Patent GB-1532689-A (GB)
Title: Optical projector
IPC: G03B23/18
Filed: 1976-06-10
Abstract: 1532689 Optical projectors FRANKE & HEIDECKE GmbH [trading as ROLLEI-WERKE FRANKE & HEIDECKE] 10 June 1976 [24 Sept 1975] 24031/76 Heading G2J A double slide projector consisting of a pair of projectors (not shown) with a common magazine 1 having indexing means, slides being taken successively from the magazine for projection in the projectors alternately and subsequent return to the magazine in correct order, in which contrarotating gears 18, 19 perform a full or half rotation during each slide change and carry circumferentially-spaced projections which drive a Maltesecross mechanism 4, the arrangement being such that the magazine 1 is moved in steps in one direction by projections 12, 13, 12 , 13' on gear 18 and in the other direction by projections 14, 14' on gear 19. There may be projections 12, 13, 14 only, in which case the gears make one revolution for each indexing cycle, but it is preferred to use two sets of projections placed 180 degrees apart on the gears, so that they make half a revolution for each indexing cycle. In each cycle the magazine 1 is moved two steps forward and one step back. Indexing mechanism. As shown in Figs. 1 and 2, the gears 18, 19 are mounted co-axially and are driven in contra-rotation by an electric motor 43 through gearing 36, 39, 37, 40. Pins 12, 13, 12', 13' are mounted on the rim of gear 18 and operate a Maltese-cross mechanism 4. This drives gears 8, 9 fast with sprockets 10, 11 which engage rack teeth 2 on magazine 1, which is moved two steps. Pin 14 moving in the other direction operates the Maltese-cross mechanism to move the magazine 1 back one step. After a further half-revolution, pins 12', 13', 14' operate in like manner. Stop lever 23 has projections 25 which are normally held clear of magazine 1 by a wheel 24 riding on the rim of gear 18. When indexing is complete, wheel 24 runs into a cut-out 26 or 26' in the rim, and projections 25 engage further teeth 3 on magazine 1 to hold it against movement until the next indexing operation. Stop key 33. To interrupt projection, key 33 is depressed to actuate lever 23 by an arm 27 to hold magazine as above. At the same time an electrical switch 49 is operated to stop operation and to de-energize the projection lamps. Projection. The magazine 1 is moved to the position shown in Fig. 3, with sprocket 10 engaging rack teeth 2 and sprocket 11 and projections 25 disengaged. When motor 43 is energized, the magazine 1 moves back one step and forward two steps, after which the compartment 1 is opposite a holder 52 for a feed claw (not shown) which moves the slide 1 to one of the projection gates, I. The projection lamp is brightened. After one step back and two forward, slide 2 is moved to projection gate II, the lamp for this gate being off. The lamps are then dimmed and brightened. The magazine moves back one step to enable slide 1 to be returned to its proper compartment from projection gate I, and then moves two steps forward to enable slide 3 to be moved to projection gate I. This process continues until all the slides have been projected. Magazine 1 is moved to its final position by sprocket 11, sprocket 10 being disengaged Fig. 4 (not shown). Reverse projection. By pressing a "reverse" key the slides may be projected in reverse order. The pins 15, 15' engage slots 16, 16' in the rim of gear 18 so that on reversal, lost motion allows the omission of one step.