07188996 is referenced by 10 patents and cites 23 patents.

A simple recording device using a stable electric resistance heater in thermal contact with an irreversible color changing time temperature material relatively insensitive to room temperatures to show and record the cumulative time an electrical appliance, battery, tool, instrument has been used. The device may use a plurality of thick film carbon printed resistive heater with a thermal gradient in contact with the time temperature material or a simple adhesive calibrated time temperature film on a surface mounted stable resistor. The indicator is in parallel or series with the power switch. The time temperature material is in thermal contact with a constant temperature heater when used in fluctuating ambient temperature conditions.

Title
Expiration indicator
Application Number
10/885217
Publication Number
7188996 (B2)
Application Date
July 1, 2004
Publication Date
March 13, 2007
Inventor
Robert Parker
Bend, 97702
OR, US
IPC
G01K 7/22
G01K 1/12
G01K 3/02
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