Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1985-01-25
1987-11-10
McElheny, Jr., Donald
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
365 51, 369 59, 371 68, G11B 7013, G11B 2110
Patent
active
047062355
ABSTRACT:
Apparatus and methods are disclosed for writing data on a track in an optical disk data storage device wherein the track is divided into two parts and binary one bits are written into one part of the data track while binary zero bits are written into the second part of the data track. Detection of data written in this manner is performed using two read coherent radiation beams each positioned over one of the parts of the data track. A binary one is detected if the signal from the beam over the first part of the data track is greater than the signal from the beam over the second part of the data track, and a binary zero is indicated if the signal from the beam over the second part of the data track is greater than the signal of the beam over the first part of the data track. In order to detect the data from the two read beams, they must be aligned accurately over the two halves of the data track. To aid this alignment, a third larger beam is used to measure the total energy from the data track. If the beams are not aligned correctly over the track, the signal output from the large beam will exceed the sum of the signal outputs from the two smaller read beams indicating the offtrack condition and further indicating the direction of the offtrack condition.
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Marks et al., "Distillation Optical Storage", IBM Tech. Disc. Bul., vol. 25, No. 11A, Apr. 1983, pp. 5523-5524.
McElheny Jr. Donald
Storage Technology Partners 11
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