Temperature indicator for deep-frozen products
US5490476A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 1994 |
| Grant date | Feb 13, 1996 |
| Priority date | — |
| Expiry date | Aug 8, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K11/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for checking deep-frozen food, which irreversibly indicates if an additional storage temperature has been exceeded, is described. A flat plastic bag having transparent walls, into which eutectic mixture having a liquid/solid phase transition in the range from 0.degree. to -50.degree. C. has been introduced, together with a magnetic dispersion consisting of finely divided magnetic pigments, has a heat-conducting connection to the material to be frozen. A magnetic stripe which contains a magnetically recorded pattern and which remains connected to the bag until the indicating apparatus together with the material to be frozen has been cooled below the limiting temperature is stuck to the bag. The magnetic stripe is then removed. If the permissible limiting temperature is exceeded, the optically or magnetically readable structure produced by the magnetic stripe in the indicator bag is eliminated, permitting easy checking of the deep-frozen food. The present invention permits many potential variations by combination of a plurality of applied magnetic stripes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.