DEVICE FOR OPERATING A DISCHARGE LAMP

摘要

The invention relates to a device for operating a fluores- cent discharge lamp of the outer electrode type. As claimed in the invention a switching device is turned on and off by driver signals with a stipulated frequency, by which on the secondary side of a transformer the periodic voltage wave- form shown at A in Figure 1 is produced. This voltage wave- form is applied to the fluorescent discharge lamp of the outer electrode type, and thus operation is effected. For the above described periodic voltage waveform, with respect to repetition period t 2 W o < t, if the width at a vol- tage of the waveform of 0 V which has a single maximum peak value within one period is labelled W o, its full width at half maximum (the width between a and b in Figure 1) being set to a stipulated value (for example, to a value of less than or equal to 2.5 .mu.sec). This makes it possible to maintain stable emission even if the pressure of the gas filled in the discharge lamp is increased. In this way high illumination intensity can be obtained.