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US 4,283,785 AGranted
Optical information recording apparatus
AssigneeHitachi, Ltd.
InventorsToshimitsu Miyauchi, Yoshito Tsunoda
Life of this patent
Estimating the term…
Abstract
In an optical information recording apparatus, a version of a recording light emitted from a light source and reflected by a recording medium is detected to control the recording light output power of the light source.
Claims4
An optical information recording apparatus comprising:
- (a) a light source;
- (b) a recording medium on which predetermined pulse information is successively recorded through the irradiation of recording light pulses emitted from said light source and modulated in accordance with said predetermined pulse information, the reflectivity of said recording medium being variable during the period of irradiation of the recording light pulse so that a reflected version of the recording light pulse from said recording medium has a changing pulse width;
- and
- (c) a control circuit section including a pulse width change detecting circuit means for receiving the reflected-light pulse from said recording medium and detecting the change in pulse width of the reflected-light pulse to produce an output relating to that change and a control circuit means associated with said light source for controlling an output power therefrom on the basis of the output of said pulse width change detecting circuit means so that the pulse width of the reflected-light pulse from said recording medium is kept constant.
1 more element
Dependencies are inferred from the claim text.