| 摘要 |
A projection screen comprises a film (4) having a projection side (10, 11, 17, 25) and provided with a number of passages (10', 10'', 12, 13, 28, 29, 30)adapted for permitting emitted sound waves to pass through said film. The projection screen is characterized in that these passages are arranged in such a manner that, if alignments can be detected, at least the principal ones have an angle alpha that is not zero with regard to the vertical and horizontal edges of the screen. |
