Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
2000-09-28
2002-06-11
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S482000, C220S00210A, C348S822000, C428S343000
Reexamination Certificate
active
06404121
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an explosion-proof tape of a cathode-ray tube and an explosion-proof structure of the cathode-ray tube, in which a metal band shrink-fitted to the outer circumference of the cathode-ray tube through the tape can be removed easily so that the cathode-ray tube can be recycled efficiently. The present application is based on Japanese Patent Application No. Hei. 11-275687, which is incorporated herein by reference.
2. Description of the Related Art
A cathode-ray tube often used as a television picture tube, a monitor for a personal computer, a word processor, etc., or the like, is subjected to explosion-proof treatment so as to be prevented from implosion because the cathode-ray tube is formed as a glass tube the inside of which is at a vacuum. A structure where an explosion-proof tape is wound on the outer circumference of a panel portion of the cathode-ray tube and a metal band is shrink-fitted on the tape is a typical one of the explosion treatment. According to such an explosion-proof structure, a bending moment generated by the atmosphere against the front surface of the cathode-ray tube due to the vacuum inside the cathode-ray tube is relieved and reduced by an opposite bending moment acting on the basis of the clamping pressure of the metal band so that the implosion is prevented.
In the background art, as such an explosion-proof tape, there has been known a tape in which a rubber or acrylic adhesive layer or the like to adhere to a cathode-ray tube in high strength is provided on a support formed by laminating a polyester or polyethylene layer on a glass or cotton cloth. According to this explosion-proof tape, when the explosion-proof tape is bonded with a cathode-ray tube through the adhesive layer and a metal band is shrink-fitted thereon, the support of the explosion-proof tape is fused to adhere to the metal band firmly.
However, when it is attempted to salvage an abandoned cathode-ray tube and reclaim glass material therefrom in view of the preservation of global environment, the effective use of resources, and so on, it is difficult to break up the cathode-ray tube because the metal band firmly adheres to the cathode-ray tube through the fused solid layer of the explosion-proof tape. In addition, there is a problem that the fused solid support of the explosion-proof tape projecting from the metal band adhere to the cathode-ray tube firmly so that it takes much time and much labor for the work of erasing the fused solid substances, the processing of grinding them, or the like. Thus, such problems have been obstacles to recycling cathode-ray tubes.
In the above-mentioned case, if it is insufficient to erase the fused solid layer of the explosion-proof tape from the cathode-ray tube, the components of the explosion-proof tape are carbonized to lower the quality of glass material obtained by the operation of reduction thereof when the cathode-ray tube is broken up into a panel portion and a funnel portion in the form of cutlet and the cullet is fused to obtain reclaimed glass. Particularly high-purity is required of lead glass which forms the panel portion of the cathode-ray tube. Therefore, such inclusion of impurities makes it difficult to reclaim lead glass for forming the panel portion.
In addition, in the background-art explosion-proof structure, in the case where there arises an error in bonding such as a displacement of the metal band, the fused solid substances of the explosion-proof tape remain on the cathode-ray tube even if the metal band is cut and removed. As a result, not only is it difficult to remove the fused solid substances, but also it is apt to damage the cathode-ray tube. If the cathode-ray tube is damaged when the remainders of the explosion-proof tape are removed, there arises a fear that the cathode-ray tube implodes due to stress concentration. Thus, the cathode-ray tube should not be put into practical use.
SUMMARY OF THE INVENTION
It is an object of the present invention to develop an explosion-proof tape and an explosion-proof structure for a cathode-ray tube, in which the explosion-proof tape applied onto the outer circumference of a panel portion of the cathode-ray tube as explosion-proof treatment, and a metal band shrink-fitted on the explosion-proof tape can be removed easily and safely so that the breaking-up and recycling of the cathode-ray tube or the reclamation of the cathode-ray tube unsuccessful in the explosion-proof treatment can be performed efficiently.
According to the present invention, there is provided an explosion-proof tape wound on an outer circumference of a panel portion of a cathode-ray tube so that a metal band is shrink-fitted on the tape, the tape comprising: a support having at least a layer composed of propylene polymer with a propylene content of not less than 40 weight % or styrene polymer with a styrene content of not less than 50 weight %; and an adhesive layer formed on one surface of the support in a manner so that a plurality of fibers with a softening point of not lower than 200° C. are buried in the adhesive layer in a lengthwise direction of the tape. There is further provided an explosion-proof structure of a cathode-ray tube, wherein a metal band is shrink-fitted on an outer circumference of a panel portion of a cathode-ray tube, through a layer which is formed by winding such an explosion-proof tape as mentioned above, through its adhesive layer.
According to the present invention, the shrink-fitted metal band is heated and expanded in the same manner as when the metal band was shrink-fitted, so that the metal band can be removed easily and efficiently even by hand, and the explosion-proof tape remaining on the cathode-ray tube can be also peeled off and removed together with the adhesive layer through the support thereof easily and efficiently even by hand. As a result, the metal band and the explosion-proof tape applied onto the cathode-ray tube as explosion-proof treatment are removed easily by hand or the like so that the cathode-ray tube can be broken up into a panel portion and a funnel portion. The broken-up portions are subjected to fusing treatment so that glass material kept as high in purity as that before the treatment can be reclaimed. The reclaimed glass material can be served for recycling efficiently as glass material with quality equal to that before the reclamation.
In addition, even if there arises an error in manufacture such as an error in bonding, for example, a divergence of the metal band at the time of the explosion-proof treatment, the metal band and the explosion-proof tape can be removed from the cathode-ray tube more easily and without damaging the cathode-ray tube. Thus, the cathode-ray tube can be salvaged and reused efficiently without being broken up.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
REFERENCES:
patent: 3873638 (1975-03-01), Olson
patent: 3912105 (1975-10-01), Eisses et al.
patent: 1 426 767 (1976-03-01), None
patent: 411297237 (1999-10-01), None
Patent Abstracts of Japan, vol. 018, No. 434, Japanese Publication 06-139962, May 20, 1994.
Patent Abstracts of Japan, vol. 014, No. 028, Japanese Publication 01-265432, Oct. 23, 1989.
Goto Yoichiro
Nagata Toshio
Nakamura Koichi
Tamaki Kazukuni
Yamamoto Hiroshi
Clove Thelma Sheree
Nitto Denko Corporation
Patel Vip
Whitham Curtis & Christofferson, P.C.
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