Start up circuit for continuous sine-wave commutated brushless motors

A tape drive mechanism, comprising:

• means for setting phase angle counters for a shaft for a takeup motor and for a shaft for a supply motor to predetermined values;
• means for locking out the supply motor;
• means for incrementing the phase angle counter for the takeup motor;
• means for generating a ramp scaler for the takeup motor;
• means responsive to the phase angle counter for the takeup motor and ramp scaler for the takeup motor for generating a plurality of phase differentiated armature currents;
• means for detecting a direction of rotation of the takeup motor;
• means responsive to the takeup motor rotating in an undesired direction for reversing the direction of the armature currents;
• means responsive to encountering an index mark defining take up motor rotation position for setting the phase angle counter to a predetermined base phase value and locking out the takeup motor while enabling the supply motor;
• means for incrementing the phase angle counter for the supply motor;
• means for generating a ramp scaler for the supply motor;
• means responsive to the phase angle counter for the supply motor and ramp scaler for the supply motor for generating a plurality of phase differentiated armature currents for the supply motor;
• means for detecting a direction of rotation of the supply motor;
• means responsive to the supply motor rotating in an undesired direction for reversing direction of the armature currents;
• and
• means responsive to encountering an index mark for the supply motor for setting the phase angle counter for the supply motor to a predetermined base phase value and enabling the takeup motor.