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:
Jun. 11, 2002
Filed:
Feb. 24, 2000
Hirofumi Ueno, Fukaya, JP;
Tsutomu Takekawa, Fukaya, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
An electron gun assembly forms an electron beam generator, pre-focusing lens, sub-lens, and main lens. The sub-lens has a weaker horizontal focusing power than the vertical one, and the main lens has a stronger horizontal focusing power than the vertical one. When the electron beam is not deflected, a first quadrupole lens is formed between the pre-focusing lens and sub-lens, and a second quadrupole lens is formed between the sub-lens and-main lens. At least one grid forming each of the first and second quadrupole lenses receives a dynamic focusing voltage which parabolically changes in synchronism with the deflection magnetic field and becomes higher when the electron beam is deflected than when it is not deflected.