Abstract: A limit stop/latching assembly in a disk storage system includes a crash stop for limiting travel of the actuator carriage at a fixed stop position. The assembly has a carriage latch incorporated with the crash stop. A magnetic latch actuator plate extends from the actuator carriage and is movable with the actuator carriage in a path of travel of the actuator carriage to abut the stop position. The carriage latch has a magnet and a pair of magnetic pole pieces abutting the magnet wherein the distance between the pole pieces defines a first gap and the distance between the pole pieces and the latch actuator plate defines a second gap. The latch is moved between a latched position, wherein said pole pieces are in magnetic contact with the latch plate, and a free position, wherein the actuator carriage is pivoted such that the second gap is greater than the first gap whereby magnetic flux is channeled substantially through the first gap to enable the latch plate to move remote from the crash stop.

Abstract: A limit stop/latching assembly in a disk storage system includes a crash stop for limiting travel of the actuator carriage at a fixed stop position. The assembly has a first abutment surface defining the stop position, a stop pin on the actuator carriage movable in a path by travel of the actuator carriage to abut the first abutment surface, and a latch having a second abutment surface which is movable between a free position out of the path of the stop pin and a latched position with the second abutment surface abuting the stop pin and facing the first abutment surface across the path to latch the stop pin at the stop position. Advantageously, the latch is mounted for movement around a first mounting pin in rotary travel having a center defined by the crash stop pin.

Abstract: An apparatus for detecting an over-velocity error condition of a head actuator driven by a voice coil motor in a hard disk drive system includes an integrator for providing an integrated value of the current flowing through the voice coil motor and a detector for detecting when the integrated value exceeds a threshold value. In response to this detection, the supply of current through the voice coil motor is interrupted. To prevent false detections, the integrator is inhibited until the motor current reaches a level indicative of a track access operation.

Abstract: A disk drive system has a closed loop servo control system which is specially tuned for optimal deceleration during performance of a track access operation. The servo control system is returned in response to a track jump signal to perform a track jump operation at a lesser deceleration and thereby reduce low frequency acoustic noise produced by physical vibrations of the disk drive system. The returning of the servo control system is advantageously achieved by reducing the gain-bandwidth product of the closed loop within the servo control system.

Abstract: An apparatus for supporting a read/write head at a selected one of a plurality of substantially circular, concrete data tracks and for absorbing the rebound shock of a rotary actuator, the apparatus including a head actuator assembly having at least one read/write head mounted thereon, an actuator housing, and a stationary coil coupled to the head actuator. At least one permanent magnet is fixedly mounted relative to the head actuator. Upper and lower magnetic plates support the permanent magnet and each has at least two cavities which are substantially aligned with, but displaced off-axis from, the cavities of the other plate. At least two crash stops are provided, one to limit pivoting movement of the head actuator at the inner diameter of the hard disk and the other to limit movement of the head actuator at the outer disk diameter.

Abstract: A servo shield used in small Winchester drives is provided to minimize undesired crosstalk between a data read/write head used in a stack of hard disks and servo information that is provided on an adjacent disk. In the present invention, one surface of a middle disk is provided with servo information which is used to make certain that the head drive assembly, or actuator, positions the heads above the center of the data track regardless of thermal effects or other factors that might introduce errors. In order to avoid crosstalk between the data head and the adjacent servo head reading the servo information, a servo shield formed of a suitable material, preferably berylium copper, is positioned between the servo head and its adjacent corresponding read/write head. This servo shield is mounted interiorly of the housing and slides between the servo head and adjacent read/write head when the housing is finally assembled.

Abstract: An n-phase, m-pole (wherein n and m are integers) brushless motor is driven without use of physical rotary position detectors, such as Hall elements or the like. An harmonic component of back emf induced in the phases of the motor is detected and used to generate phase energizing signals (such as in response to zero crossings of the detected harmonic component) which, in turn, energize selected phases of the motor. Drive current is supplied to those phases which are energized by the phase energizing signal in predetermined sequence.

Abstract: A head retracting/latching apparatus for a hard or floppy disc drive includes a prong which is held during power-on conditions by an electromagnet at an unlatched position out of contact with the head assembly. When power is interrupted, the head assembly is energized to move the heads to a retracted "home" position. The prong is released by the electromagnet and moves by spring force towards a latched position contacting the head assembly to prevent its movement as long as power remains off.

Abstract: A circuit for accurately detecting the number of tracks crossed by a reading head during motion thereof across a record medium uses a state machine operation to detect track crossing transitions and to suppress the effect of noise. The head produces a signal which assumes one of four unique states in sequence as successive tracks are crossed. The circuit detects a valid track crossing when a generated next state is the correct next state for a present state indicated by the signal.

Abstract: A rotary actuator having at least two legs or arms extending from the distal end of a body containing a bore through which passes a shaft about which the body rotates. A frame extends from the opposite end of the body to support a flat coil which, when the actuator is assembled, cooperates with magnets to function as a rotary "voice coil". The entire structure (i.e. the legs, body and frame) is formed as a monolithic structure by casting aluminum or some other non-magnetic metal. Other manufacturing techniques may be used, such as investment casting, machining or extrusion. Hence, no assembly is needed to join the legs or the coil-support frame to the body. Flexure elements are secure to the legs and each flexure element has a hollow pin that is placed within an opening of a respective actuator leg. A ball is driven downwardly through each hollow pin to expand that pin laterally and thus wedge the flexure into firm contact with a mounting pad on the leg.

Abstract: A true average peak detector includes an input capacitor having a capacitance C and an output capacitor having a capacitance nC. N voltage samples are successively stored on the input capacitor and are transferred to the output capacitor without discharging the latter. The output voltage from the accumulated charge on the output capacitor is equal to a true average of the voltages of the n samples.

Abstract: A transducer support assembly for supporting at least two transducers in back-to-back relationship, having particular application in a disk drive of the type having a disk or disk pack therein. The support assembly includes a support leg and a pair of flexure elements mounted in common and in back-to-back relationship on and extending outwardly from the support leg. The flexure elements are of substantially the same size and shape and are formed of flexible material, such as stainless steel, or the like. Longitudinal edge members are provided on the opposite edges of each flexure element, these edge members imparting a stiffening to the flexure element and function in a manner similar to load beams. The flexure elements are mounted offset from each other on the support leg such that their central axes are laterally displaced from each other to avoid interference between a longitudinal edge member of one flexure element and a longitudinal edge member of the other.

Abstract: A moving magnet rotary actuator is provided for use in a memory device of the type having a magnetic memory disk upon which data may be stored and read. The actuator includes a rotary body coupled to one or more elongated arms which support read/write transducer heads. A permanent magnet, driven by the magnetomotive forces which are generated by the energization of a stationary coil mounted opposite and adjacent to the magnet, is mounted on and moves with the body. Rotation of the body moves the heads from track to track on the magnetic memory disk. The direction of movement is determined by the polarity of the current through the coil; and the speed and distance of actuator travel is determined by the magnitude of the current.

Abstract: An address mark whose pattern is distinguishable from information data is produced by generating a number of relatively long pulses followed by a number of relatively shorter pulses. Preferably, a binary "1" is recirculated through a first predetermined number of stages of a shift register (for a first pre-established number of times) and then through a second (different) predetermined number of stages (for a second pre-established number of times). A signal level transition which defines the beginning or end of a pulse in the address mark pattern is generated in response to each binary "1" output from that shift register. The address mark pattern is detected by, preferably, supplying an input signal to be detected to the same aforementioned shift register, detecting n successive longer pulses and then detecting m successive shorter pulses, where n and m are less than the aforementioned first and second pre-established numbers, respectively.

Abstract: The head assembly of a disc drive device is retracted upon the interruption of power to that device by utilizing the emf that is generated by the disc drive spindle motor as a result of the rotation of that motor following power interruption. Then, after a delay sufficient to allow the head assembly time to retract, the spindle motor is dynamically braked. Dynamic braking is achieved by utilizing a voltage to which a capacitor has been charged during normal operation to energize switching elements which effectively short circuit the motor windings.

Abstract: An n-phase DC motor is controlled by converting a motor speed command signal generated from a programmed CPU to a motor drive signal and using this motor drive signal to apply DC power to a selected phase of the motor, the amount of applied DC power being a function of the value of the motor speed command signal. Signals representing the position and/or speed of the motor are supplied to the CPU from which the CPU detects speed errors. The speed command signal then is modified to speed up or slow down the motor so as to reduce the detected errors.

Abstract: A venturi or other air deflecting means is provided on the inside of the casing of a disc drive. The venturi or air deflecting means is arranged so that air, which is caused to move by the rotating disc, passes it and creates the lowest pressure inside the disc casing. This low pressure area is communicated to atmospheric pressure.

Abstract: In a device for retrieving and recording (read/write) information on at least one rigid disk, a stepping motor servo system operated in an open-loop manner is provided to rapidly and accurately position read/write heads relative to the disk. A fixed guide shaft adjacent to and transverse to the motor shaft carries a carriage slidably thereon, preferably on oil impregnated bearings, the carriage member including a gear rack and the stepping motor having a pinion gear thereon interfacing with the gear rack. A preload bearing is urged against the carriage at a position between the guide shaft and the pinion gear such that the carriage is rotated around the guide shaft into engagement with the pinion gear at the rack portion thereof.

Abstract: A ventilation and filtration system and method for an enclosure isolating a memory device spinning disk mechanism from airborne contaminants in which a vent through a remote filter from the ambient atmosphere is positioned with one opening adjacent the center portion of the spinning disk whereby the enclosure is vented through the filter to the ambient pressure at a location at substantially the lowest pressure within the enclosure as a result of the air pumping action of the spinning disk to thereby over pressurize the remainder of the enclosure and minimize unfiltered leaks of outside air into the enclosure.