JPS63152842A - Vacuum vessel and its manufacture - Google Patents

Abstract

PURPOSE:To ease an oxide treatment of a supporting frame as well as to prevent an unnecessary deformation of an optical window by forming the supporting frame with iron or an alloy including iron, and making the supporting frame and the optical window vacuum-airtightly jointed with the optical window hardly destroyed in an optical state. CONSTITUTION:Each supporting frame 5 and 10 is made of a metal, for instance, iron or alloy including iron, and each supporting frame 5 and 10, an input window 1, and an output window 3 are jointed vacuum-airtightly with each window hardly destroyed in an optical state, Furthermore, a ring supporting frame 5 is airtightly jointed by indium 7 to an end of a tubular vessel body 8 made of ceramics, a ring supporting plate 11 is fixed to the other end of the vessel body 8, and the supporting frame 10 is airtightly jointed to the supporting plate 11 by an arc welding 9. And the vicinity of each effective surface of the input window 1 and the output window 3 is projected to the vacuum side than each supporting frame 5 anc 10, an outside diameter of each effective surface is set to 0.5 mm or above smaller than an inside diameter of each supporting frame 5 and 10, and a gap G is provided. This enables an acid treatment to be available in an elimination of a metal oxide film, and a deformation of an output window eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a vacuum container suitable for use in image intensifier tubes, image pickup tubes, photoelectron intensifier tubes, etc., and a method for manufacturing the same.

(Prior Art) Generally, a vacuum container used for an image intensifier tube, an image pickup tube, a photoelectron intensifier tube, etc. has an optical window made of glass, such as an input window or an output window, bonded to a metal support frame. Moreover, it has a vacuum-tight structure. There are two methods for bonding the support frame (metal) used in such a vacuum container and the optical window (glass): softening the glass with a burner such as oxyhydrogen flame and fusing it, and using frit glass (solder glass). The mainstream method is to join by hand.

(Problems to be Solved by the Invention) However, in the former method, the flame spreads to areas other than where necessary, so an optically effective area cannot be secured unless a large number of fused parts are allowed. Further, in the latter method, since the frit glass has poor acid resistance, it is difficult to remove the oxide film from the metal portion.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, prevent unnecessary deformation of an optical window, and provide a vacuum container in which the support frame can be easily treated with oxide, and a method for manufacturing the same.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a vacuum container in which an optical window is bonded to a support frame, wherein the support frame is made of iron or an alloy containing iron;
This support frame and the optical window are a vacuum container formed by vacuum-tightly joining the optical window with almost no optical damage.

The optical window projects further toward the vacuum side than the support frame, and the outer diameter of the effective surface of the optical window is set smaller than the inner diameter of the support frame by 0.5 mm or more.

The present invention also provides a method for manufacturing a vacuum container in which an optical window is bonded to a support frame, in which the support frame is heated by high-frequency induction heating, and the support frame and the optical window are fused by heat conduction from the support frame. This is a method for manufacturing a vacuum container by bonding.

(Function) According to the present invention, unnecessary deformation of the optical window is prevented, and oxide treatment of the support frame is facilitated.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Taking a vacuum container for a proximity optical image intensifier tube as an example, the present invention is constructed as shown in FIG. That is, an input window 1 and an output window 1!3 made of glass, for example, optically polished, are disposed in close opposition to each other, and a photocathode 2 is formed on the inner effective surface of the input window 1, and the output An output fluorescent screen 4 is formed on the effective inner surface of the window 3.

The input window 1 has a ring-shaped support frame 5 at its periphery.
The peripheral edge of the output window 3 is joined to the ring-shaped support frame 10 by II bonding. 6 in the figure shows the fused portion. In this case, each support frame 5.10 is made of metal, such as iron or an alloy containing iron (for example, Kovar'), and each support frame 5.10, input window 1, and output window 3 are arranged so that each window is optically It is vacuum-tightly joined with almost no destruction.

Furthermore, the ring-shaped support frame 5 is hermetically bonded to one end of a ceramic cylindrical container body 8 with indium 7, and a ring-shaped support plate 11 is fixed to the other end of this container body 8. The support frame 10 is hermetically sealed together by arc welding 9.

In addition, the vicinity of each effective surface of the input window 1 and output window 3 is provided with each support frame 5.
．． 1o, and the outer diameter of each effective surface is set to be smaller than the inner diameter of each support frame 5.10 by 0.5 mm or more. In other words, a gap G is provided.

That is, in the proximity type optical image intensifier tube shown in FIG. 1, the distance between the photocathode 2 and the output phosphor screen 4 is close, and a high voltage is applied, so that withstand voltage becomes a problem. Moreover, when each support frame 5.10 is closer than the input window 1 and the output window 3, the withstand voltage deteriorates. Therefore, in the present invention, as described above, the vicinity of each effective surface of the input window 1 and the output window 3 protrudes further toward the vacuum side than each support frame 5.10. As will be described later, when glass is fused to the inner periphery of each support frame 5.10 in frequency welding, only each support frame 5.10 is heated and thermally expanded, as in arc welding. In this case, the inner periphery is more likely to be damaged. Therefore, as mentioned above, it is necessary to create a gap G between the inner circumference of each support frame 5.10 and each effective surface of the input window 1 and output window 3, and from the experimental results, it is necessary to create a gap G of 0.5 m.
By forming a gap G of m or more, damage can be prevented from occurring.

Now, to explain the manufacturing method of the present invention, for example, joining the output window 3 and the support frame 10, the support frame 10 is placed on the turntable 12 as shown in FIG. Place output window 3 on top. Then, the support frame 1o is heated by high-frequency induction by the high-frequency coil 13 to become red hot, and the glass of the output window 3 is softened and fused by the heat conduction, thereby joining the support frame 10 and the output window 3 in a vacuum-tight manner. Incidentally, the same applies to the case of joining the input window 1 and the support frame 5.

In the above-mentioned high-frequency induction heating, only the metal parts are heated, so
Since only the portion of the glass in contact with the metal portion is softened and fused, an airtight joint is completed without causing deformation of the output window 3 (input window 1).

In the proximity optical image intensifier tube using a vacuum container as described above, during operation, a light image passing through the input window 1 is converted into an electronic image by the photocathode 2, and the photocathode 2 and the output phosphor screen 4 are connected to each other. The light is accelerated by a high voltage applied between them, becomes a light image again on the output phosphor screen 4, and is taken out from the output window 4.

(Modified Examples) FIGS. 2 and 6 show modified examples (various shapes) of the support frame 10 that supports the output window 3, and the same effects as in the above embodiment can be obtained.

It should be noted that the support frame 5 that supports the input window 1 may also be modified in various shapes similar to those described above.

[Effects of the invention] As a result of experiments, it has been found that conventional joining of glass and metal usually requires a considerable amount of time to acquire the skills, but according to this invention, it is possible for people who have no experience in glass processing to Work can be done on the same day.

Further, according to the present invention, since the output phosphor screen 4 can be formed directly on the output window 3, surface Fresnel reflection of the output window 3 can be reduced and contrast can be improved. Since there is no intervention other than glass and metal, acid treatment can be used to remove the metal oxide film.

Furthermore, since there is no deformation of the output window 3, the minimum amount of material required is required and the device can be made more compact.

According to the experimental results, the vacuum tightness is 100%, the pressurized strength test is performed with a support material thickness of 1.2 mm, and a diameter of output window 3 of 45 m.
m, thickness 3.0mm, pressurize 3KG/crl to 10
It was confirmed that the product was 0% non-defective and had a strength more than three times that of atmospheric pressure.

It goes without saying that the input window 1 also provides the same effect as the output window 3.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a proximity optical image intensifier tube using a vacuum container according to an embodiment of the present invention, FIGS. 2 to 6 are cross-sectional views showing modified examples of the present invention, and FIG. FIG. 3 is a cross-sectional view showing the manufacturing method of the present invention. 1... Input window (optical window), 3... Output window (optical window)
, 5.10...Support frame. Applicant's representative Patent attorney Takehiko Suzue Houki 1 Figure 2 Figure 3 tlKt, 12I Figure 5 Figure 6 Figure 7

Claims (4)

[Claims] (1) In a vacuum container in which an optical window is bonded to a support frame, the support frame is made of iron or an alloy containing iron, and the support frame and the optical window are such that the optical window is almost optically destroyed. A vacuum container characterized by being vacuum-tightly joined without any damage. (2) The vacuum container according to claim 1, wherein the optical window projects further toward the vacuum side than the support frame. (3) The outer diameter of the effective surface of the optical window is smaller than the inner diameter of the support frame by 0.5 mm or more as claimed in Claims 1 and 2.
Vacuum container as described in section. (4) In a method for manufacturing a vacuum container in which an optical window is bonded to a support frame, the support frame is heated by high-frequency induction heating, and the support frame and the optical window are fused and bonded by heat conduction from the support frame. A method for manufacturing a vacuum container characterized by: