Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Patent
1991-07-24
1994-02-22
Picard, Leo P.
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
174 35MS, 150147, 150149, H05K 900, A45C 1118
Patent
active
052889424
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
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, i.e. the face from which the encoded information is read.
BACKGROUND ART
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.
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, tum-bag, briefcase, file (personal, hand held or 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 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, strip, granules, powders and composites with other materials.
DISCLOSURE OF THE INVENTION
According to the present invention, keepers in the 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 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.
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 received by known methods of formulation of the ferrogmatnetic 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 clo
REFERENCES:
patent: 2269149 (1942-01-01), Edgar
patent: 2353550 (1944-07-01), de Forest et al.
patent: 4593736 (1986-06-01), Morita
patent: 4632250 (1986-12-01), Ueda et al.
patent: 4851610 (1989-07-01), LeBlanc et al.
Ledynh Bot Lee
Picard Leo P.
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