JPH0523328A - Rotary cathode x-ray tube - Google Patents

Abstract

(57) [Abstract] [Purpose] Abrasion dust generated by friction between a slip ring and a brush sliding as a power supply means to a rotating cathode was prevented from scattering into a vacuum container to improve withstand voltage performance. The purpose is to obtain a rotating cathode X-ray tube. A slip ring 8 disposed on a ring-shaped rotating body 7 having a cathode rotatably supported in an annular vacuum container 1 and a brush 9 slidably contacting the slip ring 8 are made of a magnetic material.
The permanent magnet 10 was arranged in the vicinity of the sliding contact portion of both.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray CT apparatus, and more particularly to a rotating cathode X-ray tube used in an ultra-high speed X-ray CT apparatus for performing high-speed imaging.

[0002]

2. Description of the Related Art In a rotary cathode X-ray tube, a ring-shaped anode 2 is fixed in an annular vacuum container 1 as shown in FIG. 2 and is electrically connected to an external high voltage generator (not shown). ing.

Reference numeral 7 denotes a ring-shaped rotating body which is rotatably supported by a magnetic bearing 5 and is electromagnetically coupled to the stator 6 so as to be rotationally driven. The rotating body 7 is opposed to the ring-shaped anode 2 described above. At least one cathode 3 composed of a focusing electrode 3a and a filament 3b housed therein is disposed on the surface, and the cathode 3 and the rotating body 7 constitute a rotating cathode.

Reference numeral 8'denotes a slip ring fixed to the surface of the rotating body 7 facing the cathode 3 and electrically connected to the cathode 3, and 9'denotes a brush whose one end is in sliding contact with the slip ring 8 '. The output end of the other end to the outside of the vacuum container 1 is connected to a filament heating power source (not shown) and a high voltage power source (not shown), and power is supplied to the rotating cathode 3 by a slip ring method. . The slip ring 8'and the brush 9'have excellent lubricity in vacuum.
g, Cu, C, MoS2, etc. are used.

In the above structure, when power is supplied to the cathode 3 and a high voltage is applied between the anode 2 and the cathode 3, the thermoelectrons from the filament 3b are accelerated and focused to form a focus on the anode 2 X Lines are generated.

On the other hand, since the rotating body 7 rotates at a high speed by the rotating magnetic field of the stator 6, the focus moves at a high speed on the focal track of the anode 2 and the subject positioned in the cavity of the vacuum container 1 is exposed. X-rays can be emitted from all directions.

[0007]

As described above, the power feeding from the outside to the rotating cathode 3 is of the slip ring type, and the brush 9'connected on the slip ring 8'to an external power source is used.
Slides, the sliding friction between the two causes abrasion dust, and these abrasion dust scatter and adhere to the wall of the vacuum container 1 and the insulators / electrodes, deteriorating the dielectric strength and stabilizing the X-ray generation characteristics. Lower. It should be noted that the rotor 7 and the vacuum are prevented so that the dust generated in the chamber B in which the slip ring 8 ′ and the brush 9 ′ are located does not flow into the chamber A in which the anode 2 and the cathode 3 which are partitioned by the rotor 7 face each other. Although measures such as narrowing the gap with the container 1 and providing an inter-room separation plate have been taken, it is impossible to eliminate the gap for rotating the rotating body 7 in any case.

The present invention has been made in view of the above reasons, and prevents abrasion dust generated by sliding friction between a slip ring and a brush from scattering into a vacuum container to improve and stabilize dielectric withstanding voltage performance. Another object of the present invention is to provide a rotating cathode X-ray tube.

[0009]

In order to solve the above-mentioned problems, the present invention provides a rotary cathode X-ray tube in which power is supplied to a rotary cathode by a slip ring system consisting of a slip ring and a brush. The brush is made of a magnetic material, and a permanent magnet is arranged near the sliding contact between the slip ring and the brush.

[0010]

According to the present invention, since the slip ring and the brush are magnetic substances, the abrasion dust generated by the sliding friction between them is magnetic dust. Therefore, the permanent magnet arranged at the sliding contact portion between the slip ring and the brush attracts and holds the magnetic dust. As a result, it is possible to completely prevent the abrasion dust from scattering and adhering to the wall of the vacuum container, the insulator and the electrode, and the insulation withstand voltage performance of the X-ray tube is stabilized and the X-ray generation characteristics are not deteriorated. , Can always generate stable X-rays.

[0011]

EXAMPLE An example of the present invention will be described with reference to FIG. The same components as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 8 is a slip ring, and 9 is a brush, which is made of a magnetic material such as Ni, Fe and alloys thereof. Reference numeral 10 denotes a permanent magnet arranged at a position where the slip ring 8 and the brush 9 are in sliding contact with each other. In the embodiment, a U-shaped permanent magnet is used so as to cover the periphery of the sliding contact portion.
It is attached to the vacuum container 1 via a support member (not shown).

The wear dust of the magnetic substance generated by the sliding friction between the slip ring 8 and the brush 9 can be completely prevented from being attracted by the permanent magnet 10 and scattered and attached to the wall of the vacuum container, the insulator and the electrode. . Since the magnetic field of the permanent magnet 10 that collects the abrasion dust of the magnetic body is stable, the influence on the magnetic bearing 5 can be compensated by its control means, and the rotating shaft of the rotating body 7 can be accurately controlled. Therefore, the correspondence between the anode 2 and the cathode 3 can be accurately performed.

[0014]

As described above, the wear dust generated by using the slip ring and the brush as the magnetic substance can be adsorbed by the permanent magnet, and the wear dust can be scattered and adhere to the vacuum container wall or the insulator. It is possible to obtain a rotating cathode X-ray tube in which the dielectric strength of the vacuum container is stable and X-rays are always stable.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a rotary cathode X-ray tube according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is X- of (a).
It is an X'view.

FIG. 2 is a diagram showing a schematic structure of a conventional rotating cathode X-ray tube,
(A) is sectional drawing, (b) is a YY 'view of (a).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vacuum container 2 ... Anode 3 ... Cathode 3a ... Focusing electrode 3b ... Filament 5 ... Magnetic bearing 6 ... Stater 7 ... Rotating body 8, 8 '... Slip ring 9, 9' ... Brush 10 ... Permanent magnet

Claims (1)

Claim: What is claimed is: 1. A ring-shaped anode fixed in an annular vacuum container, and a cathode having an electron beam emitting portion facing the ring-shaped anode are arranged on a ring-shaped rotating body. In a rotating cathode X-ray tube provided with a rotating cathode and a slip ring and a brush as a power feeding means to the rotating cathode, the slip ring and the brush are made of a magnetic material, and a permanent magnet is provided in the vicinity of a sliding contact portion between the slip ring and the brush. A rotary cathode X-ray tube characterized by being provided with.