduced compared to when the step resistor works normally. When the step resistor Rbin has an open circuit fault or a short circuit fault, the LED can continue to display and the brightness can be reduced, thereby ensuring the safety of night driving and giving the driver a fault warning.

[0051] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A protection circuit, characterized in that: include: The LED stepping module comprises a stepping resistor connected to the main circuit, and when the stepping resistor works normally, the protection circuit provides a first control current for the main circuit; an open circuit protection module, connected to the main circuit and the step resistor, the open circuit protection module is used to detect whether the step resistor is open circuit, and provide a second control current for the main circuit when the step resistor is open circuit, the second control current is less than the first control current; as well as A short-circuit protection module, through which the step-level resistor is connected to the main circuit, and the short-circuit protection module is used to detect whether the step-level resistor is short-circuited, and disconnect the step-level resistor from the main circuit when the step-level resistor is short-circuited; The open circuit protection module includes an open circuit protection resistor connected in parallel to both ends of the step resistor; When the step-by-step resistor is working normally, the resistance value between point M and the ground terminal is equal to the resistance value of the step-by-step resistor and the open circuit protection resistor in parallel, and the current flowing into the main circuit from point M is the first control current; when the step-by-step resistor is in an open circuit fault, the resistance value between point M and the ground terminal is equal to the resistance value of the open circuit protection resistor, and the resistance value between point M and the ground terminal increases compared to when the step-by-step resistor is working normally, so that the second control current flowing into the main circuit from point M is less than the first control current; point M is the electrical connection point between the LED step-by-step module, the open circuit protection module and the main circuit.

2. The protection circuit according to claim 1, characterized in that: The LED stepping module further includes a first voltage-dividing resistor, wherein the first voltage-dividing resistor and the stepping resistor are sequentially connected in series between a power source and a ground terminal, and the main circuit is connected between the first voltage-dividing resistor and the stepping resistor.

3. The protection circuit according to claim 2, characterized in that: The short circuit protection module comprises: a short-circuit detection unit connected to the step-by-step resistor, the short-circuit detection unit being used to detect whether the step-by-step resistor is short-circuited, and outputting a conduction signal when the step-by-step resistor is short-circuited; and A short-circuit switch unit, wherein the first electrical connection end of the short-circuit switch unit is connected to the main circuit, the second electrical connection end of the short-circuit switch unit is connected to the step-position resistor, the control end of the short-circuit switch unit is connected to the short-circuit detection unit, and after the control end of the short-circuit switch unit receives the conduction signal, the first electrical connection end of the short-circuit switch unit and the second electrical connection end of the short-circuit switch unit are conductively connected.

4. The protection circuit according to claim 3, characterized in that: The short-circuit detection unit includes a comparator and a voltage divider unit, wherein the voltage divider unit is used to provide a comparison voltage for the comparator, the same-direction input terminal of the comparator is connected to the step-level resistor, the reverse input terminal of the comparator is connected to the voltage divider unit, and the output terminal of the comparator is connected to the short-circuit switch unit.

5. The protection circuit according to claim 4, characterized in that: The comparator includes an operational amplifier and a pull-up resistor, the same-direction input terminal of the operational amplifier is connected to the step resistor, the reverse input terminal of the operational amplifier is connected to the voltage divider unit, the output terminal of the operational amplifier is connected to the short-circuit switch unit, and the output terminal of the operational amplifier is also connected to the power supply through the pull-up resistor.

6. The protection circuit according to claim 3, characterized in that: The short-circuit switch unit comprises a transistor, the collector of the transistor is connected to the main circuit, the emitter of the transistor is connected to the step resistor, and the base of the transistor is connected to the short-circuit detection unit.

7. The protection circuit according to claim 1, characterized in that: It also includes a short-circuit self-recovery module, which is connected to the step-by-step resistor and the short-circuit protection module. The short-circuit self-recovery module is used to detect whether the short-circuit fault of the step-by-step resistor is restored after the short-circuit protection module detects that the step-by-step resistor is short-circuited, and after the short-circuit fault of the step-by-step resistor is restored, control the reconnection between the step-by-step resistor and the main circuit through the short-circuit protection module.

8. The protection circuit according to claim 7, characterized in that: The short-circuit self-recovery module includes a self-recovery switch unit and a fourth voltage-dividing resistor. The first electrical connection end of the self-recovery switch unit is connected to the power supply, the second electrical connection end of the self-recovery switch unit is connected to the step-level resistor through the fourth voltage-dividing resistor, and the control end of the self-recovery switch unit is connected to the short-circuit protection module.

9. The protection circuit according to claim 3, characterized in that: It also includes a short circuit self-recovery module; the short circuit protection module includes: a short circuit detection unit connected to the step resistor, the short circuit detection unit being used to detect whether the step resistor is short-circuited, outputting a first connection signal when the step resistor is operating normally and outputting a second connection signal when the step resistor is short-circuited; and A short-circuit selection unit, wherein the first electrical connection end of the short-circuit selection unit is connected to the main circuit, the second electrical connection end of the short-circuit selection unit is connected to the short-circuit self-recovery module, the third electrical connection end of the short-circuit selection unit is connected to the gear-shift resistor, and the control end of the short-circuit switch unit is connected to the short-circuit detection unit; after the control end of the short-circuit selection unit receives the first connection signal, the third electrical connection end of the short-circuit selection unit and the first electrical connection end of the short-circuit selection unit are connected and the third electrical connection end of the short-circuit selection unit and the second electrical connection end of the short-circuit selection unit are disconnected; after the control end of the short-circuit selection unit receives the second connection signal, the third electrical connection end of the short-circuit selection unit and the second electrical connection end of the short-circuit selection unit are connected, the short-circuit self-recovery module supplies power to the branch where the gear-shift resistor is located, and the third electrical connection end of the short-circuit selection unit and the first electrical connection end of the short-circuit selection unit are disconnected.

10. A vehicle lamp, characterized in that: It includes a main circuit, an LED, an LED light board and a protection circuit as described in any one of claims 1 to 9, wherein the LED and the step-position resistors are both arranged on the LED light board, and the main circuit is also connected to the LED, and the main circuit is used to control the LED for display according to the first control current or the second control current provided by the protection circuit.

Images