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[ EN ]


In the technical field of holders for devices on which information and/or data is encoded in the form of patterns of magnetism, the present invention concerns a method of 'keeping' (in magnetism terminology) the said magnetic patterns . The term ' patterns ' includes any arrangement of magnetism such as regular or irregular lines, dots, waves, areas of magnetism, areas of reversed polarity and unmagnetised areas.
The encoding of information and/or data in the form of magnetic patterns is well known and widely used, a typical device making use of this principle being the card containing one or more magnetic stripes . Such devices are widely used as credit cards, charge cards, cash dispenser cards, security cards and fare tickets and for many similar applications. It is known that extraneous
magnetic fields have a deleterious effect on the said devices and there are known methods of shielding against such effects. A good shield should completely surround but not make contact with the device being protected.
Possibly not so well known is the fact that the magnetic patterns are subject to gradual degradation due to the natural thermal activity and slowing down of the magnetic spin of the molecules of the magnetised material. Such degradation can be reduced by the use of 'keepers' to establish low reluctance paths to enable the magnetic lines of force to complete their natural circuits. To achieve this result a keeper should be in close contact with the face of the device from which lines of magnetism, emanate, ie the face from which the encoded information is read.

Credit cards and similar devices are normally carried around in holders of some sort. Known cardholders are designed to protect the tangible substance of the devices and some cardholders offer shielding against extraneous magnetic fields. Known cardholders do not provide any means of 'keeping' the information and/or data encoded on the magnetic stripes.
5 Cardholders may be designed for the sole purpose of carrying the devices, may be attached to a garment or may be part of a more comprehensive multi-purpose holder such as a wallet, pocketbook, handbag, purse, belt, bum-bag, turn-bag, briefcase, file (personal, hand held or
10.otherwise) or anything else into which the devices may be placed, carried or stored.
As further background art, it is well known that magnetically soft ferromagnetic material has the
properties of low reluctance, low remanent magnetism, high

15 relative permeability, and a narrow hysteresis loop and that the said material provides a ready path for magnetic lines of force. A well known use of these properties is in keepers for permanent magnets . Known ferromagnetic materials are manufactured in many forms, including sheet,

20 strip, granules, powders and composites with other
materials .

According to the present invention, keepers in the

25 form of thin sheets or foils of magnetically soft
ferromagnetic material are incorporated or inserted into cardholders for devices on which information and/or data is encoded or stored as patterns of magnetism. The said sheets or foils are of suitable size and shape for the

30 said devices and cardholders are designed so that the magnetised reading surfaces of the said devices are held in close contact with the surfaces of the said keepers. The purpose of the keepers is to keep the said magnetic patterns in good condition.
35 In addition to the known inherent properties of the magnetically soft ferromagnetic material, the keepers are made so that they have a high resistance to eddy currents in order to minimise any magnetic fields induced by movement of the devices. The additional property of high resistance may be achieved by known methods of formulation of the ferromagnetic material and/or composites to obtain high resistivity or by known methods of fabrication of the sheets .
The benefit of the invention is obtained when
devices, such as credit cards, are inserted into the cardholders with the reading surfaces of their magnetized components in close contact with the surfaces of the keepers . To avoid physical damage to the magnetized components, the keepers have a smooth, low friction and/or lubricated surface finish.

The drawing shows details of a specific embodiment of the invention (not to scale), in the form of a holder designed to carry two credit cards. An exploded view of the holder is shown in order to clearly illustrate the three parts. Part 1 is the keeper. Parts 2 and 3 are covers.

The best mode for carrying out the invention is a cardholder for two credit cards. In the drawing, part.1 is the keeper, said keeper being a composite sheet 0.1mm thick with a smooth, low friction surface finish. The sheet composition is a fine powder of magnetically soft iron, a polymer such as pvc or polyethylene and a suitable binder, making a material of high resistivity. The soft iron powder content is as high as possible consistent with the requirements of mechanical strength and smooth surface finish of the sheet.
The sheet is homogeneous but an alternative would be a polymer substrate coated on both sides with the
ferromagnetic material in a suitable binder. The
technology for fabrication of this type of sheet is well known, for example in the manufacture of recording tape and computer floppy discs (which, incidentally, use magnetically hard material).
Parts 2 and 3 are covers made of 0.05mm thick
transparent pvc.
To carry out the invention, the three parts are fixed together by some suitable means such as stitching, welding or glueing, along the bottom and on two sides (as
indicated by dashed lines) leaving the top end open for insertion of the cards. To make insertion easier, part 1 projects slightly farther at the open end than parts 2 and 3. (Note that known cardholders consist of parts 2 and 3 only) .
The* benefit of the invention is obtained when the cards are inserted, one each side of the keeper, with their magnetic stripes facing and in close contact with the said keeper.
A number of simple cardholders of this type could be strung together in concertina fashion, joined at one end to form a 'book' or built into multi-purpose carriers or storage receptacles. Any other suitable materials could be used instead of the clear plastic covers, for example, tooled leather for a luxury version.

Users of credit cards and similar devices with information and/or data encoded as patterns of magnetism would benefit from having holders which keep the said magnetic patterns in good condition. Cardholders made in accordance with the present invention are easily
manufactured and would find widespread use in the domestic market, in banking, security, commerce and industry.