US1977745A - Remote control system - Google Patents

Description

Oct. 23, 1934. R. E. THOMPSON REMOTE CONTROL SYSTEM Filed Feb, 10, 1930. 3 Sheets-Sheet l INVENTOR Roy E. Thompson 7 p lfiw J- M ATTORNEYS Oct. 23, 1934. R E T N 1,977,745

REMOTE CONTROL SYSTEM Filed Feb. 10. 1950' V s Sheets-Sheet 2 ATTORN EYS Oct. 23, 1934. R. THOMPSON REMOTE CONTROL SYSTEM 3 Sheets-Sheet 3 JIHIIWF Filed Feb- 10, 1930 INVENTOR 19 5. Thompson BY 7 GQ QM I M M ATTORNEYS Patented Oct. 23, 1934 REMOTE CONTROL SYSTEM Roy E. Thompson, Nyack, N. Y., assignorto Thompson Patents Corporation, New York,

N. Y., a corporation of New York Application February 10, 1930, Serial No. 427,370

23 Claims.

This invention relates to remote control systems adapted to produce a desired effect at a given point under control of an operator at a remote point. More specifically, the invention relates to a system of the type specified for use in adjusting from a remote point the tuning element of a radio receiving set.

This invention relates to improvements in the remote control systems for radio tuning disclosed in my copending earlier filed applications, Serial No. 210,780, filedAugust 5, 1927, and Serial No. 292,885'filed July 14th, 1928.

A remote control system adapted to adjust tuning of a radio receiving unit from a remote point, must satisfy certain very definite requirements which clearly differentiates it from remote control systems adapted to perform other funcpoint everything that may now be accomplished by an operator directly manipulating the tuning dials of a receiving set.

Thus it is desirable to have the control systemso operate that the adjustment of a member at the control point in either direction and to any desired extent will immediately cause the tuning element of the receiver to be correspondingly adjusted in the same direction and to the same extent.

It is further desirable that there be provided at a control point an indicating dial operable in synchronism with the tuning elementof the receiver, to indicate at all times the operative position thereof.

A remote control system to function satisfactorily for tuning. a radio receiver must operate so quickly that it is possible to adjust the tuning of the receiver from the control point with substantially the same expedition that a similar result could be accomplished by directly manipulating the dials of the receiver set. Where the control motor for adjusting the tuning element is designed. to accomplish this result, it has been found that due to its inertia it tends .to overthrow its intendedposition of adjustment or to oscillate about such position upon adjusting the tuning from a first to a. second position. Particularly is this the case where the tuning is accomplished in successivesteps by transmission of a series of electrical impulses, since the control motor must be started and stopped a large number of times within a brief time interval.

Especially with this latter arrangement it is essential that means be associated with the control motor to abruptly arrest the movement thereof after each impulse, since otherwise the immediately succeeding impulse may arrive while the motor is out of its proper position of rest, with the resultant eifect that it will either gain or lose a step or even reverse its operation, thereby causing the dial at the control point to get out of synchronism with the tuning element of the receiver.

' At thewontrol point it is necessary that there be embodied in the impulses transmitting mecha nism, a device for insuring that the impulses will not be transmitted to the control motor at a rate too rapid for the latter accurately to follow.

Inasmuch as it is desirable that the indicating dial at the control point be at all times in synchronism with the tuning element of the receiver, some means should be provided for locking the dial in position or otherwise preventing movement thereof when the receiver is not in use and the power is turned off, since otherwise a'manipulation of the impulse transmitting device at the control poiiit would cause operation of the dial without corresponding operation of the con- 80 trol motor.

It is desirable to associate with the control system means for resynchronizing from the control point the dial and the tuning element of the receiver, in case for any reason, these two elements get out of step with one another.

The present invention comprises a remote control system for tuning a radio receiverwhich embodies in a simple, economical and compact. structure all of the features listed above, which features are deemed essential to the satisfactory operation of a system of this sort, as well as a number of other advantageous features as set forth below.

In general the remote control system present invention includes a motor coupled to the tuning element of a radio receiver, the motor comprising a rotor having a multiplicity of pole pieces equally spaced on the periphery thereof, and a stator comprising a multiplicity of electro- 100 magnets positioned around the periphery of the rotor, the angular separation between adjacent magnets considered with a reference to their axes of symmetry or other. points of correspondence thereon, differing from an integral multiple in- 105 eluding zero of the angular separation between adjacent armatures, considered on the same basis, by a fractional amount expressed by the number of magnets into the angular separation of adjacent pole pieces or teeth of the rotor armature. 110

/ of the V In other words, the special relationship between field magnets and rotor pole pieces can readily be expressed by a simple equation, as follows:

where :r=pitch between corresponding field'poles y=spacing between rotor pole pieces z=number oi field magnets n=any integral number including zero.

With such a construction, regardless of the actual positioning of the magnets around theperiphery of the rotor, the effect is as though the magnets' were all concentrated within an angle corresponding to the distance between adjacent pole pieces, the magnets being successively displaced from each other by the fractional amount above referred to.

With such a positioning of the magnetsrelative to the rotor pole pieces, it will be obvious that the poles of but a single magnet at a time can be in alignment with pole pieces of the rotor. Furthermore, if the first magnet of the sequence is thus aligned with rotor pole piece, the second magnet will be one step removed therefrom, the third magnet two steps removed and so on up to the last magnet which will not only be displaced a number of steps equal to the number of magnets less one from the aligned pole pieces, but will also be displaced by a single step from the next adjacent pole pieces.

It results from this that the successive energization of the magnets in one sequence will cause displacement of the rotor in successive steps in one direction of rotation, the rotation continuing so long as the magnets are repeatedly energized in the sequence referred to. Conversely if the magnets are successively energized in the reverse sequence, the direction of rotation of the rotor will be likewise reversed, the displacement thereof occurring in successive steps as aforesaid. The

amount of rotation per step, of course, depending upon the displacement between adjacent pole pieces, and also upon the number of magnets, so that the steps can be made as small or as large as desired by suitably selecting these factors.

It will be seen that a motor of this type is admirably adapted for adjusting the tuning element of a radio receiver, since the steps of rotation can be made just suificiently small on the basis rapidly to substantially. zero on either side of the] band.

. The successive energization of the electromagnets from the control point is accomplished by joining one terminal of the windings thereof to a common lead including a source of power extending to the control point, with the second terminal of each winding connected to the control point over a separate lead.

By providing at the control point a rotary switch having a single rotary contact arm joined to the common lead, anda multiplicity of stationary contacts spaced about the periphery of a The system as described thus far, while operable, will not satisfy the rigid requirements necessary to provide a completely satisfactory remote control system for tuning a radio receiver. As stated, the motor after each successive impulse will, due to the inertia of the rotor element, tend to overthrow or oscillate about its position of rest to a greater or less degree dependent upon the design of the motor. The result is that if the impulses are transmitted too rapidly the rotor is apt to be displaced from the position of rest corresponding to a given impulse when the next succeeding impulse is received, thereby causing the motor to gain or lose a step or even to reverse its direction of rotation. As soon as this occurs, of course, the indicator at the control point gets out of step with the tuning and no longer indicates the true adjustment thereof.

It is, therefore, necessary to associate with the motor some means for insuring that the rotor will be brought quickly and abruptly to rest to complete each step subsequent to the reception of each impulse, and also some means must be associated with the rotary switch at the control point to insure that the impulses cannot be transmitted too rapidly-for the motor to follow the subsequent to each impulse, comprises a substantially aperiodic escapement mechanism consisting of an escape wheel mounted upon the rotor shaft provided with notches spaced corresponding to the steps of the rotor, and preferably, operated pivoted pallet arm having pallets adapted to alternately engage the notches of the escape wheel. A device of this type has the advantage that it provides an instantly operative and powerful reaction for stopping the rotor element to complete each step after each impulse, but at the same time offers a minimumof reaction against starting the rotor again for the next succeeding step. Furthermore the greater the momentum of the rotor as it approaches its position of rest subsequent to an impulse, the greater the reactive force with which the escapement acts to-stop the rotation thereof. Altho the function of the escape- .ment is to stop the rotor after each impulse, it

has the seemingly paradoxical effect of increasing the permissible speed with which the rotor may be actuated. It accomplishes this, of course, by preparing the rotor for the next successive impulse in a much shorter time than would be the case if the escapement were omitted. In this way it is brought about that the rotor will respond correctly to a greater number of impulses per unit time when the escapement is utilized.

It is to be. pointed out that the term escapemen used herein is understood to define the specific mechanical contrivance which connects a oscillation. The expression escapement originates from the fact that it allows a tooth of the wheel to escape from a pallet at regular intervals, while at the same time the motion of the wheel is arrested until the oscillation of the pendulum or balance is completed.

At the control point a second escapement is associated with the rotary switch, the function of which is to limit the speed with which the contact arm of the switch may be rotated, to such a value that the motor can successfully follow the impulses transmitted. This escapement likewise comprises a notched escapement wheel mounted upon the axis of the switch arm, coopcrating with a pallet arm adapted by inertia means to have a definite periodicity of vibration which cannot easily be exceeded, since the inertia of the device acts powerfully to prevent any attempt to exceed this upper limit.

Having now described the control system in general terms, reference will be had to the drawings for a detailed description of a specific em-.

bodiment thereof which has been found to give quite satisfactory operation in practice. Referring to the drawings:

Fig. 1 shows in circuit diagram form a remote control system in accordance with this invention.

Fig. 2 shows a modified form wherein an electrically operative escapement mechanism is associated with the motor.

Fig. 3 shows another modification wherein the motor may be operated from any of a multiplicity of control points, each of whichjs permanently equipped with a control device for transmitting pulses to the motor.

Fig. 4 is an elementary drawing showing a proposed use of the invention as applied to an automobile.

Referring to Fig. 1 the controlling unit A located at the control point, is connected by means of a cable containing conductors 5 to the controlled motor B located adjacent the radio receiving chassis, being mounted preferably in the same cabinet therewith.

The motor B comprises a rotor C of magnetic material having a multiplicity of radially projecting pole pieces 1 evenly spaced on the peripherythereof; and a stator consisting of the bipolar electro-magnets M1, M2 and M5 symmetrically positioned around the rotor.

Each pole face of a magnet M is provided with one or more teeth 2'dimensioned and spaced corresponding to the pole pieces of the rotor, a pur pose of providing more than one tooth per pole face being to increase the tractive force exerted by the magnet on the rotor for a given axial di- "mension of the rotor. The poles of a given magnet must, of course, span an integral number of rotor teeth in order that both poles be equally efiective in exerting a force on the rotor.

The motor B satisfies the rule laid down above relative to the angular separation of the magnets as compared to the angular separation 01 the rotor pole pieces, the former separation being 5% that of the latter in the present instance. Inasmuch as each rotor pole piece is dimensioned to subtend an angle equal to n the angular 'separation or pitch of the rotor pole pieces, it results that when certain of the rotor pole pieces are aligned with teeth of a given magnet as shown for'magnet M1, the remaining magnets will be respectively displaced in opposite directions of rotation by the width of one rotor tooth from the aligned condition.

Accordingly if the magnets are successively energized in one sequence as M1-M2-Ma. the rotor will be rotated clockwise in successive steps; whereas if the sequence of energization is reversed to the order Ma-Mz-Mn the rotation of the armature will be counterclockwise in successive steps.

Therotor pole pieces need not necessarily be dimensioned as indicated above, altho a motor constructed as indicated in Fig. 1 has been found to operate quite satisfactorily in practice. The mark aimed at in selecting the width of the rotor pole pieces, is to obtain a motor which will.

' advance most quickly in successive steps responsive to the magnet energizations.

Each magnet is provided with an energizing winding 3, one terminal of which is connected to a terminal of a battery 4 for energizing the same, the opposite terminal being connected over a conductor individual thereto to the control point. A conductor likewise extends from the opposite terminal of the battery 4 to the control point, the four wires in question constituting the conductors 5.

At the control point the common lead from battery 4. makes contact thru a brush 6 with a rotatable conductive disc '7 constituting the movable element of, a rotary switch. The disc 7 is provided with projecting teeth evenly spacedon its periphery. A group of three resilient stationary contacts 8 are so spaced relative to the spacing of the disc teeth, that as the disc is rotated clockwise, contact is made in succession with the contacts 8 beginning with that at the right and ending with that at the left. When the direction of rotation of the disc is counter-clockwise, the order of contacting the elements 8 is, of course, reversed.

Thecontacts 8 are joined respectively to the individual leads 5 extending to the windings 3 of magnets M whereby upon contact of the disc '7 with a contact 8, a circuit is completed thru battery 4 and winding 3 of the magnet in question to energize the same. The order of connecting the conductors 5 to the contacts 8 is such that rotation of the disc '7 in eitherdirection will successively energize the magnets in proper sequence to operate the motor in synchronism with the disc. Thus as the disc is rotated clockwise by turning the knob 9 mounted on the shaft common tov the disc, the motor will also rotate clockwise and vice versa if the knob 9 is oppositely rotated.

The rotor C of the motor drives the adjustable tuning element of the radio receiver such as the shaft of the variable condenser K thru suitable gears 10 mounted upon the rotor and condenser shaft respectively. At the control point a dial H is so geared to the shaft upon which the rotary switch is mounted, as to operate in synchronism with condenser K. The dial H is provided with a suitable scale operating under a stationary pointer 11 to indicate the adjusted position of the condenser. The gear teeth are omitted froma portion 12 of the dial tolimit the but in case the mechanism fails to function pr'op- 15o erly, means are provided whereby at any time the resynchronization of the two elements may be effected from the control point. To this end the gear 14 is mounted to ride freely upon the condenser shaft, but is ordinarily prevented from rotating with respect .thereto by means of the frictional clutch 15 comprising a resilient-strip aflixed at one end to the condenser shaft with the opposite end supporting a frictional washer of rubber or the like, snugly against the-face oi gear 14. The spring tension is so adjusted that normally no slippage occurs, so that the gear and condenser shaft rotate as a unit.

If, for any reason, therotor element of the condenser gets out of step with the dial indicator, thetwo elements may be resynchronized by rotating the knob 9 first in one direction until the d.al reaches its extreme adjustment in that direction as determined by the portion 12, whereupon the knob 9 is rotated in the oppose direction until the dial reaches its opposite extremity of rotation. During one or the other of these rotations of knob 9, the lug 13 afiixed to the rotor plate of the condenser will strike against the fixed plate before the dial arrives at its extreme position, on the assumption of course, that the condenser is out of step with the dial setting.

During the remaining movement ofthe dial to .its extreme position, the condenser shaft cannot follow the corresponding rotation of the motor due to contact between lug 13 and the fixed condenser plate. The result is that slippage occurs between clutch 15 and gear 14 whereby the condenser is maintained at its extreme setting until the dial is likewise adjusted to its corresponding limiting position toresynchronize the elements.

Even with the most carefully constructed motor, it is impossible to entirely eliminate the tendency of the rotor to overthrow or oscillate about its ultimate position of restin completing each step. As a result if the impulses are transmitted too rapidly, the rotor is apt to be displaced from its position of rest responsive to the actuation of a preceding impulse when the nextimpulse arrives. Dependent uponthe position of the rotor at such an instant it will gain or loose a step or even reverse direction momentarily.

To avoid this condition an escapement 16 is associated with the shaft of the motor B, and a second escapement 17 provided at the control unit A. The escapement 16 comprises a notched escape wheel 18 rigidly afiixed to the rotor shaft, and a pallet arm 19 pivotally aflixed to a separate support in such manner that as the escape wheel 18 rotates the pallets 20 and 21 alternately engage the notches therein. The notches in the escape wheel are, of course, spaced corresponding to the steps of the motor B.

Since the reaction of the pallet against movement of the escape wheel is due solely to its inertia, it will be obvious that the escapement will present a minimum reaction against the starting of the motor at the commencement of an impulse due to the fact that thevelocity is increasing from zero to a maximum. On the other hand, at the termination of an impulse the pallet arm and rotor having each attained considerable momentum imparted thereto upon initiation of each step, a notch of the escape wheel will strike a pallet with such suddenness thatthe inertia of the latter will build up a strong reactive force neutralizing the 'kinetic energy of the rotor'and bringing it abruptly to rest. The escapement, therefore, increases the" permissible speed of operation of the motorsince it decreases the time required to bring the rotor completely to rest'after each impulse, and thus prepares the motor in a shorter time interval for reception of the next impulse. In practice it has been demonstrated that the addition of the escapement increases the permissible operating speed to a surprising degree.

I The escapement 17 on the other hand is a speed limiting device, its function being to prevent rotationof the knob 9 at a rate too rapid for the motor 13 accurately to follow the impulses transmitted. To accomplish this the pallet arm 22 has amxed at right angles thereto, a bar 23 weighted at the ends to give the pallet arm a desired limiting periodicity of vibration. The pallet arm is pivotally supported at a point 24 intermediate the outer point of aflixment of a spring 25 to the pallet arm extension and the inner point of afflxment thereof to the shaft upon which is mounted the escape wheel 26.

As the knob 9 is rotated, the spring 25 assures positiveengagement of the pallet anvils alternately with the notched escape wheel 26. When the knob 9 is rotated at low speeds, the oscillation period of the pallet arm 22 is considerably below the natural periodicity'of the bar 23, so that the latter exerts little reaction in. limiting the speed of rotation. When, however, the speed of rotation is such that the periodicity of vibration of the pallet arm approaches the natural periodicity of the bar 23, the latter is thrown into violent vibration causing the pallets to engage the escape wheel notches with considerable force at intervals corresp'ondingto this natural periodicity of vibration, whereby a braking actionis obtained which eifectively limits the maximum rotative speed of the switch.

A switch 27 is provided in the common lead extending from battery 4 for rendering the system inoperative when the set is not in use. During such intervals it is, of course, essential that the knob 9 should not be rotatable, otherwise the dial H will get out of step with the condenser setting, inasmuch as rotation of the knob at such time will cause no impulses to be transmitted to the motor. Accordingly, a locking device is provided which operates to lock up the control unit'while switch 2'7 is open.

The locking device comprises a relay 28 in series with switch 27 the relay, of course, being energized only while the'switch is closed. The relay during energization attracts armature 29, which is pivotally supported at its lower end, against the tension of the restraining spring 30 thus withdrawing the pin .31 afllxed to the armature from engagement with lug 32 formed on the pallet arm 22, thereby permitting operation of the control switch.-

Upon opening switch 27, however, the release of relay 28 in turn releases the armature, caus ing pin 31 to engage lug 32 to lock one of the pallets into a notch of escape wheel 26, to pre-- vent'further operation of the control switch. At the receiver the bearing friction for the control denser, and inasmuch as it is intended that no adJusting knobs be provided on the receiver panel,

it is thus assured that the dial and,condenser ing to withdraw anvil 20 and thus cause the cycle.

not realese during the current interruptions caused by operation of switch 7.

If desired the conductors 5 may be multipled at a plurality of control points, a control unit being permanently provided at each such point for tuning the receiver; or the conductors may terminate at each such point in jacks 33 and 34 as shown in the drawings, and a single control unit A provided, the leads from which terminate in a plug 35 adapted to engage the jacks. The control unit may thus be easily carried about and plugged in at any desired jack for tuning the re! ceiver. Where this is the case the locking device above described insures that the dial setting will always correspond to the condenser setting when the control unit is thus plugged in. The plug 35 and jacks 33 and 34 are so constructed, as indicated in the drawings, to insure that the conductors extending from the control A. will be oonnected'in proper sequence to the conductors 5.

Fig. 2 shows a modified form of the invention wherein the motor B is provided with four bipolar stator magnets symmetrically positioned. about the rotor.

The control A is similar in construction and. operation to that of Fig. l, the rotary switch being shown in elementary form for simplicity as comprising a single rotary contact arm 7 adapted to make contact in succession with terminals 8 each of which is connected to a separate magnet M in such manner that they will be energized in proper sequence. The motor B is in this instance provided wit an electrically operated escapement lS, the pallet arm 19 being of magnetic material for actua-' tion by the magnets N1 to N4 inc. I

Each magnet N is in series with the like subnumbered stator magnet M, the magnets .N con- 1 sidered in sequence being arranged alternately on opposite sides of the pivotal support for pallet 19, since the pallets must alternately engage the escape wheel as the rotor teeth pass under successive magnets M.

The purpose of the magnets N is to remove any inertia or retarding effort due to the reaction of the pallet arm against starting of the escape wheel 18 at the beginning of a pulse, and also to provide a more positiveaction to stop the rotorat the end of a pulse than is obtainable with the inertia type escapement of Fig. 1.

This action is explained as follows: Assume with the rotor Cv in the position shown, magnet M2 is next energized at the same time energizing magnet N2 in series therewith. Now it will be seen that the energization of magnet N2 by withdrawing anvil 21 from engagement with the escape wheel will thereby prevent the pallet arm from exerting any retarding effect on the operation of the rotor. At the same time that anvil 21 is being thus forcibly withdrawn from the escape wheel, anvil 20 is concurrently being forcibly injected into a notch of the wheel thereby speeding up its rotation until the anvil 20 is perfectly seated within the notch being held there momentarily by the attractive force of magnet N; on the pallet arm, until motion of the escape wheel abruptly ceases. -Magnet N3 is then energized along with magnet M3, the former servfectively when the magnets N are omitted as well as when they are energized as described above.

Fig. 3 shows a modification of the invention wherein a multiplicity of control units are provided from any one of which the tuning of the receiver may be adjusted, the dial indicator of such unit and of all of the other units being operated in synchronism with the tuning element of the receiver, so that an observer at any control point. may know immediately the operative to which the receiver is adjusted.

The control motor B coupled to the tuning con,- denser which is shown in the very elementary form with the escapement omitted for convenience, operates on the same .principle asthe motors of Figs. 1 and 2. Each control. unit A is provided with a rotary switch D for transmitting impulses, preferably similar in construction to that of Fig. 1, but shown schematically as in Fig. 2. The dial H is in each case geared to a motor F thru a frictional clutch arrangement 15' for purposes of synchronization, the clutch in each case being similar to that shown at 15 by means of which the condenser K is coupled to the motor B. Each motor F is a very small elementary motor operating on the same principle as. motor B. The conductors extending from each dial D to the corresponding motor F pass thru contacts of a switch E. The arm 40 of the switch which is pivotally supported at 41 is normally in the inclined position shown for switch E1, whereby the switch contacts are maintained open, so that operation of the dial D, will cause no impulses to be transmitted to the motors.

If it is desired to tune the condenser from a given control point A, the corresponding switch E is operated to a horizontal position as shown for switch E2 whereby the conductors from dial D2 are closed thru to the motor F2 and similarly over conductors 42 to motors F1 and B. As soon as switch arm E is operated to a horizontal position circuits are completed to operate all of the magnets P associated with switches E. The operating circuit for each such magnet is traced from the upper terminal of battery 4, thru the winding of'magnet P in question, thru a winding of the associated motor F and back to the lower terminal of the battery 4 thru contacts of the operated switch E and the associated dial D.

I The operation of magnet P2 attracts armature R2 against the restraining tension of spring 43 until the armature engages the switch arm 40 locking the arm in its operated position due to the projecting lug 44 formed upon the armature passing over the upper edge 01' the switch arm.

At the same time the operation of the remaining magnets P serve to lock-the corresponding switch arms 40 in the non-operated position due to the engagement of the projecting lug 44 with a notch 45 in the switcharm. This condition is shown for switch E1.

As a result of this arrangement it becomes impossible to transmit impulses from more than one dial D at a time, namely, from the dial associated with the operated switch E. I

When the operator at control unit A: desires to restore the mechanism, the handle of switch 40 is forcibly depressed against the restraining action of magnetic attraction of the magnet upon the armature, until the end of the switch arm rides free of lug 44. As a result of this operation, the breaking of the switch contacts atEz, opens the operating circuits of all the magnets P which thereupon release, thereby placing the system under control of an operator at any control point.

The magnet windings of all the motors having one terminal in each case joined together to the upper terminal of battery 4, with the remaining winding terminal for corresponding'magnets on each motor being connected to a different contact of each of the rotary switches D thru contacts of switch E, the contact arms 7 of switches I) being in turn joined together to the lower terminal of battery 4, it follows that the operation of any dial switch D with the corresponding switch E closed, will cause all of the motors F and B to operate in synchronism.

Motor B, of course, adjusts the tuning condenser K, while motors F adjust the dials H in synchronism therewith to indicate at all times the operative position of the condenser. Thus an indicator is provided at each control point which shows at all times the adjustment of the tuning condenser, irrespective of the control point from which its adjustment is made.

Should the dials get out of synchronism with each other or with the condenser, the entire sys-- tem may at any time be resynchronized from any control point by closing the switch E thereat and rotating the switch D first in one direction of rotation until the corresponding dial H reaches its extreme setting, whereupon the direction of rotation is reversed until the dial Hrreaches its opposite extreme setting. It any dial or the condenser is out of step it will reach its extreme setting prematurely, during one or the other of these opposite rotative operations, after which the frictional clutch 15 associated therewith will be caused to slip until the dial at the impulse transmitting station has reached its extreme set ting in that direction of rotation. By carrying out the operation in both directions of rotation as stated, all elements will necessarily be resynchronized irrespective of their displacements relative to that of the dial at the impulse transmitting station.

No difficulty is encountered from the fact that the contact arm 7 of a switch D when placed in operation does not rest upon the terminal corresponding to the position of the contact arm of the switch D last used. If the positions do correspond nothing will occur when switch- E of the newlyselected control point is closed. If the positions at that time do not correspond, then all of the motors will merely advance a step in the proper direction to make the position of the rotors correspond to the position of the contact arm '7 at the switch E last operated.

Fig. 4 showsthe invention as embodied in an automobile equipped with a radioreceiving set. The receiving set 50 may be located under the front seat as shown, or at any other convenient point. Wires extend from the receiver to a loud speaker 51 mounted upon the inner rear wall of the front seat, the speaker being preferably shielded from view by a sound transmitting screen 52 woven of copper wire or the like. Conductors 53 also screened from view extendfrom the receiver to a remote control unit A1, similar to that of Fig. 1, which is located upon the instrument panel of the car so that the driver may easily adjust the tuning of the receiver. If desired a second control unit Ar may be located within easy reach of an occupant in the rear seat of the car.

I claim:

1. In a remote control system for tuning a radio receiver, a motor having a stator, and a rotor coupled to a tuning element of said receiver for adjusting the same, said rotor being operable in either direction of rotation in successive steps responsive to electrical impulses transmitted from a control point,'conductors connecting said motor thereto, escapement means associated with said rotor for abruptly arresting the motion thereof to complete each step, a source of current, and means at said control point for trans.-

mitting said impulses.

2. In a remote control system for tuning a radio receiver, a motor having a stator, and a rotor coupled to a tuning element of said receiver for adjusting the same, said rotor being operable in either direction of rotation in successive steps responsive to electrical impulses transmitted' from a control point, conductors connecting said motor thereto, escapement means associated with said rotor for abruptly arresting motion thereof to complete each step, a source of current, and means at said control point for trans itting said impulses, and an indicator at said vcontrol point operable in synchronism with said tuning element.

3. In a remote control system for tuning a radio receiver, a motor having a stator, and a rotor coupled to a tuning element of said receiver for adjusting the same, said rotor being operable in either direction of rotation in successive steps responsive to electrical impulses transmitted ,from a control-point, conductors connecting said motor thereto, escapement means associated with said rotor for abruptly arresting motion thereof to complete each step, a source of current switching, means at said control point for transmit-. ting said impulses, an indicator at said control point operable in synchronism with said tuning element, and escapement means associated with said switching means for preventing transmission of said impulses at too rapid a rate for said motor to accurately follow.

4. In a remote control system for tuning a radio receiver, a motor having a stator, and a rotor coupled to a tuning element of said receiver for adjusting the same, said rotor being operable in either direction of rotation in successive steps responsive to electrical impulses transmitted from a control point, conductors connecting said motor thereto, escapement means associated with said rotorfor abruptly arrestingmotion thereof subsequent to each pulse in preparation for the succeeding impulse, a source of current, and means at said control point for transmitting said impulses, an indicator at said control point operable in synchronism with said tuning element, a switch at said control point for rendering said system inoperative, 140 and means controlled thereby for preventing operation of said indicator during such intervals.

5. In a remote control system for tuning a radio receiver, a motor having a stator, and a rotor coupled to a tuning element of said receiver for adjusting the same, said rotor being operable in either direction of rotation in successive steps responsive to electrical impulses I transmitted from a control point, conductors connecting said motor thereto, means associated with said rotor forquickly arresting motion thereof subsequent to each impulse in preparation for the succeeding impulse, a source of current, and means at said control point for transmitting said impulses, an indicator at said control point normally operable in synchronism with said tuning element, means individual to said indicator and tuning element for limiting the tiplicity of holes evenly spaced about the periph- ,ery thereof, said stator comprising a multiplicity of electromagnets disposed about said rotor being separated by an amount which differs from an integral multiple of the angular separation of adjacent poles by an angle expressed as the number of magnets into said angular separation of adjacent poles, whereby said rotor may be advanced in successive steps in either direction of rotation dependent upon the sequence of energization of said magnets, leads separately connecting said magnet windings to a control point, pulse transmitting means thereat controlling a current source for energizing said magnets in either said sequence, frictional clutch means connecting an adjustable tuning element of said receiver with said rotor, an indicator controlled by said pulse transmitting means and operable in synchronism' with said tuning element, means for limiting adjustment of said indicator and tuning element at corresponding settings in both directions of rotation, said limiting means being adapted to cooperate with said clutch means for resynchronizing by means of said switch, said indicator-and tuning element when required.

7. A remote control system for tuning a radio receiver, comprising a motor coupled to a tunin element of said receiver, said motor being operable in successive steps in either direction of rotation responsive to electrical impulses transmitted from a control point, leads connecting said motor to a multiplicity of such control points, a similar motor at each such point for operating a dial coupled thereto in synchronism with said receiver tuning element, impulse transmitting means at each said control point controlling a source of current for simultaneously transmitting impulses to all said motors.

8. A remote control system for tuning aradio receiver, comprising a motor coupled to a tuning element of said receiver, said motor being operable in successive steps in either direction of rotation responsive to electrical impulses transmitted from a control point, leads connecting said motor to a multiplicity of such control points. a similar motor at each such point for operating a dial coupled thereto in synchronism with said receiver tuning element, impulse transmitting means at each said control point controlling a current source for simultaneously transmitting pulses to all said motors, and additional means at each control point including a switch and a relay for placing said remote control system under exclusive control of said impulse transmitting means at a desired control point.

l 9'. A remote control system for tuning a radio receiver, comprising a motor'coupled to .a tuning element of said receiver, said motor being operable in successive steps in either direction of rotation responsive to pulses transmitted from a control point, conductors connecting said motor to a multiplicity of such control points, a similar motor at each such point for operating a dial coupled thereto in synchronism with said receiver tuning element, pulse transmitting means at each said control point controlling a current source for simultaneously transmitting pulses to all said motors, additional means at each control point including a switch and a relay for placing said remote control system under exclusive control of said pulse transmitting means at a desired control point, frictional clutch means interposed between each said motor and the aforesaid element driven thereby, means associated with all said elements for lim.ting the adjustment thereof at corresponding points in both directions of adjustment, said means being adapted to cooperate with said clutch means for resynchronizing all said elements when required under control of said pulse transmitting means at any said control point.

10. In a radio system provided with remote tuning control, a motor having a stator, and a rotor responsive to electrical impulses transmitted from a control point, conductors connecting said motor thereto, means associated with said rotor for quickly arresting motion thereof subsequent to each impulse in preparation for the succeeding impulse, a source of current, means at said control point for transmitting said impulses, an indicator at said control point normally operable in synchronism with said tuning element, means individual to said indicator and tuning element for limiting the range of adjustment thereof at corresponding settings in both directions of adjustment, said limiting means being adapted to cooperate with clutch means coupling said rotor and tuning element for resynchronizing said indicator and tuning element when required, and means associated with said impulse transmitting means for preventing transmission of said impulses at too rapid a rate for said motor accurately to follow.

11. In combinationfa step-by-step motor responsive to electrical impulses comprising fixedand movable elements, and means including a pivoted substantially aperiodic reciprocatory member receiving momentum upon initiation of each step, and thereafter utilizing said momentum abruptly to arrest said movable element to complete said step enabling thereby said movable elements to respond precisely at a relatively high rate.

12. In combination, a motor comprising a stator adapted to act magnetically upon an associated rotor for'advancing said rotor in steps responsive to electrical impulses, and means including a pivoted substantially aperiodic reciprocatory member receiving momentum upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to complete said step enabling thereby said rotor to respond precisely at a relatively high rate. I

13. In combination, a motor comprising a stator adapted to act magnetically upon an associated rotor for advancing said rotor in steps responsive to electrical impulses, and escapement means including a pivoted substantially aperiodic reciprocatory member receiving momentum from said rotor upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to complete said step enabling thereby said rotor to respond precisely at a relatively high rate.

14. In combination, a motor comprising a I stator adapted to act magnetically upon an associated rotor for advancing said rotor in steps re-' sponsive to electrical impulses, and escapement means including a pivoted substantially aperiodic reciprocatory member receiving momentum from said rotor upon initiation of each step and thereafter utilizing said momentum to arrest said rotor to complete said step enabling thereby said rotor to respond precisely at a relatively high rate.

15. In combination, a motor comprising a rotor having peripherally spaced pole pieces, and a stator of electromagnets spaced with reference to said pole pieces for advancing said rotor in steps responsive to successive energizations of said electromagnets, and escapement means including a pivoted substantially aperiodic reciprocatory member receiving momentum upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to complete said step enabling thereby said rotor-to respond precisely at a relatively high rate.

16. In combination, a motor comprising a rotor having peripherally spaced pole pieces, and a stator of electromagnets spaced with reference to said pole pieces-for advancing said rotor in steps responsive to successive energizations of said electromagnets, and escapement means including a pivoted substantially aperiodic reciprocatory member receiving momentum from said rotor upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to complete said step enabling thereby said rotor to respond precisely at a relatively high rate.

17. In combination, a reversible motor comprising a stator adapted to act magnetically upon an associated rotor for advancing said rotor in steps responsive to electrical impulses, and escapement means including a pivoted substantially aperiodicreciprocatory member receiving momentum upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to completesai'd step thereby allocating said rotor statically receptive of successive impulses ena-' bling thereby said rotor to respond precisely at a relatively high rate.

18. In combination,.a motor comprising a rotor having peripherally spaced-pole pieces, and a stator of electromagnets. spaced with reference to said pole pieces for advancing said rotor in steps in either direction of rotation dependent upon the sequence of energization of said electromagnets, and escapement means including a pivoted substantially aperiodic reciprocatory member receiving momentum upon initiation of each step and thereafter utilizing said momentum abruptly to arrest said rotor to complete said step thereby allocating said rotor statically receptive of successive electromagnetic energizations'and enabling thereby said rotor to respond precisely at a relatively high rate.

. 19. In combination, a motor comprising .a

stator adapted to act magnetically upon an associated rotor for advancing said rotor in steps responsive to electrical impulses, and escapement means comprising a toothed-wheel mounted on the rotor shaft cooperating with a pivoted pallet arm abruptly to arrest said rotor to complete each step thereby, said rotor being enabled to. respond preciselyat a relatively high rate.

20. In combination, a motor comprising a rotor having peripherally spaced pole pieces, and a stator of electromagnets spaced with reference to said pole pieces for advancing said rotor in steps responsive to successive energizatlons of electromagnets, and escapement means comprise ing a toothed-wheel mounted on the rotor shaft cooperating with a pivoted pallet arm to arrest said rotor tocomplete each step thereby, said rotor being enabled to respond precisely at a relatively high rate.

21. In a remote control system, a motor comprising a rotor having peripherally spaced pole pieces, and a stator of electromagnets spaced with reference to said pole pieces for advancing said rotor in steps in either direction dependent upon the sequence of energization of said electromagnets, escapement means for abruptly arresting said rotor to complete each step, connections from said electromagnets to a control point, and electrical impulse transmitting means thereat for energizing said electromagnets in either said sequence.

22. In a remote control system, a motor comprising a rotor having peripherally spaced pole pieces, and a stator of electromagnets spaced with reference to said'pole pieces for advancing said rotor in steps in either direction dependent upon the sequence of energization of said electromagnets, escapement means for abruptly arresting said rotor to complete each step, connections from said electromagnets to a control point, electrical impulse transmitting means thereat for energizing said electromagnets in either said sequence, and means associated with said transmitting means for preventing the transmission of said impulses at a rate too rapid forsaid motor accurately to follow. 7

23. In a remote control system, a motor comprising a rotor having pole pieces peripherally spaced at constant pitch, and a stator of electromagnets disposed about said rotor at angular spacing which differ from an integral multiple of the angular separation of adjacent pole pieces by an angle expressed as the number of magnets into the angular separation of adjacent pole pieces, whereby said rotor may be advanced in successive steps in either direction of rotation dependent upon the sequence of the energization CERTIFICATE or CORRECTION.

Patent No. 1,977, 745. October 23, 1934.

- ROY 12. THOMPSON.

it is hereby certified that error appears in the printed specification of the above numbered patentrequiring correction as follows: Page l, line 110, strike out the words "or teeth of the rotor armature"; page 2. line 25, for "piece" read pieces; and page 8, line 126, claim 23, for "spacing" read spacings; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of February, A. D. 1935.

Lesl i Frazer (Seal) Acting Commissioner of Patents.

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