JPS6419562A - Clock generation circuit for detecting data of optical disk - Google Patents

Abstract

PURPOSE:To lock a PLL in a short time even when coarse positioning is performed at a zone adjacent to an object track and to realize fast seek, by using and switching three frequencies suitable for an object zone and a preceding and succeeding zones as the interpolation signal of the PLL. CONSTITUTION:To a PLL circuit 7, the fundamental frequency OSC0 of the object zone and a preceding and a succeeding frequencies OSC-1 and OSC+1 are outputted from a signal generator 12 as the interpolation signals when no reproducing signal from a disk exists, and the OSC0 of the object zone is selected by a selector 5 ordinarily. When the seek to the object track is performed, no sufficient lock is applied when a head 11 catches a little an adjacent zone since the interpolation signal of the PLL7 is the OSC0, and no reproduction of an ID part is performed. Since a microprocessor switches the interpolation signal of the PLL to the frequency of the adjacent zone in order by controlling the selector 5, the lock of the PLL7 can be performed sufficiently, then, the reading of the ID can be performed stably.