JPH04521Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an X-ray image tube, and more particularly to an improvement in the mounting structure of an optical system position adjustment member attached to an X-ray image tube.

[Technical background of the invention]

Generally, an X-ray image tube is an electron tube that converts radiation such as X-rays and γ-rays into visible images. This X-ray image tube is provided with an input fluorescent surface for converting an X-ray image into a visible image at one end of the vacuum envelope,
A photocathode that emits photoelectrons according to the strength of the visible image light, a focusing electrode and an anode that accelerate and focus the photoelectrons, and a further end of the vacuum envelope that is provided with the accelerated and focused photoelectrons. It is provided with an output fluorescent surface that emits light and presents a visible image thereon.

When such an X-ray image tube is used, the visible image appearing on the output fluorescent surface is transferred onto the film of an X-ray television camera or spot camera by an optical lens placed opposite the output fluorescent surface. In this case, the optical axis and parallelism of the output phosphor surface and the optical lens must be correctly matched, and the accuracy of this is due to the optical image formed on the film of an X-ray television camera or spot camera. This has a significant effect on the resolution and graphic distortion.

Therefore, in the past, X-ray image tubes were
It is configured as shown in the figure.

That is, this X-ray image tube 20 includes an enlarged portion 22 in which an input window 21 is formed at one end;
It has a vacuum envelope 25 made of glass and consisting of a small diameter cylindrical part 24 which is connected to the body via a shoulder part 23 and whose other end is closed. Although not shown, an input surface 26 consisting of an input fluorescent surface and a photocathode is provided close to and inside the input window 21 of the vacuum envelope 25.
Furthermore, a focusing electrode 27 is arranged on the inner wall of the vacuum envelope 25.

On the other hand, a cylindrical anode 28 is disposed at the end of the small-diameter cylindrical portion 24 made of glass, and an output fluorescent surface 29 is provided surrounded by the anode 28 . Further, a holding structure 30 is coaxially disposed on the outer wall surface of the shoulder portion 23 of the vacuum envelope 25 of the X-ray image tube 20. As is clear from FIG.
9 is integrally molded, and three position adjustment screw rods 31, 31, 31 are provided facing the output fluorescent surface 29 side, and the output fluorescent surface 29 is provided in the center thereof.
It has an opening 32 for extracting a visible image from the. This holding structure 30 is adhesively fixed to the outer wall surface of the shoulder portion 23 with an adhesive 33 so as to surround the small diameter cylindrical portion 24 . The position adjustment screw rods 31, 31, 31 of the holding structure 30 are inserted through the screw rods, and an annular support plate 34 is disposed thereon. After adjusting the parallelism to the output fluorescent surface 29 and the position of the annular support plate 34 with respect to the optical axis, that is, the tube axis X-X', using a dial depth cage and an optical microscope, ,31,31
Nuts 35, 35, 35, 3 screwed into
5, 35, and 35 are tightened and fixed. The X-ray image tube 20 that has been adjusted in this way is housed in a cylindrical casing 38 that has an X-ray shielding plate 36 and a magnetic shielding plate 37 attached to the inner wall, and is further placed facing the output fluorescent surface 29. An optical lens (not shown) is disposed at a position where the lens is used.

[Problems with background technology]

In the above-mentioned X-ray image tube, the nut 3 screwed onto the screw rods 31, 31, 31 is
When rotating 5, 35, 35, use a tool such as a nut turner. In this case, nuts 35, 35, 3
The part to which 5 is attached is usually an exhaust pipe for evacuating the X-ray image tube, an electrode for introducing alkali to obtain a photocathode on the input fluorescent surface, and a part for maintaining the vacuum inside the tube. A convex glass envelope enclosing the ion pump is placed. Therefore, when rotating and tightening the nuts 35, 35, 35 with a tool, the tool tends to touch these convex portions.
Requires extreme caution. If the glass were to receive an impact at this point, it would naturally crack or implode, potentially leading to a major accident.

Further, the distance from the output fluorescent surface 29 of the X-ray image tube 20 to the shoulder 23 is normally determined by a glass sealing operation. Glass sealing work involves many variations in dimensions, and the tolerance in the tube axis direction is generally around ±9 mm. Therefore, in order to accurately determine the distance from the output fluorescent surface 29 to the support plate 34, it is necessary to set the thickness of the support plate 34 in consideration of this tolerance. Otherwise, the screw rods 31, 31, 31 will protrude beyond the lens system mounting surface.
There may be cases where the lens system cannot be attached.

[Purpose of invention]

The object of this invention is to provide an X-ray image tube which eliminates the problems of the conventional art and allows adjustment of the distance and parallelism between the output fluorescent surface and the support plate to be carried out extremely easily and accurately.

[Summary of the idea]

This idea involves fixing an annular holding structure having a plurality of threaded holes in the tube axis direction to the output shoulder of the vacuum envelope, and screwing one end of a rotatable threaded rod having a flange into the threaded hole. X
It is a line image tube.

[Example of idea]

The X-ray image tube of this invention is constructed as shown in FIGS. 3 to 5. FIG. 3 shows the X-ray image tube 41 housed in the cylindrical housing 38, and FIGS. 5 is a perspective view and an exploded sectional view showing the vicinity of the holding structure.

In other words, the same parts as in the conventional example are given the same reference numerals.
The vacuum envelope 25 of the X-ray image tube 41 is made of glass, and has an enlarged part 22 with an input window 21 formed at one end thereof, and an enlarged part 22 connected to this enlarged part 22 via a shoulder part 23 and the other end thereof. It consists of a closed small-diameter cylindrical portion 24. Inside the vacuum envelope 25, an input surface 26 consisting of an input fluorescent surface and a photocathode is provided close to the input window 21, and a focusing electrode 27 is provided along the side wall. Also, the vacuum envelope 25
A cylindrical anode 28 is disposed within the small diameter cylindrical portion 24, and an output fluorescent surface 29 is provided surrounded by the anode 28.

Further, a holding structure 42 is coaxially disposed on the outer wall surface of the shoulder portion 23 of the vacuum envelope 25 and is fixed with an adhesive 33. This holding structure 42 is made of an insulating material such as plastic, and has a ring shape as shown in FIGS. 4 and 5, and has a plurality of screw holes 4, for example, three.
3 are provided at equal intervals in the tube axis direction. Each screw hole 43 has a position adjustment screw rod 44.
One end is screwed and fixed by a nut 45. This threaded rod 44 has a flange 46 in the middle.
are integrally formed, and a groove (or hexagonal hole) 47 for a driver is provided at the other end. At the other end of this threaded rod 44, an annular support plate 48 is provided.
is arranged in contact with the flange 46 and is tightened and fixed by a nut 49. This support plate 48 is made of non-magnetic metal such as aluminum, brass, stainless steel, etc., and it is not preferable in terms of cost to use a thick one for screw adjustment. In this invention, the length for fixing the support plate 48 and the screw rod 44 is the length of the screw rod 44.
Since the thickness T of the support plate 48 is determined only by the length of the other end side 50 of the support plate 48, it is possible to reduce the thickness T of the support plate 48.

Now, to adjust the position of the vacuum envelope 25, that is, to adjust the distance H in the tube axis direction, that is, the distance and parallelism between the support plate 48 and the output fluorescent surface 29, use a screwdriver in the groove 47 provided at the other end of the threaded rod 44. This is done by inserting the screw and turning the screw rod 44.

Note that loosening of the screw rod 44 can be prevented by rotating the screw rod 44 and tightening the nut 45.

Further, the support plate 48 and the screw rod 44 are fixed with the nuts 49 as described above, but since the distance H and parallelism between the output fluorescent surface 29 and the support plate 48 have already been adjusted, the tube axis X- After aligning the centers of X' and the support plate 48, tighten and fix the nuts 49,
The position of the tube can be easily adjusted.

Further, as described above, an insulating material such as plastic is used as the holding structure 42, but the threaded rod 44 may be directly processed, and damage to the threaded rod 44 can be prevented by reinforcing it with heliserts or the like. It becomes possible.

The X-ray image tube 41 as described above has an X-ray
It is housed in a cylindrical housing 38 provided with a radiation shielding plate 36 and a magnetic shielding plate 37, and further provided with an optical lens (not shown) at a position facing the output fluorescent surface 29 for use. .

[Effects of the invention] According to this invention, the conventional problems are solved,
Adjustment of the position of the vacuum envelope 25, that is, the output fluorescent surface 2
The distance and parallelism between the support plate 9 and the support plate 48 can be adjusted extremely easily and accurately. As a result, workability is significantly improved. Moreover, with this invention, it is possible to make the support plate 48 a low-cost structure.

[Variation of the idea]

Generally, the support plate 48 and the tube are positioned before being housed in the casing 38, but if they are held by an elastic annular support 51 or the like on the input side as shown in FIG. This makes it possible to locate the tube even after it is stored in the tube, making it extremely easy to handle.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional X-ray image tube housed in a cylindrical housing, Fig. 2 is a perspective view showing the vicinity of the holding structure used in the conventional X-ray image tube, and Fig. 3 is a A sectional view showing an X-ray image tube according to an embodiment of this invention housed in a cylindrical casing, and FIGS. 4 and 5 show the vicinity of the holding structure used in the X-ray image tube of this invention. A perspective view and an exploded sectional view, and FIG. 6 is a sectional view showing a modification of this invention. 21... Input window, 22... Ampulla, 23... Shoulder, 24... Small diameter cylindrical part, 25... Vacuum envelope,
26... Input surface, 27... Focusing electrode, 28... Anode, 29... Output fluorescent surface, 33... Adhesive, 36
...X-ray shielding plate, 37...Magnetic shielding plate, 38...
Cylindrical housing, 41... X-ray image tube, 42... Holding structure, 43... Screw hole, 44... Screw rod, 45
...Natsuto, 46...Tsubabe, 47...Groove, 48...
...Support plate, 49...Natsuto.

Claims (1)

[Scope of Claim for Utility Model Registration] An annular holding structure fixed to the output side shoulder of the vacuum envelope and having a plurality of screw holes in the tube axis direction, one end of which is screwed into the screw hole and tightened with a nut, and a rotatable screw rod having a flange, and an annular support plate fixed at the other end of the screw rod in contact with the flange, and by rotating the other end of the screw rod, the annular support plate is fixed. X, characterized in that the position of the vacuum envelope in the tube axis direction with respect to the support plate can be adjusted.
Line image tube.