US2263641A - Synchronizing system - Google Patents

Description

NoxnZS,v 1941. A. McLfNlcoLscN 2,253,641 l sYNcHRoNIzING SYSTEM l m Driginal Filed May '7, 1928 2 Sheets-Sheet 1 52 PHE/VER HND FIL TER .NIH

f xNvEN-roR ATTORNEYS l Nov. 25', 1941'. AjMcL. |-ucoLsol-1 2,263,641 r SYNGHRONIZING SYSTEM w Originl Filed May f7, 1928 2 Sheets- Sheet 2 I mire/ven HND F/L TER Loca sla/w11.

@Elven/1 lm/f HMI? . ATToRNES Patented Nov. 2 5, f Y

4UgNIiEl) STAT signor to mm ES qPME A meniem x1-emes Alexander Menem mussen, New verk, N. r., 'aeunition Patenti,

poration oilielavnre Incsacorf chronizing the operation of a plurality oi de vices situated' at spaced apart locations and more particularly relates to systems for synchronizing the operation of television and facsimile transmittersand receivers. This is a division of applicationseral No. 275,672, led May '1, 1928,--

nOW'Patent No. 2,197,005, dated April 16, :1940.

Inor'der for a television system to be capable of wide and efectiva use, the apparatus should require no greater intelligenceand skill on the part of the operator than can be-exercised by the average person, as clearly it is impractical to I sequencaeach trame being repeatedly scanned number of picture elements scanned in a unit ottime and in a predetermined` patterny or at the rate of v16 to 18 frames per second. -If the scanners .at the receiver and transmitter are operating at the samespeed and pass corre- Y sponding points in the frame of reference at the require a highly skilled operator at everysta-` Y tion, as for instance at every receiver in a television broadcasting system..

The operation of a receiver controlled in speed by a distant transmitter presents two principal difiiculties. First, there is the .dificulty` of maine' taining exactly the same speed at both stations,

' and secondly, there is the diiliculty o f bringing e the scanning apparatus mechanically in .step at beth stations es wen. This lattervdimmntymey result in parts of the received image being dis- `placed with respect to the other parts. For

example,`if thescanning apparatus is operating at exactly the same speed at the transmitting station and at the receiving station, and if, the receiving scanner is half way across the screen at the instant the 'transmitting scanner is operating on the `b'egirming of the image, it will beV apparent thatat the receiver, the image will be cut in half and thetwo halves transposed in position-L ,o

Itis clear that sincethere is only one space position of the receiving scanning apparatus relative to the transmitting scanning apparatus same time, the received image will at all times be properly placed in its frameof reference or 4erronea."

It isan object Vof this invention to provide a synchronizing system in which the synchronizing at one o1'- more stations iscontrolled by a master source of synchronizing currents,

It is a further object of this invention to provide a synchronizing system in which a plurality of elements at d iiierent-stations may `be caused to operate at the same or synchronous speed, Vand vto take and maintain thesame relative position,

'regardless of a difference in position at the be- -oI operation, or`at any time therein. It is still a iurtherobject of this .invention to provide va synchronizing system in which devices which will be correct, when synchrony is'established, and there are many possible positions which will be' incorrect, some means should be- 49 at any station may be set into operation and synchronized with a master lsource o1' synchroniz-v ing currents inthe same relative position in each station without the necessity of manual adjustments. A

Still other objects and advantages oi my inventloncwill be apparentfrom the speciiication. l

In accordance with the present invention, I

provide apparatus for transmitting periodic impulses orsignals of" some sort at definite timeA intervals representing deiinite space positions of the transmitting scanner, and I provide at the receiver apparatus such that if these signals are received at times when the receiving scanner is in an incorrect position, then the receiving scan-Y ner is caused to accelerate or retard asthe case provided which will not only cause the receiving apparatus to come to synchronous speed, but which will also cause the receiving apparatus to run `faster or slower than the transmitting scanning apparatus, until it occupiesvthe same lposition relatively to the image, and whenA this identity` ofrela'tive position is attained. syn--V such signals; when` this condition is reached, .the

chronous speed is to be maintained; and further-"` more, should the receiver and transmitter get Y out er sheathey must lee-brought nac; inV step, and the receiver again brought to. synchronous speed.

The images tbe 'considered as iixed within what I term a- `-at transmitterv and receiver maymay be, until the space position of the receiving' scanner iscorrect at the instant of receipt oi accelerating or retarding, force rendered inoperative or ineiective, aslong as the condition obtains` 1 e For a better understanding o'f the invention referenceLmay be hadY to the dl'willgs, in which:`

Figure 1 is a circuit diagram of a transmitter 5 rer transmitting signaleA eentremng iight 1nt 21s a circuit diagram of a receiver adapted for operation on signals received from frame .of reference, and each a large n apparams such as shown Figure 1';

desired accompanying speed and' :position of a receiving l as will be understood.

Figurel in which I designates diagrammatically -f a generator driven by any suitable prime mover,

' and generating currents of the desired frequency for operating motor. Il, which in turn operatesscanning apparatuslof any suitable type, such as herein shown and described, or any other form ofscanner known in the art. The apparatus for sending a signal at predetermined recurrent points, representing definite space positions of the scanner, I term a metronome, and the signal transmitted thereby I term the metronome signal.

The metronome comprises a suitable source of high frequency currents, such as a vacuum tube oscillator I1, from one terminal of which a connection passes to coil I8, thence to the shaft I2, which drives the scanning apparatus. Mounted on shaft I2 I provide a-suitable device for pev riodically closing a circuit through source I1 .and

coil I8. In the form shown, this may comprisey conducting disk I3 providedon its periphery with a coating of insulating material except at point I5. Engaging the periphery of disk I3,.IV may provide a contact nger or brush. I6.

It will be seen that in the 'operation ofthis' arrangement, coil I8 is momentarily traversedA by high frequency oscillations at the instantthat conducting point l passes under contact I 6, and this may be arranged to take place at the inmodulations upon separate carrier frequency oscillations which in turn may be used to modulate the carrier frequency of the station. Since the particular apparatus for modulating carrier oscillations, which modulated oscillations are in turn used to modulate another carrier, is well known in the art, it is not described in detail.

It will be understood that the signal radiated from the antenna 24 comprises three components: (1) the componentindicating `the value of light intensity at a particular time at the transmitter; (2)y the currents representing the frequency of the motor generator system I0 vand II; and', (3) signals representing the passage of the transmitting scanning apparatus over a particular point of the frame of reference, and while I lhave indicated a method' and apparatusv for transmitting all `of these signals of a similar carrier wave, it will be apparent that diiiiculties of modulation and separation may be avoided if desired, by transmitting each of these signals as modulations of separate carrier waves, 4each transmitted from a separate antenna or radiating system. .A

Referring now more particularly to Figure 2, I have shown diagrammatically one form of receiving apparatus, which I term a vsynchronome, adapted to operate in response to signals transmitted from asystem operating as just described. In this arrangement, represents an antenna providedwith inductance 3|, shunted if desired, by a tuning condenser 32; the inductance 3| is suitably coupled to a second instant that the scanning apparatus, driven from ,40

the shaft I2, is operating on the first element of the image.

' In the particular arrangement shown, therefore, high frequency oscillations will pass through coil I8 every time the scanning apparatus passes 4 through initial position with reference to the image. It will be understood, however, that the contact may be closed to permitoscillations to pass through coil I0 with greater or less frequency, by the interpositlon ofsuitable gearing for driving the disk I3, r by other arrangements,

A second coil Il is provided, which may bev shunted across the. power vline connecting the generator Il andmotor II;`

and a third coil 20 is provided, in which currents are flowing from the output of thephoto cell amplifier. The coilsjll, I9 and 2l, are all coupled to coil 2l, which feeds a suitable modulator and oscillator 22, such manner that the arrier frequency transmitted is modulated by the currents owing in coils It, I9 and'2l.` I

The arrangement of said coils, modulator and,v oscillator, is shown-only in diagram, as this arrangement per s e forms no part of my inventio and vis well known in the art. :The modulated carrier frequency oscillations are passed through coil 23, .and thence to cllj inductively coupled thereto, which is connected in circuit with antenna 24, andif desired, a tuning condenser 21 maybe associated therewith.- It willabe understood that all ofthe modulating currents may be amplined; if desired, to a greater or less t. and that in case it is desired, one or mo these modulated currents may be impressed as ductance 33, which feeds the input circuit of a suitable receiver and lter y34, which mayv comprise asv many stages of radio frequency amplifl. cation as desired, together with detectionand the necessary` filtering' circuits separating the various signal components from each other and from the received carrier. I

The photo cell currents are passed tothe light control apparatus, as shown diagrammatically by leads designated .to light control, and it will be understood that these currents may be amplified to the extent desired. The'. currents 4representing the frequency of motor-generator system I0; and II, may -be amplified by suitable amplifier 38, and may be converted, if desired, by means of a converter 3l, to currents of the phase desired. Inthe arrangement shown, I have4 illustrated the output ofA converter 31 as 'being supplied to a suitable .three phase motor'- 3B; in this connection, it is desired to vpoint out that preferably motor Il and motorl 38 should have as near as possible, the same operating characteristics, -'so that these two motors, under normal conditions, will operate atsubstantially the 'same speed. Mounted` on the rotor of motor ,38, I may provide' a'series of coils 4l, herein diagrammatically shown for purposes of simplicity, as `a 'single coil, preferably mounted on'a pivot at one end so as to be free to' align themselves radially under the action of centrifugal force when the motor is operating at 'substantially syn-v chronous speed.

I also providev a series of stationary coils 45, adapted to coact'with coils 4I and connected in series therewith through a circuit comprising Acontact. an bearing'on slip ring :s of the shaft :sa

of motor 33, and also by means of contact 42 bearing on slip ring 4I insulated from the shaft of motor 33.'

The coils 44 and. 45 are arranged to be enerof gized by the incoming metronome signals, which may be amplined to the extent desired by the sesam@ amplifier 3B.' It will be noted that I` provide'an insulating segment 43 on the periphery ofthe disk or slip ring' 4|,.so that the circuit through speeds. thecoils 44 will not'be extendedradiaily outward.- and will have very little eilect; however, asthe, motor 38 reaches synchronous speed.

these coils will swing into position `with their axes extending radially in position to coact with stationary coil 4B; the insulating section 43 is so positioned on the slip ring 4I, that it interrupts the output circuit of amplifier 35 when the position of the receiving scanning apparatus oper-V ated by motor 38 .correspondsl to vthe position desired; that is to sayin,case fthe transmitter sends out ,a metronome signal-` atfthe instant the scanningapparatus passesacross the rst element of'the' image, thenV the insulating segment 43 will beso positioned with respect to the scanning apparatus driven by motor Il, that insynchronous. speed until thecorrect position with reference. the driving Amotor cannot operate .at

respectlto the iframe gofjv reference has been reached;l andv this niakesdt possible to provide a single mastenswitchoperablefor example by remote control, ifdesiredrwhich master `switch* may be arranged-to close all'the necessary circuits to set the receiving apparatus in operation.

Therefore. itbecomes possible to operate a television broadcasting system. requiring noskiii on the part of the 'operator at the various receiving stations, since ifthe'transmitting station is in operation and it isdesired to receive from it, the receiving operator need only push a single start-stop switch to starting position, .whereupon the receiving apparatus will be set 'intooperatiom as already described, and will continue to function under the complete control of the transmitting stationl as long as the master switch is kept closed, no attention being required on the part. of the receiving operator,

Referring now more particularly to Figure 3, I have shown diagrammatically another form of synchronomefor synchronous receiver for exactly sulating segment 43 passes under the contact 42 at the instant that the receiving scanning apparatus driven by the motor 38, passes across the first element of the receiving screen. d

If it be assumed that the motor k38 is operating at the same speed asthe motor il and the instantaneous position of the transmittingand receiving scanning apparatus with respect to the frame ofreierence. is thesame, then the circuit of coils 44 and 45 will be open at the instant the metronome signal is received, and these coils will haveno effect. If, on the other hand, as will usually bethe casein starting,'this condition does not obtain, then the circuit through these coils will be closed, and upon receiptof the metkeeping stepfwith themaster `metronome at the g transmitting station." In'thisarrangement, I have shown the same receiving antenna and frequency filter as indicated in Figure. 2, but utilizingV ther'f' mionic vacuum tubes as controlling devices to differentiate between'periodically generated master and local signals.vr

The receivedl metronome signal, picked up by y.' the coil 50, isapplied to the control electrode 54 of the thermionic tube 5i. This signal is amplified sumciently to energize the 'coil 58, control-- @lingY the speed of the synchronome motor 58. It

ronome signal and during the duration thereof,

coils 44 and 4I will operate to attract or repel each other, as the case may be, it beingv understood that the polarity of all of the coils` is so chosen. asl to obtain maximum action.

li'or the purposeof discussion, it may be assumed that thecoils are so` wound. that upon the passage of current therethrough, they are attracted. It will then ybe apparent that if the' motor 38 is operated at less than synchronous ,l `will be observed that .fthegtube is provided with the usual cathode 52 anode 153. which is energized by the battery l1, andi-the input circuit mayinclude a tuning condenser 85. When the output-coil Il isfenergized. part of the amplified signal is transferred tothe coil 88' to control or block the activity of a similar thermionic tube'l.

:having a cathode 82, anode' 83 and control elec- 4 trode i4. The current induced in the coil 68 may be rectified by rectifier l1 of any suitable type.

The rectifier when it is energized. passes negative charges, corresponding tothe rectified metronome signal. to the control electrode 64 ofthe therniionic tube li. This vacuum tube amplifier" normally is'energized by a local signal, similar to speed or is out of proper position with respect to the frame of reference-then every-time a metronome signal is received,` an impulse will be delivered `to the motor Il tending to speed it uppprovlded the space relation of the coils 44 and Nisproperly chosen. On the'other handit the motor ll is operating at greater than syn` chronous speed.. it is apparent that the position of the coil 44-will be such that it will be retarded by-the action of the currents corresponding to the received metronome sinal.' .c

In order to prevent a condition of more or less continuous hunting by the motor 3l. it may be vdesirable to arrange the said motor so that it will normallyoperate ata speed-relatively a little slower than synchronous speed, so that correcting-or accelerating impulses are' supplied thereto periodically. so as to' maintain synchronous speed.

It will also be observed that with auch an arrangement, regardless of the space position of the receiving scanner with respect to the frame of the master metronome signal generated by oscillator 'Il and supplied periodically by a contact device 1| attached to the shaft 'I0 of the synchronome motor. The local or synchronome signal may be produced by a high frequency generator 13, coupled to the synchronome'motor Il. whence l the spring 12 feeds the local signal, which passes through filter 15 to the amplifier 6| and through the coils Gl and Il: and ra'tuning condenser il maybe providedto strengthen the input signals which pass the nlter. Both metronome and synchronome signals should comprise, near synchrony, high frequency oscillations of, preferably, similar periodicity. e v When the output` coil l0 is energized, a portion of the `energy is carried by the associated coil i4 and is rectified by the rectiner 59 so as to pass negative blocking charges tothe amplifier ll from generator 13. The coils Il and 00 operate to accelerate or retard the synchronome motor Il, except that at speeds much below synchrony, 4the accelerating coil II alone functions. When the motor speeds up suillciently to cause the generator to pass energy of approximately speed frefrequency is generated and and fine synchronizing con respectively. for dliyln1-my 1 quency through the filter, then the retarding coil will be able to function in arresting the speed of the synchronome motor.

Which coil operates to control the motor, depends on-the advent of distant or local signal.

When the metronome signal energizes the ampliner 0|, it establishes a negative blocking potential on the control electrode 04 of the amplifier 0|, and consequently suppresses energy iiow 'in the coil 00. When the synchronome signal energizes the amplifier 0|, it establishes a negative blocking potential on the control electrode of the amplifier 5|, and likewise suppresses energy A iiowin the coil 00.

Accordingly, if the synchronome is running beaaeaear synchronome motor 02.` By means of shaft |00,

the motor drives the wheel |00, which carries peripherally the suspended metallic plate |02 pivotted at |00. This plate is designed near synchronous speed, to engage capacitively correl -spending conducting sectors or areas-I 00A and |04,

` whoseseparationapart anddistanceirom the f ny plate' .|02 is adjustable.

low metronome speed, vit is accelerated, and if above it is retarded; in fact, it is maintained at synchrony. The currents in coilsv 00 and 00 are amplified sufliciently to producethe energy required to control the motor 50. the frequency driven from the receiverv 00 at approximate synl chony, at which, also, the movable condenser plate |02 will fly out sufficiently far, centrifugally,

of the currents is low, as for example representing the direct current fluctuations of the tubes 5| and 0|, then ordinaryy-iieldfcoils with magnetic material for reinforcement of the flux may be used. On the other'.ha id, high frequency currents may be applied these coils with the` design of the motor modified to respond to fluctuating currents o! higher order.

Moreover, the motor 50 may be driven by local power to approximate synchrony and the load on the coils 00 and 00 may be reduced to values sufiicient to exert the required speed variations to maintain synchrony.

Referring now more particularly to Figure 4. in. which I indicate again the thermionic controlling sytsem described in Figure 3; I show here a polyphase otor synchronome 83 driven synchronously with and by the' master metronome |0 described in Figure 1. The receiver 04 illters and amplies and supplies to output coil 00 the synchronome signals, described in Figure 3, and

to coil 0| the polyphase currents necessary to energize the network system 02 andy motor 03 of the synchronome. If the speed developed by the motor 03 is approximately synchronous with the transmitting system l0, and the time-phase suiiicient to covers. complete scanning element 'or reference frame as described, then the speed controlling coils 06 and 00 will take care of speed- .variations within the time and space represented by a single phasing of the motor system; Of course, the speed controlling coil may, at lower to close, electrostatically, one or other of the resonant circuits containing respectively coils 00 and |00.

For example, if the plates |02 and |00lmeet in capacitative conjunction, then high frequency current from ampliiier. 01 will pass through the momentarily established electric condenser, thus` formed, and will energize the coil |00 and amplifier 98; and coil or coils 9| will be strongly energized and may, for example, thus acceleratethe speed of the motor 02. Similarly, the coil or coils 00 may retard the motor when the capacitative currents flow through the moving condenser system |02 and |04. Now, when the metronome signal occurs during conjunction of the plates, the synchronome is either expedited or retarded, and

at synchrony of the synchronome the fly plate will be passing Just between the plates |03 and |04. v

In order to assist rapid acceleration of the synrchronome motor. 92, the condenser plate |03 taking part in the process may have its functioning area tail off as shown in dotted lines at |00.

In high speed television and Synchronization,

the wheel |06 should be geared to relatively high speed with the shaft |00 of the motor 92;'the separation between plates |03 and |04 and the width of the ily plate |02 should bereduced to a minimum lcompatible with sharp tuning.

WhileAI `have shown and described certain preferred embodiments of my invention, modifispeeds than synchrony, have its action cut out A by causing, as in Figure, the synchronome mo- .tor 00 to drive the generatorv 10 and to suppress its oscillating currents by iilter until the correct passed to the coil 00, as aforesaid.

- 0n the otherhand, the local signal generator 13 may, as shown' in Figure 4, be a self-sustaining.

oscillator whose energy is'periodically tapped and transmitted, asindicated, to the i'etarding coiljl. The rectiilersf 00 or 01,' if of the gaseous tube type may be shuntedwith suitableimpedances quency rectifications;` the tubes-0| andll sumdischarged at the conclusion-.'o:f ;.the

master or local time signals, so vas notv to block and interfere with the desired operation.

In Figure 5, IV show, afmodined; synchronome l `for attuning bythe principle 'ofresonancethe local apparatus tothe incoming'-- master inetto- 1. Inafsystemorsynchronizingwthe.operation cations and changes may be made without departing from'l the spirit and scope of. Imy invention as will be understood by those skilled in the "I claim:

of a plurality of devices, the combinationl offs metronome associated with one of said devices operable tovtrans'mit electrical impulses at intervals spacedinaccordance with the operation of said device, a motor, a lsecond of said devices being driven by said motor, and a synchronome associatedY with said second.v device comprising means to receive said impulses, comparing means including an element 'driven by said motor and associated with said impulse receivir'ig'meais to compare the cyclic operation of said motorwith speed-'control means including at least'- onexcoil associated 'with a moving part of f.ssicimotoi'energizable to increase or decrease the nome signals. The receiver 00l 'delivers speedfoilzsaidxj motor, and said comparing means l`beingj opchenille when, the cyclic operation of said motorlags said impulses to so energize said speed control means as to increase the speed of said motor, and when thel cyclic'v operation o! saidf motor-leads-sfaid impulses jto so energize saids speed control means las to decrease the speed 'of said motor.-4

2. Ina systemfor synchronizing the operation" o1' a pluralityfotdevices, thecombination of `a lmetronome associatedl with one 'oil said devices operable to transmit electrical impulses atintervals spaced in accordance' with the operation 1o! said device, a'motor, a second of said devices be- -ing driven by said motor, and a synchronome voi! said impulses to so energize said coils as to in-' crease thespeedof the motor when the `cyclic operation of the motor lags said impulses and to so energize said 'coils as toretard the Speedo! means to, receive-said impulses. `a pluralityI coils associated withya movinggpart of said mo-` tor, one of s'aid'fc'zoils Ito.f increase the 'speed of the' motor when energized and a-vsecend of said coils `/to decrease the rs'peedlof the'mtor vwhenener-A "gizedand means controlled by theoperationof the motor and saidimpulses to=selecti`vely ener- .jgize said-coils should the speedfof'themotor deviate from synchronism 'with'said -one device.

6. In a system for synchronizing the operationof a plurality of devices. the-combination of a metronome associated with oneof said devices operable to transmit metronome impulsesy at intervals spaced in accordance with` the operation of said device, a motor, a second of said devices being driven by said motor, and a synchronome associated with said seconddevice comprising means tol receive said metronome impulses, ak

pair of stationary coils associated :with a moving part o! said motor, one of the coils when ener-4 Y gized being operable to increase the speed of the motor and the other oi'f the coils when energized 4 being'. operable to decrease the speed of the mosaid motor, when the cyclic `operation of the motor leads said impulses.

3. In a system for synchronizing the operation of a plurality of `devices-the combination of ametronome associated `with oneof said devices operable to transmit electrical impulses at intervals spaced in accordance with the operation of said device, a motor, a second of said'devices being driven by said motor, and a synchronome 1 associated with said second device comprising means to receive r said impulses, speed controlV means includinga coil revolvable with said =mo tor and a stationary coil located adjacent thereto, the coilsv being operable to establish a force between them whenenergized, and means to electrically connect the coils with said receiving means except atspaced intervals during the operation of said motor, said impulses being operable when received before said intervalsft en-l ergize said coils to increase the speed of the motor and when received after said intervals to energize said coils to retard the speed of the motor.

, i. In a system for synchronizing the operation of a plurality of devices, the combination of a metronome associated with one of said devices operable to transmit electrical impulses at in'- tervals spaced in accordance with the operation tor,` means to connect one of Asaid coils to said receiving means, means controlled by said motor to generate and transmit synchronome impulses to said other coil at intervals spaced in ,accordance to operation of said second device, and means interconnecting said coils to compare the timing of said metronome and said synchronome I impulses and to selectively energize the coils in accordance to any, deviation, in the timing of said synchronome impulses with respect to the i timing of said metronome impulses.

oi said device, a motor, a second of said Vdevices being driven by saidl motor. and a synchronome associated'withsaid second device comprising means to receive said impulses, speed control means including'a coil revolvable with said-motor and`a stationary coil located adjacent thereto, the coils being operable to establish a force between them when energized'means driven 4by said motor operable to maintain the coils electrically connected with saidreceiving means except at a short interval in each cycle of motoroperation, and said impulse being loperable when A received before said intervals to energize said coils to increase the speed of the motor and when received after said intervals to energize saidecoils to retard the speed of the motor.

5. ,Ina systeml for synchronizing the operation of a plurality of devices, the combination-of a metronome associatedwith one of said devices operable to transmit electrical impulses at intervals spaced in accordance'with `the operation of said device, a-motor, ka second of said devices being driven by. said motor, and a synchronomeA associated `with said second device comprising' said device, a motor,- a .second ci saidgdeviees '4 7. In a system for synchronizing the'operation of a plurality of devices, the combination of a metronome associated with one of said devices operable to transmit metronome impulses at intervals spaced in accordance with the operation said one coil to said receiving means, means driven bysaid motor tc generate synchronome impulses at spaced intervals duringthe-operation of said second device, means including another thermionic tube circuit to transmit the synchronome impulses l,to said other vcoil,.and means interconnecting the tube circuits to compare the timing of said metronome and said synchronomeimpulses toselectivelyenergize the'coils in accordance to'any deviation in the timingloi'- said synchronomejimpulses with respect to the timing of said metronome impulses.

8. In a system 'for synchronizing the operation of apluralityof devices, the combination o! a metronome associated with oneoi said devices operable totransmit electrical impulses at intervals'sp'aced in accordance'with the operation of being driven by said motor, and asynchronome associated with said second devicel ycomprising means to receive said electrical impulses, apair Vof stationary coils'associated with a movingpart of said motor, one ofthe coils when energized being operable to increase the speed or the motor and the other of the coils when energized being operable to decrease th speed of the motor, aV

.increase the speed of .said lsynchronome motor.

9. Inl a system for synchronizing the operation of a plurality of devices, the combination of a metronome comprising a motor, means for transmitting electrical, impulses, means actuated by said motor for periodically actuating said means for transmitting electrical impulses, and at least one synchronome comprising means for receiving said electrical impulses, a synchronome motor, a coil rotated by said synchronome motor, a pair of spaced apart fixed coils cooperating with said coil rotated by said synchronome motor `to at-V tract the latter coil, thermionicV tu circuits connecting said impulse receiving means with said coils,'said tube circuits including a radially directed condensed plate rotated by said syn- A elements disposed in spaced apart relation so that the rotated plate passes the elements successively and forms two condenser systems, whereby ca acitative currents 4owing through said condenser systems selectivelyV energize said coils toretard or increase the speed of said synchronome motor.

l0. In a system for synchronizing the operation of a pluralityof current controlled devices, the combination of a metronome associated with one of said devices operable to. transmit electrical impulses at intervals spaced in accordance with the operation voi' said device, power means, a second of said devices beingl operated by said power means, and a synchronome associated with 'chronome motor, a pair oi cooperating condenser of said second device'tends to lag said impulses. the coils are energized to increase the application of power, and when the cyclic operagon of said second deviceleads said impulses, the coils are energized to decrease the application of power. Y l1. In a system for synchronizing the operation of a' plurality of current controlled devices, the combination of a metronome associated with one otr-said devices operable to transmit electrical impulses at intervals` spaced in accordance with the operation oi said device, power means, a sec'- ond of said devices being operated by said power means, and a synchronome associated with said second device comprising means to receive said impulses, a plurality of coils associated with said power means, one of said coils when energized to ,eiect a'n increase in the application of power. and a second of said coils when energized to ef. fect a decrease in the application of power, and means controlled by the operation o! said second device and said impulses to selectively energize said coils should the operation of the second device deviate from synchronism with said one device.

12. In a system for synchronizing the operation of a plurality of current controlled devices, the combination of a metronome associated with one of said devices operable to transmit electrical impulses at intervalsspaced in accordance with .the operation of said device, power means, a second of said devices being operated by said power means, and a synchronome associated with said second device comprising means to receive said impulses,

a 'plurality 'of coils associated with said power f means, one of said coils when energized to eiiect an increase in the application of power, and a second of said coils when energized to effect a decrease in the application of power, means controlled by the operation of said second device to generate synchronome impulses at intervals spaced in accordance to operation of said second device, and means to compare the timing oi said `metronome and said synchronome impulses and to selectively energize the 4coils in accordance to any deviation in the timing oi said synchronome .impulses with respect to the timing of said metronome impulses. ALEXANDER MCLEAN NICOLSON.

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