JPH0810584B2 - X-ray image tube and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an X-ray image tube and a method for manufacturing the same.

(Prior Art) Generally, an X-ray image tube having a built-in fluorescent screen has been widely applied to an X-ray industrial television for medical purposes, such as industrial nondestructive inspection.

An X-ray image tube of this type is constructed as shown in FIG. 2, and an input surface 2 is arranged facing the input window 1a inside the input side of a vacuum envelope mainly made of a thin metal such as Al. ing. On the other hand, inside the output side of the vacuum envelope 1, an anode 3 is provided and an output surface 4 is provided, and further, a focusing electrode 5 is provided along a side wall inside the vacuum envelope 1. .

The input surface 2 has an input phosphor layer 7 of CsI formed on the output side (concave surface side) of a substrate 6 made of spherical Al, and a photocathode 8 is further formed on the input phosphor layer 7. The output surface 4 is formed with the output phosphor layer 10 of the substrate 9.

In operation, when an X-ray (not shown) passes through a subject (not shown), it is modulated by the X-ray transmittance of the subject and excites the input phosphor layer 7. The excitation light of the input phosphor layer 7 gives energy to the photocathode 8 formed on the inner surface of the input phosphor layer 7 and causes the photocathode 8 to emit electrons. The electrons are accelerated and focused on the output phosphor layer 10 by the action of an electron lens composed of the anode 3 and the focusing electrode 5, so that the output phosphor layer 10 emits light.

In such a process, electron multiplication is performed, and an image much brighter than the optical image obtained by the input phosphor layer 7 is output phosphor layer.
Got over 10.

(Problems to be Solved by the Invention) By the way, conventionally, glass has been used as the material of the input window 1a in the above X-ray image tube. However, in order to improve the X-ray transmittance and reduce the scattered X-rays, a thin metal such as Al has recently been used as a material for the input window 1a.

However, with the recent sophistication of X-ray diagnostic technology, scattered X-rays generated from the Al input window 1a cannot be ignored, and further improvement is required.

It is an object of the present invention to provide an X-ray image tube capable of removing scattered X-rays and maintaining an excellent contrast and a high degree of vacuum, and a manufacturing method thereof.

[Configuration of the Invention] (Means for Solving the Problem) The present invention is directed to a metal input window that constitutes a part of a vacuum envelope, and is disposed inside the input window so as to face each other in a space at a predetermined interval. In an X-ray image tube including an input substrate and an input phosphor layer formed on the inner surface side of the input substrate, a metal input window and a wall surface of the input substrate which are arranged to face each other in the space. The X-ray image tube has vapor deposition layers made of a material having an atomic number larger than that of the input window.

Further, according to the present invention, a metal input window forming a part of the vacuum envelope, an input board arranged inside the input window so as to face each other in a space at a predetermined interval, and formed on an inner surface side of the input board. In the method of manufacturing an X-ray image tube having the above-mentioned input phosphor layer, a vapor deposition material having a larger atomic number than that of the input window is applied to a peripheral portion of a space facing the metal input window and the input substrate. It is attached to the heating structure, and the resistance heating structure is energized to evaporate and disperse the vapor deposition material after the vacuum evacuation step or after the vacuum evacuation step, and the metal input window and the input substrate opposite to each other in the space are mutually opposed. This is a method of manufacturing an X-ray image tube in which vapor deposition layers are formed on opposing wall surfaces.

(Operation) According to the present invention, since the vapor deposition layer made of a material having an atomic number larger than that of the input window is provided between the input window and the input surface, it absorbs scattered X-rays and Can adsorb gas.

The result is an X-ray image tube that maintains excellent contrast and high vacuum.

Embodiment An X according to an embodiment of the present invention will be described below with reference to the drawings.
The line image tube and the manufacturing method thereof will be described in detail.

The present invention is an improvement in the vicinity of the input window and the input surface of the X-ray image tube, and only the vicinity of the input window and the input surface will be described.

That is, the vicinity of the input window and the input surface of the X-ray image tube according to the present invention is constructed as shown in FIG.
If the same reference numerals are given to the same portions as those in the figure), in the vacuum envelope 1, the input surface 2 faces the input window 1a which constitutes a part thereof, and the input surface 2 is a metal ring 1b for maintaining vacuum airtightness. , 1c are arranged at predetermined intervals.

In this input surface 2 , a CsI input fluorescent layer 7 is formed on the output side (concave side) of a substrate 6 made of spherical Al, as in the conventional case, and a photocathode (omitted) is formed on the input fluorescent layer 7. ) Is formed.

Further, in the present invention, the vapor deposition layer 11 is formed on the inner surface of the input window 1a, and the vapor deposition layer 12 is formed on the input side surface of the input surface 2 , that is, the input side surface of the substrate 6 so as to face the vapor deposition layer 11. ing. That is, the vapor deposition layers 11 and 12 are provided between the input window 1a and the input surface 2 .

In this case, each vapor deposition layer 11 and 12 is made of a material having a larger atomic number than the material of the input window 1a, and when the material of the input window 1a is Al as in this embodiment, the vapor deposition layers 11 and 12 are The material of, for example, Ti, Mn, Cr, Fe, Ni, Cu, Br, Zr, Ag, Cd,
It is a simple substance or a mixture of Sn, SbBa, Cs, I, Pt and the like.

In forming each of the vapor deposition layers 11 and 12 as described above, at least one resistance heating assembly 13 arranged around the input surface 2 is formed.
Attach the evaporation material 14 to the
Are vapor-deposited and scattered to form vapor-deposited layers 11 and 12 made of the above-mentioned materials on the inner surface of the input window 1a and the substrate 6 of the input surface 2 , respectively.

In this case, when a plurality of resistance heating structures 13 are used, it is better to arrange them at substantially equal intervals so that the vapor deposition layer is formed uniformly.

Now, in operation, incident X-rays generate scattered X-rays when passing through the input window 1a. The scattered X-rays are distributed where the X-ray energy is lower than the incident X-rays.

However, in the present invention, the X-ray absorption rate can be increased at the lower X-ray energy by appropriately selecting the material having the atomic number larger than that of the input window 1a as described above. Therefore, there is an effect of removing scattered X-rays generated in the input window 1a, and it is possible to obtain an X-ray image with excellent contrast.

By the way, the vapor deposition layers 11 and 12 are provided with the same effect by forming the input window 1a before being taken in the vacuum envelope body. However, in this case, the gas is adsorbed by once contacting the air.

Therefore, in the present invention, in order to prevent this, by performing vacuum vapor deposition during the vacuum evacuation process of the X-ray image tube or in a state of a high degree of vacuum after the vacuum evacuation process, the vapor deposition layer 11 in a state with less gas adhesion, You can make 12.

Therefore, thereafter, the vapor-deposited layers 11 and 12 have an adsorbing action of the gas released in the tube, and thus can have a combined X-ray removing effect and a gas adsorbing action, that is, a gettering effect.

The vapor deposition layer 11 is most effective when it is formed over the entire surface of the input window 1a. However, the effect of removing scattered X-rays from the surrounding vacuum envelope portion can be obtained even with only the peripheral portion.
Further, in the case where the shield plate is attached and only the central portion is vapor-deposited, in addition to the effect of removing the scattered X-rays from the central portion of the input window 1a, it also has the effect of attenuating the central X-rays. Because
It is also possible to add an effect of correcting shading.

The X-ray image tube of the present invention has the same structure as that of the conventional example (FIG. 2) except for the above, and therefore detailed description thereof will be omitted.

EFFECT OF THE INVENTION According to the present invention, since the vapor deposition layer made of a material having a larger atomic number than the material of the input window is provided between the input window and the input surface, it absorbs scattered X-rays, Moreover, the gas in the pipe can be adsorbed.

The result is an X-ray image tube that maintains excellent contrast and high vacuum.

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an X-ray image tube according to an embodiment of the present invention, and FIG. 2 is a sectional view schematically showing an entire conventional X-ray image tube. 1 ... vacuum envelope, 1a ... input window, 2 ... input surface, 11,
12 ... Evaporation layer, 13 ... Resistance heating structure, 14 ... Evaporation material.

Claims (2)

[Claims] 1. A metal input window which constitutes a part of a vacuum envelope, an input board which is arranged inside the input window so as to face each other with a space at a predetermined interval, and an inner surface side of the input board. In an X-ray image tube having a formed input phosphor layer, a material having a larger atomic number than the material of the input window on the mutually opposing wall surfaces of the metal input window and the input substrate that are arranged to face each other in the space. An X-ray image tube, characterized in that each of the vapor deposition layers is formed. 2. A metal input window forming a part of a vacuum envelope, an input substrate arranged inside the input window so as to face each other in a space at a predetermined interval, and formed on an inner surface side of the input substrate. In the method of manufacturing an X-ray image tube having an input phosphor layer, a vapor deposition material having a larger atomic number than that of the input window is resistance-heated in the peripheral portion of the facing space of the metal input window and the input substrate. It is attached to the structure, and the resistance heating structure is energized to evaporate and disperse the vapor deposition material after the vacuum evacuation step or after the vacuum evacuation step, and the metal input window and the input substrate are arranged to face each other in the space. A method for manufacturing an X-ray image tube, characterized in that a vapor deposition layer is formed on each wall surface.