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US 4,918,678 AGranted
Disc reproducing system for compensating mechanical imperfections
OwnerRay M. Dolbyinventor
Life of this patent
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Abstract
Means for reducing the effects of vertical perturbations of a phonograph disc surface resulting from disc and/or playback system mechanical imperfections. Such imperfections are compensated by closed loop and/or open loop means wherein the deviations of the record path are detected and employed to minimize the effects of the mechanical imperfections.
Claims12
A phonograph disc playback apparatus comprising:
- a turntable, adapted to support a disc thereon, said disc having position-modulated signal grooves thereon and spurious vertical deviations affecting the modulations of the signal grooves;
- a cartridge;
- said cartridge including means for reproducing the modulations of the signal grooves on the disc to provide an audio signal, wherein the effects of said vertical deviations on the modulations of the signal grooves are also reproduced by said reproducing means as noise in the audio signal;
- reference path sensor means for sensing the spurious vertical deviations of the disc on the turntable, said sensor means providing a second signal to indicate the vertical deviations;
- and
- an actuator responsive to the second signal from the sensor means for moving the portion of the disc at the cartridge with respect to the cartridge to reduce noise in the audio signal caused by the spurious vertical deviations of the disc at the cartridge.
3 more elements
A phonograph disc system comprising:
- first cutting stylus means for impressing on the disc a position-modulated signal groove in relation to a quiet vertical reference position;
- second cutting stylus means for impressing a substantially quiet defined land surface on the disc representative of the vertical reference position;
- a turntable, adapted to support the disc thereon;
- a cartridge;
- sensor means for sensing any vertical deviation of the land surface of the disc on the turntable;
- and
- an actuator responsive to a signal from the sensing means for moving the portion of the disc at the cartridge to reduce any vertical deviation of the disc at the cartridge.
4 more elements
Dependencies are inferred from the claim text.