CN203072235U - Arc detection and protection circuit for cold cathode fluorescence lamp (CCFL) - Google Patents
Arc detection and protection circuit for cold cathode fluorescence lamp (CCFL) Download PDFInfo
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- CN203072235U CN203072235U CN 201320007752 CN201320007752U CN203072235U CN 203072235 U CN203072235 U CN 203072235U CN 201320007752 CN201320007752 CN 201320007752 CN 201320007752 U CN201320007752 U CN 201320007752U CN 203072235 U CN203072235 U CN 203072235U
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- ccfl
- cathode fluorescence
- fluorescence lamp
- resistance
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Abstract
The utility model relates to an arc detection and protection circuit for a cold cathode fluorescence lamp (CCFL). The circuit comprises that a CCFL loop is connected with the CCFL by a connector, a CCFL power-supply inverter control chip in the CCFL loop is connected with an arc sampling and voltage comparison circuit, a long lead L1 in the CCFL loop and a lead L2 in the arc sampling and voltage comparison circuit form an arc sampling apparatus; and the L2 is parallel with the L1 and near the L1 and length of the L2 is equal to length of the L1. Through an electromagnetic induction principle, voltage capable of detecting whether arc is generated is generated on the lead L2, sampling and voltage comparison are performed and signals are transmitted to the CCFL power-supply inverter control chip. When the arc is generated, the CCFL power-supply inverter control chip controls a CCFL power-supply inverter to stop outputting high voltage until arc faults are eliminated in order to achieve a purpose of protecting a CCFL tube and the power supply inverter.
Description
Technical field
The utility model relates to arc-detection and protective circuit, specifically, relates to a kind of cold-cathode fluorescence lamp (CCFL) arc-detection and protective circuit.
Background technology
Present liquid crystal display screen mainly adopts passive light-emitting mode, and just liquid crystal itself is not luminous, and the liquid crystal display screen light source mainly is by cold-cathode fluorescence lamp CCFL lamp luminescence, and CCFL lamp luminescence quality directly influences liquid crystal display screen picture quality.Be in performance and security requirement, when lamp works is unusual, during as fluorescent tube open circuit, lamp tube air leaking, joint loose contact, need inverter that protective effect is arranged, close output voltage.If do not protect when the lamp tube joint loose contact contact point discharge can to occur and to damage liquid crystal display screen, occur easily simultaneously causing potential safety hazard because of the long-living naked light that discharges.
Be illustrated in figure 1 as the cold-cathode fluorescence lamp connection diagram.For easy to connect, design connector S1, S2 between power initiation device and cold-cathode fluorescence lamp, S1, when S2 links together, A meets B, and C meets D, with convenient design, produce and maintenance or more new parts is for convenience detach.If but loose contact just is easy to generate electric arc between A and B or C and the D.Being illustrated in figure 2 as the current waveform under the cold-cathode fluorescence lamp normal operation, is sinusoidal wave.Shown in Figure 3 is cold-cathode fluorescence lamp current in loop waveform when producing electric arc.
The application of electromagnetic induction is very general, can produce electromagnetic induction between two parallel wires.As shown in Figure 4, two parallel, isometric, adjacent leads are arranged, wherein their length is L, and spacing d has current i when following with stream in the middle of the lead.Then the voltage swing at O point place is:
V0=M*di/dt
Wherein,
M=u0/2[ln(2L/d)-1]
In patent documentation " arc-detection and protective device " (patent No. is CN02242313.3); proposed a kind of arc-detection and protective device, its main method is to protect by the difference that detects the voltage that produces owing to electric arc between A, B or C, the D at adding voltage exploration device between A, B or C, the D.The arc signal generation device of this method needs a transformer at least, has increased volume and the cost of circuit board.
Summary of the invention
The purpose of this utility model is for the problem of arc-detection and protection in the solution ccfl circuit, according to the principle that has electromagnetic induction between two parallel wires, provides a kind of cold-cathode fluorescence lamp arc-detection and protective circuit.
For achieving the above object, the utility model adopts following technical proposals:
A kind of cold-cathode fluorescence lamp arc-detection and protective circuit comprise that cold-cathode fluorescence lamp loop (1) connects cold-cathode fluorescence lamp (2) by connector (3), is characterized in that:
1) the CCFL power inverter control chip (5) in the described cold-cathode fluorescence lamp loop (1) connects an electric arc sampling and voltage comparator (4);
2) in long lead L1 in the described cold-cathode fluorescence lamp loop (1) and described electric arc sampling and the voltage comparator circuit (4) parallel with described long lead L1, close on, the lead L2 arcing sample detecting device of equal length.
Described electric arc sampling with the voltage comparator circuit structure is:
1) described lead L2 one end ground connection, the anode of a termination first rectifier diode D1;
2) negative electrode of first a rectifier diode D1 connects the in-phase end of a comparator U1, plays the effect of rectification;
3) first resistance R, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination plays the effect of discharge after arc fault is got rid of;
4) first capacitor C, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination plays the effect of voltage stabilizing;
5) second a clamp diode D2 anode connects simulation ground, and negative electrode connects the in-phase end of described comparator U1, clamper U1 in-phase end voltage, and U2 is not by high electrical breakdown in protection;
6) second resistance R 2 links to each other with the 3rd resistance R 3, described second resistance R, 2 another termination reference voltage REG, described the 3rd resistance R 3 connects simulation ground, and the tie point of second resistance R 2 and the 3rd resistance R 3 connects the backward end of described comparator U1, plays the effect that reference voltage is set;
7) output of a described comparator U1 of the 4th resistance R 4 one terminations, the output of termination electric arc sampling and voltage comparator circuit;
8) one the 5th single group R5 one termination reference voltage REG, termination electric arc sampling and voltage comparator circuit output.
The output of electric arc sampling and voltage comparator circuit is connected to CCFL power inverter control chip.When not having electric arc to produce in the cold-cathode fluorescence lamp loop, electric arc sampling and voltage comparator circuit output low level, CCFL power inverter control chip output signal makes CCFL power inverter operate as normal.When having electric arc to produce in the cold-cathode fluorescence lamp loop, electric arc sampling and voltage comparator circuit output high level, after CCFL power inverter control chip was accepted this high level, output signal made no longer output HIGH voltage of CCFL power inverter, till arc fault is got rid of.
The beneficial effect of the utility model patent is:
1, when having electric arc in the cold-cathode fluorescence lamp loop; this arc-detection and protective device can detect arc signal; and by electric arc sampling and voltage comparator circuit output high level signal; after CCFL power inverter control chip is accepted this high level; output signal makes no longer output HIGH voltage of CCFL power inverter, till arc fault is got rid of.
2, this cold-cathode fluorescence lamp arc-detection and protective circuit can effectively be protected CCFL fluorescent tube and power inverter;
3, this cold-cathode fluorescence lamp arc-detection and protective circuit, circuit is simple, easily realize, volume is little.
Description of drawings
Fig. 1 is the ccfl circuit principle;
Fig. 2 is the current waveform under the cold-cathode fluorescence lamp normal operation;
Current waveform when Fig. 3 produces electric arc for cold-cathode fluorescence lamp;
Fig. 4 is two parallel wire batteries induction schematic diagram;
The enlarged drawing of the current waveform when Fig. 5 produces electric arc for cold-cathode fluorescence lamp;
Fig. 6 is the utility model cold-cathode fluorescence lamp arc-detection and protective circuit schematic diagram one;
Fig. 7 is the utility model cold-cathode fluorescence lamp arc-detection and protective circuit schematic diagram two;
Fig. 8 is the circuit theory diagrams of electric arc sampling and voltage comparator circuit among Fig. 6 and Fig. 7;
Fig. 9 is the PCB layout schematic diagram of the utility model cold-cathode fluorescence lamp arc-detection and protective circuit.
Embodiment
Below in conjunction with accompanying drawing preferred embodiment of the present utility model is described in detail.
Embodiment one:
Referring to Fig. 6 and Fig. 7, a kind of cold-cathode fluorescence lamp arc-detection and protective circuit comprise that cold-cathode fluorescence lamp loop (1) connects cold-cathode fluorescence lamp (2) by connector (3), is characterized in that:
1) the CCFL power inverter control chip (5) in the described cold-cathode fluorescence lamp loop (1) connects an electric arc sampling and voltage comparator (4);
2) in long lead L1 in the described cold-cathode fluorescence lamp loop (1) and described electric arc sampling and the voltage comparator circuit (4) parallel with described long lead L1, close on, the lead L2 arcing sample detecting device of equal length.
Embodiment two:
Present embodiment and embodiment one are basic identical, and special feature is:
Referring to Fig. 8, described electric arc sampling with the voltage comparator circuit structure is:
1) described lead L2 one end ground connection, the anode of a termination first rectifier diode D1;
2) negative electrode of first a rectifier diode D1 connects the in-phase end of a comparator U1;
3) first resistance R, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination;
4) first capacitor C, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination;
5) second a clamp diode D2 anode connects simulation ground, and negative electrode connects the in-phase end of described comparator U1;
6) second resistance R 2 links to each other with the 3rd resistance R 3, described second resistance R, 2 another termination reference voltage REG, and described the 3rd resistance R 3 connects simulation ground, and the tie point of second resistance R 2 and the 3rd resistance R 3 connects the backward end of described comparator U1;
7) output of a described comparator U1 of the 4th resistance R 4 one terminations, the output of termination electric arc sampling and voltage comparator circuit;
8) one the 5th single group R5 one termination reference voltage REG, termination electric arc sampling and voltage comparator circuit output.
Embodiment three:
Fig. 6 is the utility model the 3rd embodiment cold-cathode fluorescence lamp major loop connection diagram, and it comprises the long lead L1 in electric arc detecting device, electric arc sampling and voltage comparator circuit, CCFL power inverter control chip, CCFL power inverter, step-up transformer, CCFL fluorescent tube, current feedback loop, voltage feedback loop and the cold-cathode fluorescence lamp loop.Control chip produces PWM ripple driving inverter and carries out the voltage inversion, and to the cold-cathode fluorescence lamp power supply, electric current, voltage feedback loop are controlled the voltage and current of the feasible output setting of duty ratio of PWM behind step-up transformer.
Embodiment four:
Fig. 7 is the utility model the 4th embodiment cold-cathode fluorescence lamp major loop connection diagram, and the long lead L1 in the cold-cathode fluorescence lamp loop not only can ground connection, also can be connected on any place in the loop, makes circuit design more convenient like this.
Fig. 8 is electric arc sampling and voltage comparator circuit.Electric arc sampling and voltage comparator circuit comprise the first rectifier diode D1, first resistance R 1, first capacitor C 1, the second clamper diode D2, second resistance R 2, the 3rd resistance R 3, the 4th resistance R 4, the 5th resistance R 5, comparator U1, with reference to supply power voltage REG, comparator supply power voltage VCC.
L2 one end ground connection, the anode of a termination first rectifier diode D1; The negative electrode of first rectifier diode connects the in-phase end of comparator U1, plays the effect of rectification; The first resistor R1, one termination simulation ground, the in-phase end of a termination comparator U1 plays the effect of discharge after arc fault is got rid of; First capacitor C, 1 one terminations simulation ground, the in-phase end of a termination comparator U1 plays the effect of voltage stabilizing; The second clamp diode D2 anode connects simulation ground, and negative electrode connects the in-phase end of comparator U1, clamper U1 in-phase end voltage, and U2 is not by high electrical breakdown in protection; Second resistance R 2 links to each other with the 3rd resistance R 3, second resistance R, 2 another termination reference voltage REG, and the 3rd resistance R 3 connects simulation ground, and the tie point of second resistance R 2 and the 3rd resistance R 3 connects the backward end of comparator, plays the effect that reference voltage is set; The output of the 4th resistance R 4 one termination comparator U1, the output of termination electric arc sampling and voltage comparator circuit; The 5th single group R5 one termination reference voltage REG, the output of termination electric arc sampling and voltage comparator circuit.
The output of electric arc sampling and voltage comparator circuit is connected to CCFL power inverter control chip.When not having electric arc to produce in the cold-cathode fluorescence lamp loop, electric arc sampling and voltage comparator circuit output low level, CCFL power inverter control chip output signal makes CCFL power inverter operate as normal.When having electric arc to produce in the cold-cathode fluorescence lamp loop, electric arc sampling and voltage comparator circuit output high level, after CCFL power inverter control chip was accepted this high level, output signal made no longer output HIGH voltage of CCFL power inverter, till arc fault is got rid of.
In the time of the cold-cathode fluorescence lamp operate as normal,
i=8.5sin
ωt(mA)
V=M*1.9cos
ωt(mV)
This moment the comparator in-phase end very little of voltage, much smaller than REG*R3/ (R3+R2), the output port output low level signal of electric arc sampling and voltage comparator circuit, circuit operate as normal.
When electric arc produces, the current waveform that produces in the cold-cathode fluorescence lamp loop as shown in Figure 5 because the frequency of electric arc is very high, and the value of its di/dt is very big:
di/dt=58.4mV/0.033us=1.752*10E6
V=M*di/dt=1.25V
The value of comparator in-phase end voltage ratio REG*R3/ this moment (R3+R2) is big, electric arc sampling and voltage comparator circuit output high level, after CCFL power inverter control chip was accepted this high level, output signal made no longer output HIGH voltage of CCFL power inverter, till arc fault is got rid of.
Fig. 9 is the PCB layout schematic diagram of the utility model cold-cathode fluorescence lamp arc-detection and protective circuit, and wherein the equal length of L1 and L2 is 14mm, spacing 0.29mm.
Claims (2)
1. a cold-cathode fluorescence lamp arc-detection and protective circuit comprise that cold-cathode fluorescence lamp loop (1) connects cold-cathode fluorescence lamp (2) by connector (3), is characterized in that:
1) the CCFL power inverter control chip (5) in the described cold-cathode fluorescence lamp loop (1) connects an electric arc sampling and voltage comparator (4);
2) in long lead L1 in the described cold-cathode fluorescence lamp loop (1) and described electric arc sampling and the voltage comparator circuit (4) parallel with described long lead L1, close on, the lead L2 arcing sample detecting device of equal length.
2. cold-cathode fluorescence lamp arc-detection according to claim 1 and protective circuit is characterized in that described electric arc sampling with the voltage comparator circuit structure is:
1) described lead L2 one end ground connection, the anode of a termination first rectifier diode D1;
2) negative electrode of first a rectifier diode D1 connects the in-phase end of a comparator U1;
3) first resistance R, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination;
4) first capacitor C, 1 one terminations simulation ground, the in-phase end of the described comparator U1 of a termination;
5) second a clamp diode D2 anode connects simulation ground, and negative electrode connects the in-phase end of described comparator U1;
6) second resistance R 2 links to each other with the 3rd resistance R 3, described second resistance R, 2 another termination reference voltage REG, and described the 3rd resistance R 3 connects simulation ground, and the tie point of second resistance R 2 and the 3rd resistance R 3 connects the backward end of described comparator U1;
7) output of a described comparator U1 of the 4th resistance R 4 one terminations, the output of termination electric arc sampling and voltage comparator circuit;
8) one the 5th single group R5 one termination reference voltage REG, termination electric arc sampling and voltage comparator circuit output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320007752 CN203072235U (en) | 2013-01-08 | 2013-01-08 | Arc detection and protection circuit for cold cathode fluorescence lamp (CCFL) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320007752 CN203072235U (en) | 2013-01-08 | 2013-01-08 | Arc detection and protection circuit for cold cathode fluorescence lamp (CCFL) |
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| Publication Number | Publication Date |
|---|---|
| CN203072235U true CN203072235U (en) | 2013-07-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201320007752 Expired - Fee Related CN203072235U (en) | 2013-01-08 | 2013-01-08 | Arc detection and protection circuit for cold cathode fluorescence lamp (CCFL) |
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| CN (1) | CN203072235U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110007181A (en) * | 2017-12-14 | 2019-07-12 | 塔莱斯公司 | Monitoring for the failure in electrical equipment |
-
2013
- 2013-01-08 CN CN 201320007752 patent/CN203072235U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110007181A (en) * | 2017-12-14 | 2019-07-12 | 塔莱斯公司 | Monitoring for the failure in electrical equipment |
| CN110007181B (en) * | 2017-12-14 | 2021-09-21 | 塔莱斯公司 | Monitoring for faults in electrical devices |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C53 | Correction of patent for invention or patent application | ||
| CB03 | Change of inventor or designer information |
Inventor after: Ji Weigui Inventor after: Ran Feng Inventor after: Tang Yingbin Inventor after: Ji Yuan Inventor after: Xu Meihua Inventor before: Ji Weigui Inventor before: Ran Feng Inventor before: Tang Yingbin Inventor before: Ji Yuan Inventor before: Xu Meihua |
|
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130717 Termination date: 20150108 |
|
| EXPY | Termination of patent right or utility model |