Abstract: In disk drives incorporating the present Peak Detection Channel invention (PDC) an important feature is the ability to locate the data on a disk. Servo timing sectors for each data track are recognized by the embodiments of the invention cooperating with system electronics at start up of the disk drive system. Variation of data pulse heights, widths and shapes over a broad range are accommodated. The invention takes advantage of the fact that typical pulse shapes (e.g. Gaussian or cosine-squared) can be closely approximated near their peak by a parabolic curve.

Abstract: A system and method for write location defect compensation in computer storage media comprises a reflectivity channel containing a detector device and counter device, an error threshold device coupled to the reflectivity channel for determining if the write location defect requires compensation, and memory devices coupled to a processor for storage of the defective write locations. A processor responsively reallocates write data to a different write location and thus maintains an efficient and reliable data storage system.

Abstract: A system and method is disclosed for assembling a pre-formatted top half and a pre-formatted bottom half of a disk platter, and for further assembling pre-formatted disk platters into a multi-platter MO disk drive, with the servo sectors in a predetermined rotational alignment and with the tracks in good radial alignment. Because of the known rotational alignment of the servo sectors, it is possible to have independent verification of the operation of the flying MO head switch. This independent verification prevents data corruption due to an unreliable flying MO head switch.

Abstract: A positioning system for selectively directing a first beam of light towards a destination and a second beam of light towards a first diffractive optic. The first beam of light and the second beam of light traverse a substantially co-linear optical path. The first diffractive optic diffracts the second beam of light into a plurality of optical spots. The second beam of light comprising the plurality of optical spots is directed onto a second diffractive optic. A change in position of the plurality of optical spots relative to the second diffractive optic is sensed in a reflection of the second beam of light by a detection element and representative signals are derived thereof. The signals are coupled to a directing assembly, which directs the first beam of light towards the destination.

Abstract: A system and method to compensate for data defects within a magneto-optical computer memory device comprises a data channel coupled to the memory device for receiving and processing data signals, and a detector channel coupled to the data channel for detecting the data defects and then generating corresponding defect-skipping pulses. The data channel responsively uses the defect-skipping pulses to compensate for the data defects and thus maintain reliability of the data signals.

Abstract: An assembly for accessing data bits in storage locations on a succession of radially separated tracks on a rotating multilayer MSR disc comprising a storage layer and a readout layer in combination with a slider flyable over a surface of the disc with the slider supporting at least one optical element coupled to the assembly, the optical element directing light to a region of the disc including one or more storage locations, with the optical element comprising an optical fiber and a micro-machined mirror supported on the slider and adapted to direct the light to storage locations on the recording layer of the disc, a conductive coil is coupled to and supported on the assembly, a passage of current through the conductor coil is sufficient to establish a magnetic field which is coupled to the disc and in cooperation with the light stores information at one of the storage locations on the storage layer, and a magneto-resistive element is coupled to the assembly, the magneto-resistive element cooperates with the

Abstract: A bi-level optical storage media is disclosed. The media includes a flat substrate patterned with a regular pattern of lands and grooves, each land and groove having approximately equal widths. Information wobble marks of a first and second type are added to the lands and grooves as deviations in the path of each groove to a first and second side respectively. The deviation distance is by a fixed amount perpendicular to the direction of a groove and identical in magnitude for each wobble mark, and having a short duration length along the direction of a groove. Additionally, groove depths are provided in the grooves. Both the groove depth and the wobble mark deflection distances are chosen to give a usable reflectivity signal from the wobble marks when sensed during playback. Additionally, encodings using the first and second wobble mark types are provided that designate the physical location of a length of groove or land as distinguished from other length of grooves or lands.

Abstract: A record carrier having essentially circular tracks concentrically located around a point of rotation. The record carrier is divided into circular zones each having m tracks, where m is an integer. Each track within a zone is subdivided into n sectors, where n is an integer which is constant per zone and which increases as the zone is more remote from the point of rotation. Each sector including a header portion and a data portion. The header portions in the radial direction in each zone are in line. In each zone the condition of m*n=j*k is satisfied, where is j an integer greater than or equal to 2 and is constant for each zone, and k is an integer.

Abstract: An optical data storage system records pulse width modulated data as a series of contiguous and overlapping circular marks. A minimum number of circular marks are used to record the desired run length. Circular marks which overlap by greater or equal to one half the diameter of the circular mark are recorded using two different laser power levels. The result is that thermal buildup in the medium is kept to a minimum and the edge transitions are accurately positioned.

Abstract: An optical disk has groups of features (such as depressed areas) arranged in a preselected position sensing servo pattern, and a flat, non-grooved surface between a plurality of circumferentially spaced sectors. A single photodetector senses the change in amplitude of reflected light as a spot from a laser passes over one of the features and generates position sensing signals corresponding to the pattern. At least three phases of the position sensing signal are generated for each sector. Each phase is determined by edges on the disk offset circumferentially with respect to each other and separated radially from each other by a preselected critical distance that is independent of the pitch of the recording tracks on the disk to provide a track error signal that is substantially linear within a desired range to either side of a zero-crossing point.

Abstract: Storage capacity of a magnetic recording medium is increased by providing a nonconductive layer over a magnetic layer on which magnetic data is writable in a series of recording tracks, and applying a pattern of electrostatic charges to the nonconductive layer above at least one of the recording tracks to write track-position-denoting servo information in overlying relation to magnetic data. The pattern may be applied by electrostatic charges selectively of negative or positive polarity that are imprinted while the medium is in a mold or advanced over an electro-photographic charge transfer drum, for thereby preprinting the pattern as a step in fabrication of the medium.

Abstract: A track-seeking system for an optical disk using a velocity control loop with partially-digitized velocity measurement. A quadrature signal is generated based on summing the halves of a position error signal to give directionality to track-crossing counts. A so-called piggy-back construction, wherein a fine positioner is carried by a coarse positioner, is employed. Feed-forward controls are provided from the fine to the coarse positioner. At track-capture time, the dynamic range of the fine positioner is momentarily increased.

Abstract: A discrete track thin film metal alloy or metal oxide magnetic recording disk has a plurality of angularly spaced sectors, each sector being formed of a plurality of discrete blocks of magnetic material which are magnetically polarized in the disk's circumferential direction. These discrete servo blocks and the discrete magnetic tracks are both formed at the same time during the fabrication of the thin film disk such that each servo block is precisely and permanently radially aligned with an associated discrete data track. Following the fabrication of the disk, each of the servo blocks is exposed to the magnetic field generated by passing a direct current (DC) through a recording head. In this manner each of the servo blocks becomes magnetized in the circumferential direction and thereby presents two discrete magnetic transitions to a servo read head or a read/write head.

Abstract: A major/minor loop bubble domain memory system maintains the non-volatility of data when subjected to a power on-off-on sequence. A bubble domain shift register is associated with the major/minor loop array and indicates when a block of data in the major loop is in position to be transferred into the minor loops. The length of the shift register is related to the propagation delay of the path over which a bubble is propagated along the major loop from a minor loop read transfer switch to the write transfer switch for the same minor loop.

Abstract: A compressed refresh buffer utilizing a random access memory is disclosed which performs a mapping between the refresh buffer and a video display screen, such that only non-zero screen areas are represented in the refresh buffer. The dot image on the video screen is divided into rectangular subarrays. If the subarray has image points plotted in it, it is designated active and the bits of each active subarray are stored in the refresh buffer. If no image points are plotted in a subarray, it is designated inactive. A row bit map is provided which includes one bit for each subarray in the row with a "one" bit representing an active subarray and a "zero" bit representing an inactive subarray. Control means including a row tag pointer memory is provided for storing a linked list of pointers associated with each active subarray in a row, each pointer pointing to the location in the random access memory of an active subarray.