Level indicator having thermochromic leucodye inks
US6880396B2 · kind B2 · utility
Inventor
Key dates
| Filing date | Oct 31, 2003 |
| Grant date | Apr 19, 2005 |
| Priority date | — |
| Expiry date | Oct 31, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A level indicator and method is provided which is intimately affixed to the outside surface of the outside wall of a container, for use in the determination of the level of the interface between a liquid and the void volume above it within a container. The level indicator includes a thermochromic leucodye ink layer which has at least one, and usually at least two, leucodye inks. Each of the leucodye inks responds chromatically within a different operating temperature range. In one embodiment, the level indicator vertically extends substantially the height of the container. In an alternative embodiment, the level indicator vertically extends along the height of the container, in the region of the top portion of the container, and at least above the legal safe-fill level of the liquid within the container such that overfilling of the liquid in the container is detectable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.