Magnetic disk drive

Claim 1

A magnetic disk drive comprising: a carrier (52) for supporting a magnetic head (51) for reading or writing data on a rotating magnetic disk (50); a motor (53) for moving said carrier (52), a drive circuit (PA) for driving said motor (53); and a control circuit (CT) for applying a control signal and an adhesion release signal to said drive circuit (PA); said drive circuit (PA) including : a bridge circuit (1) consisting of four transistors (Q1 to Q4) for driving a coil (VCM) of said motor (53), one pair of opposite junctions of said transistors being connected to a first and second power source respectively, and the other pair of transistor junctions being connected to both ends of said coil (VCM); a pair of control amplifiers (2,3) for controlling said bridge circuit (1) to drive said coil (VCM) in a positive or negative direction in accordance with a control input signal from said control circuit (CT), by which one pair of opposing transistors (Q1 and Q4, or Q2 and Q3) are turned ON at the same time; an adhesion control circuit for controlling said bridge circuit (1) to drive said coil (VCM) in one direction in accordance with an adhesion release commmand from said control circuit (CT) before said disk (50) begins to rotate, and which turns ON only one of said four transistors connected to one end of said coil (VCM) and connects an opposing end of said coil to a medium level point between said first and second power source.