Patent GB-937812-A (GB)
Title: Improvements in channel selectors for television receivers
Inventor: MARLOW KEITH HENRY
IPC: H03J1/04
Filed: 1960-05-12
Abstract: 937,812. Television receiver channel selector arrangements; adjusting radio tuning controls. FERGUSON RADIO CORPORATION Ltd. May 12, 1960, No. 16842/60. Class 40 (5). A channel selector for television receivers comprises a frequency tuner having an angularly movable member adjustable into a plurality of frequency setting positions, a spring-loaded indexing mechanism, release means for removing or reducing the spring loading of the indexing mechanism on the tuner member to permit angular movement of the latter, and a control element movable along a scale and coupled to the tuner member by cable drive means to effect angular movement of the tuner member into any selected one of its setting positions in response to movement of the control element along the scale. The channel selector comprises a back-plate 10, tuner unit 11, a channel control member 13 and spring-loaded indexing mechanism 15 together with a fine-tuning control 16. A release bar 35 together with levers 36, 38 are pivotally mounted to bracket 42 about a common axis passing through pivot pins 40, 41. Two springs 43 and 45 act on the release bar, the former forming a toggle with lever 38 and having a dead-centre position and the latter being located in an aperture in the back-plate and arranged to bias the release bar into its forward position when the spring toggle is urging the release bar towards its rear position. The indexing mechanism, Fig. 2, comprises lever 49 pivotally connected to bracket 50; one end of the lever carrying a roller 51 arranged to roll on cam ring 24 and the other end engaging within a slot in the rear end of a link 53 which is pivotally connected to the flange 48 of lever 38, Fig. 1. Thus forward and rearward movement of the release bar about its axis effects movement of the roller 51 towards and away from the edge of the cam-ring 24, respectively; the spring toggle reinforcing the action of spring 45 in urging the roller 51 towards the cam ring when the roller is engaged in a notch, but acting against spring 45 when the release bar is moved rearwardly in order to disengage the roller, so that only a light pressure is needed to hold the release bar in its rear position. Hence any desired channel may be selected by pressing the control member 13 and sliding the latter along the scale bar 14 so as to rotate the tuner disc by the cable 23. Fine tuning control.-The fine tuning control comprises gear-wheel 56 mounted on lever 57, having a detent 59 projecting towards the tuner, and a coil spring 58 compressed between the lever 57 and an abutment on the back-plate 10; the lever and spring forming a spring toggle having a dead centre position so that spring 58 biases the gear-wheel 56 towards gear-wheel 29 of the tuner when the two are in mesh and away from the gear-wheel when the two are out of mesh. To obtain fine tuning the lever 57 is pivoted into its engaged position by hand pressure on handle 62 to move the gear-wheels into mesh, the detent 59 projecting between the cam projections 26, thus fixing the position of the cam pins 31 which engage with cam follower 61 of lever 60, the latter being biased by a spring against the cam pins 31 and connected to a tuning device in the housing. On rotating the tuner disc 17 the lever 57 is thrown into its disengaged position by the cam projections 26 engaging the detent 59.