| 摘要 |
PROBLEM TO BE SOLVED: To shorten an access time until the data are really reproduced from instruction of reproducing operation by using angular velocity constant information of a wobble and rotation driving an optical disk at a constant angular velocity. SOLUTION: While reproducing the optical disk, an FG signal from a non- wobble detection circuit 52 and a timing signal from an address mark extraction filter 51 are supplied to a wobble joint period detection circuit 55. The wobble joint period detection circuit 55 selectively outputs either one between these FG signal and timing signal, or both signals to a control circuit 38 through a switch 54 as a speed signal. Thus, the control circuit 38 CAV(constant angular velocity) rotation controls a spindle motor 31. Particularly, when angular velocity information is much in the outer periphery of the optical disk 11, an address detection circuit 53 or the control circuit 38 judges by a present address signal, etc., and constitutes a one round loop so that this frequency becomes constant. |
