Improvements in or relating to picture and sound reproduction for schools

摘要

660,821. Optical - projection apparatus. GUINNESS, G. H. GRATTAN-. Jan. 2, 1950 [Dec. 2, 1948], No. 31287/48. Class 97 (i). The apparatus as shown in plan comprises a structure a having walls a1, a2, a3, a' and completed by an angled wall having an aperture in which a screen b is mounted. Doors f may be closed to cover the screen. Each carries a sector-shaped leaf fSP1/SP at the top which acts as a light shield when the door is open and is contained in the structure above the screen when the door is closed. A flap e is hinged at the bottom of an aperture in the wall aSP4/SP to form a shelf to support a projector eSP1/SP. The projection beam is reflected on to the screen by a mirror c. The structure has a lower compartment containing a loud-speaker.