Information recording medium

Claim 2

An information recording medium to be illuminated with an optical radiation beam, comprising: a substrate having a surface provided with a pre-format pattern comprising a servo track and forming a sectional shape, in transverse to the servo track, which comprises a concavity disposed between two convexities, each having a flat top, and a light-reflecting layer formed by application of a coating liquid over the surface, wherein said light-reflecting layer has a different thickness at the concavity than at the convexities; wherein the concavity has a sectional shape, in transverse to the servo track direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the concavity, one of the parallel sides constituting the bottom of the concavity being shorter than the opposite side, each of the sloping sides forming an angle θ that is greater than 0 but not larger than 35 degrees with respect to the extension of the surface, the concavity having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 3

A medium according to claim 1, wherein said light-reflecting layer comprises an organic coloring matter.

Claim 4

A medium according to claim 1, wherein the angle θ formed between the sloping side and the recording surface is in the range of 15 to 35 degrees.

Claim 5

A medium according to claim 2, wherein the organic coloring matter comprises a polymethine-type coloring matter.

Claim 6

A medium according to claim 1, wherein the angle θ between the sloping side and the recording surface is in the range of 20 to 30 degrees.

Claim 7

A medium according to claim 1, wherein said light-reflecting layer has a larger thickness at the concavity than at the convexities of the pre-format pattern.

Claim 8

A medium according to claim 6, wherein said light-reflecting layer has a thickness showing substantially the maximum reflectivity at the convexities and a thickness showing substantially the minimum reflectivity at the concavity of the pre-format pattern.

Claim 9

A medium according to claim 1, wherein the concavity of the pre-format pattern has a depth in the range of 1500-3700 Å.

Claim 10

A medium according to claim 1, wherein the concavity of the pre-format pattern has a depth in the range of 2000-3000 Å.

Claim 11

A medium according to claim 1, wherein the concavity of the pre-format pattern has a depth in the range of 2500-3000 Å.

Claim 12

An information recording-reproduction method, comprising illuminating an information recording medium with an optical radiation beam having a wavelength λ to effect recording or reproduction of information; said information recording medium comprising a substrate having a surface provided with a pre-format pattern comprising a servo track and forming a sectional shape, in transverse to the servo track, which comprises a concavity provided between two convexities, each having a flat top, and a light-reflecting layer formed by wet application of a coating liquid over the surface, wherein said light-reflecting layer has a different thickness at the concavity than at the convexities; wherein the concavity has a sectional shape, in transverse to the servo track direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the concavity, one of the parallel sides constituting the bottom of the concavity being shorter than the opposite side, each of the sloping sides forming an angle θ that is greater than 0 but not larger than 35 degrees with respect to the extension of the surface, the concavity having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 13

An information recording-reproduction method, comprising illuminating an information recording medium with an optical radiation beam having a wavelength λ to effect recording or reproduction of information; said information recording medium comprising a substrate having a surface provided with a pre-format pattern comprising a servo track and forming a sectional shape, in transverse to the servo track, which comprises a concavity provided between two convexities, each having a flat top, and a light-reflecting layer formed by wet application of a coating liquid over the surface, wherein said light-reflecting layer has a different thickness at the concavity than at the convexities; wherein the concavity has a sectional shape, in transverse to the servo track direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the concavity, one of the parallel sides constituting the bottom of the concavity being shorter than the opposite side, each of the sloping sides forming an angle θ that is greater than 0 but not larger than 35 degrees with respect to the extension of the surface, the concavity having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 14

A method according to claim 11, wherein the information medium being recorded on and having the angle θ formed between the sloping side and the substrate surface further limits the range of the angle θ from 15 to 35 degrees.

Claim 15

A method according to claim 11, wherein the information medium being recorded on and having the angle θ formed between the sloping side and the substrate surface further limits the range of the angle θ from 20 to 30 degrees.

Claim 16

A method according to claim 11, wherein said light-reflecting layer, of the information medium being recorded on, has a larger thickness at the concavity than at the convexity of the pre-format pattern.

Claim 17

A method according to claim 11, wherein said light-reflecting layer, of the information medium being recorded on, has a thickness showing substantially the maximum reflectivity at the convexity and a thickness showing substantially the minimum reflectivity at the convexity of the pre-format pattern.

Claim 18

A method according to claim 11, wherein the concavity of the pre-format pattern of the information medium being recorded on, has a depth in the range of 1500-3700 Å.

Claim 19

A method according to claim 11, wherein the concavity of the pre-format pattern, of the information medium being recorded on, has a depth in the range of 2000-3000 Å.

Claim 20

A method according to claim 11, wherein the concavity of the pre-format pattern, of the information medium being recorded on, has a depth in the range of 2500-3500 Å.

Claim 21

An information recording medium to be illuminated with an optical radiation beam, comprising: a substrate having a surface provided with tracking grooves, the tracking grooves being separated from each other by a recording track which forms a flat surface, and alight-reflecting layer formed by application of a coating liquid over the surface, wherein said light-reflecting layer has a different thickness at the tracking groove than at the recording track, wherein each tracking groove has a sectional shape in transverse to the tracking groove direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the groove, one of the parallel sides constituting the bottom of the groove being shorter than the opposite side, each of the sloping sides forming an angle θ of not larger than 35 degrees with respect to the extension of the surface, the groove having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 22

An information recording medium to be illuminated with an optical radiation beam, comprising: a substrate having a surface provided with tracking grooves, the tracking grooves being separated from each other by a recording track which forms a flat surface, and alight-reflecting layer formed by application of a coating liquid over the surface, wherein said light-reflecting layer has a different thickness at the tracking groove than at the recording track, wherein each tracking groove has a sectional shape in transverse to the tracking groove direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the groove, one of the parallel sides constituting the bottom of the groove being shorter than the opposite side, each of the sloping sides forming an angle θ of not larger than 35 degrees with respect to the extension of the surface, the groove having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 23

A medium according to claim 19, wherein said light-reflecting layer comprises an organic coloring matter.

Claim 24

A medium according to claim 20, wherein the organic coloring matter comprises a polymethine-type coloring matter.

Claim 25

A medium according to claim 19, wherein the angle θ formed between the sloping side and the substrate surface is in the range of 15 to 35 degrees.

Claim 26

A medium according to claim 22, wherein the angle θ formed between the sloping side and the substrate surface is in the range of 20 to 30 degrees.

Claim 27

A medium according to claim 19, wherein said light-reflecting layer has a larger thickness at the tracking groove than at the recording track.

Claim 28

A medium according to claim 19, wherein said light-reflecting layer has a thickness showing substantially the maximum reflectivity at the recording track and a thickness showing substantially the minimum reflectivity at the tracking groove.

Claim 29

A medium according to claim 19, wherein the tracking groove has a depth in the range of 1500-3700 Å.

Claim 30

A medium according to claim 26, wherein the tracking groove has a depth in the range of 200-3000 Å.

Claim 31

A medium according to claim 27, wherein the tracking groove has a depth in the range of 2500-3000 Å.

Claim 32

An information recording-reproduction method, comprising illuminating an information recording medium with an optical radiation beam having a wavelength λ to effect recording or reproduction of information; said information recording medium comprising a substrate having a surface provided with tracking grooves, the tracking grooves being separated from each other by a recording track which forms a flat surface, and alight-reflecting layer formed by wet application of a coating liquid over the surface, wherein said light-reflecting layer has different thicknesses at the tracking groove than at the recording track wherein each tracking groove has a sectional shape, in transverse to the tracking groove direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the groove, one of the parallel sides constituting the bottom of the groove being shorter than the opposite side, each of the sloping sides forming an angle θ of not larger than 35 degrees with respect to the extension of the surface, the groove having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 33

An information recording-reproduction method, comprising illuminating an information recording medium with an optical radiation beam having a wavelength λ to effect recording or reproduction of information; said information recording medium comprising a substrate having a surface provided with tracking grooves, the tracking grooves being separated from each other by a recording track which forms a flat surface, and alight-reflecting layer formed by wet application of a coating liquid over the surface, wherein said light-reflecting layer has different thicknesses at the tracking groove than at the recording track wherein each tracking groove has a sectional shape, in transverse to the tracking groove direction, of an open trapezoid having a pair of parallel opposite sides and a pair of sloping sides constituting walls of the groove, one of the parallel sides constituting the bottom of the groove being shorter than the opposite side, each of the sloping sides forming an angle θ of not larger than 35 degrees with respect to the extension of the surface, the groove having a depth d larger than λ/4n, wherein λ denotes the wavelength of the optical radiation beam and n denotes the refractive index of the substrate.

Claim 34

A method according to claim 29, wherein the angle θ formed between the sloping side and the substrate surface is in the range of 15 to 35 degrees.

Claim 35

A method according to claim 30, wherein the angle θ formed between the sloping side and the substrate surface is in the range of 20 to 30 degrees.

Claim 36

A method according to claim 29, wherein said light-reflecting layer has a larger thickness at the tracking groove than at the recording track.

Claim 37

A method according to claim 29, wherein said light-reflecting layer has a thickness showing substantially the maximum reflectivity at the recording track and a thickness showing substantially the minimum reflectivity at the tracking groove.

Claim 38

A medium according to claim 29, wherein the tracking groove has a depth in the range of 1500-3700 Å.

Claim 39

A medium according to claim 34, wherein the tracking groove has a depth in the range of 2000-3000 Å.

Claim 40

A medium according to claim 35, wherein the tracking groove has a depth in the range of 2500-3500 Å.