JPS6028145A - Rotating anode x-ray tube - Google Patents

Abstract

PURPOSE:To almost eliminate generation of lowering performance in a getter by sealing the flange of a cathode stem and a glass envelope, while injecting inert gas into a tube from a exhaust tube. CONSTITUTION:A metal pipe 4 previously mounted on a turning anode 2 and a metal ring 5 previously sealed in the glass envelope 1 are partially welded at a weld portion 6 so as to exhaust the gas in the tube to the outside. Next, a cathode having the getter 10 previously mounted on the stem 7 of glass is welded and sealed to the end of the glass envelope 1 at the periphery portion of the stem flange 11. At this time, the inert gas, such as Ar, is injected through the exhaust tube 12 provided in the stem 7 from the outside of a bulb. The inert gas flows out from the welded portion 6 to the outside of the bulb, after filling the inside of the glass envelope 1 and flowing by itself, and thereby the getter has no possibility to deteriorate its performance by heated air.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotating anode X-ray tube that uses a glass envelope and can be assembled without impairing the performance of a getter attached to the cathode side.

[Background of the invention]

Traditionally, materials such as glass, ceramics, and metals have been used as the envelope of rotating anode X-ray tubes, but among these, glass has good electrical insulation against the high voltage applied to the X-ray tube, and It is the most widely used because it is easy to manufacture. However, glass is thermally weak compared to ceramics and metals (such as in rotating anode X-ray tubes with large load capacity).
If a large amount of heat is generated inside the tube, gas will be released from the glass envelope and the vacuum inside the tube will deteriorate.
Since there is a problem of shortening the lifespan, a high-performance getter is used to prevent deterioration of the degree of vacuum. As the getter, a non-evaporable getter such as Ba, Zr-, TI% Ta, etc. is used, but the getter is exposed to air during the assembly process when attaching electrodes such as the cathode and anode to the glass envelope of the X-ray tube. There was a problem in that the getter performance deteriorated due to adsorption of substances such as substances. The main reason for this is that in order to attach the electrode, glass is melt-sealed or metal is welded, and the heat generated at that time is transmitted to the getter.
This is because the getter adsorbs gas. In order to compensate for the drop in getter performance, some methods used a large amount of getter or attached the getter to parts of the target, focusing electrode, etc. that were as far away as possible from the melted or welded part, but these methods were effective in preventing the drop in getter performance. could not be said to be sufficient. The reason for this is that due to the structure of a rotating anode X-ray tube, the anode must be attached to the envelope first, and the cathode later. Since the envelope is heated for melt sealing and to remove strain from the melt seal, the problem remains that the air sealed inside the bulb gets heated and the getter performance inevitably deteriorates due to the heat. This is because it has been

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotating anode X-ray tube that hardly causes any deterioration in getter performance when assembling the X-ray tube.

[Summary of the invention]

In order to achieve the above object, in the present invention, a metal ring previously sealed to one end of the glass envelope and a metal cylinder previously welded to the outer end of the rotating anode fixing part are fitted and welded together. After attaching the rotating anode to the one end of the glass envelope, a getter is disposed within the cover, and a cathode having a stem with an exhaust pipe which also serves as an inert gas ventilation pipe is inserted from the exhaust pipe. The cathode stem was attached to the other end of the glass envelope by sealing the flange of the cathode stem and the glass envelope while flowing an inert gas into the tube. In addition, the inert gas is allowed to pass through the welded part between the metal ring and the metal tube on the rotating anode side so that the inert gas fills the glass envelope and is exhausted from the rotating anode mounting section. After the cathode and glass envelope are partially welded, the cathode and the glass envelope are sealed, and after this sealing, the welded part is hermetically welded, or the fixed part of the rotating anode is connected from inside the tube to outside the tube. A communicating hole was provided, an inert gas exhaust pipe was attached to the outer end of the tube, and this exhaust pipe was hermetically sealed after the sealing work of the cathode and the glass envelope was completed.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the invention. A rotating anode 2 is fixed to one end of the glass envelope 1 by welding a metal tube 4 attached to its fixing part 3 in advance and a metal ring 5 sealed to the glass envelope 1 in advance at a welding part 6. . At this time, the welded portion 6 is not completely welded, but only partially welded to an extent that can support the rotating anode and to allow the gas inside the tube to be exhausted to the outside. Next, a cathode cover 9 equipped with a focusing electrode 8 is placed over the glass stem 7 , and a getter 10 is attached to the inside of the cathode cover 9 . Melt seal with the end.

When performing this melt-sealing and when removing strain from the glass after melt-sealing, an inert gas such as a meter is flowed from outside the tube through an exhaust pipe 12 provided in the stem 7. This inert gas fills the inside of the glass envelope 1, flows, and flows out from the welded portion 6 to the outside of the tube.

If you do the above, the inside of the glass envelope is filled with inert gas when the bulb is assembled, and it is constantly replaced with fresh inert gas, so when the getter is sealed with the cathode, the heated air There is no risk of performance deterioration. Note that the welded portion 6 on the anode side is entirely welded after the cathode side is sealed so as to be airtight. Further, the exhaust pipe 12 is of course used as a normal exhaust pipe in the evacuation work to evacuate the inside of the X-ray tube.

FIG. 2 shows another embodiment of the invention. A horizontal hole 13 and a vertical hole 14 are provided in the fixed part 3 of the rotating anode 2, and the horizontal hole 13 and the vertical hole 14 communicate with each other.
As an extension of this vertical hole 14, an inert gas discharge pipe 15 is further attached to the fixed part 3 in an airtight manner. The other parts are the same as in the case of FIG. Even if the glass envelope 1 and the cathode stem flange 11 are sealed after the glass envelope 1 and the rotary anode 2 are all airtightly welded together at the welding part 6, the air is discharged from the exhaust pipe 12 on the cathode side. The inert gas that is introduced passes through the inside of the glass envelope 1 and is discharged from the exhaust tube 15 to the outside of the X-ray tube, thereby preventing a rise in temperature of the getter and producing acid a, 2 thus preventing deterioration of the getter performance. It can be prevented. Note that the discharge pipe 15 is hermetically closed after the cathode side is sealed. If the above method is used, the weight of the rotating anode 2 is larger than that shown in FIG. Suitable when the gap between the inert girth and the inert girth is too small.

〔Effect of the invention〕

As explained above, according to the present invention, in a rotating anode X-ray tube using a glass envelope, deterioration of getter performance can be extremely minimized (suppressed) during assembly work for attaching internal electrodes to the envelope. It prevents deterioration of the vacuum level of the anode X-ray tube, and facilitates the production of large-load capacity rotating anode X-ray tubes.
It will be possible to maintain its lifespan for a long time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a sectional view of a rotary anode mounting portion of another embodiment of the present invention. 1-Glass envelope, 2-rotating anode, 3-fixing part, ll-
Metal tube, 5-metal ring, 6--welded part, 7-stem, 8
・-Focusing electrode, 9-cathode cover, 10-getter, 11-
Stem flange, 12-exhaust pipe, 13-horizontal hole 1, 14-
Vertical hole, 15-inert gas discharge pipe. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. The rotating anode is assembled by fitting and welding a metal ring previously sealed to one end of the glass envelope and a metal cylinder previously welded to the outer end of the rotating anode fixing part. After being attached to the one end of the glass envelope, a getter is disposed within the cover, and a cathode having a stem with an exhaust pipe that also serves as an inert gas ventilation pipe is installed, and an inert gas is introduced into the pipe from the exhaust pipe. A rotary anode X-ray tube characterized in that the flange of the cathode stem and the glass envelope are sealed while the cathode stem is being poured into the glass envelope, so that the tube is attached to the other end of the glass envelope. 2.) With the welded part of the metal ring and metal cylinder on the anode side partially welded to the extent that inert gas can pass through, seal the cathode and the glass envelope, and after this sealing. The rotating anode X-ray tube according to claim 1, wherein the welded portion is hermetically welded. 3. Make a hole in the fixed part of the rotating anode that leads from the inside of the tube to the outside of the tube, attach an inert gas exhaust pipe to the outside end of the tube, and connect this exhaust pipe after sealing the cathode and the glass envelope. A rotating anode X-ray tube according to claim 1, wherein the rotary anode X-ray tube is hermetically sealed.