Tracking servo setting method and apparatus
OwnerTakeshi Maeda, Kazuo Shigematsu +3inventors
InventorsTakeshi Maeda, Kazuo Shigematsu, Shigeru Nakamura, Yoshito Tsunoda, Masuo Kasai
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Abstract
This invention relates to a track setting method for a tracking servo system in an optical disk device and a device therefor. According to this invention the track passage velocity when the light spot moves across the track is detected and setting of the light spot onto the track is performed under the condition that the passage velocity thus detected is lower than a predetermined velocity. In the case where the passage velocity is greater than the predetermined velocity, the light spot is forced to move so that the passage velocity is lower than the predetermined velocity and the light spot is set up thereafter.
Claims16
A track setting method for a tracking servo system in which a light spot is projected onto a recording medium on which a guide groove of a plurality of tracks is formed in advance, a light flux coming from said recording medium is opto-electrically transformed, a tracking error signal representing deviations of the center of said light spot from a center line of said track is detected using the output obtained by the opto-electrically transformation, and the position of the projected light spot is controlled using said tracking error signal so that said light spot follows said track, comprising the steps of:
- detecting a passage velocity at which said light spot moves across said track, based on said tracking error signal;
- determining an intensity signal representing the light intensity of said light flux coming from said recording medium using said output obtained by said opto-electric transformation;
- and
- determining a timing signal for beginning a setting operation for setting said light spot on said track by generating a pulse representing a moment in time at which said light spot moves across substantially said center line of said track using said tracking error signal, said timing signal being generated substantially in synchronism with said pulse only when said passage velocity is lower than a predetermined minimum velocity value.
A track setting device comprising:
- tracking error detection means for projecting a light spot onto a recording medium on which a guide groove formed of a plurality of tracks is formed in advance and for detecting a signal representing deviation of said light spot from a center line of said track based on a light flux reflected from said recording medium;
- tracking control servo system means for controlling the projected position of said light spot, based on an output of said tracking error detection means, such that said light spot follows said track;
- light intensity detection means for detecting an intensity signal representing the light intensity of said light flux reflected from said recording medium;
- timing signal generation means connected to said tracking error detection means and said light intensity detection means for determining a passage velocity at which said light spot moves across said track, and for generating a timing signal for beginning a setting operation of said tracking control servo system on the condition that said passage velocity thus detected is lower than a predetermined minimum velocity value, said timing signal generation means comprising;
- a velocity detector, connected to said tracking error detection means, for detecting said passage velocity based on an output of said tracking error detection means, a track center detection means connected to said tracking error detection means and said light intensity detection means, for generating a pulse representing a moment in time at which said light spot moves across substantially said center line of said track, and a timing circuit for generating said timing signal substantially in synchronism with said pulse output from said track center detection means only when said passage velocity from said velocity detection means is lower than said predetermind minimum velocity value.
Dependencies are inferred from the claim text.