| 摘要 |
PURPOSE:To enable the efficient operation by a simple constitution by flowing a detecting current which is smaller than a main current in a coil for demagnetization and detecting a magnitude of the detecting current which changes by an approach of an object to be demagnetized so as to change the current to be flowed in the demag netization coil into the main current. CONSTITUTION:When an object to be demagnetized does not exist, a detecting current supplying means 3 of a demagnetizer 1 flows a detecting current Ip which is smaller than a main current I in a coil 2 and a relatively weak alternating field if produced. Under such condition, when an object to be demagnetized approaches to the demagnetizer 1, an inductance of the coil 2 changes and the detecting current Ip decreases. This decrease is detected by a detecting means 4 and a switching means 5 operates to change the current to be supplied to the coil 2 into the main current I and an usual demagnetizing process is carried out. At this time, a timer 6 operates to supply the detecting current Ip to the coil 2 again after the predetermined preset time necessary for the demagnetizing process. Also, an automatic stop circuit 25 is connected and if a work is separated away from the demagnetizer, that is detected automatically and the supply of main current I can be stopped by switching the coil 2 into the weak excitation side. |
