US2156677A - Radio tuning device - Google Patents

Description

May 2, 1939.

F. S. COE

RADIO TUNING DEVICE Filed Jan. 22, 1938 2 Sheets-Sheet 1 ATTORNEY.

vMaly 2, 1939. F. s. @E

RADIO TUNING DEVICE Filed Jan. 22, 195s zrsheetS-sheet 2 ATTORNEY.

Patented May 2, -1939 'UNITED sTA'rssPATsNT oFFlcs 1....... s. .IMTI

American Bosch Corporation, Mass., a corporation of New' York Srrinsiield.

Application January 22, 1938, Serial No. 186,281

4I clams. (c1. 'M -1o)` This invention relates to .improvements in radio tuning devices of the type in which a conventional knob is provided for manually tuning a-receiver \to any station withinthe range thereof, andin which separate means are provided for selective'- ly tuning the receiver to a limited number of desired stations. l

It is among the objects of this invention to provide a structure in which the' driving connection between the knob and the tuning shaft is automatically disengaged upon release of the knob, and in which the selective tuning means is likewise disengaged when not in use.

In radio tuners, it is common practice to pro' vide a manually movable member, such as a lever which is adapted to coact with a cam, to rotate -to a predetermined angular position' acontrol shaft operably connected with the tuning shaft. 'l'.'he cal'n is usually adjustable on the control shaft goto permit any desired angular relation Vthereof with respect to the shaft, .and therefore a'ny desired angular position: of the tuning shaft corresponding .to any desired broadcasting station 'may be obtained. In such structures, it may happen that the angular" position of the cam upon the shaftls such that when `the lever is depressed, it

bears upon a surface of the cam closely adjacent to or upon' a line extending through the center of the shaft. Under such conditions, which may v occur during the early portion of the movement of the lever or toward the end thereof, there is little leverage available and the depression of the lever may be difficult to effect.

It is among the-objects of this invention-to overcome the abovementioned defect and provide a structure ofthis type in which vthe operation of the lever does not meet material opposition until the shafts have been rotated to the desired angular positions, at which time the lever reaches 40 its full stop position.

Still another object of the invention is to provide a simple and compact arrangement of parts,

such that the tuning'device is readily adapted ior use in various types of cabinets. To this end the control shaft is mounted parallel to the tuning shaft andloperatively connected thereto by gearing. The two shafts may be supported above and below the same base plate thus placing all tuningcontrol parts adjacent a small panel with which dial mechanisms of many suitable forms may be associated, and also adjacent the radio parts mounted on the top and bottom .of the -base Y plates.

'It 1s a further object of the invention to provide, a structure'of this type'in which themanually actuated lever requires but a small angular move. ment to effect the desired movement of the tuning shaft. a' v The above and other objects and features of this invention will be more apparent to those 5 skilled in the art from a consideration of the fol- 4 lowing detailed description taken in conjunction with the accompanying'drawings, in which:

Fig. 1 shows a portion of a radio -receiving set in side elevation with parts removed to show its 10 internal construction; Fig. 2 shows a detail of the lever tuning mechanism; and Fig. 3 shows a front view of the device with parts removed to show its internal structure. i(

In the drawings reference numeral I indicates 15 a base plate forming a portion of the chassis of a radio receiving set having the usual tubes, coils, transformers, etc., indicated generally at 2. A tuning shaft 3 mounted below and supported from the base' plate I is provided withthe usual con- 20 denser gang 4 or other variable tuning means of the receiver. A drum 5 mounted upon the shaft 3,preferably at the end thereof, is provided with an annular rim 6 adapted for engagement with a friction wheel 1, preferably of soft rubber, mountg5 ed upon a short shaft 8. The opposite end of the shaft 8 is provided with a knob 9 forming the manual tuning knob ofthe receiver. The shaft 8 is mounted for both angular and longitudinal movement so that upon slight manual pressure '30' against the knob 3 the friction wheel 'l will engage the annular rim 6 of the drum 5 and thus rotate thedrum 'upon rotation of the knob 9. ,The end of the tuning shaft 3 remote from the drum 5 is provided with a gear I 0. 35

A control shaft Il is mounted above the base plate I in journals I 2 and I3 supported by brackets I4 and I5, so that it extends substantially parallel with the tuning shaft 3. A lever shaft I6 is also supported in the brackets Il and I5, 40 behind and below the shaft II. A plurality of levers I1 are pivotally mounted upon the lever shaft I6 and are so formed that they extend upwardly over the shaft II and outwardly through slots I3 provided in the panel I9. Tension springs 45 20 supported by spring bracket 2l, mounted upon` a panel support 22, normally hold the levers I 'I in an upward position free from the shaft II. The levers I1, which are preferably formed of metal stampings, are of substantially greater breadth at their central portions than toward the ends thereof, and in this central portion each'is provided with-a notch 23 positioned to register with the shaft I I upon depression of the lever. A plurality of adjustable crank members 2l, coru fro responding in number to the number of levers I1, are mounted upon the shaft II. These cranks are identical each having' a collar 25 for rigidly clamping the member upon the shaft II and an arm 26 integral with the collar 25 extending ina plane normal to the axis of the shaft II. Ihe

arm 26 is provided at its end remote from the shaft I I with a projecting portion 21 forming a crank pin extending at right angles to its {surface which projecting portion provides a pair of spaced heels 28 and 29. lIfile/lower edge of each lever I1 is provided with smooth straight portions 30 and 3I extending on both sides of the notch 23 which straight portions are adapted to contact with the heels 28 and 29 upon the depression of the corresponding lever I1 to actuate the shaft II in a manner hereinafter moreparticularlydescribed. Each crank 24 is split through the arm face of the drum 5 and is guided by guide pulleys 31 and 39 positioned adjacent the top and bottom of the dial. This' tape carries the dial scale pointer 39. Thus rotational movement of the drum 5 is translated into upwardor downward movement of the pointer 39`over the face of the scale 35. A protecting strip of metal 40 is provided for the sake of appearance and also for protecting the exposed surface of the tape 36 inv front of the scale. A third guide pulley 4I, free to rotate upon the shaft II, may be utilized for further guiding l and tensioning the tape 36.

In the operation of the above device as above described,`normal manual tuning of the receiver set is obtained by pressing the knob 9 inwardly so that the friction wheel 1 contacts the annular rim 6 upon the drum 5. Rotation of the knob thereupon rotates the drum and accordingly the tuning shaft 3 to alter vthe setting of the condenser 4. The scale 35 being calibrated in the usual manner any particular setting of the condenser will be visibly apparent to the operator from the positioning of the pointer 39 on the scale. Since pressure is required to engage the friction wheel withthe annular rim upon the drum, the moment the pressure upon the knob is relieved the driving connection between the knob and the drum will be automatically disengaged.

In order to adjust one of the cranks 24 for selective tuning of the receiver to a particularv` station, the corresponding one of the levers I1 is depressed. In this position the lever will engage a crank 24 in the manner shown in Fig. 2, and further downward movement of the lever or any movement of the crank 24rrelative thereto is impossible. However, the shaft II may be ro.

tated within Athe collar 25, assuming that the screw 33 is loosened by a screw driver inserted tated to the same position.` The other cranks 24 can be similarly adjusted to other desired broadcasting stations. Since thecontrol shaft II is geared to the tuning shaft 3, the latter will like- Wise be moved to the position corresponding to the station for which it was set at that time. lThe finger keys on the ends of the levers may be labeled with the letters ofthe respective broadcasting stations.

It willbe noted that rotation of the tuning shaft 8 will occur regardless of the position of the control shaft II, within'its angular range, before the lever is depressed. 'I'hus if the shaft II isin such angular position that the heel 28 extends upwardly, the straight portion 30 of the llever I1 will contact this heel to rotate the shaft p shaft IIr will come to rest with both of the heels contacting the lever as shown in Fig. 2, and this position will of course be the same at which the crank 24 was adjusted upon the shaft I I.

- 'I'he ratio of the gearing between the shafts II and 3 is preferably 180 to '10. Thus a relatively small rotation of the shaft II is sufiicient to effect rotation of the shaft 3 throughout the full range, substantially 180, of the condenser gang. Such a gear ratio permits the setting of the cranks 24 upon the shaft II to various predetermined positions corresponding to any selected station within the range ofthe dial, and within such range none of the contacting heels 28 and 29 will ever assume such positions that the direction of the force applied by the lever will pass through or close to the center of the shaft II. Thus no position of a crank relative to its lever will correspond to a dead center or an approximate dead center position which would require considerable effort to depress the lever, and material resistance to the manual actuation of the lever is obtained when and only when the lever reachesA its full stop position with the heel 28 contacting the portion 30 and the heel 29 contacting the portion 3I as shown in Fig. 2. The ease with which the lever may be actuated is further augmented by the fact that during the moment when the lever tuning is being utilized, the knob shaft 8 is not in driving connection with the drum 5. The elimination of toothed gearing or other fixed driving connection between the knob shaft 8 and the tuning shaft 3 thus not only prevents rotation of the l knob when the lever tuning is being utilized but also eliminates this additional source of frictional resistance.

Although there is herein described but a single 'embodiment of the invention, other embodiments within the scope of the appended claims will be obvious to those skilled in the art from a con- 'vsideration of the above disclosures of the preferred form of the invention.

Having thus described my invention, what I claim is:

1. A radio tuning device including, in combination, a tuning shaft; a second shaft; a gearing connecting said shafts; a member adjustably mounted upon said second shaft and comprising a collar. surrounding said second shaft, an arm integral with said collar and extending in a plane normal to the axis of said second shaft; land a lever operable in a plane normal to the axis of said second shaft and having a notched portion adapted to embrace said second shaft upon actuation of said lever; said arm having a projecting 5 portion extending at right angles to its surface at the extremity thereof remote from said collar; said lever having portions adjacent each side of said notched portion for contacting said projecting portion of said arm, said projecting portion w lying in the path of said lever whereby the edge of said lever adjacent both sides of said notched portion contacts said' projecting portion to rovtate said second shaft to a predetermined posil pression of ysaid lever whereby when depressed 4the lower edge of said leverI projects below the horizontal plane of said shaft, said lever' having portions adjacent said notched portion for conw tacting said crank to rotate said shafts.

I3. In a mechanism for angularly 'positioning a control element of a radio device; a member adjustably mounted upon a rotatable shaft and comprising an arm extending in a plane normal to the axis of said shaft and having one end adjustably attached to said shaft and carrying at its other end a. lug extending perpendicularly to the plane of said arm; and an operating lever adapted. to directly engage said lug lat spaced points positioned upon one side of a longitudinal plane through the axis of said shaft and thereby rotate said shaft to an angular position determined by the adjustment ofsaid arm.

4. Ina mechanism for angularly positioning a control element of a radio device, a rotatable shaft, an arm attached at one end to said shaft and extending in a plane normal to the axis therelever and also having a portion on each side of said notch adapted to contact a portion of said arm and rotate said shaft to a predetermined position.

FRANK S. COE.

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