MAGNETIC MARKER AND ITS MANUFACTURING METHOD

摘要

A magnetic marker (1A) comprises a magnetosensitive wire (2) and a magnetic coat (3) covering the magnetosensitive wire (2). The magnetosensitive wire (2) is made of a magnetic material the magnetism of which is steeply inverted when an alternating magnetic field exceeding the coercive force is applied to the material. The magnetic coat (3) is made of a magnetically hard or semihard magnetic material and can impart a bias magnetic field to prevent the magnetic inversion of the magnetosensitive wire (2) to it. The magnetic coat (3) has an alternate of a heat-treated portion (4) and a non-heat-treated high-coercive force portion (5) in the longitudinal direction. The heat-treated portion (4) is given a magnetic property different from the original magnetic property of the magnetic coat by a heat treatment such as annealing.