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. 05, 2011
Filed:
May. 07, 2008
Hiroshi Yasuda, Tokyo, JP;
Takeshi Haraguchi, Tokyo, JP;
Yoshihisa Ooae, Tokyo, JP;
Takamasa Satoh, Tokyo, JP;
Yoshinori Terui, Shibukawa, JP;
Seiichi Sakawa, Shibukawa, JP;
Ryozo Nonogaki, Shibukawa, JP;
Hiroshi Yasuda, Tokyo, JP;
Takeshi Haraguchi, Tokyo, JP;
Yoshihisa Ooae, Tokyo, JP;
Takamasa Satoh, Tokyo, JP;
Yoshinori Terui, Shibukawa, JP;
Seiichi Sakawa, Shibukawa, JP;
Ryozo Nonogaki, Shibukawa, JP;
Advantest Corporation, Tokyo, JP;
Denki Kagaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
An electron gun includes an electron source configured to emit electrons. The electron source includes an electron emission region configured to emit the electrons and an electron emission restrictive region configured to restrict emission of the electrons. The electron emission restrictive region is located on a side surface of the electron source except an electron emission surface on a tip of the electron source and is covered with a different material from the electron source. The electron gun emits thermal field-emitted electrons by applying an electric field to the tip while maintaining a sufficiently low temperature to avoid sublimation of a material of the electron source. The material of the electron source may be lanthanum hexaboride (LaB) or cerium hexaboride (CeB). The electron emission restrictive region may be covered with carbon.