Abstract: A magnetic disk drive spindle motor start routine is provided that supersedes the spindle motor primary motor control when a stuck condition, wherein one of more transducer heads are adhered to the disk surface, is found to exist at start. The motor is provided current pulses at the resonant frequency of the worst case stuck system with the sequence limited to a number of pulses that will not cause the torque amplification to exceed a value that would damage the head/suspension assemblies. In another embodiment, the stuck system is provided with a motion sensor to sense positive and negative motion during oscillation of the stuck system and provide current to the motor when motion is positive to effect torque amplification.

Abstract: A limited rotation electromechanical torsional oscillator for driving a mirror in an optical deflection system. A drive armature is mounted on a torsion bar at the opposite end from the torsion bar support. The ends of the armature lie in an air gap between two pole pieces. The magnet flux in the gap is caused to vary by means of a drive winding which results in armature rotation. Resonant frequency is varied by adjustment of the length of the torsion bar and the flux density. Q is varied by means of resistance in series with the drive winding.

Abstract: A non-impact thermal printer is formed using a pivoted stiffner-frame on which is mounted a printed circuit card-print head assembly. The card is slotted with the print heads mounted at the distal ends of the cantilevered portions to enable close compliance between print head read/write units and the print media through the torsional resilience of the circuit card cantilevered portions. Compact, simple structure is provided by having the printer control circuitry mounted on the same printed circuit card.