Abstract: In a hard disk drive, a head actuator periodically is caused to undertake a calibration seek such that the power amplifier that energizes the head actuator is saturated. The predicted distance moved by the head during the calibration seek is compared to the actual distance moved, and the ratio of the two distances is then used to determine the saturation current of the power amplifier. For a subsequent seek, if the saturation current is less than the current requested for the subsequent seek, the saturation current is input into the head position prediction model. Otherwise, the requested current is used.

Abstract: Real-time gain control calibration is provided for each frequency of a disk drive storage system using dual-frequency, dual-burst position error sensing (PES) signals. Automatic and independent gain control for each PES servo burst frequency component is achieved with an automatic gain control (AGC) mapping that determines the approximate head position and performs an appropriate gain calibration for each servo burst frequency or with sector by sector normalization performed for each PES signal sample. For the AGC mapping, calibration is performed either with calibration tracks or with an in situ method. Both mapping and normalization methods provide accurate automatic gain calibration during signal readback.

Abstract: A method and apparatus for controlling a spindle motor having at least one winding in a storage device are proposed, the storage device having at least one data storage medium rotatably supported by the spindle motor and having a plurality of tracks on each surface thereof including data regions and nondata regions, and a transducer assembly for selectively positioning a transducer over each data storage surface of the storage medium for reading and writing of information stored on the medium. The method and apparatus control rotation of the spindle motor by providing a voltage waveform to each winding at selected switching times during each rotation such that switching does not occur while the head is positioned over data. In a first embodiment, switching during nondata regions is assured by setting the switch points to coincide in time with a fixed data storage surface format. Alternatively, the data storage surface is written with servo sectors to coincide in time with preselected switch points.

Abstract: A method and apparatus for writing binary servo data into the servo bursts contained on the storage medium of a storage device. The binary servo information may include track identifying information such as a track number, cylinder number, head number, sector number, index and/or SID. A burst includes T time slots, each slot comprising one cycle of the servo burst frequency, and the servo data to be written comprises X bits of binary data. Each one-bit of the servo data is represented as a slot containing a transition, and each zero-bit is represented as an empty or null slot. In this manner, the present invention provides a highly bit-efficient scheme for representing digital servo data. A high quality PES signal is assured by writing the binary servo information in such a manner as to guarantee a threshold number of transitions per burst as required for accurate peak-hold detection.

Abstract: A data recording disk drive is provided with a reassignment architecture that employs both an "in-line" approach for small disk defects and an "off-site" reassignment for multiple-sector defects. As a further aspect of the invention, the defective sites that have been off-site reassigned are periodically reinspected to determine whether they in fact remain defective. If it is determined upon inspection that the defect is no longer present, the data in the off-site reassign area is returned to its original location, freeing spares for reuse. As a further aspect of the invention, reinspection is performed at disk drive spin-up or during idle periods.

Abstract: A data recording disk file having multiple actuators mounted on a common pivot axis, one of the actuators having fewer arms and lower inertia characteristics than the other. A servo system separately drives each of the actuators for seek repositioning, the lower inertia actuator having a higher performance than the other. A controller selectively records one type of data on the data surfaces associated with the lower inertia actuator, and records all other data on the other data surfaces, thereby providing a disk drive with increased performance appropriate to the data stored on the surfaces associated with the lower inertia actuator. A removable locking pin may be provided which extends through corresponding holes in each of the actuators for maintaining the actuators precisely positioned with respect to each other so that servo information may be written on each of the surfaces in a single process. Additionally, one of the actuators may be provided with a shorter stroke than the other actuators.

Abstract: Switching losses at high line in variable-input Class-D resonant DC-to-DC power converters regulated by changing the duty cycle of the switching transistors are avoided by making the turn-off time of the discharging switch dependent upon the current in the resonant transformer primary circuit, thereby preserving bidirectional zero-voltage switching. Losses due to asymmetrical high current pulses in one arm of the rectified output can be mitigated by use of MOSFETs as synchronous rectifiers to take the place of rectifying diodes.

Abstract: The present invention concerns an apparatus, method, and article of manufacture that satisfies the need for verifying the identity of a designated head in a gang servo head environment by querying a control parameter unit. In one embodiment, the invention may be implemented to provide a method to increase head select robustness for group head systems controlled by drive electronics. The method is practiced when a request is made for a designated head to perform a read or write operation. The request is received by a control parameter unit included in an arm electronics unit. The control parameter unit is then queried to verify the identity of the arm electronics unit selected. The identity of the designated head is then received. A parity check of the control data is performed and, assuming no errors, an actuating arm containing the designated head is positioned. The selected arm electronics unit is loaded with read or write data copied from a host system and transferred to or from the storage device.

Abstract: A servo control system and method for accurately controlling the actuator in a rotatable storage device by adjusting a corrective control signal according to the mode of operation of the actuator and the direction of actuator movement. During track following the corrective control signal is adjusted by a first factor determined by the ratio of a nominal force or torque factor to the actual force or torque factor at the current radial actuator position. When the actuator is seeking in a first direction, the corrective control signal is adjusted by a second factor determined by adjusting the first factor by a first amount, K.sub.fwd. When seeking in the reverse direction, the corrective control signal is adjusted by a third factor determined by adjusting the first factor by a second amount, K.sub.rev. K.sub.fwd incorporates measured variations in force or torque factor when the actuator is moving in the forward direction. Similarly, K.sub.

Abstract: An apparatus and method for reducing spindle power and acoustic noise in a self-commutating brushless d.c. motor for a disk drive adjusts the commutation angle of the motor until a point of optimum power consumption is reached. In a preferred approach implemented during disk drive operation, a direction in which to change the commutation angle is determined such that spindle power consumption is decreased. The commutation angle is the changed in the determined direction until a point of minimum spindle power consumption is identified. In order to determine the correct direction of commutation angle change, the commutation angle is varied in a first direction for so long as the spindle power consumption is decreasing. If varying the commutation angle of the motor in the first direction results in an increase in spindle power consumption, the commutation angle of the motor is varied in a second direction.

Abstract: Disclosed is a data recording disk file having multiple actuators mounted on a common pivot axis, one of the actuators having fewer arms and lower inertia characteristics than the other. A servo system separately drives each of the actuators for seek repositioning, the lower inertia actuator having a higher performance than the other. A controller selectively records one type of data on the data surfaces associated with the lower inertia actuator, and records all other data on the other data surfaces, thereby providing a disk drive with increased performance appropriate to the data stored on the surfaces associated with the lower inertia actuator. A removable locking pin may be provided which extends through corresponding holes in each of the actuators for maintaining the actuators precisely positioned with respect to each other so that servo information may be written on each of the surfaces in a single process.

Abstract: Logic for detecting the reliability of an address in Pennington code (PCODE). The address is parsed into two separate halves. The first half corresponds to the front portion of the PCODE address and the second half corresponds to the back portion of the same. The two halves are compared to determine the reliability of the address. If the address is not reliable, a head position estimation is used to position the head over the described track. If the address is reliable, the PCODE is combined with a position error signal to position the head.

Abstract: A cordless telephone arranged for operation in a frequency hopping system conserves battery power in a handset unit when this unit is located remote from an associated base unit and in a standby state. While in this standby state, the handset unit resides in a low power monitoring mode and monitors a channel pseudo-randomly selected from a plurality of available channels in the frequency hopping band for receipt of an initialization signal from the associated base unit. The base unit similarly monitors this selected one of the channels for receipt of this initialization signal from the handset unit. Should ongoing communications between the base unit and the handset unit be inadvertently interrupted, the cordless telephone quickly re-establishes communications in the frequency hopping system through an initialization process executed by both the handset unit and the base unit.

Abstract: A cordless telephone arranged for operation in a frequency hopping system automatically modifies a frequency hopping sequence in the presence of interference detected on its in-use communication channels. Substitute alternative communication channels are identified and then substituted for those communication channels experiencing the interference without disruption of communications between a handset unit in the cordless telephone and its associated base unit.