US2454789A - Tuning control mechanism - Google Patents

Description

Nov. 30, 1948. Y F'. w. FRINK ET AL 2,454,789

TUNING CONTROL MECHANISM Filed June 16, 3945 4 Sheets-Sheet 2 TTo/PNE'Y Nov. 30, 1948.

F. w. FRINK ET AL 2,454,789

TUNING CONTROL MECHANISM Filed June 16, 1945 4 Sheets-Sheet 3 ATTFNE'Y Nov. 30, 1948.

Filed June 16, 1945 F. w.v FRINK ETAL 2,454,789

TUNING CONTROL lMECHANISM 4 Sheets-Sheet 4 MWA,

Patented Nov. 30, 1948 runnin oNTRoL MECHANISM .Frederick i-Frink, tEast Orange, N. J .,rand Murray Kaplan,. `-Bro9klyn, N. Y., assignors to Fedone .and Radio -Qorveratiom `New .atapi-,poration of Delaware implication 1945, -Serial No. 599,908

This invention relates totuning controimechanisrnl andmo're particularly-Ktotunin'g .control mechanism for stopping'a panoramictuningtreceiver in a predeterminedtunedposition.

In panoramic tuned'receiverswherelnthe receiver is continuously tuned over a' frequency band or bands, it is often desird-to Vstop-the scanned tuning of the receiver at .a particular tuning positionrepresenting a received ,station in order thatY the station may'4 betuned-,in more precisely for listening to orI sothatrdirctioninding may be accomplished on this .fparticularfstation. In ,the panoramic tuning recivers'generally some form of drive mechanism such asalmotor is used to drive vthe tuning condensersof vvsuch a receiver to tunevthe system over a Ldesiredtfrequency .band or Lbands'. .Iriordercto stop thevt'uning of the receivervin a `prede'termii'xdtunedposition, it is therefor desirable to provide some means .for stoppigthe 'nitor at a'..particla'r point in its rotation .sovthat lthe'freceiver.fwill'be properly tuned to the `selected station.' ySuch panoramic 'tuning receivers are r'generally provided with 'some form of visual indicator :which may, for example, `be a cathode '-ray `tuloe the sweep of which represents the sweep through th'effrquency band. .Some-form 'lo'f indexing n'ia'yibe provided adjustable over .the swep'tbandto a position corresponding to a signal indication;

Inv accordance with our invention fwe provide means for simultaneously adjusting astop mechanism together with theindexing' yindications so that'the stop mechanism .will be positionedproperly to stop the motorlshould itbe `desiredlto listen in on the slectedjs'tation. .For this purpose, the motor .preferably is'islowed .down' or stpped prior to themovement ofthestopmechamsm-nto a nnal stoppingrelationship so that .there .willrnot be too great a shock Qn themechanismwhen the motor Stop or detentcoqpraingwiththe :stop mechanism @emes irl-.centen ,therewith Further.- more, whenA two r mereffreqveeCyhepia re being separatelycannedtin ,the Ielyer, `itis Lnec- Aessary that r,tllifc ustib', ing'zczlianisizi he .A ,provided Kto stop the rotation '.0 ...t,.11`e.,`i0tor 'atlga .pointlc rw. SpendingtO the sleid,.steitien vitliinf .the lected frequencyhand.

In accordance ,with .our invention, we provide a mechanism which will `stopa 4i'x'iotm without producing undue strain 'on the shaft andwillstop the motor in the ldes'ire'd'tuingposition'inla'fselected one of 'a plurality ffeque'ncy ban s. i

' n win be cie-ar that the'mechnisniivvel-have .designed while useful principally-'inthe control of panoramic .tuning receivers'. mayube .of'mor'e generalcapplication and .may.serve to stopamotor in.a.desired.adjusted positionfor other purposesi. thanlthe .tuning of `a receiver arrangement. rIt saccordinglyan ooject of our Ainvention to ,providea motorcontrolsystem whereby a nor- I'naLcontinuously driven motormay he stopped at a...predetermined Ipoint in its rotation.

-It .slaifurthenobject of .our invention to provde amotor control system wherein .a stop mechan'ism is inserted. in thepath .of adetent rotated by .the ;motorsubsequent yto a .stop ,controlaction fofithe motor iafter .which the motor .is .driven ,at a `lovvrgrate..of..speed. until. thedetent comesin contact with thefstop mechanism.

It ;isas.til1, further 4obj ect of ,our .invention .to .provide a .motor .control system for selectively stoppingithe..motor. in either, of two .chosen posi" tions', in ,which astop .means .provided .Witlrdia- .metrcallyiopposed ,stop v surfaces is .arranged .rotatably with .respect to the moto-r and. is made movable. into; the path .of aY detent idrivenlcy the .motorin either, of two ydirections to stop .selectively themotor inthe .desired one of the two .selected positions.

Itis aJstilli-further `object of 4our invention to gnllbvide, in afrequency .scanning receiver, .means for stopping. thescanning of the receiver. in a ,desired adjusted-ztuned position lhy .theselective insertion of. astopvmechanism .into the path rof `the .driving..meansfor the .scanning receiver.

;It.is.a stllfurther objectof ourinvention-fto Iprovide, in a frequency scanning receiver, means --for adjusting selectively said receiver `in a desired .tunedposition in one of a plurality of fre- `quencyh'ands 'by Vselectively moving a selected :one .of .a plurality vof .stop Vsurfaces .into the' pat-h of .adetent Ydriven `loy the motor which normally itunesfthe receiver through 'the scanned frequency bands.'

-It :isaI still further object of our invention to provide, ina lfrequency scanning receiver, an inldexig indication and means `for .adjusting this indexing indication simultaneously Withvv .stop meansin acoar'se or line Vernier adjustment,y si- -niultaneouslywith movementof a stop means -to the desired relative position withrespect to the .tuned frequency band over which .the receiver is scanned. .Whilewe `have outlined .brieiiy above the gen- `eral objects andieatures of our invention, a bet- .'.ter .understanding of these objects and features .'.may .be hadyfrom-.the .particular description there- .of vmade With Vr'eference -to the accompanying drawings, in which:

.-1.is a .blockschematic circuit and opera- Fig. 4 is a bottom view of the apparatus illustrated in Fig. 2;

Fig. 5 is an end view taken along line Ii-i of Fig. 2;

Fig. 6 is a perspective end view oi the control mechanism;

Fig. '7 is a sectional view taken along the line 'l-- of Fig. 2; and

Fig. 8 is a sectional view taken along line of Fig. 2.

Turning first to Fig. l, it is to be noted that this operational diagram is not intended to be complete in the mechanical details; its primary purpose is to indicate iunctional relations less readily seen on the other views. In this Fig. l, a tunable receiver is shown at I having coupled thereto antennas 2 and 3 for receiving signal energy in an upper and a lower frequency band. Receiver I is tunable through; two frequency bands by means of a shait 4, driven by a motor ii. Motor 5 also drives a scanning disc l. The output of receiver I is coupled over a line l and through a coupler i5 to the vertical deflecting plates i! of a cathode ray oscillograph Ill. 'A pair of headphones II are also arranged to be energized from the output of receiver I through listen switch I2. Control disc o is provided with a slot I3 rotated between a lamp i4 and a photocell I5 which serves to produce a square control wave which is applied over line lo to receiver I. This control wave serves to switch the rem ceiver between the bands received on antennas 2 and 3 for each revolution of the disc driven by motor 5. The control wave from the output of tube I5 is also applied over lines I I? and lli to coupler 8 and then to the vertical deflecting plates 9 to produce a displacement of the tracing indication as shown at i8 and i9 representing the upper and lower frequency bands of the ren ceiver. The horizontal sweep of the indicator beam of oscillograph IIJ is provided by the shutter disc t through the medium of lamp 2d and photocell 2l. The output of photocell 2i is applied over a line 22 to a sweep generator or amplifier 23, the output of which is applied across the horizontal delecting plates 24 of indicator Ill. A third set of control means comprising a lamp 25 and a photocell 2li is associated with disc t and serves over line 2l to control the pro'- duction of indexing pulse in the indexing generator 28. The output of the indexing generator 28 may be applied over a coupling line 23 and coupler 8 to the vertical deflecting plates il of oscillograph I!) producing indicating bends or offsets 3l) and 3l in the sweeps i3 and Iii indi-- eating the upper and lower frequency bands respectively. A tuning knob 32 serves to rotate an indexing control shaft 33 which serves to adjust the position of the offset indications 3B; 3I through the adjustment oi indexing generator 28. This adjustment may be made in actual practice by adjustment of the rotary position oi lamp 25 and cell 25 relative to disc Ii as shown by the extension of shaits and 34.

Control knob 32 may normally be urged by a spring (not shown) inwardly so as to move a control means 35, which may serve simultaneously as frequency index, into contact with a clutch gear mechanism 35 loosely mounted for rotation about shaft 33. Thus when knob 22 is released from its normal position, gear 3b will normally be clutched to shaft 33. A Vernier tuning knob 3'! serves to drive Vernier gear 33 to rotate shaft 23 to provide the fine adjustment of tuning as indicated by scope indicators 3o and 3l. Motor 5 also carries on its shaft 39 a stopping detent 4o having a stopping surface 4I. Detent it rotates with motor 5 so that it at all times corresponds to the rotary position of the motor. A stop mechanism 42 mounted on a gear 43 is rotatably positioned relative to the motor in accordance with the indexing adjustment by of a gear 44 carried by shaft 33 meshing with gear 43. Thus, as the indexing indications 3o and Si are adjusted over the face oi the scope, stop mechanism 42 is adjusted in a rotary position with respect to the motor 5 so that it will at all times be positioned with respect to the rotation of the motor at a. tuning position indicated by indicators 3@ and 3l respectively. Stop mechanism 42 carries two stop surfaces diametrically opposed as shown at 45 and 46.

Under normal operating conditions, energy from power source 41 is applied over a resistor arrangement 48, line 49, switch 50, switch lil and smoothing filter 52 to motor 5 to drive the motor 5 at a predetermined speed during scan ning. When it is desired to stop the motor in a particular scanning position as represented by indications 30 or 3l, a control lever 53 is moved into the upper or lower position dependent upon which frequency band is to be observed. Upon movement of lever 53, control link 54 serves to close a switch 55 energizing relay 56 so that switch I2 is closed and the listening device E i is put into the circuit. Simultaneously, the movement oi lever 53 serves, by means of a control linkage 5T, to move switch 5l) from its contact at line 49 into contact with a line 53 serving to eiiectively short circuit the armature 5A of the motor 5, iield 5B still being energized, and stop the motors rotation. When motor 5 has been stopped, linkage mechanism 59 serves to move stop 2 in either of its two selective directions to bring stop surfaces 45 or 46 into the path of detent 4o, dependent upon which irequency band has been selected. After a delay caused by the normal operation of the linkage mechanism, linl: Eil through spring 6I serves to move switch contact 5I from its normal position into Contact with line 62 again energizing the motor with the energy produced in the yresistor 63 and the output oi power source 41. It will vbe noted, however, that in this case the voltage drop is low so that motor 5 will be rotated at a slower speed. Motor 5 will then rotate at this reduced speed until detent 40 comes into contact with the selected stop surface 45 or 46 of stop mechanism 42 at which time the motor will be brought to rest with the receiver 'I adjusted to position corresponding to indexing indications 30 or 3l dependent upon whether lever 53 has been moved up or down. It will be clear that by the use oi this type oi mechanism, motor 5 may be Stopped without undue shock to the equipment and may be stopped precisely inthe position indicated by the indexing indication. Should it be necessary then to adjust` the tuning of the receiver, for instance to bring the-receiver more sharply into tune with the received signal, then knob 31 may be rotated causing further rotation oi,` gear 43 andl stopy mechanism 42. The motor, being energizedat a lower power level, will follow up this tuning adjustment to adjust the tuning of the receiver through the medium of' shaft 4. Simultaneously, the indexing lamp 25 and photocell 26'` will be also adjusted tov its corresponding new position.

In yconnection with Figs. 2 through 8 inclusive, a more detailed description of the control mechanism is given. of shaft 4- and shaft 39, serves to drive the tuning condensers 'contained within housing 64;' when lever 53is'in its normal medium position. Movement of lever 53 `upwards or downwards as shown in` Fig. 2 serves to rotate a disc 65: moving" link.

56 either'up or down causing linkv6`| to be movedj to the right. Movement of `link 51. causes' sliding of linkage mechanism' which servesthrough the medium. of lever 59 tov close switch 50 serving to short circuit the motor as indicated'inFig. 1. At the same time, movement of disc 65v through another link 'l0 rotates a` crank arm in one ofV two directions causing tensioning of spring `|2 or spring 13. depending upon whether lever 531is moved upwardly or downwardly. Springs. 7.2 and 13 are fastened on a disc 15 which is held from rotation by means of a pin 1.6 carried on lever 1'|-. A spring 18 normally tends to pull lever I1 into engagement in slot or notch 11a in disc 15. Springs '|2 and |3 are strong enough to overcome the action of spring 'I8 so rotation of disc 'lil'will raise lever 11. A spring controlledv lever 19 fitting over a pin 80 on lever Tl prevents thisfrom happening until linkage 68 has reached the end of its stroke. When the linkage reaches the end of its stroke, however,v holding lever 19 releases lever permitting it to move upwardly under the action of spring 'l2 or '|3' and rotationof disc '|5. Rotation of disc 'l5 serves through linkages 8|, 82 and 83 to move a `carriage 84 (see Fig. 3) to the right or left depending upon which direction lever 53 was moved. Carriage 94`carries withit a push rod 85, pull r-od 86 which will` serve to rock a bell-crank lever 81 inthe same direction regardless ofthe direction oi movement of carriage 84. If' carriage 84` moves to the left, then push rod 85 serves to push the lower end of bell-crank 81 into contact with switch causing the circuit of motor 5' to be energized to drive the motor forward at a re'- duced speed as shown in Fig. 1. However, if the carriage moves to the right then a hookA 88 on lever 85 serves to pull on the other end of lever 8T moving the bell-crank lever into contact to close switch 5|'. It will thus be clear that regardless of the direction of' movement of carriage 84, switch 5| will be operated. The time consumed in operation of the linkage mechanism to move the carriage is suflicient for the motor to come toa complete stop before stopmechanism 42" is moved into stopping position.

Prior to operation of switch 5|, however, stop mechanism 42 is moved into the pathof the detent mechanism 40 driven by the motor. Operation of this may be more clearly,7 seen by reference to Fig. 6 together with Fig. 3. Carriage 84 carries with it two fixed rods 89 and Sil-which serve to move two spaced plates 9i and 92 either forward or backward. Between platesv 9| andA 92 is provided a crank pin- 93 coupled to-a mutilated gear 94 which meshes with a rack 95 carried by stop mechanism 42; Thus as the carriageis moved forward, mutilated gear 94: is rocked in one direction servingto move stop mechanism 42='intoposition for contact with detent 40. When Motor 5, throughV the medium the carriage'is moved in the opposite direction, the mutilated gear is rotated in the opposite direction and the stop mechanism is moved in the opposite direction into position for contact with detent 4|). Gear 43 carrying stop means 42 .is preferably rotatable through 7 so that stop surfaces 45' and 46 may be brought into stopping position anywhere within one quarter ci the rotary position of shaft 39 and the coupled condenser. The condenser covers both bands in; a single revolution as the rotor is of the balanced 90 type. Thus the stop mechanism may be brought into play anywhere within the scanning range covered by the system.

In order to assure a smooth drive for gear $3 upon rotation. of' knob 32, the drive mechanism instead off taking a simple form shown in. Fig. l, consists in a` gear 96 fastened directly to the driving shaft and meshing with two spur gears 98; These spur gears serve to rotate rods 99, |90: tothe ends of which are fastened to two gears 44` meshing with driven gear 43` as can be quite clearly seen in Fig. 3.

The control mechanism for the coarse and Vernier tuning of the apparatus can be more clearly seen from Fig. 5. Here the knob 32 is shown provided with the projecting portion 35 and ring gear 33. Gear 36 is provided' on its upper surface with a plurality of serrations |'0l into which a. projection on arm 35 ts as can be seen from Fig. 2. Arm 35 also carriesV with it the pointer'mechanism I B2 lwhich cooperates with the tuning scale |03. When rapid coarse adjustment of the tuning index and stop mechanism is desired,lknob 32 is pulled outward disengaging 35 from the serrations i0! so that the apparatus may be rapidly rotated. The xed gear 9S is in engagement with the drive gears 9`|- and 98 to control the positioning of the stop mechanism as previously described. When the coarse adjustment has been achieved, knob 32 is released bringing arm 35- into a corresponding notch in serrations |0| so that gear 35 will tend to turn the shaft. Then Vernier knob 3l is rotated turning the worm gear 39 to drive gear @Bf around slowly for the fine adjustment.

Turning now to Fig. 7, the operation of shutter G for the purpose of producing the various control waves can be more readily understood. In this arrangement the light I4 is arranged in xedspaced relation with respect to disc 5 and opposite a slot i941 Slot |94 is semi-circular so that* the light will shine half the time on the photocelri producing eiectively an electrical square wave output inv which the positive portions are equal tothe negative or zero portions. For the saw-tooth generator the lamp 29 shines throughone of two cut-out portions of the disc as indicated at |65; |133. Thus, saw-tooth sweep voltages are produced for alternate quadrants of a rotationV corresponding to the sweep voltages for the quarter revolution of the separate frequencyfbands. The indexing is controlled' from lampisource 25 in cooperation with the'masking portions HIT which serves to produce a pulse voltage of a higher amplitude upon rotation of the shutter. The initiation point of this higher voltage may be changed by varying rotatably the position of lamp 25 relative to the motor shaft. Thus the indexing voltage or indication may bc stepped around to the desired position as shown. I iamp'ZElis` driven simultaneously with the rotation ofA gear 43l so that the indexing indication andthe position of the stopmechanism Will'at all timesproperly coincide.

From the foregoing, the particular apparatus shown in the illustrations of the equipment may be readily understood. 7AWhile the apparatus has been shown for use with a scanning receiver, it should be clear that the stop mechanism may 'ce utilized for any type of system wherein it is desired to stop a motor at a predetermined position in its rotation. Furthermore, the disc and stop mechanism M need not rotate at the same speed as the motor but may be stepped down o-r upwards by similar gear ratios so that the two will rotate together. For the purpose of stopping the motor in proper indexing position, it is essential, however, that the stop mechanism be rotated relative to the tuning band sweep.

It is further clear from the description above that many alternatives to the specic structural arrangement shown in connection with Figs. 2 to 8 may be used if desired without departing from the scope of our invention. Furthermore, more than two stop positions may be provided if desired or a single stop position may be utilized. To those skilled in the art, the modifica tions of the apparatus for achieving the various functions will be clearly evident from the description of the foregoing apparatus.

It should therefore be clearly understood that the description given in conjunction with the specic apparatus shown is made merely by way of illustration and is not to be considered as a limitation on our invention as set forth in the objects thereof and in the appended claims.

We claim:

1. En a frequency scanning receiver, means for adjusting said receiver to a desired tuned position, comprising a motor for scanning the tuning means of said receiver over a predetermined range, an indexing generator controlled by said motor to provide an indexing indication of the desired tuned position, means for adjusting said indexing indication over said frequency range, a detent rotatable with said motor, a stop means rotatable with respect to said detent under control of said means for adjusting said indexing indication, and means for moving said stop means into the path of said detent to stop said motor in the tuned position indicated by said index.

A receiver according to claim 1 wherein said last-named means comprises means for stopping said motor prior to moving in of said stop means, and means for starting said motor at a reduced speed subsequent to movement of said stop means.

8. In a frequency scanning receiver scannable over two frequency bands, means for selectively adjusting said receiver to a desired tuned position in either of said bands, comprising a motor for scan ning the tuning means of said receiver over said two frequency bands, an indexing generator controlled by said motor to provide an indexing indication of the desired tuned position, means for adjusting said indexing indication over the frequency bands, a detent rotatable with said motor, a stop means having diametrically opposed stop surfaces rotatable with respect to said detent under control of said means for adjusting said indexing indication, and means for selectively moving said stop means in either of two directions into the path of said detent to stop said motor selectively in the tuned position with one of said frequency bands indicated by said index.

4. A receiver according to claim 3 wherein said last-named means comprises means for stopping said motor prior to moving in of said stop means, and means for starting said motor at a reduced speed subsequent to movement of said stop means.

5. ln a frequency scanning receiver scannable over two frequency bands, means for adjusting said receiver to a desired tuned position in either of said bands, comprising a motor for scanning the tuning means of said receiver over said bands in succession during each revolution of said motor, an indexing generato-r controlled by said motor to provide an indexing indication of the desired tuning position in both said bands, means for adjusting said indexing indication simultaneously over both said frequency bands, a detent rotatable with said motor, a stop means provided with diametrically related stop surfaces rotatable with respect to said motor under control of said means for adjusting said indexing indication, and means for selectively moving said stop means in either of two directions into the path of said detent to stop said motor in the tuned position within one of said bands indicated by said index.

6. A receiver according to claim 5 wherein said lastenamed means comprises means for stopping said motor prior to moving in of said stop means, and means for starting said motor in the same direction at a reduced speed subsequent to moving of said stop means.

7. In a frequency scanning receiver operative over a frequency band, tuning means for tuning said receiver over said frequency band, a motor drive means for driving said tuning means through said band, an indexing means controlled by said motor for producing an indexing indication, means for adjusting said indexing indication simultaneously over said frequency band to indicate selected tuning positions, a detent means rotated by said motor, a stop means having a stop surface movable into engaging position with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said indexing indication whereby said stop surface will be positioned with respect to said motor in accordance with said indexing indication, and means for moving said stop surface into the path of said detent to stop said motor in tuned position corresponding to the position of said indexing indication.

S. In a frequency scanning receiver operative over a frequency band, tuning means for tuning said receiver over said frequency band, a motor drive means for driving said tuning means thro-ugh said band, an indexing means controlled by said motor for producing an indexing indication, means for adjusting said indexing indication simultaneously over said frequency band to indicate selected tuning positions, a detent means rotated by said motor, a stop means have ing a stop surface movable into engaging position with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said indexing indication. whereby said stop surface will be positioned with respect to said motor in accordance with said indexing indication, means for moving said stop surface into the path of said detent to stop said motor in tuned position corresponding to the position of said indexing indication, means for stopping said motor prior to movement of said stop means into stopping pou sition, and means for starting said motor after said movement of said stop means.

9. In a frequency scanning receiver operative over a frequency band, tuning means for tuning said receiver over said frequency band, a motor toi` simultaneously with adjustment -of said indexing indication whereby said .stop surface will be positioned with respect to said motor in Vaccordance with Isaid indexing indication, means for moving said stop surface l.into lthe .path of said detent to stop said motor in Ttunedposition corresponding to the position .of said indexing indication, and means lfor coupling an audio signal reprcducer to the output of Asaid receiver upon movement of said stop mechanism. Y

l0. In a frequency scanning .receiver Ioperative over more than one frequency band, tuning means .for successively tuning said receiver over said frequency bands, va motor drive means for driving said tuning means through said successive bands for each .revolution of Vsaid motor, an indexing means controlled by 'said motor for vproducing an indexing indication, means for `adjusting said indexing indication simultaneously over said `frequency bands to indicate selected tuning positions, a detentrneans rotated by said motor, a stop means having-stop surfaces correspending to said frequency bands movable selectively into engaging position with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with e. :Eustment of said indexing indication whereby said stop surfaces will befpositioned 'with respect to said motor in accordance withsaid indexing indication, and means ffor moving az'selected one of said stop surfaces into vthe path ofsaid Adetent to stop said moto-r in tuned position corresponding to the position of .said indexing indication in the selected frequency band.

1l. In a frequency scanning receiver operative over more than .one frequency band, tuning means for .successively tuning said receiver over said frequency bands, a motor drive means for driving said tuning means through said successive bands for each revolution, a display indication in the output of said receiver yfor producing a visual display of signals in said frequency bands, an indexing means controlled by said motor for producing an indexing indication, means for adjusting said indexing indication simultaneously over said display indicator for indication-of selected frequencies in said frequency bands, a detent means rotated by said motor, a stop means having stop surfaces corresponding to said jfrequency bands movable selectively into engaging position with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said indexing indication whereby said stop surfaces will be positioned with respect to said motor in accordance with said indexing indication, and means for moving a selected one of said stop surfaces into the path of said detent to stop said motor in tuned position corresponding to the position of said indexing indication in the selected frequency band.

2. In a frequency scanning receiver operative over more than one frequency band, tuning means for successively tuning said receiver over said frequency bands, a motor drive means for driving jsaid `.tuning lmeans through said successive bands .for each revolution, a ldisplay indicator in the'ou'tput of Vsaid receiver for producing a visual display of signals .in said frequency bands, an indexing means controlled by said -motor for producing an indexing indication, means for adjusting said indexing indication simultaneously over said display indicator forindication of selected frequencies in said frequency bands, a detent means rotated by said motor, :a stop means .having stop surfaces .corresponding Vto said frequency bands movable .seloctivelyinto engaging position with respect to .said :'detent, means for rotating said stop means with resp-ect to said motor simultaneously with .adjustment of Said indexing indication whereby saidsstop surfaces ywill be positioned with respect to said motor in accordance with said indexing indication, and means for moving a selected oneof `saidjstop surfaces into the path of said detent to stopsaid motor intunedposition corresponding to the position of said indexing indication in the sellected frequency band, means for stopping said motorl prior to movement of said stop means into .stopping position, and :means for starting said motor at `a lower rate after said movement of said stopmeans.

l13. In a frequency scanning receiver operative over more lthan one .frequency band,.tuning means for successively tuning said receiver over said trequency bands, a motor drive 4means for driving said tuning means .through said successive bands foreach revolution, a display indicator in the output of said receiver for producing a visual display of signals .in said frequency bands, an indexing means controlled by said motor for producing an indexing indication, means fol-.adjusting said-indexing indication.simultaneously over said display indicato-r for indication of selected frequencies ,in said frequency bands, a detent means rotated by said motor, `a stop means having .stop surfaces -corresponding .to said frequency bands movable selectively `into engaging position with `respect to said detent, means for rotating said stop :means with respect to said motor simultaneously with adjustment of said indexing indication Wherebysaid stop surfaces will be positioned with respect-to said motorin accordance with said indexing indicationpmeans for moving a selected one of saidstop surfaces into the path of said detent to stop said motor in tuned position corresponding 'to the position of said indexing indication in `the selected frequency band, and means operative upon `movement of said stop means `.to :couple an audiosignal repro-ducerto the output of said receiver.

'14.111 a frequency scanning receiver operative over two frequency bands, tuning means for `successively :tuning said receiver over said frequency bands, amotor drive means for driving said tuninganeansthrough said Vsuccessive'bands for each revolution, .a visual display indicator for producing separate .displays of received vsignals in said two 4bands, anindexingmeans controlled by said motor for .producing an indexing indication, means for adjusting said indexing indication over said display indicator to indicate the tuning of a selected one of the received signal frequencies within said frequency bands, detent means rotated by said motor, a stop means having di ametrically opposed stop surfaces corresponding to said frequency bands movable selectively into engaging position with resp-ect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said 'indexing indication whereby said stop surfaces will be positioned with respect to said motor in. accordance with said indexing indication, selective means for stopping said scanning in a selected one or said bands, and means responsive to operation of said selective means for moving a selected one of said stop surfaces into the path of said detent to stop said motor in tun-ed posi-tion corresponding to the position of said indexing indication in the selected frequency band.

15. In a frequency scanning receiver operative over two 'frequency bands, tuning means for suc- ;cessively tuning lsaid receiver over said frequency bands, a motor drive means for driving said tuning means through said successive bands for each revolution, a visual display 'indicator for producing separate displays of received signals in said tvvo bands, an indexing means controlled by said motor for producing an indexing indication, means for adjusting said indexing indication over said display indicator to indicate the tuning of a:v

selected one of the received signal frequencies within said frequency bands, a detent means rotated by said motor, a stop means having diametrically opposed stop surfaces corresponding to said frequency bands movable selectively into engaging position with respect to said d-etent. means for rotating said stop means with respect to said. motor simultaneously with adjustment of said indexing indication whereby said stop surfaces will -be positioned with respect to said motor in accordance with said indexing indication, selective means for stopping said scanning in a solected one ol said bands, means responsive to op eration of said seiective means for Imoving a selected one of said stop surfaces into the path of said datent to stop said motor in tuned posi-tion corresponding to the position of said indexing indication in the selected frequency band, and means for maintaining said motor energized at a lower level, whereby the motor will maintain said de'tent in contact with said stop mechanism upon further rotation oi said stop means.

16. In a frequency scanning receiver operative over two frequency bands, tuning means for successively tuning said receiver over said frequency bands, a motor drive means for driving said tuning means through said successive bands for each revolution, a visual display indicatcn` for producing separate displays of received signals in said two bands, an indexing means controlled by said motor for producing an indexing indication, means for adjusting said indexing indication over said display indicator to indicate the tuning of a selected one o the received signal frequencies within said frequency bands, a detent means rotated by said motor, a stop means having diametrically opposed stop surfaces corresponding to said frequency bands movable selectively into engaging position 'with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said indexing indication whereby said stop surfaces will be positioned with respect to said motor in accordance with said indexing indication, selective means for stopping said scanning in a selected one of said bands, means responsive to operation of said selective means for moving a selected one of said stop surfaces into the path of said detent to stop said motor in tuned position corresponding to the position of said indexing indication in the selected frequency band, means for stopping said motor prior to said movement of said stop means, and means for again starting said motor and maintaining said motor energized at a lower level to cause rotation of said detent into engagement with the selected stop surface, and to maintain it in such engagement during further rotation of said stop means.

17. In a frequency scanning receiver operative over more than one frequency band, tuning mean for successively tuning said receiver over said frequency bands, a motor drive means for driving said tuning means through said successive bands for each revolution of said motor, an inn dexing means controlled by said motor for pro-- ducing an indexing indication, means for adjusting said indexing indication simultaneously over said frequency band to indicate selected tuning positions, a detent means rotated by said motor, a stop means having stop surfaces corresponding to said frequency bands movable selectively into engaging position with respect to said detent, means for rotating said stop means with respect to said motor simultaneously with adjustment of said indexing indication whereby said stop surfaces will be positioned with respect to said motor in accordance with said indexing indication, selective means movable into selective positions D for stopping scanning in a selected one of said bands, means responsive to operation of said selective means for moving a carriage mechanism in a selected direction, means responsive to movement of said carriage for successively stopping said motor, moving the selected surfaces of said stop mechanism into the path of said detent, and starting said motor at a reduced speed, whereby said motor Will be iinally stopped in the selected tuning position determined by said index adjustment.

FREDERICK W. FRINl/I.

MURRAY KAPLAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,834,272 Enderwood Dec. 1, 1931 1,894,646 Trogner Jan. 17, 1933 1,906,709 Morin May 2, 1933 2,161,183 Mastney June 6, 1939 2,307,514 King Jan. 5, 1943 2,333,848 Vette Nov. 9, 1943 FOREIGN PATENTS Number Country Date 610,642 France June 14, 1926

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