Patent GB-479172-A (GB)
Title: Improvements in dial mechanisms
IPC: H03J1/06
Filed: 1937-04-09
Abstract: 479,172. Adjusting wireless apparatus. BURGESS, A. F. (Zenith Radio Corporation) April 9, 1937, No. 10140. [Class 37] [Also in Group XIX] A dial co-operating with an indicator is formed of a plurality of complemental sections relatively and simultaneously movable into and out of the display position by an adjusting element. Preferably a plurality of dials for co-operation with one pointer are provided each in a plurality of sections, the adjustable element upon successive manipulations effecting movement of the dials to the display position successively. The invention is described as applied to a radio receiver covering three wave ranges but is applicable also to a meter which by manipulation of a switch is adjustable to measure amperes, volts and watts. As shown the tuning knob 24 drives the tuning condenser shaft 4, Figs. 1, 2, through shaft 21, belt 19, pulley 12 rigid with a pinion 11, and gearing 7, 6, 5. A pinion 8 rigid with gear 7 drives through gear 17 and sleeve 14 a slow pointer 18 which co-operates with one of three dials 37, 39, 40 according to the position of the wave range switch 63, and a fast pointer 15 driven by shaft 13 rigid with pinion 11, co-operates with a fixed scale 36 on the opaque portion 33 of a glass face 25 to indicate fine adjustments of the slow pointer 18 on all wave ranges. The dial 37 is fixed but the intermediate dial 39 and front dial 40 each consist of two movable sections. The sections of dial 40, Fig. 5, are mounted on arms 43, 44 pivoted, respectively at 31, 30, and biassed by springs 55, 56 to the inoperative position shown, the arms being connected by a link 51 so that they open and close scissorslike when the arm 44 is rocked through its extension 71. The intermediate dial sections 39 are likewise carried on interlinked arms 41, 42 pivoted at 31, 30 respectively and actuated through an extension 70 of lever 42, in opposition to springs 53, 54. The wave range switch 63 has a crank 67 mounted on the shaft 62 thereof the crank moving between the extensions 71, 70 and having pins 68, 69 on opposite sides thereof for co-operation with the extensions. Thus, in one terminal position A, Fig. 5, of the wave range switch, both movable dials are retracted to their inoperative positions by their springs, the pointer 18 being read against the frequency graduations on the fixed dial 37. In the middle position B, the pin 69 on the crank 67 has rocked the extension 70 to close the portions of dial 39, Fig. 1, to obscure the dial 37 while in the other terminal position C of the wave range switch the extension 71 is rocked by pin 68 on the crank to bring dial 40 into operative position, the dial 39 also remaining in the position shown in Fig. 1 but being obscured by dial 40. The operative wave range is displayed through an aperature 35 in the opaque portion 33 of the face 25 by the letters A, B, C on a disc 66 mounted on spindle 62. In a modification, Figs. 7, 8 (not shown), the wave range control knob is mounted coaxially with the tuning spindle and the biassing springs move the sections to the operative positions when permitted by the crank the wave range control knob.