Seagate Technology Incorporated

Jeffrey SoonBeng Sim

Joseph HengTung Lau

Stephen KowChiew Kuan

Terang KongBeng Thia

CheeWai Seetoh

The present invention provides a method to determine and to locate the position of the imbalance torque of an actuator in a disc drive. There are several steps performing different functions in the method. The first step of the method performs the function of obtaining a difference in the voice coil motor (VCM) current of the disc drive in the X orientation and in the Y orientation with the VCM current of the disc drive when the disc drive is placed flat. The second step performs the function of obtaining the square of each difference in VCM current. The third step performs the function of obtaining the imbalance by adding the square of the VCM current and subsequent square root of the addition. The valve of the imbalance torque is obtained by multiplying the imbalance with the torque constant. The fourth step performs the function of obtaining a division value of the VCM current in the X orientation or in the Y orientation with the VCM current of the disc drive when the disc drive is placed flat. The fifth step performs the function of obtaining the angle between the x-axis and the distance of the imbalance torque of the actuator from the pivot centre and measuring the mass of the actuator. The sixth step performs the function of obtaining the cosine or sine of the angle and multiple either angle with the mass of the actuator. The position of the imbalance torque is located and determined either from dividing the divided value in X orientation in the fourth step with the cosine angle in the sixth step or dividing the divided value in Y orientation in the fourth step with the sine angle in the sixth step.

Drive level actuator imbalance torque test

A preferred system for measuring bearing friction first measures voice coil motor current values required to move an actuator arm assembly to each of several cylinder position intervals. Torque values required to move the actuator arm assembly are then computed using the measured voice coil motor currents. Drive-level bearing friction values are then calculated using the computed torque values and then combined into a composite indicator.

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Singapore, Singapore

Jeffrey SoonBeng Sim