Patent GB-505095-A (GB)
Title: Improvements in or relating to apparatus for guiding and driving picture-sound filmsor sound films
IPC: G03B31/02
Filed: 1937-11-03
Abstract: 505,095. Sound-film speed-controlling devices. KLANGFILM GES. Nov. 3, 1937, Nos. 30113, 30114, and 30115. Convention dates, Nov. 3, 1936, Jan. 27, 1937, and Feb. 16, 1937. [Class 40 (ii)] [Also in Group XX] In sound-film apparatus having a spring actuated film straining roller, the movement of the latter on starting the apparatus increases the friction between the film and the smooth roller driven by the film, either by influencing means, other than the said spring, determining the bearing pressure of' the film on the smooth roller, or by supplying an additional drive to the smooth roller; on stopping the apparatus the straining roller moves means determining the bearing pressure, or supplies an additional braking effect to stop the smooth roller. As shown in Fig. 1, the film 2 fed by a sprocket 3 is held against the smooth roller 1 by a pressure roller 4 and passes over a straining roller 6 on a pivoted lever 9 held by a spring 7. On starting the apparatus the lever 9 moves in a clockwise direction so that the end 11 thereof engages a leaf spring 12 to increase the pressure of the roller 4 on the film. On stopping the apparatus the arm 11 engages a nose 16 to relieve the pressure on the film. In a modification the spring 5 is connected to the end 11 of the lever 9, the spring 12 being omitted. In a further modification shown in Fig. 4, a friction brake 21, 23 is electrically controlled by the roller 6 so that on starting the latter moves in the direction of the arrow 24 to reduce the resistance 30 and to cause a solenoid 28 to attract an armature 27 to increase the pressure on the film. Alternatively the brake may be mechanically operated by means of a cam from the roller 6 or the brake may comprise two smooth rollers between which the film passes and one of which is braked either by mechanical or electrical transmission from the roller 6. To impart an additional drive the apparatus shown in Fig. 6 may be employed. The lever 49 bearing the straining roller 6 carries also a driven sprocket 43 having a roller 47 engaging a resilient roller 48 to drive the latter. On starting, the lever rotates to bring the roller 48 into engagement with a roller connected to the sound roller 1 to impart an additional drive. The roller 6 may, in a modification, be on a separate lever and in a further modification the roller 48 is driven by a belt from the sprocket 43 and directly presses the film on the roller 1. In another arrangement the shaft at the roller 1 is coaxial with but not connected to that of the driven sprocket 43, and on starting the movement of the roller 6 brings a resilient roller into engagement with friction wheels on the two shafts to impart a drive to the roller 1. In the apparatus shown in Fig. 10 the sprockets 43, 3 are driven by a motor 64 which also drives an electro magnet 67 adjacent the flywheel 47 of the roller 1, the magnet being in circuit with a sliding contact on the roller 6. On starting, the roller 6 moves the contact - to energize the magnet which thereby drives the flywheel. In a modification, on starting the roller 6 moves to close a switch starting an auxiliary motor which is switched off on attaining, normal speed, and on stopping the roller operates a switch to connect a load to the flywheel to stop rotation. The Specification as open 'to inspection under'Sect. 91 describes also an arrangement in which the flywheel shaft is connected to the coaxial rotor of an electric motor, and a manually operated switch is described which in its first position switches on the main drive motor and the auxiliary flywheel motor, in its second position disconnects the auxiliary motor, and in its third position disconnects the main motor and connects the auxiliary motor to a load to stop rotation. The Specification also describes arrangements wherein the straining roller is maintained in its normal position until the sound roller has attained its speed and is then released manually. As shown in Fig. 16 (Cancelled) manual pressure on a lever 117 causes a locking lever 111 to engage the pivoted lever 113 of the roller 6 to hold it, and also presses a pressure roller 115 against the sound roller 1. The driving motor is then started and when the roller 1 has attained its appropriate speed the lever 117 is released to unlock the lever 113. In a modification the transmission of movement from the lever 117 is effected by cords. To ensure even running of the film the apparatus shown in Fig. 18 (Cancelled) may be employed. The film 2 is held by a roller 127 against a roller 125 having a disc 129 pressed by a spring against a friction block 130 so that as the tension in the film increases the roller 125 is raised to reduce the friction effect of the block 130 and vice versa as the tension slackens. This subject-matter does not appear in the Specification as accepted.