Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Joachim Arlt

Dietrich Fromm

Jurgen Heider

Alexander Dobrusskin

Jurgen Von Scheidt

Start and operation of high pressure discharge lamps, in which a high-frequency starting voltage U.sub.HF and an operating voltage U.sub.B are furnished to the lamp electrodes includes the steps of: 1) turning on the high-frequency starting voltage U.sub.HF at a starting time t.sub.0 to ionize the lamp filling and preheat the electrodes; 2) turning on the operating voltage U.sub.B after a preheating interval .DELTA.t.sub.H, that is, at time t.sub.1 =t.sub.0 +.DELTA.t.sub.H ; and 3) turning off the starting voltage U.sub.HF at time t.sub.2 .gtoreq.t.sub.1, as a result of which the lamp is then operated solely by means of the operating voltage U.sub.B. As a result, the transfer phase for the development of the arc is shortened. Advantageously, the frequency of the starting voltage is selected such that the product of the frequency f of the starting voltage U.sub.HF and the spacing d between the electrodes meets the condition f.multidot.d.gtoreq.50 kHz.multidot.cm. A circuit arrangement for carrying out this method includes an HF ignition device and an operating device, which are each connected to the electrodes of the lamp via a respective switch, and the two switches are actuated by means of timers.

Method and circuit to start and operate high pressure discharge lamps

To shorten the time between firing of a high-pressure discharge lamp and stantial light output therefrom, the discharge lamp includes a fill of xenon, at a cold fill pressure of at least 3 bar, in addition to mercury and a metal halide; the discharge vessel (2) is, at least in part, coated or doped so that invisible radiation is reflected into the lamp, or absorbed, while visible radiation is being transmitted by the discharge vessel. The shafts of the electrodes are thin, of only about 0.3 mm diameter, and the electrodes facing each other are part-spherical or rounded. The lamp is operated in combination with a lamp power supply (S) which has the characteristics of being capable of supplying between 5 to 10 times normal operating current of the lamp under starting conditions.

Illumination system having a low-power high-pressure discharge lamp and

Discharge lamp energization circuit to operate a discharge lamp 1 over two electronic switches 10, 11, for example high-voltage, high-current switching transistors, which alternately apply a d-c voltage connected across two capacitors 4, 5, in opposite polarity, to the lamp circuit. The capacitors have the same value, and the lamp circuit includes a serially connected inductance. The electronic switching transistors are supplied from a frequency constant square-wave generator 16, at frequency high with respect to power line frequency, for example within the audio or supersonic range, e.g. 7.5 kHz. A separate ignition or starting circuit may be provided or the series inductance 2 and a capacitor 20 connected in parallel with the lamp may form a series resonance circuit tuned to a low odd harmonic (3, 5 7) of the lamp operating frequency.

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Munich, Germany

Joachim Arlt