Focus detector for camera using preliminary irradiation

Abstract

Abstract PURPOSE:To eliminate an exposure error by inhibiting the A/D conversion of the output of a light metering circuit for exposure control from being started while a measurement for focus detection is taken by turning on a light source for preliminary irradiation. CONSTITUTION:When the output 30 of an exposure arithmetic circuit 14 is at H and the output of a dimming circuit 4 is A/D-converted by an A/D converting circuit 5, a control circuit 8 does not operate for measuring and light emitting operation even if the output of an arithmetic circuit 18 goes up to H. When data is fetched in an exposure arithmetic circuit 14 after the A/D conversion, the measuring and light emitting operation by the control circuit 8 starts. On the other hand, even if the output 30 goes up to H when an output 31 is at H and the measuring and light emitting operation by the control circuit 8 is carried on, the circuit 5 does not operate. This circuit 5 starts operating when the light emission of a xenon lamp 10 ends and the output of each photodetecting element is sampled and held. Therefore, the A/D conversion and measuring operation for focus detection are not performed simultaneously, so no exposure error occurs.

Inventors

• 👤 Nobuyuki Taniguchi
• 👤 信行 谷口
• 👤 Norio Ishikawa
• 👤 典夫 石川
• 👤 Takeshi Egawa
• 👤 猛 江川

Bibliographic Details