Control device to position projection screen for viewing
US4045123A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 9, 1976 |
| Grant date | Aug 30, 1977 |
| 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 an exposed position, and a second switch for stopping the drive motor and the roller when the screen is in a fully exposed position. A lever urged against the screen wound on the roller moves the second switch to an inoperative position when a predetermined amount of screen is unwound from the roller to interrupt the electric circuit leading to the drive motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.