초록 ▼

A thermal exposure monitor has a thermally-conductive housing adapted to be placed in close proximity to a product to be monitored and at least one thermally-responsive shape memory alloy member in the housing that has a first shape at temperatures below a critical temperature and a second shape at

A thermal exposure monitor has a thermally-conductive housing adapted to be placed in close proximity to a product to be monitored and at least one thermally-responsive shape memory alloy member in the housing that has a first shape at temperatures below a critical temperature and a second shape at temperatures above the critical temperature and a transformation temperature range encompassing a prescribed detrimental temperature related to the product being monitored. An indicator associated with the thermally-responsive member is moved from an initial position as the thermally-responsive member changes from the first shape to the second shape so as to be visually observed through a window on the housing to visually indicate whether the product being monitored has been exposed to temperatures above the prescribed detrimental temperature for a period of time that would be detrimental to the product.

대표청구항 ▼

1. A cumulative thermal exposure monitor for indicating absorption of heat outside of a prescribed temperature range for a prescribed period of time, comprising:a thermally-conductive housing having a transparent window portion, said housing formed of a material having prescribed thermal properties;

1. A cumulative thermal exposure monitor for indicating absorption of heat outside of a prescribed temperature range for a prescribed period of time, comprising:a thermally-conductive housing having a transparent window portion, said housing formed of a material having prescribed thermal properties; a thermally-responsive member in said housing formed of a shape memory alloy having a first shape at temperatures below a critical temperature and changing to a second shape at temperatures above the critical temperature and having a transformation temperature range encompassing said prescribed temperature range; indicator means associated with said thermally-responsive member to be moved from an initial position thereby as said thermally-responsive member moves between said first shape and said second shape so as to be visually observed through said window; a photochromic film material disposed in said housing closely adjacent to said indicator means and said thermally-responsive member; either of said indicator means or said thermally-responsive member containing a radiation emitting substance to effect said film material; said prescribed thermal properties of said housing and said transformation temperature range of said shape memory alloy correlated such that said thermally-responsive member moves between said first shape and said second shape upon absorption of heat above said critical temperature for said prescribed period of time; said indicator means remaining in a position at which it was moved by said thermally-responsive member to indicate the absorption of heat above said critical temperature for said prescribed period of time; and said film is altered by exposure to the radiation emitting substance with respect to time and location of said indicator means and said thermally-responsive member as said thermally-responsive member changes from said first shape to said second shape to provide a time and temperature log of environmental thermal events indicating absorption of heat above said critical temperature for said prescribed period of time.