X-ray tube

• US 20030099327A1
• Filed: 01/06/2003
• Published: 05/29/2003
• Est. Priority Date: 07/09/1998
• Status: Active Grant

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Matsushita, Tadaoki, Inazuru, Tutomu
• Granted Patent: US 6,735,282 B2
• Time in Patent Office: Days
• US Class Current: 378/138
• CPC Class Codes: H01J 2235/10 Drive means for anode (target) substrate
• CPC Class Codes: H01J 35/066 Details of electron optical components, e.g. cathode cups
• CPC Class Codes: H01J 35/147 Spot size control

Abstract

An X-ray tube 1 includes spacer 8 which is cylindrical so it does not block electrons 80 directed from a grid electrode 72 toward a focusing electrode 25, and which has one end 8b fixed to the grid electrode 72 and the other end 8c abutting against the focusing electrode 25. The distance between the grid electrode 72 and focusing electrode 25 is set to a predetermined distance by the spacer 8.

Claims

1. An X-ray tube in which a cathode is heated in a housing sealed in vacuum to emit electrons, and the electrons are focused on an anode target through a grid electrode and a focusing electrode, thereby generating X-rays, characterized by comprising

a spacer with one end fixed to said grid electrode and the other end abutting against said focusing electrode, said spacer being formed cylindrical so the electrons directed from said grid electrode toward said focusing electrode can pass therethrough.

2. An X-ray tube according to claim 1, characterized in that the other end of said spacer and said focusing electrode fit with each other through a fitting portion.

3. An X-ray tube according to claim 1, characterized in that said one end of said spacer and said grid electrode fit with each other through a fitting portion.

4. An X-ray tube according to claim 1, characterized in that said spacer has a hole in a circumferential wall thereof through which an inside and an outside of said spacer communicate with each other.

5. An X-ray tube according to claim 1, characterized in that

said spacer and said housing are conductors, and

said focusing electrode, said housing, and said spacer are electrically connected to each other.

6. An X-ray tube in which a cathode is heated in a housing sealed in vacuum to emit electrons, and the electrons are focused on an anode target through a grid electrode and a focusing electrode, thereby generating X-rays, characterized in that

said grid electrode has a plate-shaped base portion with an opening, at a center thereof, through which the electrons pass, and

a cylindrical portion which is integrally molded with said base portion from the same material as that of said base portion, is formed cylindrical so the electrons directed from said opening toward said focusing electrode can pass therethrough, and has one end abutting against said focusing electrode.

7. An X-ray tube according to claim 6, characterized in that said end of said cylindrical portion and said focusing electrode fit with each other through a fitting portion.

8. An X-ray tube according to claim 6, characterized in that said cylindrical portion has a hole in a circumferential wall thereof through which an inside and an outside of said cylindrical portion communicate with each other.

9. An X-ray tube according to claim 6, characterized in that said focusing electrode, said housing, and said grid electrode are electrically connected to each other.