A CARD READER/WRITER STATION FOR USE WITH A PERSONAL MEMORY CARD USING DIFFERENTIAL DATA TRANSFER

A personal memory card system is arranged for use with a memory card which looks and feels much like an ordinary credit card. No ohmic electrical contact is required between the card and a reader/writer in an associated station for transferring data to and from the card and operating power to the card. The need for conductive contacts in transferring data between the reader/writer and the card is avoided through use of a capacitive interface formed when insulated metallic plates on the card are aligned in close proximity with corresponding plates on the reader/writer. Operating power is transferred to the card through an inductive interface formed when a flexible flat inductor embedded in the card is aligned in close proximity to another inductor in the reader/writer. Data to and from the card and power to the card are reliably transferred even after some time of normal use since there are no exposed metallic surfaces to corrode or to which particles may collect. In addition, the potential of damage to the card from electrostatic discharges is minimized since an insulator is provided between the electrical inputs to the card and any sources from which this discharge might occur. The personal memory card system is also arranged to permit an authorized user to selectively reprogram a memory card with new and different data as desired.