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. 18, 1990
Filed:
Jun. 16, 1988
Applicant:
Inventors:
Satoru Miyamoto, Mobara, JP;
Yoshiaki Takahashi, Chiba, JP;
Katsuyuki Shirai, Mobara, JP;
Ikuya Takahara, Mobara, JP;
Satoru Endo, Mobara, JP;
Assignees:
Hitachi, Ltd., Chiba, JP;
Hitachi Device Engineering Co., Ltd., Chiba, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01J / ; H01J / ;
U.S. Cl.
CPC ...
313414 ; 313449 ; 313458 ; 313456 ;
Abstract
At least one of grid electrodes which serves as a main lens of an electron gun for use in a color cathode ray tube is divided into a plurality of cylindrical electrodes coaxially connected. An inner electrode is provided at the connection part between the cylindrical electrodes so that the center of an elliptical aperture of the inner electrode coincides with the center of an inner wall of the grid electrode. Thus, astigmatism in the main lens is removed, thereby improving the resolution of the color cathode ray tube.