OPTICAL INFORMATION RECORDING/REPRODUCING APPARATUS

PROBLEM TO BE SOLVED: To solve the problem of a disk-flaw caused by a collision due to a reduced working distance between an objective lens and a disk bearing body when NA(numerical aperture) of the objective lens is increased for achieving a high-density of optical disk, which requires a method for...

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Bibliographische Detailangaben
Hauptverfasser: MORI MASANARI, NISHINO SEIJI
Format: Patent
Sprache:eng
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Zusammenfassung:PROBLEM TO BE SOLVED: To solve the problem of a disk-flaw caused by a collision due to a reduced working distance between an objective lens and a disk bearing body when NA(numerical aperture) of the objective lens is increased for achieving a high-density of optical disk, which requires a method for precisely detecting the collision of the disk bearing body with the objective lens. SOLUTION: The difference between an electrical output from a total sum of a control signal detection region and a signal reading detection region on a photo detector which receives reflected light from the disk bearing body or from a part of these regions and an electrical output from a total sum of photo detectors outside these regions or from a part thereof is determined. This differential output signal is employed as a judgment signal for judging whether or not the collision of the disk bearing member with the objective lens has occurred.