Patent GB-214274-A (GB)
Title: Improvements in apparatus for recording and reproducing sound
IPC: G11B13/00
Filed: 1924-04-12
Abstract: 214,274. Robertson, J. R. April 12, 1923, [Convention date]. Optical apparatus; electric and magnetic apparatus; records, combined phonograph and kinematograph.-Two separate sound records, which are produced together on film, and are adapted to be reproduced simultaneously are obtained, the one by using a vacuum discharge tube to record the sound photographically, and the other by means of electromagnets adapted to make a magnetic record on a prepared strip on the film, the two recording devices being electrically connected. Alternatively, a second photographic record may be made instead of a magnetic record, by using two vacuum tubes. The records may be made on the edges of a kinematograph film, to produce " talking pictures." The invention also comprises an apparatus for reproducing sound from a photographic film record, in which a source of light, regeneratively controlled by the moving record, is employed. Figs. 3 and 4 show an optical recording apparatus in which vacuum tubes f are mounted in pockets n in a hinged casing j which surrounds a uniformly-moving part of the film. A kinematograph camera is arranged, beyond the sprocket-wheels around which the film is looped. The vacuum tubes are filled with rarefied gas, each end of the tube being metalcoated and wound with a small copper coil g. The tubes, which are connected in series or parallel, or inductively through a small transformer, are connected to a telephonic or other soundtransmitter either directly or through an amplifier. A pulsating glow is thus set up in each tube, the light passing through a slit or a lens, and illuminating only a narrow portion on each edge of the film. The vacuum tube may be entirely coated with a metal deposit in which a slit is formed. The reproducing-apparatus for use with a film bearing two photographic records is shown in Fig. 5. The record film passes between a pair of photo-electric cells 9 on one side and lamps 6 on the other side, which lamps may emit ultra-violet rays, or may be incandescent filament lamps, supplied from a battery 7. The cells 9 are connected to an amplifier 11. which is coupled through a transformer 12 to loud-speakers 13, a battery 14 being connected as shown. To each loud-speaker may be connected, through a relay if necessary, a tube 16 of rarefied gas such as helium, argon, neon, or mixtures thereof, with the object of producing colour effects which vary with the sounds reproduced. Such lamps may be arranged behind stage scenery. The amplified electric impulses caused by the cells 9 may be fed back to the lamps 6 through leads 17, so that the fluctuations created in the sound-reproducing circuit rageneratively modulate the intensity of the emitted light. The recording apparatus may be used to record speech and music transmitted by wireless, by connecting the apparatus in circuit with a wireless receiver. Specification 157,440 is referred to. The Specification, as open to inspection under Sect. 91 (3) (a), comprises also the following subject-matter, which does not appear in the Specification as accepted. In the preparation of " talking pictures," separate films may be used for making the sound and picture records respectively, these films being moved synchronously in the recording-apparatus, and the positives produced therefrom being run through the reproducer similarly, or cemented together to form a single combined record. The separate films can receive special individual photographic treatment. The vacuum tubes used may contain neon. A number of recorders and transmitters may be employed, the latter being variously proportioned and tuned so as to respond to different frequencies, and in the reproducing-apparatus the loud-speakers are variously proportioned and tuned. " An attuned comb," responsive to certain musical sounds, may be used in connection with the loud-spaakers. Various kinds of transmitting apparatus, used in making the sound records, are also described and shown.