| 摘要 |
2.1 In playback devices which can scan a rotating disc at constant orbital velocity, when jumping from one track to a target track the speed control circuit is opened and the speed of the disc is controlled by means of a second control circuit to the value required for the target track. As soon as the scanner has reached the target track, the speed control circuit is closed again. 2.2 In order to do without the second control circuit, before playing back, the pulse-width ratio of the control signal which is required in order for an electric motor to turn the disc at the speed specified for a particular track is determined and stored for each disc. When jumping from track to track, the pulse-width ratio required for the target track is calculated from the stored pulse-width ratio. A control signal with the calculated pulse-width ratio is applied to the electric motor, in order for the speed of the disc to be adjusted to the value required for the target track. As soon as the target track is reached, the speed control circuit is closed again. 2.3 CD players, video disc players, DRAW disc players and magneto-optical equipment. |
