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US 4,787,078 AGranted
Optical data recording and reproducing system with control of high frequency superposed signal applied to semiconductor laser
AssigneePioneer Electronic Corporation
InventorFumihiko Yokogawa
Life of this patent
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Abstract
In an optical data recording and reproducing system in which recording and reproducing data are carried out with a semiconductor laser, circuitry is provided to reduce the level of a high frequency current to be superposed on the laser during a data recording operation relative to the level during a data reproducing operation, to provide laser output only when necessary, to prolong laser life.
Claims4
An optical data recording and reproducing system, comprising:
- a semiconductor laser for irradiating an optical recording disk;
- means for applying a DC or low frequency current to said laser at a low amplitude during a data reproducing operation and a high amplitude during a data recording operation of said recording disk;
- means for superposing a high frequency current on said laser;
- and
- level varying means, connected to said superposing means, for varying a level of said high frequency current so as to provide a first level of said high frequency current during said data recording operation and a second, higher level of said high frequency current during said data reproducing operation.
2 more elements
Dependencies are inferred from the claim text.