Patent GB-1479302-A (GB)
Title: Motion picture projector
IPC: G03B21/43
Filed: 1974-07-18
Abstract: 1479302 Projector film drive EASTMAN KODAK CO 18 July 1974 [25 July 1973] 31869/74 Heading G2E [Also in Division B8] A motion picture projector has film supply and take-up reels mounted on spindles, with mechanism for driving one or the other spindle for forward or rewind movement of the film, and braking means for both spindles so linked that, whichever way the film is moving, the braking effect is applied to the reel supplying the film before being applied to the reel taking up the film. As shown in Fig. 3, in the normal "project" mode, the film passes from reel 18 to reel 20, the reels rotating clockwise. Reel 18 is mounted on a spindle 16, which also has a hub 86. The mechanism can be set in various operational modes by moving a lever 30 to corresponding locations in a face plate (28) Figs. 1 and 2 (not shown). The manner in which lever 30 actuates control rod 72 and pivotable plate 56 to control reel 18 for "still", "project" or "rewind" modes is as described in Specification 1479303. Reel 20 is controlled by a lever 80 pivoting on a fixed pin 82. This is actuated by rod 72, one end 72e of which engages in a slot 88a in a bent-up end 88 of lever 80. Lever 80 carries a pressure wheel 84 which can be moved into engagement with hub 86, and also has a notch-like cam surface 80a. This notch co-operates with a pin 102 on a brake lever 90 which is spring-urged clockwise, and when the pin enters the notch, lever 90 pivots clockwise so that the brake pad 98 engages and brakes reel 20. When rod 72 is in the extreme left position in Fig. 3, lever 80 is moved to the position shown in full line, which is the "still" mode, in which reel 20 and drum 42, i.e. reel 18, are both braked. When rod 72 is moved to the central position, "project" mode, the brakes are disengaged from both reels, and the drive belt 54 drives hub 86, and hence reel 20, in the normal way. When lever 30 moves the mechanism back to the "still" mode, the arrangement is such that reel 18 is braked before reel 20, thus preventing "spilling" of the film between the two reels. When lever 30 moves rod 72 to the extreme right position in Fig. 3, "fast forward" mode, both brakes are disengaged, and lever 80 pivots so that pressure wheel 84 engages with hub 86. This produces a more positive drive than that produced merely by the weight of the reel and the film on spindle 16. When lever 30 is now moved back to the "still" mode, the two reels are again braked sequentially, as before. Fig. 4 shows, in broken line, the position of the mechanism when lever 30 and rod 72 are moved still further to the left past the extreme left position shown in Fig. 3. This is the "rewind" mode. Both brakes are again disengaged, and pressure wheel 84 is retracted from hub 86. The rewind drive is applied to drum 46, as described in Specification 1479303. When lever 30 is now moved back from this position to the "still" position, both reels are again braked, but now reel 20 is braked first, since this is now the supply reel. The placement of the stud 92 on which lever 90 pivots, brake pad 98 and reel 20 are such that there is a differential braking effect according to which way reel 20 is rotating. When it is rotating clockwise, "project" or "fast forward" modes, the spring acting on lever 90 is the only effective braking force. When it is rotating anti-clockwise, "rewind" mode, brake pad 98 tends to be urged or pulled by the flange of the reel into contact with itself, and the faster the reel is rotating the greater is this tendency.