Method and device for measuring an illuminance and thus provided twilight switch

摘要

Device for measuring an illuminance (E) with a light sensor (1) and a control unit (2), characterized in that the light sensor (1) consists of a photodiode (P) operated in the blocking direction and a capacitor (C) connected in parallel with it that the control unit (2) contains a charging circuit for charging the capacitor to a capacitor voltage (Uco) and two different discharge current sources (i1, i2), which periodically discharge the capacitor (C), and a timing device (Z) that measures the discharge times (t1 , t2) of the capacitor (C) and sets them in relation to each other.