IC card

Details IC card IC card

1990-11-21

1992-10-20

Shepperd, John W.

Registers

Records

Conductive

235380, 235382, 324428, 324433, G06K 1906, G06K 500, G01N 27416

Patent

active

051572478

ABSTRACT:
An IC card has a data transmission/receiving circuit for exchanging data with an external device, a data processing circuit connected to the data transmission/receiving circuit for processing the data, a battery for supplying the data transmission/receiving circuit and the data processing circuit with electrical power, a charge storage device such as a capacitor charged at a predetermined time constant by the battery, a charge control circuit for controlling connection of the battery to the charge storage device in accordance with a control signal from the data processing circuit, a comparator circuit for comparing the output voltage from the charge storage device with a reference value, and a time measuring counter for measuring the time from electrical connection of the battery to the charge storage device until the comparator circuit detects an output voltage from the charge storage circuit exceeding the reference value.

REFERENCES:
patent: 4785166 (1988-11-01), Kushima
patent: 4794236 (1988-12-01), Kawana et al.
patent: 4800255 (1989-01-01), Imran
patent: 4816656 (1989-03-01), Nakano et al.
patent: 4839597 (1989-06-01), Rowland
patent: 4843224 (1989-06-01), Ohta et al.
patent: 4866389 (1989-09-01), Ryan et al.

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