| 摘要 |
PROBLEM TO BE SOLVED: To quickly discriminate whether or not rotation control of the disk is correctly performed irrespective of a position of a pickup in a radial direction so as not to destroy data when the linear velocity of the disk falls into emergency state of low velocity, in a disk recording/reproducing device controlled by CLV(constant linear velocity). SOLUTION: In a disk device rotating a disk recording medium with predetermined marks formed on its track for every prescribed distance by a spindle motor, and irradiating a laser beam on the above track by a semiconductor laser, a period of the predetermined mark signal detected by a signal detection means to detect the predetermined mark signal relating to the above predetermined mark on the basis of a reflected light from the track is detected, and when the difference between this period and a reference period is larger than the predetermined value, power of the semiconductor laser is turned off. |
