US3833769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for positional control of a reading head in a device for reproducing optically coded video disk recordings
Assignee: US Philips Corp
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Filing: 1972-02-25
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Granted: 1974-09-03
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Expires: 1992-02-25
Abstract
Abstract An apparatus is described for reading, by means of a beam of radiation, a disk-shaped information carrier which contains spirally arranged video and/or audio signals coded in optical form, which apparatus comprises a source of radiation and a radiationsensitive signal detector cell, the information carrier being disposed in the radiation path between this source and this detector cell. By providing at least one grating, consisting of radiation-transmitting and radiation-absorbing stripes and on which an image of part of the grating-shaped structure of the information track in the vicinity of the portion of this track to be read may be formed, and a radiation-sensitive detection system, an accurate indication of axial and radial displacements of the optical imaging system relative to the information carrier can be obtained.
Inventors
- 👤 K Compaan
- 👤 G Bouwhuis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:22
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/12
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
143 words
Apparatus for reading, by means of a beam of radiation, a disk-shaped information carrier which contains spirAlly arranged information signals coded in optical form, which apparatus comprises a source of radiation, a radiation-sensitive signal detector cell, the information carrier being disposed in the radiation path between this source and this detector cell, at least two periodic gratings which consist of radiationtransmitting and radiation-absorbing stripes, each of the gratings being at a different optical distance from the information carrier, optical means in the path of the radiation eminating from the carrier for imaging on the gratings a part of the grating-shaped structure of the carrier information track in the vicinity of the portion of this track to be read, and a radiation-sensitive detection means in the path of the radiation eminating from the gratings for providing a focus control signal for said optical means.
Claim 2
Dependent Claim
143 words
Apparatus for reading, by means of a beam of radiation, a disk-shaped information carrier which contains spirAlly arranged information signals coded in optical form, which apparatus comprises a source of radiation, a radiation-sensitive signal detector cell, the information carrier being disposed in the radiation path between this source and this detector cell, at least two periodic gratings which consist of radiationtransmitting and radiation-absorbing stripes, each of the gratings being at a different optical distance from the information carrier, optical means in the path of the radiation eminating from the carrier for imaging on the gratings a part of the grating-shaped structure of the carrier information track in the vicinity of the portion of this track to be read, and a radiation-sensitive detection means in the path of the radiation eminating from the gratings for providing a focus control signal for said optical means.
Claim 3
Dependent Claim
24 words
Apparatus as claimed in claim 1, characterized in that a grating and the radiation-sensitive detection system are combined to form a grating-shaped radiation-sensitive detector.
Claim 4
Dependent Claim
46 words
Apparatus as claimed in claim 1, characterized in that the two gratings each consist of radiation-transmitting and radiation-absorbing stripes in the path of the radiation eminating from the information carrier, the optical path length between either grating and the location of the information carrier being different.
Claim 5
Dependent Claim
57 words
Apparatus as claimed in claim 3, further comprising radiation-transmitting plates of different thicknesses arranged in front of one of the gratings, thereby forming grating images having different effective path lengths to the carrier, wherein at least one of the two gratings is a virtual grating formed by interaction between the periodic grating and the radiation transmitting plates.
Claim 6
Dependent Claim
39 words
Apparatus as claimed in claim 3 further comprising a beam splitter arranged in front of either grating, and wherein said radiation-sensitive detection means is inserted in each of the radiation paths of the sub-beams produced by the beam splitters.
Claim 7
Dependent Claim
54 words
Apparatus as claimed in claim 3, further comprising a beam splitter inserted in the radiation path of the beam from the information carrier, wherein each of the gratings is included in the path of each of the sub-beams produced by the beam splitter, the gratings being spaced by different distances from the beam splitter.
Claim 8
Dependent Claim
27 words
Apparatus as claimed in claim 3, characterized in that the stripes of the gratings projected on to an imaginary plane perpendicular to the impinging radiation are aligned.
Claim 9
Dependent Claim
29 words
Apparatus as claimed in claim 7, characterized in that the grating comprises a matrix of component gratings, the grating stripes of two adjacent component gratings being shifted in phase.
Claim 10
Dependent Claim
26 words
Apparatus as claimed in claim 1, further comprising an additional grating consisting of radiation-transmitting and radiation-absorbing stripes arranged in the plane of the signal detector cell.
Claim 11
Dependent Claim
50 words
Apparatus as claimed in claim 9, further comprising a birefringent element in the radiation path in front of the grating, a polarization separating element in the radiation path behind the grating, and an additional radiation-sensitive detection inserted in the path of each of the sub-beams produced by the polarization-separating element.
Claim 12
Dependent Claim
26 words
Apparatus as claimed in claim 9, characterized in that the additional grating comprises two component gratings the grating stripes of which are mutually shifted in phase.
Claim 13
Dependent Claim
45 words
Apparatus as claimed in claim 11, further comprising a beam splitter in the path of the beam of radiation which emerges from the information carrier, and wherein each component grating is inserted in the path of each of the sub-beams produced by the beam splitter.
Claim 14
Dependent Claim
41 words
Apparatus as claimed in claim 11, wherein the radiation-transmitting stripes of one of the component gratings projected on an imaginary plane perpendicular to the impinging radiation are aligned with the radiation-absorbing stripes of a similar projection of the other component grating.
Claim 15
Dependent Claim
34 words
Apparatus as claimed in claim 11, characTerized in that the component gratings are color-selective, the radiation-transmitting stripes of one of the components gratings being interlaced with the radiation-transmitting stripes of the other component grating.
Claim 16
Dependent Claim
45 words
Apparatus as claimed in claim 11, wherein each component grating and the signal detector cell are combined to form a grating shaped radiation-sensitive detector, characterized in that the radiation-sensitive stripes of each component grating are interlaced with the radiation-sensitive stripes of the other component grating.
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) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |