KR970064324A - Electronic ballast for discharge lamp - Google Patents

Abstract

A first smoothing means for smoothing a rectified voltage from the rectifying means, an inductor (L), and a starting capacitor (Cp) for rectifying the AC power, a resonance type inverter Trigger means for triggering resonance in the resonant inverter means in response to the smoothed voltage, a first switch for providing a current path for allowing current to flow from the resonant inverter means, A second switch for providing a current path for allowing current to flow from the resonant inverter means, a first switch for turning on one of the first and second switches in accordance with the direction of the current from the resonant inverter means, The first switch control means, and the first switch, regardless of the current direction of the resonant inverter, And second switch control means for turning off the second switch at a period shorter than the period of the resonance frequency.

Description

Electronic ballast for discharge lamp

Since this is a trivial issue, I did not include the contents of the text.

Fig. 3 (a) is an equivalent circuit diagram of an electronic ballast for discharge lamp before discharge shown for explaining the present invention. Fig.

3b is an equivalent circuit diagram of an electronic ballast for discharge lamp after discharge shown for explaining the present invention.

Figure 3c shows the resonance characteristic curves for the respective equivalent circuits of Figures 3a and 3b.

FIG. 4 is a view schematically showing a waveform of a resonant current according to a change in switching frequency shown for explaining the present invention. FIG.

FIG. 5 is a view showing an example of an electronic ballast for a discharge lamp according to the present invention; FIG.

Claims (12)

First rectifying means for rectifying AC power; First smoothing means for smoothing a rectified voltage from the rectifying means; Resonant inverter means for driving the discharge lamp including an inductor (L) and a starting capacitor (Cp); Trigger means for triggering resonance in said resonant inverter means in response to said smoothed voltage; A first switch for providing a current path for allowing a current to flow from the resonant inverter means; A second switch for providing a current path for flowing current from the resonant inverter means; First switch control means for causing one of the first switch and the second switch to be turned on and the other to be turned off in accordance with the direction of the rectification from the resonant inverter means; And second switch control means for turning off the first switch and the second switch at a period shorter than the period of the resonance frequency irrespective of the current direction of the resonance inverter. The ballast for discharge lamp according to claim 1, wherein the second switch control means turns off the first switch and the second switch at a period shorter than a half period of the resonance frequency. 2. The inverter according to claim 1, wherein the first switch control means is connected to the primary winding arranged in the path of the current from the resonant inverter and to the first switching means and the second switching means, A ballast for a discharge lamp comprising a current transformer composed of two secondary windings whose voltage is to be induced. The ballast for an electric discharge lamp according to claim 1, wherein the second switch control means includes sawtooth wave generating means and sawtooth wave period adjusting means. The sawtooth generator according to claim 4, wherein the sawtooth wave generating means comprises a reference voltage generating means, a first capacitor, a current supplying means for supplying current to the first capacitor to charge the current, And a third switch connected to the comparison means for discharging the first capacitor when the voltage of the first capacitor is greater than the reference voltage. 6. The motor according to claim 5, wherein the current supply means comprises a current mirror connected to the first capacitor, the sawtooth frequency adjusting means comprises resistance means connected to the current supply means, And a resistance adjusting means for adjusting the resistance of the lamp. 7. The ballast for an electric discharge lamp according to claim 6, wherein the resistance adjusting means includes a timer means and increases the resistance value of the resistance means under the control of the timer means. The ballast for an electric discharge lamp according to claim 6, wherein the resistance means comprises a manually adjustable variable resistor. 4. The ballast for an electric discharge lamp according to claim 3, wherein the second switch control means includes another one of the windings coupled with the secondary windings of the current transformer, and a fourth switch for shorting the other one of the windings. The ballast for discharge lamp according to claim 9, further comprising: second rectifying means for rectifying a voltage induced in said another winding; and second smoothing means for smoothing a rectified voltage from said first rectifying means. 5. The method of claim 4, further comprising: voltage sensing means for sensing the smoothed voltage; and means coupled to the sensing means for decreasing the current flowing through the first capacitor when the smoothed voltage is low, Further comprising current dividing means for increasing the current flowing through the first capacitor at a ground level. The plasma display apparatus according to claim 4, further comprising: timing detection means for detecting on / off of the first and second switches; and timing detection means for detecting on / off states of at least one of the first switch and the second switch And a fifth switch for discharging the first capacitor when the first capacitor is switched. ※ Note: It is disclosed by the contents of the first application.