Leakage protection circuit

Abstract

The utility model, 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 utility model, 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, thereby realizing anti-creeping protection.

Description

TECHNICAL FIELD

[0001] The utility model relates to LED technical field especially relates to a leakage protection circuit. BACKGROUND

[0002] At present, the lamp tube can select the commercial power direct input or select access ballast to realize power supply. Among them, when selecting the commercial power input, the commercial power is generally 220V / 50HZ or other voltage; and when selecting access ballast, the joint of the lamp tube two ends has high voltage.

[0003] In the lighting field, the lamp tube is divided into single-end input and double-end input, the single-end input is actually that the joint of the alternating current input end is all arranged in the same end, and the double-end input is arranged in the lamp tube two ends; because more lamp holders still retain the double-end access interface, when the original lamp tube is replaced and installed, the lamp tube of double-end input is generally still used.

[0004] In the process of lamp tube installation, the operator generally 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; and because the hand of the operator needs to hold the end of the lamp tube, if the human body accidentally contacts the metal of the end of the lamp tube, electric shock is easy to occur, which affects the operation safety, so it is particularly important to realize the leakage protection of the lamp tube.

[0005] In the prior art, the switch tube is mainly connected in the power input end to detect the current flowing through the switch tube, so as to judge whether there is leakage phenomenon, so as to realize the leakage protection. But the prior art is not effective at any time, when the input end is in poor contact, the leakage protection circuit will be invalid, and the operator still has the danger of electric shock. UTILITY MODEL CONTENTS

[0006] The utility model wants to solve the technical problem to provide a leakage protection circuit, can realize the protection of leakage, and the accuracy is high.

[0007] In order to solve the above technical problem, the utility model provides a leakage protection circuit, which comprises: a power supply circuit, a voltage reducing circuit, an LED circuit and a detection circuit; the input end of the power supply circuit is connected with the output pin of the power supply end, the output end of the power supply circuit is connected with the input end of the voltage reducing circuit and the input end of the LED circuit respectively, is used for rectifying the output power supply of the power supply end to the voltage reducing circuit and the LED circuit output power supply; the output end of the voltage reducing circuit is connected with the detection circuit, is used for carrying out voltage reducing treatment to the power supply of the power supply circuit output to the detection circuit output reference voltage; the detection circuit is connected with the output pin of the power supply end and the LED circuit respectively, is used for according to the real-time voltage difference between the output pin of the power supply end, real-time voltage and the reference voltage output by the voltage reducing circuit control the working condition of the LED circuit.

[0008] As an improvement of the above scheme, the detection circuit comprises two differential pressure 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 differential pressure detection module, the band-pass filter module, the real-time sampling unit, the reference sampling unit and two groups of output pins of the power supply end are in one-to-one correspondence; the differential pressure detection module is connected to a corresponding group of output pins to detect the real-time differential pressure between the corresponding group of output pins, and the differential pressure detection module controls the on-off state of the differential pressure detection module according to the real-time differential pressure; the band-pass 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 with the corresponding differential pressure detection module and band-pass filter module respectively, for detecting the real-time voltage between the corresponding group of output pins through the band-pass filter module and adjusting the real-time voltage according to the on-off state of the differential pressure detection module; the reference sampling unit is connected with the output end of the voltage reduction circuit to obtain a reference voltage; the output end of the comparison module is connected with the switch module to control the on-off state of the switch module according to the adjusted real-time voltage and reference voltage.

[0009] As an improvement of the above scheme, the differential pressure detection module comprises 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 with the rectifier bridge, and the output end of the optocoupler is connected with the comparison module to control the on-off state of the output end of the optocoupler according to the real-time differential pressure of the output power rectified by the rectifier bridge.

[0010] As an improvement of the above scheme, the band-pass filter module comprises two diodes connected in anti-phase, and the real-time sampling unit of the comparison module is connected between the two diodes.

[0011] As an improvement of the above scheme, the switch module comprises a first switch, the control end of the first switch is connected with the output end of the comparison module, one electrode end of the first switch is connected with the LED circuit, and the other electrode end of the first switch is connected with the power supply circuit.

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

[0013] As an improvement of the above-mentioned scheme, 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 sequence; one photoelectric pin of the differential pressure detection module is connected to the connection position of the reference resistor group and the first voltage dividing resistor group, the other photoelectric pin of the differential pressure detection module is connected to the connection position of the first voltage dividing resistor group and the second voltage dividing resistor group, and the sampling point of the band-pass filter module is connected to the input end of the reference resistor group.

[0014] As an improvement of the above-mentioned 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 is turned off, the switch module is turned off, so that the LED circuit and the detection circuit are disconnected.

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

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

[0017] The beneficial effects of the utility model are as follows:

[0018] The leakage protection circuit of the utility model takes the electrical signal between the output pins before rectification as a detection target, combines the real-time voltage difference, real-time voltage and reference voltage between the output pins of the power supply end, considers the voltage factor, takes the voltage difference factor as a judgment basis, realizes accurate detection of leakage from multiple angles, greatly improves the accuracy of detection, effectively controls the on-off state of the LED circuit, plays a role in preventing leakage, and guarantees the safety of people.

[0019] Further, the leakage protection circuit of the utility model introduces comparators, switching tubes and optocouplers and other control elements, realizes layer-by-layer comparison of electrical signals and flexible switching of circuits, and thus more accurately controls the on-off state of the LED circuit and has high accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the leakage protection circuit of the utility model;

[0021] Figure 2 is an embodiment circuit diagram of the leakage protection circuit of the utility model;

[0022] Figure 3 is an embodiment circuit diagram of a voltage reduction circuit in the leakage protection circuit of the utility model;

[0023] Figure 4 is another embodiment circuit diagram of a voltage reduction circuit in the leakage protection circuit of the utility model;

[0024] Figure 5 is an embodiment circuit diagram of a driving module in the leakage protection circuit of the utility model;

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

[0026] Figure 7 is Figure 2 the comparison module. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model will be described in further detail below in combination with the drawings. Only this declaration, the up, down, left, right, front, back, inside, outside and other orientation words appearing in the text or about to appear of the utility model, only take the drawings of the utility model as the benchmark, it is not the specific limitation of the utility model.

[0028] Reference Figure 1 , Figure 1 The specific structure of the utility model leak protection circuit is shown, which comprises a power supply circuit 1, a voltage reduction 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 with the input end of the voltage reduction circuit 2 and the input end of the LED circuit 3 respectively, for rectifying the output power supply of the power supply end to output the power supply to the voltage reduction circuit 2 and the LED circuit 3;

[0030] The output end of the voltage reduction circuit 2 is connected with the detection circuit 4, for reducing the voltage of the power supply circuit 1 output to output the reference voltage to the detection circuit 4;

[0031] The detection circuit 4 is connected with the output pin of the power supply end and the LED circuit 3 respectively, for controlling the working state of the LED circuit 3 according to the real-time voltage difference, real-time voltage between the output pins of the power supply end and the reference voltage output by the voltage reduction circuit 2, so as to realize the leakage control.

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

[0033] In the prior art, the leakage protection circuit detects the single signal after rectification, thereby realizing the leakage protection. Different from the prior art, the utility model leak protection circuit takes the signal before rectification (i.e. the signal between the output pins) as the detection target, and combines the real-time voltage difference, real-time voltage between the output pins of the power supply end and the reference voltage, considering the voltage factor, and also taking the voltage difference factor as the judgment basis, realizing the accurate detection of the leakage from multiple angles, greatly improving the accuracy of the detection.

[0034] The power supply circuit 1, the voltage reduction circuit 2, the LED circuit 3 and the detection circuit 4 will be described in detail below in combination with specific embodiments:

[0035] I. Power supply circuit 1

[0036] AsFigure 2 As shown in the figure, in the embodiment, the power supply circuit 1 comprises 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 DC output negative end is connected to the voltage reduction circuit 2 and the LED circuit 3, and the DC output positive end is grounded; the positive pole of the second diode D2 is connected to the input port F1, and the negative pole is connected to the LED circuit 3; the positive pole of the third diode D3 is connected to the input port F2, and the negative pole 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 voltage reduction circuit 2 and the LED circuit 3, and the DC output positive end is grounded; the positive pole of the seventh diode D7 is connected to the input port F3, and the negative pole is connected to the LED circuit 3; the positive pole of the eighth diode D8 is connected to the input port F4, and the negative pole 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 utility model is applied to the ballast, the input ports F1, F2, F3 and F4 can be connected to four pins of the ballast.

[0040] When the utility model is applied to the commercial power, any two input ports can be selected to be connected to two pins of the commercial power, for example, the input ports F1 and F2, or the input ports F3 and F4, or the input ports F1 and F3, or the input ports F1 and F4, or the input ports F2 and F3, or the input ports F2 and F4.

[0041] Therefore, the output power supply of the power supply end can be rectified by the power supply circuit 1 to output stable power supply to the voltage reduction circuit 2 and the LED circuit 3.

[0042] II. Voltage reduction circuit 2

[0043] As shown in the figure, Figure 2As shown, in this embodiment, the step-down circuit 2 includes a voltage divider resistor group (first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, and fifth resistor R5), a first capacitor C1, and a first Zener 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 Zener diode D1, respectively. The positive terminal of the first Zener diode D1 is grounded, and the negative terminal is connected to the detection circuit 4.

[0044] Therefore, the step-down circuit 2 can step down the power supply output from the power supply circuit 1 and convert it into a 5V reference voltage for use by the detection circuit 4.

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

[0046] like Figure 3 As shown, in this embodiment, the voltage divider resistor group includes four resistors connected in series (second resistor R2, third resistor R3, fourth resistor R4 and fifth resistor R5).

[0047] In other embodiments, voltage reduction can be achieved using a step-down chip.

[0048] like Figure 4 As shown, in this embodiment, the step-down circuit 2 includes a step-down 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 step-down chip U2 is connected to the negative terminal of the twelfth diode D12. The clock pin SCL and the power supply pin VCC are respectively connected to the negative terminal of the eleventh diode D11. The open-drain pin DRAI N is connected to the power supply circuit 1 through the third inductor L3. The chip select pin CS is connected to the negative terminal of the twelfth diode D12 through the current limiting resistor RS1.

[0050] The positive terminal of the twelfth diode D12 is grounded, and the negative terminal is connected to the detection circuit 4 through the fourth inductor L4 and to the negative terminal of the eleventh diode D11 through the seventeenth capacitor C17. The positive terminal 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.

[0052] The fourth resistance R41 is connected in parallel with the third inductor L3; the positive pole of the fourth polarity capacitor CE4 is connected with the open-drain pin DRAIN, and the negative pole is grounded; the positive pole of the third polarity capacitor CE3 is connected with the power supply circuit 1, and the negative pole is grounded.

[0053] It should be noted that when the city power is accessed, whether the input ports F1 and F2 are accessed in single end, or the input ports F3 and F4 are accessed in single end, or the input is accessed in double end, the voltage rectified by the first rectifier bridge DB1 and the second rectifier bridge DB2 is 310VDC, which meets the working state of the step-down chip U2; therefore, the step-down chip U2 can work normally, plays a role of step-down constant current, and supplies a constant reference voltage to the detection circuit 4.

[0054] Therefore, in the application, different step-down circuits 2 can be used to perform step-down processing on the power supply output by the power supply circuit 1 according to actual needs, which is not limited here.

[0055] III. LED circuit 3

[0056] (1) When the leakage protection circuit of the utility model is only applied to the ballast, the LED circuit 3 can not be provided with the driving module.

[0057] (2) When the leakage protection circuit of the utility model is applied to the city power and the ballast at the same time, the LED circuit 3 includes the driving module 32 and the LED module 31, and the input end of the driving module 32 is connected with the output end of the LED module 31.

[0058] (2.1) When the power supply circuit 1 is accessed to the ballast, the driving module 32 does not work;

[0059] (2.2) When the power supply circuit 1 is accessed to the city power and the driving module 32 has the 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, so as to control the working state of the LED circuit 31;

[0060] For example, when the driving module 32 does not detect the leakage condition, the driving module 32 and the LED module 31 are turned on, the driving module 32 drives the LED module 31, so as to ensure the constant current power supply of the LED module 31.

[0061] For another example, when the driving module 32 detects the leakage condition, the driving module 32 and the LED module 31 are disconnected, and the LED module 31 is disconnected.

[0062] In some embodiments, the LED module 31 comprises a plurality of light emitting diodes connected in series. The driving module 32 comprises a driving chip U1, which is provided with a detection pin REC and an open-drain pin DRAIN, and the open-drain pin DRAIN is provided with a built-in switch. The detection pin REC is connected with the power supply circuit 1, and is used for detecting the power supply output by the power supply circuit 1. The open-drain pin DRAIN is connected with 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.

[0063] As shown in FIG. 1, Figure 2 In the embodiment, the driving module 32 comprises 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. The open-drain pin DRAIN of the driving chip U1 is connected with the negative electrode of the LED module 31 through the first transformer coil T1. The compiling pins ISP are connected with the ground through the seventeenth resistor R17 and the eighteenth resistor R18 respectively. The ground pin GND is connected with the ground, and is connected with the positive electrode of the sixth diode D6 through the ninth capacitor C9. The negative electrode of the sixth diode D6 is connected with the positive electrode of the LED module 31. The detection pin REC is connected with the power supply circuit 1 through the fourteenth resistor R14 and the thirteenth resistor R13 in sequence, and is connected with the ground through the voltage stabilizing diode TVS1 and the fifteenth resistor R15 respectively. The power supply pin VIN is connected with the positive electrode of the LED module through the eighth resistor R8. One end of the tenth capacitor C10 is connected with the ground, and the other end is connected with the negative electrode of the LED module 31 and the detection circuit 4 respectively. One end of the ninth resistor R9 is connected with the positive electrode of the LED module 31, and the other end is connected with the open-drain pin DRAIN through the seventh capacitor C7. One end of the first polarity capacitor CE1 is connected with the positive electrode of the LED module 31, and the other end is connected with the negative electrode of the LED module 31. The eleventh resistor R11 is connected with the first polarity capacitor CE1 in parallel.

[0064] It should be noted that the detection pin REC of the driving chip U1 has an input current detection function. When the power supply is greater than 72MA, the driving chip U1 opens the built-in switch of the open-drain pin DRAIN. When the power supply is less than 72MA, the driving chip U1 closes the built-in switch of the open-drain pin DRAIN. Preferably, the driving chip U1 can be JW1830, JW1831, JW1832 or other similar solutions, but is not limited thereto.

[0065] Furthermore, in this embodiment, the LED circuit 3 also includes a filter circuit 33. The input terminal of the filter circuit 33 is connected to the output terminal of the power supply circuit 1, and the output terminal of the filter circuit 33 is connected to the driving module 32 and the LED module 31 respectively.

[0066] like Figure 2 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. 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 terminal 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 terminal 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 terminal of the LED module. The seventh resistor R7 is connected in parallel with the first inductor L1.

[0067] Therefore, the power supply voltage output by the power supply circuit 1 can be filtered by the filter circuit 33 to supply power to the drive module 32 and the LED module 31.

[0068] (2.3) When the power supply circuit 1 is connected to the mains power and the drive module 32 does not have leakage protection function, the drive module 32 works to drive the LED module 31, thereby ensuring the constant current power supply of the LED circuit 3.

[0069] 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 polarized 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. Specifically: 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 terminal of the LED module 31 through the eighth resistor R8; the open-drain pin DRAI N is connected to the positive terminal of the LED module 31 through the thirteenth diode D13, and to the negative terminal of the LED module 31 through the second inductor L2; the compiler pin I SP 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 terminal of the LED module 31, and the other end is grounded; the positive terminal of the eighteenth polarity capacitor C18 is connected to the positive terminal of the LED module 31, the negative terminal of the eighteenth polarity capacitor C18 is connected to the detection circuit 4 and the negative terminal of the LED module 31, and is grounded through the tenth capacitor C10; the eighteenth polarity capacitor C18 and the nineteenth capacitor C19 are connected in parallel.

[0070] Therefore, when accessing the mains, the LED module 31 can be driven by the driving chip U1 for constant current driving to ensure normal use of the LED module 31.

[0071] IV. Detection circuit 4

[0072] As shown in Figure 2 and Figure 6 The detection circuit 4 includes two differential pressure detection modules 41, two band-pass filter modules 42, a comparison module 43, and a switching module 44. The comparison module 43 is provided with two real-time sampling units 431 and two reference sampling units 432. The differential pressure 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 terminal correspond one by one.

[0073] The differential pressure detection module 41 is connected to a corresponding group of output pins to detect the real-time differential pressure between the corresponding group of output pins and control the on-off state of the differential pressure detection module 41 according to the real-time differential pressure.

[0074] The band-pass filter module 42 is connected to a corresponding group of output pins to filter the output power between the corresponding group of output pins.

[0075] The real-time sampling unit 431 is connected to the corresponding differential pressure detection module 41 and band-pass filter module 42, respectively, for detecting the real-time voltage between the corresponding group of output pins through the band-pass filter module 42 and adjusting the real-time voltage according to the on-off state of the differential pressure detection module.

[0076] The reference sampling unit 432 is connected to the output terminal of the voltage reduction circuit 2 to obtain a reference voltage.

[0077] The output terminal of the comparison module 43 is connected to the switching module 44, and the comparison module 43 is used to control the on-off state of the switching module 44 according to the adjusted real-time voltage and reference voltage.

[0078] Therefore, through the mutual cooperation between the differential pressure detection module 41, the band-pass filter module 42, the real-time sampling unit 431, the reference sampling unit 432, and the comparison module 43, the switching module 44 can accurately switch according to the real-time differential pressure between the output pins, the real-time voltage, and the reference voltage of the voltage reduction circuit 2, with high accuracy.

[0079] The differential pressure detection module 41, the band-pass filter module 42, the comparison module 43, and the switching module 44 are described in detail as follows:

[0080] (1) Differential pressure detection module

[0081] The differential pressure 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 of the optocoupler is connected to the rectifier bridge, and the output of the optocoupler is connected to the comparator module 43, which controls the on / off state of the output of the optocoupler according to the real-time differential pressure of the output power after rectification by the rectifier bridge.

[0082] like Figure 2 As shown, in this embodiment, the differential pressure 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 optocoupler U3, and a second optocoupler U4. Wherein:

[0083] One AC input terminal of the third rectifier bridge BD3 is connected to input port F1, and the other AC input terminal is connected to input port F2; one end of the sixth capacitor C6 is connected to the negative DC output terminal of the third rectifier bridge BD3, and the other end is connected to the positive DC output terminal of the third rectifier bridge BD3; the twelfth resistor R12 is connected in parallel with the sixth capacitor C6; the positive terminal of the emitter of the first optocoupler U3 is connected to the negative DC output terminal of the third rectifier bridge BD3 through the tenth resistor R10, the negative terminal of the emitter is connected to the positive DC output terminal of the third rectifier bridge BD3, and the output terminal is connected to a real-time sampling unit 431 of the comparator module 43;

[0084] Similarly, one AC input terminal of the fourth rectifier bridge BD4 is connected to input port F3, and the other AC input terminal is connected to input port F4; one end of the twelfth capacitor C12 is connected to the negative DC output terminal of the fourth rectifier bridge BD4, and the other end is connected to the positive DC output terminal of the fourth rectifier bridge BD4; the twenty-second resistor R22 is connected in parallel with the twelfth capacitor C12; the positive terminal of the emitter of the second optocoupler U4 is connected to the negative DC output terminal of the fourth rectifier bridge BD4 through the twenty-first resistor R21, the negative terminal of the emitter is connected to the positive DC output terminal of the fourth rectifier bridge BD4, and the output terminal is connected to another real-time sampling unit 431 of the comparator module 43.

[0085] Therefore, the differential pressure detection module 41 can effectively detect the real-time differential pressure between the output pins through the cooperation between the various components, thereby flexibly controlling the on / off state of the optocoupler.

[0086] (2) Bandpass filter module

[0087] The bandpass filter module 42 includes two diodes connected in series in opposite directions, and the real-time sampling unit 431 of the comparison module 43 is connected between the two diodes.

[0088] like Figure 2As shown, in this embodiment, one bandpass filter module 42 includes a fourth diode D4 and a fifth diode D5; the other bandpass filter module 42 includes a ninth diode D9 and a tenth diode D10. Wherein:

[0089] The positive terminal of the fourth diode D4 is connected to the input port F1, the negative terminal of the fourth diode D4 is connected to the negative terminal of the fifth diode D5, and the positive terminal of the fifth diode D5 is connected to the input port F2.

[0090] Similarly, the positive terminal of the ninth diode D9 is connected to the input port F3, the negative terminal of the ninth diode D9 is connected to the negative terminal of the tenth diode D10, and the positive terminal of the tenth diode D10 is connected to the input port F4.

[0091] During operation, a sampling point A of a real-time sampling unit 431 can be set between the fourth diode D4 and the fifth diode D5, and a sampling point B of another real-time sampling unit 431 can be set between the ninth diode D9 and the tenth diode D10.

[0092] Therefore, by setting sampling points A and B, the real-time voltage between the output pins can be effectively detected, thereby obtaining the power supply status between the output pins in real time.

[0093] (3) Comparison Module

[0094] 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 terminal of the first comparator U1A is connected to a real-time sampling unit 431 of the comparison module 43, and the other input terminal of the first comparator U1A is connected to a reference sampling unit 432 of the comparison module 43. 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 terminal of the second comparator U1B is connected to another real-time sampling unit 431 of the comparison module 43, and the other input terminal of the second comparator U1B is connected to another reference sampling unit 432 of the comparison module 43. B is used to control the on / off state of the third switch Q3 based on 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, and 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.

[0095] 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 to form an LED loop of the power supply circuit 1, the LED circuit 3 and the detection circuit 4, 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 to disconnect the LED circuit 3 and the detection circuit 4.

[0096] Further, referring to 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 voltage reduction 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.

[0097] For example, when the first comparator U1A and the second comparator U1B both output low level, the second switch Q2, the third switch Q3 and the switch module 44 are turned on to form an LED loop of the power supply circuit 1, the LED circuit 3 and the detection circuit 4, and the LED circuit 3 works;

[0098] When the first comparator U1A outputs high level and the second comparator U1B outputs low level, the second switch Q2 is turned off, the third switch Q3 is turned on, and the switch module 44 is turned off to disconnect the LED circuit 3 and the detection circuit 4;

[0099] When the first comparator U1A outputs low level and the second comparator U1B outputs high level, the second switch Q2 is turned on, the third switch Q3 is turned off, and the switch module 44 is turned off to disconnect the LED circuit 3 and the detection circuit 4;

[0100] When the first comparator U1A and the second comparator U1B both output high level, the second switch Q2, the third switch Q3 and the switch module 44 are turned off to disconnect the LED circuit 3 and the detection circuit 4.

[0101] It should be noted that the output level of the first comparator U1A and the second comparator U1B can affect the on-off state of the second switch Q2 and the third switch Q3, but the specific influence logic can be set according to the actual situation. For example, when the first comparator U1A outputs low level, the second switch Q2 is turned on; for another example, when the first comparator U1A outputs high level, the second switch Q2 is turned on.

[0102] Further, the real-time sampling unit 431 comprises a reference resistance group, a first voltage division resistance group and a second voltage division resistance group connected in series; one photoelectric pin (i.e. one output end) of the differential pressure detection module 41 is connected to the connection between the reference resistance group and the first voltage division resistance group, the other photoelectric pin (i.e. the other output end) of the differential pressure detection module 41 is connected to the connection between the first voltage division resistance group and the second voltage division resistance group, and the sampling point of the band-pass filter module 42 is connected to the input end of the reference resistance group.

[0103] As shown in the figure, Figure 2 In the embodiment, the reference resistance group comprises the nineteenth resistance R19, the other reference resistance group comprises the thirty-first resistance R31; the first voltage division resistance group comprises the twentieth resistance R20, the twenty-third resistance R23 and the twenty-sixth resistance R26 connected in series, the other first voltage division resistance group comprises the thirty-fourth resistance R34, the thirty-fifth resistance R35 and the thirty-seventh resistance R37 connected in series; the second voltage division resistance group comprises the twenty-seventh resistance R27 and the first voltage stabilizing diode Z1 connected in parallel, the other second voltage division resistance group comprises the thirty-eighth resistance R38 and the second voltage stabilizing diode Z2 connected in parallel.

[0104] In addition, the reference sampling unit 432 comprises a third voltage division resistance group, and the output end of the voltage reduction circuit 2 is connected to the voltage division point of the third voltage division resistance group.

[0105] As shown in the figure, Figure 2 In the embodiment, the third voltage division resistance group comprises the twenty-fifth resistance R25 and the twenty-ninth resistance R29 connected in series, and the other third voltage division resistance group comprises the twenty-fourth resistance R24 and the twenty-eighth resistance R28 connected in series.

[0106] (4) Switching module

[0107] As shown in the figure, Figure 2 In the embodiment, the switching module 44 comprises the first switch Q1, the control end of the first switch Q1 is connected to the output end of the comparison module 43, one 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.

[0108] Therefore, when the first switch Q1 is turned on, 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 first switch Q1 is turned off, the LED circuit 3 and the detection circuit 4 are disconnected.

[0109] As shown in the figure, Figure 2 In the embodiment,

[0110] The collector (i.e., one output terminal) of the first optocoupler U3 is grounded sequentially through the twentieth resistor R20, the twenty-third resistor R23, the twenty-sixth resistor R26, and the twenty-seventh resistor R27. The emitter (i.e., the other output terminal) is connected to the inverting input terminal of the first comparator U1A. The inverting input terminal of the first comparator U1A is also connected to the voltage divider point between the twenty-sixth resistor R26 and the twenty-seventh resistor R27, and grounded through the first Zener diode Z1. One end of the nineteenth resistor R19 is connected to the collector of the first optocoupler U3, and the other end is connected to the sampling point A and grounded through the eleventh capacitor C11. The non-inverting input terminal of the first comparator U1A is connected to the buck circuit 2 through the twenty-fifth resistor R25 and grounded through the twenty-ninth resistor R29. The output terminal of the first comparator U1A is connected to the gate of the second switch Q2.

[0111] Similarly, the collector (i.e., one output terminal) of the second optocoupler U4 is grounded sequentially through the thirty-fourth resistor R34, the thirty-fifth resistor R35, the thirty-seventh resistor R37, and the thirty-eighth resistor R38, and the emitter (i.e., the other output terminal) is connected to the inverting input terminal of the second comparator U1 B; the inverting input terminal of the second comparator U1 B is also connected to the voltage divider point between the thirty-seventh resistor R37 and the thirty-eighth resistor R38, and grounded through the second Zener diode Z2; one end of the thirty-first resistor R31 is connected to the collector of the second optocoupler U4, and the other end is connected to the sampling point B and grounded through the fourteenth capacitor C14; the non-inverting input terminal of the second comparator U1 B is connected to the buck circuit 2 through the twenty-fourth resistor R24, and grounded through the twenty-eighth resistor R28; the output terminal of the second comparator U1 B is connected to the gate of the third switch Q3;

[0112] 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 terminal of the first switch Q1, one output terminal of the first switch Q1 is connected to the LED circuit 3, and the other terminal is grounded.

[0113] Furthermore, the detection circuit 4 also includes an anti-interference module 45, and the comparison module 43 and the switch module 44 are connected through the anti-interference module 45.

[0114] like Figure 2 As shown, in this embodiment, the anti-interference module 45 includes a thirtieth resistor R30, a thirty-second resistor R32, and an RC circuit (with a thirty-third resistor R33 and a thirteenth capacitor C13 connected in parallel); the thirtieth resistor R30 is connected in series between the comparator module 43 and the switch module 44; one end of the thirty-second resistor R32 is connected to the switch module 44, and the other end is connected to the power supply circuit (i.e., ground); one end of the RC circuit is connected to the comparator module 43, and the other end is connected to the power supply circuit (i.e., ground).

[0115] Therefore, the isolation between the comparison module 43 and the switch module 44 can be realized by the anti-interference module 45, interference on the switch module 44 is avoided, and accuracy of the switch module 44 is improved.

[0116] The leakage detection principle of the embodiment shown is further described below Figure 2 The leakage detection principle of the embodiment shown is further described below

[0117] I. Access to ballast

[0118] When the ballast is accessed, 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 first optocoupler U3 is turned on through the tenth resistor R10. At this time, the collector C and the emitter D of the first optocoupler U3 are short-circuited by the transistor in the first optocoupler U3, which is equivalent to that the twentieth resistor R20, the twenty-third resistor R23 and the twenty-sixth resistor R26 are 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 voltage of the emitter D is raised under the voltage division of the nineteenth resistor R19, the voltage of the inverting input terminal of the first comparator U1A is higher than that 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.

[0119] 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 second optocoupler U4 is turned on through the twenty-first resistor R21. 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 that the thirty-fourth resistor R34, the thirty-fifth resistor R35 and the thirty-seventh resistor R37 are short-circuited. At the same time, the sampling point B detects the real-time voltage between the ninth diode D9 and the twelfth diode D10. Since the thirty-fourth resistor R34, the thirty-fifth resistor R35 and the thirty-seventh resistor R37 are short-circuited, the voltage of the emitter F point is raised under the voltage division of the thirty-first resistor R31, the voltage of the inverting input terminal of the second comparator U1B is higher than that of the non-inverting input terminal, the second comparator U1B outputs a low level (close to 0V), and the third switch Q3 is turned on.

[0120] The voltage enters the control electrode of the first switch Q1 through the second switch Q2 and the third switch Q3, and the first switch Q1 is turned on, so that the output power supply of the power supply circuit 1 flows through the first inductor L1, the LED module 31, the first switch Q1 in turn from the DC output negative terminal of the first rectifier bridge BD1 and the second rectifier bridge BD2, and finally returns to the DC output positive terminal of the first rectifier bridge BD1 and the second rectifier bridge BD2, so as to form an LED loop, thereby making the LED module 31 light up. At this time, the negative electrode of the LED module 31 is pulled to the ground by the first switch Q1, and the open-drain pin DRAIN of the driving chip U1 is equivalent to the ground at this time, so that the constant-current driving chip U1 does not meet the working condition and does not participate in the work.

[0121] When one end of the lamp tube is detached, there is no voltage difference between the input ports F1 and F2 or F3 and F4, and the voltage of the emitter D and the emitter F is low due to the addition of the twentieth resistor R20, the twenty-third resistor R23, the twenty-sixth resistor R26 or the thirty-fourth resistor R34, the thirty-fifth resistor R35 and the thirty-seventh 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 turned on. Since one of them is not turned on, the control electrode of the first switch Q1 has no voltage and current at this time, and the first switch Q1 is in the off state, so that the LED loop is cut off, and it is safe for the installer to touch the other end, thereby playing a role in preventing electric leakage.

[0122] II. Access to mains

[0123] When accessing to the mains, the single-ended or double-ended of the power supply 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 scheme, which can be wide voltage, narrow voltage, single voltage, etc. The following describes the working principle by taking 220V / 50HZ as an example:

[0124] When accessing the mains, the voltage input is through the input port F1 and F2, or the input port F3 and F4, or the input port F1, F2 and F3, F4 combination (such as, from F1 and F3, or F1 and F4, or F2 and F3, or F2 and F4 input);But no matter which way is two feet input, at this time the second switch Q2 or the third switch Q3 is not conductive;Because one is not conductive, the control electrode of the first switch Q1 at this time has no voltage and current, the first switch Q1 is in the off state, so that the first switch Q1 does not work, does not affect the work of the driving chip U1, so that the output power supply of the power supply circuit 1 is sequentially from the DC output negative terminal 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 driving chip U1 and the compile pin ISP, and finally returns to the DC output positive terminal 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.

[0125] At this time, when one foot input is disconnected from the human body, because the internal resistance of the human body is greater than 500Ω, the detection pin REC equivalent to the driving chip U1 is connected to a resistor at this time, the current of the detection pin REC will decrease, so that the state of more than 72MA before changes to less than 72MA, at this time the built-in switch of the open drain pin DRAIN is closed, so that the LED loop is cut off, and the effect of leakage protection is achieved.

[0126] In summary, the leakage protection circuit of the utility model takes the output pin interval electrical signal before rectification as the detection target, and combines the real-time voltage difference, real-time voltage and reference voltage of the output pin interval of the power supply end, considers the voltage factor, and also takes the voltage difference factor as the basis for judgment, realizes accurate detection of leakage from multiple angles, greatly improves the accuracy of detection, thereby effectively controls the on-off state of the LED circuit, plays the role of preventing leakage, and ensures the safety of the human body;Further, the leakage protection circuit of the utility model introduces comparators, switching tubes, optocouplers and other control elements, realizes layer-by-layer comparison of electrical signals and flexible switching of circuits, thereby more accurately controls the on-off state of the LED circuit, and has high accuracy.

[0127] The above is the preferred embodiment of the utility model, and it should be pointed out that for ordinary technical personnel in the technical field, without departing from the principle of the utility model, some improvements and decorations can be made, and these improvements and decorations are also considered as the protection range of the utility model.

Claims

1. An electric leakage protection circuit, characterized by comprising: The power supply circuit, the voltage reduction circuit, the LED circuit and the detection circuit are included. 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 connected to the input end of the voltage reduction circuit and the input end of the LED circuit respectively, for rectifying the output power supply of the power supply end to output the power supply to the voltage reduction circuit and the LED circuit. The output end of the voltage reduction circuit is connected to the detection circuit, for reducing the power supply output by the power supply circuit to output the 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, for controlling the working state of the LED circuit according to the real-time voltage difference, the real-time voltage between the output pins of the power supply end and the reference voltage output by the voltage reduction circuit.

2. The leakage protection circuit of claim 1, wherein, The detection circuit includes two voltage 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, and the voltage 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 are one-to-one corresponding. The voltage difference detection module is connected to a corresponding group of output pins to detect the real-time voltage difference between the corresponding group of output pins and control the on-off state of the voltage difference detection module according to the real-time voltage difference. The band-pass filter module is connected to a corresponding group of output pins to filter the output power supply between the corresponding group of output pins. The real-time sampling unit is connected to the corresponding voltage difference detection module and band-pass filter module respectively, for detecting the real-time voltage between the corresponding group of output pins through the band-pass filter module and adjusting the real-time voltage according to the on-off state of the voltage difference detection module. The reference sampling unit is connected to the output end of the voltage reduction circuit to obtain the reference voltage. The output end of the comparison module is connected to the switch module 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 of claim 2, wherein, The voltage 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 supply 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 to control the on-off state of the output end of the optocoupler according to the real-time voltage difference of the rectified output power supply of the rectifier bridge.

4. The ground fault protection circuit of claim 2, wherein, The band-pass filter module includes two diodes connected in anti-phase, and the real-time sampling unit of the comparison module is connected between the two diodes.

5. The leakage protection circuit of claim 2, wherein, The switch module includes a first switch, the control end of the first switch is connected to the output end of the comparison module, one electrode end of the first switch is connected to the LED circuit, and the other electrode end of the first switch is connected to the power supply circuit.

6. The leakage protection circuit of claim 2, wherein, The comparison module includes a first comparator, a second comparator, a second switch and a third switch. An input terminal of the first comparator is connected with a real-time sampling unit of the comparison module, another input terminal of the first comparator is connected with a reference sampling unit of the comparison module, and the first comparator is configured to control on-off states of the second switch according to an adjusted real-time voltage detected by the real-time sampling unit and a reference voltage obtained by the reference sampling unit; An input terminal of the second comparator is connected with another real-time sampling unit of the comparison module, another input terminal of the second comparator is connected with another reference sampling unit of the comparison module, and the second comparator is configured to control on-off states of the third switch according to an adjusted real-time voltage detected by the another real-time sampling unit and a reference voltage obtained by the another reference sampling unit; The second switch, the third switch and the switch module are connected in sequence, the on-off states of the second switch and the third switch control the on-off states of the switch module, and the on-off states of the switch module control the working state of the LED circuit.

7. The ground fault protection circuit of claim 2, wherein, 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 sequence; An optoelectrical pin of the differential pressure detection module is connected to a connection position of the reference resistor group and the first voltage dividing resistor group, another optoelectrical pin of the differential pressure detection module is connected to a connection position of the first voltage dividing resistor group and the second voltage dividing resistor group, and a sampling point of the band-pass filter module is connected to an input terminal of the reference resistor group.

8. The leakage protection circuit of claim 6, wherein, when the second switch and the third switch are turned on, the switch module is turned on to form an LED loop of the power supply circuit, the LED circuit and the detection circuit, and the LED circuit works; when the second switch and / or the third switch are turned off, the switch module is turned off to disconnect the LED circuit and the detection circuit.

9. The ground fault protection circuit of claim 1, wherein, The LED circuit comprises a driving module and an LED module, an input terminal of the driving module is connected with an output terminal of the LED module, and the driving module is configured to control the working state of the LED module according to the power supply; when the power supply circuit is connected with the ballast, the driving module does not work; when the power supply circuit is connected with the mains, the driving module controls on-off states 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 of claim 9, wherein, 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 an internal switch; the detection pin is connected with the power supply circuit to detect the power supply output by the power supply circuit; the open-drain pin is connected with the LED module, and the internal switch switches the on-off states according to the power supply to control the on-off states between the driving module and the LED module.

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