US 4,795,898 AGranted

Personal memory card having a contactless interface using differential data transfer

AssigneesAmerican Telephone and Telegraph Company, AT&T Bell Laboratories, AT&T Information Systems Inc.

InventorsHoward L. Bernstein, Thomas M. Grill, Ronald Silver

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Abstract

A personal memory card the size of a standard plastic credit card is usable in a variety of applications, from custom repertory dialing to storage of individual medical and/or banking records. Although the card looks and feels much like an ordinary credit card, the personal memory card includes a computer, an electrically erasable field-programmable read-only memory and also circuitry for inductively receiving a power signal and capacitive transferring data signals between the card and a card reader/writer located in an associated station. No direct ohmic electrical contact is made between the card and the reader/writer for transferring power to the card or for transferring data to and from the card. The card is also reprogrammable by the associated station with new and different data as desired.

Claims19

Dependent claims

A portable data card including memory means for storing data and processor means for processing data, the data card comprising:

input/output means operably connected to the processor means for communicating with at least one reader/writer station, the processor means interpreting commands and processing data from the reader/writer station, the processor means being operably connected to and communicating with the memory means and formatting data for transfer both to the reader/writer station and to the memory means, the input/output means including capacitive coupling means for differentially transferring data from the reader/writer station to the data card and from the data card to the reader/writer station;
energy coupling means for receiving magnetic energy transmitted from the reader/writer station and for converting the magnetic energy into electric energy for energizing the memory means and the processor means;
and
the capacitive coupling means and the energy coupling means providing in combination a complete communication interface between the data card and the reader/writer station.

1 more element

Dependencies are inferred from the claim text.