US3124773A - crowley - Google Patents

Description

March 10 1964 .1. E. CROWLEY ELECTRIC CONTROL APPARATUS Filed July 28, 1961 INVENTOR. JOHN E. CRO LEY W ATTORNEY United States Patent 3,124,773 ELECTRIC CGNTROL APPARATUS John E. Crowley, St. Anthony Viiiage, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Filed July 28, 1961, Ser. No. 127,701 Claims. (Cl. 338-15ti) This invention relates to the field of electrical instruments and more particularly to resistance elements for use in such instruments. A filar resistance member is incorporated in the edge of a very thin tape bearing meaningful indicia so that the resistance of the member from some measuring point is always coordinated with the associated indicium. While such a concept is not new, there has been heretofore no teaching of any practical way of accomplishing the desired result, that is, of physically securing a resistance member to the edge of a thin flexible tape so that it remains fastened thereto during the normal flexing of the tape in use, and so that continuous, reliable contact with the resistance member along its entire length can readily be assured.

An object of the invention is to develop a process for constructing an instrument component comprising a flexible graduated indicator tape with a resistance member incorporated into one or both edges thereof for continuous engagement by an external electrical contact. Another object of the invention is to provide a practical instrument component as described above and a further object of the invention is to provide a new and improved laminated fabric for use in such electrical components.

Various other objects, advantages, and features of novelty not individually enumerated above which characterize my invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the subjoined drawing, which forms a further part hereof, and to the accompanying descriptive matter, in which I have illustrated and described a preferred embodiment of my invention.

In the drawing, FIGURE 1 is a transverse cross sectional view of a completed tape resistor according to the invention, FIGURE 2 is a cross sectional view of a step in the manufacture of the element, FIGURE 3 is a fragmentary side elevation of FIGURE 2, a portion being broken away for clarity of illustration, FIGURE 4 is an enlarged view of a portion of FIGURE 2, and FIGURE 5 is a view on a smaller scale of the apparatus of FIG- URES 2 and 3.

FIGURE 1 shows a laminated fabric including outer layers and 11 of Fiberglas and an intermediate layer 12 of nylon, with filar resistance members 13 and 14 partially embedded in the edges of the fabric for edgewise engagement by suitable external electrical contact means not shown. One or both of the outer surfaces of layers 10 and 11 may bear suitable indicia, spaced linearly or nonlinearly, and the resistances of members 13 and 14 are linear or nonlinear accordingly.

Each resistance element is constructed of a flexible core wire 15 on which is formed a helical winding 16 of resistance wire, insulated from the core and between the adjacent turns thereof, as shown in FIGURE 4. In one embodiment of the invention the core was 35 gage Formvar insulated copper wire, and the resistance wire was .001 inch in diameter under enamel insulation, and was of the alloy known as Oro G: obviously other suitable materials and dimensions may be used according to the needs of the user.

The resistance element shown in FIGURE 1 is not easily constructed, and much effort was expended before a satisfactory method of making these units was invented.

In practicing this invention, a metallic disk 20 to act as a holding fixture is first turned to provide a peripheral groove 21 somewhat deeper and wider than the thickness and width of the tape and peripherally longer than the desired length of the tape. There is also provided a pair of laminated fabric members 22 and 23 comprising respectively Fiberglas layers 24 and 25 and nylon layers 26 and 27. A Teflon cushioning strip 30 and a metal clamping'ring 31 are also used.

In making a resistance element, a tape 23 is placed in groove 21 with its Fiberglas surface against disk 20. An adhesive such as Cycleweld is applied along one or both edges of the tape as at 32, and the resistance member 13 is positioned next to the edge of groove 21. This is followed by another application of adhesive 33 and tape 22 is next applied with its nylon surface against the nylon surface of tape 23. Teflon strip 3th is next applied and the whole assembly is fastened together by clamping ring 31. Members 30 and 31 are slightly narrower than groove 21 so that upon tightening ring 31, resistance members 13 and 14 are forced outwardly into engagements with the walls of groove 21.

The entire assembly is now heated to the point where the two abutting nylon layers fuse into a single homogeneous layer in which the resistance elements are embedded except along the lines where they contact the walls of groove 21. After a suitable curing interval, the clamping ring and cushioning strip are removed and the finished tape is taken from the disk and sugar-blasted along its edges to remove enamel and foreign matter so that good electrical contact may be made with the winding at any point along its length. The desired indicia may now be printed on the tape surface and the element is ready for use.

In some cases it may be desirable to supply each of members 22 and 23 with nylon strips on both sides of the Fiberglas, to act as an improved base for certain printing inks, and also to facilitate splicing of the completed device, if such is contemplated. Groove 21 may then be lined with Teflon to prevent adhesion of the nylon to the disk.

Numerous objects and advantages of my invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and I may make changes in detail, especially in matters of shape, size, and arrangement of parts, within the principle of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

I claim as my invention:

1. In combination, a pair of coextensive elongated flexible members, each comprising at least a layer of Fiberglas and a layer of nylon, arranged with their nylon layers in contact, except along an edge thereof, to form a laminated fabric, an elongated filar resistance element partially between said members along said edge, and means adhesively joining said element to said members.

2. The method of making a tape resistor from an elongated flexible resistance element and a pair of laminated flexible tapes each comprising a surface layer of nylon, which comprises the steps of laying one of said tapes, nylon side out, in a groove, of substantially the same width as the tape, in a heat transfer member, applying adhesive along an edge of the tape, applying the resistance element to the edge of the tape in contact with the adhesive so that it projects appreciably beyond said edge, applying the other of said tapes nylon side down to the first tape, applying pressure forcing the two tapes into intimate contact, and heating the assembly to the point where the two nylon layers amalgamate into a single mass.

3. The method of making a tape resistor, from a coiled, helicoid, flexible resistance element and a pair of laminated flexible tapes each comprising a surface layer of nylon, which comprises the steps of laying one of said tapes, nylon side out, in a groove, of substantially the same Width as the tape in a heat transfer member, applying adhesive along an edge of the tape, applying the V resistance element to the edge of the tape in contact with the adhesive so that it projects appreciably beyond said edge, applying the other of said tapes nylon side down to the first tape, applying pressure forcing the two tapes into intimate contact and heating the assembly to the point Where the two nylon layers amalgamate into a single mass.

- 4. A resistor comprising a lamina of a thermoplastic material such as nylon, an elongated resistance element substantially embedded in said lamina along an edge there of so that a relatively small radial portion of said element extends beyond said lamina, and further laminae of Fiberglas overlying the first named lamina.

5. A resistor comprising a lamina of a thermoplastic material such as nylon, a coiled, helicoid resistance element substantially embedded in said lamina along an edge thereof so that a relatively small radial portion of said element extends beyond said lamina, and further laminae of Fiberglas overlying'the first named lamina.

References Cited in the file of this patent UNITED STATES PATENTS 2,255,376 Bull et al. Sept. 9, 1941 2,427,979 Sorensen Sept. 23, 1947 2,617,011 MacKendrick Nov. 4, 1952 2,719,907 Combs Oct. 4, 1955 2,860,215 Williams Nov. 11, 1958'

Claims (1)

1. IN COMBINATION, A PAIR OF COEXTENSIVE ELONGATED FLEXIBLE MEMBERS, EACH COMPRISING AT LEAST A LAYER OF FIBERGLAS AND A LAYER OF NYLON, ARRANGED WITH THEIR NYLON LAYERS IN CONTACT, EXCEPT ALONG AN EDGE THEREOF, TO FORM A LAMINATED FABRIC, AN ELONGATED FILAR RESISTANCE ELEMENT PARTIALLY BETWEEN SAID MEMBERS ALONG SAID EDGE, AND MEANS ADHESIVELY JOINING SAID ELEMENT TO SAID MEMBERS.

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