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:
Jul. 31, 1990
Filed:
Jun. 14, 1989
Takeshi Kawasaki, Kokubunji, JP;
Junji Endo, Kokubunji, JP;
Shigeto Isakozawa, Katsuta, JP;
Masahiro Tomita, Katsuta, JP;
Akira Tonomura, Koganei, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In a field emission electron gun system with a multi-stage acceleration tube comprising a field emission electron source, a field emission electrode for extracting the electrons, a magnetic lens having a magnetic gap between the field emission electron source and the field emission electrode or a magnetic lens having a magnetic pole which also serves as the field emission electrode, and at least two-stages of acceleration electrodes for accelerating the electrons, a magnetization current I for the magnetic lens is changed interlocking with a field emission voltage V.sub.1 applied between the field emission electron source and the field emission electrode so that IN/.sqroot.V.sub.1 (N: the number of windings of the magnetic lens) takes a predetermined value and a first acceleration voltage V.sub.2 applied between the field emission electron source and the first-stage acceleration electrode is changed interlocking with the field emission voltage V.sub.1 so that V.sub.2 /V.sub.1 takes a predetermined value.