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:
Jan. 19, 1993
Filed:
May. 02, 1990
Mark A Jozefowicz, Kingston, CA;
Alcan International Limited, Montreal, CA;
Abstract
Liquid and/or temperature activated elaspsed time sensors suitable, in particular, for use as doneness indicators for foodstuffs and for other purposes. The liquid activated indicators include a porous structure which generates a first color by effects which include optical interference when pores of the structure are gas-filled, and a second contrasting color when the pores of the structure are liquid filled. The porous structure is covered with a transparent or translucent cover which is unattached in certain areas to allow for capillary movement of liquid between the cover and the porous structure. An entrance permits liquid to enter between the cover and the porous structure. When contacted with liqiuid, the liquid is drawn into the device and produces an expanding area of contrasting color which is used to indicate the elapse of time. In one form, the doneness indicator, when located on the outside of a food container, can be activated by water condensed from steam generated as the food is heated, preferably by microwaves. In an alternative form the activated elapsed time indicator may contain a meltable solid which provides the liquid to operate the liquid activated indicator described above at a predetermined temperature.