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:
Sep. 16, 1997
Filed:
Mar. 10, 1995
Robert P Arens, St. Paul, MN (US);
Russell D Birkholz, Maplewood, MN (US);
Dee Lynn Johnson, Woodbury, MN (US);
Theodore P Labuza, Arden Hills, MN (US);
Curtis L Larson, Hudson, WI (US);
David J Yarusso, Shoreview, MN (US);
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
A selectively activated time-temperature integrating device for providing a visually observable indication of cumulative thermal exposure, in which a viscoelastic material migrates into a diffusely light-reflective porous matrix at a rate which varies with temperature to progressively change the light transmissivity of the porous matrix and thereby provide the visually observable indication. The viscoelastic material can comprise a pressure sensitive adhesive. The visually observable indication can comprise latent indicia which initially are not visible and become visible, obscurable indicia which initially are visible and become obscured, or a combination of both. Various actuating means for selectively switching the indicator from an unactivated state to an activated state are described. Also disclosed are a method for providing a visually observable indication of cumulative thermal exposure and a method for providing a time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure of an object.