Abstract: Methods and systems are described for correcting repeatable runout. In one aspect, an open loop tracking signal is received and squared. A discrete Fourier transform (DFT) of the squared open loop tracking signal is obtained. A velocity magnitude and an absolute value of the phase of the open loop tracking signal is determined. A RRO correction signal is iteratively constructed by performing a partial correction based on an initial phase selected and an initial velocity amplitude, measuring a relative velocity amplitude, performing a partial control correction using the initial phase and relative velocity amplitude if the amplitude is smaller than an initial amplitude or using the initial phase rotated by one hundred eighty degrees and the relative velocity amplitude if the amplitude is larger than an initial amplitude, and repeating the above steps until a tracking controller can perform closed loop control of the track to optical pickup unit velocity.

Abstract: Methods and systems are described for correcting repeatable runout. In one aspect, an open loop tracking signal is received and squared. A discrete Fourier transform (DFT) of the squared open loop tracking signal is obtained. A velocity magnitude and an absolute value of the phase of the open loop tracking signal is determined. A RRO correction signal is iteratively constructed by performing a partial correction based on an initial phase selected and an initial velocity amplitude, measuring a relative velocity amplitude, performing a partial control correction using the initial phase and relative velocity amplitude if the amplitude is smaller than an initial amplitude; performing a partial control correction using the initial phase and the relative velocity amplitude if the amplitude is smaller than an initial amplitude, and repeating the above steps until a tracking controller can perform closed loop control of the track to optical pickup unit velocity.

Abstract: A method of determining a correction factor for a voice coil motor of a disk drive device is performed by driving a relatively low current through the voice coil motor during a seek operation. Actuator velocity is then measured. A correction factor is calculated as a function of the actuator velocity to allow estimation of velocity as a function of back EMF.

Abstract: A method and device for parking heads of a disk drive device involves receiving a command to immediately park the heads. A first pulse is provided to a voice coil motor causing the heads to move toward a parked position. After the first pulse, the VCM current is reduced substantially (e.g., close to zero) and back EMF in the voice coil motor is measured to determine speed of the heads. The voice coil motor is iteratively pulsed, and back EMF is measured between pulses to track a desired velocity profile to park the heads.

Abstract: A method of determining a correction factor for a voice coil motor of a disk drive device is performed by driving a relatively low current through the voice coil motor during a seek operation. Actuator velocity is then measured. A correction factor is calculated as a function of the actuator velocity to allow estimation of velocity as a function of back EMF.

Abstract: Improved deceleration control for a disk drive is provided. A deceleration profile is selected based on a present velocity (vi), a present position (xi) and a BEMF constant associated with a voice coil motor (VCM), wherein the deceleration profile is useful for moving the read/write head to a point in phase space (defined by a target velocity and a target position) where it is efficient to hand-off control of a seek operation from a deceleration controller to a seek controller. A control signal is supplied to a VCM driver in an attempt to have a read/write head follow the selected deceleration profile. As new present velocities and new present positions are obtained, these steps are repeated until the seek operation transitions from the deceleration phase to a settle phase. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures and the claims.

Abstract: Improved deceleration control for a disk drive is provided. A deceleration profile is selected based on a present velocity (vi), a present position (xi) and a BEMF constant associated with a voice coil motor (VCM). A control signal is supplied to a VCM driver in an attempt to have a read/write head follow the selected deceleration profile. As new present velocities and new present positions are obtained, these steps are repeated until the seek operation transitions from the deceleration phase to a settle phase. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures and the claims.

Abstract: An actuator in a disc drive is controlled to position a transducer over a target track on a disc surface. Movement of the actuator is initiated so the transducer begins moving toward the target track. The actuator is decelerated, as the transducer approaches the target track, according to a deceleration curve which is varied based on drive characteristics.

Abstract: A write drive logic circuit is described. The write driver logic circuit comprises a set of write drivers, with each one of the set of write drivers having an input and an output, such that each write driver is responsive to an input signal applied to the input to provide a write output signal at the output as a function of the input signal. A set of memory devices (e.g. shift registers) is provided, one for each write driver. Each one of the shift registers stores unique head identification information and includes an output to controllably output a signal representative of the unique head identification information. Furthermore, each one of a set of multiplexers includes an output, a first input coupled to a corresponding one of the outputs of the set of shift registers to receive the signal representative of the unique identification information stored in the respective shift register and a second input coupled to a common write data line that transmits a signal representative of preselected information.