Improved method of optically reproducing or copying mechanically recorded vibrations by transmitted light

摘要

426,823. Photographic reproduction of sound-records. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Jan. 1, 1934, No. 83. Convention date, Jan. 3, 1933. [Class 98 (ii)] [See also Group XXXVIII] Relates to records of sound or like vibrations, on which the record track is made by cutting an opaque layer 6 on a carrier 1 by means of a vibrating tool 2, in such a manner that at least one of the edges of the track has a wedge-shaped cross-section. According to the invention, in order that the thinnest portion 4 of the wedge-shaped edge may be completely opaque to the rays used in reproduction or in copying by transmitted light, rays of one or more predetermined wavelengths or bands of wavelengths are chosen for the optical copying &c., and the layer 6 is treated with a dye or other suitable substance which absorbs the selected rays. The top layer may, for example, be treated with a " ruby spirit solution," to enable very actinic light free from yellow and green rays to be used for photographic copying. To render the film suitable for immediate sound-reproduction or for copying by means of the appropriate rays, a mixture of copper sulphate and aesculine may be used for the treatment of the opaque layer.