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:
Nov. 21, 1978
Filed:
Oct. 12, 1976
Applicant:
Inventor:
Robert P Randall, Uxbridge, GB;
Assignee:
EMI Limited, Hayes, GB;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
313 57 ; 313 55 ; 3133 / ;
Abstract
An X-ray tube is described in which, in order to produce a well defined electron beam which can be accurately focussed on the target of the tube, the cathode comprises a flat plate member, such as a tape or foil, the surface finish of which is sufficiently smooth that electrons are emitted therefrom with lateral energies below 0.2 electron volts. The aforementioned surface finish is such that irregularities in the electron-emitting surface of the cathode do not exceed one micron in amplitude.