Circuit and lighting system for dimming an illuminant

Abstract

The invention relates to a method and to a circuit arrangement for dimming an illuminant (1) according to digital dimming values (Dd) by regulation. In order to ensure that slow dimming is possible at high resolution, but the regulation takes place quickly at the same time, according to the invention the controller (7) operates digitally but the target value/actual value comparison in the comparator (13) takes place with analog signals. To this end, the digital dimming values (Dd) are first converted to analog dimming values (Da) in a D/A converter (11). The analog control deviation (xa) ascertained by the analog operating comparator (13) is then again converted by means of an A/D converter (14) to a digital control deviation (xd) so that the digital controller (7) can process it. The A/D converter (14) must only process the control deviation—small, in comparison to the returned actual values—and ends up with a relatively low bit count. The D/A converter (11) should additionally distort exponentially in order to compensate for the logarithmic dependence of the subjectively received brightness of the physically measurable light strength of the illuminant (1).

Dependencies are inferred from the claim text.