Control circuitry for automatic focussing in still or cine cameras - has comparator for counters dealing with pulses representing actual and rated values

摘要

The control circuitry is for continuous regulation of automatic focussing or lens system in still or cine cameras. It comprises actual and rated value generators and a comparator whose output is used as the control signal. The control is digited and is based on a pulse generator. Counters are provided to a deal with the pulses corresponding to the actual and rated values during a measuring phase. A rest time for the counters can be preselected. A comparator compares the counter results and a circuit evaluates them.