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:
May. 10, 1994
Filed:
Dec. 15, 1992
Suzan J Hirz, Maplewood, MN (US);
Bruce W Weeks, Lake Elmo, MN (US);
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
A method for locally enhancing the contrast of a yellow image, which method comprises providing a yellow image on a white background, said image comprised of yellow areas and white areas, said yellow areas and white areas exhibiting pH levels which differ by at least 0.5 in an aqueous environment, applying to at least a portion of said yellow image a solution of a pH color changing dye which will change color to a color other than yellow when coated on one of said yellow areas or white areas and not change color when coated on the other of said yellow areas or white areas, thereby forming a colored image duplicating the yellow image in areas where the solution has been applied, said colored image having a visually better contrast than said yellow image.