On the luminousity vs current form of a fluorescent discharge lamp

Abstract

In case a fluorescent discharge lamp radiates light by alternating current, the relation between the luminousity and the value and shaps of discharging current is not so simple. An appropriated cathode spot temperature would be attained easily by reasonable effective value of the lamp current only, having no relations with the shape of the current. But the luminousity of a fluorescent discharge lamp varies by the shape or the crest factor of the lamp current, and in general it would be well known that somewhat smaller value of a lamp current gives better value of luminous efficacy lm/W. The author tries to analize such phenomena in this paper. At first an experimental evidence shall be shown, when a fluorescent lamp is driven by DC current, the relation of luminousity vs lamp current is not linear but has a saturative nature, and it will give an experimental equation of luminousity vs lamp current. This experimental equation should be treated as a foundation of following calculations. The luminousity would be expressed as a function of instantaneous value of the lamp current. And the time mean of integlated luminousity gives the so called practical value of the luminousity. For example there shall be explained that when phase controlled lamp current which shows zero value area of phase angle is given to a lamp, it would give low value of luminousity even if the effective value of lamp current is increased up to equal or more than standard value of lamp current in the catalogue data.