A short-circuit detection circuit and method, and a light-emitting device

Abstract

This invention provides a short-circuit detection circuit and method, as well as a light-emitting device. The short-circuit detection circuit includes a current detection circuit, a voltage detection circuit, and a logic judgment circuit. The current detection circuit acquires a current characterization signal and outputs a first current detection result when the current characterization signal is greater than a reference value. The voltage detection circuit acquires a first voltage signal at a preset position and outputs a first voltage detection result when the first voltage signal is greater than a first reference voltage. The first and second input terminals of the logic judgment circuit are respectively connected to the output terminals of the current detection circuit and the voltage detection circuit. When the first input terminal of the logic judgment circuit receives the first current detection result and both the second input terminals receive the first voltage detection result, a drive signal is output to the short-circuit protection circuit to drive the short-circuit protection circuit to activate. The short-circuit detection circuit and method provided by this invention have high detection accuracy.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a short-circuit detection circuit and method, as well as a light-emitting device. Background Technology

[0002] In the field of display technology, light-emitting diodes (LEDs) are widely used in light-emitting devices due to their advantages such as good shock resistance, high reliability and long life. Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in related technologies, such as... Figure 1 As shown, the light-emitting device includes a light-emitting circuit 01, a drive adjustment circuit 02, and a short-circuit detection circuit 03. The light-emitting circuit 01 includes three LEDs connected in series, namely LED1, LED2, and LED3. The light-emitting circuit 01 is also connected to a power converter to receive the drive voltage VOUT. The drive adjustment circuit 02 is connected to the light-emitting circuit 01 and is used to adjust the current flowing through the light-emitting circuit 01. The short-circuit detection circuit 03 is used to detect whether there is a short-circuited LED in the light-emitting circuit 01. When a short-circuited LED is detected, a short-circuit protection circuit is triggered. Figure 1 (Not shown) is turned on to provide short-circuit protection for the light-emitting device.

[0003] Figure 2 This is a schematic diagram of a short-circuit detection circuit in related technologies, such as... Figure 2 As shown, the short-circuit detection circuit includes a comparator. The negative input terminal of the comparator is used to receive a reference voltage VREF, and the positive input terminal of the comparator is connected to the cathode of LED3 to monitor the voltage VD at the output terminal of LED3. The output terminal of the comparator is connected to the short-circuit protection circuit (…). Figure 2 (Not shown) Connection. When the comparator detects that the voltage at point VD is higher than the reference voltage VREF, the output of the comparator outputs a high-level signal SCP to the short-circuit protection circuit to trigger the short-circuit protection circuit to operate.

[0004] However, the short-circuit detection circuits in related technologies have low detection accuracy and are prone to falsely triggering the short-circuit protection circuit. Summary of the Invention

[0005] The purpose of this invention is to provide a short-circuit detection circuit and method, as well as a light-emitting device, to solve the technical problem of low detection accuracy of short-circuit detection circuits in related technologies.

[0006] Firstly, to solve the above-mentioned technical problems, the present invention provides a short-circuit detection circuit, wherein the short-circuit detection circuit is connected to a light-emitting circuit, the light-emitting circuit includes a light-emitting component, the short-circuit detection circuit is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit, and the light-emitting circuit is also connected to a drive adjustment circuit, the drive adjustment circuit being used to adjust the magnitude of the current flowing through the light-emitting component, the short-circuit detection circuit comprising:

[0007] A current detection circuit, connected to the light-emitting circuit or the driving adjustment circuit, is used to acquire a current characterization signal, the value of which characterizes the current flowing through the light-emitting component; the current detection circuit is also used to: compare the value of the current characterization signal with a reference value and output a current detection signal, wherein when the value of the current characterization signal is greater than the reference value, the current detection signal is used to indicate a first current detection result; otherwise, the current detection signal is used to indicate a second current detection result.

[0008] A voltage detection circuit is provided, the input terminal of which is connected to a preset position of the light-emitting circuit, the preset position being the connection terminal between the light-emitting circuit and the driving adjustment circuit; the voltage detection circuit is used to: acquire a first voltage signal at the preset position, determine whether the first voltage signal is greater than a first reference voltage, and output a voltage detection signal, wherein when the first voltage signal is greater than the first reference voltage, the voltage detection signal is used to indicate a first voltage detection result; otherwise, the voltage detection signal is used to indicate a second voltage detection result.

[0009] A logic judgment circuit is provided, wherein the first input terminal of the logic judgment circuit is connected to the output terminal of the current detection circuit for receiving a current detection signal, the second input terminal of the logic judgment circuit is connected to the output terminal of the voltage detection circuit for receiving a voltage detection signal, and the output terminal of the logic judgment circuit is connected to a short-circuit protection circuit; the logic judgment circuit is used to: when the current detection signal obtained by the first input terminal of the logic judgment circuit indicates a first current detection result and the voltage detection signal obtained by the second input terminal indicates a first voltage detection result, output a drive signal to the short-circuit protection circuit to drive the short-circuit protection circuit to open.

[0010] Optionally, the current detection circuit is connected to the drive adjustment circuit;

[0011] The drive adjustment circuit includes a resistor, a fully differential sigma-delta modulator, an up-down counter, and a digital-to-analog converter module;

[0012] The first input terminal of the fully differential sigma-delta modulator is connected to the source of the driving transistor for sampling the source voltage of the driving transistor. The second input terminal of the fully differential sigma-delta modulator is used to receive a second reference voltage. The output terminal of the fully differential sigma-delta modulator is connected to the input terminal of the up-down counter. The output terminal of the up-down counter is connected to the input terminal of the digital-to-analog converter module. The output terminal of the digital-to-analog converter module is connected to the gate of the driving transistor. The drain of the driving transistor is connected to a preset position of the light-emitting circuit. The source of the driving transistor is also connected to one end of the resistor, and the other end of the resistor is grounded.

[0013] The value of the signal output from the output terminal of the up-down counter is positively correlated with the current value flowing through the light-emitting component.

[0014] Optionally, the first input terminal of the current detection circuit is connected to the output terminal of the up-down counter, and is used to acquire the signal output by the up-down counter in real time, and use the signal output by the up-down counter as the current characterization signal. The second input terminal of the current detection circuit is used to receive a clock signal, and the reference value is stored in the current detection circuit.

[0015] The current detection circuit is configured to: when the second input terminal of the current detection circuit receives the rising edge of the clock signal, compare the value of the current characterization signal with the reference value; when the value of the current characterization signal is greater than the reference value, output a current detection signal to indicate the first current detection result; otherwise, output a current detection signal to indicate the second current detection result.

[0016] Optionally, the reference value is the value of the signal output by the up-down counter when the current flowing through the light-emitting circuit is the product of the full-load current of the light-emitting circuit and a preset percentage.

[0017] Optionally, the preset percentage is greater than or equal to 5% and less than or equal to 15%.

[0018] Optionally, the current detection circuit is connected to the light-emitting circuit;

[0019] The current detection circuit includes:

[0020] A current sampling circuit is connected to the light-emitting circuit and is used to sample the current signal flowing through the light-emitting component in the light-emitting circuit, and convert the current signal into a second voltage signal and output it as the current characterization signal.

[0021] A comparator circuit is provided, wherein a first input terminal of the comparator circuit is connected to the output terminal of the current sampling circuit for receiving the current characterization signal, a second input terminal of the comparator circuit for receiving a third reference voltage and storing the third reference voltage as the reference value, the comparator circuit for comparing the value of the current characterization signal with the reference value, and outputting the current detection signal. When the value of the current characterization signal is greater than the reference value, the current detection signal indicates a first current detection result; otherwise, the current detection signal indicates a second current detection result.

[0022] Optionally, the current detection circuit is connected to the light-emitting circuit;

[0023] The current detection circuit includes:

[0024] A current sampling circuit is connected to the source of the driving transistor in the driving adjustment circuit. It is used to sample the source voltage signal of the driving transistor and output the source voltage signal as the current characterization signal.

[0025] A comparator circuit is provided, wherein a first input terminal of the comparator circuit is connected to the output terminal of the current sampling circuit for receiving the current characterization signal, a second input terminal of the comparator circuit for receiving a third reference voltage and storing the third reference voltage as the reference value, the comparator circuit for comparing the value of the current characterization signal with the reference value, and outputting the current detection signal. When the value of the current characterization signal is greater than the reference value, the current detection signal indicates a first current detection result; otherwise, the current detection signal indicates a second current detection result.

[0026] Optionally, the short-circuit detection circuit further includes a timing circuit, the input terminal of which is connected to the output terminal of the logic judgment circuit, and the output terminal of which is connected to the input terminal of the short-circuit protection circuit.

[0027] The timing circuit is used to: receive the drive signal output by the output terminal of the logic judgment circuit, and when the duration of the continuous output of the drive signal by the output terminal of the logic judgment circuit exceeds a preset duration, start outputting the drive signal to the short circuit protection circuit to trigger the short circuit protection circuit to open.

[0028] Secondly, the present invention also provides a short-circuit detection method performed by the aforementioned short-circuit detection circuit, the short-circuit detection method being used to detect whether a short-circuited light-emitting component exists in a light-emitting circuit including a light-emitting component, characterized in that the short-circuit detection method includes:

[0029] Acquire a current characterization signal, the current characterization signal being used to characterize the current flowing through the light-emitting component, and compare the value of the current characterization signal with a reference value; and acquire a first voltage signal at a preset position of the light-emitting circuit, the preset position being the connection terminal of the light-emitting circuit and the drive adjustment circuit; and compare the first voltage signal with a first reference voltage.

[0030] When it is determined that the value of the current characterization signal is greater than the reference value, and the first voltage signal is greater than the first reference voltage, the short-circuit protection circuit is triggered to open.

[0031] Thirdly, the present invention also provides a light-emitting device, the light-emitting device comprising at least two light-emitting units connected in parallel, each light-emitting unit comprising: a light-emitting circuit, a driving adjustment circuit, a short-circuit protection circuit, and a short-circuit detection circuit as described in the first aspect;

[0032] The light-emitting circuit includes a light-emitting component;

[0033] The driving adjustment circuit is connected to the light-emitting circuit and is used to drive the light-emitting component to emit light and to adjust the magnitude of the current flowing through the light-emitting component.

[0034] The short-circuit detection circuit is connected to the light-emitting circuit, and the short-circuit detection circuit is also connected to the short-circuit protection circuit. The short-circuit detection circuit is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit. When a short-circuited light-emitting component is detected in the light-emitting circuit, the short-circuit protection circuit is triggered to work, so as to protect the light-emitting device from short circuit.

[0035] In summary, the short-circuit detection circuit and method provided by this invention first acquires a current characterization signal representing the current flowing through the light-emitting component and a first voltage signal at a preset position of the light-emitting circuit. The value of the current characterization signal is compared with a reference value, and the first voltage signal is compared with a first reference voltage. Only when the value of the current characterization signal is greater than the reference value and the first voltage signal is greater than the first reference voltage will the short-circuit protection circuit be triggered for short-circuit protection. That is, in this invention, a short-circuited light-emitting component is determined to exist in the light-emitting circuit only when the current value flowing through the light-emitting component is determined to be large and the first voltage signal at the preset position of the light-emitting component is also large. Compared to methods that "determine whether a short-circuited light-emitting component exists in the light-emitting circuit solely based on the magnitude of the voltage value at the preset position of the light-emitting circuit," this invention has more judgment conditions and more refined judgment steps, thereby greatly improving detection accuracy and avoiding false judgments. Attached Figure Description

[0036] Figure 1This is a schematic diagram of a light-emitting device provided in related technologies;

[0037] Figure 2 This is a schematic diagram of a short-circuit detection circuit in related technologies;

[0038] Figure 3 This is a schematic diagram of a short-circuit detection circuit provided in an embodiment of the present invention;

[0039] Figure 4 A connection diagram of a short-circuit detection circuit, a light-emitting circuit, a drive adjustment circuit, and a short-circuit protection circuit provided in Embodiment 1 of the present invention;

[0040] Figure 5 This is a connection diagram of a short-circuit detection circuit, a light-emitting circuit, a drive adjustment circuit, and a short-circuit protection circuit provided in Embodiment 2 of the present invention;

[0041] Figure 6 This is a flowchart illustrating a short-circuit detection method provided in Embodiment 3 of the present invention;

[0042] Figure 7 This is a schematic diagram of the structure of a light-emitting device provided in Embodiment 4 of the present invention. Detailed Implementation

[0043] As described in the background section, the short-circuit detection circuit in the related art determines whether there is a short-circuited light-emitting component in the light-emitting circuit based solely on the voltage VD at the cathode of LED3. However, in practice, the high VD voltage can be caused by more than just LED short circuits; it can also be due to a low current flowing through the light-emitting component. For example, when the LED linear circuit is powered on, the initial current is small, resulting in a high VD voltage. At this time, LED1, LED2, and LED3 may not be short-circuited. Therefore, for the short-circuit detection circuit in the related art, if it only determines whether the LED is short-circuited based on the voltage VD, false alarms can easily occur when the current flowing through the light-emitting component is small. This can lead to false triggering of the short-circuit protection circuit, thereby affecting the normal operation of the light-emitting device.

[0044] Therefore, this invention provides a short-circuit detection circuit and method with high detection accuracy, as well as a light-emitting device. The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the short-circuit detection circuit and method, and the light-emitting device proposed by this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0045] Figure 3This is a schematic diagram of a short-circuit detection circuit provided in an embodiment of the present invention. The short-circuit detection circuit can be connected to a light-emitting circuit, which includes light-emitting components. When the light-emitting circuit includes multiple light-emitting components, the multiple light-emitting components are connected in series. The short-circuit detection circuit is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit. The light-emitting circuit is also connected to a drive adjustment circuit, which is used to adjust the current flowing through the light-emitting components. And, as... Figure 3 As shown, the short-circuit detection circuit may include:

[0046] Current detection circuit, the current detection circuit and the light-emitting circuit ( Figure 3 (not shown in the image) or drive adjustment circuit ( Figure 3 A connection (not shown) is used to acquire a current characterization signal M, the value of which characterizes the current flowing through the light-emitting component. The current detection circuit 10 is also used to compare the value of the current characterization signal M with a reference value and output a current detection signal. Wherein, when the value of the current characterization signal M is greater than the reference value, it indicates that the current flowing through the light-emitting component is large, and the current detection signal output by the current detection circuit is used to indicate a first current detection result (e.g., the current detection signal is a high-level signal); otherwise, it indicates that the current flowing through the light-emitting component is small, and the current detection signal is used to indicate a second current detection result (e.g., the current detection signal is a low-level signal).

[0047] A voltage detection circuit is included, with its input terminal connected to a preset position of the light-emitting circuit. This preset position is the connection point between the light-emitting circuit and the driving adjustment circuit. The voltage detection circuit acquires a first voltage signal VD at the preset position and determines whether the first voltage signal VD is greater than a first reference voltage VREF1 to output a voltage detection signal. Specifically, if the first voltage signal VD is greater than the first reference voltage VREF1, it indicates that the voltage at the preset position is high, and the voltage detection signal output by the voltage detection circuit indicates a first voltage detection result (e.g., a high-level signal). Otherwise, it indicates that the voltage at the preset position is low, and the voltage detection signal indicates a second voltage detection result (e.g., a low-level signal). The first reference voltage VREF1 can range from [1, 3]V, for example, it can be 2V.

[0048] Logic judgment circuit 11, the first input terminal of which is connected to the output terminal of the current detection circuit for receiving current detection signals, the second input terminal of which is connected to the output terminal of the voltage detection circuit, and the output terminal of which is connected to the short-circuit protection circuit (…). Figure 3 (Not shown) is connected to receive voltage detection signals; when the current detection signal obtained by the first input terminal of the logic judgment circuit 11 indicates the first current detection result and the voltage detection signals obtained by both the second input terminals indicate the first voltage detection result, the logic judgment circuit 11 is used to output a drive signal SCP to the short circuit protection circuit to drive the short circuit protection circuit to turn on; otherwise, no drive signal is sent to the short circuit protection circuit.

[0049] In this embodiment of the invention, the logic judgment circuit 11 can be an AND gate, the first level signal can be a high level signal, the second level signal can be a low level signal, and the driving signal can also be a high level signal.

[0050] In summary, the short-circuit detection circuit and method provided by this invention first acquires a current characterization signal representing the current flowing through the light-emitting component and a first voltage signal at a preset position of the light-emitting circuit. The value of the current characterization signal is compared with a reference value, and the first voltage signal is compared with a first reference voltage. Only when the value of the current characterization signal is greater than the reference value and the first voltage signal is greater than the first reference voltage will the short-circuit protection circuit be triggered for short-circuit protection. That is, in this invention, a short-circuited light-emitting component is determined to exist in the light-emitting circuit only when the current value flowing through the light-emitting component is determined to be large and the first voltage signal at the preset position of the light-emitting component is also large. Compared to methods that "determine whether a short-circuited light-emitting component exists in the light-emitting circuit solely based on the magnitude of the voltage value at the preset position of the light-emitting circuit," this invention has more judgment conditions and more refined judgment steps, thereby greatly improving detection accuracy and avoiding false judgments.

[0051] The short-circuit detection circuit provided in the embodiments of the present invention will be described in further detail below.

[0052] Example 1

[0053] Figure 4 This is a connection diagram of a short-circuit detection circuit, a light-emitting circuit, a drive adjustment circuit, and a short-circuit protection circuit provided in Embodiment 1 of the present invention, as shown below. Figure 4 As shown, the short-circuit detection circuit 10 is connected to the light-emitting unit 30 and the driving adjustment circuit 20 respectively. The driving adjustment circuit 20 is connected to the light-emitting circuit 30. The short-circuit detection circuit 10 is also connected to the short-circuit protection circuit.

[0054] Further reference Figure 4The light-emitting circuit 30 includes at least two light-emitting components connected in series. Specifically, each light-emitting component can be an LED. For example, the light-emitting circuit may include three LEDs connected in series: LED1, LED2, and LED3. Furthermore, each light-emitting component is connected to a power converter to receive a drive voltage VOUT provided by the power converter.

[0055] The driving adjustment circuit 20 can specifically be connected to the cathode of the last light-emitting component in the current flow direction of the branch where the light-emitting component is located in the light-emitting circuit 30. For example, refer to Figure 4 The preset position can be the cathode end of LED3 (i.e., node D).

[0056] The driving adjustment circuit specifically includes a first operational amplifier 21, a resistor R, a fully differential sigma-delta modulator, an N-bit up / down counter, and an N-bit digital-to-analog converter module, where N is a positive integer. The first input terminal of the fully differential sigma-delta modulator is connected to the source of the driving transistor and is used to sample the source voltage VCS of the driving transistor. The second input terminal of the fully differential sigma-delta modulator is used to receive a second reference voltage VCS_REF. The output terminal of the fully differential sigma-delta modulator is connected to the input terminal of the up / down counter. The output terminal of the up / down counter is connected to the input terminal of the digital-to-analog converter module. The output terminal of the digital-to-analog converter module is connected to the non-inverting input terminal of the first operational amplifier 21, the non-inverting input terminal of the first operational amplifier 21 is connected to the source of the driving transistor Q, and the output terminal of the first operational amplifier 21 is connected to the gate of the driving transistor Q. The drain of the driving transistor Q is connected to a preset position D of the light-emitting circuit, and the source of the driving transistor Q is also connected to one end of the resistor R, with the other end of the resistor R grounded.

[0057] The second reference voltage VCS_REF can be input to the second input terminal of the fully differential sigma-delta modulator of the driving adjustment circuit by other circuits in the light-emitting device (e.g., the circuit above the light-emitting unit), and the voltage value of the second reference voltage VCS_REF is adjustable.

[0058] It should be noted that in this embodiment, the first operational amplifier 21 may be omitted, and the N-bit digital-to-analog converter module may be directly connected to the gate of the driving transistor to directly drive the driving transistor.

[0059] Furthermore, for the fully differential sigma-delta modulator, when the second reference voltage VCS_REF received at the second input terminal of the fully differential sigma-delta modulator is greater than the source voltage VCS of the driving transistor received at the first input terminal of the fully differential sigma-delta modulator, the fully differential sigma-delta modulator outputs a first level signal (i.e., a high level signal) to the up-down counter; when the second reference voltage VCS_REF received at the second input terminal of the fully differential sigma-delta modulator is less than the source voltage VCS of the driving transistor received at the first input terminal of the fully differential sigma-delta modulator, the fully differential sigma-delta modulator outputs a second level signal (i.e., a low level signal) to the up-down counter.

[0060] Regarding the up / down counter, the up / down counter stores a current value. When the up / down counter receives a high-level signal, it performs an addition operation on the current value to obtain an addition result and outputs the result as a binary signal. The addition operation can be, for example, incrementing by one. When the up / down counter receives a low-level signal, it performs a subtraction operation on the current value to obtain a subtraction result and outputs the result as a binary signal. The subtraction operation can be, for example, decrementing by one. The up / down counter outputs the binary signal to the digital-to-analog converter module in parallel.

[0061] The digital-to-analog converter module is mainly used to convert the received binary signal into an analog voltage signal and output it to the non-inverting input of the first operational amplifier 21. The magnitude of the analog voltage signal output by the digital-to-analog converter module is positively correlated with the magnitude of the received binary signal.

[0062] It should be noted that when the source voltage VCS of the driving transistor received at the first input terminal of the fully differential sigma-delta modulator is equal to the second reference voltage VCS_REF, the fully differential sigma-delta modulator will alternately output high-level and low-level signals at a relatively high frequency. For example, the fully differential sigma-delta modulator will output 010101, 101010, or 001100110011. Based on this, the up-down counter will also alternately perform addition and subtraction operations. Therefore, the fluctuation range of the binary signal output by the up-down counter is relatively small. That is, after each up-down counter alternately performs an addition and subtraction operation, the value of the binary signal output by the up-down counter is the same as the value of the binary signal output by the up-down counter before the alternating addition and subtraction operation. At this time, given that the up-down counter alternately performs addition and subtraction operations at a high frequency, it can be approximately considered that the binary signal output by the up-down counter remains unchanged. As a result, the analog voltage signal output by the digital-to-analog converter module will also remain unchanged. At this time, the drive adjustment circuit can be considered to be in a steady state.

[0063] Furthermore, in this embodiment, the driving adjustment circuit 20 can be used to drive the light-emitting component to emit light, and to adjust the current flowing through the light-emitting component.

[0064] Specifically, the principle by which the driving adjustment circuit 20 drives the light-emitting component to emit light mainly includes the following:

[0065] When the power converter sends a driving voltage VOUT to the light-emitting circuit 30, if the driving transistor Q is not turned on, the branch containing the light-emitting component is open-circuited, and the light-emitting component cannot emit light. Furthermore, the source voltage VSC of the driving transistor Q is a low-level signal. At this time, the second reference voltage VCS_REF can be adjusted to increase its value, making it greater than the source voltage VSC of the driving transistor Q. Consequently, the output of the fully differential sigma-delta modulator will output a high-level signal, and the up-down counter will perform an addition operation on its current stored value. The value of the binary signal output by the up-down counter will increase, causing the voltage value of the analog voltage signal output by the digital-to-analog converter module to increase. This, in turn, increases the voltage value of the voltage signal received at the non-inverting input of the first operational amplifier 31, causing the output of the first operational amplifier 31 to output a high-level signal. This will turn on the driving transistor Q, connect the branch containing the light-emitting component, and the light-emitting component will begin to emit light.

[0066] Furthermore, the principle by which the driving adjustment circuit 20 adjusts the current flowing through the light-emitting component is mainly as follows:

[0067] The current I flowing through the light-emitting component LED =VCS / R sense Where VCS is the source voltage driving transistor Q, and R sense Let R be the resistance value. The current I can be adjusted by changing the source voltage VCS of the driving transistor Q. LED The magnitude of the source voltage VCS can be adjusted by controlling the voltage value of the second reference voltage VCS_REF to increase or decrease. Specifically, when the voltage value of the second reference voltage VCS_REF increases and exceeds the current source voltage VSC, the output of the fully differential sigma-delta modulator outputs a high-level signal. The up-down counter performs an addition operation on its current stored value, increasing the value of the binary signal output by the up-down counter. This increases the voltage value of the analog voltage signal output by the digital-to-analog converter module, and also increases the voltage value of the voltage signal received by the non-inverting input of the first operational amplifier. Consequently, the voltage value of the voltage signal output by the output of the first operational amplifier 31 also increases, leading to an increase in the gate voltage of the driving transistor Q. This, in turn, increases the source voltage VCS of the driving transistor Q until the source voltage VCS increases to equal the second reference voltage VCS_REF.

[0068] Similarly, when the voltage value of the second reference voltage VCS_REF decreases to less than the current source voltage VSC, the output of the fully differential sigma-delta modulator will output a low-level signal. The up-down counter will perform a subtraction operation on its current stored value, and the value of the binary signal output by the up-down counter will decrease, causing the voltage value of the analog voltage signal output by the digital-to-analog converter module to also decrease. The voltage value of the voltage signal received by the non-inverting input of the first operational amplifier will also decrease, and thus the voltage value of the voltage signal output by the output of the first operational amplifier 31 will also decrease. This will cause the gate voltage of the driving transistor Q to decrease, and consequently, the source voltage VCS of the driving transistor Q to decrease, until the source voltage VCS decreases to equal the second reference voltage VCS_REF and stops.

[0069] As can be seen from the above, by adjusting the voltage value of the second reference voltage VCS_REF, the magnitude of the binary signal output by the up / down counter can be adjusted, which in turn can adjust the magnitude of the source voltage VCS of the driving transistor Q. This allows for the control of the current I flowing through the light-emitting component. LED The size can be adjusted. Furthermore, the value of the binary signal output by the up / down counter is essentially related to the current I flowing through the light-emitting component.LED The correlation is positive, specifically including: when the value of the binary signal output by the up / down counter increases, the source voltage VCS of the driving transistor Q increases, which in turn increases the current I flowing through the light-emitting component. LED When the value of the binary signal output by the up / down counter decreases, the source voltage VCS of the driving transistor Q decreases, which in turn increases the current I flowing through the light-emitting component. LED Decrease.

[0070] Based on this, in this embodiment, the current detection circuit in the short-circuit detection circuit 10 can be connected to the output terminal of the up-down counter in the driving condition circuit 20 to obtain the binary signal output by the up-down counter, and determine the current I flowing through the light-emitting component based on the magnitude of the binary signal output by the up-down counter. LED The size of the current detection circuit. In other words, in this embodiment, the short-circuit detection circuit 10 reuses an intermediate signal from the feedback control loop as the current detection value. This allows a digital comparator to be used in the subsequent stage for judgment, and the judgment result can be converted back to analog. This eliminates the need for an ADC, simplifies the circuit structure, and reduces costs.

[0071] Specifically, refer to Figure 4 As shown, the first input terminal of the current detection circuit can be connected to the output terminal of the up-down counter to acquire the signal output by the up-down counter in real time, and use the signal output by the up-down counter as the current characterization signal M. The second input terminal of the current detection circuit is used to receive the clock signal CLK. The current detection circuit stores the reference value. The reference value can be preset by the operator using a preset application or the TRIM function, and the reference value can be set differently based on different light-emitting devices. The reference value can be: the value of the binary signal output by the up-down counter when the current flowing through the light-emitting circuit is the product of the full-load current of the light-emitting circuit and a preset percentage, where the preset percentage is greater than or equal to 5% and less than or equal to 15%, for example, 10%. For example, the reference value can be: the value of the binary signal output by the up-down counter when the current flowing through the light-emitting circuit is 10mA, which is 010.

[0072] Furthermore, in this first embodiment, the current detection circuit is mainly used to: when the second input terminal of the current detection circuit receives the rising edge of the clock signal CLK, compare the value of the current characterization signal M with the reference value; when the value of the current characterization signal M is greater than the reference value, determine that the current flowing through the light-emitting component is large, and output a current detection signal to indicate the first current detection result; otherwise, determine that the current flowing through the light-emitting component is small and output a current detection signal to indicate the second current detection result. Specifically, the current detection circuit can be a digital circuit, such as a current monitoring digital circuit with hysteresis function.

[0073] Further, refer to Figure 4 The first input terminal of the voltage detection circuit in the short-circuit detection circuit can be connected to the predetermined position D to acquire a first voltage signal at the predetermined position. This first voltage signal is essentially the drain voltage signal VD of the driving transistor. The second input terminal of the voltage detection circuit can be used to receive a first reference voltage VREF1. The voltage detection circuit is also used to determine whether the first voltage signal VD is greater than the first reference voltage VREF1. If it is greater than the first reference voltage VREF1, it indicates that the voltage VD at the predetermined position D is high, and the voltage detection circuit outputs a voltage detection signal (e.g., a first-level signal) to indicate the first voltage detection result. Otherwise, it indicates that the voltage at the predetermined position is low, and the voltage detection circuit outputs a voltage detection signal (e.g., a second-level signal) to indicate the second voltage detection result. Specifically, the voltage detection circuit may include a comparator, and the first-level signal may be a high-level signal, while the second-level signal may be a low-level signal.

[0074] It should be noted that the main reasons for a high voltage VD at the preset position D include: a short-circuited light-emitting component in the light-emitting unit or a low current flowing through the light-emitting component. Therefore, in this embodiment, only when both the first and second input terminals of the logic judgment circuit 11 receive the first level signal, that is, when the current flowing through the light-emitting component is large and the voltage VD at the preset position D is high, is it confirmed that a short-circuited light-emitting component exists in the light-emitting unit, and only then does the logic judgment circuit 11 output the drive signal SCP to the short-circuit protection circuit. This avoids the situation where "false judgments are likely to occur when the current flowing through the light-emitting component is small," thus improving detection accuracy.

[0075] In addition, such as Figure 4As shown, the short-circuit detection circuit 10 may further include a timing circuit. The input terminal of the timing circuit can be connected to the output terminal of the logic judgment circuit 11, and the output terminal of the timing circuit is connected to the input terminal of the short-circuit protection circuit. The timing circuit can be used to receive the drive signal SCP output by the output terminal of the logic judgment circuit, and when the duration of the continuous output of the drive signal SCP by the output terminal of the logic judgment circuit exceeds a preset duration, the timing circuit starts to output the drive signal SCP to the short-circuit protection circuit to trigger the short-circuit protection circuit to open. The value range of the preset duration may include [2, 8] ns, for example, it can be 5 ns.

[0076] By setting the timing circuit, when the logic judgment circuit 10 of the short circuit detection circuit erroneously outputs the drive signal SCP, the short circuit protection circuit can be prevented from being falsely triggered, thus further ensuring that the light-emitting device can work normally.

[0077] Furthermore, it should be noted that the current detection circuit and voltage detection circuit in the short-circuit detection circuit provided in Embodiment 1 of the present invention are both digital circuits, which can greatly reduce power consumption and area.

[0078] Example 2

[0079] Figure 5 This is a connection diagram of a short-circuit detection circuit, a light-emitting circuit, a drive adjustment circuit, and a short-circuit protection circuit provided in Embodiment 2 of the present invention, as shown below. Figure 5 As shown, the short-circuit detection circuit 10 is connected only to the light-emitting circuit 30. Furthermore, the structure of the short-circuit detection circuit when it is connected only to the light-emitting circuit 30 is the same as the structure when it is connected to both the driving adjustment circuit 20 and the light-emitting unit 30 (i.e.,...). Figure 4 The structure of the short-circuit detection circuit in the text is also different, unlike... Figure 4 The main difference lies in the structure of the current detection circuit, such as... Figure 5 As shown, the current detection circuit mainly includes:

[0080] A current sampling circuit is connected to the light-emitting circuit 30. For example, the current sampling circuit can be connected to a preset position D of the light-emitting circuit 30. It is used to sample the current signal I flowing through the light-emitting component and convert the current signal I into a second voltage signal Vsense, which is then output as the current characterization signal M. The current sampling circuit can be a conventional current sampling circuit, which will not be elaborated upon here.

[0081] A comparator circuit 100 is provided. Its first input terminal is connected to the current sampling circuit to receive the current characterization signal M. Its second input terminal receives a third reference voltage VREF3 and stores it as a reference value. The comparator circuit 100 compares the value of the current characterization signal M with the reference value. When the current characterization signal M is greater than the reference value, it indicates that the current flowing through the light-emitting component is high, and the comparator circuit outputs a first-level signal. Otherwise, it indicates that the current flowing through the light-emitting component is low, and the comparator circuit outputs a second-level signal. Specifically, the third reference voltage VREF3 can be the value of the second voltage signal Vsense output by the current sampling circuit when the value of the current signal collected by the current sampling circuit is the product of the full-load current of the light-emitting circuit and a preset percentage. The preset percentage is greater than or equal to 5% and less than or equal to 15%, for example, 10%. For example, the reference value can range from [2, 5]V, for example, 4V.

[0082] as well as, Figure 5 The light-emitting circuit, voltage detection circuit, logic judgment circuit 11, timing circuit, and drive adjustment circuit 20 mentioned above are... Figure 4 The structures and functions of the light-emitting circuit, voltage detection circuit, logic judgment circuit 11, timing circuit, and drive adjustment circuit 20 mentioned in this embodiment are the same, and will not be described again in this embodiment.

[0083] Furthermore, it should be noted that the current sampling circuit may not convert the sampled current signal into the second voltage signal. Instead, the current signal can be directly used as the current characterization signal M and compared with a preset current value. The preset current value can be the product of the full-load current of the light-emitting circuit and a preset percentage. When the current is greater than the preset current value, it is determined that the current flowing through the light-emitting component is large, and a first-level signal is output; otherwise, it is determined that the current flowing through the light-emitting component is small, and a second-level signal is output.

[0084] Furthermore, in this second embodiment, the current sampling circuit may not be connected to the light-emitting circuit, but may be connected to the source of the driving transistor in the driving adjustment circuit to sample the source voltage signal of the driving transistor. The source voltage signal can also characterize the current flowing through the light-emitting component, and the source voltage signal can be output as the current characterization signal.

[0085] Example 3

[0086] Figure 6This is a flowchart illustrating a short-circuit detection method provided in Embodiment 3 of the present invention. The short-circuit detection method is used to detect whether a short-circuited light-emitting component exists in a light-emitting circuit comprising at least two light-emitting components connected in series. Specifically, the short-circuit detection method can be... Figures 3 to 5 Execute any of the short-circuit detection circuits shown, such as Figure 6 As shown, the short-circuit detection method may include:

[0087] Step S1: Obtain a current characterization signal. The value of the current characterization signal is used to characterize the current flowing through the light-emitting component. Compare the value of the current characterization signal with a reference value.

[0088] Step S2: Obtain a first voltage signal at a preset position of the light-emitting circuit, wherein the preset position is the connection terminal of the light-emitting circuit and the driving adjustment circuit, and compare the first voltage signal with a first reference voltage.

[0089] Step S3: When it is determined that the value of the current characterization signal is greater than the reference value and the first voltage signal is greater than the first reference voltage, the short-circuit protection circuit is triggered to open.

[0090] Example 4

[0091] Figure 7 This is a schematic diagram of the structure of a light-emitting device provided in Embodiment 4 of the present invention, as shown below. Figure 7 As shown, the light-emitting device includes at least two light-emitting units 1 connected in parallel, and each light-emitting unit 1 includes: a light-emitting circuit 30, a driving adjustment circuit 20, and a short-circuit protection circuit. Figure 7 (not shown), and as Figures 3-5 Any of the short-circuit detection circuits 10 shown.

[0092] The light-emitting circuit 30 includes at least two light-emitting components connected in series. For example, it may include three light-emitting components connected in series, and the light-emitting components may be LEDs.

[0093] The driving adjustment circuit 20 is connected to the light-emitting circuit 30 and is used to drive the light-emitting component to emit light and to adjust the current flowing through the light-emitting component.

[0094] The short-circuit detection circuit 10 is connected to the light-emitting circuit 30, and the short-circuit detection circuit 10 is also connected to the short-circuit protection circuit. The short-circuit detection circuit 10 is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit 30. When a short-circuited light-emitting component is detected in the light-emitting circuit 30, the short-circuit detection circuit 10 is used to trigger the short-circuit protection circuit to work, so as to provide short-circuit protection for the light-emitting device.

[0095] In summary, the short-circuit detection circuit and method, as well as the light-emitting device provided by this invention, when detecting whether a short-circuited light-emitting component exists in the light-emitting device, first acquires a current characterization signal representing the current flowing through the light-emitting component and a first voltage signal at a preset position of the light-emitting circuit. The value of the current characterization signal is compared with a reference value, and the first voltage signal is compared with a first reference voltage. Only when the value of the current characterization signal is greater than the reference value and the first voltage signal is greater than the first reference voltage will the short-circuit protection circuit be triggered for short-circuit protection. That is, in this invention, a short-circuited light-emitting component is determined to exist in the light-emitting circuit only when the current value flowing through the light-emitting component is determined to be large and the first voltage signal at the preset position of the light-emitting component is determined to be large. Compared to the method of "determining whether a short-circuited light-emitting component exists in the light-emitting circuit solely based on the magnitude of the voltage value at the preset position of the light-emitting circuit," this invention has more judgment conditions and more refined judgment steps, thereby greatly improving detection accuracy and avoiding misjudgments.

[0096] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0097] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A short-circuit detection circuit, wherein the short-circuit detection circuit is connected to a light-emitting circuit, the light-emitting circuit includes a light-emitting component, the short-circuit detection circuit is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit, and the light-emitting circuit is further connected to a drive adjustment circuit, the drive adjustment circuit being used to adjust the magnitude of the current flowing through the light-emitting component, characterized in that, The short-circuit detection circuit includes: A current detection circuit, connected to the light-emitting circuit or the driving adjustment circuit, is used to acquire a current characterization signal, the value of which characterizes the current flowing through the light-emitting component; the current detection circuit is also used to: compare the value of the current characterization signal with a reference value and output a current detection signal, wherein when the value of the current characterization signal is greater than the reference value, the current detection signal is used to indicate a first current detection result; otherwise, the current detection signal is used to indicate a second current detection result. A voltage detection circuit is provided, the input terminal of which is connected to a preset position of the light-emitting circuit, the preset position being the connection terminal between the light-emitting circuit and the driving adjustment circuit; the voltage detection circuit is used to: acquire a first voltage signal at the preset position, determine whether the first voltage signal is greater than a first reference voltage, and output a voltage detection signal, wherein when the first voltage signal is greater than the first reference voltage, the voltage detection signal is used to indicate a first voltage detection result; otherwise, the voltage detection signal is used to indicate a second voltage detection result. A logic judgment circuit is provided, wherein the first input terminal of the logic judgment circuit is connected to the output terminal of the current detection circuit for receiving a current detection signal, the second input terminal of the logic judgment circuit is connected to the output terminal of the voltage detection circuit for receiving a voltage detection signal, and the output terminal of the logic judgment circuit is connected to a short-circuit protection circuit; the logic judgment circuit is used to: when the current detection signal obtained by the first input terminal of the logic judgment circuit indicates a first current detection result and the voltage detection signal obtained by the second input terminal indicates a first voltage detection result, output a drive signal to the short-circuit protection circuit to drive the short-circuit protection circuit to open.

2. The short-circuit detection circuit as described in claim 1, characterized in that, The current detection circuit is connected to the drive adjustment circuit; The drive adjustment circuit includes a resistor, a fully differential sigma-delta modulator, an up-down counter, and a digital-to-analog converter module; The first input terminal of the fully differential sigma-delta modulator is connected to the source of the driving transistor and is used to sample the source voltage of the driving transistor. The second input terminal of the fully differential sigma-delta modulator is used to receive a second reference voltage. The output terminal of the fully differential sigma-delta modulator is connected to the input terminal of the up-down counter. The output terminal of the up-down counter is connected to the input terminal of the digital-to-analog converter module. The output terminal of the digital-to-analog converter module is connected to the gate of the driving transistor; the drain of the driving transistor is connected to a preset position of the light-emitting circuit, and the source of the driving transistor is also connected to one end of the resistor, while the other end of the resistor is grounded. The value of the signal output from the output terminal of the up-down counter is positively correlated with the current value flowing through the light-emitting component.

3. The short-circuit detection circuit as described in claim 2, characterized in that, The first input terminal of the current detection circuit is connected to the output terminal of the up-down counter, and is used to acquire the signal output by the up-down counter in real time, and use the signal output by the up-down counter as the current characterization signal. The second input terminal of the current detection circuit is used to receive a clock signal. The reference value is stored in the current detection circuit. The current detection circuit is configured to: when the second input terminal of the current detection circuit receives the rising edge of the clock signal, compare the value of the current characterization signal with the reference value; when the value of the current characterization signal is greater than the reference value, output a current detection signal to indicate the first current detection result; otherwise, output a current detection signal to indicate the second current detection result.

4. The short-circuit detection circuit as described in claim 3, characterized in that, The reference value is the value of the signal output by the up-down counter when the current flowing through the light-emitting circuit is the product of the full-load current of the light-emitting circuit and a preset percentage.

5. The short-circuit detection circuit as described in claim 4, characterized in that, The preset percentage is greater than or equal to 5% and less than or equal to 15%.

6. The short-circuit detection circuit as described in claim 1, characterized in that, The current detection circuit is connected to the light-emitting circuit; The current detection circuit includes: A current sampling circuit is connected to the light-emitting circuit and is used to sample the current signal flowing through the light-emitting component in the light-emitting circuit, and convert the current signal into a second voltage signal and output it as the current characterization signal. A comparator circuit is provided, wherein a first input terminal of the comparator circuit is connected to the output terminal of the current sampling circuit for receiving the current characterization signal, a second input terminal of the comparator circuit for receiving a third reference voltage and storing the third reference voltage as the reference value, the comparator circuit for comparing the value of the current characterization signal with the reference value, and outputting the current detection signal. When the value of the current characterization signal is greater than the reference value, the current detection signal indicates a first current detection result; otherwise, the current detection signal indicates a second current detection result.

7. The short-circuit detection circuit as described in claim 1, characterized in that, The current detection circuit is connected to the light-emitting circuit; The current detection circuit includes: A current sampling circuit is connected to the source of the driving transistor in the driving adjustment circuit. It is used to sample the source voltage signal of the driving transistor and output the source voltage signal as the current characterization signal. A comparator circuit is provided, wherein a first input terminal of the comparator circuit is connected to the output terminal of the current sampling circuit for receiving the current characterization signal, a second input terminal of the comparator circuit for receiving a third reference voltage and storing the third reference voltage as the reference value, the comparator circuit for comparing the value of the current characterization signal with the reference value, and outputting the current detection signal. When the value of the current characterization signal is greater than the reference value, the current detection signal indicates a first current detection result; otherwise, the current detection signal indicates a second current detection result.

8. The short-circuit detection circuit as described in claim 1, characterized in that, The short-circuit detection circuit further includes a timing circuit, the input of which is connected to the output of the logic judgment circuit, and the output of which is connected to the input of the short-circuit protection circuit. The timing circuit is used to: receive the drive signal output by the output terminal of the logic judgment circuit, and when the duration of the continuous output of the drive signal by the output terminal of the logic judgment circuit exceeds a preset duration, start outputting the drive signal to the short circuit protection circuit to trigger the short circuit protection circuit to open.

9. A short-circuit detection method performed by the short-circuit detection circuit according to any one of claims 1-8, the short-circuit detection method being used to detect whether a short-circuited light-emitting component exists in a light-emitting circuit including a light-emitting component, characterized in that, The short-circuit detection method includes: Acquire a current characterization signal, the current characterization signal being used to characterize the current flowing through the light-emitting component, and compare the value of the current characterization signal with a reference value; and acquire a first voltage signal at a preset position of the light-emitting circuit, the preset position being the connection terminal of the light-emitting circuit and the drive adjustment circuit; and compare the first voltage signal with a first reference voltage. When it is determined that the value of the current characterization signal is greater than the reference value, and the first voltage signal is greater than the first reference voltage, the short-circuit protection circuit is triggered to open.

10. A light-emitting device, characterized in that, The light-emitting device includes at least two light-emitting units connected in parallel, and each light-emitting unit includes: a light-emitting circuit, a driving adjustment circuit, a short-circuit protection circuit, and a short-circuit detection circuit as described in any one of claims 1-8; The light-emitting circuit includes a light-emitting component; The driving adjustment circuit is connected to the light-emitting circuit and is used to drive the light-emitting component to emit light and to adjust the magnitude of the current flowing through the light-emitting component. The short-circuit detection circuit is connected to the light-emitting circuit, and the short-circuit detection circuit is also connected to the short-circuit protection circuit. The short-circuit detection circuit is used to detect whether there is a short-circuited light-emitting component in the light-emitting circuit. When a short-circuited light-emitting component is detected in the light-emitting circuit, the short-circuit protection circuit is triggered to work, so as to protect the light-emitting device from short circuit.

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