Patents Assigned to American Telephone and Telegraph Company AT&T Bell Laboratories
  • Patent number: 4904050
    Abstract: An optical fiber sensing system for detecting intrusion of optical fiber or optical fiber cables includes an interferometric arrangement. Two ports (28, 30) of a four port splitter (25) are connected to a source (26) of optical power such as a laser, for example, and to a detector (32). The other two ports (46, 48) are connected to ends of a length (50) of monitoring optical fiber. An input signal to the splitter is split with one subsignal being directed in one direction around the length of optical fiber which serves as a common path between the two ports. The other signal is caused to travel around the common path in an opposite direction. The split signals are recombined in the splitter and their phase difference measured as a detectable pattern by the detector. Should there be intrusion of the optical fiber or a cable containing the monitoring optical fiber, the pattern which is detected will change a significant amount.
    Type: Grant
    Filed: August 31, 1988
    Date of Patent: February 27, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell laboratories
    Inventors: Lawrence R. Dunn, Ian A. White, Willard C. White, III
  • Patent number: 4904036
    Abstract: Optoelectronic chips, such as Group III-V compound lasers and photodiodes, are mounted on a single-crystal silicon base, and are optically interconnected to one another by silica waveguides and couplers integrally formed on the base. Integrated circuit chips to provide electronic function are also mounted on the base. Various schemes for optically coupling and aligning lasers, photodiodes and optical fibers to the waveguides are described. Also described is the use of a single-crystal silicon lid, which serves to provide optical and electrical isolation between chips on the base, as well as a plug-in arrangement in which the edges of the base are adapted to receive parallel guide rods.
    Type: Grant
    Filed: March 3, 1988
    Date of Patent: February 27, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Greg E. Blonder
  • Patent number: 4904043
    Abstract: A dual wavelength optical coupler is disclosed which provides either bidirectional or unidirectional communication at different wavelengths over a single fiber. The coupler utilizes a dichroic filter and a set of three lenses to achieve dual wavelength communication. Additional blocking filters may be incorporated to decrease the degree of optical crosstalk present in the system.
    Type: Grant
    Filed: June 15, 1988
    Date of Patent: February 27, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Rudolph C. Schweizer
  • Patent number: 4905063
    Abstract: A floating gate memory device comprises a channel for conducting carriers from source to drain, a semiconductor heterostructure forming a potential well (floating gate) for confining carriers sufficiently proximate the channel so as to at least partially deplete it, and a graded bandgap injector region between the control gate and the floating gate for controlling the injection of carriers into and out of the potential well. Also described is a three element memory cell, including the memory device and two FETs, which operates from a constant, non-switched supply voltage and two-level control voltages. Arrays of memory devices may also be used to detect light in a variety of applications such as imaging.
    Type: Grant
    Filed: June 21, 1988
    Date of Patent: February 27, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Fabio Beltram, Federico Capasso, Roger J. Malik, Nitin J. Shah
  • Patent number: 4905285
    Abstract: A sensory type pattern such as a speech or other sound pattern is analyzed to obtain the spectral distribution of the neural response thereto. A plurality of logarithmically related neural response intensity threshold signals is formed. The frequency spectrum of the sensory type pattern is divided into a plurality of overlapping spectral portions and the waveform of each prescribed spectral portion is partitioned into successive time segments. For the current time segment of each spectral portion waveform, the time intervals between crossings of the neural response intensity threshold level signals by the spectral portion waveform are detected and signals representative of the counts of inverse time intervals between the crossings of the plurality of levels are generated to form an inverse time interval histogram for the spectral portion.
    Type: Grant
    Filed: February 28, 1989
    Date of Patent: February 27, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Jont B. Allen, Oded Ghitza
  • Patent number: 4902857
    Abstract: A conductive polymer interconnect structure (10) is comprised of an insulative polymer (18), a silicone or an epoxy, having a plurality of particles (20) arranged therein to provide conductive paths which extend in the z direction. At least a portion of those particles (20) proximate a separate one of the major surfaces of the matrix has at least a portion thereof coated with a solder 24 whose composition is tailored to melt below the cure temperature of the matrix (18). In this way, when the matrix (18) is sandwiched between a pair of conductive members (12 and 14) and the matrix is cured, a metallurgical bond, rather than a mechanical bond, will be formed between the members.
    Type: Grant
    Filed: December 27, 1988
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Benjamin H. Cranston, Lloyd Shepherd
  • Patent number: 4902912
    Abstract: A semiconductor integrated resonant-tunneling device having multiple negative-resistance regions, and having essentially equal current peaks in such regions, is useful as a highly compact element, e.g., in apparatus designed for ternary logic operations, frequency multiplication, waveform scrambling, memory operation, parity-bit generation, and coaxial-line driving. The device can be made by layer deposition on a substrate and includes a resonant-tunneling structure between contacts such that side-by-side first and third contacts are on one side, and a second contact is on the opposite side of the resonant-tunneling structure.
    Type: Grant
    Filed: June 13, 1989
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Federico Capasso, Alfred Y. Cho, Susanta Sen, Masakazu Shoji, Deborah Sivco
  • Patent number: 4903092
    Abstract: Real space hot electron transfer devices using hot electron transfer between two conducting channels are described.
    Type: Grant
    Filed: April 17, 1989
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Sergey Luryi, Alexander Kastalsky
  • Patent number: 4903181
    Abstract: A power converter includes an input primary switching system with its output connected to phase shift or impedance inversion circuit. These two circuits cooperate to function as a current source at the output of the impedance inversion circuit. A secondary switching system is connected in parallel with the output of the impedance inversion circuit and is switched synchronously with a controlled phase delay to the input primary switching system to synchronously charge a charge storage capacitor. The phase delay determines the voltage of the charge storage capacitor. An output load circuit is connected in parallel with both the output of the impedance inversion circuit and the input to the secondary switching system so that the capacitor voltage determined by the phase delay is controlling of the output voltage of the output load circuit.
    Type: Grant
    Filed: May 16, 1989
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Harold Seidel
  • Patent number: 4903182
    Abstract: A self oscillating converter with regenerative switching includes circuitry to enhance the gain of circuity to turn off a MOSFET power switch and enhance the regenerative action culminating in turn off in order to eliminate bursting at low loads. The MOSFET power switching device turn off circuitry includes the addition of a supplementary drive transistor operative for counteracting the effects of the parasitic capacitances of the MOSFET power switching device. This permits the converter to operate with the shorter on times and to provide a low ripple output at very low load.
    Type: Grant
    Filed: March 20, 1989
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Raymond W. Pilukaitis, Khanh C. Tran, Thomas G. Wilson, Jr.
  • Patent number: 4902644
    Abstract: The integrity of surface structural features (e.g., distributed feedback gratings) in Group III-V compound semiconductors are preserved during heating (e.g., subsequent LPE regrowth) by a thin coating containing a transition metal (e.g., Os, Ru or Rh). DFP-DCPBH InP/InGaAsP single frequency lasers made in this way are also described.
    Type: Grant
    Filed: October 21, 1988
    Date of Patent: February 20, 1990
    Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories
    Inventor: Daniel P. Wilt
  • Patent number: 4901306
    Abstract: Disclosed is a dense channel packing wavelength division multiplexed optical fiber communication system that is parsimonious in its cable length requirements and that does not require the presence of widely tunable lasers at the remote terminals. The system comprises a central station and N remote stations (N frequently greater than about 50) connected to the central station by optical fiber means that comprise a "backbone" and l (1<l<N) fiber "laterals". Associated with each remote station RS.sub.i is a predetermined wavelength .lambda..sub.i, typically in the spectral region 1.25-1.6 .mu.m. The central station comprises means adapted for generating electromagnetic radiation of a multiplicity of distinct wavelengths including all .lambda..sub.i. The radiation from the central station is coupled into the backbone fiber and transmitted to the laterals and the remote stations. Each remote station RS.sub.i comprises means for selecting the radiation of the associated wavelength .lambda..sub.
    Type: Grant
    Filed: December 5, 1988
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: William B. Gardner
  • Patent number: 4900917
    Abstract: A polarization insensitive optical device is disclosed which is capable of providing direct optical amplification of an input signal of unknown (and possibly varying) polarization. A polarization diversity technique is utilized wherein a polarization beam splitter is used to divide the incoming signal into orthogonal components of known polarization (TE,TM). The orthogonal components are then separately amplified, using a semiconductor laser as the amplifying device. The amplified components are then recombined, either optically or electrically, to form the final output signal.
    Type: Grant
    Filed: July 15, 1988
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Melvyn Dixon, Nils A. Olsson, Robert E. Tench, Liang Tzeng
  • Patent number: 4900879
    Abstract: An insulation system and method utilizes multiple helically wound insulating tape windings wound on a wire. Each individual insulating tape winding is wound so that each wrap overlaps a specified area of the preceding wrap of the winding.
    Type: Grant
    Filed: October 3, 1988
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Robert J. Buck, Helmut H. Landeck, Henry J. Luer
  • Patent number: 4901271
    Abstract: A new associative computation network that is capable of storing multi-bit vectors includes a decision network and a feedback arrangement that, functionally, is separable into serially connected networks. The first network has its inputs connectd to the outputs of the decision network and is arranged to develop sets of excitatory and inhibitory drive signals. Each set corresponds to a stored vecor. For each different output state of the decision network, a different one of the drive signal sets appears at the output of the first network. The output leads of the first network, which may also be employed as the input interface leads, are connected to the second network. The second network develops output signals, applied to inputs of the decision network, which are proportional to the projection of the input signals applied to the second network on the stored vectors.
    Type: Grant
    Filed: January 4, 1989
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Hans P. Graf
  • Patent number: 4900124
    Abstract: A biconic optical fiber connector (20) comprising two plugs (24--24) each having truncated conically shaped end portions (30--30) for terminating optical fibers to be connected and a sleeve (66) in which the plug eng portions are received is provided with an attenuator (70) which results in low reflected power. The attenuator comprises a plate-like element which is disposed between the plug end portions. Advantageously, the plugs are seated in the sleeve and the thickness and mounting of the attenuator cooperate to cause the plug ends to engage the attenuator when the plugs are seated in the sleeve cavities. Also, the attenuator is supported within the sleeve so that it is capable of slight movement in a direction parallel to a longitudinal axis (91) of the sleeve to self-adjust, if necessary, as the plug end portions are inserted and become seated in the sleeve.
    Type: Grant
    Filed: December 12, 1988
    Date of Patent: February 13, 1990
    Assignees: American Telephone & Telegraph Company, AT&T Bell Laboratories, AT&T Technologies, Inc.
    Inventors: Norman R. Lampert, Naif T. Subh
  • Patent number: 4901013
    Abstract: An apparatus for testing of electrical circuits has a buckling beam probe assembly having advantageous features that make it useful for contacting area arrays of test points, and for reliably establishing contact therewith. The probe elements remain essentially parallel even in the buckled state, and the probe tips execute a small "wiping" movement on the contact point. In some preferred embodiments the probe tips are shaped to result in reduced contact area.
    Type: Grant
    Filed: August 19, 1988
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: William E. Benedetto, Joseph M. Moran
  • Patent number: 4901260
    Abstract: A discrete event simulation system that avoids all blocking and advances the simulation time in an efficient manner by treating the simulated system as a set of subsystems and simulating the subsystems concurrently. The simulation proceeds iteratively by restricting the simulation of scheduled events for each subsystem at any one time to a chosen simulated time segment (bounded lag) beginning with the lowest simulation time found among the subsystems. With each simulation iteration, an "at risk", demarcation time is evaluated based only on a subset of the subsystems that can potentially affect the simulation at the considered subsystem. Events scheduled for a time earlier than the "at risk" time are simulated.
    Type: Grant
    Filed: October 28, 1987
    Date of Patent: February 13, 1990
    Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories
    Inventor: Boris D. Lubachevsky
  • Patent number: 4899306
    Abstract: A general purpose computer test interface is used to test various types of computers having differing input/output characteristics. The interface comprises a control unit which is responsive to messages from a controlling host computer to generate a unique set of type control signals for each computer type to be tested. Interfce control logic circuits combine the type control signals with bus control signals from a target computer under test to adapt the interface for communication with each of the different types of targets defined by the type control signals.
    Type: Grant
    Filed: August 26, 1985
    Date of Patent: February 6, 1990
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Steven C. Greer
  • Patent number: 4899358
    Abstract: A call announcement arrangement that obtains the calling party name from a database search and uses a text-to-speech unit to generate speech signals for transmission to the called communication station. The calling party name is spoken at the station instead of being displayed. For a conventional analog station, the name is spoken after the called party has answered in response to ringing at the station but before a connection is completed to the caller. The called party accepts the caller either by remaining off-hook or by transmitting a connection signal using, for example, flash or tone signaling. For other illustrative station equipment such as an ISDN speakerphone or a specially adapted analog speakerphone, the calling party name is spoken before the called party answers in place of or in addition to normal ringing. Caller-identifying speech signal are also transmitted to a station determined to be busy to announce the caller name for a call waiting call.
    Type: Grant
    Filed: August 8, 1988
    Date of Patent: February 6, 1990
    Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories
    Inventor: James R. Blakley