Abstract: An electro-mechanical latch includes a solenoid having an armature movable from a normally biased first position to a second position in response to an electrical current applied to the solenoid, and means for holding the armature in the second position to allow subsequent removal of the current from the solenoid. When the armature is in its first position, it is adapted to latch a device in a parked position. The armature is non-interactive with said device in its second position. The electro-mechanical latch of the present invention further includes means for releasing the holding of the armature in response to the device returning to its parked position whereby the armature returns to its normally biased first position to latch the device. An important advantage of the present invention is that the current need be applied to the solenoid only for moving the armature to release the device. The current may then be removed since the armature will be held in a position which is non-interactive with the device.

Abstract: An environmentally controlled media defect detection system for Winchester disk drives includes a testing cabinet which is divided into two sections. The first section is maintained at an environmentally controlled elevated temperature for testing Winchester disk drives at elevated operational temperatures above ambient room temperatures. The second section is thermally insulated from the first section and contains a plurality of disk drive test units. One test unit is coupled to each Winchester disk drive being tested, and the test units have the ability to apply digital signals to the drive for writing and reading signals onto tracks of the drives, determining malfunctions, and imperfections in the disk media of the hard disk drive systems.

Abstract: A positioning system for a hard disk drive for rapidly and accurately positioning the disk head. A constant bias compensation signal is injected into the feedback loop to reduce positioning delays otherwise caused by a steady state force which is asserted against the head. High and low velocity measuring techniques are also disclosed, along with several techniques for advantageously injecting these measurements into the feedback loop at appropriate times. An improved resonant filter is also disclosed.

Abstract: A shock resistant hard disk drive system employs a plurality of magnetic disks for recording data, a plurality of magnetic heads for performing input/output operation on the magnetic disks, with at least one of the magnetic heads being used as a servo head, a head-positioning mechanism for controlling the movement of the magnetic heads, a servo control mechanism or servo loop for opposing shifts in the location of the servo head, detecting device for detecting and measuring certain accelerations applied to the system, and filtering device for filtering the output of said detecting device and for providing the signal to the head-positioning mechanism. The detecting device detects and measures the magnitude of internal or external accelerations or shocks applied to the system, and provides the necessary signals to counter such accelerations.

Abstract: The power amplifier for the head positioning coil of a Winchester or hard disk drive digital storage system includes circuitry for generating complementary variable width pulses at a frequency above 100 kilohertz. The filter coupling the positive and negative power pulses to the head positioner coil includes two oppositely poled coils mounted on a single enclosing coil to avoid D.C. saturation and to maintain high inductance for high frequency noise filtering. Circuitry is also provided for improving the common mode noise rejection capability of the feedback circuit, and the head retract circuitry.

Abstract: The head positioner for a Winchester type hard disk drive digital storage system includes a main rotating metal body portion having outwardly extending, integral, head positioning arms. The magnetic heads for reading and writing information on the hard disks are mounted on springy members which are referred to as "load beams". In order to reduce vibration, and to increase the accuracy of positioning of the heads on the disks, the outwardly extending arms from the main metallic body of the head positioner unit extend outwardly from the central axis of rotation for a distance which is substantially greater than the additional outward extent of the spring load beams upon which the magnetic heads are supported. Preferably the outward extent of the rigid arms is in the order of twice the length of the springy load beams. In addition, the bearings for supporting the rotating head positioning assembly are preferably mounted directly to the metallic body of the head positioner assembly.

Abstract: A large capacity digital storage system includes five standard 51/4 inch Winchester disk drives, a formatter for each disk drive, and a master controller for coupling to the host computer or data processor. The spindles of the disk drives are rotated in synchronism to improve data handling. Successive bytes of digital information are routed to four of the drives, and the fifth drive has parity check information; and control circuitry is provided so that any one of the five standard drives may be unplugged and replaced without interruption of storage system operation.

Abstract: An improved switching regulator power supply with a variable duty cycle is disclosed which forms part of a compact Winchester disk drive system having a storage capacity in excess of 380M bytes of information. The switching regulator is designed for frequencies in excess of 80 kilocycles per second and may therefore be construced using smaller capacitive and inductive elements. Also, very low heat dissipation and high regulator efficiency may be achieved by the improved power supply to drive a brushless D. C. motor encased within a hard disk assembly where no separate fan or cooling system is used to aid in heat removal. Circuitry is provided to control the motor speed while simultaneously limiting the motor current to a predetermined level. This is a achieved by controlling the voltage applied to the motor by suitably adjusting the duty cycle of the switching regulator.

Abstract: The subject invention provides a digital Storage System such as a Winchester Hard Disk Drive System having a motorized hard disk drive assembly which interacts with a head positioner to read and write data and timing instructions onto a plurality of disks driven by the assembly. The drive system includes a data separation circuit for reconstruction of data recorded on the hard disk. The data separation circuit includes a phase-locked loop system. The phase-locked loop system includes a phase comparison circuit, a voltage controlled oscillator, a control circuit including a capacitor for controlling said oscillator, and a charge pump for pumping up and pumping down the control circuit. Except for the phase comparison circuit, the entire phase-locked loop system is provided on a monolithic integrated chip.

Abstract: A current amplifier is provided with three active transistors of the same polarity type, which function to amplify the input signal at a wide range of frequencies, with low power consumption and low or no output crossover distortion. One transistor, in cooperation with the second transistor, significantly amplifies the current during one swing of the input singal while the third transistor is switched off, and switches on the third transistor just prior to a reversal of the input signal swing. By the proper and immediate biasing of the third transistor according to the circuit needs, low power consumption as well as low or zero output crossover distortion is achieved.

Abstract: A digital memory system of the hard or Winchester disk type, includes a series of hard disks, and pivoted mounting arms for the magnetic heads or sliders. In order to minimize the vertical, or inter-disk space occupied by the sliders and their mounting arms when used in a rotary type of head positioner, the end of a direct, or straight, mounting arm for each slider is generally ring-shaped, or of an open rectangular configuration, with the outer transverse portion of the mounting arm extending through a slot in the surface of the slider which is not intended for engagement with or proximity to the recording disk. In addition, the slider is secured to the mounting arm by a small springy resilient sheet metal member, having a broad central area with a rounded protrusion intended to engage the outer transverse portion of the ring-shaped end of the mounting arm, and being bonded to the slider at the bottom of the slot in the slider on either side of the rounded bearing member.

Abstract: A Winchester disk drive assembly includes upper and lower mounting plates and shafts for the main drive motor assembly and for the head positioner firmly connected to both mounting plates. One end of the shafts is mounted to one of the mounting plates by a shouldered washer. A shouldered washer is mounted in a counterbored hole in the adjacent mounting plate and is firmly secured to the adjacent shaft end by a steel screw, with the dimensions of the washer being selected to provide space between the enlarged head portion of the washer, and the counterbore, so that the shaft is entirely stress-free. The space between the inner surface of the enlarged portion of the T-shaped washer and the counterbored recess is then filled with epoxy which bonds the two parts together. The shouldered washer then becomes an essential part of the adjacent mounting plate, and the mounting plate may be removed and separated from the shaft by removing the steel screw.

Abstract: A Winchester or hard disk drive, with a head positioner rotor is provided with a bidirectional preloaded stop. The head positioner rotor is provided with a plate having two spaced stop surfaces, both of which engage a single stop, which may be in the form of a U-shaped spring, which is partially compressed, and which has two pivoted, high strength plastic members against which the stop surfaces of the head positioner rotor impinge. The plate may also be provided with a notch into which the armature of an electromagnet fits so that the head positioner rotor is locked in the position with the heads adjacent the drive spindle, when the drive is turned off. When the rotor is energized, and the disks get up to speed, the electromagnetic is energized, and the head positioner rotor is freed to move to a selected track for reading or writing digital information.

Abstract: The head positioner for a Winchester type hard disk drive digital storage system includes a main rotating metal body portion having outwardly extending, integral, head positioning arms. The magnetic heads for reading and writing information on the hard disks are mounted on springly members which are referred to as "load beams". In order to reduce vibration, and to increase the accuracy of positioning of the heads on the disks, the outwardly extending arms from the main metallic body of the head positioner unit extend outwardly from the central axis of rotation for a distance which is substantially greater than the additional outward extent of the springy load beams upon which the magnetic heads are supported. Preferably the outward extent of the rigid arms is in the order of twice the length of the springy load beams. In addition, the bearings for supporting the rotating head positioning assembly are preferably mounted directly to the metallic body of the head positioner assembly.

Abstract: A digital storage system of the Winchester or hard disk drive type has a magnetic head positioner within which the arm-positioning body, including the heads, is rotatably mounted about a fixed stator assembly which includes a two-part shaft assembly comprising an aluminum cylindrical sleeve thermally shrink fitted about the central portion of an aluminum shaft having a pair of fixed ends and end portions reduced in diameter relative to the central portion by means of a pair of steel bearing assemblies attaching circumferentially about the sleeve in regions exclusive of the shrink fitted central portion of the shaft assembly. The clearance thus provided between the shaft and the mounting sleeve in the regions of the bearing assembly attachment permits a degree of decoupling of mechanical resonances potentially introduced into the head position servocontrol loop by mounting stresses acting upon the shaft.

Abstract: A digital storage system of the Winchester or hard disk drive type has the annular, hard aluminum disks mounted coaxially around the drive motor. A central fixed aluminum shaft has the motor stator coils centrally mounted on it, and an aluminum disk mounting sleeve is mounted to the shaft by bearings located above and below the motor stator. To accommodate the difference in thermal coefficients of expansion between the steel cylinder forming the outer periphery of the motor's rotor and the aluminum disk assembly, the outer steel cylinder of the motor rotor is bonded to the aluminum disk sleeve by means of an elastic adhesive, which permits relative expansion between the steel and aluminum parts occasioned by changes in temperature of the drive. The rotor, including its permanent magnets and outer steel cylinder, is mounted from the inner surface of the aluminum disk mounting sleeve, with the rotor in operating proximity to the stator.

Abstract: A digital storage system of the Winchester or hard disk drive type has the hard aluminum disks mounted around the drive motor. To accommodate the difference in thermal coefficients of expansion of the steel cylinder forming the outer periphery of the motor, and the aluminum disk assembly, an aluminum disk mounting sleeve is provided which extends for the full height of the disk assembly, and makes a thermal shrink fit around the steel motor cylinder, with the engagement between the two parts being limited to a section toward the center of the overlapping surfaces of the two parts. The aluminum storage disks and spacers between them have a slight clearance from, and are clamped between the top and bottom of the aluminum mounting sleeve.

Abstract: A printed circuit motor is constructed with the printed circuit windings stationary, and therefore constituting the stator of the motor. The stator is mounted at the end of a heavy hollow supporting frame member. The rotor is mounted on the end of a shaft which is journaled within the hollow frame member, and the rotor extends outwardly in close proximity to the stator and around the outer periphery of the stator and back toward the hollow supporting member, with a permanent magnet assembly on one side of the printed circuit stator and the magnetic return path on the other side of it. The permanent magnet assembly and the magnetic return path are rigidly coupled so that no relative motion occurs between them. Electrical connections to the winding turns of the stator are brought out from the periphery of the stator close to its surface through an additional printed circuit board, and along the outer surface of the hollow frame member to pass the inner edge of the permanent magnet rotor.

Abstract: A compact, high capacity rigid magnetic disk storage system includes three 8-inch disks in an assembly only 45/8 inches high complete with electronics. The system includes two separate sections, a first section containing the electronics, the disk drive motor, and other similar active components, and a second "clean zone" section, separated by a central cast web or partition. Within the second clean zone area are a stack of three rigid disks, the recording heads, and arrangements for positioning the recording heads; and a special filtering circuit through which air is circulated over the surface of the disks. The air circulation and filtering arrangements within the second clean zone area of the system include a special hollow hub assembly on which the rigid disks are mounted, with the hub assembly having a series of spaced radial apertures opening both to the spaces between the disks and also to the end of the hub facing away from the motor.

Abstract: A magnetic recording system is provided which encodes four bits of an eight bit "byte" at a time, and is thus compatible with most general purpose data processing systems which process eight bit bytes. Also, the special magnetic recording code groups which are formed have at least two "0's" between each "1", and always include at least one "1" in each code group, thereby increasing the average frequency of magnetic transitions and reducing the requirements for the phase lock oscillator timing circuit compared to previous methods. In addition, the conversion circuitry for converting from the short data groups to the longer code groups is simplified by the use of a small "Programmable read Only Memory" or "PROM" and "EXCLUSIVE-OR" circuit logic to insure proper code bit groupings of "1's" and "0's" within each code group and at the transitions between code groups.