| 摘要 |
PURPOSE:To decrease dark current components and to detect the focusing state with good accuracy, by disposing a light emitting part in such a position where the front end thereof is equal to a photodetecting surface or projects therefrom, and disposing a light shielding member on the side wall of an aperture part. CONSTITUTION:A lens 1 is so constituted as to form the image of an object 2 on a prescribed image plane, and a photosensor 5 is disposed in the position 4 on an optical axis 3 conjugate to the image plane. The sensor 5 is formed with a p type semiconductor layer 7 on an n type semiconductor 6, and when light is made incident to the p-n junction surface thereof, photoelectric current flows therein, and whether focusing or not can be detected by measuring the voltage across the resistor 10. A light emitting member 12 is embedded in the through- hole at the center of the p-n junction surface so as to be fitted therein. The front end of the member 12 is formed so as to be made flush with the front end face of the photodetecting surface or to project therefrom, and the side part thereof is formed of a light shielding member to prevent the leakage of the light from the member 12 directly to the photodetecting surface side. |
