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:
Dec. 27, 1994
Filed:
Oct. 04, 1993
Marian S Henry, Rochester, NY (US);
Sandra M Finn, Honeoye Falls, NY (US);
Harry J Price, Webster, NY (US);
Eastman Kodak Company, Rochester, NY (US);
Abstract
A process for controlling the silver halide grain-to-grain distribution of a variable contrast dye in a light sensitive silver halide emulsion layer of a variable contrast photographic element, and thereby adjusting the low contrast characteristic curve of the element, is disclosed comprising the process steps of adding a green variable contrast sensitizing dye of the following formula (I) to a silver halide emulsion for a variable contrast photographic element, adding a blue sensitizing dye of the following formula (II) to the same silver halide emulsion, and coating the emulsion on a support. In the process, the green and blue sensitizing dyes are added to the emulsion at substantially the same time, and the green dye is added in an amount less than that required to impart maximum sensitivity to all of the silver halide in the emulsion. ##STR1## In formula (I), R.sup.1, R.sup.2, R.sup.6 and R.sup.7 each independently represent hydrogen, halogen, hydroxy, or substituted or unsubstituted alkyl, alkenyl, alkoxy, alkylamino, alkylthio, aryl, aryloxy, arylamino or arylthio. R.sup.3, R.sup.4 and R.sup.5 each independently represent substituted or unsubstituted alkyl or aryl. X represents a counterion as needed to balance the charge of the molecule. In formula (II), Z represents the atoms necessary to complete an optionally further substituted five- or six-membered heterocyclic ring, R.sup.8 represents substituted or unsubstituted alkyl or aryl, and R.sup.9 represents hydrogen, substituted or unsubstituted alkyl or aryl, or a heterocycle.