GB439631A - Improvements in or relating to the production of photographic sound records - Google Patents

Abstract

439,631. Optical sound-recording and re-recording apparatus. KOLB, O. K., 39, Beverley Court, Wellesley Road, Chiswick, London. May 10, 1934, No. 14106. [Class 40 (ii)] An optical sound-recording or re-recording system is adapted to produce simultaneously two or more substantially identical records by means of a single electro-optical sound recording or re-recording instrument, such as a light valve or modulator, galvanometer or oscillograph system, which controls a plurality of light beams directed to and focused on the desired number of sound track spaces located on two or more separate or separable films each adapted to serve either as a negative for printing positives therefrom, or as a sound record film for direct sound reproduction. As shown, light from a source 10 passes through a lens system 11, apertures 12<a>, 12b in a mask 12 and a lens 13 on to an oscillograph mirror 7<a> which is actuated for direct recording purposes by currents from a microphone 27 and amplifier 6 or for re-recording purposes by currents from a photo-electric cell 5 influenced by a master film 1. The amplifier may be provided with known volume and tone correction devices. The light beams reflected from the mirror 7<a> pass again through the lens 13 causing images of the apertures 12<a>, 12b to be formed on the slit diaphragms 14, 15 arranged in front of lenses 16, 17. The divergent beams after being rendered parallel by double reflection in prisms 18, 19 fall on objective lens systems 20, 21 and are focused so as to produce images of the slits in diaphragms 14, 15 on the two half films 22, 23 which are combined in a single film strip 24 adapted to be divided ultimately along the centre line 24<a> and provided with two sets of sprocket feeding perforations 22<a>, 23<a> and with two sound tracks 22<b>, 23b. When the records are used as negatives, the perforations in the film serve to assist its passage through the positive printing and after processing devices before division of the film. A multiple series of cinematographic images can also be impressed on the film before the processing and division of such combined sound films is performed. According to a modification, two separate exciter lamps may be employed. An observation microscope system comprising a prism 25 and eyepiece 26 may be inserted in the path of one or other of the light beams 8<a>, 9<a>. The various optical elements may be separately and independently adjustable. Specification 393,610 is referred to.