JPS6470956A - Disk rotation controller - Google Patents

Abstract

PURPOSE:To obtain a reproducing signal having a small quantity of jitters by correcting the difference of rotation conditions between a previous rotation and a present rotation with the information at the present rotation and forecasting-controlling the rotation of a disk so that an H interval at the time of reproduction can be the same as the specified value. CONSTITUTION:A signal recorded at a disk 2 is reproduced, amplified 4 by a head 3, and separated to a synchronizing signal H used at the internal circuit and a reproducing signal to an external part by a separating circuit 5. In an arithmetic circuit 11, an arithmetic value v3 is calculated, a delaying signal v4 to subtract an electric and mechanical type lag time from the time when the disk 2 is rotated once is generated, and outputted to an arithmetic circuit 14. Further, a representative value v2 and the arithmetic value v3 of the rotation control signal of a motor 1 are delayed only by the time equivalent to the H period of a constant (a) only with a delaying circuit 13, correcting delaying signals v6 and v7 are generated and sent to the circuit 14. At the circuit 14, by the signals v6 and v7, and a multiplication correction factor (b), the signal v4 is corrected, and a correction arithmetic value v is corrected. The value v5 is sent through an LPF 15 to a motor driving device 16 as a control signal v1. The feedback control for reproduction is executed and the jitter is minimized.