| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a conducting foreign body detection apparatus capable of surely detecting not only a magnetic substance but also a fine non-magnetic conducting strip by a simple apparatus configuration. <P>SOLUTION: A first coil 11 composing a first LC oscillation circuit 10 for detecting a change of a frequency corresponding to a conducting strip in fluid and a second coil 21 composing a second LC oscillation circuit 20 are wound around the outer periphery of a pipe 1. A filter amplifier circuit 30 for generating a rectangular wave of a differential frequency of both detected frequencies from a beat-wave generated by superposing both the detected frequencies is connected to the first LC oscillation circuit 10 and the second LC oscillation circuit 20. An arithmetic processing unit 40 for counting and digitizing the frequencies of the rectangular wave, analyzing a frequency value in each determination time band based on the flow rate of fluid in which the conducting strip passes the first coil 11 and the second coil 21, using the analyzed value as a detection value, and when the detection value exceeds a preset threshold, outputting a conducting strip detection signal is connected to the filter amplifier circuit 30. An alarm is generated from a display unit 50 based on the conducting strip detection signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
