Verifying device for a key card
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United States of America Patent
Stats
-
Dec 16, 1986
Grant Date -
N/A
app pub date -
Nov 30, 1983
filing date -
Dec 3, 1982
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A verifying device for a key card on which a magnetic signal is recorded is formed of a set card on which a predetermined reference magnetic signal is recorded, a magnetic sensor consisting of a saturable core and a winding wound thereon, an oscillator for supplying a voltage to said winding, a switching element connected to the winding, a power source connected between both ends of the switching element, and an output terminal led out from one of both ends of said switching element. In this case, the saturation magnetic field of the saturable core is so selected that it is larger than the magnetic field itself generated from the reference magnetic signal recorded on the set card in absolute value but smaller than the sum magnetic field of those from the set and key cards in absolute value when the key card is a correct card, so that when the correct key card is inserted into the device to be verified with the set card, the sum magnetic field becomes larger than the saturation magnetic field of the saturable core in absolute value, hence the saturable core is saturated, no output appears at the winding, thus said switching element is turned off and an output indicating that the key card is coincident with the set card is produced at the output terminal.
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