US4633455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Headwheel for a multiple beam optical tape playback system
Assignee: RCA Corp
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Filing: 1985-03-25
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Granted: 1986-12-30
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Expires: 2005-03-25
Abstract
Abstract A multiple track playback headwheel is disclosed for use in a helical scan optical tape recording system. The headwheel includes optical diffraction gratings at the center of rotation of the headwheel positioned normal to the rotational axis. A collimated light beam supplied from a laser external to the headwheel, directed along the rotational axis of the headwheel, is split into a plurality of beams by the gratings. The plurality of beams are imaged at the entrance pupil of the playback objective lens which focuses the beams to diffraction limited spots on the surface of an optical tape having information recorded thereon. The illuminated spots are reflected back through the objective lens and are formed into beams which are directed to an information and tracking detecting apparatus and to a focus detecting apparatus.
Inventors
- 👤 Kenneth C. Hudson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:04
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/14; G11B7/002; G11B7/003; G11B7/0031; G11B7/08; G11B7/085; G11B7/08547; G11B7/09; G11B7/0901; G11B7/0903
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
124 words
A headwheel for use in a system for retrieving information stored on an information-bearing surface of an optical tape, said headwheel comprising: support means having a generally cylindrical outer surface, said support means being rotatable about a central axis thereof; said optical tape being helically wrapped about a portion of said support means such that said information-bearing surface is adjacent said outer surface; means responsive to a collimated beam of light directed along said central axis for splitting said beam into a plurality of light beams; means for directing said plurality of beams into respective diffraction limited spots on said information-bearing surface of said optical tape; and means for detecting the intensity of light reflected from said diffraction limited spots on said information-bearing surface.
Claim 2
Dependent Claim
124 words
A headwheel for use in a system for retrieving information stored on an information-bearing surface of an optical tape, said headwheel comprising: support means having a generally cylindrical outer surface, said support means being rotatable about a central axis thereof; said optical tape being helically wrapped about a portion of said support means such that said information-bearing surface is adjacent said outer surface; means responsive to a collimated beam of light directed along said central axis for splitting said beam into a plurality of light beams; means for directing said plurality of beams into respective diffraction limited spots on said information-bearing surface of said optical tape; and means for detecting the intensity of light reflected from said diffraction limited spots on said information-bearing surface.
Claim 3
Dependent Claim
31 words
The headwheel according to claim 1 wherein said outer surface includes a sapphire window through which said plurality of light beams are focused on said information-bearing surface of said optical tape.
Claim 4
Dependent Claim
29 words
The headwheel according to claim 1 wherein said splitting means includes a first optical diffraction grating for splitting said collimated beam of light into a plurality of light beams.
Claim 5
Dependent Claim
25 words
The headwheel according to claim 3 wherein said first optical diffraction grating splits said collimated beam of light into five beams of substantially equal intensity.
Claim 6
Dependent Claim
34 words
The headwheel according to claim 3 wherein said splitting means further includes a second optical diffraction grating for splitting each beam of said plurality of light beams into a second plurality of light beams.
Claim 7
Dependent Claim
31 words
The headwheel according to claim 5 wherein said first and second optical diffraction gratings are positioned at said central axis of said support means and are normal to said central axis.
Claim 8
Dependent Claim
51 words
The headwheel according to claim 1 wherein said detecting means includes means for detecting the focus condition of said diffraction limited spots on said information-bearing surface of said optical tape, said focus condition detecting means including means for generating a control signal to said directing means indicative of said focus condition.
Claim 9
Dependent Claim
51 words
The headwheel according to claim 1 wherein said detecting means includes means for detecting the tracking position of said diffraction limited spots on said information-bearing surface of said optical tape, said tracking position detecting means including means for generating a control signal to said directing means indicative of said tracking position.
Claim 10
Independent Claim
159 words
A system for retrieving information stored on an information-bearing surface of an optical tape, said system comprising: a headwheel having a generally cylindrical outer surface, said headwheel being rotatable about a central axis thereof; said optical tape being helically wrapped around a portion of said outer surface of said headwheel such that said information-bearing surface is adjacent said outer surface; means for providing relative motion between said headwheel and said optical tape by rotation of said headwheel about said central axis; and means for providing a collimated beam of light to said headwheel along said central axis; said headwheel including means for splitting said collimated beam of light into a plurality of light beams; said headwheel further including means for directing said plurality of beams into respective diffraction limited spots on said information-bearing surface of said optical tape; said headwheel further including means for detecting the intensity of light reflected from said diffraction limited spots on said information-bearing surface.
Claim 11
Independent Claim
159 words
A system for retrieving information stored on an information-bearing surface of an optical tape, said system comprising: a headwheel having a generally cylindrical outer surface, said headwheel being rotatable about a central axis thereof; said optical tape being helically wrapped around a portion of said outer surface of said headwheel such that said information-bearing surface is adjacent said outer surface; means for providing relative motion between said headwheel and said optical tape by rotation of said headwheel about said central axis; and means for providing a collimated beam of light to said headwheel along said central axis; said headwheel including means for splitting said collimated beam of light into a plurality of light beams; said headwheel further including means for directing said plurality of beams into respective diffraction limited spots on said information-bearing surface of said optical tape; said headwheel further including means for detecting the intensity of light reflected from said diffraction limited spots on said information-bearing surface.
Claim 12
Dependent Claim
34 words
The system according to claim 9 wherein said outer surface of said headwheel includes a sapphire window through which said plurality of light beams are focused on said information-bearing surface of said optical tape.
Claim 13
Dependent Claim
29 words
The system according to claim 9 wherein said splitting means includes a first optical diffraction grating for splitting said collimated beam of light into a plurality of light beams.
Claim 14
Dependent Claim
25 words
The system according to claim 11 wherein said first optical diffraction grating splits said collimated beam of light into five beams of substantially equal intensity.
Claim 15
Dependent Claim
34 words
The system according to claim 11 wherein said splitting means further includes a second optical diffraction grating for splitting each beam of said plurality of light beams into a second plurality of light beams.
Claim 16
Dependent Claim
30 words
The system according to claim 13 wherein said first and second optical diffraction gratings are positioned at said central axis of said headwheel and are normal to said central axis.
Claim 17
Dependent Claim
51 words
The system according to claim 9 wherein said detecting means includes means for detecting the focus condition of said diffraction limited spots on said information-bearing surface of said optical tape, said focus condition detecting means including means for generating a control signal to said directing means indicative of said focus condition.
Claim 18
Dependent Claim
51 words
The system according to claim 9 wherein said detecting means includes means for detecting the tracking position of said diffraction limited spots on said information-bearing surface of said optical tape, said tracking position detecting means including means for generating a control signal to said directing means indicative of said tracking position.
Claim 19
Dependent Claim
32 words
The system according to claim 9 wherein said means for providing a collimated beam of light includes a laser and a beam expander for expanding the light beam output of said laser.
Claim 20
Dependent Claim
20 words
The system according to claim 17 wherein said laser provides a light beam output at wavelength less than 650 nanometers.
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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) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |