JPH0660956U - X-ray tube device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an X-ray tube device having a long life, which prevents a decrease in creeping withstand voltage of a vacuum envelope. An X-ray tube device in which a cathode 2 and an anode 3 are arranged to face each other in a vacuum envelope 1, and a portion between the cathode 2 and the anode 3 and facing an X-ray radiation window 9 Also, by forming a protrusion 1a toward the center of the vacuum envelope 1 on the inner wall surface of the vacuum envelope 1 near the cathode side, the filament 4
The metal evaporated from the target 6 forms a portion on the inner wall of the vacuum envelope 1 that is hard to adhere to the surface of the vacuum envelope 1 to maintain the creeping withstand voltage of the vacuum envelope 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an X-ray tube device used in the medical field and the like.

[0002]

[Prior art]

 A schematic configuration of a conventional X-ray tube apparatus will be described by taking the rotary anode X-ray tube apparatus shown in FIG. 5 as an example. This rotary anode X-ray tube device is provided with a fixed cathode 2 and a rotary anode 3 which are arranged to face each other in a vacuum envelope 1 made of glass. The cathode 2 is provided with a filament 4 made of Tungsten that emits thermoelectrons. Further, the anode 3 is provided with a disk-shaped target 6 whose surface is made of tungsten and which is connected to the motor rotor 5. The motor rotor 5 is rotationally driven at high speed by a motor stator 7 arranged outside the vacuum envelope 1. The vacuum envelope 1 is housed in a casing 8 lined with lead to shield X-rays.

In the above-described rotary anode X-ray tube device, when the filament 4 is supplied with electric power and a high voltage is applied between the cathode 2 and the anode 3, the thermoelectrons A emitted from the filament 4 are generated at high speed. The target 6 of the rotating anode 3 collides, and X-rays B are generated from this target 6. The X-ray B is radiated to the outside through the vacuum envelope 1 and the X-ray radiation window 9 provided in the casing 8.

[0004]

[Problems to be solved by the device]

 By the way, in general, the X-ray tube device prevents the release of the adsorbed gas (sputtering) from the target 6 due to the collision of the accelerated thermoelectrons with the target 6, and also in the vicinity of the cathode 2 and the anode 3. In order to prevent discharge, the vacuum envelope 1 is evacuated to a high vacuum so that there is no residual gas in the vacuum envelope 1.

However, the conventional X-ray tube device has the following problems even though the vacuum envelope 1 is evacuated to a high vacuum. This will be described below with reference to FIG. During the driving of the X-ray tube device, the temperature of the focal planes of the filament 4 and the target 6 becomes high, so tungsten evaporates from the filament 4 and the target 6 as shown by the arrow 10 in the figure, and long By using the period, the vapor deposition layer 11 of tungsten is formed on the inner wall portion of the vacuum envelope 1 facing the X-ray emission window 9.

When such a vapor deposition layer 11 is formed, the creeping withstand voltage of the vacuum envelope 1 is lowered, and the path indicated by the arrow 12 in FIG. 6, that is, the cathode 2 and the vacuum envelope is shown. A discharge is likely to occur between the inner wall of No. 1 and the inner wall of the vacuum envelope 1 and the anode 3. When such a creeping discharge occurs, not only the generation of X-rays is interrupted, but also the inner surface of the vacuum envelope 1 is melted and gas is released, which deteriorates the withstand voltage performance in the vacuum envelope 1. , The life of the X-ray tube will be reached.

The present invention has been made in view of such circumstances, and prevents the creeping withstand voltage of the vacuum envelope from lowering due to the evaporation of metal from the filament or the target, and extends its life. It is an object of the present invention to provide an X-ray tube device capable of performing the above.

[0008]

[Means for Solving the Problems]

 The present invention has the following configuration in order to achieve the above object. That is, the present invention relates to an X-ray tube device in which a cathode and an anode are arranged to face each other in a vacuum envelope, and a vacuum envelope between the cathode and the anode and closer to the cathode than the X-ray tube transmission region. A protrusion is formed on the inner wall surface of the container toward the center of the vacuum envelope.

[0009]

[Action]

 The operation of this device is as follows. That is, the metal evaporated from the filament of the cathode while the X-ray tube device is driven adheres to the cathode side surface of the protrusion of the vacuum envelope, but the anode side of the protrusion shadows the filament. Therefore, the vapor deposition layer due to the evaporation of the filament is not formed on this surface. Further, the metal evaporated from the target of the anode adheres to the side surface of the anode of the protruding portion, but the cathode side surface of the protruding portion becomes a shadow on the target, so that a vapor deposition layer due to evaporation of the target is not formed on this surface. . Due to the presence of the protruding portion, the portion where the vapor deposition layer is not formed increases and the creeping discharge path between the cathode and the anode also becomes long. The surface withstand voltage of the enclosure is maintained and the life of the X-ray tube device is extended.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of a rotary anode X-ray tube device according to an embodiment, and FIG. 2 is a sectional view taken along the line CC of FIG. In FIGS. 1 and 2, the same reference numerals as those shown in FIGS. 5 and 6 are the same components as those of the conventional example, and thus detailed description thereof will be omitted.

The feature of the present embodiment is that a protrusion 1 a directed toward the center of the vacuum envelope 1 is provided on the inner wall surface of the vacuum envelope 1 between the cathode 2 and the anode 3. The protruding portion 1a is formed integrally with the vacuum envelope 1 made of glass. The protrusion 1a is set at a height that does not hinder the emission of the thermoelectrons A from the filament 4, and is formed closer to the cathode than the X-ray radiation region so as not to hinder the radiation of the X-ray tube B. ing. The protrusion 1a does not necessarily have to be provided on the entire circumference of the vacuum envelope 1, and may be formed on a portion where a creeping discharge easily occurs, that is, on the inner wall portion of the vacuum envelope 1 near the filament 4. Specifically, it may be provided within a range of 60 to 80 degrees around the portion facing the X-ray emission window 9.

The operation of this embodiment will be described with reference to FIG. The tungsten vaporized from the filament 4 of the cathode 2 while the rotating anode X-ray tube device is driven adheres to the inner wall surface of the vacuum envelope 1 on the anode side, which is slightly away from the protrusion 1a. The side surface D on the anode side of the protruding portion 1a which is shaded with respect to No. 4 is not adhered. Further, the tungsten evaporated from the target 6 of the anode 3 adheres to the side surface of the protrusion 1a on the anode side and the inner wall surface of the vacuum envelope 1 on the cathode side slightly apart from the protrusion 1a. It is not adhered to the cathode side surface E of the shadowed protrusion 1a.

As described above, the presence of the protruding portion 1a increases the number of portions where the vapor deposition layer is not formed, or the number of portions where the vapor deposition layer is slightly formed (portions indicated by reference characters D and E in FIG. 3), and Since the creeping discharge path between the cathode 2 and the anode 3 also becomes long, even if the X-ray tube device is used for a long period of time, the creeping discharge is less likely to occur because the creeping withstand voltage of the vacuum envelope 1 is maintained. The life of the X-ray tube device is extended.

In the above-described embodiment, the X-ray tube device provided with one protruding portion 1a has been described as an example, but as shown in FIG. 4, a plurality of protruding portions 1a and 1b are formed. Good. With this configuration, the creeping withstand voltage of the vacuum envelope 1 can be maintained longer.

Further, in the embodiment, the rotary anode X-ray tube device is taken as an example, but the present invention can also be applied to a fixed anode X-ray tube device.

[0016]

[Effect of device]

 As is apparent from the above description, according to the present invention, the protrusion formed on the inner wall surface of the vacuum envelope forms a portion where the metal evaporated from the cathode filament or the anode target is not deposited. In addition, since the creeping discharge path becomes long, the creeping withstand voltage of the vacuum envelope can be maintained, and an X-ray tube device having a long life can be easily realized.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a rotary anode X-ray tube device according to an embodiment.

FIG. 2 is a sectional view taken along the line CC of FIG.

FIG. 3 is an explanatory view of the operation of the X-ray tube device according to the embodiment.

FIG. 4 is a sectional view of an essential part of an X-ray tube device according to another embodiment.

FIG. 5 is a vertical cross-sectional view of a rotary anode X-ray tube device according to a conventional example.

FIG. 6 is a diagram for explaining the problems of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum envelope 1a ... Projection part 2 ... Cathode 3 ... Anode 4 ... Filament 6 ... Target

Claims (1)

[Scope of utility model registration request] 1. An X-ray tube device in which a cathode and an anode are arranged to face each other in a vacuum envelope, wherein the vacuum envelope is between the cathode and the anode and closer to the cathode than the X-ray tube transmission region. An X-ray tube device, characterized in that a projecting portion toward the center of the vacuum envelope is formed on the inner wall surface of the X-ray tube.