Non-contact transaction system with token presence detection
First Claim
1. A transaction system comprising a first body having stand-by and operative modes, said first body being arranged, in said operative mode, for communication inductively with a second body to effect a transaction, said first body including timing means, operable in said stand-by mode, for energizing circuitry of said first body at predetermined intervals each of a first duration of time, said circuitry including generator means for generating and transmitting radio frequency signals of a second duration less than said first duration, said circuitry also including detection means, said detection means being operable for a third duration of time, the third duration of time being coincident with but not greater than said second period of time, said detection means serving to detect the amplitude of the transmitted radio frequency signals and to cause said first body to switch from said stand-by to said operative mode if the detected amplitude is below (indicating the proximity of a second body) a threshold value whereby communication with said detected second body is enabled.
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Abstract
A transaction system includes a portable electronic token and an external read/write unit which communicate by inductive coupling. The read/write unit transmits short pulses of an r.f. carrier when in its dormant or stand-by mode and, upon detecting the presence of a token, switches its r.f. on continuously to power up the token and conduct a transaction. Thus, the system conserves power but can react rapidly when a transaction is necessary.
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Citations
9 Claims
- 1. A transaction system comprising a first body having stand-by and operative modes, said first body being arranged, in said operative mode, for communication inductively with a second body to effect a transaction, said first body including timing means, operable in said stand-by mode, for energizing circuitry of said first body at predetermined intervals each of a first duration of time, said circuitry including generator means for generating and transmitting radio frequency signals of a second duration less than said first duration, said circuitry also including detection means, said detection means being operable for a third duration of time, the third duration of time being coincident with but not greater than said second period of time, said detection means serving to detect the amplitude of the transmitted radio frequency signals and to cause said first body to switch from said stand-by to said operative mode if the detected amplitude is below (indicating the proximity of a second body) a threshold value whereby communication with said detected second body is enabled.
Specification