LIGHT EMISSION CONTROLLER FOR FOCUSING DEVICE

摘要

PURPOSE:To reduce the power consumption and to improve the precision of focusing by switching the quantity of emitted light in a light emitting part in accordance with the output of a light receiving part. CONSTITUTION:A reflected light from an object is condensed on a photodetector 16 in a light receiving part 10 by a condenser lens. The photodetector 16 has a function of photoelectric conversion and outputs photocurrents Ia and Ib condensed by the condenser lens. These photocurrents Ia and Ib are inputted as outputs of the light receiving part to an operating circuit 20 through current-voltage converting circuits 17a and 17b, etc. The moving direction of a photographic lens 26 is calculated in the operating circuit 20, and this signal is outputted to a lens driving circuit 21. The lens driving circuit 21 performs focusing on a basis of the output signal of the operating circuit 20 to focus the lens. Thus, the quantity of current in the photodetector is switched to reduce the power consumption and improve the precision of focusing.