Abstract A motor-driven turntable supports, for rotation therewith, a concentric ring having a plurality of permanently magnetized poles of alternate polarity symmetrically disposed along its periphery. A magnetizable core includes a pair of pole pieces having spaced surfaces defining an air gap across which magnetic flux is directed when a winding on the core is energized with alternating current. The magnetizable core is fixedly mounted such that the permanently magnetized poles pass, a seriatim, through the core gap when the turntable is rotating. The magnetized ring and the energized core form a synchronizer which opposes deviations of the turntable speed from a predetermined speed corresponding to the winding energization current frequency divided by half the number of the poles. A capacitor is connected in series with the synchronizer winding for establishing a load which exhibits a resonance at the winding energization current frequency. Means, including a crystal controlled oscillator and a frequency divider, are provided for developing a square wave output at the winding energization current frequency. Means, comprising a power amplifier including transistors operating in a switching mode, are provided for applying the square wave output of the developing means to the resonant load.
Inventors
👤 Shunji Hagino
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-30 19:37
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/20; G11B19/28
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
225 words
A speed control apparatus comprising: (A) a mounting plate; (B) a turntable secured for rotation on said mounting plate; (C) a ring concentrically secured to said turntable for rotation therewith; said ring having a plurality of permanently magnetized poles of alternate polarity symmetrically disposed along its periphery; (D) rotating means; (E) variable coupling means for transferring motion of said rotating means to said turntable; (F) a magnetizable core including a pair of pole pieces having spaced surfaces defining an air gap; said magnetizable core being fixedly secured to said mounting plate such that said permanently magnetized poles pass in succession through said core gap when said turntable is rotating; (G) a winding for establishing an alternating magnetic field across said core gap when it is energized with alternating current; wherein said magnetized ring and said energized core form a synchronizer for opposing any departures of the turntable speed from a predetermined speed corresponding to the frequency of the winding energization current divided by half the number of said poles; (H) a capacitor in a circuit relationship with said core winding for establishing a load which exhibits a resonance at said winding energization current frequency; (I) means for developing a square wave output at said winding energization current frequency; and (J) means for applying said square wave output of said developing means to said resonant load.
Claim 2
Dependent Claim
225 words
A speed control apparatus comprising: (A) a mounting plate; (B) a turntable secured for rotation on said mounting plate; (C) a ring concentrically secured to said turntable for rotation therewith; said ring having a plurality of permanently magnetized poles of alternate polarity symmetrically disposed along its periphery; (D) rotating means; (E) variable coupling means for transferring motion of said rotating means to said turntable; (F) a magnetizable core including a pair of pole pieces having spaced surfaces defining an air gap; said magnetizable core being fixedly secured to said mounting plate such that said permanently magnetized poles pass in succession through said core gap when said turntable is rotating; (G) a winding for establishing an alternating magnetic field across said core gap when it is energized with alternating current; wherein said magnetized ring and said energized core form a synchronizer for opposing any departures of the turntable speed from a predetermined speed corresponding to the frequency of the winding energization current divided by half the number of said poles; (H) a capacitor in a circuit relationship with said core winding for establishing a load which exhibits a resonance at said winding energization current frequency; (I) means for developing a square wave output at said winding energization current frequency; and (J) means for applying said square wave output of said developing means to said resonant load.
Claim 3
Dependent Claim
22 words
An apparatus as defined in claim 1 wherein said applying means comprises a power amplifier including transistors operating in a switching mode.
Claim 4
Dependent Claim
65 words
An apparatus as defined in claim 1 wherein said developing means comprises: (A) a crystal controlled oscillator operating at a frequency which is several orders of magnitude greater than, but an integral multiple of, said winding energization current frequency; and (B) a frequency divider coupled to the output of said crystal controlled oscillator for generating said square wave output at said winding energization current frequency.