Electrochromic projection and writing device
US6441942B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1998 |
| Grant date | Aug 27, 2002 |
| Priority date | — |
| Expiry date | Sep 25, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2203/12
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A display and projection apparatus includes an electrochromic material and a photoconductive material deposited in tandem used in conjunction with a light filtering means for filtering light transmitted through the electrochromic material. When an electric field is applied across the electrochromic material and the photoconductive material, light that is incident onto the photoconductive material through the surface of the projection apparatus causes the photoconductive material to conduct current locally in proportion to the amount of light incident on the photoconductive material. The flow of current causes the underlying portions of the electrochromic material to switch from an opaque state to a clear or transmissive state, thereby allowing back-light to propagate through the electrochromic material to create a visible image on the surface of the projection apparatus. Reversal of the electric field causes the electrochromic material to revert back to its opaque state, thereby blocking the transmission of back-light and effectively erasing the image from the surface of the projection apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.