The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 11, 1988
Filed:
Feb. 04, 1987
Jonathan P Kitchin, Hertford, GB;
Carlo Marchesano, Savona, IT;
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
High contrast negative images are obtained by developing a silver halide photographic element, in the presence of a hydrazine compound, with an alkali aqueous developing solution which contains a combination of developing agent comprising hydroquinone or substituted hydroquinone and a superadditive developing agent and an antioxidant, wherein the developing solution has a pH lower than about 12 and wherein the silver halide photographic element comprises an emulsion layer including surface latent image negative type silver halide grains in reactive association with a contrast promoting agent, preferably a diarylcarbinol compound, more preferably a diarylmethanol compound in a quantity useful to increase contrast.