| US 7,539,121 B2 | ||
| Optical recording medium and process for producing the same | ||
| Morio Tomiyama, Nara (Japan); Shinya Abe, Osaka (Japan); Yuuko Kawaguchi, Osaka (Japan); and Eiji Ohno, Osaka (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Appl. No. 10/550,069 PCT Filed Apr. 01, 2004, PCT No. PCT/JP2004/004778 § 371(c)(1), (2), (4) Date Sep. 21, 2005, PCT Pub. No. WO2004/090882, PCT Pub. Date Oct. 21, 2004. |
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| Claims priority of application No. 2003-101160 (JP), filed on Apr. 04, 2003. | ||
| Prior Publication US 2007/0117046 A1, May 24, 2007 | ||
| Int. Cl. G11B 7/24 (2006.01) | ||
| U.S. Cl. 369—275.4 | 20 Claims |
| 1. An optical recording medium comprising:
a first substrate having first pits on one face thereof;
a first reflective layer formed on the face bearing the first pits of the first substrate in a manner so as to reflect lands
and recesses of the first pits;
a second substrate formed on the first reflective layer, with second pits being formed on a face on the side opposite to the
first reflective layer;
a second reflective layer formed on the face bearing the second pits of the second substrate in a manner so as to reflect
lands and recesses of the second pits; and
a cover layer formed on the second reflective layer,
wherein a first pit depth d1, which is a difference between lands and recesses of the first reflective layer, a wavelength λ of signal-reproducing laser
light and a refractive index n1 of the second substrate satisfy the following relational expressions,
λ/(5n1)≤d1≤λ/(3n1) and d1≠λ/(4n1),
wherein a second pit depth d2, which is a difference between lands and recesses of the second reflective layer, the wavelength λ of signal-reproducing
laser light and a refractive index n2 of the cover layer satisfy the following relational expressions,
λ/(5n2)≤d2≤λ/(3n2) and d2≠λ(4n2),
wherein the first pits of the first substrate and the second pits of the second substrate are formed by a combination of concave-shaped
pits and convex-shaped pits or a combination of convex-shaped pits and concave-shaped pits,
wherein the first pit depth d1 is a difference between lands and recesses of the first reflective layer, and the second pit depth d2 is a difference between lands and recesses of the second reflective layer, and
wherein the first pit depth d1 and the second pit depth d2 satisfy the following relational expressions, with respect to the refractive index n1 of the second substrate, the refractive index n2 of the cover layer and the wavelength λ of signal-reproducing laser light,
4n1d1<λ<4n2d2.
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