초록 ▼

This invention relates to a system for automatic focus adjustment of an optical system particularly adapted for use in a photographic camera which utilizes non-linear resistance versus illumination response characteristics which are prominent in photoconductive cells such as cadmium sulfide and cadm

This invention relates to a system for automatic focus adjustment of an optical system particularly adapted for use in a photographic camera which utilizes non-linear resistance versus illumination response characteristics which are prominent in photoconductive cells such as cadmium sulfide and cadmium selenide cells. In one embodiment, a pair of photoconductive cells, one of which has a photoconductive surface having elongated side portions which contact the electrodes along the length of the elongated side portions and another cell which has an elongated photoconductive surface and shortened end portions and which contact the electrodes only at the shortened end portions, are arranged so that portions of an image-forming light beam entering through an objective of the camera are directed to the photoconductive surfaces on which similar real images of an object are formed. The objective includes at least one lens member movable for focusing associated with an automatic focus control mechanism operative in response to variation of an electrical output signal of the photoconductive cell assembly produced when the degree of sharpness of the image on each of the photoconductive surfaces is varied as the focussing member is moved for focussing purposes with respect to the photoconductive cell assembly.

대표청구항 ▼

A system for automatic focus adjustment of a photographic camera comprising: a. an objective lens assembly for focussing an image of an object in a predetermined position said objective lens assembly including at least one lens member movable along the optical axis of the objective lens for focussin

A system for automatic focus adjustment of a photographic camera comprising: a. an objective lens assembly for focussing an image of an object in a predetermined position said objective lens assembly including at least one lens member movable along the optical axis of the objective lens for focussing said image in said predetermined position; b. an optical system for image sharpness detection capable of focussing an image of the same object as above, said optical system including as a component at least said movable member of the objective lens assembly; and c. image sharpness detecting means for detecting an optimum sharpness of the image formed by said image sharpness detection optical system comprising: 1. first and second photoelectric transducing means of different electrical response characteristics from each other with respect to the change in sharpness of the image; and 2. circuit means electrically connected to said first and second transducing means for producing an output signal proportional to the difference between the electrical responses of said first and second cell means, wherein the focus adjustment of said objective lens assembly to selected objects in various distances is automatically effected, and wherein said first photoelectric transducing means has non-linear electrical response characteristics such that its output is increased with increase in sharpness of the image, and said second photoelectric transducing means has non-linear electrical response characteristics such that its output is decreased with increase in sharpness of the image.