Nkk Corporation

Pioneer Electronic Corporation

Seigo Ando

Katsuyuki Nishifuji

Nippon Telegraph and Telephone Corporation

Ntt Electronics Corporation

Yasuhiro Matsufuji

Kenichi Iwanaga

Masaki Takenaka

Hiroshi Maki

Yoshihiro Murakami

Hiroshi Ito

Takato Furukawa

Mamoru Inaba

Bonpei Inaba

Atsuhisa Takekoshi

Atsuhisa Takeoshi

A current of predetermined frequency is fed to a coil wound around a ferromagnetic core through a fixed impedance means. A magnetic flux measurement is performed in terms of a level of a DC component of a voltage generated across the coil. A DC bias is added to the current of predetermined frequency, and the resultant current is applied through the fixed impedance means to the coil wound around the ferromagnetic core. A magnetic flux measurement is performed in terms of a level of a DC component of the voltage across the coil. A magnetic flux measuring method and apparatus for embodying the same have a high sensitivity in detecting a minute magnetic flux and an improved temperature characteristic because an output voltage little varies against a temperature variation. A magnetic flux measuring method and apparatus for embodying the same, when they are applied to a leakage flux flaw detection using a saturable magnetic flux sensor, is capable of expanding a measuring span of the magnetic flux sensor, thereby to improve a flaw detection performance.

Magnetic flux measuring method and apparatus for detecting high

Method and apparatus for magnetically detecting defects in an object

A magnetic inspection apparatus includes a magnetizer which generates a magnetic field in an object to be inspected, the object running in a predetermined direction, the magnetizer including a pair of magnetic poles provided in facing relation to the object, the pair of magnetic poles being arranged in the predetermined direction; a plurality of magnetic sensors arranged at small intervals in a widthwise direction of the object perpendicular to the predetermined direction, for detecting a leakage magnetic flux due to a defect of the object at locations in the widthwise direction, each magnetic sensor having sides which face the magnetic poles; a plurality of subtraction circuits, each calculating a difference signal between output signals from those ones of the magnetic sensors which are separated by a predetermined distance; a plurality of absolute value circuits, each calculating an absolute value of each difference signal output from each subtraction circuit; and an arithmetic operation circuit which evaluates the defect of the object on the basis of the absolute value signal output from each absolute value circuit, with the relationship between a distance E (unit=mm) between the magnetic sensors associated with the output signals subjected to subtraction in each subtraction circuit and a distance L (unit=mm) between each magnetic sensor and the object being defined by 17&lt;EL&lt;78.

Apparatus for magnetic inspection using magnetic shield, with specific

Apparatus for magnetic inspection using magnetic shield

Saturable core magnetometer with a parallel resonant circuit in which

Magnetic inspection apparatus for thin steel strip having magnetizer and

Karaoke is provided more easily and flexibly by recording video signals from multiple video sources on a disk; selecting one of those sources as desired; and reproducing the signals from that source along with either the output of a video camera or graphics data. The graphics data is recorded on the disk with the video source signals in multiplexed fashion, along with selection signals. When the multiplexed signals are demultiplexed, chroma-key composite circuitry effects desired superimposition of a video camera output on the source video signals.

Recording medium playing apparatus

A current measuring method in which a magnetic sensor is a torodial core having a conductor for carrying a current to be measured passing through the hollow portion of the toroid. A coil on the core is excited with an AC voltage such that the positive and negative voltages induced in the coil are equal in amplitude when the conductor is not carrying current. Current in the conductor generates a change in magnetic flux which change is measured by detecting the algebraic sum of the amplitudes of the positive and negative voltages. Simultaneously, the amplifier output is applied to the input side of the AC voltage or a second coil disposed in the magnetic sensor so as to establish a magnetic equilibrium. Current measuring apparatus according to this invention include two types of apparatus composed of hardware to which the above-mentioned current measuring method is applied.

Current measuring method and apparatus therefor

Growing community of inventors

Tokyo, Japan

Seigo Ando