CN116400262A - A reliable open-short-circuit diagnosis circuit and its open-short-circuit diagnosis method for ambient light - Google Patents

Abstract

The present invention provides a reliable open-short-circuit diagnosis circuit of ambient light and its open-short-circuit diagnosis method. The open-short circuit diagnosis circuit of ambient light includes a control unit and one or more detection circuits, and each detection circuit includes first and second divided voltages. circuit, first and second diode units, the first diode unit includes m diodes, the cathodes of the m diodes are all connected to the first connection node A; the second diode unit includes another m diodes, and in addition The anodes of the m diodes are all connected to the second connection node B; the input terminal of the first voltage divider circuit is connected to the first connection node A, and its output terminal is used as the first diagnostic node C of the detection circuit where it is located; The input terminal of the second voltage dividing circuit is connected with the second connection node B, and its output terminal is used as the second diagnosis node D of the detection circuit where it is located; the control unit is based on the voltage of the first diagnosis node C and the second diagnosis node D Diagnose the open and short circuit of the corresponding LED array.

Description

A reliable open-short-circuit diagnosis circuit and its open-short-circuit diagnosis method for ambient light

【Technical field】

The invention relates to the technical field of detection of vehicle-mounted ambient lamps, in particular to a reliable open-short-circuit diagnostic circuit for ambient lamps and a diagnostic method for open-short circuit.

【Background technique】

Nowadays, car atmosphere lights have higher requirements for the diagnosis of LED open and short circuits. The traditional equivalent power supply and resistor divider method have great disadvantages. Considering the large-scale fluctuation of input voltage, large-scale fluctuation of temperature, and RGB lamp beads The error of the different BIN areas and the voltage drop of the PN junction leads to the fact that the open circuit of the green light and the blue light bead cannot be detected under the condition of low voltage and low temperature. This is also an old problem that cannot be distinguished from the open circuit of traditional discrete devices. If you work hard, you can only distinguish the open and short circuit thresholds by compressing the input voltage.

Therefore, it is necessary to propose a new technical solution to solve the above problems.

【Content of invention】

One of the objects of the present invention is to provide a reliable open-short-circuit diagnosis circuit and its open-short-circuit diagnosis method for ambient light, which can reliably detect the open-short circuit problem of RGB (Red, Green, Blue), wherein the BIN area of RGB, Factors such as temperature and input voltage have no effect on the detection.

According to one aspect of the present invention, the present invention provides an ambient light open-short circuit diagnostic circuit, which includes a control unit and one or more detection circuits, wherein each detection circuit includes a first voltage divider circuit, a second voltage divider circuit , a first diode unit and a second diode unit, the first diode unit includes m diodes, and the anodes of the m diodes are respectively connected to m detection points in a corresponding light emitting diode array , the cathodes of the m diodes are all connected to the first connection node A; the second diode unit includes another m diodes, and the cathodes of the other m diodes are respectively connected to the corresponding light-emitting diode array The m detection points are connected, and the anodes of the other m diodes are all connected to the second connection node B; the input terminal of the first voltage divider circuit is connected to the first connection node A, and its output terminal is used as its The first diagnostic node C of the detection circuit where it is located; the input terminal of the second voltage divider circuit is connected to the second connection node B, and its output terminal is used as the second diagnostic node D of the detection circuit where it is located The control unit diagnoses the corresponding light-emitting diode array by sampling the voltage of the first diagnosis node C and the second diagnosis node D of each detection circuit, and based on the voltage of the first diagnosis node C and the second diagnosis node D open short circuit, where m is a positive integer.

According to another aspect of the present invention, the present invention provides an open-short circuit diagnosis method based on an ambient light open-short circuit diagnosis circuit, which includes: the control unit first samples the voltage of the first diagnosis node C of each detection circuit and The difference of the voltage of the second diagnosis node D is stored in the memory as the diagnosis reference voltage Vadc1; The value is used as the diagnostic detection voltage Vadc2, and the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is calculated; the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is located at the first When within the predetermined fluctuation range, it is determined that the corresponding LED array does not have an open circuit or short circuit fault; when the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is outside the first predetermined fluctuation range When within the second predetermined fluctuation range, it is determined that an open-circuit fault has occurred in the corresponding LED array; when the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the first predetermined fluctuation range When it is outside the third predetermined fluctuation range, it is determined that a short-circuit fault has occurred in the corresponding LED array.

Compared with the prior art, the present invention adopts the characteristics of diodes, and the anode voltage of the diodes will change significantly when RGB appears open circuit and short circuit. Using this change combined with the corresponding detection strategy, the problem of RGB open and short circuit is solved from the source, among which RGB BIN area, temperature, input voltage and other factors have no effect on the detection.

【Description of drawings】

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort. in:

Fig. 1 is a schematic circuit diagram of an ambient light open-short circuit diagnostic circuit in an embodiment of the present invention;

FIG. 2 is an enlarged schematic diagram of the first detection circuit and the first light-emitting diode array shown in FIG. 1 of the present invention;

Fig. 3 is the enlarged schematic view of the multiplexing switch shown in Fig. 1 of the present invention;

FIG. 4 is a flow chart of an open-short circuit diagnosis method of an ambient light open-short circuit diagnosis circuit in an embodiment of the present invention.

【Detailed ways】

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Reference herein to "one embodiment" or "an embodiment" refers to a particular feature, structure or characteristic that can be included in at least one implementation of the present invention. "In one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments. Unless otherwise specified, the words coupled, connected, connected, and connected in this article mean that they are connected directly or indirectly. Electrical components or circuits are connected to B.

In describing the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "front", "back", "left", "right", "vertical", The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and Simplified descriptions, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention.

Aiming at the reason why the open and short circuit thresholds in the aforementioned background technology cannot be distinguished, the present invention adopts the characteristics of diodes, and when RGB appears to be open and short circuited, the anode voltage of the diode will change significantly, and this change is combined with the corresponding detection strategy to solve the problem from the source The open-short circuit problem of RGB is solved, and factors such as RGB's BIN area, temperature, and input voltage have no effect on the detection.

According to one aspect of the present invention, the present invention provides an ambient light open-short circuit diagnostic circuit. Please refer to FIG. 1 , which is a schematic circuit diagram of an open-short circuit diagnosis circuit for an ambient light in an embodiment of the present invention. The ambient light on-short circuit diagnosis circuit shown in FIG. The LED arrays 210 are connected, the second detection circuit 120 is connected to the corresponding second LED array 220 , and the third detection circuit 130 is connected to the corresponding third LED array 230 .

Please refer to FIG. 2 , which is an enlarged schematic diagram of the first detection circuit and the first LED array shown in FIG. 1 of the present invention. In the embodiment shown in FIG. 1 and FIG. 2 , the first detection circuit 110 includes a first voltage dividing circuit 112 , a second voltage dividing circuit 114 , a first diode unit 116 and a second diode unit 118 . Wherein, the first diode unit 116 includes three diodes D1, D2 and D3, and the anodes of the three diodes D1, D2 and D3 are respectively connected to the three detection points a, b and c in the corresponding first LED array 210. The cathodes of the three diodes D1, D2 and D3 are all connected to the first connection node A. The second diode unit 118 includes another three diodes D4, D5 and D6, and the cathodes of the three diodes D4, D5 and D6 are respectively connected to the three detection points a, b and c in the corresponding first LED array 210 , the anodes of the three diodes D4, D5 and D6 are all connected to the second connection node B. The input end of the first voltage divider circuit 112 is connected to the first connection node A, and its output end serves as the first diagnostic node C. The input terminal of the second voltage dividing circuit 114 is connected to the second connection node B, and its output terminal is used as the second diagnostic node D.

In the specific embodiment shown in FIG. 1 and FIG. 2 , the first voltage divider circuit 112 includes a resistor R2 and a resistor R1, and the resistor R2 and the resistor R1 are sequentially connected in series between the first connection node A and the ground terminal; the resistor R2 and the resistor The connection node between R1 is called the first diagnostic node C of the first detection circuit 110 where it is located. The second voltage divider circuit 114 includes a resistor R3, a resistor R7 and a resistor R8, the resistor R3 is connected between the first power supply voltage VCC and the second connection node B; the resistor R8 and the resistor R7 are sequentially connected in series with the second connection node B and the ground terminal between; the connection node between the resistors R7 and R8 is called the second diagnostic node D of the first detection circuit 110 where it is located.

In the specific embodiment shown in FIG. 1 and FIG. 2 , the first LED array 210 includes 3 LED lamps 211 , 212 and 213 , and 3 constant current sources 214 , 215 and 216 . Among them, one end of each LED lamp 211, 212, 213 is connected to the first power supply voltage VCC, and the other end is grounded through the corresponding constant current source 214, 215, 216; each LED lamp 211, 212, 213 is connected to the corresponding constant current source. A connection node between the flow sources 214, 215, 216 is called a detection point a, b, c of the first LED array 210 where it is located. For example, one end of the first LED lamp 211 is connected to the first power supply voltage VCC, and the other end is grounded through the first constant current source 214. The connection node between the first LED lamp 211 and the first constant current source 214 is called The first detection point a of the first light-emitting diode array 210; one end of the second road LED lamp 212 is connected with the first power supply voltage VCC, and its other end is grounded through the second constant current source 215, and the second road LED lamp 212 and the second The connection node between the constant current sources 215 is called the second detection point b of the first LED array 210; one end of the third LED lamp 213 is connected to the first power supply voltage VCC, and the other end is passed through the third constant current source 216 Grounded, the connection node between the third LED lamp 213 and the third constant current source 216 is called the third detection point c of the first LED array 210 .

In the specific embodiment shown in FIG. 1 and FIG. 2, the first LED lamp 211 includes two light-emitting diodes LED1 and LED4 connected in series; the second LED lamp 212 includes two light-emitting diodes LED2 and LED5 connected in series; The third LED lamp 213 includes two LEDs LED3 and LED6 serially connected in series. In other embodiments, each LED lamp 211, 212, 213 may include 1, 3, 4 or more light-emitting diodes, that is to say, each LED lamp 211, 212, 213 includes sequentially n LEDs connected in series, where n is a positive integer.

In the embodiment shown in FIG. 1 and FIG. 2 , the first constant current source 214 includes a resistor R4 , a resistor R9 , a resistor R10 , a transistor Q1 and a transistor Q4 . Wherein, the first connection terminal of the triode Q1 is connected to the second power supply voltage VDD through the resistor R4, the second connection terminal thereof is grounded through the resistor R9, and the control terminal thereof is connected to the first connection terminal; the first connection terminal of the triode Q4 is connected to the first The corresponding detection point a of the constant current source 214 is connected, its second connection terminal is grounded through the resistor R10, and its control terminal is connected to the control terminal of the transistor Q1. In the specific embodiment shown in Figures 1 and 2, the transistor Q1 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q1 are respectively the collector, the emitter and the base of the NPN transistor. ; The transistor Q4 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q4 are respectively the collector, the emitter and the base of the NPN transistor.

In the embodiment shown in FIG. 1 , the second constant current source 215 has the same circuit structure as the first constant current source 214 , and the second constant current source 215 includes a resistor R5 , a resistor R11 , a resistor R12 , a transistor Q2 and a transistor Q5 . Wherein, the first connection end of the triode Q2 is connected to the second power supply voltage VDD through the resistor R5, the second connection end is grounded through the resistor R11, and the control end is connected to the first connection end; the first connection end of the triode Q5 is connected to the second power supply voltage VDD. The corresponding detection point b of the constant current source 215 is connected, its second connection terminal is grounded through the resistor R12, and its control terminal is connected to the control terminal of the transistor Q2. In the specific embodiment shown in Fig. 1, the transistor Q2 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q2 are respectively the collector, the emitter and the base of the NPN transistor; the transistor Q5 It is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q5 are respectively the collector, the emitter and the base of the NPN transistor.

In the embodiment shown in FIG. 1 , the third constant current source 216 has the same circuit structure as the first constant current source 214 , and the third constant current source 216 includes a resistor R6 , a resistor R13 , a resistor R14 , a transistor Q3 and a transistor Q6 . Wherein, the first connection end of the triode Q3 is connected to the second power supply voltage VDD through the resistor R6, the second connection end is grounded through the resistor R13, and the control end is connected to the first connection end; the first connection end of the triode Q6 is connected to the third The corresponding detection point c of the constant current source 216 is connected, its second connection terminal is grounded through the resistor R14, and its control terminal is connected to the control terminal of the transistor Q3. In the specific embodiment shown in Fig. 1, the transistor Q3 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q3 are respectively the collector, the emitter and the base of the NPN transistor; the transistor Q6 It is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q6 are respectively the collector, the emitter and the base of the NPN transistor.

It should be noted that the circuit structure of the second detection circuit 120 and the third detection circuit 130 is consistent with the circuit structure of the first detection circuit 110; the second LED array 220 and the third LED array 230 are the same as the first LED array The circuit structure of 210 is consistent; the circuit connection relationship between the second detection circuit 120 and the second light-emitting diode array 220 is consistent with the circuit connection relationship between the first detection circuit 110 and the first light-emitting diode array 210; the third detection circuit 130 and the third light-emitting diode array The circuit connection relationship of the diode array 230 is consistent with the circuit connection relationship of the first detection circuit 110 and the first light emitting diode array 210; for details, please refer to the above description of the first detection circuit 110 and the first light emitting diode array 210, so it will not be discussed here. Let me repeat.

The control unit (for example, MCU) samples the voltage of the first diagnosis node C and the second diagnosis node D of each detection circuit 110, 120, 130, and diagnoses the corresponding Opening and shorting of the light emitting diode arrays 210, 220, 230. In the embodiment shown in Fig. 1, the first LED array 210, the second LED array 220 and the third LED array 230 form RGB, for example, the first LED array 210 is a red LED array; The LED array 220 is a green LED array; the third LED array 230 is a blue LED array.

The ambient light on-short circuit diagnostic circuit shown in FIG. 1 further includes a multiplexing switch 140, and the multiplexing switch 140 time-shares the first diagnostic node C and the second diagnostic node D of each detection circuit 110, 120, 130 It is connected to the input interface Vadc of the same analog-to-digital converter (not shown); the control unit samples each detection circuit 110, 120, 130 one by one through the analog-to-digital converter (not shown) and the multiplexing switch 140 The voltages of the first diagnosis node C and the second diagnosis node D. Please refer to FIG. 3 , which is an enlarged schematic diagram of the multiplexing switch shown in FIG. 1 of the present invention. As shown in Figure 1 and Figure 3, the input interfaces S0 and S1 of the multiplexing switch 140 are respectively connected to the first diagnostic node C and the second diagnostic node D of the first detection circuit 110; its input interface S2 and interface S3 are respectively It is connected to the first diagnosis node C and the second diagnosis node D of the second detection circuit 120; its input interface S4 and interface S5 are respectively connected to the first diagnosis node C and the second diagnosis node D of the third detection circuit 130; its power supply The interface VDD and the second power supply voltage VDD; its output interface D is connected to the ground through the voltage dividing resistors R43 and R44 in turn, and the input interface Vadc of the analog-to-digital converter (not shown) is connected to the connection node between the voltage dividing resistors R43 and R44.

The design principle of the open-short-circuit diagnostic circuit for the ambient light shown in FIG. 1 will be introduced in detail below.

1. Hardware principle, taking the first detection circuit 110 and the first LED array 210 as examples.

1. When the first light-emitting diode array 210 is in normal operation, the first power supply voltage VCC (that is, the input voltage VCC) passes through the first light-emitting diode array 210 to the constant current sources 214, 215, and 216, and the diodes D1, D2, and D3 have a common cathode , the cathode voltage is determined by the maximum voltage value among the three anode voltages. At this time, the voltage drop (or voltage) of the cathodes of D1, D2, and D3 is the highest voltage minus the voltage difference of the diode;

2. At the same time, the anode voltages of diodes D4, D5, and D6 are determined by the minimum voltage value among the three cathode voltages. The anodes of diodes D4, D5, and D6 are pulled up to the first power supply voltage VCC through resistor R3 to ensure that the anode voltage is the cathode voltage Add a diode dropout;

3. After passing through the common anode and common cathode diodes, adopt the method of resistive voltage division to come to the channel of Tmux1308-Q1, and perform polling ADC polling sampling;

4. When the first light-emitting diode array 210 is short-circuited, the highest voltage among the three voltages will be raised to the voltage of one LED, and the analog-to-digital converter ADC will be sampled after being divided by diodes and resistors, and the first diagnostic node will be detected The voltage of C rises, and a short circuit is reported;

5. When the first light-emitting diode array 210 is disconnected, the lowest voltage among the three voltages appears on the faulty one, and the anode voltages of D4, D5, and D6 will be significantly lower than normal operation, and the second diagnostic node will be detected The voltage of D is obviously pulled down, and it is reported as an open circuit.

2. Working principle

1. The control unit stores the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit 110, 120, 130 sampled for the first time as a diagnostic reference voltage Vadc1 in the memory, and the real-time sampled The difference between the voltage of the first diagnosis node C and the voltage of the second diagnosis node D of each detection circuit 110, 120, 130 is used as the diagnosis detection voltage Vadc2, and the difference between the diagnosis detection voltage Vadc2 and the corresponding diagnosis reference voltage Vadc1 is calculated ;

2. When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the first predetermined fluctuation range, it is determined that the corresponding light-emitting diode arrays 210, 220, 230 have no open circuit or short circuit fault;

3. When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the second predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that the corresponding LED array 210, 220, 230 has an open-circuit fault;

4. When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the third predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that a short-circuit fault occurs in the corresponding LED array 210, 220, 230;

5. During open-short circuit diagnosis, the control unit also stores the first power supply voltage VCC of each LED array 210, 220, 230 initially sampled in the memory as a reference power supply voltage VCC1, and stores the real-time sampled first power supply voltage VCC of each LED array The first power supply voltage VCC of 210, 220, 230 is used as the detection power supply voltage VCC2. When the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within the fourth predetermined fluctuation range, the corresponding LED arrays 210, 220, 230 performs an open-short circuit diagnosis.

In a preferred embodiment, the sampled (for example, initial sampling or real-time sampling) voltage of the first diagnostic node C, voltage of the second diagnostic node D and the first power supply voltage VCC are delayed and filtered.

It should be noted that, in the embodiment shown in FIG. 1 , there are three detection circuits 110 , 120 , and 130 , and three LED arrays. The open-short-circuit diagnosis circuit for ambient light shown in FIG. 1 can open and short-circuit RGB diagnosis. In other embodiments, there may be 1, 2, 4 or more detection circuits, and 1, 2, 4 or more corresponding light-emitting diode arrays, and the corresponding atmosphere lights shall be short-circuited. The diagnostic circuit can perform open-short circuit diagnosis on 1, 2, 4 or more LED arrays.

It can also be said that the present invention provides an ambient light on-short circuit diagnosis circuit, which includes a control unit and one or more detection circuits (for example, detection circuits 110, 120, 130), wherein each detection circuit (for example, detection circuit 110, 120, 130), all include a first voltage divider circuit 112, a second voltage divider circuit 114, a first diode unit 116 and a second diode unit 118, and the first diode unit 116 includes m diodes (for example, diodes D1, D2, D3), the anodes of the m diodes (for example, diodes D1, D2, D3) are respectively connected to m in a corresponding LED array (for example, LED array 210, 220, 230). The detection points (for example, detection points a, b, c) are connected, and the cathodes of the m diodes (for example, diodes D1, D2, D3) are all connected to the first connection node A; the second diode unit 118 includes another m diodes (for example, diodes D4, D5, D6), and the cathodes of other m diodes (for example, diodes D4, D5, D6) are respectively connected to the m detection points (for example, detection point a) in the corresponding LED array 110 , b, c) are connected, and the anodes of other m diodes (for example, diodes D4, D5, D6) are all connected to the second connection node B; the input end of the first voltage divider circuit 112 is connected to the first connection node A, and its The output terminal is used as the first diagnosis node C of the detection circuit 110 where it is located; the input terminal of the second voltage divider circuit 114 is connected with the second connection node B, and its output terminal is used as the second diagnosis node D of the detection circuit where it is located; The unit diagnoses the corresponding The open-short circuit fault of the light-emitting diode array (for example, light-emitting diode array 210, 220, 230), wherein, m is a positive integer.

Correspondingly, each light emitting diode array (for example, light emitting diode array 210, 220, 230) includes m LED lamps (for example, each LED lamp 211, 212, 213) and m constant current sources (for example, constant current source 214, 215, 216), one end of each LED lamp (for example, each LED lamp 211, 212, 213) is connected to the power supply terminal voltage VCC of the LED array (for example, LED array 210, 220, 230) where it is located , the other end of which is grounded through the corresponding constant current source (for example, constant current source 214, 215, 216); each LED lamp (for example, each LED lamp 211, 212, 213) and the corresponding constant current source (for example, The connection node between constant current sources 214, 215, 216) is called a detection point (for example, detection point a, b, c) in the LED array (for example, LED array 210, 220, 230) where it is located .

According to another aspect of the present invention, the present invention provides an open-short circuit diagnosis method based on the ambient light open-short circuit diagnosis circuit shown in FIG. 1 , please refer to FIG. 4 , which is the ambient light in an embodiment of the present invention. A flowchart of an open-short circuit diagnosis method of an open-short circuit diagnosis circuit. The open-short circuit diagnosis method of the ambient light open-short circuit diagnosis circuit shown in FIG. 4 includes the following steps.

Step 410, the control unit stores the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit 110, 120, 130 sampled for the first time as a diagnostic reference voltage Vadc1 in the memory;

Step 420, the control unit takes the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit 110, 120, 130 sampled in real time as the diagnostic detection voltage Vadc2, and calculates the diagnostic detection voltage Vadc2 and The difference of the corresponding diagnostic reference voltage Vadc1;

Step 430, when the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the first predetermined fluctuation range, it is determined that the corresponding LED arrays 210, 220, 230 have no open circuit or short circuit fault;

Step 440, when the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the second predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that the corresponding LED array 210, 220, 230 has an open-circuit fault;

Step 450 , when the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within the third predetermined fluctuation range outside the first predetermined fluctuation range, determine that the corresponding LED array 210 , 220 , 230 has a short circuit fault.

In one embodiment, during the open-short circuit diagnosis period, the control unit also stores the first power supply voltage VCC of each LED array 210, 220, 230 initially sampled in the memory as a reference power supply voltage VCC1, and stores each real-time sampled The first power supply voltage VCC of each light-emitting diode array 210, 220, 230 is used as the detection power supply voltage VCC2. When the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within the fourth predetermined fluctuation range, the corresponding light-emitting diode array 210, 220, 230 perform open and short circuit diagnosis.

In a preferred embodiment, the sampled (for example, initial sampling or real-time sampling) voltage of the first diagnostic node C, voltage of the second diagnostic node D and the first power supply voltage VCC are delayed and filtered.

In summary, the present invention utilizes the forward conduction characteristic of the diode, and the voltage detected by the ADC will change when the RGB is open-circuited or short-circuited; Diagnosis, so that not only can reliably distinguish RGB open circuit and short circuit faults, but also reduce the use of MCU peripherals, simple and reliable.

It should be pointed out that any changes made by those skilled in the art to the specific embodiments of the present invention will not depart from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited only to the foregoing specific embodiments.

Claims (13)

1. An ambient light on-short circuit diagnostic circuit, characterized in that it includes a control unit and one or more detection circuits, wherein each detection circuit includes a first voltage divider circuit, a second voltage divider circuit, a first two pole unit and a second diode unit, The first diode unit includes m diodes, the anodes of the m diodes are respectively connected to the m detection points in a corresponding LED array, and the cathodes of the m diodes are all connected to the first connection node A connected; The second diode unit includes another m diodes, the cathodes of the other m diodes are respectively connected to the m detection points in the corresponding light-emitting diode array, and the anodes of the other m diodes are all connected to the second connection node B; The input end of the first voltage divider circuit is connected to the first connection node A, and its output end serves as the first diagnosis node C of the detection circuit where it is located; The input end of the second voltage divider circuit is connected to the second connection node B, and its output end serves as the second diagnostic node D of the detection circuit where it is located; The control unit samples the voltages of the first diagnostic node C and the second diagnostic node D of each detection circuit, and diagnoses the corresponding light-emitting diode array on and off based on the voltages of the first diagnostic node C and the second diagnostic node D. short circuit, Among them, m is a positive integer. 2. The ambient light on-short-circuit diagnosis circuit according to claim 1, characterized in that: The first voltage dividing circuit includes a resistor R2 and a resistor R1, and the resistor R2 and the resistor R1 are sequentially connected in series between the first connection node A and the ground terminal; the connection node between the resistor R2 and the resistor R1 is called a first diagnostic node C of said detection circuit in which it is located; The second voltage divider circuit includes a resistor R3, a resistor R7 and a resistor R8, the resistor R3 is connected between the first power supply voltage VCC and the second connection node B; the resistor R8 and the resistor R7 are sequentially connected in series to the between the second connection node B and the ground; the connection node between the resistors R7 and R8 is called the second diagnosis node D of the detection circuit where it is located. 3. The ambient light on-short circuit diagnostic circuit according to claim 2, further comprising a multiplexing switch, The multiplexing switch connects the first diagnosis node C and the second diagnosis node D of each detection circuit to the input interface Vadc of the same analog-to-digital converter in time division; The control unit samples the voltages of the first diagnosis node C and the second diagnosis node D of each detection circuit one by one through the analog-to-digital converter and the multiplexing switch. 4. The ambient light on-short-circuit diagnostic circuit according to claim 1, wherein the light-emitting diode array includes m LED lights and m constant current sources, One end of each LED lamp is connected to the power supply terminal voltage VCC of the LED array where it is located, and the other end is grounded through a corresponding constant current source; The connection node between each LED lamp and the corresponding constant current source is called a detection point in the LED array where it is located. 5. The ambient light on-short circuit diagnostic circuit according to claim 4, characterized in that: Each LED lamp includes n light-emitting diodes connected in series in sequence, Wherein, n is a positive integer. 6. The ambient lamp open-short circuit diagnostic circuit according to claim 4, characterized in that: The constant current source includes a resistor R4, a resistor R9, a resistor R10, a transistor Q1 and a transistor Q4, The first connection terminal of the triode Q1 is connected to the second power supply voltage VDD through the resistor R4, the second connection terminal thereof is grounded through the resistor R9, and the control terminal thereof is connected to the first connection terminal; The first connection terminal of the triode Q4 is connected to the detection point corresponding to the constant current source where it is located, the second connection terminal thereof is grounded through the resistor R10, and the control terminal thereof is connected to the control terminal of the triode Q1. 7. The ambient light on-short circuit diagnostic circuit according to claim 6, characterized in that: The transistor Q1 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q1 are respectively the collector, the emitter and the base of the NPN transistor; The transistor Q4 is an NPN transistor, and the first connection terminal, the second connection terminal and the control terminal of the transistor Q4 are respectively the collector, the emitter and the base of the NPN transistor. 8. The ambient light on-short-circuit diagnostic circuit according to any one of claims 1-7, characterized in that, The control unit stores the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit sampled for the first time as a diagnostic reference voltage Vadc1 in the memory, and the real-time sampled voltage of each detection circuit The difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D is used as a diagnostic detection voltage Vadc2, and the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is calculated; When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a first predetermined fluctuation range, it is determined that no open circuit or short circuit fault occurs in the corresponding LED array; When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a second predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that an open circuit fault has occurred in the corresponding LED array , When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a third predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that a short-circuit fault has occurred in the corresponding LED array . 9. The ambient light on-short circuit diagnostic circuit according to claim 8, characterized in that: During open-short circuit diagnosis, the control unit also stores the initially sampled first power supply voltage VCC of each of the light-emitting diode arrays in the memory as a reference power supply voltage VCC1, and stores the real-time sampled first power supply voltage VCC of each of the light-emitting diode arrays. The first power supply voltage VCC is used as the detection power supply voltage VCC2, and when the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within a fourth predetermined fluctuation range, open-short circuit diagnosis is performed on the corresponding LED array. 10. The ambient light on-short circuit diagnostic circuit according to claim 9, characterized in that: Delaying and filtering are performed on the sampled voltage of the first diagnostic node C, the voltage of the second diagnostic node D, and the first power supply voltage VCC. 11. An open-short circuit diagnosis method based on the ambient light open-short circuit diagnosis circuit according to any one of claims 1-10, characterized in that it comprises: The control unit stores the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit sampled for the first time as a diagnostic reference voltage Vadc1 in the memory; The control unit uses the difference between the voltage of the first diagnosis node C and the voltage of the second diagnosis node D of each detection circuit sampled in real time as the diagnosis detection voltage Vadc2, and calculates the difference between the diagnosis detection voltage Vadc2 and the corresponding The difference of the diagnostic reference voltage Vadc1; When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a first predetermined fluctuation range, it is determined that no open circuit or short circuit fault occurs in the corresponding LED array; When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a second predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that an open circuit fault has occurred in the corresponding LED array ; When the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1 is within a third predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that a short-circuit fault has occurred in the corresponding LED array . 12. The open-short circuit diagnosis method according to claim 11, further comprising: During open-short circuit diagnosis, the control unit also stores the initially sampled first power supply voltage VCC of each of the light-emitting diode arrays in the memory as a reference power supply voltage VCC1, and stores the real-time sampled first power supply voltage VCC of each of the light-emitting diode arrays. The first power supply voltage VCC is used as the detection power supply voltage VCC2, and when the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within a fourth predetermined fluctuation range, open-short circuit diagnosis is performed on the corresponding LED array. . 13. The open-short circuit diagnosis method according to claim 12, characterized in that, Delaying and filtering are performed on the sampled voltage of the first diagnostic node C, the voltage of the second diagnostic node D, and the first power supply voltage VCC.

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