Switching type frequency flash removal circuit

Abstract

The application discloses a switching type frequency elimination flash circuit, comprising a filter capacitor for accessing the pulsed direct current of an adjustable light constant current circuit output, an adjustable constant current circuit for converting the direct current voltage output by the filter capacitor into direct current to drive an LED light emitting circuit to emit light, and a signal conversion circuit for generating a corresponding adjustment signal according to the average value of the voltage signal output by the filter capacitor, so as to control the adjustable constant current circuit to convert the input voltage connected thereto into corresponding direct current output in a switching conversion mode; the circuit has the advantages of high conversion efficiency, low cost, and low heat dissipation requirement.

Description

Technical Field

[0001] This invention relates to frequency-reducing lightning circuits, and more particularly to a switch-type frequency-reducing lightning circuit. Background Technology

[0002] Adjusting the brightness of a luminaire using a phase-cut dimmer is a common dimming method. A phase-cut dimmer has two terminals, and dimmable luminaires compatible with it have a live wire input and a neutral wire input. When dimming a luminaire using a phase-cut dimmer, one terminal of the dimmer is connected to the live wire of the mains power supply, the live wire input of the luminaire is connected to the other terminal of the dimmer, and the neutral wire input is connected to the neutral wire of the mains power supply. By operating the dimmer, changing its conduction angle, the waveform of the chopped voltage between the live and neutral wire inputs of the luminaire is altered. Because the brightness of a dimmable luminaire corresponds to the voltage between its live and neutral wire inputs, the brightness changes as the conduction angle of the dimmer changes, thus achieving the function of adjusting the brightness of the luminaire using a phase-cut dimmer.

[0003] Existing dimmable LED luminaires compatible with phase-cut dimmers typically employ dimmable LED circuits that include a dimmable constant current circuit and an LED light-emitting circuit. When a chopper voltage is applied, the dimmable constant current circuit converts it into a corresponding DC current. When the applied chopper voltage is zero, its output current is zero; when the applied chopper voltage is not zero, its output is a DC current corresponding to the magnitude of the applied chopper voltage. Therefore, the output current of the dimmable constant current circuit is a periodically changing pulsating DC current. If the pulsating DC current output from the dimmable constant current circuit directly drives the LED light-emitting circuit, the luminous intensity of the LED light-emitting circuit will vary with the magnitude of the pulsating DC current, resulting in significant flicker. Therefore, dimmable LED luminaires requiring low flicker also include a flicker-reducing circuit in their dimmable LED circuitry. Figure 1 As shown, the frequency-reducing lightning circuit is set between the dimmable constant current circuit and the LED light-emitting circuit. At this time, the pulsating DC current output by the dimmable constant current circuit first passes through the frequency-reducing lightning circuit before driving the LED light-emitting circuit to emit light. The frequency-reducing lightning circuit transforms the input pulsating DC current and outputs a DC current with very small fluctuations, so that the LED light-emitting circuit can emit light without flicker.

[0004] Existing frequency-de-scanning circuits typically employ linear frequency-de-scanning circuits. The conversion efficiency of a linear frequency-de-scanning circuit is directly related to the capacitance of its internal filter capacitor. A larger filter capacitor results in higher conversion efficiency, while a smaller one results in lower efficiency. However, high-power dimmable LED lamp circuits require frequency-de-scanning circuits with high conversion efficiency. Therefore, linear frequency-de-scanning circuits need to use large-capacity filter capacitors to meet these requirements, which increases the cost of the circuit. Furthermore, since the heat generated by a linear frequency-de-scanning circuit is mainly concentrated on its internal semiconductor devices, high heat dissipation requirements are necessary to ensure the performance of these devices. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a switching-type frequency reduction lightning circuit with high conversion efficiency, low cost and low heat dissipation requirements.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a switching-type frequency reduction circuit, including a filter capacitor for receiving the pulsating DC current output by an adjustable constant current circuit and an adjustable constant current circuit for converting the DC voltage output by the filter capacitor into a DC current to drive the LED light-emitting circuit to emit light, and a signal conversion circuit, wherein the signal conversion circuit is used to generate a corresponding adjustment signal based on the average value of the voltage signal output by the filter capacitor, so as to control the adjustable constant current circuit to convert the input voltage into a corresponding DC current output by switching.

[0007] The filter capacitor has a positive and a negative terminal. The adjustable constant current circuit has a positive terminal, a negative terminal, a positive output terminal, a negative output terminal, and an adjustment terminal. The signal conversion circuit has an input terminal, an output terminal, and a negative terminal. The positive terminal of the adjustable constant current circuit, the input terminal of the signal conversion circuit, and the positive terminal of the filter capacitor are connected, and their connection terminal is the positive input terminal of the switching-type frequency-de-lightning circuit. The adjustment terminal of the adjustable constant current circuit is connected to the output terminal of the signal conversion circuit. The negative terminal of the adjustable constant current circuit, the negative terminal of the signal conversion circuit, and the negative terminal of the filter capacitor are connected, and their connection terminal is the negative input terminal of the switching-type frequency-de-lightning circuit. The positive output terminal of the adjustable constant current circuit is the positive output terminal of the switching-type frequency-de-lightning circuit, and the negative output terminal of the adjustable constant current circuit is the negative output terminal of the switching-type frequency-de-lightning circuit. A voltage threshold is set at the signal conversion circuit, and the signal conversion circuit converts the voltage signal input to its input terminal into the adjustment signal at its output. The adjustable constant current circuit outputs a DC current between its positive and negative output terminals. When the average value of the voltage signal connected to the input terminal of the signal conversion circuit is greater than the voltage threshold, the magnitude of the adjustment signal corresponds to the average value of the voltage signal connected to the input terminal of the signal conversion circuit. The larger the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the larger the adjustment signal; the smaller the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the smaller the adjustment signal. When the average value of the voltage signal connected to the input terminal of the signal conversion circuit is less than or equal to the voltage threshold, the adjustment signal is 0. The magnitude of the DC current output between the positive and negative output terminals of the adjustable constant current circuit corresponds to the magnitude of the adjustment signal. The larger the adjustment signal, the larger the DC current output between the positive and negative output terminals of the adjustable constant current circuit; the smaller the adjustment signal, the smaller the DC current output between the positive and negative output terminals of the adjustable constant current circuit.

[0008] The adjustment signal is an analog voltage signal.

[0009] The adjustable constant current circuit also has a signal output terminal, the electrical signal output from which corresponds to the magnitude of the current input between its positive and negative terminals. The switching-type frequency-de-flash circuit further includes a linear constant current circuit, which has a positive terminal, a negative terminal, and a control terminal. The linear constant current circuit has an on-state and an off-state, and is set with a maximum on-current value and an on-voltage threshold. The on-voltage threshold is less than the voltage threshold. The positive terminal of the linear constant current circuit is connected to the positive terminal of the filter capacitor, and the negative terminal of the linear constant current circuit is connected to the filter capacitor. The negative terminal of the capacitor is connected, and the control terminal of the linear constant current circuit is connected to the signal output terminal of the adjustable constant current circuit. When the linear constant current circuit is in the conducting state, the current between its positive and negative terminals is less than or equal to the maximum conducting current value, and the voltage between its positive and negative terminals is greater than or equal to the conducting voltage threshold. The magnitude of the current between the positive and negative terminals of the linear constant current circuit corresponds to the electrical signal connected to its control terminal. The electrical signal output by the signal output terminal of the adjustable constant current circuit is used to control the linear constant current circuit to enter the conducting or cut-off state.

[0010] The signal conversion circuit includes a first resistor, a second resistor, a third resistor, a second capacitor, a first diode, and a first transistor. The first diode is a Zener diode, and the first transistor is a PNP transistor. One end of the first resistor and one end of the third resistor are connected, and their connection point is the input terminal of the signal conversion circuit. The other end of the first resistor is connected to the cathode of the first diode. The anode of the first diode, one end of the second resistor, one end of the second capacitor, and the base of the first transistor are connected. The emitter of the first transistor and the other end of the third resistor are connected, and their connection point is the output terminal of the signal conversion circuit. The other end of the second resistor, the other end of the second capacitor, and the collector of the first transistor are connected, and their connection point is the cathode of the signal conversion circuit.

[0011] The linear constant current circuit includes a first integrated circuit, a fourth resistor, a fifth resistor, and a second diode. The first integrated circuit is a JW1691H, the second diode is a Zener diode, one end of the fourth resistor is the positive terminal of the linear constant current circuit, the other end of the fourth resistor is connected to the negative terminal of the second diode, the positive terminal of the second diode is connected to the OUT pin of the first integrated circuit, the EXT pin of the first integrated circuit is connected to one end of the fifth resistor, the other end of the fifth resistor is the control terminal of the linear constant current circuit, and the GND pin of the first integrated circuit is the negative terminal of the linear constant current circuit.

[0012] The adjustable constant current circuit is an isolated adjustable constant current circuit. When the switching-type frequency-reducing lightning circuit using this adjustable constant current circuit, together with the existing non-isolated dimmable constant current circuit and the LED light-emitting circuit, constitutes a dimmable LED lamp circuit, the dimmable LED lamp circuit becomes an isolated output LED lamp circuit, which can be applied to isolated dimmable LED lamps and has a high cost performance.

[0013] The adjustable constant current circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a third diode, a fourth diode, a fifth diode, a sixth diode, an NMOS transistor, a first transformer, and a second integrated circuit. The ninth capacitor is an electrolytic capacitor. The third, fourth, fifth, and sixth diodes are all rectifier diodes. The first transformer includes a primary coil, a secondary coil, and an auxiliary coil. The second integrated circuit is a BP3378A. One end of the third capacitor and one end of the ninth resistor... One end of the tenth resistor, one end of the eighth capacitor, and one end of the primary coil of the first transformer are connected, and their connection ends are the positive terminals of the adjustable constant current circuit. The other end of the primary coil of the first transformer, the anode of the fourth diode, and the drain of the NMOS transistor are connected. The cathode of the fourth diode, the other end of the tenth resistor, and the other end of the eighth capacitor are connected. The gate of the NMOS transistor is connected to pin 5 of the second integrated circuit. Pin 3 of the second integrated circuit, the source of the NMOS transistor, and one end of the eleventh resistor are connected. Pin 1 of the second integrated circuit is connected to one end of the seventh capacitor. The first transformer... One end of the auxiliary coil of the first transformer, the positive terminal of the third diode, and one end of the sixth resistor are connected. The negative terminal of the third diode, the other end of the ninth resistor, one end of the fourth capacitor, and pin 6 of the second integrated circuit are connected. The other end of the sixth resistor, one end of the seventh resistor, and pin 2 of the second integrated circuit are connected. One end of the fifth capacitor is connected to pin 7 of the second integrated circuit, and its connection point is the adjustment terminal of the adjustable constant current circuit. The other end of the auxiliary coil of the first transformer, the other end of the third capacitor, the other end of the fourth capacitor, the other end of the fifth capacitor, one end of the sixth capacitor, and the other end of the seventh capacitor are also connected. The other end of the seventh resistor, one end of the eighth resistor, the other end of the eleventh resistor, the anode of the fifth diode, pin 8 of the second integrated circuit, and pin 4 of the second integrated circuit are connected, and their connection terminals are the signal output terminals of the adjustable constant current circuit. The other end of the eighth resistor, the other end of the sixth capacitor, and the cathode of the fifth diode are connected, and their connection terminals are the cathode of the adjustable constant current circuit. One end of the secondary coil of the first transformer is connected to the anode of the sixth diode. The cathode of the sixth diode, the anode of the ninth capacitor, and one end of the twelfth resistor are connected, and their connection terminals are the positive output terminals of the adjustable constant current circuit.The other end of the twelfth resistor, the negative terminal of the ninth capacitor, and the other end of the secondary coil of the first transformer are connected, and this connection point is the negative output terminal of the adjustable constant current circuit.

[0014] Compared with existing technologies, the advantages of this invention lie in the fact that by setting up a signal conversion circuit, the signal conversion circuit can generate a corresponding adjustment signal based on the average value of the voltage signal output by the filter capacitor. The magnitude of this adjustment signal does not change with the voltage fluctuations across the filter capacitor. Furthermore, the DC current output by the adjustable constant current circuit is related to the adjustment signal at its adjustment terminal and does not change with the voltage fluctuations across the filter capacitor. Thus, even if the voltage fluctuations across the filter capacitor are large, as long as its average voltage remains constant, the output current of the adjustable constant current circuit remains constant. Therefore, the combination of this signal conversion circuit and the adjustable constant current circuit can further reduce the fluctuations of the DC current output by the adjustable constant current circuit based on the filter capacitor. This results in a DC current with very small fluctuations that meets the low-flicker requirement to drive the LED light-emitting circuit to emit light in a low-flicker manner. This eliminates the need for a large-capacity filter capacitor to meet the low-flicker requirement, achieving high conversion efficiency at a lower cost. Simultaneously, during the switching process, the adjustable constant current circuit has high conversion efficiency, and power consumption is distributed across its various components, thereby reducing the power consumption of its internal semiconductor devices and lowering heat dissipation requirements. Attached Figure Description

[0015] Figure 1 This is a connection diagram of an existing dimmable LED lamp circuit with a lightning removal circuit and a phase-cut dimmer.

[0016] Figure 2 This is a schematic diagram of the switching-type frequency-removing lightning circuit according to Embodiment 1 of the present invention;

[0017] Figure 3 This is a schematic diagram of the switching-type frequency-removing lightning circuit according to Embodiment 2 of the present invention;

[0018] Figure 4 This is a circuit diagram of the switch-type frequency reduction lightning circuit according to Embodiment 3 of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Example 1: As Figure 2As shown, a switching-type frequency reduction circuit includes a filter capacitor C1 for receiving the pulsating DC current output from an adjustable constant current circuit and an adjustable constant current circuit for converting the DC voltage output from the filter capacitor C1 into a DC current to drive an LED light-emitting circuit. The switching-type frequency reduction circuit also includes a signal conversion circuit, which generates a corresponding adjustment signal based on the average value of the voltage signal output from the filter capacitor C1, so as to control the adjustable constant current circuit to convert its input voltage into a corresponding DC current output using a switching conversion method.

[0021] In this embodiment, the filter capacitor C1 has a positive and a negative terminal, the adjustable constant current circuit has a positive terminal, a negative terminal, a positive output terminal, a negative output terminal, and an adjustment terminal, and the signal conversion circuit has an input terminal, an output terminal, and a negative terminal. The positive terminal of the adjustable constant current circuit, the input terminal of the signal conversion circuit, and the positive terminal of the filter capacitor C1 are connected, and their connection terminal is the positive input terminal of the switching-type frequency reduction lightning circuit. The adjustment terminal of the adjustable constant current circuit is connected to the output terminal of the signal conversion circuit. The negative terminal of the adjustable constant current circuit, the negative terminal of the signal conversion circuit, and the negative terminal of the filter capacitor C1 are connected, and their connection terminal is the negative input terminal of the switching-type frequency reduction lightning circuit. The positive output terminal of the adjustable constant current circuit is the positive output terminal of the switching-type frequency reduction lightning circuit, and the negative output terminal of the adjustable constant current circuit is the negative output terminal of the switching-type frequency reduction lightning circuit. A voltage threshold is set at the signal conversion circuit, and the signal conversion circuit converts the voltage signal input to its input terminal into an adjustment signal at its output terminal. At the output terminal, when the average value of the voltage signal connected to the input terminal of the signal conversion circuit is greater than the voltage threshold, the magnitude of the adjustment signal corresponds to the magnitude of the average value of the voltage signal connected to the input terminal of the signal conversion circuit. Furthermore, the larger the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the larger the adjustment signal; the smaller the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the smaller the adjustment signal. When the average value of the voltage signal connected to the input terminal of the signal conversion circuit is less than or equal to the voltage threshold, the adjustment signal is 0. Similarly, the magnitude of the DC current output between the positive and negative output terminals of the adjustable constant current circuit corresponds to the magnitude of the adjustment signal. The larger the adjustment signal, the larger the DC current output between the positive and negative output terminals of the adjustable constant current circuit; conversely, the smaller the adjustment signal, the smaller the DC current output between the positive and negative output terminals of the adjustable constant current circuit.

[0022] In this embodiment, the adjustment signal is an analog voltage signal. The switching-type frequency-de-flash circuit in this embodiment uses an analog voltage signal as its adjustment signal. The adjustment signal output by the signal conversion circuit is an analog voltage signal. The adjustable constant current circuit's adjustment terminal adjusts its output current by connecting to the analog voltage signal. The electrical signal output by the adjustable constant current circuit's signal output terminal is also an analog voltage signal. This electrical signal sets the positive and negative terminals of the linear constant current circuit to enter a conducting or cut-off state, and the current magnitude when in the conducting state.

[0023] When the switching-type frequency-de-flash circuit of this embodiment is applied to a dimmable LED lamp circuit, a pulsating DC current output from an external dimmable constant current circuit is connected between the positive and negative terminals of the filter capacitor C1. This pulsating DC current serves as both the input current of the filter capacitor C1 and the output current of the filter circuit, providing current to the signal conversion circuit and the dimmable constant current circuit. When the pulsating DC current is connected to the filter capacitor C1, a voltage fluctuation is generated between its positive and negative terminals. The signal conversion circuit detects the average value of the voltage signal output between the positive and negative terminals of the filter capacitor C1 and outputs a corresponding adjustment signal. The DC current output between the positive and negative output terminals of the dimmable constant current circuit is thus the output current of the dimmable constant current circuit. The magnitude of the output current of the dimmable constant current circuit corresponds to this adjustment signal. Similarly, the current connected between the positive and negative terminals of the dimmable constant current circuit is proportional to the magnitude of its input and output currents. If the current of the signal conversion circuit is negligible... If the input current of the adjustable constant current circuit is equal to the output current of the filter circuit, then when the input current of the adjustable constant current circuit is less than the average value of the input current of the filter capacitor C1, the voltage between the positive and negative terminals of the filter capacitor C1 will increase. Then, the adjustment signal output by the signal conversion circuit will increase, the output current of the adjustable constant current circuit will increase, and the input current of the adjustable constant current circuit will increase accordingly. Conversely, when the input current of the adjustable constant current circuit is greater than the average value of the input current of the filter capacitor C1, the voltage between the positive and negative terminals of the filter capacitor C1 will decrease. Then, the adjustment signal output by the signal conversion circuit will decrease, the output current of the adjustable constant current circuit will decrease, and its input current will decrease accordingly. Thus, by detecting the average value of the voltage signal between the positive and negative terminals of the filter capacitor C1, the signal conversion circuit changes the magnitude of its output adjustment signal, adjusting the magnitude of the input current of the adjustable constant current circuit to be equal to the magnitude of the input current of the filter circuit, ultimately maintaining the average value of the voltage signal between the positive and negative terminals of the filter capacitor C1 in a stable state.

[0024] Example 2: This example is basically the same as Example 1, except that: Figure 3As shown, in this embodiment, the adjustable constant current circuit also has a signal output terminal. The electrical signal output from the signal output terminal corresponds to the magnitude of the current input between its positive and negative terminals. The switching-type frequency reduction lightning circuit also includes a linear constant current circuit. The linear constant current circuit has a positive terminal, a negative terminal, and a control terminal. The linear constant current circuit has a conduction state and a cutoff state, and is set with a maximum conduction current value and a conduction voltage threshold. The conduction voltage threshold is less than the voltage threshold. The positive terminal of the linear constant current circuit is connected to the positive terminal of the filter capacitor C1, and the negative terminal of the linear constant current circuit is connected to the negative terminal of the filter capacitor C1. The control terminal of the linear constant current circuit is connected to the signal output terminal of the adjustable constant current circuit. When the linear constant current circuit is in the conduction state, the current between its positive and negative terminals is less than or equal to the maximum conduction current value, and the voltage between its positive and negative terminals is greater than or equal to the conduction voltage threshold. The magnitude of the current between the positive and negative terminals of the linear constant current circuit corresponds to the electrical signal input to its control terminal. The electrical signal output from the signal output terminal of the adjustable constant current circuit is used to control the linear constant current circuit to enter the conduction state or the cutoff state.

[0025] When the switching-type frequency reduction lightning circuit of the present invention is required to have the function of dimming to the off state in practical applications, that is, when the current output of the external dimmable constant current circuit connected to the filter capacitor C1 is less than the minimum current value of the output of the adjustable constant current circuit, the output current of the adjustable constant current circuit is required to be zero. At this time, this function is achieved by adding a linear constant current circuit to the switching-type frequency reduction lightning circuit of the present invention. That is, the switching-type frequency reduction lightning circuit of this embodiment has the function of dimming to the off state.

[0026] In this embodiment, in the dimming connection line of the phase-cut dimmer, when the phase-cut dimmer continuously reduces the conduction angle, the magnitude of the pulsating DC current connected to the switch-type frequency-de-flash current in this embodiment is less than the minimum current output between its positive and negative output terminals. When the voltage between the positive and negative terminals of the filter capacitor C1 drops to the voltage threshold of the signal conversion circuit, the adjustment signal output by the signal conversion circuit is zero, the current output between the positive and negative output terminals of the adjustable constant current circuit is zero, and correspondingly, the input current between its positive and negative terminals is 0. The adjustable constant current circuit outputs an electrical signal at its signal output terminal to control the conduction between the positive and negative terminals of the linear constant current circuit. The conduction current of the linear constant current is within the range of less than the maximum conduction current. Thus, the switch-type frequency-de-flash current circuit in this embodiment changes with the magnitude of the pulsating DC current it connects to, so that the voltage between the positive and negative terminals of the filter capacitor C1 is maintained at the conduction voltage threshold of the linear constant current circuit.

[0027] In this embodiment, the switching-type frequency reduction lightning circuit with a linear constant current circuit is used in the phase-cut dimmer circuit. When the conduction angle of the phase-cut dimmer changes from large to small, the output current of the switching-type frequency reduction lightning circuit decreases as the conduction angle of the phase-cut dimmer decreases. When the output current of the switching-type frequency reduction lightning circuit reaches its minimum output current, if the external phase-cut dimmer continues to decrease its conduction angle, the output current of the switching-type frequency reduction lightning circuit becomes 0, and then its internal linear constant current circuit is turned on. When the output current of the switching-type frequency reduction lightning circuit becomes 0, when the conduction angle of the phase-cut dimmer increases, the external adjustable... When the output current of the optical conversion circuit increases to a value greater than the maximum conduction current of the linear constant current circuit in the switching-type frequency-de-flash circuit of this embodiment, the voltage between the positive and negative terminals of the filter capacitor C1 rises. When the voltage between the positive and negative terminals of the filter capacitor C1 is greater than or equal to the voltage threshold of the signal conversion circuit, the adjustment signal output by the signal conversion circuit is not zero, and the output current between the positive and negative output terminals of the adjustable constant current circuit is generated. By adjusting the output current of the adjustable constant current circuit, the signal conversion circuit makes the voltage between the positive and negative terminals of the filter capacitor C1 enter a voltage balance state, so that the output current of the adjustable constant current circuit is constant.

[0028] Example 3: This example is basically the same as Example 2, except that: Figure 4 As shown, in this embodiment, the signal conversion circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a second capacitor C2, a first diode D1, and a first transistor Q1. The first diode D1 is a Zener diode, and the first transistor Q1 is a PNP transistor. One end of the first resistor R1 is connected to one end of the third resistor R3, and their connection point is the input terminal of the signal conversion circuit. The other end of the first resistor R1 is connected to the cathode of the first diode D1. The anode of the first diode D1, one end of the second resistor R2, one end of the second capacitor C2, and the base of the first transistor Q1 are connected. The emitter of the first transistor Q1 is connected to the other end of the third resistor R3, and their connection point is the output terminal of the signal conversion circuit. The other end of the second resistor R2, the other end of the second capacitor C2, and the collector of the first transistor Q1 are connected, and their connection point is the cathode of the signal conversion circuit.

[0029] like Figure 4As shown, in this embodiment, the linear constant current circuit includes a first integrated circuit U1, a fourth resistor R4, a fifth resistor R5, and a second diode D2. The first integrated circuit U1 is model JW1691H, the second diode D2 is a Zener diode, one end of the fourth resistor R4 is the positive terminal of the linear constant current circuit, the other end of the fourth resistor R4 is connected to the negative terminal of the second diode D2, the positive terminal of the second diode D2 is connected to the OUT pin of the first integrated circuit U1, the EXT pin of the first integrated circuit U1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is the control terminal of the linear constant current circuit, and the GND pin of the first integrated circuit U1 is the negative terminal of the linear constant current circuit.

[0030] In this embodiment, the adjustable constant current circuit is an isolated adjustable constant current circuit.

[0031] like Figure 4As shown, in this embodiment, the adjustable constant current circuit includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, an NMOS transistor N1, a first transformer T1, and a second integrated circuit U2. The ninth capacitor C9 is an electrolytic capacitor. The third diode D3, fourth diode D4, fifth diode D5, and sixth diode D6 are all rectifier diodes. The first transformer T1 includes a primary coil Np and a secondary coil... The circuit consists of coil Ns and auxiliary coil Na. The second integrated circuit U2 is model BP3378A. One end of the third capacitor C3, one end of the ninth resistor R9, one end of the tenth resistor R10, one end of the eighth capacitor C8, and one end of the primary coil Np of the first transformer T1 are connected, and their connection ends are the positive terminals of the adjustable constant current circuit. The other end of the primary coil Np of the first transformer T1, the positive terminal of the fourth diode D4, and the drain of the NMOS transistor N1 are connected. The negative terminal of the fourth diode D4, the other end of the tenth resistor R10, and the other end of the eighth capacitor C8 are connected. The gate of the NMOS transistor N1 is connected to pin 5 of the second integrated circuit U2. Pin 3 of the second integrated circuit U2, the source of the NMOS transistor N1, and one end of the eleventh resistor R11 are connected. The connections are as follows: pin 1 of the second integrated circuit U2 is connected to one end of the seventh capacitor C7; one end of the auxiliary coil Na of the first transformer T1, the positive terminal of the third diode D3, and one end of the sixth resistor R6 are connected; the negative terminal of the third diode D3, the other end of the ninth resistor R9, one end of the fourth capacitor C4, and pin 6 of the second integrated circuit U2 are connected; the other end of the sixth resistor R6, one end of the seventh resistor R7, and pin 2 of the second integrated circuit U2 are connected; one end of the fifth capacitor C5 is connected to pin 7 of the second integrated circuit U2, and its connection terminal is the adjustment terminal of the adjustable constant current circuit; the other end of the auxiliary coil Na of the first transformer T1, the other end of the third capacitor C3, the other end of the fourth capacitor C4, the other end of the fifth capacitor C5, and the... One end of capacitor C6 (sixth capacitor), the other end of capacitor C7 (seventh capacitor), the other end of resistor R7 (seventh resistor), one end of resistor R8 (eighth resistor), the other end of resistor R11 (eleventh resistor), the positive terminal of diode D5 (fifth diode), pin 8 of integrated circuit U2, and pin 4 of integrated circuit U2 are connected, and this connection is the signal output terminal of the adjustable constant current circuit. The other end of resistor R8, the other end of capacitor C6, and the negative terminal of diode D5 are connected, and this connection is the negative terminal of the adjustable constant current circuit. One end of the secondary coil Ns of transformer T1 is connected to the positive terminal of diode D6 (sixth diode). The negative terminal of diode D6, the positive terminal of capacitor C9 (ninth capacitor), and one end of resistor R12 are connected, and this connection is the positive output terminal of the adjustable constant current circuit.The other end of the twelfth resistor R12, the negative terminal of the ninth capacitor C9, and the other end of the secondary coil Ns of the first transformer T1 are connected, and this connection point is the negative output terminal of the adjustable constant current circuit.

[0032] In this embodiment, the adjustable constant current circuit adopts an existing isolated constant current converter circuit with an adjustment terminal for connecting analog voltage. By connecting a fifth diode D5 in series with its negative terminal, the control voltage at its adjustment terminal is raised, achieving voltage matching with the adjustment signal output by the signal conversion circuit. Furthermore, the switching-type flicker removal circuit in this embodiment utilizes a common circuit in existing LED lighting technology. By adding a small number of passive components, it achieves the function of switching-type flicker removal with isolated output, offering advantages such as convenient component selection and low cost.

Claims

1. A switching-type frequency reduction circuit, comprising a filter capacitor for receiving a pulsating DC current output from an adjustable constant current circuit, and an adjustable constant current circuit for converting the DC voltage output from the filter capacitor into a DC current to drive an LED light-emitting circuit to emit light, characterized in that... It also includes a signal conversion circuit, which is used to generate a corresponding adjustment signal based on the average value of the voltage signal output by the filter capacitor, so as to control the adjustable constant current circuit to convert the input voltage into a corresponding DC current output by using a switching conversion method. The filter capacitor has a positive and a negative terminal. The adjustable constant current circuit has a positive terminal, a negative terminal, a positive output terminal, a negative output terminal, and an adjustment terminal. The signal conversion circuit has an input terminal, an output terminal, and a negative terminal. The positive terminal of the adjustable constant current circuit, the input terminal of the signal conversion circuit, and the positive terminal of the filter capacitor are connected, and their connection terminal is the positive input terminal of the switching-type frequency-de-lightning circuit. The adjustment terminal of the adjustable constant current circuit is connected to the output terminal of the signal conversion circuit. The negative terminal of the adjustable constant current circuit, the negative terminal of the signal conversion circuit, and the negative terminal of the filter capacitor are connected, and their connection terminal is the negative input terminal of the switching-type frequency-de-lightning circuit. The positive output terminal of the adjustable constant current circuit is the positive output terminal of the switching-type frequency-de-lightning circuit, and the negative output terminal of the adjustable constant current circuit is the negative output terminal of the switching-type frequency-de-lightning circuit. A voltage threshold is set at the signal conversion circuit, and the signal conversion circuit converts the voltage signal input to its input terminal into the adjustment signal at its output. The adjustable constant current circuit outputs a DC current between its positive and negative output terminals. When the average value of the voltage signal connected to the input terminal of the signal conversion circuit is greater than the voltage threshold, the magnitude of the adjustment signal corresponds to the average value of the voltage signal connected to the input terminal of the signal conversion circuit. The larger the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the larger the adjustment signal; the smaller the average value of the voltage signal connected to the input terminal of the signal conversion circuit, the smaller the adjustment signal. When the average value of the voltage signal connected to the input terminal of the signal conversion circuit is less than or equal to the voltage threshold, the adjustment signal is 0. The magnitude of the DC current output between the positive and negative output terminals of the adjustable constant current circuit corresponds to the magnitude of the adjustment signal. The larger the adjustment signal, the larger the DC current output between the positive and negative output terminals of the adjustable constant current circuit; the smaller the adjustment signal, the smaller the DC current output between the positive and negative output terminals of the adjustable constant current circuit.

2. The switching type frequency reduction lightning circuit according to claim 1, characterized in that... The adjustment signal is an analog voltage signal.

3. A switching-type frequency-removing lightning circuit according to claim 1, characterized in that... The adjustable constant current circuit also has a signal output terminal, the electrical signal output from which corresponds to the magnitude of the current input between its positive and negative terminals. The switching-type frequency-de-flash circuit further includes a linear constant current circuit, which has a positive terminal, a negative terminal, and a control terminal. The linear constant current circuit has an on-state and an off-state, and is set with a maximum on-current value and an on-voltage threshold. The on-voltage threshold is less than the voltage threshold. The positive terminal of the linear constant current circuit is connected to the positive terminal of the filter capacitor, and the negative terminal of the linear constant current circuit is connected to the filter capacitor. The negative terminal of the capacitor is connected, and the control terminal of the linear constant current circuit is connected to the signal output terminal of the adjustable constant current circuit. When the linear constant current circuit is in the conducting state, the current between its positive and negative terminals is less than or equal to the maximum conducting current value, and the voltage between its positive and negative terminals is greater than or equal to the conducting voltage threshold. The magnitude of the current between the positive and negative terminals of the linear constant current circuit corresponds to the electrical signal connected to its control terminal. The electrical signal output by the signal output terminal of the adjustable constant current circuit is used to control the linear constant current circuit to enter the conducting or cut-off state.

4. A switching-type frequency-removing lightning circuit according to claim 3, characterized in that... The signal conversion circuit includes a first resistor, a second resistor, a third resistor, a second capacitor, a first diode, and a first transistor. The first diode is a Zener diode, and the first transistor is a PNP transistor. One end of the first resistor and one end of the third resistor are connected, and their connection point is the input terminal of the signal conversion circuit. The other end of the first resistor is connected to the cathode of the first diode. The anode of the first diode, one end of the second resistor, one end of the second capacitor, and the base of the first transistor are connected. The emitter of the first transistor and the other end of the third resistor are connected, and their connection point is the output terminal of the signal conversion circuit. The other end of the second resistor, the other end of the second capacitor, and the collector of the first transistor are connected, and their connection point is the cathode of the signal conversion circuit.

5. A switching-type frequency-removing lightning circuit according to claim 3, characterized in that... The linear constant current circuit includes a first integrated circuit, a fourth resistor, a fifth resistor, and a second diode. The first integrated circuit is a JW1691H, the second diode is a Zener diode, one end of the fourth resistor is the positive terminal of the linear constant current circuit, the other end of the fourth resistor is connected to the negative terminal of the second diode, the positive terminal of the second diode is connected to the OUT pin of the first integrated circuit, the EXT pin of the first integrated circuit is connected to one end of the fifth resistor, the other end of the fifth resistor is the control terminal of the linear constant current circuit, and the GND pin of the first integrated circuit is the negative terminal of the linear constant current circuit.

6. A switching-type frequency reduction lightning circuit according to claim 3, characterized in that... The adjustable constant current circuit is an isolated adjustable constant current circuit.

7. A switching-type frequency-removing lightning circuit according to claim 6, characterized in that... The adjustable constant current circuit includes a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a third diode, a fourth diode, a fifth diode, a sixth diode, an NMOS transistor, a first transformer, and a second integrated circuit. The eighth capacitor is an electrolytic capacitor. The third, fourth, fifth, and sixth diodes are all rectifier diodes. The first transformer includes a primary coil, a secondary coil, and an auxiliary coil. The second integrated circuit is a BP3378A. One end of the third capacitor and one end of the ninth resistor... One end of the tenth resistor, one end of the eighth capacitor, and one end of the primary coil of the first transformer are connected, and their connection ends are the positive terminals of the adjustable constant current circuit. The other end of the primary coil of the first transformer, the anode of the fourth diode, and the drain of the NMOS transistor are connected. The cathode of the fourth diode, the other end of the tenth resistor, and the other end of the eighth capacitor are connected. The gate of the NMOS transistor is connected to pin 5 of the second integrated circuit. Pin 3 of the second integrated circuit, the source of the NMOS transistor, and one end of the eleventh resistor are connected. Pin 1 of the second integrated circuit is connected to one end of the seventh capacitor. The first transformer... One end of the auxiliary coil of the first transformer, the positive terminal of the third diode, and one end of the sixth resistor are connected. The negative terminal of the third diode, the other end of the ninth resistor, one end of the fourth capacitor, and pin 6 of the second integrated circuit are connected. The other end of the sixth resistor, one end of the seventh resistor, and pin 2 of the second integrated circuit are connected. One end of the fifth capacitor is connected to pin 7 of the second integrated circuit, and its connection point is the adjustment terminal of the adjustable constant current circuit. The other end of the auxiliary coil of the first transformer, the other end of the third capacitor, the other end of the fourth capacitor, the other end of the fifth capacitor, one end of the sixth capacitor, and the other end of the seventh capacitor are also connected. The other end of the seventh resistor, one end of the eighth resistor, the other end of the eleventh resistor, the anode of the fifth diode, pin 8 of the second integrated circuit, and pin 4 of the second integrated circuit are connected, and their connection terminals are the signal output terminals of the adjustable constant current circuit. The other end of the eighth resistor, the other end of the sixth capacitor, and the cathode of the fifth diode are connected, and their connection terminals are the cathode of the adjustable constant current circuit. One end of the secondary coil of the first transformer is connected to the anode of the sixth diode. The cathode of the sixth diode, the anode of the ninth capacitor, and one end of the twelfth resistor are connected, and their connection terminals are the positive output terminals of the adjustable constant current circuit.The other end of the twelfth resistor, the negative terminal of the ninth capacitor, and the other end of the secondary coil of the first transformer are connected, and this connection point is the negative output terminal of the adjustable constant current circuit.

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