JPH03261053A - Image pick-up tube - Google Patents

Abstract

PURPOSE:To suppress crack initiation in the photoconductive layer of an image pick-up tube using an amorphous semiconductor equipped with a photoconductive layer mainly made up of Se by installing an external circumferential layer for prevention of crack initiation on the external circumference of a photoelectric layer. CONSTITUTION:An external layer 5 made up of As at 80atom%, etc., is provided on the external circumference of a photoconductive layer 4 mainly composed of Se on a substrate 1 to prevent crack initiation, so that it is possible to obtain an image pick-up tube having a photoconductive layer prevented from crack initiation without deterioration of such characteristics as high sensitivity, low afterimage, etc., because of application of an amorphous semiconductor equipped with the photoconductive layer mainly composed of Se.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to photoconductive image pickup tubes and X-ray image pickup tubes, and particularly to an improvement in the target portion that is suitable for image pickup tubes used with increased target voltage. Regarding.

[Prior art 1] In general, a photoconductive image pickup tube and an
It consists of a target section for converting a line image into a charge pattern and accumulating it, and a scanning electron beam generating section for reading the accumulated charge pattern as a signal current, and the target is scanned by the electron beam. Immediately after the scanning side surface potential is balanced with the cathode potential.

An image pickup tube using an amorphous semiconductor mainly composed of Se in the photoconductive layer of the target part is sensitive to visible light, ultraviolet rays, and X-rays, and has low image retention and high resolution characteristics. It is widely used in various fields.

Regarding such an image pickup tube, for example, Japanese Patent Publication No. 54-303
82, Preliminary Lectures for the National Conference of the Television Society (1982), pp. 81-82. In such an image pickup tube, if the scanning surface side of the target is likely to emit secondary electrons due to the scanning electron beam, the above-mentioned normal operation of the image pickup tube will not be possible, so the secondary electron emission on the scanning surface side is reduced. As a means to improve the landing characteristics of the electron beam, for example, porous Sb,
A method has been proposed in which an electron beam Rande ink layer consisting of s3 is formed by evaporation in an inert gas (Japanese Patent Publication No. 1973-
40809).

Furthermore, when the voltage between the target electrode and the cathode electrode (hereinafter simply referred to as target voltage) of the image pickup tube is increased by 3-, avalanche multiplication of charges occurs inside the photoconductive layer, resulting in even higher sensitivity characteristics. It is known that

[Problems to be Solved by the Invention] The image pickup tube according to the above-mentioned prior art in which the photoconductive layer is made of an amorphous semiconductor mainly composed of Se has the disadvantage that the photoconductive film tends to crack when used at high temperatures. there were. The above drawback is that the amorphous semiconductor mainly composed of Se in the photoconductive layer has
This can be improved by adding S, Ge, etc., but if the amount of As, Ge, etc. added is too large, there are problems such as deterioration of photoresponse characteristics and fluctuation of sensitivity during use.

It is an object of the present invention to eliminate the above-mentioned drawbacks, that is, the occurrence of cracks, without deteriorating the excellent characteristics such as high sensitivity and low afterimage of an image pickup tube using an amorphous semiconductor mainly composed of Se in the photoconductive layer. An object of the present invention is to realize an image pickup tube that is difficult to use and an imaging device using the image pickup tube.

[Means for Solving the Problems 1] In order to achieve the above object, in an image pickup tube using a non-4-quality semiconductor mainly composed of Se for the photoconductive layer or the X-ray conductive layer of the image pickup tube target, the photoconductive layer A highly dense outer peripheral layer is provided around the periphery to suppress the occurrence of cracks.

The material for the outer peripheral layer contains at least S, Se, or Te. In particular, Zn, Cd, Ga, In, G
A compound consisting of at least one selected from the group consisting of e, As, and Bi and at least one selected from S, Se, and Te is preferable, and a single layer consisting of these compounds or a plurality of compounds is preferable. A laminated layer or a layer made of a mixture of multiple compounds can be used. In this case, the total sum of S, Se, and Te contained in the above material is desirably 50 atomic % or more and 95 atomic % or less on average within the layer, and other than this, the effect is small.

The shapes of the outermost layer, the conductive layer, and the photoconductive layer are not particularly limited, but the outermost layer only needs to cover the periphery of the photoconductive layer outside the effective scanning area of the photoconductive layer, and the outermost layer should be larger than the photoconductive layer to prevent cracks. Great suppressive effect.

What is required is that the inner side of the outer circumferential layer be equal to or larger than the effective scanning area, and the outer side be equal to or larger than the outer periphery of the photoconductive layer.

It is sufficient that the thickness of the outer peripheral layer is approximately the same as the thickness of the photoconductive layer, but if it is too thin, no effect will be obtained, so the thickness of 0.1 μm is sufficient.
It is desirable that it is more than m.

Furthermore, cracks in the photoconductive layer can be suppressed by providing an outer peripheral layer inside the photoconductive layer or between the conductive layer and the photoconductive layer, but the suppressing effect is limited to This is most noticeable when provided between layers.

In addition, in order to improve the S/N ratio, the conductive layer is divided into two parts on the substrate, a part corresponding to the effective scanning area and a part corresponding to the area outside the effective scanning area, or the conductive layer is formed in the effective scanning area. The present invention can be similarly implemented in an image pickup tube using a substrate formed only on the corresponding portions. In this case, the effects of the present invention can be obtained without impairing the improvement of the SN ratio.

If a transparent insulator such as a glass face plate or a quartz face plate is used as the substrate, an image pickup tube that detects visible light or ultraviolet images can be obtained.
If a thin plate is used, an imaging tube for X-rays can be obtained.

[Function] As a result of a detailed investigation by the present inventors of cracks in the photoconductive film that occur at high temperatures in an image pickup tube using an amorphous semiconductor mainly composed of Se for the photoconductive layer of the image pickup tube target,
It was revealed that the cracks occur from the periphery of the photoconductive layer, and when the outer layer is provided at the periphery of the photoconductive layer,
The present invention was realized by discovering that the above-mentioned cracks can be suppressed without deteriorating other properties.

The cause of cracks is to improve the resolution characteristics.
This is thought to be because, in an image pickup tube using an amorphous semiconductor mainly composed of Se for the photoconductive layer, thermal stress is concentrated in the periphery of the photoconductive layer due to its thermal conductivity. Therefore, in the present invention, by distributing a high-density outer layer around the photoconductive layer using an amorphous semiconductor mainly composed of Se, the stress in the peripheral area is dispersed and the rise of crack generation is suppressed. It is suppressed.

The present invention aims to reduce sensitivity fluctuations during use by reducing additives such as As and Ge to improve heat resistance in an image pickup tube using an amorphous semiconductor mainly composed of Se as an optical conductive layer.
It is a good opponent for high-performance image pickup tubes with low afterimages, and if the present invention is applied to such image pickup tubes, it becomes possible to use them at high temperatures without impairing the excellent characteristics of the image pickup tube. Furthermore,
In such an image pickup tube, the dark current is suppressed to a lower level, so it is possible to apply a higher voltage and use it, which increases the efficiency of avalanche multiplication of charges within the photoconductive layer. High sensitivity can be obtained.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the structure of a target section of an image pickup tube according to the present invention. FIG. 1(a) is a sectional view of the target portion, and FIG. 1(b) is a plan view. 1 is a substrate, 2 is a conductive layer, 4 is a photoconductive layer made of an amorphous semiconductor mainly composed of Se, and 3 is a hole injection blocking layer, which prevents charge injection from the conductive layer 2 to the photoconductive layer 4. 5 is an outer circumferential layer, 6 is an electron beam land ink layer, and a broken line 6 indicates an effective scanning area, and the inside of the broken line 6 will be scanned with an electron beam during use.

In the figure, the inner shape of the outer peripheral layer is circular, but it does not necessarily have to be circular, and may be a square meter, an ellipse, or the like. Further, the outer circumferential layer may have the same external shape as the photoconductive layer, but the larger the outer circumferential layer is, the more effective it is in suppressing cracks.

Further, the outer shapes of the conductive layer and the photoconductive layer do not necessarily have to be circular as shown in the figures.

Hereinafter, an example of specific manufacturing of an image pickup tube will be described.

Example 1 A transparent conductive layer with a diameter of 24 mmφ and containing indium oxide as the main component was formed on a transparent glass substrate with a diameter of 26 mmφ by electron beam evaporation, sputtering evaporation, or current heating evaporation using a resistor boat. form. Thereon, a 0.02 μm thick hole injection blocking layer made of cerium oxide with a diameter of 20 mm and a 4 μm thick photoconductive layer made of amorphous Se are successively formed by vacuum evaporation.

Thereon, a 2 μm thick outer peripheral layer made of 80% As is formed by vacuum evaporation. In this case, a vapor deposition mask is used to control the outer circumferential layer so that its inner diameter is 16 mmφ and its outer diameter is 22 mmφ. On top of that, 5b2s, the pressure Q, 2
Deposited in a nitrogen gas atmosphere of Torr, with a diameter of 22 mmφ
Then, an electron beam Lande ink layer made of porous Sb2S3 with a film thickness of 0.1 μm is formed to obtain an image pickup tube target.

The obtained image pickup tube target is crimped onto a 1 inch size image pickup tube housing containing an electron gun via indium, and the inside of the tube is vacuum sealed to obtain an image pickup tube.

Example 2 FIG. 2 is a diagram showing the shapes of a substrate and a conductive layer used in this example. FIG. 2(a) is a plan view as seen from the electron beam scanning side, and FIG. 2(b) is a cross-sectional view.

7 is a transparent glass substrate, 8 is a transparent conductive layer for a target electrode containing indium oxide as a main component, and is formed in the same manner as in Example 1 using a vapor deposition mask. Reference numeral 9 denotes a guard electrode conductive layer made of an Afl thin film, which is formed by vacuum evaporation using a evaporation mask.

Reference numeral 10 denotes electrode pins connected to each conductive layer and welded to the glass substrate.

A hole injection blocking layer having the same diameter as the outer periphery of the guard electrode 9 is formed by the same method as in Example 1 on the surface on which the conductive layer shown in FIG. 2 is formed. On top of that, 2 atomic % of As was added by vacuum evaporation method.
An amorphous 5e-Te layer with a thickness of 0.05 μm is sequentially formed. Thereon, an outer peripheral layer of As2Se3 having a thickness of up to .mu.m is formed by vacuum evaporation. In this case, As2
A vapor deposition mask is used to control Se3 so that it does not adhere inside the broken line 6 indicating the effective scanning area in FIG. 2(a).

On top of that, an amorphous Se layer with the same diameter as the 5e-As layer and the 5e-Te layer and a thickness of 2 μm is formed by vacuum evaporation, and the layer consisting of these three becomes a photoconductive layer. . An electron beam land ink layer made of porous sb and s3 is formed thereon in the same manner as in Example 1, and an image pickup tube is then manufactured in the same manner as in Example 1. This image pickup tube uses a guard electrode with the same potential as the cathode electrode of the image pickup tube.

Example 3 11- A transparent glass conductive layer for a target electrode made of indium oxide as a matrix shown in FIG. 2 and a target electrode bottle are formed on a transparent glass plate having a diameter of 18 mmφ. Next, on the side where the conductive layer is formed, apply 1 layer in the same manner as in Example 1.
A hole injection blocking layer with a diameter of 3 mm is formed, and a photoconductive layer made of amorphous Se containing 1 atomic % of As and having a thickness of 4 μm is formed thereon by vacuum evaporation. On top of that, inner diameter 1
An outer peripheral layer made of As and S3 having a diameter of 2 mm, an outer diameter of 14 mm, and a thickness of 2 μm is formed. An electron beam Rande ink layer is formed thereon in the same manner as in Example 1, and this is attached to a 2/3 inch size image pickup tube housing to obtain an image pickup tube.

Example 4 In this example, the substrate was a metal Be plate with a diameter of 26 mmφ and a plate thickness Q of 5 mmφ, or a composite plate with a 5in2 layer laminated on it with a film thickness of 10 μm in order to improve the surface smoothness. use A conductive layer made of an All thin film having a thickness of 0.02 μm is formed on this substrate by vacuum evaporation.

However, in the former case, the resistor 12- Due to the low resistance, the conductive layer can be omitted.

Thereon, a hole injection blocking layer made of cerium oxide with a thickness of 0.02 μm and a photoconductive layer made of amorphous Se with a thickness of 20 μm are formed using the same method as in Example 1. Furthermore, an outer peripheral layer of Ge-As-8e having an inner diameter of 16 mmφ, an outer diameter of 22 mmφ, and a film thickness of 5 μm is formed thereon by sputtering vapor deposition. The composition of the outer layer is Ge 20 atomic %, As 20
atomic%, 5e60 atomic%. Thereon, an electron beam Rande ink layer made of porous sb, s and having a thickness of 0.2 μm is formed by the same method as in Example 1. This is crimped onto an imaging tube housing via indium, and the inside of the tube is vacuum sealed to obtain an X-ray imaging tube.

The image pickup tubes obtained in Examples 1 to 4 above can be used at higher temperatures because the temperature at which racking occurs in the photoconductive layer is about 10 degrees higher than that of conventional image pickup tubes that do not have an outer peripheral layer. It became.

FIG. 3 is a schematic diagram of the main structure of a three-tube color camera for high-definition television using the image pickup tube according to the present invention.

R, G, and B are image pickup tubes for R, G, and B channels according to the present invention, respectively; 1 is a color separation optical system; 12 is a power supply circuit;
3 is an electron beam scanning circuit, 14 is a video signal amplification circuit, 1
5 is a viewfinder of the camera, 16 is a color monitor for video reproduction, 17 is a camera control device, and 18 is a zoom lens.

R, G, of the color camera for high-definition television shown in Figure 3,
For example, three image pickup tubes of the present invention according to Example 3 were mounted on the B channel, a target voltage of 480 V was supplied from the power supply circuit 12 to the target electrode of each image pickup tube, and the number of scanning lines was 1125. , avalanche multiplication of charges occurs inside the photoconductive layer, resulting in an increase of 10% compared to conventional cameras.
Ultra-sensitive television images more than twice as sensitive were obtained.

FIG. 4 is a schematic structural diagram of an X-ray image analysis device using the X-ray imaging tube according to the present invention. 19 is an X-ray source, 20 is an X-ray imaging tube according to the present invention, 21 is a camera control device, 22 is a frame memory, 23 is an image processing device, 24 is a monitor, 25 is a target power source, and 26 is a subject.

The X-ray image pickup tube of the present invention according to the fourth embodiment is mounted on the X-ray image analyzer shown in FIG.
When the device was operated by applying a Targetera 1-voltage of 00 ■, a good X-ray image analysis processed image was obtained.

(Effect of the invention 1) According to the present invention, it is possible to increase the operating temperature of a high-resolution, low-afterimage image pickup tube whose photoconductive layer is made of an amorphous semiconductor mainly composed of Se, making it possible to expand the field of use. , the industrial effect is improved.Furthermore, if the present invention is applied to the target of an ultra-high sensitivity image pickup tube that is used by causing avalanche multiplication of charges in the photoconductive layer, excellent ultra-high sensitivity and high resolution characteristics can be obtained. High-definition television cameras, ultraviolet cameras,
It becomes possible to improve the performance of X-ray cameras.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic structure of an embodiment of the image pickup tube target according to the present invention, FIG. 2 is a diagram showing the structure of an embodiment of the substrate section used in the image pickup tube according to the present invention, and FIG. A structural diagram of a high-definition 15-tube color camera for television using the image pickup tube according to the invention. FIG. 4 is a schematic configuration diagram of an X-ray image analysis apparatus using the X-ray image pickup tube according to the present invention. 16 1... Substrate, 2... Conductive layer, 3... Hole injection blocking layer, 4... Photoconductive layer, 5... Outer layer, 6... Effective scanning area, 7... - Transparent glass substrate, 8... Transparent conductive layer for target electrode, 9... Conductive layer for guard electrode, 10... Electrode bottle.

Claims (1)

[Claims] 1. An image pickup tube target formed by sequentially laminating on a substrate at least a conductive layer, a photoconductive layer made of an amorphous semiconductor mainly composed of Se, and an electron beam land ink layer. An image pickup tube, characterized in that the photoconductive layer is provided with an outer peripheral layer around the photoconductive layer to prevent cracks from occurring in the photoconductive layer. 2. The image pickup tube according to claim 1, wherein the outermost circumference of the outer peripheral layer is larger than the outermost circumference of the photoconductive layer. 3. In claim 1, the outermost periphery of the outer peripheral layer is at least between the conductive layer and the photoconductive layer, between the photoconductive layer and the electron beam Landek layer, or inside the photoconductive layer. An imaging tube characterized in that it is provided in. 4. Claim 1, 2 or 3, wherein the peripheral layer contains at least one of S, Se, or Te, and the sum of S, Se, and Te is 50 atomic % or more and 95 atomic % or less An image pickup tube characterized by: 5. In claim 4, the outer peripheral layer is made of Zn, Cd.
, Ga, In, Ge, As, and Bi, and at least one member selected from the group of S, Se, and Te. 6. Claim 1, 2 or 3, 4 or 5, wherein the conductive layer divides the substrate into a portion corresponding to the effective scanning area and a portion corresponding to outside the effective scanning area. An imaging tube characterized in that: 7. The image pickup tube according to claim 6, wherein a portion of the conductive layer corresponding to outside the effective scanning area is removed. 8. A television camera using the image pickup tube according to claim 1, second, third, fourth, fifth, sixth or seventh. 9. The X-ray imaging tube according to claim 1, second, third, fourth, fifth, sixth, or seventh, wherein the substrate is made of a material that transmits X-rays. 10. An X-ray image analysis system using the X-ray imaging tube according to claim 9.