Method and apparatus for correcting the loop gain of a servo loop in accordance with measurements during open-loop operation
AssigneePioneer Electronic Corporation
InventorsMasanori Suzuki, Kiyoshi Tateishi
Life of this patent
Estimating the term…
Abstract
A servo loop particulary useful for a focusing or tracking servo in an optical disk. The peak-to-peak value of an error signal in the servo loop is detected while the optical pickup is being driven perpendicularly to the disk in focusing or transversely to the disk in tracking. The detected peak-to-peak value is used to adjust the gain of a variable gain amplifier included in the servo loop.
Claims15
A method of correcting a loop gain of a servo loop, said servo loop being of the type wherein an error signal is derived from signal representing the condition of an object and wherein said object is driven toward a desired condition in accordance with said error signal, said method comprising the steps of:
- opening a servo loop;
- changing the condition of said object to cause said error signal to pass through an upper peak representing a maximum error in a first direction and a lower peak of said error signal representing a maximum error in a second direction;
- detecting a peak-to-peak value of an error signal of said servo loop while said servo loop is open, wherein said peak-to-peak value represents the difference between said upper and lower peaks of said error signal;
- adjusting an amplification gain in accordance with said detected peak-to-peak value;
- closing said servo loop;
- and
- operating said closed servo loop including amplifying said error signal by said adjusted amplification gain.
An apparatus for correcting a loop gain of a servo loop, said servo loop being of the type wherein an error signal is derived from a signal representing the condition of an object and wherein said object is driven toward a desired condition in accordance with said error signal, said apparatus comprising:
- a servo loop including an error detection signal source, a variable gain amplifier receiving an output of said error detection signal source and switching means for opening and closing said servo loop;
- means for changing the condition of said object while said switching means has opened said servo loop to cause said error signal to pass through an upper peak representing a maximum error in a first direction and a lower peak of said error signal representing a maximum error in a second direction;
- means for detecting a peak-to-peak value of said error detection signal while said switching means has opened said servo loop, wherein said peak-to-peak value represents the difference between said upper and lower peaks of said error signal;
- means for setting a gain constant according to said detected peak-to-peak value;
- and
- means for controlling a gain of said variable gain amplifier according to said set gain constant.
Dependencies are inferred from the claim text.