CN111741556A - Protection circuit and car light - Google Patents
Protection circuit and car light Download PDFInfo
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- CN111741556A CN111741556A CN202010744138.8A CN202010744138A CN111741556A CN 111741556 A CN111741556 A CN 111741556A CN 202010744138 A CN202010744138 A CN 202010744138A CN 111741556 A CN111741556 A CN 111741556A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The invention relates to a protection circuit and a vehicle lamp, comprising: the LED stepping module comprises a stepping resistor connected with the main circuit, and when the stepping resistor works normally, the protection circuit provides a first control current for the main circuit; the open-circuit protection module is connected with the main circuit and the stepping resistor, and is used for detecting whether the stepping resistor is open or not and providing a second control current for the main circuit when the stepping resistor is open, wherein the second control current is smaller than the first control current; and the short-circuit protection module is used for detecting whether the stepping resistor is short-circuited or not and disconnecting the stepping resistor from the main circuit when the stepping resistor is short-circuited. The protection circuit and the car lamp can keep the LED to continue displaying and reduce the brightness when the stepping resistor has an open circuit fault and a short circuit fault, thereby ensuring the safety of driving at night and giving a driver fault warning.
Description
Technical Field
The invention relates to the technical field of vehicle lamp control, in particular to a protection circuit and a vehicle lamp.
Background
The car light includes LED lamp plate and the LDM (constant current control module for LED illumination and signal lamp) that the LED that controls on the LED lamp plate shows, can set up corresponding stepping resistance Rbin according to the power demand of LED on the LED lamp plate usually in order to be used for controlling the demonstration luminance gear of LED. When the LED is connected to the LDM, the LDM reads the voltage or current value of the stepping resistor Rbin on the LED lamp panel to determine the magnitude of the current output from the LDM to the LED lamp panel. Because the stepping resistor Rbin is installed on the LED lamp panel, and the detection circuit of the stepping resistor Rbin is located in the LDM, the stepping resistor Rbin and the LDM can work only by being connected through a connector and a wiring harness. However, in the vehicle body, the connector may have poor contact, and the wire harness may also have a short circuit to the ground, thereby causing a fault that the bin resistor Rbin is open or short-circuited to the ground.
The sensing and action types of the LDM for the gear shifting resistor Rbin include that the larger the gear shifting resistor Rbin is, the smaller the output power is, the smaller the gear shifting resistor Rbin is, the larger the output power is, namely, the LDM is formed by inversely proportional the size of the gear shifting resistor Rbin and the output power. Therefore, when the stepping resistor Rbin is open, the LDM has no output, so that the LED is turned off; when the stepping resistor Rbin is short-circuited to the ground, the LDM can output over power, so that the LED is burnt out due to overheating. For night driving, the sudden turn-off of the lighting and signal lights can cause a great safety problem.
Disclosure of Invention
Therefore, it is necessary to provide a protection circuit and a vehicle lamp for solving the problem that when the magnitude of the bin resistor Rbin is inversely proportional to the output power of the LDM, the open circuit and the short circuit to ground fault of the bin resistor Rbin the conventional technology will make the LED unable to display and thus threaten the safety of the driver.
A protection circuit, comprising:
the LED stepping module comprises a stepping resistor connected with a main circuit, and the protection circuit provides a first control current for the main circuit when the stepping resistor works normally;
the open-circuit protection module is connected with the main circuit and the gear dividing resistor, and is used for detecting whether the gear dividing resistor is open-circuit or not and providing a second control current for the main circuit when the gear dividing resistor is open-circuit, wherein the second control current is smaller than the first control current; and
the short-circuit protection module is used for detecting whether the stepping resistor is short-circuited or not and disconnecting the stepping resistor from the main circuit when the stepping resistor is short-circuited.
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.
In one embodiment, the open circuit protection module comprises an open circuit protection resistor connected in parallel across the tap resistor.
In one embodiment, the short-circuit protection module includes:
the short circuit detection unit is connected with the gear dividing resistor and is used for detecting whether the gear dividing resistor is short-circuited or not and outputting a conducting signal when the gear dividing resistor is short-circuited; and
and the first electric connection end of the short-circuit switch unit is connected with the main circuit, the second electric connection end of the short-circuit switch unit is connected with the stepping resistor, the control end of the short-circuit switch unit is connected with the short-circuit detection unit, and the first electric connection end of the short-circuit switch unit is connected with the second electric connection end of the short-circuit switch unit after the control end of the short-circuit switch unit receives the conduction signal.
In one embodiment, the short circuit detection unit includes a comparator and a voltage dividing unit, the voltage dividing unit is configured to provide a comparison voltage for the comparator, a same-direction input end of the comparator is connected to the stepping resistor, an opposite-direction input end of the comparator is connected to the voltage dividing unit, and an output end of the comparator is connected to the short circuit switch unit.
In one embodiment, the comparator includes an operational amplifier and a pull-up resistor, a unidirectional input terminal of the operational amplifier is connected to the stepping resistor, an inverting input terminal of the operational amplifier is connected to the voltage dividing unit, an output terminal of the operational amplifier is connected to the short-circuit switch unit, and an output terminal of the operational amplifier is further connected to the power supply through the pull-up resistor.
In one embodiment, the short circuit switch unit includes a triode, a collector of the triode is connected with the main circuit, an emitter of the triode is connected with the stepping resistor, and a base of the triode is connected with the short circuit detection unit.
In one embodiment, the short circuit self-recovery module is connected to the stepping resistor and the short circuit protection module, and is configured to detect whether a short circuit fault of the stepping resistor is recovered after the short circuit protection module detects that the stepping resistor is short-circuited, and control reconnection between the stepping resistor and the main circuit through the short circuit protection module after the short circuit fault of the stepping resistor is recovered.
In one embodiment, the short circuit self-recovery module includes a self-recovery switch unit and a fourth voltage-dividing resistor, a first electrical connection end of the self-recovery switch unit is connected to a power supply, a second electrical connection end of the self-recovery switch unit is connected to the stepping resistor through the fourth voltage-dividing resistor, and a control end of the self-recovery switch unit is connected to the short circuit protection module.
In one embodiment, the short circuit self-recovery module is further included; the short-circuit protection module includes:
the short circuit detection unit is connected with the gear resistor and is used for detecting whether the gear resistor is short-circuited or not, outputting a first connection signal when the gear resistor works normally and outputting a second connection signal when the gear resistor is short-circuited; and
a first electric connection end of the short circuit selection unit is connected with the main circuit, a second electric connection end of the short circuit selection unit is connected with the short circuit self-recovery module, a third electric connection end of the short circuit selection unit is connected with the stepping resistor, and a control end of the short circuit switch unit is connected with the short circuit detection unit; after the control end of the short circuit selection unit receives the first connection signal, the third electric connection end of the short circuit selection unit is connected with the first electric connection end of the short circuit selection unit, and the third electric connection end of the short circuit selection unit is disconnected with the second electric connection end of the short circuit selection unit; and after the control end of the short circuit selection unit receives the second connection signal, the third electric connection end of the short circuit selection unit is connected with the second electric connection end of the short circuit selection unit, the short circuit self-recovery module supplies power to the branch circuit where the stepping resistor is located, and the third electric connection end of the short circuit selection unit is disconnected with the first electric connection end of the short circuit selection unit.
The utility model provides a car light, includes main circuit, LED lamp plate and as above arbitrary the protection short circuit, LED and divide gear resistance all set up in on the LED lamp plate, the main circuit still with LED connects, the main circuit is used for the basis protection circuit provides first control current or second control current control LED shows.
The protective circuit and the vehicle lamp provide first control current for the main circuit when the stepping resistor works normally, and the main circuit controls the display brightness gear of the LED in the LED lamp panel according to the first control current; when the stepping resistor is in an open-circuit fault, the open-circuit protection module provides a second control current for the main circuit, the main circuit controls the display brightness gear of the LED in the LED lamp panel according to the second control current, and the second control current is smaller than the first control current, so that the brightness of the LED is reduced when the stepping resistor normally works; when stepping resistance short-circuit fault, short-circuit protection module disconnection is connected between stepping resistance and the main circuit, open circuit protection module provides the second control current for the main circuit then, the main circuit is according to the display luminance gear of the LED in the second control current control LED lamp plate, because the second control current is less than first control current, make for the luminance that has reduced LED when stepping resistance normal work, when stepping resistance open circuit fault and short-circuit fault, can both keep LED to continue to show and reduce luminance, thereby guarantee the safety of driving night and give driver trouble warning.
Drawings
Fig. 1 is a block diagram of a protection circuit according to an embodiment.
Fig. 2 is a circuit diagram of a protection circuit in an embodiment.
Fig. 3 is a circuit diagram of a protection circuit in another embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the description of the present application, it is to be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner" and "outer" etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application. Further, when an element is referred to as being "formed on" another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.
Fig. 1 is a block diagram of a protection circuit in an embodiment. As shown in fig. 1, the protection circuit includes an LED binning module 110, an open-circuit protection module 120, and a short-circuit protection module 130.
The LED stepping module 110 includes a stepping resistor (not shown in fig. 1) connected to the main circuit 200. When the stepping resistor works normally, the protection circuit provides a first control current for the main circuit 200. The main circuit 200 is a circuit used for performing constant current control on the LEDs in the LDM, and the main circuit 200 controls the display brightness gear of the LEDs in the LED lamp panel according to the first control current.
The open circuit protection module 120 is connected to the main circuit 200 and the stepping resistor, and the open circuit protection module 120 is configured to detect whether the stepping resistor is open. For example, whether the stepping resistor is open or not is detected by detecting the voltage across the stepping resistor, the magnitude of the resistor, and the like. The open-circuit protection module 120 provides a second control current to the main circuit 200 when the stepping resistor is open, and the second control current is smaller than the first control current. At this time, the main circuit 200 controls the display brightness level of the LEDs in the LED lamp panel according to the second control current, and the display brightness of the LEDs is reduced because the second control current is smaller than the first control current.
The stepping resistor is connected to the main circuit 200 through the short-circuit protection module 130, and the short-circuit protection module 130 is configured to detect whether the stepping resistor is short-circuited, for example, detect whether the stepping resistor is short-circuited to ground by detecting a voltage across the stepping resistor, a resistance magnitude, and the like. The short-circuit protection module 130 disconnects the stepping resistor from the main circuit 200 when the stepping resistor is short-circuited, at this time, the open-circuit protection module 120 provides a second control current for the main circuit 200, the main circuit 200 controls the display brightness position of the LED in the LED lamp panel according to the second control current, and the display brightness of the LED is reduced because the second control current is smaller than the first control current.
The protection circuit provides a first control current for the main circuit 200 when the stepping resistor works normally, and the main circuit 200 controls the display brightness gear of the LED in the LED lamp panel according to the first control current; when the stepping resistor is in an open-circuit fault, the open-circuit protection module 120 provides a second control current for the main circuit 200, the main circuit 200 controls the display brightness gear of the LED in the LED lamp panel according to the second control current, and the brightness of the LED is reduced compared with that when the stepping resistor normally works because the second control current is smaller than the first control current; when the stepping resistor has a short-circuit fault, the short-circuit protection module 130 disconnects the stepping resistor from the main circuit 200, then the open-circuit protection module 120 provides a second control current for the main circuit 200, the main circuit 200 controls the display brightness gear of the LED in the LED lamp panel according to the second control current, and because the second control current is smaller than the first control current, the brightness of the LED is reduced when the stepping resistor normally works, so that the LED can be kept to continue displaying and reduce the brightness when the stepping resistor has the short-circuit fault, thereby ensuring the safety of driving at night and giving a fault warning to a driver.
Fig. 2 is a circuit diagram of a protection circuit in an embodiment. As shown in fig. 2, the LED stepping module 110 includes a first voltage-dividing resistor R1 and a stepping resistor Rbin, the first voltage-dividing resistor R1 and the stepping resistor Rbin are sequentially connected in series between the power supply and the ground, and the main circuit 200 is connected between the first voltage-dividing resistor R1 and the stepping resistor Rbin.
In one embodiment, the open circuit protection module 120 includes an open circuit protection resistor R2 connected in parallel across the stepping resistor Rbin. When the tap resistor Rbin operates normally, the resistance between the point M and the ground is equal to the resistance between the tap resistor Rbin and the open-circuit protection resistor R2 in parallel, and the current flowing into the main circuit 200 from the point M is the first control current. When the stepping resistor Rbin is in an open-circuit fault, the resistance between the M point and the ground terminal is equal to the resistance of the open-circuit protection resistor R2, which is larger than the resistance between the normal operation of the stepping resistor Rbin and the ground terminal, so that the current flowing into the main circuit 200 from the M point, i.e., the second control current, is smaller than the first control current, thereby reducing the LED display brightness.
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 generation unit, wherein the open circuit detection unit is connected to the bin resistor and is configured to detect whether the bin resistor Rbin is open. The open switch unit is connected between the main circuit 200 and the second control current generating unit, and when the tap position resistor Rbin works normally, the open switch unit disconnects the main circuit 200 from the second control current generating unit, the resistance value between the point M and the ground is equal to the resistance value of the tap position resistor Rbin, and the first control current is input to the main circuit 200 from the point M. When the tap position resistor Rbin is in an open-circuit fault, the open-circuit switch unit controls the main circuit 200 to be conducted with the second control current generating unit, and the second control current output by the second control current generating unit is input to the main circuit 200 from the point M.
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 with the stepping resistor and is used for detecting whether the stepping resistor is short-circuited or not and outputting a conducting signal when the stepping resistor is short-circuited. The first electric connection end of the short-circuit switch unit is connected with the main circuit 200, the second electric connection end of the short-circuit switch unit is connected with the stepping resistor, the control end of the short-circuit switch unit is connected with the short-circuit detection unit, and the first electric connection end of the short-circuit switch unit and the second electric connection end of the short-circuit switch unit are conducted after the control end of the short-circuit switch unit receives the conducting signal.
Illustratively, the short detection unit includes a comparator and a voltage division unit. The voltage division unit is used for providing comparison voltage for the comparator. The same-direction input end of the comparator is connected with the stepping resistor Rbin, the reverse input end of the comparator is connected with the voltage division unit, and the output end of the comparator is connected with the short-circuit switch unit.
Specifically, the comparator includes an operational amplifier U1 and a pull-up resistor R9. The same-direction input end of the operational amplifier U1 is connected with the stepping resistor Rbin, the reverse-direction input end of the operational amplifier U1 is connected with the voltage division unit, the output end of the operational amplifier U1 is connected with the short-circuit switch unit, and the output end of the operational amplifier U1 is connected with a power supply through a pull-up resistor R9. The voltage dividing unit comprises a second voltage dividing resistor R6 and a third voltage dividing resistor R7 which are connected in series between a power supply and a ground terminal, and the inverting input end of the operational amplifier U1 is connected between the second voltage dividing resistor R6 and the third voltage dividing resistor R7, so that the voltage at the point L is the reference voltage Vth. The shorting switch unit includes a transistor Q1. The collector of the triode Q1 is connected with the main circuit 200, the emitter of the triode Q1 is connected with the stepping resistor Rbin, and the base of the triode Q1 is connected with the output end of the operational amplifier U1 in the short-circuit detection unit.
The comparator compares the voltage input by the equidirectional input end, namely the voltage of an N point, with the voltage Vth of the reverse input end, when the gear-shifting resistor Rbin works normally, the voltage Vbin of the N point is more than Vth and more than Vgnd, the Vgnd is the voltage of the grounding end, the output end of the comparator outputs high level, the collector and the emitter of the triode Q1 are conducted, the gear-shifting resistor Rbin is connected into the circuit to work normally, and the main circuit 200 controls the LED to display according to the first control current. When the stepping resistor Rbin has a short-circuit fault to the ground, the voltage Vbin at the point N is Vgnd < Vth, Vgnd is the voltage of the ground terminal, the output end of the comparator outputs a low level, the collector and the emitter of the triode Q1 are switched off, and the stepping resistor Rbin is disconnected from the main circuit 200. At this time, the open-circuit protection module 120 detects that the stepping resistor Rbin is open-circuited, and provides the second control current for the main circuit 200, and the main circuit 200 controls the LED to display according to the second control current, so that the LED display brightness is reduced.
In one embodiment, the protection circuit further comprises a short circuit self-recovery module 140. The short circuit self-recovery module 140 is connected to the stepping resistor and the short circuit protection module 130, and the short circuit self-recovery module 140 is configured to detect whether a short circuit fault of the stepping resistor Rbin is recovered after the short circuit protection module 130 detects that the stepping resistor Rbin is short-circuited, and control the stepping resistor Rbin to be reconnected with the main circuit 200 through the short circuit protection module 130 after the short circuit fault of the stepping resistor Rbin is recovered, so that the main circuit 200 still controls the LED to normally display according to the first control current after the short circuit fault of the stepping resistor Rbin is recovered.
Illustratively, the short circuit self-recovery module 140 includes a self-recovery switching unit and a fourth voltage-dividing resistor R4. The first electrical connection end of the self-recovery switch unit is connected with the power supply, the second electrical connection end of the self-recovery switch unit is connected with the stepping resistor Rbin through the fourth voltage dividing resistor R4, and the control end of the self-recovery switch unit is connected with the short-circuit protection module 130. The self-recovery switching unit may include a transistor Q2 and a pull-up resistor R8. The collector of the triode Q2 is connected with the stepping resistor Rbin through a fourth voltage-dividing resistor R4, the emitter of the triode Q2 is connected with the power supply, and the base of the triode Q2 is connected with the power supply through a pull-up resistor R8 and is connected with the output end of the operational amplifier U1.
When the stepping resistor Rbin has a short-circuit fault, the comparator outputs a low level, the triode Q2 is conducted, the power supply supplies power to the stepping resistor Rbin through the triode Q2 and the fourth voltage-dividing resistor R4, and when the short-circuit fault of the stepping resistor Rbin is not recovered, the voltage Vbin of an N point is still equal to the voltage Vgnd of a grounding end, the comparator still outputs the low level, and the triode Q1 is still in a turn-off state to perform short-circuit protection; when the gear resistor Rbin returns to normal, the voltage Vbin at the point N is higher than the reference voltage Vth at the point L again due to the addition of the triode Q2 and the fourth voltage resistor R4, the comparator outputs high level in an overturning manner, the triode Q1 is opened, the gear resistor Rbin is connected to the main circuit 200 again to work normally, meanwhile, the triode Q2 is turned off, and the triode Q2 and the fourth voltage resistor R4 do not influence the gear resistor Rbin any more. In addition, when the circuit is powered on, the transistor Q1 is not conducted, and the stepping resistor Rbin cannot be normally connected, so that the circuit is not started, and therefore, the circuits corresponding to the transistor Q2 and the fourth voltage-dividing resistor R4 can also ensure that the circuit is powered on and normally starts to work.
Fig. 3 is a circuit diagram of a protection circuit in another embodiment. As shown in fig. 3, the protection circuit includes a short circuit protection module 150 and a short circuit self-recovery module 160 in addition to the LED binning module 110 and the open circuit protection module 120 described above.
The short-circuit protection module 150 includes a short-circuit detection unit and a short-circuit selection unit, which may be an alternative switch S1 such as an electrically controlled mechanical switch, an electronic switch, and the like. The short circuit detection unit is connected with the gear-shifting resistor Rbin and is used for detecting whether the gear-shifting resistor Rbin is short-circuited or not, outputting a first connection signal when the gear-shifting resistor Rbin normally works and outputting a second connection signal when the gear-shifting resistor Rbin is short-circuited. The circuit structure of the short circuit detection unit in this embodiment may be the same as that of the short circuit detection unit in fig. 2, and is not described herein again. The short circuit detection unit may output a low level as the first connection signal when the bin resistor Rbin normally operates, and may output a high level as the second connection signal when the bin resistor Rbin is short-circuited.
The first electrical connection end a of the short circuit selection unit is connected with the main circuit 200, the second electrical connection end B of the short circuit selection unit is connected with the short circuit self-recovery module 160, the third electrical connection end X of the short circuit selection unit is connected with the gear-shifting resistor Rbin, and the control end Sel of the short circuit selection unit is connected with the short circuit detection unit. After the control end Sel of the short circuit selection unit receives the first connection signal, the third electric connection end X of the short circuit selection unit is connected with the first electric connection end a of the short circuit selection unit, and the third electric connection end X of the short circuit selection unit is disconnected with the second electric connection end B of the short circuit selection unit; after the control end Sel of the short circuit selection unit receives the second connection signal, the third electrical connection end X of the short circuit selection unit is connected with the second electrical connection end B of the short circuit selection unit, so that the short circuit self-recovery module 160 supplies power to the branch where the stepping resistor Rbin is located, and the third electrical connection end X of the short circuit selection unit is disconnected with the first electrical connection end a of the short circuit selection unit.
For example, the short circuit self-recovery module 160 may include a resistor R10, one end of the resistor R10 being connected to the power source, and the other end being connected to the bin resistor Rbin.
In the protection circuit, the open-circuit protection resistor R2 is arranged in the LDM to serve as an internal equivalent step resistor, and when the external step resistor Rbin works normally, a total resistance value is obtained by connecting the internal equivalent step resistor R2 and the external step resistor Rbin in parallel to set the output power required by the LED. When the external tap position resistor Rbin is open-circuited or short-circuit to the ground occurs, the external tap position resistor Rbin is disconnected from the main circuit 200, and the output power is set independently according to the resistance value of the internal equivalent tap position resistor R2. The external gear resistor Rbin is maintained by an additional circuit (in the embodiment of fig. 2, the short circuit self-recovery module 140, and in the embodiment of fig. 3, the short circuit self-recovery module 160), so that the external gear resistor Rbin can automatically recover to normal operation after the short circuit fault is removed. The access circuit of the external gear resistor Rbin and the circuit for additionally supplying power and maintaining are in a mutual exclusion relationship, and cannot interfere with each other.
The application also provides a car light. The vehicle lamp comprises a main circuit 200, an LED lamp panel and a protective short circuit as in any of the above embodiments. The LED and the stepping resistor are arranged on the LED lamp panel, the main circuit 200 is further connected with the LED, and the main circuit 200 is used for providing a first control current or a second control current to control the LED to display according to the protection circuit.
In the vehicle lamp, when the gear-shifting resistor Rbin works normally, a first control current is provided for the main circuit 200, and the main circuit 200 controls the display brightness gear of the LED in the LED lamp panel according to the first control current; when the tap position resistor Rbin is in an open-circuit fault, the open-circuit protection module 120 provides a second control current for the main circuit 200, the main circuit 200 controls the display brightness tap position of the LED in the LED lamp panel according to the second control current, and the second control current is smaller than the first control current, so that the brightness of the LED is reduced when the tap position resistor Rbin normally works; when the stepping resistor Rbin has a short-circuit fault, the short-circuit protection module 130 disconnects the stepping resistor Rbin from the main circuit 200, then the open-circuit protection module 120 provides a second control current for the main circuit 200, the main circuit 200 controls the display brightness level of the LED in the LED lamp panel according to the second control current, because the second control current is smaller than the first control current, the brightness of the LED is reduced when the stepping resistor normally works, and when the stepping resistor Rbin has the short-circuit fault, the LED can be kept to continue displaying and reduce the brightness, so that the safety of driving at night is ensured, and the fault warning is given to a driver.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A protection circuit, comprising:
the LED stepping module comprises a stepping resistor connected with a main circuit, and the protection circuit provides a first control current for the main circuit when the stepping resistor works normally;
the open-circuit protection module is connected with the main circuit and the gear dividing resistor, and is used for detecting whether the gear dividing resistor is open-circuit or not and providing a second control current for the main circuit when the gear dividing resistor is open-circuit, wherein the second control current is smaller than the first control current; and
the short-circuit protection module is used for detecting whether the stepping resistor is short-circuited or not and disconnecting the stepping resistor from the main circuit when the stepping resistor is short-circuited.
2. The protection circuit of claim 1, wherein the LED stepping module further comprises 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.
3. The protection circuit of claim 1, wherein the open circuit protection module comprises an open circuit protection resistor connected in parallel across the tap resistor.
4. The protection circuit of claim 1, wherein the short-circuit protection module comprises:
the short circuit detection unit is connected with the gear dividing resistor and is used for detecting whether the gear dividing resistor is short-circuited or not and outputting a conducting signal when the gear dividing resistor is short-circuited; and
and the first electric connection end of the short-circuit switch unit is connected with the main circuit, the second electric connection end of the short-circuit switch unit is connected with the stepping resistor, the control end of the short-circuit switch unit is connected with the short-circuit detection unit, and the first electric connection end of the short-circuit switch unit is connected with the second electric connection end of the short-circuit switch unit after the control end of the short-circuit switch unit receives the conduction signal.
5. The protection circuit according to claim 4, wherein the short circuit detection unit includes a comparator and a voltage dividing unit, the voltage dividing unit is configured to provide a comparison voltage for the comparator, a same-direction input terminal of the comparator is connected to the stepping resistor, an opposite-direction input terminal of the comparator is connected to the voltage dividing unit, and an output terminal of the comparator is connected to the short circuit switch unit.
6. The protection circuit according to claim 5, wherein the comparator comprises an operational amplifier and a pull-up resistor, a unidirectional input terminal of the operational amplifier is connected with the stepping resistor, an inverting input terminal of the operational amplifier is connected with the voltage dividing unit, an output terminal of the operational amplifier is connected with the short-circuit switch unit, and an output terminal of the operational amplifier is further connected with the power supply through the pull-up resistor.
7. The protection circuit according to claim 4, wherein the short-circuit switch unit comprises a triode, a collector of the triode is connected with the main circuit, an emitter of the triode is connected with the stepping resistor, and a base of the triode is connected with the short-circuit detection unit.
8. The protection circuit according to claim 1, further comprising a short circuit self-recovery module connected to the stepping resistor and the short circuit protection module, wherein the short circuit self-recovery module is configured to detect whether the short circuit fault of the stepping resistor is recovered after the short circuit protection module detects that the stepping resistor is short-circuited, and control the stepping resistor and the main circuit to be turned on again through the short circuit protection module after the short circuit fault of the stepping resistor is recovered.
9. The protection circuit according to claim 8, wherein the short-circuit self-recovery module includes a self-recovery switch unit and a fourth voltage-dividing resistor, a first electrical connection terminal of the self-recovery switch unit is connected to a power supply, a second electrical connection terminal of the self-recovery switch unit is connected to the stepping resistor through the fourth voltage-dividing resistor, and a control terminal of the self-recovery switch unit is connected to the short-circuit protection module.
10. The protection circuit of claim 1, further comprising a short circuit self-recovery module; the short-circuit protection module includes:
the short circuit detection unit is connected with the gear resistor and is used for detecting whether the gear resistor is short-circuited or not, outputting a first connection signal when the gear resistor works normally and outputting a second connection signal when the gear resistor is short-circuited; and
a first electric connection end of the short circuit selection unit is connected with the main circuit, a second electric connection end of the short circuit selection unit is connected with the short circuit self-recovery module, a third electric connection end of the short circuit selection unit is connected with the stepping resistor, and a control end of the short circuit switch unit is connected with the short circuit detection unit; after the control end of the short circuit selection unit receives the first connection signal, the third electric connection end of the short circuit selection unit is connected with the first electric connection end of the short circuit selection unit, and the third electric connection end of the short circuit selection unit is disconnected with the second electric connection end of the short circuit selection unit; and after the control end of the short circuit selection unit receives the second connection signal, the third electric connection end of the short circuit selection unit is connected with the second electric connection end of the short circuit selection unit, the short circuit self-recovery module supplies power to the branch circuit where the stepping resistor is located, and the third electric connection end of the short circuit selection unit is disconnected with the first electric connection end of the short circuit selection unit.
11. A car lamp is characterized by comprising a main circuit, an LED lamp panel and the protection short circuit according to any one of claims 1 to 10, wherein the LED and the gear dividing resistor are arranged on the LED lamp panel, the main circuit is further connected with the LED, and the main circuit is used for controlling the LED to display according to the first control current or the second control current provided by the protection circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010744138.8A CN111741556A (en) | 2020-07-29 | 2020-07-29 | Protection circuit and car light |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010744138.8A CN111741556A (en) | 2020-07-29 | 2020-07-29 | Protection circuit and car light |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111741556A true CN111741556A (en) | 2020-10-02 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010744138.8A Pending CN111741556A (en) | 2020-07-29 | 2020-07-29 | Protection circuit and car light |
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| Country | Link |
|---|---|
| CN (1) | CN111741556A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114063526A (en) * | 2021-11-22 | 2022-02-18 | 江苏科技大学 | Motor gear control circuit and control method |
-
2020
- 2020-07-29 CN CN202010744138.8A patent/CN111741556A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114063526A (en) * | 2021-11-22 | 2022-02-18 | 江苏科技大学 | Motor gear control circuit and control method |
| CN114063526B (en) * | 2021-11-22 | 2024-04-23 | 江苏科技大学 | Motor gear control circuit and control method |
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