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US 2012/0069726 A1Published application
Optical Storage Focus Servo System And Method Of Controlling Same
AssigneeOracle International Corporation
InventorFaramarz Mahnad
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Abstract
An optical storage focus servo system may include an optical pickup unit that includes an astigmatic focusing lens, a focusing actuator that controls a position of the lens relative to an optical media, and a plurality of detectors that detect an intensity and shape of a reflected beam from the media. The system may also include a controller that controls the focusing actuator based on the intensity and shape of the reflected beam.
Claims20
An optical storage focus servo system comprising:
- an optical pickup unit including an astigmatic focusing lens, a focusing actuator that controls a position of the lens relative to an optical media, and a plurality of detectors configured to detect an intensity and shape of a reflected beam from the media;
- and
- a controller configured to control the focusing actuator based on the intensity and shape of the reflected beam.
An optical storage focus servo system comprising:
- a controller configured to receive information representing an intensity and shape of a beam reflected from an optical media, to generate a focus error signal based on the information representing the intensity and shape of the reflected beam, and to control a position of an astigmatic focusing lens relative to the optical media based on the focus error signal.
A method for controlling an optical pickup unit, the method comprising:
- detecting a shape of a beam reflected from an optical media in a vicinity of the optical pickup unit;
- generating an s-curve signal based on the shape of the reflected beam;
- detecting an intensity of the reflected beam;
- generating a sum-curve signal based on the intensity of the reflected beam;
- generating a focus error signal that tracks the s-curve signal for values of the sum-curve signal greater than a predefined threshold and that has a constant magnitude for values of the sum-curve signal less than the predefined threshold;
- and
- writing data to or retrieving data from the optical media in a vicinity of defects on the optical media that result in non-linear behavior of the focus error signal.
4 more elements
Dependencies are inferred from the claim text.