US2981114A - lingenbrink - Google Patents

Description

A ril 25, 1961 H. E. F. c. LINGENBRINK 2,981,114

DRIVE SYSTEM FOR TUNING ASSEMBLY Filed April 29. 1958 2 Sheets-Sheet 1 Q INVENTOR.

L? FUPM H 770/? IVE) April 25, 1961 Filed April 29, 1958 H. E. F. C. LINGENBRINK DRIVE SYSTEM FOR TUNING ASSEMBLY 2 Sheets-Sheet 2 45" 42 44 /6 i M? 1 fig 472} F3 F "W1 x W N I W9 M M NH W 11H 1/ T l\ T I 0 Z2 3 7! 37 z/ i F/ 7 INVENTOR.

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United States Patent 2,981,114 nmvn SYSTEM r01: TUNING ASSEMBLY Hermann E. F. C. Lingenbrink, Hilltown, Pa., assignor to Philco Corporation, Philadelphia, Pa., a corporation of vPennsylvania Filed Apr. 29, 1958, Ser. No. 731,831

1 Claim. or. 74-10) This invention relates to tuning means for broadcast receivers, particularly for small, portable receivers such as pocket radios. It is a general object of the invention to provide an instrument of the indicated type which can be accurately tuned by simple, manual operations.

Ordinary tuning knobs and shafts, adapted to the dimensions of the human hand and also to those of conventional receiver elements, are evidently too large for" incorporation in such a small unit as can be carried in a pocket'or held in one hand. If ordinary knobs, however,

were simply miniaturized in proportion to the size of the cabinet or box, it would no longer be easy to adjust them accurately. Nevertheless a system of tuning elements is required, which elements must be moved relative to fixed points, and/or relative to one another, with considerable accuracy, often for instance with an accuracy exceeding that of the conventional adjustment of a small watch. a -A solution for this dilemma between smallness of conv terimprovements form, added or independentfeatures of the invention.

., Briefly described the new construction, as illustrated herein, includes a receiver box of such small size that it can conveniently be held in one hand. According to one' aspect of the invention the, tuning system comprises relatively small wheel means-generally a pair of wheels pivoted and generally disposed within the small receiver exposed on opposite outer surfaces of the box, thereby allowing fine manual tuning by the relative small wheel means. According to another aspect ofthe invention two tuning wheels are directly interconnected by integral clutch means providing a controlled degree of relatively loose or lost-motion coupling therebetween; and the said wheels may additionally provide tuningtindicator means on furtherintegral portions of the wheels.

These and other features of the new construction will .be described more fully in conjunction with the drawing,

wherein: l

g [,Figur'e lis a perspective'view ofiapreferrcd embodiment hereof and Fig'iire Z its side view of said embodiment. Figure 3 is an enlarged fragmentary sectional view; takenalong line 3-3 in Figure 2.- Figure 4 is a partially exploded perspective view, of some of the parts shown in Figure: 3. -FigureS is a section taken along line 5--S'in Figure 3. Figure 6 is a front view of the receiver box of Figure l, partly broken away to show internal construction; and Figure 7 is a schematic wiring diagram of the tuning system and of directly associated parts of the new receiver.

As shown in Figure l, the pocket size receiver casing or box 10 has a pair of peripherally serrated or knurled tuning wheels 11, 12-therein, each of which has a segment thereof projecting beyond the front surface 13 of the box. A diametrically opposite segment of each wheel 11, 12 projects similarly from the back surface 14 of the box, as shown in Figures 2 and 3. On each surface of the box, the so projecting portions of said wheels are separated from one another by a narrow strip 15 of the corresponding wall 13 or 14, (Figures 1 and 8).

Selector wheels 11, 12, as shown in Figure 6, preferably have indicia, such as numbers, associated therewith to indicate station frequencies or the like, and receptacle or casing 10 is shown in Figures 1 and 6 as providing for inspection of such indicia, by an aperture 16 in a top or end portion of the casing. The receiver is also shown in Figures 1 and 2 as having an on-off switch and volume control device 17 which utilizes an actuator wheel similar to wheels 11, 12; this latter wheel however being distinctively located and/ or arranged and projecting only from one wall 13, remotely from the system of tuning wheels 11, 12. An electrical cord 18 connects the set to a suitable earphone 19 with holder 20.

Referring now to Figures 3, 4. and 5, each selector wheel 11, 12 has loose or free-play coupling means 21 on one side thereof for the purpose of suitably interconnecting these wheels, while having rotary slidable condenser means 22, 23 on the other side thereof. The mechanical construction of both condenser means 22, 23 may be substantially the same and only one of them has been shown in exploded form in Figure 4.

Each condenser includes a first segment carrier 24 of insulating material, carrying a conductive segment 25. A

, central conductive pin 26 is electrically connected to this box, each wheel having tunable circuit means connected i therewith and having a pairof wheel rim or segment areas segment and is mechanically connected, by a square end portion as shown, with segment carrier 24 and also with wheel 11 or 12, see Figure 3. Each condenser also includes a thin di-electric wafer 27 of suitable ceramic or .the like, which as shown in Figure 4 has a central aperture 28 for pin 26 and a conductive segment 29 suitably spaced from aperture 28. A resilient washer 30 is provided with .a similar central aperture 31 and with an eccentric aperresilient washer, dielectric wafer and segment carrier 34,

' v30, 27 and 24 assembled. The assembly is secured to a wheel 11 or 12 by press fitting segment carrier 24 intothe wheel; and due to the pivoting of elements 27, 30 and 34 onpin 26 the segments 25, 29 can be rotated relative to one another, by rotating for instance wheel 12 relative wafer of the second condenser 23, which is mechanically of the same construction,while having independent electrical terminals 38, 39.

The loose coupling mechanism 21 interconnecting the two condensers 22, 23 is best illustratedin Figure 5 in conjunction with Figure 4. It will be seen that selector -Wheel-11 has jaw means 40, 41 integrally formed thereon opposite condenser 22, and wheel 12 has similar-jaws 42,"

as to leave as many gaps 44 in coupling 21 as there are jaws; and the arrangement is desirably such that the several gaps have approximately uniform width. This is conveniently; achievediby. using wheels 11, 120i substantially identical construction, each wheel having two diametrically opposite, arcuate jawsand each jaw covering for-instance about 85 degrees of a complete circle.

Referring now to Figurefi'it will be seen that the loose coupling mechanism 21 and the associated condenser devices 22, 23 are disposed in an upper portion of the box 10. The bearing plate 34 of each tuning wheel 11, 12 is advantageously supported by a pair of holder members 45, 46;rigid with casing and disposed within the same; one such member 46 can also be seen on each side of Figure 3. These holders desirably comprise channel members rigid with wall 13 and/or 14 and frictionally engaging edgeuportions of bearing plates 34. These latter plates desirably taper toward one end, as indicated in Figure 4, athus facilitating insertion in holders 45, 46. No accurate :pivoting of wheels 11, 12 and associated parts is required,

.48; said panel having connecting means 49, 50, etc. for

condenser terminals 35, 38, etc. The panel is also provided with associated circuit elements which are shown in Figures 6 and 7 and which comprise a first transformer or antenna unit 51; amplifier transformers 52, 53; a detector diode 54; amplifying transistors 55, 56; and associated circuit elements which require no detailed discussion herein. Suitable batteries 57 are used as a power source.

In order to operate the new device, the user of course starts by applying earphone 19 and by turning switch and volume control member 17 to on and to suitable volume. He then manipulates wheels 11 and 12 for the tuning in of a desired broadcast. For such manipulation the usercan conveniently grasp the entire receptacle 10 in one hand and he may initially place the tips of forefinger and thumb of the same hand, on the exposed portions of one wheel 11 or 12, in the manner shown in Figure 2, although he may, if preferred, use two fingers of the other hand for this purpose. In either case the operation is very convenient, as the actual size of the unit is generally smaller thanthat of Figure 3; and at the same time the operation is accurate, as the two-sided gripping of each wheel, provided in this way, allows very gradual, minute shifting, particularly-by virtue of the simultaneous abutment of each operating finger tip against the surface of receptacle 10. I

As indicated by Figure 6, anysubstantialrotation of one tuning wheel 11 or 12, provided in this way, causes rotation of the other tuning wheel, which however remains free for adjustment relative to said one wheel,.by

There may follow a correction of the disturbance of elements 51, 55, caused by the fine matching of elements 55, 56. About two to four such consecutive movements of the condensers are generally required for adequately sharp tuning of a pocket radio; it being generally preferred first to move the, two condensers conjointly, into the range of high volume'output, and then to adjust them relative to. one another within said range,

Some of these consecutive movements of the two condensers and wheels, mainly their adjusting movements relative to one another, involve very slight, delicate and accurate rotations of wheel 11 and/or 12; and such minute and precise motion is most readily achieved by the construction of the receiver casing, exposing two oppovirtue of the loose coupling between these wheels. The

loose coupling is indicated in the circuit diagram of Figure 7 by broken line 21 It will be understood from the latter diagram that init1al, progressive, unidirectional, rotation of one tuning condenser,22 or 23, whichresults ingenerally similar rotation of the other tuningcondenser, matches the primary or antennacoil of transformer 51 to the input of amplifier device 55 and,-by loosecoupling 21, 'partly matches the output of amplifier deviceSS to the input of the second amplifier device 56, thereby providing a first maximum volume of output in. earphone 19. A further increasein such output can then be obtained by progressively, unidirectionally moving only the other condenser to a slight extent, as is allowed by the loose mechanical coupling; this improves the'matching of elements 55, 56,

those ofv the other.

site segment areas of each'tuning wheel. Displacements of the two wheels, relative to one another, can be detectcd and/ or effected by this arrangement with considerably. greater accuracy than is available when conventional tuningwheel designs and'arrangements are used on the smallrscale which is here involved. The user of the new device can,.a s indicated by Figure 2, span the front and back walls of cabinet 10. between the thumb and a finger of one hand andcan thereby frictionally. engage any of the projecting segments of wheels 11 and 12. The width of the wheel-separating strip 15 (Figure l) is, as shown, smaller than the width of a thumb or other finger. Thus the. user can shift the tips of the fingers of the hand holding the cabinet from the segments of one wheel to The manual-adjustment, as already explained can be. carried out with great accuracy as well as;convenience, by virtue of the wheel segment arrangement .as: described. It can often be performed in merely a second or two.

Although only a single embodiment of the invention has beendescribed, it should be understood that the details thereof are not to be construed as limitative of the invention, except insofar as is consistent with the scope of the following claim;

I claim:

Ina pocket broadcast receiverz an enclosure which has front and rear. walls, so closely spaced that one hand can-spanboth of said walls; a receiver set in said enclosure; a tuning device comprising a pair of friction wheels, each being rigid and coaxial with one circuit tuner element which forms part of the receiver set, said wheels being coaxial one with the other, both being pivoted in said enclosure, .each'h'aving asegrnental portion projecting throughsaid front wall and a segmental portion projectingthrough said rear wall, the segmental portions projecting through each of said walls being spaced apart not substantially morewidely than the widthof a finger; and acoupling; comprising jaw means on each of the two wheels, within: said enclosure; each ofsaid jaw means being rigidly peripherally formed on one of said wheels and-beingadapted toengage and rotate the jaw means of; theother wheel, subjectto lost rotary motion, so that conjoint as well as relative rotation of said pair of tuner elementscanbe effected by each of two fingers of said one hand. 6t).v

' References iCited inthe file of this patent UNITED STATES PATENTS Vreeland Mar. 11, 1930 1,914,018 Hollerith June 1 3, 1933 1,934,524 Conrad 'N0v. 7, 1933 2,510,757 i ,J ne6, 0

4 FOREIGN-PATENTS LO-15,506 Germany Sept. 12, 1957 THE RE E E Radio-it. Television News, January 1955, A New Pocket Radio, page :54.- t

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