GB377784A - Improvements relating to optical projection apparatus - Google Patents

Abstract

377,784. Kaleidoscopic projection apparatus. CROCKER, W. A., 38, Leamington Street, Oak Lane, Bradford, Yorkshire. June 6, 1931, No. 16598. [Class 97 (i).] In kaleidoscopic optical-projection apparatus the object box is rotatable on a fixed cylinder enclosing the mirrors, and is intermittently turned by a star wheel engaged by a pin on a constantly driven member. As shown, the object box is formed with a toothed ring 23 meshing with a pinion 22 on a spindle 21 carrying a star wheel 20 turned intermittently by a pin 19 on a gear 18 constantly rotated by a worm 17 on the spindle of a motor 16. The box 10 is illuminated by a lamp 11 and comprises glass discs 25, 26 separated by a fibre &c. ring 27, the disc 25 being provided with an opal skin ; two mirrors 13 are held by apertured and slotted discs 29 secured in a fixed cylinder 24. The aperture in each disc 29 may be shaped to produce an image of circular or other outline, and lettering may be cut in its edge or inscribed on the box 10 ; the projection screen may be blackened where necessary to render the reversed images of the lettering invisible. Three or more mirrors may be used, and the mirrors may be replaced by a prism. The optical axis a, b of the projection lens 14 and the line of intersection of the mirrors may be relatively inclined, either of them. being normal to the faces of the object box. Constructions in which the object box is illuminated through an opening in the cylinder 24, and in which the lens 14 is replaced or augmented by a concave mirror, are described.