US4588882A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Skew detection system for optically read data
Assignee: LaserCard Corp
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Filing: 1984-06-06
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Granted: 1986-05-13
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Expires: 2004-06-06
Abstract
Abstract A skew correction system for data media, especially optical data storage media wherein a pair of identical geometric marks are spaced apart in a band or track parallel to a data track, the data tracks being transverse to the directions of relative motion of the data storage medium with respect to a detector. As the medium moves relative to the detector, a linearly scanning detector, portions of each geometric mark are observed by the detector. A ratio of picture elements is determined using the two sets of observed picture elements. If the ratio is other than 1, skew exists. A closed-loop servo system is used to restore the ratio to 1, thereby eliminating skew. The geometric marks may be disposed forward of the data tracks, astride the data tracks, behind the data tracks, interspersed with the data tracks, or if different colors of light are used, atop the data tracks.
Inventors
- 👤 James L. Buxton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:53
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/01; G06K7/015; G06K19/00; G06K19/06; G06K19/06009; G06K19/06018; G06K2019/06215; G06K2019/06262
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
121 words
A skew correction system for an elongated optical data storage medium comprising, an elongated optical data storage medium having data tracks transverse to the length of the medium, a pair of geometrically related marks disposed on the medium having a width dimension which varies as a function of the lengthwise dimension, the marks disposed in a known relation to the tracks and in parallel alignment therewith, means for linearly scanning said data tracks and said marks, means for detecting geometric deviations between the pair of marks along a linear scan of the medium and producing a deviation signal in response thereto, and servo means for changing the alignment of said scanning means relative to the data tracks using said deviation signal.
Claim 2
Dependent Claim
121 words
A skew correction system for an elongated optical data storage medium comprising, an elongated optical data storage medium having data tracks transverse to the length of the medium, a pair of geometrically related marks disposed on the medium having a width dimension which varies as a function of the lengthwise dimension, the marks disposed in a known relation to the tracks and in parallel alignment therewith, means for linearly scanning said data tracks and said marks, means for detecting geometric deviations between the pair of marks along a linear scan of the medium and producing a deviation signal in response thereto, and servo means for changing the alignment of said scanning means relative to the data tracks using said deviation signal.
Claim 3
Dependent Claim
34 words
The system of claim 1 wherein said geometrically related marks are triangles having two long sides and a vertex, the long sides being in generally the same direction as the length of the medium.
Claim 4
Dependent Claim
32 words
The system of claim 1 wherein said geometrically related marks are triangles having two long sides and a vertex, the long sides being in generally the same direction as said data tracks.
Claim 5
Dependent Claim
23 words
The system of claim 1 where said geometrically related marks are located in an area on said storage medium preceeding said data tracks.
Claim 6
Dependent Claim
31 words
The system of claim 1 wherein an indicating mark is disposed in parallel alignment with said geometrically related marks, said indicating bar having the same length as said geometrically related marks.
Claim 7
Dependent Claim
15 words
The system of claim 1 wherein said data storage medium is a light reflective medium.
Claim 8
Dependent Claim
15 words
The system of claim 1 wherein said data storage medium is a light transmissive medium.
Claim 9
Dependent Claim
19 words
The system of claim 1 wherein said means for linearly scanning said data tracks is a CCD linear array.
Claim 10
Dependent Claim
17 words
The system of claim 1 wherein said means for linearly scanning said data tracks is a laser.
Claim 11
Dependent Claim
80 words
A data card for use in an optical data storage system having skew correction apparatus comprising, an elongate optical data storage medium having data tracks transverse to the length of the medium, said data storage medium disposed on a data card, and a pair of geometrically related marks disposed on the medium having a width dimension which varies as a function of the lengthwise dimension, the marks disposed in a known relation to the tracks and in parallel alignment therewith.
Claim 12
Dependent Claim
80 words
A data card for use in an optical data storage system having skew correction apparatus comprising, an elongate optical data storage medium having data tracks transverse to the length of the medium, said data storage medium disposed on a data card, and a pair of geometrically related marks disposed on the medium having a width dimension which varies as a function of the lengthwise dimension, the marks disposed in a known relation to the tracks and in parallel alignment therewith.
Claim 13
Dependent Claim
34 words
The system of claim 10 wherein said geometrically related marks are triangles having two long sides and a vertex, the long sides being in generally the same direction as the length of the medium.
Claim 14
Dependent Claim
32 words
The system of claim 10 wherein said geometrically related marks are triangles having two long sides and a vertex, the long sides being in generally the same direction as said data tracks.
Claim 15
Dependent Claim
23 words
The system of claim 10 where said geometrically related marks are located in an area on said storage medium preceeding said data tracks.
Claim 16
Dependent Claim
31 words
The system of claim 10 wherein an indicating mark is disposed in parallel alignment with said geometrically related marks, said indicating bar having the same length as said geometrically related marks.
Claim 17
Dependent Claim
15 words
The system of claim 10 wherein said data storage medium is a light transmissive medium.
Claim 18
Independent Claim
102 words
A method of skew correction for data cards of the type having stored information in bit patterns recorded in tracks on elongated stips, the tracks transverse to the length of the strips, the method comprising, disposing geometrically identical pairs of marks on a data card in parallel alignment with the data tracks, the marks having a width dimension which varies as a function of length, scanning said tracks and said marks in parallel scans, determining the ratio of portions of each mark detected in a scan, and reorienting the relative position of said scans with said tracks until said ratio is one.
Claim 19
Independent Claim
102 words
A method of skew correction for data cards of the type having stored information in bit patterns recorded in tracks on elongated stips, the tracks transverse to the length of the strips, the method comprising, disposing geometrically identical pairs of marks on a data card in parallel alignment with the data tracks, the marks having a width dimension which varies as a function of length, scanning said tracks and said marks in parallel scans, determining the ratio of portions of each mark detected in a scan, and reorienting the relative position of said scans with said tracks until said ratio is one.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-12 | 1989-11-11 | 1990-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-12 | 1993-11-11 | 1994-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-12 | 1997-11-11 | 1998-05-13 | $7700.00 | Window Closed / Lapsed |