| 摘要 |
PROBLEM TO BE SOLVED: To lessen the unbalance of groove part and land part by specifying the width of the flat part of the bottom of guide groove to a size smaller than half the groove pitch and setting the angle formed by the slopes at the boundary between the groove and the land and the horizontal plane of a board smaller than 90 deg.. SOLUTION: The board 11 is produced by an injection method using a polycarbonate resin and has pits (holes) indicating information, such as guide groove address signals, on its surface. Aluminum is laminated by sputtering or vapor deposition as a reflection film 12 thereon. The angle formed by the sloped parts near the bottom parts of the grooves and the flat plane is inclination of >=30 deg. without exceeding 90 deg.. More preferably the angle is 40 to 70 deg.. The groove width and effective land width on the optical disk board can be made equal to each other according to the board and, therefore, the regenerative signal outputs of nearly the same degree are obtainable when the signals are recorded on both of the groove part 21 and the land part 22. |
