DETECTION OF DISTANCE BETWEEN ELECTROMAGNETIC TRANSPONDER AND TERMINAL

Japanese Patent JP3293610

B2

PROBLEM TO BE SOLVED: To measure distance to a terminal on a transponder side by comparing DC voltage level information when an oscillation circuit being arranged on the upstream side from the DC voltage rectification means of a transponder is tuned or detuned from a fixed frequency.
SOLUTION: The transponder 30 is provided with an inductance L2 and a capacitor C2 between terminals 11 and 12 as an oscillation circuit. The voltage of a capacitor Ca is subjected to single half-wave rectification by a diode D. A reference voltage 15 corresponds to the negative terminal of the capacitor Ca that is connected to the terminal 12. A DC supply voltage Va is inputted to input DET being connected to the microprocessor of an electronic block 31. A capacitor C3 is connected in series with a switch K1 and is located between the terminals 11 and 12. When the transponder 30 is in a terminal region, power is supplied, the transistor K1 is turned on, and an oscillation circuit is turned for recharging the terminal DET. After that, the transistor K1 is turned off, and the circuit is detuned and the terminal DET is recharged again. The two DC voltage values are compared and are stored at a single bit.

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Luk Vidal

JP2000106524A

June 17, 2002

April 07, 2000

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STMicroelectronics Society Anonymous

B42D15/10; G01S13/74; G06K7/00; G06K17/00; G06K19/00; G06K19/07; G08C17/00; H01Q7/00; (IPC1-7): G01S13/74; B42D15/10; G06K17/00; G06K19/00; G06K19/07

JP85731A
JP8191259A
JP10285087A
JP200134718A

Keiichi Yamamoto

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