Expiration indicator
US7188996B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Jul 1, 2004 |
| Grant date | Mar 13, 2007 |
| Priority date | — |
| Expiry date | Jul 1, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K3/04
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.