Abstract: An improved connector apparatus for electrically coupling a magnetic transducer to the read/write electronics of a magnetic recording system is described. The connector apparatus includes a first connector having an elongated substrate with a plurality of first bonding pads on one end connected to a corresponding plurality of second bonding pads on the other end. The invention further includes a second connector having a plurality of third bonding pads on one end connected to a plurality of fourth bonding pads on the other end. Bonding pads are included for aligning the first bonding pads with the terminals of the conductive cable that is connected to the electronics of the magnetic system and the second bonding pads with the third bonding pads to facilitate electrical interconnection between the first and second connectors.

Abstract: A sample data position error signal detection means. This invention has application in a digital servo in a magnetic media disk drive environment. In particular, the invention relates to the detection in digital form of position error signals (PES) representative of magnitude and sign of recording head displacement from a track center line. The circuits disclosed provide a digital representation of PES suitable for direct application to a digital signal processor which controls overall servo positioning operations. The invention detects the PES by employing a digital integrator which comprises a register and adder. The composite servo data is first amplified by variable gain amplifier and then undergoes low pass filtering before being digitized by an analog to digital converter (ADC). The digital integration is performed by accumulating a constant number of ADC samples in the register.

Abstract: A head loading mechanism for a disk drive. When power to the disk drive is disconnected, an actuating spring is released. Movement of the spring causes a plunger to contact a bracket on the actuator arm, moving the actuator arm over a parking zone. Further movement of the spring causes blades to lift read/write heads mounted on the actuator arm away from disk surfaces. When power is restored, a motor compresses the spring and returns the plunger and the blades to their original positions.

Abstract: An improved rotary actuator for torque linearization in a disk drive recording system is described. A notch is formed in the actuator frame at a point midway along one of the sidewalls of a pair of circumferential slots which define a centerpole member therebetween. These slots house the actuator coil. The notch increases the air gap between the coil and the frame at the midpoint of the data stroke. This reduces the flux density at the midpoint of the data stroke which linearizes the torque of the actuator as a function of the angular position of the coil (i.e., the coil arc). In addition, the dimension of the centerpole member which extends beyond the sweep of the coil during a data stroke is widened to decrease the air gap in these regions.

Abstract: In the present invention, a single sector counter and accompanying multiple buffer registers are used to provide the sector count for a plurality of recording zones. Initially, the sector counter is validated by synchronizing it with an index mark. In one embodiment, an angular position sensing counter counts a clock having a frequency and phase to match the occurrence of segments in a reference zone. A look up table or computation provides an offset value representing the difference between each reference zone segment boundary, and the occurrence of the next consecutive sector in each of the recording zones. Additional logic generates periodic sector pulses once the zone transition has been accomplished, and provides means to prevent generation of shortened sector intervals. This permits rapid validation of the sector signal so that it is no longer necessary to wait for the index in a hard-sectored drive before establishing the sector position when changing zones.

Abstract: A thermally independent dedicated servo disk drive where the temperature is kept within an acceptable range and temperature gradients that can cause differential thermal expansion are eliminated to minimize off tracking due to differential thermal expansion of thermally sensitive components. A novel isolated "box within a box" architecture is utilized to provide a thermal buffer to external temperature gradients and an inner HDA support structure is coupled to an outer housing with thermally insulative isolators which prevent the conductive transfer of heat from external sources where the outer housing and isolators create a thermal buffer to shield the inner HDA support structure from external heat sources. In addition, certain heat generating components not integrated into the symmetrical thermal "box within a box" design are isolated where possible.

Abstract: A read channel detector circuit for recovery of digital data from a readback waveform produced by a magnetic recording head is disclosed. The detector circuit includes a forward filter for slimming the rising edge and slurring the falling edge of an isolated input magnetic pulse. Quantized feedback techniques are then used to produce a compensating waveform which is substantially complimentary to the slurred falling edge of the isolated magnetic pulse. The complimentary waveform is added to the forward filter output to produce a waveform which is substantially a step function. This step function corresponds to a single digital transition, either positive-going or negative-going in a digital output sequence. The equalized waveform is then limited by a comparator to produce the desired digital output sequence.

Abstract: A magnetic recording head for longitudinal rigid-disk recording is described. The recording head is characterized by an I-bar shaped magnetic core which is attached flushly along the side of a slider body. The core has a pole body section around which a wire coil is wrapped for inducing magnetic flux changes in the media during write operations and for sensing magnetic flux which emanates from the disk surface during readback operations. The I-bar design is relatively inexpensive to manufacture, mechanically durable and improves overall head performance.

Abstract: In a hard disk drive memory, a device for controlling a seek operation in which the head is gradually accelerated, then gradually decelerated to move the head quickly from one track to another. The head detects the current track position and triggers a "seek profile" based on the distance of the destination track whereby the device determines the ideal acceleration curve for the seek to be performed. From this, the head begins the seek over a series of consecutive time segments, monitoring its position and determining nominal position at the end of the next successive time segment. In this way the seek profile is updated at each small time segment. Thus, the final head placement is more accurate than in conventional art, in which only an initial distance estimate is used to guide the placement of head. The gradual acceleration/deceleration of the head reduces noise and system wear compared with the full-power acceleration/deceleration utilized in the prior art.

Abstract: A fault tolerant servo index scheme is described. The present invention provides a servo index pattern and detection method which can be utilized to any servo scheme, including, but not limited to, sector servo and dedicated surface servo. The servo pattern of the preferred embodiment of present invention is a twelve bit pattern chosen to limit the side lobes of an autocorrelation plot of the pattern with a template of the pattern. In this manner a greater number of errors can be tolerated while still permitting index identification. Initially, the entire servo pattern on a servo track is detected in sequence at the bit rate. Each twelve bit sequences of bits is compared to a template of the servo pattern and the number of bits whose position and value ("1" or "0") match the template are determined. Whenever a threshold level (less than the total number of bits in the pattern) of "hits" takes place it assumed that the index has been detected.

Abstract: An in-spindle disk drive motor incorporating a novel two-piece aluminum spindle and a method for fabricating the same. The spindle is hollow and contains a removable steel flux sleeve on which plastic permanent magnets are mounted. The spindle is mounted by means of two bearings to a non-rotating stator shaft disposed through the center of the spindle and rigidly attached to a disk drive base. One of the bearings is located in a removeable bearing sleeve at the top of the spindle and the other is located beyond the steel sleeve at the bottom end of the spindle. The aluminum spindle eliminates thermal distortion effects caused in prior art in-spindle motors by thermal expansion differences between aluminum disks and non-aluminum spindles.

Abstract: The present invention provides a method and apparatus for linking together a plurality of disk drives. One drive is designated the "master". The others, designated "slaves", are synchronized to a common signal which may be from the "master" drive or from an external source. The disks are synchronized with respect to rate of revolution (spindle speed) and angular position. A plurality of hard disk drives are coupled in this manner to provide a parallel data output to a host computer. Each disk drive is microprocessor controlled. In normal operation a speed control loop regulates spindle speeds to within one percent of 3600 RPM. Both master and slave drives are equipped with input "MAPIN" and output "MAPOUT" signal terminals. The MAPOUT signal is relative to and dependant on the angular position of the disk. Synchronization is achieved by coupling the output signal from the master drive (MAPOUT) to the input terminal on the slave drives (MAPIN).

Abstract: Method and apparatus for providing constant density recording is described. A single set of reconfigurable electronics is employed to control the write frequency for a plurality of frequency zones on a magnetic storage disk. The reconfigurable electronics include means for selectively switching a frequency response determining element within a common channel. Switching is controlled by a digital signal provided by a disk file control microprocessor, avoiding the necessity of mechanical linkages and/or changes in spindle rotation rate. The plurality of zones need not be of equal radius in width but the recording frequency within each zone is fixed throughout that zone. Zone selection is under the control of a disk file control microprocessor which produces a digital code to appropriately configure the electronics for the particular zone. Zone switching is done only when a seek across a zone boundary occurs so that no access time penalties result.

Abstract: An improved head loader is disclosed for use in assembling hard disk drives to permit the placement of magnetic heads over desired tracks of the magnetic disks. The loader includes a main frame, through which is disposed a shaft. The shaft passes through the frame and is secured to a positioning piece which includes an upwardly extending guide pin, and a downwardly extending positioning pin. A guide piece having a plurality of guides is rigidly attached to the frame. In operation, spreading blades pass through the guides and separate the magnetic heads on an actuator arm to permit the movement of the actuator arm to a position over desired areas of the magnetic disks, without the magnetic heads contacting the disks and causing damage.

Abstract: An in-spindle disk drive motor incorporating a novel two-piece aluminum spindle and a method for fabricating the same. The spindle is hollow and contains a removable steel flux sleeve on which plastic permanent magnets are mounted. The spindle is mounted by means of two bearings to a non-rotating stator shaft disposed through the center of the spindle and rigidly attached to a disk drive base. One of the bearings is located in a removable bearing sleeve at the top of the spindle and the other is located beyond the steel sleeve at the bottom end of the spindle. The aluminum spindle eliminates thermal distortion effects caused in prior art in spindle motors by thermal expansion differences between aluminum disks and non-aluminum spindles.

Abstract: Method and apparatus for astigmatic focusing control which is independent of intensity distribution and is implemented with a combined data/focus error sensor array is described. An objective lens is utilized to focus a laser beam for use in reading and/or writing in an optical disk storage system. An astigmatic focus control system is utilized in which a cylindrical lens is disposed in the path of light reflected from the optical disk. The light from the cylindrical lens forms an astigmatic image on a sensor array. The image shifts between a circle at the focal point and one of two ellipses disposed orthoganally to each other depending on whether the focal point of the objective lens is above or below the plane of the optical disk. In the preferred embodiment, a circular bi-cell sensor is disposed so as to receive and encompass a reflected beam through the cylindrical lens when the objective lens is "in focus". An outer array of four sensors is disposed symetrically about the central bi-cell.

Abstract: An in-spindle disk drive motor incorporating a novel two-piece aluminum spindle and a method for fabricating the same. The spindle is hollow and contains a removable steel flux sleeve on which plastic permanent magnets are mounted. The spindle is mounted by means of two bearings to a non-rotating stator shaft disposed through the center of the spindle and rigidly attached to a disk drive base. One of the bearings is located in a removeable bearing sleeve at the top of the spindle and the other is located beyond the steel sleeve at the bottom end of the spindle. The aluminum spindle eliminates thermal distortion effects caused in prior art in-spindle motors by thermal expansion differences between aluminum disks and non-aluminum spindles.

Abstract: A Winchester disc spindle construction provides a spindle motor coil wound around laminated formed annular plates and having lead wires extending through a central stationary shaft. Surrounding a spindle coil is a cylinder having a pocket for arcuate permanent magnets. The discs are fixed to and rotated by the cylinder. Relatively large bearings support the cylinder concentric with the shaft and give increased strength to the structure, permitting more discs to be supported in equivalent space, as compared with prior structures. The arms carrying the read-write heads are mounted on a stack of spaced-apart arms pivotted at a distance from the discs so that the heads move along a shallow arc to reduce skewing of the heads relative to the recording tracks of the discs.

Abstract: A channel filter employing time domain targeting techniques to eliminate inter symbol interference in the reading of information from magnetic media. A pulse detector outputs a signal characteristic of polarity reversals on the surface of magnetic storage media. This output signal is coupled to a tapped delay line network and a moderate order L-C network. The tapped delay line provides an output signal to the L-C network, which flattens out pre-cursive and post-cursive undershoots. As a result, a moderate order L-C network is sufficient to approximate the desired target response so that maximum information density can be achieved. The tapped delay line provides an output signal that consists of a superposition (sum) of the input signal delayed and weighted. This forms a transversal filter. As with any linear filter, reciprocity applies. Consequently, the output of the tapped delay line is taken from the input with AC coupling directly to ground.

Abstract: In a Winchester hard disk drive assembly having at least one disk rotatably disposed on a cylindrical spindle, the improvement compromising spacer means interposed between the inner diameter of said at least one disk and the outer diameter of said cylindrical spindle, said spacer means defining a clearance between said at least one disk and said spindle and adhesive means for adhesively securing said spacer means between said spindle, and said at least one disk, whereby a substantially uniform and contiguous clearance is maintained about the circumference of the spindle upon thermally induced differential expansion of the disk, and whereby said disk will be substantially prevented from abutting the outer circumferential wall of the spindle.