A novel thyristor constant-voltage digital dimming circuit

Abstract

The present invention provides a novel thyristor constant-voltage digital dimming circuit, which relates to the technical field of LED lighting dimming and includes: a dimming detection module connected to the output end of a thyristor dimmer, for converting a detected dimming signal generated by the thyristor dimmer into a corresponding pulse-width modulation signal and outputting it; a constant-voltage dimming module connected to the dimming detection module and a dimming switch module respectively, the dimming switch module is connected to a lamp, for receiving the pulse-width modulation signal, comparing the pulse-width modulation signal with a preset reference signal, and when the pulse-width modulation signal is greater than the preset reference signal, controlling the on / off of the dimming switch module according to the pulse-width modulation signal to perform constant-voltage dimming on the lamp. The beneficial effect is that during the dimming process of the LED lamp, the light is softer and more delicate, and when the knob of the thyristor dimmer is rotated to the minimum, the output of the pulse-width modulation signal can be completely turned off without the phenomenon of weak light emission.

Description

Technical Field

[0001] The present invention relates to the technical field of LED lighting dimming, and particularly to a novel thyristor constant voltage digital dimming circuit. Background Art

[0002] With the increasing application of LED lamps in the fields of home and commercial lighting, in many application scenarios, people need to control LED lamps through a simpler and more user-friendly control method. Thyristor dimming is a physical dimming method. Starting from the AC phase 0, the input voltage is chopped until the thyristor conducts, and then there is voltage input. Its principle is to adjust the conduction angle of each half-wave of the alternating current to change the sine wave shape, thereby changing the effective value of the alternating current to achieve the purpose of dimming. Thyristor dimmers have the advantages of high adjustment accuracy, high efficiency, small volume, light weight, and easy remote control, and dominate the market. Most manufacturers' products are of this type of dimmer.

[0003] The advantages of using a thyristor dimmer on an LED lighting lamp are: low dimming cost. The disadvantage is that the thyristor dimming performance is poor, usually resulting in a reduced dimming range. Due to the property of the thyristor semi-controlled switch, it only has the function of turning on the current and cannot completely turn off the current. Even when adjusted to the lowest level, there is still a weak current passing through. And due to the characteristic of the LED that it emits light with a very small current, there is still a phenomenon that the LED still emits weak light after being turned off when using thyristor dimming, which has become a difficult problem in the popularization of the current LED dimming method. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the present invention provides a novel thyristor constant voltage digital dimming circuit, including:

[0005] A dimming detection module, connected to the output end of a thyristor dimmer, for converting a detected dimming signal generated by the thyristor dimmer into a corresponding pulse width modulation signal and outputting it;

[0006] A constant voltage dimming module, respectively connected to the dimming detection module and a dimming switch module, the dimming switch module is connected to a lamp, for receiving the pulse width modulation signal, comparing the pulse width modulation signal with a preset reference signal, and when the pulse width modulation signal is greater than the preset reference signal, controlling the on-off of the dimming switch module according to the pulse width modulation signal to perform constant voltage dimming on the lamp.

[0007] Preferably, the dimming detection module includes:

[0008] An active load unit, which is connected to the output end of the thyristor dimmer through a first detection end and a second detection end, and is used to maintain the working current of the thyristor dimmer to be greater than a minimum holding current;

[0009] A signal detection unit, connected to the active load unit, for receiving the dimming signal and converting the dimming signal into a corresponding pulse width adjustment signal and outputting it.

[0010] Preferably, the active load unit includes:

[0011] A first resistor, one end of the first resistor is connected to one end of a second resistor, the other end of the first resistor is respectively connected to the cathode of a first diode and the cathode of a second diode, the anode of the first diode is connected to the first detection end, and the anode of the second diode is connected to the second detection end;

[0012] A third resistor, one end of the third resistor is connected to the other end of the second resistor, the other end of the third resistor is respectively connected to the cathode of a third diode, one end of a first capacitor and one end of a fourth resistor, and the other end of the fourth resistor is grounded;

[0013] A first triode, the base of the first triode is connected to one end of the fourth resistor, the collector of the first triode is connected to one end of a fifth resistor, the other end of the fifth resistor is connected to the other end of the second resistor, and the emitter of the first triode is grounded;

[0014] A first transistor, the gate of the first transistor is respectively connected to the collector of the first triode and the cathode of a breakdown diode, the anode of the breakdown diode is grounded, the drain of the first transistor is connected to the other end of the second resistor, the source of the first transistor is respectively connected to the anode of the third diode, the other end of the first capacitor and one end of a sixth resistor, and the other end of the sixth resistor is connected in series with a seventh resistor and then grounded.

[0015] Preferably, the signal detection unit includes:

[0016] An eighth resistor, one end of the eighth resistor is connected to the other end of the second resistor, and the other end of the eighth resistor is connected in series with a ninth resistor and a tenth resistor and then grounded;

[0017] A second triode, the base of the second triode is respectively connected to the connection point of the ninth resistor and the tenth resistor, and one end of an eleventh resistor, the other end of the eleventh resistor is grounded, the collector of the second triode is respectively connected to the cathode of a primary diode of an optocoupler and one end of a twelfth resistor, and the emitter of the second triode is grounded;

[0018] The thirteenth resistor, one end of the thirteenth resistor is respectively connected to the other end of the twelfth resistor and the anode of the primary side diode of the optocoupler, and the other end of the thirteenth resistor is connected to a 15V power supply.

[0019] Preferably, the constant voltage dimming module includes:

[0020] A signal comparison unit, configured to receive the pulse width modulation signal, and output the pulse width modulation signal when the pulse width modulation signal is greater than the preset reference signal, and output a turn-off signal when the pulse width modulation signal is not greater than the preset reference signal;

[0021] A signal transmission unit, connected to the signal comparison unit, configured to transmit the pulse width modulation signal to the dimming switch module to control the on / off of the dimming switch module, and stop transmitting the pulse width modulation signal according to the turn-off signal.

[0022] Preferably, the signal comparison unit includes:

[0023] A third triode, the base of the third triode is respectively connected to one end of a fourteenth resistor and one end of a second capacitor, the other end of the second capacitor is grounded, the collector of the third triode is connected to a 5V power supply, and the emitter of the third triode is grounded through a fifteenth resistor;

[0024] A sixteenth resistor, one end of the sixteenth resistor is respectively connected to the collector of a secondary side triode of the optocoupler and the other end of the fourteenth resistor, the other end of the sixteenth resistor is connected to the 5V power supply, and the emitter of the secondary side triode is grounded.

[0025] Preferably, the signal transmission unit includes:

[0026] A microprocessor, the fifth pin of the microprocessor is connected to the emitter of the third triode through a seventeenth resistor, the second pin of the microprocessor is the output port of the constant voltage dimming module, and the eighth pin of the microprocessor is grounded;

[0027] A voltage regulator chip, the third pin of the voltage regulator chip is connected to a power supply, the second pin of the voltage regulator chip is grounded, and the first pin of the voltage regulator chip is connected to the 5V power supply;

[0028] A third capacitor, one end of the third capacitor is connected to the first pin of the voltage regulator chip, and the other end of the third capacitor is grounded;

[0029] A fourth capacitor, one end of the fourth capacitor is respectively connected to the first pin of the voltage regulator chip and the first pin of the microprocessor, and the other end of the fourth capacitor is grounded;

[0030] A fifth capacitor, one end of the fifth capacitor is respectively connected to the first pin of the microprocessor and one end of the fourth capacitor, and the other end of the fifth capacitor is grounded.

[0031] Preferably, the dimming switch module includes:

[0032] A switching chip, the fifth pin of the switching chip is connected to the output end of the constant voltage dimming module through an eighteenth resistor, the first pin of the switching chip is connected to a power supply, and the fourth pin of the switching chip is grounded;

[0033] A second transistor, the gate of the second transistor is connected to the third pin of the switching chip through a nineteenth resistor, the gate of the second transistor is also connected to the source of the second transistor through a twentieth resistor, and the drain of the second transistor is connected to the negative electrode of the lamp;

[0034] A sixth capacitor, the negative electrode of the sixth capacitor is connected to the source of the second transistor, and the positive electrode of the sixth capacitor is connected to the positive electrode of the lamp.

[0035] Preferably, it further includes a discharging module, which is respectively connected to the thyristor dimmer and the dimming detection module. The discharging module includes:

[0036] A first passive discharger, including a seventh capacitor and a twenty-first resistor. One end of the seventh capacitor is connected to the live wire, the other end of the seventh capacitor is connected to the other end of the twenty-first resistor, and the other end of the twenty-first resistor is connected to the neutral wire;

[0037] A second passive discharger, including an eighth capacitor and a twenty-second resistor. One end of the eighth capacitor is connected to the live wire, the other end of the eighth capacitor is connected to the other end of the twenty-second resistor, and the other end of the twenty-second resistor is connected to the neutral wire;

[0038] A first common mode inductor, two windings of the first common mode inductor are respectively connected to the neutral wire and the live wire, and it is located between the first passive discharger and the second passive discharger;

[0039] A second common mode inductor, two windings of the second common mode inductor are respectively connected to the neutral wire and the live wire, and it is located at the rear stage of the second passive discharger;

[0040] A twenty-third resistor is arranged at the rear stage of the second common mode inductor. One end of the twenty-third resistor is connected to the live wire and serves as the first detection end. The other end of the twenty-third resistor is connected to one end of a twenty-fourth resistor, and the other end of the twenty-fourth resistor is connected to the neutral wire and serves as the second detection end;

[0041] A rectifier bridge, with two AC pins of the rectifier bridge respectively connected to the neutral wire and the live wire and used as the first detection end and the second detection end.

[0042] Preferably, the thyristor dimmer is connected in series with the neutral wire or the live wire.

[0043] The above technical solution has the following advantages or beneficial effects:

[0044] 1) The microprocessor samples the dimming signal of the thyristor dimmer, and then through digital coding, outputs a pulse width modulation signal of high and low levels to control the magnitude of the current of the dimming switch module, thereby controlling the brightness of the LED lamp. The circuit is simple and reliable, with fewer components, low cost, and strong anti-interference ability;

[0045] 2) During the dimming process of the LED lamp, the light is softer and more delicate. When the knob of the thyristor dimmer is rotated to the minimum, the output of the pulse width modulation signal can be completely turned off, and there is no phenomenon of weak light emission. Description of the Drawings

[0046] Figure 1 In a preferred embodiment of the present invention, it is the circuit schematic diagram of a novel thyristor constant voltage digital dimming circuit;

[0047] Figure 2 In a preferred embodiment of the present invention, it is the circuit diagram of a novel thyristor constant voltage digital dimming circuit. Detailed Embodiments

[0048] The present invention will be described in detail below with reference to the drawings and specific embodiments. The present invention is not limited to this embodiment, and other embodiments may also fall within the scope of the present invention as long as they conform to the gist of the present invention.

[0049] In a preferred embodiment of the present invention, based on the above problems existing in the prior art, a novel thyristor constant voltage digital dimming circuit is provided, as Figures 1 to 2 shown, including:

[0050] A dimming detection module 1, connected to the output end of a thyristor dimmer 2, for converting a detected dimming signal generated by the thyristor dimmer 2 into a corresponding pulse width modulation signal and outputting it;

[0051] A constant voltage dimming module 3, respectively connected to the dimming detection module 1 and a dimming switch module 4, and the dimming switch module 4 is connected to a lamp LED, for receiving the pulse width modulation signal, comparing the pulse width modulation signal with a preset reference signal, and when the pulse width modulation signal is greater than the preset reference signal, controlling the on-off of the dimming switch module 4 according to the pulse width modulation signal to perform constant voltage dimming on the lamp.

[0052] Specifically, in this embodiment, the thyristor dimmer 2 can be connected in series to any of the AC input lines L or N. For the AC power supply terminals L and N of the constant-voltage thyristor dimming driver, when in use, the two lead wires of the thyristor dimmer, one is connected to the L line of the mains, and the other wire is connected to the AC power supply terminal L of the constant-voltage thyristor dimming driver. By rotating the knob of the thyristor dimmer, the conduction angle of the AC half-wave of the thyristor is changed, and then through the dimming detection module, the dimming signal is converted into a square wave signal with a changing duty cycle, that is, a pulse width modulation signal. This pulse width modulation signal is transmitted to the constant-voltage dimming module 3, and when the pulse width modulation signal is greater than a preset reference signal, it is output to the dimming switch module 4 to achieve dimming of the LED of the lamp. It can be seen that if the knob of the thyristor dimmer is rotated to the minimum, the pulse width modulation signal is too small and not greater than the preset reference signal, making the signal at the dimming input terminal of the microprocessor IC1 in the constant-voltage dimming module 3 too small, and the microprocessor IC1 cannot output a driving signal, thereby completely turning off the dimming switch module 4, effectively solving the problem of weak LED light emission.

[0053] In a preferred embodiment of the present invention, the dimming detection module 1 includes:

[0054] An active load unit 11, the active load unit 11 is connected to the output terminal of the thyristor dimmer 2 through a first detection terminal AC1 and a second detection terminal AC2, and is used to maintain the operating current of the thyristor dimmer 2 greater than a minimum holding current;

[0055] A signal detection unit 12, connected to the active load unit 11, for receiving the dimming signal and converting the dimming signal into a corresponding pulse width adjustment signal and outputting it.

[0056] Specifically, in this embodiment, for the thyristor dimmer 2 at the input end, when sliding the potentiometer, the conduction angle of each half-wave of the alternating current is adjusted to change the sine waveform, thereby changing the effective value of the alternating current, so as to achieve the purpose of dimming. The output of the thyristor dimmer 2 is connected to the active load unit 11 and the signal detection unit 12 through the first detection terminal AC1 and the second detection terminal AC2 in the circuit. The signal detection unit 12 can monitor the dimming signal by detecting the change of the above-mentioned conduction angle, and after signal conversion, it is connected to the constant-voltage dimming module 3 for digital encoding and then output to the dimming switch module 4 to change the brightness of the LED lamp according to the pulse width of the converted PWM signal. Among them, the active load unit 11 is used to maintain the operating current of the thyristor dimmer 2 greater than its minimum holding current IH to make it work normally; the signal detection unit 12 is used to sample the dimming signal of the thyristor dimmer, convert it into a pulse width modulation signal with high and low level changes, and input it into the microprocessor IC1 of the constant-voltage dimming module 3 for processing; and then the constant-voltage dimming module 3 drives the opening and closing of the dimming switch module to achieve the purpose of dimming.

[0057] In a preferred embodiment of the present invention, the active load unit 11 includes:

[0058] A first resistor R1, one end of the first resistor R1 is connected to one end of a second resistor R2, the other end of the first resistor R1 is respectively connected to the cathode of a first diode D1 and the cathode of a second diode D2, the anode of the first diode D1 is connected to the first detection terminal AC1, and the anode of the second diode D2 is connected to the second detection terminal AC2;

[0059] A third resistor R3, one end of the third resistor R3 is connected to the other end of the second resistor R2, the other end of the third resistor R3 is respectively connected to the cathode of a third diode D3, one end of a first capacitor C1, and one end of a fourth resistor R4, and the other end of the fourth resistor R4 is grounded;

[0060] A first triode Q1, the base of the first triode Q1 is connected to one end of the fourth resistor R4, the collector of the first triode Q1 is connected to one end of a fifth resistor R5, the other end of the fifth resistor R5 is connected to the other end of the second resistor R2, and the emitter of the first triode Q1 is grounded;

[0061] A first transistor M1, the gate of the first transistor M1 is respectively connected to the collector of the first triode Q1 and the cathode of a breakdown diode ZD, the anode of the breakdown diode ZD is grounded, the drain of the first transistor M1 is connected to the other end of the second resistor R2, and the source of the first transistor M1 is respectively connected to the anode of the third diode D3, the other end of the first capacitor C1, and one end of a sixth resistor R6, and the other end of the sixth resistor R6 is grounded after being connected in series with a seventh resistor R7.

[0062] In a preferred embodiment of the present invention, the signal detection unit 12 includes:

[0063] An eighth resistor R8, one end of the eighth resistor R8 is connected to the other end of the second resistor R2, and the other end of the eighth resistor R8 is grounded after being connected in series with a ninth resistor R9 and a tenth resistor R10 in sequence;

[0064] A second triode Q2, the base of the second triode Q2 is respectively connected to the connection point of the ninth resistor R9 and the tenth resistor R10, and one end of an eleventh resistor R11, the other end of the eleventh resistor R11 is grounded, the collector of the second triode Q2 is respectively connected to the cathode of a primary diode of an optocoupler PC and one end of a twelfth resistor R12, and the emitter of the second triode Q2 is grounded;

[0065] A thirteenth resistor R13, one end of the thirteenth resistor R13 is respectively connected to the other end of the twelfth resistor R12 and the anode of the primary diode of the optocoupler PC, and the other end of the thirteenth resistor R13 is connected to a 15V power supply.

[0066] Specifically, in this embodiment, the signal detection unit 12 controls the conduction and cutoff of the second triode Q2 to convert the dimming signal into a square wave signal with a varying duty cycle, that is, a pulse width modulation signal. Subsequently, the pulse width modulation signal is transmitted to the constant voltage dimming module 3 through the optocoupler PC to achieve optoelectronic isolation.

[0067] In a preferred embodiment of the present invention, the constant voltage dimming module 3 includes:

[0068] A signal comparison unit 31, configured to receive the pulse width modulation signal, output the pulse width modulation signal when the pulse width modulation signal is greater than a preset reference signal, and output a cutoff signal when the pulse width modulation signal is not greater than the preset reference signal;

[0069] A signal transmission unit 32, connected to the signal comparison unit 31, configured to transmit the pulse width modulation signal to the dimming switch module to control the on / off of the dimming switch module 4, and stop transmitting the pulse width modulation signal according to the cutoff signal.

[0070] In a preferred embodiment of the present invention, the signal comparison unit 31 includes:

[0071] A third triode Q3, the base of the third triode Q3 is respectively connected to one end of a fourteenth resistor R14 and one end of a second capacitor C2, the other end of the second capacitor C2 is grounded, the collector of the third triode Q3 is connected to a 5V power supply, and the emitter of the third triode Q3 is grounded through a fifteenth resistor R15;

[0072] A sixteenth resistor R16, one end of the sixteenth resistor R16 is respectively connected to the collector of a sub - side triode of the optocoupler PC and the other end of the fourteenth resistor R14, the other end of the sixteenth resistor R16 is connected to the 5V power supply, and the emitter of the sub - side triode is grounded.

[0073] Specifically, in this embodiment, by reasonably setting the preset reference signal, when the received pulse width modulation signal is greater than the preset reference signal, the third triode Q3 is controlled to conduct, and then the pulse width modulation signal is transmitted to the signal transmission unit 32 through the emitter of the third triode Q3.

[0074] In a preferred embodiment of the present invention, the signal transmission unit 32 includes:

[0075] A microprocessor IC1, the fifth pin of the microprocessor IC1 is connected to the emitter of the third triode through a seventeenth resistor, the second pin of the microprocessor IC1 is the output port of the constant voltage dimming module, and the eighth pin of the microprocessor IC1 is grounded;

[0076] The voltage regulator chip IC2, the third pin of the voltage regulator chip IC2 is connected to a power supply VCC, the second pin of the voltage regulator chip IC2 is grounded, and the first pin of the voltage regulator chip IC2 is connected to a 5V power supply;

[0077] The third capacitor C3, one end of the third capacitor C3 is connected to the first pin of the voltage regulator chip IC2, and the other end of the third capacitor C3 is grounded;

[0078] The fourth capacitor C4, one end of the fourth capacitor C4 is respectively connected to the first pin of the voltage regulator chip and the first pin of the microprocessor IC1, and the other end of the fourth capacitor C4 is grounded;

[0079] The fifth capacitor C5, one end of the fifth capacitor C5 is respectively connected to the first pin of the microprocessor IC1 and one end of the fourth capacitor C4, and the other end of the fifth capacitor C5 is grounded.

[0080] Specifically, in this embodiment, the above-mentioned voltage regulator chip IC2, the third capacitor C3, the fourth capacitor C4 and the fifth capacitor C5 are the power supply circuit for the microprocessor IC1. The above-mentioned voltage regulator is a three-terminal voltage regulator.

[0081] In a preferred embodiment of the present invention, the dimming switch module 4 includes:

[0082] The switch chip IC3, the fifth pin of the switch chip IC3 is connected to the output end of the constant voltage dimming module through an eighteenth resistor R18, the first pin of the switch chip IC3 is connected to a power supply VCC, and the fourth pin of the switch chip IC3 is grounded;

[0083] The second transistor M2, the gate of the second transistor M2 is connected to the third pin of the switch chip IC3 through a nineteenth resistor R19, the gate of the second transistor M2 is also connected to the source of the second transistor M2 through a twentieth resistor R20, and the drain of the second transistor M2 is connected to the negative pole of the lamp LED;

[0084] The sixth capacitor C6, the negative pole of the sixth capacitor C6 is connected to the source of the second transistor M2, and the positive pole of the sixth capacitor C6 is connected to the positive pole of the lamp LED.

[0085] Specifically, in this embodiment, the switch chip IC3 drives the G-S of the second transistor M2, and dims the lamp LED according to the pulse width of the pulse width modulation signal.

[0086] In a preferred embodiment of the present invention, it further includes a discharge module 5, which is respectively connected to the thyristor dimmer 2 and the dimming detection module 1. The discharge module 5 includes:

[0087] The first passive discharge device 51 includes a seventh capacitor C7 and a twenty-first resistor R21. One end of the seventh capacitor C7 is connected to the live wire L, and the other end of the seventh capacitor C7 is connected to the other end of the twenty-first resistor R21. The other end of the twenty-first resistor R21 is connected to the neutral wire N;

[0088] The second passive discharge device 52 includes an eighth capacitor C8 and a twenty-second resistor R22. One end of the eighth capacitor C8 is connected to the live wire L, and the other end of the eighth capacitor C8 is connected to the other end of the twenty-second resistor R22. The other end of the twenty-second resistor R22 is connected to the neutral wire N;

[0089] The first common-mode inductor LF1 has two windings respectively connected to the neutral wire N and the live wire L, and is located between the first passive discharge device 51 and the second passive discharge device 52;

[0090] The second common-mode inductor LF2 has two windings respectively connected to the neutral wire N and the live wire L, and is located at the subsequent stage of the second passive discharge device 52;

[0091] The twenty-third resistor R23 is arranged at the subsequent stage of the second common-mode inductor LF2. One end of the twenty-third resistor R23 is connected to the live wire L and serves as the first detection terminal AC1. The other end of the twenty-third resistor R23 is connected to one end of a twenty-fourth resistor R24. The other end of the twenty-fourth resistor R24 is connected to the neutral wire N and serves as the second detection terminal AC2;

[0092] The rectifier bridge BD has its two AC pins respectively connected to the neutral wire N and the live wire L and serves as the first detection terminal AC1 and the second detection terminal AC2.

[0093] Specifically, in this embodiment, by providing the first passive discharge device 51 and the second passive discharge device 52 to form a two-stage passive discharge device, it is ensured that when the conduction angle of the thyristor dimmer is the smallest, it is greater than its minimum holding current, so that it can work normally.

[0094] In a preferred embodiment of the present invention, the thyristor dimmer 2 is connected in series to the neutral wire N or the live wire L.

[0095] The above are only preferred embodiments of the present invention, and thus do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all equivalent replacements and obvious changes made by using the content of this specification and the drawings should be included in the protection scope of the present invention.

Claims

1. A novel thyristor constant-voltage digital dimming circuit, characterized in that, Including: A dimming detection module, connected to the output end of a thyristor dimmer, for converting a detected dimming signal generated by the thyristor dimmer into a corresponding pulse width modulation signal and outputting it; A constant voltage dimming module, respectively connected to the dimming detection module and a dimming switch module, the dimming switch module being connected to a lamp, for receiving the pulse width modulation signal, comparing the pulse width modulation signal with a preset reference signal, and when the pulse width modulation signal is greater than the preset reference signal, controlling the on / off of the dimming switch module according to the pulse width modulation signal to perform constant voltage dimming on the lamp.

2. The novel thyristor constant-voltage digital dimming circuit according to claim 1, characterized in that, The dimming detection module includes: An active load unit, the active load unit being connected to the output end of the thyristor dimmer through a first detection end and a second detection end, for maintaining the working current of the thyristor dimmer greater than a minimum holding current; A signal detection unit, connected to the active load unit, for receiving the dimming signal and converting the dimming signal into the corresponding pulse width adjustment signal and outputting it.

3. The novel thyristor constant-voltage digital dimming circuit according to claim 2, characterized in that, The active load unit includes: A first resistor, one end of the first resistor being connected to one end of a second resistor, the other end of the first resistor being respectively connected to the cathode of a first diode and the cathode of a second diode, the anode of the first diode being connected to the first detection end, and the anode of the second diode being connected to the second detection end; A third resistor, one end of the third resistor being connected to the other end of the second resistor, the other end of the third resistor being respectively connected to the cathode of a third diode, one end of a first capacitor, and one end of a fourth resistor, the other end of the fourth resistor being grounded; A first triode, the base of the first triode being connected to one end of the fourth resistor, the collector of the first triode being connected to one end of a fifth resistor, the other end of the fifth resistor being connected to the other end of the second resistor, and the emitter of the first triode being grounded; A first transistor, the gate of the first transistor being respectively connected to the collector of the first triode and the cathode of a zener diode, the anode of the zener diode being grounded, the drain of the first transistor being connected to the other end of the second resistor, and the source of the first transistor being respectively connected to the anode of the third diode, the other end of the first capacitor, and one end of a sixth resistor, the other end of the sixth resistor being grounded after being connected in series with a seventh resistor.

4. The novel thyristor constant-voltage digital dimming circuit according to claim 3, characterized in that, The signal detection unit includes: An eighth resistor, one end of the eighth resistor being connected to the other end of the second resistor, and the other end of the eighth resistor being grounded after being connected in series with a ninth resistor and a tenth resistor in sequence; A second triode, the base of the second triode being respectively connected to the connection point of the ninth resistor and the tenth resistor, and one end of an eleventh resistor, the other end of the eleventh resistor being grounded, the collector of the second triode being respectively connected to the cathode of a primary diode of an optocoupler and one end of a twelfth resistor, and the emitter of the second triode being grounded; The thirteenth resistor, one end of the thirteenth resistor is respectively connected to the other end of the twelfth resistor and the anode of the primary side diode of the optocoupler, and the other end of the thirteenth resistor is connected to a 15V power supply.

5. The novel thyristor constant-voltage digital dimming circuit according to claim 4, characterized in that, The constant voltage dimming module includes: A signal comparison unit, configured to receive the pulse width modulation signal, and output the pulse width modulation signal when the pulse width modulation signal is greater than the preset reference signal, and output a turn-off signal when the pulse width modulation signal is not greater than the preset reference signal; A signal transmission unit, connected to the signal comparison unit, configured to transmit the pulse width modulation signal to the dimming switch module to control the on / off of the dimming switch module, and stop transmitting the pulse width modulation signal according to the turn-off signal.

6. The novel thyristor constant-voltage digital dimming circuit according to claim 5, characterized in that, The signal comparison unit includes: A third triode, the base of the third triode is respectively connected to one end of a fourteenth resistor and one end of a second capacitor, the other end of the second capacitor is grounded, the collector of the third triode is connected to a 5V power supply, and the emitter of the third triode is grounded through a fifteenth resistor; A sixteenth resistor, one end of the sixteenth resistor is respectively connected to the collector of a secondary side triode of the optocoupler and the other end of the fourteenth resistor, the other end of the sixteenth resistor is connected to the 5V power supply, and the emitter of the secondary side triode is grounded.

7. The novel thyristor constant-voltage digital dimming circuit according to claim 6, characterized in that, The signal transmission unit includes: A microprocessor, the fifth pin of the microprocessor is connected to the emitter of the third triode through a seventeenth resistor, the second pin of the microprocessor is the output port of the constant voltage dimming module, and the eighth pin of the microprocessor is grounded; A voltage regulator chip, the third pin of the voltage regulator chip is connected to a power supply, the second pin of the voltage regulator chip is grounded, and the first pin of the voltage regulator chip is connected to the 5V power supply; A third capacitor, one end of the third capacitor is connected to the first pin of the voltage regulator chip, and the other end of the third capacitor is grounded; A fourth capacitor, one end of the fourth capacitor is respectively connected to the first pin of the voltage regulator chip and the first pin of the microprocessor, and the other end of the fourth capacitor is grounded; A fifth capacitor, one end of the fifth capacitor is respectively connected to the first pin of the microprocessor and one end of the fourth capacitor, and the other end of the fifth capacitor is grounded.

8. The novel thyristor constant-voltage digital dimming circuit according to claim 1, characterized in that, The dimming switch module includes: A switch chip, the fifth pin of the switch chip is connected to the output end of the constant voltage dimming module through an eighteenth resistor, the first pin of the switch chip is connected to a power supply, and the fourth pin of the switch chip is grounded; A second transistor, the gate of the second transistor is connected to the third pin of the switch chip through a nineteenth resistor, the gate of the second transistor is also connected to the source of the second transistor through a twentieth resistor, and the drain of the second transistor is connected to the negative electrode of the lamp; A sixth capacitor, the negative electrode of the sixth capacitor is connected to the source of the second transistor, and the positive electrode of the sixth capacitor is connected to the positive electrode of the lamp.

9. The novel thyristor constant-voltage digital dimming circuit according to claim 2, wherein, It further includes a discharge module, which is respectively connected to the thyristor dimmer and the dimming detection module. The discharge module includes: The first passive discharge device includes a seventh capacitor and a twenty-first resistor. One end of the seventh capacitor is connected to the live wire, the other end of the seventh capacitor is connected to the other end of the twenty-first resistor, and the other end of the twenty-first resistor is connected to the neutral wire; The second passive discharge device includes an eighth capacitor and a twenty-second resistor. One end of the eighth capacitor is connected to the live wire, the other end of the eighth capacitor is connected to the other end of the twenty-second resistor, and the other end of the twenty-second resistor is connected to the neutral wire; The first common-mode inductor has two windings respectively connected to the neutral wire and the live wire, and is located between the first passive discharge device and the second passive discharge device; The second common-mode inductor has two windings respectively connected to the neutral wire and the live wire, and is located at the subsequent stage of the second passive discharge device; The twenty-third resistor is arranged at the subsequent stage of the second common-mode inductor. One end of the twenty-third resistor is connected to the live wire and serves as the first detection terminal, the other end of the twenty-third resistor is connected to one end of a twenty-fourth resistor, and the other end of the twenty-fourth resistor is connected to the neutral wire and serves as the second detection terminal; The rectifier bridge has its two AC pins respectively connected to the neutral wire and the live wire and serves as the first detection terminal and the second detection terminal.

10. The novel thyristor constant-voltage digital dimming circuit according to claim 9, wherein, The thyristor dimmer is connected in series to the neutral wire or the live wire.

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