Recording disk and producing method therefor

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially-outer periphery of the overlay is substantially within a radially-outer periphery of the substrate -as seen in an axial direction of the recording disk, wherein the substrate includes a main surface on which the overlay is arranged and a side surface which extends radially outward from the main surface and is prevented from extending parallel to the main surface, and the overlay extends to a boundary between the main surface and the side surface.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially-outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk, wherein the substrate includes a main surface on which the overlay is arranged and a side surface which extends radially outward from the main surface, is prevented from extending parallel to the main surface and exposed to an environment of the recording disk, the overlay includes a front surface extending substantially parallel to the main surface and exposed to the environment of the recording disk and an edge surface extending radially outward from the front surface, prevented from extending parallel to the front surface and exposed to the environment of the recording disk, and an angle between the main surface and a tangential line of the edge surface is more than 90 degrees.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially-outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk, wherein the substrate includes a main surface which extends substantially perpendicular to the axial direction and on which the overlay is arranged, and a side surface which extends radially outward from the main surface and is prevented from extending parallel to the main surface, the overlay includes a front surface extending substantially parallel to the main surface and exposed to the environment of the recording disk and an edge surface extending radially outward from the front surface, prevented from extending parallel to the front surface and exposed to the environment of the recording disk, and the radially-outer periphery of the front surface extends substantially along the boundary between the main surface and the side surface.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk,

• wherein the substrate includes a main surface which extends substantially perpendicular to the axial direction and on which the overlay is arranged, and a side surface which extends radially outward from the main surface and is prevented from extending parallel to the main surface, the overlay includes a front surface extending substantially parallel to the main surface and exposed to the environment of the recording disk and an edge surface extending radially outward from the front surface, prevented from extending parallel to the front surface and exposed to the environment of the recording disk, and the radially-outer periphery of the front surface extends at a radially inner side with respect to the boundary between the main surface and the side surface.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk, wherein the substrate includes a main surface which extends substantially perpendicular to the axial direction and on which the overlay is arranged, and a side surface which extends radially outward from the main surface and is prevented from extending parallel to the main surface, the overlay includes a front surface extending substantially parallel to the main surface and exposed to the environment of the recording disk and an edge surface extending radially outward from the front surface, prevented from extending parallel to the front surface and exposed to the environment of the recording disk.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially-outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk, and a radial distance between the radially-outer periphery of the overlay and the radially-outer periphery of the substrate is not more than 40 μm.

A recording disk comprising a substrate including a plastic material, and an overlay arranged over the substrate and including a recording substance for recording therein an information, wherein a radially-outer periphery of the overlay is substantially within a radially-outer periphery of the substrate as seen in an axial direction of the recording disk, wherein the overlay includes a front surface extending substantially parallel to the main surface and exposed to the environment of the recording disk and an edge surface extending radially outward from the front surface, prevented from extending parallel to the front surface and exposed to the environment of the recording disk, and an outer periphery of the front surface extends at a radially inner side with respect to an outer periphery of the edge surface.

A method for producing a recording disk including a substrate and an overlay on the substrate, comprising the steps of:

• forming the substrate including a plastic material,
• forming on the substrate the overlay including a recording substance for recording therein an information, and
• removing a radially-outer peripheral part of the substrate after forming the overlay.