CN101541124B - Failure detection method of circuit with LCD screen backlight power supply structure - Google Patents
Failure detection method of circuit with LCD screen backlight power supply structure Download PDFInfo
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- CN101541124B CN101541124B CN200910105267.6A CN200910105267A CN101541124B CN 101541124 B CN101541124 B CN 101541124B CN 200910105267 A CN200910105267 A CN 200910105267A CN 101541124 B CN101541124 B CN 101541124B
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Abstract
The invention discloses a failure detection method with an LCD screen backlight power supply structure, which comprises a frequency modulation control IC, lamp loop current feedback, a detection loop of lamp failure electric parameters, a power converting loop and a lamp; the frequency modulation control IC generates lamp operating frequency, the frequency is used for stabilizing the current thereof according to the adjustment of the lamp loop current feedback, and simultaneously, the detection loop of lamp failure electric parameters samples the lamp loop electric parameters for failure judgment; the power converting loop works at the frequency generated by the frequency modulation control IC to complete the conversion of energy required when the lamp works. The invention adopts the method of sampling the variation value of electric parameters corresponding to the different operating conditions of frequency under two or a plurality of operating conditions of frequency for alternative judgment; in the specific application, the converter is led to be at another preset operating frequency regularly or irregularly by the instructions of the control loop, and the electric parameters (including voltage, current or the dispersion thereof) with sensitive change at the operating frequency are sampled and whether the electric parameters exceed the set value is judged, thus being capable of more accurately detecting the variation of the electric parameters which are difficult to be discriminated when the failure of weak electric arc occurs at the normal operating frequency; therefore, the accuracy of failure recognition is improved and the safety is greatly promoted.
Description
Technical field
The present invention relates to many lamps of CCFL power supply technique field, relate in particular to a kind of detection method that adopts series capacitance balanced balanced current multiple lamp LCD screen backlight power supply fault.
Background technology
When LCD screen adopts CCFL backlight power supply, due to the complicated negative resistance charactertistic of CCFL fluorescent tube, drive circuit must be that high impedance output coordinates with it, and conventional method is perhaps inductance (comprising the inductance existing with fabric drain inductive mode) of loop series electrical.As shown in Figure 1, a kind of typical loop series capacitance mode, from circuit theory and mathematical computations, during normal operation, series capacitance impedance will reach the more than approximately 1.5 times of tube impedance, could obtain good impedance neutralization, thus the impact of the complicated negative resistance charactertistic of reduction CCFL fluorescent tube on drive circuit, simultaneously for drive circuit of CCFL lamps common using provides good current balance type condition; But, after incident problem is series connection high impedance, the electric physical quantity intensity of variation that CCFL fluorescent tube fault case causes is also weakened, this situation is at drive circuit of CCFL lamps common using, particularly outstanding during the electric physical quantity of the minor loop after the detection of fault samples main drive circuit or part branch road and gathers, cause when there is the light current arc fault case that some electric leakage state, corona discharge and solder cracks etc. cause, testing circuit is not differentiated, poor stability.
Every CCFL fluorescent tube branch road of existing employing independently samples the mode detecting, and when its advantage is fault case, can accurately identify, and fail safe is good, and shortcoming is that cost is high, and circuit is complicated, is applicable to the few occasion of fluorescent tube number.Or detect the electric physical quantity of the minor loop after the main drive circuit of sampling or part branch road gather; its advantage is to have simplified circuit; be applicable to the occasion that fluorescent tube number is many; shortcoming is that what to detect reflection is the total amount after a plurality of fluorescent tube branch circuit parallel connections; after fluorescent tube number increases; while having the faults such as electric leakage state, corona discharge and light current arc when one of them branch road, the high impedance of series capacitance has reduced the reflection of fault-signal in test side, causes some fault secure circuit None-identifieds.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of LCD screen backlight power supply structural circuit fault detection method.
For solving the problems of the technologies described above, the object of the invention is to be achieved through the following technical solutions.
A screen backlight power supply structural circuit fault detection method, comprising: frequency modulation control IC, fluorescent tube loop current feedback, and fluorescent tube fault electric parameter detects loop, power converting loop and fluorescent tube; Described frequency modulation control IC produces lamp works frequency, and frequency is according to fluorescent tube loop current feedback adjusting to stablize its electric current, and meanwhile, described fluorescent tube fault electric parameter detects loop sampling lamp tube loop electric parameter for fault judgement; Under the frequency that described power converting loop works produces in frequency modulation control IC, complete the required power conversion of lamp works.
Wherein, during frequency modulation control IC work, can switch at two or more different design frequencies, between different frequencies, generally have twice or above difference.
Wherein, to be operated in that two or more different design frequencies switch can be regular or irregular to frequency modulation control IC.
Wherein, fluorescent tube fault electric parameter detects the sample variation of fluorescent tube loop electric parameter under different operating frequencies of loop, makes the fault occurring under normal working frequency can be because electric parameter changes sampled identification under high-frequency operation.
Wherein, described fluorescent tube can be extinguish state also can the specified state of lighting of right and wrong.
Above technical scheme can find out, the present invention has following beneficial effect:
The present invention has adopted under two or more frequency operating conditions of sampling, the variation value of the electric parameter under corresponding different frequency operating conditions is done and is supplemented judgement, in concrete application, by the instruction of control loop, allow converter and regularly or aperiodically enter predetermined another operating frequency of establishing, and the electric parameter that samples the sensitive under this operating frequency (comprises voltage, electric current or its residual quantity etc.) whether exceed that set point judges, the variation of the electric parameter of impalpable while there is weak arc fault can be detected more accurately under normal working frequency; Thereby improved Fault Identification precision, greatly improved fail safe.
Accompanying drawing explanation
Fig. 1 is existing LCD screen backlight power supply structure chart;
Fig. 2 is LCD screen backlight power supply structure chart of the present invention;
Fig. 3 is LCD screen backlight power supply structural circuit fault detection method flow chart of the present invention.
Embodiment
Core concept of the present invention is: the invention provides the initiatively method of fault inspection; pass through program setting; at regular intervals; make inverter be operated under another high operating frequency; utilize circuit theory that output impedance characteristic changes with frequency change and circuit working at the property difference of different resonance curve points; relatively improve Fault Identification precision, solved similar sealing-off protection problem.On the other hand, although inverter is not operated in a fixing state, as long as the inspection operating time is enough short, utilize lamp luminescence and eye ghost, after each physical quantity that sampling sets, return to immediately normal frequency, little on application impact.
For ease of the present invention is further understood, now describe the present invention by reference to the accompanying drawings.
The invention provides a kind of LCD screen backlight power supply structural circuit detects, comprise: frequency modulation control IC, CCFL loop current feedback, the CCFL fluorescent tube of CCFL loop fault (open circuit, short circuit or electric leakage etc.) electric parameter detection, power converting loop and employing series capacitance balanced balanced current; Described frequency modulation control IC produces CCFL lamp works frequency, normal frequency is generally 40KHz-60KHz, frequency according to CCFL loop current feedback adjusting to stablize its electric current, simultaneously, described detection loop sampling CCFL loop electric parameter (voltage, electric current or residual quantity etc.) is for fault judgement; The frequency that described power converting loop works produces in frequency modulation control IC, completes the required power conversion of CCFL lamp works, as shown in Figure 2.
Its testing process as shown in Figure 3; pass through program setting; at regular intervals; make inverter be operated under another high operating frequency; utilize circuit theory that output impedance characteristic changes with frequency change and circuit working at the property difference of different resonance curve points; relatively improve Fault Identification precision, solved similar sealing-off protection problem.
Different from other control IC operation mode, during described frequency modulation control IC normal operation, frequency (being generally 40KHz-60KHz) is except controlled CCFL loop current feedback, after a period of time, can jump to another frequency band setting (such as 120KHz), its objective is under setpoint frequency state, the CCFL loop electric parameter that provides testing circuit to sample corresponding, from electric circuit knowledge:
Condensance Zc=1/ (2 π * f*c);
F: operating frequency;
C: capacitance;
π：3.14159；
Visible operating frequency and the condensance Zc relation that is inversely proportional to, if operating frequency rises to the twice of primary frequency, impedance Z c is original 1/2, and the impact that the impedance loop causing because of series capacitance raises reduces, when there is fault (short circuit in CCFL loop, arcing or electric leakage etc.) time, by rational design, variable quantity when the relative normal frequency of electric parameter (voltage, electric current or residual quantity etc.) that detection loop samples is worked wants large, improve Fault Identification precision, greatly improved fail safe.Based on above analysis, frequency modulation control IC is designed at least discontinuous operation two sections of not close frequencies, such as, more than differing twice; While being wherein operated in the operating mode of high-frequency section, the physical phenomenon of utilizing loop series capacitance impedance to diminish, can detect under normal working frequency more accurately, the variation of the electric parameter of impalpable while there is weak arc fault.
Above a kind of LCD screen backlight power supply structural circuit fault detection method provided by the present invention is described in detail, applied specific case herein principle of the present invention and execution mode are set forth, the explanation of above embodiment is just for helping to understand method of the present invention and core concept thereof; , for one of ordinary skill in the art, according to thought of the present invention, all will change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention meanwhile.
Claims (5)
1. a LCD screen backlight power supply structural circuit fault detection method, comprising: frequency modulation control IC, fluorescent tube loop current feedback, the detection of fluorescent tube fault electric parameter loop, power converting loop and fluorescent tube; It is characterized in that, described frequency modulation control IC produces lamp works frequency, and frequency is according to fluorescent tube loop current feedback adjusting to stablize its electric current, and meanwhile, described fluorescent tube fault electric parameter detects loop sampling lamp tube loop electric parameter for fault judgement; Under the frequency that described power converting loop works produces in frequency modulation control IC, complete the required power conversion of lamp works; At regular intervals, make inverter be operated under another high operating frequency, after each physical quantity that sampling sets, return to immediately normal frequency.
2. LCD screen backlight power supply structural circuit fault detection method according to claim 1, is characterized in that, during frequency modulation control IC work, can switch at two or more different design frequencies, generally has twice or above difference between different frequencies.
3. LCD screen backlight power supply structural circuit fault detection method according to claim 2, is characterized in that, it can be regular or irregular that frequency modulation control IC is operated in two or more different design frequencies switchings.
4. LCD screen backlight power supply structural circuit fault detection method according to claim 1, it is characterized in that, fluorescent tube fault electric parameter detects the sample variation of fluorescent tube loop electric parameter under different operating frequencies of loop, makes the fault occurring under normal working frequency can be because electric parameter changes sampled identification under high-frequency operation.
5. LCD screen backlight power supply structural circuit fault detection method according to claim 1, is characterized in that, described fluorescent tube can be extinguish state also can the specified state of lighting of right and wrong.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910105267.6A CN101541124B (en) | 2009-01-24 | 2009-01-24 | Failure detection method of circuit with LCD screen backlight power supply structure |
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| Application Number | Priority Date | Filing Date | Title |
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| CN200910105267.6A CN101541124B (en) | 2009-01-24 | 2009-01-24 | Failure detection method of circuit with LCD screen backlight power supply structure |
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| CN101541124A CN101541124A (en) | 2009-09-23 |
| CN101541124B true CN101541124B (en) | 2014-01-29 |
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| CN103475204B (en) * | 2013-08-31 | 2016-05-18 | 西北工业大学 | Bear thermal stress by adjustment element and realize the method that LED power failure is evaded |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1387394A (en) * | 2001-05-22 | 2002-12-25 | 国碁电子股份有限公司 | Drive system of fluorescent lamp and fluorescent lamp system using it |
| EP1189488B1 (en) * | 2000-09-15 | 2004-04-07 | TridonicAtco GmbH & Co. KG | Electronic self-calibrating ballast and method for calibrating a ballast |
| CN1856201A (en) * | 2005-04-26 | 2006-11-01 | 美国芯源系统股份有限公司 | HF power device for driving discharge lamp and frequency setting method thereof |
| US7339321B2 (en) * | 2005-01-17 | 2008-03-04 | Valeo Vision | Discharge-lamp ballast in particular for a vehicle headlight |
| CN101155454A (en) * | 2006-09-30 | 2008-04-02 | 唯冠科技（深圳）有限公司 | Multi-light tube current control method and driving circuit thereof |
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2009
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1189488B1 (en) * | 2000-09-15 | 2004-04-07 | TridonicAtco GmbH & Co. KG | Electronic self-calibrating ballast and method for calibrating a ballast |
| CN1387394A (en) * | 2001-05-22 | 2002-12-25 | 国碁电子股份有限公司 | Drive system of fluorescent lamp and fluorescent lamp system using it |
| US7339321B2 (en) * | 2005-01-17 | 2008-03-04 | Valeo Vision | Discharge-lamp ballast in particular for a vehicle headlight |
| CN1856201A (en) * | 2005-04-26 | 2006-11-01 | 美国芯源系统股份有限公司 | HF power device for driving discharge lamp and frequency setting method thereof |
| CN101155454A (en) * | 2006-09-30 | 2008-04-02 | 唯冠科技（深圳）有限公司 | Multi-light tube current control method and driving circuit thereof |
Non-Patent Citations (1)
| Title |
|---|
| JP特开2008-166290A 2008.07.17 |
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Address after: 518057, Shenzhen science and technology zone, Guangdong, Nanshan District Province, 13 North Road, Thunis Road, 5, A;B;C501-C503;D;E Applicant after: Shenzhen Megmeet Electrical Co., Ltd. Address before: 1804, room 6006, Huafeng building, No. 518053 Shennan Road, Guangdong, Shenzhen Applicant before: Shenzhen Megmeet Electrical Co., Ltd. |
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