US4779253A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sampled servo for an optical disk drive
Assignee: Philips North America LLC
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Filing: 1986-08-29
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Granted: 1988-10-18
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Expires: 2006-08-29
Abstract
Abstract Sampled servo data comprising one pit centered on a track and two pits spaced 1/4 track pitch from track center on opposite sides thereof provide for two sinusoidal tracking signals, one radially phase offset from the other by 90 degrees. A first tracking signal derived from subtracting the signals of the offset pits has a zero crossing at track center and is used by the servo system for tracking. Its derivative is used for damping. A second tracking signal derived from all three pits has maxima at track centers and is therefore 90 degrees out of phase with the first tracking signal. This second signal provides track crossing information, and when used in quadrature with the first tracking signal, provides information about the radial direction of crossing. The second signal also provides a control signal for inverting the damping signal while between tracks when the derivative of the first tracking signal would ordinarily be negative and provide for negative damping.
Inventors
- 👤 Kurt W. Getreuer
- 👤 Johannes J. Verboom
- 👤 David L. Schell
- 👤 David E. Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:40
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/085; G11B7/0901; G11B7/0938; G11B7/24; G11B7/2407; G11B7/24085
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
92 words
In an optical disk drive having a disk with concentric or spiral tracks and a laser beam, optics and detector means for tracking said tracks, servo data pits comprising: at least one centered servo data pit centered on a track and at least two offset servo data pits offset on opposite sides of track center by one quarter of the track pitch; each of said servo data pits being of substantially the same size and shape, and wherein two servo signals are generated using two or more of said servo data pits.
Claim 2
Dependent Claim
92 words
In an optical disk drive having a disk with concentric or spiral tracks and a laser beam, optics and detector means for tracking said tracks, servo data pits comprising: at least one centered servo data pit centered on a track and at least two offset servo data pits offset on opposite sides of track center by one quarter of the track pitch; each of said servo data pits being of substantially the same size and shape, and wherein two servo signals are generated using two or more of said servo data pits.
Claim 3
Dependent Claim
109 words
Apparatus for generating servo signals in an optical disk drive having a disk with concentric or spiral tracks and a laser beam, comprising: a first servo data pit centered on a track; a second servo data pit outwardly, radially offset from said first servo data pit; a third servo data pit inwardly, radially offset from said first servo data pit; and servo signal generator means responsive to said servo data pits and the laser beam for deriving a first servo signal using said offset pits and a second servo signal using said centered and offset pits, the second servo signal radially offset from the first by substantially 90 degrees.
Claim 4
Dependent Claim
109 words
Apparatus for generating servo signals in an optical disk drive having a disk with concentric or spiral tracks and a laser beam, comprising: a first servo data pit centered on a track; a second servo data pit outwardly, radially offset from said first servo data pit; a third servo data pit inwardly, radially offset from said first servo data pit; and servo signal generator means responsive to said servo data pits and the laser beam for deriving a first servo signal using said offset pits and a second servo signal using said centered and offset pits, the second servo signal radially offset from the first by substantially 90 degrees.
Claim 5
Dependent Claim
40 words
Apparatus according to claim 2 wherein said servo signal generator means includes: means for subtracting a signal detected from said second servo data pit from a signal detected from said third servo data pit to generate said first servo signal.
Claim 6
Dependent Claim
70 words
Apparatus according to claim 2 wherein said servo signal generator means includes: means for subtracting a signal detected from said second servo data pit from a signal detected from said first servo data pit; means for subtracting a signal detected from said third servo data pit from said signal detected from said first servo data pit; and means for adding said two subtracted signals to form said second tracking signal.
Claim 7
Dependent Claim
36 words
Apparatus according to claim 2 wherein: said first, second and third servo data pits of a first track are radially aligned with the corresponding said first, second and third servo data pits of a second track.
Claim 8
Dependent Claim
26 words
Apparatus according to claim 2 wherein: said first, second and third servo data pits are recorded in an area of a track having no preformatted groove.
Claim 9
Dependent Claim
26 words
Apparatus according to claim 5 wherein: said first, second and third servo data pits are recorded in an area of a track having no preformatted groove.
Claim 10
Dependent Claim
34 words
Apparatus according to 2 wherein: said first, second and third servo data pits are recorded in a servo data area, and a plurality of said area are recorded on each track interspersed with data.
Claim 11
Dependent Claim
34 words
Apparatus according to 2 wherein: said first, second and third servo data pits are recorded in a servo data area, and a plurality of said area are recorded on each track interspersed with data.
Claim 12
Dependent Claim
34 words
Apparatus according to claim 5 wherein: said first, second and third servo data pits are recorded in a servo area, and a plurality of said area are recorded on each track interspersed with data.
Claim 13
Dependent Claim
35 words
Apparatus according to claim 6 wherein: said first, second and third servo data pits are recorded in a servo data area, and a plurality of said area are recorded on each track interspersed with data.
Claim 14
Dependent Claim
35 words
Apparatus according to claim 7 wherein: said first, second and third servo data pits are recorded in a servo data area, and a plurality of said area are recorded on each track interspersed with data.
Claim 15
Dependent Claim
19 words
Apparatus according to claim 2 wherein: said first servo data pit follows said second and third servo data pits.
Claim 16
Dependent Claim
25 words
Apparatus according to claim 2 wherein: said first, second and third servo data pits are each preformatted holes one-quarter wavelength of the laser beam deep.
Claim 17
Dependent Claim
29 words
Apparatus according to claim 2 wherein: said first, second and third servo data pits are spaced longitudinally from each other at least 1.5 times the size of each pit.
Claim 18
Dependent Claim
47 words
Apparatus according to claim 2 wherein: data is recorded on said tracks in a fixed block format and said first, second and third servo data pits are recorded with at least one of said pits not having the fixed block format relationship to the other said pits.
Claim 19
Dependent Claim
60 words
Apparatus according to claim 2 wherein: data is recorded on said tracks in a fixed block format and said first, second and third servo data pits are recorded with said first servo data pit spaced from at least the adjacent one of said second or third servo data pit farther than the distance specified by the fixed block format relationship.
Claim 20
Dependent Claim
43 words
Apparatus according to claim 4 further comprising: servo system means responsive to said first servo signal, said servo system means including damping means responsive to said first servo signal and means for controlling said damping means in response to said second servo signal.
Claim 21
Dependent Claim
48 words
Apparatus according to claim 17 wherein: said means for controlling said damping means in response to said second servo signal includes means for inverting the output of said damping means when the laser beam of the optical disk is centered outside the offset servo data pits between tracks.
Claim 22
Dependent Claim
34 words
Apparatus according to claim 4 further comprising: servo system means including a quadrature direction detector means responsive to both said first and said second servo signals for determining the direction of track crossing movement.
Claim 23
Dependent Claim
26 words
Apparatus according to claim 19 further comprising: means responsive to said quadrature direction detector means and to said servo signal for counting tracks during seek operations.
Claim 24
Dependent Claim
32 words
Apparatus according to claim 2 wherein: data is recorded in a predetermined format and said first, second and third servo data pits are recorded in a pattern distinguishable from said predetermined format.
Claim 25
Independent Claim
106 words
An apparatus for generating at least one servo signal in an optical disk drive having a disk with concentric or spiral tracks and a laser beam, comprising: a first servo data pit centered on a track; a second servo data pit outwardly, radially offset from said first servo data pit; a third servo data pit inwardly, radially offset from said first servo data pit; and means for generating a servo signal from said first servo data pit, said second data pit and said third servo data pit, said servo signal having a maximum when the laser beam is centered relative to said first servo data pit.
Claim 26
Independent Claim
106 words
An apparatus for generating at least one servo signal in an optical disk drive having a disk with concentric or spiral tracks and a laser beam, comprising: a first servo data pit centered on a track; a second servo data pit outwardly, radially offset from said first servo data pit; a third servo data pit inwardly, radially offset from said first servo data pit; and means for generating a servo signal from said first servo data pit, said second data pit and said third servo data pit, said servo signal having a maximum when the laser beam is centered relative to said first servo data pit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-18 | 1992-04-18 | 1992-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-18 | 1996-04-18 | 1996-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-18 | 2000-04-18 | 2000-10-18 | $7700.00 | Window Closed / Lapsed |