JPH03201354A - x-ray image tube - Google Patents

Abstract

PURPOSE:To obtain a X-ray image tube having high assembly accuracy on the fixing arrangement with a focusing electrode and a mask by fixing a mask, which is a part of an anode shape, via the inner side wall of a supporting ring connected to an envelope and the horizontal expanded part of an anode. CONSTITUTION:A mask 18c' additional serving as a part of an anode shape is fixed to a valve side supporting ring or covering 26a by means of a screw 18e to keep a distance L1 to a focusing electrode 18b to maintain 11 constant. A tapped hole on the mask side is larger than a screw axis and has room, and a coaxial relation is made to be constant when the mask 18c' and an anode 18a are fixed together. This can obtain a X-ray image tube having high assembly accuracy.

Description

[Detailed description of the invention] (b) Industrial application field INDUSTRIAL APPLICATION This invention is utilized in the field of an image sensor.

The present invention relates to an X-ray image tube, and particularly to improvements in its anode portion.

(b) Prior art In general, X-ray image tubes, such as X-ray fluorescence amplification tubes, are
An input surface 14 is disposed inside the input side of the vacuum envelope 10, which is configured as shown in the figure and is mainly made of glass.
Inside the output side, an anode 18 and an output surface 20 are arranged. Further, a focusing electrode l'I3 is provided along the side wall inside the vacuum envelope 10. In addition, 12
is an input window.

The X-rays emitted from the X-ray source pass through the subject and reach the input surface 1.
4. The X-ray image transmitted by the subject is converted into a photoelectron image by the incident surface 14, and this photoelectron image is further accelerated and focused by the anode 18 and the focusing electrode 16, and enters the output surface 20, where the photoelectron image is converted into a visible image. be done.

By the way, the output surface 20 is connected to the vacuum envelope 10 as shown in the illustrated example.
However, in this case, there is a lot of reflection of the emitted light from the output surface 20, and the contrast is poor. For this reason, in recent years, X-ray image tubes have been developed that use a separate vacuum-tight window as the substrate that forms the output surface and require a window support ring to support it. 6
The device disclosed in Japanese Patent No. 4-76645 is illustrated in FIG.

In this drawing, 24 is a vacuum-tight window, 26 is a window support ring or Kovar ring, 22 is an output phosphor layer, and the window support ring 26 is composed of two, one of which is the vacuum envelope 10. The other is connected to the vacuum-tight window 24.

By the way, the above-mentioned patent publication describes the improvement of the output surface.
We are proposing a so-called vacuum-tight X-ray image tube.
There is no mention of how the anode, especially the anode, is configured or fixed in relation to the mask that regulates the trajectory of photoelectrons.

Prior to vacuum-tight X-ray image tubes, ie, those in which the output surface was formed from the rear part of a vacuum envelope (bulb), there were conventional examples shown in FIGS. 2 and 3.

In the example shown in FIG. 2, a spring plate is inserted between the neck of the bulb 10 and the anode 18 at the arrow 8A, and the anode 18 is
8 is fixed.

In the example shown in FIG. 3, a ceramic rod 18d is suspended from the focusing electrode 18b, and the anode 18a is connected to the ceramic rod 18d.
Fixed by Further, a mask 18c for regulating the trajectory of photoelectrons is placed and fixed inside the anode 18a.

In such a conventional example, the anode 18a is used as a part of an electron lens to form an image of the photoelectron beam from the input surface side, and the mask 18c is placed inside the anode 18a to form an image in the image forming part. It is used as a means to remove images caused by unnecessary scattered electron beams, etc.

Note that in the vacuum-tight X-ray image tube as shown in FIG. 4, the mask has two support rings 26a, although not shown.
It seems that it is sandwiched between 26b.

SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray image tube of the type that uses a vacuum-tight window constituting an output surface with low reflection of emitted light, and which has high assembly precision with respect to fixed arrangement with a focusing electrode and a mask.

(d) Means for solving the problem The above purpose is to provide an input surface on the X-ray input side in the vacuum envelope, an anode on the output side, and a focusing electrode on the inner wall of the envelope. A vacuum-tight window is used as an output surface at the rear of the envelope, an output phosphor layer is formed on its inner surface, and a support ring connected to the rear of the envelope and a vacuum-tight window are used to support the vacuum-tight window. In an X-ray image tube having another support ring, by fixing this as a mask forming part of the anode shape via the inner wall of the support ring connected to the envelope and the horizontally expanding part of the anode, achieved.

(E) Function: Make the conventional mask 11f5L as an extension of the anode as part of its shape. The mask forming part of the anode shape is fixed using a vacuum-tight window or a window support or a copper ring at the glass output end.

Connecting the main anode shape to such a mask,
Fix it.

(f) Example A preferred embodiment of the invention will be explained based on the drawings.

FIG. 5 shows a conventional example, in which the anode 18a is sandwiched and fixed between two support rings 26a and 26b.

Since the distance between the electrodes and the coaxial relationship between the electrodes shown at 11.12 in the figure cannot be precisely maintained, there is a problem in that the assembly accuracy of the electron lens cannot be improved. Although it is not impossible to maintain precision, manufacturing such parts requires a relatively high cost.

Therefore, FIG. 1 is a sectional view of essential parts showing one embodiment of the present invention.

According to the invention, the valve side support ring or cover ring 2
A mask 180 that also serves as a part of the anode shape for 6a
' is fixed with a screw 18e to maintain the distance L1 from the focusing electrode 18b, making the distance 11 constant. The screw hole on the mask side has a larger margin than the screw shaft so that the coaxial relationship 12 can be kept constant when fixing the mask 180' and the anode 18a.

Fortunately, the positional relationship between the aperture of the mask 180' and the focusing electrode 18b does not require any degree of accuracy, so the configuration of the present invention can improve the accuracy or image of the electron lens.・Does not disturb the resolution of the intensifier. Furthermore, the accuracy of the parts is not required to be as high as that of an integral part.

(g) Effects According to the present invention, the anode section is divided into two parts, the main anode section and the mask section that bears part of the shape of the anode section,
By combining them to function as an anode section, it is possible to easily improve the assembly accuracy of the electrodes, that is, the accuracy of the electron lens.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a main part showing an embodiment of the present invention, Fig. 2 is a half-sectional view of a general X-ray image tube, and Fig. 3 is a cross-sectional view of a main part of an X-ray image tube having a focusing electrode. 4 are sectional views of essential parts of a vacuum-tight type, and FIG. 5 is a sectional view of essential parts of a conventional example. 18a is an anode, 18b is a focusing electrode, 18c is a mask, 18e is a fixing screw, 22 is an output phosphor, 24 is a vacuum-tight window or glass substrate, and 26 is a support ring.

Claims (1)

[Claims] 1. An input surface is provided on the X-ray input side in the vacuum envelope, an anode is provided on the output side, a focusing electrode is provided along the inner wall of the envelope, and an output surface is provided at the rear of the envelope. An X-ray image tube in which a vacuum-tight window is used, an output phosphor layer is formed on the inner surface thereof, a support ring is connected to the rear part of the envelope, and another support ring is provided to support the vacuum-tight window. An X-ray image tube according to claim 1, characterized in that the mask forming part of the anode shape is fixed via the inner wall of the support ring connected to the envelope and the horizontal extension of the anode.