US3840773A

US3840773A - Display system with rapid color switching

Info

Publication number: US3840773A
Application number: US00319968A
Authority: US
Inventors: H Hart
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-12-29
Filing date: 1972-12-29
Publication date: 1974-10-08
Anticipated expiration: 1991-10-08
Also published as: CA986168A; JPS4998923A; GB1443031A; SE381372B; DE2363136A1; GB1443032A; BE808269A; FR2212637A1; IT990295B; FR2212637B1; DE2363136C2; CH566073A5

Abstract

An improved color display system employing a beam penetration type cathode-ray tube with rapid color switching. The screen electrode is separated from the accelerating electrodes without the use of an isolating mesh so that the voltage applied to the screen electrode is switched across only a relatively small capacitance. The invention may be used in conjunction with either magnetic or electrostatic deflection beam penetration cathode-ray tubes as well as either magnetic or electrostatic focus tubes. Such display systems may be used for radar type random access or scanned raster type displays.

Description

SWITCHING lhiited States atent 119i [iii 3,840,773 Hart [45] Oct. 8, 1974 [54] DISPLAY SYSTEM WITH RAPID COLOR 3,603,830 9/1971 Ganar@ et ai. 313/92 PF [76] Inventor: Harold M. Hart, 5 Marvin Rd., lfggllldbisbasmn Wellesley Mass 02181 Attorney, Agent, or Firm-Joseph D. Pannone; Milton [22] Filed: Dec. 29, 1972 D. Bartlett; David M. Warren [2l] Appl. No.: 319,968 [57] ABSTRACT An improved color display system employing a beam [gi] JSCCII' 315/29 313/65 T 3%/1l.5259 penetration type cathode-ray tube with rapid color [58] Flitid 28 J29 /17 switching. The screen electrode is separated from the "134001 8g Si) 343 5 accelerating electrodes without the use of an isolating C/D mesh so that the voltage applied to the screen electrode is switched across only a relatively small capaci- 56 R f Ct d tance. The invention may be used in conjunction with 1 e erences l e either magnetic or electrostatic deflection beam pene- UNITED STATES PATENTS tration cathode-ray tubes as well as either magnetic or 2,455,710 12/1948 Szegho 313/92 PF electrostatic focus tubes. Such display systems may be 2.590.018 3/ 1952 Koller etal. 3l3/92 PF used for radar type random access or scanned raster 3,114,907 12/1963 Lufiman e; a1 343/5 CD type displays. 3,270,234 8/l966 Schaffernicht et al. 313/83 SP 3,428,858 2/1969 Giypiis 313/92 PF 22 Claims, 4 Drawing Figures 9 x 56 g) sa ii/ y i@ 75 t 93 98 5/ 74 j i 90 T i 37 56 y2 40 ss 141 Racen/ER WDEO l`l g 4/ AMP 92' /05 /03 /07 f3 72 ,Ye Y ;"M'Mw RAMP I xdlg GEN. 9%-- ad/ 99 'DDJ 6 977 vlii'AGE SUPPLY l /U --Y 42 2O 2/ L COLOR 43 VAFrliIIAGLE HMM CONTROL MME-4M' VOLTAGE CIRCUIT SUPPLY /5 DISPLAY SYSTEM WITH RAPID COLOR SWITCHING BACKGROUND OF THE INVNTION Numerous prior art attempts have been made to construct multiple color cathode-ray tube systems in which the color is varied by changing the screen anode voltage and hence the beam velocity and the penetration depth of the electron beam into a multilayer phosphor screen. The earliest of' these attempts included a cathode-ray tube wherein the screen electrode and conductive coating on the inside of the tube envelope formed a single electrode both connected to the same high voltage source. These early attempts suffered from two major problems. First, the screen electrode and conductive coating connected together formed a large capacitance across which the high voltage had to be switched each time the color was to be changed. This large capacitance created the need for a high powered amplifier which was capable of switching the voltage across such a capacitance in a relatively short period of time, otherwise large delay times had to be tolerated if a more reasonably powered amplifier switch was used to the high voltage. Secondly, whenever the high voltage to the screen and conductive coating was switched, the deflection sensitivity of the tube also changed since the high voltage which was connected to these electrodes was the final accelerating voltage which is determinative of the deflection sensitivity of the tube.

Later attempts divided the screen electrode from the conductive coating on the inside of the tube envelope with a conductive wire mesh inserted between the two electrodes thus formed. Although the capacitance of the screen electrode, with respect to the tube cathode and ground, was reduced somewhat by the separation, the insertion of the mesh raised the capacitance again to a higher capacitance since the mesh and screen electrodes formed a parallel plate capacitor. Furthermore, such a mesh created problems when the electron beam struck the wire of the mesh.

One attempt to circumvent the problem of having to switch a high voltage across a large capacitance included a tube in which the screen electrode and envelope coating electrode were connected together but two or more separate electron guns were used, one for each of the layers of phosphor in the screen. Each of these electron guns was connected to a different voltage so that the voltage between each gun and the screen was different. One problem with such multiple gun beam penetration cathode-ray tubes was arcing between the guns as several kilovolts of voltage difference were typically required between the electron guns to achieve usable penetration depth differences. Furthermore, the potential difference between the electron guns created lensing effect in the gun region which resulted in pattern distortion problems. Also, it was necessary to impress the video signals upon a relatively high voltage compared with their normal voltage levels.

SUMMARY OF THE INVENTION The above stated as well as other objections of the prior art may be overcome by a multicolor cathode-ray tube having means for providing an electron beam, tube envelope, and screen in which is provided the combination of means for creating an electric field in the region adjacent to the screen and means for applying a plurality of voltages to the electric field creating means. The electric field creating means is located outside of the region traversed by the beam. The electric field creating means may be a plurality of electrodes or a spiral electrode located adjacent to the surface of the envelope of the cathode-ray tube.

Objections of the prior art may also be overcome by providing the combination f means for focussing the beam of a cathode-ray tube, means for positioning the beam of the cathode-ray tube in proportion to one or more independent signals and one or more electrodes for changing the color of the light emitted from the cathode-ray tube without affecting the focus of the beam wherein the electrodes are located outside the region traversed by the beam. The positioning means may comprise one or more deflection amplifiers, each having at least one input and one output, the inputs of which are coupled to the aforementioned input signals. These input signals may be generated from a computer such as a central computer used in a radar display system where the radar data is first digitized for processing and then displayed at appropriate places upon the screen of the display. The positioning means further may include means for generating defiecting fields in response to the outputs of the amplifiers. The deflecting field generating means may comprise either deflection coils, such as a magnetic deflection yoke, or electrostatic deflection plates located within the cathoderay tube. The electrodes mentioned above provide an electrostatic field such as an electrostatic field produced by placing a screen electrode at one voltage and one or more accelerating electrodes at other voltages. Such a combination may be used in a display system, such as a radar display system, which may be a random access display system or in a scanned raster television type display system.

Furthermore, the objections of the prior art may be overcome by the combination of a beam penetration cathode-ray tube, one or more electrodes for changing the velocity of the beam of the tube located the region traversed by the beam, means for focussing the beam which operates independently from and is not affected by the electrodes, and means for positioning the beam in proportion to one or more input signals. In this case, the focussing means may include means for providing an electrostatic focussing lens, such as one normally used in an electron gun of a cathode-ray tube, and a magnetic focussing coil. i

Still further, the objections of the prior art may be overcome by the combination of means for providing a focussed beam of electrons, a luminescent phosphor screen which, upon excitation, emits a plurality of light colors, first and second voltage sources, a screen electrode adjacent to the screen connected to the first voltage source, one or more accelerating electrodes connected to the second voltage source located between the beam providing means and the screen electrode and outside the path of the beam, means for varying the voltage of the first voltage source, and means for deflecting the beam to positions on the screen determined by one or more input signals. In this case, the beam providing means includes an electron gun. The phosphor screen comprises a plurality of layers of phosphor particles. These plurality of layers may be either a plurality of separated layers, each layer of which is composed of a single phosphor type or a layer of phosphor particles,

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects and other features of the invention are explained in the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a cross-sectional view of first type of cathode-ray tube used in a radar data display system in accordance with the present invention;

FIG. 2 is a cross-sectional view of the screen of one type of a cathode-ray tube;

FIG. 3 is a cross-sectional view of the screen of a second type of cathode-ray tube; and

FIG. 4 is a cross-sectional view of an alternate type of cathode-ray tube used in a scanned raster display system in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a cathode-ray tube, shown generally at 47, is used in a display system in accordance with the present invention. In this tube 47, the electron gun 61 is a standard electron gun as is used in a monochrome cathode-ray tube. The electron gun 61 produces a single electron beam rather than a plurality of electron beams as used in some multiple color cathode-ray tubes. In this electron gun, the cathode 33, heated by filament 64, emits electrons which are focussed into a beam by focussing electrodes 36 and accelerated towards the screen by the first accelerating electrode 35. The first accelerating electrode 35 is coupled to fixed high voltage supply through conductive coating 38.` The magnetic deflection yoke 18 deflects the beam to the desired position on the screen 62 as in most cathode-ray tube systems. In the particular embodiment of the invention shown in FIG. 1, the conductive coating 38 on the inside of the glass tube envelope 37 extends from the electron gun region towards the front of the tube and completely covers the inside of the tube envelope 37 in the region between the electron gun 61 and gap 46 thereby forming a second accelerating electrode at the same voltage as the first accelerating electrode 35 as the two are electrically connected. A nonconductive gap 46, for example, lVz inches in width, separates the conductive coating 38 from a second region of conductive coating 39 connected to the aluminization layer 40 forms the screen electrode. The second conductive coating region 39 extends from the aluminization layer 40 to one side of the gap 46, for example, 3.5 inches from the edge of the aluminization layer 40. The width of gap 46 is chosen along with the width of the second conductive coating 39 to have dimensions which will minimize the electrostatic field concentrations and hence lensing effects within the region near the screen 4l of the tube as the proper gap width of gap 46 will greatly reduce the strength of the electrostatic lens formed by the voltage difference between the first conductive coating 38 and second conductive coating 39. Furthermore, locating the gap at some distance from the screen tends to linearize non-linear peripheral fringing effects that would be created if the gap were located nearer the screen thereby reducing potential positional distortion near the edges of the screen 41.

In other embodiments of the invention there are a plurality of gaps such as gap 46 to further reduce the strength of the electrostatic lenses and hence further reduce positional distortion caused by such electrostatic lenses. In some 0f these embodiments, with multiple gaps and hence multiple accelerating electrodes, the electrodes may each be set at a different voltage. In still further embodiments of the present invention, the conductive coating on the inside of the tube envelope may be fashioned in the form of a spiral or helix with the end nearest the electron gun at one voltage and the end nearest the screen electrode at a second voltage. In such cases, the screen electrode may be connected to one end of the helix or it may be connected to a separate high voltage supply. Such a system will be discussed later in conjunction with FIG. 4.

In any of the embodiments of the present invention, there need be no conductive mesh between the screen electrode and the electrode or electrodes formed on the inner surface of the tube envelope. Thus, only a comparatively small capacitance need be switched, i.e., the capacitance formed by the screen electrode 40 and the reference ground of the screen electrodes high voltage power supply which is most commonly the system ground. In most applications, this capacitance tends to be minimal in that the screen must be exposed for viewing and hence is not usually near or parallel to any large metallic or conductive surfaces with which relatively large capacitances may be formed. In contrast, the capacitances formed from the electrodes on the conductive surface of the tube envelope which, in many applications are either surrounded by a grounded metallic shield or are near a grounded conductive chassis or other such components within the console in which it is customarily mounted, are much higher. Hence, if an attempt were made to switch these electrodes, the capacitance across which the high voltage must be switched is correspondingly higher. With the capacitance reduced across which the high voltage which must be switched in order to change colors the switching time between colors is reduced making the cathode-ray tube useful in many applications in which it formerly could not be used because of the long switching times or high amplifier power required.

Again referring to the embodiment shown in FIG. 1, a fixed high voltage supply 20 is connected through a metallic connector 48 through the glass tube envelope 37 to the conductive coating 38. Similarly, a variable high voltage supply 21, used to change the potential of the electrode 40 and hence the displayed color, is connected through metallic connector 49 through the glass envelope 37 to the conductive coating 39. The conductive coating 39 is connected to the aluminization layer 40 so that the aluminization layer 40 is at the same potential as the conductive coating 39. A multilayer phosphor coating 41 is placed between the aluminization layer 40 and the front of the screen. The electron beam 46 easily penetrates the thin aluminization layer 40 and strikes the phosphor layer 4l with a velocity determined by the voltage of variable high voltage supply 2l. Light, which is emitted from the phosphor layer 41 when excited by the electron beam 56, is reflected from the aluminization layer 40 towards the front of the screen thereby increasing the available light output of the tube.

Referring now to FIG. 2, there is shown a crosssectional view of the screen 62 of the cathode-ray tube of F IG. 1. The phosphor layer 41 consists of multilayered phosphor particles in which the different layers are each a different `type of phosphor. For example, the inner layer 51 of one such particle is surrounded by an outer layer 50 of another type phosphor with an inert layer 51A separating the two. The inert layer 51A absorbs electron energy without absorbing light thereby increasing the voltage difference necessary to change colors. Improved color resolution is thereby attained since the electron beam contains typically a range of electron velocity rather than a single velocity. The inner layer 51 may, for example, be a green light emitting phosphor while the outer layer 50 is a red light emitting phosphor. When the electron beam 56 penetrates through the aluminization layer 40 and strikes the phosphor layer 41 with a comparatively low velocity, the beam will only penetrate the first layer 50 of the phosphor and will not reach the inner layer 51 as the energy of the electrons is substantially completely absorbed in penetrating and exciting the first layer 50. As the electron beam velocity is increased and the electrons acquire higher momentum, the beam will penetrate deeper insider the phosphor particles and eventually penetrate through inert layer 51A into the inner layer 5I. If the inner phosphor layer 51 has a higher light emitting efficiency than the outer layer S0, the light emitted from the inner layer 51 will be the predominant light output from the phosphor layer 4l at the comparatively higher beam velocities.

Referring now to FIG. 3, there is shown an alternative method of constructing a multiple layer beam penetration type screen. Here, the phosphor layer 41 contains phosphor particles, each with light emitting

layers

52 and 53, each of a different type of phosphor, separated by inert layer 53A. For example, the first layer 52 may be a phosphor which emits predominantly red light while the layer 53 is composed of phosphor particles 55 which emit predominantly green light. At comparatively low beam velocities, the beam will penetrate only into the first layer 52 and not through the second layer 53. The layer 53, when its phosphor particles are not excited, and inert layer 53A are relatively transparent to the light emitted from the first layer 52. As the beam velocity increases, electrons will penetrate through layer 52 and into the layer 53. If the phosphor particles 55 of layer 53 are of-a higher efficiency phosphor than i the particles 54 of layer 52, the total light emitted from the tube will be predominantly the color emitted from the second layer 53 at the higher electron beam velocity. Inert layer 53A serves the same purpose as layer 51A in FIG. 2.

In either embodiment shown in FIG. 2 or FIG. 3 more than two layers of phosphor may be used. For example, a third level of phosphor could be added between layers 5l and 50 in FIG. 2 or a third layer of phosphor particles inserted either between or on one side of phosphor layers 52 and 53 in FIG. 3 along with appropriate inert layers. Furthermore, one layer such as the layer 41 in FIG. 2 could be used in place of one of the

layers

52 or 53 in FIG. 3 thereby `forming a three-color tube. If the layer 41 in FIG. 2 were substituted for layer 53 in FIG. 3, at low electron beam velocity only the particles 54 in layer 52 would be excited. As the beam velocity increased to intermediate values, the outer layer would be excited and at the higher electron beam velocities the inner layer of phosphor 51 would finally be excited.

Referring again to FIG. 1, the cathode-ray tube 47 will be described in its use in a random access radar display system in accordance with the present invention. Radar target returns received by radar antenna and amplified and demodulated by radar transmitter/- receiver 81 are converted to digital form by digitizer 82. The digitized radar signals are coupled to central computer 83 where they are converted along with data on lines 85 from peripheral units by pre-programmed instructions to the proper format for visual presentation. The data on lines 85 may include operator instructions such as desired radar range as well as ancillary data such as weather maps or target identification symbols. The central computer 83 may be capable of supplying data to several display units 16 such as shown within the dotted lines of FIG. 1. Data is coupled from the central computer 83 to the display controller 10 of the display unit 16 on lines 57. The display controller includes a refresh memory for maintaining the visual presentation of data in a flicker-free condition. Use of a refresh memory within display controller 10 frees the central computer 83 from having to perform the refresh function. The display controller 10 also provides data coupling and control signals to vector generator 11, character generator l2 and color control circuit I5. In order to cause the system to write aline, such as part of a weather map or radar target, the display controller l0 on lines 58 sends to the vector generator ll the start and end point coordinates of the line which is to be written. The vector generator 11 converts this beginning and end point information to time varying X and Y position signals representing points on the line to be traced out. These position signals are connected out of the vector generator on

lines

25 and 26 respectively. The output on line 27 includes information as to when the cathode-ray tube beam 56 is to be blanked and unblanked and at what level of brightness the line is to be written.

The display controller 10 generates signals on lines 60 to the color control circuit 15 which determine which color should be used in writing the displayed lines or characters. The color control circuit 15 on line 43 signals the variable high voltage supply 21 indicating the proper voltage to apply to the screen electrode for the desired beam penetration and hence the proper color. Also, the color control circuit 15 indicates the proper amplifier gain on line 42 for the X axis amplifier 17 and the Y axis amplifier 19 for the deflection sensitivity determined by the high voltage settings. It should be noted, however, that the deflection sensitivity changes with a tube such as illustrated in FIG. l is significantly less than the deflection sensitivity changes if the screen electrode and conductive coating were at the same voltage and were changed at the same time to change the color. The color control circuit 15 indicates the selected color on line 63 to video amplifier 14 for brightness adjustments among the various colors.

Similarly, on lines 59 the display controller 10 transfers data to the character generator 12 concerning the characters to be written. The position on the face of the cathode-ray tube may either be set through the character generator 12 or through the vector generator 11. The character generator 12 receives character code inputs on lines 59 from computer controller 10 and l2 converts the codes to time varying X and Y deflection signals on

lines

28 and 29 respectively, thereby causing the beam to trace out the desired character pattern. The character generator also produces a video signal on line 30 which causes the video amplifier 14 to blank and unblank the beam 56 and to select the appropriate brightness by varying the applied voltage on line 34 and hence the beam current flowing from the cathode 33 of the electron gun 61.

Switches

22, 23 and 24 select either the vector generator 11 or character generator 12 as inputs to the X and Y axis amplifiers on

lines

65 and 66 through pattern correction circuit 13 and on line 67 to video amplifier 14. The switch position is chosen through the computer controller through lines not shown in the drawing.

Switches

22, 23, and 24 are preferably high speed electronic switches.

The pattern correction circuit 13 receives X and Y inputs on

lines

65 and 66 respectively and applies a correction factor to these signals prior to final amplification to correct for the fact that the surface of the screen of the cathode-ray tube 47 is more nearly flat than spherical. If this correction were not made, the pattern on the face of the cathode-ray tube would be severely distorted. For example, if a square box were to be drawn, the sides of -the box would appear curved inwards.

The electron beam 56 is focussed by the voltage applied to focussing electrodes 36 by focus control 44 on line 45. Since the electrostatic lens formed between

conductive coatings

38 and 39 is extremely weak in the area near the electron gun 61, the beam focus is unaffected by changes in color. Hence, the focus control'44 need not be coupled to color control circuit 15.

The X axis amplifier 17 and Y axis amplifier 19 receive their corrected inputs on lines 31 and 32 respectively. These amplifiers provide the correct signal levels for beam deflection to the deflection yoke 18 which contains both X and Y deflection coils. As mentioned previously, the gain of the X axis amplifier 17 and Y axis amplifier I9 are properly set for the chosen color by the color control circuit on line 42.

FIG. 4 shows an alternative method of constructing a display system in accordance with the present invention. In the system of FIG. 4, the cathode-ray tube shown generally at 105 has two main areas of difference from the cathode-ray tube in FIG. l. First, the two regions of

conductive coating

38 and 39 in FIG. 1 are here replaced by a front section of conductive coating 75 connected to a helical strip of conductive coating 74 on the inside of the tube envelope 109. A variable high voltage power supply 21, as in FIG. 1, is connected to the front section of conductive coating 75 and the fixed high voltage power supply 20 is connected to the end of the helical strip of conductive coating 74 nearest the electron gun shown generally at 61. The second main difference with the cathode-ray tube 105 is that deflection of the electron beam 56 is accomplished by elec

trostatic deflection plates

72 and 73 rather than with a magnetic deflection yoke as used in the system of FIG. l. The electron gun 61 and the screen 62 are the same as shown in FIG. 1. It is to be understood, of course, that the helical strip may be used with magnetic deflection as can the two separate regions of conductive coating be used with electrostatic deflection.

The cathode-ray tube 105 is shown used in a swept raster display system. Remotely transmitted signals are intercepted by antenna 93 and coupled to receiver 92.

In some embodiments, signals may be coupled from a radar receiver and processor or other signal source through a cable thus eliminating the need for a receiver. The receiver 92 generates combined X and Y axis sync signals on line 102, demodulated video information on line 106, and color information on line 108. The video amplifier 89 amplifies the video signal to the proper voltage level and couples it to the cathode of the cathode-ray tube 105 on line 107. The sync circuit 91 separates the combined sync signal on line 102 and generates separate X and Y axis sync signals on

lines

101 and 100 respectively.

When the raster is being generated in the usual fashion with the scanned lines parallel to the X axis, there is one sync pulse for the Y axis for a number of sync pulses for the X axis equal in number to the number of scanned lines in the presentation. The Y sync pulse starts the generation of the Y axis ramp in Y ramp generator 88 on line 99 while the X sync pulse starts the generation of the X axis ramp in X ramp generator on line 98.

Lines

103 and 104 coupling the output ramp signals between the two ramp generators are necessary for corrections to the ramp waveforms dictated by the fact mentioned previously that in the preferred embodiment the face of the cathode-ray tube is more nearly flat than round. The outputs of the X axis amplifier 87 on

lines

94 and 95, which are preferably equal in magnitude but opposite in polarity, are coupled to the X deflection plates 73 while the outputs of the Y axis amplifier 86, similarly equal in magnitude but opposite in polarity, are coupled to the Y deflection plates 72.

The color control circuit l5 receives information pertaining to the color to be displayed on line 108 from receiver 92. Its operation is the same as that for the color control circuit of FIG. 1.

Although a preferred embodiment of the invention has been described, numerous modifications and alterations would be apparent to one skilled in the art without departing from the spirit and scope of the present invention. For example, the circuit of FIG. 4 may be used with the cathode-ray tube Aof FIG. 1 and vice versa. Numerous arrangements of layered phosphors may also be used. A radial scanning mode as used in a plan position indicator color display presentation is also well within the scope ofthe invention. Furthermore, many different arrangements may be used for the electrodes formed from the conductive coating on the inside of the tube envelope. Materials other than glass may be used for this envelope. Although electrostatic focussing means has been described in conjunction with the preferred embodiments, magnetic focussing employing a standard focussing coil may be used as well.

What is claimed is:

1. In combination:

means for providing a beam of electrons;

a beam penetration luminescent phosphor screen, the color of light emitted from said screen being dependent upon the velocity of the electrons in said beam;

means for providing first and second voltage sources;

a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating `said beam of electrons to a final impingement velocity;

an accelerating electrode, said accelerating electrode 'being located between said beam providing means and'said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source;

means for varying the voltage of said first voltage source, the voltage of said second voltage source being fixed at a predetermined value; and

means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes.

2. The combination according to claim l wherein said beam providing means comprises an electron gun.

3. The combination according to claim l wherein said phosphor screen comprises a plurality of layers of phosphor particles.

4. The combination according to claim 1 wherein said phosphor screen comprises a layer of phosphor particles, each of said particles comprising a plurality of concentric layers of phosphors each of said layers emitting a different color light upon excitation.

5. The combination according to claim 3 wherein said screen electrode further comprises a layer of` metal. y

6. The combination according to claim 5 wherein said metal is aluminum.

7. The combination according to claim l wherein said deflecting means comprises means for generating deflecting fields in response to the outputs of deflection amplifiers.

8. The combination according to claim 7 wherein said deflecting field generating means comprises deflection coils.

9. The combination according to claim 7 wherein said deflecting field generating means comprises electrostatic deflection plates.

10. The combination according to claim 1 further comprising utilization means in a display system.

l1.. The combination according to claim 10 wherein said display system comprises a randomaccess display system.

l2. The combination according to claim 10 wherein said display system comprises a scanned raster display system.

13. The combination according to claim 7 further comprising deflection amplifier means coupled to said means for generating deflecting fields.

14. A display system comprising in combination:

means for providing a beam of electrons;

a beam penetration luminescent phosphor screen,

the color of light emitted from said screen being dependent upon the velocity of the electrons in` said beam; means for providing first and second voltage sources;

a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of electrons to a final impingement velocity;

an accelerating electrode, said accelerating electrode being located between said beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source;

means for varying the voltage of said first voltage source;

means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes; and

signal receiving means, the voltage of said first voltage source varying in response to signals received by receiving means.

15. The combination of claim 14 wherein said signal receiving means comprises radar signal receiving means.

16. The combination of claim 15 further comprising computer means coupled to one or more outputs of said radar signal receiving means.

17. The combination of claim 16 further comprising means for producing signals corresponding to target positions on said screen in response to outputs from said computer means.

18. The combination of claim 17 wherein said means for varying the voltage of said first voltage source operates in response to outputs from said computer means, the color of data being displayed being varied in response to said outputs.

19. A random access display system comprising in combination:

means for providing a beam of electrons;

means for providing first and second voltage sources;

an accelerating electrode, said accelerating electrode being located between said' beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source;

' a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of` electrons to a final impingement velocity;

means for varying the voltage of said first voltage source;

means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes;

deflection amplifier means coupled to each of said deflecting means;

vector generator means coupled to said deflection amplifier means; and

character generator means coupled to said deflection generator means.

20. The combination of claim 19 further comprising computer means coupled to said vector generator means, said character generator means, and said means for varying the voltage of said first voltage source, at least some vectors and at least some characters being displayed on said screen being displayed in different colors.

21. A raster scanned display system comprising in combination:

means for providing a beam of electrons;

means for providing first and second voltage sources;

means for varying the voltage of said first voltage source;

deflection amplifier means coupled to each of said deflecting means; and

means for producing signals for generating a raster scan pattern on said screen, said signal producing means being coupled to said deflection amplifier means.

22. The combination of claim 2l wherein at least some lines of said raster scan pattern are displayed in different colors.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIUN Patent NO- 3,84 0,773 Dated OCT.. 8, 1974 Invented@ Harold M. Hart It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, the name of the Assignee, Raytheon Company, is not shown.

In the Claims Claim 19, column 10, lines 38-42, should follow lines 43-47 (Paragraphs are reversed) gned and Sealed this twenty-frst D ay Of October 1975 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Attesting Officer C ommissimzer of Patents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,840,773 Dated Oct. 8, 1974 Inventor(s) Harold M. Hart It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, the name of the Assignee, Raytheon Company, is not shown.

In the Claims Claim 19, column l0, lines 38-42, should follow lines 43-47 (Paragraphs are reversed) Signed and Sealed this twenty-frst D ay Of October 19 75 [SEAL] AES.'

RUTH C. MASON C. MARSHALL DANN Attesing Offcer Commissioner of Patents and Trademarks

Claims

1. In combination: means for providing a beam of electrons; a beam penetration luminescent phosphor screen, the color of light emitted from said screen being dependent upon the velocity of the electrons in said beam; means for providing first and second voltage sources; a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of electrons to a final impingement velocity; an accelerating electrode, said accelerating electrode being located between said beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source; means for varying the voltage of said first voltage source, the voltage of said second voltage source being fixed at a predetermined value; and means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes.

2. The combination according to claim 1 wherein said beam providing means comprises an electron gun.

3. The combination according to claim 1 wherein said phosphor screen comprises a plurality of layers of phosphor particles.

5. The combination according to claim 3 wherein said screen electrode further comprises a layer of metal.

6. The combination according to claim 5 wherein said metal is aluminum.

7. The combination according to claim 1 wherein said deflecting means comprises means for generating deflecting fields in response to the outputs of deflection amplifiers.

11. The combination according to claim 10 wherein said display system comprises a random access display system.

12. The combination according to claim 10 wherein said display system comprises a scanned raster display system.

14. A display system comprising in combination: means for providing a beam of electrons; a beam penetration luminescent phosphor screen, the color of light emitted from said screen being dependent upon the velocity of the electrons in said beam; means for providing first and second voltage sources; a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of electrons to a final impingement velocity; an accelerating electrode, said accelerating electrode being located between said beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source; means for varying the voltage of said first voltage source; means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes; and signal receiving means, the voltage of said first voltage source varying in response to signals received by receiving means.

19. A random access display system comprising in combination: means for providing a beam of electrons; a beam penetration luminescent phosphor screen, the color of light emitted from said screen being dependent upon the velocity of the electrons in said beam; means for providing first and second voltage sources; an accelerating electrode, said accelerating electrode being located between said beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source; a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of electrons to a final impingement velocity; means for varying the voltage of said first voltage source; means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes; deflection amplifier means coupled to each of said deflecting means; vector generator means coupled to said deflection amplifier means; and character generator means coupled to said deflection generator means.

21. A raster scanned display system comprising in combination: means for providing a beam of electrons; a beam penetration luminescent phosphor screen, the color of light emitted from said screen being dependent upon the velocity of the electrons in said beam; means for providing first and second voltage sources; a screen electrode adjacent to said screen, said screen electrode being connected to said first voltage source and said screen electrode accelerating said beam of electrons to a final impingement velocity; an accelerating electrode, said accelerating electrode being located between said beam providing means and said screen electrode and outside the path of said electron beam, and said accelerating electrode being connected to said second voltage source; means for varying the voltage of said first voltage source; means for deflecting said beam to positions on said screen determined by one or more input signals, said deflecting means being disposed between said beam providing means and said accelerating electrodes; deflection amplifier means coupled to each of said deflecting means; and means for producing signals for generating a raster scan pattern on said screen, said signal producing means being coupled to said deflection amplifier means.

22. The combination of claim 21 wherein at least some lines of said raster scan pattern are displayed in different colors.