CA1186364A - Picture tube with protective facility - Google Patents
Picture tube with protective facilityInfo
- Publication number
- CA1186364A CA1186364A CA000398426A CA398426A CA1186364A CA 1186364 A CA1186364 A CA 1186364A CA 000398426 A CA000398426 A CA 000398426A CA 398426 A CA398426 A CA 398426A CA 1186364 A CA1186364 A CA 1186364A
- Authority
- CA
- Canada
- Prior art keywords
- inhomogeneities
- funnel
- shaped
- wall
- picture tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/86—Vessels; Containers; Vacuum locks
- H01J29/87—Arrangements for preventing or limiting effects of implosion of vessels or containers
Landscapes
- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
PICTURE TUBE WITH PROTECTIVE FACILITY
Abstract of the Disclosure A few sharply defined and irregularly distributed obstacles in the form of inhomogeneities are provided in or at the funnel section of a picture tube. This influences the process of an unavoidable implosion from the very beginning as cracks are formed at the inhomogeneities as a result of the energy accumulation in case of impacts endangering the tube. These cracks propogate immediately to the tube neck, where they result in safe devacuation of the tube.
Abstract of the Disclosure A few sharply defined and irregularly distributed obstacles in the form of inhomogeneities are provided in or at the funnel section of a picture tube. This influences the process of an unavoidable implosion from the very beginning as cracks are formed at the inhomogeneities as a result of the energy accumulation in case of impacts endangering the tube. These cracks propogate immediately to the tube neck, where they result in safe devacuation of the tube.
Description
Background of the Invent _n The presen-t invention relates to a p:icture tube com-prising a faceplate, a funnel, and a neck provided with an implosion proof facility.
In the course of their development, picture tLbes for monochrome and color television sets have been made much more implosion-proof by improvements in their shape. The risk of destruction as a result of bumps on the glass body of the tube has been greatly reduced. It is known, however, -that the implosion of a picture tube presents quite di-fferent dangers to the surroundings depending on where the fracture begins.
It is, therefore, disadvantageous if the funnel section of the tube is too resistant compared -to the faceplate or panel section, for the fragments of the front glass panel can -then be reflected from he funnel in the forward direction. It hasl therefore, been proposed to reduce the resistance to the impac-t of fragments and, thus, eliminate the risk of reflec--tion by means of a ring o:E predetermi.ned breaking points around the funnel section, so that no fragments of the glass panel will be thrown back toward the viewer. However, this measure acts on the implosion process relatively late, namely when the panel fragments strike the wall of the funnel.
Summary of the Invention It is, therefore, an object o.E the presen-t invention to provide a more effective means for reducing the danger of implosion in a picture -tube.
According to the invention, the implosi.on process is influenced from the very beginning by a few sharply defined and irregularly distributed obstacles to thi? s11ock waves occur-ring in the Eunne1 wall wh:ict1 cbst.1c:1es i.l1 Ll~e L`0~.`11~ cil- a plu~--ali-ty oE wal.l-th:i.ck1le~ss ancl~o~~ wa11.-~ t-e~:ial irre~Ju1.1~:1.y ti3~
distributed inhomogeneities in the funnel wall. As impacts on the tube cause an accumulation of eneryy o~ the inhomoyene-i-ties, the inhomogeneities a-t the neck-to-funnel transition cause cracks to start at those points. Such a crack will immed-iately proceed to the tube neck and, thus, result in relatively safe devacuation of the tube. In an preferred embodiment, each inhomogeneity has a circumscribed circle thereabout, measured in the surface of the funnel, which is 0.001 to 0.1 -times the funnel circumference at that point.
The shock waves caused in the glass wall by impacts delivered to the tube envelope are reflected by the inhomogene-ities. Excessive internal stresses are caused in the glass envelope particularly if the inhomogeneity is located at a vibration antinode of the envelope.
The location of these vibration areas depends on the point of impact, so that several inhomogeneities will advan-tageously be irregularly distributed over the surface of the Eunnel in such a way that the distance from one inhomogeneity to one or more further inhomogeneities, measured in the surface of the funnel, is at least equal to half the length of the circumference of an inhomogeneity.
To safely keep any undesirable fracture yrow-th at an inhomoyeneity to a subcritical ra-te, inhomogeneities are advantageously provided at points of the tube which are substan-tially free of tensile strain.
The neck-to-funnel and funnel-to-faceplate transition zones are less resistant, so that the inhomogeneities will advantageously be spaced at least the length of their circum-ference from the cylindrical portion of the neck and from the line at which the facepla-tc? and tlle ~ullnel ale -joined.
~63~
The inhomogeneities should be bounded so that a maxi-mum gradient of internal stress can occur at their boundaries.
Therefore, the inhornogenei-ties ;3~
include combinations of line-shaped depressions and/or elevations in/of the glass wall, i.e., are I-, I-, V-, Y- or X-shaped.
Such inhomogeneities can be implemented, for example, with metallic inclusions in the glass wall of the funnel. They may also be ground or cut into the inside or outside of the glass wall, or they may be obtained by thermally or chemically introducing internal stresses into the glassA
The desired effects were proved by implos;on tests as specified by VDE (Association of German ~lectrical Engineers) and Underwriters Laboratories Inc. The crack started at the inhomogeneity and travelled to the neck of the tube. There, devacuation was consequently initiated, so that the pressure e~erted in the front panel would no longer be sufficient to accelerate any fragments of glass if a crack had formed there.
This result was obtained with a 1 mm deep I-shaped depression in the inside surface of the funnel of an A55-14X color picture tube. The length of this depression was about 20mm.
Brief Descri~tion of the Drawin~
Above mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the ~ccompanying drawing, in which:
Fig. 1 shows the basic shape of the discontinuities, herein called "inhomogeneities", in the wall of the glass envelope;
Fig. 2 shows cross sections through portions of the glass envelope where inhomogeneities, namely ribs, steps and depressions, are formed in the wall;
Fig. 3 shows corresponding inhomogeneities which are subsequently attached to or formed in the wall;
Fig. 4 shows an inhomogeneity introduced into the wall of the envelope;
~:~86;3~4~
Fig. 5 shows an inhomogeneity and its circumscribed circle (broke line) which is to be understood as the circumference U of the inhomogeneity;
Fig. 6 illustrates the proportions of the arrangement of inhomoge-neities on the funnel of the picture tube; and Fig. 7 indicates the formation of a crack in the presence of an in-homogeneity according to the invention.
Description of the Preferred Embodiment The implosion of a picture tube involves relatiYely little danger if eracks form at the neck-to-cone transition at least simultaneously but if possible earlier than in other areas. In that case, the vacuum in the tube will be reduced from the rear before fragments of the front glass panel are accelerated by the violent devacuation.
The invention, therefore, mal~es use of the inhomogeneities shown in Figs. 1 to 4, which serve to eonvert the energy of an impact on the glass en-velope into internal stresses at the desired point of the envelope, the internal stress being essential to produee an effective reflection. The obstacle may be a mass excess, a mass deficiency or a deformation. If the obstacle is represented by a foreign-body inclusion, an added advantage is gained if the thermal expan-sion of the inclusion is chosen so that if the tube is greatly over-heated, internal stresses will also be produced at the inhomogeneity located at the small funnel end; this inhomogeneity will then initiate the implosion at the desired point.
As shown in Fig. 3, an inhomogeneity of a different material may also be soldered on, for example. All measures of Figs. 1- 4 rnay be taken on the inside or outside wall of the tube.
In the course of the development of television tubes, the risk of destruction due to external loading has been greatly reduced. The funnel-to-~1863S~L
neck transition and the seal area between the front panel and the funnel are,of course, more sensitive than the other tube areas. Therefore, as shown in Fig.
~i, the inhomogeneities should be spaced about 1- 2 U apart, where U is the cir-cumference of an inhomogeneity (see Fig. 5). Within the remaining area of the funnel surface, two or more inhomogeneities, also of different kind, may be provided, for the propagation paths of the vibration energy are different at different points, particularly on the front panel surface, and after a few reflections nodes and antinodes of the glass envelope vibrations are formed in the different areas. As experiments have shown, the crack formed at an inhomogeneity travels into the relatively easily separating neck-to-funnel transition area as desired.
Advantageously, the inhomogeneity points in the direction of the tube neck.
While I have described above the principles of my invention in con-nection with specific apparatus, it is to be clearly understood that this description is made only by way of e2cample and not as a limitation to the scope of my in-vention as set forth in the objects thereof and in the accompanying claims.
In the course of their development, picture tLbes for monochrome and color television sets have been made much more implosion-proof by improvements in their shape. The risk of destruction as a result of bumps on the glass body of the tube has been greatly reduced. It is known, however, -that the implosion of a picture tube presents quite di-fferent dangers to the surroundings depending on where the fracture begins.
It is, therefore, disadvantageous if the funnel section of the tube is too resistant compared -to the faceplate or panel section, for the fragments of the front glass panel can -then be reflected from he funnel in the forward direction. It hasl therefore, been proposed to reduce the resistance to the impac-t of fragments and, thus, eliminate the risk of reflec--tion by means of a ring o:E predetermi.ned breaking points around the funnel section, so that no fragments of the glass panel will be thrown back toward the viewer. However, this measure acts on the implosion process relatively late, namely when the panel fragments strike the wall of the funnel.
Summary of the Invention It is, therefore, an object o.E the presen-t invention to provide a more effective means for reducing the danger of implosion in a picture -tube.
According to the invention, the implosi.on process is influenced from the very beginning by a few sharply defined and irregularly distributed obstacles to thi? s11ock waves occur-ring in the Eunne1 wall wh:ict1 cbst.1c:1es i.l1 Ll~e L`0~.`11~ cil- a plu~--ali-ty oE wal.l-th:i.ck1le~ss ancl~o~~ wa11.-~ t-e~:ial irre~Ju1.1~:1.y ti3~
distributed inhomogeneities in the funnel wall. As impacts on the tube cause an accumulation of eneryy o~ the inhomoyene-i-ties, the inhomogeneities a-t the neck-to-funnel transition cause cracks to start at those points. Such a crack will immed-iately proceed to the tube neck and, thus, result in relatively safe devacuation of the tube. In an preferred embodiment, each inhomogeneity has a circumscribed circle thereabout, measured in the surface of the funnel, which is 0.001 to 0.1 -times the funnel circumference at that point.
The shock waves caused in the glass wall by impacts delivered to the tube envelope are reflected by the inhomogene-ities. Excessive internal stresses are caused in the glass envelope particularly if the inhomogeneity is located at a vibration antinode of the envelope.
The location of these vibration areas depends on the point of impact, so that several inhomogeneities will advan-tageously be irregularly distributed over the surface of the Eunnel in such a way that the distance from one inhomogeneity to one or more further inhomogeneities, measured in the surface of the funnel, is at least equal to half the length of the circumference of an inhomogeneity.
To safely keep any undesirable fracture yrow-th at an inhomoyeneity to a subcritical ra-te, inhomogeneities are advantageously provided at points of the tube which are substan-tially free of tensile strain.
The neck-to-funnel and funnel-to-faceplate transition zones are less resistant, so that the inhomogeneities will advantageously be spaced at least the length of their circum-ference from the cylindrical portion of the neck and from the line at which the facepla-tc? and tlle ~ullnel ale -joined.
~63~
The inhomogeneities should be bounded so that a maxi-mum gradient of internal stress can occur at their boundaries.
Therefore, the inhornogenei-ties ;3~
include combinations of line-shaped depressions and/or elevations in/of the glass wall, i.e., are I-, I-, V-, Y- or X-shaped.
Such inhomogeneities can be implemented, for example, with metallic inclusions in the glass wall of the funnel. They may also be ground or cut into the inside or outside of the glass wall, or they may be obtained by thermally or chemically introducing internal stresses into the glassA
The desired effects were proved by implos;on tests as specified by VDE (Association of German ~lectrical Engineers) and Underwriters Laboratories Inc. The crack started at the inhomogeneity and travelled to the neck of the tube. There, devacuation was consequently initiated, so that the pressure e~erted in the front panel would no longer be sufficient to accelerate any fragments of glass if a crack had formed there.
This result was obtained with a 1 mm deep I-shaped depression in the inside surface of the funnel of an A55-14X color picture tube. The length of this depression was about 20mm.
Brief Descri~tion of the Drawin~
Above mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the ~ccompanying drawing, in which:
Fig. 1 shows the basic shape of the discontinuities, herein called "inhomogeneities", in the wall of the glass envelope;
Fig. 2 shows cross sections through portions of the glass envelope where inhomogeneities, namely ribs, steps and depressions, are formed in the wall;
Fig. 3 shows corresponding inhomogeneities which are subsequently attached to or formed in the wall;
Fig. 4 shows an inhomogeneity introduced into the wall of the envelope;
~:~86;3~4~
Fig. 5 shows an inhomogeneity and its circumscribed circle (broke line) which is to be understood as the circumference U of the inhomogeneity;
Fig. 6 illustrates the proportions of the arrangement of inhomoge-neities on the funnel of the picture tube; and Fig. 7 indicates the formation of a crack in the presence of an in-homogeneity according to the invention.
Description of the Preferred Embodiment The implosion of a picture tube involves relatiYely little danger if eracks form at the neck-to-cone transition at least simultaneously but if possible earlier than in other areas. In that case, the vacuum in the tube will be reduced from the rear before fragments of the front glass panel are accelerated by the violent devacuation.
The invention, therefore, mal~es use of the inhomogeneities shown in Figs. 1 to 4, which serve to eonvert the energy of an impact on the glass en-velope into internal stresses at the desired point of the envelope, the internal stress being essential to produee an effective reflection. The obstacle may be a mass excess, a mass deficiency or a deformation. If the obstacle is represented by a foreign-body inclusion, an added advantage is gained if the thermal expan-sion of the inclusion is chosen so that if the tube is greatly over-heated, internal stresses will also be produced at the inhomogeneity located at the small funnel end; this inhomogeneity will then initiate the implosion at the desired point.
As shown in Fig. 3, an inhomogeneity of a different material may also be soldered on, for example. All measures of Figs. 1- 4 rnay be taken on the inside or outside wall of the tube.
In the course of the development of television tubes, the risk of destruction due to external loading has been greatly reduced. The funnel-to-~1863S~L
neck transition and the seal area between the front panel and the funnel are,of course, more sensitive than the other tube areas. Therefore, as shown in Fig.
~i, the inhomogeneities should be spaced about 1- 2 U apart, where U is the cir-cumference of an inhomogeneity (see Fig. 5). Within the remaining area of the funnel surface, two or more inhomogeneities, also of different kind, may be provided, for the propagation paths of the vibration energy are different at different points, particularly on the front panel surface, and after a few reflections nodes and antinodes of the glass envelope vibrations are formed in the different areas. As experiments have shown, the crack formed at an inhomogeneity travels into the relatively easily separating neck-to-funnel transition area as desired.
Advantageously, the inhomogeneity points in the direction of the tube neck.
While I have described above the principles of my invention in con-nection with specific apparatus, it is to be clearly understood that this description is made only by way of e2cample and not as a limitation to the scope of my in-vention as set forth in the objects thereof and in the accompanying claims.
Claims (20)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An implosion proof picture tube comprising:
a faceplate;
a neck;
a funnel disposed between and fastened to said faceplate and said neck; and a plurality of sharply defined and irregularly distributed inhomogeneities disposed at said funnel responsive to shock waves in a wall of said funnel to cause a crack to develop in said wall of said funnel extending from at least one of said plurality of inhomogeneities toward said neck to provide a safe devacuation of said tube upon occurrence of a destructive impact on said tube.
a faceplate;
a neck;
a funnel disposed between and fastened to said faceplate and said neck; and a plurality of sharply defined and irregularly distributed inhomogeneities disposed at said funnel responsive to shock waves in a wall of said funnel to cause a crack to develop in said wall of said funnel extending from at least one of said plurality of inhomogeneities toward said neck to provide a safe devacuation of said tube upon occurrence of a destructive impact on said tube.
2. A picture tube according to claim 1, wherein each of said plural-ity of inhomogeneities has a circumscribed circle thereabout, measured on a surface of said funnel, having a circumference equal to 0.001 to 0.1 times a cir-cumference of said wall of said funnel passing therethrough.
3. A picture tube according to claim 2, wherein each of said plurality of inhomogeneities is spaced from each of the others of said plurality of inhomo-geneities a distance, measured on a surface of said wall of said funnel, at least equal to one half of a length of a circumference of one of said plurality of in-homogeneities.
4. A picture tube according to claim 3, wherein each of said plurality of inhomogeneities are spaced from said neck and from said faceplate an amount equal to at least a circumference of one of said plurality of inhomogeneities.
5. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities includes line-shaped depressions in said wall of said funnel having a shape selected from I-shaped, T-shaped, V-shaped, Y-shaped and X-shaped.
6. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities includes line-shaped elevations in said wall of said funnel having a shape selected from I-shaped, T-shaped, V-shaped, Y-shaped and X-shaped.
7. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities includes a metallic member in said wall of said funnel.
8. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities is ground into an inner surface of said wall of said funnel.
9. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities is ground into an outer surface of said wall of said funnel.
10. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities is a thermally introduced internal stress in said wall of said funnel.
11. A picture tube according to claim 4, wherein each of said plurality of inhomogeneities is a chemically introduced internal stress in said wall of said funnel.
12. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities is spaced from each of the others of said plurality of inhomo-geneities a distance, measured on a surface of said wall of said funnel, at least equal to one half of a length of a circumference of one of said plurality of in-homogeneities.
13. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities are spaced from said neck and from said faceplate an amount equal to at least a circumference of one of said plurality of inhomogeneities.
14. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities includes line-shaped depressions in said wall of said funnel having a shape selected from I-shaped, T-shaped, V-shaped, Y-shaped and X-shaped.
15. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities includes line-shaped elevations in said wall of said funnel having a shape selected from I-shaped, T-shaped, V-shaped, Y-shaped and X-shaped.
16. A picture tube according to claim 1, wherein each of said plu-rality of inhomogeneities includes a metallic member in said wall of said funnel.
17. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities is ground into an inner surface of said wall of said funnel.
18. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities is ground into an outer surface of said wall of said funnel.
19 A picture tube according to claim 1, wherein each of said plurality of inhomogeneities is a thermally introduced internal stress in said wall of said funnel.
20. A picture tube according to claim 1, wherein each of said plurality of inhomogeneities is a chemically introduced internal stress in said wall of said funnel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3110930.6 | 1981-03-20 | ||
| DE19813110930 DE3110930A1 (en) | 1981-03-20 | 1981-03-20 | IMAGE TUBES WITH PROTECTIVE DEVICE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186364A true CA1186364A (en) | 1985-04-30 |
Family
ID=6127821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000398426A Expired CA1186364A (en) | 1981-03-20 | 1982-03-16 | Picture tube with protective facility |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0061103A3 (en) |
| JP (1) | JPS57197735A (en) |
| CA (1) | CA1186364A (en) |
| DE (1) | DE3110930A1 (en) |
| FI (1) | FI820937L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1244131A1 (en) * | 2001-03-22 | 2002-09-25 | Schott Glas | Cathode ray tube |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3720345A (en) * | 1970-06-08 | 1973-03-13 | Owens Illinois Inc | Television bulb with improved strength |
| DE2407527B2 (en) * | 1974-02-16 | 1976-01-08 | Jenaer Glaswerk Schott & Gen., 6500 Mainz | Cathode ray tube flasks with a rectangular screen |
| JPS50123267A (en) * | 1974-03-15 | 1975-09-27 | ||
| US4158419A (en) * | 1977-12-27 | 1979-06-19 | Rca Corporation | Implosion protected CRT |
| US4245255A (en) * | 1979-04-13 | 1981-01-13 | Corning Glass Works | Implosion protection for TV tubes |
-
1981
- 1981-03-20 DE DE19813110930 patent/DE3110930A1/en not_active Withdrawn
-
1982
- 1982-03-13 EP EP82102035A patent/EP0061103A3/en not_active Withdrawn
- 1982-03-16 CA CA000398426A patent/CA1186364A/en not_active Expired
- 1982-03-18 FI FI820937A patent/FI820937L/en not_active Application Discontinuation
- 1982-03-19 JP JP4443982A patent/JPS57197735A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FI820937L (en) | 1982-09-21 |
| JPS57197735A (en) | 1982-12-04 |
| EP0061103A2 (en) | 1982-09-29 |
| EP0061103A3 (en) | 1982-12-08 |
| DE3110930A1 (en) | 1982-09-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |