Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2006-05-30
2006-05-30
Hindi, Nabil (Department: 2655)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S124120
Reexamination Certificate
active
07054242
ABSTRACT:
A system for controlling focus in an optical disc drive for optical media with a premastered area that cannot be overwritten and a user-writeable area that can be overwritten includes instructions for turning focus on and off; and for acquiring focus on the optical media in response to a command to acquire focus. The actuator arm is moved according to a sinusoidal ramp function to prevent exciting resonances in the actuator arm. The amount of push-away force used while moving the actuator arm can be adjusted to avoid overshoot. The integrity of a focus error signal is determined and an attempt to re-acquire focus is made if the focus error signal indicates a bad focus status. The system turns focus off when at least one of the following conditions are met: (1) current state is a ramp focus acquire state and the maximum ramp position was reached; (2) current state is a focus push retry state and best push away value is greater than or equal to a predetermined fraction of a nominal push away value; or (3) a focus problem develops while in a focus active state.
REFERENCES:
patent: 5113387 (1992-05-01), Goldsmith et al.
patent: 5199011 (1993-03-01), McDonald et al.
patent: 5606536 (1997-02-01), Watanabe et al.
patent: 6714493 (2004-03-01), Kishimoto et al.
Kadlec Ron J.
Turner Christopher J.
Watt Charles R.
DPHI Acquisitions, Inc.
Hallman Jonathan W.
Hindi Nabil
McPherson Kwok Chen & Held
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