US 6,982,110 B2 | ||
Information recording medium and manufacturing method thereof | ||
Hisamitsu Kamezaki, Kanagawa (Japan); Yasuo Sawada, Tokyo (Japan); and Yasuhide Fujiwara, Kanagawa (Japan) | ||
Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
Filed on May 23, 2002, as Appl. No. 10/155,491. | ||
Claims priority of application No. 2001-157431 (JP), filed on May 25, 2001; and application No. 2001-195243 (JP), filed on Jun. 27, 2001. | ||
Prior Publication US 2003/0007448 A1, Jan. 09, 2003 | ||
Int. Cl. B32B 3/02 (2006.01) |
U.S. Cl. 428—64.1 | 13 Claims |
1. An information recording medium comprising:
a transparent substrate; and
a recording layer or a metal layer provided on said transparent substrate directly or via a ground layer,
wherein:
said information recording medium has a RAM area on which information is recorded, reproduced or erased, and a ROM area from
which only reproduction is made; and
an average thickness of the recording layer of said RAM area is larger than that of the recording layer or metal layer of
the ROM area.
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