Patent EP0229035A2 successfully refreshed from Google Patents.
EP0229035A2
Expired / Lapsed
EP
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Optical recording/reproducing of information signals
Assignee: Victor Company of Japan Ltd
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Filing: 1987-01-08
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Granted: —
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Expires: 2007-01-08
Abstract
Abstract Disclosed are an information signal recording medium having pits which are formed in geometric concave or convex configuration for recording information signals and on which a light spot is applied for reproduction of the information signals, and a recording apparatus for optically recording the information signals thereon and a reproducing apparatus for optically reproducing the information signals therefrom. In the information signal recording medium, a pit width of a first pit having pit length substantially equal to half the longest recording wavelength is set to a first pit width smaller than the diameter of the light spot, a pit width of a second pit having a pit length substantially equal to half the shortest recording wavelength is set to a second pit width greater in dimention than the first pit width, and a pit width of a third pit having a pit length in-between the pit length substantially equal to half the longest recording wavelength and the pit length substantially equal to half the shortest recording wavelength is set to be equal to a pit width of a fourth pit having a pit length shorter than the pit length of the third pit or set to be smaller than the pit width of the fourth pit.
Inventors
- 👤 Osamu Tajima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 10:12
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/2407; G11B7/24085; G11B7/004; G11B7/005; G11B7/12; G11B7/135; G11B7/1395
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
145 words
An information signal recording medium having pits which are formed in geometric concave or convex configuration for recording information signals and on which a light spot is to be applied for reproduction of the information signals, characterised in that the width of pits whose length is substantially equal to half the longest recording wavelength is set to a first width smaller than the diameter of said light spot, in that the width of pits whose length is substantially equal to half the shortest recording wavelength is set to a second width greater than said first width, and in that the width of intermediate pits whose length is in-between substantially half the longest recording wavelength and substantially half the shortest recording wavelength is set to be equal to or smaller than the width of a pit whose length is shorter than that of said intermediate pit.
Claim 2
Dependent Claim
145 words
An information signal recording medium having pits which are formed in geometric concave or convex configuration for recording information signals and on which a light spot is to be applied for reproduction of the information signals, characterised in that the width of pits whose length is substantially equal to half the longest recording wavelength is set to a first width smaller than the diameter of said light spot, in that the width of pits whose length is substantially equal to half the shortest recording wavelength is set to a second width greater than said first width, and in that the width of intermediate pits whose length is in-between substantially half the longest recording wavelength and substantially half the shortest recording wavelength is set to be equal to or smaller than the width of a pit whose length is shorter than that of said intermediate pit.
Claim 3
Dependent Claim
59 words
An information signal recording medium as claimed in claim 1, characterised in that when the diameter d of said light spot is expressed by d = 0.82 À/NA where is light wavelength and NA is numerical aperture of a lens for forming the spot, at least said first width is approximately d/3 and said second width is approximately d.
Claim 4
Dependent Claim
59 words
An information signal recording medium as claimed in claim 1, characterised in that when the diameter d of said light spot is expressed by d = 0.82 λ/NA where λ is light wavelength and NA is numerical aperture of a lens for forming the spot, the width of pits whose length is substantially greater than d is approximately d/3.
Claim 5
Dependent Claim
33 words
An information signal recording medium as claimed in claim 1, 2 or 3, characterised in that the optical path difference between a pit and a land is smaller than half the light wavelength.
Claim 6
Dependent Claim
197 words
An optical information signal reproducing apparatus for reproducing information signals from an information signal recording medium by irradiating a light spot onto said information signal recording medium on which said information signals are recorded with pits formed in geometric concave or convex configuration, characterised in that it comprises a photodetector having two photosensitive elements divided into two on optical axis in a recorded trace-arranged direction in said information signal recording medium within a light path of reflected light resulting from said light spot irradiated on a signal surface of said information signal recording medium; a first adder for producing a sum signal of output signals of said two photosensitive elements of said photodetector; a subtractor for producing a difference signal between said output signals of said two photosensitive elements of said photodetector; a phase shift circuit for coinciding the phase of the output signal of said first adder with the phase of the output signal of said subtractor; and a second adder for producing a sum signal of both the output signals of said first adder and said subtractor coincident in phase with each other, the output signal of said second adder being a reproduced information signal.
Claim 7
Dependent Claim
197 words
An optical information signal reproducing apparatus for reproducing information signals from an information signal recording medium by irradiating a light spot onto said information signal recording medium on which said information signals are recorded with pits formed in geometric concave or convex configuration, characterised in that it comprises a photodetector having two photosensitive elements divided into two on optical axis in a recorded trace-arranged direction in said information signal recording medium within a light path of reflected light resulting from said light spot irradiated on a signal surface of said information signal recording medium; a first adder for producing a sum signal of output signals of said two photosensitive elements of said photodetector; a subtractor for producing a difference signal between said output signals of said two photosensitive elements of said photodetector; a phase shift circuit for coinciding the phase of the output signal of said first adder with the phase of the output signal of said subtractor; and a second adder for producing a sum signal of both the output signals of said first adder and said subtractor coincident in phase with each other, the output signal of said second adder being a reproduced information signal.
Claim 8
Dependent Claim
200 words
An optical information signal reproducing apparatus for reproducing information signals from an information signal recording medium by irradiating a light spot onto said information signal recording medium on which said information signals are recorded with pits formed in geometric concave or convex configuration, characterised in that it comprises a photodetector having two photosensitive elements divided into two on optical axis in a direction intersecting a recorded trace-arranged direction in said information signal recording medium within a light path of transmission light resulting from said light spot irradiated on a signal surface of said information signal recording medium; a first adder for producing a sum signal of output signals of said two photosensitive elements of said photodetector; a subtractor for producing a difference signal between said output signals of said two photosensitive elements of said photodetector; a phase shift circuit for coinciding the phase of the output signal of said first adder with the phase of the output signal of said subtractor; and a second adder for producing a sum signal of both the output signals of said first adder and said subtractor coincident in phase with each other, the output signal of said second adder being a reproduced information signal.
Claim 9
Dependent Claim
200 words
An optical information signal reproducing apparatus for reproducing information signals from an information signal recording medium by irradiating a light spot onto said information signal recording medium on which said information signals are recorded with pits formed in geometric concave or convex configuration, characterised in that it comprises a photodetector having two photosensitive elements divided into two on optical axis in a direction intersecting a recorded trace-arranged direction in said information signal recording medium within a light path of transmission light resulting from said light spot irradiated on a signal surface of said information signal recording medium; a first adder for producing a sum signal of output signals of said two photosensitive elements of said photodetector; a subtractor for producing a difference signal between said output signals of said two photosensitive elements of said photodetector; a phase shift circuit for coinciding the phase of the output signal of said first adder with the phase of the output signal of said subtractor; and a second adder for producing a sum signal of both the output signals of said first adder and said subtractor coincident in phase with each other, the output signal of said second adder being a reproduced information signal.
Claim 10
Dependent Claim
121 words
An optical information signal recording apparatus for recording an information signal on an information-signal recording medium by means of a pit formed in geometric concave or convex configuration by irradiating a light spot obtained by condensing a light beam intensity-modulated in accordance with said information signal, characterised in that the pit width of said pit is varied in accordance with recording wavelength, and in that said recording apparatus comprises a deflection element made of an electro-optical crystal for dividing light symmetrically to two directions with respect to the optical axis, said deflection element being within the light path and changing the cross-sectional configuration of a light beam to vary the pit width of said pit in accordance with the recording wavelength.
Claim 11
Dependent Claim
121 words
An optical information signal recording apparatus for recording an information signal on an information-signal recording medium by means of a pit formed in geometric concave or convex configuration by irradiating a light spot obtained by condensing a light beam intensity-modulated in accordance with said information signal, characterised in that the pit width of said pit is varied in accordance with recording wavelength, and in that said recording apparatus comprises a deflection element made of an electro-optical crystal for dividing light symmetrically to two directions with respect to the optical axis, said deflection element being within the light path and changing the cross-sectional configuration of a light beam to vary the pit width of said pit in accordance with the recording wavelength.
Claim 12
Dependent Claim
124 words
An optical information signal recording apparatus as claimed in claim 7, characterised in that when the principal axes of a refraction ellipsoid in terms of the electro-optical crystal resulting in an isotropic crystal or a biaxial crystal from a single axis crystal by action of electric field are X-axis, Y-axis and Z-axis and when the Z-axis is positioned in a direction that refractive index is not varied by electric field, said deflection element comprises two triangle-pole-like prisms whose oblique surfaces are attached to each other with the respective Z-axes being in parallel in opposite directions so that a combined prism is formed to symmetrically deflect the light, passing in the Z-axis direction, in two directions within an incident plane with respect to attached surfaces.
Claim 13
Dependent Claim
74 words
An optical information signal recording apparatus as claimed in claim 7, wherein said deflection element comprises a parallel polarised light deflection element made of an electro-optical crystal whose number of optical axes may be increased by action of electric field, an element deflecting light in a direction separated from the light deflected by said parallel polarised light deflection element and a half-wave plate interposed therebetween in order to refract light concurrently in two directions.
Claim 14
Dependent Claim
63 words
An optical information signal recording apparatus as claimed in claim 7 wherein said deflection element is arranged such that the Z-axis of an electro-optical crystal whose number of optical axes may be increased by action of electric field intersects the optical axis and the cross-section of light passing through is divided with a strong electric field portion and a weak electric field portion.
Claim 15
Independent Claim
48 words
A method of optically recording an information signal on an information signal recording medium in the form of a track whose reflectivity or transmittance is varied in accordance with the information to be recorded, characterised by varying the width of the track in accordance with the recording wavelength.
Claim 16
Independent Claim
48 words
A method of optically recording an information signal on an information signal recording medium in the form of a track whose reflectivity or transmittance is varied in accordance with the information to be recorded, characterised by varying the width of the track in accordance with the recording wavelength.
References Cited (Backward Citations)
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