US453466A - Half to william f - Google Patents

Description

(No Model.)

B. A. DARLING. CIRCUIT CLOSER FOR BURGLAB ALARMS.

No. 453,466. Patented June 2, 1891.

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W Lt71/6656S, I 71,7/(7' 71/1 57" Edwin uiflarziny' ZQ J UNITED STATES PATENT OFFICE.

ED\VIN A. DARLING, OF HOPEDALE, MASSACHUSETTS, ASSIGNOR OF ONE- HALF TO WILLIAM F. DRAPER, OF SAME PLACE.

CIRCUIT-CLOSER FOR BURGLAR-ALARMS.

SPECIFICATION forming part of Letters Patent No. 453,466, dated June 2, 1891.

Application filed January 10, 1888. Serial No. 260,349. No model.)

To all whom it may concern.-

Be it known that I, EDWIN A. DARLING, of Hopedale, county of 'Worcester, Stateof Massachusetts,have invented an Improvement in Circuit-Closers for Burglar-Alarms, of which the following description, in connection with the accompanying drawings, is a specifica-,

tion, like letters on the drawings representing like parts.

The object of my invention is to produce a circuit-closer for burglar-alarms or similar apparatus adapted to be operated by the pressure of the foot when stepped upon and of such construction as not to be observed by the person operating it.

Circuit-closers to be operated by the pressure of the foot have been previously made which were concealed in mats to be placed near the doors or windows, so as to be operated bya person entering the room; but such circuit-closers, so far as known to me, have occupied a considerable space and have sufficient movement in operating to be readily recognized by persons familiar with such apparatus and are likely to be avoided by experienced burglars, who know of the existence of circuit-closers in mats, and are thus careful to avoid stepping on a mat or rug when entering a house.

The present invention consists of a circuitcloser composed of a'pair of very thin strips of elastic metal, watch spring steel being preferred, said strips being mechanically connected together, but electrically insulated from one another by thin pads or washers of insulating material, set at short distances from one another-say an inch or so=along the metal strips, which may be of any desired length, and is inclosed in a tubular covering, which protects it and prevents accidental displacement of the springs. The entire circuitcloser thus constructed may be less than from one thirty-second to one fiftieth of an inch thick, and when placed under an ordinary carpet will produce no ridge that would make its presence known, and will produce no appreciable wear on the carpet. The elasticity of the springs is sufficient to support the weight of the carpet without permitting the springs to come in contact, but when pressed upon by a heavy weight, as when a person treads on the carpet just above one of these circuit-closers, the springs will yield and come in contact with one another at some point between the insulating-pads, and will thus close an electric circuit, of which the two springs constitute the terminals, and which may contain any suitable alarm apparatus.

Figure 1 is a side elevation of a circuitcloser for burglar alarms embodying this invention, and Fig. 2 a plan view thereof.

The said circuit-closer consists of two strips a l) of thin elastic conducting materialsteel, such as commonly used for watch-springs, being well adapted for this purpose. The said strips are supported one above the other and separated from one another a short distance, sufficient to insulate them, by pads c of insulating material, which may be small pieces of paper cemented to the springs or otherwise fastened at proper distances apart, the said pads being preferably spaced at about three-fourths of an inch from one another. The conductors d e of an electric circuit may be soldered to said strips, respectively, which will thus form the terminals of the said circuit, and each of said conductors d 6 may have branches connected, respectively, with the springs a, and b, and any desired number of the said circuit-closers may be placed beneath the carpet at any desired part of the room, preferably near the doors and windows, so that a person cannot enter or leave the room without stepping on some one of said circuit-closers and thus pressing the upper spring a into contact with the lower spring I) at some point between the insulatingpads c, and thus closing the circuit. The circuit'closing springs are inclosed in tubular coverings, which may be a fabric Woven or braided thereon, as shown at f, Fig. 2, or may be a thin rubber tube drawn over the springsto prevent them from accidental displacement, and to prevent dust from entering between them so as to impair the electrical contact when they are pressed together.

The entire circuit-closer as made in actual practice is not over from one thirty-second to one fiftieth of an inch thick, and when placed under an ordinary carpet gives no indication of its position, so that a person aware that such circuit-closers are used would not be able to avoid stepping upon and operating them,

tic strips of conducting material and a number of thin pads of insulating material interposed between said conducting-strips at short distances from one another along the said conductors, and a tubular covering inclosing the said springs, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

EDWIN A. DARLING.

\Vitnesses:

F. J. DU'rcHER, v ARTHUR H. BALL.

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