| 摘要 |
1,243,638. Mechanical switches without quick action; variable resistors. INTERNATIONAL STANDARD ELECTRIC CORP. 19 Dec., 1968 [27 Dec., 1967], No. 60319/68. Headings H1N and H1S. [Also in Division H3] A selector switch including a manual control knob 2 having a plurality of switching positions has a plurality of circuit elements 3, 4 spaced apart in the direction of movement of the knob 2, one for each switch position, and an adjustment member 15 which is operable into and out of engagement with an adjuster 20, 14 of the selected circuit element 3, 4 so that the impedance of the selected one of the pre-set circuits 3, 4 can be altered. As shown the selector is for a television or radio receiver having an oscillating circuit tuned by a varactor diode. Variable potentiometers 3, 4 provide pre-set tuning voltages for the varactor diode for VHF and UHF bands via changeover contacts 11, 33 to 40, The contacts 33, 39, 40 are resilient and contacts 11, 34 to 38 are printed circuit type. The selected position of the selector switch 1 is obtained by star type or as shown ball 41, 42 location. Adjustment of pre-set potentiometers is obtained by pressing tuning knob 15 downwards until the bevel gear 17 engages bevel gear 14 and adjusts slider 10 of one of the UHF potentiometers 4. A pin 18 positively locates the gears 17, 14 during adjustment. By rotating the selector switch 1 so that gear 17 is over one of the potentiometers 3, on pressing down the tuning knob 15 the bevel gear 17 engages internal gear 21 of the rotor 20 of this potentiometer which can now be adjusted. Construction of potentiometers.-The potentiometers 4 have sliders 10 and resistance tracks 7 of carbon or graphite printed on a resin-bondedpaper board 6. The potentiometers 3 have slide springs 22 and resistance ring tracks 23. In a modification of the potentiometers 3 (Figs. 3, 3a, 3b, not shown), the rotors 20 may be in the form of hubs (26) with spring blades (27, 28) riveted at each end of the hub so as to engage the printed contact 11 and carbon or graphite layer (25) on opposite sides of the board 6. Alternatively the spring blades (27, 28) may be S-shaped and with the central part through a hole in the hub (26). In a further modification (Fig. 4 and 4a, not shown), with the spring blades (27, 28) contact 11 and a resistance layer (31) punched out as carbon coated hard paper segments the blades (27, 28) are resilient circular shaped flat springs. Dial indicators with pointers may be coupled to the drive spindle of the UHF potentiometers 4 and indication for VHF may be obtained by marking with the associated channel numbers. |
