JP2001297725A - X-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape of a focusing electrode of a cathode of an X-ray tube with accuracy of dimension easily secured and with high productivity. SOLUTION: A ceiling face of a cathode member 1 is formed flat through a cutting process, based on which plane, a center axis Y1-Y1 of a filament 2 is adjusted to the center of a focusing electrode 1a, a bottom face of which is formed by a cutting process into a plurality of planes 1a, 1b, 1c, at positions outside by a1 and inside by a2 from the center axis Y1-Y1 of each of which, vertical planes 1d, 1e are formed on top of the cathode member 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an X-ray tube apparatus,
In particular, it relates to the shape of the cathode focusing electrode.

[0002]

2. Description of the Related Art The configuration of a conventional X-ray tube apparatus is disclosed in Japanese Unexamined Utility Model Publication No. 1-127.
No. 162 is disclosed in FIG. The details are shown below. The X-ray tube apparatus comprises an anode section and a cathode section which are vacuum-enclosed in one envelope, and the anode section has a target which is generated from the cathode section and which is collided with accelerated and focused electrons. The part is composed of a valley surface composed of two inclined surfaces, a cathode member having a concave groove formed substantially perpendicular to each inclined surface, and a filament arranged so that its central axis coincides with the central axis of each concave groove. Made up of With this configuration, thermoelectrons generated from each filament can be focused to the same focal position.

[0003]

In the structure of the above-mentioned conventional cathode member, the converging groove, the central axis of the converging groove, and the central axis of the mounting hole of the filament anchor supporting the filament are aligned on the inclined surface. It had to be formed. Since a slight displacement on the inclined surface of the machining process for forming the focusing electrode leads to a displacement of the X-ray generation position on the target, there is a problem that the machining process for securing the dimensional accuracy requires time and effort. An object of the present invention has been made in view of the above problems, and an object of the present invention is to provide a shape of a focusing electrode of a cathode of an X-ray tube device, which can easily secure dimensional accuracy and has high productivity.

[0004]

According to the present invention, there is provided an X-ray tube apparatus comprising: a cathode member having a plurality of focusing electrodes; and a plurality of filaments corresponding to the plurality of focusing electrodes. Wherein the focusing electrode is formed of a plurality of planes parallel to the top surface of the cathode member and a plurality of planes perpendicular to the top surface of the cathode member, and the surface perpendicular to the top surface of the cathode member is a longitudinal central axis of the filament. Characterized by being formed asymmetrically with respect to the position.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a cathode portion of an X-ray tube device according to the present invention. In FIG. 1, 1 is a cathode member, 1a
Are focusing electrodes formed on the side of the cathode member 1 facing the target along the longitudinal direction of the axis of the filament, 2a and 2b are filaments, 3 is a filament anchor, and 4 is an insulator. FIG. 2 is an explanatory diagram of the trajectories of thermoelectrons generated from the filament. In FIG. 2, 5 is the orbit of the thermoelectrons, 6 is the isoelectric field, 7 is the target of the anode, and YY is the central axis of the cathode member 1, Y1-Y1 is the central axis of each filament 2,
a1 is the width dimension of the space of the focusing electrode formed outside the central axis Y1-Y1 of the filament 2, and a2 is the central axis of the filament
The width dimension of the space of the focusing electrode formed inside Y1-Y1 is shown.

Next, an example of a method for processing the cathode structural member of the present invention constituted by the above components will be described. First, the cathode member
The upper surface of 1 is formed by cutting into a plane, and the mounting hole of the filament 2 is drilled symmetrically with respect to the central axis Y-Y, and the focusing electrode 1a is formed perpendicularly with respect to this plane. End mill the part. The surfaces to be end milled include surfaces 1a, 1b, and 1c that are parallel to the upper surface of the cathode member 1 and have different depths, and surfaces 1d and 1e that are perpendicular to the upper surface of the cathode member 1. The processing of the focusing electrode 1a is performed on an axis Y1-Y1 having a width a1 outside the center axis Y1-Y1 and a width a2 inside.
Left and right asymmetric with respect to the center. When the processing of the focusing electrode 1a is completed, counterboring processing for mounting the boss of the insulator 4 is performed.

[0007] The filament 2 and the filament anchor 3 are joined and fixed by spot welding or laser welding, and the joined and fixed filament anchor 3 is passed through a hole of the insulator 4 and similarly fixed to the cathode member 1 by spot welding or laser welding.

Next, the trajectory of thermoelectrons generated from the coil portion of the filament 2 by application of the filament heating current, focused on the target 7 by the X-ray tube voltage applied between the anode and the cathode, and generating X-rays will be described. . In FIG. 2, the thermoelectrons 5 generated from the filament 2 a are changed in direction by an electric field and travel in the space of the focusing electrode 1 a, that is, travel in a direction orthogonal to each of the isoelectric lines 6.
Focus at the focus 7 of the target. As shown in FIG. 2, the shape and the size of the focusing electrode 1a of the cathode 1 are set such that the space of a1 is narrow outside the central axis Y1-Y1 and the space of a2 is wide inside, and YY
By providing the protrusions on the axis, the thermoelectrons 5 are generated from the coil portions and bent inwardly toward the target 7 to be focused. As a result, thermionic electrons 5 having a high density can collide with each other, and X-rays necessary for a clear X-ray image can be obtained. Focusing electrode of cathode when tube voltage is applied
In the space 1a, the isoelectric field lines 6 as shown in the figure are generated by the surfaces 1a to 1e of the focusing electrode 1a and the edges formed by the surfaces. This isoelectric field line 6 is formed by the edge of the upper surface of the cathode member 1 and the projection 1e of the YY axis.

[0009]

According to the present invention, the top surface of the cathode member of the X-ray tube apparatus for obtaining X-rays necessary for a clear X-ray image is formed as a flat surface, and the space of the focusing electrode is perpendicular to the flat surface. Are formed on the surface in the orthogonal direction, so that they can be integrally formed with high accuracy, and there is an effect of greatly improving the productivity of the cathode of the X-ray tube device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cathode portion of an X-ray tube device according to the present invention.

FIG. 2 is a diagram for explaining orbits of thermoelectrons.

[Explanation of symbols] 1 cathode, 1a left and right asymmetric focusing electrode, 2 filament, 3 filament anchor, 4 insulator, 5 thermoelectron, 6
Isoelectric field, 7 targets, Y-Y Cathode 1 center axis, Y1
−Y1 the central axis of each filament 2 or the central axis of the focusing electrode space, a1 the central axis of the focusing electrode space, the width dimension of the focusing electrode space formed outside Y1−Y1, the a2 focusing electrode space , The width of the space of the focusing electrode formed inside Y1-Y1

Claims (1)

[Claims] 1. An X-ray tube apparatus comprising a cathode member having a plurality of focusing electrodes formed thereon and a plurality of filaments corresponding to the plurality of focusing electrodes, wherein the focusing electrode comprises a plurality of filaments parallel to a top surface of the cathode member. And a plurality of planes perpendicular to the upper surface of the cathode member, and the surface perpendicular to the upper surface of the cathode member is formed asymmetrically with respect to the position of the longitudinal central axis of the filament. X-ray tube device.