JPS62122030A - Target for x-ray image pickup tube and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a picture of a high quality, by coating a thin metallic aluminum layer over a metallic beryllium plate, and coating a converting substance layer to convert the X-ray energy into an electrical signal over the thin metallic aluminum layer. CONSTITUTION:A completed target 10 is composed by coating a metallic aluminum layer 13 with smooth surface over a metallic beryllium plate 11, over which is coated a converting substance layer 12 to convert the X-ray energy into an electrical signal, and by sealing up the converting layer 12 in a vacuum container furnishing an electron gun composition and the like. The favorable manufacture is that the metallic beryllium plate 11 is surface-treated by undiluted sulfuric acid or pure water, and then a metallic aluminum (Al) layer 13 is coated and formed over a side of the beryllium plate 11. After that, the surface of the metallic aluminum layer 13 side is grinded and removed up to the position of the X-X' line beyond the recessed portions 13a of the surface to gain a smooth surface of aluminum layer 13. Finally, the converting substance layer 12 to convert the X-ray energy into an electrical signal is coated and formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a target for an X-ray imaging tube and a method for manufacturing the same.

[Technical Background of the Invention and Problems Therewith] As an apparatus for observing a non-transparent object, there is an apparatus that reproduces a transparent image by conveying X-rays that have passed through a decoy image object through an imaging tube. The target of this X-ray image pickup tube is, as shown in FIG.
2 is attached. This converting material layer 12 is positioned and sealed inside a vacuum container in which an electron gun assembly (not shown) and the like are arranged, and X-rays transmitted through the object to be traversed through the metal beryllium face plate 11 are incident thereon. Although the handling of metal beryllium is restricted because its oxide is harmful, it has the advantage that it absorbs less X-rays, especially in the soft X-ray region, and can construct a highly efficient image carrier.

By the way, when an X-ray image is conveyed by such an image pickup tube, it is often experienced that defects such as white scratches and black scratches are likely to occur on the image conveyance screen. The main reason for this is the unevenness that exists on the surface of the metal beryllium face plate. In other words, when the surface of the face plate is microscopically observed, the reference numeral 11a is shown in FIG.
In many cases, dents as shown in the figure are observed here and there. The depth of this recess lla is sometimes several μm. When the conversion material layer 12 is deposited on this face plate, a locally depressed portion 12a is created corresponding to the depression of the face plate. It has been found that when a target having discontinuous portions in the conversion material layer 12 is used, the above-mentioned screen defects appear.

[Object of the Invention] The present invention provides a target for an X-ray imaging tube and a method for manufacturing the same, which can eliminate the above-mentioned disadvantages and provide high-quality images.

[Summary of the invention]

The present invention provides an X-ray image pickup tube in which a thin layer of metal aluminum is deposited on a metal beryllium face plate, and a conversion material layer for converting X-ray energy into electrical signals is deposited on the thin metal aluminum layer. It's a target. The manufacturing method is characterized by first depositing metal aluminum on the metal beryllium face plate by vapor deposition, polishing this metal aluminum layer from the front side to make the surface smooth, and then applying the conversion material on top of this metal aluminum thin layer. This is a method in which the layers are applied directly or through multiple layers.

As a result, even if there are irregularities on the surface of the metal beryllium face plate, the beryllium face plate itself is coated with a conversion material layer that converts X-ray energy into electrical signals on a smooth surface without having to cut or polish the surface. It is possible to reproduce a homogeneous X-ray image. Therefore, high-quality X-ray images can be reliably obtained.

[Embodiments of the Invention] Examples thereof will be described below with reference to the drawings. Identical parts are designated by the same reference numerals.

As shown in FIG. 1, the completed target 4 of the present invention has a thin metallic aluminum layer 13 with a smooth surface deposited on a metallic beryllium face plate 11, which converts X-ray energy into electrical signals. A converting material layer 12 is deposited thereon. Then, the conversion layer 12 is sealed and assembled in a vacuum container in which an electron gun assembly (not shown) is attached, and a 1-inch vidicon type picture tube, for example, is completed.

Next, the preferred manufacturing method will be explained.

First, the diameter is approximately 26mm, corresponding to the 1-inch type.
A metal beryllium plate 11 with a thickness of 0.5 mm is prepared.

The surface of this is treated with concentrated nitric acid or pure. Next, as shown in FIG. 2, a metal aluminum (AI2) layer 13 having a thickness of about 10 μm is deposited on one surface of the beryllium face plate by vacuum evaporation or sputtering. As a result, if there is a recess 11a in the face plate 11, the aluminum layer will fill it, and there will also be a slight recess 13 on the surface.
a occurs.

Next, the surface side of the metal aluminum layer 13 is polished and removed by, for example, mechanical polishing, beyond the surface recess 13a, to the position of the X-X line, that is, to a thickness of, for example, 5 μm.

This polishing is performed using cerium oxide grindstone powder and polishing liquid, which are commonly used for glass optical polishing.
The surface roughness is, for example, a smooth surface with a roughness of about 100 or less. As a result, a thin aluminum layer 13 with a smooth surface is obtained as shown in FIG.

Next, as shown in FIG. 4, the metal aluminum thin layer 13 is covered with a conversion material layer 12 such as -lead oxide, an amorphous selenium film, or a silicon film that converts X-ray energy into electrical signals. Form a deposit. The thickness of this conversion layer 12 is, for example, approximately 20 μm in the case of lead oxide.

In this way, we completed the target crossing of the X-ray image pickup tube,
It arrives in a vacuum container (not shown) in an airtight manner.

Evaluation of the reproduction of XtQ images shows that image pickup tubes with such tags 1~ have no white scratches or black scratches at a target voltage of 50V, as shown by characteristic curve A in Figure 5, and above that, there are no white scratches or black scratches. Although the image defects thought to be the cause of the image defects appeared, good image quality was obtained with good reproducibility. On the other hand, in the conventional structure shown in FIG.
As shown in Figure 2, the number of screen defects increases from a low target voltage.

As shown by curve A in Figure 6, the sensitivity is slightly lower than that of conventional type B when the accelerating anode voltage of the X-ray tube, which is the X-ray source, is approximately 40 kV or less, but there is no problem in practical use. was confirmed. In addition, since the thin aluminum layer can be used as a signal electrode, there is no need to form an extra conductive layer.
It's convenient.

Note that the thickness of the metal aluminum thin layer 13 was practically appropriate in the range of 2 to 7 μm in view of the film strength of this layer and polishing workability.

〔Effect of the invention〕

As explained above, according to the present invention, good X-ray image quality can be obtained with good reproducibility. Even if the metal beryllium face plate has irregularities, there is no need to directly polish the surface of the beryllium face plate, so there is no generation of harmful substances, and there is an advantage that it is suitable for industrial large-scale production of X-ray image pickup tubes.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main part showing an embodiment of the present invention, FIGS. 2 to 4 are enlarged sectional views of the main part of the manufacturing process, and FIG.
6 and 6 are comparative characteristic diagrams, respectively, and FIGS. 7 and 8 are sectional views of main parts and enlarged views of conventional structures. 11... Metal beryllium face plate, 12... Conversion layer, 13... Metal aluminum thin layer.

Claims (3)

[Claims] (1) In an X-ray image pickup tube target having a face plate made of metal beryllium and a conversion material layer for converting X-ray energy into electrical signals deposited on the face plate, a thin film of metal aluminum is placed on the metal beryllium face plate. 1. A target for an X-ray image pickup tube, characterized in that the conversion material layer is deposited directly or via another layer on the thin metallic aluminum layer. (2) The thickness of the metal aluminum thin layer is 2 to 7 μm.
The target of the X-ray image pickup tube according to claim 1, which is within the range of m. (3) In a method for manufacturing an X-ray image pickup tube target comprising a metal beryllium face plate and a conversion material layer deposited on the face plate for converting X-ray energy into an electrical signal, the metal beryllium face plate has a metal beryllium face plate. Aluminum is deposited by vapor deposition, this metal aluminum layer is polished from the surface side to make the surface smooth, and the conversion material layer is deposited directly or through another layer on this metal aluminum thin layer. A method for manufacturing a target for an X-ray imaging tube, characterized in that: