WO1990003623A1

WO1990003623A1 - System for verification of de-activation of anti-theft markers

Info

Publication number: WO1990003623A1
Application number: PCT/GB1989/001168
Authority: WO
Inventors: Dafydd Geraint Davies
Original assignee: Scientific Generics Limited
Priority date: 1988-09-30
Filing date: 1989-10-02
Publication date: 1990-04-05
Also published as: GB8822932D0; AU4483189A

Abstract

A verification system is disclosed which in one embodiment comprises a magnetic flux detector located close to the magnetising element of an anti-theft marker deactivator so as to detect a rapid change in magnetic flux when an anti-theft marker is subjected to the magnetising force of the magnetising element of said deactivator. An electronic article surveillance system incorporating such a system together with deactivators and an interrogation gate is also disclosed.

Description

SYSTEM FOR VERIFICATION OF DE-ACTIVATION OF ANTI-THEFT

MARKERS This invention relates to anti-theft or electronic article surveillance (EAS) systems. These systems are r- commonly used in retail outlets for consumer goods, to prevent shoplifting and theft of the goods. Many EAS systems use markers which are attached to the goods, but which are removed at the time of purchase by the operator. However, in EAS systems today there is an

10 increasing desire to attach inexpensive, disposable markers to the goods, which are not removed but de-activated by some means at the point of sale. If the marker is de-activated it can pass through the controlled or "interrogation" region without triggering an alarm in

15 the EAS system. However, if the marker is not de-activated, but left in its normal active condition (as when the goods are being stolen) , then it is sensed in the interrogation region by the EAS system, and sets off an alarm.

20 A problem of considerable concern to the operator of the system (usually the retailer) is that markers attached to legitimately-bought goods may be incompletely or incorrectly deactivated at the point of sale (often due to the operator's incorrect use of the deactivation _-. system). This will result in unwanted alarms which cause extreme embarrassment and annoyance to both the retailer and the purchaser, and which can result in legal proceedings or a loss of business to the retailer. In order to overcome this problem, this invention proposes _n the use of systems for point-of-sale (POS) verification that correct deactivation has occurred. The commercial value of such systems is obvious.

The value of deactivation verification (DV) systems can also be seen from the following. There is an

„ increasing wish to move from EAS systems with multiple interrogation regions, each are situated close to a POS such that purchased goods can be passed outside the interrogation volume by the operator (avoiding alarms from incorrectly deactivated markers), to systems where there is a single large interrogation region at the exit of the premises through which all goods must pass. Under these circumstances POS verification is particularly important.

According to various aspects of this invention, the DV system may function either by detecting the operation of the deactivation apparatus, or by detecting the process of the change of state of the marker, or by detecting an active marker immediately after (in time or space) the deactivation is meant to have taken place. The latter is the safest option.

In the sense that the EAS system and the DV system may both detect active markers, they might be considered in some cases to be functionally similar devices. This is not the case, however, since the requirements and constraints upon the two systems are very different.

The EAS system should have a large interrogation volume through which a person may walk. Also it must have a vanishingly small likelihood of falsely detecting everyday objects (such as eys, tin cans etc) as markers, while it need not detect actual active markers with very high efficiency since a correct detection probability of only about 2 out of every 3 markers attached to stolen goods will most probably indicate a thief of multiple goods or in any case deter a prospective thief of a single item. The large volume and the very high rejection of false alarms means that the EAS system is usually expensive.

The DV system need only have a small interrogation volume through which legitimately purchased goods are passed. It must detect all active markers, with very close to 100% efficiency, since none must be allowed to pass through and trigger the EAS system. This high detection probability may be achieved at the expense of allowing a relatively high incidence of false alarms from everyday objects, since such objects will not generally be sent through DV systems, and in any case the most likely result of such a false alarm is just that the article is subjected for a second time to the deactivation process. This lack of discrimination, the small size of the interrogation volume, and the fewer cosmetic constraints mean that the DV system can operate using different physical principles from the EAS system, and is likely to be considerably cheaper. An important implementation of this invention is where the DV system is combined with the EAS system by having a single EAS system (or one at each exit from the retail store) and a number of DV systems, one at each point of sale or deactivation station. In one embodiment, suitable for use with magnetically deactivated markers, the DV system consists of a magnetic flux detector, placed close to the magnetising element of the deactivation system, which detects a rapid change in the local magnetic flux when the deactivating component of the marker has its magnetisation state changed. This detector may consist of a semiconductor Hall probe element, a wire coil or loop, a fluxgate magnetometer, a magnetoresistive magnetometer, or other sensitive flux measuring device. When the detection is made a "success" signal is emitted; or if the DV is combined with an optical or other object-detection device then a "failure" signal will be emitted if no flux detection is made at the same time as object-detection. In another embodiment, suitable for markers where the deactivating procedure is well localised in space, or where the deactivator is triggered by pressure or by the proximity of an object, then the DV system may simply give a confirmatory audible or visible indication that an object has passed within the deactivation region or that the deactivator device has been triggered. In this embodiment the DV need not measure any parameter associated with the active or deactivated marker, but simply the presence of any object in the appropriate position.

In a further embodiment the DV system detects one parameter or parameters associated with an active (i.e. non-deactivated marker) , such as some of the magnetic properties or electrical non-linearities of the marker which are used for its detection by the EAS system. For example, with soft magnetic markers, the DV system may use a single- or multiple-frequency magnetic field to interrogate the marker, and detect the presence of a harmonic or harmonics of the interrogation frequencies as the soft magnetic element is driven through magnetic saturation. This would indicate the presence of a non-deactivated marker.

In a further aspect, the invention provides an electronic article surveillance system for use in a store in conjunction with markers carried by merchandise offerred for sale, which electronic article surveillance system comprises a plurality of deactivators located or intended to be located one at each point of sale within a store; a plurality of deactivation detectors located or intended to be located one at each point of sale within a store and so that each item sold, after its marker has been deactivated at the point of sale, can be brought to or into or passed through a deactivation detector before being handed to the purchaser; and at least one interrogation gate through which all shoppers pass before leaving the store, said interrogation gate incorporating a detector for non-deactivated markers.

Preferably, the markers for use in conjunction with a system as defined above are magnetic markers or tags, e.g. markers as described and claimed in European Patent Application No. 88305134.4. The deactivators may also be of the type or types described and claimed in European Patent Application No. 88305134.4. The deactivation detectors preferably function by detecting the magnetic properties of the tags or markers as they pass by, or through, a localised deactivation detector zone.

Claims

CLAIMS :

1. A system for verification of de-activation of an anti-theft marker which is de-activated magnetically, which comprises a deactivation device including a magnetising element; and a magnetic flux detector located close to said magnetising element so as to detect a rapid change in magnetic flux when an anti-theft marker is subjected to the magnetising force of said magnetising element.

2. A system as claimed in claim 1, wherein said magnetic flux detector is one of: a Hall effect device, a wire coil or loop, a fluxgate magnetometer, a magnetoresistive magnetometer.

3. A system for verification of de-activation of an anti-theft marker which is de-activated in a localised zone, which comprises the deactivation device and a device for detecting the proximit of an anti-theft marker within said localised zone.

4. A system as claimed in claim 1, wherein there is additionally provided a magnetic field generating device which is arranged to produce an alternating frequency magneti field, and wherein said magnetic flux detector is arranged to detect the presence of a harmonic or of harmonics of the frequency generated by said magnetic field generating device in response to the anti-theft marker.

5. An electronic article surveillance system for use in conjunction with markers carried by merchandise or other objects, which system comprises a plurality of deactivators located at predetermined positions; a plurality of deactivation detectors, one being associated with each of said deactivators; and at least one interrogation gate through which said merchandise or objects is/are required to pass, wherein said deactivation detectors are located so that each item of merchandise or each object can be brought into or passed through a deactivation detector after its marker has been deactivated and before it passes through said interrogation gate; and wherein said interrogation gate incorporates a detector for non-deactivated markers.