Leakage protection circuit based on ballast

Abstract

The utility model discloses a leakage protection circuit based on a ballast, which relates to the technical field of LEDs and comprises 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 an output pin of the ballast, 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 ballast so as to output a 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 ballast and the LED circuit, and is used for controlling the working state of the LED circuit according to the real-time voltage between the output pins of the ballast 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 and the reference voltage, thereby realizing anti-creeping protection.

Description

TECHNICAL FIELD

[0001] The utility model relates to LED technical field especially, it relates to a leakage protection circuit based on ballast. BACKGROUND

[0002] At present, the lamp tube can select to access ballast to realize power supply.

[0003] In the lighting field, the lamp tube is divided into single-end input and double-end input, the single-end input is actually to set the joint of the alternating current input end in the same end, and the double-end input is divided and set in the two ends of the lamp tube; 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 operator's hand needs to be held at the end of the lamp tube, if the human body accidentally contacts the conductive metal of the end, 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 accessed at the power input end to detect the current flowing through the switch tube, so as to judge whether there is a 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 technical problem to be solved by the utility model lies in providing a leakage protection circuit based on ballast, which can realize leakage protection.

[0007] In order to solve the above technical problem, the utility model provides a leakage protection circuit based on ballast, which comprises: a power circuit, a voltage reduction circuit, an LED circuit and a detection circuit; the input end of the power circuit accesses the output pin of the ballast, the output end of the power circuit is connected with the input end of the voltage reduction circuit and the input end of the LED circuit respectively, and is used for rectifying the output power supply of the ballast to output the power supply to the voltage reduction circuit and the LED circuit; the output end of the voltage reduction circuit is connected with the detection circuit, and is used for reducing the power supply output by the power circuit to output the reference voltage to the detection circuit; the detection circuit is connected with the output pin of the ballast and the LED circuit respectively, and is used for controlling the working state of the LED circuit according to the real-time voltage between the output pins of the ballast and the reference voltage output by the voltage reduction circuit.

[0008] As an improvement of the above-mentioned scheme, the detection circuit comprises two band-pass filter modules, a comparison module and a switch module, the comparison module is provided with two real-time sampling ends and two reference sampling ends, the band-pass filter modules, the real-time sampling ends, the reference sampling ends and two groups of output pins of the ballast are one-to-one corresponding; 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 end is connected to the corresponding band-pass filter module to detect the real-time voltage between the corresponding group of output pins; the reference sampling end 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 real-time voltage and the reference voltage.

[0009] As an improvement of the above-mentioned scheme, the band-pass filter module comprises two diodes connected in anti-parallel, and the real-time sampling end of the comparison module is connected between the two diodes.

[0010] As an improvement of the above-mentioned scheme, the switch module comprises 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.

[0011] 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 to one real-time sampling end of the comparison module, the other input end of the first comparator is connected to one reference sampling end of the comparison module, and the first comparator is used to control the on-off state of the second switch according to the real-time voltage detected by one real-time sampling end and the reference voltage obtained by one reference sampling end; one input end of the second comparator is connected to the other real-time sampling end of the comparison module, the other input end of the second comparator is connected to the other reference sampling end of the comparison module, and the second comparator is used to control the on-off state of the third switch according to the real-time voltage detected by the other real-time sampling end and the reference voltage obtained by the other reference sampling end; 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 circuit, and the on-off state of the switch module controls the working state of the LED circuit.

[0012] 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 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 is turned off, the switch module is turned off to disconnect the LED circuit and the detection circuit, and the LED circuit does not work.

[0013] As the improvement of the above scheme, the comparison module further comprises a first voltage division resistor group, a second voltage division resistor group, a third voltage division resistor group and a fourth voltage division resistor group; one input end of the first comparator is connected with a real-time sampling end of the comparison module through the first voltage division resistor group, and the other input end of the first comparator is connected with a reference sampling end of the comparison module through the second voltage division resistor group; one input end of the second comparator is connected with another real-time sampling end of the comparison module through the third voltage division resistor group, and the other input end of the first comparator is connected with another reference sampling end of the comparison module through the fourth voltage division resistor group.

[0014] As the improvement of the above scheme, the detection circuit further comprises an anti-interference module, and the comparison module and the switch module are connected through the anti-interference module.

[0015] As the improvement of the above scheme, the anti-interference module comprises a thirteenth resistor, a fourteenth resistor and an RC circuit; the thirteenth resistor is connected in series between the comparison module and the switch module; one end of the fourteenth resistor is connected with the switch module, and the other end is connected with the power supply circuit; one end of the RC circuit is connected with the comparison module, and the other end is connected with the power supply circuit.

[0016] As the improvement of the above scheme, the LED circuit comprises a filter module and an LED module which are connected in parallel.

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

[0018] The utility model discloses a ballast-based leakage protection circuit, which takes the electrical signal between output pins before rectification as a detection target, combines the real-time voltage and reference voltage between the output pins of the power supply end, takes the voltage factor as a judgment basis, realizes accurate detection of leakage from the voltage angle, greatly improves the detection accuracy, 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 ballast-based leakage protection circuit of the utility model introduces comparators, switch tubes 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, with high accuracy. DRAWINGS

[0020] Figure 1 Fig. 1 is a structural schematic diagram of the ballast-based leakage protection circuit of the utility model;

[0021] Figure 2 Fig. 2 is a circuit diagram of an embodiment of the ballast-based leakage protection circuit of the utility model;

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

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

[0024] Figure 5 is another structure schematic view of the leakage protection circuit based on the ballast of the utility model. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the utility model more clear, the utility model will be described further in detail below with reference to the drawings. Only this statement, the up, down, left, right, front, back, inside, outside and other directions of the utility model appearing or about to appear in the text, only with the drawings of the utility model as the base, it is not the specific limitation of the utility model.

[0026] Referring to Figure 1 , Figure 1 The specific structure of the leakage protection circuit based on the ballast of the utility model is shown, which comprises a power supply circuit 1, a voltage reduction circuit 2, an LED circuit 3 and a detection circuit 4, specifically:

[0027] The input end of the power supply circuit 1 is connected to the output pin of the ballast, 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 ballast to output the power supply to the voltage reduction circuit 2 and the LED circuit 3;

[0028] The output end of the voltage reduction circuit 2 is connected with the detection circuit 4, for reducing the power supply output by the power supply circuit 1 to output the reference voltage to the detection circuit 4;

[0029] The detection circuit 4 is connected with the output pin of the ballast and the LED circuit 3 respectively, for controlling the working state of the LED circuit 3 according to the real-time voltage between the output pins of the ballast and the reference voltage output by the voltage reduction circuit.

[0030] It should be noted that the leakage protection circuit based on the ballast of the utility model can be applied to the ballast, and the leakage protection of the ballast can be realized at the same time.

[0031] In the prior art, the leakage protection circuit detects the rectified electric signal to realize the leakage protection. Different from the prior art, the leakage protection circuit based on the ballast of the utility model takes the electric signal before rectification (i.e. the electric signal between the output pins) as the detection target, and takes the voltage factor as the judgment basis, realizes the accurate detection of the leakage from the voltage angle, and greatly improves the accuracy of the detection.

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

[0033] I. Power Supply Circuit 1

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

[0035] One AC input terminal of the first rectifier bridge BD1 is connected to input port F1, and the other AC input terminal is connected to input port F2. The negative terminal of the DC output is connected to the step-down circuit 2 and the LED circuit 3, and the positive terminal of the DC output is grounded. One end of the second capacitor C2 is connected to input port F1, and the other end is connected to input port F2.

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

[0037] During operation, input ports F1, F2, F3, and F4 can be connected to the four pins of the ballast.

[0038] II. Step-down circuit 2

[0039] like Figure 2 As 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.

[0040] 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.

[0041] In other embodiments, different numbers and resistance values ​​of resistors can be selected for voltage reduction according to actual needs.

[0042] 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).

[0043] In other embodiments, voltage reduction can be achieved using a step-down chip.

[0044] 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:

[0045] 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 DRAIN 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.

[0046] 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.

[0047] 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.

[0048] The forty-first resistor R41 is connected in parallel with the third inductor L3; the positive terminal of the fourth polarity capacitor CE4 is connected to the open-drain pin DRAIN, and the negative terminal is grounded; the positive terminal of the third polarity capacitor CE3 is connected to power supply circuit 1, and the negative terminal is grounded.

[0049] It should be noted that the voltage after rectification by the first rectifier bridge DB1 and the second rectifier bridge DB2 is 310VDC, which is consistent with the working state of the buck chip U2. Therefore, the buck chip U2 can work normally, play the role of bucking constant current, and supply a constant reference voltage to the detection circuit 4.

[0050] Therefore, in applications, different step-down circuits 2 can be used to step down the power output of power supply circuit 1 according to actual needs, and no restrictions are imposed here.

[0051] III. LED Circuit 3

[0052] like Figure 2As shown, in this embodiment, the LED circuit 3 includes a filter module and an LED module connected in parallel. The filter module includes a sixteenth capacitor C16 and a fortieth resistor R40 connected in parallel, and the LED module includes multiple light-emitting diodes (LED1...LEDN) connected in series. The filter module and the series-connected light-emitting diodes are connected in parallel to achieve a filtering effect.

[0053] IV. Detection Circuit 4

[0054] like Figure 2 As shown, the detection circuit 4 includes two bandpass filter modules 41, a comparison module 42 and a switch module 43. The comparison module 42 is provided with two real-time sampling terminals and two reference sampling terminals. The two sets of output pins of the bandpass filter module 41, the real-time sampling terminal, the reference sampling terminal and the power supply terminal correspond one-to-one.

[0055] The bandpass filter module 41 is connected to a corresponding set of output pins to filter the output power supply between the corresponding set of output pins;

[0056] The real-time sampling terminal is connected to the corresponding bandpass filter module 41 to detect the real-time voltage between a set of corresponding output pins;

[0057] The reference sampling terminal is connected to the output terminal of step-down circuit 2 to obtain the reference voltage;

[0058] The output of the comparison module 42 is connected to the switch module 43 and is used to control the on / off state of the switch module 43 according to the real-time voltage and the reference voltage.

[0059] Therefore, through the cooperation between the bandpass filter module 41, the comparison module 42 and the switching module 43, the switching module 43 can accurately switch on and off according to the real-time voltage between the output pins and the reference voltage of the step-down circuit 2, with high precision.

[0060] The bandpass filter module 41, the comparator module 42, and the switch module 43 are described in detail below:

[0061] (1) Bandpass filter module

[0062] The bandpass filter module 41 includes two diodes connected in series in opposite directions, and the real-time sampling terminal of the comparator module 42 is connected between the two diodes.

[0063] like Figure 2 As shown, in this embodiment, one bandpass filter module 41 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:

[0064] The positive electrode of the fourth diode D4 is connected to the input port F1, the negative electrode of the fourth diode D4 is connected to the negative electrode of the fifth diode D5, and the positive electrode of the fifth diode D5 is connected to the input port F2.

[0065] Similarly, the positive electrode of the ninth diode D9 is connected to the input port F3, the negative electrode of the ninth diode D9 is connected to the negative electrode of the twelfth diode D10, and the positive electrode of the twelfth diode D10 is connected to the input port F4.

[0066] In operation, a real-time sampling terminal A can be arranged between the fourth diode D4 and the fifth diode D5, and another real-time sampling terminal B can be arranged between the ninth diode D9 and the twelfth diode D10.

[0067] Therefore, by arranging the real-time sampling terminals A and B, the real-time voltage between the output pins can be effectively detected, so that the power supply state between the output pins can be obtained in real time.

[0068] (2) Comparison module

[0069] As shown in Figure 2 the embodiment, the comparison module 42 includes a first comparator U1A, a second comparator UIB, a second switch Q2, and a third switch Q3. One input terminal of the first comparator U1A is connected to a real-time sampling terminal of the comparison module 42, and the other input terminal of the first comparator U1A is connected to a reference sampling terminal of the comparison module 42. The first comparator U1A is used to control the on-off state of the second switch Q2 according to the real-time voltage detected by the real-time sampling terminal and the reference voltage obtained by the reference sampling terminal. One input terminal of the second comparator UIB is connected to another real-time sampling terminal of the comparison module 42, and the other input terminal of the second comparator UIB is connected to another reference sampling terminal of the comparison module 42. The second comparator UIB is used to control the on-off state of the third switch Q3 according to the real-time voltage detected by the other real-time sampling terminal and the reference voltage obtained by the other reference sampling terminal. The second switch Q2, the third switch Q3, and the switch module 43 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 43, and the on-off state of the switch module 43 controls the working state of the LED circuit 3.

[0070] It should be noted that when the second switch Q2 and the third switch Q3 are turned on, the switch module 43 is turned on, so that the LED circuit 3 is not working and the power supply circuit 1, the LED circuit 3, and the detection circuit 4 form an LED loop, and the LED circuit 3 works. When the second switch Q2 and / or the third switch Q3 are turned off, the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4, and the LED circuit 3 does not work.

[0071] Further, referring to Figure 5The 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 43.

[0072] For example, when the first comparator U1A and the second comparator U1B both output low levels, the second switch Q2, the third switch Q3 and the switch module 43 are 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;

[0073] When the first comparator U1A outputs a high level and the second comparator U1B outputs a low level, the second switch Q2 is turned off, the third switch Q3 is turned on, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4, and the LED circuit 3 does not work;

[0074] When the first comparator U1A outputs a low level and the second comparator U1B outputs a high level, the second switch Q2 is turned on, the third switch Q3 is turned off, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4, and the LED circuit 3 does not work;

[0075] When the first comparator U1A and the second comparator U1B both output high levels, the second switch Q2, the third switch Q3 and the switch module 43 are turned off, so that the LED circuit 3 is disconnected from the detection circuit 4, and the LED circuit 3 does not work.

[0076] It should be noted that the output levels 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 a low level, the second switch Q2 is turned on; for another example, when the first comparator U1A outputs a high level, the second switch Q2 is turned on.

[0077] Further, the comparison module 42 further comprises a first voltage division resistor group 421, a second voltage division resistor group 422, a third voltage division resistor group 423 and a fourth voltage division resistor group 424; one input end of the first comparator U1A is connected to a real-time sampling end of the comparison module 42 through the first voltage division resistor group 421, and the other input end of the first comparator U1A is connected to a reference sampling end of the comparison module 42 through the second voltage division resistor group 422; one input end of the second comparator U1B is connected to another real-time sampling end of the comparison module 42 through the third voltage division resistor group 423, and the other input end of the second comparator U1B is connected to another reference sampling end of the comparison module 42 through the fourth voltage division resistor group 424.

[0078] It should be noted that in practical applications, different numbers and resistance values ​​of voltage divider resistors can be set according to requirements to form the first voltage divider resistor group 421, the second voltage divider resistor group 422, the third voltage divider resistor group 423 and the fourth voltage divider resistor group 424.

[0079] like Figure 2 As shown, in this embodiment, the first voltage divider resistor group 421 includes the twenty-sixth resistor R26 and the twenty-seventh resistor R27 connected in series; the second voltage divider resistor group 422 includes the twenty-fifth resistor R25 and the twenty-ninth resistor R29 connected in series; the third voltage divider resistor group 423 includes the thirty-seventh resistor R37 and the thirty-eighth resistor R38 connected in series; and the fourth voltage divider resistor group 424 includes the twenty-fourth resistor R24 ​​and the twenty-eighth resistor R28 connected in series.

[0080] (3) Switching module

[0081] like Figure 2 As shown, in this embodiment, the switch module 43 includes a first switch Q1. The control terminal of the first switch Q1 is connected to the output terminal of the comparison module 42. One terminal of the first switch Q1 is connected to the LED circuit 3, and the other terminal of the first switch Q1 is connected to the power supply circuit 1.

[0082] 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 is disconnected from the detection circuit 4, and the LED circuit 3 does not work.

[0083] Based on the circuit structure of the comprehensive bandpass filter module 41, the comparator module 42, and the switch module 43, it can be seen that... Figure 2 In the example shown:

[0084] The non-inverting input of the first comparator U1A is connected to the step-down circuit 2 through the 25th resistor R25 and grounded through the 29th resistor R29. The inverting input of the first comparator U1A is connected to a real-time sampling terminal A through the 26th resistor R26 and grounded through the 27th resistor R27. The output of the first comparator U1A is connected to the gate of the second switch Q2.

[0085] The non-inverting input of the second comparator U1B is connected to the step-down circuit 2 through the twenty-fourth resistor R24 ​​and grounded through the twenty-eighth resistor R28. The inverting input of the second comparator U1B is connected to another real-time sampling terminal B through the thirty-seventh resistor R37 and grounded through the thirty-eighth resistor R38. The output of the second comparator U1B is connected to the gate of the third switch Q3.

[0086] 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.

[0087] Furthermore, the detection circuit 4 also includes an anti-interference module 44, and the comparison module 42 and the switch module 43 are connected through the anti-interference module 44.

[0088] like Figure 2 As shown, in this embodiment, the anti-interference module 44 includes a 30th resistor R30, a 32nd resistor R32, and an RC circuit (with a 33rd resistor R33 and a 13th capacitor C13 connected in parallel); the 30th resistor R30 is connected in series between the comparator module 42 and the switch module 43; one end of the 32nd resistor R32 is connected to the switch module 43, and the other end is connected to the power supply circuit (i.e., ground); one end of the RC circuit is connected to the comparator module 42, and the other end is connected to the power supply circuit (i.e., ground).

[0089] Therefore, the anti-interference module 44 can isolate the comparison module 42 from the switch module 43, avoid interference to the switch module 43, and improve the accuracy of the switch module 43.

[0090] The following is a further description Figure 2 The leakage current detection principle of the embodiment shown is as follows:

[0091] When the ballast is input, a real-time voltage difference exists between input ports F1 and F2. This real-time voltage, after being divided by resistors R26 (26th resistor) and R27 (27th resistor), is greater than the 5V voltage division of the first comparator U1A (where 5V is a vague concept, and this voltage can change depending on the output power supply). The first comparator U1A outputs a low level, thus turning on the second switch Q2. Similarly, a real-time voltage difference exists between input ports F3 and F4. This real-time voltage, after being divided by resistors R37 (37th resistor) and R38 (38th resistor), is greater than the voltage division of the second comparator U1A. The 5V voltage is divided by the second comparator U1B, causing the second comparator U1B to output a low level, thus turning on the third switch Q3. The 5V voltage then flows through the second switch Q2 and the third switch Q3 to the control terminal of the first switch Q1. At this time, the first switch Q1 turns on, causing the output power of the power supply circuit 1 to flow sequentially from the negative DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the LED circuit 3, the first switch Q1, and finally back to the positive DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2, thus forming an LED circuit and lighting up the LED circuit 3.

[0092] When one end of the lamp tube is off, there is no voltage difference between the input ports F1 and F2 or F3 and F4, and the second switch Q2 or the third switch Q3 is not turned on; since one is not turned on, the control electrode of the first switch Q1 is voltage-free and current-free at this time, and the first switch Q1 will be in the off state, so that the LED loop of the circuit is cut off, and it is safe for the installer to contact the other end, and the function of preventing electric leakage is achieved.

[0093] In summary, the utility model discloses the leakage protection circuit based on ballast, and the real-time voltage between the output pins of the power supply end and the reference voltage are combined to take the electric signal between the output pins before rectification as the detection target, and voltage factor is taken as the judgment basis, so that the accurate detection of leakage is realized from the voltage angle, the accuracy of detection is greatly improved, the on-off state of the LED circuit is effectively controlled, the function of preventing electric leakage is achieved, and the safety of people is ensured.

[0094] The above is the preferred embodiment of the utility model, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principle of the utility model, and these improvements and refinements are also regarded as the protection scope of the utility model.

Claims

1. A ballast-based leakage protection circuit, characterized by, 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 ballast, 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 ballast to output 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 reference voltage to the detection circuit. The detection circuit is connected to the output pin of the ballast and the LED circuit respectively, for controlling the working state of the LED circuit according to the real-time voltage between the output pin of the ballast and the reference voltage output by the voltage reduction circuit.

2. The ballast-based ground fault protection circuit of claim 1, wherein, The detection circuit includes two band-pass filter modules, a comparison module and a switch module, the comparison module is provided with two real-time sampling ends and two reference sampling ends, and the band-pass filter module, the real-time sampling end, the reference sampling end and the two groups of output pins of the ballast are one-to-one corresponding. The band-pass filter module is connected to the corresponding group of output pins to filter the output power supply between the corresponding group of output pins. The real-time sampling end is connected to the corresponding band-pass filter module to detect the real-time voltage between the corresponding group of output pins. The reference sampling end 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 real-time voltage and the reference voltage.

3. The ballast-based ground fault protection circuit of claim 2, wherein, The band-pass filter module includes two diodes connected in anti-parallel, and the real-time sampling end of the comparison module is connected between the two diodes.

4. The ballast-based ground fault 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.

5. The ballast-based ground fault protection circuit of claim 2, wherein, The comparison module includes a first comparator, a second comparator, a second switch and a third switch. One input end of the first comparator is connected to one real-time sampling end of the comparison module, the other input end of the first comparator is connected to one reference sampling end of the comparison module, and the first comparator is used for controlling the on-off state of the second switch according to the real-time voltage detected by one real-time sampling end and the reference voltage obtained by one reference sampling end. One input end of the second comparator is connected to the other real-time sampling end of the comparison module, the other input end of the second comparator is connected to the other reference sampling end of the comparison module, and the second comparator is used for controlling the on-off state of the third switch according to the real-time voltage detected by the other real-time sampling end and the reference voltage obtained by the other reference sampling end. 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 circuit, and the on-off state of the switch module controls the working state of the LED circuit.

6. The ballast-based leakage protection circuit of claim 5, wherein, 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 and the detection circuit are disconnected, and the LED circuit does not work.

7. The ballast-based ground fault protection circuit of claim 5, wherein, The comparison module further comprises a first voltage division resistor group, a second voltage division resistor group, a third voltage division resistor group and a fourth voltage division resistor group; One input end of the first comparator is connected with a real-time sampling end of the comparison module through the first voltage division resistor group, and the other input end of the first comparator is connected with a reference sampling end of the comparison module through the second voltage division resistor group; One input end of the second comparator is connected with another real-time sampling end of the comparison module through the third voltage division resistor group, and the other input end of the first comparator is connected with another reference sampling end of the comparison module through the fourth voltage division resistor group.

8. The ballast-based ground fault protection circuit of claim 2, wherein, The detection circuit further comprises an anti-interference module, and the comparison module and the switch module are connected through the anti-interference module.

9. The ballast-based ground fault protection circuit of claim 8, wherein, The anti-interference module comprises a thirteenth resistor, a fourteenth resistor and an RC circuit; The thirteenth resistor is connected in series between the comparison module and the switch module; One end of the fourteenth resistor is connected with the switch module, and the other end is connected with the power supply circuit; One end of the RC circuit is connected with the comparison module, and the other end is connected with the power supply circuit.

10. The ballast-based ground fault protection circuit of claim 1, wherein, The LED circuit comprises a filter module and an LED module which are connected in parallel with each other.

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