GB1399263A - Tuning mechanisms for radio frequency tuners - Google Patents

Abstract

1399263 Radio tuners with fine tuning MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 19 June 1972 [18 June 1971 (4)] 28693/72 Heading H3Q [Also in Division F2] In a tuning mechanism for a radio frequency tuner including a rotor 26 for varying the tuning of the tuner, a control shaft 10, a gear train 20, 33, 25 and 34 between the shaft 10 and the rotor and a detent mechanism 16, 17, 18 to enable the shaft 10 to be positioned in a stepby-step fashion, a manually operable fine tuning shaft 11 provided with a cam 35 and a cam follower 37 associated with the cam moves the position of the rotary axis of one gear 25 of the train relative to the rotary axis of another gear 34 of the train so as to move the rotor 26 by planetary movement of one gear with respect to the other. In the T.V. tuner shown the shaft 10 drives via gears 20, 33, 25 and 34, the rotor 26 of a variable capacitor 27. The rotor 26 is moved in a step-by-step fashion due to the detent mechanism which includes a cam 16 and a ball 18 recessed in a spring 17. Anti-backlash gears 33 and 34 each consist of a pair of gearwheels 24, 29 spring loaded by a spring 32, 41. Fine tuning is obtained by rotating a sleeve 11 which rotates a cam 35. This moves a lever 37 so as to pivot a support lever 21 about the control shaft 10. The gears 33 and 25 are mounted on the support lever 21 so as to rotate in a planetary manner about the gears 20 and 34 to cause fine rotary adjustment of the rotor 26. The cam 35 is frictionally held in the adjusted position by a leaf-spring (60, Fig. 1, not shown).