Positioning device for optical disc apparatus

A positioning system of an optical disc apparatus according to the present invention comprising:

• tracking error detection means for detecting a tracking error signal as an off-track error of a light spot tracing the track on the optical disc;
• light spot radially moving means for moving the light spot substantially in the radial direction of the optical disc;
• fourth digital arithmetic means for receiving said tracking error signal and outputting a fourth control signal;
• fifth digital arithmetic means for receiving said tracking error signal and a sixth control signal, performing arithmetic operations of a disturbance observer and outputting a fifth control signal;
• adding means for adding said fourth control signal and said fifth control signal and outputting said sixth control signal;
• seventh digital arithmetic means for receiving the sixth control signal and outputting a seventh control signal;
• and
• radially drive means for driving the light spot radially moving means by the sixth control signal and the seventh control signal,
• wherein said fourth digital arithmetic means and said fifth digital arithmetic means perform arithmetic operations at different sampling periods.

A positioning system of an optical disc apparatus according to the present invention comprising:

• focus error detection means and tracking error detection means for respectively detecting a focus error signal as a focal shift of a light spot relative to an information recording surface of an optical disc and an off-track error of the light spot tracing the track on the optical disc;
• light spot moving means for moving the light spot in a direction intersecting substantially perpendicularly to the optical disc surface and light spot radially moving means for moving the light spot substantially in the radial direction of the optical disc surface;
• first digital arithmetic means for receiving the focus error signal and outputting a first control signal;
• second digital arithmetic means for receiving said focus error signal and a third control signal, performing arithmetic operations of a disturbance observer and outputting a second control signal;
• first adding means for adding said first control signal and said second control signal and outputting said third control signal;
• drive means for driving the light spot moving means in a direction intersecting perpendicularly to the disc surface by said third control signal;
• fourth digital arithmetic means for receiving said tracking error signal and outputting a fourth control signal;
• fifth digital arithmetic means for receiving said tracking error signal and a sixth control signal and outputting a fifth control signal;
• second adding means for adding said fourth control signal and said fifth control signal and outputting said sixth control signal;
• seventh digital arithmetic means for receiving said sixth control signal and outputting a seventh control signal;
• and
• radially driving means for driving the light spot radially moving means by the sixth control signal and the seventh control signal,
• wherein said first and second digital arithmetic means perform arithmetic operations respectively at different sampling periods, and said fourth and fifth digital arithmetic means perform arithmetic operations at different sampling periods.