GB1376607A - Push-button control device for a radio or television tuner - Google Patents

Abstract

1376607 Push-button tuners PYE Ltd 17 March 1972 [29 April 1971] 12134/71 Heading H3Q [Also in Division H1] In a push-button control device for a radio or television varicap tuner with A.F.C. having a plurality of potentiometers 3 and a corresponding plurality of push-buttons 7, 8, each pushbutton has a first part 8 which, when the pushbutton is depressed, operates an associated switch for connecting the corresponding potentiometer into the tuning circuit of the tuner and co-operates with latching means 10-13 so as to be retained in the depressed position when the push-button is released and a second part 7 which operates A.F.C. cut-out means 20, 22 when the push-button is depressed and which returns to the undepressed position when the push-button is released, the A.F.C. cut-out means 20, 22 is operable by the second parts 7 of all the push-buttons and is arranged to remain in operation only while the second part 7 of one of the push-buttons remains in the depressed position and the second part 7 of each pushbutton also is rotatable to adjust the corresponding potentiometer to tune the tuner. When all the push-buttons 7, 8 are in their released position a pivoted plate 23 occupies the dotted position and the contacts 20, 22 of the A.F.C. cut-out switch 19 are open. When a push-button 7, 8 is pressed in as shown by 4c first the rear end 25 of the push-button moves the plate 23 about pivot pins 24 and closes the contact pin 22 on to spring blade contact 20 so as to short out the A.F.C. A cam surface 13 on outer sleeve 8 moves a locking bar to the right against the action of a spring to release any previously depresssed button and then a collar 9 closes a switch to switch the associated potentiometer into the tuning circuit. The locking bar now engages shoulder 14 to hold the sleeve 8 in. The fixed contact 20 is connected to the A.F.C. circuit and the movable contact is connected to a reference potential such as ground. On release of the pushbutton 4c the sleeve 8 is held in by the locking bar 10 and the rod 7 slides within the sleeve 8 and is returned by a spring 16 to its released position. This causes the plate 23 to move back to the dotted position so that the A.F.C. cut-out switch contacts 20, 22 open. Tuning adjustment can be made to the button which has been pressed by pressing in its rod 7 so that the plate 23 causes the A.F.C. cut-out switch contacts 20, 22 to close again. Then by rotating the rod 7 the spindle of the potentiometer 3 can be adjusted via gearing 25, 26. The wiper of the potentiometer is connected to a pin 3 which co-operates with a member 27 which is visible through a slot 24 at the front 5 of the tuner. Instead of the A.F.C. cut-out switch operating to short the A.F.C. it may be normally closed and arranged to open when the push-button is pressed so as to interrupt the A.F.C.