US 3413405 A
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Description (OCR text may contain errors)
Nov. 26, 1968` J. A. MYERS 3,413,405
ELECTRICAL SHIELDING TAPE Filed OCT.. lO, 1966 www" ll I:'=V
mvENToR JAMES A. MYERS wuuw ATTORNEY United States Patent O 3,413,405 ELECTRICAL SHIELDING TAPE James Albert Myers, Toledo, Ohio, assignor to Staulfer Chemical Company, New York, N.Y., a corporation of Delaware Filed Oct. 10, 1966, Ser. No. 585,436 6 Claims. (Cl. 174-36) ABSTRACT OF THE DISCLOSURE A tape product is provided which is particularly adapted for electrical shielding. In use, the tape prevents intermixing of signals in adjacent circuits. The tape structure is distinguished in that the conductor is in the form of a ribbon having two exposed areas extending the length of the tape and located one at either side of the tape and of the center line thereof making electrical contact when the tape is Wrapped, with overlapping, about an electric cable or the like.
This invention relates to an electrical shielding tape adapted for various applications.
In electrical and electronic communication and instrumentation it is manifestly important that signals in adjacent circuits do not become intermixed and that they be protected from the influence of outside magnetic fields. This is commonly accomplished by surrounding the insulated conductor with a wire mesh sleeving formed of a metal capable of conducting an electric current. Such means translates the magnetic field created about the conductor into an electric current which it conveys harmlessly to ground.
Heretofore the wire mesh sleeving has either been slippcd over the insulated conductor, simply wrapped therearound, or formed directly thereon by a braiding operation. In any case, the sleeving itself must be insulated either before or after it is applied to the conductor.
The present invention aims to provide a pre-formed tape which may be applied for the above indicated purposes and which greatly simplifies the shielding whether effected by the fabricator or in the field.
Other objects of the invention will be apparent from the following description which will proceed with reference to the accompanying drawings in which FIGURE l is a fragmentary, isometric sectional view illustrating a tape conforming to the invention;
FIGURES 2-4 are sections illustrating modified forms; and
FIGURE 5 is a view similar to FIGURE 1 but showing a further modification.
Referring rst to FIGURE 1, the numeral denotes the body of 'insulating material, preferably a plastic or elastomeric substance. Of the many available materials, silicone rubber has been found most advantageous, particularly silicone rubber which has been formulated to be self-adhering. In the event an insulating material is employed which does not possess this property, it is necessary according to the invention to apply a suitable adhesive to the tape before application of the same.
The insulation 10 has embedded therein (FIG. 1) a ribbon 12 formed of a conducting material. Such ribbon is continuous with the body of insulating material and is transversely distorted over its length to provide exposed areas 14 and 16 located one at either side of the center line of the tape. In the particular embodiment, the conductor 12, which includes a straight portion 18 mediate the portions 14 and 16, terminates in anchoring flanges 20, 22 extending downwardly and upwardly, respectively, into the body of the insulating material.
Portions or areas 14 and 16 are located at the opposite sides or faces of the tape so that on over-lapping Wrapping of the tape about the electric cable or the like required to be shielded the two areas make contact to provide continuity of electrical conductivity over the length of the wrapped tape which is connected to the common ground or return circuit of the system.
Going now to FIGURE 2, it will be observed that in such modification the conductor 12a embedded in the insulating material 10a is not distorted as the conductor 12. Rather, the areas 14a and 16a are exposed by channeling of the insulating material. The latter will be seen as having deposited thereon a raised guide line 24 located along the center line of the tape and serving to facilitate wrapping of the tape with the degree of over-lap necessary to assure electrical contact between the areas 14a and 16a.
It is to be recognized that in the interest of simplifying an understanding of the invention, FIGURE 2, as well as the other figures, are not drawn to true scale, which is to say that the thickness of the section is substantially enlarged. In the commercial embodiment, assuming the same were cut to afford a similar sectional view, the layers of plastic above and below the conductor would appear relatively quite thin. Thus, the mere wrapping of f the tape about an insulated lead as contemplated by the invention would insure sufficient flow of insulation in the areas of the channels to make certain positive electrical contact between the portions 14a and 16a of the conductor 12a.
The embodiment of FIGURE 3 again involves a conductor ribbon 12b which is not transversely distorted as the conductor 12. Here, the insulating material 10b is applied in two separate strips each of which has a width less than that of the conductor 12b. In this manner, the exposed areas 14b and 16b are provided. It is to be observed that each insulating strip terminates in a flange portion 26, as necessary for insulation of the edges of the conductor.
The modification of FIGURE 4 contemplates an application demanding a thickness of insulation greater than normal. Here, there is deposited in the channels corresponding to those shown in FIGURE 2, strips 30 of conductive material compatible with the particular insulation 10c. These strips are in contact with the areas 14C and 16C of the conductor 12e In FIGURE 5 there is shown a tape having feathered edges 32 and a guide line 34 which is flush with the adjacent surface of insulating material 12d. The conductor 12d corresponds with the conductor 12 in FIGURE l. Thus, it comprises anchoring flanges 20d and 22d serving just as the corresponding anges in FIGURE 1. The feathering of the edges of the tape and the guide line 34 facilitates wrapping of the tape with the over-lapping necessary to insure the required positive electrical contact between the areas 14d and 16d.
It is to be emphasized that the overall dimensions of the tape and the choice of insulating and conducting materials are determined by the mechanical, electrical, and environmental factors involved in the particular application. The use of self-bonding or self-adhering silicone rubber, hereinbefore stated as the preferred insulation, is most especially recommended where low frequencies and somewhat elevated temperatures must be dealt with. In such an application the conductor, with advantage, may be a flattened knitted sleeving formed of Monel metal.
Although reference has been made herein to overlapping wrapping of the tape, it should be evident that the tape may be laid longitudinally around electrical conductors or bundles of conductors. This, however, does not preclude definition of the tape in terms of its use as a helical or spiral wrap.
Shielding tapes conforming to the invention may be 3 manufactured by various methods. In a preferred procedure, the teachings of Skobel Patent 3,253,073 and U.S. application Ser. No. 536,161 filed March 21, 1966, in the name of Sylvester Meitinger are followed.
The invention claimed is:
1. An electrical shielding tape comprising a continuous ribbon of conductive material and an insulating substance, said ribbon having two areas extending the length of the tape and located one at either side of the ribbon and of the center line of the tape adapted to make electrical contact when the tape is wrapped, with over-lapping, about an electric cable or the like.
2. An electrical shielding tape comprising a plastic body portion having a continuous ribbon of conductive material embedded therein, said ribbon having two exposed portions of extending the length of the tape and located one at either side 'of the ribbon and of the center line of the tape to the end that on wrapping of the latter about an electric cable or the like such portions by overlapping of the tape are caused to make contact to provide continuity of electrical conductivity over the length of the Wrapped tape.
3. A tape according to claim 2 where the two said exposed portions are provided by transverse distortion of the ribbon over its length. v
4. A tape conforming with claim 2 where the plastic is silicone rubber.
5. A tape conforming to claim 4 where the silicone rubber is formulated to be self-adhering.
6. A tape conforming to claim 3 Where the plastic is silicone rubber formulated to be self-adhering.
References Cited UNITED STATES PATENTS 2,454,567 11/ 1948 Pierson 174-35 2,477,267 7/ 1949 Robinson 174-35 2,882,183 4/ 1959 Bond et al 174-110 3,051,771 8/1962 Lee 174-36 3,230,121 1/1966 Nitzsche et al 174-110 3,253,073 5/1966 Skobel 156-244 X LEWIS H. MYERS, Primary Examiner.
A. T. GRIMLEY, Assistant Examiner.