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| OF THE INVENTION An embodiment of the present invention will be described below with reference to ... |
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| Magnetically actuated electric switch |
| OF INVENTION Referring now to the single FIGURE of the drawing, a channel or passageway 4, formed ... |
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| System and a process for recording cartographic information on a videodisk |
| The embodiments of the invention in which an exclusive property or privilege is claimed are defined ... |
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| Optical information recording apparatus |
| It is an object of this invention to prevent errors of code discrimination which tends to occur ... |
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| Loading and ejecting device for a disk player |
| OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a disc player comprises a casing 300 ... |
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Method for reproducing information recorded on a magneto-optical recording medium including servo controlling the dimension of the reproduction region of the recording medium by means of a recorded signal
| Details |
Inventors: Fukumoto, Atsushi; Udagawa, Toshiki; Yoshimura, Shunji;
Assignee: Sony Corporation (Tokyo, JP)
Primary Examiner: Nguyen; Hoa T.
Assistant Examiner:
Attorney, Agent or Firm: Limbach & Limbach
This invention is directed to an improvement in a novel magneto-optical disc reproducing method of the record information erasing type or the record information raised or transfer type wherein a technique is employed to prevent the dimension of an actual reproduction region from varying by a change of temperature or linear velocity of a magneto-optical disc. To realize this, reference information is recorded on a magneto-optical disc to reproduce this reference information prior to actual data reproduction to detect the regenerative RF signal level to control a laser power or an external magnetic field so that the regenerative RF signal level becomes equal to a level optimum for reproduction, thus allowing the dimension of an actual reproduction region to be an optimum fixed dimension at all times. At the time of actual reproduction, control is made so that the controlled laser power or external magnetic field is maintained. |
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DETAILED DESCRIPTION With the above in view, an object of this invention is to provide a reproducing method wherein even if there is any temperature change in a magneto-optical disc, the track recording density or the linear velocity changes according to the kind of magneto-optical discs, or there is any linear velocity change corresponding to the reproducing position on a magneto-optical disc, this method allows the dimension of the substantial reproduction region to be fixed, thus making it possible to stably read out information, and to allow the dimension of the reproduction region to be an optimum dimension corresponding to the recording density of a magneto-optical disc.
To achieve the above-described object, this invention provides a method of carrying out reproduction from a magneto-optical disc to which a reproducing method of the erasing type is applied, wherein reference information is recorded onto the magneto-optical disc to be read out from the magneto-optical disc prior to reproduction to allow detection of the level of a regenerative signal thereof to control the dimension of the magnetic coupling extinct region at the time of reproduction on the basis of the detected level.
Further, there is also provided a method of carrying out reproduction from a magneto-optical disc to which a reproducing method of the high temperature type is applied, wherein reference information is recorded onto the magneto-optical disc to be read out from the magneto-optical disc prior to reproduction to allow detection of the level of a regenerative signal thereof to control the dimension of the high temperature region at the time of reproduction on the basis of the detected level.
A regenerative signal of reference information from a magneto-optical disc has a signal level corresponding to the dimension of a reproduction region in the reproducing method of the erasing type or the high temperature type.
Accordingly, by controlling, on the basis of the regenerative signal level, the dimension of the reproduction region so that, e
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