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:
Aug. 15, 1995
Filed:
Nov. 03, 1993
Toshiro Kubo, Katsuta, JP;
Toshiyuki Ohashi, Katsuta, JP;
Mikio Ichihashi, Kodaira, JP;
Yuji Sato, Katsuta, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An electron lens comprising a first exciting coil, a second exciting coil, a casing for encompassing the first and second exciting coils, and an excitation control apparatus for controlling the excitation state of at least the first exciting coil independently of the second exciting coil. The excitation control apparatus independently controls currents applied to the first and second exciting coils, respectively. At this time, exothermy of each coil can be kept constant and thermal deformation of the casing can be prevented by keeping the sum of the absolute values of the currents applied to the coils.