JPS5836805B2 - Image tube manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention is directed to an improvement in the method of manufacturing an image pickup tube.

Generally, in an image pickup tube, a face plate made of glass with a photoelectric conversion target formed by sequentially laminating a transparent conductive layer and a photoconductive layer on the inner surface is sealed at the open end of a vacuum envelope made of glass in the shape of a cylinder with a bottom. It is worn.

By the way, in a so-called vidicon using antimony trisulfide as a photoconductive layer, vacuum sealing between a face plate and a vacuum envelope (bulb) has conventionally been performed by cold compression bonding using high-purity metal indium.

That is, as shown in FIG. 1a, metal indium 2 is attached in advance to the inner surface of the annular signal electrode (target ring) 1, and as shown in b, the metal indium 2 is trimmed to the required amount. A surface 2a having an arcuate cross section is formed, and the annular signal electrode 1 is placed at a predetermined position.

If the face plate 3 is immediately cold-pressed to the metal indium 2 as shown in C, the face plate 3 is sealed in the vacuum envelope 4 via the metal indium 2.

However, according to the above sealing means, cold compression bonding is required, cleanliness is required on the sealing surface of the face plate 3 and the end surface of the vacuum envelope 4, and if there are minute line scratches, etc., the vacuum The disadvantage is that the reliability of airtightness is significantly reduced.

Furthermore, the metal indium 2 has poor moisture resistance and is easily corroded by high temperature and high humidity, and it is essential to apply a moisture proofing agent such as silicone varnish to the exposed surface after cold pressing.

Furthermore, in order to facilitate the trimming, it is necessary to use an annular signal electrode 1 made of stainless steel or chrome plating, and metal indium 2 also has the disadvantage of being very expensive.

In addition, for vidicon using antimony trisulfide, the heat resistance of the vapor-deposited film is about 170°C in an inert gas atmosphere, so cold compression bonding using high-purity metal indium 2 was conventionally performed as mentioned above. However, since the melting point of metal indium 2 is 156°C, the baking time during exhaust is 120°C to 120°C.
Due to the temperature limit of 130° C., gas cannot be sufficiently vented from the vacuum envelope 4, the face plate 3, and the electrode assembly in the vicinity thereof.

An object of the present invention is to provide a method for manufacturing an image pickup tube that eliminates the above-mentioned conventional drawbacks.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The image pickup tube obtained by the manufacturing method of the present invention is constructed as shown in FIGS. 2 and 3, and FIG. 3 is an enlarged view of the main part of FIG. 2.

That is, a face plate 6 made of glass is sealed to the open end of a bottomed cylindrical vacuum envelope 5 made of glass, and an annular signal electrode 7 is attached near the boundary thereof.

A transparent conductive layer 8 is provided on the inner surface of the face plate 6.
and photoconductive layer 9 are sequentially formed.

The transparent conductive layer 8 and the photoconductive layer constitute a so-called Nine Electric conversion target 10, and the transparent conductive layer 8 is electrically connected to the annular signal electrode 7.

Further, inside the vacuum envelope 5, there is a cathode 1 having a built-in heater 11.
First to fourth grid electrodes 13 to 16 are sequentially disposed coaxially with respect to the stem 5a at predetermined intervals, and the heater 11 and each electrode 12 to 16 are connected to a plurality of conductive pins penetrating the stem 5a. 1T (however, in the figure, it is shown as not being connected for convenience).

Further, the first to third grid electrodes 13 to 15 are supported by insulating rods (not shown) via support elements, and the fourth grid electrode 16 is a so-called mesh electrode and faces the photoconductive layer 9.

Incidentally, even in the image pickup tube obtained by the manufacturing method of the present invention, the open ends of the face plate 6 and the vacuum envelope 5 are vacuum-sealed with a sealing material 18 as shown in FIG.
If the sealing material 18 is made of metal indium, there will be the same drawbacks as in the prior art.

Therefore, according to the inventor's experiments, 0.1 to 10% by weight of sb and 0% of Zn were added to the sealing material mainly composed of Pb and Sn.
．． It has been found that by adding about 1 to 10% by weight, it can bond very strongly with metal oxides such as glass, ceramics, ferrite, and metal oxide films.

The melting point of such a sealing material can be varied between 180 and 3508 C by changing the composition of Pb and Sn, and can be selected to be the highest temperature that the photoelectric conversion target 10 can withstand. can.

Further, in the case of vacuum sealing by applying pressure, there is no need to raise the temperature of the sealing material to its melting point, and vacuum sealing can be performed at a temperature 20 to 30° C. lower than the melting point, although this varies depending on the ultrasonic vibration and pressure.

Furthermore, by locally increasing the temperature of the sealing material, the periphery of the face plate, and the open end of the vacuum envelope, the temperature can be raised to 55% higher than the temperature that the photoelectric conversion target can withstand in the inert gas atmosphere.
A sealing material with a melting point 0 to 70°C higher can also be used.

Therefore, in the image pickup tube of the present invention, as the sealing material 18 shown in FIG.
A material having a melting point below a temperature that can be withstood by a photoelectric conversion target containing 0.1 to 10% by weight of b and 0.1 to 10% by weight of Zn is used.

Next, a method for vacuum sealing the face plate 6 and the vacuum envelope 5 using the sealing material 18 will be specifically described.

[First vacuum sealing method] First, the sealing material 18 as described above is prepared, and this sealing material 18 is made of a plate whose melting point is set to 200° C. as shown in FIG. 4a and b. It is punched out in a ring shape.

In this case, the appropriate plate thickness t is 0.05 to 0.5 mm, and the width d needs to be made smaller as the plate thickness t becomes larger. According to the inventor's experiments, t (ii) mi) = 0.0 5~0
．． It was best to choose between 3(mi)2.

0. If it is larger than 3 (in)2, the sealing material 18 will protrude into the inner surface of the vacuum envelope 5, disturbing the uniform electric field between the target and the mesh, which is not preferable.

When sealing other electron tubes without such concerns, use tX
d to 0. 3 (it) Needless to say, it may be increased by 2 or more.

Furthermore, if the diameter opening matches the diameter of the vacuum envelope 5 or the diameter of the face plate 6, centering will be easier.

Vacuum sealing is performed using such a sealing material 18, and as shown in FIG. A cylindrical guide 19 made of ceramic, glass, etc. is attached to the outer periphery, and the annular sealing material 18 is placed on the opening end surface.

In this case, the outer diameter of the sealing material 18 is set to be the same as the outer diameter of the vacuum envelope 5, and centering is performed by the guide 19.

Next, the face plate 6 on which the photoelectric exchange target 10 is vapor-deposited on the inner surface (see FIG. 2, omitted in FIG. 5 for convenience) is placed on the sealing material 18, and the exhaust hole 20 at the lower end of the vacuum envelope 5 is placed on the sealing material 18. to inert gas such as N2, Ar, He
etc. to replace the vicinity of the photoelectric conversion target 10 with an inert gas.

Next, a press plate 21 made of ceramic or the like is placed on the face plate 6, and a pressure F is applied to the press plate 21 via a steel ball 22 by a pressurizer 23.

Note that the steel balls 22 serve to uniformly apply force to the sealing surface.

The pressure F is suitably in the range of 20 to 200 kg/cnt; if the pressure is low, the vacuum sealing will be incomplete, and if the pressure is high, the vacuum envelope 5 may be damaged.

Next, the high frequency heating coil 2 provided outside the guide 19
4 is energized, and the temperature of the sealing material 18, the peripheral part of the face plate 6, and the open end of the vacuum envelope 5 is 160 to 1, which is below the temperature that the photoelectric conversion target can withstand in an inert gas atmosphere.
Heat to 80'C.

It goes without saying that the higher the pressure, the better the lower temperature, but according to experiments, the best conditions were 1700C and 60k9/ca.

In addition, if the time required for heating up is shorter than 5 seconds, there is a risk of damage to the face plate 6 and vacuum envelope 5 due to rapid heating, so it is desirable to set the time to 10 seconds or more.
Can be removed at temperatures below 50°C.

[Second vacuum sealing method] It is the same as the first vacuum sealing method, but the pressure applied by the pressure machine 23 is 0.2 to 20 kg/crA, and the pressure applied by the pressure machine 23 is
Vacuum sealing is performed by applying ultrasonic vibration to.

[Third vacuum sealing method] First, the sealing material used has the same external shape as shown in Figure 4 a and b, but unlike the first vacuum sealing method, its melting point is 18
This is an annular punch cut out of a plate set at 5°C.

Vacuum sealing is performed using such a sealing material, but
As shown in FIG. 6a, a metal guide 25 has a cylindrical bent part 25a with one end bent inward on the outside near the open end of the vacuum envelope 5, and a heater 26 is embedded therein. to be placed.

Next, the annular signal electrode 7 is installed on the bent portion 25a of the guide 25, and a sealing material 18 is placed on the open end surface of the vacuum envelope 5.

Next, a photoelectric conversion target 10 is deposited on the inner surface (
(See Fig. 2, omitted in Fig. 6 for convenience) Place the face plate 6 on the sealing material 18, and inject an inert gas, for example, N2*Ar t, from the exhaust hole (not shown) at the lower end of the vacuum envelope 5.
He or the like is sent to replace the vicinity of the photoelectric conversion target with inert gas.

Next, a push plate 28 in which a heater 27 is embedded is placed on the face plate 6, and a pressure F is applied to this push plate 28 by a pressurizer 30 via a steel ball 29.

The appropriate pressure F is in the range of 20 to 200 kg/crA.

Next, the heaters 26 and 27 are energized to ensure that the temperatures at the periphery of the face plate 6, the sealing material 18, and the open end of the vacuum envelope 5 are below the temperature that the photoelectric conversion target can withstand in an inert gas atmosphere. Heat to 160-170°C.

In this case, the heater 26. By preheating No. 27 to about 100° C., the heating time can be set to 20 to 40 seconds.

Vacuum sealing is performed in this way, but at this time, the partially softened sealing material 18 spreads between the face plate 6 and the open end surface of the vacuum envelope 5, and a part of it protrudes outside the vacuum envelope 5. The annular signal electrode 7 is fixed.

In this case, in order to secure the fixation more firmly, one or more chevron-shaped or concave grooves 31 are provided near the center of the inner surface of the annular signal electrode 7, as shown in FIG. What is necessary is to guide the material 18.

The push plate 28 described above is flat on the face plate 6 side, but the center part may be formed into a concave shape so as not to come into contact with the face plate 6, or a heater may be embedded in the periphery of the push plate 28 to make the face plate 6. The temperature rise in the central portion may be reduced.

[Fourth vacuum sealing method] This is the same as the third vacuum sealing method, but the pressure applied by the pressure machine 30 is 0.2 to 20 kg/ci, and the vacuum sealing is performed by applying ultrasonic vibration. Let's do it.

[Fifth vacuum sealing method] In the third and fourth vacuum sealing methods, the heater 26.2
Instead of 7, a metal body such as brass is buried and heated with a high frequency coil.

[Sixth Vacuum Sealing Method] First, the sealing material used is a plate whose melting point is set at 180 to 200°C, as shown in FIG. Slightly different from the sealing material 18, two protruding pieces 32a and 32b are provided at opposing positions.

The plate thickness t1 width d1 diameter D is the same as that of the sealing material 18, but the width W of the protruding pieces 32a, 32b is set to about 2d, and the length t is set to d or more.

Vacuum sealing is performed using such a sealing material 32, and each electrode is arranged as shown in FIG. A first cylindrical guide 33 made of, for example, ceramic is attached to the outer periphery so that one side is flush with the opening end surface, and the sealing material 32 is placed on this guide 33 and the opening end surface.

Furthermore, a second cylindrical guide 34 is placed.

At this time, the two protruding pieces 3 2 a t 3 of the sealing material 32
2b is exposed outside both guides 33 and 34.

Next, the face plate 6 on which a nine-density conversion target (not shown) is vapor-deposited on the inner surface is placed on the sealing material 32, and an inert gas, for example, N
2, Ar, He, etc. are sent to replace the vicinity of the photoelectric conversion target with an inert gas. Next, a push plate 35 made of ceramic or the like is placed on the face plate 6, and a steel ball 36 is placed on this push plate 35. Pressure F is applied by pressurizer 37 via
Add.

This pressure F is suitably in the range of 20 to 200 k9/crrt.

Next, a current supply terminal 38 is connected to the protruding pieces 3 2 a t 3 2 b of the sealing material 32 exposed from the guides 33 and 34.
．． 39 and turn on the power.

Then, electricity is applied until the temperatures near the sealing material 32, the face plate 6, and the open end of the vacuum envelope 5 reach 160-180°C, so that the maximum temperature becomes 165-185°C.

Note that if the heating time is less than 5 seconds, there is a risk of damaging the face plate 6 and the vacuum envelope 5, so the current is set in advance so that the heating time is 10 seconds or more.

After the sealing is completed, it can be taken out at a temperature of 150° C. or lower.

[Seventh vacuum sealing method] It is the same as the sixth vacuum sealing method, but the pressure applied by the pressure machine 37 is set to 0.2 to 20 kg/cIrL, and the pressure applied by the pressure machine 37 is
Vacuum sealing is performed by applying ultrasonic vibration to 7.

[Eighth Vacuum Sealing Method] Each of the above vacuum sealing methods uses a high frequency heating coil 24, a metal guide 25 which is a block heater, and a push plate 28, but in this eighth vacuum sealing method, heating This is carried out using a laser beam.

That is, the face plate 6, the vacuum envelope 5, the sealing material 18
While rotating the sealing material 18, a laser beam may be applied to heat the sealing material 18, or a mirror may be provided and the laser beam may be reflected from the mirror and the laser beam may be applied to the sealing material 18 to heat it.

The method for manufacturing an image pickup tube of the present invention has the above-mentioned structure and as shown in the drawings, and uses a sealing material 18.32 in which Sb and Zn are added to a Pb and Sn system having a melting point below the temperature that the photoelectric conversion target 10 can withstand. Face plate 6 using
Since the vacuum envelope 5 is vacuum-sealed, the drawbacks of the conventional method can be eliminated.

That is, although the present invention does not use cold compression bonding, the sealing material 18 is inexpensive unlike conventional metal indium.

Further, the annular signal electrode 7 is not necessarily necessary, and gas can be removed from the face plate 6 and the vacuum envelope 5 by sufficient heating.

Moreover, in the present invention, the pressure sealing time is short, and as a result, deterioration of the photoconductive layer 9 is avoided, and reliability is significantly improved.

In addition, when sealed using conventional metal indium 2,
This metal indium 2 was diffused to a considerable area of the face plate 3, but in the present invention, the diffusion area of the sealing material 18 is very small and is extremely effective.

Further, the atmosphere in vacuum sealing does not necessarily have to be an inert gas atmosphere, but in the case of an inert gas atmosphere, a sealing material having a higher melting point can be used by protecting the target with an inert gas.

Alternatively, the entire surface can be heated, and the equipment and work can be simplified.

As described above, according to the present invention, it is possible to provide an imaging manufacturing method having great practical value.

[Brief explanation of drawings]

1a, b, and c are cross-sectional views showing the assembly process (vacuum sealing process) of the main parts of a conventional image pickup tube; FIG. 2 is a cross-sectional view showing an image pickup tube according to an embodiment of the present invention; FIG. 3 is an enlarged sectional view of the main part of FIG. 2, and FIGS. 4a and 4b are seals used for vacuum sealing between the face plate and the vacuum envelope in the method for manufacturing an image pickup tube of the present invention. A plan view and a cross-sectional view showing an example of the material, FIG. 5 is a cross-sectional view showing an example of the vacuum sealing method for the face plate and the vacuum envelope in the method of manufacturing an image pickup tube of the present invention, and FIGS. b is a sectional view showing another example, FIG. 7 is a plan view showing another example of the sealing material, and FIG. 8 is a sectional view showing another example of the sealing material.
FIG. 3 is a cross-sectional view showing a method of vacuum sealing a face plate and a vacuum envelope when using the sealing material shown in the figure. 5... Vacuum envelope, 6... Face plate, 7... Annular signal electrode, 8...
Transparent conductive layer, 9...Photoconductive layer, 10...
・Photoelectric conversion target, 18, 32...Sealing material, 24...High frequency heating coil, 25...
・Metallic guide (block heater), 28...
・Push plate (block heater).

Claims (1)

[Claims] 1. In an image pickup tube formed by vacuum-sealing a face plate with a photoelectric conversion target formed on the inner surface at the open end of a cylindrical vacuum envelope, Sb and Zn are added to the Pb and Sn system. The annular sealing material is sandwiched between the open end surface of the vacuum envelope and the face plate, and while applying pressure, it is heated to a temperature lower than the melting point of the sealing material, so that the face plate and the vacuum A method for manufacturing an image pickup tube, characterized in that the envelope is sealed in vacuum. 2 Claim 1 of heating while applying ultrasonic vibrations
A method for manufacturing an image pickup tube as described in Section 1. 3. The method of manufacturing an image pickup tube according to claim 1, wherein the heating is high-frequency induction heating. 4. A method for manufacturing an image pickup tube according to claim 1, wherein the heating is performed by a block heater; 5. A patent for providing two or more protruding pieces facing the sealing material, and heating the protruding pieces by energizing them. A method for manufacturing an image pickup tube according to claim 1. 6 Claim 5 of heating while applying ultrasonic vibrations
A method for manufacturing an image pickup tube as described in Section 1. 7. The method of manufacturing an image pickup tube according to claim 1, wherein the face plate and the vacuum envelope are vacuum-sealed in an inert gas atmosphere.