DATA TRANSFER SYSTEM AND DEMODULATOR THEREFOR

摘要

PROBLEM TO BE SOLVED: To properly transfer data with simple device configuration without requiring high processing ability in a non-contact data transfer system. SOLUTION: A data transfer circuit is provided with a reading device which adds a coil 4 and a voltage source 27 applying a voltage on a control circuit and the coil 4 by a carrier frequency and a key 2 which adds a coil 3 receiving energy from the coil 4 by magnetic coupling and also transmitting data to the coil 4 and the control circuit 8. The reading device adds a demodulating circuit 31, a sample-and-hold circuit 35 and a delay control unit 38 for controlling the sampling of the voltage to be executed by the carrier frequency. Average circuits 60 and 61 provide an average sample voltage signal to one input 59 of a comparator 58, the other input 57 of the comparator 58 is coupled with the output of the sample-and-hold circuit 35 and the comparator 58 obtains the output which indicates sample voltage change.