GB395369A - Improvements in or relating to sound records and systems for recording the same - Google Patents

Abstract

395,369. Photographic recording of sound. ROUND, H. J., Westfield, Muswell Hill, London. Jan. 12, 1932, No. 953. [Class 40 (ii).] Comprises a method of photographically recording sound upon a film by utilizing a plurality of record tracks of different fixed widths, sound below a predetermined volume being recorded upon a narrow track while sound exceeding this predetermined volume is recorded upon a wider track. More than two tracks may be employed and the resultant record is stated to minimize " background noise " when reproduced. Fig. 1 shows a record wherein weak sounds are recorded upon a narrow track 1 and sounds of more than a predetermined volume upon a wider track 2. Such a record may be recorded by an apparatus illustrated diagrammatically by Fig. 3, wherein light from a source A B, which is partially masked by a member C D, is focused by a lens L to give an image B<1> D<1> upon a moving photographic film F. A shutter S S may be interposed into the path of the light beam to reduce the effective width thereof so that the edge of the image photographed on the film F is transposed to S<1> and recording effected on a relatively 'narrow-width track. The shutter may be moved automatically at a definite rate under the control,of the sound being recorded. Fig. 2 shows a recording effected in three separate tracks 1, 2, 3. The variable density method of recording may be employed when it is arranged that the light source shall be weakened on changing over to a wider track in order to avoid a disproportionate increase in the recorded sound intensity. Specification 394,328 is referred to.