OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE

PURPOSE:To detect the output reduction of a photodetector due to the sticking of the dust and stain of an objective lens in an optical head by providing a reflecting mirror and outputting an abnormality detecting signal when the reflecting light quantity is lower than a constant level. CONSTITUTION:...

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Bibliographic Details
Main Author MIZUNIWA YASUHIRO
Format Patent
LanguageEnglish
Published 06.03.1990
Subjects
INFORMATION STORAGE
INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER
PHYSICS
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Summary:PURPOSE:To detect the output reduction of a photodetector due to the sticking of the dust and stain of an objective lens in an optical head by providing a reflecting mirror and outputting an abnormality detecting signal when the reflecting light quantity is lower than a constant level. CONSTITUTION:With a light beam from a laser diode 11 in an optical head 1, a reference reflecting mirror 2 is irradiated through an optical system 3 and the reflecting light is detected through the optical system 3 by a light detector 12 again. At this time, when the dust and the stain are stuck to an objective lens 31 in the head 1, the emitting light quantity emitted through a lens 31 is reduced, the output of the detector 12 is reduced. The output of the detector 12 is lower than a reference voltage 41 of a differential discriminator 4, and then, the differential discriminator 4 outputs an abnormality detecting signal 42.
Bibliography:Application Number: JP19880218834