Abstract:
In a transport system using contactless microcircuit cards, users are obliged to hand in a card when the credit shown on it has been used up. The value of the cards is recharged and they are then sold again. Recovering and recharging the cards reduces the ticketing cost per journey.

Description:
BACKGROUND OF THE INVENTION 
     The present invention consists in a contactless payment method and device using a rechargeable medium. The medium is typically a microcircuit card (“smart card”) which can be read and written without physical contact via a radio link, but the invention can be applied to all rewritable media which can be read and written without contact. Some smart cards which can be read and written using a radio link can also be read by contact (magnetically, optically or electrically) and so can also be read and written by contact readers, i.e. readers which require the card to be inserted into a machine. 
     The method of the invention is more particularly intended to be used in the field of travel tickets. It is described in relation to that field, but other fields are feasible, in particular automatic dispensing. 
     Travel tickets are generally on a single-use medium, for example paper tickets carrying a magnetic stripe, because their cost is low compared to the fare. The user discards the ticket when a predetermined journey or a predetermined number of journeys has been completed or when an expiry date has been reached. Those media are read by contact in a reader. 
     Payment methods using a contact reader have the disadvantage of a low throughput of users, because each user takes some time to stop in front of a gate, take the ticket out of a pocket or handbag, insert it into a machine and recover it. It is necessary to provide parallel gates to increase the throughput of users. 
     For several years now, public transport ticketing systems have been evolving from the use of conventional tickets towards the use of contactless smart cards. However, the cost of these contactless cards (several hundred times the cost of a paper ticket with magnetic stripe) limits their use to season tickets or rechargeable tickets (tickets that the user can “recharge” in an automatic machine accepting payment by banknotes, coins or credit card), to retain a ratio close to one percent between the cost of the ticket per journey and the fare. Consequently, conventional tickets continue to be used either for all users or at least for occasional users who purchase tickets valid for only one journey (“single-journey tickets”). 
     Contactless smart cards are currently being used as public transport tickets on an experimental basis in France (Paris and Marseille) and for real (Seoul, Hong Kong, Washington, etc.). The system is generally referred to as teleticketing. To carry out all the standard functions of a microcircuit card, such as writing, reading, authentication, etc., the card can communicate over a short distance (approximately ten centimeters) with a coupler provided with an antenna. It usually also receives the power needed for it to operate from the antenna. This type of remote communication is currently being standardized by ISO Standard 14443. There are also combined cards operating without contact for transport access transactions and with contact for personalization or recharging transactions using standard contact equipment. 
     The teleticketing system has a number of advantages over conventional paper or magnetic stripe tickets:
         there is no need to insert the ticket into a slot and recover the ticket from the same slot or an outlet chute, which reduces the overall time of a transaction by eliminating the human action and reaction times, and the electronic transaction time is short (approximately 100 ms to 200 ms) compared to a magnetic stripe transaction (from 500 ms to 1 000 ms), these two features increasing the throughput at the control point, which leads to a reduction in the number of control points;   users retain the ticket in the hand (or handbag), which eliminates the risk of loss or theft of the ticket at the time of payment;   more data can be stored in the memory card than on a magnetic stripe ticket and operators can therefore add to their knowledge of how the transport network is used;   a teleticketing reader is less costly than a magnetic stripe reader (by a factor of approximately 5);   the reader requires less maintenance because there are no mechanical moving parts;   the scope for vandalism is limited;   the scope for differential fare structures is extended; and   other applications (electronic purse) are also possible.       

     On the other hand, the cost of a contactless ticket is much higher than that of a magnetic stripe ticket (by a factor of at least 1000) and in practice incompatible with the fare for a single journey or the cost of a basic service which can be paid for using a ticket of this kind. It is not feasible to use a medium of this kind to pay for a single journey and then discard it. 
     The contactless smart card is therefore restricted to season tickets and rechargeable tickets. In the transport field, where occasional users represent approximately 20% of all passengers and account for approximately 40% of revenue (because single-journey tickets do not benefit from reduced fares), cheap media continue to be used for single-journey tickets, for example paper tickets with a magnetic stripe. This significantly reduces the benefit of teleticketing because the need for the two systems to co-exist increases installation and maintenance costs and limits throughput. 
     In the field of conventional ticket ing, the problem of the coexistence of two systems has been solved (in Asia in particular) by using plastics material magnetic stripe cards to the standard format for all types of tickets, instead of using plastics material cards for season rickets and rechargeable tickets and paper or card single-journey tickets. The cost of manufacturing each plastics material card is greater than that of a paper or card ticket, but very much less than the cost of a smart card. The cost problem is solved by recycling, which reduces the cost per journey. A magnetic stripe card inserted into a reader is retained by the reader when it has no further value. After checking its physical condition, its value is recharged by rewriting it magnetically, and it is then sold again. In this way it can be used several hundred times, which reduces the cost per journey and therefore avoids the need for two systems to co-exist. 
     A transport company has no difficulty in recovering the magnetic stripe cards because all users must in all cases insert their magnetic stripe card into a terminal which reads the magnetic stripe on the card, possibly writes data on it, and then unlocks a gate or a barrier if the card shows sufficient credit for a journey. The cycle of use of a magnetic stripe card in the case of centralized recycling in a metro network is as follows:
         1—Passengers purchase their tickets (single-journey tickets, rechargeable tickets or time-period tickets, etc.) from an automatic dispenser or at a ticket office.   2—The ticket is inserted into the reader of a terminal which controls physical entry and exit of passengers.   3—At the exit, the ticket is returned to the user if, after processing, it still has some value (sufficient credit for one or more journeys or a sum of money), or if the expiry date has not been reached.   4—The ticket is retained by the exit terminal if it shows no value after processing (which applies to all single-journey tickets).   5—In the case of centralized recycling, the recovered tickets are taken to a sorting center. They are checked to see if they can be used again. Those which can be used again are sorted by category.   6—The sorted tickets are returned to ticket offices or automatic dispensers and are magnetically written with the appropriate value when they are issued.       

     The above description is somewhat simplified. Rechargeable tickets can be processed differently. Users can recharge them for themselves at an automatic machine accepting payment by banknote, coin, or credit card. In this case they are neither retained nor recycled by the gate. Other variants are equally possible. The current trend is for decentralized recycling at each station. The tickets are sorted in each gate, which limits the circulation of the tickets but complicates the gates. 
     To summarize, well known in the art are: payment methods using low-cost media, read by contact in a reader, but with the problem of a low throughput of users; and payment methods using contactless media achieving a fast throughput of users but causing a problem in terms of the cost of the media which leads to their use being restricted to certain tickets so that two ticketing systems have to co-exist. 
     SUMMARY OF THE INVENTION 
     The object of the invent-on is to encourage the use of contactless media for low-value payments. 
     The invention consists in a contactless payment method using a rechargeable medium, consisting in:
         offering up the medium in the vicinity of a contactless reader, and   debiting the medium with the cost of a requested service if the credit shown on the medium is at least equal to that cost,   characterized in that, to oblige the user to hand in the medium when the credit shown by the medium is less than a fixed amount, it further consists in   verifying if the credit shown by the medium is less than a fixed amount and, if it is, inviting the user to hand in the medium they are using, and   providing a service only after the user has handed in the medium.       

     The user is therefore obliged to give up the medium so that it can be recycled. For example, in the case of travel tickets, the method consists in reading the medium without contact and then opening a gate to allow the user to pass through at the beginning and/or at the end of the journey if the medium still contains sufficient credit for at least one more journey. On the other hand, if the credit has been used up by the journey currently being paid for, or which has just been completed, the user is requested to insert the medium into a machine that retains it and then opens the gate. For example, the user is obliged to give up the medium by making the opening of an entry or exit gate associated with a controlled area conditional on giving up the medium. If users do not give up the medium, they cannot enter or leave the controlled area. 
     The medium can be given up by inserting it into a machine similar to a standard terminal associated with a standard gate. Thus the medium is used most of the time without contact, which enables a high throughput of users, and is exceptionally used as a standard contact medium on the occasion on which it must be given up. On that occasion, a user must take the card out from a pocket or handbag and insert it into a terminal in order to give it up. The procedure then takes longer than usual, but overall the method provides for a high throughput of users because contactless reading means that most users pass through the gate quickly. 
     Recycling single-journey tickets of occasional travelers, and possibly rechargeable tickets, reduces their cost and therefore generalizes the use of contactless media. 
     Recycling single-journey tickets divides the cost of the medium per transaction by the number of times it is used. For example, a medium costing around 10 French francs and used 500 times has a cost per transaction of 2 centimes, comparable to that of an Edmonson format magnetic stripe paper ticket. 
     The payment system preferably physically obliges a user to return the medium when invited to do so. The method of the invention is therefore more particularly intended for systems with turnstiles or gates for physically controlling the movement of passengers. It can nevertheless also be applied to payment systems including validating units with no physical access control. In this case, the method of the invention merely uses signals to tell the user that access is refused (by displaying a message and actuating an audible warning device). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention will be better understood after reading the following description and examining the accompanying drawings. The drawings are given exclusively by way of illustrative and non-limiting example of the invention. The figures show: 
       FIG.  1 : one example of a terminal and a microcircuit medium which be used to implement the method of the invention in the transport field, 
       FIG.  2 : a flowchart showing the successive steps of the method of the invention, and 
       FIG.  3 : a more detailed representation of the terminal from FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     This example corresponds to a mode of use in which the terminal controls entry into a controlled area.  FIG. 1  shows:
         a terminal  1  which includes a contactless reader having an antenna  2  under a cover that is transparent to electromagnetic radiation, and   a contactless medium in the form of a smart card  3  incorporating a microcircuit  4  communicating with the outside world via an antenna  5  and optionally a connection interface  6  with electrical contacts.       

     The terminal  1  is in the form of a cabinet alongside a passageway blocked by a three-legged turnstile  9 . The terminal  1  further includes.
         a display  7  and a loudspeaker  8  for imparting information to a user, and   a collection device essentially consisting of a collecting chute  10  into which the user slides or throws the smart card at the invitation of the display  7  and the loudspeaker B.       

     The smart card  3  includes:
         standard means, not shown, for extracting the electrical power required for it to operate from the electromagnetic signal received by its antenna  5 ,   standard means, not shown, for transmitting and receiving data via the antenna  5 ,   a logic circuit  11  for processing the data (for example a microprocessor and an associated program), in particular for effecting a payment operation and securing the data exchanged with the terminal  1 , and   a non-volatile memory  13  containing transaction data.       

     A credit is stored in a portion  14  of the memory  13 . Some credit units are electronically canceled by the circuit  11  to show that their value has been used up. A second portion  15  of the memory  13  contains an identifier, for example the user&#39;s Social Security number. 
       FIG. 2  is a flowchart of one example of the method of the invention. When a user with a smart card  3  approaches the terminal  1 , the contactless smart card reader detects the presence of the microcircuit  4 . This is step  17  in FIG.  2 . When the card  3  receives the signals transmitted by the antenna  2 , it transmits data to the reader in the terminal  1 . 
     In step  18  the reader in the terminal  1  reads the transaction data contained in the memory  13  of the card  3 . The reader then performs a test to determine if the card is valid (step  19 ). The test verifies if the card  3  corresponds to the intended purpose of the terminal  1 : 
     The card  3  may not correspond to the transport company operating the terminal  1 . In this case, the card is refused but is not retained. A message on the screen  7  and a sound signal or message reproduced by the loudspeaker  8  indicate that the card does not authorize access (step  20 ).
         If the card is valid, the reader in the terminal  1  modifies the credit stored in the portion  14  of the memory  13  (step  22 ). It causes the circuit  11  to write data. After this writing, the card may not be valid for a subsequent journey. The reader in the terminal  1  tests whether the card is valid for another journey by comparing the remaining credit to a predetermined amount (step  23 ):
           If the card is still valid for another journey, or another use, the reader authorizes entry/exit (step  24 ). The reader commands the unlocking of a latch which prevents the barrier  9  rotating. It displays on the screen  7  a message  25  indicating that the use of the service has been accounted for and inviting the user to pass through the barrier. The display can be replaced by the lighting of a green lamp or any other visual and/or audible and/or mechanical signal. In this instance, all that remains is for the user to pass through the barrier.   If the card is not valid for another journey, the user is invited to insert the card into the chute  10  to return it to the transport company (message  27 , step  28 ). This is because, in this example, the terminal  1  controls entry to a controlled area and the user is invited to return the card before making the journey. In return the user is issued a ticket  26  indicating the legitimate nature of his situation during the journey. A message on the screen  7  and/or a sound message reproduced by the loudspeaker  8  then indicates that the card must be given up by inserting it into the chute  10  (step  28 ). At the same time, the terminal  1  prepares to retain the card. Meanwhile, the barrier remains locked. A test verifies whether the card has been returned (step  29 ):
               If it has, a message  30  on the screen  7  and/or an audible message reproduced by the loudspeaker  8  invite(s) the user to take the ticket  26  and pass through the barrier  9 . The barrier  9  is then unlocked (step  24 ).   If it has not, the barrier  9  is not unlocked. At the end of a predetermined time the terminal  1  reverts to step  1  to detect the card of another user.   
               
               

     In another mode of use, the terminal  1  controls exit from the con-rolled area. In this case, users are invited to hand in their card at the end of the journey, but there is no need to issue a ticket  26  in exchange. 
       FIG. 3  shows the construction of the terminal  1  in more detail. Its main components include a printer  36 , a contactless reader  31  connected to the antenna  2  and a microprocessor  32 . To prevent entry of foreign bodies into the chute  10 , the chute is provided with an access door  33 . The microprocessor  32  opens the door  33  only when it receives from the reader  31  information indicating the presence of a card  3  whose credit has just been used up and is therefore to be handed in. In all other cases, the door  33  remains closed. 
     For implementing the test of step  29 , the chute  10  has another door  34  further downstream and also controlled by the microprocessor  32 . The door  34  retains in the chute  10  a card  3  or any other object deposited therein. During this time, the nature of the object is tested. To this end, a detector  35  faces the chute  10 , slightly above the door  34 . The detector  35  can be a very simple device, for example an optical or infrared detector. It can also be an antenna of the same type as the antenna  2  and which is coupled to the reader  31  to read the memory  13  of the deposited card.
         If the presence of a card  3  is detected in the chute  10 , the processor  32  authorizes user entry or exit, opens the door  34  and causes the printer  36  to deliver a ticket  26 . All the operations are timed and synchronized so that they can be efficiently perceived by the user.   If no card  3  is detected in the chute  10 , the microprocessor  32  leaves the door  34  closed and does not unlock the barrier  9 . If a foreign object has been inserted, it remains in the chute  10  and the door  33  remains open until a user removes the foreign object and deposits a card.       

     A routing device  37  controlled by the microprocessor  32  can optionally divide cards into two categories. To remedy the insertion of foreign objects, the routing device  37  can also separate cards from other objects thrown into the chute  10 . To this end, the receptacle of the terminal  1  includes two hoppers  38  and  39 . The cards can be stored loose in these hoppers or stacked to facilitate their re-use. 
     In practice the entry slot above the door  33  is shaped to facilitate inserting the card. The opening can be wider than the entry slot of a magnetic stripe reader because its guide function is less precise, to facilitate fast insertion of the card. 
     The two doors  33  and  34  are preferably actuated so that opening of the door  34  is followed a second test by the detector  35  to verify that the card is no longer present before authorizing re-opening of the door  33 . This prevents removal of cards by so-called “fishing” methods. 
     Cards valid for a single journey (single cards) do not need to be recharged and can be recycled without rewriting their memory. The other tickets are recharged by writing a new value into the microcircuit  4 . A secret key is generally required for recharging the microcircuit  4 . The security precautions in respect of the secret key are simpler because the value is recharged only by employees of the company owning the terminal  1 . 
     The recycling mode is preferably adapted to suit particular operating conditions. In the situation where only single cards are recycled and then dispensed automatically, the collected cards are stacked in the hoppers without recharging their value. They are recharged at the time they are sold. For manual distribution to ticket offices of stations equipped with a reader for recharging their value, the cards are stacked in boxes without recharging their value. Their value is recharged at the time they are sold. For distribution by external resellers, who have no means of recharging their value, the tickets have their value recharged by a secure dedicated equipment unit belonging to the transport company. 
     The cards can be stacked any way around, unlike magnetic stripe cards, which simplifies the mechanism in the terminals.