JPS6035169Y2 - x-ray tube - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an X-ray tube, and particularly relates to an improvement in the cathode structure thereof.

In the manufacturing process of the X-ray tube, generally, as shown in FIG. 1, the storage gas in the cathode structure 11, that is, the focusing electrode 12 having a cathode therein, and the support cover 13 made of a conductive plate that supports the cathode structure 11 is heated by high-frequency induction heating. It is heated and exhausted by the power source 14 and its coil 15.

In the figure, reference numeral 16 is a vacuum vessel, 17 is a rotating anode, 18 is a target, and 19 is an exhaust pipe.

Note that the target 18 is degassed by high-frequency induction heating or electron beam impact from a cathode.

This X-ray tube is effective when the vacuum vessel is made of a dielectric material such as glass or ceramic, but in recent years, vacuum vessels whose main parts are made of metal have been used for large-capacity X-ray tubes. However, this gas release method using high-frequency induction heating cannot be adopted.

Furthermore, accurate temperature control of the cathode structure for gas release is almost impossible as it cannot be directly observed from the outside.

This idea was made in view of the above circumstances,
The present invention provides an X-ray tube structure in which temperature control during gas discharge from the cathode assembly can be performed with relatively high precision, and which is particularly effective in a structure having a metal vacuum vessel portion.

Examples thereof will be described below with reference to the drawings.

Identical parts are designated by the same reference numerals.

As shown in Figures 2 to 5, the vacuum vessel of this X-ray tube includes a cylindrical metal vessel 21 with a large diameter in the center, a cathode side metal vessel 23 hermetically sealed to this at a welding point 22, and both sides. It consists of parts of a glass container 24, 25 which are hermetically welded together.

Inside the vacuum vessel, a rotating anode 27 having a target 26 on one side and a cathode structure (2) facing the rotating anode 27 are fixed.

Now, in the cathode assembly 11, a focusing electrode 30 having a cathode 29 therein is held at one end of a support cover 31 formed of a conductive plate.

The support cover 31 has a substantially flat front side with a wide area facing the target to alleviate electric field distribution, and a support cylinder 32 is fixed on the back side.

Therefore, electron-emitting filaments 34 are stretched over a relatively wide area in close proximity to the back side of the support cover 31 and the back side of the upper part of the cylinder 32.

The filament 34 may be a tungsten (W) wire, a thorium tungsten wire, or the like wound into a coil, and is stably held by a plurality of insulating supports 35, 35.

One end of the filament 34 is electrically connected to one of the lead wires 36 and 36 of the cathode 29, and the other end is independently led out of the tube as a lead wire 37, to which a heating power source 38 can be connected. It is.

Further, the focusing electrode 30, the support cover 31, and the cylinder 32 are short-circuited to each other and drawn out with one lead wire 39, so that a power source 40 can be applied.

When this X-ray tube is evacuated, the cathode 29 and gas venting filament 34 are heated by a source 41.38,
Further, a direct current or alternating current power source 40 is connected to the focusing electrode 30, support cover 31, and cylinder 32 to cause electron bombardment and discharge the occluded gas.

The heating temperature can be indirectly controlled while observing the impact electron flow at this time using the meter 42.

Further, the degree of electron impact, that is, the temperature and time of each of the focusing electrode and the support cover can be arbitrarily determined by controlling the power sources 38 and 41.

Note that the lower part of the cylinder 32, that is, the glass container part 2
It is also important to limit the position of the filament 34 to the upper part so that the temperature in the vicinity of the filament 5a does not increase undesirably too much.

This idea is particularly effective when applied to X-ray tubes in which the outer periphery of the cathode structure, especially the support cover, is surrounded by a metal vacuum container. Although high-frequency induction heating is not possible and the internal temperature cannot be observed directly, by detecting the electron impact current, it is possible to convert the temperature for each tube type using this current, allowing for more accurate temperature control. .

This makes it possible to easily pump out different types of X-ray tubes at desired gas outlet temperatures at the same time using a single pumping device.

Furthermore, according to this invention, since the electron impact current is controlled, it has become possible to easily automate the exhaust.

In the above embodiment, the filament is also stretched on the back side of the cylinder 32, but it goes without saying that this may be omitted and the filament stretched only on the back side of the support cover.

[Brief explanation of the drawing]

Figure 1 is a schematic side view showing the exhaust state of a general X-ray tube.
FIG. 2 is a longitudinal cross-sectional view showing an embodiment of this invention, FIG. 3 is a cross-sectional view of the main part thereof, and FIGS. 4 and 5 are examples of its connection diagrams. 21... Vacuum container, ■... Cathode structure,
29...Cathode, 30...Focusing electrode, 31...Support cover 34 @*@mam filament.

Claims (1)

[Scope of utility model registration request] A supporting cover made of a plate-like conductive member is provided to support the assembled structure of the electron beam generating cathode and the focusing electrode, facing the rotating anode target, and the vacuum container wall surrounding the target and a portion of the supporting cover is made of metal. In the X-ray tube formed, an electron-emitting filament is stretched on the back side of the support cover while being electrically insulated from the support cover, and lead wires are independently extended from the filament and the support cover to the outside of the tube. An X-ray tube characterized by being drawn out.