The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 14, 2004
Filed:
Jul. 17, 2002
Canon Kabushiki Kiasha, , JP;
Abstract
When light from a reflection image display element is incident on a polarization split surface at an angle other than 45°, leakage light that decreases the contrast of an image is produced. In a projection image display apparatus which illuminates an image display element with light from a light source and projects light from the image display element through two polarization split surfaces, when the angles of first and second light rays, of light rays incident on the polarization split surface, with respect to the optical axis correspond to 55% of the maximum angle of the incident light rays with respect to the optical axis, where light rays of which incident angle with respect to said image display element is larger is set as first light ray and light rays of which incident angle with respect to said image display element is smaller is set as second light ray, and a light shielding characteristic value L on the two polarization split surfaces is represented by L=[(M )a·(M )b+(M )a·(M )b]/2 where (M )a is the amount of leakage light of the first light ray on the polarization split on the reflection image display element side, (M )a is the amount of leakage light of the second light ray, (M )b is the amount of leakage light of the first light ray on the polarization split on the projection optical system side, and (M )b is the amount of leakage light of the second light ray.