CN102097063B - LCD backlight power source and television - Google Patents
LCD backlight power source and television Download PDFInfo
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- CN102097063B CN102097063B CN 200910188923 CN200910188923A CN102097063B CN 102097063 B CN102097063 B CN 102097063B CN 200910188923 CN200910188923 CN 200910188923 CN 200910188923 A CN200910188923 A CN 200910188923A CN 102097063 B CN102097063 B CN 102097063B
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- 239000003990 capacitor Substances 0.000 claims abstract description 15
- 230000001105 regulatory effect Effects 0.000 claims description 10
- 239000004973 liquid crystal related substance Substances 0.000 abstract 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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Abstract
The invention relates to a liquid crystal display (LCD) backlight power source and a television. The LCD backlight power source comprises a pulse-width modulation (PWM) controller and a current adjustment circuit connected in parallel with a resistor R4; the resistor R4 and a capacitor C1 are sequentially connected between an RT pin and a CT pin of the PWM controller; the connecting nodes of the resistor R4 and the capacitor C1 are grounded; the current adjustment circuit comprises resistors R1, R2 and R3, a switch tube Q1 and a sawtooth wave generator, wherein the switch tube Q1 and the resistor R3 are sequentially connected with each other and connected in parallel between both ends of the resistor R4; and the control end of the switch tube Q1 is coupled with the output end of the sawtooth wave generator through a voltage division circuit composed of the resistor R1 and the resistor R2. By the circuit structure, the frequency of the PWM controller can be changed, so the PWM controller can shake within a proper range, and an electromagnetic interference conductance test is improved.
Description
Technical field
The present invention relates to backlight electric power, more particularly, relate to a kind of LCD backlight electric power and televisor.
Background technology
Existing backlight electric power all adopts the mode of fixed frequency to control when work.In test EMI(electromagnetic interference (EMI)) when conducting, the higher harmonic components energy of switching frequency is too concentrated.Comparatively difficult by international standard.
Summary of the invention
The technical problem to be solved in the present invention is, the frequency of controlling for the PWM of the LCD backlight electric power of prior art only can be fixed the defective of setting, and a kind of LCD backlight electric power and televisor are provided.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of LCD backlight electric power, it comprises the PWM controller, be connected with in turn resistance R 4 and capacitor C 1 between the RT of described PWM controller pin and CT pin, the connected node ground connection of described resistance R 4 and capacitor C 1 also comprises the current regulating circuit in parallel with described resistance R 4; Described current regulating circuit comprises: resistance R 1, R2, R3, switching tube Q1 and saw-toothed wave generator;
Wherein, switching tube Q1 is connected with resistance R in turn and is connected in parallel on resistance R 4 two ends after connecting, and the bleeder circuit that the control end of switching tube Q1 consists of by resistance R 1 and R2 is coupled to the output terminal of described saw-toothed wave generator;
One end of described resistance R 2 is connected with the output terminal of described saw-toothed wave generator, and the other end of resistance R 2 is connected with the control end of described switching tube Q1 and is connected with an end of resistance R 1, the other end ground connection of resistance R 1.
In LCD backlight electric power of the present invention, described switching tube Q1 is triode, and the base stage of this triode is coupled to described saw-toothed wave generator, and emitter is connected with described resistance R 3, and collector coupled is to the RT pin of described PWM controller.
According to another aspect of the present invention, a kind of LCD televisor is provided, it comprises the LCD backlight electric power, described LCD backlight electric power comprises the PWM controller, be connected with in turn resistance R 4 and capacitor C 1 between the RT of described PWM controller pin and CT pin, the connected node ground connection of described resistance R 4 and capacitor C 1 also comprises the current regulating circuit in parallel with described resistance R 4; Described current regulating circuit comprises: resistance R 1, R2, R3, switching tube Q1 and saw-toothed wave generator;
Wherein, switching tube Q1 is connected with resistance R in turn and is connected in parallel on resistance R 4 two ends after connecting, and the bleeder circuit that the control end of switching tube Q1 consists of by resistance R 1 and R2 is coupled to the output terminal of described saw-toothed wave generator;
One end of described resistance R 2 is connected with the output terminal of described saw-toothed wave generator, and the other end of resistance R 2 is connected with the control end of described switching tube Q1 and is connected with an end of resistance R 1, the other end ground connection of resistance R 1.
In LCD televisor of the present invention, described switching tube Q1 is triode, and the base stage of this triode is coupled to described saw-toothed wave generator, and emitter is connected with described resistance R 3, and collector coupled is to the RT pin of described PWM controller.
Implement LCD backlight electric power of the present invention and televisor, have following beneficial effect: change the frequency of PWM controller device, make in a suitable scope and shake, improve the EMI conduction test.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples, in accompanying drawing:
Fig. 1 is the circuit theory diagrams of LCD televisor one embodiment of the present invention.
Embodiment
As shown in Figure 1, in an embodiment of LCD televisor of the present invention, because improvement for the LCD televisor in technical scheme of the present invention only is LCD backlight electric power part, especially be the set of frequency to PWM controller 1, the remaining circuit structure is not improved, thus at this only in part relevant to the PWM controller this illustrate.
As shown in Figure 1, be connected with in turn resistance R 4 and capacitor C 1 between the RT of PWM controller 1 pin and CT pin, the connected node ground connection of described resistance R 4 and capacitor C 1, wherein, resistance R 4 and capacitor C 1 consist of the frequency setting circuit 4 of PWM controller, the i.e. frequency f of PWM controller
s=0.6/ (C1 * R4).Innovative point of the present invention is, at the current regulating circuit 2 of the two ends of resistance R 4 parallel connection, with change the RT pin that flows out PWM controller 1 electric current, thereby make the frequency of PWM controller 1 to change in a controlled scope.
In a preferred embodiment, this current regulating circuit 2 comprises: resistance R 1, R2, R3, switching tube Q1 and saw-toothed wave generator 3; Wherein, switching tube Q1 is connected with resistance R in turn and is connected in parallel on resistance R 4 two ends after connecting, and the bleeder circuit that the control end of switching tube Q1 consists of by resistance R 1 and R2 is coupled to the output terminal of described saw-toothed wave generator.One end of described resistance R 2 is connected with the output terminal of described saw-toothed wave generator 3, and the other end of resistance R 2 is connected with the control end of described switching tube Q1 and is connected with an end of resistance R 1, the other end ground connection of resistance R 1.When specific design, this switching tube Q1 can be triode, and the base stage of this triode is coupled to described saw-toothed wave generator 3, and emitter is connected with described resistance R 3, and collector coupled is to the RT pin of described PWM controller.
At work, the charging current in capacitor C 1 can by the electric current setting of the RT pin that flows out PWM controller 1, change the frequency that the electric current that flows out the RT pin can change the PWM controller.In a preferred embodiment, it is 125HZ that saw-toothed wave generator 3 has produced a frequency, and amplitude is the sawtooth wave of 3V, after the bleeder circuit of this signal through resistance R 1 and R2 composition, drives triode Q1.Flow through triode Q1 base current I1 by change, thereby change Q1 collector current I2, and then to have changed outflow RT pin electric current I 4(VRT be reference voltage 5V).The concrete derivation of equation is as follows:
I1=K*Vin (1) K is scale factor
I2=β*I1 （2）
I3=VRT/R4 （3）
I4=I2+I3=β*(Vin*R2/R1-Vbe)/R3+VRT/R4（4）
By formula (4) as can be known, I3 is the electric current that flows through resistance R 4, and the charging current of capacitor C 1 changes with the change of sawtooth wave output voltage V IN, thereby the frequency of PWM controller changes along with sawtooth wave output voltage V IN and shake, and the frequency of shake is 125HZ.
The present invention describes by several specific embodiments, it will be appreciated by those skilled in the art that, without departing from the present invention, can also carry out various conversion and be equal to alternative the present invention.In addition, for particular condition or concrete condition, can make various modifications to the present invention, and not depart from the scope of the present invention.Therefore, the present invention is not limited to disclosed specific embodiment, and should comprise the whole embodiments that fall in claim scope of the present invention.
Claims (4)
1. LCD backlight electric power, comprise the PWM controller, be connected with in turn resistance R 4 and capacitor C 1 between the RT of described PWM controller pin and CT pin, the connected node ground connection of described resistance R 4 and capacitor C 1, it is characterized in that, also comprise the current regulating circuit in parallel with described resistance R 4; Described current regulating circuit comprises: resistance R 1, R2, R3, switching tube Q1 and saw-toothed wave generator;
Wherein, switching tube Q1 is connected with resistance R in turn and is connected in parallel on resistance R 4 two ends after connecting, and the bleeder circuit that the control end of switching tube Q1 consists of by resistance R 1 and R2 is coupled to the output terminal of described saw-toothed wave generator;
One end of described resistance R 2 is connected with the output terminal of described saw-toothed wave generator, and the other end of resistance R 2 is connected with the control end of described switching tube Q1 and is connected with an end of resistance R 1, the other end ground connection of resistance R 1.
2. LCD backlight electric power according to claim 1, it is characterized in that, described switching tube Q1 is triode, and the base stage of this triode is coupled to described saw-toothed wave generator, emitter is connected with described resistance R 3, and collector coupled is to the RT pin of described PWM controller.
3. LCD televisor, comprise the LCD backlight electric power, described LCD backlight electric power comprises the PWM controller, be connected with in turn resistance R 4 and capacitor C 1 between the RT of described PWM controller pin and CT pin, the connected node ground connection of described resistance R 4 and capacitor C 1, it is characterized in that, also comprise the current regulating circuit in parallel with described resistance R 4; Described current regulating circuit comprises: resistance R 1, R2, R3, switching tube Q1 and saw-toothed wave generator;
Wherein, switching tube Q1 is connected with resistance R in turn and is connected in parallel on resistance R 4 two ends after connecting, and the bleeder circuit that the control end of switching tube Q1 consists of by resistance R 1 and R2 is coupled to the output terminal of described saw-toothed wave generator;
One end of described resistance R 2 is connected with the output terminal of described saw-toothed wave generator, and the other end of resistance R 2 is connected with the control end of described switching tube Q1 and is connected with an end of resistance R 1, the other end ground connection of resistance R 1.
4. LCD televisor according to claim 3, is characterized in that, described switching tube Q1 is triode, and the base stage of this triode is coupled to described saw-toothed wave generator, and emitter is connected with described resistance R 3, and collector coupled is to the RT pin of described PWM controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910188923 CN102097063B (en) | 2009-12-14 | 2009-12-14 | LCD backlight power source and television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910188923 CN102097063B (en) | 2009-12-14 | 2009-12-14 | LCD backlight power source and television |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102097063A CN102097063A (en) | 2011-06-15 |
| CN102097063B true CN102097063B (en) | 2013-11-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 200910188923 Expired - Fee Related CN102097063B (en) | 2009-12-14 | 2009-12-14 | LCD backlight power source and television |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105048798B (en) * | 2015-07-17 | 2018-01-09 | 许继电源有限公司 | A kind of frequency jitter circuit and Switching Power Supply |
| CN105610316A (en) * | 2015-08-14 | 2016-05-25 | 许继电源有限公司 | Frequency jittering circuit |
Citations (3)
| 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 |
| CN1906841A (en) * | 2004-01-27 | 2007-01-31 | 罗姆股份有限公司 | DC-AC converter, controller IC therefor, and electronic apparatus utilizing the DC-AC converter |
| CN101048932A (en) * | 2004-11-12 | 2007-10-03 | 罗姆股份有限公司 | Direct-current-to-alternating current converter, controller IC therefor, and parallel operation system for direct-current-to-alternating current converter |
-
2009
- 2009-12-14 CN CN 200910188923 patent/CN102097063B/en not_active Expired - Fee Related
Patent Citations (3)
| 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 |
| CN1906841A (en) * | 2004-01-27 | 2007-01-31 | 罗姆股份有限公司 | DC-AC converter, controller IC therefor, and electronic apparatus utilizing the DC-AC converter |
| CN101048932A (en) * | 2004-11-12 | 2007-10-03 | 罗姆股份有限公司 | Direct-current-to-alternating current converter, controller IC therefor, and parallel operation system for direct-current-to-alternating current converter |
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| CN102097063A (en) | 2011-06-15 |
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Granted publication date: 20131106 Termination date: 20181214 |