Patent GB-1339122-A (GB)
Title: Slot-load m otion-picture projector
IPC: G03B1/56
Filed: 1972-04-27
Abstract: 1339122 Cinematography GRAFLEX Inc 27 April 1972 [24 May 1971] 19579/72 Heading G2E A cine projection including a slot (11), Fig.1 (not shown) for edgewise insertion of a film has a control lever 20 movable between a loading position Fig.5 and a forward projection position Fig. 6 through an intermediate reverse projection position. Movement from the load to a projection position closes film gate 18, creates film loops between the sprocket 16 and gate 18 and between the sound drum 19 and sprocket 17. Film Threading The apparatus is placed in the position shown in Fig.5 with the lever in its lower position and the rewind lever 106 in either of the positions shown in Fig.5, 6. The film is manually inserted in the slot (11) so that is passes between rollers 43 and sprocket 16, through opened gate 18, between rollers 86, 71 and sound drum 19, around roller 75 and between rollers 76 and sprocket 17. Movement of the levers 106, 20 to the Fig.6 position closes the gate 18, holds the film in contact with the drum 19 and sprockets 16, 17 and produces the said film loops. The gate is moved by means of levers 22, 23 connected to the lever 20 which slide a bar 25 linked to the gate 18 by a toggle arrangement 37, 38. Elements 27, 28 are respectively engaged by pins 29, 30 on the lever 23 and ensure that the bar 25 (and hence the gate 18) is moved rapidly to its open or closed positions in the initial part of the respective movements of the lever 20. A pin 46 and slot 47 link causes the rollers 43 to be moved relative to the sprocket 16 simultaneously with movement of the gate 18. A pin 73 carried by plate 72 engages slot 74 in the lever 20. As the lever 20 is raised the plate 72 turns on pin 65 lifting arm 79, pivoted to the plate 72 at 80, and pushes the rollers 76 about the sprocket 17. The film which was threaded about roller 75 thereby forms a film loop. The other film loop is formed after the early closing of the rollers 43 about the sprocket 16 to ensure that a spring motor in the sprocket 16 Fig.9 efficiently advances the film to provide the loop. The spring motor is a spring 50 attached to the shaft 48, which is electrically driven during projection and rewind, and pin 51 on the sprocket. The spring 50 is tensioned by movement of the lever 20 from its projection to load position. This causes cable 55 to rotate drum 54 and tighten a wrap spring clutch 56 (by the abuttal of surface 68 and spring end 66) so that the rotation of the drum 54 is transmitted to the sprocket 16 to wind up the spring 50. Movement of the lever 20 to a projection position from the load position thus causes the rapid closing of the gate 18 and roolers 43 about the sprocket 16 followed by the anticlockwise rotation of the drum 54 which releases the clutch 56 and permits the spring 50 to drive the sprocket 16 anti-clockwise to create a film loop between the gate 18 and sprocket 16. During forward projection the spring 50 may also absorb tension in the film between the supply reel and gate by modifying the anti-clockwise rotation of the shaft 48. Reverse winding The lever 20 has an intermediate reverse projection position. Compared with the forward projection position Fig. 6 pin 73 still retains the same position in the slot 74 but moves down the slot 87 on to the adjacent projection to rotate the plate 84 about pin 85 so that roller 86 is moved away from the sound drum 19 to its Fig.5 position. Also plate 72 is slightly rotated so that roller 71 moves upwards and a cam plate (88), Fig.12 (not shown), coaxially mounted with plate 72 on pin 65 is rotated, so switching the projector motor into reverse. Rewinding To rewind the film after projection lever 20 is placed in the load position and a rewind lever 106 placed as shown in Fig.5. Movement of the lever 106 into this position lowers pulley 60 which slackens cable 55 thereby releasing the spring motor 50. The plate 124 and pulley 60 acts as interlocks so that in the Fig.5 position the lever 20 cannot be raised until the lever 106 is moved to the right because the pulley 60 prevents the plate 124 moving to close the gate 18 and in the Fig.6 position the lever 106 cannot move to the left till the lever 20 is lowered because the plate 124 blocks the lowering of the pulley 60. Movement of the lever 20 to its load position sufficiently rotates the cam (88) to set the motor in reverse and extinguish the lamp. Spool drives and brakes As shown in Fig.13, the take-up reel is driven by pulley 93 and belt 94, a wrap spring 96 acting on brake drum 95 to prevent reverse movement of the take-up reel except when solenoid 99 is energized during reverse projection and rewind. The supply reel is powered by pulley 101 and belt 102 which is connected to a driven gear 134 by clutch 103. The clutch 103 is engaged by activating the solenoid 99. In reverse projection the gear 134 is powered by a slip drive provided by a wrap spring (130), Fig.14, 15 (not shown), but in rewind the movement of lever 106 presses a paddle (136), Fig.14 (not shown) which causes the gear 134 to be directly driven by by-passing the wrap spring (130).