Staggered waveplate LCD privacy screen
US6239853A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1999 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | Oct 1, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2413/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An assembly for restricting the angle of vision of an image emitted from an LCD screen comprising a linearly parallel arrangement of two polarizing films with at least two waveplates there between. The transmission planes of the polarizing films are at an angle, preferrably 90.degree. to each other. At least two parallel waveplates are positioned between, the polarizing films. Each waveplate has parallel transmitting regions alternating between birefringent and isotropic regions. The waveplates are positioned in a spaced apart relationship to each other such that substantially orthogonal light passing through the first polarizing screen and one of the birefringent or isotropic alternating transmitting regions of the first waveplate will pass through the other of the alternating striped transmitting regions of the second waveplate. Light so transmitted will then pass through the second polarizing film and be viewable. At least a portion of the horizontal components of non-orthogonal light incident on the waveplate assembly will not pass through the second polarizing film This assembly results in a angle of vision narrower than from the LCD screen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.