| 摘要 |
PURPOSE:To make possible the focus detection of the subject of a wide luminance region including low luminances as well with a miniature constitution by changing over self-scanning type photoelectric transducer groups alternately for luminance modulation and luminance detection. CONSTITUTION:When a luminance detecting-modulating changeover circuit 16 becomes high level output, a semiconductor switch B2 and a semiconductor switch B1 connecting to an inverter go ON and OFF respectively and the outputs of AND gates A1, A6... become of low levels, causing semiconductor switches S1... to go ON and S0 to go OFF, and preventing reverse bias from being applied to the photo diodes d1... constituting the self-scanning type photoelectric transducer groups. Thus, the subject luminance is detected by the current corresponding to the overall luminance. According to this detected luminance, the scanning time, etc. of the circuit 1 are adjusted by way of a luminance modulating circuit 17. When the output of the circuit 16 inverts, it similarly becomes the focus detection operation in which the luminance at every scanning point corresponding to the diodes d1... is well detected over a wide range region of the subject luminance. |
