| 摘要 |
1,081,968. Optical projection screens. RADIANT MANUFACTURING CORPORATION. May 24, 1966 [May 24, 1965], No.23191/66. Heading G2J. A portable projection screen has a stand with three or more legs 26 hinged at 28 to a collar 30 which is fixed to column 11, and braced by links 34 which are pivoted at 33 to a sliding collar 32, and at 27 to legs 26, the legs being biased towards the retracted position of Figs. 1 and 3 (not shown) by coil springs mounted on pivots 27 and 28. The legs therefore automatically retract when the stand is lifted. The legs are extended by exerting an outward force on one leg, as by tilting the stand. |
