US3896426A

US3896426A - Theft alarm employing self-adjusting disturbance switch

Info

Publication number: US3896426A
Application number: US322151A
Authority: US
Inventors: Philippe Laurent
Original assignee: Klaxon SA
Current assignee: Klaxon SA
Priority date: 1972-01-11
Filing date: 1973-01-09
Publication date: 1975-07-22
Anticipated expiration: 1992-07-22
Also published as: DE2301271C3; IT978084B; GB1418722A; DE2301271A1; FR2167234B1; FR2167234A1; DE2301271B2

Abstract

This invention relates to an alarm device comprising a sensitive element and electric circuit arranged for releasing an alarm signal when the sensitive element is exposed to shocks or vibration. The sensitive element comprises at least one flexible rod adapted to contact an annular abutment, the contact thus formed between the rod and said abutment being inserted in the electric circuit. This device is suitable for protecting rooms, premises or vehicles against intruders.

Description

United States Patent [191 Laurent July 22, 1975 [54] THEFT ALARM EMPLOYING 2,885,504 5/1959 Yurtz 340/65 SELF ADJUSTING DISTURBANCE SWITCH 3,053,949 9/1962 Johnson 340/ 261 3,074,049 1/1963 Sallba et al. 340/65 Inventor: pp Laurent, Eaubonne. France 3.192517 6/1 965 Werlin .[340/261 [73] Assignee: Klaxon, Ne'uilly-sur-Seine, France Primary ExaminerGlen R. Swann, Ill [22] Filed 19-73 Attorney, Agent, or FirmFleit & Jacobson [21] App], No.1 322,151

' V 57 ABSTRACT [30] Foreign Application Priority Data Jan H 1972 France 72 00714 This invention relates to an alarm device comprising a sensitive element and electric circuit arranged for re- [52] U S C 340/26l. 200/61 200/61 51 leasing an alarm signal when the sensitive element is [51] 6 m2 exposed to shocks or vibration. The sensitive element '[58] Fienld 200/61 49 comprises at least one flexible rod adapted to contact zoo/61' an annular abutment, the contact thus formed between the rod and said abutment being inserted in the [56] References Cited electric circuit. This device is" suitable for protecting UNITED STATES PATENTS rooms, premises or vehicles against intruders. 2,407,122 9/1946 Young 340/261 I 11 Claims, 5 Drawing Figures therewith and to be explained in detail presently.

THEFT ALARM EMPLOYING SELF-ADJUSTING DISTURBANCE SWITCH BACKGROUND OF INVENTION The present invention relates in general to alarm systems and has specific reference to alarm devices of the type adapted to be secured to a wall. partition or panel of a room. premises or a vehicle to be protected against undesired tampering or intrusion. Thesedevices are of v the type-comprising essentially in combination at least one sensitive element and electric means. adapted to release an alarm signal when the sensitive element is exposed to shocks or vibration of a predetermined P V t It is the primary object of the present invention to provide devices of the type broadly set forth hereinabove and such that they constitute a marked improvement over the prior art from the point of view of constructional simplicity, reliability and low cost.

Accordingly, this invention is directed to provide an improved alarm device which is relatively simple, reliable and economical.

Another object of this invention is to provide an alarm device capable, owing to its high sensitivity, to release an alarm signal before one or more intruders can damage the wall or partition to which the device is secured.

The alarm device according to this invention comprises an assembly consisting of at least one sensitive element and electronic means adapted to release an alarm signal when said sensitive element is exposed to shocks and/or vibration of a predetermined character, the assembly beingfurther characterised in that:

a. the sensitive element comprises at least one rod having one end fitted on a frame structure and having certain flexibility properties at least in the vicinity of its fitted end, and a fixed or displaceable abutment disposed ,on said frame structure for limiting the beat or oscillation of said rod at least in one direction, said abutment being remote from the fitted end of the rod, with at least one portion of said abutment and at least the rod portion being adapted to engage said abutment consisting of electric conducting material, and

b. electric means comprising said abutment and rod portions, a source of electric current and a relay controlling the energization of an alarm circuit, said relay being so connected to said source of current that it is closed when said abutment portion and said rod portion contact each other, and to remain closed when this contact is discontinued.

Under these conditions it is clear that the alarm device of this invention is simple, reliable and of relatively low cost. Moreover, it is characterised by a high sensitivity. I

This invention, in addition to the main arrangement broadly described hereinabove, comprises certain other arrangement to be used preferably in conjunction 'ment of the invention, it being understood that these are given by way of illustration, not of limitation. ln the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic illustration of a typical form of embodiment of an alarm device constructed according to the teachings of this invention;

FIG. 2 is a section taken along the line llll of FIG.

1 but on a larger scale;

FIG. 3 is a diagrammatic view illustrating an alarm device constructed according to another form of embodiment of the invention.

' FIG. 4 is a fragmentary section illustrating on a larger scale a. modified device according to the principle of the form of embodiment shown in FIG. I, and

FIG. 5 is a diagrammatic view illustrating the telescopic feature of the inventive alarm device.

The device illustrated in FIGS. 1 and 3 comprises a sensitive element 1 and electric means 2, constituting an assembly adapted to deliver an alarm signal when the sensitive element 1 is exposed to shocks or vibration of a certain character.

The sensitive element 1 illustrated in FIG. 1 comprisesessentially a flexible rod 3 having one end fitted in a frame structure 4. This frame structure 4 has fas- The flexible rod 3 advantageously consists of a circu- 1 larsectional straight metal rod and is disposed vertically with its lower end fitted or embedded in the frame structure 4.

An annular abutment member 6 advantageously consisting of a metal washer is disposed on said frame structure 4 for limiting the permissible radial oscillation of the flexible rod 3 in all directions, this annular abutment member'6 surrounding a portion of the flexible rod which is relatively remote from its end engaged in the frame structure 4.

The aforesaid annular abutment 6 and frame structure 4 are electrically insulated by means of an insulating plate 7 constituting the top cover of said frame structure 4. I

At the level of said annular abutment 6 a metal block 8 of substantially frustoconical configuration is advantageously provided on said rod 3 and adapted to slide longitudinally therealong in order to vary at will the clearance between this block 8 and the annular abutment 6. This advantageous arrangement permits adjusting the sensitivity of the device by simply setting the metal block 8 in the proper position along said rod 3.

The metal block 8 may be locked in the selected position along the rod 3 by means of one or a plurality of set screws 9.

The flexible rod 3 may be provided with an auxiliary weight 10 disposed preferably above the metal block 8 and slidably displaceable along the flexible rod 3 to permit the adjustment of its inherent vibration frequency.

This auxiliary weight 10 may advantageously consist of a pair of disks 10a, 10b each formed with a through hole 11 so that each disk has its center of gravity disposed eccentrically in relation to said rod. Each disk 10a, 10b further comprises one or a plurality of set screws 12 for the dual purpose of locking the auxiliary weight 10 to the flexible rod 3 and varying as required the relative angular position of said disks 10a, 10b (see FIG. 2). 1

With this arrangement, the flexible rod 3 can be properly centered with respect to the axis of the annular abutment 6.

According to an arrangement applicable more particularly to a more economical range of alarm devices adapted to be put into actual service without requiring a preliminary adjustment, the annular abutment 6 is displaceably mounted. This arrangement is illustrated in FIG. 4 in which the same or corresponding component elements are designed with the same reference numerals as in FIG. 1.

The annular abutment consists in this case of a conducting washer bearing by gravity on a support 6a made of electrical conducting material. This support 6a may consist for instance of the metal section of a printed circuit of which the insulating portion is the aforesaid insulating plate 7.

With this arrangement, the centering adjustments in the inoperative condition of the metal block'8 take place automatically as a consequence of contacts have already taken place between the metal block 8 and the annular abutment 6 due to accidental or voluntary shocks; in fact, since the clearance is relatively small between the metal block 8 and the annular abutment 6, the flexible rod 3 carrying said metal block 8 will come naturally to a standstill without producing any contact between said block and the annular abutment 6 which will have been moved in one or several directions, and in at least one way (inwards or outwards) during the initial oscillations of greater amplitude imparted to the flexible rod.

This specific arrangement is particularly advantageous in that the putting of the apparatus into actual service is thus greatly facilitated. In fact, it is only necessary to impart one or several initial shocks thereto (as will compulsorily occur when fitting the device in position) for obtaining a satisfactory and automatic adjustment of the device. Under these conditions, no specific care is required when putting the device into service, as far as the fastening of the device and the proper vertical positioning of the flexible rod 3 are concerned.

The electric means 2 illustrated in FIG. 1 comprise said annular abutment 6 and flexible rod 3, plus a source of current 13 and a relay 14 controlling the energization of an alarm signal 15.

This relay 14 is so connected to the current source 13 that it closes when a contact occurs between said annular abutment 6 and the flexible rod 3, the relay 14 remaining subsequently in its closed position, even when this contact is discontinued.

To this end, the relay 14 comprises a coil 16 controlling a pair of

contacts

17 and 18, the terminals of said coil 16 being connected the one to the source of current 13 and the other on the one hand to said flexible rod 3 (or to the annular abutment 6) and on the other hand to one of the pair of contacts (for example contact 17) of relay 14.

The other contact (in this case contact 18) of relay 14 is inserted in the alarm circuit 15 comprising for example a separate or independent source of current 19 and a sound or light signal device 20.

The annular abutment 6 (of the flexible rod 3) is connected via a main switch 21 to the source of current 13, so that the device can be set in its operative condition (with switch 21 closed) or in its inoperative condition (with switch 21 open).

Therefore. a single contact between the flexible rod 3 and the annular abutment 6 is sufficient for energizing the relay 14 which, being fed with current through its holding contact 17, remains energized. When it is desired to stop the operation of the alarm circuit 15, the relay 14 must be released by performing a separate operation. If it is desired to limit the time period during which the alarm circuit can be rendered operative, a timing device 22 may be inserted between the coil 16 and contact 17 and, a switch 23 connected in parallel with said timing device 22.

When switch 23 is closed, the timing device 22 is shunted off and when the switch 23 is open said timing device 22 receives the energizing current for coil 16 and is adapted to open this coil energizing circuit after a predetermined time period, thus discontinuing the operation of the alarm circuit 15. I

The sensitive element 1 illustrated in FIG. 3 comprises a pair of flexible rods 24 and 25 having their ends fitted in a frame structure 26. This frame structure 26 comprises fastening lugs 27 for securing the device to a'partition, wall or panel of the room, premises or vehicle to be protected against undesired intrusions.

The pair of flexible rods 24 and 25 comprise vertically disposed circular-sectioned metal rods having therefore their lower ends fitted or embedded in the frame structure 26.

A pair of

annular abutments

28 and 29 advantageously consisting of a metal washer are disposed in the frame structure 26 for limiting the possible beats of flexible rods 24 and 25 in all directions, each

annular abutment

28 or 29 surrounding the corresponding flexible rod 24 or 25 at a level relatively remote from its fitted or embedded end.

The

annular abutments

28 and 29, whether fixed, movable or adjustable, and the frame structure 26 are electrically insulated by means of an insulating plate 30.

A At the level of the pair of

annular abutments

28 and 29 the pair of flexible rods 24 and 25 may advantageously carry corresponding metal blocks 31 and 32 of substantially frustoconical configuration, which are slidably mounted on the corresponding rod 24 or 25 and thus permit adjusting and varying at will the clearance between each

metal block

31 or 32 and the corresponding

annular abutments

28 or 29. This advantageous arrangement permits of adjusting or presetting the sensitivity of the device by simply moving the metal blocks 31 and 32 along their relevant flexible rods 24 and 25.

The metal blocks 31 and 32 may be locked on the corresponding rods 24 and 25 by means of one or more set screws 33.

Furthermore, the pair of flexible rods 24 and 25 may be provided with

metal weights

34 and 35, respectively, disposed preferably above the aforesaid metal blocks 31 and 32. Said

auxiliary weights

34 and 35 are slidably mounted on the rods 24 and 25 to permit the proper adjustment of the inherent oscillation frequency of .these rods.

On the other hand, the two rods 24 and 25 may be adjusted differently so that each of them has a different inherent frequency.

a first circuit 36 associated with one of the flexible The electric means 2 illustrated in FIG. 2 comprise both

circuits

36, 37 comprise the same current source I 38 and are controlled by a starting switch 39.

continued.

To this end, the relay 40 comprises acoil 42 control- I ling a pair of

contacts

43, 44, the terminals of said coil 42 being connected the. one to the current source 38 and the other on the one hand to the flexible rod 24 (or to the annular abutment 28) and on the other hand to one of the pair of contacts 43 of relay 40.

The other contact 44 of relay 40 is inserted in the alarm circuit 41 which may be connected to the source of current 38 and comprise a pilot light 45. If desired, this light 45 maybe controlled independently, for example for illumination purposes, through a connection 46 comprising a switch 47. The annular abutment 28 (of the flexible rod 24) is connected to the source of current 38 via a starting or main switch 39. q

A timing device 48 is disposed between the coil and contact 43.

Under these conditions, and when the switch 47 is open, a single contact between the flexible rod 24 and annular abutment 28 will cause the energization of relay 40 which, being subsequently kept in its energized condition by its holding contact 43, is controlled by the time constant of said timing device 48.

The other circuit 37 comprises an annular abutment 29, the flexible rod 25 and a relay 49 controlling another alarm circuit50.

This relay 49 is connected to the source of current 38 so as to close when a contact takes place between the annular abutment 29 and the flexible rod 25, the relay remaining closed even after this contact is discontinued.

To this end, the relay 49 comprises a coil 51 actuating a pair of

contacts

52 and 53, one terminal of said coil 51 being connected to the source of current 38, the other terminal being connected on the one hand to the flexible rod 25 (or to the annular abutment 29) and on the other hand to one of the pair of contacts 52 of relay 49.

The other contact 53 of relay 49 is inserted in the alarm circuit 50 comprising for example a separate current source 54 and a sound alarm device 55.

The annular abutment 29 (of the flexible rod 25) is connected to the source of current 38 via the starting or main switch 39.

Under these conditions, a single contact between the flexible rod 25 and the annular abutment 29 is sufficient for energizing the relay 49 which, being then energized through its holding contact 52, remains energized.

As explained in the foregoing with reference to the form of embodiment illustrated in FIG. 1, a timing device 56 is provided between the coil 51 and contact 52, a switch 57 being advantageously connected in parallel with said timing device 56.

A voltage checking device 58 may be connected across the voltage source 38, if desired.

In any one of the above-described forms of embodiment the switch 21 (FIG. I) or 39 (FIG. 3) may be controlled if desired from the locks or other closing devices provided on the doors and/or windows of the room.

premises or vehicle to be protected.

In all cases, the inherent frequency of the flexible rods of the device can be adjusted by changing the position of an auxiliary mass or weight.

' It may also'be pointed out that the inherent frequency of these rods may be adjusted by altering their lengths, this adjustment procedure being facilitated by using telescopic flexible rods shown at 3a'and 3b in FIG. 5. Y I I The alarm device according to this invention may be provided with flexible rods of different lengths, for example by providing an adjustable fitting of these rods in the frame structure of the device.

If the use of flexible rods of relatively great length I (and therefore of relatively low frequency) is contemplated, the device may be rendered substantially insensitive to accidental shocks. i

In contrast thereto, if the device is provided with a flexible rod of relatively short length and therefore of highinherent frequency even the slightest shock will cause its operation.

In any case, it is still possible to adapt the flexible rod as a function of the inherent frequency of the partition, wall or panel of the room or vehicle to be protected, for instance if the space to be protected is a flat, a bungalow, a caravan or a motor vehicle.

The ideal adjustment would consist in general in tuning the flexible rod at an inherent frequency slightly inferior or slightly superior to that of said partition, wall or the like, considering the fact that any attempt to tamper with or intrude in such space involves almost inevitably either a shock disturbing the natural vibration or a variation in the inherent frequency of the partition or like element.

If the device comprises two flexible rods, these are arranged preferably with a view to have different inherent frequencies; on the other hand, it is also advantageous to provide different clearances between the flexible rods and their corresponding annular abutments.

Thus, an advantageous procedure may consist in providing an arrangement wherein:

the shortest rod will have a very small clearance with respect to its surrounding annular abutment; it will be sensitive to a strong shock, its inherent frequency being greater than that of said partition or panel;

the longest rod will have a greater clearance in relation to its annular abutment and will be sensitive to repeated, moderate shocks, its inherent frequency being lower than that of said partition or wall (such moderate, recurrent shocks being produced for example by movements such as placing tools for breaking a door open, or the like, or by the slow progress of a burglar on the roof of a bungalow).

The complete assembly (i.e., the sensitive element and the electric means) may be enclosed in a casing adapted to be secured to the proper partition, wall or panel of the flat, room, premises or vehicle to be protected, only the upper portion of the flexible rod or rods projecting from the top of this casing.

Although specific forms of embodiment of this invention have been described hereinabove and illustrated in the accompanying drawing, it will readily occur to those skilled in the art that various modifications and changes may be brought thereto without departing from the scope of the invention as set forth in the appended claims.

What is claimed as new is:

l. A disturbance switch for use in an alarm device comprising at least one element sensitive to shocks and vibration, and electric means, said sensitive element comprising at least one rod having a circular crosssectional contour and one end fitted in a frame structure to assume a generally upright position, said rod having flexibility characteristics at least in the vicinity of its fitted end, and an abutment member disposed on said frame structure for limiting the beat of said rod in at least one direction, said abutment member being remote from the fitted end of said rod, at least one portion of said abutment member and at least one portion of said rod which is adapted to contact said abutment member consisting of electrical conducting material, and electric means comprising said portions of said abutment member and rod consisting of electrical conducting material, a source of current and a relay controlling the release of an alarm circuit, said relay being so connected to said current source that said relay is closed when a contact takes place between said portions of said abutment member and rod, and remains closed even after said contact is discontinued, the improvement in the disturbance switch comprising said abutment member consisting of an annular member surrounding said rod with a certain clearance and said annular member being adapted to move freely radially with respect to said rod whereupon vibration of said flexible rod self-centers the freely radially moveable annular member about said flexible rod.

2. Disturbance switch according to claim 1, characterised in that said sensitive element comprises two flexible rods having different inherent frequencies.

3. Disturbance switch according to claim 1 including a metal block of substantially frustoconical configuration, slidably mounted to said flexible rod at the level of said annular abutment, said metal block being adapted to be moved along said flexible rod.

4. Disturbance switch according to claim 1, characterised in that said flexible rod is provided with an auxiliary weight displaceable along said flexible rod.

5. Disturbance switch according to claim 1, wherein said flexible rod has its lower end embedded in said frame structure and a displaceable weight is mounted to said flexible rod at its upper end.

6. Disturbance switch according to claim 4, characterised in that said auxiliary weight consists of a pair of disks having their centers of gravity off-set in relation to the rod axis, said disks being displaceable angularly in relation to each other and along said flexible rod.

7. Disturbance switch according to claim 1 characterised in that said flexible rod is telescopic.

8. Disturbance switch according to claim 1 characterised in that the inherent frequency of said flexible rod is adjusted to a value slightly lower or slightly greater than the inherent frequency value of the partition, wall or panel on which the sensitive element is mounted.

9. Disturbance switch according to claim 2 characterised in that one of the pair of flexible rods has a higher inherent frequency and a lower clearance in re: lation to its annular abutment, and that the other flexible rod has a lower inherent frequency and a greater clearance in relation to its annular abutment.

10. Distrubance switch according to claim 2 characterised in that said relay controls the actuation of at least one alarm circuit, said relay comprising a coil adapted to actuate a pair of contacts, the terminals of said coil being connected the one to the source of current and the other on the one hand to one of the pair of flexible rods and abutment associated therewith and on the other hand to one contact of said pair of contacts of said relay, the other contact of said pair being inserted in said alarm circuit, to the other of the pair of flexible rods and abutment associated therewith.

l 1. Disturbance switch according to claim 10, including timer means for discontinuing operations of the alarm device wherein said relay is provided with a timing device inserted between said coil of said relay and the contact of said relay which is adapted to receive the relay energizing current.

Claims

1. A disturbance switch for use in an alarm device comprising at least one element sensitive to shocks and vibration, and electric means, said sensitive element comprising at least one rod having a circular cross-sectional contour and one end fitted in a frame structure to assume a generally upright position, said rod having flexibility characteristics at least in the vicinity of its fitted end, and an abutment member disposed on said frame structure for limiting the beat of said rod in at least one direction, said abutment member being remote from the fitted end of said rod, at least one portion of said abutment member and at least one portion of said rod which is adapted to contact said abutment member consisting of electrical conducting material, and electric means comprising said portions of said abutment member and rod consisting of electrical conducting material, a source of current and a relay controlling the relasse of an alarm circuit, said relay being so connected to said current source that said relay is closed when a contact takes place between said portions of said abutment member and rod, and remains closed even after said contact is discontinued, the improvement in the disturbance switch comprising said abutment member consisting of an annular member surrounding said rod with a certain clearance and said annular member being adapted to move freely radially with respect to said rod whereupon vibration of said flexible rod self-centers the freely radially moveable annular member about said flexible rod.

9. Disturbance switch according to claim 2 characterised in that one of the pair of flexible rods has a higher inherent frequency and a lower clearance in relation to its annular abutment, and that the other flexible rod has a lower inherent frequency and a greater clearance in relation to its annular abutment.

11. Disturbance switch according to claim 10, including timer means for discontinuing operations of the alarm device wherein said relay is provided with a timing device inserted between said coil of said relay and the contact of said relay which is adapted to receive the relay energizing current.