Auto focus detecting device

Abstract

Abstract PURPOSE:To make a spatial adjustment of a lens photodetector and a stroboscope device unnecessary, and to raise the productivity by deriving an output ratio of two photodetecting means, and detecting a distance of an object to be photographed. CONSTITUTION:A stroboscope flashgun ST illuminates an object to be photographed under a prescribed view angle, and a reflected luminous flux corresponding to a distance of the object to be photographed is made incident to photodetectors PD1, PD2. A light quantity ratio of the photodetector PD1 and PD2 is large in a short distance side and draws near ''1'' as the object goes toward a long distance. A photodetecting output is inputted to sample holding circuits 52, 55 through photocurrent amplifiers 50, 53 and differentiating circuits 51, 54, the light quantity ratio of the photodetectors PD1, PD2 is calculated by an operating circuit 56, and a distance information of the object to be photographed is derived.

Inventors

• 👤 Takashi Kagechika
• 👤 影近　隆

Bibliographic Details