Patents by Inventor Douglas Walker

Douglas Walker 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).

  • Phosphorescent materials
    Patent number: 4089995
    Abstract: A method of rendering a surface, especially a paper surface, phosphorescent, in which a composition comprising a phosphorescence activator and a soluble condensation product of formaldehyde and an amino compound is applied to the surface and is allowed to react in situ to form a phosphorescent insoluble condensation product. The composition may, for example, be in the form of a printing ink or a paper-coating mix.
    Type: Grant
    Filed: December 7, 1976
    Date of Patent: May 16, 1978
    Assignee: Post Office
    Inventors: Berkeley Michael Ferro, Rodney Edwin Spratling, Aubrey Douglas Walker
  • Phosphorescent materials
    Patent number: 4022709
    Abstract: Phosphorescent materials and solutions suitable for their preparation, the solutions comprising a phosphorescence activator and a soluble condensation product capable of further reaction to form an insoluble condensation product, the latter being one that does not absorb ultraviolet radiation in the absorption range of the activator.
    Type: Grant
    Filed: January 22, 1975
    Date of Patent: May 10, 1977
    Assignee: The Post Office
    Inventors: Berkeley Michael Ferro, Rodney Edwin Spratling, Aubrey Douglas Walker