Projection screen assembly
US4406519A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 4, 1982 |
| Grant date | Sep 27, 1983 |
| Priority date | — |
| Expiry date | Feb 4, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B21/58
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection screen assembly is disclosed. The assembly includes a screen which can be lifted into an extended position or lowered into a collapsed configuration for permitting a building in which the screen is installed to be used for other purposes. Lifting means is provided for raising the screen and tensioning it in the vertical direction. Lateral tensioning is effected simultaneously by tensioning elements disposed one adjacent each side edge of the screen. The tensioning elements are coupled to the screen by lateral tensioning members which are of progressively decreasing length in directions extending inwardly from the upper and lower margins of the screen so that the tensioning elements adopt the shape of caternary curves. When the screen is tensioned vertically, these curves are flattened so that the screen is tensioned laterally by the lateral tensioning members.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.