Patent GB-492165-A (GB)
Title: Improvements in or relating to talking machines
IPC: G11B7/003
Filed: 1937-03-09
Abstract: 492,165. Sound - film apparatus. BRITISH OZAPHANE, Ltd. March 9, 1937, No. 6949. Convention date, March 9, 1936. [Class 40 (ii)] Relates to apparatus for reproducing sound from an endless transparent film having two oi more parallel sound tracks, and consists in the provision of film stopping means operated by a local thickening of the film at the end of the track, a selective light gate adapted to scan the tracks in succession, and a selecting device for automatically causing according to its setting either (1) reproduction from a single track with stoppage at end of track, or (2) reproduction from two or more tracks in succession with stoppage at end of last track, or (3) repeated reproduction from a single track. The local thickening of the film may consist of several layers of adhesive tape of leather, paper, regenerated cellulose, or opaque or transparent tissues coated with an adhesive such as rubber or copaiba gum. As shown, the film f, Fig. 5, is unwound from the centre of a coil 5, and after passing a sound gate 37 and over a fly-wheel 51 is returned to the outside of the coil. A plate 7 is provided to guide the film. The film is pressed against the fly-wheel by a roller 50 under the influence of a spring 57, Fig. 6. The roller is carried by an arm 49, pivoted about an axis 35. A prong 53 and a lever 55, forked at its inner end 56 to embrace the prong are attached to a collar 54 rotatably mounted on the axle of the roller 50 ; and a spring 66 normally urges the lever 55 in a clockwise direction to engage the prong 53 in a notch in a sector 47. This sector, which is attached to the gate 37 rotatably mounted on the axle 35, has four radial notches 62, two radial notches 63 preceded each by a slanting notch 63a, and a radial notch 64 preceded by three slanting notches 64a. In addition, the sector has ratchet teeth 65 adapted to be engaged by a pawl 58. A spring 59 urges the sector in the clockwise direction. A rod 60 attached to the sector carries a pointer 60a over a scale 15 concentric with the axle 35. The pawl 58 is normally disengaged from the ratchet teeth 65 and is controlled by a motor switch 18, which can be turned on in either of two positions, one for " discontinuous " operation and one for " continuous " operation, the pawl being put in engagement with the ratchet teeth 65, in the first position and out of engagement in the second position. If it is desired to play only one track only once, the lever 55 is moved to the off position 17 to release the sector 47, and this is then set for the desired track 1, 2, 3 or 4, as indicated by the pointer, after which the lever 55 is released to the influence of the spring 66 which makes the prong 53 engage one of the notches 62 corresponding to the selected track. The switch 18 is now turned to the " discontinuous " operation position, which causes the pawl 58 to be in engagement while the playing of the track proceeds. At the end of the track, the local thickening on the film passes between the fly-wheel 51 and the roller 50 causing the arm 49 and with it the sector 47 to rock about the axis 35, whereupon the pawl 58 slips on to the next ratchet tooth and prevents return of sector 47 and arm 49. The roller 50 is thus held away from the film, and reproduction stops. The same track may again be played by turning the switch off to release the pawl 58 and on again to restart the apparatus. If it is desired to play tracks 1, 2 or 3, 4 once in uninterrupted succession, the pointer 60a is set to the mark 1-2 or 3-4 on the scale 15 while the lever 55 and switch 18 are in the off position, then lever 55 is released to cause prong 53 to engage one of the slanting notches 63a, and the switch 18 is turned to the " discontinuous " operation position. The play of the first track proceeds and at the end of the track the sector 47 is rocked as before, and held by the pawl 58, but now the slanting notch 63a allows the prong to slip from the slanting notch 63a to the radial notch 63 and the arm 49 is free to rock back, so that roller 50 again presses on the film, and reproduction of the second track proceeds. At the end of the second track, however, prong 53 being in a radial notch 63, roller 50 cannot press again on the film and reproduction stops. Similarly, if it is desired to reproduce all four tracks in succession, the pointer 60a is placed at the mark 1-2-3-4 on the scale 15 to make the prong- 53 engage the first slanting notch 64a. Finally, if it is desired to play and repeat one track, the pointer 60a is put to the mark of the desired track on the scale 15 to make the prong 53 engage the corresponding notch 62 as mentioned above ; but in this case the switch 18 is turned to the " continuous operation position which puts the pawl 58 out of action and therefore allows the sector 47 and arm 49 to rock back after a temporary deflection by the passage of the thickened part of the film between the fly-wheel and the roller. The pressure of the roller on the film is thus maintained and reproduction is repeated. These mechanical devices may be replaced by equivalently acting electrically operated devices controlled by a switch actuated by the local thickening of the film. The sound gate 37 is in the form of a sector having ribs 39, Fig. 7, to support the film between the sound tracks, guiding flanges 38, and apertures 40, only one of which is shown, to allow the light coming from a source 44 through a condenser 43 to pass to the film and thence through an objective 45 to a selenium cell 14. The holes 40 are so disposed that in the several positions of the gate determined by the particular notch of the sector 47 engaged by the prong 53, light passes through the track selected for playing. Alternatively, apertures may be formed in a plate situated behind the film. The gate or plate in front or behind the film may have a set of holes r. Fig. 4, displaced longitudinally and laterally and corresponding to the tracks 1 2, 3, 4, the apertured member being adjustable lengthwise to bring one of the holes in line with a transverse slit t. Or the holes may be replaced by an oblique slot. The Specification as open to inspection under Sect. 91 described also a selenium cell, a circuit therefor, and an optical scanning device now constituting the subject-matter of Specification 492,087. This subject-matter does not appear in the Specification as accepted.