United States Patent m
Maeda et al.
 OPTICAL MEMORY AND INFORMATION PROCESSING APPARATUS
 Inventors: Yoshihito Maeda, Mito; Isao Scuta, Iwaki; Masaichi Nagai, Hitachi; Yoshimi Katou, Takahagi; Hisashi Andoh, Hitachi; Nobuyoshi Tsuboi, Ibaraki; Hiroyuki Minemura, Hitachi; Tatsuya Sugita, Hitachi; Yoshio Sato, Hitachi; Yutaka Sugita, Tokorozawa, all of Japan
 Assignee: Hitachi, Ltd., Tokyo, Japan
 Appl. No.: 618,980
 Filed: Nov. 28,1990
 Foreign Application Priority Data
Nov. 29, 1989 [JP] Japan 1-307715
 Int. CI.* G11B 23/03
 U.S. CI 369/291; 360/133
 Field of Search 369/100, 291, 289, 275.5;
360/133, 132, 131
 References Cited
U.S. PATENT DOCUMENTS
4,535,434 8/1985 Kiski 369/291
4,698,797 10/1987 Komatsu 369/116
4,740,447 4/1988 Itoh 369/284
4,796,139 1/1989 Faber 360/133
4,908,817 3/1990 Sandell et al 360/133
5,077,726 12/1991 Dodds et al 369/291
5,093,174 3/1992 Suzuki et al 369/286
FOREIGN PATENT DOCUMENTS
59-198546 11/1984 Japan 369/291
[ii] Patent Number: 5,371,730  Date of Patent: Dec. 6,1994
61-079581 5/1985 Japan .
60-243836 12/1985 Japan .
63-251290 10/1988 Japan .
64-25378 1/1989 Japan .
64-30087 1/1989 Japan .
Primary Examiner—Paul M. Dzierzynski
Assistant Examiner—Kiet T. Nguyen
Attorney, Agent, or Firm—Antonelli, Terry, Stout &
The invention relates to an optical memory in which an optical recording medium is built in a case, and also to a memory apparatus. Recording, reproducing and erasing operations are performed by irradiating light via a transparent portion of the case onto the built-in optical recording medium. The optical recording medium built in the case has face vibrations with respect to the case, because it is moved within the case. The present invention is characterized by employing such a construction for optically mitigating irregular fluctuation in reflectivity caused by this face vibration. In the optical memory of the present invention, the reflectivity fluctuation caused by an interference effect made between reflection light from the case and air, and also reflection light from the optical recording medium and air due to the relative deviation in the face vibrations, may be reduced by antirefiection films provided in the case and the optical recording medium. In a memory apparatus of the present invention, the abovedescribed memory is mounted, the fluctuation in the reflectivity is monitored and laser power is varied in order to further mitigate the reflection vibrations.
23 Claims, 13 Drawing Sheets