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 and the real-time voltage 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, the real-time voltage 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 with high accuracy.

[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, the real-time voltage 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, two bandpass filtering modules, a comparison module and a switch module, the comparison module is provided with two real-time sampling units and two reference sampling units, the pressure difference detection module, the bandpass filtering module, the real-time sampling unit, the reference sampling unit and the two groups of output pins of the power supply end 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 control the on-off state of the pressure difference detection module according to the real-time pressure difference; the bandpass filtering module is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins; the real-time sampling unit is connected to the corresponding pressure difference detection module and the bandpass filtering module respectively, and is used to detect the real-time voltage between the corresponding group of output pins through the bandpass filtering module and adjust the real-time voltage according to the on-off state of the pressure difference detection module; the reference sampling unit is connected to the output end of the step-down circuit to obtain the reference voltage; the output end of the comparison module is connected to the switch module, and is used to control the on-off state of the switch module according to the adjusted real-time voltage 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 comparison 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 bandpass filtering module includes two diodes connected in anti-phase series, and the real-time sampling unit of the comparison module is connected between the two diodes.

[0011] 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 comparison 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.

[0012] As an improvement of the above scheme, the comparison module includes a first comparator, a second comparator, a second switch and a third switch; an input end of the first comparator is connected to a real-time sampling unit of the comparison module, and the other input end of the first comparator is connected to a reference sampling unit of the comparison module, and the first comparator is used to control the on-off state of the second switch according to the adjusted real-time voltage detected by a real-time sampling unit and the reference voltage obtained by a reference sampling unit; an input end of the second comparator is connected to another real-time sampling unit of the comparison module, and the other input end of the second comparator is connected to another reference sampling unit of the comparison module, and the second comparator is used to control the on-off state of the third switch according to the adjusted real-time voltage detected by another real-time sampling unit and the reference voltage obtained by another reference sampling unit; the second switch, the third switch and the switch module are connected in sequence, and the on-off state of the second switch and 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.

[0013] As an improvement of the above scheme, the real-time sampling unit includes a reference resistor group, a first voltage-dividing resistor group and a second voltage-dividing resistor group connected in series in sequence; a photoelectric pin of the pressure difference detection module is connected to the connection between the reference resistor group and the first voltage-dividing resistor group, another photoelectric pin of the pressure difference detection module is connected to the connection between the first voltage-dividing resistor group and the second voltage-dividing resistor group, and the sampling point of the bandpass filtering module is connected to the input end of the reference resistor group.

[0014] 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.

[0015] As an improvement of the above-mentioned scheme, the LED circuit includes a driving module and an LED module, 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 module does not work; when the power supply circuit is connected to the mains, the driving module 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 takes the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage difference, real-time voltage and reference voltage between the output pins of the power supply end. While considering the voltage factor, the voltage difference factor is also used as the judgment basis, and accurate leakage detection is achieved from multiple angles, which greatly improves the accuracy of detection, thereby effectively controlling the on-off state of the LED circuit, playing a role in preventing leakage, and ensuring the safety of people.

[0019] Furthermore, the leakage protection circuit of the present invention introduces control elements such as comparators, switch tubes, and optocouplers to achieve layer-by-layer comparison of electrical signals and flexible switching of circuits, 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 2 1 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;

[0025] Figure 6 is another structural schematic diagram of the leakage protection circuit of the present invention;

[0026] Figure 7 yes Figure 2 Enlarged view of the comparison module. DETAILED DESCRIPTION

[0027] 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.

[0028] 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:

[0029] 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 1 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;

[0030] 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;

[0031] 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, the real-time voltage and the reference voltage output by the step-down circuit 2, thereby realizing leakage control.

[0032] It should be noted that the leakage protection circuit of the present invention can be applied only to the ballast, and can also be applied to the AC power and the ballast at the same time, so the power supply end can be the AC power supply end, and can also be the ballast power supply end; at the same time, the leakage protection circuit of the present invention can realize the leakage protection of the ballast alone, and can also realize the leakage protection of the ballast and the AC power at the same time.

[0033] 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 combines the real-time voltage difference, real-time voltage and reference voltage between the output pins of the power supply end. While considering the voltage factor, the voltage difference factor is also used as the judgment basis, achieving accurate leakage detection from multiple angles, greatly improving the accuracy of detection.

[0034] 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:

[0035] 1. Power supply circuit 1

[0036] like Figure 2As 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;

[0037] 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;

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 .

[0042] 2. Buck circuit 2

[0043] like Figure 2As 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.

[0044] 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 5V for use by the detection circuit 4 .

[0045] In other embodiments, resistors of different numbers and resistance values ​​may be selected for voltage reduction according to actual needs.

[0046] 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.

[0047] In other embodiments, the voltage may be reduced by using a voltage-reducing chip.

[0048] like Figure 4 As 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:

[0049] 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, the open drain pin DRAIN 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;

[0050] The anode of the twelfth diode D12 is grounded, the cathode is connected to the detection circuit 4 via the fourth inductor L4 and connected to the cathode of the eleventh diode D11 via the seventeenth capacitor C17, and the anode of the eleventh diode D11 is connected to the detection circuit 4;

[0051] One end of the 40th resistor R40 is connected to the detection circuit 4, and the other end is grounded. The 40th resistor R40, the 16th capacitor C16 and the second polarity capacitor CE2 are connected in parallel with each other.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 3. LED circuit 3

[0056] (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.

[0057] (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 .

[0058] in:

[0059] (2.1) When the power circuit 1 is connected to the ballast, the driving module 32 does not work;

[0060] (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;

[0061] 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;

[0062] 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.

[0063] 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.

[0064] like Figure 2 As 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;

[0065] 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.

[0066] 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.

[0067] like Figure 2 As 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.

[0068] 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 .

[0069] (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;

[0070] 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;

[0071] 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.

[0072] 4. Detection circuit 4

[0073] like Figure 2 and Figure 6 As shown, the detection circuit 4 includes two pressure difference detection modules 41, two band-pass filter modules 42, a comparison module 43 and a switch module 44; wherein the comparison module 43 is provided with two real-time sampling units 431 and two reference sampling units 432, and the pressure difference detection module 41, the band-pass filter module 42, the real-time sampling unit 431, the reference sampling unit 432 and the two groups of output pins of the power supply end correspond to each other;

[0074] 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 on-off state of the pressure difference detection module 41 according to the real-time pressure difference;

[0075] The bandpass filter module 42 is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins;

[0076] The real-time sampling unit 431 is connected to the corresponding pressure difference detection module 41 and the band-pass filter module 42, respectively, and is used to detect the real-time voltage between a corresponding group of output pins through the band-pass filter module 42 and adjust the real-time voltage according to the on-off state of the pressure difference detection module;

[0077] The reference sampling unit 432 is connected to the output end of the voltage-reducing circuit 2 to obtain a reference voltage;

[0078] The output end of the comparison module 43 is connected to the switch module 44 , and the comparison module 43 is used to control the on-off state of the switch module 44 according to the adjusted real-time voltage and the reference voltage.

[0079] Therefore, through the mutual cooperation among the pressure difference detection module 41, the bandpass filtering module 42, the real-time sampling unit 431, the reference sampling unit 432, and the comparison module 43, the switch module 44 can be accurately switched on and off according to the real-time pressure difference between the output pins, the real-time voltage and the reference voltage of the buck circuit 2, with high precision.

[0080] The pressure difference detection module 41, the bandpass filter module 42, the comparison module 43 and the switch module 44 are described in detail below:

[0081] (1) Pressure difference detection module

[0082] 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 comparison module 43, 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.

[0083] 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:

[0084] 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, and the output end is connected to a real-time sampling unit 431 of the comparison module 43;

[0085] 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, and the output end is connected to another real-time sampling unit 431 of the comparison module 43.

[0086] 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, thereby flexibly controlling the on-off state of the optocoupler.

[0087] (2) Bandpass filter module

[0088] The bandpass filter module 42 includes two diodes connected in series in an anti-phase manner, and the real-time sampling unit 431 of the comparison module 43 is connected between the two diodes.

[0089] like Figure 2As shown, in this embodiment, one bandpass filter module 42 includes a fourth diode D4 and a fifth diode D5; another bandpass filter module 42 includes a ninth diode D9 and a tenth diode D10. Wherein:

[0090] The anode of the fourth diode D4 is connected to the input port F1, the cathode of the fourth diode D4 is connected to the cathode of the fifth diode D5, and the anode of the fifth diode D5 is connected to the input port F2;

[0091] Similarly, the anode of the ninth diode D9 is connected to the input port F3 , the cathode of the ninth diode D9 is connected to the cathode of the tenth diode D10 , and the anode of the tenth diode D10 is connected to the input port F4 .

[0092] During operation, a sampling point A of the real-time sampling unit 431 may be set between the fourth diode D4 and the fifth diode D5, and another sampling point B of the real-time sampling unit 431 may be set between the ninth diode D9 and the tenth diode D10.

[0093] Therefore, by setting the sampling points A and B, the real-time voltage between the output pins can be effectively detected, thereby obtaining the power status between the output pins in real time.

[0094] (3) Comparison module

[0095] like Figure 2 and Figure 6 As shown, in this embodiment, the comparison module 43 includes a first comparator U1A, a second comparator U1B, a second switch Q2 and a third switch Q3; wherein, one input end of the first comparator U1A is connected to a real-time sampling unit 431 of the comparison module 43, and the other input end of the first comparator U1A is connected to a reference sampling unit 432 of the comparison module 43, and the first comparator U1A is used to control the on-off state of the second switch Q2 according to the adjusted real-time voltage detected by the real-time sampling unit 431 and the reference voltage obtained by the reference sampling unit 432; one input end of the second comparator U1B is connected to another real-time sampling unit 431 of the comparison module 43, and the other input end of the second comparator U1B is connected to another reference sampling unit 432 of the comparison module 43, and the second comparator U1A is used to control the on-off state of the second switch Q2 according to the adjusted real-time voltage detected by the real-time sampling unit 431 and the reference voltage obtained by the reference sampling unit 432. B is used to control the on-off state of the third switch Q3 according to the adjusted real-time voltage detected by another real-time sampling unit 431 and the reference voltage obtained by another reference sampling unit 432; the second switch Q2, the third switch Q3 and the switch module 44 are connected in sequence, the on-off state of the second switch Q2 and the third switch Q3 controls the on-off state of the switch module 44, and the on-off state of the switch module 44 controls the working state of the LED circuit.

[0096] It should be noted that when the second switch Q2 and the third switch Q3 are turned on, the switch module 44 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 44 is turned off, so that the LED circuit 3 and the detection circuit 4 are disconnected.

[0097] For further information, see Figure 7 , the control electrode of the second switch Q2 is connected to the output end of the first comparator U1A, the first electrode of the second switch Q2 is connected to the output end of the buck circuit 2, 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 the second comparator U1B, and the second electrode of the third switch Q3 is connected to the switch module 44.

[0098] For example, when the first comparator U1A and the second comparator UIB both output a low level, the second switch Q2, the third switch Q3 and the switch module 44 are turned on, so that the power circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 works;

[0099] When the first comparator U1A outputs a high level and the second comparator UIB outputs a low level, the second switch Q2 is turned off, the third switch Q3 is turned on, and the switch module 44 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4;

[0100] When the first comparator U1A outputs a low level and the second comparator UIB outputs a high level, the second switch Q2 is turned on, the third switch Q3 is turned off, and the switch module 44 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4;

[0101] When the first comparator U1A and the second comparator UIB both output high level, the second switch Q2 , the third switch Q3 and the switch module 44 are turned off, so that the LED circuit 3 is disconnected from the detection circuit 4 .

[0102] It should be noted that the output levels of the first comparator U1A and the second comparator UIB can affect the on / off state of the second switch Q2 and the third switch Q3, but the specific influencing logic can be set according to the actual situation. For example, it can be set as follows: when the first comparator U1A outputs a low level, the second switch Q2 is turned on; for another example, it can be set as follows: when the first comparator U1A outputs a high level, the second switch Q2 is turned on.

[0103] Furthermore, the real-time sampling unit 431 includes a reference resistor group, a first voltage-dividing resistor group and a second voltage-dividing resistor group connected in series in sequence; a photoelectric pin (i.e., an output end) of the pressure difference detection module 41 is connected to the connection between the reference resistor group and the first voltage-dividing resistor group, another photoelectric pin (i.e., another output end) of the pressure difference detection module 41 is connected to the connection between the first voltage-dividing resistor group and the second voltage-dividing resistor group, and the sampling point of the bandpass filtering module 42 is connected to the input end of the reference resistor group.

[0104] like Figure 2 As shown, in this embodiment, a reference resistor group includes a nineteenth resistor R19, and another reference resistor group includes a thirty-first resistor R31; a first voltage-dividing resistor group includes a twentieth resistor R20, a twenty-third resistor R23 and a twenty-sixth resistor R26 connected in series in sequence, and another first voltage-dividing resistor group includes a thirty-fourth resistor R34, a thirty-fifth resistor R35 and a thirty-seventh resistor R37 connected in series in sequence; a second voltage-dividing resistor group includes a twenty-seventh resistor R27 and a first voltage-dividing diode Z1 connected in parallel, and another second voltage-dividing resistor group includes a thirty-eighth resistor R38 and a second voltage-dividing diode Z2 connected in parallel.

[0105] In addition, the reference sampling unit 432 includes a third voltage-dividing resistor group, and the output end of the voltage-reducing circuit 2 is connected to the voltage-dividing point of the third voltage-dividing resistor group.

[0106] like Figure 2 As shown, in this embodiment, a third voltage-dividing resistor group includes a twenty-fifth resistor R25 and a twenty-ninth resistor R29 connected in series, and another third voltage-dividing resistor group includes a twenty-fourth resistor R24 ​​and a twenty-eighth resistor R28 connected in series.

[0107] (4) Switch module

[0108] like Figure 2 As shown, in this embodiment, the switch module 44 includes a first switch Q1, a control end of the first switch Q1 is connected to the output end of the comparison module 43, 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.

[0109] 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.

[0110] It can be seen from the circuit structures of the pressure difference detection module 41, the bandpass filter module 42, the comparison module 43 and the switch module 44 that: Figure 2 In the embodiment shown:

[0111] The collector (i.e., an output end) of the first optical coupler U3 is connected to ground through the twentieth resistor R20, the twenty-third resistor R23, the twenty-sixth resistor R26, and the twenty-seventh resistor R27 in sequence, and the emitter (i.e., the other output end) is connected to the inverting input end of the first comparator U1A; the inverting input end of the first comparator U1A is also connected to the voltage dividing point between the twenty-sixth resistor R26 and the twenty-seventh resistor R27, and is grounded through the first voltage zener diode Z1; one end of the nineteenth resistor R19 is connected to the collector of the first optical coupler U3, and the other end is connected to the sampling point A and is grounded through the eleventh capacitor C11; the non-inverting input end of the first comparator U1A is connected to the step-down circuit 2 through the twenty-fifth resistor R25, and is grounded through the twenty-ninth resistor R29, and the output end of the first comparator U1A is connected to the gate of the second switch Q2;

[0112] Similarly, the collector (i.e., an output end) of the second optical coupler U4 is connected to ground through the thirty-fourth resistor R34, the thirty-fifth resistor R35, the thirty-seventh resistor R37, and the thirty-eighth resistor R38 in sequence, and the emitter (i.e., the other output end) is connected to the inverting input end of the second comparator U1 B; the inverting input end of the second comparator U1 B is also connected to the voltage dividing point between the thirty-seventh resistor R37 and the thirty-eighth resistor R38, and is grounded through the second voltage zener diode Z2; one end of the thirty-first resistor R31 is connected to the collector of the second optical coupler U4, and the other end is connected to the sampling point B and is grounded through the fourteenth capacitor C14; the non-inverting input end of the second comparator U1 B is connected to the step-down circuit 2 through the twenty-fourth resistor R24, and is grounded through the twenty-eighth resistor R28, and the output end of the second comparator U1 B is connected to the gate of the third switch Q3;

[0113] The source of the second switch Q2 is connected to the step-down circuit 2 , the drain of the second switch Q2 is connected to the source of the third switch Q3 , the drain of the third switch Q3 is connected to the control electrode of the first switch Q1 , one output end of the first switch Q1 is connected to the LED circuit 3 , and the other end is grounded.

[0114] Furthermore, the detection circuit 4 further includes an anti-interference module 45 , and the comparison module 43 and the switch module 44 are connected via the anti-interference module 45 .

[0115] like Figure 2 As shown, in this embodiment, the anti-interference module 45 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 comparison module 43 and the switch module 44; one end of the 32nd resistor R32 is connected to the switch module 44, and the other end is connected to the power supply circuit (i.e., grounded); one end of the RC circuit is connected to the comparison module 43, and the other end is connected to the power supply circuit (i.e., grounded).

[0116] Therefore, the anti-interference module 45 can be used to isolate the comparison module 43 from the switch module 44 , thereby avoiding interference to the switch module 44 and improving the accuracy of the switch module 44 .

[0117] The following further describes Figure 2 The leakage detection principle of the embodiment shown:

[0118] 1. Connect the ballast

[0119] 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, it passes through the tenth resistor R10 to turn on the first optical coupler U3. At this time, the collector C and the emitter D of the first optical coupler U3 are short-circuited by the transistor in the first optical coupler U3, which is equivalent to the twentieth resistor R20, the twenty-third resistor R23 and the twenty-sixth resistor R26 being short-circuited; at the same time, the sampling point A detects the real-time voltage between the fourth diode D4 and the fifth diode D5. Since the twentieth resistor R20, the twenty-third resistor R23 and the twenty-sixth resistor R26 are short-circuited, the real-time voltage single is increased under the voltage division effect of the nineteenth resistor R19, and the voltage of the emitter D is increased. The voltage of the inverting input terminal of the first comparator U1A is higher than the voltage of the non-inverting input terminal. The first comparator U1A outputs a low level (close to 0V), and the second switch Q2 is turned on;

[0120] 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, it passes through the twenty-first resistor R21 to turn on the second optocoupler U4. At this time, the collector E and the emitter F of the second optocoupler U4 are short-circuited by the transistor in the second optocoupler U4, which is equivalent to the thirty-fourth resistor R34, the thirty-fifth resistor R35 and the thirty-seventh resistor R37 being short-circuited; at the same time, the sampling point B detects the real-time voltage between the ninth diode D9 and the tenth diode D10. Since the thirty-fourth resistor R34, the thirty-fifth resistor R35 and the thirty-seventh resistor R37 are short-circuited, the real-time voltage single is increased under the voltage division effect of the thirty-first resistor R31, and the voltage at the emitter F point is increased. The voltage at the inverting input terminal of the second comparator U1 B is higher than the voltage at the non-inverting input terminal. The second comparator U1 B outputs a low level (close to 0V), and the third switch Q3 is turned on;

[0121] 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 constant current driver chip U1 does not meet the working conditions and does not participate in the work.

[0122] 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. The voltage of the emitter D and the emitter F is low due to the addition of the 20th resistor R20, the 23rd resistor R23, the 26th resistor R26 or the 34th resistor R34, the 35th resistor R35, the 37th resistor R37. At this time, the first comparator U1A or the second comparator U1B outputs a high level, 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 at this time has no voltage and current, and the first switch Q1 is in the off state, so that the LED circuit is cut off, so that it is safe for the installer to touch the other end, which plays a role in preventing leakage.

[0123] 2. Connect to the mains

[0124] 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:

[0125] 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.

[0126] 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.

[0127] 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, real-time voltage and reference voltage between the output pins of the power supply end. While considering the voltage factor, the voltage difference factor is also used as the judgment basis, and accurate leakage detection is achieved from multiple angles, which greatly improves 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 comparators, switching tubes, and optocouplers, realizes layer-by-layer comparison of electrical signals and flexible switching of circuits, thereby more accurately controlling the on-off state of the LED circuit with high accuracy.

[0128] 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, the real-time voltage and the reference voltage output by the buck circuit.

2. The leakage protection circuit as claimed in claim 1, characterized in that: The detection circuit includes two pressure difference detection modules, two band-pass filter modules, a comparison module and a switch module. The comparison module is provided with two real-time sampling units and two reference sampling units. The pressure difference detection module, the band-pass filter module, the real-time sampling unit, the reference sampling unit and the two groups of output pins of the power supply end 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 controls the on-off state of the pressure difference detection module according to the real-time pressure difference; The bandpass filter module is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins; The real-time sampling unit is connected to the corresponding pressure difference detection module and the band-pass filtering module respectively, and is used to detect the real-time voltage between a corresponding group of output pins through the band-pass filtering module and adjust the real-time voltage according to the on-off state of the pressure difference detection module; The reference sampling unit is connected to the output end of the step-down circuit to obtain a reference voltage; The output end of the comparison module is connected to the switch module, and is used to control the on-off state of the switch module according to the adjusted real-time voltage 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 comparison 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 according to claim 2, characterized in that: The bandpass filtering module comprises two diodes connected in series in anti-phase, and the real-time sampling unit of the comparison module is connected between the two diodes.

5. 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 comparison 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.

6. The leakage protection circuit according to claim 2, characterized in that: The comparison module includes a first comparator, a second comparator, a second switch and a third switch; An input end of the first comparator is connected to a real-time sampling unit of the comparison module, and another input end of the first comparator is connected to a reference sampling unit of the comparison module, and the first comparator is used to control the on-off state of the second switch according to the adjusted real-time voltage detected by a real-time sampling unit and the reference voltage obtained by a reference sampling unit; One input end of the second comparator is connected to another real-time sampling unit of the comparison module, and another input end of the second comparator is connected to another reference sampling unit of the comparison module, and the second comparator is used to control the on-off state of the third switch according to the adjusted real-time voltage detected by another real-time sampling unit and the reference voltage obtained by another reference sampling unit; The second switch, the third switch and the switch module are connected in sequence, the on-off state of the second switch and 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.

7. The leakage protection circuit according to claim 2, characterized in that: The real-time sampling unit comprises a reference resistor group, a first voltage-dividing resistor group and a second voltage-dividing resistor group connected in series in sequence; One photoelectric pin of the pressure difference detection module is connected to the connection between the reference resistor group and the first voltage-dividing resistor group, another photoelectric pin of the pressure difference detection module is connected to the connection between the first voltage-dividing resistor group and the second voltage-dividing resistor group, and the sampling point of the bandpass filtering module is connected to the input end of the reference resistor group.

8. The leakage protection circuit according to claim 6, 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.

9. The leakage protection circuit according to claim 1, characterized in that: The LED circuit includes 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 driving module does not work; When the power supply circuit is connected to the mains, the driving module 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.

Images