PURPOSE: To provide a sheet material supply managing system in which a deci sion can be made whether a correct number of sheets are fed regardless of the material or the thickness of the sheet when sheet materials, e.g. print papers, are fed sequentially to a printer or the like while suppressing the effect of disturbance, e.g. noise or vibration, and enhancing reliability in decision.
CONSTITUTION: Ultrasonic wave is transmitted from a transmitter 3 in the way of supply of a sheet material 1 and transmitted ultrasonic wave is received by a first receiver 5 which then produces a measurement phase signal corresponding to the phase of the transmitted wave. On the other hand, direct ultrasonic wave is received by a second receiver 7 which then produces a reference phase signal corresponding to the phase of the direct wave. When the phase difference between the transmitted wave and the direct wave obtained, respectively, from the measurement phase signal and the reference phase signal is within a predetermined range, a decision circuit section 20 makes a decision that a correct number of sheets are fed.
SUGANO ISAO
IZUMI KENKICHI
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