Patent ID: 7864469

Claim:
An information recording medium where data track patterns and servo patterns are formed on at least one surface of a substrate by concave/convex patterns with plural convexes, at least protruding end parts of which are formed of one of a recording material and a non-recording material, and concaves, which are filled with another of the recording material and the non-recording material, wherein the concave/convex patterns that construct the data track patterns are formed so that the convexes and the concaves are disposed in one of concentric circles and a spiral, the concave/convex patterns that construct the data track patterns and the servo patterns are divided into plural ring-shaped regions that are concentric with the data track patterns, in the concave/convex patterns that construct the servo patterns, unit convex lengths and unit concave lengths are set in each ring-shaped region so that a unit convex length along a direction of rotation of the substrate and a unit concave length along the direction of rotation become longer in each ring-shaped region from an inner periphery of the ring-shaped region to an outer periphery of the ring-shaped region in proportion to a distance from a center of the data track patterns and so that a value produced by dividing an average of the unit convex length inside each ring-shaped region by a distance from the center of the data track patterns to the ring-shaped region and a value produced by dividing an average of the unit concave length inside each ring-shaped region by a distance from the center of the data track patterns to the ring-shaped region decrease from an inner-periphery ring-shaped region to an outer-periphery ring-shaped region, the plural ring-shaped regions are composed of an innermost ring-shaped region, an outermost ring-shaped region, and plural first ring-shaped regions between the innermost ring-shaped region and the outermost ring-shaped region, and respective lengths along a radial direction of the substrate of the first ring-shaped regions are set so as to increase from an inner-periphery first ring-shaped region toward an outer-periphery first ring-shaped region.