US 1873926 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 23, 1932.
Filed Feb. 2l, 1930 4 Sheets-Sheet l 1 J J l 1 J J J J JJ Allg- 23, 1932 M. cENTENo v. 1,873,926
TELEVISION APPARATUS Filed Feb. 21, 1930 4 Sheets-Sheet 2 ATTORNEY Aug. 23, 1932. M. cENTENo v.
TELEVISION APIARATUS Filed Feb. 21, 1930 4 Sheets-Sheet 3 INVENTQR ATTORNEY Aug. 23, 1932. M. cENTr-:No v.
TELEVISION APPARATUS Filed Fem 21, 195o 4 Sheets-Sheet 4 ZVQTK ATTORNEY @Imn /Www
-20 in the television art.
Murciana cENTENo v.. or lioS'roN, MASSA onusnlviis'y YfriiLEv,Isroiv ArrARATUS Application aia jrepri;aryi21,'193o. Serial No. 430,375.
i This invention relates to televisionr psystems and morefpar-ticularly Ato the electrical transmission and reproduction off images either by Wire or lby carrier Waves produced n inthe ether byfme'ans offa suitable radio transmitting system. f ,i `r The broad object of the present invention Y i'sto provide an vimproved'system oftele-v vision whereby stereoscopic Vtransmission and reception of vimages'may be 'carried on simultaneously and by means of simple ap-Y paratus arranged in a novel manner as` unitary structure.A Y i lAnother broad object apparatus adapted'gto be lused in a system for the transmission or reception ofordinary or'stereoscopicfmotion pictures.
Another object isto provide ajsimp'le and efficient apparatus adapted torj'general use A.V more specific' objectis to provide an improved mounting and means for actuation of the vibrating mirror commonly used in connection with television systems and apparatus.
Other Vobjects and advantages 'e'ffthe invention will be hereinafter specifically pointed outyor vvilll becomeapparent, as the specification proceeds.v
the invention resides y-in certainf'novel con` structions and combinations and arrangement of parts, clearlydescribedin the following speciication andA fully illustrated in the accompanying drawings,` vvhichv Vlatter show embodiments of the invention as at present preferred- Inv said drawings; Fig.y 1 is a diagrammaticl viewillustrat'- lling the manner in Whiclr'the improved television apparatus embodying the present in`- vention is applied to av system oftransmisf sion oli-images and themanner in Which reception ofl the transmitted images is eiected by lthesame apparatus.4
- "Fig. 2 is a diagrammatic vievv lillustrating the manner in vvh ich .motion` pictures may be transmitted by means ,of
the present invention.
5 l' I ig. Bis a planvievv of asystemv of'app'a-i is to provide anovelv n Vtightenedfor tuning purposes.
WTith the above indicated objects inv view,y
ratus Vfor the simultaneous transmission and reception of stereoscopicv images.. Inf u Fig t is a vertical elevation oit'- the system shoWn in Fig.3.. 1
.. Fig." 5' is avertical elevation 'of the improved apparatus for. use in connection With thesystems illustrated inF-igs. 1 ytoa incluf sive, and illustrates the manner in Which the vibrating `mirror 'iSl actuated.`
, Fig. 6,is a vertical section on the line 6 6 0 Fig. 7 is an -enlarged horiZontalvsect-ion on the line 7-7 of Fig. 5 showingthe man-Y ner in Which the supporting strings lare nFig.8 is an enlarged verti the line 8-.8of Fig. 5.- l y Fig. 9 is an enlarged vertical sectionon the linnei9-9 of Fig. 5 and illustrates `in detail themanner in- Which the vibrating mirror y.is mounted upon the ysupporting string. K Fig.` 9a is a back vieW of the mounting Jfor cal section on the member supporting the vibrating mirror.
Fig. 10is a horizontal section taken on the line'10--`10. oFig.5. l k 75 Fig. 11 isa vertical elevation-.illustrating a modification in theconstructionof the apparatus.illustratedinFigs 5 toj10.` Y
Fig. 12 isa verticalgsectionon the line 12412 of Fig. 11. A n s Fig. 13 is an enlarged horizontalsectlon through the center of the armaturewhich carries the mirror, taken 'onthe line '13 -13 of Fig'. V. .5 p Fig. 14: is an enlarged vert1calelevat1on of S5 the upperend ofthe armaturewhicll lcarries the-mirror and clearly illustrates the manner of lattaching the supportingv strings V,to the armature. Fig. -15 -is an enlargedLsection-talien on the 90 y line v15-15 of Fig. 16 and illustrates the means fork tightening'the supportingstrings for tuninglpurposes. .f 'A y p Fig. 16vis anenlarged vievv of v the means kfor tightening the vsu'ppporting strings for 95 tuning. purposes.f I y The numerals 2O and 21, Figs. 5 and@7 representfframe pieces mounted upon a-base 22 and supporting a cross-bar 23 'between their upper extremities. A frame 24.,y havingthe v are fastened to suitableY lugs carried by the base 22, passes over a projection 31 formed in the lowerpart of the frame 24 and ispre-` vented from slipping olf the projection a groove 32.
.The shafts 26, as stated, are journaled in the cross-bar 23. and each has fastened thereon a'worm wheel83 .adapted to be driven a worm 34 integral with a vertical shaft 35. The shaft 35 is journaled in members 36, 37 extending from the cross-bar 23 and is provided with a thumb-piece 38 for thepurpose of turning the-shaft. The ends ofthe wire 25 pass over notches 39 formed in the edge of the member 37 and also lthrough diametrical holes in the shafts 26, each end of the wire being wrapped several times around the shaft so as to ensure a. positive fastening to the shaft. Y It will be clear from the foregoing description that turning of the thumb-piece 39 in the'right direction will cause the shafts26 to be rotated and tighten up both ofthe wires 25 and 29.
Adjustably mounted upon the frame V24 are two'arms 40 which are slidable in dovetail slots 41 formed inthe frame 24. A screw 42 having a groove 43`and threaded rportio`ns'44 co-operates withthe arms in suchamanner that the arms are moved inopposite directionswhenever the screw is turnedv this result being accomplished by cutting la lefthanded thread on the leftiend of the screw Fig. 10) and a right handed thread on the right end of the screw, the respective threads on the screw 42 mating with similar threads on the arms 40. Alug 45 Vforming part of the Aframe 24 is provided with a notch co-operating WithV the groove 43 so that turningfof the screw 42 will cause-the arms to be'moved equal distances toward or away from the central :lug 45.
Screws 46, 47 are provided for the purpose of locking the arms 40 and screw 42, respectively, against movement after they have been adj usted. l l l Extending between the arms 40 Vis an endless wire 48 which passes over thefree ends of the arms and is prevented from slipping off the ends'of the arms by notches 49 cut in the arms. The lengths of wire lying between the arms 40 are parallel to each other andfsupport an upwardly extending flat strip of metal 50, theupper end of which is capable ofbeing vibratedby a magnet l'carried by the frame24. The lower end of the member 50 is stamped so as to provide tongues 51'which are pressed over the wire 48, thereby holding the member 50 Yfirmly place. is mounted upon the lower end of the member 50 and maybe either Isquare Vor round in shape.
The mirror 52 is adapted to receive a beam of light from a source such as a powerful arc lightplaced below an imaginary horizontal line passing through the center of the mirror. The reflected beamis requiredto be reflected so as to be capable ofsweepingvertically through' a small angle above and below the imaginary horizontal line just mentioned and for that A,reason the wire. 48 is disposed so that the mirror is inclined somewhat from a vertical positionj. f f
The frame24 is provided with `an arm 53 which acts as the armature of a magnet 54 betightened to tune the entire apparatus to certain delinitefrequencies of, vibration for a purpose now to be described.
The magnet 54 lis energized by ymeans of an alternating current of low frequency, say ten cycles per second, the strings 25 and 29 being tightened by means of the thumbpiece 3 8'until the entire frame 24 and associated parts vibrate continuously about a vertical axis in resonance with the low frequency alternating current.
The magnet 51, on the other hand, is energizedby a high frequency alternating current, 'say around 450Vv cycles per second and thestring 48 tightened until the member50 vibrates continuously abouta horizontal axis and in` resonance-with the high frequency alternating current.
When both of the magnets 54 and 51 have been energized and the strings properly adjusted to resonance with the respective energizing currents a beam of light projected upon the `mirror 52 will be reflected and the reflected beam used in a television ysystem to scan or trace a picture or object for transmission of an image in conjunction with a light sensitive medium such as a photo-electric cell; a similar apparatus .to that just described being used at the receivingend of the system in conjunction with a source of light such as a neon lamp to trace an image identical with the picture or object. This arrangement is illustrated in Fig. l wherein the numeral 56 representsa source of light which would be an arc light when-transmitting the image or a neon lamp when receivingV Va transmitted image. VVA photo-electric cell 57 or other light A mirror 52 which the relectedbeam 58 from the light' source. 56 is'directed uponftheimages .59 of the motion picture film 60 as they 'are successively movedv into the field of the beam by an intermittent motion mechanism similar to that used in a standard motion picture projector or camera, the images on the film being moved into the field of ther beam 58 at,
the rate of about sixteen images per second,
each image being held stationary long enough for the beam.58 to scan or trace the entire image, a photo-electric cell 57 or other light sensitive medium being provided to convert l'. the minute variations in the intensity of the light transmitted thro-ugh the film into electrical impulses for transmission to the receiv-v ing apparatus. At the receiving end .an arrangement similar to that illustrated in Fig. l
j may be used in connection with a neon lamp to convert the varying current Vfrom the photo-electric cell into asuccession of4 images similar to the images inthe film 60. I
f It will be clearly understood, of course, that for successful operation ofthe systems mentioned the mirrors at the transmitting and receiving ends of the systemV must be operated in exact synchronism with each other in order to successfully transmit a clear image of vthe picture or obj ect. Y
. Figs. 3 and illustrate a system adapted for the simultaneous transmission or reception of stereoscopic images. Y Through the arrangement shown in these figures a person standing fi: in frontvof the apparatus at one end Vof the system could be seen by a person standing in front of theapparatus at the other end o-f the system and vice versa, the images produced being stereoscopic.
The numerals 6l represent suitable light sources suc-h as arc lamps projecting beams of light 62 upon the mirror 52, which is kept vibrating in` synchronism- Awith asimilar mirror at the other end of the system. The
' reflected beam 62a from eacharc lamp 6l is adapted to trace a pictureor object in the manner in which has already been described in connection with Fig. l, however, dueto .the
displacement of the lamps 61 there will be two beams of light simultaneously traced over the object with the resultthat photo-electric cells 64 will be variablyaffected in a. stereoscopic sense. and ovvingto their displaced relation will produce variations in current which1 when transmitted to the otherV end Yof the system, willfbe "converted by. separate Vlight sources .such as neon lamps into beams of flight ofv varying-intensity which, :after being reflected from the vibrating mirror similar to thefmirror152vand oper'atedlin synchronism therewith, will trace a stereoscopicimage upon a suitable screen..v rlhis situation may be illustratedi'n Figs. v3 and 4L in which the reference numerals represent neon lamps adapted to receive the impulses froml the photo electriccells 64 and convert them into beams of light of varying intensity which will trace an image upon an opaque screengeneraily indicated by the letters A-Bin :'Fig.'4;
y In Fig. 4 the letters C-Dldiagrammatically indicate the location of the picture or object which is being'traced at the'tra-nsmitting end.
In order to reducethe angle through which the mirror 52 is vibrated, therei's provided:
kaan optical system including suitable diverging lenses 66 and 67which serve to deliectthe beams of light from the light source 61, and
cause them to sweep over greater horizontal:
and vertical angles than`are swept by the beams reflected from the mirror, consequently the area swept by each of the beams is cone siderably increased without increasing the angleof vibration of the'mirror52. Since the rate ofvibration of the'mirror in the vertical direction is very high, Iit is desirabley that the angle to which the member 50 swings be reduced as much as possible in vorder to make the member 5() more Vresponsive'tovthe vhigh frequency energizing current. Another reasonfor reduci-ngi the angle ofvibr'ation of the mirror 52 is to reduce the weight of the vibrating parts since the currents vreceived by the Yreceiving apparatus will vbe relatively weak even after amplification -by suitable amplifiers and it is desirable that the weight of thle moving parts be reduced as much las possi le.
cells 64 together with'the displaced relation of the lenses 67createsa stereoscopic eect similar to the effect produced by the human eye wherein the eyeballsl are separatedV by a few inches and-receive images simultaneously-fromv dierent angles.4 Similarly the displacement of the neon lamps 65 andthe lenses f 66 produce a. corresponding.l stereo-V scopic effect at the `receiving end of thesystem. nIt' will rbe understood, of course, that lin, the present invention both sending and L receiving is accomplished simultaneously'by the same apparatus and s o farasthefforegoing description is concerned,v the distinction between receiving and sending isrelatively vimmaterial and has been chosen merely to make clear the operation'of thesystem.y o i In actual practice both the neon lamp 65 and the light source 61 would be operation simultaneously and thejimage' ofthe object or picture C-D would be'. transmitted by the same apparatus vand simultaneously .with the' The displacement of 'the-photoeelectric i Cfr reception ofk another imagetra'cedupon the screen`A-B, the images transmitted'and received being-both stereoscopic. l
Figs. 1l to 16 inclusive .illustrate a modification in the construction of the apparatus illustrated in Figs. to 9a inclusive. The numeral 67 represents a supporting frame which. may Vbe made as a unitary structure if desired. Mounted .upon the upper and lower portions of the frame 67 Y are coils 68 which are energized from an external source of direct current. The coils 68 Vsurround suitable pole pieces 69 sov thatrwhen a direct current is flowing through the coils 68 a strong magnetic field Vis produced between the poles 69. rlhe coils 68 are'rconnected in series and, through the Amedium of binding posts 70, may be-connected to theexternal source of direct current. y Y
An armature 71 adapted to oscillate in the field produced between pole oieces 69, is sup? ported by means of strings 2. Each of the strings 7 2 is attached to the armature 71 by members' 73 which are provided with two holes through' which the string passes, theV string passing in one hole and out the other hole. The object of this construction is to permit the strings to slide freely in the mem bers 73, the members 73 being attached to the armature by means of suitable screws 7 l. Each end of the strings 72 passes around andvis attached to a shaft 75 which is jour,` naled in suitable lugs 76 supported lby the frame 67. 'I
The shaft 75 1is provided with a worm wheel 77 integral therewith while a shaft 78 providedV with a `worm 79 engaging the worm wheel 77 is adapted to be turned by means of a slotted head'80 for Vthe purpose of tightening theV strings.. l y
The worm 79 lies within a cavity formed in the frame 67 while the shaft 78 lies .in suitable slots 81 formed inthe frame 67 and is held in place by slotted plates 82 attached to the frame 67 by screws 83. The obj ect ofV this construction is to make it an'easy matter to assemble and* adjust the tightening mechanism for the strings. that the worm 79 may be turned by means of a screw driver'to tighten the vstring 72 by winding the .ends of` thefstrings over the shaft 75. In orderto hold the strings in proper alignment a bridge 84 attached to the lugs 7 6A is provided and has formed therein suitable notches 85 inwhich the Vstrings lie.
The armature 71`has supported thereon pole pieces 86 which hold coils 87 in place, the pole pieces 86 being separated from the pole pieces 69 by a small air gap. The coils 87 are connected in series and toV suitable binding posts 88. The armature 71 also is provided with pole pieces 89 bearing coils 90connected in series and to binding posts 91. Thebinding posts 91 are connected to.
an external source of direct current so as It will be clear1V to maintaina strong magnetic field between the pole pieces89v. y
`Mountedfu'ithi-n the `strong magnetic field produced bythe coils V90 is asecond arma-v ture comprising a member 92 carrying pole pieces 93 and vcoils 94 surrounding-thepole ypieces,"suitable screws 95 serving to hold the pole pieces upon .the member 92.l The member'92 is supportedbetween the -pole pieces 89 by means of strings 96, eachfof which `is attached tothe member 92 by'fmeans of'a member 97 ,similar to the member 7 3, and fastenedto the member 92 by means of screws 98; The means for attachingthe Vstrings 96 tothe memberl 92 isvalike in all respects to the means for attaching the strings 72to the armature 71. The attaching means for strings-96 is Vclearly illustrated lin Figs. 13v and `14 and these two gures will also clearly explain the method of attaching the strings 72-to the armature 71. Each of the strings 96 is tightened by means similar'to the arrangement illustrated in Figs. and 16, the tightening means being of a smaller size owing to the smaller space available and also so as to reduce thel weight of the armature 71 as much as possible. j
The coils V94M are connected in series to binding posts 99 and are energized by a high frequency alternating current of say 450 cycles per second. upon the member '92 and preferably should be inclined somewhat from the yvertical so that a beam lof light directed upon the mirror from a source such as an arc lamp placed below and in front of the mirror will be reflected horizontally when both armatures are at rest. i
`The apparatus just described, illustrated in Figs. 11 to 16, may be 'used'in the same manner and under the sameV circumstances in a television transmitting system 'utilizing a vibrating mirror for tracing an object or picture'in connection with a photo-electric cell or it may be used in a television receivlng system to trace an image transmitted b such a transmitting system. It will be understood, of course that the vibrating mirror Y in the receiving system Vmust vibrate in exact synchronism with the mirror in the transmitting. system in order to secure a clear image.
In :practice 'the coils 68'and 90'will be energized from an external source of direct current soas to maintain a constant field between the pole pieces 69 and 89 respectively. The coils87 will be energized by `an alternating current of a frequency of say ten cycles per second and the strings V72 will be tuned to bring the entire system carried by the Varmature 71 into resonance with the Vlow frequency alternating current. Similarly, the coils 94: will be energized with an alternating current of a frequency of say cycles per second and the strings 96 tuned-to bring the central A mirror 100 is mounted f lia' armature supported lthereby into .resonance with the high frequency alternatingcurrent,l Itwill thus bef-seen whenA the'appa'ratus has been `properly tuned to resonance that the mirror 100 will be vibrated about-,one axis ata high frequency and alsovibrated ata lowV frequency, about another aXisz/at right angles vto the first,consequently a beam of.
light reflected from themirrorwill make a large numberfof tracespersecond',ranging in the hundreds. .v
The apparatus may beusedin any of the Y systems anda'rrangements shown inlfigs.V l
to 4, inclusive, and accomplishes exactly the same results as the, apparatus shownfinthose figures diagramm'atically Y and greater detail infFigs. 5kto-9ajinclusive l Y In the foregoing descriptionl .of the apparatus for vibrating the mirror reference has been made tothe use of alternating current for providing the energizing current forthe elements vibrating the'mirror'. Itis pointedv out that the presentinvention isy not limited to the use of alternating current alone as pulsating direct currents might be used, the
pulsating frequencies being the same as ifl ception of images illustrated in Figs. 3 and l is the accomplishing of simultaneous reception and transmissmn of an image by means of a single vibrating mirror as heretoforeA several such mirrorswere" necessary and the f apparatus for transmitting an image of any object had to be separate from the apparatus for receivingand reproducing said image.
\ Another advantage is that a single vibratc ing mirror canbe used to accomplish stereoscopic transmission or reception.' Heretofore in transmission of anfimage stereoscopi cally 1t was necessary to provide two such Ymirrors displaced from each other an amount` approximately equal or proportional to thel ist distance between the normal human eyeballs so that the proper relationshipl wouldbe preserved betweenthe two simultaneously transmitted images, a similar arrangement being required at the receiving end of the systemV to reproduce the two images and create the stereoscopic effect. Y Y
The principal advantage of the apparatus for vibrating the mirror herein described is the readiness and ease of adjustment made possible by the'manner of mounting the vi- Y brating parts by means of strings and ther rovisions for tightening the strings where,- y each of the vibrating parts may be easily and conveniently tuned to reso-nance at any desired frequency of vibration. l
Various modifications may be made in the systems-and apparatus herein:describedfandf e it is not desired to limit the scope ofthe in-:zA ventionv to the `.precise arrangements shown.
inthe ldrawings and described herein.- As
one instance of theadaptability of zthepresent linvention the systemfor transmittingor receiving stereoscopic images of picturepor;
objects might be used for the transmissionr of motion pictures stereoscopically by ,causil ing two strips of motionpicture yfilm, photo-g` i5 4 graphed from different angles, to pass .in front of two photo-electric cells,.the,limages on one film being traced byone ofthe beams` of light 62a-while the images on the other.
yfilm are beingtraced'simultaneouslybythe other beam of'light 62a-, suitableintermitf tent motion mechanism being providedto drive/both films intermittently andpinsyn.-
chronism.. -At they receiving end an arrange,-l -mentsimilar'to that shownv in Figs. 3.and4:
may bey used'y to reproduce the transmitted images from both films simultaneously thereby producing stereoscopic Ymotion pictures.
" f'lhel vhereinbefore described constructions and, systems admit of eonsiderable modifica- 56 tion ywithout 'departing from., the. invention; therefore, it is the wish not to be limited to 'thef precise arrangements-shownA and/deffV scribedfwhich arel asaforesaid, by wayfof illustrationgmerely."'Ini vother Words', Lfthfe'l scope Yofjprotection contemplated I,is into" be taken -solely '.fromlgthe appended claims, inf `'terpreted as broadly as is'consistent with the prior .a1 't.\ l ,p
Whittielamefsnew, iS= .lf Il.' In a ltelevision-'apparatus, afstationary frame, a movableiframe disposed Vwithin the stationaryfframe, flexible suspension means for supporting the movablefranie in the stationary frame, thelatter being provided .with
an armature@ 10WA freqerfy Maestrinlportcd inthe stationary frame so aste proj ect itseldthrugh th armature Oft/he' mevable frame, a l mirror, a high frequency magnet carried by the ym0vable frame, f au armature 'Y Y forthelast said magnet, said armaturebe'ing flexibly` mounted in themovable frame and carrying said mirror. f v
frame, amovable frame .disposed within' the' stationary frame, flexiblev suspension f' means forsupp'ortingthe .movable vframe in the stationary frame, a-low 'frequency' magnet supported in the'stationary-Sframe,thetmov# Y l able frame having anarmature in the field' of said"magnet,a tensioning member for said flexible suspension means, to'vary the tension on thesameto change the `rateof'vibration" ofthe movable'frame to accord with theffrequency` ofthe magnet, a high frequency e Het, Carried by th movble'ffema and a" miriforjsupporte'dby the movable frame.' and havmaia member uiictnngf asfth@ "armature i lof'said high frequency "magnet to vibrate the ion .2. Inatelevision apparatus, a stationary 'izo i mirror whensaid high frequency magnet is energized.
3. In a television apparatus, a stationary frame, a movable frame disposed Within the stationary frame, flexible suspension means for supporting themovable frame in the stationary frame, a lovv frequency magnet sup'- ported in the stationary frame, the movable frame having an armature in the field of said magnet, a tensioning member for said flexible suspension means, to vary the tension on the same to change the rate of vibration of the movable frame to accord With the fre# quency of the magnet, a high frequency magnet carried by the movable frame, and a mirror-[supported by the movable frame'and having a member functioning asl the', armature of said high frequency magnet tovibrate the mirror When saidf high frequency magnet is energized, the axis of vibration of the mirror being `angularly related to the axisv of vibration of the movable frame. Y
4. In a television apparatus, a stationary frame, a movable frame disposed Within the stationary frame, flexible suspension means formsupporting the movable frame in the stationary frame, a lovv frequency magnet supported in they stationary frame, the movable frame having an armature thev field ofv said magnet, a tensioning member for said vflexible suspension means, to vary the tension Van armature, a lovv` frequency magnet supported in:the stationary frame so" as to .project its field through 1 the armature of the movable frame, a high frequency magnet cari ried by the movableframe, a mirror having a member disposed in the ieldofthe high frequency magnet and actingas an armature for the same, and vflexible suspension means forsupporting. said mirrorin the movable frame and consisting of parallel strands, Vand ad?v i justablel-meansifor varyingfthe tension on s aid strands." Y
In testimony whereof I Vhereof affix signature.V Y Y y MELCIIOR` CENTENO V.
on the same to change the rate of vibration of Y y the movable frame to accord Withthe' frequency of the magnet, a high frequency mag-v net carried by the movable frame, anda mirror supported by the movable lframe and having a member functioning as the armature of saidhigh frequency 'magnet to vibrate the mirror when said high frequency magnet is energized, the axis'of vibration of the mirror being angularly related to theaxis of vi#` brationl of the movable frame, and thetensioning device for the suspensionY meansfor thelatter consisting of Worms inmesh with a common screw, and shafts Withv which the Worms -are connected, Vand the suspension means' consisting of parallel exible members connecting the movable frame to the sta# i Y tionarfy frame and the `former to the said A i shafts, the latter being rotatably mounted in the movable frame. y y 415.'In Aa television apparatus, a stationary frame, a movable framedisposed Within the stationary frame, flexible suspension means for `supporting the movable frame inf-the stationary frame, the latter being provided f i with an armature, a. low frequency magnet supported in the stationary 'frame sov as to project its eld through the armature ofthe quency'rmagnet and acting as anarmatureV for lthe same, and flexible" suspension Vmeans movable frame, a; high frequency magnet car V'