method and apparatus for checking the light bulb, in particular the dark

摘要

At the start of the switching-on process of the incandescent lamp (5), a first actual value (ILA) of the lamp current (IL) and then, after a time lapse (T), a second actual value (ILE) are measured. The time lapse (T; T1, T2, T3) is predetermined dependently upon the first actual value (IL1A, IL2A, IL3A) at the start of a switching-on process in such a way that, when a drop (I, II, III) therein occurs, the length of the time (T1, T2, T3) is extended. The difference ((Delta) I; (Delta) IL1 (Delta) IL2, (Delta) IL3) between the measured actual values is evaluated to detect the operability of the incandescent lamp. The time is preferably predetermined in such a way that the lamp does not light up until it has elapsed and the lamp is then disconnected from the supply voltage again.