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:
Mar. 04, 2003
Filed:
May. 30, 2000
Hsing-Yao Chen, Barrington, IL (US);
Shunlu Xiao, Beijing, CN;
Chunghwa Picture Tubes Ltd., Taoyuan, TW;
Abstract
An electron gun for use in a cathode ray tube (CRT) includes a source of energetic electrons, i.e., a cathode, a beam forming region for forming the energetic electrons into a narrow beam, an arrangement for deflecting the beam over a display screen, and a focus arrangement for focusing the beam on the display screen in the form of a small spot in forming a video image. The beam forming region includes a G control grid, a G screen grid and a portion of a G grid in facing relation to the G grid, where each grid includes a respective aperture through which the electron beam is directed, with the apertures aligned along a common axis. The size of the aperture on the side of the G grid in facing relation to the G grid forms a first focusing lens and is smaller than the size of the aperture on the opposed side of the G grid in facing relation to the G grid which forms a second focusing lens. The larger size of the G aperture in facing relation to the G grid reduces electron beam convergence and spherical aberration of a video image formed by the beam on the display screen. The aperture of the G grid may increase in diameter in proceeding from the low side, i.e., the G control grid facing side, to the high side, i.e., the G grid facing side, in a step-wise manner or in the general shape of a cone. The invention is adapted for use in a single beam projection CRT as well as in a multi-beam color CRT.