Patent EP0311859A2 successfully refreshed from Google Patents.
EP0311859A2
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EP
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Data storage apparatus
Assignee: Polaroid Corp
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Filing: 1988-09-30
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Granted: —
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Expires: 2008-09-30
Abstract
Abstract A magnetic data storage system for use with a double sided disk in which a prerecorded pattern of opaque optical lines is used to define the tracks in which magnetic data is to be stored. A separate optical system including an illumination source and a photosensitive detector is provided on a read/write assembly for each side of the disk. Each detector is designed also to serve as a reference grating. The illumination source is designed to image the prerecorded pattern of optical lines on the reference grating as an indication of the alignment of the read/write head of the assembly and a desired data track and any misalignment of the head and track generates a servo signal. The detector uses four separate photocells interleaved in a prescribed fashion to form a quadrature detector that is adjustable to compensate for various non-uniformities. One form of illumination source uses a surface-emitting light emitting diode and optics for forming a multiple beam source.
Inventors
- 👤 David V. Cronin
- 👤 John M. Guerra
- 👤 Paul F. Sullivan
- 👤 Patricia Mokry
- 👤 Peter P. Clark
- 👤 Vincent L. Cocco
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 05:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/265; G11B5/48; G11B5/58; G11B5/596; G11B5/59677; G11B21/00; G11B21/02; G11B21/08; G11B5/54; G11B5/55; G11B5/5521
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
279 words
A data storage apparatus for use with a double sided data storage medium of the type including a transparent support, a light transmissive data storage layer on each of respective opposite sides of the support, and an optical grating formed on the support between the storage layers for defining the location of data storage tracks in the storage layers, said apparatus comprising : means for supporting and moving such a medium for data read and/or write operations; first and second heads each including a data recording and/or reading transducer, a light source, and a detector, including a reference grating, responsive to light transmitted through the medium for modulation by the medium grating and thereafter incident upon said reference grating for providing position error signals indicative of the position of said transducer relative to a selected track; a head carriage configured for cross track movement relative to the medium and mounting said first and second heads thereon in complementary alignment on opposite sides of the medium such that said transducers are each in recording and/or reading relation to an adjacent one of the storage layers , said light source on said first head is positioned to direct its light output through the medium and onto said reference grating of said detector on said second head, and said light source on said second head is positioned to direct its light output through the medium and onto said reference grating of said detector on said first head for providing said position error signals; and means responsive to said position error signals for moving said head carriage assembly to maintain a selected one of said transducers in aligned relation to a selected track.
Claim 2
Dependent Claim
279 words
A data storage apparatus for use with a double sided data storage medium of the type including a transparent support, a light transmissive data storage layer on each of respective opposite sides of the support, and an optical grating formed on the support between the storage layers for defining the location of data storage tracks in the storage layers, said apparatus comprising : means for supporting and moving such a medium for data read and/or write operations; first and second heads each including a data recording and/or reading transducer, a light source, and a detector, including a reference grating, responsive to light transmitted through the medium for modulation by the medium grating and thereafter incident upon said reference grating for providing position error signals indicative of the position of said transducer relative to a selected track; a head carriage configured for cross track movement relative to the medium and mounting said first and second heads thereon in complementary alignment on opposite sides of the medium such that said transducers are each in recording and/or reading relation to an adjacent one of the storage layers , said light source on said first head is positioned to direct its light output through the medium and onto said reference grating of said detector on said second head, and said light source on said second head is positioned to direct its light output through the medium and onto said reference grating of said detector on said first head for providing said position error signals; and means responsive to said position error signals for moving said head carriage assembly to maintain a selected one of said transducers in aligned relation to a selected track.
Claim 3
Dependent Claim
283 words
A magnetic data storage apparatus for use with a double sided magnetic data storage medium of the type including a transparent support, a light transmissive magnetic data storage layer on each of respective opposite sides of the support, and an optical grating formed on the support between the storage layers for defining the location of data storage tracks in the storage layers, said apparatus comprising : means for supporting and moving such a medium for data read and/or write operations; first and second heads each including a magnetic data recording and/or reading transducer, a light source, and a detector, including a reference grating, responsive to light transmitted through the medium for modulation by the medium grating and thereafter incident upon said reference grating for providing position error signals indicative of the position of said transducer relative to a selected track; a head carriage configured for cross track movement relative to the medium and mounting said first and second heads thereon in complementary alignment on opposite sides of the medium such that said transducers are each in recording and/or reading relation to an adjacent one of the storage layers , said light source on said first head is positioned to direct its light output through the medium and onto said reference grating of said detector on said second head, and said light source on said second head is positioned to direct its light output through the medium and onto said reference grating of said detector on said first head for providing said position error signals; and means responsive to said position error signals for moving said head carriage assembly to maintain a selected one of said transducers in aligned relation to a selected track.
Claim 4
Dependent Claim
283 words
A magnetic data storage apparatus for use with a double sided magnetic data storage medium of the type including a transparent support, a light transmissive magnetic data storage layer on each of respective opposite sides of the support, and an optical grating formed on the support between the storage layers for defining the location of data storage tracks in the storage layers, said apparatus comprising : means for supporting and moving such a medium for data read and/or write operations; first and second heads each including a magnetic data recording and/or reading transducer, a light source, and a detector, including a reference grating, responsive to light transmitted through the medium for modulation by the medium grating and thereafter incident upon said reference grating for providing position error signals indicative of the position of said transducer relative to a selected track; a head carriage configured for cross track movement relative to the medium and mounting said first and second heads thereon in complementary alignment on opposite sides of the medium such that said transducers are each in recording and/or reading relation to an adjacent one of the storage layers , said light source on said first head is positioned to direct its light output through the medium and onto said reference grating of said detector on said second head, and said light source on said second head is positioned to direct its light output through the medium and onto said reference grating of said detector on said first head for providing said position error signals; and means responsive to said position error signals for moving said head carriage assembly to maintain a selected one of said transducers in aligned relation to a selected track.
Claim 5
Dependent Claim
75 words
The magnetic data storage apparatus of claim 2 wherein the magnetic storage medium is a flexible magnetic recording disk and said head carriage includes first and second head supports, mounted for movement between a first position wherein said first and second heads are in operative relation to the disk and a second position wherein said first and second heads are spaced further apart than when in said first position to facilitate disk insertion and removal.
Claim 6
Dependent Claim
19 words
The magnetic data storage apparatus of claim 3 wherein said first head is gimbal mounted on said first support.
Claim 7
Dependent Claim
32 words
The magnetic data storage apparatus of claim 2 where on each of said first and second heads, said light source and said detector are disposed on opposite sides of said magnetic transducer.
Claim 8
Dependent Claim
46 words
The magnetic data storage apparatus of claim 5 wherein said transducer includes a magnetic core, having a flux gap, mounted near one side of a transducer body and said detector is located adjacent said one side to position said detector in close relation to said core.
Claim 9
Dependent Claim
33 words
The magnetic data storage apparatus of claim 2 wherein each of said detectors comprises a photosensitive sensor which is configured to serve as reference grating as well as providing said position error signals.
Claim 10
Dependent Claim
80 words
The magnetic data storage apparatus of claim 2 wherein the magnetic storage medium is a flexible magnetic recording disk having a grating therein formed by concentric opaque rings separated by transparent rings to define the location of concentric circular data tracks in magnetic recording layers on opposite sides of the disk, and in which each detector includes a sensor comprising a plurality of uniform parallel photosensitive elements spaced apart to define said reference grating for cooperating with the disk grating.
Claim 11
Dependent Claim
43 words
The magnetic data storage apparatus of claim 8 in which each sensor comprises four separate photocells, each photocell including a plurality of said photosensitive elements, said photosensitive elements of said four photocells being periodically interleaved and spaced apart for defining said reference grating.
Claim 12
Dependent Claim
72 words
The magnetic data storage apparatus of claim 9 in which the disk grating transparent rings are of a width equal to the width of the opaque rings and in which the width of said photosensitive elements of the detector is equal to that of each of said opaque and transparent rings and in which said photosensitive elements are spaced apart by a distance equal to one-half the width of said photosensitive elements.
Claim 13
Dependent Claim
50 words
The magnetic data storage apparatus of claim 10 in which said means responsive to the position error signals includes a circuit which is supplied with the outputs of the four photocells for deriving a position error signal as a measure of any misalignment between a head and a selected track.
Claim 14
Dependent Claim
78 words
The magnetic data storage apparatus of claim 11 in which said circuit includes a first differential amplifier whose two inputs are supplied with the outputs of two of the photocells and a second differential amplifier whose two inputs are supplied with the output of the others of the photocells, and the outputs of the two differential amplifiers are supplied to opposite ends of an impedance means that includes a variable terminal where a position error signal is available.
Claim 15
Dependent Claim
30 words
The magnetic data storage apparatus of claim 2 further including means for imaging a respective aligned portion of the storage medium grating onto said reference grating of each said detector.
Claim 16
Dependent Claim
33 words
The magnetic data storage apparatus of claim 13 in which said imaging means includes means for self imaging by diffraction said respective aligned portion of the medium grating onto each said reference gratings.
Claim 17
Dependent Claim
46 words
The magnetic data storage apparatus of claim 2 in which said light source comprises an area-emitting diode and said apparatus further includes optical means for forming incident illumination provided by said diode into a plurality of collimated angularly spaced beams of light that are spatially coherent.
Claim 18
Dependent Claim
40 words
The magnetic data storage apparatus of claim 15 in which said optical means includes means for providing that multiple self images associated with the plurality of collimated beams image the medium grating on the reference grating of the detector constructively.
Claim 19
Dependent Claim
54 words
The magnetic data storage apparatus of claim 16 in which said optical means includes an optical element that includes an entrance surface that includes an array of flat surfaces spaced by faceted surfaces and an exit surface that is aspheric for forming the incident illumination into the plurality of angularly-spaced collimated beams of light.
Claim 20
Dependent Claim
52 words
The magnetic data storage apparatus of claim 2 in which each of said light sources comprises a quasi-point or line source and each head further includes a collimating optical element positioned such the said light source is at the infinity focus of said collimating optical element and parallel to said medium grating.
Claim 21
Dependent Claim
19 words
The magnetic data storage apparatus of claim 18 in which said collimating optical element is a plastic aspherical lens.
Claim 22
Dependent Claim
17 words
The magnetic data storage apparatus of claim 18 in which said collimating optic is a diffraction lens.
Claim 23
Dependent Claim
18 words
The magnetic data storage apparatus of claim 18 in which said collimating optic is a gradient index lens.
Claim 24
Dependent Claim
22 words
The magnetic data storage apparatus of claim 18 in which said quasi point line source is an edge emitting light emitting diode.
Claim 25
Dependent Claim
19 words
The magnetic data storage apparatus of claim 18 in which said quasi point line source is a laser diode.
Claim 26
Dependent Claim
32 words
The magnetic data storage apparatus of claim 18 in which said quasi-point line source is an area emitting light emitting diode with its area of emission approximating a quasi-point or line source.
Claim 27
Dependent Claim
15 words
The magnetic storage apparatus of claim 2 wherein said light sources are infra-red light sources.
Claim 28
Dependent Claim
21 words
The magnetic storage apparatus of claim 25 wherein said light sources emit infra-red light in a band centered about 890 nanometers.
References Cited (Backward Citations)
No citation records indexed.
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