US2251612A - Tuning dial - Google Patents

Description

Aug. 5., 1941.

E. E. KOHLS El' AL TUNNG DIAL,

Filed Feb. 16. 1938 2 Sheets-Sheet l gm@ ffm/5 5/57/7/7 5. 7770/27 pa, SM

gsm w Aug. 5, 1941. E. E. KoHLs Erm.

TUNING DIAL Filed Feb. 16, 1938 2 Smets-sheet 2 @an LN @www mim.

GOEE@ mm Patented Aug. 5, 1941 TUNING DIAL Erich Eugene Kohls and Glenn S. Thompson, Fairy Chasm, Wis., assignors to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware .fipplication February 16, 1938; Serial No. 190,803

(Cl. lli-)` 2 Claims.

This invention relates to'improvements in radio tuning dials, and refers particularly to .so-called automatic tuning for radio receivers whereby a receiver may be quickly and accurately tuned to any one of a number of predetermined different broadcasting stations.

Tuning devices of this character, except those which are driven by electric motors, generally comprise a rotatable element directly connected with the condenser shaft and provided with a plurality of station selecting elements in the form of movable stops, each adapted to arrestmotion of the rotatable element at a deiinite point to tune the receiver to a predetermined broadcasting station.

These individual station selecting elements or stops are adjustable to permit each one tc be used for one of a number of broadcasting stations lying in adjacent channels.

Heretofore the adjustment of these individual station selecting elements or stops has been diflicult and required the services of an expert. In addition, their design was such that adjustment had to be made from in back of the panel or entailed at least partial dismantling of the mechanism.

it is therefore an object of this invention to provide a radio tuning device of the so-called automatic type which is so designed that adjustment of its individual station selecting elements or stops may be quickly and easily effected and does not require the services of an expert.

Another object of this invention is to provide a tuning device of the character described Wherein adjustment of the individual station selecting elements may be effected entirely from in front of the panel and without the necessity for dismantling the mechanism.

A further object of this invention is to provide greater accuracy for tuning devices of the character described by improving the construction of the individual station-selecting elements.

With the above and other objects in View which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come Within the scope ofthe claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with v Il which is joined to a large pulley i2 positioned the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a front plan view of a tuning device embodying this invention;

Figure 2 is a longitudinal sectional view through the tuning device illustrating its application to a radio receiver chassis;.

Figure 3 is a sectional view taken through Fig- -ure 2 on the plane of the line 3 3 with parts '.brokenaway;

ving drawings in which like numerals indicate like parts, the numeral 5 designates the chassis of a radio receiver equipped with tuning condensers 6 from which a condenser shaft l projects forwardiy toward the panel 8 of the cabinet in which the receiver is mounted. The panel is provided with the customary opening to accommodate the dial assembly indicated generally by the numeral 9. This assembly includes a glass covered dial proper indicated by the numeral i0, which is assembled with the condenser shaft and is equipped with the customary indicia and pointer for indicating the Wave length to which the receiver is adjusted.

Surrounding the dial l is an escutcheon ring in back of the panel. A plurality of posts I3 riveted'to the pulley and having the escutcheon ring xed thereto by screws M serves to join the ring to the pulley. The pulley l2 has an arm vlli secured thereto by which it is mounted on the condenser shaft l so as to turn with the shaft. A cable I6 trained over the pulley l2 and a smaller pulley H which is driven by a knob I8, provides means for manually adjusting the condensers in the customary manner.

Extending around substantially the lower half offthe escutcheon ring Il are individual station selecting elements indicated generallynby the numeral it. These station selecting elements have depressible buttons 2t on which the call letters of the various stations to be automatically tuned are delineated. Depression of any one of these buttons renders` its station selecting element operative to arrest rotation of the escutcheon ring and consequently the condenser shaft at a predetermined point necessary to tune the receiver to the broadcasting station represented by the selected button.

Inasmuch as all of these station selecting elements are identical in construction, a description of one will suffice for all.

Each station selecting element consists of a body in the form of a cylinder 2l having a large diameter` bore 22 at its outer end and a small diameter` bore 23 at its inner end. Between the two bores is a tapered bore 2d and between the large end of the tapered bore and the large diameter bore 22 are threads 25.

The inner end 25 of the cylinder is smaller in diameter than the central portion 2'! of the cylinder, and its extreme outer end 28 is of a diameter even smaller than its inner end portion, to receive the cup-shaped button 2B. A spring snap ring 2? detachably holds the button 2l) in position on the outer end of the cylinder.

At its extreme inner end the cylinder has an annular groove 39 to receive a tongue 3| carried by a disk S2 from which an eccentrically disposed stop finger 33 projects. The disk 32 is rigidly and nonrotatably secured to a stem 34 which passes through the central bores in the cylinder with substantial clearance between it and the smallest bore 23. This clearance, together with a gateway 35 which extends across the flange left between the annular groove 3B and the inner end of the cylinder enables the disk and stem to be assembled with the cylinder.

This disk and stem constitute a movable dial carried stop which cooperates with a stationary stop 3S to be hereinafter more fully described, to limit rotation of the rotating unit at a definite point which is adjustable by rotation of the stem and disk. The stem and disk are held in any desired position of rotational adjustment with respect to the cylinder 2i by a conical clamping bushing 3l pressed into the tapered bore 24 by a clamping screw 33 to grip the stem 34.

The manner of effecting this adjustment is clearly illustrated in Figure 6 and to facilitate the same, a special tool 39 is provided. This tool consists of a tube l equipped with a knurled knob 4l and an inner flattened end to engage in a screw slot SQ in the outer end of the screw 38. A screw driver i3 inserted through the tube 46 is engageable in a screw slot formed in the end of the stem 34.

Hence, by backing ofi the clamping screw to release the grip which the conical bushing has on the stem and holding the same in a released position by means of the knurled knob lil, rotation may be readily imparted to the stern Sli by means of the screw driver i3 to swing the stop pin 33 about the axis of the cylinder.

Before this adjustment can be made, it is of course understood that the cup-shaped button 20 is iirst removed.

The entire station selecting element or movable stop is mounted in position by means of two complementary ring members lll and 45 in such a manner as to permit endwise or axial depression of the assembly to dispose its stop pin 33 in line with the stationary stop 35. Both of these ring members lill and may be formed of bendable metal and each has a flange 46 by which it is attached to the back or" the escutcheon ring and a cylindrical part Lil, the outer edge of which carries a flange el? parallel to and directed in the opposite direction of the flange 46.

Together, the two complementary ring members form a box-like annular channel which encloses the several individual station selecting elements. The inner ring member M is permanently secured to the escutcheon ring ll by having its flange 46 spot-welded to the back of the escutcheon ring, but for purposes of assembly the other ring member 45 is held to the escutcheon plate by having its ange 46 interposed between the back of the escutcheon ring and the adjacent posts I3.

The adjacent edges of the anges G8 of both ring members have semi-circular notches 5i), each pair of which forms a round hole to receive the end portion 2S of a cylinder 2l. The engagement of the end portion 25 in the hole thus formed together with tongue and groove connections 5I between the cylindrical portions 4l of the two ring members and the enlarged central portion 2'! of the cylinder guides the cylinder for endwise motion and accurately holds the same against rotation.

A compression spring 53 coniined between the shoulder formed at the juncture of the inner and central portions 26 and 2l' of the cylinder and the inner surfaces of the flanges i8 of the ring members yieldingly urges the cylinder 2i toward the escutcheon plate. This spring propelled motion of the cylinder El is limited by the engagement of the front end of its central portion 2l with the end of a rearwardly directed tubular part Effi encircling a hole 55 in the escutcheon plate through which the button 2@ projects.

In this manner the cylinder 2i and consequently the movable stop is yieldingly held in an inoperative position at which the stop pin 33 clears the stationary stop 33 to be instantly ready for movement to operative position by merely an inward depression.

The stationary stop 3E, in order to accommodate the thickness of the stop pins 33 and insure accuracy in the location of the position at which rotation of the tuning condensers is arrested regardless of the direction from which the selected movable stop is moved toward the stationary stop, has a degree of lost motion. To this end the stationary stop is pivot-ed from the condenser shaft and is held in place with a degree of lost motion by a screw 55 carried by a fixed support 5l and engaging a transverse slot E3 in the stop.

The length of the transverse slot 53 is such to permit the lower free end of the stop 36 to move just the required distance necessary to arrest adjusting motion of the escutcheon ring at the saine position regardless of the direction from which the selected movable stop approached the stationary stop.

In assembling, the individual station'sclecting elements, each properly assembled, are first applied to the escutcheon ring before the ring member 'i5 is in place. This assembly is easily eiected especially if the buttons Eil are left oi the individual station selecting elements` Then, after all of the individual station selecting elements have been applied in this manner and with all of their pins positioned to point inwardly toward thel center, the other ring member 5 may be assembled with the escutcheon ring.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides an automatic tuning device for radio receivers which greatly facilitates adjustment of the individual station selecting stops; and that this adjustment may be entirely effected from in front of the dial and. does not require any great degree of skill.

What We claim as our invention is:

1. In a radio tuning device of the character described: a rotatable escutcheon ring; a plurality of depressible stop devices carried by the escutcheon ring, each of said stop devices comprising a longitudinally movable supporting member, and a stop pin adjustably carried thereby; and means for mounting the supporting members of all of the stop devices from the escutcheon ring comprising, radially spaced ring members, and tongues carried by each of said ring members and slidably disposed in grooves in said supporting members.

2. In a radio tuning device: a rotatable escutcheon ring adapted upon rotation to effect tuning of a receiver with which the device is associated; means for arresting tuning motion of the escutcheon ring including depressible stop devices carried by the escutcheon ring; each of said stop devices comprising a supporting body and a stop pin a-djustably carried thereby; vand. means for slidably but nonrotatably supporting said body members from the escutcheon ring including radially spaced ring members fixed to-

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