CN201438775U - Piezoelectric resonant high voltage lighting circuit - Google Patents

Abstract

A piezoelectric resonance high-voltage lighting circuit utilizes the capacitance characteristic existing in the piezoelectric transformer as the piezoelectric capacitance, connects the piezoelectric transformer connected on the lamp tube with the independent inductance in series, makes it form the resonance series or parallel lighting circuit, achieves the effects of small leakage current, low temperature and high pressure resistance, helps the lighting efficiency to improve by a wide margin, moreover, the utility model discloses an utilize step-up transformer to further amplify the output in the voltage output terminal, by means of providing the characteristic of high brightness output; when the utility model discloses be applied to the drive of many fluorescent tubes, it is that usable fixed frequency makes the internal resistance value fixed in piezoelectric capacitor's the equivalent circuit, can make the electric current in each fluorescent tube of circulation unanimous, and produces the balanced effect of many fluorescent tubes electric current.

Description

Piezoelectric resonant high voltage lighting circuit

technical field

The utility model relates to a resonant lighting circuit, in particular to a piezoelectric resonant high-voltage lighting circuit using independent inductors in series or in parallel with piezoelectric transformers.

Background technique

The luminescence principle of Cold Cathode Fluorescent Lamp (CCFL) is similar to that of ordinary fluorescent lamps. Its luminescence principle is that when high voltage is input from the electrode end, a small number of electron molecules in the tube hit the electrode at high speed, and secondary electron emission is generated at this time. When the discharge starts, electrons collide with mercury atoms, and the mercury atoms are excited to radiate 253.7nm ultraviolet light. The ultraviolet light excites the phosphor powder coated on the tube wall to produce visible light with relative color temperature. In addition to being widely used in monitors, personal digital assistants, digital cameras and mobile phones, it is also one of the indispensable backlight materials for liquid crystal displays.

However, due to the gradual expansion of the application of the liquid crystal display, its size has gradually increased, so the number of cold cathode lamps used in the backlight must also increase accordingly, in order to maintain the same or higher brightness. Based on the requirements of uniform brightness distribution and extended lamp life, the absolute value and relative difference of the lamp current must be strictly controlled. A commonly used multi-lamp module is to use a traditional coil-type step-up transformer connected in parallel to the lamp tubes. Its disadvantages are that the efficiency is not high, and the withstand voltage of the coil is insufficient, and it is easy to break down due to high voltage, resulting in It is extremely dangerous to burn out in a short circuit. Another type of multi-lamp module structure, as shown in FIG. 1 , the current difference between the lamp tubes 100 is compensated by the capacitor 110 connected in series to the high-voltage end of the lamp tubes 100, which will cause a large leakage current. , the efficiency is not high, and the voltage resistance of the capacitor 110 is insufficient, the failure mode will be that the capacitor 110 explodes, which easily leads to the danger of fire.

On the other hand, since the use of U-shaped lamps for the backlight can reduce the use of lamps and inverters, U-shaped lamps have been widely used based on cost considerations. However, the voltage and voltage of U-shaped lamps at the bend The current will be partially lost, and it needs to provide enough voltage to achieve the same luminous efficiency as the long lamp. Therefore, seeking a high-voltage lighting circuit that can improve lighting efficiency and achieve tube current balance is an important topic that the industry attaches great importance to at present.

Contents of the invention

In view of the above problems, the main purpose of this utility model is to provide a piezoelectric resonant high-voltage lighting circuit, which utilizes the capacitance characteristics of the piezoelectric transformer itself as a piezoelectric capacitor to form the resonance of the inductance series or parallel piezoelectric transformers. The lighting circuit can meet the needs of low leakage, high lighting efficiency and current balance, and a step-up transformer is added to the voltage output end to amplify the output voltage, making it easier to start the lamp with high voltage.

Another object of the present invention is to provide a piezoelectric resonant high-voltage lighting circuit. The piezoelectric transformer replaces the capacitor or coil type step-up transformer in the traditional lighting circuit. It is not only small in size, but also has superior electrical performance. It can avoid the danger of failure and overheating caused by insufficient pressure resistance, and its reliability is high, which has a very competitive advantage in the market.

Another object of the present invention is to provide a piezoelectric resonant high-voltage lighting circuit, which can reduce the length of the circuit and simplify the size of the final product by using a series connection.

In order to achieve the above purpose, the piezoelectric resonant high-voltage lighting circuit disclosed in the utility model is to apply the high-power piezoelectric ceramic oscillator originally used in the ultrasonic oscillator to the ballast and converter of the resonant lighting circuit. As a piezoelectric capacitor, this resonant lighting circuit has the characteristic that the boost ratio will vary with the internal impedance of the load, which is very suitable for driving the lamp. When the lamp has not been started, it can be equivalent to an open circuit state. At this time, the resonant lighting circuit can provide a high boost ratio to start the lamp instantly; when the lamp is started, the equivalent impedance value drops, and the circuit boost ratio It will also drop accordingly, so that the normal operation of the lamp is in a steady state.

In order to be suitable for high-current and high-brightness lighting requirements, the utility model uses a step-up transformer to boost the output voltage to the required voltage, and the boosted voltage is provided to both ends of each lamp tube, which improves the utilization rate of electric energy. In order to provide the characteristics of high luminance output, and can provide low start-up time, so it can better protect the lamp tube.

At the same time, the utility model can be applied to the current balance of multiple lamp tubes. The internal impedance value in the equivalent circuit of the piezoelectric capacitor is fixed through the fixed frequency to form a fixed current through the lamp tube. When the piezoelectric capacitor on the series lamp tube and the When the electrical characteristics of piezoelectric capacitors on other lamp tubes are similar, their internal impedance values are similar, so that the current in each lamp tube is consistent, and the tube current balance is achieved.

In addition, the utility model combines piezoelectric capacitors with independent inductors to form a resonant lighting circuit structure, which is suitable for dual high-voltage lighting under full-bridge circuits. Of course, it is also suitable for single-voltage lighting under half-bridge circuits.

In order to have a further understanding of the purpose, features and functions of the present utility model, hereby cooperate with the drawings to describe in detail as follows:

Description of drawings

Fig. 1 is a prior art multi-lamp module using general capacitors;

Fig. 2A is the piezoelectric resonant high-voltage lighting circuit provided by the embodiment of the present invention, in which the piezoelectric capacitor is connected in series with the resonant inductor;

Fig. 2B is the piezoelectric resonant high-voltage lighting circuit provided by the embodiment of the present invention, in which the piezoelectric capacitor is connected in parallel with the resonant inductance;

Fig. 3 is the assembly structure of the piezoelectric capacitor provided by the embodiment of the present invention;

Figures 4A and 4B are piezoelectric resonant high-voltage lighting circuits with full-bridge output provided by the embodiment of the present invention;

5A and 5B are schematic diagrams of the piezoelectric resonant high-voltage lighting circuit used in the external electrode fluorescent lamp panel of the embodiment of the present invention;

6A and 6B are schematic diagrams of piezoelectric resonant high-voltage lighting circuits used in light-emitting diodes according to embodiments of the present invention;

7A and 7B are schematic diagrams of piezoelectric resonant high-voltage lighting circuits used in energy-saving light bulbs according to embodiments of the present invention;

8A and 8B are the full-bridge input piezoelectric resonant high-voltage lighting circuits provided by the embodiment of the present invention;

9A and 9B are piezoelectric resonant high-voltage lighting circuits with half-bridge input provided by the embodiment of the present invention; and

Fig. 10 is an equivalent circuit of the piezoelectric capacitor provided by the embodiment of the present invention.

In the picture:

10 piezoelectric capacitors

11 piezoelectric substrate

12 conductive layer

13 conductive layer

20 piezoelectric capacitors

30 cold cathode lamps

40 resonant inductance

41 resonant inductance

50 auxiliary capacitor

51 auxiliary capacitor

60 resonant inductance

61 resonant inductance

70 External Electrode Fluorescent Lamp Panel

80 LEDs

90 energy-saving light bulbs

100 tubes

110 capacitor

200 double high voltage input piezoelectric resonant high voltage lighting circuit

300 single high voltage input piezoelectric resonant high voltage lighting circuit

500 step-up transformer

Detailed ways

Please refer to FIG. 2A , which is a schematic diagram of the piezoelectric resonant high-voltage lighting circuit provided by the embodiment of the present invention. It mainly includes multiple sets of cold-cathode lamps 30 connected in series between two auxiliary capacitors 50 and 51. Each A group of cold cathode lamp tubes 30 are connected in parallel with each other, and are connected in series with the resonant inductor 40 and the piezoelectric capacitor 10 through the coupling of the step-up transformer 500 . This piezoelectric resonant high-voltage lighting circuit uses the capacitive characteristics of the piezoelectric transformer itself as the piezoelectric capacitor 10, and is connected in series with the resonant inductor 40 to form a resonant lighting circuit of an inductance series piezoelectric transformer, which can be adjusted by adjusting the resonance The inductance 40 and the capacitance value of the piezoelectric transformer achieve the function of boosting the voltage to light the lamp. At the same time, the output voltage can be increased to the required voltage by using the characteristic of the boosting transformer 500 for output amplification, and the boosted voltage is provided to the The two ends of the cold cathode lamp tube 30 meet the requirement of high brightness output, make it easier to start the lamp tube under high voltage, and can provide a short start-up time, which can better protect the lamp tube.

The piezoelectric capacitor 10 disclosed in this embodiment, as shown in FIG. Copper paste or nickel paste are used to form circular conductive layers 12 and 13 on the entire or part of the upper and lower surfaces of the piezoelectric substrate 11 to form the two poles of the piezoelectric capacitor 10 to guide current. Here, please refer to FIG. 10 , which is an equivalent circuit of a piezoelectric capacitor 10; the equivalent circuit shows an equivalent resistance R, an equivalent inductance L, and equivalent capacitances Cb and Ca representing mechanical properties and electrical properties, respectively. . Different from general capacitors or coil-type step-up transformers, the piezoelectric capacitor 10 of this embodiment has small leakage current, high pressure resistance, no danger of overheating and fire, high reliability, and can also provide multiplied output power , so that the lighting efficiency is greatly improved; secondly, due to the small size of the piezoelectric capacitor and the thin package thickness, and the configuration of connecting the resonant inductor, piezoelectric capacitor and the lamp tube in series, the overall line length can be reduced, making the final product Dimensions are reduced.

In this embodiment, the piezoelectric capacitor 10 is connected in series with the resonant inductor 40, but it is not limited to this in practice. As shown in FIG. The use of series connection can maintain a lower temperature and produce less loss. In addition, the auxiliary capacitors 50 and 51 can also be piezoelectric capacitors. In addition to the function of starting, the capacitance value can be adjusted to fine-tune the output current and optimize the output power. When the light is turned on, the voltage will rise instantly, and after the light is turned on, the internal impedance of the load will become smaller, and the step-up ratio will drop, so the output will be adjusted to reduce additional power consumption.

Moreover, the piezoelectric resonant high-voltage lighting circuit of the piezoelectric transformer in series with the inductor can effectively maintain the balance of the tube current; when the input pulse voltage source is converted to AC to drive the circuit, the piezoelectric capacitor will increase the low voltage to the required level for lighting the tube. Due to the difference in the impedance characteristics of the lamp tube, the inconsistency of the lamp current will cause uneven brightness of the backlight and reduce the life of the lamp tube. Therefore, the utility model uses a fixed frequency to drive the resonant lighting circuit, so that the equivalent circuit of the piezoelectric capacitor The impedance value is fixed, and a fixed current is formed to pass through the lamp tube. When the electrical characteristics of the piezoelectric capacitor on the series lamp tube and the piezoelectric capacitor on other lamp tubes are close, the internal impedance value is close, so that each lamp tube The current is consistent, in other words, the function of achieving multi-lamp current balance.

In the above-mentioned embodiment, each lamp tube 30 is matched with a piezoelectric capacitor 10 and a resonant inductor 40 to form a half-bridge resonant circuit, which can reduce production cost and has the advantage of price competition. Of course, if two resonant inductors 40 and 60 are used to form a full-bridge resonant circuit, higher power output can be promoted, as shown in FIGS. 4A and 4B . 4A is an embodiment in which two resonant inductors 40 and 60 are connected in parallel with a piezoelectric capacitor 10 , and FIG. 4B is an embodiment in which two resonant inductors 40 and 60 are connected in series with two piezoelectric capacitors 10 and 20 respectively.

In addition, the utility model can be applied to single high-intensity discharge lamps (HID), negative metal lamps, ceramic fluorescent lamps (CPFL), cold cathode lamps (CCFL), external electrode fluorescent lamps (EEFL), energy-saving bulbs or light emitting Diodes (LEDs) are also suitable for parallel connection of multiple cold-cathode lamps, external electrode fluorescent lamp panels, energy-saving bulbs or light-emitting diodes. Please refer to Fig. 5A, 5B, Fig. 6A, 6B and Fig. 7A, 7B, respectively depicting the piezoelectric resonant high-voltage lighting circuit of the present utility model used in the external electrode fluorescent lamp board 70 (or high-intensity discharge lamp (HID), negative Metal lamp, ceramic fluorescent lamp (CPFL)), light-emitting diode 80 and energy-saving light bulb 90, two resonant inductors 40, 60 can be connected in parallel with one piezoelectric capacitor 10, or can also be connected with two piezoelectric capacitors 10, 20 in series. Certainly, the structure thereof can be a half-bridge or a full-bridge resonant circuit.

Furthermore, the utility model is also applicable to large-sized backlight panels (such as above 42 o'clock), and large-size backlight panels often need to install long lamp tubes (such as lamp tubes with a length of more than 1m), and the capacitance loss rate in the lamp tubes Large, it is easy to cause differences in the brightness of the lamps. At this time, each lamp needs an individual independent resonant inductor and piezoelectric capacitor to balance the capacitance. Please refer to Figs. 8A, 8B and Figs. 9A and 9B, respectively taking piezoelectric resonant high voltage lighting circuits 200 and 300 with double high voltage (full bridge) and single high voltage (half bridge) input as examples, and each lamp tube 30 is connected in series. Between two auxiliary capacitors 50, 51 and two resonant inductors 41, 61 (see Fig. 8A, 8B), or each lamp tube 30 is connected in series with an auxiliary capacitor 10 and a resonant inductor 41 respectively, Then be connected in parallel (see Figure 9A, 9B). Certainly, the utility model is more particularly suitable for U-shaped lamp tubes, so as to provide high-brightness output, make it easier to start the lamp tubes with high voltage, and provide low start-up time to prolong the service life of the lamp tubes.

Although the present invention is disclosed above with the aforementioned embodiments, it is not intended to limit the present invention. Without departing from the spirit and scope of the utility model, all changes and modifications made belong to the patent protection scope of the utility model. For the scope of protection defined by the utility model, please refer to the appended scope of patent application.

Claims (12)

1. piezoelectric type resonance high-voltage lamp circuit includes:

One piezoelectric capacitance is to comprise a piezoelectricity base material and two conductive layers, and this piezoelectricity base material has upper surface and lower surface, and this two conductive layer is formed at the upper surface and the lower surface of this piezoelectricity base material respectively, and constitutes the two poles of the earth of this piezoelectric capacitance;

One resonant inductance, serial or parallel connection is in this piezoelectric capacitance; And

One step-up transformer is electrically coupled to this piezoelectric capacitance and a fluorescent tube, gives this fluorescent tube so that higher voltage to be provided.

2. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, wherein the number of this resonant inductance is two.

3. according to 2 described piezoelectric type resonance high-voltage lamp circuits of claim the, wherein this two resonant inductance is in parallel with this piezoelectric capacitance, or connects with this piezoelectric capacitance respectively.

4. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, wherein this fluorescent tube is the high-intensity discharge lamp for single, negative metalized lamp, ceramic fluorescent lamp pipe, cold cathode fluorescent lamp, external electrode fluorescent lamp plate, Electricity-saving lamp bulb or light-emitting diode.

5. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, wherein this fluorescent tube is many high-intensity discharge lamps for parallel connection, negative metalized lamp, ceramic fluorescent lamp pipe, cold cathode fluorescent lamp, external electrode fluorescent lamp plate, Electricity-saving lamp bulb or light-emitting diode.

6. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, more comprise an auxiliary capacitor, be series at this fluorescent tube.

7. according to 6 described piezoelectric type resonance high-voltage lamp circuits of claim the, wherein this auxiliary capacitor is to be another piezoelectric capacitance.

8. according to 6 described piezoelectric type resonance high-voltage lamp circuits of claim the, wherein the number of this auxiliary capacitor is two, and this fluorescent tube is to be series between this two auxiliary capacitor.

9. according to 8 described piezoelectric type resonance high-voltage lamp circuits of claim the, these two auxiliary capacitors resonant inductance of connecting respectively wherein.

10. according to 6 described piezoelectric type resonance high-voltage lamp circuits of claim the, wherein those fluorescent tubes are connect respectively an auxiliary capacitor and a resonant inductance.

11. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, wherein this piezoelectricity base material and this two conductive layer are to be circle, this two conductive layer is formed at the upper surface and the lower surface of the whole of this piezoelectricity base material or part respectively.

12. according to 1 described piezoelectric type resonance high-voltage lamp circuit of claim the, wherein this two conductive layer is formed by elargol, copper cream or nickel cream.

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