US2978601A - Electronic control system - Google Patents

Description

April 4; A'1961 n Filed nec. i2', 19s? 3 sneetspseet 2L .W mllluvlmU.

v rNvENi-OR WILLIAM Ross AMEN ATTORNEYS April 4, 1961 I w. fR. Amt-:N -mscimouzc comm. sysma' md n. 12,195?

' n/sHrNEss 7o HUE 62x SATURATIUN 64 INVENTOR WILLIAM ROSS AMEN ATTORNEYS z,91s,to1 ELErRoNIc coNrRoL sYsrEM William Ross Aiken, Los Altos, Calif., assignor to-Kniser.v

Industries Corporation, Oakland, Calif., a corporation of Nevada Filed Dee. 12, 1957.5. No. 702,340

9 (cl. srs-92) The present invention relates to cathode ray tubes and Vmore'#particularly to =acathode eray :tube capable of color display employing a layered phosphor target screen.

In the prior art, attempts have been made to produce color` kinescopes employing a single electron gun wherein a plurailty of phosphors capable of emitting light of different colors are settled on the target screens :United states IPnemi-fc3 iCCjk n 2 f Figure 5 is asectional view of Figure 6 Ais a schematic illust-ration ofA acontrol cir-' f.

cuit for energizing the various embodiments.` y l Figures l and 2 show a cathodejray tube of the Aiken type wherein there is a relativelyat orshallow envelope 10 adapted to completely house the internal components of the device. A pair of electron guns 12 and 14 adapted to deliver electron beams 16 and 18 respectively is disposed in spaced relation with respect to a marginal edge of a composite target screen S. The electron guns are provided with conventional electrostatic deflection plates' 20 and 22 respectively. However in the event electromagnetic deflection is deemed desirable, magnetic yokes may be employed to effect the'desired scanning control y of lthe-electronbearns. n y t .'Ihe'target screen S is comprisedof a supporting plate- 24 and a plurality of superposed phosphor material layers 26, 28 and 30, each of the phosphor layers beingcapable in discrete layers. The layer to be excited is determined l by varying the velocity of the electrons which are caused to strike the composite target screen. velocity of the electrons, the depth of penetration of the electrons into thel target screen may Abe varied. Mani- By varying the festly,'to.eiect the maximum degree of penetration, the

mount necessity during which time correspondingly high voltages would be required to effect the desired scanning of the electron beam across the targetscreen. ln conjunction with such tube, rather extensive electronic circuitry may be required for effecting switching ofl the beam between colors. v v It is an object ci the present invention to cathode ray tube capable of providing color display which is simple in construction and consumes a. minimum application of extremely high voltages would be of parawhich also may be optically transparent.

of emitting light of different colors upon excitation by an impinging beam of electrons. l- The arrangementof 4 deflection electrodes 32 are disposed in. spaced relation amount of electrical energy in effecting color selection or switching.

It is a particular object of the invention to provide a cathode ray tube which is capable of providing color displays which are operative to provide a display indicative of incoming saturation, hue and brightness signals.

The instant invention in one embodiment comprises a l.target comprisedvof a control layer and a plurality of phosphor layers disposed in superposed relation, each phosphor layer being capable of emitting a different color ilightupon electron excitation.

ment, a first electron beam of insut'ticient energy to penetrate the control, layer is delivered into registration with the target. This beam is operative to vary the potential on the various portions of the impinged target in accordance with they energizing control signals which are fed to the electron source. A second electron beam is delivered v into registration with the target and will penetrate therein a degree determined by the potential impressed thereon following registration of the iirst mentioned beam therewith.

This invention will be clearly understood from reading the following detailed description when taken in view of the following drawings in which:

Figure 1 is a front elevational view partially in section of a cathode ray tube employing the instant invention;

Figure 2 is a sectional view of the tube illustrated in Figure l taken along line 2 2; l

Figure 3 is an end view of a modification of cathode ray tube shown inv Figures 1 and 2;

Figure 4 is a view similar to Figure ly showing another modification of the invention shown in Figures l and 2 wherein the electrons are initially directed along a marginal edge of the target screen and illustrates the so-called Aiken double bend tube.

In ar preferred embodi v vfrom the composite target screen S. Each of the deecv tion electrodes 32' is electrically coupled to an electric generatcr'prcfcraltf situatedcutsde the envelope.

The deflection electrodes 32 may be formed of an electrically conducting material which isv optically transparent such as for example vconducting glass. Manifestly by forming the deflection electrodes 32 of-a transparent' material, any display presented on the target screen S may be readily rviewed frommeach surface thereof. The

composition targetscreen S and the vertical deflection electrodes 32 may be referred to as the secondary or high voltage section of the tube. r'

The instant invention is operative to achieve'ffcolor display as well as in certain applications, black and white displays. Color presentations are effected by the principle vol? selected penetration of an electron beam into the target screen S, comprised of the superposed layers 26, 28, 30 of phosphor material which when individually energized will give olf green, red and blue light respectively. The penetrationof the impinging electron beams into the target screen S is variedby varying the potential of the different target areas and particularly the potential of the different areas of the control layer 31.

More specifically, it is proposed'in the instant arrangement to employ two electron guns 12 and 14 which are operative to deliver electron beams 16 and 18 respectively. The electron gun 12 is controlled bythe colorv component of the transmitted signal and the electron gun 14 is controlled by the brightness component of the transmitted signal.

In operatiomthe beams 16 and 18 me delivered along a path between the target screen S and the array of vertical deflection elements 32, the position ofthe initial beam paths adjacent the vertical deflection elements 32 being controlled by the energization of the deection plates 20, 22 of the respective electron guns 12 and 14. It will be appreciated by those skilled in the art that the electron beams ltiand 18 may be effectively causedrto scan the target screen by varying the'voltages impressed I on the deection plates 20 andy 22and the -dellection er 1 Panarea Apr. 4, 1961 j Y the ytube taken along i plates. sa

'corner of the target. 'horizontal sweep signal to the dctlection plates 20, 22

the beam sweeps the zone adjacent the target, and the'endf,v thereof traces a linear path adjacent the upper marginal` in a synchronized manner. r l In the event the rinstant/tube were employed for the reception of convcn tional television information, the signals, impressed on the deflection plates 20'an'd 2 2 would be the horizontalk oscillator output signals at. 15,750 cycles per second, and' the vertical oscillator signals'would be applied to a eon- .trol circuit which in turn applies energizing potentials to brightness beam the vertical deection electrodes 32 in a progressive overt i lapping manner.

If the deflection electrodes 32 are initially all main tained inthe order of kv. maintained at a like potential, created thus allowing the and the target'screen is` a held-free region will bev electron` beams to travel therein f green light. lt

on a given incremental area non-uorescent layer 31, the phosphor layers 3 0 and 28, and finally come to rest in the layer 26 which will emit -is apparent that thesmaller the charge of' thetarget screen S following registrationof the color beam 16, ther less the amount of penetration which can be achieved by the 18. Thus color selection or hue for a determined by controlling the intensity particular area is l beam 16 at the. time of registration of the color selection withsuch area.

Prior t0.

v layers are recharged by any one of al number of acceptunaffected. With the application of the horizontal sweep signal to the deflection plates 20, 22 the electronv beams are initiallydelivered adjacent the left hand margin otthe target and the vertical dellectirm electrodesmand the i. voltage on the upper deliection 'electrodes is lowered -to bend same into registration with the upper left hand With continued application of the edge of the target. ered on the successive cessivelines of the raster are traced on the target screen S. Each of the electron guns and associated primary sets are operated at different potenttals,vas more fullyv described hereinafter. As mentioned hereinabove, a color display is achieved by varying the penetration screen S. In a first embodiment the electron gants 12 and 14 are controlled by different control signals, the gun 12 being controlled by the hue or color component of the transmitted-signal, while the gun 14 is controlled by the brightness signal; In practice, t'nc or hue beam 16 emanating lfrom the electron gun 12 is adapted to sweep the target screen slightly in advance of the brightness beam 18 which emanates from the electron gun 14. Also, paths differently spaced from deection electrodes 32,

since thebeams initially travel along of they electrons into the target 16, 18 to insure registration of the linear paths for each of the sucthe respective beams beams with identical ccssive traces.

' Thus the color selecting or'hue beam 16 is composed of electrons which have traversed a voltage gradient insuilcient to allow the electrons to penetrate the control layer 31, and the intensity of the beam the value of the potential on the target screen at each localized area of impingement. It is apparent that variation of the beam value as it impinges with successive areas in its sweep across therscreen will effect a corresponding variation of the value of the charge on the dilerent incremental screen areas.

It is well known that an electron of a given velocity will penetrate a phosphor layer a given distance and can be made to give up thc majority of its energy in that layer. Accordingly, with the cathode voltage of the electron gun 12 operated at +10 kv. and the composite target screen operated at 20 kv., the color beam 16r will not have suicient velocity to penetrate the tirst layer 31 of the target screen S. However, as mentioned above, the beam 16 will tend to discharge the areas on which it impinges and thereby vary the voltage of incremental areas of the target screen S. The value of the voltage at each incremental area will determine the degree of penetration ofthe layers by the brightness beam 18 which emanates from the electron gun 14, and which scans the target screen S slightly behind the color beam 16.

In the event that the c olor desired at an area is green,

16 will determine able methods. ing-of the phosphor layers is effected -by the application `of leakage currentsover the conductive layer 31. Other `vent penetration of In one preferred arrangement, rechargmethods will be readily obvious to parties skilled in the art. l

' e control "circuit VVforthe'thirbtubcisA set lfortrrin .the schematic showing ofkFigure 6, wherein a conventional colot receiver is connected to effect application of the hue and brightness-signals over conductors 62, 70 to electron guns 12,14, respectively in the manner ofthe previously disclosure. Delay circuit 72 introduces the necessary time diterential between the sweeping of the screen by the respective the color rasters. The operation of the system a color displayiwill be obvious from the foregoing disclosure.l

'-ln a second embodiment, the color system is adapted to additionally respond to saturation signals,`such arrangement being also schematically illustrated at Figure 6. Briey, thegsaturaton signal detected by receiver is appliedover conductor 64 to a highrrequency modulation circuit (approximately one magacycle 'in value) the output of which is connected over capacitor 67 and y conductor 68 to the gridv (or cathode) of the hue gun 12.l

The' signal output ot' the modulator unit ne te the :ne

gun 12 is commensurate with the value oi the saturation signal applied to the input of modulator 66 by receiver 60.

In operation the hue' beam is controlled to sweep across the vcontrol layer 31-in the manner previously described to condition the successive incremental areas of the target to different voltages in preparation for the registration of the brightness beam with such areas. The brightness beam 18 in its sweep across the target closely behind the hue beam penetrates the control layer to the particular color layer indicated by the value of the charge on the control layer at such area. Thus the display of a fully saturated red (the second layer 28 inthe present example) by an area is effected by controlling the hue beam to discharge the'arca to a value suiciently low to prethe brightness beam beyond the second layer.' The brightness of the fully saturated red color is determined by the intensity of the brightness beam.

vof the hue lgun -corresponding value, With the application of the modw With receipt ofthe incomingA saturation signal indicating a diluted red signal, a saturation signal is applied to the modulator unit 64 which is proportional to the degree of dilution desired, and the modulator unit 64 isresporv` sively operative to couple a proportionate signal over capacitor 67 and conductor 68 to the grid (or cathode) 12 to modulate the output thereof by a lation frequency to the gun 12, the potential in closely successive lincremental intervals-on the control layer 31 adjacent the initial point of color selection will be successively varied ina manner related tothe successive value of the beam. The successive intervals of the arca thus conditioned are so close as to appear to the observer` as a single dot, and as a result of therdillerence of potential established ontbese successively adjacent intervals, the brightness beam Ain -its registration there with will'tnove through the three successive phosphor the initiation of each rastertrace, the various beams 16 and 18 in their provision ot' l to provide layers in rapid succession sursaut l' 1 s' whereby the color selected bylthe hue beam willfbefdi- ,i

with the value of the incoming saturation signal.

` 1n such embodiment,.therefo're, the value of the incom' i ing brightness signal controls the value of the brightness beam and the resolution and picture brightness; l'the in coming hue signal controls the intensity` ofthe hue beamV and the color to be selected; and the incoming saturation signal controls the degree of steady high frequency modulationv of the hue beam, and therefore the dilution ofr the selectedl color with white light.-

Figure 3 shows a modification of the cathode rayftnbe illustrated in Figures 1 and 2 wherein the` ytarget screen S is identicalwith that illustrated in the earlier figures luted by an amount of vwhite light which is` commensuratev 'y with an additional'phosphor layer 34 disposed on the' side opposite the layered phosphors. The layer 34 is voperative to be used inthe presentation of the conventional black and white displays. Por purposes of simplilication primeA numerals are used to denote the elements of the tube which arel similar to those shown and de-v scribed in connection with Figures 1 and 2;

A second set of vertical. detlection electrodesl 36, smil lar to electrodes 32, are disposed in adjacent spaced re lation with respect to the layer 34. The electrodes 36 are formed of` electrically conductive optically transparent material such as for example conducting glass. l

An electron gun 38 is disposed in the same relative position with respect to the v'composite target screen S as the electron guns 12 and 14 and is operative to deliverv an electron beam 40 along a pathfwhich lies be-rv tween the phosphor layer 34 and the set of deflection electrodes 36. A pair of conventional electrostatic deflection plates 42 are'employed to effect the desired vdirectional control of the electron beam 40 in a plane substantiallyparallel to the layer 34. The beam 40 may be S which delivers the-beam 52' is controlled by the brightness component of the transmitted signal. T he color beam 52 iscontrolled to scan the target slightly in' advance of-the brightness beam 52' `and such is accom- 'I f n plished in this embodiment by applying energizing signals vto the horizontal deflection electrodes 54slightly in Vadl vanceA of the energizing potentials appliedto the deflection The desired deflection ofthe electron .y beam 52 is accomplished by maintaining all the electrodes l 54 at a negative potential with respect to the Abeam 52, s land selectively driving Athem in a positive direction tol electrodes 54'.

ward the potential of the associated slotted electrode 56.

Acfdngly, it will be appreciated that if the electrode 54 closest to the electron gun S0 is negative with respect to the beam 52, the beam will be deilected upwardly ber tween the focussing and accelerating lelectrodes 58 and thence into'a field-free zone within the secondary section.

This field-free zonevis established by maintaining the target j screenS andthe"verticaldetlecton electrodes `32' at-substantially the'same potential. The beam S2 will thcre-` t i `fore travel unaffected until such time as thevoltage on, -f i one or more of the electrodes 32' is caused to be lowered a degree sufficient `to causethe beam to be deflected toward and impinge onthe target screen S.v In .order to effect movement of the beam 52 across the face of the target screen S', lthe horizontal" deflection electrode 54 whichis effecting the first bend in the beam is driven "jacent electrode 54. To assure a lineardetlection of the beam, the deflection electrodes 54 as well as ,the deflecdeflected' toward vand intol impingernent with the target energization of the deflection plates42 and the deflection electrodes 36.

It will be obvious to those skilled in the art that the cathode ray tube shown in'Figure 3 is capable of achieving separate black and white display.

The device illustrated in Figures 1, 2, and 3 uses va deflection principle known in 'the art as the Aiken single bend deflection method. However, it must be understood that the invention may also be employed in connection 'with the Aiken double bend dellection principle. The

cathode ray tube illustrated in Figure 4 incorporates thev n instant invention and is in many respects similar to the arrangement shown in Figures l and 2 but employs the advantageous inherent focussing principles of the Aiken double bend deflection method. In the cathode ray tubes employing this type deection arrangement the internal components are divided generally into threemajor sections: primary, transition, and secondary or high voltage. The primary section includes a pair of electron guns 50 and 50', capable of delivering an electron beam S2 and 52 respectively, two linear arrays of horizontal deflection electrodes 54 and 54 and a pair of slotted electrodes 56 and S6'. The transition section includes two pairs of focussing and'accelerating electrodes 58 and 58'. The

secondary or high voltage section includes the composite` target screen S and a plurality of vertical deflection election electrodes 32' are energizedin an overlapping manner. That is, prior-to the instant lthe first energized electrode has reached its full charged or discharged state (depending upon which electrodes are concerned) the chargel or discharge of the next adjacent electrode is commenced.

In the preferred embodiment the primary associated with the brightness gun 50' isA operated with the cathode ofthe associated primary section 54' at zero potential, and the color gun 50 is operated with the cathode and primary at approximately l0 kv. so that the beam 52 delivered .thereby will not fall through enough .voltage to providev sufficient energy to cause same to pass through the control layer 31'. swept by the same sweep generator by connecting like deflection plates 54, 54 in the two primaries together through suitable capacitor members, and differential in the sweeping of the target bythe two beams may be effected by the use of a suitable dela'yrnetwork 72 in the control circuit for the deflection plates associated with the brightness gun 50'. If preferred, the low velocity hue beam can be made to lprecede the brightness beam when sweeping by physically placing the primary associated with gun 50 ahead of the primary associated with the brightness gun 50.

Alternatively, the differential can be introduced by changing the cathode grid voltage of the gun with respect to its slotted accelerator.

Other methods will be apparent to parties skilled in the art.

In order to effect movement of the beam 52 down the face of the target screen S the vertical deflection electrodes 32' are selectively energized in an overlapping manner such that they establish a deflecting force stiflicient to elect a second bend in the beam 52 so as to cause it to be deflected toward and into mpingement with the target screen vS at successive points down the surface thereof.y Manifestly, by properly synchronizing the energization of the horizontal deflection electrodes 54 and the verticahdeflection electrodes 32' a complete raster may be obtained.

As explained in connecion withFigures l and 2, the

ponents of the transmitted signal, while the electron gunl color beam is operative to change the potential of vari-.

It is apparent that the two primaries may be' of 'penetration l being capable of emitting a different .maar

y screen lSixt `accordance with the y* received color signal, and the .'various areas, being charged differently, will correspondingly vary lthe'depth.

l ons areas of the' target v of the'brightness beam 5`2fy whichfollows j t closely behindthe color beam 52. 'I'he saturation signal in turn effects 'time sharing-of the brightness beamv with f the different phosphorV layers by suitable modulations of the hue beam. The brightness beam SZand color beam v 52 are deflected in the manner above described and ac.- cordingly, it is not believed that a further description is necessary for a complete understanding of the'invention.

'I for registration with control layer to change'the potential thereof a predeter-` According to the provisions of the patent statutes, the f principles and mode of operation:` of the invention-have been explained, illustrated and described in what is con-A jsidered to be the best embodiments.v However, it is to` the scope of the appended l be practiced otherwise than .4

be understood that, within claims, the invention may lspecificallyillustratedfandtdescribed .y What is claimed is:

l. In a cathode ray'tube for.v usi kin the presentation of color displays, a target comprised of a plurality of phosy ulating the intensity of the phor layers and afcontrol layer v.disposed insuperposed,

layered relation with each other, each phosphor layer tion thereof, color selection meansfor delivering a-rst electron beam for registration with an incremental area of said target control layer to change the potential thereof a predetermined amount consistent with the particular phosphor layer to beenergized, and brightness .control energization of said one color layer lthereat.

2. in a cathode :ny tube for use in. the presentation of color displays responsive to the receipt of different color selection signals, a target comprised of a plurality of phosphor layers and a control layer disposed in superpoSed relation with each other, eachphosphor layer being capable of emitting a different color with energization thereof, color selection means for providing a tirst electron beam for registration with an incremental area of said target control layer to change the potential thereof a predetermined amount consistent with the particular phosphor layer to be energized, means for applying the incoming color signals to said the value of the potential change effected by said 4first electron beam, and brightness control means including means for providing a second beam for registration with 'said incremental area subsequent to said first beam to penetrate the plurality of layers to the one of the color layers indicated by the potential condition previously established by said first beam on said control layer to effect the energization of said one color layer thereat.

3. In a cathode ray tube for use in the presentation of color displays, a target comprised of a plurality of phosphor layers and a control layer disposed in superposed relation, each phosphor layer being capable of emitting' a different color with energization thereof, color selection means including means for delivering aiirst electron beam for registration with an incremental area of said target control layer to change the potential thereof a predetermined amount consistent with the particular phosphor layer to be energized, brightness control means including means for providing a modulated second beam for registration with said incremental area, and means for controlling said second beam to strike said incremental areas subsequent to said first beam to thereby effect penetration of the beam 'through said phosphor layers to the one of the color layers indicatedv by the potential condition previously established by'said first beam and to provide a brightness output of a value determined by the color with energizaf color selection means to control indicated by the potential condii of color displays, a target degree of modulation of the beam at its of registra.` tion therewith. l 4. In a cathode ray selection and brightness signals, a target comprised of a plurality of n layer disposed in superposed contactingrelatton with each other, each phosphor layer being capable of emitting a energization thereof, color selection for delivering a first electron beam different color with means'including means n an incremental areav of said vtargetmined amount consistent with the particular color signal received, brightness control means including rmeans for provding a second beam for registration with said incremental area subsequent to said first beam to thereby effect penetration of said second beam through the control layer and the superposed phosphor layers to the oneof the y color' 'layers indicated Vby the Apotentialv fcondition Mpreviously established by said first beam, and means for modsecond beam in accordance with the value of the received brightness signal.

5. In acathode raytube for use in the presentation other to change the potential thereof a predetermined amount consistent with the particular one of the phosphor layers to be energized at each area, and brightness control means including means for providing a second beam for deflection by said deflection means into registration with-each incremental area independent of the' other incremental areas subsequent to .registration of said first beam therewith to effect energization ofthe color in-- dicated by the potential condition by the control layer las established by said rst beam. i

6. In acathode vray tube for use in tiection means disposed in adjacent spaced relation with selection meansincluding means for said target, color delivering a first electron beam`A between said target and said deflection means for selective deflection into registration with an incremental'area of said target control layer to change the potential thereof a predetermined amount consistent with the particularphosphorlayer to be energized, and brightness control means including means for .delivering a second beam between said deflection means and said target for selective deflection intov registration with said incremental area subsequent to said first beam to thereby effect energization of the color indicated by the potential condition established on the control layer by said first beam.

7. In a cathode ray tube for use in the presentation of color displays, a target comprised of a plurality of phosphor layers and a control layer disposed in superposed relation, said control layer being comprised of a non-luminescent material and each successive phosphor layer in the target relative to the direction of travel of the beam being of a progressively increased thickness and capable of emitting a different color with the energization thereof.

8. ln a cathode ray tube for vuse in the presentation of color displays, a target comprised of a plurality of phosphor layers and a control layer disposed in superposed relation, cach phosphor layer being capable of emitting a different color with energization thereof, color selection means for delivering a rst electron beam for tube for use in the presentation of i 'i vcolor displays responsive to the receipt of different color` phosphor layers and a non-foraminous control' comprised of a plurality of phosphor layers and a control layer disposed in supern posed relation, each -ting a different color with selection means including means for providing a first with the different incremental l the presentation of color-displays, a target comprised of a plurality of c .gement registration with an incremental area ofsaid target tov v' change thepotentialthereof a predetermined amount comv f r y Y sistent with the particular phosphor layer to be energized@ l brightness control means including means for providing a second beam for registrationwith said incremental aren thereafter to thereby elfect energization of the one of the f colox layers .indicated by the potential condition'cstabv lishedon said target by said rst beam, and saturationY Acontrol means for controlling said vfirst beam to condition said target to effect time sharing of the second beam between the cliterent phosphorlayers and thereby dilute vthe-selected color. 'K 9. In a cathode ray tube for use in the presentation of color displays in accordanc'efwith the infomation cond 15 target comprised of a pluralityv of phosphor layers and a v control layer disposed in super-posed relation, each phoS- Y phor 'layer-being capable of-liemittinga-iditerent c0101' tained in incoming hue, brightness, saturation signals, a

with energization thereof, color selection means for delivering a rst electronA beam of insufficient energy t0 l penetrate the control layer for registration with anincremental areaof said target control layer to change the potential thereof a predetermined amount consistent with tion of. the one the `yaltxe vof the incoming linetsignal, brightness control for providing a secondlbeam'of Y an intensity related to the incoming brightness signal for means including means registration -with said incremental area' subsequent toy `r registration of said first beam to thereby eiect energizaof the color layers indicated by the ,l Y tential condition established on the control layer by said first beam-and saturation control means for controlling n said first beam to condition said control layer to share the second beam between the different phosphor layers in relation to the value of the incoming saturation signal.

References Cited in the le of patent UNITED STATES Pa'fmrs 2,173,257v Klemperer .A Sept. 19, y1939 i 2,227,484 Bouwers Jan'. 7, 1941 2,449,339 Sziklai Sept. 14, 1948 'vv-f2\ .455,71()v Szegho Dec.-7, 1948 2,457g175 Parker' lDe :."28, 1948 2,532,339 Schlesinger Dec. 5, 1950 2,795,731 Aiken June ll, 1957 2,802,966 Hae Aug. 131957 2,857,551 j Hansen Oct. 21, 19,58'

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