Patents by Inventor David M. Mitchell

David M. Mitchell has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5448669
    Abstract: A hybrid cable (20) includes a first transmission portion such as a metallic conductor portion (22) and a second transmission portion such as an optical fiber portion (24). The metallic conductor portion includes a core which includes twisted pairs of metallic conductors enclosed in a plastic core wrap, a shielding system and a plastic jacket (48). A longitudinally extending duct (52) is disposed in engagement with an outer surface of the plastic jacket of the metallic conductor portion. An outer plastic jacket (60) is disposed about the duct and the metallic conductor portion. An optical fiber cable (50) or optical fibers (51, 51) may be caused to become disposed initially in the duct or when the use of fibers becomes economically justified.
    Type: Grant
    Filed: December 21, 1993
    Date of Patent: September 5, 1995
    Assignee: AT&T Corp.
    Inventors: Lawrence R. Dunn, Nathan E. Hardwick, III, David M. Mitchell, Robert P. Mohalley, Peter A. Woog
  • Patent number: 5373100
    Abstract: A communication cable includes a core comprising at least one transmission medium and a sheath system which is disposed about the core. Means are disposed within the cable for preventing the longitudinal migration of water through the cable core, said means including both a hydrophilic material and a hydrophobic material in cooperative communication with each other. Specifically, a hydrophilic, water-absorptive material is supported by a yarn which is helically wrapped about various sections of the communication core. In a copper cable, the water-absorptive yarn may be wrapped about individual twisted pair conductors or a unit consisting of a plurality of twisted pair conductors or the cable core itself. In addition to the helically-wrapped, water-absorptive yarn, the cable of the present invention includes a hydrophobic, water-blocking material interdisposed to fill all voids and interstices within the communication core.
    Type: Grant
    Filed: November 3, 1993
    Date of Patent: December 13, 1994
    Assignee: AT&T Corp.
    Inventors: Candido J. Arroyo, David S. Hancock, John F. Malluck, David M. Mitchell, Jim J. Sheu
  • Patent number: 5306867
    Abstract: A cable (20) includes a plurality of conductors (24) included in a core (22) enclosed in a sheath system. Voids between the conductors are filled by a mixture of a filling composition characterized by a styrene-rubber block copolymer having a styrene/rubber ratio of from 0.2 to 0.5, an ASTM Type 104A oil and polyethylene and a superabsorbent polymer material. The mixture has a viscosity in the range of about 400 cps at 88.degree. C. to 11 cps at 110.degree. C. and may be used to fill substantially voids in a cable comprising as many as 3000 pairs of insulated metallic conductors. The superabsorbent polymer is incorporated into the gel composition in a concentration of about 10 parts by weight to per 100 parts by weight of the filling mixture. A flooding material which comprises a mixture of a flooding composition and a superabsorbent polymer may be used to flood voids between layers of the sheath system.
    Type: Grant
    Filed: August 31, 1992
    Date of Patent: April 26, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Kent B. Connole, Richard S. Cuprak, Myles H. Grunewald, David M. Mitchell, Gabriel P. Pellicciotti, Albert S. Tingley
  • Patent number: 5095176
    Abstract: An aerial cable (20) includes a transmission portion and a supporting portion. The transmission portion includes a core (21) comprising at least one transmission medium enclosed in a relatively flexible dielectric wrapping material (23). The wrapping material is enclosed by two metallic shields (31, 40) between which is interposed a layer (42) of a waterblocking material. An outer one (40) of the shields is formed with overlapping longitudinal edge portions at least one of which is turned inwardly toward the core. A cavity (44) between those edge portions is provided with a waterblocking material which inhibits the longitudinal flow of water. The supporting portion includes a longitudinally extending strand material (60) capable of supporting a length of the cable which is supported by poles, for example, at ends of the length. A plastic jacket (45) encloses the supporting portion and the transmission portion.
    Type: Grant
    Filed: June 12, 1990
    Date of Patent: March 10, 1992
    Assignee: AT&T Bell Laboratories
    Inventors: Paul W. Harbrecht, Frederick L. Henklein, David M. Mitchell, Cecil G. Montgomery, Francis J. Mullin, James J. Riordan
  • Patent number: 5043539
    Abstract: A bonded sheath cable (20) includes a core (22) and a longitudinally wrapped outer shield (36) which encloses the core. An outer surface of the shield is provided with a layer (39) of a copolymer adhesive material which causes the shield to bond to an outerlying plastic jacket (41). The shield is wrapped longitudinally about the core to have overlapping portions (51,53) which form a longitudinal seam (38). In order to avoid seam splitting of the jacket along a line aligned with the longitudinal edge (55) of the outer overlapping portion, control means (60) comprising a polymeric material is provided to extend in bicircumferential directions from the longitudinal edge thereby reducing the bond along the overlap seam and allowing the cable to bend and/or twist without causing a stress concentration in the plastic overlying the longitudinal edge.
    Type: Grant
    Filed: March 28, 1990
    Date of Patent: August 27, 1991
    Assignee: AT&T Bell Laboratories
    Inventors: Kent B. Connole, Richard S. Cuprak, Jr., Karen D. Dye, Michael K. McKee, David M. Mitchell, Gabriel P. Pellicciotti, Albert S. Tingley
  • Patent number: 4755629
    Abstract: A cable (20) which is particularly suited to the transmission of substantially error-free data at relatively high rates over relatively long distances includes at least two pairs of individually insulated conductors (42--43). Each pair of individually insulated conductors is enclosed individually in its own tubular member (51) comprising a plastic material. A metallic shield (60) encloses the tubular members, and in a preferred embodiment, a plastic jacket (80) encloses the shield. In the preferred embodiment, two pairs of voice communications conductors are disposed at opposed locations between the shield and the jacket. The thickness of the tubular member is such that each insulated conductor of each twisted pair is caused to be spaced from the shield a distance which is not less than one half the diameter of the metallic wire portion of each pair enclosed by the tubular member.
    Type: Grant
    Filed: September 24, 1986
    Date of Patent: July 5, 1988
    Assignees: AT&T Technologies, AT&T Bell Laboratories
    Inventors: Richard D. Beggs, Harold W. Friesen, David M. Mitchell, Wendell G. Nutt, Palmer D. Thomas