Abstract: A latch mechanism for use in a disc drive rotary actuator and like magnetic device includes a selectively energizable electromagnet mounted to the actuator and spaced from the magnets, and a ferrous arm pivotally attached between the magnets and the electromagnet whereby the latch arm can assume two stable positions of low magnetic reluctance for stray flux from the magnets. In one position the latch arm pivots towards the magnets and engages the rotary actuator. In the other position, the latch arm pivots towards the electromagnet and disengages the rotary actuator. Positioning of the latch arm is dependent on momentary energization and polarity of the electromagnet.

Abstract: In an information storage system having a plurality of data storage medias which may be read and/or written onto by multiple read/write heads carried by a plurality of aligned head arms, a damping device is provided for reducing vibrations within the head arms. The damping device is formed of a compressible viscoelastic material having a relatively high loss factor.

Abstract: A mounting structure for a spindle motor assembly is disclosed that is capable of reducing acoustic noise generated by the motor assembly. Standard spindle motor assembly parts are provided with a viscoelastic stator mounting system that isolates and damps vibrations between the rotor assembly and the rest of the spindle motor assembly. Additionally, rotor slots are provided in the rotor cap. The slots are designed to ensure that the resonant frequency of the rotor cap is substantially different than the switching frequency of the motor itself.

Abstract: Each spacer separating adjacent discs in a magnetic disc drive includes an insert having a body portion having a height equal to the height of the spacer and with a plurality of finger portions extending from the body portion less than one-half the thickness of a disc, the finger portions separating a disc from the hub and permitting movement of a disc relative to the hub during temperature cycling. Each insert further includes a plurality of cavities in the body portion in association with the finger portions for accommodating a finger which might be folded during assembly of the discs on the hub.

Abstract: A gate generator useful for validating readout signals incorporates three channels, including differentiators and threshold comparators, and a logic circuit coupled to the output circuits of the channels for passing valid readout signals. The output signals of the comparators and of detected zero crossings derived from a differentiated signal are fed to the logic circuit for processing.

Abstract: A data processing system employs a run-length limited code and incorporates an encoder and decoder sharing common circuits, including a data shift register, a code shift register and a write precompensation logic circuit. Data bits are processed as single words or double words depending upon the pattern of data bits as they are shifted.

Abstract: A crash stop assembly for use in a rotary actuator includes a folded leaf spring having two opposing spring arms joined by a base portion. The base portion is mounted to the rotary actuator with the spring arms maintained in compression. Projecting ears on the pivot block assembly of the rotary actuator engage the folded leaf spring to limit travel of the pivot block assembly.

Abstract: A linear motor having improved magnetic characteristics in driving a coil and in preventing flux leakage which is particularly useful with a magnetic disc memory. The motor includes a magnetic housing having top and bottom surfaces, side surfaces and one end surface with the end surface including integral first and second magnetic center pieces. An end plate mates with the magnetic housing with the end plate having integral first and second magnetic center pieces which mate with the first and second magnetic center pieces of the housing. First, second, and third magnets are mounted to the top and bottom surfaces and one side surface of the magnetic housing in cooperative relationship with the first center piece. Fourth, fifth, and sixth magnets are mounted to the top and bottom surfaces and the other side surface of the housing in cooperative relationship with the second magnetic center piece. A coil is coupled to the first and second magnetic center pieces and drives a carriage assembly.

Abstract: A disc servo pattern and servo detector for use in a system for reading and writing data on a magnetic disc. The magnetic disc has a servo data area formatted with a multiplicity of servo tracks which are formatted with a 1F-2F servo pattern. Each servo frame has a single sync pulse and a single position pulse at predefined positions. The 1F frames are those frames where the sync pulse and position pulse are of opposite polarity. The 2F frames are those where the sync and position pulses are of like polarity. Fill-in pulses separate neighboring sync and position pulses of like polarity.In a preferred embodiment the servo pattern in each servo track is the same as the servo pattern of the neighboring servo track shifted by one frame. Each track has a repeating pattern of two 1F frames followed by two 2F frames, and so on.The system has a servo head for reading a servo pattern on a magnetic disc and producing a servo carrier signal corresponding thereto.

Abstract: A disc transfer device for the manipulation of hard discs without damage to the recording surfaces thereof. The device is manually operated and consists of a U-shaped handle adapted for fitting over a disc storage spindle. The handle includes two grippers made of a rigid and smooth yet soft material which will not damage the disc surfaces. One gripper is fixedly attached to one end of the handle, and the other gripper is attached to a pivotable arm affixed to the other end of the handle. A lever attached to the movable arm allows for moving the arm outwards to enable a disc to fit between the grippers. A spring biases the arm in the normally closed position.

Abstract: A safety latch is provided for a disc drive to prevent accidental movement of the pickup heads across the recording surface of a disc when power to the disc drive is terminated. The safety latch includes a magnet which engages a mechanical stop for limiting the inward travel of the pickup head assembly. In a preferred embodiment the magnet is mounted on the bobbin of a linear motor which moves the pickup head assembly.

Abstract: A dual lock mechanism for a magnetic disc drive whereby rotation of the disc spindle and translation of the carriage assembly can be prevented. A first lock arm is pivotally mounted whereby one end can engage the spindle drive motor. A connector link is operated in response to rotation of the first lock arm and pivots a second lock arm within the housing into engagement with the carriage assembly.

Abstract: A combination filter system for an enclosed disc drive in which a breather filter is provided in a central position in the disc drive cover and a recirculating air filter is concentrically positioned about the breather filter. The recirculating filter includes an annular air deflector whereby air flowing from the periphery of the disc housing is filtered and directed towards the spindle, which is positioned in the central opening of the annular air deflector, thereby establishing continuous flow of filtered air within the housing.

Abstract: A linear actuator for a magnetic disc drive has shortened magnetic flux lines totally confined within the actuator housing whereby the actuator can be placed in closer proximity to a disc and thus reduce the size of the disc drive package. The actuator includes a generally cylindrical housing with magnets attached to the inside surface of the housing. A cylindrical bobbin having a voice coil wound on its periphery is positioned within the housing and linearly movable therein with the voice coil in close proximity to the magnets. An annular magnetic flux transmission means is attached to one face of the housing and a flux transmission plate is attached to the opposite face of the housing with the flux transmission means providing magnetic flux paths and preventing flux leakage from the housing.