| 摘要 |
PURPOSE:To attain a high-speed access with a disk device by shifting the tracking to the bank part when the data is recorded at a groove part of a disk and to the groove part when the data is recorded at the bank part respectively with the focusing state kept as it is after the data is recorded. CONSTITUTION:This disk device records or reproduces the information to an optical disk by means of the focused light. A focusing means consisting of lenses 13 and 16 which focus the light sent from a light source 11 for semiconductor laser on the disk 1 is provided together with detecting means 19 and 22 which detect at least two types of signals by means of the light reflected by the disk 1 and a means which adds the reference voltage given from a reference signal generating circuit 46 to the detection signals gamma and delta detected by the means 19. Then the lens 16 is driven by coils 23 and 24 and the detection signals alpha and beta given from said adding means and the means 22 via drive circuits 48 and 35.
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