Apparatus for damping rotation of turntable

Details Apparatus for damping rotation of turntable Apparatus for damping rotation of turntable

1977-08-11

1978-11-28

Schaefer, Robert K.

Electricity: motive power systems

Braking

'plugging' or application of reverse power to motor

318138, 318254, H02P 310

Patent

active

041277996

ABSTRACT:
A disc record player in which a turntable is driven by a motor comprising a rotor magnet having plural magnetic poles arranged separately along the periphery of the turntable, stator coils disposed in the magnetic field of the rotor magnet and Hall-effect elements sequentially coupled magnetically to the poles of the rotor magnet for generating output signals having polarities corresponding to the polarities of the poles of the rotor magnet, and causing the rotor magnet to rotate by supplying the output signals of the Hall-effect elements to the stator coils, wherein a first and a second speed detecting coils for generating signals having phases different from each other are disposed in the magnetic field of the rotor magnet, wherein the output signals of the first and second speed detecting coils respectively turn the gate circuit off and on and when the turntable is to be stopped, the gate circuit is turned on by the output signal of the second speed detecting coil, and wherein the rotation of the turntable is damped by controlling the polarities of the output signals of the Hall-effect elements with the output signal of the gate circuit and thereby causing the stator coils to generate the magnetic flux to rotate the rotor magnet in the reverse direction.

REFERENCES:
patent: 3466520 (1969-09-01), Aylicki et al.
patent: 3706021 (1972-12-01), Yawagida
patent: 3792329 (1974-02-01), Kuhnlein

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