Contactless battery charging device and process

1. A process of recharging a battery ( 19 ) in a portable object ( 1 ) communicating with a reader establishing communication over a modulated electromagnetic field that further enables powering of the portable object, the portable object furthermore having a rechargeable battery the process comprising:

operating the portable object to send at least one waiting message to the reader, the waiting message telling the reader a waiting time (WTXM) before the next message; and

operating the portable object to use the energy of the electromagnetic field to recharge the battery during the waiting time.

2. The process according to claim 1 , further operating the portable object to send at least one adjustment message ( 210 - 203 ) to the reader to adjust the power of the electromagnetic field.

3. The process according to claim 2 , in which the adjustment message is a message of the same type as the waiting message, which has a shorter waiting time.

4. The process according to claim 2 , in which the portable object is operated to send several adjustment messages until the electromagnetic field reaches a power level matching the desired power level to charge the battery.

5. The process according to claim 1 , in which the communicating portable object and the reader comply with ISO standard 14443 and in which the waiting messages are S-Block (WTX) type messages having a significant waiting time.

6. The process according to claim 2 or 5 , in which the adjustment message is an S-Block(WTX) type message, which has a shorter waiting time than a waiting message.

7. A portable object ( 1 ) communicating over a modulated electromagnetic field with a reader, the portable object comprising:

a means of recovering energy ( 18 ) from the electromagnetic field;

means of communication ( 11 ) in order to demodulate and modulate messages over the electromagnetic field;

means of processing ( 10 );

a battery ( 19 ) allowing the means of processing to operate outside the electromagnetic field;

a means of recharging the battery during which the means of processing ( 19 ) sends ( 209 ) at least one waiting message to the reader, the said waiting message telling the reader a waiting time before the next message; and

means whereby the portable object uses the energy of the electromagnetic field to recharge the battery during the waiting time.

8. The portable object of claim 7 wherein the means whereby the portable object uses the energy of the electromagnetic field to recharge the battery during the waiting time is further operable to shut down other components of the portable object during the waiting time thereby making additional power available for recharging the battery.

9. The process of recharging a battery ( 19 ) in a portable object ( 1 ) of claim 1 further comprising:

shutting down other components of the portable object during the waiting time thereby making additional power available for recharging the battery.

10. A portable object communicating over a modulated electromagnetic field with a reader, the portable object comprising:

an electromagnetic-field energy-receiving circuit;

a battery allowing the means of processing to operate outside the electromagnetic field;

a power supply circuit connected to the electromagnetic-field energy-receiving circuit and connected to the battery;

a processor connected to the power supply circuit operable to direct the power supply circuit to cause energy received from the electromagnetic-field energy-receiving circuit to be used to recharge the battery during a recharging period defined by a waiting period transmitted by the processor to the reader, the said waiting message telling the reader a waiting time before the next message.

11. The portable object communicating over a modulated electromagnetic field with a reader of claim 10 wherein the power supply circuit is further operable to shut down other components of the portable object during the waiting time thereby making additional power available for recharging the battery.