Photocopying – Contact printing – Light boxes
Patent
1974-08-08
1975-02-03
Hayes, Monroe H.
Photocopying
Contact printing
Light boxes
354 25, 355 56, G03B 300
Patent
active
039368491
ABSTRACT:
A device for detecting focussing in an optical instrument such as a camera which has an objective lens and a plane, at which light sensitive film may be disposed, upon which a real image of an object is intended to be focussed. The device comprises a window to which the eye of the operator is held, and means for projecting light to the operator's eye which looks at the real image of the object formed by the objective lens. The light projected on the retina of the operator's eye is reflected back into the camera and is directed to focus-judging means in the nature of a light sensitive member which detects when the retina of the operator's eye is optically conjugate with an imaginary reference plane located in a position optically equal to a plane on which a real image of the object formed by the objective lens is intended to be focussed, thus also detecting when the position of the real image coincides with said reference plane so that the selected object is properly focussed.
REFERENCES:
patent: 3543666 (1970-12-01), Kazel
patent: 3713371 (1973-01-01), Kurihara
Hayes Monroe H.
Minolta Camera Kabushiki Kaisha
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