Patent US6323969B1 successfully refreshed from Google Patents.
Patent EP0255305A2 successfully refreshed from Google Patents.
EP0255305A2
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Focusing error detecting device and method of manufacturing the same
Assignee: Sharp Corp
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Filing: 1987-07-24
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Granted: —
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Expires: 2007-07-24
Abstract
Abstract A focusing error detector comprises a light source (21), a collimator lens (22a) for making parallel the pencil of rays emitted by the light source (21), an objective lens (24a) which focuses the parallel pencil of rays to form a beam spot on a data-recording disc (23) with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from the data-recording disc (23), an optical system (26) for forming a beam spot from the reflected pencil of rays incident to the objective lens (24a), and an optical detector (27) having a plurality of divided optical sensor blocks (27a, 27b, 27c, 27d) for receiving the formed beam spot so as to detect the focusing error of the beam spot formed on the data-recording disc (23) on the basis of the configuration of the received beam spot.
Inventors
- 👤 Nobuo Ogata
- 👤 Yasuo Nakata
- 👤 Hideaki Satou
- 👤 Toshiyuki Tanaka
- 👤 Etsuji Minami
- 👤 Yoshio Yoshida
- 👤 Yukio Kurata
- 👤 Teruaki Inoue
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:04
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/22; G11B7/08; G11B7/09; G11B7/0908; G11B7/0909; G11B7/135; G11B7/1392; G11B7/13922
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
194 words
A focusing error detector, comprising: a light source; a collimator lens for making parallel the pencil of rays emitted by said light source; an objective lens which focuses the parallel pencil of rays to form a beam spot on a data-recording disc with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from said data-recording disc; an optical system for forming a beam spot from the reflected pencil of rays incident to said objective lens; and an optical detector having a plurality of divided optical sensor blocks for receiving the beam spot formed on said optical detector, said optical detector detecting the focusing error of the beam spot formed on said data-recording disc on the basis of the configuration of the received beam spot, wherein said objective lens and/or said collimator lens are place at such rotation positions as minimize the influence of aberration in the optical system between the light source and the data-recording disc on the symmetry with respect to the axis corresponding to the direction at right angle with the guide tracks, of a diffraction pattern formed in said beam spot on the optical detector.
Claim 2
Dependent Claim
194 words
A focusing error detector, comprising: a light source; a collimator lens for making parallel the pencil of rays emitted by said light source; an objective lens which focuses the parallel pencil of rays to form a beam spot on a data-recording disc with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from said data-recording disc; an optical system for forming a beam spot from the reflected pencil of rays incident to said objective lens; and an optical detector having a plurality of divided optical sensor blocks for receiving the beam spot formed on said optical detector, said optical detector detecting the focusing error of the beam spot formed on said data-recording disc on the basis of the configuration of the received beam spot, wherein said objective lens and/or said collimator lens are place at such rotation positions as minimize the influence of aberration in the optical system between the light source and the data-recording disc on the symmetry with respect to the axis corresponding to the direction at right angle with the guide tracks, of a diffraction pattern formed in said beam spot on the optical detector.
Claim 3
Dependent Claim
70 words
A focusing error detector, wherein a parallel plate inclined with respect to the optical axis and rotatable about the op tical axis is placed in either the optical divergent or the convergent zone in the optical path between a light source and a data-recording disc, said parallel plate being controlled so as to minimize the influence of aberration in the optical system between the light source and the data-recording disc.
Claim 4
Dependent Claim
70 words
A focusing error detector, wherein a parallel plate inclined with respect to the optical axis and rotatable about the op tical axis is placed in either the optical divergent or the convergent zone in the optical path between a light source and a data-recording disc, said parallel plate being controlled so as to minimize the influence of aberration in the optical system between the light source and the data-recording disc.
Claim 5
Dependent Claim
101 words
An optical data detecting device, comprising: a light source; an objective lens for concentrating the pencil of rays emitted from said light source onto a data-recording disc with circular or spiral guide tracks formed thereon and for receiving the pencil of rays reflected from said data-recording disc; and an optical system for transmitting said reflected pencil of rays into an optical detector having a plurality of divided optical sensor blocks, wherein said objective lens is positioned in such orientation as to minimize the inverse affect of the aberration by said objective lens on a diffractive pattern projected on said optical detector.
Claim 6
Dependent Claim
101 words
An optical data detecting device, comprising: a light source; an objective lens for concentrating the pencil of rays emitted from said light source onto a data-recording disc with circular or spiral guide tracks formed thereon and for receiving the pencil of rays reflected from said data-recording disc; and an optical system for transmitting said reflected pencil of rays into an optical detector having a plurality of divided optical sensor blocks, wherein said objective lens is positioned in such orientation as to minimize the inverse affect of the aberration by said objective lens on a diffractive pattern projected on said optical detector.
Claim 7
Dependent Claim
20 words
The focusing error detector of claim 1, wherein said focusing error detector is mounted in an optical data detecting device.
Claim 8
Dependent Claim
20 words
The focusing error detector of claim 2, wherein said focusing error detector is mounted in an optical data detecting device.
Claim 9
Dependent Claim
165 words
Apparatus for recording, reproducing and/or erasing information on an optical recording medium (23) using a beam of radiation which is focussed by a beam focussing means (22, 24) into a light spot on said medium, the apparatus having means (27) for determining the focus condition of said light spot, said determining means including an optical detector (27) which has a light sensor area divided into a plurality of area portions (27a-d), and being operable to determine said focus condition in accordance with the distribution between said sensor area portions of an image of said light spot projected onto said light sensor area, wherein means (42, 44, 28a, 29, 71) is provided for compensating for the effect which aberration in the optical system (22, 24) between the source of the radiation and the medium tends to have upon the symmetry of a diffraction pattern formed on the light sensor area due guide track portions (23c) of the medium (23) in the region of the light spot.
Claim 10
Dependent Claim
165 words
Apparatus for recording, reproducing and/or erasing information on an optical recording medium (23) using a beam of radiation which is focussed by a beam focussing means (22, 24) into a light spot on said medium, the apparatus having means (27) for determining the focus condition of said light spot, said determining means including an optical detector (27) which has a light sensor area divided into a plurality of area portions (27a-d), and being operable to determine said focus condition in accordance with the distribution between said sensor area portions of an image of said light spot projected onto said light sensor area, wherein means (42, 44, 28a, 29, 71) is provided for compensating for the effect which aberration in the optical system (22, 24) between the source of the radiation and the medium tends to have upon the symmetry of a diffraction pattern formed on the light sensor area due guide track portions (23c) of the medium (23) in the region of the light spot.
References Cited (Backward Citations)
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