Elapsed time indicator
US4229813A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1978 |
| Grant date | Oct 21, 1980 |
| Priority date | — |
| Expiry date | Jun 26, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04F13/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A time indicator which is substantially unaffected by variations in temperature. The indicator utilizes a silicone oil which is slowly absorbed onto and moves up a porous strip at a rate which is a function of time. One side of the strip is printed with an oil soluble ink, while the other side is unprinted. The printed side of the strip is laminated with polyethylene film to an unprinted strip. As the silicone oil moves up the strip, the oil contacts the ink causing a dye in the ink to migrate from the printed side to the unprinted side, thus providing a measurable color front moving up the strip. The oil is contained in a frangible ampul and a sponge with a small hole at the bottom is situated between the ampul and the strip. The indicator is substantially unaffected by normal variations in temperature and humidity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.