Light spot position control system and method by sampling servo
AssigneeHitachi, Ltd.
InventorsMasatoshi Ohtake, Seiji Yonezawa, Toshiaki Tsuyoshi, Wasao Takasugi, Takashi Takeuchi
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Abstract
A light spot position control system of the invention uses an optical disc in which a servo area and a data area are alternately formed along a rotating direction of a rotary recording medium, wherein error signals obtained from the servo areas are sampled, the latest sample value is compared with at least one-preceding sample value, a check is made to see if the latest sample value is correct or incorrect, and when the latest sample value is decided to be incorrect, the preceding error signal held is directly used as a light spot position control signal without updating the current error signal holding value.
Claims7
A system for controlling a position of a light spot comprising:
- a recording medium in which a servo area and a data area are alternately formed along a track;
- error detecting means for irradiating a light spot onto said recording medium and for detecting error signals, as sampled signals, from the lights obtained from said servo areas;
- deciding means connected to said error detecting means, for discriminating whether the error signal detected by said error detecting means is correct or incorrect;
- and
- control signal generating means for outputting as a position control signal either the error signal detected by the error detecting means or an error signal based on at least one-preceding sample value on the basis of an output of said deciding means.
A method of controlling a position of a light spot using an optical disc in which a servo area and a data area are alternately formed along a rotating direction of a rotary recording medium, comprising the steps of:
- sampling error signals which are obtained from said servo areas;
- comparing the latest sample value with at least one-preceding sample value;
- deciding whether said latest sample value is correct or incorrect;
- and
- when said latest sample value is decided to be incorrect, using a preceding error signal held as a light spot position control signal without updating a current error signal holding value.
Dependencies are inferred from the claim text.