Patent GB-1192547-A (GB)
Title: Improvements in or relating to Push-Button Tuning Mechanisms
Inventor: BICKFORD IAN JAMES
IPC: H03J5/12
Filed: 1966-08-12
Abstract: 1,192,547. Push-button tuners. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 16 June, 1967 [12 Aug., 1966], No. 36208/66. Heading H3Q. [Also in Division F2] In a push-button tuner each button has a member which moves through a given distance and engages a second member, one of the members having a plurality of abutments spaced angularly about an axis and longitudinally with respect to the axis; one member is angularly adjustable and has a portion of regular polygonal shape which slidably engages a corresponding aperture to lock the member in a predetermined angular position and hence determine which abutment engages the other member. Fig. 1 shows one button of a television receiver in which the selection of the appropriate abutment automatically sets the wave-band and line-frequency standard for the station corresponding to that button. The button spindle 2 carries a nut 7 which operates a lever 8 for setting the tuning means in the usual way, the nut being axially adjustable by rotation of the button. The nut is preferably of plastic which grips the spindle to reduce the risk of accidental detuning. At the rear of the receiver the button shaft is polygonal and ends in a knob 37, the polygonal section carrying at its end a semi-circular rib 31. One abutment is formed by the surface of the rib at 31a and other abutments are formed by the ends of rods 28, 29, 30 projecting from the rib to unequal extents. These four abutments correspond, e.g. to four wavebands operating on 405 lines. Similarly (as seen in Fig. 2, not shown) there are three rods (32, 33, 34) on the opposite side of the axis which together with the other end (31b) of the rib 31 form four abutments corresponding to four wavebands operating on 625 lines. When the button is pressed in, one of these eight abutments will engage a spring-loaded switch bar, 17 common to all the buttons and move it through the appropriate distance to select the correct waveband for that button. The upper edge of the bar 17 has a pin-and-slot connection 25a with a bell-crank 25 pivoted at 23 and operating the waveband switch (not shown) through a pin 27. The line-frequency switch is operated through a plate 43 which slides transversely to the button spindle and is biased to one extreme position or the other. With no button pressed, a ridge 46 is urged upwards into the position shown, and will remain so if the button is adjusted to a 405-waveband. On the 605- wavebands the rib 31 will engage the ridge 46 and depress it, causing the other end 44 to operate the line-standard switch (not shown). If a second 605-button is now pressed, the rib 31 will hold the ridge 46 down before the latching mechanism 13, 14 releases the first button. For a single-system receiver only one set of abutments is provided on each button and the mechanism 43, 44, 46 is omitted. Adjustment of abutments.-The knob 37 is pushed in until its polygonal portion 35 becomes disengaged from the corresponding aperture 36 in the wall of the housing. The knob is then rotated to bring the appropriate abutment opposite the switch bar 17. On release, the knob is returned to its original position by a bifurcated leaf spring 42.