Two-wire dimmer with improved zero-cross detection

摘要

A two-wire lighting control device, may include a controllably conductive device, a signal generation circuit, and a filter circuit. The controllably conductive device may apply an AC line voltage to a load, being conductive for a first duration of time and non-conductive for a second duration of time within a half-cycle of the AC line voltage. The signal generation circuit may generate a non-zero-magnitude signal. And, the filter circuit may receive a signal from the controllably conductive device during the first duration of time and the non-zero-magnitude signal from the signal generation circuit during the second duration of time. The non-zero-magnitude signal may, in effect, fill-in or complement the signal from the controllably conductive device, and any delay variation as a function of the firing angle of the controllably conductive device through the filter circuit may be mitigated by the presence of the non-zero-magnitude signal.

主权项

1. A lighting control device comprising:
a controllably conductive device configured to supply an AC line voltage to a load in response to a control signal, wherein the controllably conductive device is non-conductive for a first duration of time and is conductive for a second duration of time, wherein the first duration of time and the second duration of time are within the same half-cycle of the AC line voltage; a signal generation circuit configured to generate a fill signal; a combiner circuit for combining a signal from the controllably conductive device during the first duration of time and the fill signal during the second duration of time; and a filter circuit configured to receive the combined signal from the combiner circuit, wherein the signal generation circuit is configured to shape the fill signal such that delay associated with filtering the signal from the controllably conductive device during the first duration of time and the fill signal during the second duration of time is consistent with delay associated with filtering the AC line voltage.