LIQUID AND/OR TEMPERATURE ACTIVATED ELAPSED TIME INDICATORS SUITABLE, IN PARTICULAR AS DONENESS INDICATORS FOR FOODSTUFFS

摘要

PURPOSE: To display an elapsed time accurately and reliably from a predetermined condition is sensed. ;CONSTITUTION: A liquid activated indicator 10 comprises porous structures 11, 12 that generate a first color by effects, which include optical interference when a pore 16 is gas-filled, and a second contrasting color when the pore 16 is liquid-filled. The porous structures 11, 12 are covered with a transparent or translucent cover 17. The cover 17 has a gap X in certain areas to allow for capillary movement of liquid between the cover and the porous structure 12. An entrance 20 is provided to permit liquid to enter between the cover 17 and the porous structure 12. When contacted with liquid, the liquid is drawn into the device and produces an expanding area of contrasting color, which is used to indicate the elapsed time.;COPYRIGHT: (C)1993,JPO