Patent GB-1372180-A (GB)
Title: Fare reckoning system
IPC: G07B15/00
Filed: 1971-12-22
Abstract: 1372180 Ticket-operated, public transport, fare-computing systems EMI Ltd 22 Dec 1971 [23 Dec 1970] 61056/70 Heading G4T In a public transport fare reckoning system, a ticket, bearing a magnetically-encoded representation of the amount of travel credit remaining from an originally paid for travel value, is presented to apparatus associated with an entry turnstile at the starting station for a journey; the apparatus magnetically records on the ticket information identifying the starting station; at the destination station the ticket is presented to apparatus associated with an exit turnstile; this apparatus reads the information identifying the starting station, retrieves from a store the fare corresponding to the journey, subtracts this fare from the travel credit encoded on the ticket and issues a new ticket bearing a magnetically encoded representation of the updated remaining travel credit. The store from which the fare is retrieved may be a store associated with the individual destination station or; if this does not hold the sought fare, a more comprehensive store serving all the stations on the appropriate line, or, if this does  not hold the sought fare, a central store, serving all stations and containing all fares for the complete system. Tickets and first class travel arrangements.- Each ticket is a card bearing human readable printed or embossed information and a central strip for receiving the magnetically encoded  details of remaining credit and whether the ticket is for adult or child. If the ticket is to be used for first class travel for all its paid for travel value, then it is printed and encoded to this effect. Otherwise, a normal ticket can be used for first class travel for any selected journey by presenting the ticket at the starting station to a device which prints "First" on the ticket and punches a hole in it. At the destination station, the exit turnstile apparatus detects the hole and causes deduction of the higher first class fare. Turnstiles.-Each turnstile apparatus ineludes a ticket entry throat and a ticket return slot, from which the ticket must be removed to free the turnstile. Up to four tickets may be held in the return slot to make use of the turnstiles by families easier. On receiving a ticket a magnetic read head passes the encoded information to a computer associated with the respective station. This checks the validity of the ticket. Invalid tickets are returned through the entry throat. At each entry gate, a magnetic write head applies the station-identifying information and further information aimed at minimizing fraud. At each exit gate, the computer either provides the required fare from its memory or formulates the request for this fare for transmission to the line store. At each exit gate, the apparatus also issues the new updated ticket if the remaining credit exceeds the journey value or returns the old ticket if the remaining credit is not sufficient for the journey. In the latter case, the ticket is subsequently presented to an excess fare turnstile with facilities for inserting cash or an additional stored value ticket or both, for paying off the deficit. At each turnstile, a display is lit and a warning is sounded when a child ticket is sensed. A reversible turnstile may be provided and manually switched between entry and exit modes. Stores.-The fares held in the store associated with each individual station (i.e. the computer memory) are continuously updated by clearing from the store those fares not recently used at the respective station and replacing them by more commonly used fares from the line store. The line and central stores are also computers. The line computer may control the turnstiles direct if the associated station computer fails. Parity checks.-The various signals communicated between the various components of the system are based on a binary coded hexadecimal system with six parity check bits. Fraud preventing.-Each station computer keeps a continuously updated store of the serial numbers of the ten most recently presented tickets at its station. If the serial number of a presented ticket corresponds to one of these stored ten numbers, the ticket is declared invalid, thus preventing tickets being passed back over the turnstile for use by another person.