Patent ID: 6348697
Filing Date: 2002-02-19
Classification: B65H,G01V

Abstract:
A media detection method using an optical sensor for detecting reflected light of emitted light, and a differential amplifier having a detection signal input terminal for receiving an output of the optical sensor and a reference input terminal for receiving a reference input voltage, to detect a presence of a medium to be detected based on an output from the optical sensor, said method comprising the steps of:obtaining an output of said differential amplifier with the reference input terminal set at 0 volts, said differential amplifier being responsive to an output of said optical sensor when or where no medium is present; applying the obtained output of said differential amplifier to a predetermined formula so as to compute a value of voltage to next be applied to the reference input terminal of said differential amplifier; and when actually detecting a medium, applying the computed value of voltage to the reference input terminal of said differential amplifier while applying the output from said optical sensor to the signal input terminal of said differential amplifier such that the output of said differential amplifier is compared with a predetermined threshold to judge a presence or absence of a medium.