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AssigneeTosoh Corporation
InventorsToshio Inase, Koyata Takahashi, Koji Katayama, Tatsuo Kawasaki, Kenichi Sekimoto, Toru Futami, Keiichiro Nishizawa
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A near field optical recording medium having a header area in which at least an addressing signal or a timing signal is recorded by means of a concave/convex pattern with laser light using a flying optical head. When a concave/convex portion of the concave/convex pattern is to be detected, either an effect due to a change in returning light caused by distance wherein the reflectance is changed or an effect due to a change in returning light caused by a diffraction effect is sufficiently larger, or a combination of such effects (changes by distance effect and changes by diffraction effect) are not weakened by each other, so that header information recorded by the concave/convex pattern can correctly be reproduced even in a super-high density recording medium using near field light.
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that said concave/convex pattern is constituted by concave pits or convex bumps, each width of the pits or the bumps in a direction perpendicular to a track being smaller than the beam spot, wherein |Dp−Df|/(Dp+Df)≧0.05 where Dp is an intensity of returning light returned to the optical head at a position just above a pit or just above a bump and Df is an intensity of returning light returned to the optical head in a flat portion in which no pit or bump is formed, or said concave/convex pattern is constituted by concave portions and convex portions adjacent to each other wherein in a case that returning light returned to the optical head at a position just above a step portion, which is formed at the boundary of a concave portion and a convex portion which are adjacent to each other in a direction of track, is divided into a concave side and a convex side, |Dc−Dd|/(Dc+Dd)≧0.05 where Dc is an intensity of returning light at a concave side and Dd is an intensity of returning light at a convex side.
In a near field optical recording medium wherein a pre-pit is formed in at least a surface of a substrate;
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that a change in returning light returned from the concave/convex portion formed in the header area includes at least a change due to a distance effect wherein the reflectance is changed depending on the distance between a bottom surface of the optical head and the substrate surface and a change due to a diffraction effect caused by a step, and wherein the header area is so constructed that in detecting the concave/convex portion, the effect due to the change by the distance effect and the effect by the diffraction effect are not mutually weakened each other.
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that said concave/convex pattern is constituted by concave pits, each width of the pits in a direction perpendicular to a track being smaller than the beam spot, wherein when Ht is the distance between a bottom surface of the optical head and a flat portion in which no pit is formed, and Ha is the distance between the bottom surface of the optical head and a bottom surface of a pit, the reflectance R has a negative inclination in a range of from Ht to Ha.
In a near field optical recording medium wherein a pre-pit comprising concave pits is formed in at least a surface of a substrate;
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that said concave/convex pattern is constituted by convex bumps, each width of the bumps in a direction perpendicular to a track being smaller than the beam spot, wherein when Ht is the distance between a bottom surface of the optical head and a flat portion in which no bump is formed, and Hb is the distance between the bottom surface of the optical head and an upper surface of a bump, the reflectance R has a positive inclination in a range of from Hb to Ht.
In a near field optical recording medium wherein a pre-pit comprising convex bumps is formed in at least a surface of a substrate;
In a near field optical recording medium having a header area in which at least an addressing signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that said concave/convex pattern is constituted by concave portions and convex portions which are adjacent to each other, wherein when Hc is the distance between a bottom surface of the optical head and a bottom surface of a concave portion, and Hd is the distance between the bottom surface of the optical head and an upper surface of a convex portion, the reflectance R has a positive inclination in a range of from Hd to Hc.
In a near field optical recording medium having a header area in which a header information including at least a signal for reproducing an address or a timing signal for providing datum for writing an address is recorded by means of a concave/convex pattern formed in a substrate wherein recording and/or reproducing is conducted by laser light using a flying optical head, the near field optical recording medium being characterized in that an intensity of returning light from a concave/convex portion for forming the concave/convex pattern is changed depending on the distance between a bottom surface of the optical head and the medium surface, and at least a polarity of a signal reproduced by an effect due to such change of the intensity of returning light is not opposite to a polarity of a signal reproduced by diffraction.
Dependencies are inferred from the claim text.