Matsushita Electric Industrial Co., Ltd.

Sayuri Muramatsu

Akio Murata

Akio Kuroe

Ken Takahashi

Hirotsugu Fusayasu

Yoshihiro Tosaki

A conductive wire held between a first magnetic core of a soft magnetic film and a second magnetic core, the area of the cross-section, perpendicular to a magnetic path, of which is made partially smaller constitutes a magnetic detection device, and a DC current for generating a DC bias magnetic field and a high-frequency carrier signal are let to flow through the conductive wire. The DC current is selected so that the portion at which the cross-sectional area of the above-mentioned second magnetic core is made smaller has an appropriate DC bias magnetic field intensity. When this magnetic detection device is placed in an external magnetic field, the intensity of the DC bias magnetic field changes depending on the intensity of the external magnetic field; hence, the level of the carrier signal in the conductive wire changes. The change of the level of the carrier signal is output as the change of an electrical signal, whereby the intensity and direction of the magnetic field are detected.

Magnetic sensing element, magnetic sensor, and its manufacturing method

In order to obtain a magneto-impedance type magnetic sensor having a soft magnetic film facing to a conductive nonmagnetic film, and available a large impedance change with a carrier signal at a relatively low frequency, the magnetic sensor comprises a meander type conductive nonmagnetic thin film of zigzag shape formed with at least one pair of electrode terminals at both ends and a soft magnetic film which is strip-shaped so as to face thereto at a plurality of regions and has an easy axis of magnetization in a width direction of the strip shape, a high frequency carrier signal is applied to the above-mentioned electrode terminals and further a direct current bias magnetic field is applied. By performing AM detection of an AM modulation signal output from the above-mentioned electrode terminals, an impedance change of the conductive nonmagnetic film which is changed by external magnetic field is detected as a change of the high frequency carrier signal, thereby the external magnetic field can be detected.

Magnetic sensor having a closed magnetic path formed by soft magnetic films

In a high-frequency impedance type magnetic head having high impedance and capable of efficiently detecting a change in impedance, an electrically conductive metal film is sandwiched between two soft magnetic films, and the two soft magnetic films form a portion of a magnetic path. The thickness of one soft magnetic film is smaller than the thickness of the other soft magnetic film. The electrically conductive metal thin film has a pair of electrodes at respective ends thereof, to which are connected an oscillator for applying a high frequency carrier signal to the electrodes and a high frequency amplifier having a demodulator circuit. Further, an electrically conductive metal film winding is provided, and a DC current is applied to the electrically conductive metal film winding at the time of reproduction, while on the other hand, a signal current is applied to the electrically conductive metal film winding at the time of recording.

Magnetic head

Magnetic sensing apparatus having a central core with wire therethrough

A shielded magnetic head includes a magnetically shielded gap and first to fourth conductive magnetic films disposed in the gap. The first to fourth conductive magnetic films, each extending parallel to a tip face of a magnetic head to be opposed to a magnetic recording medium, are aligned at a distance from one another in a direction perpendicular to the tip face so as to be away from the tip face in ascending order and connected to one another so as to form a bridge circuit. The distance between the first conductive magnetic film and the tip face is set so that a signal magnetic field from the magnetic recording medium is applied to the first conductive magnetic film. By canceling impedance components that do not vary depending on a magnetic field, the shielded magnetic head detects only impedance components that vary depending on a signal magnetic field.

Shielded magnetic head and magnetic reproducing apparatus

A magnetic head unit of the present invention is provided with a magnetic head having a magnetic impedance element, and a head suspension for suspending the magnetic head is provided with a matching transmission line of one-fourth wavelength for transmitting a high-frequency signal output from the magnetic head.

Magnetic head apparatus including a quarter wavelength transmission line

A magnetic head includes a first, second and third magnetic core of a soft magnetic film formed by a thin film forming method. One end of the first and second magnetic core face a magnetic recording medium and are disposed with a predetermined distance therebetween. The third magnetic core is disposed between the first and second magnetic cores. A conductive coil is wound around the third magnetic core. A conductive wire passes through the third magnetic core and is insulated therefrom. A DC-biased high-frequency constant current flows through the conductive wire to reproduce information recorded on the magnetic recording medium. Also, a recording signal is applied to the conductive coil.

Growing community of inventors

Hirakata, Japan

Sayuri Muramatsu