CN202145377U - Piezoelectric transformer drive circuit - Google Patents
Piezoelectric transformer drive circuit Download PDFInfo
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- CN202145377U CN202145377U CN201120125354U CN201120125354U CN202145377U CN 202145377 U CN202145377 U CN 202145377U CN 201120125354 U CN201120125354 U CN 201120125354U CN 201120125354 U CN201120125354 U CN 201120125354U CN 202145377 U CN202145377 U CN 202145377U
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- piezoelectric transformer
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Abstract
The utility model provides a piezoelectric transformer drive circuit for cold cathode tubes, which comprises an input voltage module, a power level module, a resonance circuit, a piezoelectric transformer group and a florescence lamp group and is characterized in that the input voltage module is connected with the power level module and used for supplying the power level module with input direct current voltage; the power level module is connected with the resonance circuit, square wave signals generated by the power level module are converted into sine wave signals by the resonance circuit, the sine wave signals are supplied to piezoelectric transformers, and two adjacent piezoelectric transformers are used for driving one florescence lamp; and terminals at the primary side of the piezoelectric transformer group are connected in series.
Description
Technical field
The utility model relates to driving device of cold-cathod fluorescent lamp, and more specifically, the utility model relates to a kind of circuit for driving piezoelectric transformer that is used for the LCD TV cold-cathode tube.
Background technology
In recent years, be equipped with in the display device of LCD, back light generally uses cold-cathode tube, uses the step-up transformer of piezoelectric transformer as the cold-cathode tube that drives backlight usually.Piezoelectric transformer is such voltage conversion elements: the primary side input alternating voltage to piezoelectric element utilizes piezoelectric effect to produce mechanical vibration, exports the driven after the step-up ratio of confirming with the shape of piezoelectric transformer is carried out voltage amplification from primary side.
In using the driving circuit of cold-cathode tube as the cold-cathode tube TRT of the load of piezoelectric transformer; Piezoelectric transformer is at the electrode that in piezoelectric, forms primary side (primary side) and primary side (secondary side); High-tension frequency to be lower than interchange intermittently loads high voltage; Through controlling during the loading action in this intermitten and the ratio that loads the action stopping period, adjust the briliancy of cold-cathode tube.
In the backlight module design of LCD TV cold-cathode tube (CCFL); High frequency inverter is main with the traditional electrical magnetic type transformer still; But along with LCD TV constantly increases in the slimming of terminal market and energy-conservation demand voice, it is quite important that the development and Design of LCD TV backlight module seems.Piezoelectric ceramic transformer has that volume is little, in light weight, conversion efficiency is high, high-insulativity, high security, if can apply in the transverter line design, for the slimming of LCD TV and energy-conservation, with having suitable benefiting.
Fig. 1 illustrates a kind of circuit for driving piezoelectric transformer of the prior art, wherein piezoelectric transformer parallel connection, and each output terminal is lighted corresponding cold-cathode tube respectively, because differing greatly of piezoelectric transformer is easy to generate the situation of current imbalance.And in LCD TV; When using a plurality of CCFL to be connected each CCFL as the backlight of liquid crystal panel and with piezoelectric transformer; Only if the size of current of the kinescope of feasible each CCFL that flows through is impartial, otherwise will cause the unevenness of lumen backlight, use special control circuit to insert each piezoelectric transformer usually in the prior art; Control the output current of each piezoelectric transformer; Increase the cost that circuit brings extraly, and cause the power attenuation of other circuit and make decrease in efficiency, and manufacturing cost raises and microminiaturized difficulty improves.
The utility model content
For overcoming above-mentioned defective of the prior art, the utility model proposes a kind of circuit for driving piezoelectric transformer that is used for the LCD TV cold-cathode tube.
An aspect according to the utility model; A kind of circuit for driving piezoelectric transformer that is used for cold-cathode tube has been proposed; Comprise: input voltage module, power level module, resonant circuit, piezoelectric transformer group and fluorescent light group; It is characterized in that the input voltage module links to each other with the power level module, be used for DC voltage supply power level module input; Power level module resonant circuit is connected; The square-wave signal that the power level module produces converts string ripple signal to through resonant circuit; Offer piezoelectric transformer, two adjacent piezoelectric transformers are used to drive a fluorescent light, a side series connection of several piezoelectric transformers of piezoelectric transformer group; The terminal series connection of the primary side of piezoelectric transformer group, the power level module is the full bridge structure circuit.
Resonant circuit comprises the Inductive component and the capacitance component of series connection.
The disjunct end of one end of Inductive component and capacitance component is connected respectively to full-bridge circuit; The end that Inductive component links to each other with capacitance component is connected to the first terminal of the primary side of first piezoelectric transformer, and the other end of capacitance component connects second terminal of the primary side of lowermost end piezoelectric transformer.
The number of turns of each piezoelectric transformer is than identical in the piezoelectric transformer group.
Circuit for driving piezoelectric transformer also comprises pwm chip, and the terminal of the lowermost end primary side of piezoelectric transformer is connected to pwm chip, and pwm chip is adjusted the electric current input of full bridge structure according to feedback result.Also comprise the on-off circuit that pwm chip is external, come the adjustment of Control current.
Piezoelectric transformer adopts piezoelectric ceramic transformer.
First output terminal of full-bridge circuit is connected to the input end of the Inductive component of resonant circuit; Second output terminal of full-bridge circuit is connected to the other end of capacitance component; The terminal of the primary side of piezoelectric transformer is connected to an input end of fluorescent light, another terminal ground connection.
When backlight module adopts the design of multitube cold-cathode tube; Owing to have a little otherness between each fluorescent tube; Make actual flow cross lamp tube current and produce unequal phenomenon; Cause the inconsistent problem of backlight module brightness, the utility model utilizes piezoelectric transformer tandem drive circuit, can improve lamp tube current balance property problem.Because lamp current and optical brightness correlate, so not only in the full uniformity coefficient that can reach electric current when bright, more the current balance type property is better when light modulation, backlightly is not easy to produce scintillation.
Description of drawings
Fig. 1 illustrates parallel piezoelectric transformer drive circuit of the prior art;
Fig. 2 illustrates the logic module figure according to the circuit for driving piezoelectric transformer of first embodiment of the utility model;
Fig. 3 illustrates the circuit for driving piezoelectric transformer according to second embodiment of the utility model;
Fig. 4 illustrates the waveform synoptic diagram of circuit shown in Figure 3:
Fig. 5 illustrates the logic module figure according to the circuit for driving piezoelectric transformer of the 3rd embodiment of the utility model;
Fig. 6 illustrates the logical circuitry of circuit module shown in Figure 5;
Fig. 7 illustrates the circuit theory diagrams of the full-bridge circuit resonant circuit among first embodiment and the 3rd embodiment;
Fig. 8 illustrates the sequential chart of circuit shown in Figure 7;
Fig. 9 illustrates the detailed circuit schematic diagram of circuit shown in Figure 6.
As shown in the figure; In order clearly to realize the structure of the embodiment of the utility model, marked specific structure and device in the drawings, but this is merely the signal needs; Be not that intention is limited to the utility model in this ad hoc structure, device and the environment; According to concrete needs, those of ordinary skill in the art can adjust these devices and environment or revise, and adjustment of being carried out or modification still are included in the scope of accompanying Claim.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment a kind of circuit for driving piezoelectric transformer that is used for the LCD TV cold-cathode tube that the utility model provides is described in detail.
In the following description, with a plurality of different aspect of describing the utility model, yet, for the one of ordinary skilled in the art, can only utilize some or the entire infrastructure of the utility model or flow process to implement the utility model.For the definition of explaining, set forth specific number, configuration and order, but clearly, do not had also can to implement the utility model under the situation of these specific detail.In other cases, in order not obscure the utility model, will set forth no longer in detail for some well-known characteristics.
Embodiment 1
Fig. 2 illustrates the logic module figure according to the circuit for driving piezoelectric transformer of first embodiment of the utility model; As shown in Figure 2, this driving circuit comprises input voltage module, power level module, piezoelectric transformer group, fluorescent light group, pwm chip and on-off circuit.Wherein, the input voltage module links to each other with the power level module, is used for the DC voltage supply power level module with input.Wherein, the power level module is the full bridge structure circuit.Wherein, the power level module links to each other with the piezoelectric transformer group, and two adjacent piezoelectric transformers are used to drive a fluorescent light.Wherein, the series connection of the terminal of the primary side of piezoelectric transformer group, the terminal of lowermost end is connected to pwm chip, and pwm chip is adjusted the electric current input of full bridge structure according to feedback result.Wherein, the external circuit that cut-offs of pwm chip, the adjustment of Control current.
Further, as shown in Figure 2, with a side series connection of several piezoelectric transformers; Be example wherein with first and second transformers; The elementary terminal of this first transformer is respectively 1a and 1b, and secondary terminal is 1c, and the elementary terminal of second voltage is respectively 2a and 2b; Secondary terminal is 2c; Then the output terminal of full-bridge circuit connects the 1a terminal of first transformer and the nb terminal of n transformer respectively, and the 1b terminal of first transformer is connected to the 2a terminal of second transformer, and the 1c terminal of first transformer and second transformer and 2c terminal are connected respectively to the two ends of fluorescent light.Thereby make the flow through electric current of piezoelectric transformer primary side to equate, wherein, because the number of turns of selected piezoelectric transformer is than identical, so the output current of piezoelectric transformer secondary side is also identical, thus brightness that can each fluorescent light of active balance.
Wherein, Piezoelectric transformer is selected piezoelectric ceramic transformer for use; This piezoelectric ceramic transformer has that volume is little, in light weight, conversion efficiency is high, the advantage of high-insulativity, high security (nonflammable); Can apply in the transverter line design, for the slimming of LCD TV and energy-conservation, with having suitable benefit.
Fig. 3 illustrates the circuit for driving piezoelectric transformer according to second embodiment of the utility model; To similarly partly omit with Fig. 2 among Fig. 3; Simultaneously referring to figs. 2 and 3, the circuit for driving piezoelectric transformer of second embodiment comprises that this driving circuit comprises input voltage module, power level module, piezoelectric transformer group, fluorescent light group, pwm chip, resonant circuit and on-off circuit.Wherein, the input voltage module links to each other with the power level module, is used for the DC voltage supply power level module with input.Wherein, the power level module is the full bridge structure circuit.Wherein, power level module resonant circuit is connected, and full-bridge circuit switches the generation square-wave signal, and square-wave signal converts string ripple signal to through resonant circuit, and string ripple signal offers piezoelectric transformer.Resonant circuit comprises the Inductive component and the capacitance component of series connection, a plurality of piezoelectric transformer parallel connections of piezoelectric transformer group.The disjunct end of one end of Inductive component and capacitance component is connected respectively to full-bridge circuit; The end that Inductive component links to each other with capacitance component is connected the first terminal of the primary side of piezoelectric transformer group respectively, and the other end of capacitance component connects second terminal of the primary side of piezoelectric transformer respectively.
Each piezoelectric transformer is used to drive a fluorescent light, and the primary side of piezoelectric transformer connects the input end of fluorescent light, the other end ground connection of fluorescent light.Wherein, the first terminal of the primary side of piezoelectric transformer group all is connected to the link of Inductive component and capacitance component.Second terminal of the primary side of piezoelectric transformer group all is connected to the other end of capacitance component.
The other end of capacitance component is connected to pwm chip, and pwm chip is adjusted the electric current input of full bridge structure according to feedback result.Wherein, the external circuit that cut-offs of pwm chip, the adjustment of Control current.
Wherein, Piezoelectric transformer is selected piezoelectric ceramic transformer for use; This piezoelectric ceramic transformer has that volume is little, in light weight, conversion efficiency is high, the advantage of high-insulativity, high security (nonflammable); Can apply in the transverter line design, for the slimming of LCD TV and energy-conservation, with having suitable benefit.The environmental protection characteristic of piezoelectric ceramic transformer meets two megatrend now of Chinese flat panel TV industry: the energy conservation standard of brand value/competitive power, export markets.
Fig. 4 illustrates the waveform synoptic diagram of circuit shown in Figure 3, and is as shown in Figure 4, full-bridge circuit output square wave; Through the resonant circuit module in Fig. 3 driving circuit; Convert the string ripple into, this string ripple is input to fluorescent light after through piezoelectric transformer and comes driving fluorescent lamp, still is stable string ripple.Wherein, If piezoelectric transformer is the input square-wave signal; With might be because wherein high-frequency harmonic composition or impact signal, cause the piezoelectric transformer temperature to rise rapidly and produce overheatedly, and then cause the piezoelectric transformer conversion efficiency to descend; So piezoelectric transformer input string ripple signal can improve conversion efficiency.The energy conservation criteria in Europe is evolved to EPA 4.0 by EPA 3.0, because its standard is higher than the U.S., and string ripple drive voltage circuit can improve piezoelectric transformer efficient, will make more environmental protection of product.
Embodiment 3
Fig. 5 illustrates the logic module figure according to the circuit for driving piezoelectric transformer of the 3rd embodiment of the utility model; As shown in Figure 5, this driving circuit comprises input voltage module, power level module, resonant circuit, piezoelectric transformer group, fluorescent light group, pwm chip and on-off circuit.
Wherein, the input voltage module links to each other with the power level module, is used for the DC voltage supply power level module with input.Wherein, the power level module is the full bridge structure circuit.Wherein, power level module resonant circuit is connected, and full-bridge circuit switches the generation square-wave signal, and square-wave signal converts string ripple signal to through resonant circuit, and string ripple signal offers piezoelectric transformer.Two adjacent piezoelectric transformers are used to drive a fluorescent light.Wherein, the series connection of the terminal of the primary side of piezoelectric transformer group, the terminal of lowermost end is connected to pwm chip, and pwm chip is adjusted the electric current input of full bridge structure according to feedback result.Wherein, the external circuit that cut-offs of pwm chip, the adjustment of Control current.
Further, as shown in Figure 5, with a side series connection of several piezoelectric transformers; Be example wherein with first and second transformers; The elementary terminal of this first transformer is respectively 1a and 1b, and secondary terminal is 1c, and the elementary terminal of second voltage is respectively 2a and 2b; Secondary terminal is 2c; Then the output terminal of resonant circuit connects the 1a terminal of first transformer and the nb terminal of n transformer respectively, and the 1b terminal of first transformer is connected to the 2a terminal of second transformer, and the 1c terminal of first transformer and second transformer and 2c terminal are connected respectively to the two ends of fluorescent light.Thereby make the flow through electric current of piezoelectric transformer primary side to equate, wherein, because the number of turns of selected piezoelectric transformer is than identical, so the output current of piezoelectric transformer secondary side is also identical, thus brightness that can each fluorescent light of active balance.
Resonant circuit comprises the Inductive component and the capacitance component of series connection.The disjunct end of one end of Inductive component and capacitance component is connected respectively to full-bridge circuit; The end that Inductive component links to each other with capacitance component is connected to the first terminal of the primary side of first piezoelectric transformer, and the other end of capacitance component is to second terminal of the primary side that connects the lowermost end piezoelectric transformer.
Wherein, Piezoelectric transformer is selected piezoelectric ceramic transformer for use; This piezoelectric ceramic transformer has that volume is little, in light weight, conversion efficiency is high, the advantage of high-insulativity, high security (nonflammable); Can apply in the transverter line design, for the slimming of LCD TV and energy-conservation, with having suitable benefit.The environmental protection characteristic of piezoelectric ceramic transformer meets two megatrend now of Chinese flat panel TV industry: the energy conservation standard of brand value/competitive power, export markets.
Wherein, full-bridge circuit output square wave, the resonant circuit through in Fig. 5 driving circuit converts the string ripple into, and this string ripple is input to fluorescent light after through piezoelectric transformer and comes driving fluorescent lamp, still is stable string ripple.Wherein, If piezoelectric transformer is the input square-wave signal; With might be because wherein high-frequency harmonic composition or impact signal, cause the piezoelectric transformer temperature to rise rapidly and produce overheatedly, and then cause the piezoelectric transformer conversion efficiency to descend; So piezoelectric transformer input string ripple signal can improve conversion efficiency.The energy conservation criteria in Europe is evolved to EPA 4.0 by EPA 3.0, because its standard is higher than the U.S., and string ripple drive voltage circuit can improve piezoelectric transformer efficient, will make more environmental protection of product.
Fig. 6 illustrates the logical circuitry of circuit module shown in Figure 5; As shown in Figure 6, first output terminal of full-bridge circuit is connected to the input end of the Inductive component of resonant circuit, and second output terminal of full-bridge circuit is connected to the other end of capacitance component, and the electric current through Inductive component is i
p, this electric current is given each piezoelectric transformer T1, T2......Tn by mean allocation, and the terminal of the primary side of piezoelectric transformer is connected to an input end of fluorescent light, another terminal ground connection.
Fig. 7 illustrates the circuit theory diagrams of the full-bridge circuit resonant circuit among first embodiment and the 3rd embodiment, with identical shown in Fig. 6, among Fig. 7 this two parts circuit is listed separately, clearly to distinguish the composition of annexation and each circuit.Shown in describe in detail above connecting and forming, repeat no more here.
Fig. 8 illustrates the sequential chart of circuit shown in Figure 7; Corresponding to the voltage signal of each node among Fig. 7, can find out that the voltage Vab that the input end at resonant circuit clearly illustrates is a square-wave signal, when square-wave signal through behind the resonant circuit, be output as string ripple signal Vo at the two ends of capacitance component.
Fig. 9 illustrates the detailed circuit schematic diagram of circuit shown in Figure 6, and upper left illustrates the input voltage module among the figure, and the rear end is connected with denoising electric capacity.The bottom of input voltage module is a full-bridge circuit; Be resonant circuit again, right half part is the circuit that a piezoelectric transformer and fluorescent lamp element are shown, and is clear and definite with the concrete annexation of piezoelectric transformer group of parallel connection for series connection certainly as stated, need not to illustrate a plurality of to obscure the circuit composition.Circuit shown in Fig. 9 is merely a concrete realization of above-mentioned module and logical circuit, and those skilled in the art can realize a plurality of such circuit according to above-mentioned teachings.
What should explain at last is; Above embodiment only limits in order to the technical scheme of description the utility model rather than to the present technique method; The utility model can extend to other modification, variation, application and embodiment on using, and therefore thinks that all such modifications, variation, application, embodiment are in the spirit and teachings of the utility model.
Claims (8)
1. circuit for driving piezoelectric transformer that is used for cold-cathode tube; Comprise: input voltage module, power level module, resonant circuit, piezoelectric transformer group and fluorescent light group; It is characterized in that; The input voltage module links to each other with the power level module, is used for the DC voltage supply power level module with input; Power level module resonant circuit is connected; The square-wave signal that the power level module produces converts string ripple signal to through resonant circuit; Offer piezoelectric transformer, two adjacent piezoelectric transformers are used to drive a fluorescent light, a side series connection of several piezoelectric transformers of piezoelectric transformer group; The terminal series connection of the primary side of piezoelectric transformer group, the power level module is the full bridge structure circuit.
2. circuit for driving piezoelectric transformer according to claim 1 is characterized in that, resonant circuit comprises the Inductive component and the capacitance component of series connection.
3. circuit for driving piezoelectric transformer according to claim 2; It is characterized in that; The disjunct end of one end of Inductive component and capacitance component is connected respectively to full-bridge circuit; The end that Inductive component links to each other with capacitance component is connected to the first terminal of the primary side of first piezoelectric transformer, and the other end of capacitance component connects second terminal of the primary side of lowermost end piezoelectric transformer.
4. circuit for driving piezoelectric transformer according to claim 1 is characterized in that the number of turns of each piezoelectric transformer is than identical in the piezoelectric transformer group.
5. circuit for driving piezoelectric transformer according to claim 1; It is characterized in that; Also comprise pwm chip, the terminal of the lowermost end primary side of piezoelectric transformer is connected to pwm chip, and pwm chip is adjusted the electric current input of full bridge structure according to feedback result.
6. circuit for driving piezoelectric transformer according to claim 5 is characterized in that, also comprises the on-off circuit that pwm chip is external, comes the adjustment of Control current.
7. circuit for driving piezoelectric transformer according to claim 1 is characterized in that, piezoelectric transformer adopts piezoelectric ceramic transformer.
8. circuit for driving piezoelectric transformer according to claim 6; It is characterized in that; First output terminal of full-bridge circuit is connected to the input end of the Inductive component of resonant circuit; Second output terminal of full-bridge circuit is connected to the other end of capacitance component, and the terminal of the primary side of piezoelectric transformer is connected to an input end of fluorescent light, another terminal ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120125354U CN202145377U (en) | 2011-04-26 | 2011-04-26 | Piezoelectric transformer drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120125354U CN202145377U (en) | 2011-04-26 | 2011-04-26 | Piezoelectric transformer drive circuit |
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| Publication Number | Publication Date |
|---|---|
| CN202145377U true CN202145377U (en) | 2012-02-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201120125354U Expired - Lifetime CN202145377U (en) | 2011-04-26 | 2011-04-26 | Piezoelectric transformer drive circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102760413A (en) * | 2011-04-26 | 2012-10-31 | 佛山市南海平板显示技术中心 | Piezoelectric transformer drive circuit |
-
2011
- 2011-04-26 CN CN201120125354U patent/CN202145377U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102760413A (en) * | 2011-04-26 | 2012-10-31 | 佛山市南海平板显示技术中心 | Piezoelectric transformer drive circuit |
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Legal Events
| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120215 |