Patent ID: 8018321

Claim:
A baggage management gate comprising: an exciting coil that forms an alternating magnetic field in a passage to an area from which manages objects to be carried in or carried out; a detecting coil that detects a variation in the alternating magnetic field when magnetization of a magnetic material showing a large Barkhausen effect is reversed in the alternating magnetic field; and a signal processing unit that determines as to whether the magnetization reversal occurs in the alternating magnetic field due to the large Barkhausen effect or not, based on a signal detected by the detecting coil, the signal processing unit including a plurality of amplifiers, each amplifier amplifying the signal detected by the detecting coil with a different amplification factor and outputting the amplified signal with the different amplification factor to a central processing unit, wherein the detecting coil includes a first detecting coil that is provided on one side of the passage and a second detecting coil that is provided on the other side of the passage, a signal detected by the first detecting coil is amplified with a first amplification factor, a signal detected by the second detecting coil is amplified with a second amplification factor that is lower than the first amplification factor, and the signal detected by the first detecting coil is amplified with a third amplification factor that is lower than the second amplification factor.