US2907907A - Cathode ray tube apparatus - Google Patents

Description

Oct. 6, 1959 J. T. MCNANEY cATHoDE RAY TUBE APPARATUS Filed Dec. 13, 195e Oct. 6, 1959 J. T. MCNANEY 2,907,907

' CATHODE 'RAY TUBE APPARATUS Filed neo. 1s, 195e s sheets-sheets NN N\ l N. E LL INVENTOR. JDSEPH T'. MCNANEY BY j mM TTUQNEY.

Oct. 6, 1959 J. T. McNANEY 2,907,907

Y CATHODE RAY TUBE APPARATUS I Filed Deo. l3.5551956 l 5 Sheets-Sheet 3 l INVENTOR. Jose-PH T. MCA/AMEX Y .BY www ATTORNEY.

Oct. 6, 1959 v J. T. McNANEY 2,907,907

CATHoDE RAY TUBE APPARATUS i 5 `sheets-sheet 4 Filed Dec. 13. 1956 BY n TTOQNEY mw E N, \\\\\\\\\\\N.

Oct'. 6, 1959 J. T. MCNANEY CATI-IODE RAY TUBE APPARATUS 5 Sheets-Sheet 5 Filed Dec. 13, 1956 CA'IHODE RAY TUBE APPARATUS Joseph T. McNaney, La Mesa, Calif., assignor to General Dynamics Corporation, Rochester, N.Y.,k a corporation of Delaware :Application December' 13, 1956, Serial No. 628,044 16 Claims.` (Cl. 313-70) The present invention pertains to cathode ray tubes capable of displaying intelligible information on a viewing screen in the form of letters, numerals 'and symbols which may, for example, be representative of the identity and position of aircrafttlying in space.

Present display system requirements are not being fully met by existing cathode ray tubes. It is desirable from the standpoint of operatingeliiciency to includein such tubes a form of memory or storage to retain data which may represent target identity for continuous display on a large situation display viewing screen. Practical viewing areas of screens in display cathode ray tubes having storage or memory and developed thus far, have generally been rather limited to small usable viewing diameters.

It is .an object of the present invention to provide an evacuated'display apparatus wherein the viewing` screen may be of a large diameter and is not limited in size by the diiculties of existing memory devices.

It is another object of this invention to provide apparatuslcapable of utilizing a memory or storage means for the' purpose of retaining desired data, which data may then be selectively ydisplayed and positioned on a viewing screen.

. It is another object of this invention to provide a cathoderay tube apparatus capable of storing selected data and allowing the projection of such data to desired positions on the viewing screen under the control of independent deilection data.

It is another object of this invention to provide improved resolution of displayed message characters over those obtainable by use of the more conventional storage tubes.

It is another object of this invention to provide an electrostatically controllable electron emissive cathode system for generation and projection of the ultimately viewed information.

It is another object of this invention to provide electron emissive means whose areas of emissivity may be controlled with regards to electron density and time by control means all positioned within the evacuated container or cathode ray tube.

`It is another object of this invention to provide electron emissive cathode means capable of generating sustained character shaped beams 'whose cross-sectional shapesand duration of emission are determined by electrostatic charge Writing methods.

It is another object of this invention to establish electrical charges on the control surfaces of a cathode whereby these charges will control the emission of electrons in accordance with the pattern of electrical conditions established thereupon.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanyingdrawings, in which:

Figure 1 is a simplified schematic of one embodiment of the invention showing in a block diagram form conventional control circuitry; j

Figure 2 shows an enlarged diagrammatic View of a' light sensitive cathode ray or second beam generator pref-i erably utilized in Figure 1;

Figuresl 3, 4, 5 and 6 are enlarged and fragmentary cross-sectional views of portions of further embodiments" of the second beam generator;

Figure 7, a partial view 'in perspective, shows in greaterj detail, the construction of the control means or elementi of the second beam generator as shown in Figure 2;

Figure 8 shows an additional embodiment of a sec-' ond cathode beam generator of a thermionic type;

Figure 9 is still another embodiment of a beam con-,j

trol for the second beam generator;

Figure l0 s a schematic view. of an additional embodiment of the invention wherein the rst beam generator:

is displaced from the tube axis;

Figure ll illustrates a beamA shaping member suitable:

for use in the invention. Referring to Figure l, an evacuated container or envelope 11, shaped as a cathode ray tube, has disposed symmetrically with respect to the longitudinal axis oiA the envelope 11 a target or screen 10 located at one end thereof. The target 10 may be of any known electron: responsive target construction and utilizes preferably electron to light conversion, such as, phosphor construction.l

The constituent parts of the preferred embodiment of the invention as shown in Figure l includes a primary electron message character beam generator or rst beam generating means 13, a first deflection system 14, a beam4 selection aperture plate 15, a second deflection system 1'7 and asecondary electron beam control generator or; second beam generating means 19. In cooperation with these parts a system of individual electron lenses 21,22;4 and 23 have Vbeen provided, which in combination with: beam accelerator 25, may be utilized to direct and project electron :beamsf along their desired or prescribed paths.' A third deection system or unit 27 is used to `dellect electron beams generally from axis to predetermined areasof the target 10. Both the deflection systems and the lens systems may be of known electromagnetic or electrostatic construction and are Vexemplified herein as elec` tromagnetic construction.

The lens systems, namely, lirst lens system 21, second lens system 22 and third lens system 23 which, as stated, may be, for example, of an electrostatic or electromagnetic type, is exemplied as of an electromagnetic construction. Such a desired construction is also disclosed,`

in detail, incopending applications Serial Nos. 507,856, now Patent No. 2,824,250, and 507,902, both assignedto the common assignee of this invention.

Primary beam generation or rst beam generating means 13, may utilize any known electron beam generating cathode construction, such as thermionic or photoelectric, but is preferably vshown as a thermionic cathode.' The first generator 13 generates and projects an electron beam through a beam shaping matrix 91 of the general type shown in Figure 1l, thereby projecting a rst beamV Figure 11 thereby deriving one or a plurality of character' shaped electron beams. At least a selected beam cross-' section ofthe first beam cross section 31 may be .selectedy and directed through an aperture 30 in aperture plate 1i Patented Oct. 6, 9

which is capable of selecting one of a plurality of cross sections Ygenerated by first generator 13.

The magnetic lens or rst lens system 21 assists in the control of such beams by causing the electrons of the beam 31 to converge on, and cross-over at, substantially,

the midpoint of the first deflection system 14 along the longitudinal axis. Lens system 21 may also be so designed as to effect an image of the beam cross section 31, as generated by first generator 13, at the plane of the aperture plate 15. After a beam has been selected through the aperture 30, a second lens system or magnetic lens 22, acts on the beam to cause it to converge on, and cross over at, substantially, the midpoint of the second deflection system 17 Yand along the longitudinal axis. Deflection system `17 effects imaging of the selected cross sections upon an electrostatic potential control surface of the second electron beam generator or second beam generating means 19. The second deflection system 17, which is supplied withpredetermined control voltages from the second deflection amplifier, permits the selected beam to be directed to any desired position upon the control surface of the secondary beam generator 19.

The second beam generating means may be a planar unit or a curved unit, it being exemplified in the preferred embodiment as parabollically shaped to aid in directivity of the re-emitted second beam cross section. Operational details of this generator 19 will be explained in conjunction with descriptions of its various embodiments wherein the electrons generated and projected may be generated in the manner shown in Figures 2, S and 9. However, in general, all electron beams stored or reemitted therefrom, or therethrough, will be the cross sectionalconfiguration or shape of the actuating first beam cross section, which of course, may be in the form of message characters, such as symbols, letters and numerals, as predetermined by the selected beamcross section 31. 'Ihe ability to maintain electron emission, as va second beam cross section `35, from the secondary beam generator i19, in the form of predetermined shaped beams, will be a function of the control characteristics of the generator which will also be explained along with the descriptions of the embodiments.

Electron beams emitted from the second lgenerator 19 are caused by the action of the third lens system or magnetic lens 23 to cross overV at a point substantially along the `axis and substantially at the midpoint of the second deflection system '17, and, to image on the surface of the aperture plate 15. Application of desired control voltages, from second deflection amplifiers, to the deflection system 17, will permit any one or group of electron beams from one or a plurality of predetermined shaped beams or second beam cross sections 35 to be directed, or selected, through the aperture v30. The magnetic lens 22 then efectsfocusing of the selected shaped beam of electrons or second cross section to cross over at a point midway of the first deflection system :14. Application of predetermined bias voltages to deflection plates 14 will, for example, cause the selected second cross section or beam 36 to be deflected off the longitudinal axis and into the field of the magnetic lens 21. The selected beam 36 is deflected around the character beam generator 1'3 and returned to the longitudinal axis of the tube at a point substantially midway of third deflection system or deflection yoke 27 by lens 21. The third deflection system 27 may deflect the beam 36 to cause impingement of the beam cro-ss section at any desired position on the screen or target 10.` Y

Generally speaking, only two types of information inputs are needed, namely, writing information and beam selection-deflection or reading information. Under normal operating conditions, the first beam generating means or beam shaping gun 1-3, is used to write SGCOildaTY detron charge potentials upon the control surface of the generator 19 in response to coded input information usually furnished by a computer.` These potentials mayv be distributed over discrete areas of the generator 19, namely, on its control surfaces, in conformance with the shape of the one or more beams selected from the one or plurality of first beam cross sections 31. This may be accomplished by establishing positive potentials on selective portions of the control surfaces through secondary emission in a manner that will become more apparent later. These potentials once established will be retained to control and shape electron beam 35 until erased. When it is desired to establish certain conditions of emissivity on the control surface of generator 19, or write, energizing voltages from a pulse generator 40 are applied to the control elements of the electron source "13 and a control element of the generator 19 whereby both of these are energized to a potential that will permit a secondary emission condition on the control surface of generator 19. The application of pulsed potentials may be under the control of write control circuitry A41, which may be a simple switching device suchV asl an Eccles-Jordan fiipflop, as -is well known in the art. After the writing is accomplished, second generator 19 retains the charge potentials caused by the first beam cross section as electrostatic charges thereon until erased by gun l13.

Various embodiments of the second beam generating means are included in this invention, namely, Figures 3, 4, 5 and 6. The important dierences in these embodiments reside in their construction and method of control.

In each case the operation of second beam generating means 19 depends upon certain well known principles employed in cathode ray storage tubes, namely, that induced conductivity may be effected in or upon certain electrical insulating materials by means of high energy electron beam bombardment. In Figures 3, 4, 5 and 6 the secondary beam gener-ating means y1'9 utilizes an electrically resistive material 56, `56a and 56b, hereinafter referred to as resistive material 56, that may be charged in a positive sense with respect to the energized photoemissive cathode 5-1 when subjected to bombardment by high enengy electrons fromV gun source 13. This bombardment results in secondary electrons being emitted from material 56 in areas contacted by the electron beam 31, which Vemitted electrons are collected by collector 50 leaving a positive condition on the surface of material 56. At the time it is desired to write character information on resistive material 56, the'photocathode 53 is in a non-energized condition and collector 50 has a given potential. The given potential on collector Sil at this point is insufficient to provide a voltage differential between collector 50 and resistive material 56 that will permit a secondary emission condition to occur on the surface of resistive material `56. When a write control pulse is received from write control circuitry 41, pulse generator 40 supplies output pulses to the beam generating gun 13 and the collector i50. The pulse received by collector I50 raises its positive Voltage to a magnitude where the voltage differential between the potential on collector 50 and the' potential of resistive material 56 is sufficient to permit `secondary emission to occuron the surface of resistive material 56. The pulse received by gun 13 from pulse generator 40 causes a high energy electron beam 31 to be projected onto the resistive material 56. The Ybeam 31 bombards the surface of the resistive material 56 causing secondary electrons to be knocked therefrom, which electrons are collected by collector 50. The secondary electrons knocked from the surface of material '56 exceed the number of primary electrons absorbed by material 56. This occurs `since there is suffrcient positive potential magnitude on collector 50 to draw the secondary electrons from the surface vof material S6. The loss of secondary electrons by the surface of material '56 creates a positive voltage condition to exist on the Vsurface bombarded by beam 31. After the ypositive voltage condition has been established on desired areas of material 56, the gun 13 is de-energzed and the positive voltage pulse supplied to collector50 is terminated. The reduced magnitude of the potential on collector 50 is now insuiicient to permit secondary emission to occur but will not atfect the positive condition already stored on the surface of material '56. The resultant voltage impressed on the selective areas of resistive material 56 from mpingement by beam 3'1 will have a potential that is positive with respect to emitter 51 in the energized condition and less positive than collector 50. The electron beam generated by emitter y51 will now pass through the areas of the material S6 that have a more positive charge thereon and will substantially not pass through the areas of material '56 not bombarded by beamf3l1. Thus, resistive material S6 is capable of shaping the electron beam generated by emitter 51. When it is desired to erase the` positively charged areas on material 56, the beam generating gun '13 is energized projecting an electron beam 31 that will ood the surface of material '56. This bombardment of the material 56 by beam 31 will not cause a secondary emission condition to occur because no positive pulse is supplied to collector '50. Thus, the potential differential between material `56 and collector 50 is insufficient to permit eifective secondary emission. The electrons in beam 3!1 are therefore able to remove the aforesaid positive conditions on the surface of resistive material y56 through their negative charges. The theory and operation of various such devices are set forth and described in detail by M. Knoll and B. Kazan in Storage Tubes and Their Basic Principles, published by lohn Wiley & Sons, Inc., New York, New York.

One of the preferred embodiments of second generator |19 is shown in Figure 2. In 'Figure 2, the beam control generator 19 includes an electron collector 50, an electron emitter 51, and a transparent window support 52 in envelope 1-1. An electrically conductive surface 52 energizedy by a lead-in conductor 54 is preferably disposed on support 5'2 and contiguous with the emitter 51 and a resistive material '56 is placed on the surface of emitter 51 in substantially the manner shown in Figures 3 and 4. The grid 50 is provided with a lead-in conductor 55. The emitter 5&1 may be thermionic or photo emissive and is shown as of the photocathode type. Emitter 51 may be energized from any light source and is exemplified by an external light source y60, which source includesra lamp `61 and light reilector 62. When the emitter 51 is exposed lto light rays -63 it will emit photoelectrons through resistive material 56 as second beam cross sections 35. Resistive material 56 either prevents or permits passage of the photo electrons therethrough and effects shaping of second beam-cross sections 35 in response to its induced charge pattern. Collector S0 can function either as a collector for secondary electrons emitted from material '56 or as an overriding grid control. y

Figures 3, 4, 5 and 6 present fragmentary views of the beam control generator 19 with four-different construction arrangements which may be utilized to control or modulate electron emission therethrough or therefrom. Figures 3, 4 and 5 are varied construction arrangements of the second beam generating means 19 as shown in Figure 2, and Figure 6 is an additional embodiment of means 19 as shown in Figure S. In each of the Figures 3, 4 and 5, electron emissive material Slis deposited on a conductive coating 53, which, in turn, -is supported by the window or support S2. In Figure 3 an electrically resistive material 56 in the form of spaced apart islands, is applied to the emitting surface of the photocathode 51. The resistive material may be any known material, metallic or non-metallic,` which is capable-of secondary emission and of a high electrical resistance, such as talc, carbon and others, -as set forth in bibliography of Storage Tubes and Their Basic Principles Ibid. In Figure 4, a similar resistive material 56a is applied directly to the conducting layer V53 in spaced apart islands with a material in the intervening spacing. In Figure 5, the` resistive material 5619 is supported on a fine wire mesh or perforated conductive or non-conductive element 57, which mesh or element 57 is located adjacent the photocathode 51.

Figure 6 will be adequately explained in connection with Figure 8. l

In lFigure 7, a three-dimensional view of a small section of -a beam control generator 19, as exemplified in Figure 4, is shown for the purpose of showing the electron control grid 50 in greater detail. The construction of the grid 50 is such that it will provide individual apertures or openings, 0.009 x 0.009", for example, through which the individual characters shaped cross sections, emitted from the surface of the photocathode 51, maypass. Each opening frame or grid opening performing the function of a switch as well as an electron accelerator. The photocathode may, in this case, be in the form of a mosaic of islands of light responsive materials separated by the electrically resistive material 56a. 'Ihe photocathode or light responsive materials 51 may be of any known type such as set forth in my copending applications Serial Nos. 568,236 or 604,931, now Patent 2,850,657. The light responsive materials 51 are applied or coated on the conducting layer 53 which, in turn, is supported on the inner surface of the window 52. An insulating spacer 70, such as mica, glass, and so forth, is shown in the various embodiments to support and establish the predetermined mechanical relationship and spacing of the grid S0 with respect tothe remaining parts of the structure 19. l

Under preferred operating conditions, the control grid 50 serves as a collector of secondary electrons emanating from the resistive material 56. This emission of secondary electrons occurs when the resistive material 56 is subjected to bombardment by high energy electrons from the rst beam generating means 13 which eiects the writing of static charges on material 56. After positively charged patterns have been established on resistive material 56, generally Within the contines of the individual aperture frames of grid 50, excitation of the appropriate portions of cathode 51 will cause emission of photo-electrous, namely second beam cross section 35, in the form of individual message characters. The grid 50, having a more positive potential applied toit than the cathode 51 will also cause the second beam cross section 35 to be accelerated through the respective apertures or frame of the grid 50 in the direction of the midpoint of the second deflection plate system 17 onaxis. The curvature of the second beam generatingv means 19 could additionally aid in focusing all emitted electrons at the stated midpoint of system 17.

Another embodiment of the beam control generator 19 is shown in Figure 8 exemplifying a thermionic emitter. The structure, shown in detail in Figure 6, includes an emitter support housed Within and adjacent envelope 11. Supported by emitter support 75 is a concaved portion 76 having deposited thereon 'an oxide cathode material 77. Any known thermionic electron emitting material may be used for cathode material 77, such as thorium oxide, barium oxide or the like, or any ofthe known dispenser type cathodes may also be used. In a heat transfer, a heater element 78 is provided with a pair of electrical energizing conductors 79 to effect desired heat transfer or heating of the concaved portion 76 and materialV 77. The operation of the thermionically emissive cathode 77 is similar to the previously described structures except that the photo-emitter 51 has been replaced with the thermionic emitter 77. The wire mesh V57a has likewise been provided with the electrically resistive material 56h, as shown in Figures 5 and 6, which is deposited thereon.

In another embodiment of the beam control generator 19 as shown in Figure 9, the second beam generating neans `19 may Vinclude means to modulate another elec- .tron beam in a manner that Will provide second beam beam cross-section`86 by flooding and projection through the storage grid 50. Included in the means is a conventional cathode ray gun 80, having a heater 81, a'cathode 82, a control grid 83 and an electrostatic lens 84. A low velocity electron beam 85 is generated and projected by gun 80 into the magnetic eld of the lens 23, iiooding the perforated grid 50 carrying the electrically resistive material V57a (i.e., electrostatically chargeable material 56b may be supported by a wire mesh 57 as shown in Figure Prior to `the passage of electrons 85 through the openings of the modulator element 57a, the beam of electrons will have been formed in accordance with the electrical potentials established by rst beam cross section 31 on the control surfaces adjacent the openings therein. With the potential upon grid 50 and the iield strength of the lens 23, the modulated beam 86 is caused to converge at the midpoint of the deflection system 17 on the axis. From thereon, the previously described operational conditions may be utilized.

The manner in which electrostatic charges are established on the resistive elements 56 of the control surface in Veach embodiment is similar. It should also be understood that once the conditions for modulating the second beam cross section have been established, the control of the character shaped beams 35, derived from the generator 19, is similar in each embodiment. For additional information regarding the theory involving the establishing of a charge pattern on the surface of resistive materials 'by means of secondary emission, attention is called to the aforestated book Storage Tubes and Their Basic Principles.

Figure lOexemplifies an additional embodiment Wherein the tirst beam generating means 13 is displaced from the axis of the envelope or tube 11. The generating means 13 may, for example, generate the entire character format desired and be lensed to a cross-over peint at, for example, a coplanar set of electrostatic selection plates 90. Plates 90 would be capable of selecting the desired one or more first beam cross sections 31 to be passed through auxiliary aperture 30a in plate 15. The entire parts, namely, iirst beam generating means 13, plates 90 and auxiliary aperture Sila may be so aligned as to cause the selected iirst beam cross section to be projected to the midpoint on axis of deflection system 17.

This embodiment would simplify the deflect'ing of second beam cross section 36 around means 13 as shown in Figure 1, in that cross section 36 would be selected on axis through aperture 3i) and thereafter be capable of final position deflection by dellection system 27. l

The particular embodiments of the invention illustrated and described herein are illustrative only and the invention includes such other modifications and equivalents as may readily appear to those skilled in the art and in the scope of the appended claims.

I claim:

l. In an evacuated envelope having a longitudinal axis, the combination comprising, an electron responsive target at one end thereof, a second beam generating means positioned at the other end of the envelope and substantially symmetrically disposed with respect ot the axis, a irst beam generating means positioned intermediate the target and the second beam generating means and substantially adjacent the axis, an aperture plate positioned intermediate the rst and second beam generating means transversely disposed with respect to the axis and having at least one aperture therethrough, said first beam generating means being adapted to cause projection of a plurality of first beam cross sections toward said aperture plate, said aperture being adapted to cause a selected beam c 'ross section of said plurality of first beam cross sections to pass therethrough, said second beam generating means being capable of responding to said rst beam cross section a'n'd being adapted to cause selectively stof.

in'gof said first beam cross section and projection `o`f 'a second beam cross section corresponding in cross section configuration tothe first beam cross section through said aperture plate at said aperture for impingement upon said target. l

2. In an evacuated envelope having a longitudinal axis, the combination comprising, an electron responsive target at one end'thereof, a second beam generating means positioned at the other end of the envelope and substantially I symmetrically disposed with respect to the axis, a rst beam generating means positioned intermediate the 'target and the second beam generating means and substantially symmetrically disposed with respect to the axis, an laperture plate positioned intermediate the first and 'second beam generating means transversely disposed with respect to the axis and having an aperture therethrough coaxial with the axis, said iirst beam generating means being adapted to cause projection of a plurality of'r's't beam cross sections toward said aperture plate, said aperture being adapted to cause a selected beam cross section of said plurality of iirst beam cross sections to pass therethrough, said second beam generating means being capable of responding to said iirst beam cross section and being adapted to selectively cause storing o'f said rst beam cross section and projection of a second beam cross section corresponding in cross section conguration to the irst beam cross section through said aperture plate at said aperture for impingement upon said target.

3. In an evacuated envelope having a longitudinal axis, theco'mbination comprising, an electron responsive target at one end thereof, a second beam generating means positioned at the other end of the envelope and substantially symmetrically disposed with respect to the axis, a irst beam generating means positioned vintermediate the target and the `second beam generating means and disposed o the axis, an aperture plate positioned intermediate the rst and second beam generating means transversely disposed With respect to the axis and having two apertures therethrough, one of said apertures being disposed coaxially with and along said axis, and the other of said apertures being disposed oi' the axis, said first beam generating means being adapted to cause projection of a plurality of first beam cross sections toward said aperture plate, said other of said apertures being adapted to cause a selected beam cross section of said plurality of lirst beam cross sections to pass therethrough, said second beam generating means being capable of responding to said rst beam cross section and being adapted to selectively cause storing of said iirst beam cross section and projection of a second beam cross section correspond-A ing 1n cross section coniiguration to the iirst beam cross section through said aperture plate at said one of said apertures for impingement upon said target. I

4. In Aan evacuated envelope having a longitudinal the combination comprising, Van electron responsive target at one end thereof, a second beam generating means positioned at the other end of the envelope and substantially symmetrically disposed with respect to the axis, said` second beam generating means including an electron charge storage mesh and an electron generator positioned adjacent each other with the mesh intermediate the generator and the target, a first beam generating means positioned intermediate the target and the second beam generating means and disposed substantially adjacent the axis, an aperture plate positioned intermediate the irst and second beam generating means'transversely disposed with respect to the axis and having at least one aperture therethrough, said lirst beam generating means being adapted to cause projection of a plurality ofirst beam cross sections toward said aperture plate, said aperture being adapted to cause a selected beam cross section of said plurality ofrtirst beam cross sec- .t.1on$t.0, Passthejfethfough, 'Said second beam generatingmmeans being capable 'of responding to said selected beam cross section of said section on said mesh as an electrostatic charge-pattern,Y said generator beingadapted to cause electron emission to project or shadow through said mesh a second beam cross section corresponding in cross section to the electrostatic charge pattern stored on said mesh, said sec- .ond beam cross section being projected through said` Vaperture for impingement upon said target. l

5. The invention in accordance with claim 4 wherein the electron generator includes a light radiation respon- Vsive photocathode disposed at the other end of the en- Y the-electron generator includes means for generating and projecting a low electron velocity ood beam, said flood beam being adapted to cause electron illumination of said mesh and shadowing said stored second cross section upon said target. Y

8. In an evacuated envelope having a longitudinal axis, the combination comprising an electron responsive target at one end thereof, a second beamV generating means po'- sitioned-at the other end of the envelope and substan' tially symmetrically disposed with respect to the axis, a first beam generating means positioned intermediate the target land the' second beam rgenerating means and adjacent the axis, an aperture plate positioned intermediate th'e first and second beam generating means transversely disposed With respect to the axis and having at least one aperture therethrough, said first beam generating'means being adapted to cause projection of a plurality of iirst beam cross sections toward said aperture plate, said aperture being adapted to cause at least' a selected beam cross section of said plurality of rst'beam cross sectionsto pass therethrough, said second beam generating means being capable of responding to said iirst beam cross section and being adapted to selectively cause storing of said first beam cross section and projection of a second beam cross section corresponding in cross section conlguration to the rst beam cross section through said aperture plate at said aperture for impingement upon said target, and 'a plurality of deflection and convergence rst lbeam cross sections and." being adapted to cause storing of the rst beam crossl cent said aperture plate for imaging said selected beam cross section upon' said second beam generating means, a thirdflens systemV disposed substantially adjacent said second beam generating means for imaging said second beam cross section at said aperture, a second deection system positioned intermediate the aperture plate and the second generating means for selectively positioning said second beam cross section through said aperture, said second lens system being adapted to cause said second beam cross section to cross over at saidv rst deection system, said tirst deection system being further capable of deflecting said second beam cross section around said rst beam generating means, a rst lens system p0- sitioned adjacent said irst beam generating means for effecting desiredimaging and cross over of said second beam cross section, and a third deflection system intermediate the irst lens system and the target positioned adjacent the cross over effected by the rst lens systeml for deecting the second beam cross section to impingement at a desired position upon the target. v

10. In an evacuated envelope having a longitudinal axis, the combination comprising an electron responsive target at one end thereof, a second beam generating means positioned at the other end of the envelope and substantially symmetricaily disposed With respect to the axis, a first beam generating means positioned intermediate the target and the second beam generating means and displaced from the axis, an aperture plate positioned intermediate the rst and second beam generating means transversely disposed with respect to the axis and having one aperture therethrough disposed coaxially with the axis and an auxiliary aperture aligned with said rst beamgenerating means, an electrostatic character selection` means positioned intermediate said first beam generating means and said aperture plate in alignment with said rst means and said auxiliary aperture, said rst beam generating means being adapted to cause projection ofy a plurality of first beam cross sections tow-ard said Y aperture plate, selection means being capable of deflect` ing said first cross sections to cause at least a selected beam cross section of said plurality of first beam cross sections to pass through said auxiliary aperture, said second beam ygenerating means being capable of respondingl v to said selected beam cross section of said iirst beam means for'eiecting desired beam cross overs and imaging of the beam cross sections.

9. :In an evacuated envelope having a longitudinal axis, the combination comprising an electron responsive target at one end thereof, a second beam generating means positioned at the other end of the envelope and substantially symmetrically disposed with respect to the axis, a rst beam generating means positioned intermediate the target and the second beam generating means and substantially symmetrically disposed with respect to the axis, an aperture plate positioned intermediate the iirst and second beam generating means transversely disposed with respect to the axis and having at least one aperture therethrough, a iirst deection system positioned intermediate said rst beam generating means and said 'aperture plate, said iirst beam generating means being adapted to cause projection of a plurality of rst beam cross sections toward said aperture plate, said rst deflection system being capable of deecting said first cross sections t0 cause at least a selected beam cross section of said plura-lity of iirst beam cross sections to pass through said aperture, said second beam generating means being capable of `responding to said selected beam cross-section of said iirst beam cross section and being adapted to cause selectively storing of said iirst beam cross section and projection of a second beam cross section corresponding in cross section coniiguration to the selected beam cross section, a second lens system disposed substantially adjacross section and being adapted to cause selectively storing of said lirst beam cross section and projection of a second beam cross section corresponding in cross section configuration to the selected beam cross section, a second lens system disposed substantially adjacent said aperture plate for imaging said selected beam cross section upon said second beam generating means, a third lens system disposed substantially adjacent said second beam generating means for imaging said second beam cross section at said aperture, a second deflection system positioned intermediate the aperture plate and the second generating means for selectively positioning said second Y beam cross section through said aperture, said second lens system being adapted to cause said second beam cross section fto cross over at said first deflection system, and a third deflection system intermediate the second lens system and the target positioned adjacent the cross Vover effected by `the second lens system for deilecting the second beam cross section to impingement at a desired position upon the target.

l1. In an evacuated envelope having opposite ends the combination comprising, an electron responsive target at one end thereof, a rst electron beam generating means positioned intermediate said target and the other end of said envelope for projecting a rst electron beam cross section toward said other end, a second electron beam generating means positioned at said other end of said envelope and responsiveto impingement by said l rst electron beam cross section for selectively storing the image of said first beam cross section for a desired period of time and for subsequently projecting a second l1li electron beam cross section havingan image corresponding in cross sectional conguration tolsa'idrst beam cross section for impingement upon s-aid target. K

12. In anevacuated envelope having opposite ends the combination comprising, an electron responsive target at one end thereof, a first electron beam'generating means positioned intermediate said target and the other end of said envelope for projecting a first electron beam cross section toward said other end, a second electron beam generatingA means positioned at said other end of said envelope and responsive to impingement by said first electron beam cross section for selectively storing therimage of said first beam cross section for a desired period of time and for vsubsequently projecting a second electron beam cross section having an image corresponding in cross sectional configuration to `said first beam cross section for impingement upon said target, said second beam generating means including an electrostatically controllable electron emissive means, and said electron emissive means being capable of storing said first beam cross section electrostatically.

13. In an evacuated envelope having opposite endsthe combination comprising, an electron responsive target having at one end thereof, a first electron beam generating means positioned intermediate said target and the other end of said envelope for projecting a first electron beam cross section toward said other end, a second electron beam generating means positioned at said other end of said envelope and responsive to impingement by said first electron beam cross section for storing the image of said first beam cross section for a desired period of time and for subsequently projecting a second electron beam cross section having an image corresponding in cross sectional coniiguration to said first beamY cross Section for impingement upon said target, said second beam generating means including an electrostatically controllable electron emissive means, and said electron ernissive means being capable of projecting said second beam cross section corresponding to electrostatically stored charges created on said emissive means by said first beam cross section.

14. In an evacuated envelope having a longitudinal axis land opposite ends, the combination comprising, an electron responsive target at one end thereof, afirst electron beam generating means positioned intermediate said target and the other end of said envelope and disposed adjacent said axis for projecting a first electron beam cross'section toward said other end, a second electron beam generating means positioned at said other end of said envelope substantially symmetrically disposed with respect to said axis and responsive to impingement by said rst electron beam cross section for selectively storing theimage of said rst beam cross section for a desired period of time and for subsequently projecting a second. electron beam crossl section having an image corresponding in cross sectional configuration to said first beam cross section for impingement upon said target.V

15. In an evacuated envelope having a longitudinal axis and opposite ends the combination comprising, anv

electron responsive targent at one end thereof, a firstY electron beam generating means positioned intermediate said target and the other end of ysaid envelope and substantially symmetrically disposed with respect to andi along said axis for projecting a first electron beam cross section towardsaid other end, a second electron beam generating' means positioned at said other'end of said envelope substantially symmetrically disposed with respect to said axis and responsive to impingment by said first electron beam cross section for selectively storing the image of said first .beam cross section for a desired period of time and for subsequently projecting a second electron beam cross section having an image corresponding cross sectional configuration to said first beam cross section for impingement upon said target.

16. In an evacuated envelope having a longitudinal axis and opposite ends the combination comprising, an electron responsive target at one end thereof, a rst electron beam generating means positioned intermediate said target kand the other end of said envelope and disposed off said axis for projecting a rst electron beam cross section toward said other end, a second electron beam generating means positioned at said other end of `said envelope substantially symmetrically disposed with respect to said axis and responsive to impingement by said first electron beam cross section for selectively storing the image of said first beam cross section for a desired period of time and for subsequently projecting a second electron beam cross section having an image corresponding in cross sectional configuration to said rst beam cross section for impingement upon said target.

References Cited in the file of this patent UNITED STATES PATENTS France Aug. 15, 1951

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