Control mechanism for positioning projection screen in closed position
US4072404A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 9, 1976 |
| Grant date | Feb 7, 1978 |
| Priority date | — |
| Expiry date | Jan 9, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B21/58
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection screen apparatus includes an elongate roller, a flexible screen which is wound on the roller when it is in a closed position and unwound from the roller when it is in an exposed position, an electric drive motor connected to the roller for rotating the roller to move the screen between exposed and closed positions, a first switch for actuating the drive motor to move the screen toward a closed position, and a second switch for stopping the drive motor and the roller when the screen is in a fully closed position. A free marginal end portion of the screen engages a lever which moves the second switch to an inoperative position to interrupt the electric circuit leading to the drive motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.