| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal detecting apparatus capable of stably and reliably checking missing parts. SOLUTION: In the metal detecting apparatus, an AC magnetic field corresponding to a reference signals is generated to detect changes in the magnetic field caused by the passage of an object W to be inspected through the magnetic field and determine whether components including metal bodies or metal components in the object W are missing or not. The metal detecting apparatus is provided with phase setting means 26a and 31b and frequency setting means 31c and 33. The phase setting means 26a and 31b set one phase on a plurality of different frequencies of the reference signals in such a way that the degree of article effects of the object W in magnetic field detection signals may be in the vicinity of maximum. The frequency setting means 31c and 33 acquire both a detection signal of a magnetic field detecting means 23 when the object W is passed through the generated magnetic field under the set phase and a detection signal when a sample of missing parts is passed through the generated magnetic field, selects such a frequency that the ratioαof the detection signal of the object W to the detection signal of the sample of missing parts may be maximum, and sets a reference signal frequency on the plurality of frequencies. COPYRIGHT: (C)2006,JPO&NCIPI |
