PURPOSE: To accurately grasp the life of recorded information in the actual use state by forming a second information recording means whose detection sensitivity is lower than that of a first information recording means.
CONSTITUTION: a first recording hole 2 having a normal diameter is formed as the first information recording means on an optical disk to additionally record first desired information; and second recording holes 14, 13, and 12 which are smaller than the first recording hole 2 and has a detection sensitivity lower than that of the first recording hole 2 are formed as the second information recording means at the time of production of the like of the optical disk to record picture information like a desired test pattern. Since specific picture information like the test pattern recorded by the second recording holes having a lower detection sensitivity is first made unreadable by the degradation in the use process of the optical disk, a user can be accurately previously informed of disappearance (life) of first information recorded by the first recording hole 2.
OKUMURA MASAHIRO
UCHIYAMA HAJIME
SUZUKI YOSHIO
FUJINAWA MASAAKI
SHIMIZU HIROO
KUBUSHIRO NAOAKI
KANEMA SEIICHI
