Improvements relating to the making of sound recordings

摘要

728,904. Embossing; feeding webs. TALKING DEVICES, Ltd. Jan. 23, 1953 [ Oct. 23, 1951], No. 24731/51. Classes 100 (1) and 100 (2). [Also in Groups V and XXXVIII]_ A method of making a hill-and-dale sound record on a plastic tape from a variable density sound film, comprises the production of a metal record on a plastic tape from a variable density die by means of a known photo-chemical etching process, and using the die to impress the plastic tape. The die forming a master record 21 is clamped to the periphery of a wheel 23, which is rotated by means of a motor 30, so that at each turn of the wheel 23 a duplicate of the recording is impressed on a plastic tape 26 drawn from a spool 27 onto another spool 28. The tape 26 is pressed against the wheel 23 by a roller 24 which is mounted on a bridge 25 pivoted on a shaft 40 and pulled down against the wheel 23 by a hydraulic ram 41. A further roller 55 presses the tape against a heated spring- loaded arcuate metal member 50. The wheel 23 contains electric heaters which are coupled to an electric supply by means of slip rings 37 and brushes 38. The steel die is made with a fishtail at one end and a point at the other end so that when arranged on the wheel 23, the ends engage each other in a manner which ensures their alignment. The resulting V-shaped mark which is impressed on the tape serves to indicate the start of each duplicate record. Guiding webs transversely. The tape is passed between four pairs of guide rollers 47, the lower roller of each pair being grooved to effect transverse guiding of the tape. Level winding on the spool 28 is effected by means of a transversely movable element 73, 74, Fig. 8, which moves on a carriage 72 under the control of a cam 77 rotated by a motor 78.