Range control for automatic flashgun - has thin film potentiometer operated by light valve and film speed controls

摘要

An automatic, electronic flash gun with input controls for light value and film speed has one of the controls (18) mechanically linked to a thin film potentiometer (30) while the other control (15) is linked to the wiper contact (32). The relative setting of the two controls is read off on the potentiometer by the automatic exposure control. The two parts of the control circuit are effectively linked by the potentiometer, with a reference bias applied to the potentiometer for accurate exposures. The connection between the setting controls and the potentiometer can be made by reduction gearings to achieve a more precise control.