| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus servo acquisition controller which can perform safe and secure focus servo acquisition and defocusing detection even if a recording medium varies in thickness or reflection factor. SOLUTION: The controller is equipped with total reflection signal generating means 9 and 10 which detect the total reflection from the recording medium 1 and generate a total reflection signal, focusing point error signals generating means 8 and 11 which detect defocusing on the recording medium and generate a focusing point error signal, an objective driving means 6 which generates a sine-wave signal for moving up and down an objective 4 over the recording medium by sine-wave vibration and a cosine wave signal having a 90 deg. phase delay behind the sine-wave signal, and an OR means 12 which ORs the total reflection signal, focusing point error signal, and cosine-wave signal, thereby controlling the servo to the focusing position in the timing of the focusing point signal outputted by the OR means.
|
