Patents by Inventor Patrick D. P. Thomas

Patrick D. P. Thomas 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).

  • Hydroquinone derivatives and their use in photographic materials
    Patent number: 4480104
    Abstract: Compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl, X represents the atoms to complete an aromatic heterocyclic ring system and Y is hydrogen or has the meaning assigned to X, are readily cleaved in alkaline solutions to release a hydroquinone derivative.The compounds can be incorporated into photographic materials used for activation processing.
    Type: Grant
    Filed: May 15, 1983
    Date of Patent: October 30, 1984
    Assignee: Ciba-Geigy AG
    Inventors: Stephen R. Postle, Patrick D. P. Thomas
  • Hydroquinone derivatives and their use in photographic materials
    Patent number: 4443537
    Abstract: Substituted hydroquinone compounds of the formula ##STR1## wherein R.sub.1 to R.sub.4 are hydrogen or alkyl and Z is an aromatic ring or a group of the formula --X--Y--X--, wherein X is an aromatic ring and Y is an electron withdrawing group, are incorporated as developers into photographic materials. These materials are suitable for activation processings.
    Type: Grant
    Filed: September 24, 1982
    Date of Patent: April 17, 1984
    Assignee: Ciba-Geigy AG
    Inventors: Stephen R. Postle, Patrick D. P. Thomas, Brian R. D. Whitear
  • Hydroquinone derivatives and their use in photographic materials
    Patent number: 4426444
    Abstract: Compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl, X represents the atoms to complete an aromatic heterocyclic ring system and Y is hydrogen or the group ##STR2## where X is defined as above, are readily cleaved in alkaline solutions to release a hydroquinone derivative.The compounds can be incorporated into photographic materials used for activation processing.
    Type: Grant
    Filed: September 17, 1982
    Date of Patent: January 17, 1984
    Assignee: Ciba Geigy AG
    Inventors: Stephen R. Postle, Patrick D. P. Thomas
  • Hydroquinone derivatives and their use in photographic materials
    Patent number: 4417072
    Abstract: Substituted hydroquinone compounds of the formula ##STR1## wherein R.sub.1 to R.sub.4 are hydrogen or alkyl and Z is an aromatic ring or a group of the formula --X--Y--X--, wherein X is an aromatic ring and Y is an electron withdrawing group, are incorporated as developers into photographic materials. These materials are suitable for activation processings.
    Type: Grant
    Filed: September 29, 1981
    Date of Patent: November 22, 1983
    Assignee: Ciba-Geigy AG
    Inventors: Stephen R. Postle, Patrick D. P. Thomas, Brian R. D. Whitear
  • Hydroquinone derivatives of pyridinecarboxylic acids
    Patent number: 4410702
    Abstract: Compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl, X represents the atoms to complete an aromatic heterocyclic ring system and Y is hydrogen or has the meaning assigned to X, are readily cleaved in alkaline solutions to release a hydroquinone derivative.The compounds can be incorporated into photographic materials used for activation processing.
    Type: Grant
    Filed: September 29, 1981
    Date of Patent: October 18, 1983
    Assignee: Ciba-Geigy AG
    Inventors: Stephen R. Postle, Patrick D. P. Thomas
  • Process for the production of photographic images and photographic materials used in this process
    Patent number: 4353974
    Abstract: A process for the production of a photographic image which comprises(a) imagewise exposing a photographic assembly which comprises at least during a silver halide developing step, in order optionally a supercoat layer, at least one silver halide emulsion layer, a layer containing a layer substantive hydroxypyridone azamethine compound of the general formula ##STR1## wherein R.sub.1 is hydrogen or an optionally substituted alkyl, aralkyl, cycloalkyl, aryl, amino or heterocyclic radical, Y represents hydrogen or hydroxy, --CN, --COOR.sup.1, --CONR.sup.1 R.sup.2 or --COR.sup.1 or an optionally substituted alkyl, aralkyl, cycloalkyl, aryl or heterocyclic radical and Z is hydrogen or is --CN, --COOR.sup.3, --CONR.sup.3 R.sup.4, --SO.sub.3 H, --SO.sub.3.sup.- or --COR.sup.3, where R.sup.1, R.sup.2, R.sup.3 and R.sup.
    Type: Grant
    Filed: February 23, 1981
    Date of Patent: October 12, 1982
    Assignee: Ciba-Geigy AG
    Inventors: Terence C. Webb, Patrick D. P. Thomas, William E. Long