JP2000057983A - X-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for restricting the lowering of degree of vacuum in a getter part capable of sufficiently adsorbing the gas by arranging the getter part in a recessed part of a member for supporting a negative electrode part inside of a case. SOLUTION: A glass stem 4 holds the whole of a negative electrode structure and secures vacuum tightness, and a lead wire 5 for applying electrical potential from outside is sealed in a vacuum tube. A getter part 7 is supported by the lead wire 5 at a tube inside through a nickel wire 6 in the condition that a vapor spraying direction thereof is directed to the inner wall side of a cylinder 2 so as to prevent the generation of a contact of the getter part 7 with the peripheral part of a sheath 3. In the getter part 7, barium or the like is sealed in a columnar container made of nickel or the like formed into a recessed part. The getter part 7 is sealed after evacuating a bulb of an X-ray tube device so as to maintain the inside of the tube at a high degree of vacuum. A vapor spraying area is widened so as to increase the adsorbed amount in total, and a room for adsorbing further much gas is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray tube apparatus having a getter for adsorbing minute gas in an envelope, and more particularly to an X-ray tube improved so as to increase the deposition area of the getter. It concerns the device.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a mounting structure of a getter portion in a conventional X-ray tube device. In a conventional X-ray tube device, a steam-type getter is disposed in the vicinity of a lead wire enclosing portion in a direction perpendicular to the stem axis within approximately a diameter interval of 4 to 9 lead wires circumferentially arranged on a glass stem in a cathode assembly. After the X-ray tube device is evacuated to vacuum and sealed off, the getter is heated by applying electricity from the outside to the lead wire to which the two directions of the getter are connected, and the glass stem is vaporized. Then, an evaporation film of about 200 mm ² is formed on the glass surface.

The getter-deposited film has a function of adsorbing a gas released due to a rise in the temperature of components in the tube or a residual gas excited in the minute discharge space.

[0004]

However, in the prior art, the steaming type getter portion is located near the lead wire enclosing portion within substantially the diameter interval between 4 to 9 lead wires circumferentially arranged on the glass stem. in the axis-perpendicular direction is arranged蒸飛getter unit, because it was taking place to蒸飛to the lead wire enclosure direction glass surface, outgassing and due to the temperature rise of the tube parts without taken only deposition area of approximately 200 mm ² The amount of gas adsorbed and excited by the minute discharge was not sufficient.

[0005] Therefore, when the amount of generated gas that can be adsorbed is small and the adsorbing capacity is saturated, the degree of vacuum in the envelope gradually decreases, eventually causing a glow discharge, which may cause a withstand voltage failure. was there.

Further, in the case of a triode structure, that is, an X-ray tube device in which a potential difference of about 3,000 V is generated between adjacent lead wires, a grid lead is formed by vaporizing the getter portion on the glass surface in the direction of the lead wire enclosing portion. There is a problem that dielectric breakdown due to the getter portion deposited film easily occurs between the filament lead and the filament lead, and it may not be possible to cope with the problem simply by attaching a shielding plate for preventing evaporation near the root of the lead wire.

SUMMARY OF THE INVENTION The present invention has been made to solve at least one of the above problems, and an object thereof is to provide an X-ray tube in which a getter portion capable of sufficiently adsorbing gas suppresses a decrease in vacuum degree. It is to provide a device.

[0008]

According to the present invention, there is provided a cathode section for generating thermoelectrons, an anode section which is arranged opposite to the cathode section and collides the thermoelectrons to generate X-rays, An envelope that supports the anode section so as to be in a facing positional relationship and hermetically seals the cathode section and the anode section in a substantially vacuum state; and an outer casing provided on the cathode section in a direction in which the anode section is not located. An X-ray tube apparatus having a getter unit for adsorbing minute gas in an envelope, wherein the getter unit is disposed in a concave portion of a member supporting the cathode unit in the envelope. This is achieved by a tube device.

More specifically, the present invention relates to an X-ray tube apparatus, in which a lead wire for applying an electric potential from outside the tube does not come into contact with the sheath through a nickel wire so as to surround the sheath. An object of the present invention is to dispose the steam-type columnar getter toward the inner wall of the cylinder. As a result, about 2,000
and mm ^2, it is possible to secure a deposition area of a conventional 10-fold. This is because it is more substantial to increase the total absorption amount by increasing the evaporation area rather than increasing the adsorption efficiency per unit area of the deposited film, so that more gas is adsorbed. Can afford.

[0010] Further, even in the triode, since there is no vapor deposition near the root of the lead wire, a sufficient insulation resistance can be secured between the filament lead and the grid lead.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray tube apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main part of a cathode structure of an X-ray tube device according to the present invention. In FIG.
The cathode of the X-ray tube device faces the anode (not shown) and is vacuum-sealed in an envelope (not shown). A cylinder 2 for stabilizing the withstand voltage when a high voltage is applied is attached to the focusing assembly 1 and is supported by a sheath 3. The sheath 3 is fixed to a glass stem 4. The glass stem 4 secures the entire cathode component and maintains vacuum tightness, and a lead wire 5 for applying a potential from the outside to the inside of the vacuum tube is sealed. The steaming direction is supported toward the inner wall side of the cylinder 2 so that the getter portion 7 does not come into contact with the outer periphery of the sheath 3 via the nickel wire 6 inside the tube of the lead wire 5 via the nickel wire 6. . The getter portion 7 is enclosed in a columnar container made of a material such as barium and formed into a concave shape made of nickel or the like. Also, the getter unit 7 seals and cuts the tube of the X-ray tube device after evacuation to keep the inside of the tube at a high vacuum. Thereafter, a getter member enclosed in a concave container heated to about 900 ° C. by externally applying a current of, for example, 10 A for about 3 minutes to a lead wire to which the getter section 7 is connected is connected from the outside. Evaporation, vaporization, and uniform evaporation from the container opening direction to the inner wall of the cylinder 2 can form a vapor deposition area about 10 times as large as the conventional structure as described above. This deposited film has the function of physically adsorbing CO, N ₂ and H ₂ gases. For this reason, it is possible to adsorb the gas released due to the temperature rise of the components in the tube and the residual gas excited by the minute discharge over a long period of time, to maintain the inside of the tube at a high vacuum, and to prolong the service life.

Further, the structure in which the getter portion is evaporated to the inner wall portion of the cylinder eliminates the formation of a getter portion deposition film around the lead wire. As a result, the dielectric breakdown between the filament lead and the grid lead, which has been a problem in the triode, does not occur.
Stable operation is possible even with a wire tube device.

As described above, since the cathode structure of the X-ray tube device of the present embodiment has the above-described structure, a high degree of vacuum can be maintained for a long time, and the degree of vacuum can be reduced. A stable X-ray tube device without accompanying discharge can be provided. Further, in the X-ray tube device having the triode structure, sufficient insulation resistance can be secured between the filament lead and the grid lead.

[0014]

The present invention has the effect of providing an X-ray tube apparatus in which a lowering of the degree of vacuum is suppressed by a getter portion capable of sufficiently adsorbing gas.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cathode structure of an X-ray tube device according to the present invention.

FIG. 2 is a diagram showing an example of a conventional getter unit mounting structure.

[Explanation of symbols]

 2 Cylinder 7 Getter

Claims (1)

[Claims] 1. A cathode section for generating thermoelectrons, an anode section disposed opposite to the cathode section to generate X-rays by colliding the thermoelectrons, and a positional relationship between the cathode section and the anode section. An envelope that supports the cathode portion and the anode portion in a substantially vacuum state while supporting the cathode portion and the minute gas in the envelope provided in the cathode portion in a direction in which the anode portion is not located. In an X-ray tube device having a getter unit to be adsorbed,
An X-ray tube apparatus, wherein the getter section is provided in a concave portion of a member supporting the cathode section in the envelope.