Patents Assigned to American Telephone and Telegraph Co., AT&T Bell Laboratories
  • Patent number: 4904087
    Abstract: Photomasks (11, 12) are aligned on opposite sides of a wafer by directing light beams through zone plates (13 A-C) in one photomask and through aligned transparent slits (14 A-C) on the other photomask. Simulantaneous detection of the beams by photodetectors (18 A-C) indicates alignment. A method for obtaining precise centering by scanning the slits with the beams, sampling light transmitted through the slits, and fitting the samples to a parabola by the use of a computer (27) is also described.
    Type: Grant
    Filed: November 21, 1988
    Date of Patent: February 27, 1990
    Assignees: American Telephone & Telegraph Co., AT&T Bell Laboratories, American Telephone & Telegraph Company
    Inventors: George T. Harvey, Laurence S. Watkins
  • Patent number: 4893893
    Abstract: A buffer optical fiber (20) includes an optical fiber (21) comprising a core and a cladding. The optical fiber is enclosed by a plastic buffer layer (50). Interposed between the optical fiber and the buffer layer are a plurality of fibrous strands (25--25) which are strength members for the buffered optical fiber. In a preferred embodiment, the strength members are layless and as such are generally linear and parallel to a longitudinal axis of the buffered optical fiber. The buffer layer has a predetermined compressive engagement with the strength members which allows the stripability of the buffer layer from the fiber to be controlled.
    Type: Grant
    Filed: February 8, 1988
    Date of Patent: January 16, 1990
    Assignees: American Telephone and Telegraph Co., AT&T Bell Laboratories, AT&T Technologies, Inc.
    Inventors: James D. Claxton, Gerald A. Scheidt, Stanley C. Shores
  • Patent number: 4891580
    Abstract: The longitudinal electro-optic effect is used with an external probe to make voltage measurements on electrical conductors.
    Type: Grant
    Filed: April 29, 1988
    Date of Patent: January 2, 1990
    Assignee: American Telephone and Telegraph Co., AT&T Bell Laboratories
    Inventor: Janis A. Valdmanis
  • Patent number: 4789825
    Abstract: An integrated circuit includes first and second field effect transistors having differing channel lengths, and a means for comparing the channel currents flowing therethrough. An excessive difference of currents indicates "short channel" effects, which can degrade performance. A signal flag indicating this condition may be provided to a test pad on the chip, or used to disable operation of the integrated circuit, or otherwise used to provide an indication.
    Type: Grant
    Filed: February 25, 1988
    Date of Patent: December 6, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Laboratories
    Inventors: John A. Carelli, Richard A. Pedersen, Robert L. Pritchett
  • Patent number: 4771325
    Abstract: An integrated photodetector-amplifier is described which is planar and exhibits excellent circuit characteristics including low input capacitance, high speed, and high sensitivity. Also, certain self-alignment features and a planar technology made fabrication of the circuits simpler and easier than most such circuits.
    Type: Grant
    Filed: February 11, 1985
    Date of Patent: September 13, 1988
    Assignee: American Telephone & Telegraph Co., AT&T Bell Laboratories
    Inventors: Julian Cheng, Bernard C. DeLoach, Jr., Stephen R. Forrest
  • Patent number: 4767429
    Abstract: The disclosed simple, economical and rapid sol-gel process for forming a silica-based glass body, termed the "vapogel" process, comprises introduction of a silicon halide-containing gas (e.g., SiCl.sub.4 +O.sub.2) into an aqueous medium. The thus formed sol can gel within minutes, resulting in a monolithic gel from which particles having a narrow size distribution can easily be formed. The thus formed particles can be used to produce a glass body such as an optical fiber. Various techniques for forming the glass body from the gel are disclosed. Among the many advantages of the vapogel method are its ability to produce very homogeneous mixed oxide glasses of composition not obtainable by prior art sol-gel processes, and the advantageous mechanical properties of the gel produced by the method. The latter makes possible, inter alia, formation of particles having a relatively narrow size distribution.
    Type: Grant
    Filed: December 11, 1986
    Date of Patent: August 30, 1988
    Assignee: American Telephone & Telegraph Co., AT&T Bell Laboratories
    Inventors: James W. Fleming, Sandra A. Pardenek
  • Patent number: 4763183
    Abstract: A new SOI device which permits both the kink effect to be avoided and threshold voltage to be regulated, as well as a new method for fabricating SOI ICs, is disclosed. The new device included an electrically conductive pathway extending from the active volume and terminating in a non-active region of the substrate of the device. A back-gate bias is communicated to, and kink-inducing charges are conducted away from, the active volume through the conductive pathway. The new fabrication methd permits SOI ICs to be fabricated using available circuit designs and pattern delineating apparatus, e.g., IC mask sets. This method involves the formation of a precursor substrate surface which includes islands of insulating material, each of which is encircled by a crystallization seeding area of substantially single crystal semiconductor material. The boundaries of the islands are defined with a first pattern delineating device, e.g.
    Type: Grant
    Filed: October 24, 1986
    Date of Patent: August 9, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Laboratories
    Inventors: Kwok K. Ng, Simon M. Sze
  • Patent number: 4743085
    Abstract: An optical fiber cable (20) includes a core (22) comprising at least one optical fiber (23) which is enclosed in a tubular member (28) and which includes a non-metallic sheath system (30). The sheath system includes two contiguous layers (40, 50) of non-metallic strength members which extend longitudinally along the cable and which are wrapped helically in opposite directions about the tubular member. The layers of strength members are enclosed in a plastic jacket (36). At least some of the strength members which are capable of withstanding expected compressive as well as tensile loading are coupled sufficiently to the jacket to provide a composite arrangement which is effective to inhibit contraction. Those strength members cooperate with the remaining strength members to provide the cable with a predetermined tensile stiffness and to cause the cable to be relatively flexible.
    Type: Grant
    Filed: May 28, 1986
    Date of Patent: May 10, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Laboratories
    Inventors: Artis C. Jenkins, Parbhubhai D. Patel
  • Patent number: 4740433
    Abstract: Lithium nonaqueous rechargeable batteries are described in which the separators in the cells have been exposed to a radiation grafting process to increase wettability. This increases charging and discharging rates without use of a wetting agent or addition of undesirable substances to the electrolyte system. In a preferred embodiment, a particularly advantageous electrolyte solvent system (propylene carbonate and ethylene carbonate) is used with excellent charge and discharge rates and excellent cycle life.
    Type: Grant
    Filed: September 29, 1986
    Date of Patent: April 26, 1988
    Assignee: American Telephone and Telegraph Co., AT&T Bell Laboratories
    Inventor: Wen-Tong P. Lu
  • Patent number: 4677323
    Abstract: An MOS current steering circuit (10) includes a current mirror arrangement with an input branch (12) and an output branch (16). In the input branch, the conduction channels of a current-limiting transistor (M1) and a current mirror input transistor (M3) are connected in series with each other between a first power supply voltage node V+ and one side of a current source (14). The other side of the current source and the gate of the current-limiting transistor are connected to another supply voltage node (V-). In the output branch, a current mirror output transistor (M4) has one side of its conduction channel connected as a current output node (D). The gates of the input and output transistors are connected together and to the common node (A) of the input transistor and the current source. A control transistor (M2) has its conduction channel connected between the other side of the output transistor and the first voltage supply node.
    Type: Grant
    Filed: July 22, 1985
    Date of Patent: June 30, 1987
    Assignee: American Telephone & Telegraph Co., AT&T Bell Laboratories
    Inventor: Douglas G. Marsh