Chip card with field strength detector having a switch and load

Details Chip card with field strength detector having a switch and load Chip card with field strength detector having a switch and load

1993-07-28

1995-05-23

Shepperd, John

Registers

Records

Conductive

G06K 1907

Patent

active

054183588

ABSTRACT:
The invention relates to a contactless and batteryless chip card having an antenna coil, a transmission and reception stage which via an electromagnetic alternating field generated by a write/read unit on the one hand supplies the chip card with energy and on the other hand ensures bidirectional data transmission to the write/read unit. The chip card in accordance with the invention has a detector for determining the field strength of the electromagnetic alternating field transmitting energy to said chip card. The functions of the user part, which have a high energy requirement to implement them, are only implemented advantageously when the detector has detected a sufficient field strength. This prevents defective or incomplete implementation of energy-consuming functions of the chip card before they are begun. The field strength detector consists of a switch and load in parallel to the coil with the switch controlled by a control circuit to cause the switch to be on only during a measurement cycle. By having the switch on only during the measurement cycle damping of the coil is prevented and the range of the card is extended compared to a card where the load is always in parallel to the coil. The control circuit can also monitor the supply voltage and prevent the measurement cycle if the supply voltage drops below a predetermined value. Such interruption in the measurement cycle prevents the measurement from reducing the supply of energy to the rest of the circuits.

REFERENCES:
patent: 4463353 (1984-07-01), Kuzara
patent: 4546241 (1985-10-01), Walton
patent: 4783658 (1988-11-01), Nakano et al.
patent: 4797541 (1989-01-01), Billings et al.
patent: 4924171 (1990-05-01), Baba et al.
patent: 5013898 (1991-05-01), Glasspool
patent: 5030807 (1991-07-01), Landt et al.
patent: 5113184 (1992-05-01), Katayama
Wigand, W., "Die Karte mit dem Chip Schlussel zu einer Welt neuer Leistungen und Losungen", Siemens-Aktienges., ISBN 3-8009-1573-1 (1991).

Affiliated with

Also associated with

Rating

Chip card with field strength detector having a switch and load does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Chip card with field strength detector having a switch and load , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chip card with field strength detector having a switch and load will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2141488