JP2003068226A - Output section of x-ray image detector, method and device for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output section of an X-ray image detector which can reduce the structural noise and have a good contrast, and to provide a method and a device for manufacturing the same. SOLUTION: In the output section of the X-ray image detector comprising an output substrate 13 and a phosphor layer 22 which consists of numerous phosphor particles 24 converting photoelectrons into the visual light and is arranged on the output substrate 13, the filling density of the phosphor particles 24 constituting the phosphor layer 22 in the lower layer part A being in contact with the output substrate 13 is set to be smaller than the filling density in the upper layer part B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output section of an X-ray image detector for converting photoelectrons into visible light, and a manufacturing method and a manufacturing apparatus thereof.

[0002]

2. Description of the Related Art An X-ray image detector, such as an X-ray image tube or an X-ray image detector, is an electron tube for converting X-rays into visible light, and the X-ray image detector is entirely composed of a vacuum container. An input section for converting X-rays into photoelectrons is provided on one side of the vacuum vessel, and an output section for converting photoelectrons into visible light is provided on the other side of the vacuum vessel. The output part is
For example, phosphor particles are laminated on an output substrate made of glass which also serves as a part of a vacuum container, and an Al film is formed on the upper part thereof by a vapor deposition method or the like.

Now, the output section of the conventional X-ray image detector will be described with reference to FIG. Reference numeral 41 is a glass output substrate that also serves as a part of the vacuum container, and an annular support ring 42 for fixing the output substrate 41 to the vacuum container is provided on the outer peripheral portion of the output substrate. Further, a phosphor layer 43 is provided on the output substrate 41. The phosphor layer 43 has a plurality of phosphor particles 43a that convert photoelectrons into visible light, and an Al film 44 is formed on the phosphor layer 43 by a vapor deposition method or the like.

Next, another example of the output section of the conventional X-ray image detector will be described with reference to FIG. Figure 5
The same reference numerals are given to the portions corresponding to those in FIG. 4, and the overlapping description will be partially omitted.

FIG. 4 shows phosphor particles 4 having a relatively large particle size.
3A shows a case where the phosphor layer 43 is formed using FIG.
Shows the case where the phosphor layer 43 is formed using the phosphor particles 43a having a relatively small particle diameter.

[0006]

The output part of the conventional X-ray image detector is composed of the output substrate 41 and the phosphor layer 43, and the phosphor layer 43 is composed of a large number of phosphor particles 43.
It has a structure in which a is stacked.

When the phosphor layer 43 constituting the output portion of the X-ray image detector is formed of phosphor particles 43a having a relatively large particle size as shown in FIG. 4, the output substrate 41 and the phosphor particles 43a are formed. There is an advantage that the contact portion with is in a point contact state, the contrast of the output image is improved, and the brightness is improved. However, there is a problem in that the so-called structural noise generated in the output image becomes large due to the arrangement of the phosphor particles 43a and the size of the particle size.

When the particle size of the phosphor particles 43a is large, the flatness of the surface of the phosphor layer 43 deteriorates due to the unevenness of the phosphor particles 43a, and Al formed on the phosphor layer 43 is formed.
The flatness of the film 44 is reduced. As a result, the light converted near the upper portion of the phosphor layer 43, for example, the side where the photoelectrons are input, is diffusely reflected by the Al film 44 and is MTF (spatial modulation transfer function).
Is reduced. In addition, pinholes may be generated in the Al film 44 deposited on the phosphor layer 43.

On the other hand, as shown in FIG. 5, when the phosphor layer 43 is formed of phosphor particles 43a having a relatively small particle diameter,
The packing density of the phosphor particles 43a is increased, and structural noise is reduced. However, the contact between the output substrate 41 and the phosphor particles 43a is not a point contact but a surface contact state, so that the contrast is lowered. Further, when the particle size of the phosphor particles 43a is small, there is also a problem that the brightness is lowered.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide an output section of an X-ray image detector having reduced structural noise and good contrast characteristics, and a method and apparatus for manufacturing the same. To do.

[0011]

SUMMARY OF THE INVENTION The present invention comprises an output board and
In an output part of an X-ray image detector, which comprises a large number of phosphor particles for converting photoelectrons into visible light and which is provided on the output substrate, the phosphor layer in contact with the output substrate The filling density of the phosphor particles in the lower layer portion is smaller than that in the upper layer portion located thereabove.

The method of manufacturing the output part of the X-ray image detector according to the present invention comprises a first step of forming a phosphor layer made of a large number of phosphor particles for converting photoelectrons into visible light on an output substrate. A second step of applying pressure to the phosphor layer from the side where the photoelectrons are input. .

Further, the apparatus for manufacturing the output part of the X-ray image detector of the present invention comprises an output substrate having a phosphor layer formed of a large number of phosphor particles for converting photoelectrons into visible light, and the phosphor layer. And a pressure device for applying pressure from the side where the photoelectrons are input.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic structural diagram of an X-ray image detector to which the present invention is applied, for example, an X-ray image tube, and the X-ray image tube is entirely composed of a vacuum container 11 and the like. The vacuum container 11 includes an input substrate 12 located on the side where X-rays are input, and a disk-shaped output substrate 13 made of glass located on the side where an output image is taken out, the input substrate 12 and the output substrate 13.
It is composed of a tubular portion 14 and the like that connect between and.

On the vacuum side of the input substrate 12, an input section 15 for converting X-rays input from the outside into photoelectrons is provided. An output unit 16 for converting photoelectrons into visible light is provided on the vacuum side of the output substrate 13. The cylindrical portion 14 is provided with a plurality of focusing electrodes 17a to 17d for focusing and accelerating the photoelectrons that are output from the input portion 15 and are directed to the output portion 16, and the anode 18.

The output section 16 of the X-ray image tube will be described with reference to FIG. In FIG. 2, FIG.
The same reference numerals are given to the portions corresponding to, and the overlapping description will be partially omitted.

The output board 13 is provided on the outer peripheral portion of the output board 13.
An annular support ring 21 made of metal is provided for attaching the part to the vacuum container 11. A phosphor layer 22 is formed on the output substrate 13, and a metal film such as an Al film 23 is formed on the phosphor layer 22. The phosphor layer 22 is composed of a group of a large number of phosphor particles 24, and the phosphor particles 24 are formed in multiple layers, for example.

The phosphor layer 22 is formed by stacking phosphor particles 24 in, for example, approximately eight layers. Phosphor layer 2
Lower layer portion A of the second layer, for example, the first layer in contact with the output substrate 13,
Alternatively, the first layer and the second layer are formed so that the packing density of the phosphor particles 24 is as small as 30% to 40%. The upper layer portion B of the phosphor layer 22 located above the lower layer portion A, for example, on the side where photoelectrons are input, that is, the second to eighth layers.
The layers, or the third to eighth layers, have an average packing density of the phosphor particles 24 larger than that of the lower layer portion A, for example, 6
It is formed to 0% or more.

The above-mentioned phosphor layer 22 is, for example, 0.5 μm.
From 30% to 4 of phosphor particles 24 having a particle diameter of m to 2.0 μm
The phosphor particles 24 in the upper layer portion B are crushed by applying pressure from the side where the photoelectrons are input to form a multilayer with a packing density of 0%. And the packing density is increased.

A phosphor layer 22 is formed on the phosphor layer 22 by vapor deposition or the like.
The l film 23 is formed.

Next, a method of manufacturing the above-mentioned output section will be described with reference to FIG. Note that in FIG. 3, parts corresponding to those in FIG. 1 and FIG.

First, three phosphor particles 24 having a particle diameter of 0.5 to 2.0 μm are formed on the output substrate 13 by using a sedimentation method or the like.
Stack in multiple layers with packing density of 0% to 40%. In this case, for example, the output substrate 13 is placed in a suspension in which phosphor particles are dispersed, the phosphor particles 24 are submerged in multiple layers on the surface of the output substrate 13, and then the output substrate 13 is taken out and dried to obtain the phosphor. A phosphor layer 23 in which particles 24 are laminated is formed.

Next, a metal film having a thickness of 1000 to 4000 Å, for example, the Al film 21 is used as a protective film.
The phosphor particles 24 are arranged so as to be covered from above. In this case, an inorganic adhesive or an incinerable organic adhesive is applied to the surface of the Al film 21 on the phosphor particle 24 side.

Then, for the phosphor particles 24 stacked,
From the upper side of the Al film 21, for example, 5 g weight /
A pressure of cm2 or more is applied in the direction of arrow Y. Pressurizing device 31
Has a width in contact with the entire surface of the phosphor particles 24, and when pressed, the phosphor particles 24 in the upper layer portion B are crushed, or the gap between the phosphor particles 24 becomes small,
The packing density of the phosphor particles 24 increases.

In the above embodiment, when an organic adhesive is used as the adhesive applied to the Al film 21, the organic adhesive may generate gas and reduce the degree of vacuum. Therefore, it is desirable to heat and incinerate the organic adhesive after applying pressure to the phosphor particles. The Al film 21 used as a protective film is used as it is as an electrode film on the phosphor layer 22.

According to the above construction, the particle size of the phosphor particles in the portion in contact with the output substrate is relatively large.
Therefore, the contact between the output substrate and the phosphor particles becomes a point contact state, and the contrast is improved. Further, the phosphor particles in the upper layer portion of the phosphor layer are relatively small. Therefore, structural noise is reduced. Also, the flatness of the Al film located on the phosphor layer is improved, the MTF is prevented from being lowered by diffuse reflection, and the luminance is also prevented from being lowered.

The above embodiment has been described in the case where an X-ray image tube is used as the X-ray image detector. However, the present invention can be applied not only to the X-ray image tube but also to the output part of an X-ray image detector having an electron multiplying electrode that accelerates photoelectrons by an electric field.

[0029]

According to the present invention, structural noise is reduced,
It is possible to realize an output surface of an X-ray image detector having good contrast characteristics, and a manufacturing method and manufacturing apparatus thereof.

[Brief description of drawings]

FIG. 1 is a schematic structural diagram for explaining an X-ray image tube to which the present invention is applied.

FIG. 2 is a structural diagram illustrating an embodiment of the present invention.

FIG. 3 is a structural diagram illustrating a manufacturing method according to an embodiment of the present invention.

FIG. 4 is a structural diagram illustrating a conventional example.

FIG. 5 is a structural diagram illustrating another conventional example.

[Explanation of symbols]

11 ... Vacuum container 12 ... Input board 13 ... Output board 14 ... Cylindrical part 15 ... Input section 16 ... Output section 17a, 17b, 17c ... Focusing electrode 18 ... Anode 21 ... Annular support ring 22 ... Phosphor layer 23 ... Al film 24 ... Phosphor particles A ... Lower part of phosphor layer B ... Upper part of phosphor layer

Claims (4)

[Claims] 1. An output part of an X-ray image detector, comprising an output substrate and a phosphor layer formed on a plurality of phosphor particles for converting photoelectrons into visible light, the phosphor layer being provided on the output substrate. An output unit of an X-ray image detector, wherein a lower layer portion of the phosphor layer in contact with the output substrate has a packing density of the phosphor particles smaller than an upper layer portion located thereabove. 2. A first step of forming a phosphor layer composed of a large number of phosphor particles for converting photoelectrons into visible light on an output substrate, and a pressure is applied to the phosphor layer from a side where the photoelectrons are input. A second step of adding, and a method of manufacturing an output part of an X-ray image detector. 3. The X according to claim 2, further comprising a step of disposing a metal sheet on the phosphor layer between the first step and the second step.
Method of manufacturing output section of line image detector. 4. An output substrate having a phosphor layer formed of a large number of phosphor particles for converting photoelectrons into visible light, and a pressurizing device for applying pressure to the phosphor layer from the side where the photoelectrons are input. An apparatus for manufacturing an output part of an X-ray image detector, comprising: