GB681445A - An improved rear projection screen unit for picture projection - Google Patents

Abstract

681,445. Optical - projection apparatus. STABLEFORD, J. L. Dec. 21, 1950 [Dec. 21, 1949; April 19, 1950], Nos. 32740/49 and 9669/50. Class 97 (i). A rear projection unit comprises a rigid housing 2 with a screen 1 at the front and at least one reflector at the rear end 3 to throw on to the screen an image from a projector at the side of the housing, the screen being hooded at least at top and sides by hinged flaps 35, 37, 38, the flaps 37 and 38 having wings 40 which support the flap 35 when the hood is open, and when the hood is closed, are accommodated in the housing 2. In the form shown, the wings 37, 38 also have wings 41 to support a bottom flap 36. The frame 7, at the front of the housing, supports, through screws 9, a smaller frame carrying the screen, there being a narrow space between the frames through which the wings 40, 41 pass as the hood is closed. When closed, the hood is secured by catches 44. The projection light beam passes through a trunk 4 at the side of the housing. As shown, the trunk is hinged at 27 so as to be able to be pushed in flush with the housing wall or pulled out for projection to be effected through the aperture 5. A turnbuckle 30 secures it in either position. An inspection aperture 33, with cover 34, is provided. The mirror at 3 is inclined and may be detachable through a slot in the casing. The housing 2 tapers rearwardly and may have a foldable leg (not shown) at the rear so that it can stand on a level table. A foldable supporting frame, as shown, may be provided, having two tubular frames 50, 51, the rear vertical members 53 of which are hinged, the front members 52 being held, when open, by a diagonal strut 57 hinged to the top of the frame 50 and detachably secured at 58 to the frame 51. A frame 62, comprising parallel tubes, is hinged to the top bar 54 of the frame 51 and clips on to the top bar of the frame 50. The frame 62 carries projections, not shown, for locating the projector and a table 70 for supporting the projector. The table may have locating means for the projector. The vertical frame members may have feet 73, 74, 75 which may be adjustable telescopically. An upward extension on one of the tubes 53 holds the screen unit level. A strap 80, 81 secures the screen frames when folded. In a modification, Fig. 8, the supporting structure 84 has an upper horizontal rectangular frame with folding legs. The screen structure is secured obliquely and the projector on the table 85 projects through a hole in the side wall, there being no trunk. The beam is reflected successively by three mirrors 82, 83, 19<SP>1</SP>.