Focus detection in a digital focus servo system
First Claim
Patent Images
1. A method of detecting focus, comprising:
- obtaining a sum signal;
determining if the sum signal is below a threshold value; and
indicating a focus open condition if the sum signal is below the threshold value.
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Abstract
A system for determining whether a focus servo system is in focus or out of focus (i.e. open) is disclosed. A sum signal can be compared with a threshold value. If the sum signal is below the threshold value, then a focus open condition (i.e., out-of-focus) can be indicated. In some embodiments, a focus open condition is indicated where the sum signal remains below the threshold value for a predetermined period of time.
69 Citations
10 Claims
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1. A method of detecting focus, comprising:
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obtaining a sum signal;
determining if the sum signal is below a threshold value; and
indicating a focus open condition if the sum signal is below the threshold value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A focus servo system, comprising:
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an optical pick-up unit mounted on an actuator arm, the optical pick-up unit being positioned over an optical media;
at least one analog to digital converter that digitized signals received from detectors in the optical pick-up unit;
at least one processor coupled to receive signals from the at least one analog to digital converter and provide a control signal; and
a driver coupled to receive the control signal and control the actuator arm, wherein the at least one processor executes software that computes a sum signal from the signals received from the at least one analog to digital converter, determines if the sum signal is below a threshold value, and indicates a focus open condition if the sum signal is below the threshold value. - View Dependent Claims (8)
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9. A focus servo system, comprising:
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means for obtaining signals from an optical pick-up unit mounted to an actuator arm; and
means for determining whether the optical pick-up unit is at an in-focus position above an optical medium. - View Dependent Claims (10)
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Specification
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Current AssigneeRPX Corporation
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Original AssigneeDPHI Incorporated
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InventorsKadlec, Ron J., Watt, Charles R.
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current369/53.28
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CPC Class CodesG11B 7/0908 for focusing only G11B7/092...G11B 7/0946 specially adapted for opera...G11B 7/0948 specially adapted for detec...
