US5294791A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System and a method for controlling position of a magnetic head relative to a servo track of a tape by optical detection of an edge of the tape
Assignee: Tandberg Data Storage AS
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Filing: 1992-02-13
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Granted: 1994-03-15
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Expires: 2012-02-13
Abstract
Abstract A method and apparatus performs the detection of an edge of a tape and further controls the read/write head to position itself relative to the detected edge. An array of photodetectors in an integrated circuit chip senses the intensity of light illuminating the chip with the tape running between the light source and the photodetectors. A light-to-dark transition is formed which is indicative of the edge of the tape.
Inventors
- 👤 Per O. Pahr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:32
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5504; G11B5/5508; G11B5/58; G11B5/584; G11B15/00; G11B15/02; G11B15/05; G11B15/087; G11B27/00; G11B27/36
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
209 words
An apparatus for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one dedicated servo track correlated with respect to an edge of said tape, comprising: a matrix of photodetectors in an integrated circuit chip disposed behind said tape wherein the position of each photodetector in said matrix is known from the manufacture of said chip and each photodetector generates an electrical signal corresponding to the intensity of light incident thereon; illumination means for projecting light on said tape and said matrix so that said tape casts a shadow on said matrix wherein said shadow has a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix; analyzing means for processing signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition wherein the location of a servo track of said tape is determined by the location of said sharpest light-to-dark transition; and positioning means responsive to the location of said servo track for positioning said head relative to said servo track of said tape.
Claim 2
Independent Claim
209 words
An apparatus for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one dedicated servo track correlated with respect to an edge of said tape, comprising: a matrix of photodetectors in an integrated circuit chip disposed behind said tape wherein the position of each photodetector in said matrix is known from the manufacture of said chip and each photodetector generates an electrical signal corresponding to the intensity of light incident thereon; illumination means for projecting light on said tape and said matrix so that said tape casts a shadow on said matrix wherein said shadow has a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix; analyzing means for processing signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition wherein the location of a servo track of said tape is determined by the location of said sharpest light-to-dark transition; and positioning means responsive to the location of said servo track for positioning said head relative to said servo track of said tape.
Claim 3
Dependent Claim
48 words
The apparatus of claim 1 wherein said at least one servo track further comprises: an erased or non-recorded portion at fixed intervals, each of said erased or non-recorded sections having an upper edge and a lower edge, which can be tracked via a servo demodulator and servo system.
Claim 4
Dependent Claim
32 words
The apparatus of claim 2 wherein said positioning means is responsive to one of said edges of said erased or non-recorded section for positioning said head relative to one of said edges.
Claim 5
Dependent Claim
25 words
The apparatus of claim 1 further comprising: a memory for storing position information relative to a tape edge of one of said dedicated servo tracks.
Claim 6
Dependent Claim
36 words
The apparatus of claim 4 further comprising: a read table for storing position information relative to a tape edge of each data track of said tape based on said information stored for said single servo track.
Claim 7
Dependent Claim
23 words
The apparatus of claim 1 wherein said tape further comprises: designations for synchronizing counting of servo samples along the length of said tape.
Claim 8
Dependent Claim
12 words
The apparatus of claim 1 wherein said magnetic head comprises three channels.
Claim 9
Dependent Claim
19 words
The apparatus of claim 1 wherein said magnetic tape comprises 112 tracks of which 16 are dedicated servo tracks.
Claim 10
Dependent Claim
26 words
The apparatus of claim 2 wherein said each of said erased or non-recorded sections is 10 kHz when the tape speed is 120 inches per second.
Claim 11
Independent Claim
189 words
A method for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one servo track correlated with respect to an edge of said tape, comprising: disposing said tape in front of a matrix of photodetectors in an integrated circuit chip, the position of each photodetector in said matrix being known from the manufacture of said chip, wherein each photodetector generates an electrical signal corresponding to the intensity of light incident thereon; illuminating said tape and said matrix so that said tape casts a shadow on said matrix, said shadow having a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix; analyzing the signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition; using the location of said sharpest light-to-dark transition as the location of a servo track of said tape; and positioning said magnetic head relative to said servo track of said tape.
Claim 12
Independent Claim
189 words
A method for controlling the position of a magnetic head relative to the detection of a servo track of a tape, said tape comprising a format with at least one dedicated servo track, said at least one servo track correlated with respect to an edge of said tape, comprising: disposing said tape in front of a matrix of photodetectors in an integrated circuit chip, the position of each photodetector in said matrix being known from the manufacture of said chip, wherein each photodetector generates an electrical signal corresponding to the intensity of light incident thereon; illuminating said tape and said matrix so that said tape casts a shadow on said matrix, said shadow having a transition region at the tape edges from light to dark covering a plurality of photodetectors in said matrix; analyzing the signals from said photodetectors in said transition region to determine the location, relative to said known photodetector positions, of a sharpest light-to-dark transition; using the location of said sharpest light-to-dark transition as the location of a servo track of said tape; and positioning said magnetic head relative to said servo track of said tape.
Claim 13
Dependent Claim
67 words
The method of claim 10 wherein said analyzing step further comprises: detecting an erased or non-recorded section of each of said servo tracks, said erased or non-recorded section recurring at fixed intervals and each said erased or non-recorded section having an upper edge and a lower edge wherein a light-to-dark transition equal to one-half of said sharpest light-to-dark transition can be detected at each of said edges.
Claim 14
Dependent Claim
31 words
The method of claim 10 wherein said positioning step further comprises the step of: positioning said head relative to one of said edges of one of said erased or non-recorded sections.
Claim 15
Dependent Claim
25 words
The method of claim 10 further comprising the step of: storing position information relative to a tape edge of one of said dedicated servo tracks.
Claim 16
Dependent Claim
35 words
The method of claim 13 further comprising the step of: storing position information relative to a tape edge of each data track of said tape based on said information stored for said single servo track.
Claim 17
Dependent Claim
21 words
The method of claim 10 further comprising the step of: synchronizing counting of servo samples along the length of said tape.
Claim 18
Dependent Claim
31 words
The method of claim 11 further comprising the step of: repeating each of said erase sections at a rate of 10 kHz, when the tape speed is 120 inches per second.
Claim 19
Dependent Claim
23 words
The method of claim 10 further comprising the step of: dedicating 16 servo tracks for said tape, wherein said tape comprises 112 tracks.
Claim 20
Dependent Claim
17 words
The method of claim 10 further comprising the step of: providing said magnetic head with three channels.
Claim 21
Dependent Claim
30 words
The method of claim 15 further comprising the step of: beginning or ending said synchronizing at holes designated in said tape marking data load point or end of data area.
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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) | 1997-03-14 | 1997-09-13 | 1998-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-14 | 2001-09-13 | 2002-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-14 | 2005-09-13 | 2006-03-15 | $7700.00 | Window Closed / Lapsed |