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. 15, 2003
Filed:
Mar. 29, 2000
Applicant:
Inventor:
Yoshikiyo Yui, Utsunomiya, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J 2/946 ;
U.S. Cl.
CPC ...
H01J 2/946 ;
Abstract
An electron gun according to this invention includes a cathode having a hemispherical electron-emitting surface, an anode which is arranged to face the cathode, and has a first aperture on the optical axis, and a bias electrode which is arranged between the anode and the cathode, receives a potential lower than one applied to the cathode, and has a second aperture larger than the electron-emitting surface of the cathode on the optical axis. The distal end of the electron-emitting surface of the cathode is arranged in contact with or outside a sphere whose diameter is equal to the diameter of the second aperture of the bias electrode.