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. 27, 1983
Filed:
Jan. 11, 1982
Yoshitaka Nakamura, Otsu, JP;
NEC Kansai, Ltd., Otsu, JP;
Abstract
A projection cathode ray tube is provided with elements for correcting a spherical aberration in the optical system. These elements include a correction lens disposed in front of the tube and a masking member adjustably mounted on the lens. The masking member partially covers peripheral surface portions of the lens in an adjustable manner to obtain a high image resolution on the screen with a minimum decrease in the image brightness. Preferably, the masking member is removable or adjustable in the form of a masking tape or divided shutter attached to partial portions of the front face of the lens for removing an undesired aberration with a minimized shuttering area. The projection tube comprises in combination with the correction lens, a tube envelope including a convex target and a concave mirror disposed opposite to each other and having the same center of curvature. This structure with the adjustable masking achieves a high quality reception or image projection.