Patent GB-1192090-A (GB)
Title: Improved Push-Button Channel Selecting Units for Multiband Receivers
Inventor: PREH WALTER
IPC: H03J1/06
Filed: 1968-02-01
Abstract: 1,192,090. Push-button tuning. W. PREH [trading as PREH ELEKTROFEINMECHANISCHE WERKE JAKOB PREH NACHFOLGER]. 1 Feb., 1968 [18 Feb., 1967; 4 March, 1967; 14 March, 1967], No. 5289/68. Heading H3Q. [Also in Division H1] Each button in a push-button tuner has three positions: (a) inoperative, (b) rotatable to adjust the waveband switch, and (c) operative for channel selection and fine tuning and simultaneously to display the appropriate scale bearing the number of the selected channel, e.g. in a television receiver. Fig. 1 shows a button in the inoperative position. To switch in a desired channel the appropriate button is pressed in (Fig. 3, not shown) so that a loop 13a of a bent spring contact 13 makes contact with a screwed spindle 6 of a voltage divider (not shown) which applies a voltage to a varicap diode for tuning. The energizing voltage for the voltage divider is obtained from a bar 23 which extends perpendicularly to the axes of the buttons. The button is latched in by a conventional locking bar 11 which engages a cross-piece (9b in Fig. 11, not shown) on a switching element 9 inside the button, The element 9 also carries a segment (9e in Fig. 11, not shown) which engages a recess 19b in a control element 19 and shifts the latter to the right to engage by means of part 19c a flap 20 common to all the buttons. This flap moves a switch slide 22 to perform the necessary switching operations for the appropriate waveband. Fine tuning.-When the button is pressed in, longitudinal pins (15b in Fig. 15, not shown) on a coupling piece 15 are urged by a spring 16 to engage corresponding recesses in a bevel gear 8 which meshes with another bevel gear 5 on the spindle 6. Rotation of the button causes the pins on the coupling piece 15 to snap into the recesses m the gear 8 and also into recesses (14b in Fig. 7, not shown) on the inside of the button. Further rotation of the button then turns the spindle 6 and moves a slider on a voltage divider (not shown) to alter the voltage supplied to the varicap diode. Waveband changing.-The button is pulled out (Fig. 2, not shown) to cause external teeth on the button to engage internal teeth 18b of an element having two arms 18c and 18d. Rotation of the button now turns these, and the arm 18c carries a pin (18e in Fig. 13, not shown) which co-operates with studs 2b to set the element in one of three possible angular positions. Rotation of the element carries with it the control element 19, which thus engages the flap 20 in one of three positions on the latter. These positions are recessed differently (Fig. 4, not shown) so that the flap 20 and slide 22 are moved by different amounts depending on the angular setting of the button. Instead of one flap there may be two flaps performing separate switching functions (Fig. 5, not shown) the element 19 operating, according to its position, one, both or none of these flaps. The latter may perform electronic band-switching by means of diodes. Alternative waveband switching.-The elements 18 and 19 may be replaced by a rotor 28 (Fig. 22) having teeth (28b in Fig. 21, not shown) which engage the external teeth on the button. The rotor 28 carries a contact 29c which engages concave contacts (e.g. 35a in Fig. 19), and a further contact on a bent arm 29a which connects with one of the bars 30, 31, 32 (Fig. 19) according to the angular position of the rotor 28. These bars energize solenoids to perform band-switching. If the solenoids are pulse-operated they are supplied via a further switch 38, 39 which is closed by the locking bar 11 (Fig. 1) for a short time during channel switching. The contacts (e.g. 35a) may be made in one piece and inserted in grooves in the frame, and may have depressions to locate the rotor 28 in the correct positions. Alternatively the contacts may be made as printed conductive lines on an insulating plate. Channel indication.-Associated with each button is a window (Fig. 26, not shown) through which one of a number of slides can be seen. Each slide bears the numbers of adjacent channels and a censor coupled to the slider of the corresponding voltage divider indicates the particular channel to which the receiver is tuned. Fig. 25 shows windows 45, 46, 47 for three buttons, with slides 42, 43, 44 overlapping in tile-fashion and slidable sideways as the waveband is changed. The cursors 48, 49, 50 move at right angles to the plane of the paper. A slot in each slide (d in Fig. 23, not shown) is engaged by an arm 18d (Fig. 1) or 28d (Fig. 22) so that the slide is moved sideways when the waveband is changed.