MAGNETIC TAG EXECUTING ACOUSTIC OR MAGNETIC INQUIRY

摘要

PROBLEM TO BE SOLVED: To provide a simple and inexpensive magnetic tag by providing an element made of a soft magnetic body material and a means for forming an ununiform magnetic field around the element. SOLUTION: Plural cantilevers 20 formed from the thin pieces of a ferromagnetic body provided with low coercivity even though it is highly magnetic known as the soft magnetic body material are provided. The respective cantilevers 20 are constituted so as to resonate at a prescribed resonance frequency. The cantilevers 20 are positioned near the means for supplying the ununiform magnetic field H(x) around one or more elements and assembled. A magnetic field supply means is formed from the hard magnetic material and composed of the magnetized ferromagnetic body 21 like cobalt or iron. The assembly resonates at a frequency proportional to the thickness of the cantilevers 20 and inversely proportional to the square of the length and resonance vibration generated as a result generates a time fluctuation magnetic field inside the cantilevers 20. The size of generated magnetic signals is raised by placing the element of the cantilevers 20 inside a Helmholtz resonator.