GB322535A - Improvements in or relating to optical projection apparatus - Google Patents

Abstract

322,535. Savage, J. C. Sept. 8, 1928. Optical-projection apparatus.-Luminous signs &c. are projected on to clouds or other distant screens, without the use of a stencil or other facsimile of the sign &c., by means for producing a substantially parallel beam of light, and an assemblage of separately adjustable optical units occupying a cross sectional area of the beam and capable of rotation in its own plane; the assemblage may be rotatable round the axis of the beam in the manner of a swash plate. As shown in Fig. 1, an assemblage of mirrors 4 is mounted on a member 5 inclined to the axis of the beam from a projector 10. The mirrors are each adjustably mounted by means of a ball and socket joint, or by means of a spring 6 and screws 7, Fig. 4, on a member 15, Fig. 5, which is rotatable in its own plane on the member 5. The member 15 may rotate on ball bearings round a collar 20, and may carry rollers 18 running on the member 5; screws 22 and slots may be provided to lock the members together. The member 5 may be formed with a. sleeve 8<1> rotatable on a shaft 8 carried by stays 9 secured to the projector casing; the projector may be rotatable round a vertical axis, and may be mounted on a vehicle. Pointers 11, 13, and scales 12, 14 may be provided. The mirrors may be replaced by prisms or lenses, and colour screens or distorting devices may be used at any point in the beam.