GB357994A - Improvements in or relating to apparatus for recording or reproducing sound - Google Patents

Abstract

357,994. Optical sound recording or reproducing apparatus. STOCKS, H. B., 103, Cornwall Road, South Tottenham, London. March 28, 1930, No. 9992. [Class 40 (ii).] In optical sound recording or reproducing apparatus, a light slit is formed by the space between adjacent edges of two rings which rotate close to each other, means being preferably provided for cleaning the edges automatically, to keep the slit free from dust &c. The invention is shown as applied to sound-reproducing apparatus, in which light from a lamp 9 passes through a record film 16 on to a photo-electric cell 10. The lamp is placed within an apertured casing 1 on which are mounted rings 5, 6. These have closely adjacent edges 5a, 6a between which the light passes before reaching the film 16. The rings are adjustably mounted on ball bearings 12, and are rotated by suitable mechanism, such as friction rollers on a spindle 11 driven from a kinematograph. Cleaning pads carried by a spring blade 14 engage the edges of the rings as shown. The rings are preferably arranged horizontally and eccentrically to each other, and in the construction shown they rotate at different speeds. They may be made of stainless steel. Light from the lamp 9 may be concentrated on the aperture between the rings by a lens, or by a mirror, preferably made of nickel chromium steel. Instead of arranging a lamp inside the rings, a source of light outside the rings may be used. For this purpose light from the arc light of the projector itself may be suitably directed by mirrors, prisms, or lenses. Instead of rigid circular rings, travelling endless flexible bands may be employed to form the light. slit.