KR20030018220A - High efficiency piezoelectric ballast with a piezoelectric coupler - Google Patents

Abstract

PURPOSE: A high efficiency piezo-electric ballast is provided to allow piezo-electric ceramics to be applied to the ballast for fluorescent lamp and high voltage discharge lamp, while eliminating the necessity of a soft start circuit. CONSTITUTION: A high efficiency piezo-electric ballast comprises an over-current and over-voltage protection element; a power factor improvement circuit connected to an AC power source including an EMI prevention circuit; a rectifier connected to the power factor improvement circuit; a pulse generator for receiving signals from an input power and generating a frequency; a switching frequency setting circuit for setting the frequency; two field effect transistors for switching an AC voltage output from the rectifier in accordance with the pulse generated from the pulse generator; an inductor(1) connected between a discharge lamp and a common output of the two field effect transistors; and a piezo-electric coupler(5) connected in parallel to the discharge lamp.

Description

High efficiency piezoelectric ballast with a piezoelectric coupler

The present invention relates to a high-efficiency piezoelectric stabilizer using a piezoelectric coupler, and more particularly, to a high-efficiency piezoelectric stabilizer that applies piezoceramic to a ballast for fluorescent and high-pressure discharge lamps, but does not require a preheating lamp and a soft start circuit.

Unlike incandescent lamps using commercial power sources of 50 to 60 hertz (Hz), fluorescent lamps operate at 10 kilohertz (kHz) or higher using a ballast that has a built-in inverter that can generate high frequency, high efficiency, high life, and low power consumption. Type lighting fixtures. Conventional electronic ballasts for fluorescent lamps use winding type transformers by electromagnetic induction method, and are stabilizers of cathode preheating type with various supplementary circuits for improving performance and lifespan.The current for preheating the cathode filament It starts to light up and adds soft start function to prevent sudden high voltage discharge.

Electronic ballasts using winding type transformers by electromagnetic induction have disadvantages such as large size and low efficiency. Therefore, in order to solve this drawback, there have been attempts to light a discharge lamp using ceramics such as piezoelectric bodies. U.S. Patents 4,858,066 and 4,447,549 show that the discharge lamp can be turned on by using the nonlinear response of ceramic capacitance due to the nonlinear field-polarization effect of the ferroelectric, but does not include a ballast for practical use. The focus is on the material properties to take advantage of the hysteresis characteristics, and the actual driving frequency is very high. In addition, since the polarization is continuously inverted at high frequency, there is a high possibility that the lifetime problem may be caused by the distribution fatigue phenomenon of the ceramics used.

On the other hand, US Patent No. 6,034,484 relates to a piezoelectric ballast that can light a fluorescent lamp by acting as a piezoelectric resonator by polarizing the ferroelectric and then connected to the inductor, unlike the patent. The piezoelectric material used herein has various shapes, and the piezoelectric material is connected in parallel to the fluorescent lamp and connected in series to the negative electrode filament to have a preheating function. In addition, it includes connecting a plurality of piezoelectric resonators in parallel to extend the use of the driving frequency range.

According to the invention of the ballast using the ceramic element, the material's constant electric field is small enough to obtain a nonlinear capacitance change even in a commercial power supply, or to connect a plurality of piezoelectric resonators to widen the driving frequency, and each resonator has an accurate resonance frequency. There is a problem that only works, and because there was no measure against the problem that the piezoelectric element driven at the resonance frequency at no load could be destroyed by excessive current, it was not implemented as a complete ballast.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a reliable ballast by replacing such a function with a piezoelectric coupler without including a preheating and soft start circuit of a general ballast.

Another object of the present invention is to provide a high-efficiency piezoelectric ballast having high power efficiency and light efficiency that solves the above-mentioned disadvantages of the nonlinear ferroelectric capacitor or piezoelectric resonator.

Still another object of the present invention is a piezoelectric stabilizer capable of stably driving a discharge lamp such as a U-shaped PL lamp, a compact lamp with a ballast, or a fluorescent lamp, a high-pressure sodium lamp, as well as a general straight fluorescent lamp having a different diameter. To provide. In particular, in the case of a high-pressure sodium lamp ballast, by supplying sufficient discharge voltage by the piezoelectric coupler, there is no need for an ignition circuit for initial lighting. In addition to eliminating this, it is possible to provide a compact and lightweight ballast.

It is still another object of the present invention to select a instantaneous lighting method that does not use a filament of a fluorescent lamp in order to manufacture a high-efficiency ballast. The size can be adjusted using a driving frequency and a general capacitor, and the driving frequency is removed from the main resonance frequency to have a soft start function, thereby eliminating the shortening of life, which is a disadvantage of the instantaneous lighting method.

Another object of the present invention is to change the driving frequency is extremely small even at high temperature (~ 130 ℃) to apply the piezoelectric coupler to the ballast can be stably driven, as well as the non-resonant point of the piezoelectric coupler according to the discharge, etc. To provide a ballast designed for normal operation in

1A and 1B show electric field-polarization hysteresis curves for piezoelectric ceramics used in the present invention, in which FIG. 1A is measured under bipolar voltage and FIG. 1B under unipolar voltage.

2 is a schematic diagram showing a connection method of a piezoelectric coupler, a discharge lamp, and an inductor designed for manufacturing the piezoelectric ballast of the present invention.

3A is a graph showing a change in resonant frequency according to a change in inductance of an inductor in FIG. 2, and FIG. 3B is a graph of impedance change at an induced resonant frequency.

4 is an overall circuit diagram of a piezoelectric stabilizer for a fluorescent lamp and a high-pressure discharge lamp with a piezoelectric coupler according to the present invention.

5 shows the magnitude of the initial discharge voltage and whether the discharge lamp is turned on according to the frequency band of the piezoelectric ballast including the piezoelectric coupler (C = 2.3nF) according to the present invention.

Figure 6 shows the magnitude of the initial discharge voltage according to the frequency band of the piezoelectric ballast including the piezoelectric coupler (C = 2.5nF) according to the present invention and whether the discharge lamp is lit.

Figure 7 shows the change in voltage and current with time when the fluorescent lamp lighting by the piezoelectric ballast according to the present invention.

8 shows the illuminance change of the ballast according to the temperature change of the piezoelectric coupler according to the present invention.

The present invention provides a high efficiency piezoelectric ballast which does not require a preheating lamp and a soft start circuit to achieve the above object. In addition to piezoelectric ceramics, piezoelectric stabilizers include circuit configurations throughout the ballast, such as no-load and overload protection, power factor correction and noise filters. In addition, an inductor for achieving LC resonance and impedance matching with a piezoelectric ballast is used as a piezoelectric stabilizer. The inductor is an instantaneous lighting method driven in series with a piezoelectric element connected in parallel with a fluorescent lamp shorting a cathode filament. Therefore, energy can be saved by eliminating the preheating current flowing in the filament and reducing the exothermic temperature generated in the filament.

Since the piezoelectric element included in the piezoelectric stabilizer is combined with a frequency inverter to serve as a high efficiency stabilizer, the piezoelectric used in the present invention is called a piezoelectric coupler. The piezoelectric coupler serves as a nonlinear capacitor in which the high voltage generator discharges the initial high voltage when the discharge lamp is turned on, the resonator makes resonance with the inductor, and the capacitance of the piezoelectric body changes nonlinearly by the input voltage. The driving frequency bandwidth is determined by the characteristics of the piezoelectric coupler and impedance matching with the inductor.

In general, the application of the piezoelectric element is driven at the resonant frequency induced as described above, but in the present invention, the soft start function is achieved by driving at the non-resonant frequency band deviated by at least 5 kHz or more from the induced resonant frequency in order to extend the life of the discharge lamp. I had it. Therefore, the piezoelectric stabilizer of the instantaneous lighting method according to the present invention replaces this function with a piezoelectric coupler without providing a preheating lighting and a soft start circuit, thereby providing a reliable ballast.

The piezoelectric coupler used in the present invention was prepared by polarizing a single layer piezoelectric material of various compositions in the thickness direction. At this time, the capacitance of the piezoelectric body was used by adjusting the area of the electrode and the distance between the electrodes as in the general capacitor. The piezoelectric ceramics included in the present invention were used by selecting a material semi-permanently stable in polarization state under a commercial power supply (100 to 240 V). The resonant frequency of the piezoelectric coupler is largely dependent on the size of the device, and in the case of a disc, the resonant frequency of the piezoelectric coupler is increased to several hundred kHz as the diameter decreases. By adjusting and driving the non-resonant point, the fluorescent lamp can be driven normally, so that the fluorescent lamp can be driven in a frequency band (20 to 90 kHz) that can maximize the efficiency of the fluorescent lamp.

A piezoelectric stabilizer for a discharge lamp may be manufactured using the piezoelectric coupler and a corresponding driving circuit. The piezoelectric stabilizer for a fluorescent lamp according to the present invention may include an overcurrent and overvoltage protection device and an EMI (electromagnetic interference) prevention circuit. An alternating current power supply and a power factor correction circuit connected thereto, a rectifier connected thereto, a pulse generator and a switching frequency setting circuit for generating a constant frequency by receiving a signal from an input power supply, and two electric fields for switching the output alternating voltage from the rectifier. An effect transistor, a piezoelectric coupler and a discharge lamp of a parallel connection connected in series with an inductor connected thereto, and a reset circuit connected to a pulse generator for resetting the pulse generator when an overload or no load occurs.

Here, the reset circuit is connected to a secondary winding formed to face an inductor to detect an abnormal current under overload or no load from a fluorescent lamp, a zener diode for detecting an abnormal voltage connected to the secondary winding, and a signal input from a zener diode. A silicon controlled rectifier is operated. The piezoelectric stabilizer can be commonly applied to both fluorescent lamps and high-pressure discharge lamps, because the initial lighting voltage generated in the piezoelectric coupler is automatically adjusted according to the type of load, that is, the discharge lamp.

Such a piezoelectric ballast for discharge lamp of the present invention can adjust the output by the capacitance of the piezoelectric coupler, it can not only minimize the size, but also there is no anisotropy of polarization, it is driven by a commercial power supply lower than the polarization field of polarization The fatigue phenomenon can be minimized, and the frequency range that can be used is greatly enlarged by driving at the non-resonant point of the piezoelectric coupler. By using the impedance difference with the discharge lamp efficiently, the high efficiency piezoelectric stabilizer of the instantaneous lighting method can be manufactured.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a measurement of the electric field-polarization hysteresis curve for the piezoelectric coupler used in the present invention. In general, the size of the residual polarization and the electric field is different according to the composition of the piezoelectric body, and the overall piezoelectric characteristics are greatly changed. In the present invention, the piezoceramic composition was selected in consideration of the magnitude and temperature stability of the voltage generated for the initial lighting.

FIG. 1A is a hysteresis curve under a bipolar voltage, and FIG. 1B is a characteristic under a unipolar voltage. Since the piezoelectric coupler used in the present invention is polarized, the commercial input voltage 100 to 240 V is smoothed by a rectifier in a state in which the polarization is aligned in one direction as shown in FIG. The signal of the square wave is transmitted to the inductor so that the initial high discharge voltage is induced by the resonance induced during the piezoelectric coupling period with the inductor. The peak value of the generated voltage varies depending on the load, but a voltage of about 500 to 1,500 V is induced for a commercial fluorescent lamp, and an initial lighting voltage of about 3,000 V is generated for a high-voltage discharge lamp. This generated voltage is caused by a piezoelectric coupler and an inductor whose polarization amount changes rapidly nonlinearly according to the voltage applied as shown in the circled portion of FIG. 1 (b), and the voltage is applied to the discharge lamp and the piezoelectric coupler connected in parallel with each other. At the same time, after the discharge lamp is turned on and the discharge lamp is turned on, after a predetermined time has elapsed, the constant tube voltage and tube current required for the discharge lamp are maintained.

Figure 2 schematically shows a part of the ballast using the piezoelectric coupler used in the present invention. In order to limit the current flowing through the filament, the cathode filament 3 of the fluorescent lamp 2 is short-circuited and connected in parallel with the piezoelectric coupler 5, and then connected in series with the inductor 1 at the front end. Adopted. The reason is that the initial preheating current flows through the cathode filament 3 of the fluorescent lamp, and since a certain amount of current flows even after the lighting, a part of the current flowing through the fluorescent lamp is consumed in the filament, thereby reducing the power efficiency and thus the light efficiency. Done.

At this time, since the initial lighting voltage of the discharge lamp used varies greatly depending on the type of the lamp, the voltage of the discharge lamp can be prevented from being applied to the discharge lamp by connecting and dividing the capacitor 4 in series with the lamp (2) as necessary. .

Even when a ceramic capacitor having a high breakdown voltage is used instead of the piezoelectric ceramics used in the present invention, the discharge lamp is normally turned on by LC resonance, but the initial discharge is not shown because it does not show a sudden change in capacitance as shown in the piezoelectric coupler of FIG. Not only the peak voltage is small but also the heat generation is very large and power loss occurs, resulting in a decrease in efficiency.

3A and 3B illustrate correlations between inductance and resonance frequency of the inductor 1 and impedance at inductance and resonance frequency used for efficient operation and impedance matching of the resonance circuit described with reference to FIG. 2. In general, for LC resonators As shown in the table of FIG. 3A, the resonance frequency decreases as the inductance increases, and the impedance at the resonance frequency generated by the piezoelectric coupler and the inductor tends to saturate at an inductance of about 2 mH or more. . Therefore, the inductor matched to the piezoelectric coupler used in the present invention is preferably at least 2mH that the impedance is saturated and the driving frequency is stabilized. However, the capacitance can be adjusted according to the piezoceramic composition, so it is possible to find an effective matching point even at a lower inductance value.

The resonance frequency shown at 0 mH in FIG. 3A is a resonance frequency of the piezoelectric coupler itself and varies with the diameter of the device. However, the resonance frequency can be reduced to 100 kHz or less by matching the piezoelectric coupler and the inductor. In addition, since the frequency bandwidth that can be driven is enlarged by using a non-resonant frequency other than the main resonance frequency, it is possible to select and operate a frequency range having excellent super characteristic of a discharge lamp to be used. This will be described later.

4 is an overall circuit diagram of a ballast including a piezoelectric coupler. This piezoelectric stabilizer is applicable to both fluorescent lamps and high-pressure discharge lamps, and can be used regardless of the power consumption size. This is a possible ballast. In particular, when applied as a piezoelectric ballast for turning on one of the high-pressure discharge lamps, the high voltage is discharged for the initial lighting even when the ignition circuit including the existing ballast is not included. Compared to the compact and lightweight ballast, it is possible to manufacture.

In FIG. 4, the power source is a commercial AC power source, and a fuse is used for overcurrent protection, and a varistor connected in parallel to an AC line in front of the rectifier is used as an overvoltage protection device. Noise filters and three capacitors C1, C2 and C3 act as EMI protection, while EI1916 coils, diodes and capacitors C4 improve the power factor in a bell-fill way for power factor improvement. When commercial AC power is applied, the bridge is rectified and energy is accumulated and smoothed by C5 after power factor improvement. In addition, the excess low voltage is obtained from the secondary of the inductor and rectified to use as a power source for the IC. A Zener diode of 12V is used to keep the IC supply voltage constant, and C6 is a smoothing capacitor for the IC supply. The IC is also a pulse generator, and the frequency of the generated pulses is determined by R5, R4 and C7. At this time, it is preferable to configure R4 as a variable resistor so that an accurate oscillation frequency can be set.

The oscillation frequency may vary depending on the type of pulse generator used, and the oscillation frequency in the IC used in this example is determined by the following equation.

The oscillation frequency is preferably set so as to deviate from the resonance frequency by the inductor EI2519 and the piezoelectric coupler PC.

Using the oscillation input terminal of the IC, the capacitor is normally connected and oscillated. However, when an abnormal current occurs, the anode of the capacitor is closed by a FET (field effect transistor) to stop the oscillation.

Each output pin of the IC outputs a rectangular inverted and non-inverted pulse. This output waveform drives FETs Q3 and Q4 through resistors R6 and R12, respectively. When a driving voltage of a predetermined frequency is applied to the FET gate, two FETs Q3 and Q4 are alternately switched to form an output AC. This causes resonance by the inductor EI2519 and the piezoelectric coupler (PC), and discharges the high voltage by the initial input signal, and the high voltage is induced equally to the discharge lamp (FL) connected in parallel with the piezoelectric coupler (PC). By activating the mercury in the FL) it is possible to turn on, and then to the normal state to maintain the lighting state of the discharge lamp (FL).

In the case of a ballast using a piezoelectric coupler, the capacitance of the piezoelectric body varies nonlinearly according to the input voltage, and the magnitude of the voltage initially discharged is automatically changed according to the characteristics of the discharge lamp. On the other hand, if the secondary winding is installed in EI2519 to detect the current under overload and no load, divide the voltage between R9 and R10, and detect the abnormal voltage with 5.1V Zener diode so that the voltage on pin 2 of IC becomes 0V. Since the oscillation stage of the IC is fixed at a low voltage, the IC stops oscillation. This causes the inverter to stop switching and protect the ballast.

FIG. 5 illustrates a frequency band in which normal driving is possible and a correlation between a magnitude and a frequency of voltage generated when a discharge lamp is turned on using the ballast of FIG. 4.

The capacitance of the piezoelectric coupler used was 2.3 kHz, and the self-resonant frequency of the device was 114 kHz in the radial vibration mode. The inductor used here was 2.15 mH, and the resonance frequency and impedance at the time of coupling with the piezoelectric coupler were 70.8 kHz and 8.8 Ω, respectively.

FIG. 5 shows the results of lighting a 20W light bulb fluorescent lamp (CFL) (solid line) and a T8 straight fluorescent lamp (dotted line) having a 32W diameter of 26 mm. The initial lighting voltage required to turn on the lamps was 740V for bulb-type fluorescent lamps and 780V for T8. Here, since the initial voltage value required for lighting varies among manufacturers even in the same type of discharge lamp, the lighting voltage of a specific fluorescent lamp used in the present invention does not mean an absolute value that can be universally applied to all fluorescent lamps. . For example, among fluorescent lamps, a product having a lighting voltage of about 400V is also available.

In the case of the fluorescent lamps used in the present invention, the frequency bands that can be turned on are 18 to 22 kHz and 60 to 72 kHz, respectively, and the bandwidths are 4 and 12 kHz. Although the highest voltage is shown at the resonance point, the light can be turned on over a large area even near the resonance point, and the light can be turned on at a point of 18 to 22 kHz, which is a significant deviation from the resonance point.

In the case of T8, the driving band is wider between 18-22kHz and 58-78kHz in the band near the resonance point than the bulb fluorescent lamp. This is because the fluorescent lamp itself is a non-linear impedance element having a RC component, the range of the driving frequency and the magnitude of the generated voltage vary according to the type of discharge lamp applied.

6 shows a piezoelectric coupler having different characteristics, the capacitance of the piezoelectric element was 2.5 Hz, the resonance frequency of the element itself was 78 kHz, and the main resonance point connected to the inductor was 58.5 kHz.

As a result of using the discharge lamp as used in FIG. 5, it was possible to light in the frequency band of 18 to 27, 32 to 38, 52 to 63, 103 to 108 kHz in the case of the bulb fluorescent lamp, the lowest frequency band in the case of T8 Only the bandwidth narrowed down to 18-22 kHz, but showed similar frequency characteristics as the bulb fluorescent lamp. In general, piezoelectric ceramics have a resonant frequency band of the device depending on the vibration mode to be used, and the resonant frequency of the piezoelectric ceramics varies greatly depending on the size of the portion that causes resonance in the same vibration mode. Since the piezoelectric coupler used in the present invention mainly used a disk type in consideration of reliability and mass productivity, the resonance mode used is a radial direction and the resonance frequency increases as the diameter of the piezoelectric coupler decreases.

However, since the efficient driving of discharge lamps is generally in the range of 20 to 90 kHz, the resonance frequency of the device must be adjusted to this band. Therefore, if the matching with the inductor used is effective, the discharge lamp may be turned on in the range of 20 to 100 kHz regardless of the size of the device. Can produce a ballast.

7 shows the voltage and current characteristics of the tube during initial lighting when a 20W class fluorescent lamp (CFL) is used as a load. As shown in FIG. 5 and FIG. 6, the lighting is possible even at the non-resonant frequency, and FIG. 7 shows the result when the lighting is performed at the non-resonant frequency.

As can be seen in the figure, by using the non-resonant frequency, initially only 600V high voltage for lighting is applied, but after 0.4 seconds, the tube current is 166kV which is the steady state value and the initial discharge voltage is the steady state tube voltage. Since it is reduced to 83V, it can be seen that it has a soft-start due to a 0.4 second delay.

In this case, when the driving frequency of the applied discharge lamp is driven at the resonance frequency of 70.8 kHz of FIG. 5, the discharge lamp may be turned on as soon as the electric signal is applied, thereby shortening the life of the discharge lamp. However, in the present invention, the driving frequency may be set between 60 and 65 kHz. This allows the soft start function to be eliminated early, eliminating the problem of shortened life.

FIG. 8 is a result of measuring illuminance characteristics according to temperature change of a device using a fluorescent lamp (CFL) having a ballast. In order to see the temperature characteristics of the piezoelectric stabilizer according to the present invention, after the whole ballast including the piezoelectric coupler or the piezoelectric coupler was left in a constant temperature and humidity chamber at -20 to 150 ° C, the lighting test and the change in illuminance were performed. When the entire ballast including the piezoelectric coupler was left in the constant temperature and humidity chamber, it operated normally up to 110 ℃ without changing the illuminance, and the frequency range of the lighting band was wide even though the driving frequency changed slightly due to the temperature characteristics of the passive element and the piezoelectric coupler. There was no abnormality in reliability as a ballast. Among the passive components used in this case, the maximum usable temperature of the capacitor is 105 ° C, which is consistent with the available temperature range of existing ballasts. Meanwhile, as shown in FIG. 8, only the piezoelectric coupler was left in the constant temperature and humidity chamber. As a result, the piezoelectric coupler was stably lit up to 130 ° C., and the change frequency of the driving frequency was less than about 0.5 kHz at 130 ° C. for the frequency of the piezoelectric coupler. The response characteristic was determined to be very good. Since the bulb-type fluorescent lamp is close to the ballast and the lamp, since the ballast receives the heat radiated from the lamp as it is, a higher temperature stability of the device is required than in other ballasts. The usable temperature range varies greatly depending on the piezoelectric coupler used, and the piezoelectric coupler used in the present invention exhibits normal on / off characteristics up to 130 ° C.

In general, all discharge lamps generate considerable heat due to the current flowing through the internal filament and the characteristics of the stirrups, and these heats contribute to the increase of the optical brightness. Therefore, in general ballasts, the lamps are driven at 80 to 100 ° C. In the case of, because the back and ballast are attached, the internal temperature of the ballast reaches about 100 ℃. In addition, since the instantaneous lighting ballast of the present invention uses a short circuit of the filament which is a heat source of the lamp, the heat generated from the surface of the lamp may be limited to being generated simultaneously with the emission of light while hitting the inner wall of the fluorescent lamp. . Therefore, by greatly reducing the amount of heat emitted from the surface of the back can not only lower the internal temperature of the ballast, but also to minimize the loss of electrical energy relatively, it was possible to manufacture a ballast of high efficiency. Another reason for achieving high efficiency is that the energy applied to hot electrons during high pressure discharge is increased compared to the electronic ballast, and thus the light efficiency of the lamp increases because electric energy is emitted as much as electric energy is converted to light energy. .

A practical example for showing such an increase in light efficiency is as follows.

Experimental Example 1

Table 1 shows the results of lighting various discharge lamps using a ballast circuit as shown in FIG. 4 equipped with a piezoelectric piezoelectric coupler, which is indicated immediately below.

The size of the piezoelectric coupler used depends on the type of discharge lamp used, and is represented by the capacitance C of the piezoelectric coupler. T8, T5, and T2 shown in the table are straight fluorescent lamps with diameters of 26 mm, 16 mm, and 7 mm, FPL is U-shaped fluorescent lamps, and fluorescent lamps are compact lamps with built-in ballast (CFL). Sodium or the like was used. The driving frequency varies from 30 to 65 kHz in accordance with the diameter of the piezoelectric coupler and the inductor used, and the non-resonant frequency band is used. At least 91% of power efficiency was measured for all discharge lamps measured. Especially, in case of general T8 fluorescent lamps with a relatively large diameter, the surface temperature of the lamp was 40-45 ℃, and the heat generation temperature was turned on by the electronic ballast of the cathode preheating method. The exothermic properties were significantly lower than those of 60 to 70 ° C. This shows that the heat dissipation temperature of the piezoelectric stabilizer is lower than that of the electronic type for all the applied lamps.

Experimental Example 2

Table 2 below is a comparison of the electrical characteristics of the piezoelectric stabilizer and the electronic ballast shown in Figure 4 is a result showing that the piezoelectric stabilizer has a high power efficiency. In the case of bulb-type fluorescent lamps, the piezoelectric input power is lower than that of the conventional products, but the same illuminance as the conventional products can be obtained by maximizing the super-characteristic that the lamp can exhibit even by such input power. In the case of general electronic ballasts, the specifications of transformers or chokes used as ballast components vary depending on the discharge lamp or load used.In the case of piezoelectric couplers, the initial lighting voltage and the tube voltage vary depending on the load characteristics to be applied. It has a function that adjusts automatically.

Experimental Example 3

50, 150, 200W class sodium lamps were turned on using a piezoelectric ballast for high pressure sodium lamps shown in FIG. Conventional magnetic ballasts show less than 80% power efficiency, while piezoelectric ballasts show 91% power efficiency as shown in Table 1, and the initial lighting voltage of about 2,800V is generated without an ignition circuit. The lighting could be achieved.

As mentioned above, although this invention was demonstrated with drawing and Example, this invention is not limited to a specific Example, The person of ordinary skill in the art, many corrections and a change without departing from the scope of this invention. I will understand this possible.

In addition, the protection scope of the present invention will be defined by the appended claims.

According to the present invention, the piezoelectric stabilizer using the piezoceramic as a ballast component can be applied to both a general fluorescent lamp and a high-pressure discharge lamp, thereby producing a power-saving product that realizes higher efficiency than an electronic ballast, which is a conventional high-efficiency energy equipment.

In addition, by minimizing the size of the piezoelectric ceramics used in the piezoelectric ballast, the high output of the piezoelectric ceramics can be stably driven to drive a discharge lamp of 30W or more even with the size of a general capacitor. There is a significant advantage in reliability and mass production over piezoelectric transformers that have to be large in size.

In addition, by showing the applicability of the piezoelectric coupler of the present invention to a compact backlight fluorescent lamp (CCFL) inverter, which is an LCD backlight, mass production and cost aspects compared to piezoelectric transformers that are recently applied to low-power inverters The piezoelectric coupler having superior advantages in is widely applicable to various discharge lamps throughout the industry.

Claims (6)

Overcurrent and overvoltage protection devices, An AC power supply including an unwanted electromagnetic wave (EMI) prevention circuit and a power factor improving circuit connected thereto; A rectifier connected to the power factor improving circuit, A pulse generator for receiving a signal from an input power source to produce a constant frequency, and a switching frequency setting circuit for setting the constant frequency; Two field effect transistors for switching the output alternating voltage from the rectifier in accordance with the pulse of the pulse generator; An inductor connected between the common output of the two field effect transistors and a discharge lamp, Piezoelectric couplers connected in parallel to discharge lamps, Piezoelectric stabilizer using a piezoelectric coupler having a. The method of claim 1, And a reset circuit connected to the pulse generator for resetting the pulse generator in the event of an overload or no load. The method of claim 1, And a capacitor connected in series with the discharge lamp and in parallel with the piezoelectric coupler. The method according to any one of claims 1 to 3, And said switching frequency setting circuit is set to a frequency deviating from the resonant frequency due to the coupling of said piezoelectric coupler and said inductor. The method of claim 4, wherein The piezoelectric coupler is a piezoceramic disk-shaped, the resonant mode is a radial direction, the piezoelectric stabilizer using a piezoelectric coupler, characterized in that the resonance frequency increases as the diameter of the piezoceramic decreases. The method of claim 4, wherein The inductor is a high efficiency piezoelectric stabilizer using a piezoelectric coupler, characterized in that more than 2mH.