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EP0414380A2
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EP
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Optical recording and reproducing apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1990-07-23
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Granted: —
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Expires: 2010-07-23
Abstract
Abstract A data playback apparatus for reproduction of data from an optical recording medium (100) which has a data layer disposed on a substrate (1) thereof having a specific thickness is provided with an optical length corrector (9) interposed between the recording medium and an objective lens (8) for converging a light beam. The optical length corrector is selected so that the sum of the optical length of the substrate of the recording medium and the optical length of the optical length corrector equals a predetermined length for the objective lens. Accordingly, the light passing the objective lens can converge on the data layer developing a light spot close to the limit of refraction, regardless of the thickness of the substrate of the recording medium.
Inventors
- 👤 Kenichi Nishiuchi
- 👤 Nobuo Akahiro
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 20:18
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1392; G11B7/13925; G11B7/08; G11B7/09; G11B7/0945; G11B7/1365; G11B7/1369; G11B11/00; G11B11/10; G11B11/105; G11B2007/0003; G11B2007/0006; G11B2007/0009; G11B2007/0013
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
150 words
An optical data recording/reproducing apparatus, in which record and reproduction of data is carried out by directing a light beam onto an optical data recording medium having a data recording layer disposed on a transparent substrate thereof and detecting a reflected or transmitted light from the recording medium, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on the data recording layer and when the transparent substrate has an optical length equal to a predetermined optical length, establishing a focus on the data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having an optical length corresponding to a difference between the predetermined optical length and the optical length of the transparent substrate; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 2
Dependent Claim
150 words
An optical data recording/reproducing apparatus, in which record and reproduction of data is carried out by directing a light beam onto an optical data recording medium having a data recording layer disposed on a transparent substrate thereof and detecting a reflected or transmitted light from the recording medium, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on the data recording layer and when the transparent substrate has an optical length equal to a predetermined optical length, establishing a focus on the data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having an optical length corresponding to a difference between the predetermined optical length and the optical length of the transparent substrate; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 3
Dependent Claim
31 words
An apparatus according to Claim 1, wherein the optical length of the optical length correcting means is variable corresponding to the thickness of the substrate of the optical data recording medium.
Claim 4
Dependent Claim
21 words
An apparatus according to Claim 1, wherein the optical length correcting means is a transparent planer plate having a constant thickness.
Claim 5
Dependent Claim
22 words
An apparatus according to Claim 1, wherein the optical length of the optical length correcting means is variable continuously or in steps.
Claim 6
Dependent Claim
79 words
An adapter for an optical data recording medium for use with a playback apparatus in which a light beam is directed onto a data recording layer of the recording medium and a reflected or transmitted light from the data recording layer is detected for reproduction of data, said adapter accommodating a smaller-sized data medium therein for loading into the playback apparatus; and said adapter carrying at a part thereof an optical length correcting means having a given optical length.
Claim 7
Dependent Claim
79 words
An adapter for an optical data recording medium for use with a playback apparatus in which a light beam is directed onto a data recording layer of the recording medium and a reflected or transmitted light from the data recording layer is detected for reproduction of data, said adapter accommodating a smaller-sized data medium therein for loading into the playback apparatus; and said adapter carrying at a part thereof an optical length correcting means having a given optical length.
Claim 8
Dependent Claim
40 words
An adapter according to Claim 5, further carrying at a part thereof a substrate thickness correcting plate having a thickness equal to that of the optical length correcting means and provided for movement in synchronism with the data recording medium.
Claim 9
Independent Claim
149 words
An apparatus for recording and reproducing of data onto and from an optical data recording medium, in which record and reproduction of data is carried out by directing a light beam onto the optical data recording medium having at least two or more data recording layers and detecting a reflected or transmitted light, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on a data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having at least two different optical lengths; a means for selecting one of the different optical lengths of the optical length correcting means according to a position of a target data recording layer in the data recording medium; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 10
Independent Claim
149 words
An apparatus for recording and reproducing of data onto and from an optical data recording medium, in which record and reproduction of data is carried out by directing a light beam onto the optical data recording medium having at least two or more data recording layers and detecting a reflected or transmitted light, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on a data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having at least two different optical lengths; a means for selecting one of the different optical lengths of the optical length correcting means according to a position of a target data recording layer in the data recording medium; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 11
Dependent Claim
30 words
An apparatus according to Claim 7, wherein a difference between the different optical lengths of the optical length correcting means is equal to a distance between the data recording layers.
Claim 12
Dependent Claim
22 words
An apparatus according to Claim 7, wherein the optical length correcting means is arranged movable corresponding to a target data recording layer.
Claim 13
Dependent Claim
26 words
An apparatus according to Claim 7, wherein at least one of the data recording layers is arranged for record and reproduction by means of magneto-optical effect.
Claim 14
Dependent Claim
148 words
An optical data playback apparatus in which reproduction of data is carried out by directing a light beam onto an optical data recording medium having a data recording layer disposed on a transparent substrate thereof and detecting a reflected or transmitted light from the recording medium, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on the data recording layer and when the transparent substrate has an optical length equal to a predetermined optical length, establishing a focus on the data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having an optical length corresponding to a difference between the predetermined optical length and the optical length of the transparent substrate; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 15
Dependent Claim
148 words
An optical data playback apparatus in which reproduction of data is carried out by directing a light beam onto an optical data recording medium having a data recording layer disposed on a transparent substrate thereof and detecting a reflected or transmitted light from the recording medium, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on the data recording layer and when the transparent substrate has an optical length equal to a predetermined optical length, establishing a focus on the data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having an optical length corresponding to a difference between the predetermined optical length and the optical length of the transparent substrate; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 16
Dependent Claim
31 words
An apparatus according to Claim 11, wherein the optical length of the optical length correcting means is variable corresponding to the thickness of the substrate of the optical data recording medium.
Claim 17
Dependent Claim
21 words
An apparatus according to Claim 11, wherein the optical length correcting means is a transparent planer plate having a constant thickness.
Claim 18
Dependent Claim
22 words
An apparatus according to Claim 11, wherein the optical length of the optical length correcting means is variable continuously or in steps.
Claim 19
Dependent Claim
138 words
A playback apparatus for an optical data recording medium, in which reproduction of data is carried out by directing a light beam onto the optical data recording medium having at least two data recording layers and detecting a reflected or transmitted light, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on a data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having at least two different optical lengths; a means for selecting one of the different optical lengths of the optical length correcting means according to a position of a target data recording layer in the data recording medium; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 20
Dependent Claim
138 words
A playback apparatus for an optical data recording medium, in which reproduction of data is carried out by directing a light beam onto the optical data recording medium having at least two data recording layers and detecting a reflected or transmitted light, comprising: a light source for emitting a light beam; an objective lens for converging the light beam from the light source on a data recording layer; an optical length correcting means provided between the objective lens and the optical data recording medium and having at least two different optical lengths; a means for selecting one of the different optical lengths of the optical length correcting means according to a position of a target data recording layer in the data recording medium; and a photodetector for detection of the transmitted or reflected light from the recording medium.
Claim 21
Dependent Claim
31 words
A playback apparatus according to Claim 15, wherein a difference between the different optical lengths of the optical length correcting means is equal to a distance between the data recording layers.
Claim 22
Dependent Claim
23 words
A playback apparatus according to Claim 15, wherein the optical length correcting means is arranged movable corresponding to a target data recording layer.
References Cited (Backward Citations)
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