Magnetic disk storage apparatus

Abstract

Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

1 - 9 . (cancelled)  
   
   
       10 . A magnetic disk storage apparatus comprising: 
 a motor for rotating a magnetic disk;    a magnetic head disposed for reading information from recording tracks on the magnetic disk; and    a motor driving control circuit that controls drive currents of the motor,    wherein the motor is a multi-phase brushless motor, and wherein the motor driving control circuit of the motor performs driving by feedback control so that for a coil of one phase a first drive is implemented with an amplitude at which an applied voltage becomes equal to a source voltage, for a coil of a second phase a second drive is implemented with gradually and linearly changing voltage so that a current of sine waveform is delivered, and for a coil of a third phase a third drive is implemented so that a total current flowing through all coils becomes a predetermined current value by a PWM drive.    
   
   
       11 . The magnetic disk storage apparatus according to  claim 10 , wherein the motor driving control circuit includes an arithmetic circuit that produces, by predetermined operations, a signal driven with gradually and linearly changing voltages so that a current of sine waveform is delivered.  
   
   
       12 . The magnetic disk storage apparatus according to  claim 11 , wherein the motor driving control circuit produces, as a PWM signal, a signal driven with gradually and linearly changing voltage so that a current of sine waveform is delivered.  
   
   
       13 . The magnetic disk storage apparatus according to  claim 11 , wherein the motor driving control circuit produces, as a PWM signal, a signal driven with the feedback control.  
   
   
       14 . The magnetic disk storage apparatus according to  claim 10 , wherein coil currents fed through coils of individual phases by the motor driving control circuit are formed to have phases that are of predetermined electrical angle, corresponding to coil inductance and internal resistance, ahead of phases of back electromotive forces induced in the coils.  
   
   
       15 . The magnetic disk storage apparatus according to  claim 14 , wherein the motor driving control circuit drives coils of individual phases so that phase switching timing is off zero-crossing points of the back electromotive forces.  
   
   
       16 . The magnetic disk storage apparatus according to  claim 10 , wherein the motor driving control circuit produces signals driven with gradually and linearly changing voltages by identical operation even if phases driven by the signals are different from each other so that currents of sine waveforms are delivered.  
   
   
       17 . The magnetic disk storage apparatus according to  claim 10 , including a controller that controls the motor driving control circuit, said controller being constructed to perform control so that the total of currents fed through the coils of the phases matches a current indication value supplied from the controller, and including a current indication value correcting circuit that corrects the current indication value, taking into account fluctuations of the total current produced by the currents fed through the coils of the phases being changed according to sine waveforms.  
   
   
       18 . The magnetic disk storage apparatus according to  claim 10 , wherein the motor is a three-phase brushless motor.  
   
   
       19 . The magnetic disk storage apparatus according to  claim 10 , 
 wherein in a first stage, the first drive is implemented for the coil of the one phase, the second drive is implemented for the coil of the second phase, and the third drive is implemented for the coil of the third phase,    wherein in a stage 60 degrees ahead of the first stage, the third drive is implemented for the coil of the one phase, the first drive is implemented for the coil of the second phase, and the second drive is implemented for the coil of the third phase, and    wherein in a stage 120 degrees ahead of the first stage, the second drive is implemented for the coil of the one phase, the third drive is implemented for the coil of the second phase, and the first drive is implemented for the coil of the third phase.