GB344876A - Improvements in periodically controlled mechanism for advertisement and other purposes - Google Patents

Abstract

344,876. Changing signs. MARPLES, S. A., Norton, Walpole Avenue, Chipstead, Surrey. Nov. 9, 1929, No. 34258. [Class 3 (i).] Optical-projection apparatus.- Transparencies for optical-projection are mounted horizontally on a horizontal holder h rotated intermittently about a vertical shaft g, the projector beam passing from the source of light without deflection vertically through the transparencies, and being reflected by an inclined reflector q on to a screen s. A pivoted pawl t rests on the holder h and falls into registering slots therein at each stop. Two or more opticalprojectors may be combined with one holder, and a corresponding number of inclined reflectors and screens. In one arrangement four projectors are provided, and the screens form a pyramid with the apex removed. Fig. 5 depicts a holder in the form of a disc h having a curved annulus 15 about the transparency openings. Flexible transparencies are placed over the openings and are held in place by spring plates 17 having hooks 18 and clips 20. A secondary colour disc 24 may be pivoted to the disc h about a vertical spindle 25 to control the appearance &c. of the transparency immediately beneath, and a further colour disc 29 may be pivoted to an external frame 30. The disc 24 is intermittently rotated by pins 27 thereon striking a fixed abutment 28, and the disc 29 by an arm 33 on its spindle contacting with pins 32 on the disc h. The pawl t may have a stepped face 45, 46, Fig. 7, whereby the holder h is either retained in other than its central position, or is jerked forward after coming to rest. The pawl may form part of a switch whereby the projector lamp P is extinguished during movement of the holder. The holder h may be driven by gearing e, f or by an arm 54, Fig. 10, engaging notches 57 in the holder, the arm being pivoted to a crank-pin &c. 56 on the motor spindle 52. The transparencies may bear advertisements, messages, or pictures. The reflector q may be replaced by mirrors mounted on the holder h, one for each transparency.