Nhk Spring Co., Ltd.

Tatsuya Kurihara

Hidekazu Hoshino

Itsuo Takeuchi

Masumi Yoda

Hajime Arai

Yoshiki Ono

Minoru Komiya

Tsukasa Higashi

Shigemi Sato

Sumikazu Oki

A magnetic marker comprises a magnetically switchable wire and a magnetic casing that covers the magnetically switchable wire. The magnetically switchable wire is formed of a magnetic material that undergoes occurrence of sharp magnetic inversion when an alternating field of intensity higher than its coercive force is applied to it. The magnetic casing is formed of a magnetically hard or semihard magnetic material and can apply a bias magnetic field to the magnetically switchable wire to prevent magnetic inversion of the magnetically switchable wire. Heat-treated portions and high-coercivity regions, which are not heat-treated, are formed alternately in the longitudinal direction on the magnetic casing. The heat-treated portions are given magnetic properties different from magnetic properties essential to the magnetic casing by heat treatment such as annealing.

Magnetic marker and manufacturing method therefor

A pulse generating element formed of a switchable magnetic wire is worked so as to have an arcuate shape such that the ratio R/d between the radius of curvature R and diameter d of the wire in a state free from external force ranges from 65 to 95. This is achieved by subjecting a wire of a ferromagnetic material, such as Fe--Co--V, to drawing-bending work. The pulse generating element, which is obtained by cutting the switchable magnetic wire to a predetermined length, is restricted to a substantially straight state by a retaining member, and undergoes a drastic flux reversal when it is subjected to an alternating field.

Pulse generating element and a method and an apparatus for manufacturing

An object to be checked contains a large number of magnetic polymer elements scattered at random. Each of magnetic polymer elements is made up of an element main body formed of a high molecular material, and magnetic metal powder contained in the element main body. The magnetic polymer elements are integrally incorporated in paper and tangled with the wood pulp fibers of the paper three-dimensionally. In the manufacturing process of the object, a processing apparatus magnetically scans the magnetic polymer elements incorporated in the scanning region of the object while moving the scanning region at a predetermined speed, converts a detection signal obtained by the magnetic scan into a cipher code, and records the cipher code in a code indicator section. In the authenticity checking process, the processing apparatus magnetically scans the magnetic polymer elements once again, and a detection signal obtained thereby is collated with the cipher code recorded in the code indicator section. When the detection signal and the cipher code agree with each other, the object is determined as being authentic.

Objects to be checked for authenticity, and method and apparatus for

A number of bistable magnetic devices are dispersed in a scanning region of a checking object. Each bistable magnetic device is formed of a nonmagnetic material which undergoes a drastic flux reversal attributable to the Large Barkhausen effect when subjected in succession to first and second external magnetic fields of opposite directions. A processing apparatus comprises magnetic generators for generating magnetic fields of opposite directions, a transportation mechanism for moving the checking object at constant speed, and a coil for detecting magnetic pulses, which are generated as the bistable magnetic devices are subjected to the flux reversal, as changes of electromagnetic induction voltage. A detection signal for the scanning region detected by the apparatus is converted into a cipher code and then recorded in a code indicator section of the checking object. In checking the authenticity of the object, the detection signal obtained by scanning the scanning region and a code for collation obtained by decoding the cipher code recorded in the code indicator section are compared, and it is concluded that the checking object is real when the detection signal and the collation code correspond to each other.

Method and apparatus for checking the authenticity of a checking object

Checking objects including bistable magnetic devices, to be checked for

A number of high-permeability magnetic elements are dispersed in a scanning region of a checking object. A core of a processing apparatus is provided with an exciting coil and a sensor coil. When a bias magnetic field is applied to the core, and the scanning region is passed in the vicinity of a gap, the permeability of the gap varies depending on the density of the magnetic elements, so that a magnetic flux passing through the core changes. A detection signal corresponding to the change of the magnetic flux is detected by means of the sensor coil. This detection signal is converted into a cipher code and then recorded in a code indicator section of the checking object. In checking the authenticity of the object, a detection signal obtained by scanning the scanning region by means of the processing apparatus and a code for collation obtained by decoding the cipher code recorded in the code indicator section are compared, and it is concluded that the checking object is real when the detection signal and the collation code correspond to each other.

Method and an apparatus for checking objects to be checked for

An object to be checked has a scanning region which contains a large number of magnetic elements scattered at random. Each of the magnetic elements is made up of an element main body formed of a high molecular material, and magnetic metal powder contained in the element main body. A processing apparatus employed for checking whether or not the object is authentic has a magnetic sensor which is made up of a pair of MR elements and a magnet. The MR elements are arranged side by side in the direction in which the scanning region is scanned. In the manufacturing process of the object, a detection signal which is based on variations in the output ratio between the MR elements is produced, with the scanning region of the object being moved. The detection signal is converted into a cipher code, and this cipher code is recorded in a code indicator section. When the object is checked for authenticity, a detection signal obtained by scanning the scanning region is collated with the cipher code recorded in the code indicator section. When the detection signal and the cipher code agree with each other, the object is determined as being authentic.

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Yokohama, Japan

Tatsuya Kurihara