| 摘要 |
The effects of vertical perturbations of a gramophone disc record surface resulting from e.g. record warp and rumble are reduced by sensing the perturbations and compensating therefor by closed loop or open loop means. Thus a reference path adjacent the groove tracked by the main stylus may be tracked, e.g. by a supplementary stylus riding on the lands of the disc surface or photoelectrically. A reference path signal may then be derived by a reference path sensor 104, and this signal is then applied to a preferably closed loop servo 95, 98, 100, 112, 114, 97 which moves the disc 9 itself up and down to tend to null out the reference path signal. Alternatively the compensation is applied by causing the tone arm to track the reference path by a servo technique or by mechanical coupling within the cartridge or electrically by subtracting the reference path signal from the main stylus signal, or by a combination of such techniques. <IMAGE> |
