Fare card read-writer which overwrites oldest or invalid data

Abstract

An access control ticket having three fields of data, a first field (3) of fixed data, a second field (7) of variable data, and a third field (8) of variable data is read and information processed by a microprocessor. The microprocessor determines the validity of information on the ticket data fields and which of the variable fields has older data. Writing only occurs on (over) the variable field with invalid or older data. Upon subsequent use, the ticket contains current access data (just written) and last previous access data, as well as fixed field data. This added data (past use) can be used for statistical analysis or other purposes. More importantly, the added data field reduces read/write reliability problems. One improperly written variable data field does not invalidate ticket, only the last variable data entry. The microprocessor is programmed to overwrite invalid data in one of the variable data fields during the next use. Since the ticket still has the fixed data field and a prior use variable data field, no human intervention, repair of access control devices (for single failures), or new tickets are required. The location of variable use data can also be segregated from fixed data to further enhance reliability. This reduction in failures and tolerance of single non recurring errors allows hand held swipe type read/writer to be utilized for mass transit applications. Access is quick, avoiding manual ticket insertion, grabbing, transport and return.