US2345771A - Alarm system - Google Patents

Description

Search WWW INVENTOR TTORNEY 2 Sheets-Sheet 1 Richard WRe /noId-s' o 3 g 2 z R. W. REYNOLDS ALARM SYSTEM Fi1d Oct. 21, 1941 1H HEU RI A'p ril 4,1944.

R. W. REYNOLDS ALARM SYSTEM Filed Oct. 21. 1941 2 Sheets-Sheet 2 eynaldfl INVENTOR ATTORNEY Patented Apr. 4, 1944 illicit-till! (will UNITED STATES PATENT OFFICE ALARM SYSTEM Richard W. Reynolds, Wilmington, DcL, assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application October 21, 1941, Serial No. 415,940

Claims. (Cl. 177-314) it is possible for guards to visually observe, even at considerable distances, any efforts to pass through or over the fences protecting important areas. At night when adequate lighting is not available, and in localities Where dense fogs are of frequent occurrence, equal protection is difficult of attainment. It may not be possible to secure additional guards promptly after a heavy fog has descended, or when there has been a break-down in the lighting system.

The heretofore proposed signaling systems, for example, the location of microphones at short intervals around the enclosure, etc., are so e5;- pensive that their installation where their use is infrequent is of questionable wisdom from an economic standpoint, and they have in addition the disadvantage that they, like the fences, wall, or the like which they are designed to protect, are subject to tampering at the place where entry into the prohibited area is sought. Furthermore, none of these arrangements protect both against tampering or other contact with the fence, and tunneling under or bridging over the same.

The primary object of this invention was to design an alarm system which could be installed easily and economically, and which would detect any unusual activity, for the protection against intruders, trespassers, tamperers, etc., at or near the fence or other enclosing means. Another object was to devise a system and apparatus for detecting the touching, striking, pulling, kicking, climbing, twisting, bending or cutting of the protective enclosure, as well as walking, shoveling, digging, jumping, crawling, etc., adjacent the said structure. A further object was to devise a Signaling system for buildings, wire enclosures, etc., which would utilize equipment conventional in other fields with little or no alteration or modification. Still further objects were to design an alarm system for a fence in which the fence itself is utilized for transmitting vibration signals over considerable distances to an observing or pick-up point, and to utilize an audio amplifier in combination with indicating or recording electrical instruments to facilitate the observation and interpretation of mechanical vibrations transmitted by wire enclosures.

A general advance in the art, and other objects which'will appear hereinafter, are also contemplated.

It has now been found that wire fences and related structures conduct the vibrations produced therein with such distinctness that, with the pick-up arrangement of .the present invention, such delicate disturbances as weeds being blown against the fence by a strong wind can be detected at distances approximating one-half mile.

The said pick-up arrangement comprises a conventional phonograph crystal or dynamic needle pick-up capable of converting the mechanical vibration of the fence into a suitable electrical impulse, mounted on an element of the fence near, and connected to an amplifier and loud speaker hook-up at, a guard tower.

How the foregoing objects and related ends are accomplished will be apparent from the following exposition, in which are disclosed the principle and divers embodiments of the invention, includ ing the best mode contemplated for carrying out the same. The written description is amplified by the accompanying drawings, in which:

Figure l is a fragmentary perspective view of a woven Wire fence section with the arm and needle pick-up of the present invention located thereon;

Figure 2 is an elevation view partly in section of a portion of a guard house and adjacent portion of a wire fence with the alarm system of the present invention installed thereupon;

Figure 3 is an enlarged elevation View, partly in section, of the arm and needle pick-up of the present invention mounted on the top rail of a fence of the type shown in Figure 1;

Figure 4 is a fragmentary elevation view with parts broken away, showing a modified mode of mounting the arm and needle pick-up;

Figure 5 is another fragmentary elevation view with parts broken away, showing another modified Way of mounting the arm and needle pick-up;

Figure 6 is a fragmentary elevation view with parts broken away, showing a method of mounting the arm-and needle pick-up on a modified form'of fence;

Figure 7 is a fragmentary end elevation view with parts broken away, showing the mounting of an arm and needle pick-up on a fence line post;

Figure 8 is a fragmentary elevation view with parts broken away, showing a method of mounting the arm and needle pick-up on the mesh of a wire fence;

Figure 9 is a fragmentary side elevation view showing the mounting of the arm and needle pick-up on a special tie Wire joining the metal line posts of a fence;

Figure 10 is a figure similar to Figure 1 but showing two complete alarm systems, one mounted on each side of a complete separation in a fence system;

Figure 11 is a fragmentary perspective view showing a pick-up without a supporting arm, mounted on a fence element by means of a hook arrangement; and

Figure 12 is a fragmentary perspective View showing an arm and hook pick-up suspended on the wire of a fence.

Referring now to page 1 of the drawings, there is shown in Figure 3 at 30 the arm of a pick-up of the type employed in phonographs and the like. Since the pick-up arm arrangement is con ventional, it is believed to be unnecessary to burden this specification with details of its construction. Detailed descriptions are available in the prior art. The needle is shown at 3|, and the pivot at 32. Either the crystal or dynamic type of pick-up is suitable.

A bracket or strap 33, firmly secured about the top horizontal rail 50 of the fence, provides a suitable support for the pivot 32. The electrical impulses resulting from the vibration of 'the needle 3| are transmitted by the wires 34 to the cable 35, which carries them to the amplifying means.

A protective housing 36, secured to the fence top rail by means of angular brackets 31, is provided for the pick-up arm. This housing is ordinarily of such a character as to discourage tampering, and may have a heavy covering 38, of metal, plastic or the like, for waterproofing purposes.

In Figure l, a very satisfactory location for the pick-up arm along the fence, is shown. Here it is close to an extension arm 54, mounted on a line post 5|, upon which the cable is supported by means of straps, one of which is shown at 52. The line post is an excellent support for the cable, and the top rail provides a very firm base upon which to mount the arm pivot.

The barbed wire '53, secured to the extension arm 54 by means of a conventional tongue-andgroove arrangement, is provided to prevent persons from climbing over the fence 40.

In the preferred embodiment of the invention, the pick-up is mounted on one of the barbed wires 53, as shown in Figure 4.

In still another modification of the invention the pick-up is mounted on an extension arm 54, as shown in Figure 5.

If desired, a special cross-wire 55 may be stretched across a Y extension arm, and the pick-up mounted thereon, as shown in Figure 2.

In some instances it may be desirable to support the tone arm on a lin post, rather than on the fence itself. Such modifications are shown in Figures 6, 7, 8 and 9. In Figure 6, the arm is supported on the line post, and the needle pick-up rests on the fence top rail. In Figure 7, the same supporting means is used, but the needle pick-up rests on the line post itself. In Figure 8, the needle rests on the woven fence. In Figure 9, a special Wire 56, stretched along the fence and secured to the line posts, is provided for the needle support. This Wire is kept taut by means of a turn-buckle 51. A small disc-like piece 58, secured by welding or in an equivalent manner to the wire 56, keeps the needle in satisfactory contact therewith.

. in Figure 12.

In some installations, segregation to provide directional indication is desirable, and a suitable arrangement for accomplishing this purpose is illustrated in Figure 10. There a complete break is made in the fence by having the wire sections 40 terminate at line posts 5|, placed sufficiently close together to prevent access to the fenced off area. In this set-up a pick-up is located adjacent each line post, and the respective cables 35 lead to separate amplifying and loud speaking systems. These two loud speaker amplifier hook-ups may be located nearby, or in widely separated places, as is desired.

The most common arrangement is shown in Figure 2, where the cable 35 leads through the wall 60 of a guardhouse to an amplifier 10, the casing of which supports a loud speaker 80.

If desired, the needle, or stylus, in the ick-up may be replaced by hook 39, as illustrated in Figure 11. With this arrangement, a bracket to support the tone arm is not necessary. The arm and its hook may be hung from various parts of the enclosing means, such as the fence 40, the top rail, the top strands of barbed wire, or related parts.

With the hook arrangement, it is not necessary to use the tone arm support for the pick-up. The pick-up may be removed from this casing and suspended by the hook 39 to a fence element, for example, the barbed wire 53, as shown In such an instance it would be desirable to provide some sort of weatherproof casing for the pick-up. What this casing is, and how it is arranged, will obviously depend upon the environment encountered in the location where the pick-up is employed.

The principle of the present invention is believed obvious from the foregoing description of the structural features of the various embodiments. Briefly, the mechanical vibrations in the fence are changed to electrical waves by a vibration pick-up, and the electrical waves fed to an amplifier or loud speaker hook-up which changes them to audio sound, which informs the guard, or listener, of the tampering, its character, and its location. It would be possible to provide visual observation, or to make a record, of the disturbances through suitable indicating and recording instruments.

Amplifiers and loud speakers are well known in the art, and details of their construction and operation are not necessary to an adequate disclosure of the present invention. Preferably a high gain (for example, 115 db.) low power (for example, 5 watts) audio amplifier and magnetic type loud speaker is employed. Suitable amplifiers are disclosed in U. S. A. Patents Nos. 1,693,756, 1,780,567 and 2,051,153. A suitable loud speaker is illustrated in U. S. A. Patent No. 1,713,210.

The crystal type of pick-up is preferred where the amplifier is located nearby, since some simplification in the installation is obtainable. Where the amplifier is located at a distance greater than feet from the pick-up, the dynamic type of pick-up is more desirable. If the guard post is to be located more than 500 feet from the pick-up, a pre-amplifier may be employed. Ordinarily the pre-amplifier will be at least 200 feet from the main amplifier.

A good (tight) fence will transmit vibrations up to 3,000 feet from the point of incidence. The vibrations travel along the woven wire fence proper, the overhanging barbed wire, the continuous pipe frame (top rail) or separate transmission wires, depending upon the type of fence or enclosure to which the alarm system is being adapted. At any point within the range of transmitted mechanical vibrations the pick-up may be located on the fence, and the electrical impulses produced thereby transmitted by cable to a guard house, fence terminal, or any convenient place where indication is desired. Ordinarily the aforementioned cables are shielded, but if the distances are short they may be unshielded Without danger of extraneous pick-up.

The needle pick-up has been described as a matter of convenience and preference, but those skilled in the art will understand that the vibration type of pick-up can be employed.

The pick-up need not necessarily be of the crystal or dynamic types previously mentioned. In some instances the resistance (carbon) type operates quite satisfactorily. It is desirable that the pick-up have a weatherproof casing.

Where a separate transmission wire is employed (see Figure 9), it need not terminate along the fence. If desired it may be continued to an observation post some distance from the fence, and there contact the pick-up.

The amplifier characteristics should be matched to the type and number of pick-ups used, if the best results are to be obtained with the installation. Ordinarily a watt amplifier is satisfactory, but if the listening post is large or the listener remote from the loud speaker, a higher powered device may be needed. The amplifier and loud speaker combination must have power capable of enabling hearing under the conditions encountered. The amplifier gain needed obviously depends upon conditions obtaining, but in general it should be at least 100 db., and preferably slightly more. It will be appreciated that too high an amplifier gain may prove objectionable.

The type of sound produced, that is, the magnitude and frequency components, gives a direct indication of the character of the tampering with the fence, and in a very short time guards are able to interpret the various kinds of vibrations with such accuracy that they are aware of the location and nature of the operation being carried out on, or near, the fence. Visual indications and vibration records can be similarly interpreted.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. In an alarm system comprising a fencing barrier, a pick-up device, strain resistant means contacting a part of the barrier, said means being responsive to mechanical disturbances in the barrier and capable of transmitting to the pick-up device a mechanical vibratile disturbance set up in the barrier, means for mounting the pick-up device at a point distant from the seat of a disturbance, said pick-up device having a vibratile part contacting said strain resistant means and bbtiiiiii iitltl being mechanically responsive to vibratile disturbances set up in the strain resistant means, means responsive to said vibratile part to transform the vibrations into electrical impulses, and means at a point distant from the seat of disturbance responsive to said electrical impulses to amplify the same and operate a signal.

2. In an alarm system comprising a fencing barrier, a dynamic pick-up device, strain resistant means contacting a part of the barrier, said means being responsive to mechanical disturbances in the barrier and capable of transmitting to the pick-up device a mechanical vibratile disturbance set up in the barrier, means for mounting the pick-up device at a point distant from the seat of a disturbance, said pick-up device having a vibratile part contacting said strain resistant means and being mechanically responsive to vibratile disturbances set up in the strain resistant means, means responsive to said vibratile part to transform the vibrations into electrical impulses, and means responsive to said electrical impulses to amplify the same and operate a signal.

3. In an alarm system comprising a fencing barrier, a pick-up device, strain resistant means contacting a part of the barrier, said means being responsive to mechanical disturbances in the barrier and capable of transmitting to the pick-up device a mechanical vibratile disturbance set up in the barrier, means for mounting the pick-up device at a point distant from the seat of a disturbance, said pick-up device having a vibratile part contacting said strain resistant means, said part being responsive to vibratile disturbances set up in the strain resistant means, means responsive to said vibratile part to transform the vibrations into electrical impulses, and means responsive to said electrical impulses to amplify the same and operate a signal.

4. In an alarm system comprising a fencing barrier, strain resistant wire means contacting a part of the barrier, said means being responsive to mechanical vibrations set up in the barrier, means to stress said wire means, a pick-up device having a vibratile part mechanically responsive to vibrations in the wire means, means for mounting the pick-up device at a point distant from the seat of a disturbance, means responsive to said vibratile part to transform the vibrations into electrical impulses, and means responsive to said electrical impulses to amplify the same and operate a signal.

5. In an alarm system comprising a fencing barrier, a strain resistant wire contacting a part of the barrier, said means being responsive to mechanical vibrations set up in the barrier, a dynamic pick-up device having a vibratile part mechanically responsive to vibrations in the wire, means for mounting the pick-up device at a point distant from the seat of a disturbance, said part contacting the wire, means responsive to said vibratile part to transform the vibrations into electrical impulses, and means responsive to said electrical impulses to amplify the same and operate a signal.

RICHARD W. REYNOLDS.

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