LU82424A1 - SECURITY ALARM SYSTEMS - Google Patents

Description

V.346.049 DB.33. £ 56 2.4332 ow

-0 2 4— TT ”GRAND-DUCHY OF LUXEMBOURG

Patent No ............................................... ...

. May 7, 1980 / HFlbni ,,.

of ................................................. .................. Minister

GtvSeïi of the National Economy and the Middle Classes

Title issued: ...................................... 3¾ vft

LUXEMBOURG Industrial Property Service

Application for invention patent I. Reauête

The British company known as: Chubb Electronics Limited, (1). 42-50 Hershan Road, Walton-on-Thames, Surrey KT Ï2 1 RY, ~ Gr ^ dë-Bretagne, represented by Mr Charles München, patent attorney in Luxembourg, acting as attorney Ään. „Seit mai 1900 eighty 15 Q ^ | Installation— ............. · - · .................... ............................. ~ .................... ..................... "· —.......................... ............................................. (3) to. ................... * ....... hours, at the Ministry of National Economy and the Middle Classes, in Luxembourg: 1. this request for obtaining a patent for an invention concerning: rs5? s * têïnëFdrrârTa1 ^ 3ê s & curTtë - “^ ........................... ........ (4>

Good 1 Âfflfr, ¾¾¾ t * "*>:„

Have ari o, Canada ............................................. .................................................. .................................................. .................................................

.................................................. .................................................. ..................................... WäTtoh-öh-Thämes ........ .......... '2'8 ..... April ...... 1980 2. the delegation of power, dat ^, d ^ .ç.g. ^ .. gg .. ............................................... the .. .................................................. ....................

3. description in language ............................................ ........................................ of the invention in two copies: 4. .... Un.î .............. drawing boards, in two copies; 5. the receipt of the taxes paid to the Luxembourg Registration Office,. May 7, 1980 .............................................. .................................................. .................................................. .................................................. .................................................. ................................

claims for the above patent application the priority of one (s) request (s) of '(6) ...................... DD ... .................................................. ......... filed in (7) ................................. ....... LL, ......................................... ..............................................

the ................................................. LL ................................................. .................................................. .................................................. .................................................. ........ (8) in the name of .................................... ......................... LL ........................ .................................................. .................................................. .................................................. ..... (9) take up residence for him / her and, if designated, for their proxy, in Luxembourg ........................ ................

lia, boulevard Prince-Henri (10) is requesting the grant of a patent for Vobjj. described and represented in the abovementioned appendices, - with / addition of this issue to .................................. ..............month.

The / ^^ [datai II. Deposit Minutes

The above application for a patent for invention has been filed with the Ministry of National Economy and the Middle Classes, Industrial Property Service in Luxembourg, dated: May 7, 1980 15 QQ .......... Fr. the Minister at ................. * ............ hours / \ of the National Economy and the Middle Classes,

Go0) A 68007 i, * 2.4332 b

DESCRIPTION MEMORY filed in support of a request for; PATENT

j in the Grand Duchy of LUXEMBOURG

on behalf of Chubb Electronics Limited for: "Security Alarm Systems".

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i 2 "Security alarm systems"

The present invention relates to security alarm systems of the kind in which a detector assembly intended to detect an alarm state at a first location is connected by a signaling path to alarm control means. in a second location, and the alarm control means are put into action in response to signal variations occurring in the aforementioned route in *. following detection of the alarm state by the detector assembly or interference with the signaling path.

A detector assembly used in a security alarm system of the above kind may involve one or more electrical switches or other devices for establishing or breaking an electrical circuit in response to an intrusion into an area or for an article to be protected, or may be of the type of equipment which detects, for example, ultrasonic or microwave disturbances, in order to generate or interrupt an electrical signal in response to the alarm state. Whatever the form of detector assembly 20 used, the existence of the alarm state is conventionally signaled to the alarm control means, which can be located in the vicinity of the detector assembly or at a large distance therefrom, by the transmission or interruption of an electrical signal in one or more electrical signaling conductors extending from the detector assembly. However, such conductors or cables are vulnerable to attack or other interference that could endanger the security of the system. More particularly, the conductors can be cut or derived.

30 Although it is relatively simple to provide that a variation in impedance of the signaling path resulting from an action of naked bypass cut-off, causes a variation of signal making it possible to activate the alarm control means, such action can generally go unnoticed if interference techniques to eliminate the occurrence of such variations are adopted. Particularly, / especially, for a system in which the alarm state is so- / f \ jt l · w u 3 I '!! f

Li 1 A çnalé by the interruption of a signal, the operation; venable - can be eliminated by a concealed introduction; in the signaling path of a reproduction of the

Normal ignal, intended to be received by the alarm control means. Although coded signaling, for example involving pseudo-erratic digital sequences, can be used to improve security from this point of view, this is normally expensive and unacceptable from an economic point of view for short distance operation.

An object of the present invention is to provide a security alarm system in which security concerning the signaling route can be obtained easily and relatively inexpensively.

According to the present invention, there is provided a security alarm system in which a detection assembly! a detector intended to detect an alarm state at a first location is connected by a signaling path to alarm control means at a second location, and alarm control means are activated by rejj 20 responds to signal variations occurring in the route; i] following the detection of the alarm state by the detector set or interference with the signaling route, with for characteristic that the course of signa-. reading is a fiber optic light guide and a | 25 light signal is transmitted from the detector assembly to the alarm control means in the light guide.

The use of a fiber optic light guide as a signaling route is advantageous | geuse in the sense that it is difficult to intervene in a j 30 such course without affecting the light signal transmitted to by shooting the detector assembly. In particular, it is very difficult to cut the optical fibers to establish a branch or a signal injection point, without appreciably attenuating the transmitted light even when the section of fibers to be cut is first bridged. . Such interference can therefore be easily detected at the location of the alarm control means by monitoring the light intensity of the signal received from the light guide. The difficulty of determining the nature of the normal signal and of introducing a reproduction thereof into the signaling path is further increased if the light signal transmitted from the detector assembly is modulated and a or more of the modulation parameters are controlled in the alarm control means.

Complex modulation is generally unnecessary and the modulated light signal can be generated using a 10-pulse electrical circuit or other oscillator circuit which provides its output signal for driving a light emitting diode or other device, up to alarm condition is detected. The necessary control of the signal modulated by the alarm control means can also be carried out simply by integrating with respect to time a signal derived as a function of the light output of the light guide and responding to a deviation from the integrated signal. with respect to predetermined limits.

A single fiber light guide can be used, but safety is improved if a fiber bundle is used, especially because different fibers can carry different signals. From this latter point of view, a particular light signal can be transmitted in one or only some of the optical fibers and the alarm control means can be activated in response to the reception of this light signal or any light, from the other or other optical fibers.

The light guide can in fact comprise two optical fiber sub-beams which are mixed together between the detector assembly and the alarm control means in order to make it difficult to distinguish between the fibers of the different sub-beams at different interference purposes.

A security alarm system according to the present invention will now be described, by way of example, with reference to the accompanying drawing which shows the system in schematic form. /

Referring to the drawing, an enclosure 1 which / ^ / • f * i / * i 1 * 5 i

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\\ Îcan for example be a safe, a vault or another room or article to be protected, is connected to an alarm control assembly 2 inside the enclosure 3, by a fiber light guide flexible optics 4 and by 5 positive and negative power supply lines 5 and 6.

The guide 4 is constituted by a bundle of individual optical fibers divided into two multiple fiber sub-beams 7 and 8. The fibers of the two sub-beams 7 and 8 are mixed together at least on the part of the guide 4 extending 10 between speakers 1 and 3.

The fiber optic guide 4 is coupled inside the enclosure 1 to a detector assembly 9 intended to respond to conditions in which there is an intruder or an attempted intrusion into the enclosure 1 or an action 15 on an associated article (for example a door or a window) or on the assembly 9 proper. The assembly 9 comprises on this subject one or more detectors, which can be active or passive devices, intended to detect the alarm state. A single detector has been illustrated in the present case in the form of a normally open switch 10 which closes in response to the alarm state. The switch 10 is connected in series with a diode 11 in parallel with a capacitor 12 of a relaxation oscillator 13. When the switch 10 remains open, the capacitor 12 is charged and discharged fa-! 25 lessons repeated in the oscillator circuit. The capacitor 12 | is charged during each oscillation cycle via a resistor 14 and then discharges into a resistor 15 via a unijunction transistor 116, when the voltage of the capacitor reaches a predetermined value; the fixed value is a function of the value of! , resistor 15 connected to a base of transistor 16 and t the value of a resistor 17 connected to its other base. The pulse train generated at the terminals of resistor 15 I of oscillator 13 is applied via a resistor 18 to the base electrode of a transistor 19 connected in a circuit configuration ground transmitter. / The collector load of transistor 19 comprises a light emitting diode / u 6 (LED) 20, which is connected in series with a current limiting resistor 21 and which emits light pulses as a function of the output pulses of oscillator 13 .

5 The diode 20 is optically coupled to the end of the fiber sub-bundle 7 inside the assembly 9, while the end of the sub-bundle 8 is shielded (or otherwise arranged) from so as to prevent light coming from the diode 20 or from any other source from penetrating into the fibers of the sub-beam 8. Thus, the light pulses emitted by the diode 20 are transmitted along the length of the guide 4 from the detector assembly 9 to the alarm control assembly 2 inside the enclosure 3, via the individual fibers of the sub-beam 7 only. No light is transmitted from the assembly 9 into the fibers of the sub-beam 8.

The two sub-beams 7 and 8 are optically coupled inside the assembly 2 to phototransis-tors 22 and 23, respectively. These transistors 22 and 23 are connected in set 2 in individual discharge paths of a capacitor 24 which is charged via a variable resistor 25 and a resistor 26 in series. The voltage across the capacitor 24 is compared * by two comparators 27 and 28 to respective upper and lower voltage levels established in a voltage divider chain formed by three resistors 29, 30 and 31. The outputs of the comparators 27 and 28 are connected via respective diodes 32 and 33 to a common line 34. The two diodes 32 and 33 are non-conductive when the voltage at capacitor 24 remains within the small range defined between the upper and lower levels of comparison. However, if the voltage across the capacitor 24 rises above the upper comparison level, the response of the comparator 27 causes the diode 32 to become conductive, tan-35 say that if the voltage drops below the level of lower comparison, the response of the comparator 28 in this case causes the diode 33 to become conductive. In both circumstances- / j, /, /! . In these cases, the conduction of the diode 32 or 33 concerned draws a current via a resistor 35 to reduce the potential of the common line 34. This reduction in potential is signaled to the alarm equipment. 36 which is used to execute appropriate alarm processes and actions in response to such potential reduction. i However, under normal conditions, i - i j light pulses are regularly received from | \ sub-beam 7 by the phötotransistor 22 and no light j! 10 is received by the phototransistor 23 from the under-do! · J ceau 8, a discharge and a partial charge alterné® of the condenser 24 taking place by means of the resistor 26. During each pulse of light coming from the sub-beam 7, the transistor 22 flows to discharge the conden - 15 sator 24, while during the intervals between the light pulses, the transistor 22 is not conductive, thus allowing the capacitor 24 to recharge. Under normal conditions where the transistor 22 is alternately conductive and non-conductive in synchronism with the pulsed si-20 generated by the oscillator 13 and where the transistor 23 remains non-conductive, the voltage across the condensa! tor 24 varies within the admissible range defined for comparators 27 and 28. The two diodes 32 and 33 therefore remain non-conductive and the potential of the common line 25 34 is high, so that no alarm is given. by equipment 36.

A variation in duration or frequency of the light pulses received from the sub-beam 7; causes the voltage across the capacitor 24 to deviate • e 30 from the permissible range, so that one or the other of the diodes 32 and 33 becomes conductive to reduce the potential of the line 34 and therefore actuate the alarm equipment 36. The same result will come from any appreciable variation in the intensity of the light pulses 35 received, since this will affect the current flow through the transistor 22 and therefore the amplitude of / “· '- “1—“ · "“ v 8 tioned in the case where the train of light pulses is interrupted, case where the charge of the capacitor 24 continues without interruption so that the higher level of comparison is exceeded. if any light is received by the transistor 23 to make it conductive, the capacitor 24 is in fact short-circuited and the response of the comparator 28 with the resulting conduction from the diode 33, activates the alarm equipment 36. The latter will be activated "in these circumstances despite that regular light pulses 10 are received by the transistor 22.

The train of light pulses received by the transistor 22 is interrupted, which activates the assembly 2 to activate the equipment 36, each time that the alarm state is detected by closing the switch 10 15 in the detector assembly 9. The closing of the switch lo short-circuits the capacitor 12, so that the oscillation of the oscillator 13 ceases and that light pulses are no longer emitted in the sub-beam 7 of the guide 4 However, while the switch 10 is open and light pulses are emitted in the sub-beam 7, interference with the guide 4 will also activate the assembly 2 with the same result. More particularly, one or more of the parameters of the pulse train. light ions, namely the intensity, duration and frequency of the pulses, will generally be affected by the interference with the fibers of the guide beam η 4. A cut, a bypass and a bridging and possibly even a stress of the fibers will generally affect at least the intensity of the light. Likewise, when a substitution of the pulsed signal is attempted, a very precise reproduction of all these parameters, for the injected signal, is required if an activation of the alarm control unit 2 is to be avoided. There is also the difficulty of distinguishing the fibers of the sub-beam 7 from those of the sub-beam 8; The fibers of these two sub-bundles are mixed together between the enclosures 1 and 3 and the injection of the replacement / signal or of any light, into one of them; · 9! conch fibers of the sub-bundles 8 will in itself activate the assembly 2. Thus, a very high degree of security of; signaling route is reached in a simple and relatively inexpensive way.

5 Various modifications to the system described can be made. In particular, if a lower degree of security is tolerable, the light signal transmitted from the detector assembly may be continuous rather than modulated by pulses and, in this case, the alarm control assembly will be activated only in response to an interruption or other change in intensity. From the same point of view, the optical fiber sub-bundles 7 and 8 can be reduced to single fibers and in fact the sub-beam 8 could be eliminated. Regardless of the simplification question, other forms of modulation can be adopted and other detector and alarm control sets can be incorporated into the system. From this latter point of view, the diodes 37 and 38 of another control assembly corresponding to the assembly 2, connected to the common line 34 just like the diodes 32 and 33, have been illustrated in the drawing.

The use of an oscillator such as oscillator 13 in the detector assembly can be avoided in advance. seeing that a modulated light signal generated in the alarm control assembly 25 is transmitted via another optical fiber sub-bundle (which can also be mixed with those of sub-bundle 7) to the i | detector, to return via the sub-beam 7 in the absence of the alert state. The return of the signal 30 received from the control assembly can be achieved by transforming it inside the detector assembly into an electrical signal which, as long as the alert state is absent, is applied for modulate the light output / of a light-emitting diode corresponding to diode 2CK / 35 of assembly 9. i fi

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Claims (10)

1. Security alarm system, in which a detector assembly intended to detect an alarm state at a first location is connected by a signaling path to alarm control means at a second location, and the alarm control means are activated in response to variations in signal occurring in this path due to the detection of the alarm state by the detector assembly or to interference with the signaling path , characterized in that the signaling path is a fiber optic light guide (4), and in that a light signal is transmitted from the detector assembly (9) to the alarm control means ( 2) in the light guide (4). 2. Security alarm system according to claim 1, characterized in that the detector assembly (9) comprises a light emitting device (20) which can be electrically excited to emit a light signal in one end of the light guide ( 4) for a transmission to the alarm control means (2), an electrical circuit (13) intended to supply an electrical signal to excite the light emitting device (20), and one or more detectors of alarm state (lo) coupled to this circuit (13) for interrupting the supply of the excitation signal 25 to the light emitting device (20) in response to the detection of the alarm state, and in that the alarm control means (2) are activated in response to the interruption of reception of the light signal at the other end of the light guide (4). 3. Security alarm system according to either of claims 1 and 2, characterized in that the alarm control means (2) control the light intensity of the signal which they receive from the light guide (4). 35 4. S ^ SièE alarm safety device according to any one of claims 1 to 3, characterized in that / the light signal transmitted by the detector assembly (9) is /// 11 a modulated light signal, and in that that the alarm control means (2) control at least one parameter for modulating the signal they receive from the light guide (4). 5. Security alarm system according to any one of the preceding claims, characterized in that the dlaLarme control means (2) comprise a device (24) for integrating a time derivative signal as a function of light. received from the light guide (4), and means (27,28) responding to a deviation of the integrated signal from 10 predetermined limits. 6. Security alarm system according to any one of the preceding claims, characterized in that the light guide (4) comprises a multiplicity of optical fibers. 7. Security alarm system according to claim 6, characterized in that the detector assembly (9) transmits the aforementioned light signal in one or a few (7) of the optical fibers of the light guide (4), and in that the alarm control means (2) are actuated in response to the reception of this light signal from the other (s) (8) other optical fibers. 8. Security alarm system according to claim 7, characterized in that the light guide (4) comprises two sub-beams (7,8) of optical fibers which are mixed together between the detector assembly (9 ) and the alarm control means (2), and in that the light signal is transmitted only in a first (7) of the two sub-beams (7,8) and the alarm control means (2) control the light output of both the first and second sub-beams (7,8). 9. Security alarm system according to re- j vendication 8, characterized in that the penetration of light | in the second sub-beam (8) is locked to the set of | guard (9), and the alarm control means (2) are activated in response to the reception of light from the second sub-beam (8). / 10. Security alarm system according to / ~ j 12 claim 9, characterized in that the alarm control means (2) comprise first and second light-sensitive devices (22,23) intended to respond electrically to a light output of the first and second 5-beams (7,8), respectively, the first light-sensitive device (22) being connected in the electrical circuit (24,26) to derive an electrical signal having a magnitude function of one or more parameters of the light received by this device (22) from the first sub-beam 10 (7), an electrical control circuit (27,33) for controlling the magnitude of this signal bypass to activate the alarm equipment (36) in response to a deviation of the signal magnitude from a predetermined range, the second light sensitive device (23) being connected to the bypass circuit 15 signal (24-26) to cause the magnitude of the derived signal to deviate from the pl Aforementioned age in response to reception by the second light-sensitive device (23) of light from the second sub-beam (8). 20 L. - ......... ÿ °, j ΛΙ CC ΓΛ ....... Λ ....... e- r. & R.jQ ........ ... '^ ......... g ...... v; - ô u · .- description ......... 3 ...... r. · Pus 6 =., Claim ....... A edregé descriptif I Ί- ίτ »νβΛ- Lu '/ emt-VV V / V ί, /, !! “,;' Hiifi