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Browse Prior Art Database

Externally Powered Semiconductor Transponder

IP.com Disclosure Number: IPCOM000089642D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Dillon, BC: AUTHOR [+3]

Abstract

The feature described herein is an identification card, credit card or similar device which embodies a semiconductor circuit radio frequency (RF) coupled to a sensing mechanism for power and readout.

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Externally Powered Semiconductor Transponder

The feature described herein is an identification card, credit card or similar device which embodies a semiconductor circuit radio frequency (RF) coupled to a sensing mechanism for power and readout.

As indicated in the above figure, the card comprises a base 1 having a circuit mounted thereon. The circuit may be in the card material or be otherwise protected, and may comprise a master slice chip 2 which will contain all of the logic needed for the card functions, a shift register 3 and a decoupling capacitor
4. The logic chip 2 will control the operation of the shift register to transmit a coded identification signal to external circuitry.

There is no power supply on the card so external power is needed. This external power is inductively coupled to the chip 2 by a coupler winding 5 which will be inductively coupled to a corresponding winding in the card sensor so that an RF energization of the windings will supply power to the chip 2. When the power supplied to the chip 2 is up to a given level, chip 2 will start shifting the data out of shift register 3 and will drive a readout coil winding 6, which is also inductively coupled to a pickup coil in the reading device. A shield 7 is used to isolate the readout coil winding 6 and the logic circuits 2, 3 from the power winding 5.

This type of card system may be used as an identification or charge card, or it can be used as a key to enable access to restricted areas. By i...