American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Bell Laboratories

Bell Telephone Laboratories

American Telephone and Telegraph Company; At&t Information Systems

Robert L Billings

Alan Michael Lyons

Richard C Sherwood

Ernst M Gyorgy

Donald W Dahringer

Ho-Sou Chen

Robert C Cooper

Frankie G Meier

Mark A Bowers

Magnetic circuit elements, e.g. for inclusion on circuit boards including one or more windings about a toroidal core are produced by joinder of mating sheets, one or both recessed to hold the core, and each containing partial windings. Joinder is by use of an anisotropically conducting adhesive layer. The layer is applied as an uncured thermosetting adhesive containing spherical conducting particles of such size and distribution as to statistically result in electrical completion of windings while avoiding turn-to-turn shorting.

Circuit elements dependent on core inductance and fabrication thereof

A power transfer arrangement provides regulated power transfer from a station to a contactless portable data card without the need for regulation circuitry on the card itself. The station includes a primary coil for magnetically coupling power to a secondary coil, located on the card, when the data card is brought into close association with the station. The arrangment includes a microprocessor, a power amplifier including the primary coil, a variable voltage source and apparatus for measuring current flow in the primary coil. When the portable data card is not in close association with the station, the microprocessor causes the variable voltage source to provide a sequence of stepped voltages. Quiescent current flow is measured at each step and stored in memory. When the portable data card is brought into close association with the station, the microprocessor causes the variable voltage source to provide a sequence of stepped voltages. Active current flow is measured at each step and stored in memory. Power delivered to the data card is calculated as the difference between active and quiescent currents--multiplied by the magnitude of the variable voltage source. The sequence of active current measurements continues until the calculated value of power delivered to the data card exceeds a predetermined threshold power, at which time the data card is receiving a precise, predetermined amount of power.

Power regulator for a contactless credit card system

A transformer (10) for mounting on a printed wire board includes a bobbin (14) held between two ferrite core slabs (12). The bobbin is wound with a primary winding (28) having a secondary winding (32) wound over it. The wire leads (30) of the primary winding lie in slots (26) in one of the flanges (20) of the bobbin which extend to terminals (24) of a terminal base (22) integral with the flange to isolate them from the secondary windings and leads (34).

Transformer with wire lead isolation slots

Contactless inductive power transfer from a stationary 'reader' to energize the electronics on a portable data or 'smart' card is made practical through a flexible inductor carried on the card. The inductor, which acts as the secondary portion of a power transformer, comprises a flat coil and a flexible magnetic but nonmagnetostrictive core piece. The core piece may be a thin wafer of amorphous magnetic alloy. Clock pulses to synchronize data transfer on the card with the reader can also be generated from the signal picked up by the inductor.

Flexible inductor

The disclosed magnetic devices, including a magnetically coupled conducting path, incorporate amorphous, low magnetostriction alloys of the general formula (Co.sub.a Fe.sub.b T.sub.c).sub.i X.sub.j, the 'metallic' constituents thereof being within the parenthetical expression. T, in the formulation, is selected from among Ni, Cr, Mn, V, Ti, Mo, W, Nb, Zr, Pd, Pt, Cu, Ag and Au, X being at least one 'glass former' selected from among P, Si, B, C, As, Ge, Al, Ga, In, Sb, Bi and Sn. The 'metallic' constituents comprise from 70-90 atomic percent of the alloy with cobalt being present in an amount of at least 70 atomic percent of the 'metallic' constituents. The described material has been prepared by rapid cooling from the liquid, directly to the shape needed for fabrication of the device (e.g., tape to be wound to form an inductor core). When the amorphous material is heat treated for from 30 minutes to two hours at temperatures from 125 degrees Centigrade to 200 degrees Centigrade, it exhibits a temperature stabilized magnetic permeability. The fabrication of such devices as temperature stabilized inductors and transformers is contemplated.

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Andover, MA, United States of America

Robert L Billings