| 摘要 |
PROBLEM TO BE SOLVED: To detect overlap of sheet-like articles with excellent accuracy even when the articles are special paper such as cardboard with large ultrasonic attenuation factor. SOLUTION: The amplification factor GA of a second amplifier AMP2 is changed while one paper sheet 4 to be fed is held between an ultrasonic transmitter 1 and an ultrasonic receiver 2. If the output value AP2 from the second amplifier AMP2 reaches AP2≈V2s during the time, the output from the second amplifier AMP2 is set to be the monitoring output for detecting overlap, and the amplification factor GA at the time is defined to be the amplification factor for detecting overlap. Unless AP2≈V2s, the amplification factor GA is again changed. If the output value AP3 from a third amplifier AMP3 reaches AP3≈V3s during the time, the output from the third amplifier AMP3 is set to be the monitoring output for detecting overlap, and the amplification factor GA at the time is defined as the amplification factor for detecting overlap. COPYRIGHT: (C)2009,JPO&INPIT
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