JPS6297239A - X-ray image pickup tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to an X-ray image pickup tube, and particularly to an improvement of its target.

[Background technology and its problems]

In recent years, various X-ray television systems have been proposed as means for observing invisible objects. For example, (1) the image of the fluorescent plate is taken with a high-sensitivity television camera, (2) the image is taken with an X-ray fluorochrome multiplier tube's own television camera, and (3) the image is taken directly with an X-ray imaging tube. There are things to take pictures of. Among these, the direct imaging method (3), in which the X-ray transmitted image is directly received by the photoelectric conversion layer of the image pickup tube and converted into an electrical signal, has a simpler device compared to other methods, and uses a fluorescent plate and optical system? Since it can be omitted, high resolution can be obtained, and it is widely used in various fields.

For the face plate used in this X-ray imaging tube, it is necessary to select a material or plate thickness that absorbs as little X-rays as possible. Generally, metal laminate, aluminum, glass, etc. are used. Among these metal beryllium, its oxide is toxic and its handling is restricted, but it absorbs little in the soft X-ray region and is often used as a face plate material.

By the way, the target of the visocon type X-ray image pickup tube that has been put into practical use so far is constructed as shown in FIG. Conversion layer 2 e.g. - lead oxide (pbo)
, amorphous selenium (Se), α-silicon (St), etc., were used as targets by vapor deposition or sputtering.

However, such conventional targets have the disadvantage that image defects such as white scratches or black spots are likely to occur on the captured image, resulting in a significant deterioration of image quality. The cause of this is the unevenness of several hundred square meters to several micrometers on the surface of the face plate that occurs during the process of manufacturing one face plate, that is, the process of vacuum pressing the powder at high temperature and manufacturing the entire face plate from the hot press block. It turns out that there is something. The face plate 1 made of metal beryllium has limitations in manufacturing and processing the face plate due to its preservative nature, and it is extremely difficult to sufficiently remove surface irregularities. Therefore, the surface smoothness required for the face plate of a picon type image pickup tube is insufficient, and deterioration in image quality due to the occurrence of white or black scratches is an unavoidable problem.

[Purpose of the invention]

An object of the present invention is to provide an X-ray image pickup tube that eliminates the above-mentioned drawbacks and allows good X-ray images to be obtained.

[Summary of the invention]

In this invention, a thin glass plate is bonded to one surface of a face plate made of a metal with good X-ray transparency, such as metallic beryllium,
A conductive layer and a photoelectric conversion layer are sequentially formed on this thin glass plate, and the outer peripheral surface of this thin glass plate is hermetically sealed to the open end of the vacuum envelope of the image pickup tube. It's a target.

[Embodiments of the invention]

The target of the X-ray image pickup tube according to the present invention is constructed as shown in FIG. They are joined by adhesive 7. On this thin glass plate 4, a conductive layer 5 and an X-ray sensitive source voltage conversion layer 6 are formed in sequence. In this case, the thickness of the thin glass plate 4 is 10 μm.
m is set.

Next, a method for manufacturing the above-described starter for an X-ray image pickup tube will be described. First, choose a suitable shape and thickness, for example 1.
In case of inch type video controller, diameter is 26.2 mm, thickness is 0.5 mm.
- The face plate 3 made of metal beryllium is heated with concentrated sulfuric acid (HNO).
3) Alternatively, treat the surface with pure water. Then, on either side of this face plate 3, a diameter of 26.2-1 and a thickness of about 0.
A glass thin plate 4 having an extremely low X-ray absorption rate of about 1 to 1 m is laminated using an optical glass adhesive 2 or the like.

Thereafter, this glass thin plate 4t is optically polished until the thickness becomes about 10 μm.

Next, on this thin glass plate 4, a quaternary conductive layer such as kL, Au, etc., or SnO2,
A barrier layer 5, such as In 203, is formed to a thickness of about 100X to 1000X. Further, on this conductive layer 5,
Photoconductive materials that are sensitive to radiation, such as lead oxide (pbo
) film, Ss-based film, α-Si, etc., to complete the target.

Such a target is sealed in an opening at one end of a cylindrical vacuum envelope 8, as shown in FIG. At this time, the outer peripheral surface of the thin glass plate 4 is hermetically joined to the opening at one end of the vacuum envelope 8 via an adhesive 9 such as In. Moreover, the conductive layer 5
It also contacts the adhesive 9 and is electrically connected to the signal extraction ring 10.

〔Effect of the invention〕

According to this invention, a thin glass plate 4 is bonded to one surface of a face plate 3 made of metal beryllium, and a conductive layer 5 and a photoelectric conversion layer 6 are sequentially formed on this thin glass plate 4. This results in
Image defects such as white scratches and black scratches are suppressed, and a good X-ray image can be obtained.

That is, when the X-ray image pickup tube of the present invention was applied to a 1-inch picon type image pickup tube and the captured image quality was evaluated, the characteristics shown in FIG. 3 were obtained.

That is, at the target operating voltage (50 V), no image defects such as white scratches or black scratches were observed, and good image quality could be obtained.

The thickness of the glass thin plate 4 was set to 10 μm in the above embodiment, but considering the soft X-ray transmittance, the thicker the film, the more disadvantageous it is, but considering the strength of the glass thin plate 40 and bonding workability, etc. , a range of 10 μm to 50 μm is appropriate.

Also, if only metal beryllium is used, metal beryllium +10
FIG. 4 shows the relative sensitivity to the X-ray tube voltage in the case of a glass thin plate 4 of .mu.m thick and for the case of metal beryllium plus a glass thin plate 4 of 50 .mu.m thick.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the target of the present invention, which is a target of the X-ray image pickup tube Kl! ! FIG. 3 is a characteristic curve diagram showing the number of defects with respect to the target voltage in the conventional and present invention, and FIG. 4 is a sectional view showing the relative sensitivity tube target with respect to the X-ray tube voltage. . 3... Face plate, 4... Glass thin plate, 5... Conductive layer, 6
...Photoelectric conversion layer, 7...Adhesive for optical glass, 8...
・Vacuum envelope. Applicant's agent Patent attorney Takehiko Suzue Figure 2 (V) Figure 3

Claims (2)

[Claims] (1) A thin glass plate is bonded to one surface of a face plate made of a metal with good X-ray transparency, a conductive layer and a photoelectric conversion layer are sequentially formed on this thin glass plate to serve as a target, and the outer peripheral surface of this thin glass plate is An X-ray imaging tube characterized by being hermetically sealed to the open end of a vacuum envelope. (2) The thin glass plate has a thickness within the range of 10 μm to 50 μm.
ray imaging tube