| 摘要 |
A focus detecting device comprises an image forming optical system, a light beam scanning device for scanning the light beam from the image forming optical system in a predetermined direction and for generating an electrical output corresponding to the scanning direction of the light beam, an image re-forming optical system for re-forming the image formed by the image forming optical system, an image position detecting device for photoelectrically detecting the direction of movement of the image formed by the image re-forming lens, and a discriminating circuit for discriminating between the focusing, the front focus and the backward focus from the direction of movement of the image by the image re-forming optical system with respect to the direction of scanning of the light beam by the scanning optical system on the basis of the outputs of the light beam scanning device and the image position detecting device.
|
