Normally closed pressure switch

United States Patent

[“) 3,553,404

<td> [72]</td><td> Inventor</td><td> Robert H. Koenig Cambria Heights, N.Y.</td>

<td> [21]</td><td> Appl. No.</td><td> 762,057</td>

<td> [22]</td><td> Filed</td><td> Sept. 24,1968</td>

<td> [45]</td><td> Patented</td><td> Jan. 5,1971</td>

<td> [73]</td><td> Assignee</td><td> Tapeswitch Corporation of America</td>

<td></td><td></td><td> Farmingdale, N.Y.</td>

[ 54 ] NORMALLY CLOSED PRESSURE SWITCH

Claims, 4 Drawing Figs.

[52] U.S.CI........................................................ 200/85,

200/86

[51] Int.Cl......................................................... H01113/14

[50] Field of Search............................................ 200/85,86,

61.43,67D2,153.14; 340/272

[56] References Cited

UNITED STATES PATENTS

2,896,042 7/1959 Koenig......................... 200/86

FOREIGN PATENTS 1,352,256 1/1964 France......................... 200/67D(UX)

Primary Examiner—David Smith, Jr.

Attorney—James P. Malone

ABSTRACT: A normally closed pressure switch having a pair of curved contact members which are backed up by parallel stiffener plates. A pair of insulating strips are mounted between the outer edges of the contact members. When pressure is applied normal to the planes of the stiffener plates, the contact members are straightened and held separated by the insulating strips.

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PATENTED JAN 51971

3,553,404

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INVENTOR.

ROBERT H,KOENIG

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3,553,404

NORMALLY CLOSED PRESSURE SWITCH

This invention relates to normally closed pressure switches.

Conventional pressure or force actuated switches, for instance tape type switches, are normally open and separated by insulating strips along the edges of the conductive members until the contacts are closed by pressure.

In the present switch, the contact members are of spring material and curved and mounted to contact each other in normal relaxed position. However, when pressure is applied, the contact members are straightened by the stiffener plates and held separated by a pair of insulating strips mounted between the edges of the contact members.

An advantage of the present invention is that it can withstand heavy weights or forces without damage, due to the rugged construction of the relatively heavy stiffener plates. Therefore, there is little likelihood of the contact members being deformed so as to cause a short circuit.

The present switch may be used for detecting the opening of doors such as vehicle doors, or windows, or the moving of articles of furniture, or as foot or wheel operated switches for general detection purposes. The switch contacts may be connected to alarms, indicators or other utilization devices.

Accordingly, a principal object of the invention is to provide new and improved pressure switch means.

Another object of the invention is to provide new and improved normally closed pressure switch means.

Another object of the invention is to provide new and improved pressure or force actuated switch means which have rugged construction and which are adapted to withstand heavy weights and forces.

Another object of the invention is to provide new and improved pressure switch means which are adapted to withstand heavy weights and forces, including twisting forces, without permanently deforming so as to cause a short circuit.

Another object of the invention is to provide new and improved normally closed pressure switch means comprising a first curved contact member having a pair of edges, a first stiffener member resting on said edges of said first contact member, a second curved contact member having a pair of 40 edges, a second stiffener plate resting on the edges of said second contact member, means to mount said stiffener plates generally parallel to each other and movable toward each other, said first and second curved members being curved toward each other at their center portions and normally 45 touching each other at their center portions, a pair of insulated strips mounted between the edges of first and second contact members, whereby said contact members are normally touching along their center portions but are straightened by said stiffener plates and separated by said insulated strips when pressure is applied normal to the parallel planes of said stiffener members.

These and other objects of the invention will be apparent from the following specification and drawings, of which:

FIG. 1 is a cross-sectional view of an embodiment of the invention shown in normally closed position;

FIG. 2 is a cross-sectional view of an embodiment of the invention shown in open position caused by the application of force or pressure;

FIG. 3 is an end view of another embodiment of the invention in closed position; and

FIG. 4 is an end view of the embodiment of FIG. 3 in open position.

Referring to the drawings, the invention generally comprises a pair of curved conductive springlike contact members 1 and 2, sandwiched between a pair of stiffener plates 4 and 5 which are mounted generally parallel to each other so that the edges of the conductive members touch the stiffener plates, as illustrated in FIG. 1, and the curved portions of the conductive members touch each other in the central area of the conductive members, due to spring action of the contact members.

A pair of insulating members or strips 6 and 7 are mounted between the edges of the conductive members and are preferably connected to the edge surfaces of one of the conductive members.

The whole assembly is held by a flexible casing 3 which may be of extruded plastic or rubber, having good insulating properties. The casing holds the assembly together in normal closed position, as illustrated in FIG. 1. However, when a 5 force, indicated by the arrow 8, is applied, the casing is flexible enough to collapse and the stiffener plates straighten out the contact members so that the contact members are separated by the insulating strips along their edges.

The stiffener plates permit the force to be applied at any 10 spot over their surface, and due to the rigidity of the stiffener plates, the switch is adapted to withstand heavy forces without being permanently deformed or damaged.

The contact members 1 and 2 may be of spring tempered steel, coated with conductive contact material, and they are 15 formed into the curved shape illustrated in FIG. 1.

The insulating members 6 and 7 may be of polyester or any stable insulating material having good mechanical strength. The stiffener plates may be of steel or other rigid material.

In a typical embodiment, the switch is approximately ‘/a inch 20 x inch and may be as little as one-eighth inch thick. The relative width of each insulation member or strip is approximately one quarter the width of the contact member. The insulating strips may be, for instance, 0.015 inch thick, and the outer jacketing can be molded or extruded rubber or plastic 25 material which is sufficiently flexible to permit proper operation. The outer jacketing should be waterproof and sealed against moisture. The switch is not limited to the typical dimensions disclosed. For instance, the switch may be elongated to several inches or longer with all of the members hav30 ing an elongated strip form. Conductive leads 9 and 10 are preferably connected to the ends of the conductive members 1 and 2 for connection to alarms, indicators or other utilization devices.

FIGS. 3 and 4 show a modification of the invention wherein 35 the contact members 10 and 11 are normally curved and contact at their edges and are separated by a large insulating member 12.

When a force is applied, as shown by the arrow 13, then the contact strips will straighten out, as shown in FIG. 4, and break the contact. In this embodiment, the stiffener plates could be eliminated. This embodiment could also be made with one of the contact strips remaining flat at all times. This modification would also be enclosed in a waterproof jacket, as discussed in connection with FIGS. 1 and 2.

Many modifications may be made by those who desire to practice the invention without departing from the scope thereof which is defined by the following claims: