GB2303967A - A vibration sensing device - Google Patents

Abstract

A vibration sensing device (1) comprises a pair of spaced apart first electrically conductive support plates (2,3) and a pair of spaced apart electrically conductive second support plates (10,11). The first and second support plates (2,3,10,11) form respective supports, e.g. annular tracks (6,15), for supporting electrically conductive inertia masses (7,16), which in turn form an electrical circuit between the first and second plates (2,3,10,11). The longitudinal axes of the first and second inertia masses (7,16) extend at an angle, e.g. a right angle, to each other. Thus, the vibration sensing device (1) may be mounted in any orientation through 360{ around the first and second inertia masses (7,16) depending on which of the inertia masses (7, 16) is supported on the support (6,15) in a horizontal orientation thereby increasing the number of orientations at which the device (1) may be mounted.

Description

"A vibration sensing device" The present invention relates to a vibration sensing device, and in particular, though not limited to an inertia sensor for use in an intruder detecting device of the type which would normally be mounted on a window, window frame, door or door frame for detecting vibrations or shock induced by an attempted break-in through the window or door.

Such vibration sensing devices are well known.

Broadly, there are two types of such devices, one of which comprises an inertia mass supported on three spaced apart electrically conductive contacts, and the other of which comprises an inertia mass supported on two spaced apart electrically conductive contacts. The three contact devices, in general, comprise an inertia mass in the form of an electrically conductive sphere, such as, for example, a steel ball which rests on the three contacts. The sphere while resting on the contacts closes a circuit between the contacts, however, an open circuit condition prevails between the contacts when the inertia mass rises from one or more of the contacts as a result of induced shock or vibrations.The two contact devices, in general, comprise an inertia mass formed by elongated electrically conductive bar which rests on the electrically conductive contacts, thus closing a circuit between the contacts. On the bar rising from one or both contacts as a result of induced shock or vibrations, an open circuit condition prevails, thereby giving an indication of an attempted unauthorised entry.

The three contact devices which support a spherical inertia mass, suffer from a number of disadvantages.

In particular, they must be mounted so that the contacts face vertically upwardly for supporting the sphere. Thus, in general, such devices are suitable for mounting in one orientation only. This can be a considerable disadvantage where the device must be located in a relatively inaccessible location, or a location which does not lend itself to the device being mounted with the three contacts facing upwardly.

In general, in the two contact devices each contact is formed by an annular track formed by the peripheral edge defined by a hole extending through a pair of respective electrically conductive plates. The plates are located spaced apart from each other and the inertia bar extends between and through the holes and is supported on the tracks defined by the respective holes. The inertia bar defines a longitudinally extending axis, and it will be appreciated that such devices may be mounted in a plurality of different orientations by rotating the plates about the longitudinal axis of the bar. This, thus, enables this type of device to be mounted in any orientation through 3600 about the axis of the bar. This considerably facilitates mounting of such devices in inaccessible locations.However, it is essential that the device must be mounted with the bar horizontal or substantially horizontal. Therefore, there are still many orientations in which such device can not be mounted.

Thus, while such two contact type devices to some extent alleviate the problems of the three contact type devices, nonetheless, these two contact devices also suffer from limitations to the number of orientations in which they can be mounted in order to operate efficiently.

There is therefore a need for a vibration sensing device which overcomes these problems.

The present invention is directed towards providing such a vibration sensing device.

According to the invention there is provided a vibration sensing device comprising a pair of spaced apart first electrically conductive support means for supporting a first electrically conductive inertia mass extending between the respective first support means for closing an electrical circuit between the respective first support means, the first inertia mass defining a first longitudinal axis extending between the respective first support means, each first support means being located around the first inertia mass so that the first inertia mass is supported on the respective first support means for all angles of rotation of the first support means about the first axis when the first axis extends substantially horizontally, and a pair of spaced apart second electrically conductive support means for supporting a second electrically conductive inertia mass extending between the respective second support means for closing an electrical circuit between the respective second support means, the second inertia mass defining a second longitudinal axis extending between the respective second support means and being disposed at an angle to the first axis, each second support means being located around the second inertia mass so that the second inertia mass is supported on the respective second support means for all angles of rotation of the second support means about the second axis when the second axis extends substantially horizontally.

Preferably, the respective first and second support means are disposed relative to each other so that when the first and second inertia masses are supported substantially horizontally on the respective pairs of first and second support means, the first and second axes of the respective first and second inertia masses are disposed at an angle of approximately 900 relative to each other.

Advantageously, each of the first support means of the pair of first support means is electrically connected to a corresponding one of the pair of second support means.

In one embodiment of the invention a pair of spaced apart third electrically conductive support means is provided for supporting a third electrically conductive inertia mass extending between the respective third support means for closing an electrical circuit between the respective third support means, the third inertia mass defining a third longitudinal axis extending between the third support means, the third axis being disposed at an angle to the respective first and second axes, each third support means being located around the third inertia mass so that the third inertia mass is supported on the respective third support means for all angles of rotation of the third support means about the third axis, when the third axis extends substantially horizontally.

Preferably, the third support means is disposed relative to the first support means so that when the first and third inertia masses are supported substantially horizontally on the respective pairs of first and third support means, the first and third axes of the respective first and third inertia masses are disposed at an angle of approximately 900 relative to each other.

Advantageously, the third support means is disposed relative to the second support means so that when the second and third inertia masses are supported substantially horizontally on the respective pairs of second and third support means, the second and third axes of the respective second and third inertia masses are disposed at an angle of approximately 900 relative to each other.

In another embodiment of the invention at least two pairs of third support means are provided for supporting at least two corresponding spaced apart third inertia masses, the respective third support means of each pair being arranged so that the third axes of the respective third inertia masses extend parallel to each other.

Preferably, each third support means of one pair of third support means is electrically connected to a corresponding one of the third support means of the other pair of third support means.

Advantageously, each of the third support means of each pair of third support means is electrically connected to a corresponding one of the pair of first support means.

In a further embodiment of the invention two pairs of first support means are provided for supporting two spaced apart first inertia masses, the respective first support means of each pair being arranged so that the first axes of the respective first inertia masses extend parallel to each other.

In one embodiment of the invention adjacent first support means of the respective pairs of first support means are electrically separated from each other.

In another embodiment of the invention adjacent first support means of the respective pairs of first support means are electrically connected to the opposite support means of the other pair of first support means.

In one embodiment of the invention two pairs of second support means are provided for supporting two spaced apart second inertia masses, the respective second support means of each pair being arranged so that the second axes of the respective second inertia masses extend parallel to each other.

In another embodiment of the invention adjacent first support means of the respective pairs of second support means are electrically separated from each other.

In a further embodiment of the invention adjacent second support means of the respective pairs of second support means are electrically connected to the opposite second support means of the other pair of second support means.

Preferably, each inertia mass is an elongated inertia mass.

Advantageously, each inertia mass is provided by an elongated electrically conductive bar.

In one embodiment of the invention each support means comprises an electrically conductive annular track for supporting the corresponding inertia mass, each annular track being formed by a peripheral edge of a hole extending through a support plate.

Preferably, each support plate is of electrically conductive material.

Advantageously, a plurality of radially inwardly extending projections extend from each support means for providing point or line electrical contact between the respective support means and the corresponding inertia mass.

In one embodiment of the invention the inertia masses are arranged to cross each other but are electrically separated from each other.

The advantages of the invention are many. By virtue of the fact that first and second inertia masses are supported on respective spaced apart pairs of first and second support means which are located around the respective inertia masses, and the axes of the respective inertia masses are disposed at an angle to each other, the number of orientations at which the vibration sensing device may be mounted are significantly increased, than if only one inertia mass were provided. The vibration sensing device may be disposed at any angle through 3600 about the respective first and second axes, provided the axis of the relevant inertia masses extends horizontally or substantially horizontally.The provision of a third pair of support means supporting a third inertia mass with the third axis of the third inertia mass extending at angles of 900 to the respective first and second axes provides a vibration sensing device which may be mounted in an infinite number of orientations.

The invention will be more clearly understood from the following description of some preferred embodiments thereof which are given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a vibration sensing device according to the invention, Fig. 2 is an exploded perspective view of a portion of the vibration sensing device of Fig. 1, Fig. 3 is a perspective view of a vibration sensing device according to another embodiment of the invention, Fig. 4 is an exploded view of a portion of the vibration sensing device of Fig. 3, Fig. 5 is an elevational view of a detail of the vibration sensing device of Fig. 3, Fig. 6 is a perspective view of a vibration sensing device according to another embodiment of the invention, and Fig. 7 is an exploded perspective view of a portion of the vibration sensing device of Fig. 6.

Referring to the drawings and initially, to Figs. 1 and 2 there is illustrated a vibration sensing device according to the invention indicated generally by the reference numeral 1 for detecting a shock or vibrations. The vibration sensing device 1 illustrates the invention in its simplest form, and the device 1 is particularly suitable for use in an intruder detecting device which would normally be connected to a security circuit, and mounted on a window, window frame, door or door frame for detecting a shock or vibrations induced in the window or door resulting from an attempted break-in. Normally, the vibration sensing device 1 would be housed in a housing, typically, a housing of injection moulded plastics material which is not illustrated.

The vibration sensing device 1 comprises a pair of spaced apart first support means, namely, a pair of spaced apart first support plates 2 and 3 of electrically conductive material. A hole 4 extends through each first support plate 2 and 3 and forms an electrically conductive annular track 6 in each plate 2 and 3 for supporting an inertia mass, namely, an elongated electrically conductive inertia bar 7. The inertia bar 7 when horizontal or substantially horizontal, rests on the tracks 6 of the first support plates 2 and 3, and closes an electrical circuit between the first support plates 2 and 3. On being subjected to a shock or vibration, the first inertia bar 7 vibrates, thus rapidly rising from and falling onto either or both of the tracks 6 for rapidly opening and closing the electrical circuit between the first support plates 2 and 3.

A pair of second support means, namely, a pair of spaced apart second support plates 10 and 11 which are of electrically conductive material and similar to the first support plates 2 and 3 have holes 14 extending therethrough which define electrically conductive annular tracks 15. A second inertia mass, namely, a second elongated electrically conductive inertia bar 16 is supported on the annular tracks 15 in similar fashion as the first inertia mass 7 is supported on first support plates 2 and 3, when the device 1 is oriented with the second inertia bar 16 horizontal.

In this embodiment of the invention the first support plate 2 and the second support plate 10 are formed from a sheet of brass which is bent along an apex 17 so that the first and second support plates 3 and 10, respectively, extend at right angles to each other.

The first support plate 3 and the second support plate 11, are similarly formed from sheet of brass which is likewise bent along an apex 18 so that the first and second support plates 3 and 11 extend at right angles to each other. Accordingly, the first and second support plates 2 and 10, respectively, are electrically connected to each other, while the first and second support plates 3 and 11, respectively, are likewise electrically connected to each other. However, the first and second support plates 2 and 10, respectively, and the first and second support plates 3 and 11, respectively, are electrically separated and insulated from each other, and are electrically connected only by the respective first and second inertia bars 7 and 16.

The first and second inertia bars 7 and 16 are of brass which is gold plated for enhancing electrical contact between the respective bars 7 and 16, and the corresponding annular tracks 6 and 15. The first and second support plates 2, 3 and 10, 11 are also gold plated, as are the annular tracks 6 and 15 for further ensuring good electrical contact between the first and second inertia bars 7 and 16, and the corresponding annular tracks 6 and 15. The first and second inertia bars 7 and 16, respectively, define first and second axes 20 and 21, respectively.The holes 4 and 14 which form the respective annular tracks 6 and 15 are located in the respective first and second support plates 2, 3 and 10, 11, so that when the vibration sensing device 1 is oriented with both of the first and second inertia bars 7 and 16, respectively, resting substantially horizontally on the corresponding annular tracks 6 and 15, the axes 20 and 21 of the inertia bars 7 and 16 are disposed at an angle of approximately 900 to each other. To ensure that the first and second inertia bars 7 and 16 are separated from each other for all orientations of the vibration sensing device 1, the holes 4 and 14 are offset relative to each other.

Since the annular tracks 6 and 15 extend completely around the respective first and second inertia bars 7 and 16, the vibration sensing device may be mounted in any orientation once one of the first and second inertia bars 7 and 16 rests horizontally on the corresponding annular tracks 6 or 15. Thus, the vibration sensing device may be mounted at any orientation through 360 about the respective first and second inertia bars 7 and 16, which ever is substantially horizontal.

Electrical connectors 25 and 26 extend, respectively from the first support plate 3 and the second support plate 10 for connecting the vibration sensing device 1 into a security circuit, typically, into a loop circuit whereby the vibration sensing device 1 is connected in series or in parallel with other security sensors, which may include one or more similar type vibration sensing devices. Accordingly, electrical continuity is maintained through the security circuit between the connectors 25 and 26, the first and second support plates 2 and 3, and 10 and 11, respectively, through one or other or both of the inertia bars 7 and 16, depending upon the orientation at which the vibration sensing device 1 is mounted.

In use, with the vibration sensing device 1 mounted on a door or window frame, or a door or window, and connected into a security circuit which is being monitored by a central control panel, with the vibration sensing device 1 being subjected to a shock or vibration, the relevant inertia bar or inertia bars 7 and 16 vibrate, thereby rapidly opening and closing the security circuit between the connectors 25 and 26.

The central control panel on detecting such vibration determines if an attempt is being made to break or gain entry through the door or window on which the vibration sensing device 1 is mounted.

Referring now to Figs. 3 to 5 there is illustrated a vibration sensing device 30 according to another embodiment of the invention. The vibration sensing device 30 in principle is substantially similar to the vibration sensing device 1 and similar components are identified by similar reference numerals. The main difference between the device 30 and the device 1 is that instead of having one first inertia bar 7 and one second inertia bar 16, the vibration sensing device 30 is provided with two parallel first inertia bars 7 and two parallel second inertia bars 16 which are disposed at approximately 900 to the first inertia bars 7. In this embodiment of the invention two pairs of first support plates 2 and 3 are provided for supporting the two first inertia bars 7, and two second support plates 10 and 11 are provided for supporting the two second inertia bars 16.

The pairs of first support plates 2 and 3 and the pairs of second support plates 10 and 11 are located so that the first inertia bars 7 extend parallel to each other and the second inertia bars 16 also extend parallel to each other, but the first inertia bars 7 extend at right angles to the second inertia bars 16.

Additionally, to provide symmetry to the vibration sensing device 30, the first support plate 2 of one pair of first support plates 2 and 3 is located opposite to the first support plate 2 of the other pair of first support plates 2 and 3, as are the two first support plates 3 located opposite to each other.

Additionally, the two first support plates 2 of the two pairs of first support plates 2 and 3 are electrically connected together, as are the two first support plates 3 electrically connected. The second support plates 10 of the pairs of second support plates 10 and 11 are also located in similar fashion as the first support plates 2 of the pairs of first support plates 2 and 3, as are the second support plates 11 of the pairs of second support plates 10 and 11 located similarly to the first support plates 3. Additionally, the second support plates 10 of each pair of second support plates 10 and 11 are electrically connected together as are the second support plates 11 of each pair of second support plates 10 and 11 electrically connected. An electrically conductive connecting member 34 extends between the second support plates 10 for electrically connecting the plates 10, and an electrically conductive connecting member 35 extends between the second support plates 11 for electrically connecting the second support plates 11. The plates 2 and 10 are electrically connected as are the plates 3 and 11.

The holes 4 and 14 in the first support plates 2 and 3 and in the second support plates 10 and 11, respectively, are located so that for all orientations of the vibration sensing device about the respective first and second axes 20 and 21, the first and second inertia bars 7 and 16 are at all times electrically separated.

In this embodiment of the invention the holes 4 and 14 in the first support plates 2 and 3 and second support plates 10 and 11, respectively, are formed with a plurality of radially inwardly extending projections 36 for supporting the respective first and second inertia bars 7 and 16, with substantially line contact for increasing electrical continuity between the respective first and second bars 7 and 16 and the annular tracks 6 and 15 formed by the holes 4 and 14.

The first and second support plates 2 and 3, and 10 and 11, respectively, the connecting members 34 and 35 and the connectors 25 and 26 are punched and bent from respective sheets of brass which are subsequently gold plated. The first and second inertia bars 7 and 16 are also of brass gold plated.

Otherwise, this vibration sensing device 30 and its operation are is similar to that of the vibration sensing device 1, and its mounting to a structure is similar to that already described with reference to the vibration sensing device 1.

Referring now to Figs. 6 and 7 there is illustrated a vibration sensing device 40 according to a further embodiment of the invention. The vibration sensing device 40 in principle is substantially similar to the vibration sensing device 1 and similar components are identified by the same reference numerals. The main difference between the vibration sensing device 40 and the vibration sensing device 1 is that a pair of third electrically conductive support plates 42 and 43 are provided for supporting two third electrically conductive inertia bars 44 so that longitudinally extending axes 45 of the third inertia bars 44 extend at angles of approximately 900 to both the first and second axes 20 and 21, respectively, of the first and second inertia bars 7 and 16.The third support plate 42 is electrically connected to the first and second support plates 2 and 10, respectively, while the third support plate 43 is electrically connected to the first and second support plates 3 and 11. Holes 46 through the third support plates 42 and 43 form annular tracks 47 for supporting the inertia bars 44, when the bars 44 are horizontal. Accordingly, the vibration sensing device 40 can be mounted in any orientation through 3600 about the respective first, second and third axes 20, 21 and 45, respectively, provided one of the first, second and third axes 20, 21 and 45, respectively, extends horizontally. Accordingly, the vibration sensing device 40 may be mounted in an infinite number of orientations.

The first, second and third support plates 2, 3 and 10, 11 and 42, 43 are formed from respective sheets of brass by punching and bending, which are subsequently gold plated. The first, second and third inertia bars 7, 16 and 44 are also of brass gold plate.

While the first, second and third support means have been described as being provided by electrically conductive annular tracks formed in first, second and third support plates, the first, second and third support means may be provided by any other suitable support means, for example, by a wire or wires bent into the appropriate shape or shapes for extending around the corresponding inertia bar. Needless to say, any other suitable first, second and third inertia mass may be provided. Indeed, in certain cases, it is envisaged that the inertia masses may be provided by spheres.

Claims (24)

1. A vibration sensing device comprising a pair of spaced apart first electrically conductive support means for supporting a first electrically conductive inertia mass extending between the respective first support means for closing an electrical circuit between the respective first support means, the first inertia mass defining a first longitudinal axis extending between the respective first support means, each first support means being located around the first inertia mass so that the first inertia mass is supported on the respective first support means for all angles of rotation of the first support means about the first axis when the first axis extends substantially horizontally, and a pair of spaced apart second electrically conductive support means for supporting a second electrically conductive inertia mass extending between the respective second support means for closing an electrical circuit between the respective second support means, the second inertia mass defining a second longitudinal axis extending between the respective second support means and being disposed at an angle to the first axis, each second support means being located around the second inertia mass so that the second inertia mass is supported on the respective second support means for all angles of rotation of the second support means about the second axis when the second axis extends substantially horizontally.

2. A vibration sensing device as claimed in Claim 1 in which the respective first and second support means are disposed relative to each other so that when the first and second inertia masses are supported substantially horizontally on the respective pairs of first and second support means, the first and second axes of the respective first and second inertia masses are disposed at an angle of approximately 900 relative to each other.

3. A vibration sensing device as claimed in Claim 1 or 2 in which each of the first support means of the pair of first support means is electrically connected to a corresponding one of the pair of second support means.

4. A vibration sensing device as claimed in any preceding claim in which a pair of spaced apart third electrically conductive support means is provided for supporting a third electrically conductive inertia mass extending between the respective third support means for closing an electrical circuit between the respective third support means, the third inertia mass defining a third longitudinal axis extending between the third support means, the third axis being disposed at an angle to the respective first and second axes, each third support means being located around the third inertia mass so that the third inertia mass is supported on the respective third support means for all angles of rotation of the third support means about the third axis, when the third axis extends substantially horizontally.

5. A vibration sensing device as claimed in Claim 4 in which the third support means is disposed relative to the first support means so that when the first and third inertia masses are supported substantially horizontally on the respective pairs of first and third support means, the first and third axes of the respective first and third inertia masses are disposed at an angle of approximately 900 relative to each other.

6. A vibration sensing device as claimed in Claim 4 or 5 in which the third support means is disposed relative to the second support means so that when the second and third inertia masses are supported substantially horizontally on the respective pairs of second and third support means, the second and third axes of the respective second and third inertia masses are disposed at an angle of approximately 900 relative to each other.

7. A vibration sensing device as claimed in any of Claims 4 to 6 in which at least two pairs of third support means are provided for supporting at least two corresponding spaced apart third inertia masses, the respective third support means of each pair being arranged so that the third axes of the respective third inertia masses extend parallel to each other.

8. A vibration sensing device as claimed in Claim 7 in which each third support means of one pair of third support means is electrically connected to a corresponding one of the third support means of the other pair of third support means.

9. A vibration sensing device as claimed in any of Claims 4 to 8 in which each of the third support means of each pair of third support means is electrically connected to a corresponding one of the pair of first support means.

10. A vibration sensing device as claimed in any preceding claim in which two pairs of first support means are provided for supporting two spaced apart first inertia masses, the respective first support means of each pair being arranged so that the first axes of the respective first inertia masses extend parallel to each other.

11. A vibration sensing device as claimed in Claim 10 in which adjacent first support means of the respective pairs of first support means are electrically separated from each other.

12. A vibration sensing device as claimed in Claim 10 or 11 in which adjacent first support means of the respective pairs of first support means are electrically connected to the opposite support means of the other pair of first support means.

13. A vibration sensing device as claimed in any preceding claim in which two pairs of second support means are provided for supporting two spaced apart second inertia masses, the respective second support means of each pair being arranged so that the second axes of the respective second inertia masses extend parallel to each other.

14. A vibration sensing device as claimed in Claim 13 in which adjacent first support means of the respective pairs of second support means are electrically separated from each other.

15. A vibration sensing device as claimed in Claim 13 or 14 in which adjacent second support means of the respective pairs of second support means are electrically connected to the opposite second support means of the other pair of second support means.

16. A vibration sensing device as claimed in any preceding claim in which each inertia mass is an elongated inertia mass.

17. A vibration sensing device as claimed in any preceding claim in which each inertia mass is provided by an elongated electrically conductive bar.

18. A vibration sensing device as claimed in any preceding claim in which each support means comprises an electrically conductive annular track for supporting the corresponding inertia mass, each annular track being formed by a peripheral edge of a hole extending through a support plate.

19. A vibration sensing device as claimed in Claim 18 in which each support plate is of electrically conductive material.

20. A vibration sensing device as claimed in any preceding claim in which a plurality of radially inwardly extending projections extend from each support means for providing point or line electrical contact between the respective support means and the corresponding inertia mass.

21. A vibration sensing device as claimed in any preceding claim in which the inertia masses are arranged to cross each other but are electrically separated from each other.

22. A vibration sensing device substantially as described herein with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings.

23. A vibration sensing device substantially as described herein with reference to and as illustrated in Figs. 3 to 5 of the accompanying drawings.

24. A vibration sensing device substantially as described herein with reference to and as illustrated in Figs. 6 and 7 of the accompanying drawings.