US3835250A

US3835250A - Explosion-proof cathode-ray tubes

Info

Publication number: US3835250A
Application number: US00413331A
Authority: US
Inventors: N Cherednik; L Pravednaya; A Kasakov; A Saposkov; A Lischinsky; A Kaljuko; F Simkhovich
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-27
Filing date: 1973-11-06
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10

Abstract

An explosion-proof cathode-ray tube has an anti-explosion device made as an annular frame which is mounted onto the tube envelope at a critical zone thereof so that there is a gap therebetween which is filled with a self-expanding filler. The frame is provided with a flange, contacting the envelope at the side of the tube screen along the whole of its perimeter, and having a recess facing the surface of the envelope that corresponds to the critical zone of the envelope. The recess has a special profile designed in a manner ensuring a counterbalancing of axial tensions occuring in the tube envelope in its critical zone.

Description

United States Patent [191 Kaljuko et a1.

[451 Sept. 10,1974

[ EXPLOSION-PROOF CATHODE-RAY TUBES [22] Filed: Nov. 6, 1973 [21] Appl. No.: 413,331

Related U.S. Application Data [63] Continuation of Ser. No. 325,127, Jan. 19, 1973, abandoned, which is a continuation of Ser. No. 187,274, Oct. 7, 1971, abandoned.

[30] Foreign Application Priority Data Oct. 27, 1970 U.S.S.R 1481151 Dec. 19, 1970 U.S.S.R 1496301 [52] U.S. Cl l78/7.8, l78/7.82, 220/2.l A

[51] Int. Cl H01j 31/08, HOlk l/28 [58] Field of Search l78/7.8, 7.82; 220/21 A, 220/23 A [56] References Cited UNITED STATES PATENTS 3,278,682 10/1966 Panis 178/7.8

3,314,566 4/1967 Minneman 220/2.1 A

3,558,818 1/1971 DeBoer 178/7.82

Primary Examiner-Howard W. Britton Attorney, Agent, or Firm-Holman & Stern [5 7] ABSTRACT An explosion-proof cathode-ray tube has an antiexplosion device made as an annular frame which is mounted onto the tube envelope at a critical zone thereof so that there is a gap therebetween which is filled with a self-expanding filler. The frame is provided with a flange, contacting the envelope at the side of the tube screen along the whole of its perimeter, and having a recess facing the surface of the envelope that corresponds to the critical zone of the envelope. The recess has a special profile designed in a manner ensuring a counterbalancing of axial tensions occuring in the tube envelope in its critical zone.

4 Claims, 6 Drawing Figures EXPLOSION-PROOF CATHODE-RAY TUBES PRIOR APPLICATIONS BACKGROUND OF THE INVENTION The present invention relates to electron vacuum devices and, in particular, to cathode-ray tubes provided with anti-explosion devices.

Known in the art are cathode-ray tubes with antiexplosion devices, embracing the tube envelope along its critical zone and having the shape of a frame mounted onto the envelope with a gap to be filled with a filler, the frame being provided with a flange contacting the envelope on the side of the tube screen along the whole of its perimeter. Hence, the tube envelope is made explosion-proof with the help of a frame having a flange and with the help of a filler stuck into the gap between the frame and the envelope.

Such a cathode-raytube with an anti-explosion device comprises a single-ribbon frame of variable thickness or a multi-ribbon frame welded of a number of separate ribbons which is tightly pulled onto the side surface of the tube envelope over its critical zone so that between the frame and the envelope there would be a gap to be filled with a filler. However, the combined action of the metal frame and the tiller of such an anti-explosion device is exploited incompletely and does not ensure complete explosion-protection of said cathode-ray tubes. Additionally, the metal consumption of such frames is rather high and amounts to 5-15 percent.

The above anti-explosion devices for cathode-ray tubes do not ensure the required degree of explosion protection since they do not provide sufficient compensation for maximum axial tensil forces in the critical zone of the envelope.

SUMMARY OF THE INVENTION tube having an anti-explosion device, embracing the tube envelope along its critical zone and which has the shape of a frame mounted onto the envelope with a gap' to be filled with a filler, the frame being provided with a flange contacting the tube envelope on the side of the shape of an arc;

tube screen along the whole of its perimeter, further,

according to the invention, the frame has a recess in its surface facing the tube envelope in the critical zone of the latter. The frame is also designed so as to compensate for the axial tensile stresses occuring in the tube envelope in its critical zone.

It is preferred that the frame of the anti-explosion device should be designed with a recess having the cross sectional shape of an arc.

In another embodiment of the invention the frame of the anti-explosion device is preferably designed with a recess having the cross sectional shape of an angle.

In a further embodiment of the invention the frame of the anti-explosion device is preferably designed with a recess of a rectangular cross section.

The invention provides tubes having reliable explosion protection and makes possible reduction of material and of labor consumption required for the manufacturing of cathode-ray tubes with anti-explosion devices.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood from the description of an embodiment given by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows the general view of a cathode-ray tube with an anti-explosiondevice according to the invention illustrating the tube envelope in part-section;

FIG. 2 is a view similar to that of FIG. 1, but viewed from above;

FIG. 3 is a view showing the section along III-III as in FIG. 2;

F IG. 4 is a view showing the section along IV-IV as in FIG. 2;

FIG. 5 shows a part-section the second version of the anti-explosion device made with a recess having the FIG. 6 shows the third version of the anti-explosion device made with a recess of a rectangular shape (longitudinal section).

The cathode-ray tube, according to the invention, is provided with an anti-explosion device 1 (FIG. 1) made as a single-ribbon annular frame 2 of constant thickness which follows the contour of the periphery of the tube screen and which is mounted on the side surface of the tube in the critical zone of the envelope 3 corresponding to the rim of the screen and to the area where the screen is attached to the tube cone. The frame 2 has a channel like recess 4 of rectangular cross section running along the whole of its perimeter.

The recess 4 tapers upwards along the height of the frame 2 to form a flange 5 constituting the upper part of the frame. The contact between the frame 2 and the side surface of the tube is effected through the flange 5 (FIG. 2), the perimeter of which is somewhat less than that of the tube envelope 3 (FIG. 1) along the line of contact, due to which a certain amount of tensile stress in the critical zone of the tube envelope is counter-balanced. The frame 2 can practically embrace the whole critical zone of the tube envelope 3. It is mounted on the side surface of the tube so that the recess 4 faces the critical zone in the region of maximum stress to which the tube envelope 3 is subjected. When the frame 2 is tightly pulled over the envelope a gap appears adjacent the line of contact between the frame and the side surface of the tube. The gap is then filled with a self-expanding tiller 6, eg with alebaster.

The distribution of tensile stresses in the critical zone of the tube envelope 3 is not'uniform along its perimeter. The maximum tensile stress occurs in the corners of the screen and decreases towards the centers of its sides. To counterbalance the stress in the critical zone of the envelope 3 in a uniform manner the frame 2 is made so that the angle a of the flange 5 is variable along the perimeter of the frame 2 in contrast to known anti-explosion devices. The value of the angle a is se lected in accordance with the amount of tensile stress to be countered and can vary from 3 to When the tube has a round screen the angle a of the flange will be constant and will be selected within the above range depending on the value of axial tensile stress in the tube envelope 3.

FIG. 3 illustrates a section of the tube envelope 3 with the anti-explosion device 1, the section being made along the IIIIII line as in FIG. 2. The angle a, of the flange 5 is minimum; it is selected from 3 and higher. It is preferable that the angle a, be selected between and.20.

FIG. 4 illustrates a section of the tube envelope with the anti-explosion device 1, the section being made along the lV-IV line as in FIG. 2. The maximum angle a is selected to be 90 and lower. It is preferable that the 0: angle be selected between 45 and 50.

The maximum tensile forces in the critical zone of the tube envelope 3 are counterbalanced by the total action of all compensation forces. These are: the tightness of the frame 2 caused by the elastic deformation of the flange 5 and the expansion of the filler 6 affecting the envelope 3 right in its critical zone. Here, the thickness of the filler 6 layer and the counterbalance force produces depend upon the recess 4. Additional compression of the envelope 3 is caused also by the elastic properties of the frame 2 manifested through its co-action with the self-expanding filler 6.

The recess 4 in the frame 2 can be of various shapes depending upon the application of the cathode-ray tube having the anti-explosion device 1.

Illustrated in FIG. 5 is a section of a cathode-ray tube with the anti-explosion device 1 whose frame 2 is provided with a recess 7 having the shape of an arc.

FIG. 6 shows a section of a cathode-ray tube with the anti-explosion device I provided with a recess 8 having the shape of an angle.

The anti-explosion device protects the cathode-ray tube from an accidental explosion caused by a defect in the envelope 3 as well as from an explosion caused by a mechanical damage of the tube envelope 3. It is most preferable to use the anti-explosion devices 1 of the type described herein with larger cathode-ray tubes that might explode with a great force. The employment of the present antiexplosion device 1 makes it possible to practically avoid explosions.

The anti-explosion device 1 is mounted onto the envelope 3 of a cathode-ray tube in the following way.

The frame 2 having a substantially rectangular recess 4 and a flange 5 whose angle 0: with the tube envelope varies along the perimeter of the frame 2 from to 45, is pulled tightly with the force of 2-3 tonnes over the side surface of the tube envelope 3. The frame 2 is mounted in such a way that the recess 4 should be opposite the area of maximum stress in the critical zone of the tube envelope 3. The gap that is formed between the side surface of the envelope 3 and the frame 2 is filled with an alebaster mixture of definite concentration ensuring that the whole of the gap is tightly filled. In the course of solidification the alebaster, which has adhesive properties, expands and compresses the envelope 3 counterbalancing the stress in its critical zone. Under normal conditions the initial process of alebaster solidification lasts 15-20 min. At higher temperatures however; this process can be accelerated. The explosion-proof action of the anti-explosion device 1 is fully effective only after the process of complete solidification of the alebaster material is over, which, under normal conditions, takes about 24 hours.

The cathode-ray tube with the anti-explosion device described above increases the efficiency of explosion protection and ensures savings in labour and materials during tube manufacture.

What is claimed is:

1. An explosion-proof cathode-ray tube comprising:

an envelope having a screen portion and a core portion;

an anti-explosion means embracing the surface of said envelope in a critical zone, which zone defines a region where said screen portion is attached to said cone portion; and

a frame means of said anti-explosion means peripherally mounted on said surface of said envelope so that a gap is formed between said frame and said envelope, which gap is filled with a consolidated filler material, said frame means having a flanged portion and a recessed portion, said flanged portion tensionally contacting the perimeter of said screen portion of said envelope in the vicinity of said critical zone, said recessed portion facing the surface of said screen portion of said envelope along said critical zone and having a constant cross-sectional shape around said frame perimeter so as to counter-balance together with said tensionally contacting flanged portion, axial tensile stresses which occur in said critical zone. 2. A cathode-ray tube as claimed in claim 1, wherein said recess is are shaped in cross-section.

3. A cathode-ray tube as claimed in claim 1, wherein said recess has an angle-shaped cross-section.

4. A cathode-ray tube as claimed in claim 1, wherein said recess has a rectangular cross section.

Claims

1. An explosion-proof cathode-ray tube comprising: an envelope having a screen portion and a core pOrtion; an anti-explosion means embracing the surface of said envelope in a critical zone, which zone defines a region where said screen portion is attached to said cone portion; and a frame means of said anti-explosion means peripherally mounted on said surface of said envelope so that a gap is formed between said frame and said envelope, which gap is filled with a consolidated filler material, said frame means having a flanged portion and a recessed portion, said flanged portion tensionally contacting the perimeter of said screen portion of said envelope in the vicinity of said critical zone, said recessed portion facing the surface of said screen portion of said envelope along said critical zone and having a constant cross-sectional shape around said frame perimeter so as to counter-balance together with said tensionally contacting flanged portion, axial tensile stresses which occur in said critical zone.

2. A cathode-ray tube as claimed in claim 1, wherein said recess is arc shaped in cross-section.