Abstract: A magnetoresistive (MR) head assembly includes an elongated MR element, arranged transverse to an adjacent magnetic recording medium, defining two substantially equal MR portions. Signal processing circuitry, coupled to respective outputs of the two MR portions, is arranged for producing and manipulating sum and difference signals of respective playback signals developed across the two MR portions, to produce a resultant information-bearing signal played back from both MR portions that is unperturbed by any error signal induced by a localized asperity in the adjacent magnetic recording medium.

Abstract: An optical tape recording medium is provided with a transparent flexible membrane which covers the recording surface of the tape and is bonded to its edges so as to trap a small bubble of fluid, e.g., gas or liquid. During recording, the trapped bubble displaces dust particles resting on the film's upper surface to a location out of the zone of focus of a read/write beam. As the tape is longitudinally transported, the trapped bubble is held stationary at the read/write station of the recording apparatus. In a tape cassette, the optically writable tape is wound around two reels with sufficient tension to trap the bubble in that portion of the tape stretched between the supply and take-up reels. In one embodiment of the invention, the bubble contains a transparent magnetic liquid which can be properly positioned by a magnet when the cassette is first inserted into an optical recording or playback apparatus.

Abstract: An operational amplifier input stage includes two transistors coupled as a differential amplifier to receive input signals. At least one transistor is stacked in a load circuit of each input transistor for the purpose of lowering the voltage across each transistor. In order to eliminate the effects of error currents resulting from conventional resistor self biasing of the stacked transistors, two nodes, to which the input transistors are coupled, are identified. According to a first embodiment, feedback circuits are coupled to each node and each feedback circuit maintains the coupled node at a voltage level established by the feedback apparatus of the operational amplifier. According to a second embodiment, a single feedback circuit controls the voltage at a first node and the same feedback circuit maintains the voltage level of a second node at a constant level.

Abstract: A hybrid, thin-film, optical waveguide structure has a substrate with a grating coupler formed thereon. A thin-film waveguide film is formed on the substrate and has a tapered portion overlaying the grating.

Abstract: In the transfer of checks between facilities receiving checks and facilities for processing checks, checks are sorted into batches according to selected classifications at the check receiving facilities. The checks are accumulated in bundles and transferred to the check processing facility according to a predetermined schedule. In the present invention, a batch slip is provided with each transferred bundle. The batch slip identifies the type of checks in the batch, identification of the receiving facility and a sequence number. The information is provided both in a bar code format and in a MICR format. The batch slip is kept with the associated batch of checks during the processing in the processing facility. Bar code readers are provided at various processing stations.

Abstract: Apparatus and a method are disclosed for providing a microwave attenuator system using distributed (transmission line) reactive elements to achieve a reduction in the transmitted electrical signal amplitude. The attenuator system includes a fixed attenuator unit and an adjustable attenuator unit. The fixed attenuator unit contains a "T" resistive attenuator component. Transmission line resonator components are added to the attenuator component to provide frequency selectively. The transmission line resonator components are coupled to the resistive attenuator component in such a way as not to compromise the impedance match of the transmission line. The step adjustable loss component includes shunt transmission lines coupled to the center conductor of the transmission line by means of a spring contacting mechanism. The shunt transmission lines include preselected resistive elements.

Abstract: An apparatus for recording onto and reading from an optical disk includes an array of laser diodes that emit a plurality of laser beams with each beam at the diode source spaced a distance greater than about 50 .mu.m from adjacent beams. The apparatus includes a plurality of channel waveguides coupled to the plurality of laser diodes with each channel waveguide associated with a respective laser diode for directing light emitted by the diodes toward the optical disk for optical recording and for receiving reflected light from the optical disk for reading the optical disk. Each beam emanating from the channels is spaced from adjacent beams a preselected distance less than about 50 .mu.m.

Abstract: An MR head includes two substantially identical MR elements, separated by a thin film non-magnetic electrically conductive spacer. A current applied to the MR head splits into two respective substantially equal currents that flow in the same direction through the substantially identical MR elements, to provide mutual bias and to serve as sense currents for detecting change in element resistance. The MR elements are biased to operate in a magnetically unsaturated mode. This results in a "bootstrapping" of short wavelength signals that effectively amplifies the reproduced signal over a broad region of the signal spectrum when the linear spacing between the MR elements is in the range of from one half to one times the half-wavelength of signals recorded on a magnetic recording medium.

Abstract: A resonant AC circuit includes a network of switching elements (e.g., power field-effect transistor) by which the direction of current flow through a coil can be selectively switched at each time in the current cycle, when the current amplitude is substantially zero. Such circuit is particularly advantageous and useful in magneto-optic recording systems for switching the polarity of a magnetic field enabling the direct-overwriting of information on a previously recorded magneto-optic recording element at a high data transfer rate.

Abstract: A magneto-optic playback apparatus which plays back information from a recording layer (RL) which exhibits different light absorption of left and right circular polarized beams emitted from a laser (L). The laser (L) operates in two different polarization modes, DE and TM. Polarization converter (PC) converts linear polarized radiation from the laser in one plane to one circular polarization orientation (left or right) in one direction of transmission, and then converts the opposite circular polarized radiation orientation back to linear polarization in the other direction of transmission. The laser switches between modes according to the magnetic orientation of the medium which is determined by the reflected light. Loss control element (LC) selectively increases the TE losses in the extended laser cavity. The self-coupling laser's operation in either the TE or TM mode depends on the differential absorption by the media of right (RCP) or left (LCP) handed circularly polarized beams.

Abstract: An optical device is disclosed for diffracting an incident beam of radiation to form a plurality of discrete diffracted beams of different orders. The optical device comprises two diffraction gratings which are supported on a substrate and are separated from each other by a thin film. In order to obtain the advantages of a doubly-periodic structure, the thickness of the thin film between the two gratings is very accurately controlled to be on the order of the wavelength of the incident beam of radiation.

Abstract: Apparatus for reading out information magneto-optically recorded in a magnetic layer comprises a single, polarization-preserving optical fiber for transmitting plane-polarized readout radiation from a source to the recording layer, as well as for transmitting such radiation, upon being reflected by the recording layer, toward a pair of photodetectors for the differential detection of the Kerr rotation angles (.+-..THETA..sub.k) produced by the up/down orientation of the vertically oriented magnetic domain in the recording layer. Optical feedback of the reflected readout radiation to the readout source is minimized by the provision of a pair of polarization beam-splitters having a 45 degree magneto-optic polarization-rotator (e.g. a Faraday rotator) positioned therebetween. The polarization beam-splitters and retardation plate are positioned in the optical path between the readout source and the optical fiber.

Abstract: In a data processing system having a plurality of tightly coupled data processing units connected by an asynchronous system bus, apparatus and an associated method are described for maintaining the coherency of data groups stored in instruction cache units and execution cache units. The apparatus includes a monitor unit as part of the bus interface unit, and a bus interface unit coupling each associated data processing unit to the system bus. The monitor unit receives signals, applied to the system bus, identifying data groups transferred between the memory unit and the data processing units, including those data groups originating from the bus interface unit of which the monitor unit is a component. The bus interface unit includes directories duplicating the contents of the instruction cache unit directory and the execution cache unit directory.

Abstract: A method and apparatus for heat and mass transfer is described that is applicable to: regeneration of liquid desiccant solutions, heat pumping of humid gases, cooling and dehumidifying of gases for air conditioning, and water absorption from air. Generally, using a moving gas, at a constant pressure, a continual change in a vapor-liquid equilibrium is created between proximate but continually changing gas and liquid desiccant temperatures within an energy transferring chamber. Chamber wetting, implemented segmentedly, allows mass transfer into and from the moving gas. A forced temperature differential between heat sinks and sources causes heat transferred by means of thermally conductive barriers. Concurrent with temperature variances, the segmented wetting further allows liquid desiccant concentrations caused by evaporation or condensation, to vary between wetted sectors.

Abstract: A method of using vaporized solvent to fuse a thermal image includes containment of the solvent vapor.

Abstract: An operational amplifier input stage includes two transistors coupled as a differential amplifier to receive input signals. At least one transistor is stacked in a load circuit of each input transistor for the purpose of lowering the voltage across each transistor. In order to eliminate the effects of error currents resulting from conventional resistor self biasing of the stacked transistors, two nodes, to which the input transistors are coupled, are identified. A feedback circuit is coupled to each node and each feedback circuit maintains the coupled node at a voltage level established by the feedback apparatus of the operational amplifier. The disclosed circuit eliminates circuit drift and offset voltages resulting from changes in common mode and/or power supply voltages by eliminating the effects of resistive loading on the input stage components.

Abstract: A protective cartridge for a data storage disk (e.g. optical, magneto-optical and magnetic disks) has two disk-access apertures which enable the disk to be used with two different types of disk drives, i.e. those which extract the disk from the cartridge prior to a record/playback operation, and those which record/playback information on the disk while rotating the disk within the cartridge. One aperture is provided in a side wall of the cartridge and is sized to allow a disk to be inserted into or extracted from the cartridge interior, and the other aperture is provided in the top and/or bottom wall(s) of the cartridge to expose a sufficient portion of the disk to enable it to be rotated within the cartridge and to have data recorded or played back over its entire data-recording surface(s). Two different cartridge doors prevent dirt and other contaminants from entering the cartridge interior through the disk-access apertures.

Abstract: An electrostatic discharge collection device for mounting in an air delivery duct system leading into a carpeted area for neutralizing an electrostatic charge in the air prior to its entering into the carpeted area so as to prevent or reduce a problem known as pooling in the carpet.

Abstract: Interleaved cyclic error correction encoded binary data, of the type employed in the compact audio disk standard for example, in which the parity characters are located in the middle of a codeword, are encoded by a serial encoder to greatly increase the speed at which such data may be recorded. In the invention, the message characters are treated as two polynomials, a left-hand sub-codeword or message block representing the message characters to the left of the parity characters and a right-hand sub-codeword or message block representing the message characters to the right of the parity characters. The encoder of the invention has two parallel inputs which simultaneously receive the message characters of the right-hand and left-hand sub-codewords, respectively, each input receiving one character at a time in serial fashion.

Abstract: Apparatus and a method are disclosed for transporting a motor scooter or similar type vehicle on the back of a motor vehicle such as an automobile, van, pick-up truck or the like. The apparatus of the present invention attaches to the rear of the motor vehicle and includes a platform which, when not in use, is oriented in a vertical direction. When the apparatus is used to transport a motor scooter, the platform is lowered to the ground and the motor scooter can be loaded onto the platform. A restraining bar is used to secure the scooter to the platform. The platform, still with the horizontal orientation, is raised to prevent contact with the ground when the motor vehicle is in motion. To remove the motor scooter, the platform is lowered to the ground, the lowering of the platform causing the restraining bar to be released. The motor scooter can then be removed from the platform and the platform secured in a vertical orientation until required further.