Patents by Inventor Francois Leon Schelfaut

Francois Leon Schelfaut 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: 4108661
    Abstract: A photographic material is described for making positive images by reversal processing, the material comprising a support and a silver halide Lippmann-emulsion layer the average silver halide grain-size of which is less than 100 nm wherein the grains have been chemically sensitized to fog so that a test portion of the emulsion when coated on a support at a coverage of silver halide corresponding to from about 3 g to about 7 g of silver nitrate per sq.m. gives a density between about 0.20 and about 0.70 upon development without exposure for 6 min at 20.degree. C in a developer of the composition:Hydroquinone: 16.5 gPotassium bromide: 1.7 gSodium salt of EDTA: 1.7 gPotassium metabisulphite: 40 g1-phenyl-5-mercaptotetrazole: 35 gSodium hydroxide and water to make: 1 liter at pH 11.
    Type: Grant
    Filed: December 3, 1976
    Date of Patent: August 22, 1978
    Assignee: Agfa-Gevaert, N.V.
    Inventors: Willy Joseph Vanassche, Herman Adelbert Philippaerts, Rene Omer Duville, Francois Leon Schelfaut
  • Patent number: 4081280
    Abstract: A process for developing photographic silver halide lith-materials in an automatic processing machine with a lith-developer, wherein two replenishers are used, one for compensation of the developer exhaustion resulting from aerial oxidation and a second replenisher serving for the compensation of exhaustion by development.
    Type: Grant
    Filed: February 26, 1976
    Date of Patent: March 28, 1978
    Assignee: AGFA-GEVAERT N.V.
    Inventors: Hans Josephus Corluy, Francois Leon Schelfaut, Pierre Herman Nys, Raoul Jan Bortels
  • Patent number: 3947273
    Abstract: A process is described of improving the development characteristics of photographic silver halide elements by the use of compounds corresponding to the formula:RO(CH.sub.2 CH.sub.2 O).sub.n (CO).sub.m Awherein:R represents hydrogen, C.sub.1 -C.sub.5 alkyl or (--CO).sub.m --A,n is an integer of at least 4,m is 0 or 1, andA represents, when m is O, sulphoalkyl, carboxyalkyl, or sulphoalkoxycarbonylalkyl, and when m is 1, carboxyalkyl, sulphoalkoxycarbonylalkyl, carboxyalkenyl, sulphoalkoxycarbonylalkenyl, carboxyphenyl, sulphoalkoxycarbonylphenyl or sulphophenyl,The aliphatic hydrocarbon groups having at most 4C-atoms and the carboxyl and sulpho groups being in acid or salt form. The polyethylene glycol derivatives increase developability and sensitivity of black-and-white as well as colour emulsions. They also improve lith-development of photographic "lith"-emulsions.
    Type: Grant
    Filed: April 29, 1974
    Date of Patent: March 30, 1976
    Assignee: Agfa-Gevaert, N. V.
    Inventors: Robert Joseph Pollet, Herman Adelbert Philippaerts, Francis Jeanne Sels, Francois Leon Schelfaut