Doppelkontroll-Drehknopf,beispielsweise fuer Rundfunk- und Fernsehempfaenger

1,180,939. Tuning controls. USM CORP. 22 May, 1967 [23 May, 1966], No. 23610/67. Heading H3Q. [Also in Division F2] In a fine control knob assembly for manually rotating a shaft 24, for example in a radio or television set, a tubular flexspline 28 has a tubular portion 26 secured to the shaft 24 and internal teeth 36 which are caused to mesh at spaced points with external teeth 38 formed on a circular member 14 which is prevented from rotating freely with respect to a chassis 10 by a friction brake consisting of a ring 16 and spring washer 18. The meshing is effected by a wave generator surface 34 in the shape of an ellipsoid formed within a fine adjusting knob 32. The number of teeth 36 on the flexspline 28 exceeds that of teeth 38 by two, or a multiple thereof. On rotation of fine control knob 32 relatively slow rotation of shaft 24 is effected, the member 14 remaining stationary. For coarse adjustment of shaft 24 a knob 30 secured thereto is rotated; the brake 16, 18 then slipping. In a modification, a fine control knob 52, Fig. 3, acts through a flexspline 50, and a coarse control knob 62 incorporates a circular arrangement of teeth 60 and a brake 64, 66.