Patent GB-341615-A (GB)
Title: Projection apparatus for projecting advertisements and other matter
IPC: G02B27/06
Filed: 1929-11-13
Abstract: 341,615. Changing signs. FIMMEN, O., 26, N³rnbergerstrasse, Dresden, Germany. Nov. 13, 1929. No. 34713. [Class 3 (i).] Optical-projection apparatus.-Apparatus for projecting luminous signs for advertisement and other purposes, comprises means for producing periodic movement of the projector and screen relatively to each other whereby the projected picture increases and diminishes in size during the period of projection. Preferably the screen is stationary and the projector moved, and modifications of the effect are produced by causing the movement to take place at different angles. Means are also provided for automatically focusing the picture at the varying distance and for changing the pictures. Figs. 1 and 2 show in side and end elevation one embodiment of the invention. The projector is mounted on a carriage 3 provided with wheels 4 running on rails 2 and reciprocated by a driven endless chain 5 to which it is connected by a link 8. The projector comprises a lamp housing 16, condenser 16<1>, objective 21 and a standard 17 on which is mounted the picture changing and.shutter device. ' The objective is mounted for vertical and lateral adjustment on a pivoted bail 25 which carries an arm 26 with a roller 27 running in a stationary cam groove, whereby in the reciprocating movements of the carriage the objective is moved to adapt the focusing according to the distance of the projector from the screen. The cam groove, at the end nearest the screen is parallel to the direction of movement of the carriage. The rails may be directed at right-angles or obliquely to the screen. The picture-changing device described consists of a disc 31 provided with openings 31<1> in which diapositives are mounted. The disc has ratchet teeth 35 and is moved through the distance between the pictures in the forward movement of the carriage by a lever-and-pawl device 32 actuated by a stationary cam 39 through the connecting- rod 36 and roller 38. A link 40 steadies the rod during its movements and a spring pawl 44 holds the disc during the return movement of the actuating mechanism. The picture change is masked by a shutter 46 pivoted on the standard 17 and held in both its open and closed position by a detent 50<1>, which consists of a spring-controlled lever pivoted at 51 and provided at its lower end with a spring-controlled pivoted extension 53. The detent is withdrawn at the beginning of the forward movement of the carriage by a tappet 57 to allow the shutter to close by its own weight and comes behind the rear side of the shutter as shown in Fig. 2. At the forward end of the movement, it is again released by the tappet 58, allowing a weighted or spring-pressed lever 47, which is freely pivoted on the standard 17 and is lifted by the upward movement of the picturechanging lever, to return the shutter to its open position with the detent bearing on its front edge. The expansion 53 allows the detent to pass the tappets 57, 58 on their rearward movement without being actuated. The shutter may have rows of apertures 46<1> to form a spot of light on the screen in .the closed position. Several projectors may be used together to form a complete design.