LED current feedback control system and LED control circuit

Abstract

The utility model relates to a kind of LED current feedback control system and LED control circuit, including micro control unit;Emitting voltage linear control module;At least one LED unit, including LED and enable module;Emitting voltage linear control module controls the emission current of LED, enable module connects the micro control unit and LED;Detection unit, it includes signal sampling module, threshold comparison module and threshold control module;Signal sampling module is also connected with the threshold comparison module and the LED unit;Signal sampling module converts the emission current of the LED into voltage signal, is transmitted to threshold comparison module, threshold comparison module sends the result of judgment into micro control unit, and micro control unit judges the working state of present LED according to result and corresponding adjustment emission voltage and comparison threshold value.The utility model has the advantages of simple structure, low cost, high precision and higher reliability, can directly control the light-emitting current of LED, and is suitable for safety light curtain and other optical communication systems.

Description

Technical Field

[0001] This utility model relates to the field of LED current control technology, and in particular to an LED current feedback control system and an LED control circuit. Background Technology

[0002] Light-emitting diodes (LEDs), as a highly efficient and energy-saving new type of light source, have wide applications in various fields. The brightness, stability, and lifespan of LEDs depend on the precise control of their emission current. In the field of optical communication, a safety light curtain is a photoelectric protection device that forms a dense barrier of infrared or visible light beams through an emitting end (LED array) and a receiving end (photoelectric sensor). When an object (such as a human hand) blocks any beam of light, the system immediately triggers a shutdown signal, ensuring that the equipment stops operating and thus preventing harm to the human body. LEDs, due to their high reliability, fast response, and long lifespan, are ideal light sources for safety light curtains. In existing technologies, the mainstream LED circuit detection and control method typically involves deploying a current detection circuit in the LED emission circuit that needs to be measured, and adjusting the emission pulse based on the detection results, such as through duty cycle adjustment (PWM).

[0003] However, existing detection solutions have shortcomings in applications such as safety light curtains: First, multi-channel expansion designs are complex and costly. Based on the working principle of safety light curtains, a large number of LEDs are typically used. To achieve N-channel LED adjustment, at least N channels of detection and control are required, leading to a surge in the number of components and increased software complexity, resulting in high design and hardware costs. Second, PWM control has limitations. While PWM control of LED emission intensity is common, this method cannot be used in scenarios such as optical communication where emission frequency is critical. In these products, real-time and rapid direct control of LED emission current is required. Third, closed-loop control has slow dynamic response. Traditional LED emission current detection circuits based on software algorithm feedback control typically require ADC sampling, algorithm calculation, and PWM updates, each step introducing operational delays. Furthermore, system reliability is questionable. Traditional LED emission current control systems usually require a sampling resistor connected in series in the loop to obtain current information. Because the sampling resistor must withstand the loop current for extended periods, operating under high temperature and high current conditions, it is prone to drift and burnout. Therefore, traditional sampling methods lack reliability for current detection. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide an LED current feedback control system and LED control circuit, which has the advantages of simple structure, low cost, high precision and high reliability, and can directly control the light emission current of LEDs, and is suitable for optical communication systems such as safety light curtains.

[0005] To solve the above-mentioned technical problems, this utility model provides an LED current feedback control system, including, Microcontroller unit; A linear control module for transmitting voltage, the input of which is connected to the microcontroller unit; At least one LED unit, the LED unit including an LED and an enable module; the emission voltage linear control module controls the emission current of the LED, the enable module is connected to the microcontroller unit and the LED, and the enable unit controls the on / off state of the LED; The detection unit includes a signal sampling module, a threshold comparison module, and a threshold control module. The output of the emission voltage linear control module is connected to the signal sampling module. The signal sampling module is also connected to the threshold comparison module and the LED unit. The signal sampling module converts the emission current of the LED into a voltage signal and transmits it to the threshold comparison module. The threshold comparison module converts the voltage signal into a digital signal and outputs a logic judgment signal to the microcontroller unit. The microcontroller unit determines the current operating state of the LED based on the logic judgment signal. The threshold control module can control the threshold voltage of the threshold comparison module.

[0006] In one embodiment of this utility model, the transmit voltage linear control module obtains the input level V_CTRL through the microcontroller unit and converts it into a transmit voltage V_EMIT. The transmit voltage linear control module outputs the transmit voltage V_EMIT to the signal sampling module.

[0007] In one embodiment of this utility model, multiple LED units are provided, and the signal sampling module is connected to multiple LED units.

[0008] In one embodiment of this utility model, the signal sampling module includes a transmit current-limiting resistor R_LIM and a sampling resistor R_SAMPLING. The transmit current-limiting resistor R_LIM is connected in series between the transmit voltage linear control module and the LED unit; the sampling resistor R_SAMPLING is connected between the LED unit and the threshold comparison module; and the signal sampling module outputs a voltage signal. To the threshold comparison module.

[0009] In one embodiment of this utility model, the formula for calculating the emission current of a single LED is as follows: ,in The transmit voltage of the transmit voltage linear control module. The output voltage of the signal sampling module is N, and the number of LED units is N. The value of the emission current limiting resistor R_LIM is given.

[0010] In one embodiment of this utility model, the threshold comparison module includes an open-circuit detection module and a short-circuit detection module. The open-circuit detection module is connected to the microcontroller unit to output the open-circuit detection result to the microcontroller unit; the short-circuit detection module is connected to the microcontroller unit to output the short-circuit detection result to the microcontroller unit.

[0011] In one embodiment of this utility model, the threshold control module includes a first operational amplifier and a second operational amplifier. The input terminal of the first operational amplifier is connected to the V_SHORT terminal of the microcontroller unit, and the output terminal of the first operational amplifier is connected to the threshold comparison module. The input terminal of the second operational amplifier is connected to the V_OPEN terminal of the microcontroller unit, and the output terminal of the second operational amplifier is connected to the threshold comparison module.

[0012] This invention also provides an LED control circuit, including the LED current feedback control system described above.

[0013] The above-mentioned technical solution of this utility model has the following advantages compared with the prior art: The present invention discloses an LED current feedback control system comprising a microcontroller unit, an emission voltage linear control module, at least one LED unit, a signal sampling module, a threshold comparison module, and a threshold control module. The microcontroller unit is connected to the emission voltage linear control module, the LED unit, and the threshold comparison module to control the emission voltage and emission current of the emission voltage linear control module, and the on / off state of the LEDs in the LED unit. First, this invention offers fast control of the transmission current. Since the response time of the linear control module for the transmission voltage depends on the voltage settling time of the operational amplifier used, typically in the nanosecond range, while the transmission current depends on the output voltage of the linear control module, its current control speed is faster than traditional PWM control systems, making it suitable for most optical communication systems. Second, this invention is highly scalable. Multiple LEDs can be connected to the control system as needed, enabling simultaneous detection and control of multiple LEDs, reducing circuit complexity and cost. Third, this invention boasts high reliability. Compared to traditional current detection methods, the signal sampling module in this system is not connected in series in the transmission circuit. Therefore, the current through the signal sampling module depends only on the input resistance of the threshold comparator, which is typically in the megaohm range. This avoids the vulnerability of the sampling resistor in traditional current detection methods, resulting in higher reliability. Furthermore, the control logic of this invention is simple. It does not require ADC sampling of the input signal of the signal sampling module; it only needs to adjust the transmission current based on the open / short circuit judgment result output by the threshold comparator. Therefore, compared to traditional control methods, it improves response speed and reduces algorithm complexity. Finally, this invention can identify open-circuit and short-circuit faults in the current circuit based on the signals received by the microcontroller and the feedback control process. When a fault occurs, it can promptly shut down the LED's emission circuit and issue an alarm, which is of great significance in functional safety devices such as safety light curtains. Attached Figure Description

[0014] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0015] Figure 1 This is a circuit diagram of the LED current feedback control system according to a preferred embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the system architecture of the LED current feedback control system according to a preferred embodiment of the present invention.

[0017] Explanation of reference numerals in the accompanying drawings: 1. Transmit voltage linear control module; 2. LED unit; 3. Signal sampling module; 4. Threshold comparison module; 5. Threshold control module. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention. Example 1

[0019] Reference Figures 1 to 2 As shown, this utility model discloses an LED current feedback control system, including a microcontroller unit; The LED current feedback control system also includes an emission voltage linear control module 1.

[0020] The LED current feedback control system also includes at least one LED unit 2; Specifically, each LED unit 2 includes an LED and an enable module; the emission voltage module control module 1 controls the emission current of the LED, the enable module is connected to the microcontroller unit to obtain the enable signal of the microcontroller unit, and the enable module is also connected to the LED to control the on / off state of the LED.

[0021] The LED current feedback control system also includes a detection unit, which includes a signal sampling module 3, a threshold comparison module 4, and a threshold control module 5.

[0022] The input terminal of the transmit voltage linear control module 1 is connected to the microcontroller unit, and the output terminal of the transmit voltage linear control module 1 is connected to the signal acquisition module 3.

[0023] Furthermore, the signal sampling module 3 is also connected to the threshold comparison module 4 and the LED unit 2; the signal sampling module 3 converts the emission current of the LED into a voltage signal and transmits it to the threshold comparison module 4; the threshold comparison module 4 converts the voltage signal into a digital signal and outputs a logic judgment signal to the microcontroller unit. It should be noted that when there are multiple LED units 2, the multiple LED units 2 are connected to the signal sampling module 3. Preferably, the multiple LED units 2 are connected in parallel to form multiple LED circuits.

[0024] The microcontroller receives the logic judgment signal and determines the current working state of the LED based on the logic judgment signal; the threshold control module 5 is connected to the threshold comparison module 4, and the threshold control module 5 can control the threshold voltage of the threshold comparison module 4. Specifically, the threshold control module 5 can control the threshold comparison module 4 to determine the limit voltage value of open circuit and short circuit states.

[0025] During operation, the microcontroller unit can identify the fault type of the current circuit based on the logic judgment signal, and turn off the LED unit 2 when a fault occurs; Specifically, the microcontroller changes the output level of the emission voltage linear control module 1 according to the current working state of the LED unit. When the LED unit 2 is open-circuited, the output level is increased; when the LED unit 2 is short-circuited, the output level is decreased. The microcontroller adjusts the open-circuit threshold voltage and short-circuit threshold voltage of the threshold control module 5 according to the preset threshold of the emission current of the LED unit 2, until the received open-circuit and short-circuit judgment results indicate that the LED unit is currently working normally.

[0026] Therefore, it can be understood that the LED current feedback control system to be protected by this utility model includes a microcontroller unit, an emission voltage linear control module, at least one LED unit, a signal sampling module, a threshold comparison module, and a threshold control module. The microcontroller unit is connected to the emission voltage linear control module, the LED unit, and the threshold comparison module respectively to control the emission voltage and emission current of the emission voltage linear control module and the on or off of the LED of the LED unit. First, this invention offers fast control of the transmission current. Since the response time of the linear control module for the transmission voltage depends on the voltage settling time of the operational amplifier used, typically in the nanosecond range, while the transmission current depends on the output voltage of the linear control module, its current control speed is faster than traditional PWM control systems, making it suitable for most optical communication systems. Second, this invention offers strong scalability. Multiple LEDs can be connected to the control system as needed, enabling simultaneous detection and control of multiple LEDs, reducing circuit complexity and cost. Third, this invention offers high reliability. Compared to traditional current detection methods, the signal sampling module in this system is not connected in series in the transmission circuit. Therefore, the current through the signal sampling module depends only on the input resistance of the threshold comparison module, which is typically in the megaohm range. This avoids the vulnerability of the sampling resistor in traditional current detection methods, resulting in higher reliability. Furthermore, the control logic of this invention is simple. It does not require ADC sampling of the input signal of the signal sampling module; it only needs to adjust the transmission current based on the open / short circuit judgment result output by the threshold comparison module. Therefore, compared to traditional control methods, it improves response speed and reduces algorithm complexity. Finally, this invention can identify open-circuit and short-circuit faults in the current circuit based on the signals received by the microcontroller and the feedback control process. When a fault occurs, it can promptly shut down the LED's emission circuit and issue an alarm, which is of great significance in safety devices such as safety light curtains.

[0027] In detail, the transmit voltage linear control module 1 obtains the input level signal V_CTRL through the microcontroller unit and converts it into a transmit voltage V_EMIT. The transmit voltage linear control module 1 outputs the transmit voltage V_EMIT to the signal sampling module.

[0028] The LED unit 2 is provided in multiple ways, and the signal sampling module 3 is connected to multiple LED units.

[0029] In a preferred embodiment, the signal sampling module 3 includes a transmit current limiting resistor R_LIM and a sampling resistor R_SAMPLING; wherein, the transmit current limiting resistor R_LIM is connected in series between the transmit voltage linear control module 2 and the LED unit 3; The sampling resistor R_SAMPLING is connected between the LED unit 2 and the threshold comparison module 4, and the signal sampling module 3 outputs a voltage signal. To the threshold comparison module 4.

[0030] As a preferred embodiment, the formula for calculating the emission current of a single LED is: , in, The transmit voltage of the transmit voltage linear control module 1 is the transmit voltage. The output voltage of the signal sampling module 3 is N, and the number of LED units 2 is N. The value of the emission current limiting resistor R_LIM is given.

[0031] In a preferred embodiment, the enabling module includes an enabling switch Q_EMIT_EN, which can acquire the output signal EMIT_CTRL of the microcontroller unit and turn a single LED on or off through the output signal EMIT_CTRL.

[0032] The enable switch Q_EMIT_EN includes an NMOS transistor, and the enable module further includes a resistor R_GATE; the gate of the NMOS transistor is connected to the resistor R_GATE, and the source of the NMOS transistor is grounded.

[0033] Specifically, the threshold comparison module 4 includes an open-circuit detection module and a short-circuit detection module; the open-circuit detection module is connected to the microcontroller unit to output the open-circuit detection result to the microcontroller unit; the short-circuit detection module is connected to the microcontroller unit to output the short-circuit detection result to the microcontroller unit.

[0034] In a preferred embodiment, the threshold control module 5 includes a first operational amplifier and a second operational amplifier. The input terminal of the first operational amplifier is connected to the V_SHORT terminal of the microcontroller unit, and the output terminal of the first operational amplifier is connected to the threshold comparison module 4. The input terminal of the second operational amplifier is connected to the V_OPEN terminal of the microcontroller unit, and the output terminal of the second operational amplifier is connected to the threshold comparison module 4.

[0035] when > When the LED unit 2 is determined to be open, when < The system is determined to be short-circuited in LED unit 2. in The voltage value at the V_OPEN terminal is given by [value]. This refers to the voltage value at the V_SHORT terminal.

[0036] Furthermore, the threshold control module 5 can linearly change the voltage value at the V_OPEN terminal. and the voltage value at the V_SHORT terminal. This changes the voltage limit values ​​for open circuit and short circuit conditions determined by the threshold comparison module 4.

[0037] The threshold comparison module 4 uploads the open-circuit judgment result CHECK_OPEN and the short-circuit judgment result CHECK_SHORT to the microcontroller unit. The microcontroller unit determines the current working state of the LED unit 2 based on the received open-circuit and short-circuit judgment results. When CHECK_OPEN = 1 and CHECK_SHORT = 1, the circuit works normally; When CHECK_OPEN = 0 and CHECK_SHORT = 1, the circuit is open. When CHECK_OPEN = 1 and CHECK_SHORT = 0, the circuit is short-circuited; The microcontroller changes the output level signal V_CTRL according to the current operating state of the LED unit 2. When the LED unit 2 is open-circuited, the output level voltage U is increased. V_CTRL When the LED unit 2 is short-circuited, the voltage U of the output level is reduced. V_CTRL Meanwhile, V_OPEN and V_SHORT are changed according to the normal emission current threshold of the LED unit until the received open circuit and short circuit judgment results show that the LED unit 2 is currently working normally. Example 2

[0038] This utility model also discloses an LED control circuit, including the LED current feedback control system as described in Embodiment 1.

[0039] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0041] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. An LED current feedback control system, characterized in that: include, Microcontroller unit; A linear control module for transmitting voltage, the input of which is connected to the microcontroller unit; At least one LED unit, the LED unit comprising an LED and an enable module; The emission voltage linear control module controls the emission current of the LED, and the enable module is connected to the microcontroller unit and the LED, controlling the on / off state of the LED; The detection unit includes a signal sampling module, a threshold comparison module, and a threshold control module. The output of the emission voltage linear control module is connected to the signal sampling module. The signal sampling module is also connected to the threshold comparison module and the LED unit. The signal sampling module converts the emission current of the LED into a voltage signal and transmits it to the threshold comparison module. The threshold comparison module converts the voltage signal into a digital signal and outputs a logic judgment signal to the microcontroller unit. The microcontroller unit determines the current operating state of the LED based on the logic judgment signal. The threshold control module can control the threshold voltage of the threshold comparison module.

2. The LED current feedback control system according to claim 1, characterized in that: The transmit voltage linear control module obtains the input level V_CTRL through the microcontroller unit and converts it into a transmit voltage V_EMIT. The transmit voltage linear control module outputs the transmit voltage V_EMIT to the signal sampling module.

3. The LED current feedback control system according to claim 1, characterized in that: The LED unit is provided in multiple ways, and the signal sampling module is connected to multiple LED units.

4. The LED current feedback control system according to claim 1, characterized in that: The signal sampling module includes a transmit current-limiting resistor R_LIM and a sampling resistor R_SAMPLING. The transmit current-limiting resistor R_LIM is connected in series between the transmit voltage linear control module and the LED unit; the sampling resistor R_SAMPLING is connected between the LED unit and the threshold comparison module. The signal sampling module outputs a voltage signal. To the threshold comparison module.

5. The LED current feedback control system according to claim 4, characterized in that: The formula for calculating the emission current of a single LED is as follows: ,in The transmit voltage of the transmit voltage linear control module. The output voltage of the signal sampling module is N, and the number of LED units is N. The value of the emission current limiting resistor R_LIM is given.

6. The LED current feedback control system according to claim 1, characterized in that: The threshold comparison module includes an open-circuit detection module and a short-circuit detection module. The open-circuit detection module is connected to the microcontroller unit to output the open-circuit detection result to the microcontroller unit; the short-circuit detection module is connected to the microcontroller unit to output the short-circuit detection result to the microcontroller unit.

7. The LED current feedback control system according to claim 1, characterized in that: The threshold control module includes a first operational amplifier and a second operational amplifier. The input terminal of the first operational amplifier is connected to the V_SHORT terminal of the microcontroller unit, and the output terminal of the first operational amplifier is connected to the threshold comparison module. The input terminal of the second operational amplifier is connected to the V_OPEN terminal of the microcontroller unit, and the output terminal of the second operational amplifier is connected to the threshold comparison module.

8. An LED control circuit, characterized in that: Includes the LED current feedback control system as described in any one of claims 1-7.

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