Abstract: An optical drive system includes a computer that monitors the current in an improved bias coil assembly in conjunction with a magnetomotive field generator to determine when a predetermined current threshold is exceeded. The bias coil assembly includes a wire coil wrapped around a center bar contained by a bias coil housing. The bias coil assembly is positionable above an information storage medium so that the entire medium may be within the magnetic field thereby allowing writing of information to all portions of the medium. When the threshold is exceeded, a sufficiently strong magnetic field is generated to permit writing of information on the storage medium utilizing a laser. A laser pulse generator is then enabled. The device thereby achieves a substantially shortened write cycle while employing the improved bias coil assembly.

Abstract: An apparatus and method is disclosed for focus control of a beam of radiant energy, wherein a detector of the beam has first and second outputs responsive to a position of the beam. A circuit is coupled to the outputs of the detector for producing an error signal representing a displacement of the focus from a predetermined position, wherein the error signal has a periodic characteristic relative to the displacement. A servo responsive to the error signal restores the displaced beam to the predetermined position. A local feedback loop is coupled to the outputs of the detector, and includes first and second periodic function generators, each responsive to the error signal. The second periodic function generator has an output that differs from an output of the first periodic function generator by a phase angle, preferably 90 degrees. A first multiplier multiplies the first output of the detector by the output of the first periodic function generator.

Abstract: This invention discloses a method for accessing Dynamic Random Access Memory (DRAM) to store and retrieve data words associated with a two dimensional image. The DRAM includes two separate banks, a first bank and a second bank. Each bank is capable of operating in page mode to read and write the data words. The two dimensional image is organized in a two dimensional grid pattern of cells, each cell containing an M by N matrix of pixels. The words associated with each cell occupy one page or less of a bank. Each cell is assigned a particular one of the two banks so that all data words associated with that particular cell are read from and written to one particular page of that particular bank. The assignment of banks to cells is done such that each cell is associated with a different bank than any bordering cell which is also either in the same row or in the same column.

Abstract: An optical drive system includes a computer that monitors the current in the bias coil of a magnetomotive field generator to determine when a predetermined current threshold is exceeded. When the threshold is exceeded, a sufficiently strong magnetic field is generated to permit writing of information on a storage medium utilizing a laser. A laser pulse generator is then enabled. The system is provided with an optics module for processing light produced by the laser light source. A laser driver for energizing the laser light source is positioned in close proximity to the optics module and the laser light source to reduce noise in signals associated with the optics module. The system thereby achieves a substantially shortened write cycle while reducing relevant signal noise.

Abstract: An analog to digital circuit assembly for use in an optical information includes a circuit for multiplexing a reference voltage input of an analog to digital converter to produce alternating normalized and referenced digital outputs of a plurality of analog signal inputs at a rate controlled by a sampling clock which includes a switch including first and second inputs, an output, and a control input for alternately connecting the first and the second inputs to the output, the output being applied to the reference voltage input.

Abstract: A plurality of processing stages interposed between an input and an output of a system including a pipeline machine interconnect for conveyance of tokens along the pipeline. Control and or data tokens in the form of universal adaptation units interface with all of the stages in the pipeline and alternatively interact with selected stages in the pipeline so that the processing stages in the pipeline are afforded enhanced flexibility in configuration and processing. In one embodiment of the system, the stages accept a data stream having portions encoded according to respectively different video formats. At least one of the stages includes circuitry for generating signals to indicate an end-of-picture data decoding. The stage includes state machine logic that is responsive to the generated signals for effecting an end of picture data decoding by clearing the pipeline.

Abstract: An optical drive system includes an optical assembly, a light source, a lens positioned to direct light between the optical assembly and an information storage medium or disc, and an actuator suspending the lens. A photodetector is disposed in a path of returning light to measure light received from the medium. A monitoring circuit is provided to monitor a Quad Sum signal associated with return light. A first servomotor is employed to move the lens in a tracking direction and to move the lens during focus capture while system circuitry searches for a maximum Quad Sum signal. A second servomotor is employed to move the lens in a focusing direction. A first electronic circuit is provided to control the first and second servomotors.

Abstract: A magneto-optical drive system having a computer that monitors the current in the bias coil of a magnetomotive field generator to determine when a predetermined current threshold is exceeded. When the threshold is exceeded, a sufficiently strong magnetic field is generated to permit writing of information on a storage medium utilizing a laser. A laser pulse generator is then enabled. The device thereby achieves a substantially shortened write cycle.

Abstract: An interferometer includes a beamsplitter for splitting a source beam into a test beam and a reference beam, an imaging device for detecting an interference pattern, a mirror disposed in a path of the test beam for reflection of the test beam toward the imaging device, a micromirror disposed in a path of the reference beam for reflection of a portion of the reference beam toward the imaging device, and a focusing mechanism disposed for focusing the reference beam on the micromirror. The micromirror has a lateral dimension not exceeding the approximate lateral dimension of a central lobe of the reference beam focused thereon by the focusing mechanism. A spatial filter for reducing effects of aberration in a beam includes a reflector disposed upon a transparent base wherein the reflector has a lateral dimension not exceeding the approximate lateral dimension of a central lobe of the spatial intensity distribution of the beam focused upon the reflector.

Abstract: The mechanism for loading and unloading a disk cartridge uses two sliders (one on each side of a base plate), which move in opposite directions under the influence of a tiller. Each slider has a slot to receive one of the two lifting pins provided on the cartridge receiver. The movement of the sliders drives the lifting pins along the slots, thereby raising or lowering the cartridge receiver depending upon the direction of rotation of the tiller. The sliding motion of the lifting pins engaged in the S-shaped slots thus unloads a disk from or, alternatively, loads the disk onto the drive spindle. As the lifting pins travel along their respective slots, the lifting and lowering of the disk is accomplished in such a manner that the disk hub is peeled from the spindle magnet rather than being lifted vertically off the spindle. This reduces the peak force required to break the magnetic clamp force between the spindle magnet and the disk hub.

Abstract: The present invention preferably includes a shading band which is suitably electro-optically created in a grid pattern formed through a photolithographic process, so consequently, the electro optic shading band is easily eliminated or re-configured dynamically to substantially eliminate its shading effect for lower density optical disks which do not experience substantial adjacent track crosstalk (ATC). Eliminating or reconfiguring the shading effect also helps in accommodating different media types and generations and those of different manufacturers. Moreover, the electro-optic shading band suitably adjusts the amplitude, phase, frequency, polarization and/or the like of the light beam to compensate for possible material property variations, defects, misalignments or other imperfections in the reading process. The present electro-optic shading band substantially restricts or alters any portion of a light beam containing signal information read from an optical disk.

Abstract: An improved system for recording and playing back digital information in a special pulse-length modulation format on a disc-shaped record. The digital information is stored in a succession of alternating marks and spaces, both having lengths that are discretely variable in accordance with a succession of multi-bit binary code blocks.

Abstract: A video record medium, such as a record disc, for recording a composite video and audio signal suitable for stop-motion playback, with accompanying audio. Discrete segments of analog audio signal are digitized and compressed in time and recorded on alternate tracks on the disc, and corresponding frames of a video signal are recorded on the tracks located therebetween. During playback of the disc, a selected audio track is scanned initially and the digital audio data recovered therefrom is entered into a memory device, after which the track for recording the corresponding video frame is scanned in a repeated fashion, to produce a stop-motion display of the frame, while the stored audio data is extracted from the memory device and converted back to an analog format, for simultaneous playback at its original speed.

Abstract: The present invention includes a method and apparatus for reducing the width of a mark written in optical media. When forming a long mark, the prior art recording methods typically cause blooming at the edges of the mark, resulting in a wide mark pattern which may be sensed by the read focused spot reading an adjacent track causing increased adjacent track crosstalk (ATC). However, by removing every other pulse from the write pulse waveform, the cooling sequence of the writing process is sufficiently increased to allow for additional cooling between pulses. When forming marks with less pulses, the effects of blooming are substantially reduced. Thus, because of the reduction in the effect of blooming, the problems associated with ATC, whereby adjacent track information is recorded, is substantially reduced.

Abstract: A method and system for automatically collecting and for analyzing information about time and work performed on a computer includes a hardware abstraction layer for monitoring activity on various user input devices. The system also includes the following elements: a data collector for monitoring certain portions of a user's computer activity and for logging into a log file those certain portions of a user's computer activity; a data analyzer for determining by following user-defined rules showing which portions of those certain portions of a user's computer activity constitutes continuous work activities, and how this work should be categorized by project and task with project; and an external interface for building the rules defining work. The data collector includes a resident module, such as a TSR (terminate-and-stay-resident) module, which extends the file system of the computer so that detailed records are kept of file activities.

Abstract: A releasable disc adaptor for conforming the central hub of an information storage disc to a standardized magneto-optical disc drive spindle. The disc adaptor includes a hub receiving member having a center connected to a medium receiving member having a center. The centers of the medium receiving and hub receiving members are collinear. The adaptor includes a hub fastener fixedly mounted to the hub receiving member. The hub fastener is utilized to removably secure the hub receiving member to a disc drive spindle. The adaptor also includes a medium fastener connected to the medium receiving member. The medium fastener is used to removably secure the central hub of an information storage disc to the hub receiving member and prevent slippage therebetween so that the disc hub is thereby conformed to properly seat on the disc drive spindle while thereafter allowing the disc to be fully disengaged from the adaptor members for proper seating on an alternate disc drive spindle.

Abstract: A video record medium, such as a record disc, for recording a composite video and audio signal suitable for stop-motion playback, with accompanying audio. Discrete segments of analog audio signal are digitized and compressed in time and recorded on alternate tracks on the disc, and corresponding frames of a video signal are recorded on the tracks located therebetween. During playback of the disc, a selected audio track is scanned initially and the digital audio data recovered therefrom is entered into a memory device, after which the track for recording the corresponding video frame is scanned in a repeated fashion, to produce a stop-motion display of the frame, while the stored audio data is extracted from the memory device and converted back to an analog format, for simultaneous playback at its original speed.

Abstract: An apparatus for optically reading or recording information on an optical disc which is rotatable about an axis of rotation. The apparatus includes a frame, a carriage, a carriage drive, an objective lens, an objective lens holder, a focus drive, a fine tracking drive and an objective lens position sensor. The objective lens is mounted on the objective lens holder so that the optical axis of the objective lens substantially intersects the center of mass of the carriage. The fine motor, used for tracking and focus, has a center of mass that substantially lies on the optical axis and proximate the center of mass of the carriage.

Abstract: A method of asynchronously accessing a random access memory having a plurality of rows and columns, where each row has a wordline connected to read and write row decoders and each column is connected to bitlines. A row address is assigned to a first and second row, i.e. a pair of rows. A read address is provided to the read row decoder and a write address is provided to the write row decoder. The read and write addresses are decoded by the read and write row decoders, respectively, and one of the first or second rows is selected for reading. Asynchronous with selecting one of the first or second rows for reading, one of the first or second rows is selected for writing. Data is then read from the row selected for reading and asynchronously data is written into the row selected for writing. Signals are provided which coordinate the reading and writing of data, where in the event reading or writing is being performed, another of the reading or writing is deferred until completion of the first reading or writing.

Abstract: A video record medium, such as a record disc, for recording a composite video and audio signal suitable for stop-motion playback, with accompanying audio. Discrete segments of analog audio signal are digitized and compressed in time and recorded on alternate tracks on the disc, and corresponding frames of a video signal are recorded on the tracks located therebetween. During playback of the disc, a selected audio track is scanned initially and the digital audio data recovered therefrom is entered into a memory device, after which the track for recording the corresponding video frame is scanned in a repeated fashion, to produce a stop-motion display of the frame, while the stored audio data is extracted from the memory device and converted back to an analog format, for simultaneous playback at its original speed.