US2790872A

US2790872A - Deformation switch assembly

Info

Publication number: US2790872A
Application number: US395683A
Authority: US
Inventors: Robert G Helsper
Original assignee: Specialties Development Corp
Current assignee: Specialties Development Corp
Priority date: 1953-12-02
Filing date: 1953-12-02
Publication date: 1957-04-30
Anticipated expiration: 1974-04-30

Description

April 1957 R. cs. HELSPER 2,790,872

DEFORMATION SWITCH ASSEMBLY Filed Dec 2 53 INVENTQR Hold-l ATTd EY United States Patent DEFORMATION SWITCH ASSEMBLY Robert G. Helsper, South Orange, N. J., assignor to Specialties Development Corporation, Belleville, N. J., a corporation of New Jersey Application December 2, 1953, Serial No. 395,683

7 Claims. (Cl. 200-86) The present invention relates to electrical circuit makers, and, more particularly, to a deformable switch assembly which is operable by being compressed at any point along its length.

Specifically, the present invention aims to improve the switch assembly disclosed in copending application for United States Letters Patent, Serial No. 353,781, filed May 8, 1953, assigned to my assignee, issued on even date herewith.

The switch assembly disclosed in the aforementioned application generally comprises first, second and third elongate, superimposed, flexible, electrically conductive strips; a series of lengthwise spaced pad-like insulating elements extending diagonally between the first and second strips to hold these strips out of contact with each other; a second series of similar elements between the second and third strips, the elements of the first and second series being staggered with respect to each other; and a tubular, deformable, nonconductive housing for the strips.

This assembly is made by adhesively securing the padlike elements to one or more of the strips in their proper position and then inserting the strips in the housing. It will be appreciated that this mode of arranging the pad-like elements, it performed by hand, is tedious, cumbersome and expensive due to the labor cost involved, and, if performed by automatic machinery, requires fairly complicated and costly equipment.

Accordingly, an object of the present invention is to provide a switch assembly, having all the beneficial structural features of the aforementioned switch assembly, which is constructed and arranged in a practical and highly economical manner.

Another object is to provide such a switch assembly which comprises a minimum number of simple and relatively inexpensive parts.

A further object is to provide such a switch assembly, the deformable characteristic of which can be varied without changing the dimensions of the parts thereof.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention, the foregoing objects are accomplished by providing a switch assembly which comprises first and second elongate, superimposed, flexible, electrically conductive strips; a third strip of the foregoing description having thereon a spiral winding of a nonconductive ribbon formed with spaced apart convolutions and being sandwiched between the first and second strips; and a tubular, deformable nonconductive housing for the strips.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

2,790,872 Patented Apr. 30, 1957 Fig. 1 is a fragmentary side elevational view, partly in section, illustrating a switch assembly, in accordance with the invention, connected in an alarm circuit.

Fig. 2 is a fragmentary perspective view of the strips and the ribbon winding on the middle strip apart from the housing.

Fig. 3 is an enlarged sectional view taken along the line 3-3 on Fig. 1.

Referring to drawing in detail, there is shown a switch assembly generally comprising three superimposed metallic strips 10, 11 and 12, a spiral winding of a nonconductive ribbon 14 about the middle strip 11 which is sandwiched between the strips 10 and 12, and a tubular deformable nonconductive housing 15 for the strips.

The strips 10, 11 and 12 may be of equal width or the middle strip 11 may be of a lesser width, as shown, so that, when the ribbon Winding 14 is applied thereon, the effective width thereof is about equal to or slightly greater than the width of the strips 10 and 12. The strips are formed of a highly conductive, springy material such as Phosphor bronze and are of a desirable width and thickness. For example, the strips 10 and 12 may have a width of about five-sixteenths of an inch and the strip 11 may have a width of about one-quarter of an inch, and all of the strips have a thickness of about ten thousandths of an inch.

The ribbon, tape or band 14 may be fiat or oval, and may be formed of rubber or rubber-like or other yieldable material having insulating properties. For example, an excellent material for this purpose is silicone rubber because it has these desired properties and can be readily handled and wound or twisted about the strip 11 either by hand or simple automatic machinery. The width and thickness of the ribbon may vary, but, for example, the width may be about one-fourth of an inch and the thickness thereof may be about one-sixteenth of an inch.

As shown herein, the ribbon is spirally wound on the strip 11 in zig-zag fashion with adjacent convolutions at the same fiat side surface of the strip spaced apart a distance slightly greater than the width of the ribbon. For example, the convolutions of the ribbon extend diagonally across the side surfaces at an angle of about 45 with respect to the longitudinal axis of the strips, whereby, if the strip 11 is about twice as wide as the ribbon, the space between convolutions will be about twice the width of the ribbon. The angle at which the convolutions extend across the strip may be varied to vary the space between adjacent convolutions, and thereby vary the degree of force required to bring adjacent strips into contact. This is a very desirable feature because the characteristics of the strip assembly can be altered as desired while still using the same materials in the manufacture of the switch assembly and without changing the dimensions of the materials.

As shown in Fig. 3, the housing comprises a flat base strip 16, and a cover strip 17 having a channel section 18 for receiving the strip assembly and having side flanges 19 secured upon the base strip 16. The channel section may be dimensioned to snugly receive the strip assembly including the strips 10 and 12 and the middle strip 11 with the winding 14 thereon, but having a width slightly greater than the strips 10 and 12 to provide a loose fit at the side edges of these strips, whereby these strips are free to move towards the strip 11 when pressure is applied thereon.

The housing strips 16 and 17 are formed of rubber or rubber-like insulating material which is readily deformed, provides a watertight seal, and is weather resistant at temperatures between about 65 F. and about F.

The switch assembly is adapted to be used in an alarm circuit, including a source of energy 20 and alarm means herein shown as a bell 21. In this circuit, the strips greases 10 and 12 are electrically connected to each other at one 01' both ends thereof and to one terminal of the bell, the strip 11 is connected to one side of the source, and the other terminal of the bell is connected to the other side of the'source, so that, upon establishing contact between the strip 11 and the strip 10 and/or the strip 12, the circuit is closed and an alarm is given.

From the foregoing description, it will be seen that the present invention provides a practical and reliable switch assembly which is extremely economical to manufacture and assemble.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

I claim:

1. A deformation switch assembly comprising first and second superimposed, flexible, electrically conductive, thin, metallic, flat strips of relatively narrow width and of indefinite, continuous length; a third strip of the fore going description having thereon a spiral winding of a resilient, electrically nonconductive ribbon formed with spaced apart convolutions and being sandwiched between said first and second strips such that said first and third, and said second and third strips are normally held out of contact with each other by the convolutions of said ribbon; and an enclosed tubular, deformable, electrically nonconductive housing of indefinite, continuous length for confining the side edges of said strips and said spiral winding, said housing comprising a channel member and a flat base member sealed to said channel member to provide weather-tight protection for said strips.

2. A switch assembly according to claim 1, wherein said strips are wider than said ribbon.

3. A switch assembly according to claim 1, wherein said convolutions extend diagonally across the flat sides of said strip.

4. A switch assembly according to claim 2, wherein said convolutions are disposed at an angle of about 4-5 with respect to the longitudinal axis of said third strip.

5. A switch assembly according to claim 1, wherein the distance between adjacent convolutions along the longitudinal axis of said third strip is greater than the width of said ribbon.

6. A switch assembly according to claim 1, wherein said ribbon is formed of silicone rubber.

7. A switch assembly according to claim 1, wherein the width of said third strip is less than that of said first and second strips by about twice the thickness of said ribbon.

References Cited in the file of this patent UNITED STATES PATENTS 2,132,685 Hampton et al -2 Oct. ll, 1938 2,163,960 Paver June 27, 1939 2,611,049 Roby .a Sept. 16, 1952 FOREIGN PATENTS 272,893 Great Britain a- Aug. 30, 1928