Self-synchronizing clock source for optical memories
AssigneeXerox Corporation
InventorsRoger D. Bates, Gordon R. Knight
Life of this patent
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Abstract
Periodic clock pulses are pre-recorded on each servo track of an optical disk to provide a local self-synchronizing source of clock frequency information for read only or direct read after write optical digital disk memories. In keeping with accepted practices, the servo track or tracks additionally function as references for controlling the radial positioning of a read head or a read/write head of such a memory.
Claims7
A digital optical memory for use with a recording medium having at least one band of tracks, each such band including at least one data track for storing data and a servo track containing periodic clock pulses;
- said memory comprising
- optical means for simultaneaously focusing a first light beam on said data track and a second light beam on said servo track, whereby said first and second light beams are modulated in accordance with said data and said clock pulses, respectively;
- servo control means coupled to said optical means for maintaining said second light beam on said servo track;
- and
- detector means positioned to intercept said first and second modulated light beams, thereby simultaneously providing a first signal representing said data and a second signal representing a local source of clock frequency information.
Dependencies are inferred from the claim text.