JPS61279044A - Image pickup tube - Google Patents

Abstract

PURPOSE:To intend to improve the resolution in the IR region by making the target of an image pickup tube by adhering or filling the semiconductive material with photo conductive characteristics to a large number of holes provided in the insulation substrate regularly. CONSTITUTION:After diffusing sulfur in the glass substrate 31 containing for example PbO, SiO2 in the vacuum vessel 1 under the vapor pressure of S at 70 deg.C for time interval of 30-60min, by reaction at 200-350 deg.C PbO is substituted by PbS and so the semiconductive material 32 is produced on the inner wall of the channel and the surface of the substrate. On one side of the surface the electrode 33 is produced by evaporating Fe-Cr. On the other side of the surface the beam landing layer 34 is produced by evaporating porous Sb2S3 after removing the PbS. By this, resolution in the IR region can be improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an image pickup tube using a photoconductive material on its light receiving surface.

(Conventional technology) ``A conventional light guide type imaging tube will be explained with reference to FIG. 4.

20 is a cylindrical vacuum container 1 of an image pickup tube.
is located close to the inner surface of the entrance window.

An electron gun 11 is provided on the other bottom surface of the vacuum vessel 1 so as to face the target 20 .

The surface of the target 20 that does not face the electron gun 11 (hereinafter referred to as the first surface) is given a potential of several volts to several tens of volts by the power source 5, and the electron gun 11 is grounded.

Further, a voltage of several hundred pol I- is applied to the accelerating electrode 4. Further, a focusing coil 7 for focusing the electron beam directed from the electron gun 11 toward the target 20 and a deflection coil 8 for deflecting the electron beam are provided outside the vacuum chamber 1.
The surface of 0 facing the electron gun 11 is scanned with an electron beam.

When an optical image is projected onto the first surface of the target laser I-20, a video signal is obtained at an output terminal 10 connected to the first surface via a capacitor 9.

FIG. 5 is an enlarged cross-sectional view of the target portion of the conventional light guide type imaging tube.

The photoconductive target 20 is provided through a transparent electrode 22 in a light entrance window 21 made of hard glass.

A semiconductor film 23 having a very high specific resistance of 109 to 1011 Ωcm is deposited on the transparent electrode 22, and a porous beam landing layer 24 is provided to improve the reading of the scanning beam of the image pickup tube.

When a light image is focused on this target while a voltage of several volts to several + volts is applied to the transparent electrode 22 with respect to the beam landing layer 24, light absorption occurs in the semiconductor film 23.

The excited electron-hole pair at this time is caused by the photoconductive phenomenon.
Electrons are injected into the power source through the transparent electrode 22, while holes are accumulated in the beam landing layer 24 and increase the surface potential.

This surface potential distribution matches the optical image. The surface potential distribution image is read out by a scanning electron beam system and becomes a video signal.

(Problems to be Solved by the Invention) The semiconductor film constituting the photoconductive target of the image pickup tube with the above configuration needs to have a very high specific resistance. Therefore, the conventional target uses a highly pure material and is made of a polycrystalline film or an amorphous material to achieve high specific resistance.

In a photoconductive target that is sensitive to the infrared region, the target material has a small specific resistance, so the photo-excited electron-hole pairs are diffused while traveling due to the electric field, and the potential distribution accumulated with respect to the optical image is It's blurry.

Further, in order to increase the resistivity, it is sufficient to cool it to a low temperature, but it is not easy to create such a state in an image pickup tube used at normal room temperature.

An object of the present invention is to solve the problems caused by the semiconductor film, and to provide a high-resolution image pickup tube that is particularly sensitive to the infrared region, which was previously impossible.

(Structure of the Invention) In order to achieve the above object, an image pickup tube according to the present invention is an image pickup tube using a photoconductive target, in which the target is formed by forming a hole in the front handle of an insulating substrate in which a large number of small holes are regularly provided. A semiconductor having photoconductive properties is adhered to or filled with a semiconductor.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a perspective view showing an embodiment of a photoconductive target used in an image pickup tube according to the present invention.

The insulating substrate 31 is a disk having a thickness of 0.05 to 0.5 mm by bundling a large number of thin glass tubes (channels) with an inner diameter of 6 to 20 μm.

The inner wall of the channel of this insulating substrate 31 is filled with a semiconductor 32 having photoconductive properties. In this embodiment, PbTe is used as the semiconductor 32 having photoconductive properties by being vapor-deposited by the real wall method.

PbT, e of the semiconductor 32 is formed of a single crystal, the impurity concentration at room temperature is 2.times.10.sup.17 cm.sup.-3, and the carrier mobility is 2000 cm/(V-sec).

The inner wall of the channel may be completely filled, or there may be a gap in the center, but in any case, it must be continuous from the front to the rear.

In this example, the resistance of the PbTe in the channel is 2Ω
~200Ω.

The electrode 33 on the surface is formed by vapor deposition of Fe-Cr, and has a sheet resistance of 100 to 200Ω.

Beam landing layer 34 is porous Sb2S3.

FIG. 2 is a sectional view showing an embodiment of an image pickup tube according to the present invention using the target.

At this time, the window material 41 is made of sapphire, and the electrode 42 connected to the electrode 33 on the front surface of the target 3 is taken out through the indium rings 43 and 44.

Other structures are basically the same as those of the conventional image pickup tube described above with reference to FIG. 4 and the like.

FIG. 3 shows the spectral characteristics of the image pickup tube of the embodiment.

1 (nA/, 1jW at room temperature wavelength 3000 nm
) or higher sensitivity has been obtained.

The resolution is determined by the channel pitch, and 550 to 600 TV lines were obtained at 15 μm pitch.

The target can also be realized by a manufacturing process different from that described above.

Channel diameter 12 with glass substrate containing Pb0.5i02
μm, channel pitch 19 μm 1 plate thickness 0
．． A 5 mm sample is diffused in a vacuum container at a vapor pressure of S at 70°C for 30 to 60 minutes, and then reacted at 200 to 350°C. As a result, pb◯ is replaced with PbS on the inner wall and surface of the channel, and a semiconductor 32 is formed.

Fe--Cr is deposited on one surface to form an electrode 33. After removing the pbs on other surfaces, the porous 5b2s3
A beam landing layer 34 is formed by vapor depositing.

A 1-inch diameter image pickup tube incorporating such a photoconductive target has a maximum sensitivity wavelength of 2°0 μm and a resolution of 500 TV.
I got the book.

Even higher resolution can be obtained by making the hole formed in the insulating substrate square.

PbTe, 5nTe, and Pb5e can be used similarly to the semiconductor material pbs that is sensitive to the infrared region.

In addition, ZnS, ZnT, which has sensitivity in the normal visible range
Compound semiconductors such as e % Cd S % Cd Te can also be used in the same manner and are easy to manufacture.

(Effects of the Invention) As explained in detail above, the present invention achieves the original purpose of causing the semiconductor material of the photoconductive target that converts light in the image pickup tube into an electrical signal to generate a photoconductive phenomenon in the vertical direction between the electrodes. can be achieved.

That is, in the present invention, a semiconductor having photoconductivity is arranged in the needle shape in the vertical direction, and the resistance in the horizontal direction is 1011 to 1 QSQcm in order to prevent the diffusion of photoexcited carriers and maintain positional accuracy as a charge storage layer. It's very expensive.

Previously, photoconductive semiconductors sensitive to the infrared region could not be used because they could not be made to have a high specific resistance.
According to the structure with an insulating substrate according to the present invention, PbTe5S
nTe, Pb5e, PbS, etc. can be used, and manufacturing is easy.

Z n S s Z n with sensitivity in the normal visible range
Compound semiconductors such as T e %CdS and CdTe can also be used.

Also, single crystals can be used instead of the polycrystalline or amorphous materials of conventional photoconductive targets.

By using a single crystal, the photoexcited carriers respond quickly, a photoconductive target with high sensitivity and low afterimage can be obtained, and an excellent image pickup tube can be provided.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a target used in an image pickup tube according to the present invention. FIG. 2 is a sectional view showing an embodiment of an image pickup tube using the target. FIG. 3 is a graph showing the spectral sensitivity characteristics of the image pickup tube. FIG. 4 is a sectional view showing a conventional imaging device. FIG. 5 is an enlarged sectional view of the target 7) of the imaging device. 1... Vacuum-tight container 3... Target 31... Insulating substrate 32... Photoconductive semiconductor 33... Electrode 34... Beam land ink layer 4... Accelerating and focusing electrode 11... Electron Gun 41...Entrance window plate 42...Electrode

Claims (3)

[Claims] (1) An image pickup tube using a photoconductive target, characterized in that the target is constructed by adhering or filling a semiconductor having photoconductive properties into the small holes of an insulating substrate in which many small holes are regularly provided. An image pickup tube. (2) The image pickup tube according to claim 1, wherein the semiconductor having photoconductivity is a single crystal or polycrystalline semiconductor. (3) The target is formed by diffusing and substituting S, Se, or Te on the inner surface of the channel of a glass base material having a channel mainly composed of PbO.
The image pickup tube according to claim 1, which is made of bTe.