Patent ID: 6978937

Claim:
An information reading apparatus comprising: a signal acquiring unit for acquiring from a medium, a signal containing binary digit information having a predetermined information length and an arrangement; an elemental frequency extracting unit for extracting an elemental frequency corresponding to an elemental unit length of the binary digit information of the information length from the acquired signal; a band limiting unit for limiting a frequency band of the acquired signal based on the extracted elemental frequency information; a timing point extracting unit for extracting a timing point which is in synchronism with the acquired signal and has the elemental frequency, based on the acquired signal and the elemental frequency information; an amplitude extracting unit for extracting an amplitude value of a signal from the band limiting unit in accordance with the timing point extracted by the timing point extracting unit; a tri-state value generating unit for generating tri-state value data from the amplitude value extracted by the amplitude extracting unit in accordance with the timing point; and a reading unit for reading a ratio of the binary digit information to the information length by calculating the tri-state value data generated by the tri-state value generating unit.