Device for the local attenuation of the light intensity in the field of vision of a light-sensitive monitoring device
US6636278B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 6, 1999 |
| Grant date | Oct 21, 2003 |
| Priority date | — |
| Expiry date | Apr 6, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/75
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A device for the local attenuation of the light intensity in the field of vision of a light-sensitive monitoring and/or recording device (CCD) is described, which is suitable in particular as a glare protection device for video cameras in videophones or correspondingly equipped PCs. The device includes a first objective (L1) and a high resolution ferroelectric liquid crystal modulator (PC, LC) arranged between two polarizers (P1, P2), the liquid crystal modulator having a photo-conductive layer (PC) and a downstream liquid crystal film (LC) made up of helical smectic liquid crystals which is in contact with this layer. The photo-conductive layer (PC) is essentially arranged in the image plane of the first objective (L1), the image plane being imaged onto the monitoring and/or recording device by a second objective (L2). As this occurs, bright light sources or backgrounds are locally suppressed without resulting in a glare or bloom of the image. As an alternative, if the intermediate imaging is omitted, the monitoring and/or recording device (CCD) may be arranged in the image plane of the first objective (L1), the second objective (L2) being eliminated. In this connection, the liqui…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.