Matsushita Electric Industrial Co., Ltd.

Other

Yoshihiro Tosaki

Hiromichi Shimada

Shinichi Tanaka

Masaru Odagiri

Toshio Fukazawa

Kumiko Wada

Toshiaki Kunieda

Tomiharu Hosaka

Yuji Nagata

Ken Takahashi

Akio Murata

Sayuri Muramatsu

Katsuyuki Takahashi

Shinji Inoue

Satoru Mitani

Akio Kuroe

Akira Matsubara

Tsutomu Kai

Yukako Doi

Masatoshi Taniguchi

Terumi Yanagi

Tomoyuki Hase

Yoshiyuki Takase

Noriko Kobayashi

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 DVD player, when data information in a DVD disk is played back, it is judged whether the data information is protected by a copyright or not on the basis of disk control information. Further, it is judged whether the DVD disk is writable or not, based on whether the DVD disk is provided with a wobble or not. Thus, if the data information is protected by the copyright and the DVD disk is writable, a playback of the DVD disk is prevented so that an illegal use of the DVD disk, which infringes the copyright, is effectively prevented.

Optical disk, method of reproducing and copying optical disk, and method of preventing illegal use of optical disk

A DVD-R has a main information area where data information is recorded in a track having a wobble, and first and second control data areas each of which is disposed in an inner space closer to the disk center than the main information area . The information structure and physical structure of the first control area are different from those of the second control area . In the second control area , predetermined physical format information and disk production information, for example, the last address of when data is written in the DVD-R , the maximum transfer rate or the like, are recorded. Thus, when the DVD-R is reproduced by a DVD player etc., the physical format information and disk production information etc. recorded in the second control data area are read. Thereby, the disk can be precisely identified without spoiling the physical format information, the disk production information or the like, and further illegal use of the DVD or another optical disk leading up to breach of the copyright can be effectively prevented.

Recordable optical disk

A write-once DVD has a lead-in area provided inside a data area where digital information on a document, image sound or the like is recorded, which includes prepits holding copy managing key information for preventing unauthorized copy from a source disk to the DVD . The DVD has also a test area provided inside the lead-in area , which is used for adjusting the power characteristics of the DVD . In the DVD , information recorded in the source disk can be. physically prevented from being copied into the DVD without good cause on the basis of the copy managing key information recorded in the prepits

Optical disk and optical disk drive

A DVD-R has a main information area where data information is recorded in a track having a wobble, and first and second control data areas each of which is disposed in an inner space closer to the disk center than the main information area The information structure and physical structure of the first control area are different from those of the second control area In the second control area predetermined physical format information and disk production information, for example, the last address of when data is written in the DVD-R the maximum transfer rate or the like, are recorded. Thus, when the DVD-R is reproduced by a DVD player etc., the physical format information and disk production information etc. recorded in the second control data area are read. Thereby, the disk can be precisely identified without spoiling the physical format information, the disk production information or the like, and further illegal use of the DVD or another optical disk leading up to breach of the copyright can be effectively prevented.

A DVD-R has a main information area where data information is recorded in a track having a wobble, and first and second control data areas each of which is disposed in an inner space closer to the disk center than the main information area . The information structure and physical structure of the first control area are different from those of the second control area . In the second control area , predetermined physical format information and disk production information, for example, the last address of when data is written in the DVD-R , the maximum transfer rate or the like, are recorded. Thus, when the DVD-R is reproduced by a DVD player etc., the physical format Information and disk production information etc. recorded in the second control data area are read. Thereby, the disk can be precisely identified without spoiling the physical format information, the disk production information or the like, and further illegal use of the DVD or another optical disk leading up to breach of the copyright can be effectively prevented.

A DVD-R has a main information area where data information is recorded in a track having a wobble, and first and second control data areas each of which is disposed in an inner space closer to the disk center than the main information area The information structure and physical structure of the first control area are different from those of the second control area In the second control area predetermined physical format information and disk production information, for example, the last address of when data is written in the DVD-R , the maximum transfer rate or the like, are recorded. Thus, when the DVD-R is reproduced by a DVD player etc., the physical format information and disk production information etc. recorded in the second control data area are read. Thereby, the disk can be precisely identified without spoiling the physical format information, the disk production information or the like, and further illegal use of the DVD or another optical disk leading up to breach of the copyright can be effectively prevented.

Metal-containing azo compound and optical recording media

The optical recording medium includes at least a recording layer, a recording supplemental layer, a reflection layer and a protection layer on a light permeable substrate, each of the recording layer and the recording supplemental layer is made mainly of an organic pigment material, with the optical recording medium, recording and reproducing is possible using a laser beam having a wavelength of &lgr; and also recording and/or reproducing is possible using a laser beam having a wavelength of &lgr; which is shorter than &lgr; a spectral absorbance of the recording layer is in the range between 5% and 35% at a wavelength of &lgr; and not less than 15% at a wavelength of &lgr; and the recording supplemental layer has a peak of spectral reflectance at a wavelength in the vicinity of &lgr;

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Osaka, Japan

Yoshihiro Tosaki