A reliable open / short circuit diagnostic circuit for ambient lights and its diagnostic method

Abstract

This invention provides a reliable open / short circuit diagnostic circuit and method for ambient lighting. The ambient lighting open / short circuit diagnostic circuit includes a control unit and one or more detection circuits. Each detection circuit includes a first and a second voltage divider circuit, a first and a second diode unit. The first diode unit includes m diodes, the cathodes of which are all connected to a first connection node A. The second diode unit includes another m diodes, the anodes of which are all connected to a 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 serves as the first diagnostic node C of the detection circuit. The input terminal of the second voltage divider circuit is connected to the second connection node B, and its output terminal serves as the second diagnostic node D of the detection circuit. The control unit diagnoses the open / short circuit of the corresponding LED array based on the voltage of the first diagnostic node C and the second diagnostic node D.

Description

[Technical Field]

[0001] This invention relates to the field of vehicle ambient lighting testing technology, and in particular to a reliable ambient lighting open / short circuit diagnostic circuit and its open / short circuit diagnostic method. [Background Technology]

[0002] Nowadays, the diagnostic requirements for open and short circuits in automotive ambient lighting are becoming increasingly stringent. Traditional methods such as equivalent power supply and resistor voltage division have significant drawbacks. Considering the wide range of input voltage and temperature fluctuations, as well as the differences in the BIN regions of RGB LEDs and the errors in their PN junction voltage drops, it is impossible to detect open circuits in green and blue LEDs under low voltage and low temperature conditions. This is also a long-standing problem that traditional discrete components cannot distinguish between open and short circuits. Even with software algorithm improvements, it is only possible to differentiate open and short circuit thresholds by compressing the input voltage.

[0003] Therefore, it is necessary to propose a new technical solution to address the above problems. [Summary of the Invention]

[0004] One of the objectives of this invention is to provide a reliable ambient light open / short circuit diagnostic circuit and its open / short circuit diagnostic method, which can reliably detect open / short circuit problems in RGB (Red, Green, Blue) circuits. Factors such as the RGB BIN area, temperature, and input voltage have no effect on the detection.

[0005] According to one aspect of the present invention, an ambient light open / short circuit diagnostic circuit is provided, comprising a control unit and one or more detection circuits. 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, the anodes of which are respectively connected to m detection points in a corresponding LED array, and the cathodes of which are all connected to a first connection node A. The second diode unit includes another m diodes, the cathodes of which are respectively connected to the m detection points in the corresponding LED array, and the anodes of which are all connected to a 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 serves as the first diagnostic node C of the detection circuit to which it belongs. The input terminal of the second voltage divider circuit is connected to the second connection node B, and its output terminal serves as the second diagnostic node D of the detection circuit to which it belongs. 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 open / short circuit of the corresponding LED array based on the voltages of the first diagnostic node C and the second diagnostic node D, where m is a positive integer.

[0006] 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, comprising: the control unit storing the difference between the voltage of the first diagnostic node C and the voltage of the second diagnostic node D of each detection circuit initially sampled as a diagnostic reference voltage Vadc1 in a memory; the control unit storing 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 in real time as a diagnostic detection voltage Vadc2, and calculating the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1; the difference between the diagnostic detection voltage Vadc2 and the corresponding... When the difference between the diagnostic reference voltage Vadc1 and the diagnostic reference voltage Vadc1 is within a first predetermined fluctuation range, it is determined that the corresponding LED array has not experienced an open circuit or short circuit fault. 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 the corresponding LED array has experienced an open circuit fault. 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 the corresponding LED array has experienced a short circuit fault.

[0007] Compared with existing technologies, this invention utilizes the characteristics of diodes. When RGB is open-circuited or short-circuited, the anode voltage of the diode will change significantly. By using this change in combination with the corresponding detection strategy, the open-circuit and short-circuit problems of RGB are solved from the source. Factors such as the RGB BIN area, temperature, and input voltage have no effect on the detection. [Attached Image Description]

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0009] Figure 1 This is a circuit diagram of an ambient light open / short circuit diagnostic circuit in one embodiment of the present invention;

[0010] Figure 2 For the purposes of this invention Figure 1 An enlarged schematic diagram of the first detection circuit and the first light-emitting diode array shown;

[0011] Figure 3 For the purposes of this invention Figure 1 An enlarged schematic diagram of the multiplexer shown;

[0012] Figure 4This is a flowchart of an open / short circuit diagnosis method for an ambient light open / short circuit in one embodiment of the present invention.

Detailed Implementation Methods

[0013] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms coupling, connection, linking, and interconnection used herein to indicate electrical connection mean direct or indirect connection. For example, A being connected to B includes both a direct electrical connection between A and B and a connection between A and B via electrical components or circuits.

[0015] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0016] To address the inability to distinguish between open and short circuit thresholds in the aforementioned background technology, this invention utilizes the characteristics of a diode. When an RGB circuit is open or short-circuited, the diode's anode voltage will change significantly. By combining this change with a corresponding detection strategy, the open and short circuit problem of RGB is solved at its source. Factors such as the RGB BIN area, temperature, and input voltage have no impact on the detection.

[0017] According to one aspect of the present invention, an ambient light open / short circuit diagnostic circuit is provided. Please refer to... Figure 1 As shown, it is a circuit diagram of an ambient light open / short circuit diagnostic circuit in one embodiment of the present invention. Figure 1 The ambient light open / short circuit diagnostic circuit shown includes a first detection circuit 110, a second detection circuit 120, a third detection circuit 130, and a control unit (not shown). The first detection circuit 110 is connected to the corresponding first light-emitting diode array 210, the second detection circuit 120 is connected to the corresponding second light-emitting diode array 220, and the third detection circuit 130 is connected to the corresponding third light-emitting diode array 230.

[0018] Please refer to Figure 2As shown, it is the present invention as follows. Figure 1 An enlarged schematic diagram of the first detection circuit and the first light-emitting diode array is shown. Figure 1 and Figure 2 In the illustrated embodiment, the first detection circuit 110 includes a first voltage divider circuit 112, a second voltage divider circuit 114, a first diode unit 116, and a second diode unit 118. The first diode unit 116 includes three diodes D1, D2, and D3. The anodes of the three diodes D1, D2, and D3 are connected to three detection points a, b, and c in the corresponding first light-emitting diode array 210, respectively. 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. The cathodes of the three diodes D4, D5, and D6 are connected to three detection points a, b, and c in the corresponding first light-emitting diode array 210, respectively. The anodes of the three diodes D4, D5, and D6 are all connected to the second connection node B. The input terminal of the first voltage divider circuit 112 is connected to the first connection node A, and its output terminal serves as the first diagnostic node C. The input terminal of the second voltage divider circuit 114 is connected to the second connection node B, and its output terminal serves as the second diagnostic node D.

[0019] exist Figure 1 and Figure 2 In the specific embodiment shown, the first voltage divider circuit 112 includes resistors R2 and R1, which are connected in series between the first connection node A and the ground terminal; the connection node between resistors R2 and R1 is called the first diagnostic node C of the first detection circuit 110. The second voltage divider circuit 114 includes resistors R3, R7, and R8, with resistor R3 connected between the first power supply voltage VCC and the second connection node B; resistors R8 and R7 are connected in series between the second connection node B and the ground terminal; the connection node between resistors R7 and R8 is called the second diagnostic node D of the first detection circuit 110.

[0020] exist Figure 1 and Figure 2In the specific embodiment shown, the first light-emitting diode array 210 includes three LEDs 211, 212, and 213, and three constant current sources 214, 215, and 216. One end of each LED 211, 212, and 213 is connected to the first power supply voltage VCC, and the other end is grounded via the corresponding constant current source 214, 215, and 216. The connection node between each LED 211, 212, and 213 and its corresponding constant current source 214, 215, and 216 is called a detection point a, b, or c of the first light-emitting diode array 210 to which it belongs. For example, one end of the first LED 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 211 and the first constant current source 214 is called the first detection point a of the first LED array 210; one end of the second LED 212 is connected to the first power supply voltage VCC, and the other end is grounded through the second constant current source 215. The connection node between the second LED 212 and the second constant current source 215 is called the second detection point b of the first LED array 210; one end of the third LED 213 is connected to the first power supply voltage VCC, and the other end is grounded through the third constant current source 216. The connection node between the third LED 213 and the third constant current source 216 is called the third detection point c of the first LED array 210.

[0021] exist Figure 1 and Figure 2 In the specific embodiment shown, the first LED light 211 includes two light-emitting diodes LED1 and LED4 connected in series; the second LED light 212 includes two light-emitting diodes LED2 and LED5 connected in series; and the third LED light 213 includes two light-emitting diodes LED3 and LED6 connected in series. In other embodiments, each LED light 211, 212, and 213 may include one, three, four, or more light-emitting diodes, that is, each LED light 211, 212, and 213 includes n light-emitting diodes connected in series, where n is a positive integer.

[0022] exist Figure 1 and Figure 2 In the illustrated embodiment, the first constant current source 214 includes resistors R4, R9, and R10, and transistors Q1 and Q4. The first terminal of transistor Q1 is connected to the second power supply voltage VDD via resistor R4, its second terminal is grounded via resistor R9, and its control terminal is connected to its first terminal. The first terminal of transistor Q4 is connected to the detection point a corresponding to the first constant current source 214, its second terminal is grounded via resistor R10, and its control terminal is connected to the control terminal of transistor Q1. Figure 1 and Figure 2In the specific embodiment shown, transistor Q1 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q1 are the collector, emitter, and base of the NPN transistor, respectively; transistor Q4 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q4 are the collector, emitter, and base of the NPN transistor, respectively.

[0023] exist Figure 1 In the illustrated embodiment, the second constant current source 215 has the same circuit structure as the first constant current source 214. The second constant current source 215 includes resistors R5, R11, and R12, and transistors Q2 and Q5. The first terminal of transistor Q2 is connected to the second power supply voltage VDD via resistor R5, and its second terminal is grounded via resistor R11. Its control terminal is connected to its first terminal. The first terminal of transistor Q5 is connected to the detection point b corresponding to the second constant current source 215, its second terminal is grounded via resistor R12, and its control terminal is connected to the control terminal of transistor Q2. Figure 1 In the specific embodiment shown, transistor Q2 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q2 are the collector, emitter, and base of the NPN transistor, respectively; transistor Q5 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q5 are the collector, emitter, and base of the NPN transistor, respectively.

[0024] exist Figure 1 In the illustrated embodiment, the circuit structure of the third constant current source 216 is identical to that of the first constant current source 214. The third constant current source 216 includes resistors R6, R13, and R14, and transistors Q3 and Q6. The first terminal of transistor Q3 is connected to the second power supply voltage VDD via resistor R6, its second terminal is grounded via resistor R13, and its control terminal is connected to its first terminal. The first terminal of transistor Q6 is connected to the detection point c corresponding to the third constant current source 216, its second terminal is grounded via resistor R14, and its control terminal is connected to the control terminal of transistor Q3. Figure 1 In the specific embodiment shown, transistor Q3 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q3 are the collector, emitter, and base of the NPN transistor, respectively; transistor Q6 is an NPN transistor, and the first connection terminal, the second connection terminal, and the control terminal of transistor Q6 are the collector, emitter, and base of the NPN transistor, respectively.

[0025] It should be noted that the circuit structures of the second detection circuit 120 and the third detection circuit 130 are consistent with the circuit structure of the first detection circuit 110; the circuit structures of the second light-emitting diode array 220 and the third light-emitting diode array 230 are consistent with the circuit structure of the first light-emitting diode array 210; the circuit connection relationship of the second detection circuit 120 and the second light-emitting diode array 220 is consistent with the circuit connection relationship of the first detection circuit 110 and the first light-emitting diode array 210; the circuit connection relationship of the third detection circuit 130 and the third light-emitting 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 repeated here.

[0026] The control unit (e.g., MCU) diagnoses open / short circuits in the corresponding LED arrays 210, 220, 230 by sampling the voltages of the first diagnostic node C and the second diagnostic node D of each detection circuit 110, 120, 130, and based on the voltages of the first diagnostic node C and the second diagnostic node D. Figure 1 In the illustrated embodiment, the first LED array 210, the second LED array 220, and the third LED array 230 form an RGB array. For example, the first LED array 210 is a red LED array; the second LED array 220 is a green LED array; and the third LED array 230 is a blue LED array.

[0027] Figure 1 The ambient light open / short circuit diagnostic circuit shown also includes a multiplexer 140. The multiplexer 140 connects the first diagnostic node C and the second diagnostic node D of each detection circuit 110, 120, and 130 to the same analog-to-digital converter (not shown) input interface Vadc in a time-division manner. The control unit samples the voltage of the first diagnostic node C and the second diagnostic node D of each detection circuit 110, 120, and 130 sequentially through this analog-to-digital converter (not shown) and the multiplexer 140. Please refer to... Figure 3 As shown, it is the present invention as follows. Figure 1 An enlarged schematic diagram of the multiplexer switch is shown. Figure 1 and Figure 3As shown, the input interfaces S0 and S1 of the multiplexer 140 are connected to the first diagnostic node C and the second diagnostic node D of the first detection circuit 110, respectively; its input interfaces S2 and S3 are connected to the first diagnostic node C and the second diagnostic node D of the second detection circuit 120, respectively; its input interfaces S4 and S5 are connected to the first diagnostic node C and the second diagnostic node D of the third detection circuit 130, respectively; its power interface VDD is connected to the second power supply voltage VDD; its output interface D is grounded in sequence through voltage divider resistors R43 and R44; and the input interface Vadc of the analog-to-digital converter (not shown) is connected to the connection node between voltage divider resistors R43 and R44.

[0028] The following is a detailed introduction Figure 1 The design principle of the ambient light open / short circuit diagnostic circuit is shown.

[0029] I. Hardware Principles, taking the first detection circuit 110 and the first light-emitting diode array 210 as an example.

[0030] 1. Under normal operating conditions, the first power supply voltage VCC (i.e., input voltage VCC) passes through the first LED array 210 to the constant current sources 214, 215 and 216. Diodes D1, D2 and D3 share a common cathode, and 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 maximum voltage minus the voltage difference of the diode.

[0031] 2. At the same time, the anode voltage of diodes D4, D5, and D6 is 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 plus the voltage difference of one diode.

[0032] 3. After passing through common anode and common cathode diodes, a resistor voltage divider is used to reach the channel of Tmux1308-Q1 for polling ADC sampling;

[0033] 4. When the first LED array 210 is short-circuited, the highest voltage among the three voltages will be raised by the voltage of one LED. After being divided by diodes and resistors, the voltage is sampled by the analog-to-digital converter (ADC), which will detect the voltage rise at the first diagnostic node C and report a short circuit.

[0034] 5. When the first LED array 210 is open-circuited, the lowest voltage among the three voltages will appear in the faulty path. The anode voltages of D4, D5, and D6 will be significantly lower than normal. The voltage of the second diagnostic node D will be detected as significantly lower, and an open circuit will be reported.

[0035] II. Working Principle

[0036] 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 initially as a diagnostic reference voltage Vadc1 in the memory, and 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 in real time as a diagnostic detection voltage Vadc2, and calculates the difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1.

[0037] 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 LED arrays 210, 220, and 230 have not experienced open-circuit or short-circuit faults.

[0038] 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 arrays 210, 220, and 230 have an open circuit fault.

[0039] 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 the corresponding LED arrays 210, 220, and 230 have a short circuit fault.

[0040] 5. During the open / short circuit diagnosis, the control unit will also store the first power supply voltage VCC of each LED array 210, 220, 230 sampled initially as the reference power supply voltage VCC1 in the memory, and use the first power supply voltage VCC of each LED array 210, 220, 230 sampled in real time as the detection power supply voltage VCC2. Only when the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within the fourth predetermined fluctuation range will the corresponding LED array 210, 220, 230 be subjected to open / short circuit diagnosis.

[0041] In a preferred embodiment, the voltage of the first diagnostic node C, the voltage of the second diagnostic node D, and the first power supply voltage VCC are sampled (e.g., initial sampling or real-time sampling) and then delayed and filtered.

[0042] It should be noted that, in Figure 1 In the illustrated embodiment, there are three detection circuits 110, 120, and 130, and three light-emitting diode arrays. Figure 1The ambient light open / short circuit shown can perform open / short circuit diagnosis on RGB. In other embodiments, the detection circuit can be one, two, four or more, and the corresponding LED array can also be one, two, four or more, and the corresponding ambient light open / short circuit can perform open / short circuit diagnosis on one, two, four or more LED arrays.

[0043] Alternatively, the present invention provides an ambient light open / short circuit diagnostic circuit, which includes a control unit and one or more detection circuits (e.g., detection circuits 110, 120, 130). Each detection circuit (e.g., detection circuits 110, 120, 130) includes a first voltage divider circuit 112, a second voltage divider circuit 114, a first diode unit 116, and a second diode unit 118. The first diode unit 116 includes m diodes (e.g., diodes D1, D2, D3). The anodes of the m diodes (e.g., diodes D1, D2, D3) are respectively connected to m detection points (e.g., detection points a, b, c) in a corresponding LED array (e.g., LED arrays 210, 220, 230). The cathodes of the m diodes (e.g., diodes D1, D2, D3) are all connected to a first connection node A. The second diode unit 118 includes another m diodes (e.g., diodes D4, D5, D6). The cathodes of the additional m diodes (e.g., diodes D4, D5, D6) are connected to the m detection points (e.g., detection points a, b, c) in the corresponding LED array 110, and the anodes of the additional m diodes (e.g., diodes D4, D5, D6) are all connected to the second connection node B; the input of the first voltage divider circuit 112 is connected to the first connection node A, and its output serves as the first diagnostic node C of the detection circuit 110 to which it belongs; the input of the second voltage divider circuit 114 is connected to the second connection node B, and its output serves as the second diagnostic node D of the detection circuit to which it belongs; the control unit samples the voltage of the first diagnostic node C and the second diagnostic node D of each detection circuit (e.g., detection circuits 110, 120, 130), and diagnoses the open and short circuit faults of the corresponding LED arrays (e.g., LED arrays 210, 220, 230) based on the voltage of the first diagnostic node C and the second diagnostic node D, where m is a positive integer.

[0044] Correspondingly, each LED array (e.g., LED arrays 210, 220, 230) includes m LEDs (e.g., each LED 211, 212, 213) and m constant current sources (e.g., constant current sources 214, 215, 216). One end of each LED (e.g., each LED 211, 212, 213) is connected to the power supply voltage VCC of the LED array (e.g., LED arrays 210, 220, 230) it belongs to, and the other end is grounded through the corresponding constant current source (e.g., constant current source 214, 215, 216). The connection node between each LED (e.g., each LED 211, 212, 213) and the corresponding constant current source (e.g., constant current source 214, 215, 216) is called a detection point (e.g., detection point a, b, c) in the LED array (e.g., LED arrays 210, 220, 230) it belongs to.

[0045] According to another aspect of the present invention, the present invention provides a method based on Figure 1 For the open / short circuit diagnostic method of the ambient light shown, please refer to [reference needed]. Figure 4 The diagram shown is a flowchart of an open / short circuit diagnosis method for an ambient light open / short circuit in one embodiment of the present invention. Figure 4 The open / short circuit diagnosis method for the ambient light diagnostic circuit shown includes the following steps.

[0046] 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 of the initial sampling detection circuits 110, 120, and 130 as the diagnostic reference voltage Vadc1 in the memory.

[0047] Step 420: The control unit takes the voltage difference between the first diagnostic node C and 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 difference between the diagnostic detection voltage Vadc2 and the corresponding diagnostic reference voltage Vadc1.

[0048] 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 light-emitting diode arrays 210, 220, and 230 have not experienced open-circuit or short-circuit faults.

[0049] 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 light-emitting diode arrays 210, 220, and 230 have an open-circuit fault.

[0050] 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, it is determined that the corresponding light-emitting diode arrays 210, 220, and 230 have a short-circuit fault.

[0051] In one embodiment, during open / short circuit diagnosis, the control unit also stores the first power supply voltage VCC of each LED array 210, 220, 230 sampled initially as a reference power supply voltage VCC1 in the memory, and uses the first power supply voltage VCC of each LED array 210, 220, 230 sampled in real time as a detection power supply voltage VCC2. Only 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 210, 220, 230.

[0052] In a preferred embodiment, the voltage of the first diagnostic node C, the voltage of the second diagnostic node D, and the first power supply voltage VCC are sampled (e.g., initial sampling or real-time sampling) and then delayed and filtered.

[0053] In summary, this invention utilizes the forward conduction characteristics of a diode, and the voltage detected by the ADC changes when RGB is open or short-circuited. This invention also employs a multiplexed switch for polling sampling to determine the changes in the ADC sampling value before and after sampling and make a diagnosis. This not only reliably distinguishes between open and short-circuit faults in RGB, but also reduces the use of MCU peripherals, making it simple and reliable.

[0054] It should be noted that any modifications made by those skilled in the art to the specific embodiments of the present invention do not depart from the scope of the claims. Accordingly, the scope of the claims is not limited to the foregoing specific embodiments.

Claims

1. An ambient light open-short diagnostic circuit, comprising: It comprises a control unit and one or more detection circuits, wherein each detection circuit comprises a first voltage dividing circuit, a second voltage dividing circuit, a first diode unit and a second diode unit, The first diode unit comprises m diodes, the anodes of which are connected to m detection points in a corresponding light emitting diode array, and the cathodes of which are connected to a first connection node A; The second diode unit comprises another m diodes, the cathodes of which are connected to the m detection points in the corresponding light emitting diode array, and the anodes of which are connected to a second connection node B; The input end of the first voltage dividing circuit is connected to the first connection node A, and its output end is a first diagnostic node C of the detection circuit in which it is located; The input end of the second voltage dividing circuit is connected to the second connection node B, and its output end is a second diagnostic node D of the detection circuit in which it is located; The control unit diagnoses the open / short circuit of the corresponding light emitting diode array by sampling the voltages of the first diagnostic node C and the second diagnostic node D of each detection circuit, and diagnosing the voltages of the first diagnostic node C and the second diagnostic node D, wherein m is a positive integer.

2. The open / short circuit diagnosis circuit of the ambient light according to claim 1, wherein The first voltage dividing circuit comprises a resistor R2 and a resistor R1, which are connected in series between the first connection node A and the ground; the connection node between the resistor R2 and the resistor R1 is referred to as the first diagnostic node C of the detection circuit in which it is located; The second voltage dividing circuit comprises 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 connected in series between the second connection node B and the ground; the connection node between the resistor R7 and the resistor R8 is referred to as the second diagnostic node D of the detection circuit in which it is located.

3. The ambiance lamp open-short diagnostic circuit of claim 2, wherein, It further comprises a multiplexing switch, The multiplexing switch connects the first diagnostic node C and the second diagnostic node D of each detection circuit to the input interface Vadc of the same analog-to-digital converter in time sharing mode; The control unit samples the voltages of the first diagnostic node C and the second diagnostic node D of each detection circuit through the analog-to-digital converter and the multiplexing switch.

4. The ambiance lamp open-short diagnostic circuit of claim 1, wherein, The light emitting diode array comprises m LED lights and m constant current sources, One end of each LED light is connected to the power supply end voltage VCC of the light emitting diode array in which it is located, and the other end is grounded through a corresponding constant current source; The connection node between each LED light and the corresponding constant current source is referred to as a detection point in the light emitting diode array in which it is located.

5. The open / short circuit diagnosis circuit of the ambient light according to claim 4, wherein Each LED light comprises n light emitting diodes connected in series, wherein n is a positive integer.

6. The open / short circuit diagnosis circuit of the ambient light according to claim 4, wherein The constant current source comprises a resistor R4, a resistor R9, a resistor R10, a transistor Q1 and a transistor Q4, The first connection end of the transistor Q1 is connected with the second power supply voltage VDD through the resistor R4, the second connection end is grounded through the resistor R9, and the control end is connected with the first connection end; The first connection end of the transistor Q4 is connected with the corresponding detection point of the constant current source, the second connection end is grounded through the resistor R10, and the control end is connected with the control end of the transistor Q1.

7. The open / short circuit diagnosis circuit of the ambient light according to claim 6, wherein, The transistor Q1 is an NPN transistor, and the first connection end, the second connection end and the control end of the transistor Q1 are the collector, the emitter and the base of the NPN transistor respectively; The transistor Q4 is an NPN transistor, and the first connection end, the second connection end and the control end of the transistor Q4 are the collector, the emitter and the base of the NPN transistor respectively.

8. The open / short circuit diagnosis circuit of the ambient light according to any one of claims 1-7, wherein, The control unit stores the difference between the voltage of the first diagnosis node C and the voltage of the second diagnosis node D of each detection circuit in the initial sampling as the diagnosis reference voltage Vadc1 in the memory, stores the difference between the voltage of the first diagnosis node C and the voltage of the second diagnosis node D of each detection circuit in the real-time sampling as the diagnosis detection voltage Vadc2, and calculates the difference between the diagnosis detection voltage Vadc2 and the corresponding diagnosis reference voltage Vadc1; When the difference between the diagnosis detection voltage Vadc2 and the corresponding diagnosis reference voltage Vadc1 is within the first predetermined fluctuation range, it is determined that the corresponding light-emitting diode array has no open circuit or short circuit failure; When the difference between the diagnosis detection voltage Vadc2 and the corresponding diagnosis reference voltage Vadc1 is within the second predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that the corresponding light-emitting diode array has an open circuit failure, When the difference between the diagnosis detection voltage Vadc2 and the corresponding diagnosis reference voltage Vadc1 is within the third predetermined fluctuation range outside the first predetermined fluctuation range, it is determined that the corresponding light-emitting diode array has a short circuit failure.

9. The open / short circuit diagnosis circuit of the ambient light according to claim 8, wherein, During the open / short circuit diagnosis, the control unit also stores the first power supply voltage VCC of each light-emitting diode array in the initial sampling as the reference power supply voltage VCC1 in the memory, stores the first power supply voltage VCC of each light-emitting diode array in the real-time sampling as the detection power supply voltage VCC2, and only performs the open / short circuit diagnosis on the corresponding light-emitting diode array when the difference between the detection power supply voltage VCC2 and the reference power supply voltage VCC1 is within the fourth predetermined fluctuation range.

10. The open / short circuit diagnosis circuit of the ambient light according to claim 9, wherein, The sampled voltage of the first diagnostic node C, the voltage of the second diagnostic node D and the first power voltage VCC are delayed and filtered.

11. An open / short circuit diagnosis method for an ambient light open / short circuit diagnosis circuit according to any one of claims 1 to 10, characterized by, 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 in the initial sampling as a diagnostic reference voltage Vadc1 in the memory; 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 in the real-time sampling as a diagnostic detection voltage Vadc2, and calculates the difference between the diagnostic detection voltage Vadc2 and the corresponding 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 the corresponding LED array has no open circuit or short circuit failure; 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 the corresponding LED array has an open circuit failure; 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 the corresponding LED array has a short circuit failure.

12. The open / short circuit diagnosis method according to claim 11, characterized by, It further comprises: During the open / short circuit diagnosis, the control unit also stores the first power voltage VCC of each LED array in the initial sampling as a reference power voltage VCC1 in the memory, and stores the first power voltage VCC of each LED array in the real-time sampling as a detection power voltage VCC2. When the difference between the detection power voltage VCC2 and the reference power voltage VCC1 is within a fourth predetermined fluctuation range, the open / short circuit diagnosis is performed on the corresponding LED array.

13. The open / short circuit diagnosis method according to claim 12, wherein The sampled voltage of the first diagnostic node C, the voltage of the second diagnostic node D and the first power voltage VCC are delayed and filtered.

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