US2805360A - Image storage apparatus - Google Patents

Description

Sept# 3, 1957 J. T. MONANEY IMAGE STORAGE APPARATUS Filed Oct. 8, 1954 Patented Sept. 3, 1957 nce strasse IMAGE sroanon Arran/aros Joseph Thomas McNaney, La Mesa, Calif., .assigrnn to General Dynamics Corporation, San Riego, Cailr., a corporation of Delaware Application Uctober 3, 1954, Seriai No. delgi??? 7 Claims. (Cl. S15-11) This invention relates to image display apparatus and more particularly to image display apparatus for storing and producing lasting image displays.

In many computer, facsimile, and other electronic systems in which output data is constantly changing, it has become increasingly necessary that accurate retention of this output information at any given instant be conveniently provided for extended periods of time. It is, therefore, an object of the present invention to provide apparatus for retaining and storing image information applied thereto at any given instant.

It is another object of the present invention to provide image storage apparatus adapted to simultaneously receive image information from a plurality of sources and produce sustained joint displays of the data applied at any given time.

It is another object of the present invention to provide image storage apparatus in the form of a cathoderay type storage tube having means for selectively erasing different images from the storage surface.

It is a further object of the present invention to pro-` vide a lightweight, inexpensive image storage device utilizing simplified construction for producing lasting displays of a size suitable for simultaneous presentation to a plurality of observers.

Other objects and features of the present invention will be readily apparent toY those skilled in the art from the following specification and appended drawings wherein is illustrated a preferred form of the invention, and in which:

Figure 1 is a diagrammatic elevation View of a storage device illustrating an embodiment of the invention,

Figure 2 is a sectional view taken along line 2 2 of Figure 1,

Figure 3 is a fragmentary sectional View similar to Figure 2 but illustrating another embodiment of the invention,

Figure 4 is an enlarged sectional View taken along line 4--4 of Figure 3,

Figure 5 is a fragmentary sectional View similar to Figure 3 but illustrating still another embodiment of the invention,

Figure 6 is a sectional View of a cathode-ray tube embodying the invention, and

Figure 7 is an enlarged fragmentary view of a cathoderay tube screen, similar to that shown in Figure 6, but illustrating another embodiment of the invention.

In its preferred embodiments, the present invention basically comprises a device having a plurality of layers including a radiation sensitive layer which emits electrons in response to image radiations directed` thereon, an electron sensitive layer which responds to electron bombardment to produce image radiations in accordance with the electron image patterns, and a screen which transforms the total emission of the radiation sensitive layer into a plurality of isolated and discrete electron beams and also transforms the total radiations of the electron sensitive layer into a plurality of isolated and discrete radiation beams. These laminae and the screen cooperate to produce area controlled radiation feedback from the electron sensitive lamina to the radiation sensitive lamina, such that electron emission is continuously regenerated from corresponding areas of electron sensitive lamina.

Referring to Figure 1, an image storage device is shown which includes an envelope 10 having a circular configuration in the particular construction illustrated. As illustrated in more detail in the sectional view of Figure 2, a lamina of radiation sensitive material 11, a lamina of electron sensitive material 12, and a screen 13 having a plurality of openings therein are positioned within envelope 10. The particular shape of envelope 10 forms no part of the present invention, and, as shown, it may take the form of a circular cylinder 14 having end faces 15 and 15a suitably sealed thereto. Thus, cylinder 14 and end faces 15 and 15a provide, in this embodiment, a sealed container capable of being evacuated. End portions 15 and 15a are preferably transparent to radiation patterns directed thereon and, where these radiation patterns are in the form of light, transparent glass or plastic may be utilized. The cylindrical member 14 may be produced from materials similar to those of end portions 15 and 15a, however, in some applications it may be desirable to make member 14 non-transparent and thereby limit radiations to those directed through faces 15 or 15a.

Radiation sensitive material 11 serves to transform radiation t patterns directed thereon into corresponding electron images. Although the utility of the present invention is not limited to light radiations, for purposes of simplicity and clarification, the description hereafter will be given in terms of light. Accordingly, radiation sensitive material 11 may comprise material selected from the class of metals known as alkali-metals which characteristically emit electrons in the presence of light. Typical metals of this class are lithium, sodium, potassium, ceasium, calcium, strontium, and the like. In accordance with the invention one of these light sensitive materials is formed in a continuous layer` 11, positioned and arranged within envelope 10 to receive light patterns to be stored. A thin foil of the formed and effectively installed within envelope 10 in juxtaposition with transparent face 15 or, on the other hand, a lamina 11 of the proper material may be directly formed as a thin film upon face 15. Methods and techniques of preparing this light sensitive, electron emissive surface are well known in the art and many references are available, such as Television by V. K. Zworykin and B. A. Morton published. in 1940 by John Wiley and Sons, Inc. Consequently, a light pattern directed through transparent face 15 serves to energize light sensitive lamina 11 whereupon lamina 11 emits electron streams in proportion to the light intensity and thereupon transforms and reproduces the light pattern into a corresponding integral electron image.

Screen 13 is positioned within envelope 19 and serves primarily to subdivide the integral electron image produced by light sensitive surface 11 into a plurality of independent elements to form a composite image in accordance with the integral image. Screen 13 may be a substantially planar member or lamina formed of a nontransparent material and is arranged to overlay portions of the continuous light sensitive surface 11. As shown in greater detail in Figure 4, screen 13 has incorporated therein a plurality of discrete areas or electron pervious portions 16, and with lamina 11 being a light sensitive material, screen 13 may be produced from opaque glass, plastic, ceramic, or like material in which areas 16 are actual Iopenings extending therethrough, which are generally normal to the surfaces. The screen 1.3, which is opaque intermediate the areasV 16, is impervious to light transmission therethrough and may be said to be a light impervious portion which has formed therethrough the areas or electron pervious portions 16,- Y Openings ,.16 are` of a size suicientto afford .passageways forfelectronV emission from surface 11` and` also'v to afford transmission therethrough of light from electron sensitiye material,12. Openings 16 may be formed in screen 13 by'any ofseveral` suitable methods, such as molding, drilling, or photoetching'.Y In Figure 2, screen 13 is adjacent the', continuous surface 1 1 and, as shown, is inV abutting relation thereto, The opaquersreen withftsisolated transparent areas 16 serves ,to mask portions of the continuous., lightsensitive layer. 11, transforms the integral electron image; into va composite imageformed within the areas.. 16 of. screen 13, and openings. 16,1 communicating between laminae 11 and 172 provide separatereg'enerative paths between corresponding areasY of said laminae; Screen 13 also serves toY restrict the directionjof travel' ofjthe resulting electron streams forming the;c ornpfosite imageV and consequently 'restricts the area of regeneration. within limits established` bythe 'respective transparent areas 16', `I-Ivence, with a light patterndirected through transparent face 15 and upon surface 11, a correspond? ing integral4 electron imageV is produced.V Sleen, 13, inV associationA with surface 11, breaks up the'integral` electronV image into aI plurality of independent image elements to form a composite image and channels. eahof the'particular image elements toward 'predeterminedfareas onelectron'r'esponsive lamina12, y

`Itwill b e Vapparent'that the resolution of'thei composite` electron image formed'by the totality of the independent electron streams produced by the openings 16 of screenillaw isdependent upon the number of openings per unit area of the screen. openingsin screen 13 resolutionwill be increased and the composite 'electron image transmitted through openings .i 16 will more nearly 4approximate-'the integral electron` image formedV onsurfa.ce11. As shown in the sectional view'oflFigure 4, apertures 16 arequite evenly distributed and arranged throughout the screen 13, however, the particularV arrangement of the apertures 16 forms no part of' thepresentlinvention andfromthe following description it will become readily apparent to those skilled; in the arti lthat the size, arrangement, and distribution of the saperev tures may be systematically organized for specific appli= cations. 'For example, itrmay be desired to utilize apertures of graduated sizes and thereby provide variations in, resolution over the surface of the screen. Furthermore,

vit has been determinedlthat the pathlength travelled'by the plurality oflelectron streams throughthe 'apertures I6. of screen 13 isirnmater-ial tov theV operation of the device, however, the thickness of -screenV 13 should be suingcient tovr withstand the required potential4 gradients de A veloped` across.. it.

surface having actual openings therein, it shou-ldbe understood that otherernbodi'ments ofthe screen are contemplated., For instance, screen 13 may be in the form of amosaic plate comprising Vanmltiplicity of transparent, nonconductive.. particles Visolatedj one fromfanother by an Y Y opaque material. The resulting screen `is functionally similar tojscreen 13 "illustrated in Figure`4and, when overlayi-ng, photoemissive surface 11, serves to convert the integral electron image into the. composite imageforrnedl by thefmultiplicity of independent electronrstre'ams Which-- are transmitted to lamina 12Via the isolated non-conductive-particles, The transparent. characteristic of the par` VVticlesuaffords'v a regenerative .feedbackI path from.- lamina. 12vtog1aminav11lto thereby rte-energize exposed areasof thelightfsensitive surface. 11;

Y Referring Lto FigureZ, the laminal of electron sensitivematerial ;12,4 which serves to convert 'electronibombard- Obviously, by increasing. the 'number ofj' 4 1 is arranged to receive the various electron streams forming the composite electr-on image. Y Inv terms of light, lamina 12 may be produced from the generally used phosphors of zinc, cadmium, or calcium which are commonly termed fluorescent materials. As in cathode ray tube applications, fluorescent layer 12 is continuous and may be in the form of a thin llm or coating .which can be produced by the settling out of the phosphor material from a water suspension by methods familiar to those skilled in the art. Electron sensitive lamina 12` is` arranged adjacent' the transparent face 16 but may be formed directly upon face 16 by the settling process or by usingV a volatile liquid such as acetone with a small amount of binder and spraying the electron sensitive material on surface 16. Electron sensitive layer 12 is preferably coextensive with the apertured area yof screen 13 and, thus, with a light pattern directed upon surface 11 an electron image is produced thereby which screen 13 subdivides into a multiplicity of independent electron streams corresponding to the image produced on surface 11 and directs, each stream to a particular area on the fluorescent surface 12. Light is generated at surface 12 in responsetothe electron bombardment. Inasmuch as openings` 16 allow the transmission of light therethrough, as Wellas electron streams, the light produced by a particular electron stream comprising the composite image is channeled backv to surface 1'1 through the same opening throughwhich the energizing electron stream travelled. In this manner regenerative feedback isy provided tore-excite the portion oftheV continuous surface llfwhich originally produced 'the elecf tron stream in response to an element ofthe incident lightA image. Since the electron sensitive lamina. 12 is arranged adjacent the transparent end portion 16 of envelope '10, the 1 light image produced upon surface 12 will be visiblet-V ductive layer 25 is connected to the voltageV divider 22 by. a lea-d25. It will become apparent that means other,

- than conductive layer 25 may be utilized to Yestablish the*` field -between laminae 11 and 12. For example, where electron sensitive lamina 12is aV goodconductive surface,

then the positive potential may be applied directlyVV thereto -by' connecting lead 25 `directly to lamina 12, However,

as. illustrated in Figure 2, conductive layer 24fis Varranged Vadjacent to and coextensive-with` the light sensi- `55 Although screen 13Sy has. been vdescribed iii-'terms offen tive layer 12. Layer 24 is 'n preferably a verythintrans-V parent coating or hlm of material such as-silver, cadmiurm or aluminum, 'and the various electron streams which make. -up thercomposite electron image have-sufficientV energy to. penetrate. layerr24 and impinge Vuponv thelelecfV tron sensitive lamina 12. Since layer 24 is transparent, the light. generated by` lamina 12 also'penetrates layer` 24, passes through areas 16 in screen 113;and1re-energizes the yassociated surface elements of'lamin-a 1I.Y "It, therefore, becomesV apparent that the presenceof 'conductivelayer 24`.does.not adversely falfect the operation ofthe device. However, where layer 2'4--is utilized, its position with` respectto lamina. 12 isimmateri-al and they may be transposed without materially affecting -theoperation-of;

thedevice. A

' in? operation, a light patternfis. directed-through trans-f parent face 15 and onto the light sensitive layer llvthereby Vcausing eachV incremental tareaV illuminated by the light upattern to producean integral `electron image which has la.pattern-andV density that corresponds in detail "to f the` pattern and density ofthe incident light-image. VThe electric field established across laminae 11 and 12 serves to direct the integral electron image as a unit toward the electron sensitive lamina 12. However, screen 13, as illustrated in Figure 2, is interposed between the layers and masks portions thereof. Hence, the integral electron image is dissected into a plurality of independent image elements by the configuration of screen 13 to form the composite electron image. Each of the plurality of discrete electron `beams forming the composite image has 1a magnitude proportional to the intensity ofthe light falling upon the corresponding area of layer 11 underlying an opening 16 in screen 13. Each of the electron streams flowing from layer 11 is confined within an opening 16 `of screen 13 and forms an element of the integral image generated at lamina 11 in response to the incident light image.

, The electric field applied to the electron beams travelling through areas 16 in screen 13 imparts suiiicient venergy to the beams to cause them to penetrate coniductive layer 25 and impinge upon electron sensitive lamina 12. In response to bombardment lby the various electron streams, area-s of lamina 12 in the path cof the streams are caused to generate light--the intensity and pattern `of which is proportional to the intensity and pattern of the respective electron beams. The areas of light and shadow thus produced on lamina 12 -form a light image which is generally similar to the incident light pattern directed through transparent face 15 onto lamina 11. The light im-age produced on Vlamina 12 is visible through transparent yface 16 `of envelope 10.

Regenerative action is established which serves to sus tain the secondary light image developed on lamina 12. This regeneration is realized by the feedback of light from lamina 12 through the transparent conductive layer 24 :and the openings 16 `of the collimating screen 13 and onto the light sensitive layer 11. It, therefore, becomes 1apparent that a plurality of regenerative feedback paths are provided and the light from each element of the secondary light image is confined within the same `opening of screen 13 as that in which the corresponding electron beam which produced the light was conned. The `electric field impressed across laminae 11 and 12 may be utilized t-o control, in effect, the degree of regeneration. .By varying the potential applied to conductive layer 24, control may be indirectly exerted `over the amount of light feedback to lamina 11 and lthis consequently provides regulation of the intensity of the light image displayed on surface 12 and viewable by an 'observer through member 12.

In Figure 3 is illustrated a display device including light sensitive layer 11, electron sensitive layer 12, and -screen 13 all of which are structurally Iand operationally similar to those `described hereinbefore. Elements 11, 12 and 13 are enclosed within an envelope 19a which comprises transparent -faces 31 and 32 and an fannular member 33 to which faces 31 and 32 may be suitably sealed. The `faces 31 and 32 are preferably `constructed of a transparent material such as glass or plastic although other materials that Iare optically transparent may be used. Assuming that faces 31 and 32 are glass and lan electrically non-conductive material, faces 31 and 32 are made electrically conductive. The electrically conductive `coating applied to the glass surface is also substantially transparent optically. A preferred method of providing the transparent conductive lcoating is known as iridizing and is fully described in U. S. lPatent 2,522,531 entitled, Method of Producing Electrically Conductive Coatings on Glass and -Mica Sheets. The unitary structure of transparent faces 31 and 32 comprising the glass surface and a transparent conductive layer of i-ridized tin is commercially available and is generally known as electrically conductive glass. Alternatively, transparent conductive faces 31 and 32 may include a glass surface and a conductive layer applied thereto by a vacuum-evaporation process, such as a layer of evaporated aluminum, or lby a sputtering process, such as a layer of sputtered gold..

As shown, an electric field is established between faces 31 and 32 by direct interconnection of source 21 through voltage divider 22 and leads 23 and 2S to surfaces 31 and 32, Operation of the device illustrated in Figure 3 is similar to that described hereinbefore. A pattern of light and shadow is directed through the transparent face 31 and vonto the light sensitive member 11 whereby an integral electron image is generated which is proportional to the light and shadow of the incident light pattern. The voltage applied to the conductive faces 31 and 32 from the source 21 yestablishes the electric field across the continuous laminae 11 and 12 and serves to direct the integral electronic image toward lamina 12. Screen 13 is interposed between the laminae and overlays portions -of each, hence, the integral electron image produced `on layer 11 is broken up into a multiplicity of independent image elements in accordance with the opening 16 of screen 13. Each of the image elements thereby produced has a magnitude proportional to the intensity lof the light 'falling upon the corresponding area of layer 11 underlying the particular opening in the screen. As stated hereinbefore, the electric eld established between laminae 11 and 12 serves to accelerate the various elements forming the composite image toward the electron sensitive layer 12, and screen 13 with the electron pervious areas 16 therein serves not only to transform the integral electron image into the elements forming the composite image but also aids in preventing spreading and scattering of the electron image elements in traveling from lamina 11 to lamina 12. In response to bombardment by the various electron streams, areas of the continuous surface 12 in the path-of the streams are caused to generate light. The light pattern generated by lamina 12 in response to the independent electron streams forming the composite image and channeled to the electron sensitive lamina 12 via the openings of screen 13 serves to reenergize corresponding portions of surface 11. Energy feedback to lamina 11 is focused by the openings 16 to the particular element of layer 11 from which the energizing electron stream originally emanated. rfhis area restricted feedback is regenerative and serves to produce a sustained composite light image on layer 12 which may be viewed through the transparent -end face 32.

As illustrated in Figure 5, a continuous light sensitive lamina 11,-screen 34, and lamina of electron sensitive material 35 are positioned within the envelope 10a, which includes transparent conductive faces 31 and 32 and the cylindrical member 33 suitably connected between the faces 31 and 32 to provide an enclosed container. A voltage is impressed across laminae 11 and. 35 by the connection `of leads 23 and 25 to the conductive portion of transparent faces 31 and 32. Thus, with a light pattern directed through end face 31 and onto the continuous light sensitive layer 11, an integral electron image is produced by layer 11 which has a pattern corresponding in detail to the incident light pattern. Screen 34 is generally similar to screen 13 described hereinbefore and illustrated in Figure 4 and is preferably a planar member of non-transparent material which has a plurality of small openings therein, such -as the openings 16. The lamina ol' electron sensitive material 35, which serves to transform electron images into light, may comprise one of the fluorescent materials mentioned hereinbefore, however, in this display device the fluorescent lamina 3S is arranged within the openings of screen 34. Thus, it becomes apparent that within screen 34, lamina 35 is a discontinuous layer and is more in the form of isolated islands of electron sensitive material surrounded by the opaque areas of screen 34 and together the screen and fluorescent mate rial constitute a continuous layer. The electron sensitive material may be established within the openings of screen 34 by the well known process of settling out of the phosphor material from a water suspension. Screen 34 is arranged adjacent the continuous light sensitive surface 11,

` tivematerial-withirrrthe-V openings oli/screen 34 andlight' generated by-loneelementl oflami'n-a `35Jis. channelled by the Vsurrounding opaque portions of screen- 34 to a partieular incremental,areaofsurfacelll. It becomes apparentdy at'tlie--Tfeedbacsk fr'om elements of fluorescent layer 135f`to`associated areas'yoflayer 1-1 isl regenerative. This-area controlled regenerative feedback serves to producea sustainedl composite light? image onlayer 35, and being arranged adjacent the, transparentA end' portion 32 of' envelope 10a, the light image produced thereon will v bevisibleto an observer. Although envelope a is illustrated in the drawings and' describedv in detail in conjunction-with the` description andoperation of lamina 11, screen; 34, andi electron sensitive lamina 35, shown in Figurer 5, it 'is understood that envelope 10 and suitable means for impressing the voltage across Ithe laminae as shown'and described in connection with Figure 2 may be el'ectivelylutilized. Y

VReferring now-to Figure 6 a cathode ray type image storage "devicerisillustrated which includes an evacuated envelope '40? enclosingafstorage screen 41 to be described in detail hereinafter, an electron gun 42 for generating, focusing, and' accelerating af beam of electrons toward causing the electron'beam tobe deilected to various areas ofscreen41. Y Y V,

' Theelectron gun 42 positioned atan end of envelope 40' preferably comprises a cathode 44, a control electrode 45; Iand an accelerating anode 46. Associated with electron gunV 42 and positioned along the path of the electron beam isthe set of deection plates 43. For purposes of simpli'cation a` single 'pair of deflection plates is illustrated which will serve tov deflect the electron beam in a-singl'e plane upon areas of storage screen 41, however, it will' be apparent that Ian additional pair of deection plates may be incorporated toV provide deflections -of the electron-"beam in a plane normal to that afforded by the plates illustrated. Thus, in response to 4signals lapplied to 4both pairs of deflection plates 43, the `electron beam maybe directed to any. desired area fon storage screen 41. -An anode4'7 is positioned-between deflection plates 4'3 andstorage'screen-41 and serves both to accelerate the yelectron .beam and to collectphotoelectrons gene-rated by elementsofV the lstorage screen41 under conditions toV be describeldin'detail hereinafter. The particular contiguration=ofanode 47 forms nopart'ofthe present invention and may 'bei conveniently embodied as a conductive wall-:coating on the inside of'tubc envelope 46,

"Storage screen 41 is' positioned within the evacuated envelope 40 and 'inthe path of the electron lbea-m generated'by'electron gunr42. Inthe embodiment illustrated in Figure 6V screen 41 includes a layer-of'. light sensitive material '11; a layer of electron sensitive material 12, and a' screen 13 interposed between said laminae. Screen 134 'has vopenings 16 therein which provide independent vpassageways for both electron streamsemitted from `surface 11 .and light radiation produced from electron sensitive material 12; Storage screen 41 may also include .a pair of transparent, conductive layers 48 `and 49 which are positioned adjacent. the layersv 11 and 12, respectively,

Y and ,serve 'to apply-Yacceleratingvoltages thereacross.

Storage screenAL may alsortzomplise;ailarninazofelectron Ystorage-screen 41, and a set Iofgdellection plates 43 for Y sensitive material 501 `arrangedlm todi-rectly receive; elec-i tron 'images Aformedfby:the incident electron e-bearnL gene erated by-guny `42," and" transform said-electronimages into?.A

corresponding; -lightimages.V v

Meansiirthe forni-ofa voltage divider, :referred itoA generally by reference numeral 52, Y is 'connectedV acrossA a; source offdirect;currentI voltage (not show-n) and'serves to Aprovide; suitable electric eldsacross lamina 11, and; lamina. 12, as-wellas maintaining the'various electrodes, such-as-anode747f and the elementsl ofthe,VV electron gunk 42, at their proper operatingfvoltage levels.-V i divider-'52 includes droppingresistorswSS through 579 and with they source Yofj Voltage connected with proper ,polarity` acrosslthef terminals indicated-F and' the voltage apj-f Y pliedtoconductive layerA 49-by lead 61,'under normal:

operating conditions, willfbe Vmaintainedlat apositive potential withl respect to the Voltage applied to the'c'onduc-.

tive layer V48 by lead 62; `Hence,V thenvoltage appliedV across laminae 11`v and V12 is' the voltage drop appearing across resistor 54. Throughl connection by `lead 63; to. the junction of dropping resistorsY 55 Vand 56, suitable..

operating voltageis afforded anode 47, .and under normal' operating conditions anode"47ismaintained ata voltage level lower than either'the voltagejapplied' to lamina 1'1 or laminalZ. 4Theelements of electron gun 52 are main,-V tainedat suitable operating potentials by. being connected; as shown, across droppingresistorsSS and 59 ofnetwork 52: y

A'lead 6,4'isv connected'` to controlY grid 45 ofY electron gun Hand-provides means for applying,V an intensityrsignal thereto. which` serves to trigger the electron, beam generated by cathode v44' oirA anden.V Leads 6,5 and66 areonnectedjto the deflection pilates 43' and providev meanspfor applying signals. thereto whereby `the electronV bearnngenerated by gun'42is. selectively: directed overdifferent areasl of'storage screen 41,.

'j In, operation with a suitable energizing si'gnal'applied` overV lead"`6`4'l to control electrode 45, an electron beam is generated by cathode 44 avndj,directed/along,the,axis;VV

ofienvelope` toward'the storage screen-41, In travel'- ling .toward screen'41, theV electron beamis directed betweenV deflection plates 43. By the application of signals to deflection plates 43v via leads 65 and V66, the electron beam may be selectively directed to dierent areas fon screen 41, andby well' known circuits the beam maybe A caused jto b esscanned, if desired, across the storage screen 41' in ,anyV desiredraster. Y V

Directedl toward storage screen 41,' the electron beam strikes .the electron sensitive layer with suflici'ent energy i to cause it toV generate a light image in accordance withl lzinc, cadmium, or calcium. lWhere utilized in association witharelativelylow energy electron beam, layer 50'serves top'adapt the-essential storage elements ofV the storage screen 41 to cathode ray tube applications`, and itV will become apparent to those skilledin 'the art thatlamina '50i is noti essential in cathode ray storage tubes wherein high energy Acathode raybeams are utilized.' 'In these` latterfapplication's, the `high energy. electronfbeam possesses sulicientenergy-to'penetrate layer 48 and layer`11,

traverse; the openings '16,V in screeng13and kstrike the; electronsensitivev layerI 12, whereupon 4a light image is generated inracoordance with the incident electron image formedbylthe beam; However, for purposesof claritication, uoitescentllamina, 50'is incorporated in the-embodimentfillustratedin Figure and theV light'images t' formed'thereon Vin response to bombardmentby the elec-V tr'on `beam, pass through the transparent conductive layer 48'andv strike light sensitive layerll; V Conductive layerV 48- is similar to vconductive Vlayerj24,.

described in connection with` Figure 2 andV ils'spreferably' 7 5 asverytthin., transparent cating offmaterial," such-'as alu- Voltage minum.Y As illustrated in Figure 6, the transparent` tinuous layer and generates an integral electron image,v

corresponding in detail to an electron image directed upon layer 50 by the cathode ray beam. Screen 13 is positioned adjacent the light sensitive layer 11 and serves primarily to subdivide the integral electron image produced on surface 11 `into a plurality of independent elements which together form a composite image in accordance with the integral electron image. Screen 13 is structurally and functionally similar to the screen 13 shown in detail in Figure 4. As described, screen 13 is preferably a planar member, or lamina, of opaque material which is arranged to overlay and mask portions of the continuous light sensitive surface 11. Screen 13, with openings 16 therein, not only dissects the integral electron image formed on surface 11 into the independent elements of the composite image, but also serves to restrict the direction of travel of the resulting electron streams and consequently proi vides separate channels for each of the composite image elements directed toward the electron responsive lamina 12.

Under normal operating conditions, the electric fields applied between laminae 11 and 12 produce forces on the resulting electron streams which accelerate the bundle of streams through the channels formed by openings 16 toward electron responsive lamina 12. Lamina 12, which serves to convert electron bombardment into corresponding light patterns, is a thin film or coating functionally similar to layer 50 and may be similarly produced from any of the fluorescent materials mentioned hereinbefore. Hence, in response to bombardment by the electron streams, light elements are generated by lamina 12 which correspond to the electron elements forming the composite electron image, and the aggregate of the light elements produce an image corresponding to the composite electron image formed on the surface of lamina 11 adjacent screen 13. It, therefore, becomes` apparent that each element of the light image produced on lamina 12 is energized by an electron stream derived from an area of surface 11 which lies beneath the opening in screen 13 associated with the particular incremental area of lamina 12 which produced the light element. j

The light image formed upon lamina 12 by the individual light elements may be made visible through the transparent conductive layer 49 and a transparent end face 67 of envelope 40, As described hereinbefore, the image displayed on lamina 12 is sustained thereon through rep generative feedback of light to iiuorescent lamina 11. A plurality of independent regenerative feedback paths between laminae 12 and 11 are provided by the openings in screen 13, which is interposed between the laminae. Light t from each element of the image appearing on lamina 12v is channelled back to lamina 11 through the same opening in screen 13 in which the particularenergizing electron stream travelled in producing the particular light element. Thus, elements forming the light pattern generated by lamina 12 in response to the electron streams forming the composite electron image, serve to re-energize the areas of surface 11 that originally produced the light element and in this manner the image described on lamina 50 by the electron beam produced by electron gun 42 is stored as a corresponding image visible through the end face 67 of the cathode ray tube.

The cathode ray display and storage device also includes circuit means 71 for selectively removing different retained images from storage screen 41. Circuit means 71 is associated with the elements of the voltage divider 52, which serves to establish predetermined electric fields between the light sensitive lamina 11, electron sensitive lamina 12, and anode 47 for retaining the images produced by the cathode ray beam, and in addition to essential components described in connection with voltage divider network 52 includes an electron tube 72 having an anode 73, a cathode 74, and a control electrode 75. Anode 73 may be connected directly to terminal of voltage divider 52 and the anode circuit is completed by connecting cathode 74 through a resistor 76 to the junction between dropping resistors 5S and 56 of divider 52. A grid return resistor 77 is provided, which is connected between an input terminal 78 and the junction of control grid 75 and a second input terminal 79. Thus, it may be seen that electron tube 72, with its associated components is actually in parallel with dropping resistor 55 and functions to selectively control the voltage applied to anode 47 over a voltage range sutlicient to permit storage and image display or selective erasure of previously stored images in response to external signals.

Under operating conditions for writing, displaying, and storing an image, electron tube 72 is non-conductive and voltages are established by voltage divider 52 and applied to elements of the cathode ray tube which maintain anode 47 at a voltage level lower than either the voltage applied to lamina 11 or lamina 12. For descriptive purposes, it may be assumed that to establish the aforementioned normal operating conditions, the values: of the various dropping resistors are so chosen that a potential of 10,000 volts appears at terminal a potential of 9,000 volts is established at the junction of resistors 53 and 54, and apotential of 8,000 volts is established at the junction of resistors 55 and 56. When it is desired to erase a previously stored image or a portion thereof a signal voltage is applied to control electrode 45 over lead 64 which serves to turn the electron beam on. By the application of suitable deection signals applied to the deilection plates 43 over the leads 65 and 66, the electron beam is then directed to the area of the storage screen 41 tol be erased. To actually initiate erasure of the image, an external selective erase signal is applied to electron tube 72 through input terminals 78 and 79. Electron tube 72 is thereby driven to become conductive whereupon dropping resistor 5S is essentially short circuited. Thus, the junction between resistors 55 and 56 is raised to a voltage level approximating the assumed 10,000 volts applied to terminal of voltage divider network 52. Under these conditions and with accelerating anode 47 interconnected by lead 63 to the junction of resistors 55 and 56, the voltage applied to anode 47 is raised to approximately 10,000 volts and to a voltage level substantially higher than either the voltage applied to lamina 11 or lamina 12. Hence, electron emission from lamina 11 is now directed toward anode 47 as a result of the potential gradient appearing therebetween and electron emission is materially reduced in a direction toward lamina 12. This action reduces the electron iiow from lamina 11 to lamina 12 below the critical point necessary to energize iiuorescent lamina 12. and thereby removes this portion of the image. Anode 47 will remain at a positive voltage level with respect to both laminae 11 and 12 during the period the external selective erase signal is applied to the input terminals l and 79 of tube 72, and upon removal of this signal, anode 47 is restored to its normal Voltage level and the device is returned to its normal operating conditions for Writing, storing, and displaying an image.

Where a high energy electron beam is produced by the cathode ray tube, the fluorescent layer 50 may be eliminated and the device will function in generally the same manner. The ability of an electron beam to penetrate thin conductive layers, such as conductive layers 48 and 49, is well known and the incident electron beam generatedby-electron gun '42 and `directedupon'tlle storage .i

screen` penetrates lightsensitive Vlayerpllfas vvellasconductilvelayer'48,Y passes through theopenings 176of`scree'n 13; andl impinges upon electron sensitive lamina 12.' Light produced'by lamina 1'2"is1directed,` back to lamina 11'.' and is localized' by the openingsin screenluto'those areas oflamina 11 underlying' the illuminatedv openings ofthe.` screen. jllluminationof larninallv causes photoelect'rons. Y to -be generated 'in proportion to" the impinging,lightpand` these photoeliectrons are directed through the same open- A modification' of the storagescreen `shown.in Figure g-isillfustrated in Figure 7 and includes a continuousllight sensitive lamina 11, Va screen 81having a plurality 'of openings therein, and a lamina of electronV sensitive material 82 which is` arranged within the openings-of screen 81. An electric field'is impressed across lamina 11 and the elements comprising lamina 82 by the leads61 and `62'which.

.are interconnected between the voltage divider SZ' described in connection with Figure 6, and to conductive.

endface `253 and directlyto the continuous light sensitive lamina 11', respectively. Lead 63 serves, to interconnect the accelerating anode 47 with the'junction of'dropping resistors 55' and 56'and thereby'supplies both the normal f storage potentials andselective erase potentials thereto. Transparent conductive end face 83' is provided which mayv bey fabricated from` electrically conductive. glass produced by methods referred to hereinbefore and' issuit-V v ably sealed to envelope S4.

zjsoasad produced Vby the u-orescent materialV arrangedjirrtliejI openings of screen 81 serves to energize adjacent por? Y leads '61'and 62, Hence, conductive layers-48"an'd 49 v Y illustrated in Figure ,6 also may be effectively eliminated.

Screen 81 is generally physically andV functionally simi-. i

larito screen 13 described hereinbefore and illustratedin Figure 4and is preferably a planar member of non-transparent material which has a plurality of'small openings. therein in the orderof affew thousandths of anv inch, such as openings 16. Fluorescent phosphor material 82;A which serves to transform electron images into 1ight,.is arranged withinthe openings. by, for example, a settling process. Thusjtogether the'screen 81 and the iluorescent material 82' form a surface ofisolated elemen-ts of electron .sensiofthe screen. Y Screen.81` with the areas of. uo'rescentmaterial thereinis interposed betweenthe electrically conductive glass surfacev 83V andlthe continuous light` sensitive surface V11; The opaque portions ofscreen 8 1"k serve to mask out portions of laminall and prevent 'diffusion and.

written'by the beam thereupon is transformed into plu-... rality `of .independent light elements, the sum of which.

correspond to the incident electron image. The ilight tions ofthe continuous-light 'sensitive lamina 11,V rIhe re- 'sulti'ng electron imageV thereby producedV on laminaVT 11 serves to relenergize the corresponding adjacent elements o of lluorescentmaterial S2 interposediin the nonftrans.-

` parent :screen 81. A.This regenerative actionproducesthe n desired. retention of theimage. written by the electron Y beam generated` by the cathode ray tube which maybe readily viewed through the transparent end face S3.

Y i It will; be apparent tlratselective erasure ofthe entire image, 4or any portion thereof, maybe accompli-shed in the mannerv described hereinbefore. in connection Awith Figure. 6'.Y By the application `of "a "selective erasesignalA to. input terminals 78 and 79V of electron tube 72 associfV ated withV voltage divider 52, anode. 47 Vis' switched4 to .aj Vvoltage level which is higher thaneither that applied tonv lamina 11 or, conductive face8`3 whereupon thelimage o underlying thearea of.. the screen to which the incident Velectro'nvbeam is directed is removed. o l While'certain preferred embodiments of .the invention Y have been specically disclosed, it is understoodthat the invention is not Vlimited theretoV las many variations will be readily apparent to those skilled in the art,=and the invention is to be givenoits broadest possible interpretation within the terms of the following claims:v v

What I"claim is: A Y

ll. In .an image storage device including a laminar electronnsensitive material yarranged to receive electron image emission and transform saidimage Vemission into corre- Y splondinglight radiation patterns, a laminar light radiation sensitive material adapted to cause transformationof light radiation patterns-into corresponding electron image emission, said image emission beingdirected toward said elec-v tron'sensitivemat-erial; at least one of saidlaminae being Y Y a continuous surface, the improvement Icomprising a screen having at least yone light -transparent electron perviousvA portion andat least one non-conductive light impervious portion, said. screen being interposed 'adjacent saidlaminae and arranged to overlay said continuous surface,- `said electronpervious portion being adapted to pass electronV tive material completely surrounded by the opaque areas scattering of'li'ght from the individuali areas of''uorescent l material. K Y

,Under operating |conditions for writing and storing an image, voltage conditions developed 'by voltage divider 52' 'and' applied over the leads 61, 62 and 63 establish the conductive surface 33 at a voltage applied to ac-celerat- Ving anode 47 at a voltage level lower than that applied- Vto lamina 11. Thefelectron beam produced 'by the electron gun of' the cathodelray. tube and directed toward vthe storage screen has 'sufficient `energy Vto penetrate photo-V cathode :.11 and impinge'directly upon the surface formedl by the screen 81 and 'the isolated areas ofiluorescent'vv material 82 i formed Withinthe screen; i The areas` of fluorescent material 82. which are bombardedf'by the-electronfbeam generate light ypatterns in accordance -withi'the patternl described by the incident electronbeam. Howg Vever, with-'the configuration of the opaquescre'en '815 andVY uorescenti'areassvSZ4 asdescribedjtheelectronimager` "emission therethrough andsaid impervious portion being,V

adapted to isolate light radiation from saidrelectron sensi` tivematerial, said screen being adapted to provide improvedregeneration over limitedV areas of said laminaef 2. In an. image storage device including a laminay of "electron sensitivejmaterial arranged to receive electron image emission and transforml said image emissionlinto corresponding light radiationl patterns, ala-mina of light v radiation sensitive material adapted' to Icause transformation of'lightiadiation patterns into'corresponding electron image emission; said image emission beingdirected toward said. electr-on sensitiv-ematerial, at least one; of

saidrlaminae. beingY al continuous surface, the improve-V ment comprising a screen having Ia plurality 4of light transf parent electron perviou's portions and a plurality of non- Aconductive light impervious portions, saidscreen being interposed adjacent said laminae and 'arranged to'overlay saidl 'continuoussurfacd said electron pervious portions lbeing 'adaptedito pass electron emission therethrough and, .said imperviousportions beingadaptedto isolate lightV radiation fromsa-id electron sensitive material, said screen Y regeneration. over being adapted .to provide improved limited areas of said lamin'ae.

' 3; An4 evacuatedx image. srt-orage device oomprisingfin". combination 1a lamlnar electron-,sensitive material adapted* .to receive .electron imageemission'a'nd transform said image emission into correspondinglight radiation patterns, Va laminar photo emissivematerial capable o f receiving said light radiation patterns andtrausformingsaid patterns .into corresponding electron image emission, said 75 image' emission being'directed 'toward 4said electron Isensitive material, at least one of said laminae being a continuous surface, and a screen having a light transparent electron pervious portion and a non-conductive light impervious portion, said screen being interposed adjacent said laminae and arranged to overlay said continuous surface, said pervious portion being adapted to pass said image emission, said impervious portion being adapted to isolate light radiation from said electron sensitive material, said screen being adapted to provide improved regeneration over limited areas of said laminae.

4. An evacuated image storage device comprising in combination a laminar electron sensitive material adapted to receive electron image emission and transform said image emission into corresponding light radiation patterns, la laminar photo emissive material capable of receiving said light radiation patterns and transforming said patterns into corresponding electron image emission, said image emission being directed toward said electron sensitive material, at least one of said laminae 'being a continuous surface, and a screen having a light transparent electron pervious portion and a non-conductive light impervious portion, said screen being interposed ladjacent said laminae and arranged to overlay said continuous surface, said pervious portion being adapted to selectively accept and pass said image emission, said impervious portion being adapted to isolate light radiation from said electron sensitive material, said screen being adapted to provide improved regeneration over limited areas of said laminae, and means for establishing an electric field between said laminae, said means being `adapted to cause acceleration of said image emission toward said electron sensitive material.

5. An evacuated image storage device comprising in combination a laminar electron sensitive material adapted to receive electron image emission and transform said image emission into corresponding light radiation patterns, a laminar photo emissive material capable of receiving said light radiation patterns and transforming said patterns into corresponding electron image emission, said image emission being directed toward said electron sensitive material, at least one of said laminae being a continnous surface, and a screen having a light transparent electron pervious portion and a non-conductive light impervious portion, said screen being interposed adjacent said laminae and arranged to overlay said continuous surface, said pervious portion being adapted to pass said image emission, said impervious portion being adapted to isolate `light radiation from said electron sensitive material, said screen being adapted to provide improved regeneration over limited areas of said laminae, said electron sensitive material being disposed within at least a portion of said electron pervious portion, and means for establishing an electric field between said laminae of materials, said means being adapted to cause acceleration of said image emission toward said electron sensitive material.

6. In a cathode ray device including means for producing and directing a high energy electron beam emission along said device including an accelerating anode, a storage screen positioned within the device in the path of said beam emission, said storage screen including a first laminar electron sensitive material adapted to transform said beam emission into corresponding light images, a laminar light sensitive material arranged to convert said light images into corresponding electron image emission, a second laminar electron sensitive material adapted to transform said image emission in corresponding light images, said image emission being directed toward said second electron sensitive material, at least one of said latter two laminae being a continuous surface, and a screen having light transparent electron pervious portions and non-conductive light impervious portions, said screen being interposed adjacent said latter two laminae and arranged to overlay said continuous surface, said pervious portion being adapted to pass said image emission, said impervious portion being adapted to isolate light radiation from said electron sensitive material, said screen being adapted to provide improved regeneration over limited areas of said latter two laminae, means for establishing predetermined electric fields between said light sensitive material, said second electron sensitive material and said accelerating anode to provide retention of said images, said means including a circuit arranged to change said retaining fields for selectively removing retained images from the screen.

7. In a cathode ray device including means for producing and directing a high energy electron beam emission along said device including an accelerating anode, a storage screen positioned within the device in the path of said beam emission, said storage screen including a laminar light sensitive material capable of converting light images into corresponding electron image emission, a laminar electron sensitive material adapted to selectively transform said electron beam emission and said image emission into corresponding said light images, said image emission being directed toward said electron sensitive material, at least one of said laminae being a continuous surface, and a screen having light transparent electron pervious portions and non-conductive light impervious portions, said screen being interposed adjacent said laminae and arranged to overlay said continuous surface, said pervious portion being adapted to selectively accept and pass said image emission, said electron sensitive material being disposed within at least a portion of said pervious portion, said impervious portion being adapted to isolate light radiation from said electron sensitive material, said screen being adapted to provide improved regeneration over limited areas of said laminae, means for establishing predetermined electric fields between said light sensitive material, said electron sensitive material and said accelerating anode to provide retention of said images, said means including a circuit arranged to change said retaining lelds for selectively removing retained images from the screen.

References Cited in the tile of this patent UNITED STATES PATENTS Re. 23,802 Sheldon Mar. 16, 1954 2,594,740 DeForest et al Apr. 29, 1952 2,605,335 Greenwood et al J'uly 29, 1952 2,683,832 Edwards et al July-13, 1954 2,699,511 Sheldon Ian. 11, 1955 2,773,992 Ullery Dec. 11, 1956

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