A color mixing COB light source color difference control circuit

Abstract

The application discloses a color mixing COB light source color difference control circuit, and relates to a color mixing COB light source color difference control circuit, wherein a pulse duty ratio and a driving current signal Samp1 of an LED driving unit under a current color temperature are selected as a reference, and a signal corresponding to the pulse duty ratio is a reference pulse signal Pwm; a control unit further collects a driving current signal Samp2 of another LED driving unit, and generates a positive / negative compensation control signal Control; a processing unit generates a differential signal DIFF after differentiating Samp1 and Samp2, and feeds back the differential signal DIFF to the control unit; and the control unit synthesizes a low-level lagging or high-level lagging hetero-pulse control signal Pulse with the same frequency as the Pwm and matching the compensation pulse width and the differential signal DIFF value in the time sequence of the high level or the low level output by the Pwm based on the Control level state and the differential signal DIFF signal amplitude, and feeds the hetero-pulse control signal Pulse into the LED driving unit.

Description

A color difference control circuit for a mixed-color COB light source Technical Field

[0001] This invention relates to the field of LED control technology, and more specifically, to a color difference control circuit for a COB (Chip-on-Board) light source. Background Technology

[0002] COB packaging (Chip-on-Board) is a high-density LED packaging technology. Its core process involves directly integrating multiple bare LED dies onto the surface of a substrate such as a ceramic or aluminum substrate through die bonding and bonding processes. Subsequently, after uniform phosphor coating, encapsulation, and lens encapsulation processes, a highly integrated light-emitting module is formed.

[0003] In practical applications, to adapt to the spatial layout and installation requirements of complex lighting scenarios, multiple COB segments are usually spliced ​​together to adjust their luminous length and arrangement. However, due to the inherent parameter dispersion of LED devices (such as differences in chip electro-optical conversion efficiency and uneven phosphor coating thickness), coupled with the optical superposition effect generated after splicing, problems such as uneven illuminance distribution and decreased color temperature consistency can easily occur in the system.

[0004] The current mainstream solution is an algorithm-driven hybrid control scheme, which achieves color temperature calibration by constructing a color temperature-current mapping model and using algorithms to reverse-engineer the drive current compensation value under specific color temperature conditions. However, this scheme requires multiple sets of parameter calibrations and dynamic scene adaptation adjustments to establish a complete and effective mapping model, resulting in a high overall technical threshold. Furthermore, it demands a high level of professional technical expertise from operators during daily control and subsequent maintenance, significantly increasing the customer's labor costs for later maintenance. Summary of the Invention

[0005] In view of this, this application provides a color difference control circuit for a mixed COB light source, which uses hardware-based control logic to replace the traditional mixed control scheme to achieve the adjustment and real-time synchronization of the color difference consistency of the light source, making it convenient for daily control and maintenance.

[0006] In a first aspect, this application proposes a color difference control circuit for a COB (Chip-on-Board) light source, comprising a control unit, a processing unit, and multiple LED driving units. The control unit selects the pulse duty cycle and driving current signal Samp1 of the LED driving unit at the current color temperature as a reference, and the signal corresponding to the pulse duty cycle is the reference pulse signal Pwm. The control unit then acquires the driving current signal Samp2 of another LED driving unit and generates a positive / negative compensation control signal Control. The processing unit differentially divides Samp1 and Samp2 to generate a differential signal DIFF, which is fed back to the control unit. Based on the level state of Control and the amplitude of the differential signal DIFF, the control unit synthesizes a different pulse control signal Pulse with the same frequency as Pwm and whose compensation pulse width matches the DIFF value, with low-level lag or high-level lag, and feeds it back to the LED driving unit.

[0007] Optionally, the control unit includes a first P-type MOSFET, a first capacitor, a first resistor, a first operational amplifier, a second operational amplifier, a third XOR gate, a fourth AND gate, a fifth NOT gate, and a sixth operational amplifier. The non-inverting input of the first operational amplifier receives the Samp1 signal, the inverting input receives the Samp2 signal, and its output is connected to one input of the third XOR gate. The other input of the third XOR gate is connected to the output of the fifth NOT gate, and the output outputs the Pulse signal. The output of the fourth AND gate is connected to the input of the fifth NOT gate. One input of the fourth AND gate is connected to one end of the first resistor, the gate of the first P-type MOSFET, and the output of the second operational amplifier. The other input is connected to the output of the sixth operational amplifier. The non-inverting input of the second operational amplifier receives the PWM signal. The inverting input of the sixth operational amplifier receives the differential signal DIFF. The non-inverting input is connected to the other end of the first resistor, one end of the first capacitor, and the source of the first P-type MOSFET. The drain of the first P-type MOSFET, the other end of the first capacitor, and the ground terminal are connected.

[0008] Secondly, based on the above-mentioned scheme, this application proposes a control scheme that simplifies the processing logic. The processing unit includes a seventh operational amplifier, an eighth gating switch, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The differential signal DIFF is output by the seventh operational amplifier. The output terminal of the seventh operational amplifier is connected to one end of the fourth resistor, the non-inverting input is connected to one end of the second resistor, and the inverting input is connected to one end of the third resistor and the other end of the fourth resistor. The other end of the second resistor is connected to the AX / AY pin of the eighth gating switch and one end of the fifth resistor. The A and B pins of the eighth gating switch input Control signals and are connected to one end of the sixth resistor. The AX and BY pins are connected in parallel to input the Samp2 signal, and the AY and BX pins are connected in parallel to input the Samp1 signal. The other ends of the sixth resistor and the other ends of the fifth resistor are connected to the ground terminal.

[0009] Optionally, the processing unit includes a microprocessor. The microprocessor acquires the Samp1 and Samp2 signals, performs differential processing, and inputs the positive pressure DIFF signal to the control unit. The microprocessor also outputs a pulse signal to the LED driver unit.

[0010] Optionally, the LED driving unit includes a first light-emitting diode D1, a second light-emitting diode D2, a seventh resistor R7, an eighth resistor R8, a second P-type MOSFET Q2, a third N-type MOSFET Q3, and a ninth resistor R9. The first and second light-emitting diodes feed back a driving current signal Samp1 or a driving current signal Samp2 to the control unit and the processing unit. The cathode of the first light-emitting diode D1 is connected to one end of the seventh resistor R7; the other end of the seventh resistor R7 is connected to the source of the second P-type MOSFET Q2; the cathode of the second light-emitting diode D2 is connected to one end of the eighth resistor R8; the other end of the eighth resistor R8 is connected to the drain of the third N-type MOSFET Q3; the gates of the second P-type MOSFET Q2 and the third N-type MOSFET Q3, and one end of the ninth resistor R9 are connected to a PWM signal or a Pulse signal; the other end of the ninth resistor R9, the source of the third N-type MOSFET Q3, the drain of the second P-type MOSFET Q2, and the ground terminal are connected.

[0011] Optionally, the control unit also includes a pulse generator, which generates the pulse signal for the LED driver unit.

[0012] Optionally, the pulse signal for the LED driver unit is provided by a microprocessor.

[0013] This application selects the pulse duty cycle and drive current signal Samp1 of an LED driver unit at the current color temperature as a reference by a control unit, with the signal corresponding to the pulse duty cycle being the reference pulse signal Pwm. It also acquires the drive current signal Samp2 of another LED driver unit. The control unit differentially divides Samp1 and Samp2 to generate a differential signal DIFF. Simultaneously, it generates a positive / negative compensation control signal Control. Based on the Control level and the DIFF signal amplitude, the control unit synthesizes a different pulse control signal Pulse with the same frequency as Pwm and whose compensation pulse width matches the DIFF value, either with a low-level lag or a high-level lag. This different pulse control signal Pulse controls the target LED driver circuit to achieve adjustment and real-time synchronization of the light source color difference consistency. This control scheme does not require building a mapping model, reducing the soft-tuning process. In daily control, simply changing the duty cycle signal of the reference light source LED driver unit allows for the resynthesis of the different pulse control signal Pulse to the target light source to complete the control. During later maintenance, Samp1 and Samp2 can be retested to reuse the circuit. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 is a schematic diagram of the control unit circuit provided by the present invention.

[0016] Figure 2 is a schematic diagram of the processing unit circuit provided by the present invention.

[0017] Figure 3 is a waveform diagram of the output signal of the control unit of the present invention.

[0018] Figures 4 and 5 are schematic diagrams of the LED driving unit circuit provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0021] One embodiment of this application provides a color difference control circuit for a mixed-color COB light source. It replaces the traditional mixed control method with hardware-based control logic to achieve adjustment and real-time synchronization of the light source's color difference consistency. The circuit includes a control unit, a processing unit, and multiple LED driving units. The control unit selects the pulse duty cycle and driving current signal Samp1 of the LED driving unit at the current color temperature as a reference, with the signal corresponding to the pulse duty cycle being the reference pulse signal Pwm. The control unit then acquires the driving current signal Samp2 of another LED driving unit and generates a positive / negative compensation control signal Control. The processing unit differentially divides Samp1 and Samp2 to generate a differential signal DIFF, which is fed back to the control unit. Based on the Control level state and the amplitude of the differential signal DIFF, the control unit synthesizes a different pulse control signal Pulse with the same frequency as Pwm and whose compensation pulse width matches the DIFF value. This signal is either low-level lag or high-level lag and is fed back to the LED driving unit.

[0022] Specifically, first, the LED driver unit of a light source is used as a reference. The duty cycle of the pulse signal and the corresponding drive current signal Samp1 of the LED driver unit of this reference light source at the current color temperature are collected, and the current duty cycle is marked as the reference pulse signal Pwm. Then, the drive current signal Samp2 of the LED driver unit of another target light source that has a color difference from the reference circuit is collected. The drive current signal Samp1 and the drive current signal Samp2 are then differentially divided to generate a differential signal DIFF, and a positive / negative compensation control signal Control is generated. Based on the state of the positive / negative compensation control signal Control and the difference... The control unit can synthesize a pulse control signal Pulse with the same frequency as PWM and compensated for by the pulse width matching the DIFF value, under the timing of PWM output high or low level. The pulse width is matched with the DIFF value, and the pulse control signal Pulse is used to regulate the target light source LED driver unit, so that the target light source and the reference light source always maintain the same color temperature. This control scheme does not require the construction of a color temperature-current mapping model. In daily adjustment, the duty cycle signal of the reference light source LED driver unit can be directly changed to resynthesize the pulse control signal Pulse to the target light source.

[0023] In one embodiment, the control unit includes a first P-type MOSFET, a first capacitor, a first resistor, a first operational amplifier, a second operational amplifier, a third XOR gate, a fourth AND gate, a fifth NOT gate, and a sixth operational amplifier. The non-inverting input of the first operational amplifier receives the Samp1 signal, the inverting input receives the Samp2 signal, and its output is connected to one input of the third XOR gate. The other input of the third XOR gate is connected to the output of the fifth NOT gate, and the output outputs the Pulse signal. The output of the fourth AND gate is connected to the input of the fifth NOT gate. One input of the fourth AND gate is connected to one end of the first resistor, the gate of the first P-type MOSFET, and the output of the second operational amplifier. The other input is connected to the output of the sixth operational amplifier. The non-inverting input of the second operational amplifier receives the PWM signal. The inverting input of the sixth operational amplifier receives the differential signal DIFF, and its non-inverting input is connected to the other end of the first resistor, one end of the first capacitor, and the source of the first P-type MOSFET. The drain of the first P-type MOSFET, the other end of the first capacitor, and ground are connected.

[0024] Specifically, referring to Figures 1 and 3, the reference pulse signal Pwm is input to the non-inverting input of the second operational amplifier U2. When the reference pulse signal Pwm is high, the second operational amplifier U2 outputs a high level, which is transmitted to the gate of the first P-type MOSFET Q1 and the fourth AND gate U4. At this time, a positive potential difference is formed between the gate and source of the first P-type MOSFET Q1, and it is in the cutoff state. Simultaneously, the output of the second operational amplifier U2 charges the first capacitor C1 through the first resistor R1 to store energy. After the voltage of the first capacitor C1 rises, it is fed back to the sixth operational amplifier U. At the non-inverting input of gate 6, the fourth AND gate U4 blocks the signal input from the second operational amplifier U2 to the fifth NOT gate U5. The fifth NOT gate U5 still outputs a high level to the third XOR gate U3. Assuming the current positive / inverse compensation control signal Control is positive, the output of the third XOR gate U3 remains unchanged at a low level. When the voltage of the first capacitor C1 is greater than the differential signal DIFF, the sixth operational amplifier U6 outputs a high level to the fourth AND gate U4, triggering the fourth AND gate U4 to release the current high level output of the second operational amplifier U2 to the fifth NOT gate U5. After gate U5 is inverted, it outputs a low level to the third XOR gate U3. At the same time, the non-inverting and inverting inputs of the first operational amplifier U1 are input to the drive current signals Samp1 and Samp2, respectively. By comparing the two, the compensation type of the differential pulse control signal Pulse is confirmed. If the current positive / inverse compensation control signal Control is positive, the third XOR gate U3 outputs a low-level delayed differential pulse control signal Pulse (the waveform at the bottom of Figure 3) that matches the value of the differential signal DIFF. The middle waveform is a schematic waveform of the reference pulse signal Pwm. If the positive / inverse compensation control signal Control is inverted, the third XOR gate U3 will output a high-level delayed differential pulse control signal Pulse (the waveform at the top of Figure 3) that matches the value of the differential signal DIFF. When the reference pulse signal Pwm is low, the second operational amplifier U2 outputs a low level. The first P-type MOS transistor Q1 turns on because a negative voltage difference is formed between the gate and the source. The first capacitor C1 forms a loop through the first P-type MOS transistor Q1 and the ground terminal, and the voltage of the first capacitor C1 gradually decreases.Unlike when PWM is high, in this case, the fourth AND gate U4 directly feeds back the level signal output by the second operational amplifier U2 to the fifth NOT gate U5 for inversion, causing the third XOR gate U3 to directly output a low-level differential pulse control signal Pulse, which matches the state of the reference pulse signal PWM. When PWM outputs a high level again, the above control process is repeated, ultimately synthesizing a differential pulse control signal Pulse that is in sync with PWM and whose compensation pulse width matches DIFF. The differential pulse control signal Pulse is then sent to the controlled LED driver unit for control. When reused in other lamp groups, the drive current signals Samp1 and Samp2 are sampled again. In this embodiment, the differential signal DIFF is input by the microprocessor, and the PWM signal of the LED driver unit can be provided by the microprocessor or input by a pulse generator.

[0025] In one embodiment, the processing unit includes a seventh operational amplifier, an eighth gating switch, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The differential signal DIFF is output by the seventh operational amplifier. The output terminal of the seventh operational amplifier is connected to one end of the fourth resistor, the non-inverting input is connected to one end of the second resistor, and the inverting input is connected to one end of the third resistor and the other end of the fourth resistor. The other end of the second resistor is connected to the AX / AY pin of the eighth gating switch and one end of the fifth resistor. The A and B pins of the eighth gating switch input Control signals and are connected to one end of the sixth resistor. The AX and BY pins are connected in parallel to input the Samp2 signal, and the AY and BX pins are connected in parallel to input the Samp1 signal. The other ends of the sixth resistor and the other ends of the fifth resistor are connected to ground.

[0026] Specifically, referring to Figures 1 and 2, the differential signal DIFF generated by the microprocessor assumes that if the color temperature of the reference LED is higher than that of the other LED, then the drive current signal Samp1 is greater than the drive current signal Samp2. After differential processing, the voltage of the differential signal DIFF is positive. At this time, one processing step is sufficient to input this signal to the inverting input of the sixth operational amplifier U6. However, if the color temperature of the reference LED is lower than that of the other LED, then the drive current signal Samp1 is less than the drive current signal Samp2, and the voltage of the differential signal DIFF is negative. Another processing step is needed to obtain a positive voltage differential signal DIFF before inputting it to the inverting input of the sixth operational amplifier U6. This ensures that the voltage range of the input to the inverting input of the sixth operational amplifier U6 is always within the voltage variation range of the non-inverting input of the sixth operational amplifier U6, allowing the circuit to output normally. Therefore, based on the above scheme, this embodiment proposes a design scheme that simplifies the processing logic. A single processing step can synthesize the different pulse control signal Pulse. In this scheme, the output state of the positive / inverse compensation control signal Control is first fed back to pins 11 and 10 of the eighth gating switch U8. Assuming the color temperature of the reference LED is higher than that of the other LED, the drive current signal Samp1 is greater than the drive current signal Samp2. The positive / inverse compensation control signal Control will then be high and fed back to the eighth gating switch U8. Pin 14 of the eighth gating switch U8 outputs the drive current signal Samp1, which is fed back to the non-inverting input of the seventh operational amplifier U7 via the second resistor R2. Pin 15 of the eighth gating switch U8 inputs the drive current signal Samp2 to the inverting input of the seventh operational amplifier U7 via the third resistor R3. The output of the seventh operational amplifier U7 is fed back to the inverting input via the fourth resistor R4, then differentially divided, and a differential signal is output. The positive voltage parameter DIFF is fed to the inverting input of the sixth operational amplifier U6. After the synthesis of the differential pulse control signal is completed by the above control process, if the color temperature value of the LED used as the reference light source is lower than that of the LED of another light source, the drive current signal Samp1 is less than the drive current signal Samp2. The positive / inverse compensation control signal Control will be low and fed back to the eighth gating switch U8. The 14 pin of the eighth gating switch U8 will output the drive current signal Samp2 and feed it back to the non-inverting input of the seventh operational amplifier U7 through the second resistor R2. The 15 pin of the eighth gating switch U8 will input the drive current signal Samp1 to the inverting input of the seventh operational amplifier U7 through the third resistor R3. The seventh operational amplifier U7 outputs the differential signal DIFF after differential conversion and returns it to the inverting input of the sixth operational amplifier U6. The output of the seventh operational amplifier U7 is fed back to the inverting input through the fourth resistor R4 and differentially converted. It still outputs the differential signal DIFF with positive voltage parameter to the inverting input of the sixth operational amplifier U6.

[0027] In one embodiment, the LED driving unit includes a first light-emitting diode D1, a second light-emitting diode D2, a seventh resistor R7, an eighth resistor R8, a second P-type MOSFET Q2, a third N-type MOSFET Q3, and a ninth resistor R9. The anodes of the first light-emitting diode D1 and the second light-emitting diode D2 are powered by ADD_CP. The first light-emitting diode and the second light-emitting diode feed back a driving current signal Samp1 or a driving current signal Samp2 to the control unit and the processing unit. The cathode of the first light-emitting diode D1 is connected to one end of the seventh resistor R7; the other end of the seventh resistor R7 is connected to the source of the second P-type MOSFET Q2; the cathode of the second light-emitting diode D2 is connected to one end of the eighth resistor R8; the other end of the eighth resistor R8 is connected to the drain of the third N-type MOSFET Q3; the gates of the second P-type MOSFET Q2 and the third N-type MOSFET Q3, one end of the ninth resistor R9, and a PWM signal or a Pulse signal are connected; the other end of the ninth resistor R9, the source of the third N-type MOSFET Q3, the drain of the second P-type MOSFET Q2, and the ground terminal are connected.

[0028] Specifically, referring to Figures 4 and 5, assuming Figure 4 is used as the reference light source, the driving current signals Samp1 and Samp2 convert the sampled driving current of the first LED D1 or the second LED D2 into voltage via the seventh resistor R7 or the eighth resistor R8. Subsequently, the control unit and processing unit generate an aberration control signal Pulse, which is input to the gates of the second P-type MOSFET Q2 and the third N-type MOSFET Q3. The LED driving unit can also provide constant current through the ADD_CP port to adjust the brightness and color difference. When the aberration control signal Pulse is high, the third N-type MOSFET Q3 is turned on while the second P-type MOSFET Q2 is turned off. The ADD_CP current forms a path through the second LED D2, the eighth resistor R8, the third N-type MOSFET Q3, and the ground terminal, and the second LED D2 is working. Conversely, when the ADD_CP current is low, the second P-type MOSFET Q2 is turned on while the third N-type MOSFET Q3 is turned off, and the ADD_CP current forms a path through the first LED D1, the seventh resistor R7, the second P-type MOSFET Q2, and the ground terminal, and the first LED D1 is working.

Claims

1. A color difference control circuit for a mixed-color COB light source, characterized in that, It includes a control unit, a processing unit and multiple LED driving units. The control unit selects the pulse duty cycle and driving current signal Samp1 of the LED driving unit at the current color temperature as a reference, and the signal corresponding to the pulse duty cycle is the reference pulse signal Pwm. The control unit then acquires the drive current signal Samp2 from another LED driver unit and generates a positive / negative compensation control signal Control. The processing unit differentially divides Samp1 and Samp2 to generate a differential signal DIFF, which is fed back to the control unit. Based on the Control level and the amplitude of the differential signal DIFF, the control unit synthesizes a different pulse control signal Pulse with the same frequency as PWM and whose compensation pulse width matches the value of the differential signal DIFF, and sends it to the LED driver unit.

2. The color difference control circuit for a COB light source according to claim 1, characterized in that, The control unit includes a first P-type MOSFET, a first capacitor, a first resistor, a first operational amplifier, a second operational amplifier, a third XOR gate, a fourth AND gate, a fifth NOT gate, and a sixth operational amplifier. The non-inverting input of the first operational amplifier receives the Samp1 signal, the inverting input receives the Samp2 signal, and its output is connected to one input of the third XOR gate. The other input of the third XOR gate is connected to the output of the fifth NOT gate, and the output outputs the Pulse signal. The output of the fourth AND gate is connected to the input of the fifth NOT gate. One input of the fourth AND gate is connected to one end of the first resistor, the gate of the first P-type MOSFET, and the output of the second operational amplifier. The other input is connected to the output of the sixth operational amplifier. The non-inverting input of the second operational amplifier receives the PWM signal. The inverting input of the sixth operational amplifier receives the differential signal DIFF. The non-inverting input is connected to the other end of the first resistor, one end of the first capacitor, and the source of the first P-type MOSFET. The drain of the first P-type MOSFET, the other end of the first capacitor, and the ground terminal are connected.

3. The color difference control circuit for a mixed-color COB light source according to claim 1, characterized in that, The processing unit includes a seventh operational amplifier, an eighth gating switch, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor. The differential signal DIFF is output by the seventh operational amplifier. The output terminal of the seventh operational amplifier is connected to one end of the fourth resistor, the non-inverting input is connected to one end of the second resistor, and the inverting input is connected to one end of the third resistor and the other end of the fourth resistor. The other end of the second resistor is connected to the AX / AY pin of the eighth gating switch and one end of the fifth resistor. The A and B pins of the eighth gating switch input Control signals and are connected to one end of the sixth resistor. The AX and BY pins are connected in parallel to input the Samp2 signal, and the AY and BX pins are connected in parallel to input the Samp1 signal. The other ends of the sixth resistor and the other ends of the fifth resistor are connected to ground.

4. The color difference control circuit for a mixed-color COB light source according to claim 1, characterized in that, The processing unit includes a microprocessor, which acquires Samp1 and Samp2 signals for differential processing, and inputs the positive voltage differential signal DIFF to the control unit when it generates the differential signal. The microprocessor also outputs a pulse signal to the LED driver unit.

5. The color difference control circuit for a mixed-color COB light source according to claim 1, characterized in that, The LED driving unit includes a first light-emitting diode, a second light-emitting diode, a seventh resistor, an eighth resistor, a second P-type MOSFET, a third N-type MOSFET, and a ninth resistor. The anodes of the first and second light-emitting diodes are powered by ADD_CP. The first and second light-emitting diodes feed back driving current signals Samp1 or Samp2 to the control unit and processing unit. The cathode of the first light-emitting diode is connected to one end of the seventh resistor; the other end of the seventh resistor is connected to the source of the second P-type MOSFET; the cathode of the second light-emitting diode is connected to one end of the eighth resistor; the other end of the eighth resistor is connected to the drain of the third N-type MOSFET; the gates of the second P-type MOSFET, the third N-type MOSFET, and one end of the ninth resistor are connected to a PWM signal or a Pulse signal; the other end of the ninth resistor, the source of the third N-type MOSFET, the drain of the second P-type MOSFET, and the ground terminal are connected.

6. The color difference control circuit for a mixed-color COB light source according to claim 2, characterized in that, The control unit also includes a pulse generator, which generates the pulse signal for the LED driving unit.

7. The color difference control circuit for a COB light source according to claim 4, characterized in that, The pulse signal for the LED driving unit is provided by a microprocessor.

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