Claims
- 1. An apparatus for moving an optical head from an initial track to a target track on a storage medium having data arranged in tracks thereon, comprising:
- a sensor for measuring a reflectivity level of light from said storage medium;
- a preamplifier responsive to said reflectivity level for generating a data signal, wherein said data signal indicates changes in said reflectivity level in response to said data;
- a tracking error signal generator responsive to said reflectivity level for deriving a tracking error signal having first zero crossings and second zero crossings;
- a track/hold selector responsive to said data signal for directing said tracking error signal generator to generate a corrected tracking error signal of a constant amplitude for a predetermined period of time when said data signal indicates changes in said reflectivity level in response to the data; and
- a track crossing signal generator based on said corrected tracking error signal, for deriving a digital track crossing signal having zero crossings corresponding to only said first zero crossings.
- 2. The apparatus according to claim 1 wherein said preamplifier contains a high pass filter through which said data signal is passed.
- 3. The apparatus according to claim 1 further comprising a track crossing counter responsive to said digital track crossing signal for counting said second zero crossings.
- 4. The apparatus according to claim 1, 2, or 3 wherein said sensor comprises a split detector for measuring said reflectivity level.
- 5. The apparatus according to claim 1, 2, or 3 wherein said sensor comprises a quad detector for measuring said reflectivity level.
Parent Case Info
This is a division of application Ser. No. 08/418,723, filed Apr. 7, 1995.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
225877 |
Jun 1994 |
TWX |
Divisions (1)
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Number |
Date |
Country |
Parent |
418723 |
Apr 1995 |
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