Leakage protection circuit

Abstract

The invention, which relates to the technical field of the LED, discloses a leakage protection circuit comprising a power supply circuit, a step-down circuit, an LED circuit and a detection circuit. The input end of the power supply circuit is connected to the output pin of the power supply end, the output end of the power supply circuit is connected with the input end of the step-down circuit and the input end of the LED circuit, and the power supply circuit is used for rectifying the output power supply of the power supply end so as to output the power supply to the step-down circuit and the LED circuit; the output end of the step-down circuit is connected with the detection circuit, and the step-down circuit is used for carrying out step-down processing on the power supply output by the power circuit to output reference voltage to the detection circuit; and the detection circuit is respectively connected with the output pins of the power supply end and the LED circuit, and is used for controlling the working state of the LED circuit according to the real-time voltage difference between the output pins of the power supply end and the reference voltage output by the step-down circuit. According to the invention, the working state of the LED circuit can be controlled according to the real-time voltage difference and the reference voltage, so that anti-creeping protection is realized.

Description

Technical Field

[0001] The invention relates to the technical field of LEDs, and in particular to a leakage protection circuit. Background Art

[0002] At present, the lamp can be powered by AC power directly or by a ballast. When AC power is selected, the AC power is generally 220V / 50HZ or other voltages; when a ballast is selected, high voltage electricity exists at the connectors at both ends of the lamp.

[0003] In the field of lighting, lamps are divided into two types: single-ended input and double-ended input. Single-ended input actually sets the AC input connectors at the same end, while double-ended input sets them at both ends of the lamp. Since many lamp holders still retain double-ended access interfaces, double-ended input lamps are generally used when replacing and installing the original lamps.

[0004] During the installation of the lamp tube, the operator usually inserts one end of the lamp tube into the lamp holder first, and then inserts the other end. At this time, partial connection may occur. Since the operator's hand needs to hold the end of the lamp tube, if the human body accidentally touches the conductive metal at the end, electric shock may occur easily, affecting the safety of operation. Therefore, it is particularly important to implement leakage protection for the lamp tube.

[0005] In the prior art, a switch tube is connected to the power input end to detect the current flowing through the switch tube, thereby determining whether there is leakage to achieve leakage protection. However, the prior art is not always effective. When the input end has poor contact, the leakage protection circuit will fail, and the operator is still at risk of electric shock. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a leakage protection circuit which can realize leakage protection.

[0007] In order to solve the above technical problems, the present invention provides a leakage protection circuit, including: a power supply circuit, a step-down circuit, an LED circuit and a detection circuit; the input end of the power supply circuit is connected to the output pin of the power supply end, and the output end of the power supply circuit is respectively connected to the input end of the step-down circuit and the input end of the LED circuit, for rectifying the output power of the power supply end to output power supply to the step-down circuit and the LED circuit; the output end of the step-down circuit is connected to the detection circuit, for step-down the power supply output by the power supply circuit to output a reference voltage to the detection circuit; the detection circuit is respectively connected to the output pin of the power supply end and the LED circuit, for controlling the working state of the LED circuit according to the real-time voltage difference between the output pins of the power supply end and the reference voltage output by the step-down circuit.

[0008] As an improvement of the above scheme, the detection circuit includes two pressure difference detection modules, a control module and a switch module, the control module is provided with two real-time sampling terminals and one reference sampling terminal, and the two groups of output pins of the pressure difference detection module, the real-time sampling terminal and the power supply terminal correspond to each other one by one; the pressure difference detection module is connected to a corresponding group of output pins to detect the real-time pressure difference between the corresponding group of output pins, and control the detection signal output by the pressure difference detection module according to the real-time pressure difference; the real-time sampling terminal is connected to the corresponding pressure difference detection module to obtain the detection signal; the reference sampling terminal is connected to the output terminal of the step-down circuit to obtain the reference voltage; the output terminal of the control module is connected to the switch module, and is used to control the on-off state of the switch module according to the detection signal and the reference voltage.

[0009] As an improvement of the above scheme, the pressure difference detection module includes a rectifier bridge and an optocoupler; the rectifier bridge is connected to a corresponding group of output pins to rectify the output power between the output pins; the input end of the optocoupler is connected to the rectifier bridge, and the output end of the optocoupler is connected to the control module, which is used to control the on-off state of the output end of the optocoupler according to the real-time pressure difference of the output power after rectification by the rectifier bridge.

[0010] As an improvement of the above solution, the switch module includes a first switch, a control end of the first switch is connected to the output end of the control module, an electrode end of the first switch is connected to the LED circuit, and another electrode end of the first switch is connected to the power supply circuit.

[0011] As an improvement of the above scheme, the control module includes a second switch and a third switch; the second switch is respectively connected to a real-time sampling end of the control module and a reference sampling end of the control module, and the second switch is used to adjust its own on-off state according to a detection signal obtained by a real-time sampling end and a reference voltage obtained by a reference sampling end; the third switch is connected to another real-time sampling end of the control module and an output end of the second switch, and is used to adjust its own on-off state according to a detection signal obtained by the other real-time sampling end and an output signal of the second switch; the output end of the third switch is connected to the switch module, and the on-off state of the third switch controls the on-off state of the switch module, and the on-off state of the switch module controls the working state of the LED circuit.

[0012] As an improvement of the above scheme, when the second switch and the third switch are turned on, the switch module is turned on so that the power supply circuit, the LED circuit and the detection circuit form an LED loop, and the LED circuit works; when the second switch and / or the third switch are turned off, the switch module is turned off so that the LED circuit is disconnected from the detection circuit.

[0013] As an improvement of the above scheme, the control electrode of the second switch is connected to the output end of a pressure difference detection module through a real-time sampling end, the first electrode of the second switch is connected to the output end of the step-down circuit through a reference sampling end, and the second electrode of the second switch is connected to the first electrode of the third switch; the control electrode of the third switch is connected to the output end of another pressure difference detection module through another real-time sampling end, and the second electrode of the third switch is connected to the switch module.

[0014] As an improvement of the above solution, the detection circuit further includes an anti-interference module, and the control module and the switch module are connected via the anti-interference module.

[0015] As an improvement of the above-mentioned scheme, the LED circuit includes a driving module and an LED module, and the input end of the driving module is connected to the output end of the LED module, and is used to control the working state of the LED module according to the power supply; when the power supply circuit is connected to the ballast, the driving circuit does not work; when the power supply circuit is connected to the mains, the driving circuit controls the on-off state between the driving module and the LED module according to the power supply to control the working state of the LED circuit.

[0016] As an improvement of the above-mentioned scheme, the driving module includes a driving chip, the driving chip is provided with a detection pin and an open-drain pin, and the open-drain pin is provided with a built-in switch; the detection pin is connected to the power supply circuit and is used to detect the power supply output by the power supply circuit; the open-drain pin is connected to the LED module, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the driving module and the LED module.

[0017] The beneficial effects of implementing the present invention are:

[0018] The leakage protection circuit of the present invention uses the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage difference between the output pins of the power supply end with the reference voltage, and uses the voltage difference factor as the judgment basis to achieve accurate leakage detection from the voltage difference angle, thereby greatly improving the accuracy of detection, thereby effectively controlling the on-off state of the LED circuit, playing a role in preventing leakage, and ensuring human safety;

[0019] Furthermore, the leakage protection circuit of the present invention introduces control elements such as switch tubes and optical couplers to achieve flexible switching of the circuit, thereby more accurately controlling the on and off state of the LED circuit with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the leakage protection circuit of the present invention;

[0021] Figure 21 is a circuit diagram of an embodiment of a leakage protection circuit of the present invention;

[0022] Figure 3 It is a circuit diagram of an embodiment of a voltage reduction circuit in a leakage protection circuit of the present invention;

[0023] Figure 4 It is a circuit diagram of another embodiment of a voltage reduction circuit in a leakage protection circuit of the present invention;

[0024] Figure 5 It is a circuit diagram of an embodiment of a driving module in a leakage protection circuit of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention.

[0026] See also Figure 1 , Figure 1 The specific structure of the leakage protection circuit of the present invention is shown, which includes a power supply circuit 1, a step-down circuit 2, an LED circuit 3 and a detection circuit 4. Specifically:

[0027] The input end of the power supply circuit 1 is connected to the output pin of the power supply end, and the output end of the power supply circuit is connected to the input end of the step-down circuit 2 and the input end of the LED circuit 3 respectively, so as to rectify the output power of the power supply end to output the power supply to the step-down circuit 2 and the LED circuit 3;

[0028] The output end of the step-down circuit 2 is connected to the detection circuit 4, and is used to step down the power supply output by the power supply circuit 1 to output a reference voltage to the detection circuit 4;

[0029] The detection circuit 4 is connected to the output pin of the power supply end and the LED circuit 3 respectively, and is used to control the working state of the LED circuit 3 according to the real-time voltage difference between the output pins of the power supply end and the reference voltage output by the step-down circuit 2, thereby realizing leakage control.

[0030] It should be noted that the leakage protection circuit of the present invention can be applied only to AC power, or to AC power and ballast at the same time, so the power supply end can be a AC power supply end, or it can be a ballast power supply end; at the same time, the leakage protection circuit of the present invention can realize leakage protection of the ballast alone, or it can realize leakage protection of the ballast and AC power at the same time.

[0031] In the prior art, leakage protection circuits usually detect a single electrical signal after rectification to achieve leakage protection. Unlike the prior art, the leakage protection circuit of the present invention uses the electrical signal before rectification (i.e., the electrical signal between the output pins) as the detection target, and uses the voltage difference factor as the judgment basis, to achieve accurate leakage detection from the perspective of voltage difference, greatly improving the accuracy of detection.

[0032] The power supply circuit 1, the step-down circuit 2, the LED circuit 3 and the detection circuit 4 are described in detail below in conjunction with specific embodiments:

[0033] 1. Power supply circuit 1

[0034] like Figure 2 As shown, in this embodiment, the power supply circuit 1 includes a first rectifier bridge BD1, a second rectifier bridge BD2, a second diode D2, a third diode D3, a seventh diode D7, an eighth diode D8, a second capacitor C2, an eighth capacitor C8 and input ports F1, F2, F3 and F4;

[0035] One AC input end of the first rectifier bridge BD1 is connected to the input port F1, the other AC input end is connected to the input port F2, the negative end of the DC output is connected to the step-down circuit 2 and the LED circuit 3, and the positive end of the DC output is grounded; the anode of the second diode D2 is connected to the input port F1, and the cathode is connected to the LED circuit 3; the anode of the third diode D3 is connected to the input port F2, and the cathode is connected to the LED circuit 3; one end of the second capacitor C2 is connected to the input port F1, and the other end is connected to the input port F2;

[0036] Similarly, one AC input end of the second rectifier bridge BD2 is connected to the input port F3, the other AC input end is connected to the input port F4, the DC output negative end is connected to the step-down circuit 2 and the LED circuit 3, and the DC output positive end is grounded; the anode of the seventh diode D7 is connected to the input port F3, and the cathode is connected to the LED circuit 3; the anode of the eighth diode D8 is connected to the input port F4, and the cathode is connected to the LED circuit 3; one end of the eighth capacitor C8 is connected to the input port F3, and the other end is connected to the input port F4.

[0037] When the present invention is applied to a ballast, the input ports F1 , F2 , F3 and F4 can be connected to four pins of the ballast.

[0038] When the present invention is applied to AC power, any two input ports can be selected to connect two pins of the AC power, for example, input ports F1 and F2, or input ports F3 and F4, or input ports F1 and F3, or input ports F1 and F4, or input ports F2 and F3, or input ports F2 and F4.

[0039] Therefore, the power supply circuit 1 can rectify the output power of the power supply end to output a stable power supply to the step-down circuit 2 and the LED circuit 3 .

[0040] 2. Buck circuit 2

[0041] like Figure 2 As shown, in this embodiment, the step-down circuit 2 includes a voltage-dividing resistor group (a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5), a first capacitor C1 and a first voltage-stabilizing diode D1; wherein, one end of the first resistor R1 is connected to the power supply circuit 1, and the other end is grounded through the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5 in sequence, the fifth resistor R5 is connected in parallel with the first capacitor C1 and the first voltage-stabilizing diode D1, the positive electrode of the first voltage-stabilizing diode D1 is grounded, and the negative electrode is connected to the detection circuit 4.

[0042] Therefore, the power supply output by the power supply circuit 1 can be stepped down by the step-down circuit 2 and converted into a reference voltage of 12V for use by the detection circuit 4 .

[0043] In other embodiments, resistors of different numbers and resistance values ​​may be selected for voltage reduction according to actual needs.

[0044] like Figure 3 As shown, in this embodiment, the voltage-dividing resistor group includes four resistors (a second resistor R2, a third resistor R3, a fourth resistor R4 and a fifth resistor R5) connected in series.

[0045] In other embodiments, the voltage may be reduced by using a voltage-reducing chip.

[0046] like Figure 4As shown, in this embodiment, the buck circuit 2 includes a buck chip U2, an eleventh diode D11, a twelfth diode D12, a third inductor L3, a fourth inductor L4, a sixteenth capacitor C16, a seventeenth capacitor C17, a second polarity capacitor CE2, a third polarity capacitor CE3, a fourth polarity capacitor CE4, a fortieth resistor R40, a forty-first resistor R41 and a current limiting resistor RS1, wherein: the ground pin GND of the buck chip U2 is connected to the cathode of the twelfth diode D12, the clock pin SCL and the power supply pin VCC are respectively connected to the cathode of the eleventh diode D11, and the open drain pin DRAI is N is connected to the power supply circuit 1 through the third inductor L3, and the chip select pin CS is connected to the cathode of the twelfth diode D12 through the current limiting resistor RS1; the anode of the twelfth diode D12 is grounded, and the cathode is connected to the detection circuit 4 through the fourth inductor L4 and connected to the cathode of the eleventh diode D11 through the seventeenth capacitor C17, and the anode of the eleventh diode D11 is connected to the detection circuit 4; one end of the fortieth resistor R40 is connected to the detection circuit 4, and the other end is grounded, the fortieth resistor R40, the sixteenth capacitor C16 and the second polarity capacitor CE2 are connected in parallel with each other; the forty-first resistor R41 is connected in parallel with the third inductor L3; the positive electrode of the fourth polarity capacitor CE4 is connected to the open-drain pin DRAIN, and the negative electrode is grounded; the positive electrode of the third polarity capacitor CE3 is connected to the power supply circuit 1, and the negative electrode is grounded.

[0047] It should be noted that when connected to the AC power, no matter it is single-ended access to the input ports F1 and F2, or single-ended access to the input ports F3 and F4, or double-ended input, the voltage after rectification by the first rectifier bridge DB1 and the second rectifier bridge DB2 is 310VDC, which meets the working state of the buck chip U2; therefore, the buck chip U2 can work normally, play the role of step-down constant current, and supply a constant reference voltage to the detection circuit 4.

[0048] Therefore, in applications, different step-down circuits 2 may be used to step down the power output by the power supply circuit 1 according to actual needs, and no limitation is made here.

[0049] 3. LED circuit 3

[0050] (1) When the leakage protection circuit of the present invention is only applied to a ballast, the LED circuit 3 may not be provided with a driving module.

[0051] (2) When the leakage protection circuit of the present invention is applied to both the mains and the ballast, the LED circuit 3 includes a driving module 32 and an LED module 31 , and the input end of the driving module 32 is connected to the output end of the LED module 31 .

[0052] in:

[0053] (2.1) When the power circuit 1 is connected to the ballast, the driving module 32 does not work;

[0054] (2.2) When the power supply circuit 1 is connected to the mains and the driving module 32 has a leakage protection function, the driving module 32 controls the on / off state between the driving module 32 and the LED module 31 according to the power supply output by the power supply circuit 1 to control the working state of the LED circuit 31;

[0055] For example, when the driving module 32 does not detect leakage, the driving module 32 is connected to the LED module 31, and the driving module 32 drives the LED module 31, thereby ensuring constant current power supply to the LED module 31;

[0056] For another example, when the driving module 32 detects a leakage, the driving module 32 is disconnected from the LED module 31 , and the LED module 31 is short-circuited.

[0057] In some embodiments, the LED module 31 includes a plurality of light-emitting diodes connected in series. The driving module 32 includes a driving chip U1, on which a detection pin REC and an open-drain pin DRAIN are provided, and a built-in switch is provided in the open-drain pin DRAIN; the detection pin REC is connected to the power circuit 1 and is used to detect the power supply output by the power circuit 1. The open-drain pin DRAIN is connected to the LED module 31, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the driving module 32 and the LED module 31.

[0058] like Figure 2As shown, in this embodiment, the driving module 32 includes a driving chip U1, a first transformer coil T1, a sixth diode D6, a voltage stabilizing diode TVS1, a first polarity capacitor CE1, a seventh capacitor C7, a ninth capacitor C9, a tenth capacitor C10, an eighth resistor R8, a ninth resistor R9, an eleventh resistor R11, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a seventeenth resistor R17 and an eighteenth resistor R18, wherein: an open-drain pin DRAIN of the driving chip U1 is connected to the cathode of the LED module 31 through the first transformer coil T1; the compiling pin IS is grounded through the seventeenth resistor R17 and the eighteenth resistor R18 respectively; the grounding pin GND is grounded and connected to the anode of the sixth diode D6 through the ninth capacitor C9, and the cathode of the sixth diode D6 is connected to the anode of the LED module 31; the detection pin REC is connected to the power supply circuit 1 through the fourteenth resistor R14 and the thirteenth resistor R13 in sequence, and is grounded through the voltage stabilizing diode TVS1 and the fifteenth resistor R15 respectively; the power pin VI N is connected to the positive electrode of the LED module through the eighth resistor R8; one end of the tenth capacitor C10 is grounded, and the other end is respectively connected to the detection circuit 4 and the negative electrode of the LED module 31; one end of the ninth resistor R9 is connected to the positive electrode of the LED module 31, and the other end is connected to the open-drain pin DRAI N through the seventh capacitor C7; one end of the first polarity capacitor CE1 is connected to the positive electrode of the LED module 31, and the other end is connected to the negative electrode of the LED module 31, and the eleventh resistor R11 is connected in parallel with the first polarity capacitor CE1;

[0059] It should be noted that the detection pin REC of the driver chip U1 has an input current detection function; when the power supply is greater than 72MA, the driver chip U1 turns on the built-in switch of the open-drain pin DRAIN; when the power supply is less than 72MA, the driver chip U1 turns off the built-in switch of the open-drain pin DRAIN. Preferably, the driver chip U1 can be JW1830, JW1831, JW1832 or other similar solutions, but is not limited thereto.

[0060] Furthermore, in this embodiment, the LED circuit 3 further includes a filter circuit 33 , an input end of the filter circuit 33 is connected to an output end of the power circuit 1 , and an output end of the filter circuit 33 is connected to the driving module 32 and the LED module 31 , respectively.

[0061] like Figure 2As described, in this embodiment, the filter circuit 33 includes a first inductor L1, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a seventh resistor R7 and a thermistor RV1; wherein, the power supply pin VCC of the driver chip U1 is grounded through the fifth capacitor C5; one end of the thermistor RV1 is connected to the positive electrode of the LED module 31, and the other end is grounded; one end of the third capacitor C3 is connected to the power supply circuit 1, and the other end is grounded; one end of the fourth capacitor C4 is connected to the positive electrode of the LED module, and the other end is grounded; one end of the first inductor L1 is connected to the power supply circuit 1, and the other end is connected to the positive electrode of the LED module, and the seventh resistor R7 is connected in parallel with the first inductor L1.

[0062] Therefore, the filter circuit 33 can filter the supply voltage output by the power supply circuit 1 to provide power to the driving module 32 and the LED module 31 .

[0063] (2.3) When the power supply circuit 1 is connected to the mains and the driving module 32 does not have a leakage protection function, the driving module 32 works to drive the LED module 31, thereby ensuring a constant current power supply to the LED circuit 3;

[0064] like Figure 5 As shown, in this embodiment, the driving module 32 includes a driving chip U1, a second inductor L2, a thirteenth diode D13, a tenth capacitor C10, an eighteenth polarity capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, an eighth resistor R8, a seventeenth resistor R17, an eighteenth resistor R18 and a forty-first resistor R41. Wherein: the overvoltage protection pin OVP of the driver chip U1 is grounded through the forty-first resistor R41; the power input pin VI N is connected to the positive electrode of the LED module 31 through the eighth resistor R8; the open-drain pin DRAI N is connected to the positive electrode of the LED module 31 through the thirteenth diode D13, and is connected to the negative electrode of the LED module 31 through the second inductor L2; the compilation pin IS P is grounded through the seventeenth resistor R17 and the eighteenth resistor R18 respectively; one end of the twentieth capacitor C20 is connected to the positive electrode of the LED module 31, and the other end is grounded; the positive electrode of the eighteenth polarity capacitor C18 is connected to the positive electrode of the LED module 31, the negative electrode of the eighteenth polarity capacitor C18 is connected to the detection circuit 4 and the negative electrode of the LED module 31, and is grounded through the tenth capacitor C10, and the eighteenth polarity capacitor C18 is connected in parallel with the nineteenth capacitor C19;

[0065] Therefore, when the mains is connected, the LED module 31 can be driven by the driver chip U1 at a constant current to ensure that the LED module 31 can be used normally.

[0066] 4. Detection circuit 4

[0067] like Figure 2As shown, the detection circuit 4 includes two pressure difference detection modules 41, a control module 42 and a switch module 43. The control module 42 is provided with two real-time sampling terminals and one reference sampling terminal. The two groups of output pins of the pressure difference detection module 41, the real-time sampling terminal and the power supply terminal correspond to each other.

[0068] The pressure difference detection module 41 is connected to a corresponding group of output pins to detect the real-time pressure difference between the corresponding group of output pins, and controls the detection signal output by the pressure difference detection module 41 according to the real-time pressure difference;

[0069] The real-time sampling end is connected to the corresponding pressure difference detection module 41 to obtain a detection signal;

[0070] The reference sampling terminal is connected to the output terminal of the step-down circuit 2 to obtain a reference voltage;

[0071] The output end of the control module 42 is connected to the switch module 43 and is used to control the on / off state of the switch module 43 according to the detection signal and the reference voltage.

[0072] Therefore, through the cooperation among the voltage difference detection module 41, the control module 42 and the switch module 43, the switch module 43 can be accurately switched on and off according to the real-time voltage difference between the output pins and the reference voltage of the step-down circuit 2, with high precision.

[0073] The pressure difference detection module 41, the control module 42 and the switch module 43 are described in detail below:

[0074] (1) Pressure difference detection module

[0075] The pressure difference detection module 41 includes a rectifier bridge and an optocoupler; the rectifier bridge is connected to a corresponding set of output pins to rectify the output power between the output pins; the input end of the optocoupler is connected to the rectifier bridge, and the output end of the optocoupler is connected to the control module 42, which is used to control the on-off state of the output end of the optocoupler according to the real-time pressure difference of the output power after rectification by the rectifier bridge.

[0076] like Figure 2 As shown, in this embodiment, the voltage difference detection module 41 includes a third rectifier bridge BD3, a fourth rectifier bridge BD4, a tenth resistor R10, a twelfth resistor R12, a twenty-first resistor R21, a twenty-second resistor R22, a sixth capacitor C6, a twelfth capacitor C12, a first optical coupler U3 and a second optical coupler U4. Wherein:

[0077] One AC input end of the third rectifier bridge BD3 is connected to the input port F1, and the other AC input end is connected to the input port F2; one end of the sixth capacitor C6 is connected to the negative DC output end of the third rectifier bridge BD3, and the other end is connected to the positive DC output end of the third rectifier bridge BD3; the twelfth resistor R12 is connected in parallel with the sixth capacitor C6; the positive electrode of the transmitting tube of the first optical coupler U3 is connected to the negative DC output end of the third rectifier bridge BD3 through the tenth resistor R10, the negative electrode of the transmitting tube is connected to the positive DC output end of the third rectifier bridge BD3, the collector is connected to a real-time sampling end of the control module 42, and the emitter is grounded;

[0078] Similarly, one AC input end of the fourth rectifier bridge BD4 is connected to the input port F3, and the other AC input end is connected to the input port F4; one end of the twelfth capacitor C12 is connected to the negative DC output end of the fourth rectifier bridge BD4, and the other end is connected to the positive DC output end of the fourth rectifier bridge BD4; the twenty-second resistor R22 is connected in parallel with the twelfth capacitor C12; the positive electrode of the transmitting tube of the second optocoupler U4 is connected to the negative DC output end of the fourth rectifier bridge BD4 through the twenty-first resistor R21, the negative electrode of the transmitting tube is connected to the positive DC output end of the fourth rectifier bridge BD4, the collector is connected to the other real-time sampling end of the real-time sampling end, and the emitter is grounded.

[0079] Therefore, the pressure difference detection module 41 can effectively detect the real-time pressure difference between the output pins through the mutual cooperation between various components, so as to flexibly control the on-off state of the optocoupler, thereby outputting different detection signals to the control module 42.

[0080] (2) Control module

[0081] In some embodiments, the control module 42 includes a second switch Q2 and a third switch Q3; the second switch Q2 is respectively connected to a real-time sampling end of the control module 42 and a reference sampling end of the control module 42, and the second switch Q2 is used to adjust its own on-off state according to a detection signal obtained by a real-time sampling end and a reference voltage obtained by the reference sampling end; the third switch Q3 is connected to another real-time sampling end of the control module 41 and an output end of the second switch Q2, and is used to adjust its own on-off state according to a detection signal obtained by another real-time sampling end and an output signal of the second switch Q2; the output end of the third switch Q3 is connected to the switch module 43, the on-off state of the third switch Q3 controls the on-off state of the switch module 43, and the on-off state of the switch module 43 controls the working state of the LED circuit 3.

[0082] Further, the control electrode of the second switch Q2 is connected to the output end of a pressure difference detection module 41 through a real-time sampling end, the first electrode of the second switch Q2 is connected to the output end of the step-down circuit 2 through the reference sampling end, and the second electrode of the second switch Q2 is connected to the first electrode of the third switch Q3; the control electrode of the third switch Q3 is connected to the output end of another pressure difference detection module 41 through another real-time sampling end, and the second electrode of the third switch Q3 is connected to the switch module 43.

[0083] like Figure 2 As shown, in this embodiment, the control module 42 includes a second switch Q2, a third switch Q3, a 44th resistor R44 and a 45th resistor R45, wherein: the source of the second switch Q2 is connected to the step-down circuit 2, the gate of the second switch Q2 is connected to a voltage difference detection module 41, the drain of the second switch Q2 is connected to the source of the third switch Q3, the gate of the third switch Q3 is connected to another voltage difference detection module 41, and the drain of the third switch Q3 is connected to the switch module 43; one end of the 44th resistor R44 is connected to the step-down circuit 2, and the other end is connected to the gate of the third switch Q3; one end of the 45th resistor R45 is connected to the step-down circuit 2, and the other end is connected to the gate of the second switch Q2.

[0084] Therefore, when the second switch Q2 and the third switch Q3 are turned on, the switch module 43 is turned on, so that the power supply circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works; when the second switch Q2 and / or the third switch Q3 are turned off, the switch module 43 is turned off, so that the LED circuit 1 and the detection circuit 4 are disconnected.

[0085] (3) Switch module

[0086] like Figure 2 As shown, in this embodiment, the switch module 43 includes a first switch Q1, a control end of the first switch Q1 is connected to the output end of the control module 4, an electrode end of the first switch Q1 is connected to the LED circuit 3, and the other electrode end of the first switch Q1 is connected to the power supply circuit 1.

[0087] Therefore, when the first switch Q1 is turned on, the power circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works; when the first switch Q1 is turned off, the LED circuit 3 and the detection circuit 4 are disconnected.

[0088] Furthermore, the detection circuit 4 further includes an anti-interference module 44 , and the control module 42 and the switch module 43 are connected via the anti-interference module 44 .

[0089] like Figure 2As shown, in this embodiment, the anti-interference module 44 includes a 30th resistor R30, a 32nd resistor R32 and an RC circuit (a 33rd resistor R33 and a 13th capacitor C13 connected in parallel with each other); the 30th resistor R30 is connected in series between the control module 42 and the switch module 43; one end of the 32nd resistor R32 is connected to the switch module 43, and the other end is connected to the power supply circuit (i.e., grounded); one end of the RC circuit is connected to the control module 42, and the other end is connected to the power supply circuit (i.e., grounded).

[0090] Therefore, the anti-interference module 44 can be used to isolate the control module 42 from the switch module 43 , thereby avoiding interference to the switch module 43 and improving the accuracy of the switch module 43 .

[0091] The following further describes Figure 2 The leakage detection principle of the embodiment shown:

[0092] 1. Connect the ballast

[0093] When the ballast is connected, there is a real-time voltage difference between the input ports F1 and F2. After the real-time voltage difference is rectified by the third rectifier bridge BD3, the current passes through the tenth resistor R10 to turn on the first optical coupler U3. At this time, the voltage of the collector C of the first optical coupler U3 is pulled to the ground by the transistor, and the second switch Q2 is turned on.

[0094] Similarly, there is a real-time voltage difference between the input ports F3 and F4. After the real-time voltage difference is rectified by the fourth rectifier bridge BD4, the current passes through the twenty-first resistor R21 to turn on the second optocoupler U4. At this time, the voltage of the collector E of the second optocoupler U4 is pulled to the ground by the transistor, and the third switch Q3 is turned on.

[0095] The voltage enters the control electrode of the first switch Q1 through the second switch Q2 and the third switch Q3. At this time, the first switch Q1 is turned on, so that the output power of the power supply circuit 1 flows from the negative DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the first inductor L1, the LED module 31, and the first switch Q1 in sequence, and finally returns to the positive DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED loop, thereby lighting the LED module 31. At this time, the cathode of the LED module 31 is pulled to the ground by the first switch Q1, and the open drain pin DRAIN of the driver chip U1 is equivalent to grounding. At this time, the driver chip U1 does not meet the working conditions and does not participate in the work.

[0096] When one end of the lamp tube falls off, there is no voltage difference between the input ports F1 and F2, or F3 and F4, and the second switch Q2 or the third switch Q3 is not conducting. Since one of them is not conducting, the control electrode of the first switch Q1 has no voltage and current, and the first switch Q1 is in the off state, so that the LED circuit is cut off, making it safe for the installer to touch the other end, which plays a role in preventing leakage.

[0097] 2. Connect to the mains

[0098] When connected to the mains, the single-end or double-end of the power circuit 1 can work normally. When the input ports F1 and F2, or F3 and F4 input the mains, the input voltage is subject to the actual solution, which can be wide voltage, narrow voltage, single voltage, etc. The following uses 220V / 50HZ to explain the working principle:

[0099] When connected to the mains, the voltage input path is input ports F1 and F2, or input ports F3 and F4, or a combination of input ports F1, F2 and F3, F4 (for example, input from F1 and F3, or F1 and F4, or F2 and F3, or F2 and F4); but no matter which method is used, it is input from two pins, and at this time the second switch Q2 or the third switch Q3 is not conducting; because one of them is not conducting, at this time the control electrode of the first switch Q1 has no voltage and current, and the first switch Q1 is in a turned-off state, so that the first switch Q1 does not work and does not affect the operation of the driver chip U1, so that the output power of the power supply circuit 1 flows from the DC output negative end of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the first inductor L1, the LED module 31, the open-drain pin DRAIN, the driver chip U1 and the compile pin ISp in sequence, and finally returns to the DC output positive end of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED loop, so that the LED module 31 is normally lit.

[0100] At this time, when one of the input pins is disconnected and contacts a person, since the internal resistance of the person is greater than 500Ω, it is equivalent to connecting a resistor to the detection pin REC of the driver chip U1. At this time, the current of the detection pin REC will decrease, causing the previous state greater than 72MA to change to less than 72MA. At this time, the built-in switch of the open-drain pin DRAIN is closed, so that the LED circuit is cut off, which plays a role in leakage protection.

[0101] To sum up, the leakage protection circuit of the present invention takes the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage difference between the output pins of the power supply end with the reference voltage, and takes the voltage difference factor as the judgment basis, thereby realizing accurate detection of leakage from the perspective of voltage difference, greatly improving the accuracy of detection, thereby effectively controlling the on-off state of the LED circuit, playing a role in preventing leakage, and ensuring human safety; further, the leakage protection circuit of the present invention introduces control elements such as switching tubes and optocouplers, realizing flexible switching of the circuit, thereby more accurately controlling the on-off state of the LED circuit with high accuracy.

[0102] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A leakage protection circuit, characterized in that: Including power supply circuit, step-down circuit, LED circuit and detection circuit; The input end of the power supply circuit is connected to the output pin of the power supply end, and the output end of the power supply circuit is respectively connected to the input end of the step-down circuit and the input end of the LED circuit, so as to rectify the output power of the power supply end to output the power supply to the step-down circuit and the LED circuit; The output end of the step-down circuit is connected to the detection circuit, and is used to step down the power supply output by the power supply circuit to output a reference voltage to the detection circuit; The detection circuit is connected to the output pin of the power supply end and the LED circuit respectively, and is used to control the working state of the LED circuit according to the real-time voltage difference between the output pins of the power supply end and the reference voltage output by the step-down circuit.

2. The leakage protection circuit as claimed in claim 1, characterized in that: The detection circuit includes two pressure difference detection modules, a control module and a switch module. The control module is provided with two real-time sampling terminals and one reference sampling terminal. The pressure difference detection module, the real-time sampling terminal and the two groups of output pins of the power supply terminal correspond to each other. The pressure difference detection module is connected to a corresponding group of output pins to detect the real-time pressure difference between the corresponding group of output pins, and controls the detection signal output by the pressure difference detection module according to the real-time pressure difference; The real-time sampling end is connected to the corresponding pressure difference detection module to obtain the detection signal; The reference sampling terminal is connected to the output terminal of the step-down circuit to obtain a reference voltage; The output end of the control module is connected to the switch module, and is used to control the on-off state of the switch module according to the detection signal and the reference voltage.

3. The leakage protection circuit according to claim 2, characterized in that: The pressure difference detection module includes a rectifier bridge and an optical coupler; The rectifier bridge is connected to a corresponding group of output pins to rectify the output power between the output pins; The input end of the optocoupler is connected to the rectifier bridge, and the output end of the optocoupler is connected to the control module, which is used to control the on-off state of the output end of the optocoupler according to the real-time voltage difference of the output power after rectification by the rectifier bridge.

4. The leakage protection circuit as claimed in claim 2, characterized in that: The switch module includes a first switch, a control end of the first switch is connected to the output end of the control module, an electrode end of the first switch is connected to the LED circuit, and another electrode end of the first switch is connected to the power circuit.

5. The leakage protection circuit according to claim 2, characterized in that: The control module includes a second switch and a third switch; The second switch is connected to a real-time sampling terminal of the control module and a reference sampling terminal of the control module respectively, and the second switch is used to adjust its on-off state according to a detection signal obtained by a real-time sampling terminal and a reference voltage obtained by the reference sampling terminal; The third switch is connected to another real-time sampling terminal of the control module and the output terminal of the second switch, and is used to adjust its on-off state according to the detection signal obtained by the other real-time sampling terminal and the output signal of the second switch; The output end of the third switch is connected to the switch module, the on-off state of the third switch controls the on-off state of the switch module, and the on-off state of the switch module controls the working state of the LED circuit.

6. The leakage protection circuit according to claim 5, characterized in that: When the second switch and the third switch are turned on, the switch module is turned on, so that the power circuit, the LED circuit and the detection circuit form an LED loop, and the LED circuit works; When the second switch and / or the third switch is turned off, the switch module is turned off to disconnect the LED circuit from the detection circuit.

7. The ballast leakage protection circuit compatible with mains power as claimed in claim 5, characterized in that: The control electrode of the second switch is connected to the output end of a voltage difference detection module through a real-time sampling end, the first electrode of the second switch is connected to the output end of the step-down circuit through a reference sampling end, and the second electrode of the second switch is connected to the first electrode of the third switch; The control electrode of the third switch is connected to the output end of another pressure difference detection module through another real-time sampling end, and the second electrode of the third switch is connected to the switch module.

8. The ballast-based leakage protection circuit as claimed in claim 2, characterized in that: The detection circuit further includes an anti-interference module, and the control module and the switch module are connected via the anti-interference module.

9. The leakage protection circuit according to claim 1, characterized in that: The LED circuit comprises a driving module and an LED module, wherein an input end of the driving module is connected to an output end of the LED module and is used to control a working state of the LED module according to the power supply; When the power supply circuit is connected to the ballast, the drive circuit does not work; When the power supply circuit is connected to the mains, the driving circuit controls the on-off state between the driving module and the LED module according to the power supply to control the working state of the LED circuit.

10. The leakage protection circuit according to claim 9, characterized in that: The driving module comprises a driving chip, the driving chip is provided with a detection pin and an open-drain pin, and the open-drain pin is provided with a built-in switch; The detection pin is connected to the power circuit and is used to detect the power supply output by the power circuit; The open-drain pin is connected to the LED module, and the built-in switch switches the on-off state according to the power supply to control the on-off state between the driving module and the LED module.

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