| 摘要 |
PURPOSE:To access at high speed by approximating a quadratic function used for converting time/track to be linearity, using a linear function obtained from the linear approximation and converting time information into the number of tracks. CONSTITUTION:Data recorded on a CD 1 are reproduced by a reproducing pickup 3 and sent via an RF amplifier 4 to a digital signal processing circuit 5, servo signal processing circuit 6 and a high speed track detector 11. A system controller 10 calculates a difference (time information) between a track positioned presently and a target track to be positioned based on address data DA and TOC data of CD 1, and converts it into the number of tracks by using the linear function. Different linear functions are provided for individual linear speeds respectively and selected in response to a linear speed of a CD to be reproduced. Then, the linear speed is corrected based on the amt. of an error between the actual count value and the number of tracks calculated by using the selected linear function. By this method, since the linear speed is corrected in advance in response to the CD 1, the search of a CD with a different linear speed can thus be speeded up.
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