| 摘要 |
1467569 Projection screens NECKERMANN VERSAND KGaA 18 Aug 1975 [17 Jan 1975] 34267/75 Heading G2X [Also in Division H4] At least one loud speaker is mounted inside a box housing a projection screen rolled on a spool. The screen is unwound from the box and the loud speaker permits a commentary or music to accompany the projected pictures. Preferably two speakers are provided, one at each end of the spool, for stereophonic effects. |
