| 摘要 |
PURPOSE:To obtain a simple, low-cost and easily fixable position detecting device by removing a signal having relation with a control quantity from a servo means to drive and control a recording medium, obtaining the rotational angle of a mobile body and from this and traveling distance, calculating its own position. CONSTITUTION:At present, when the mobile body rotates clockwise at a point P1, an enclosure in which an optical pick-up is fixed rotates clockwise, therefore, the relative velocity of the pick-up and a disk 1 changes and the rate of a clock signal to be obtained from a demodulating circuit 3 becomes lower than a clock rate from a reference oscillator 5. The difference in these rates are detected by a comparator 4, integrated by an integration circuit 6, supplied to spindle motor 7 as a control signal and its rotational speed is increased. At this time, on the output side of an A/D converting circuit 17, a signal S1 is obtained as angular acceleration information at the point of time corresponding to the point P1. The signal S1 is integrated twice and a signal S3 is obtained as the rotational angle of the mobile body. Since the control signal of the motor 7 changes in proportion to the angular acceleration, when this is detected, the angular rotation can be detected and from this and the output of a distance sensor 21, its own position is obtained. |
