Patent ID: 6065231
Filing Date: 2000-05-23
Classification: G11B

Abstract:
A motor drive method of a synchronous spindle motor for use in a record disc drive of an information recording device, the method comprising:producing a rotating magnetic field at substantially equal pitches in an air gap by a stator winding having a number of poles P (poles); andapplying an excitation voltage v(t) to the stator winding so as to drive said motor at a number of revolutions n(rps) relative to time t;wherein said excitation voltage v(t) has a waveform which is not a sinusoidal waveform or a square wave but a continuous waveform which exists in a region bounded by the sinusoidal waveform and the square wave both having a maximum valve Vm(V) of a voltage amplitude and a synchronous frequency n.multidot.P/2(Hz) and being equal to each other in phase, wherein said excitation voltage v(t) has a voltage gradient having an absolute value which does not exceed eight times the gradient of the sinusoidal commercial power supply waveform at a zero-crossing 8.pi.Vm.multidot.n.multidot.P(V/s), and wherein the voltage gradient before and after commutation of said excitation voltage v(t) has a maximum absolute value of 2.pi.Vm.multidot.n.multidot.P(V/s) or more.