Abstract: A difference counter in a servo system includes RX signal processing circuitry, TX signal processing circuitry, and a latch. The RX processing circuitry includes a RX z-hold (zero order) circuit, a RX delay circuit coupled thereto, and a RX XOR logic circuit coupled thereto for producing an RX processed signal. The TX processing circuitry includes a TX z-hold circuit, a TX delay circuit coupled thereto, and a TX XOR logic circuit coupled thereto for producing an TX processed signal. The RX and TX processed signals are fed into the latch which, in response, generates a noise-free quarter track signal. Half and full track signals are generated therefrom to further process the signal track information.

Abstract: A higher-capacity disk drive system and a higher-capacity removable disk cartridge adapted for downward compatibility with older, lower-capacity disk drive systems, wherein a unique control information format is stored on higher-capacity removable disk cartridges to distinguish them from older, lower-capacity removable disk cartridges and thereby to facilitate cartridge capacity recognition by the higher-capacity disk drive system. Upon recognizing the capacity of an inserted removable disk cartridge, the higher-capacity disk drive system can read and write data to the removable disk cartridge such that data which it stores on a lower-capacity removable disk cartridge may be read by lower-capacity disk drive systems.

Abstract: Processing of disc-drive pickup signals in a manner that maintains an approximate quadrature relationship. Second order matching filters (353, 303) process pickup signals to remove high frequency components and maintain an approximate quadrature relationship.

Abstract: An optical disk drive in which changes in rotational speed are achieved under closed loop control, avoiding significant undershoots or overshoots in speed, increasing access time and reducing power. The speed control is suitable for use in a CLV system, in an CAV/CLV scheme, or in any system in which the speed of the disk must be changed at various times. Feedback from the motor, rather than data read from the disk, determines and controls motor speed during all search operations. The disk motor servo determines the desired motor speed for a target track through a speed profile table. The speed profile table can be designed to accommodate a combination of CAV mode and CLV mode of operation such that the disk drive system can run at the maximum data transfer rate permitted by the data processing electronics, or to minimize power consumption.

Abstract: A disk drive system having downward compatibility includes a read/write head and a feedback servo controller for reading and writing information to and from a removable disk cartridge. When writing information to the data tracks of magnetic medium of a lower-capacity disk cartridge, in which the data tracks are substantially wider than the width of the read/write head, the read/write head is operated in an erase mode for several resolutions prior to writing the data. The read/write head is first shifted off track center by a small DC offset, then operated in an erase mode while being guided in a repeating oscillating pattern under closed loop servo control. The read/write head is then shifted off track center in the other direction, then again operated in an erase mode while being guided in a repeating oscillating pattern under closed loop servo control.

Abstract: The present invention provides a magnet positioned to attract and hold a portion of a head arm in a disk drive assembly. The magnet is mounted by a resilient mechanism to a support structure so that there is some overtravel when the head arm assembly contacts the magnet, to dampen the impact and prevent the head arm from bouncing away and maintain contact when the disk drive housing receives an external shock. The present invention is preferably implemented with a swing plate which extends downward from the head arm support structure and is mounted at the top portion by a spring-loaded screw. A magnet is mounted on the bottom portion of the swing plate, and interacts with a permeable iron lock pin coupled to the voice coil of the head arm assembly. A pair of locating pins extend through holes in the mid-portion of the swing plate to guide the movement of the swing plate.

Abstract: A high performance linear actuator for a memory storage device includes a carriage having bearings at opposed sides thereof for engaging a pair of rail members. One of the pair of rail members is preloaded against the respective carriage bearings to provide structural stiffness and increased resonant frequency to the carriage assembly. Another set of bearings straddle a third rail member extending medially between the pair of rail members. An electromagnetic coil motor is secured to the carriage and disposed to engage an E-frame driving magnet, with the force vector of the coil extending parallel to the rail members and proximate to the center of gravity of the carriage assembly. A plurality of read/write heads is secured laterally adjacent to the electromagnetic assembly and extend toward the magnetic storage medium. The E-frame is closed at both ends to prevent flux leakage. An electronic latch under program control engages and immobilizes the carriage whenever the system is not operating.

Abstract: A high performance linear actuator for a memory storage device includes a carriage having bearings at opposed sides thereof for engaging a pair of rail members. One of the pair of rail members is preloaded against the respective carriage bearings to provide structural stiffness and increased resonant frequency to the carriage assembly. Another set of bearings straddle a third rail member extending medially between the pair of rail members. An electromagnetic coil motor is secured to the carriage and disposed to engage an E-frame driving magnet, with the force vector of the coil extending parallel to the rail members and proximate to the center of gravity of the carriage assembly. A plurality of read/write heads is secured laterally adjacent to the electromagnetic assembly and extend toward the magnetic storage medium. The E-frame is closed at both ends to prevent flux leakage. An electronic latch under program control engages and immobilizes the carriage whenever the system is not operating.

Abstract: A power amplifier is disclosed for controlling the current flow through a load, such as a d-c servo motor. The amplifier includes a plurality of switching elements connected in bridge fashion with the load and a predetermined power source for coupling the load across alternate output terminals of the power source in accordance with the levels of a plurality of control signals respectively coupled to the plurality of switching elements. Logic circuitry, when enabled, couples each of the control signals to their respective switching elements for controlling same. Sensing circuitry is coupled to the load for generating an actual current signal indicative of the actual level of current flow through the load. A current limiter is coupled to the sensing circuitry for comparing the actual current signal with high and low level limit signals and for generating a current disable signal when either the actual current signal exceeds the high limit signal or the low limit signal exceeds the actual current signal.

Abstract: Apparatus is disclosed for controlling the current flow through first and second loads, such as motors, to thereby control the direction and speed of the motors. The apparatus comprises a first power amplifier connected to the first motor and including an oscillator for generating an oscillator signal having a predetermined frequency of oscillation and circuitry responsive to the oscillator signal for developing a first control current through the first motor. A second power amplifier is connected to the second motor and includes circuitry responsive to the same oscillator signal for developing a second control current through the second motor. The oscillator signal is coupled from the oscillator of the first power amplifier to the circuitry of the second power amplifier, whereby the second power amplifier is slaved to the first power amplifier.

Abstract: A power amplifier is disclosed for controlling the current flow through a load. The power amplifier includes a plurality of switching elements connected in bridge fashion with the load and a first predetermined power source for coupling the load across alternate output terminals of the power source in accordance with the levels of a plurality of control signals respectively applied to the plurality of switching elements. Circuitry is coupled to a second predetermined power source for generating the control signals. Logic circuitry, when enabled, is capable of coupling each of the control signals to the respective switching element. A power monitor circuit compares the voltage level of the second power source with a predetermined reference potential and generates a current disable signal when the voltage level is less than the reference potential.