1. Basic structure：
(1)Probe:
Probe is composed of upper part and down part. The upper part is magnetic field’s sensing part while the down part is magnetic field’s reacting part that is responsible for signal treatment and output.
(2)Rack
It is not only detector’s body but also working platform. The probe is place on rack.
(3)Motor transmission
The motor drives the belt’s roller to run the belt.
(4)Electric cabinet
It is composed of heavy power integrated block, sensitivity control integrated block, signal reception integrated block and signal output integrated block.
2. Operation theory：
The upper and down part of the probe receives and treats the signal; the signal is sensed and scanned by magnetic field and photoelectric scanner respectively. Finally the four integrated blocks (heavy power integrated block, sensitivity control integrated block, signal reception integrated block and signal output integrated block) complete the detection.
