GB2268369A - Security tag and automated goods handling - Google Patents

Abstract

An automated shopping or other goods handling process in which a magnetically coded tag identifying the goods and its price or other information has a degree of permanence such as to prevent or limit vandalism and theft. Multiple magnetic strips of different length or a single strip are caused to oscillate at various multiples of a fundamental frequency when placed in an alternating magnetic field by means of a parallel high coercivity magnetic strip which is magnetised according to a particular pattern to provide the coding. The tag is "debited" at a handling station and tags are magnetically sensed so as to sound an alarm if undebited.

Description

Automated Goods Handling Process This invention relates to automated goods handling processes employing magnetic tags or labels and is particularly although not exclusively applicable to supermarket shopping transactions.

It is probable that future supermarket shopping transactions will be performed with minimal staff supervision and consequently additional security safeguards will be required. Accounting processes on shopping goods items will involve both identification information: price, type of goods, origin etc, and also security measures.

An object of the present invention is to provide magnetic tags and methods of using them which facilitate both the security and ID aspects of the processes.

According to one aspect of the present invention, in a method of performing a goods handling process, each goods item has attached to it a magnetically coded tag carrying information relating to the identity and source of the item, the magnetic coding being imposed in high coercivity material not easily erased.

The goods handling process maybe a shopping transaction in which the goods item is purchased by a shopping customer, the magnetic tag is read by a debiting magnetic reader which also converts the magnetic coding into a 'debited' state, and the exit from the debiting reader is by way of a magnetic sensor which detects non-debited magnetic codings and initiates an alarm condition.

According to another aspect of the invention, in a method of performing a goods handling process in which goods items pass through an accounting process into one of a plurality of collection means, each goods item has attached to it a magnetic tag, the accounting process is associated with magnetic writing means which imposes on each goods item a magnetic coding associated with the particular collection means and each collection means has magnetic reading means responsive to a magnetic coding not associated with the particular collection means to initiate an alarm condition.

The collection means maybe shopping trolleys equipped with magnetic readers, the goods items having identity and price tags readable by scanning means in accounting process, and the magnetic writing means being incorpqrated with the scanning means.

The magnetic writing means and the magnetic readers preferably have their magnetic codings changed in unison at intervals.

According to another aspect of the invention, in a method of performing a goods handling process in which goods items pass through an accounting process into a collection means, each goods item has attached to it a magnetic tag carrying a random number magnetic code in addition to an identification code subject to the accounting process, the accounting process having magnetic reading means responsive to the random number codes to indicate whether one or more than one random number codes are present and to initiate an alarm condition when different random number codes are submitted simultaneously.

The collection means maybe a shopping trolley equipped with the magnetic reading means. The identification code may also be a magnetic code, the random number code and the identification code being read as a goods item is put into the shopping rolley.

The random number code may have a predetermined number of unique segments the number of segments being counted by the magnetic reading means to determine whether the total number read at any one time exceeds the predetermined number and to initiate the alarm condition in that the event.

According to another aspect of the invention, a magnetic tag for use in a method as aforesaid comprises a first linear component of relatively hard magnetic material, intimately fixed to a plurality of second linear components of relatively soft magnetostrictive material, the first component being adapted to carry a linear magnetic code and to constrain the second components to resonate at respective discrete frequencies when subject to an appropriate oscillatory magnetic field.

In such a magnetic tag, the discrete frequencies being dependent upon the lengths of the second components the second components are of such different lengths as not to prodcue overlap between harmonic frequencies of the different second components. Code magnetisation of the first component may be effected by a single magnetic writing head held closely adjacent the magnetic tag.

In a method of performing a goods handling process as aforesaid, the goods items have magnetic tags attached, the magnetic tags incorporating a plurality of second linear components as aforesaid, in which method magnetic reading means on the shopping trolley maybe adapted to transmit energising pulses of oscillatory magnetic field at an oscillation frequency which is swept through a predetermined band to initiate resonances from the second components, the combination of resonances forming an identification and/or a security code.

A method according to Claim 16, wherein each of said second components exhibits only one or two resonances in the band.

The magnetic tag may comprise a first component, being a strip of relatively hard magnetic material intimately fixed face to face with a second component, being a strip of relatively soft magnetostrictive material, the second component strip having tapered ends to permit its resonating length to be determined by the imposition of magnetic limit marks on the first component between the tapered portions of the second component.

Where the magnetic tags have a tapered second component strip, magnetic writing means may impose a resonating length on each second component which is the same for all goods items in a particular accounting process and which modifies the harmonic frequencies otherwise available from the physical length of the second component strip.

Several methods of operating automated shopping processes using magnetic tags will now be described by way of example only.

The magnetic tags to be employed are of several forms. In a first type the tag incorporates the commonly used bar code number (the "EAN-1S" ID) which comprises a 13 digit number giving the price, type of goods, sometimes the origin of the goods, etc. This 13 digit number is presently presented as an optically read bar code number.

To encode it magnetically 43 magnetic bits are required. The tag comprises two component types, a relatively hard magnetic component and one or more relatively soft magnetic components comprising an amorphous alloy having high permeability and low loss. The two component types are intimately bonded together so that magnetisation patterns stored in the hard component an a permanent or semi-permanent basis by an external writing head are induced in the second, soft, component. The soft component has magnetostrictive characteristics and is triggered into oscillation by a subsequently applied oscillatory magnetic field. The two components (in one form) are longitudinal strips intimately attached face to face. The magnetostrictive component has a frequency of oscillation determined by its physical length and by any magnetic bias that is imposed on it by the magnetisation pattern in the hard component. These magnetic biases can be arranged to produce resonances at a selection of harmonics of the fundamental frequency, the harmonics being taken to correspond to the bits of a binary code.

In accordance with one embodiment of the invention 5 'soft' strips are arranged side by side over a common or individual 'hard strips'. The soft strips are of different lengths such as to have different fundamental resonance frequencies and also such that the harmonics of these different fundamentals do not overlap, i.e are separate and distinguishable.

The tags are coded by writing into the hard strip(s) a common magnetic pattern designating a code selection of harmonics.

When a reading or interrogating field of a particular harmonic frequency is applied to the tag, only that strip for which the written magnetic pattern is harmonically related will resonate for a significant period of time. The other four will absorb little energy from the field and consequently regenerate no significant field. If the interrogation is performed by a pulsed signal the regenerated resonance signal may be detected in a time - gated homodyne receiver, the receiver being enabled for a short period following interrogating pulse transmission. The frequency band of potential harmonics is scanned by stepping the interrogating pulse frequency.

In the above arrangement the harmonic that is regenerated on interrogation indicates which of the five strips is resonating. This is effectively a 1 out of 5 code. This use of a single frequency to represent a code enhances detectability.

In another form of re-writable tag, there is a single two-layer strip. At least the 'soft' component of this strip has tapered ends, i.e. the width of the strip decreases to zero or near zero over a length of e.g. one-tenth to one-eighth of the strip length. This tapering suppresses the effect of the strip length in determining the fundamental resonant frequency. On writing a code to the strip, a magnetic limit mark is imposed on the hard component at each end between the tapered portions. These very positive limit marks effectively determine the resonant length of the strip and, by adjustment of their position, allow it to be set differently on different occasions. The limit marks are wiped and re-imposed at the new required position when the tag is re-written.

By this means a single strip can, at different times, carry as many orthogonal codes as, for example, the 5-strip tag above.

Where the magnetic coding is to be carried on a permanently magnetised tag (not eraseable), the tag will have the same general form as before but the lower (hard) strip of the sandwich is composed of an extremely hard magnetic material, for example based on samarium cobalt (in dust form) or other rare earth material. This may be used in the form of a magnetic ink and printed onto packaging or formulated into an extremely hard type of magnetic recording tape. Such pre-recorded codes will be applied at manufacture using a powerful wide gapped recording head.

Printing of the tags is, in general, a preferred form of application.

Operation of an automated shopping system employing one or other of the above kinds of magnetic tag may take several forms.

In one basic system goods are marked with a 43-bit semi-permanently magnetised tag, this 43-bit code giving the standard EAN-13 identification. The customer takes the tagged goods off the supermarket shelf, places them in a trolley and takes them to an automatic checkout where they are loaded on to a conveyor to pass a magnetic reader. The details of each goods item are read, recorded and debited in the accounting system, the reader being effective at distances in the region of 0.5 metres. In addition, after registering in this way, the semi-permanent tag coding is converted to a 'bought', i.e. 'debited', condition. On collection of the goods and passage through a detector region the 'bought' condition may consist of re-writing it to a 'bought' code.

In this system the tags are so hard magnetically as to be immune to casual erasure even by a determined vandal. Clearly however, it would be easier to delete a code than to convert it to an unspecified 'bought' code and the latter system is preferred.

In another system goods are marked with a conventional optical bar code giving the EAN-13 number, and an adjacent magnetic tag capable of carrying a re-writable code.

Each shopping trolley is fitted with a magnetic reader which reads the magnetic tag as the goods item is placed in the trolley and at subsequent periodic intervals. Also associated with each trolley is a hand held optical bar code reader and magnetic code writer. When the customer takes the goods item off the shelf he reads the tag to indicate intention to buy. At the same time the magnetic writer writes a code identifying the particular trolley. Each item is treated in the same way: optically read for shopping transaction purposes and magnetically coded with a code which is unchanged throughout the particular shopping session. The trolley reader, at each subsequent reading, reads the tag of every item present - all of which are within the reader range and all of which should give the same code, which is associated, temporarily at least, with that trolley.If an item is stolen from another trolley, which of course has already been debited to the customer, the item will have the ID code of the other trolley and will trigger an alarm when read by the trolley reader. There may be, typically, 30 orthogonal trolley codes (although perhaps many more trolleys) and these are selected randomely by the hand held reader/writer at each new shopping session.

The orthogonal codes are such that each may be read in the presence of any or all of the others.

The magnetic tag in this system may be the 5-strip version or the single tapered strip version described above.

In addition to the detection of theft by transfer from one trolley to another this system also detects the use of old magnetic tags from a previous shopping session. 30 different trolley codes is a sufficient number to give a good probability that the current code and any other picked at random will be different.

If a customer wishes to 'de-register' an item before the final act of purchase, which he performs by pressing a 'debit' button, for example, on the hand held reader, he again repeats the hand held reading operation but with a 'de-register' button.

In a further system the magnetic tag employs a hard magnetic material and a permanent code comprising the 43-bit EAN-13 code plus a 20-bit random number code. The trolley in this system is electronically aided with a pair of entry coils that automatically detect entry and exit of an item by means of the order of detection.

At the same time the EAN-13 number is read and the price debited.

However, items should be put in the trolley one by one otherwise the magnetic reader may be confused. The use of a random number which is individual to the particular item enables the insertion of two or more identical items to be detected. Each 20-bit random number comprises say three segments which are detectable as such. If more than three are detected at one time there is more than one item present and staff are alerted to resolve the difficulty. Alternatively shopper is made aware of the difficulty and corrects it himself.

It will be appreciated that the magnetic tag described may be used in goods handling applications generally, for example baggage handling in airports.

Claims (19)

1. A method of performing a goods handling process in which each goods item has attached to it a magnetically coded tag carrying information relating to the identity and source of the item, the magnetic coding being imposed in high coercivity material not easily erased.

2. A method of performing a shopping transaction according to Claim 1, wherein said goods item is purchased by a shopping customer, the magnetic tag is read by a debiting magnetic reader which also converts the magnetic coding into a 'debited' state, and the exit from the debiting reader is by way of a magnetic sensor which detects non-debited magnetic codings and initiates an alarm condition.

3. A method of performing a goods handling process in which goods items pass through an accounting process into one of a plurality of collection means, each goods item having attached to it a magnetic tag, said accounting process having associated magnetic writing means which imposes on each goods item a magnetic coding associated with the particular said collection means and wherein each said collection means has magnetic reading means responsive to a magnetic coding not associated with the particular said colleciton means to initiate an alarm condition.

4. A method according to Claim 3, wherein said collection means are shopping trolleys equipped with magnetic readers, said goods items have identity and price tags readable by scanning means in said accounting process, and said magnetic writing means is incorporated with said scanning means.

5. A method according to Claim 4, wherein said magnetic writing means and said magnetic readers have their magnetic codings changed in unison at intervals.

6. A method of performing a goods handling process in which goods items pass through an accounting process into a collection means, each goods item has attached to it a mgnetic tag carrying a random number magnetic code in addition to an identification code subject to the accounting process, the accounting process having magnetic reading means responsive to the random number codes to indicate whether one or more than one random number codes are present and to initiate an alarm condition when different random number codes are submitted simultaneously.

7. A method according to Claim 6, wherein said collection means is a shopping trolley equipped with said magnetic reading means.

8. A method according to Claim 7, wherein said identification code is also a magnetic code, said random number code and said identification code being read as a goods item is put into the shopping trolley.

9. A method according to any of Claims 6, 7 and 8, wherein said random number code has a predetermined number of unique segments the number of said segments being counted by said magnetic reading means to determine whether the total number read at any one time exceeds said predetermined number and to initiate said alarm condition in that event.

10. A method according to Claim 9, wherein said random code comprises 20 magnetic bits.

11. A method of performing a shopping transaction substantially as hereinto described.

12. A magnetic tag for use in a method according to any preceding claim the tag comprising a first linear component of relatively hard magnetic material, intimately fixed to a plurality of second linear components of relatively soft magnetostrictive material, the first component being adapted to carry a linear magnetic code and to constrain the second components to resonate at respective discrete frequencies when subject to an appropriate oscillatory magnetic field.

13. A magnetic tag according to Claim 12, wherein said discrete frequencies are dependent upon the lengths of the second components and wherein the second components are of such different lengths as not to produce overlap between harmonic frequencies of the different second components.

14. A magnetic tag according to Claim 13, adapted for code magnetisation of said first component by a single magnetic writing head held closely adjacent the magnetic tag in a process according to Claim 5.

15. A method of performing a goods handling process according to Claim 4 or Claim 7, in which said goods items have magnetic tags attached, said magnetic tags being in accordance with any of Claims 12, 13 and 14, in which method magnetic reading means on the shopping trolley is adapted to transmit energising pulses of oscillatory magnetic field at an oscillation frequency which is swept through a predetermined band to initiate resonances from said second components, the combination of said resonances forming an identification and/or a security code.

16. A method according to Claim 15, wherein each of said second components exhibits only one or two resonances in said band.

17. A magnetic tag for use in a method according to any of Claims 1 to 11, the tag comprising a first component, being a strip of relatively hard magnetic material intimately fixed face to face with a second component, being a strip of relatively soft magnetostrictive material, the-second component strip having tapered ends to permit its resonating length to be determined by the imposition of magnetic limit marks on the first component between the tapered portions of the second component.

18. A method according to any of Claims 4, 5 and 5, for processing goods items having magnetic tags according to Claim 17, wherein said magnetic writing means imposes a resonating length on each second component which is the same for all goods items in a particular accounting process and which modifies the harmonic frequencies otherwise available from the physical length of the second component strip.

19. A magnetic tag providing identification and/or security for goods items in a shopping transaction, substantially as hereinbefore described.