Improvements in or relating to the production of sound records and of synchronised sound and picture records bearing invisibly recorded sound signals

摘要

627,515. Magnetic sound-reproducing apparatus. KOLB, O. K., and PETERSEN, A. C. G. Oct. 30, 1946, No. 32276. [Class 40 (ii)] In a sound-reproducing apparatus in which the sound-track is invisible, as in a magnetic record, the signals are located by means of a visual indicating device in circuit with a reproducing head. The indicating device may take the form of a cathode-ray tube, and the signal may be rectified before being applied to the indicating device so that the resulting waveform follows the envelope of the soundwaves and thus corresponds to the amplitude only of the signals.