EP0717401A1
Expired / Lapsed
EP
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Apparatus and method for reproducing data from multilayered disks
Assignee: Sony Corp
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Filing: 1995-12-14
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Granted: —
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Expires: 2015-12-14
Abstract
Abstract A method for moving the focus of an object lens from one layer to another in a disk having data recorded on a plurality of layers comprises: a first step for accelerating an object lens in a first direction; a second step for detecting that a focus error signal surpasses a first voltage and for accelerating the object lens in a second direction different from the first direction; a third step for detecting that the object lens has moved for a predetermined duration of time and for accelerating the object lens in the first direction; and a fourth step for detecting that the focus error signal surpasses a second voltage and for starting focus servo control. The method and apparatus can reliably catch the just-focus point of a layer and reduce the time required for movement from one layer to another.
Inventors
- 👤 Masanobu c/o Int. Prop Div Sony Corp. Nishikata
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 05:59
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0945; G11B7/085; G11B7/08505; G11B7/08511; G11B2007/0003; G11B2007/0006; G11B2007/0009; G11B2007/0013; G11B7/0908
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
94 words
A disk reproducing apparatus for reproducing data recorded on a plurality of layers of an optical disk, comprising: first comparator means for comparing a focus error signal with a first voltage; second comparator means for comparing the focus error signal with a second voltage; drive voltage supplying means for selectively supplying a first or a second object lens drive voltage in response to results of comparison supplied from said first and/or second comparator means; and means for driving an object lens with said object lens drive voltage supplied from said drive voltage supplying means.
Claim 2
Dependent Claim
53 words
The disk reproducing apparatus according to claim 1, wherein said drive voltage supplying means comprises: first object lens drive voltage generator means for accelerating said object lens in a first direction; and second object lens drive voltage generator means for accelerating said object lens in a second direction different from said first direction.
Claim 3
Dependent Claim
35 words
The disk reproducing apparatus according to claim 2, wherein said first and second object lens drive voltage generator means generate object lens drive voltages which are opposite in polarity and substantially equal in absolute value.
Claim 4
Dependent Claim
49 words
The disk reproducing apparatus according to claim 3, further comprising means for obtaining a duration of time from the point of time where the object lens passes over a focalized point to the point of time where the object lens reaches a position most distant from the focalized point.
Claim 5
Dependent Claim
67 words
The disk reproducing apparatus according to claim 4, further comprising: means for obtaining a duration of time T1 since the object lens passes over a focalized point until it reaches a position most distant from the focalized point; and means for obtaining a duration of time T2 since a comparison output is supplied from said first comparator means until said object lens passes over the focalized point.
Claim 6
Dependent Claim
73 words
The disk reproducing apparatus according to claim 5, further comprising means for obtaining from said T1 and T2 a duration of time from a point of time where the object lens moves from the position most distant from the focalized point to a point of time where the object lens passes over a position distant from the focalized point by one half the distance of the most distant position from the focalized point.
Claim 7
Dependent Claim
32 words
The disk reproducing apparatus according to claim 2, wherein said first and second voltages are set to values at which the focus error signal is approximately 0V and not affected by noise.
Claim 8
Dependent Claim
46 words
The disk reproducing apparatus according to claim 1, further comprising: third comparator means for comparing a reproduced RF signal with a third voltage; and means responsive to a result of comparison by said third comparator means to control operations of said first and second comparator means.
Claim 9
Dependent Claim
107 words
A disk reproducing method for reproducing data recorded on a plurality of layers of an optical disk, comprising: a first step for accelerating an object lens in a first direction; a second step for detecting that a focus error signal surpasses a first voltage and for accelerating the object lens in a second direction different from said first direction; a third step for detecting that the object lens has moved for a predetermined duration of time and for accelerating the object lens in said first direction; and a fourth step for detecting that the focus error signal surpasses a second voltage and for starting focus servo control.
Claim 10
Dependent Claim
32 words
The disk reproducing method according to claim 9, wherein the acceleration in said first direction and the acceleration in said second direction are opposite in direction and substantially equal in absolute value.
Claim 11
Dependent Claim
64 words
The disk reproducing method according to claim 10, wherein said third step further comprises: a step for obtaining a duration of time T1 of acceleration in said first direction by said first step; and a step for obtaining a duration of time T2 since the acceleration in said second direction by said second step starts until the object lens passes over a focalized point.
Claim 12
Dependent Claim
78 words
The disk reproducing method according to claim 11, wherein said third step further comprises a step for obtaining from said T1 and T2 a duration of time from a point of time where the object lens moves from the position most distant from the focalized point to a point of time where the object lens passes over a position distant from the focalized point by one half the distance of the most distant position from the focalized point.
Claim 13
Dependent Claim
22 words
The disk reproducing method according to claim 9, further comprising a step of comparing a reproduced RF signal with a third voltage.
References Cited (Backward Citations)
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