Patent Number: 6,167,013

Title: Information storage medium and information reproducing apparatus

Abstract: The present invention provides an information storage medium that is manufactured to have a high yield. When information is to be reproduced by an information reproducing apparatus, there is little or no undesirable influence, such as oscillation or unstableness, from the reproducing apparatus onto the information storage medium. Thus, the information reproducing apparatus is capable of performing stable information reproductions. The information storage medium comprises a pre-groove having a groove-like, continuous projections-and-recess shape and a pre-pit having an intermittent projection-and-recess shape. The level difference of the depth or the height of the projections and recesses of the pre-pit is substantially equal to that of the pre-groove. Each of the pre-pit and pre-groove has a recording surface wobbling along a predetermined curved line. Utilizing a push-pull type of tracking error detection method, a reproduction signal with a high signal-to-noise (S/N) ratio can be obtained from the recording surface of the information storage medium. The push-pull tracking error detection method divides the reproduction light at its wave front into two components, and the difference between the sum of the light returning in the positive direction and the sum of the light returning in the negative direction is found to detect a variation amount.

Inventors: Ando; Hideo (Tokyo, JP), Yamamuro; Mikio (Yokohama, JP)

Assignee: Kabushiki Kaisha Toshiba

International Classification: G11B 7/013 (20060101); G11B 7/09 (20060101); G11B 7/005 (20060101); G11B 7/00 (20060101); G11B 7/26 (20060101); G11B 7/007 (20060101); G11B 007/00 ()

Expiration Date: 12/26/2017