EP0013484A1 - Alarmsystem und Verfahren, das die Entfernung eines Gegenstandes von seinem vorbestimmten Platz meldet - Google Patents

Alarmsystem und Verfahren, das die Entfernung eines Gegenstandes von seinem vorbestimmten Platz meldet Download PDF

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Publication number
EP0013484A1
EP0013484A1 EP79302781A EP79302781A EP0013484A1 EP 0013484 A1 EP0013484 A1 EP 0013484A1 EP 79302781 A EP79302781 A EP 79302781A EP 79302781 A EP79302781 A EP 79302781A EP 0013484 A1 EP0013484 A1 EP 0013484A1
Authority
EP
European Patent Office
Prior art keywords
article
output
change
capacitance
alarm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP79302781A
Other languages
English (en)
French (fr)
Inventor
Groby Warrington Rogers
Stephen Frederick Goggin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAWRENCE SECURITY SERVICES Ltd
Original Assignee
LAWRENCE SECURITY SERVICES Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LAWRENCE SECURITY SERVICES Ltd filed Critical LAWRENCE SECURITY SERVICES Ltd
Publication of EP0013484A1 publication Critical patent/EP0013484A1/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/02—Mechanical actuation
    • G08B13/14—Mechanical actuation by lifting or attempted removal of hand-portable articles
    • G08B13/149—Mechanical actuation by lifting or attempted removal of hand-portable articles with electric, magnetic, capacitive switch actuation
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/26—Electrical actuation by proximity of an intruder causing variation in capacitance or inductance of a circuit

Definitions

  • the invention relates to an alarm system capable of detecting when an article is removed from a predetermined position.
  • each article on an open display has been interconnected in a loop by means of a wire coupled to an alarm.
  • a wire coupled to an alarm Such a system is obtrusive and tends to detract from the display. Adding or removing articles with such a display requires disconnecting the interconnected wires in the loop which can become tedious.
  • the present invention is concerned with a system which overcomes the above drawbacks to provide a reliable, flexible and typically unobtrusive system which can cope with a number of articles together if required.
  • an alarm system for indicating the removal of an article from a predetermined position comprising:
  • a method of detecting and indicating when an article has been removed from a predetermined position comprising:
  • an alarm system for indicating the removal of an article from a predetermined position comprising:
  • a method of detecting and indicating when an article has been removed from a predetermined position comprising:
  • the item or items to be displayed will be positioned such that they will overlie the electrodes 10, 11 which will typically be provided on top of a display stand but not necessarily in the straight configuration indicated.
  • the effective capacitance of the items so placed is indicated by capacitor c.
  • the electrodes 10 and 11 are connected to the sensor 12 which produces en output level indicative of the change in the capacitance c. Any object removed from across the electrodes 10 and 11 will cause a rapid change in capacitance and thus the sensor 12 will detect this change and the output thereof will rise.
  • the output of sensor 12 is received by alarm block 13 which compares the sensor level with a predetermined threshold and effects an alarm condition when the threshold is exceeded.
  • the shelf 1 is provided on its upper face with two metallic electrode strips 10, 11 which are arranged typically in an interleaved pattern so that, irrespective of the position of placing an article 15 on the shelf, the base of the article will overlie the two electrodes 10 and 11.
  • the article is assumed to be metallic, or to incorporate metal at or near its base, or to carry a sticker or tag 5 which is made of or incorporates metal.
  • the strips are advantageously self-adhesive, and may be for example i inch apart, and one-eighth to three- eighths of an inch in width. Thin wire could also be used.
  • the sticker could be a small disc of silver paper, for use in the case of glass, china etc. When the disc is placed over the strips, there is an increase of capacitative bridging of the strips 10 and 11.
  • the two electrode strips in this example are connected by the inner and outer portions of a coaxial cable 4 to the sensor arrangement.
  • the electrodes 10 and 11 are shown on the upper surface of the shelf in contact with the article 15 (or metallic sticker 5), it would also be possible to disguise the electrodes by covering these with a thin dry material (e.g. cloth), and placing the article on the cloth. Alternatively if the shelf were thin it may be possible to provide the electrodes on its lower surface, although in these latter configurations the sensitivity of the system would be somewhat reduced.
  • a thin dry material e.g. cloth
  • FIG. 3 An arrangement for realising the system of Figure 1 is shown in Figure 3.
  • the electrodes 10 and 11 are shown interleaved by way of example and suitable positions for a number of articles 15 - 18 are shown thereon.
  • the electrodes are connected via cable 4 to points A and Bo
  • the sensor 12 consists of a high impedance oscillator employing a field effect transistor (FET) TR1 (e.g. 2N3819).
  • FET field effect transistor
  • Components associated with the oscillator include inductance T 1 , capacitors C 1 , C 2 , C 3 and C 5 and resistors R 1 and R 2 .
  • the circuit is arranged to go into, and out of, oscillation by the change of capacity occurring between the strips.
  • the setting of the oscillator is controlled by the variable capacitor C1 in the gate circuit of the FET, and which is affected by the loading of the shelf; when the shelf is loaded with articles, the capacitor C 1 is adjusted so that the oscillator is just not oscillating, When an article is removed from the shelf, the capacity at the shelf decreases, and allows the oscillator to start working.
  • the output of the oscillator is typically selected to be at R.F. frequency, e.g. 450-470 Kcs., and this output is passed via capacitor C 4 to the amplifier comprised of transistor TR2 with associated resistors R 3 and R 4 .
  • the output from this transistor passes via capacitor C 6 and is rectified by the diode Dl, and the DC content is fed to the driving circuit comprising power transistor TR3 and associated resistor R 5 and capacitor C 7 which circuit actuates the relay circuit (RL 1 and C 8 ) when this DC level exceeds a predetermined threshold.
  • the contacts of the relay are used to switch on any convenient alarm system shown here as a bell 6 powered by battery B l .
  • the oscillator radiates only micro-watts, and only does so when an article is removed.
  • the oscillator is not in a state of oscillation, when everything is normal at the shelf. When in this normal state, the supply current used by the equipment is very low.
  • the maximum current is used when an article is removed from the shelf, and tnis current mainly consists of that which is consumed by the power transistor and the relay used.
  • the oscillator circuit and the relay could be miniaturised and encapsulated.
  • the relay although shown as an electro-mechanical device, this could alternatively comprise a solid state switch.
  • the device When the alarm or indicator means installed at a point remote from the shelf, e.g. at a supervisory post or assistant's location in a shop, the device provides an automatic safeguard against unobserved removal of articles, and moreover dependent on the type of alarm (i.e. visual or audible) can give notification of an alarm condition without giving any indication of that fact to the person removing the article.
  • the type of alarm i.e. visual or audible
  • the placing of the electrodes as a pair in close proximity to each other and over which the article is placed so as to bridge the electrodes ensures that stray capacitance effects due to customers or assistants moving in the vicinity of the display are minimised and thus reduce the possibility of false alarm conditions.
  • the system has been described generally for use with an 'article' comprising an object for display, the system is also capable of detecting the movement of other 'articles' away from a predetermined position for example such as in opening of a door or window, a face of which could be provided with a metallic strip for example in the vicinity of the electrodes and any movement thereof causing actuation of the alarm.
  • electrodes 10 and 11 could again be coupled via coaxial cable to the sensor 12.
  • Oscillator 20 is a free running oscillator (typically 200 kHz).
  • the oscillator output is received by buffer 22 to prevent loading of the oscillator.
  • a filter 21 is provided to remove any r.f. present.
  • the buffered oscillator output passes via pulse shaper 24 to a phase locked loop configuration provided by blocks 26 - 29 inclusive.
  • the shaped pulses are received by the first comparator 26 which produces an error voltage which passes via low pass filter 27 to control the oscillator 28.
  • the output of the voltage controlled oscillator (VCO) is used as the other input to comparator 26 so as to allow this comparator to determine the error and adjust the error voltage.
  • comparator 29 receives the pulses from shnper 24 and the output from VCO 28, so as to again produce an error voltage.
  • This error voltage passes via driver 30 to an integrator 31 where it is integrated.
  • the integrator output is received by alarm trip unit 13 which instigates an alarm condition when this output exceeds a predetermined level.
  • the low pass filter 27 effectively determines the rate at which a change in capacitance c affecting oscillator 20 will cause the VCO to come out of lock and so cause the error voltage at the output of comparator 29 to continuously change as the VCO is searching for a locked situation. Thus this comparator output on integration will effectively cause the alarm to actuate.
  • the low pass filter 27 and integrator 31 provide the facility for determining the rate of change rather than change per se in capacitance c.
  • the oscillator 20 comprises coil L 1 (e.g. a standard I.F. coil), resistors R 1 -R 3 , capacitors C 1 , C 2 and integrated circuit element 40.
  • C 8 is a decoupling capacitor.
  • Filter 21 comprises R 4 and C 3 .
  • Buffer 22 comprises C 4 , R5 and element 41.
  • Pulse shaper 24 comprises R 12 and element 46.
  • Driver 30 comprises elements 47, 50, 51 and resistor R 9 .
  • Integrator 31 Comprises element 52, R10, Rll, C 7 and diode D1.
  • the phase locked loop 26 - 29 comprises integrated circuit chip 44 and associated components R 6 -R 8 , C 5 ,C 6 and relay contact AI.
  • the alarm trip 13 comprises elements 42, 43 , 48 , 49, resistors R13, R14, diodes D 2 , D 3 , light emitting diode 56, relay A and loudspeaker 55 (e.g. Piezo transducer U35R). Elements 42 and 43 operate in parallel to provide the necessary current handling capability due to the relatively low value of R13.
  • Elements 40 - 43 can conveniently comprise 4 dual input Rand gates on a single chip (e.g. type 4011). The inputs of each of these elements 40 - 43 are strapped together so that each functions as an inverter.
  • Chip 44 is a phase locked loop chip (e.g. type 4046).
  • Elements 46 - 49 can typically comprise 4 Schmitt triggers on a single chip (e.g. type 4093).
  • Elements 50 - 52 can conveniently comprise 3 out of 4 of the Nand gates of an I.C. chip (e.g. type 4011), each with inputs strapped to function as inverters. It is convenient to use NANDs since these are also used elsewhere although a normal inverter chip could be used.
  • I.C. chip e.g. type 4011
  • the output from the integrator is normally low.
  • C 7 charges up and the elements 42, 43 go low (when C 7 reaches about 1/2 rail voltage).
  • the Schmitts 48, 49 positively select the alarm condition causing the transducer 55 to operate.
  • the relay A is also energised and contact A 1 closes and thus R 8 is placed in parallel.with R 7 to relock the phase locked loop more quickly, (R 7 and C 6 forming the low pass filter). C 5 and R 6 define the center frequency of the VCO.
  • the oscillator is free running whether or not an alarm condition is occuring. Any slight changes in capacitance will cause the oscillator frequency to vary but this variation can be followed by the phase locked loop system. A rapid capacitance change however will cause the loop error to become large and thus on integration cause an alarm condition to be instigated.
  • the system will automatically relock into a standby condition on de-energisation of relay A. This locking into a standby condition will also occur automatically a short time after articles have been placed on the electrodes when making up the display and thus typically no manual adjustment or setting up of the system is required, other than initially arranging the electrodes in a suitable configuration.
  • this system has been generally described as for use with an article comprising an object for display, this system can also be used with 'articles' such as doors or windows which typically cculd be provided on one face with a metallic strip in the vicinity of the electrodes to allow any movement of the door or window by opening to be detected and an alarm condition actuated.
  • 'articles' such as doors or windows which typically cculd be provided on one face with a metallic strip in the vicinity of the electrodes to allow any movement of the door or window by opening to be detected and an alarm condition actuated.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)
EP79302781A 1978-12-08 1979-12-04 Alarmsystem und Verfahren, das die Entfernung eines Gegenstandes von seinem vorbestimmten Platz meldet Withdrawn EP0013484A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB4772478 1978-12-08
GB7847724 1978-12-08
GB7929297 1979-08-22
GB7929297 1979-08-22

Publications (1)

Publication Number Publication Date
EP0013484A1 true EP0013484A1 (de) 1980-07-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP79302781A Withdrawn EP0013484A1 (de) 1978-12-08 1979-12-04 Alarmsystem und Verfahren, das die Entfernung eines Gegenstandes von seinem vorbestimmten Platz meldet

Country Status (2)

Country Link
EP (1) EP0013484A1 (de)
AU (1) AU5341879A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205950A (en) * 1987-04-24 1988-12-21 Coleman Electronic Designs Ltd Capacitive proximity sensor
EP0989671A2 (de) * 1998-09-28 2000-03-29 Omron Corporation Berührungssensor zur Identifizierung eines Körperteils
CN112758573A (zh) * 2020-12-15 2021-05-07 湖南红太阳光电科技有限公司 一种移动货架用定位耦合装置、移动货架及传料系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103164875B (zh) * 2011-12-08 2016-03-30 北京北大千方科技有限公司 车载设备

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1808250U (de) * 1959-07-28 1960-03-17 Telefonbau & Normalzeit Gmbh Vorrichtung an tischen zur sicherung von daraufliegenden gegenstaenden.
DE1121507B (de) * 1960-06-03 1962-01-04 Siemens Ag Schaltungsanordnung zur Sicherung gegen Diebstahl
DE2323065A1 (de) * 1973-05-08 1974-11-28 Werner Cordes Regalfachboden
US3919705A (en) * 1973-02-05 1975-11-11 Joseph L Stendig Loop cord alarm system
US4091371A (en) * 1976-07-28 1978-05-23 Simco, Inc. Touch-responsive portable intrusion alarm

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1808250U (de) * 1959-07-28 1960-03-17 Telefonbau & Normalzeit Gmbh Vorrichtung an tischen zur sicherung von daraufliegenden gegenstaenden.
DE1121507B (de) * 1960-06-03 1962-01-04 Siemens Ag Schaltungsanordnung zur Sicherung gegen Diebstahl
US3919705A (en) * 1973-02-05 1975-11-11 Joseph L Stendig Loop cord alarm system
DE2323065A1 (de) * 1973-05-08 1974-11-28 Werner Cordes Regalfachboden
US4091371A (en) * 1976-07-28 1978-05-23 Simco, Inc. Touch-responsive portable intrusion alarm

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205950A (en) * 1987-04-24 1988-12-21 Coleman Electronic Designs Ltd Capacitive proximity sensor
EP0989671A2 (de) * 1998-09-28 2000-03-29 Omron Corporation Berührungssensor zur Identifizierung eines Körperteils
EP0989671A3 (de) * 1998-09-28 2005-04-20 Omron Healthcare Co., Ltd. Berührungssensor zur Identifizierung eines Körperteils
CN112758573A (zh) * 2020-12-15 2021-05-07 湖南红太阳光电科技有限公司 一种移动货架用定位耦合装置、移动货架及传料系统

Also Published As

Publication number Publication date
AU5341879A (en) 1980-06-12

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Effective date: 19810430

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Inventor name: GOGGIN, STEPHEN FREDERICK

Inventor name: ROGERS, GROBY WARRINGTON