04837422 is referenced by 483 patents and cites 13 patents.

A card combination which is issued to a single cardholder can be reprogrammed by the cardholder for use by a sub-user to a desired extent with regard to value and time. The cardholder uses a master enabling code to access the programming mechanism. He/she assigns a sub-PIN for use by the sub-user and opens a subordinate account for the allowed credit value within card's total credit value. This subordinate account can be accessed using the sub-PIN. A limited term can be selected during which any transaction using the sub-PIN and using the subordinate account can be conducted. After the expiration of that term the sub-PIN is automatically erased and any balance in the suborinate account is re-credited to the main credit account of the card. Such a multi-user card can also be used in conjunction with a program for varying the value of units stored in the credit account.

Title
Multi-user card system
Application Number
7/94379
Publication Number
4837422
Application Date
September 8, 1987
Publication Date
June 6, 1989
Inventor
Christian Hinneberg
Hamburg
DE
Juergen Dethloff
Hamburg
DE
Agent
Notaro & Michalos
Assignee
Juergen Dethloff
DE
IPC
G06F 15/30
View Original Source