US2543477A - Kinescope for the reproduction of color images - Google Patents

Description

Feb. 27, 1951 G. c. szlKLAl ETAL 2,543,477

KINEsCoPE EoR THE REPRODUCTION oF coLoR IMAGES Filed July 29, 1948 2 Sheets-Sheet l @Pfff/FILTER 3 Ell/EF/LTE? Fo fF/LTE? o Z 9 @E E@ Rg! v I F g *w y su gy o 55 l V E R Feb. 27, 1951 G. c. szlKLAl x-:T AL 2,543,477

KEESOOPE FOR THE REPRODUCTION OF COLOR IMAGES Filed July 29, 1948 2 sheets-sheet 2 E @mmm Gttorneg @Patented Feb., 27, A1795.1

UNIE!) STATES TENT OFFICE KENESCPE FOR THE REPRODUCTION OF CLR .MAGES Ware Application July 29, 1948, Serial No. 41,294

(Cl. Z50-164) 12 Claims. i

This invention relates. to the reproduction of necessarily exclusively, to a color television system or the like in which limages in substantially their natural color are produced by electronic means.

in accordance with this invention, colored light is obtained by altering the effective velocity of the scanning cathode ray beam of a cathode ray image producing tubeV in the region or the target area'by physically retarding the velocity of the electrons by predetermined amounts by means of mechanical barriers or the like.

The theory of'operation of this invention can perhaps best be understood after a brief review of the electron penetration phenomenon.

An excellent treatise on the subject is H. Bethes The Theory of Transmission-of Fast Corpuscular RaY s Through Materials which may be found in the Annalen der Physik, vol 5,V

193%, beginning on page 325.

In this paper, considering electrons as the particles, the ray equation may be simpliedto a form:

no4-r4.1., BX :K` (a constant) where on is the initial velocity of the electron,

c is the velocity after the electron traveled distance in the material,

e is the charge of the electron 4.'l7 10-10 ESU,

m is the mass of the electron 9.04 -28 gram,

N is the number of atoms per unit volume of the material, and

B is the retardation factor of the material.

112:? (1)02 i 2MB-@UTK iva; K)

which is a function containing a maxima.

Thus considering a layer of phosphor with a barrier of agiven- K value bombarded'` With a beam of increasing velocity, at rst the radiation will be Zero since the beam does not penetrate thephosphor, then at a value `K=o04 most of ther energy will be absorbed by the phosphor, beyond which the loss of velocity becomes smaller and the energy lost Will shift beyond the phosphor.

I-t will be seen from the above discussion that contrary'to the obvious. concept, the light radiationy does not necessarily increase With the velocityiof the impinging electrons but reaches a maximumand then is reduced.

It will be seen, therefore, that differently colored lights may be producedin a stacked or composite screen. arrangement wherein the velocity ofthe `electronstraveling through the screen is` controlledrin such a manner that its mest eiiicient light producing velocity will be at the location of the selectedcolor light producing phosphor or at the phosphor with the properly chosen -associated light ilten This particular principle has, of course, been recognized heretofore for the production of colored light by electron bombardment. An electron sensitive photograph plate may be found Well shown and described, for example, in the U. S. patent to E. G. Ramberg, No. 2,442,961, datedJune 8, 1948, wherein electrons at controlled velocities are-made to impinge upon a layered screen. The velocities are so chosen that the maximum eiciencyfof each of two velocities produces a maximum of radiation in one of two selected component color light producing mediums.

This fundamental principle of colored light production is also'recognized as being applicable to television image reproduction.' An arrangement of this sort may be found in the copending U. S. application of Vladimir K. Zworykin entitled Kinescope for Color Television, Serial No. 739,563, led April 4, 1947;

Inl the copending application of Zworykin referred to immediately above, the velocityof the electrons impinging on a multiple layer f'screen is controlled in accordance with component color information Which'is transmitted together with video information.

According to this invention, a novel arrange ment is provided for color selection. In the practice of this invention; a cathode ray tube is employed including an electron gun for forming an electron beam. Av beam electron velocity ccntrol electrode is arrangedto receive image color informationV and av target area consisting of a plurality of color producing light areas is spreadv over the target area. A material having different predetermined physical properties is employed to retard the electron beam to predetermined diierent amounts. This material covers the target area. The amounts of electron retardation correspond to selective color representation associated with similarly representative light producing areas. The color of the iight produced may then be controlled by the signal applied to the beam electron velocity control electrode. Images may then be formed in the usual manner of scanning familiar in the television art.

A primary object of this invention is to provide for the production of colored light and colored images without resorting to mechanical rotating devices.

Another object of this invention is to provide for improved color television image reproduction.

Another object of this invention is to provide a novel electron beam target for an image producing tube.

Other and incidental objects of the invention will be apparent to those skilled in the art from a reading of the following specification and an inspection of the accompanying drawing in which:

Figure l illustrates schematically one form of this invention;

Figure 2 illustrates graphically the operation of this invention;

Figure 3 illustrates schematically another form of this invention;

Figure 4 illustrates schematically still another form of this invention; and

Figure 5 shows by block diagram this invention as applied to television image reproduction.

Turning now in more detail to Figure l, there is illustrated schematically a source of electrons I which are directed toward an electron target 3 which includes a white light producing phosphor 5 and a series of elemental color filters l, whose color is indicated by appropriate crosshatch.

Between the source of electrons I and the phosphor or other luminescent material 5, there is positioned a mechanical barrier 9 whose thick'- ness, it will be s;en, is dependent upon which of the several component color filters with which it is associated. For example, for each of the green lter elements the mechanical barrier is of the minimum specic amount. However, for each of the blue lter elements the thickness of the mechanical barrier is of the speciiic amount, while for each of the red lter elements the thickness of the mechanical barrier is still a third predetermined amount. Although a barrier having diierent thicknesses is shown, according to another form of this invention a barrier having uniform thickness but other different phyical characteristics is employed.

Before an attempt is made to explain the operation of the invention shown in Figure 1, a brief reference to the graphs of Figure 2 will be made.

In Figure 2, the light producing eiect of electrons impinging upon a luminescent material will be seen not to be directly in proportion to their velocity, but will produce a maximum of luminescence at one particular velocity and drop in light producing eiect if the velocity of the electrons is increased above that predetermined amount. In the graph shown in Figure 2, the ordinate R is indicative of light production, while the abscissa V is indicative of the velocity of the electrons.

' ing through the thinnest barrier layer.

From the above explanation and illustration it will be understood that if the velocity of the electrons from their source is controlled in accordance with several selected component color representations, the mechanical barricr will cause to be produced a luminescence only behind that barrier which retards the velocity of the electrons to the amount which produces a maximum luminescence in the luminescent portion of the screen. It will be seen, therefore, that color sel-ction may be obtained by utilizing appropriate color phosphors or appropriate color nlters adjacent to each different thickness o bar-- rier.

Figure 2 is a graphic representation of the third equation given above.

Turning now t0 Figure 3, there is illustrated another form of this invention wherein the mechanical barrier tak-s a different form. In the form of the invention shown in Figure 3, the luminescent material I I is surrounded by a transparent electron barrier I3. The combination of the luminescent material and the barrier will form a sphere. It will be seen that by controlling the size of the sphere, the m-chanical retardation can be controlled. It is therefore possible, by coating the sphere with appropriate color lter material, to obtain the ei'ect shown in the form of the invention illustrated in Figure l. Thus, as illustrated, by employing several diierrnt size spheres any selected component color may be produced.

A transparent support member I5 such as glass or mica is provided.

Although specic values for electron velocity are illustrated, they are by way of example only- More detail regarding control of velocity is given in connection with Figure 5.

Turning now to Figure 4, there is shown still another form of this invention wherein the electron retarding elements also perform the function of color ltering.

It will be seen that each of the green transparent barriers, although irregular in size and irregular in position, are all of a predetermined thickness while the bluel transparent barri.rs are of anoher predetermined thickness. Likewise, the red transparent barriers are of still another thickness. It will thus been seen that if the observation is made from the direction of source l o1 electrons, the color of the light will depend upon the color of the lter at which point the electrons intercept the barriers.

The size of the barriers shown in the drawings is greatly exaggerated. The random distribution, if desired, may be accomplished by etching, plating, spraying, sputtering, etc.

One suitable method for constructing a target of this nature is outlined below.

Once the composite surface of phosphor, barrier and support is made, a layer of photosensitive gelatin is placed on the empty side of the support and the surface is exposed to electron bombardment of a velocity capable of penetrat- The parts of the screen undsr the thin portion will flow and expose the photosensitive layer. After proper processing, the exposed portions ol the gelatin will be green (or any other primary additive color). Next a higher velocity beam is scanned over the barrier, releasing its energy in the phosphor behind the medium thickness barrier and exposing a second layer of photosensitive gelatin which may then be processed to appear blue. Then in a similar manner with an even higher velocity electron beam, a third gelatin layer is exposed and processed into a random color nlter of the third additive primary color. A color lter is thus made, corresponding to the various areas of the phosphor that glow under selective excitation by different velocity electron beams. If the complete surface is now scanned successively with three different velocity electron beams, the screen will appeal` successively in the three primary colors.

In Figure there is shown a television receiving apparatus having an image producing device in the form of a cathode ray tube il provided with the novel target arrangement of this invention, indicated generally by reference character 3, for producing images in color in accordance with the invention. The tube il is equipped with a cathode ray gun structure l for developing a beam of electrons shown conventionally and indicated by reference character I9. The gun I is provided with a control electrode or a grid 2l for modulating the beam I9 which is focused Within the depth or thickness of the target device l. A hcrizonal (line) and Vertical (iield) deflecting coil yoke assembly is indicated generally by reference character 29, and the horizontal and vertical deilecting coil assemblies therein are connected to horizontal and vertical deflection generators 25 and 2 respectively to produce scanning action of the beam l 9 in a manner which is by now well known. This scanning action is to be maintained substantially constant in area. A television receiver arranged generally in this manner is shown in U. S. reissue patent to Carlson, No. Re. 20,790, granted April i9, 1938. The deflection and control circuits shown and described therein and in a U. S. patent to Toison et al., No. 2,191,520, granted December 17, 1937, or in the U. S. patent to Vance, No. 2,137,039, granted November 15, 1938 may be employed in connection with the tube Il' of this invention. Synchronization may be maintained in accordance with the arrangement disclosed and claimed in the copending U. S. application of Wright et al. entitled Beam Deflection Control For Cathode Ray Devicesj Serial No. 699,536, filed September 26, 1946, now Patent Number 2,460,112, issued on January 25, 1949. The various electrodes of the electron gun 2l (not all shown) of the tube IT are to be supplied as usual with suitable operating potentials.

A radio receiver 29 suitable for the reception of television signals from a more or less distant transmitter and equipped with the usual selective circuits, ampliers and a demodulating device is connected, as shown, so that its output is furnished to a video signal separator and amplifier 3|. The demodulated signal from the radio receiver 29 will provide sets of video signals sequentially representing the scanning of an original in several primary colors. In the illustrative arrangement, scanning of the original in any three selected primary or component colors, such as the additive red, blue and green, is assumed for purposes of illustration. Any three colors may be selected so long as they are widely separated spectrally in the I. C. I. color triangle and no two of them can be added together to produce the third, but all add together to produce Whitey Transmitters for scanning images and objects in this manner are known and may comprise separate scanning devices, one for each color,v

6 O. H. Schade, December 24, 1946, or U. S. Patent 2,297,524 to E. I. Anderson, granted September 29, 1942.

The demodulated'signal from the radio receiver 29 is applied to a sync separator 33 which` separates the horizontal (line) and the vertical (field) sync pulses normally present in the demodulated television signal so that these may be applied to the horizontal and vertical synchronizing controls 25 and 2? respectively. This general arrangement for synchronizing a receiver is commonly used in the art and, for instance, is shown in detail in the Carlson reissue patent referred to above and has been described herein merely for the sake of completeness of the disclosure.

The cathode ray tube Il includes an electrode 35 which may be in the form of a line Wire grid and is preferably placed outside of the focus of the beam I9. This electrode 35 may be of the type shown in U. S. patent to Beers, No. 2,385,563, granted September 25, 1945, for example. effect of the grid 35 on the beam at its focal point may be substantially eliminated as described in the Beers patent. It should be understood, however, that the electrode 35 may be in the form of a metallic film or the like which is not impervious to the electron stream of the beam. In the present invention this grid 35 is in communication with a source of relatively high positive potential, such as an appropriate terminal on the power supply unit 3l for the cathode ray tube ll. A connection to the power supply unit is shown diagrammatically and is indicated at 39.

In accordance with the invention, the velocity of the beam I9 in the region of the target 3 is to be altered by an electrode 4l. In order to maintain the image size constant the beam stiness and hence the deilection sensitivity is maintained constant by the grid 35 just described. This grid maintains a constant stiffness or" the beam irrespective of voltage changes on the electrode di.

Having thus described the invention, what Ais claimed is:

1. An image reproducing system comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to receive image color information, a target area consisting of a plurality of different selected component color light producing areas spread. over said target area in mosaic, a material having dir"- ferent predetermined physical properties to retard the velocity of said beam by predetermined different amounts said material positioned between said target area and said electron gun, said predetermined amounts corresponding to selected component color representations, and wherein all material having like physical properties is posi-- tioned adjacent areas producing one only of said different selected component color lights and in the path of said electron beam.

2. A color television system employing image color information signals comprising in combination a cathode ray tube including an electron gun structure for forming an electron beam, a beam intensity control electrode and a beam electron Velocity control electrode arranged to receive said image color information signals, a target area consisting of a plurality of diierent selected component color light producing areas spread over said target area side by side, a material poties to retard the velocity of said beam by pre- The 7.. determined different amounts, said predetermined amounts corresponding to selected component color` representations, and wherein all material having like physical properties is positioned adjacent areas producing one only of said different selected component color lights and in the path of said electron beam.

3. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to receive image color information, a target of luminescent material, a plurality of different selected component color light filters each of image elemental area spread over said target area, a mechanical medium barrier positioned between said target area and said electron gun having different predetermined physical properties to retard the velocity of said beam by predetermined different amounts, said predetermined amounts corresponding to selected component color representations, and wherein all of said medium having like physical properties is positioned adjacent filters of one only of said different selected component color and in the path of said electron beam.

4. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to receive image color information, a mosaic target area consisting of a plurality of diierent selected component color light producing areas spread over said target area, a

material positioned in the direct path of said beam having different predetermined thicknesses to physically retard the velocity of said beam by predetermined different amounts, said predetermined amounts corresponding to selected component color representations, and wherein all material having like thicknesses is positioned adjacent areas producing one only of said different selected component colors and in the path of said electron beam.

5. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam intensity control electrode and a beam electron velocity control electrode, said beam electron velocity control electrode arranged to receive a potential depending upon the image color information of the point under scansion, and a mosaic luminescent target, the color of luminescence depending upon the Velocity of impact of said electrons, said target including a material positioned in the path of said beam and having different predetermined physical properties to retard the velocity of said beam by predetermined different amounts, said predetermined amounts corresponding to selected component color representations.

6. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam intensity control electrode and a beam electron velocity control electrode, said beam electron velocity control electrode arranged to receive a potential depending upon the image color information of the point under scansion, and a luminescent target, the color of luminescence depnding upon the velocity of impact of said electrons, said target including a material having different predetermined physical thickness to the path of said beam to retard the velocity of said beam by predetermined different amounts, said predetermined amounts Varying across the target area corresponding to selected component color representations.

7. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam intensity control electrode and a beam electron velocity control electrode, said beam electron velocity control electrode arranged to receive a potential depending upon the image color information of the point under scansion, anda luminescent target, the color of luminescence depending upon the velocity of impact of said electrons, said target including a maf terial having diierent predetermined physical thickness across its face to retard the velocity of said beam by predetermined different amounts, said predetermined amounts corresponding to selected component color representations, and wherein all the material having the same thickness is positioned adjacent to the same color luminescent portion of the target said material being positioned between said target and said electron gun.

8. A colored light producing system comprising a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to electrically r ceive color information, a target area consisting of a plurality of different selected component color light producing areas spread side by side with respect to the direction of said beam over said target area, a material having dilerent predetermined physical properties to retard the velocity of said beam by predetermined different amounts, said material being positioned on the gun side of said target area, said predetermined amounts corresponding to selected component color representations, and wherein all material having like physical properties is positioned adjacent one of said diiferent selected component color light producing areas and in the path of said electron beam.

9. A colored light producing system comprising an electron discharge device, an electron velocity control electrode arranged to electrically receive color information and to impart to said electrons a velocity dependent thereon, an electron target area consisting of a mosaic of different selected component color light producing areas spread over said target area, a material having diiferent predetermined physical properties to retard the velocity of said electrons by predetermined different amounts, and wherein all material having like physical properties is positioned adjacent one of said different selected component color light producing areas and within the path of said electrons.

10. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to receive image color information, a target of luminescent material, a material positioned between said target and said gun and spread over said target area having different predetermined physical properties at different points across the area of said target to retard the velocity of said beam by predetermined different amounts, said predetermined amounts corresponding to selected component color representations, and wherein said material also has diierent light color filter properties depending upon its physical properties.

11. An image reproducing system for color television comprising in combination a cathode ray tube including an electron gun for forming an electron beam, a beam electron velocity control electrode arranged to receive image color information, a target of luminescent material, a material spread over the inside of said target area having diierent predetermined thicknesses across the target area to retard the velocity of said beam by predetermined different amounts, and wherein said material also has diierent color light transmission'properties depending upon its thickness.

12. A colored light producing system comprising a cathode ray tube including an electron gun for forming an electron beam. a beam electron velocity control electrode arranged to electrically receive color information, a material spread over the inner surface of said target area having diierent predetermined physical properties at diierent'points across the face of said target REFERENCES CITED The following references are of record in the lefof this patent:

UNITED STATES PATENTS Number Name Date 2,296,908 Crosby Sept. 29, 1942 2442,961 Ramberg rJune 8, 1948 214a44o swedhmd Aug. 3, 1948 25455310 Szegho Dec. '7, 1948 Bronwell Feb. 15, 1949

Images