| 摘要 |
<p>A projection screen comprises a sheet with grooves on its observed face, pref. also with other grooves running transversely to these, so that between the sets of grooves pyramids of square or rhombus shape are produced. One surface may be coated with plastic (454g) contg. titanium dioxide (10-50g), optionally also contg. small glass balls to improve reflectivity.</p> |
