GB2372799A - Security system including a smoke composition - Google Patents

Abstract

A non-rigid security device comprises a pyrotechnic composition 7, an igniter 10 therefor, field detection means, and motion sensors. Control means may initiate ignition in response to a signal from said motion sensors, if there is a continued absence of a signal from said field detection means subsequent to a predetermined delay period after the field detection means ceases to detect a field. The device is sufficiently flexible for it to be incorporated within a bundle of bank notes or the like without impairment of their feel. The pyrotechnic material 7 may cover a printed circuits board 2 on which the field detection means, motion sensor and a sounder 4 are mounted. The pyrotechnic composition comprises a colouring agent, a fuel, an oxidiser and silicone rubber.

Description

SECURITY SYSTEM INCLUDING A SMOKE COMPOSITION The present invention relates to a security device and to a security system which may employ

said security device, said device incorporating a smoke composition, which term is intended al s to include compositions which are capable of generating smoke, preferably, but not ZD exclusively, coloured smoke.

The invention further relates to the smoke composition.

The composition should be sufficiently flexible as to allow its concealment within a flexible substrate, one example of which is a bank note package, or sufficiently mouldable as to be shaped for easy concealment. Other uses can of course be foreseen. However, one function of the composition of the invention is for use in bank and retail security, and therefore the present invention further relates more particularly to a bank note package containing the composition of the invention. It further relates to a security system of which the composition of the invention forms a part.

It is well known to provide a smoke producing composition for use in grenades and the like, which, when ignited, produces a smoke, often coloured, from the grenade It is also known to incorporate smoke producing compositions within carriers for currency, which compositions can be activated in the event of a robbery to emit a dye to stain the money and thereby make it unusable, and also to stain the hands and clothes of the thieves Such compositions are usually concealed within a special briefcase, dummy bundle or the like The deterrent effect of such compositions relies on the thief taking an alarmed briefcase, bundle of notes or other container within which is the money or other valuables It would be preferable if the money itself could be discreetly alarmed, so that an alarmed bundle of notes could be given to, or taken by, a thief and activated after a predetermined interval. However, it is sometimes customary to flick through a bundle of notes to check that all is correct and, since a bundle of bank notes is not a rigid object, a rigid composition within the bundle would be obvious to a thief Where the smoke producing composition is concealed within the bundle, it has hitherto usually been contained within a metal canister, concealed within the bundle and of size approximately 10 x 50 x 70 millimetres or such other size as to suit the dimensions of the bank note bundle Such a solid object renders the bundle easily identifiable by thieves as being alarmed, since it will lack the flexibility of standard bank note packages.

The feel of the bank note package can be improved by providing a liquid smoke generating composition within a plastics foil container. This gives a very flexible package. However, it is possible to puncture the container or for it otherwise to leak. In this event, the notes of the package, and other notes with which the leaking dye composition comes into contact will become irretrievably stained. Furthermore, the leaking dye composition may stain the hands and clothing of innocent people This in itself is troublesome but it may also confuse the police or security officers when searching for the perpetrators of a crime or attempted crime Liquid compositions as described above are difficult to make and difficult to ignite.

Furthermore, in common with compositions in solid block form or enclosed within a canister, it is not easy to locate such compositions in awkward corners or around objects, either for concealment or to provide the maximum amount of smoke.

It is thus one object of a first aspect of the present invention to provide a composition which may be used in a deterrent smoke charge for use in a bundle of bank notes or the like and which may conform to the general flexibility of a bundle of bank notes or the like and which obviates the disadvantages set out above.

Also, it is usually necessary to provide some electronic control means, at least for initiating combustion. This needs also to be accommodated discreetly within the bundle and to this end should be inset, at least partially, into the composition.

Hence, another object of the present invention is to provide a solid but mouldable smoke generating composition which obviates the disadvantages set out above, and allows the composition to be moulded around the electronic control means.

Hence, further objects of other aspects of the present invention are to provide a security device and a security system adapted to exploit the benefits of said composition According to a first aspect of the present invention, there is provided a pyrotechnic composition comprising a colouring agent, a fuel, an oxidiser and a silicone rubber The silicone rubber may be present in the composition in an amount of between 15 and 35 wt%, preferably between 20 and 30 wt%, optionally in the region of 30 wt% Preferably, the silicone rubber is a room temperature vulcanisable silicone The viscoelasticity of the composition may be adjusted by addition of a small quantity of low viscosity, e. g 50 centistokes (0. 00005 m2/s) silicone fluid The fuel, which is preferably a sugar or other carbohydrate such as sucrose, fructose, lactose, maltose, corn starch, dextrin or cellulose, preferably lactose, may be present in the composition in an amount of between 13 and 30 wt%, optionally in the region of 16 and 20 wt%.

The oxidiser may be present in the composition in an amount of between 17 and 30 wt%, optionally in the region of 25 wt%.

The oxidiser may be an oxygen containing compound, such as a chlorate or perchlorate of an alkali metal such as sodium or potassium. The preferred oxidiser is potassium chlorate. The proportions of oxidiser and fuel may be varied to produce either hotter or faster combustion. Obviously, the combustion temperature must be high enough to volatilise the dye Preferably, the colouring agent or dye is present in the composition in an amount of between

15 and 40 wt%, preferably between 20 and 35 wt%, optionally in the region of 30 wt% Advantageously, the colouring agent is a readily volatilisable material, such as an organic pigment or dye The colouring agent may include an ultraviolet fluorescent marker dye, to aid identification at a later date The colouring agent may comprise any one or more of the following : Solvent Red 1 (ortho methoxy-phenyl-azo-beta naphthol) Disperse Red 9 (1-methylamin anthraquinone) Solvent Yellow 33 (2- (2-quinolyl)-1, 3-indandione).

Other dyes, such as smoke blue 180, smoke orange 18, smoke yellow 33 and smoke green 3A, may be included additionally, or substituted for the above.

According to a second aspect of the present invention, there is provided a non-rigid security device, optionally adapted for use in conjunction with a package of bank notes, the device comprising a pyrotechnic composition, ignition means adapted to ignite said pyrotechnic composition, field detection means, motion sensing means and control means adapted to initiate ignition in response to a signal from said motion sensing means, in the continued absence of a signal from said field detection means subsequent to a predetermined delay period after the field detection means ceases to detect a field Said control means may comprise audible alarm means The control means may be adapted to activate said audible alarm means at the same time as initiating said ignition means Alternatively or additionally, the control means may be adapted to activate said audible alarm means, should said field detection means cease to detect a field and said motion sensing means not detect motion subsequent to said predetermined delay period.

Preferably, the control means is adapted to classify and to count successive time intervals of predetermined length as motion intervals or non-motion intervals, according to whether an amount of motion in a respective time interval exceeds a predetermined threshold Advantageously, the control means is adapted to initiate the ignition means only following a first predetermined number of said motion intervals.

The control means may then be adapted to cease counting said time intervals and optionally only to activate said audible alarm means, should it count a second predetermined number of said non-motion intervals before counting said first predetermined number of motion intervals.

Alternatively, the control means may be adapted in such an event to activate said audible alarm means and to continue to count said time intervals, ceasing counting said time intervals only after counting a third predetermined number of non-motion intervals.

The control means may then be adapted instead to initiate the ignition means should it count a fourth predetermined number of motion intervals before counting said third predetermined number of non-motion intervals.

Optionally, the control means may be adapted to be switchable between alternative modes of operation.

Advantageously, said pyrotechnic composition is a non-rigid pyrotechnic composition, optionally substantially as described above in the first aspect of the present invention.

The security device may comprise a non-rigid printed circuit board, to which at least some of said field detection means, said motion sensing means and/or said control means are mounted.

Advantageously, said pyrotechnic composition is moulded to said circuit board so as to cover said field detection means, said motion sensing means and said control means, optionally so as to encapsulate them protectively.

Said field detection means may comprise a receiver for radio frequency electromagnetic waves, optionally Very Low Frequency (VLF) electromagnetic waves.

Said motion sensing means may comprise an accelerometer, preferably a solid-state accelerometer comprising a single integrated circuit chip The accelerometer may be capable of detecting accelerations along at least two orthogonal axes, preferably along three mutually orthogonal axes.

The control means may be adapted to distinguish between different types of signals from the motion sensing means, such as between those corresponding to translational movement and those signals corresponding to vibrational movement The control means may then be adapted to respond only to said signals corresponding to translational movement Advantageously, said ignition means comprise means to transmit ignition through said pyrotechnic composition more rapidly than ignition would propagate spontaneously therethrough.

Optionally, said means to transmit ignition may comprise strips, films or wires of an igniter composition comprising an oxidising material and an oxidisable material.

Said igniter composition may comprise potassium nitrate and metallic silicon.

Strips, films or wires of the igniter composition may be attached to a surface of said pyrotechnic composition. Alternatively, strips or wires of the igniter composition may be incorporated into the bulk of said pyrotechnic composition Preferably, said security device is provided with removable safety means to prevent initiation of said ignition means, such as a pull-tab, which may be removed to arm the security device Optionally, the security device may comprise means such as a light source to display that said ignition means would have been initiated but for the presence of said removable safety means According to a third aspect of the present invention, there is provided a security system, comprising at least one signal transmitter and a security device adapted to be attached to an item to be protected, wherein the signal from said at least one transmitter extends or may be extended to cover substantially the whole of a region within which said item is authorised to be moved, and said security device comprises detection means for said signal, motion sensing means and alarm means, and is adapted to trigger said alarm means should the detection means not detect said signal and the motion sensing means detect motion subsequent to a predetermined delay period after said detection means ceases to detect said signal Preferably, each said at least one signal transmitter is a radio frequency transmitter, optionally a Very Low Frequency (VLF) radio transmitter.

Optionally, there are at least two said signal transmitters, one of which is a master transmitter and the other or the others of which are slave transmitters linked thereto. Alternatively, said at least two signal transmitters are adapted to operate synchronously by means of a predetermined control program common to each Preferably, each said at least one signal transmitter is adapted to emit a signal which may be detected at a range of at least between 2.5 and 7 metres.

Preferably, said alarm means comprises a pyrotechnic composition, adapted to emit smoke, optionally coloured smoke, when ignited, and is optionally the composition described above, which comprises the first aspect of the invention Advantageously, said motion sensing means comprises an accelerometer, optionally a solid state accelerometer comprising a single integrated circuit chip.

Said accelerometer may be capable of detecting accelerations along at least two orthogonal axes, optionally along three mutually orthogonal axes.

Said security device may be adapted to distinguish signals from the motion sensing means corresponding to translational movement from signals from the motion sensing means corresponding to vibrational movement, and to respond only to said signals corresponding to translational motion.

Preferably, said security device, and in particular said detection means, is adapted to operate only for a predetermined period after said motion sensing means has detected motion.

Said item to be protected may comprise a package of bank notes Preferably, said security device is a security device as described in the second aspect of the present invention An embodiment of the first aspect of the invention will now be more particularly described in the following Example : A composition was prepared containing Potassium chlorate powder 25 wt% Lactose powder 16 wt% Anthraquinone dyes 29 wt% Room temperature vulcanisable rubber 23 wt% (Dow Coming 3493) Silicone fluid 50 cstokes (0.00005 m2/s) 4 7 wt% Curing agent (Dow Coming 93) 2.3 wt% The first three components were incorporated into a mixture comprising the room temperature, vulcanisable rubber and the silicone fluid The curing agent was then added and mixed in thoroughly and the resulting composition was allowed to cure at room temperature The resulting composition was passed through rollers to form a flexible sheet.

Strips of an igniter composition (potassium nitrate/metallic silicon) were placed on the sheet, which was again passed through rollers to embed the igniter in the surface of the final flexible sheet. The product is a flexible solid which overcomes the opposite disadvantages of rigidity for canister smokes and leakage for liquid smoke compositions A method of use of the smoke composition described above will now be more particularly described, by way of further example and with reference to the accompanying drawings, in which Figure 1 is a cross-sectional view of a security device embodying the second aspect of the present invention, and Figure 2 is a schematic view of the operation of a security system embodying the third aspect of the present invention Referring now to the drawings, and to Figure 1 in particular, a security device 1, is adapted to be concealed within a package of bank notes and comprises a flexible circuit board 2. bearing components 3 of a control circuit including an accelerometer, radio receiver and computing means The circuit may also include a piezoelectric sounder 4. An electric battery 5 is connected to the control circuit and mounted to the circuit board 2 by connectors 6.

A thin layer of a flexible pyrotechnic composition 7, such as the composition described above and including potassium chlorate, lactose, dye and silicone rubber, is moulded over one surface of the circuit board 2 so as to encapsulate the components 3 and sounder 4. The composition 7 may be provided with indentations 8 to increase the flexibility of the security device 1 as a whole.

Electrical contacts 9 of the battery 5 are connected to a respective initiating charge or squib 10 to cause ignition on command of the control unit. The pyrotechnic composition 7 may be ignited directly by the heat of the squibs 10, as shown, or alternatively it may be set off by strips, wires or films of an igniter composition, such as a potassium nitrate/silicon composition, optionally including charcoal, which may be in intimate contact with either the surface of or within the bulk of the layer of pyrotechnic composition 7. Such an igniter composition may be set off by the squibs 10 and burns particularly quickly, propagating the ignition of the pyrotechnic composition 7 more rapidly than an ignition front travelling spontaneously through the pyrotechnic composition 7.

The security device 1 is dimensioned to be concealable between two notes or within a cut-out made in the centre of a small stack of bank notes, so that said notes or the stack may be placed within a thicker package or bundle of bank notes to conceal the device 1 The flexibility of the security device I renders it far less likely to be discovered by a malefactor than if it were rigid. The security device 1 is as thin as possible, to increase its flexibility and to reduce the number of bank notes that are required to conceal it. Ideally, it is less than three millimetres thick (the vertical scale of Figure I is exaggerated for clarity). To fit within the area of a f20 bank note (148mm x 80mm) or a no bank note (142mm x 75mm), the security device 1 should be no more than 129mm x 53mm in area.

The use of the flexible pyrotechnic composition described above allows the composition to be moulded around the components of the control circuit, allowing the security device as a whole to be made thinner as a result. By encapsulating the components, it also serves to conceal them from tampering and protects them from inadvertent damage. A non-flexible composition, such as one cast around the components in liquid form and then allowed to set solid, would not allow any flexibility in the final security device Figure 3 shows a security system adapted to operate with security devices 1, 11, 21 as described above An array of a master transmitter 12 and two slave transmitters 13, powered by a power source 14, is arranged such that the extent 15 of their transmissions (preferably VLF radio waves) completely covers a zone to be made"safe"Such a zone may be, for example, the interior of a bank, or the interior of a security van The number and arrangement of slave transmitters 13 may be altered to correspond to the configuration of the zone in question The serial master slave array shown here has the advantage of ensuring synchronisation of signals from each transmitter 12, 13 In operation, the transmitters 12,13 emit signals which are picked up by a receiver within the control circuit of the security device 1, as long as it remains within the extent 15 of the transmissions from at least one transmitter 12,13. The control circuit of the security device 1 also comprises an accelerometer chip as a motion sensor To extend battery life, the receiver and the remainder of the control circuit are only activated when the motion detector detects movement of the security device 1. Alternatively, the receiver may be turned on periodically with a timer The motion sensor may only be switched on when there is a loss of signal.

Should the security device I be moved past a point 11 at the limit of the extent 15 of the transmissions, so that the receiver no longer receives transmissions from the transmitters 12,13, the control circuit responds by starting a countdown timer. The duration of this countdown may be pre-selected, for example by selection between one, ten, twenty, thirty or forty seconds. If the security device 11 is returned within the extent 15 of the transmissions before expiry of the countdown, the countdown is cancelled and the control circuit is reset If, however, the security device is at a position 21 beyond the extent 15 of the transmissions at the expiry of the countdown, two responses may occur If the motion sensor detects no motion consistent with the security device (and the package of bank notes containing it) being taken away, the control circuit activates the sounder 4, to alert authorised staff that the security device I is outside the"safe"zone and, for example, to retrieve an abandoned package If the motion sensor detects motion consistent with a theft in progress, such as motion consistent with a person carrying the security device 1, walking, running or driving away, the control circuit commands the battery 5 to set off the pyrotechnic composition 7 as described above. Thick clouds of coloured smoke are generated; staining the money, alerting all present to the theft, marking the position of the thief and hampering his escape. The sounder 4 may also be activated to add to the alarm.

This method of operation ensures that a package of bank notes containing such a security device may be freely moved within the"safe"zone, and may even be removed briefly therefrom (presumably inadvertently) without triggering the pyrotechnic composition unnecessarily, as might occur with a simple triggering mechanism based only on the device passing out of the extent of the radio transmissions.

The use of a motion sensor may permit the control circuit of a security device to operate only when required, extending battery life. More importantly, it permits discrimination between situations in which the package has been dropped, so no pyrotechnics are required, and those in which the package is still being removed, and a full response from the security device is required The use of an accelerometer, particularly one in the form of a solid state chip, as the motion sensor provides an added advantage that, with only limited processing power in the control circuit, vibrations from nearby equipment, vehicles, loud noises and the like can be distinguished from actual translational movement of the security device Thus, the security device only responds to genuine motion and is not prone to false alarms It would also be possible to provide memory means in the control circuit, and to programme the memory with patterns of movement which may be expected during normal (legal) transfers of money, and hence of the device, and patterns of movement which could be associated with unlawful movement of money, and hence of the device. Movement of the device, as detected by the accelerometer, may be compared to the pre-entered patterns and a judgement reached as to whether the movement is likely to be proper or not.

In a particularly useful embodiment of the method, the control circuit has two selectable modes of operation. In either mode, the control circuit divides the motion data received from the motion sensor into packets corresponding to successive two-second intervals following the expiry of the countdown. By referring to a predetermined threshold level, the control circuit classifies each interval as a Motion Interval or a Non-Motion Interval, depending on the quantity and/or quality of translational motion registered in that interval. Vibrational movement may be discriminated and classified as non-motion for these purposes.

In a first, or"Raid Protection"mode, the control circuit counts the number of Non-Motion Intervals registered and, when a predetermined number (such as two or three) is reached, it enters "Safe Mode" In "Safe Mode", the control circuit activates the sounder 4, alerting authorised staff that the security device is outside the"safe"zone, but is not being removed any farther However, should the control circuit count a predetermined number of consecutive or non-consecutive Motion Intervals before entering"Safe Mode", it instead causes the pyrotechnic composition 7 to be set off, as described above.

In a second, or"Raid and Safe Protection"mode, the control circuit operates as described for the"Raid Protection"mode, except that"Safe Mode"is replaced by"Warning Alert Mode" In"Warning Alert Mode", the control circuit activates the sounder 4, as in"Safe Mode", although with a recognisably different pattern of sounds (such as a more rapid series of beeps). In contradistinction to"Safe Mode"while in"Warning Alert Mode", the control circuit continues to count Motion Intervals and Non-Motion Intervals. When it reaches a predetermined large number of Non-Motion Intervals (for example 150 such intervals), the control circuit enters"Safe Mode"as described above. However, if before that point it reaches another predetermined large number of (not necessarily consecutive) Motion Intervals, for example 24 such intervals, it instead causes the pyrotechnic composition 7 to be set off as described above. Hence, the package may be protected when contained in a safe which is being removed, in its entirety, but necessarily at a slow rate.

The"Raid and Safe Protection Mode"also allows an abandoned package to be safely retrieved and returned to the"safe"zone by authorised personnel. Meanwhile, it cannot inconsequentially be picked up and taken away by the thief or any other person.

A switch may be provided to select either"Raid Protection"mode or"Raid and Safe Protection"mode As may be seen, the smoke composition of the invention is easier to manufacture and form into a desired shape As in the Example given, it may be rolled into a flexible sheet Alternatively, it may be formed around an igniter insert or it may be moulded into any shape either for concealment, to maximise the amount of smoke production from small volume spaces or to minimise the size of a security device. Furthermore, it is easier to cause ignition since, being a solid, the ignition composition may be embedded in its surface or even within the product or the surface of the product may be coated with igniter Since the composition is mouldable around the electronic components, the alarm device as a whole is flexible and may more easily be concealed within a bank note package Furthermore, it is a comparatively simple matter to alter the specification to add or change components

Claims (1)

1. CLAIMS I. A non-rigid security device comprising a pyrotechnic composition, ignition means adapted to ignite said pyrotechnic composition, field detection means, motion sensing means and control means adapted to initiate ignition in response to a signal from said motion sensing means in the continued absence of a signal from said field detection means subsequent to a predetermined delay period after the field detection means ceases to detect a field.

   2. A non-rigid security device as claimed in claim I, wherein the pyrotechnic composition comprises a colouring agent, a fuel, an oxidiser and a silicone rubber.

   3. A non-rigid security device as claimed in claim 2, wherein the silicone rubber is present in the composition in an amount of between 15 and 35 wt%.

   4. A non-rigid security device as claimed in claim 3, wherein the silicone rubber is present in the composition in an amount of between 20 and 30 wt%.

   5. A non-rigid security device as claimed in either claim 3 or claim 4, wherein the silicone rubber is present in the composition in an amount in the region of 30 wt%.

   6. A non-rigid security device as claimed in any one of claims 2 to 5, wherein the silicone rubber is a room temperature vulcanisable silicone.

   7. A non-rigid security device as claimed in any one of claims 2 to 6, further comprising approximately 5wt% of low viscosity silicone fluid. 8. A non-rigid security device as claimed in claim 7. wherein the silicone fluid has a viscosity of about 0.00005 m2/s.

   9. A non-rigid security device as claimed in any one of claims 2 to 8. wherein the fuel is a sugar or other carbohydrate. such as sucrose. fructose, lactose, maltose, corn starch. dextrin or cellulose.

   10. A non-rigid security device as claimed in claim 9. wherein the fuel is lactose.

   11. A non-rigid security device as claimed in any one of claims 2 to 10. wherein the fuel is present in the composition in an amount between 13 and 30wt%.

   12. A non-rigid security device as claimed in claim 11, wherein the fuel is present in the composition in an amount of between 16 and 20wt% 13. A non-rigid security device as claimed in any one of claims 2 to 12, wherein the oxidiser is present in the composition in an amount of between 17 and 30wt%, preferably in the region of 25wt%.

   14. A non-rigid security device as claimed in any one of claims 2 to 13, wherein the oxidiser is a chlorate or perchlorate of an alkali metal such as sodium or potassium, preferably potassium chlorate.

   27. A non-rigid security device as claimed in claim 26, wherein the control means is adapted to activate said audible alarm means and then to continue to count said time intervals, ceasing counting said time intervals only after counting a third predetermined number of non-motion intervals.

   28. A non-rigid security device as claimed in claim 27, wherein the control means is adapted to initiate the ignition means should it count a fourth predetermined number of motion intervals before counting said third predetermined number of non-motion intervals.

   29. A non-rigid security device as claimed in any one of the preceding claims, wherein the control means is adapted to be switchable between alternative modes of operation.

   30. A non-rigid security device as claimed in any one of the preceding claims, comprising a non-rigid printed circuit board, to which at least some of said field detection means, said motion sensing means and/or said control means are mounted.

   31. A non-rigid security device as claimed in claim 30, wherein said pyrotechnic composition is moulded to said circuit board so as to cover said field detection means, said motion sensing means and said control means.

   32. A non-rigid security device as claimed in any one of the preceding claims, wherein said field detection means comprises a receiver for radio frequency electromagnetic waves.

   33. A non-rigid security device as claimed in any one of the preceding claims, wherein I I in any one of said motion sensing means comprises an accelerometer.

   34. A non-rigid security device as claimed in claim 33. wherein the accelerometer is capable of detecting accelerations along at least two orthogonal axes.

   35. A non-rigid security device as claimed in any one of the preceding claims. wherein the control means is adapted to distinguish between different types of signals from the motion sensing means.

   36. A non-rigid security device as claimed in claim 35. wherein the control means is adapted to distinguish between those signals corresponding to translational movement and those signals corresponding to vibrational movement.

   37. A non-rigid security device as claimed in claim 36, wherein the control means is adapted to respond only to said signals corresponding to translational movement.

   38. A non-rigid security device as claimed in any one of the preceding claims, wherein said ignition means comprises means to transmit ignition through said pyrotechnic composition more rapidly than ignition would propagate spontaneously therethrough.

   39. A non-rigid security device as claimed in claim 38, wherein said means to transmit ignition comprises strips, films or wires of an igniter composition.

   40. A non-rigid security device as claimed in claim 39, wherein said igniter composition comprises potassium nitrate and metallic silicon.

   41. A non-rigid security device as claimed in either claim 39 or claim 40, wherein the strips, films or wires of the igniter composition are attached to a surface of said pyrotechnic composition.

   42. A non-rigid security device as claimed in either claim 39 or claim 40, wherein the strips, films or wires of the igniter composition are incorporated into the bulk of said pyrotechnic composition.

   43. A non-rigid security device as claimed in any one of the preceding claims, further provided with safety means to prevent initiation of said ignition means, such as a removable pull-tab, which may be removed to arm the security device.

   44. A non-rigid security device as claimed in claim 43, wherein the security device comprises means, such as a light source, to display that said ignition means would have been initiated but for the presence of said safety means.

   45. A non-rigid security device substantially as described herein with reference to any one of the Figures of the accompanying drawings.

   46. A pyrotechnic composition comprising a colouring agent, a fuel, an oxidiser and a silicone rubber. 47. A pyrotechnic composition as claimed in claim 46. wherein the silicone rubber is present in the composition in an amount of between 15 and 35 wt%. preferably between 20 and 30 t%.

   48. A pyrotechnic composition as claimed in either claim 46 or claim 47, wherein the silicone rubber is a room temperature vulcanisable silicone.

   49. A pyrotechnic composition as claimed in any one of claims 46 to 48. further comprising approximately 5nit% of low viscosity silicone fluid.

   50. A pyrotechnic composition as claimed in claim 49. wherein the silicone fluid has a viscosity in the region of 0. 00005 m2/s.

   51. A pyrotechnic composition as claimed in any one of claims 46 to 50. wherein the fuel is a sugar or other carbohydrate such as sucrose, fructose, lactose, maltose, corn starch, dextrin or cellulose, preferably lactose.

   52. A pyrotechnic composition as claimed in any one of claims 46 to 51, wherein the fuel

   is present in the composition in an amount between 13 and 30wt%. 53. A pyrotechnic composition as claimed in claim 52, wherein the fuel is present in the composition in an amount between 16 and 20wt%.

   54. A pyrotechnic composition as claimed in any one of claims 46 to 53, wherein the oxidiser is present in the composition in an amount between 17 and 30wt%, preferably in the region of25wt%.

   55. A pyrotechnic composition as claimed in any one of claims 46 to 54, wherein the oxidiser is a chlorate or perchlorate of an alkali metal such as sodium or potassium, preferably potassium chlorate.

   56. A pyrotechnic composition as claimed in any one of claims 46 to 55, wherein the colouring agent is present in the composition in an amount between 15 and 40wt%.

   57. A pyrotechnic composition as claimed in claim 56, wherein the colouring agent is present in the composition in an amount between 20 and 35wt%, preferably in the region of 30wt%.

   58. A pyrotechnic composition as claimed in any one of claims 46 to 57, wherein the colouring agent is a readily volatiliseable material, such as an organic pigment or dye.

   59. A pyrotechnic composition as claimed in any one of claims 46 to 58, wherein the colouring agent comprises any one or more of Solvent Red 1 (ortho methoxy-phenyl azo-beta naphthol), Disperse Red 9 (1-methylamin anthraquinone), Solvent Yellow 33 (2- (2-quinolyl)-1, 3- indandione), Smoke Blue 180, Smoke Orange 18, Smoke Yellow 33 and Smoke Green 3A.

   60. A pyrotechnic composition as claimed in any one of claims 46 to 59. wherein the colouring agent includes an ultraviolet fluorescent marker dye.

   61. A pyrotechnic composition substantially as described herein with reference to the Example.

   62. A security system comprising at least one signal transmitter and a security device adapted to be attached to an item to be protected, wherein the signal from said at least one transmitter extends or may be extended to cover substantially the whole of a region within which said item is authorised to be moved. and said security device comprises detection means for said signal, motion sensing means and alarm means. and is adapted to trigger said alarm means should the detection means not detect said signal and the motion sensing means detect motion subsequent to a predetermined delay period after said detection means ceases to detect said signal.

   63. A security system as claimed in claim 62. wherein each said at least one signal transmitter is a radio frequency transmitter.

   64. A security system as claimed in either claim 62 or claim 63. wherein there are at least two said signal transmitters.

   65. A security system as claimed in any one of claims 62 to 64, wherein each said at least one signal transmitter is adapted to emit a signal which may be detected at a range of at least between 2.5 and 7 metres.

   66. A security system as claimed in any one of claims 62 to 65, wherein said alarm means comprises a pyrotechnic composition, adapted to emit smoke, optionally coloured smoke, when ignited.

   67. A security system as claimed in claim 66, wherein the pyrotechnic composition is a composition as claimed in any one of claims 46 to 61.

   68. A security system as claimed in any one of claims 62 to 67, wherein said motion sensing means comprises an accelerometer.

   69. A security system as claimed in claim 68, wherein said accelerometer is capable of detecting accelerations along at least two orthogonal axes.

   70. A security system as claimed in any one of claims 62 to 69, wherein said security device is adapted to distinguish signals from the motion sensing means corresponding to translational movement from signals from the motion sensing means corresponding to vibrational movement, and to respond only to said signals corresponding to translational motion.

   71. A security system as claimed in any one of claims 62 to 70, wherein said security device, and in particular said detection means, is adapted to operate only for a predetermined period after said motion sensing means has detected motion.

   72. A security system as claimed in any one of claims 62 to 71, wherein said item to be protected comprises a package of bank notes. 73. A security system as claimed in any one of claims 62 to 72. wherein said security device is a security device as claimed in any one of claims I to 45.

   74. A security system substantially as described herein with reference to any one of the Figures of the accompanying drawings.

   Patents Act 1977 Search Report under Section 17 Databases searched: UK Patent Office collections, including GB, EP, WO & US patent specifications, in: UK Cl (Ed. T): F3A; E2X Int Cl (Ed. 7) : G08B ; E05G Other: Online : WPI, EPODOC Documents considered to be relevant:

   Category Identity of document and relevant passage Relevant to claims Y EP 0632418A US CURRENCY PROTECTION I at least Y EP 0355404A BRADAVKA tat least Y US 5196828 KENISTON 1 at least Y US 5059949 CAPARONI 1 at least Y US 4975680 FOGLE (see particularly col. 5 lines 16-34) 1 at least

   X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art y Document indicating lack of inventive step if combined P Documentpublished on or after the declared priority date but before the with one or more other documents of same category filing date of this invention.

   E Patent document published on or after, but with priority date earlier & Member of the same patent family than, the filing date of this application