US2915660A - Beam shaping member for a shaped beam tube - Google Patents

Description

Dec. 1, 1959 J. T. MONANEY BEAM SHAPING MEMBER FOR A SHAPED BEAM TUBE Filed April 21, 1958 @QQQ hi l w N R M m c M MT m H I w OW .N 3 $536 wizgm mbau u 42:28 FDQZ JOUFZOU uuOI Wm 9536 9536 nm 55% 55% "55 J 2050:

ATTORNEY.

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BEAM SHAPING MEMBER FOR A SHAPED BEAM TUBE Joseph T. McNaney, La Mesa, Califl, assignor to General Dynamics Corporation, Rochester, N.Y., a corporation of Delaware Application April 21, 1958, Serial No. 729,761

4 Claims. (Cl. 313-68) ments in a beam shaping member utilized within the shaped beam tube to effect desired cross sectional shapatent ing or configuration of the electron beam in its path from origin to a target. For purposes of explanation the present invention is exemplified in a shaped beam tube which displays a character-at-a-time upon its screen. Such a tube may be defined generally as a shaped beam tube capable of displaying upon its target or screen for viewing a single character at a time in response to coded input information. Tubes such as these are in considerable demand in such fields as type setting, telegraphic code conversion, computer indicating devices, outputs for testing instruments and the like. In many of these and other uses, it is often desirable to display for prolonged periods if need be, the character upon the face or the target of the tube. By prolonged periods is meant a period longer than that of the persistence of a phosphorescent screen.

To accomplish such a prolonged display, several di-ffering approaches may be utilized. It is possible to utilize adjacent the. screen a mesh network capable of storing secondary emissive charges in a desired pattern. Subsequent flooding of the storage mesh network with a beam of low velocity electrons permits shadowing of the charge pattern thereon onto the screen. .Charge patterns so flooded with low velocity electron beams present on the screen, characters having a rather poor quality and resolution.

The instant invention overcomes these difficulties. The invention contemplates a new and improved beam shaping member for the shaped beam tube. Theinvention permits the selection of the character to be'displayed from among a plurality of characters presented by the beam shaping member, in stencil-like form, and, will further permit the selective display of that sole character for prolonged periods of time, if desired, by controlling the character to be displayed at its point of formation rather than after its shaping. The present invention therefore does not sacrifice resolution or clarity of the character itself.

In general, the invention includes an electron beam generating means capable of generating and projecting an electron beam which may be selectively formed into focused and a defocused condition. The beam is projected generally along the tube toward a target capable of responding thereto. Selection means positioned about the path of the beam are provided to effect deflection of the beam from the axis. A beam shaping member is positioned spaced apart from the selection means in the path of the beam and intermediate the selection means and the target. In addition, desired electron lenses are provided to effect the necessary imaging of the beam "and its subsequent cross section or character shape to the desired points along the shaped beam tube to effect a character display upon the target. The beam shaping member provides a plurality of cutout stencil-like portions through which the beam may be passed. Upon the side of the beam shaping member facing the selection means and the beam generating means, may be disposed either integrallywith' the base of the member or as an additional element disposed upon the base, the latter being shown and described herein, an insulating material, such as talc or the like, capable of accepting and retaining electron charges. Such insulating material may be generally disposed about the openings or stencil-like portions formed through the base of the beam shaping member. Upon bombardment by a focused electron beam, the material (which is initially negative charged), may be made to have a charge more positive adjacent the particular character or stencil-like portion bombarded than the areas adjacent the other characters not so bombarded. Subsequent utilization of the defocused or flood beam will then cause an attraction of negative beam electrons through the opening so positively charged and a repelling of flood electrons from the other negatively charged openings. In this manner, the character chosen may be displayed for such prolonged period until the flood beam is de-energized.

It can therefore be seen that the present invention provides a very simple and throuble-free construction for effecting a character-at-a-time display upon the screen of a tube for a prolonged period of time, if so desired.

In addition to the objects and advantages aforestated, it is an object of the invention to provide a simple and trouble-free character-at-a-time display on a shaped beam tube.

It is another object of the invention to provide a shaped beam tube whose display has a duration of persistence such as may be desired by an operator thereof.

It is another object of the invention to provide a compact and simplified construction capable of generating at least a character-at-a-time for display which character has a resolution and clarity limited only by the optics and final target resolving capabilities.

Objects and advantages other than those set forth above will be apparent when read in connection with the accompanying specification and drawings, in which:

Figure 1 is a view in schematic of a shaped beam tub embodying the instant invention;

Figure 2 is an enlarged plan view of the beam shaping member utilized in the invention shown in Figure 1;

Figure 3 is a side view of the beam shaping member of Figure 2.

Adverting to Figure 1, there is shown a general outline of a shaped beam tube 10 which has positioned at one end thereof an electron beam generating and projecting means 12. The generating and projecting means 12 is capable of generating and projecting an electron beam. The beam may be controlled to provide both a focused high intensity or Writing beam 13 or a defocused low intensity or flood beam 15. Exemplary circuitry to effect such focusing and defocusing actions of the beam generating and projecting means 12 is shown generally as generating control means 16. At the other end of the tube 10 is positioned a screen or target such as phosphor screen 18 capable of responding to electron impingement of the electron beam to present a visual display thereon. In the path of the electron beams and spaced apart from the generating means 12, is a selection means 20 capable of deflecting the electron beam to a desired portion of a beam shaping member 22. Beam shaping member 22 is disposed in the path of the beam intermediate the selection means 20 and the target 18. Through desired control, at least a selected stencil-like cutout portion or character 23 is selected from the plurality of such characters in the beam shaping member 22 to impart to the electron beam a corresponding shape for subsequent display upon the target 18.

To aid in the proper diverging and converging. of the electron beam, and, in the desired imaging'of the cross section of the'electronbeam at points generally along the axis of the tube 10, are a pair of electron lenses 25,

26 Y selectively controlled vby lens control circuitry 28.

I Lenses '25 and 26 image the cross section of the electron Y beam to a point intermediate an electron lens '30 sub-' sequently disposed generally along the axis and positioned intermediate the lens.26 and the screen 18. Lens 30,

through its control circuitry 32, is capable of 'eifecting an enlargement of the crosssection of the electron beam for display upon the target 18. If desired, an accelerating I anode such as anode 34 may be disposed as resistive coat-' .ing. upon the interior: of the tube 10, having positive potential impressed thereon, to aid in the acceleration of the electrons in their path to the target The various control circuits such as 16, 28 and 32, as well; as, the selection control circuits 37, 38, may, for

example, be under thecontrol of input signals distributed Y from an'exemplary control circuit network 40 to the gaforestated On-Off control circuit '41 and to a circuit providing theread and write pulses necessary to focus and :defocus the electron beam.

The general theory and operation of the beam shaping in a book entitled Storage Tubes and Their Basic'Prin- York, N.Y. I

Y ciples published by John Wiley and Sons, Inc., New

In order to obtain a better understanding of the'oper- Y 'ation of the shaped beam tube 10, Figure 2 presents an enlarged, detailed view of the beam shaping'm'ember 22.: Describing the beam shaping member 22 in greater detail with reference to Figures 2 and 3, the member; 22 may, if desired,be constructed of a base or base member 1 Y 45 through which openings 46 are provided. Openings .46 may be ofastencil-like cutout or. portion corresponding to the desired character shapes to be imparted to an electron beam to be shaped. On the side of member 45 facing the generating means 12 may be provided or disposed an insulating material, such as talc, which material will accept electron charges for storage thereon. The insulating material may, of course, be integrally made with member 45, or separately disposed upon member 45, the latter being exemplified in the instant embodiment as insulating material 48. Disposed upon the insulating material is a conducting layer 50 which may be selectively energized to collect secondary electrons from selectively bombarded areas of material 48 adjacent a given opening 46.

The exemplified construction shown in Figures 2 and 3 provides a simple layer upon layer construction in which the base member 45, with its cutout portions 46 formed therethrough, may have disposed thereupon the insulating layers 43 adjacent and generally surrounding each of the cutout portions 46, which insulating layer 48 are electrically isolated from each adjacent cutout portion and each other and may be overplated by a common conductor layer 50.

While the detailed manner of operation of the storage type beam shaping member 22 is adequately set forth in the aforestated book entitled Storage Tubes and Their Basic Principles, a simplified general explanation is presented as follows.

In operation of the instant invention, the electron beam, through its circuitry 16, is first adjusted at the generating means 12 to the flood or defocused type of beam. Prior to flooding member 22, however, the con ductive layer 50 of the beam shaping member 22 is provided from circuits 28 with a potential of a value with respect to the cathode so that a minimum of secondary electrons will be emitted from the insulating surfaces 48 during the initial flooding of the matrix :by the flood :beam; 'Thebeam shaping member 22 is then flooded with electrons from the generatingmeanslZ'b'y the flood beam, so that all of the insulating materials or surfaces 43: are uniformly exposed to the slow moving electron beam. 1 The potential of the flood beam with respect 'to the conductive layer 56) is :such that the; insulating surfaces liberate fewer secondary electrons than instant Y primary electrons. The'insulating material'48 therebybe- Y comes charged in a negative direction until it has reached approximately,thepotential at which the flood beam is generated. Then, the writing'or focused beam is formed Y and properinput signal-s cause the selection circuits 37, :38 to deflect thewriting beam to select one of the desired characters or cutout portions 46 'from the beam Y. shaping member 22. The character selected is bom Y barded by the electrons of the writing beam at and adjacent the area of thecharacter so 'selected The writing beam being of a greater intensity than the flood beam creates such electron bombardment upon the in- .sulating material 48'as to'cause liberation of secondary electrons from theinsulating material 48 totheconduc- Y tive. material 50. The electrons so liberated are greater in number than the-instant primary electrons.: Y The conductor 50 is maintain'ed at'more positive potential with respect to the potential of the beam generating means through proper connection of switch 52, for example. The resultant more positively charged; character so. illu- Y minated will retain the more positive potential charge in its insulating surface '48 adjacent that character so that subsequent flooding of the beam shaping member. 22,

Y for. the. purpose of displaying the character, will permit the flood beam electrons to pass through the more posi tively charged area adjacent the characterselected, and, the more negative charges adjacent all non-selected charactors carried by their'adjacent insulating surfaces 48 will 1 repell the flood beam fromsuch areas. Y Y Y Y Y Itcan therefore be seenthat the character so selected may be Continuously projected upon the target 18 until the flood beam is tie-energized; The flood beam potential is given an adjustment with respect to the positively charged area adjacent the character selected to prevent the area from collecting a negative charge. When it is desired to erase the displayed character, the potential of the flood beam is returned to the initial pro-selection condition.

The particular embodiment of the invention illustrated and described herein is illustrative only and the invention includes such other modifications and cquivalents as may readily appear to those skilled in the art, within the scope of the appended claims.

I claim:

1. In a shaped beam tube including means to generate and project an electron beam for impingement upon a spaced apart target, and a beam shaping member disposed in the path of the beam to eflect selective crosssectional shaping of the electron beam, the improvement in the beam shaping member comprising a plurality of spaced apart stencil like cutout portions for shaping the beam, means positioned intermediate and adjacent each of the cutout portions for selectively permitting and preventing electron transmission through each of said cutout portions, said last stated means including an electron storage element for storing electrons thereon in response to impingement of the beam thereagainst, and a conductive element selectively operable to discharge said storage element.

2. A shaped beam tube for presenting a one-at-a-time display of a desired character, said display being capable of a selectively prolonged display period, comprising means to generate and project an electron beam, means selectively focusing and defocusing said beam, a target for responding to the beam to provide a visual display, beam shaping means positioned in the path of the beam for shaping the beam cross section into the desired character, said beam shaping means being adapted to present said character in said selectively prolonged display period, said beam shaping means including a base member presenting a plurality of cutout portions, the cutout portions being adapted to shape the beam, insulating elements for responding selectively to the selectively focused and defocused beam, to establish thereupon electron charges, said elements being disposed in mutually insulated relation with respect to each other adjacent each of the cutout portions, and means connected with the insulating elements for selectively conducting charges from said insulating element.

3. The invention in accordance with claim 2, wherein said insulating elements individually surround the respective cutout portions they are placed adjacent to.

4. A shaped beam tube for presenting a one-at-a-tirne display of a desired character, said display being capable of a selectively prolonged display period, comprising means to generate and project an electron beam, means selectively focusing and defocusing said beam, a target for responding to the beam to provide a visual display, beam shaping means positioned in the path of the beam for shaping the beam cross section into the desired character, said beam shaping means being adapted to present said character in said selectively prolonged display period, said beam shaping means including a base member presenting a plurality of cutout portions, the cutout portions being adapted to shape the beam, insulating elements for responding selectively to the selectively focused and defocused beam, to establish thereupon electron charges, said elements being mutually insulated from each other and disposed in encircling relation with and adjacent to each of the cutout portions upon the base member for selectively permitting and preventing electron passage through the cutout portion in response to the charges upon the insulating element, and a conductive layer in electrical connection with and overlaying said insulating elements for selectively conducting charges from said insulating layers.

References Cited in the file of this patent UNITED STATES PATENTS 2,283,383 McNaney May 19, 1942 2,532,339 Schlesinger Dec. 5, 1950 ,687,492 Szegho et al. Aug. 24, 1954 2,769,116 Koda et a1. Oct. 30, 1956 2,824,249 Hansen Feb. 18, 1958

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