| 摘要 |
An overhead projector is provided which eliminates disturbing light on a projection screen (12) from parts of a picture plate (2) of the projector which surround a projected document (10) as well as light on the screen (12) which arises when documents are being changed on the picture plate (2). The picture plate (2) is covered with a first polarizing layer (3) which is a supporting surface for the document, by placing a second polarizing layer (9) in the path of the light close to a projector head (6, 7) and by arranging the polarization directions of the first and second polarizing layers (3, 9) perpendicular to each other so that light which first passes the first polarizing layer (3) where no document is placed and thereafter passes the second polarizing layer (9) is absorbed. |
