Optics: image projectors – Prism in light path
Patent
1995-05-11
1996-05-07
Dowling, William C.
Optics: image projectors
Prism in light path
353 26A, 355045, G03B 2128
Patent
active
055151213
ABSTRACT:
In an apparatus for projecting an image by a projection lens onto a projection surface such as a screen surface or a surface of a recording medium, a prism for rotating the projection image is disposed on the exit side of the projection lens so that the entrance-side optical axis of the prism deviates from the exit-side optical axis thereof. An image-forming lens and a focal point detecting unit for detecting a focus state of the projection lens on the projection surface are disposed on a reflection side of a half mirror. When the focal point detecting unit detects the focus state of the projection lens, an adjusting unit effects a relative rotation between the prism and the image-forming lens and focal point detecting unit so as to make the exit-side optical axis of the prism coincide with the optical axis of the image-forming lens.
REFERENCES:
patent: 4436391 (1984-03-01), Kashiwagi
patent: 4695155 (1987-09-01), Ishii et al.
patent: 4825243 (1989-04-01), Ito et al.
patent: 4855789 (1989-08-01), Ogawa
patent: 4952052 (1990-08-01), Ueda et al.
Canon Kabushiki Kaisha
Dowling William C.
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