Patents by Inventor David W. Johnson, Jr.

David W. Johnson, Jr. 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).

  • Negative temperature coefficient thermistors
    Patent number: 4531110
    Abstract: Inexpensive Mn or Mg ferrites may be used as negative temperature coefficient thermistors. Fabrication of devices with the desired high temperature coefficients is facilitated by a processing method which forms a thin layer of oxidized and high resistivity material on a low resistivity layer of ferrite material.
    Type: Grant
    Filed: September 14, 1981
    Date of Patent: July 23, 1985
    Assignee: AT&T Bell Laboratories
    Inventors: David W. Johnson, Jr., Murray Robbins
  • Fabrication of sintered high-silica glasses
    Patent number: 4419115
    Abstract: High-silica glasses are formed by sintering a dried gel at temperatures below the liquidus. The gel may be formed by mixing colloidal silica particles or silica-containing liquids with appropriate liquids. Fragmentation of the gel during drying is advantageously avoided by redispersing the dried gel or sol in a liquid to yield a colloidal suspension which is then gelled, dried, and finally sintered below the liquidus.
    Type: Grant
    Filed: July 31, 1981
    Date of Patent: December 6, 1983
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: David W. Johnson, Jr., John B. MacChesney, Eliezer M. Rabinovich
  • Method of ceramic preparation
    Patent number: 4357251
    Abstract: Preparation of ceramic materials, including ferrites and garnets, through a processing sequence that includes a sintering step is facilitated by a flux, having a relatively low melting temperature and an approximately eutectic composition consisting of two or more of the final ceramic components. The flux permits the sintering step to proceed at temperatures lower than otherwise possible, and results in better control of the final ceramic composition and microstructure.
    Type: Grant
    Filed: November 7, 1977
    Date of Patent: November 2, 1982
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: David W. Johnson, Jr., Man F. Yan
  • Process of slurrying and spray drying ceramic oxides with polyethyleneimine dispersants
    Patent number: 4301020
    Abstract: Many ceramics are produced with a processing sequence that includes spray drying or ball milling a slurry. To produce ceramics with the best properties and to facilitate ball milling or spray drying, a dispersant is normally added to the ceramic slurry. Ammonium citrate and polyethylenimine have been found to produce ceramic slurries with the desired characteristics. The dispersants appear especially well suited for use with ferrite slurries.
    Type: Grant
    Filed: February 6, 1981
    Date of Patent: November 17, 1981
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: David W. Johnson, Jr., Eva M. Vogel
  • Persistent memory cell
    Patent number: 4297005
    Abstract: Display devices are described which contain, in addition to organic quinones and suitable organic solvent, a solid ionic conductor. Such display devices are advantageous because of exceptional persistence of the display. Thus, an image may be retained without application of electrical energy. In addition, these displays exhibit high optical contrast and low power consumption. Under certain conditions, these devices are non-linear (exhibit sharp thresholds) which permit multiplexing. This is highly advantageous in display device applications.
    Type: Grant
    Filed: June 25, 1979
    Date of Patent: October 27, 1981
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: David W. Johnson, Jr., Shobha Singh, LeGrand G. Van Uitert, George J. Zydzik
  • Dispersants for a ceramic slurry
    Patent number: 4267065
    Abstract: Many ceramics are produced with a processing sequence that includes spray drying or ball milling a slurry. To produce ceramics with the best properties and to facilitate ball milling or spray drying, a dispersant is normally added to the ceramic slurry. Ammonium citrate and polyethylenimine have been found to produce ceramic slurries with the desired characteristics. The dispersants appear especially well suited for use with ferrite slurries.
    Type: Grant
    Filed: August 1, 1978
    Date of Patent: May 12, 1981
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: David W. Johnson, Jr., Eva M. Vogel
  • Method of making MnZn ferrites
    Patent number: 4246128
    Abstract: Desirable properties of manganese zinc ferrites are obtained without the need for controlling or changing the oxygen partial pressure during the sintering and cooling steps by adding a small amount of germanium or gallium to the ferrite and using an atmosphere, such as air, during the sintering and cooling steps, that has at least 1 percent oxygen by volume.
    Type: Grant
    Filed: August 8, 1979
    Date of Patent: January 20, 1981
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: Patrick K. Gallagher, Ernst M. Gyorgy, David W. Johnson, Jr., Murray Robbins