| 摘要 |
In a record player having a tone arm support moved, as by a rotated screw or other feeding device, in a feeding path that is in parallel, spaced relation to a radius of the turntable so that a pickup stylus depending from the tone arm will move linearly along that radius in tracking the groove of a record disc on the turntable with the tone arm in a predetermined angular relationship to the feeding path, and in which any deviation of the speed of movement of the tone arm support by the feeding device relative to the speed of movement of the stylus by its engagement with the record groove is accompanied by angular displacement of the tone arm from the predetermined angular relationship to the feeding path; a periodic signal has an angular characteristic thereof, such as, the frequency or phase, varied in accordance with detected angular displacements or deviations of the tone arm from the predetermined angular relationship to the feeding path, a reference signal of constant frequency or phase is compared with the periodic signal of varying frequency or phase, respectively, to provide a corresponding control signal, and such control signal varies the speed of movement of the tone arm support by the feeding device in the sense to eliminate the angular displacement or deviation of the tone arm from the predetermined angular relationship.
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