Patent ID: 7378674

Claim:
A magnetic verification system used in a bill acceptor and adapted for verifying the authenticity of the bill inserted into said bill acceptor, said magnetic verification system comprising: a magnetic induction circuit, a signal amplifying and regulating circuit comprising a D/A (digital-to-analog) converter, and a magnetic field generating circuit for generating a reference magnetic field in response to a preset reference value input by a user, said reference magnetic field being sensed by said magnetic induction circuit to generate a magnetic field reference value, wherein said signal amplifying and regulating circuit and said magnetic field generating circuit are connected to a microprocessor, wherein said signal amplifying and regulating circuit comprises a D/A (digital-to-analog) converter, wherein said magnetic induction circuit comprises a magnetic device adapted for scanning the magnetic ink of the bill to be verified and to output a magnetic field signal value, and wherein said magnetic induction circuit is adapted to write the magnetic field reference value generated in response to said reference magnetic field generated by said magnetic field generating circuit into said D/A converter, for enabling said D/A converter to adjust the light intensity of light being emitted by a LED (light emitting diode) of said signal amplifying and regulating circuit onto a photoresistance of said signal amplifying and regulating circuit when said magnetic device has scanned said reference magnetic field, so as to cause said photoresistance to change the resistance thereof subject to the intensity of light from said LED, an so that an operational amplifier at an output end of said magnetic induction circuit obtains a correct magnetic field signal value after scanning an inserted bill to verify the authenticity of the inserted bill.