[54] UNAUTHORIZED USE PREVENTING
METHOD FOR OPTICAL DISKS, OPTICAL
DISK HAVING UNAUTHORIZED USE
PREVENTION FUNCTION, AND OPTICAL
DISK APPARATUS
[75] Inventors: Satoshi Itami; Kenichi Utsumi;
Masahiro Nakada; Hiroshi Suzuki;
Kazunori Naito; Kazuo Nakashima;
Toshikatsu Narumi; Masaru
Nakahara, all of Kawasaki, Japan
[73] Assignee: Fujitsu Limited, Kawasaki, Japan
[ * ] Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154(a)(2).
This patent is subject to a terminal disclaimer.
[21] Appl. No.: 08/730,654 [22] Filed: Oct. 11, 1996
Related U.S. Application Data
[60] Continuation of application No. 08/444,872, May 19, 1995, abandoned, which is a division of application No. 08/032, 481, Mar. 17, 1993, Pat. No. 5,418,852.
[30] Foreign Application Priority Data
Mar. 18, 1992 [JP] Japan 4-061882
Mar. 18, 1992 [JP] Japan 4-062608
Mar. 18, 1992 [JP] Japan 4-062609
May 21, 1992 [JP] Japan 4-129092
[51] Int. CI.6 H04L 9/00; G11B 7/013
[52] U.S. CI 380/4; 369/47; 380/5
[58] Field of Search 380/3, 4, 5; 369/44.33,
369/47; 360/60
[56] References Cited
U.S. PATENT DOCUMENTS
4,462,078 7/1984 Ross 380/4
