Stmicroelectronics Gmbh

Carlo Vertemara

Paolo Menegoli

Massimiliano Brambilla

Giorgio Pedrazzini

A control circuit controls a motor assembly having a coil and a movable arm. The control circuit includes a drive circuit that is coupled to the coil and that generates a drive signal in response to a control signal and a speed signal. The control circuit also includes a sensor circuit that is coupled to the drive circuit and to the coil and that generates the speed signal at a level that corresponds to the speed of the arm. In a disk drive, such a circuit can be used to control the movement of a read-write-head assembly during parking and unparking of a read-write head. The circuit monitors the speed of the head and uses this speed information as feedback to maintain the speed of the head within a specified range. This prevents damage to the head and other disk-drive components, particularly in a disk drive that incorporates a head parking platform.

Circuit and method for controlling the parking and unparking of a read-write head

A method for starting a polyphase DC motor having a rotor. The position of the rotor is detected by initiating current in each of the phases of the motor and measuring a time period between the initiation of current in the coil and an instant when the current exceeds a threshold current. The phase in which the current reaches the threshold in the shortest amount of time is the phase closest to the position of the rotor. A phase closest to the position of the rotor is identified in each of an odd number of trials, and a starting phase is selected as the phase identified in the majority of trials. The motor is started by providing current to the starting phase.

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Carlo Vertemara