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:
Apr. 29, 2003
Filed:
Jun. 28, 2001
Kazunori Satou, Fukaya, JP;
Tomonari Ishihara, Fukaya, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
A main lens includes a second segment, a sixth grid and an additional electrode disposed between the second segment and the sixth grid. A first-level constant voltage and a second-level constant voltage are applied to the second segment and sixth grid, respectively. A third-level voltage, which is at a level between the first level and the second level, is applied to the additional electrode. In accordance with the increase in a deflection amount of an electric beam, the third-level voltage varies as a value expressed by ((voltage to the additional electrode)−(voltage to the second segment))/((voltage to the sixth grid)−(voltage to the second segment)). An auxiliary lens having lenses including a third grid and a first segment has a focusing power decreasing in accordance with an increase in the deflection amount of the electron beam.