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:
Sep. 09, 1986
Filed:
Apr. 03, 1985
Hiroshi Minami, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
An X-ray image tube has a vacuum envelope, a photocathode arranged at an input side in the vacuum envelope and having a curved surface open to an output side thereof, and a phosphor screen arranged at an output side in the vacuum envelope and having a surface on which electrons emitted from the photocathode are electrooptically focused. The photocathode consists of a central surface region with a diameter which is 1/2 to 4/5 of the diameter of the photocathode and a peripheral surface region. The central surface region has a profile such that an increment of the meridional curvature radius from the center to a peripheral portion thereof is larger than a constant derived from a linearity between the increment and a distance from the axis of the photocathode. The peripheral surface region has a profile such that an increment of the meridional curvature radius from an inner peripheral portion to an outer peripheral portion is smaller than the constant derived from a linearity between the increment and the distance from the axis of the photocathode.