US2899579A

US2899579A - Cathode ray tubes or the like -

Info

Publication number: US2899579A
Authority: US
Publication date: 1959-08-11
Anticipated expiration: 1976-08-11

Description

Aug. 11, 1959 c. w. GEER 2,899,579

CATHODE RAY TUBES OR THE LIKE I Filed June 21, 1954 I 10 Sheets-Sheet 1' CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER 7 2,899,579

CATHODE RAY TUBES OR THE LIKE Filed June 21, 1964 10 Sheets-Sheet 2 I TEi E! g I CHARLES WILLARD GEER INVENTOR. =I T 6 svflw-w HlS ATTORNEY" Aug. 11, 1959 c. w. GEER Y CATHODE RAY TUBES OR THE LIKE 1 1O Sheets-Sheet 3 Filed June 21. 1954 CHARLES WILLARDGEER IN VEN TOR. BYflw M HIS ATTORNEY Aug. 11, 1959 c; w, GEER 2,899,579

CATHODE RAY TUBES OR THE Lmz Filed June 21. 1954 1o Sheets-Sheet 4 CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER CATHODE RAY TUBES OR THE LIKE 10 Sheets-Sheet 5 Filed June 21, 1954 '7-"--------1'--'--;}-----------"Ffl CHARLES WILLARD GEER ,9 INVENTOR. gyflual HIS ATTORNEY Aug. 11, 1959 c. w. GEER CATHODE RAY TUBES OR THE LIKE l0 Sheets-Sheet 6 Filed June 21, 1954 CHARLES WILLARD GEER INVENTOR. BY a-M HIS ATTORNEY Aug. 11, 1959 Filed June 21, 1954 c. w. GEER 2,899,579

- CATHODE RAY TUBES OR THE LIKE 1O Sheets-Sheet 7 CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER CATHODE RAY TUBES OR THE LIKE 10 Sheets-Sheet 8 Filed June 21, 1954 CHARLES WILLARD GEER INVENTOR. syfifi HIS ATTORNEY Aug. 11, 1959 c. w. GEER 2,899,579

CATHODE RAY TUBES OR THE LIKE Filed June 21, 1954 10 Sheets-Sheet 9 CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEERY CATHODE RAY TUBES OR THE LIKE l0 Sheets-Sheet 10 Filed June 21, 1954 CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY United States Patent 2,899,579 CATHODE RAY TUBES on THE LIKE Charles Willard Geer, Long Beach, Calif., assignor to Hoffman Electronics Corporation, a corporation of California Application June 21, 1954, Serial No. 438,096

12 Claims. (Cl. 313--81) This invention relates to improvements in cathode ray tubes and, more particularly, to an improved structure for the reproduction of television images in natural color. In the past numerous devices and systems have been proposed for color television reproduction, but such apparatus has suffered from defects which fall into four main categories. First, the definition available with cathode ray tubes utilizing a single gun and bands of difierent colored phosphor has proven, generally, poor and the grain or line structure has been very objectionable. Further there are undesired effects from the grid switching usually found in tubes of this type. Second, in tubes utilizing parallax grids or shadow masks'the high loss of electrons at the shadow mask has resulted in low line intensity from the tubes. Third, tubes utilizing three guns and, for example, a screen formed of pyramidal elements, such as that shown and described in my Patent No. 2,480,848, have been bulky in form and not easily adaptable to home television receiver cabinetry. Fourth, a characteristic particularly existent in the shadow mask type of tubes is the high cost of manufacture arising from the familiar problems of obtaining alignment or registration between the shadow mask and the various color producing phosphors.

Therefore, it is an object of this invention to provide an improved cathode ray tube for reproduction of images in color.

It is a further object of this invention to provide a color television reproducing tube which affords high definition and freedom from objectionable line structure at a minimum cost and with a form factor which makes the tube adaptable to home receiver use.

It is a further object of this invention to provide a relatively low-cost color television reproducing tube in which certain of the grid structures may be formed by low-cost weaving techniques.

According to one embodiment of the present invention, there is provided a cathode ray tube utilizing multiple cathode ray guns arranged in parallel fashion within the neck of the tube and in which the screen is formed of a multiple of pyramidal elements of the tyme utilized in the structure according to my Patent No. 2,480,848. Interposed between the electron guns and the screen are three grids, the first of which acts as a parallax-convergence or convergence and positioning grid. The second of such grids counting from the gun side to the screen side is an electrostatic deflection grid charged from an external source so as to deflect the impinging electron beams in a predetermined direction. The third of such grids which is spaced relatively closely to the second of such grids completes the beam deflection process as a result of its being charged with an appropriate static potential. A

corresponding deflection may be effected by electromag-' lieved to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, may best be under= stood by reference to the following description, taken in connection with the accompanying drawings, in which:

Figure 1 is a side elevational view, partially in section, showing one embodiment of the invention;

Figure 2 is a cross-sectional view taken along line 22 in Figure 1;

Figure 3 is a view taken along line 33 in Figure 1;

Figure 4 is an enlarged view of a portion of the grid structure shown in Figure 3;

Figure 5 is a sectional view taken along line 55 in Figure 1 showing the most proximate grid;

Figure 6 is an enlarged view of a portion of the outermost grid shown in Figure 5;

Figure 7 is a sectional view taken along line 77 in Figure 1;

Figure 8 is an enlarged view of a portion of the grid shown in Figure 7;

Figure 9 is a sectional view taken along line 99 in Figure 1;

Figure 10 is an enlarged view of a portion of the screen or electron target shown in Figure 9;

Figure 11 is an enlarged perspective view showing the relative orientation of the grid structures shown in Figures 3, 5 and 7, and, in addition, showing the orientation of a segment of the screen structure of Figure 9 associated with the enlarged portion of the grid;

Figure 12 is a side elevational View, partially cut away, of a second embodiment of the invention;

Figure 13 is a cross-sectional view taken along lines 13 -13 in. Figure 12;

Figure 14 is a sectional view taken along line 14-14 in Figure 12 showing the most proximate grid;

Figure 15 is an enlarged view of a portion of the grid structure disclosed in Figure 14;

Figure 16 is a sectional view taken along line 15-46 in Figure 12 showing t e m pro t gr d;

Figure 17 is an enlarged view of the Portion of the grid structure shown in Figure 16;

Figure 18 is a sectional view taken along line 18.- 1 8 in Figure 12 showing the most proximate grid;

Figure 19 is an enlarged view of a segment of the grid structure shown in Figure 18;

Figure 20 is a sectional view taken along line 20-- 20 in Figure 12;

Figure 21 is an enlarged view of the segment of the target structure shown in Figure 20;

Figure 22 is a perspective view showing the relative orientation of the grid structures and screen structure according to this invention;

Figure 23 is a diagrammatic representation of a twogun embodiment of the present invention;

Figure 24 is a diagrammatic representation of an additional embodiment of a four-gun cathode ray tube utilizing electromagnetic rather than electrostatic deflection;

Figure 25 is an enlarged view of a portion of the grid structure shown in Figure 24; and

Figure 26 is a view, partially in schematic form, of the deflection grid of Figure 24.

In Figure 1, a beam of electrons is generated in the electron guns 10 and 11, which are shown in Figure 1, and in two

additional electron guns

20 and 21 not visi- Me in Figure 1 but visible in Figure 2. These electron guns are of the conventional variety utilized in cathode ray tubes and includes the necessary cathodes, control grids and accelerating electrodes, which are not shown because of their conventional nature. Electrons from each of the guns first pass through apertures in grid 12 which is positioned and tensioned by support member 13. The function of this first grid is to converge the electron beams and position each of the beams at the appropriate point on grid 14. To realize those effects, this grid is maintained at a negative potential. The term parallax-convergence grid as used throughout the specification and claims is intended to mean a unitary or composite grid which is so constructed and positioned within the cathode ray tube as to, upon apobserver views the side of target structure remote from the phosphored surfaces, hence, the target struc/ ture must be transparent. Grid 16, which is in close proximity to grid 14, is also a deflection grid and supplements the initial effect produced by grid 14, further assuring the proper impingement of the electron beams on target or screen 15. The relative positioning of

grids

12, 14 and 16 is assured by the rigid nature of support member 13 of this multiple grid assembly and support member 13 is in turn supported from envelope 17 by means of

support elements

18 and 19.

In Figure 2, the relative orientation of the four guns utilized in this embodiment of the invention is shown. Gun 20 is positioned so that the electrons emanating from it impinge upon the blue-producing phosphor of target 15. Correspondingly, electrons from

guns

21, 22 and 23 impinge upon the red, white and green phosphors, respectively, of the target structure 15. In Figure 3, grid 12 may be stamped, electro-formed or woven by well known and economical techniques. For purposes of discussion grid 12 is considered to have been made by a weaving process, as may be more clearly determined by reference to the enlarged view in Figure 4. Because of the common potential of all of the conductors 40 the grid may be woven from bare wire of the appropriate dimensions, and because of the high degree of vacuum existing in the cathode ray tube, no problem of corrosion exists. Techniques are well established for weaving metal wire of small diameter and the process if simple and inexpensive.

An indication is also made in Figure 4 as to the points of impingement of the electron beams emanating from the various guns. As can be seen, the beams may impinge upon separate apertures and several at one time. Such positioning is not critical to the degree that positioning is critical in present day shadow mask tubes. Thus, the grid need not be constructed to extremely high tolerances and with a reasonable amount of tensioning in support member 13 and with proper orientation with respect to

subsequent grids

14 and 16, which will be discussed later, proper functioning of the cathode ray tube may be realized. Grid 40 is maintained at a negative potential so that the beam of electrons impinging upon it from each of the guns is condensed or converged and, at the same time, positioned in some degree.

In Figure 5, grid 14 is of a conductive material and may be formed by stamping, electro-forming or by weaving. Once again, the grid has been shown as woven, which is more evident in the enlarged view of .Figure 6.

The purpose of this size differential will become more 'from their apexes. the invention the pyramids are quadrahedronal, each In Figure 6, the points of electron beams impinging on grid 14 or its interstices are indicated. Grid 14 is maintained at a positive potential so as to attract the electron beams towards the grid elements 60. Thus, the beams must fall in the region of the intersection between grid elements and on the indicated sides of diagonal bisectors of each of the apertures of interstices, as indicated. Thus, in Figure 6, each of the red, green, white and blue electron beams will be atttracted towards intersection 61. An initial deflection of each of the electron beams is thus effected.

In Figure 7, grid 16 is composed of intersecting grid elements which may be formed by stamping, electro-forming or weaving. Once again the grids are shown as having been formed by a weaving technique. This is evident in Figure 8, the enlarged view. Once again the grid elements 70 are all operating at a common potential so that no insulating problems exist and the grid may, be woven from bare conductive wire. The relative positions of the electron beams impinging on grid 16 are indicated in Figure 8. Grid 16 is maintained at a negative potential so that it repels the .beams of the electrons.

Its orientation with respect to grid 14 is more clearly indicated in Figure 11, but generally this grid 16 is displaced one-half the width of one of its interstices in both the horizontal and vertical directions so that grid element 70 effectively bisects the interstices of grid 14 if the two

grids

14 and 16 are viewed either from the gun side of the grid combination or from the target side. Grid 16 thus provides the additionally required deflection of each of the electron beams to insure impingement on the proper portions of target or screen electrode 15.

In Figure 9, the relative positioning of the various pyramidal screen elements is shown. It is to be realized that in this figure the pyramids are viewed substantially In this four gun embodiment of of the four sides carrying a phosphor which produces one of the desired color components. This orientation of the pyramids and the different color phosphor is exhibited more clearly in Figure 10 wherein the standard designation for each of the primary colors and white are utilized showing the deposition of the phosphors on the various sides of the pyramids.

In Figure 11, the relative positions of

grids

12, 14 and 16 and target or screen electrode 15 and the spacings are indicated. It is to be noted that grid 12 is spaced from grid 14 a distance which is substantially greater than the distance from

grid

14 and 16. This spacing is a function of a number of factors, as follows.

By reason of the displacement of each gun from the common center between the guns the familiar phenomenon of parallax occurs and the electron beam from each gun has an angle of incidence upon a given interstice in convergence grid 12 which is different from that of the beam from each other gun. The establishment of a negative potential on grid 12 results in converging each incident beam and confining its point of passage through grid 12 to a common point in each interstice, which is substantially the geometrical center of each interstice. As the beams are scanned over the entire surface of grid 12 they move in discrete steps from aperture to aperture by reason of the negative potential maintained on grid 12. However, by reason of the aforementioned parallax effect, despite the shifting of each beam to such geometrical center, each beam emerges from grid 12 at an angle different from'that of each other beam and the beams remain separate as they fall upon predetermined points on the succeeding deflection grid 14. The points at which the beams fall in any given aperture in grid 14 are determined by the angles of incidence, and the separation between

grids

12 and 14.

From Figure 11 it may also be seen that the spacing of successive grid elements 40 is approximately one-half the corresponding spacing of grid elements 60 of grid 14 and, hence, the size of the interstices in grid 12 is onehalf the size of the interstices in grid 14. Also, it should be noted that whereas the outermost of

grid elements

40 and 60 lie substantially in a plane normal to

grids

12 and 14, the outermost grid element 70 of grid 16 is dis placed so that it does not lie directly behind grid element 60 but is centrally disposed in the distance between successive grid elements 60 of grid 14. Thus, behind each grid element 41) there lies either a grid element 60 or a grid element 70 but not both, all as viewed from the electron gun side of the grid combination. It should be noted that the electron beam positions indicated in Figures 6 and 8 represent, substantially, the point within the interstices where the indicated electron beam will fall as it passes over that interstice. However, at any one instant the electron beam from each of the electron guns may fall in different interstices but will fall in the indicated quadrants of any interstice in which each beam falls. The ultimate requirement is, of course, that the beam intended to produce each of the primary colors and white should produce only each of such colors throughout the scanning of the combination of the beams across the screen or target structure 15. To accomplish this the separation of

grids

12, 14 and 16 and the potentials applied to each of these grids must be properly established. When that relationship is established, each of the beams emerging from the grid combination should have a main component oriented approximately in a normal direction to the plane of the pyramid face bearing the phosphor which each such beam is intended to excite. Once that relationship has been established, any movement of the entire grid combination in a plane parallel to the plane of the pyramid bases will produce no color infidelity because of the discrete directional component of each of the electron beams. Thus, the complex registry problem presently encountered in shadow mask or parallax-grid color tubes is eliminated.

As has been indicated, the exact point in the interstice upon which each of the electron beams falls is not critical for a minor adjustment in the electrostatic potentials on each of the grids can compensate for any minor variations in the initial positioning of the beams on grid 12.

Further, the exact configuration of each aperture is not critical for a reasonable amount of uniform tensioning in support member 13 so that the general relative position of grid elements 40, 6t) and 70 is as already described, is all that is required. Upon such adjustment and positioning of the grids, possibilities of color infidelity are slight with this invention.

It should be noted that the loss of electrons in the convergence of beams in grid 12 is slight because of the large open areas and the use of negative potentials to condense or converge the beam or to position it as desired. In present parallax-grid tubes, a high electron loss occurs because the apertures, of necessity, are very small, the

registry between the parallax grid and the phosphor elements being extremely critical.

7 The foregoing description has dealt with a four-gun cathode ray tube capable of reproducing the three primary colors plus white light energy which corresponds to the brightness of any scene to be reproduced. It is entirely possible to reproduce an original image in natural color using only the three primary colors and applying brightness information to each of the three guns producing the electron beams which ultimately produce the three primary colors. A cathode ray tube utilizing the structural principles of the present invention and capable of reproducing images in natural color through the use of three primary colors is shown in Figure 12 and details of that tube are shown in succeeding Figures 13 through 22. In Figure 12 cathode ray tube 126 includes electron 1

guns

121, 122 and 123 which may be designated for the purposes of this description as the blue, green and red electron guns, respectively. The exact orientation of flection grid 126 and second deflection grid 127, the shape and orientation of the various apertures in those grids being shown more clearly in Figures 14 through 20. As can be seen in Figures 12 and 22, the spacing between grids and 126 is large with respect to the spacing between

grids

126 and 127. The relative positioning of the three grids is fixed and maintained by means of support 128, which, in turn, is directly supported from envelope 129 of cathode ray tube 120 through bracket element 130.

The cathode ray tube of Figure 12 operates substantially as follows. A beam of electrons of the appropriate velocity is generated in conventional fashion by each of the

guns

121, 122 and 123. These guns may include the conventional first accelerating anodes and focusing electrodes, neither of which is shown. As can be seen from Figure 15, electrons from each of the guns pass through apertures in positioning grid 125. These apertures are surrounded by

conductive grid elements

151, 152, 153, 154, and 156 which may be formed by weaving, as shown in Figure 15, or by stamping or electroforming. A negative potential is applied to this grid so as to produce convergence of the impinging electron beams. It is to be noted that at any one instant, the three separate electron beams may be passed through three separate apertures 150 in grid 125 but when any one of the beams, for example, the red beam, passes over a given interstice it Will pass through the grid at a point having the indicated relationship with respect to the point of passage of the other beams. It is to be noted that by utilizing negative potentials on this grid, it is possible to use a grid having a relatively large mesh while retaining the desired positioning efiect, thus reducing the loss of electrons which normally results from the striking of the conductive members forming the boundaries of the apertures or interstices. Grid 125 may be woven from conductive material, as shown in Figures 14 and 15, stamped from conductive material or electro-formed.

Upon emerging from grid 125, each of the electron beams impinges upon grid 126, or more accurately, upon the apertures in grid 126. The relative positions of the three beams in their respective traversals of any one of the apertures in grid 126 are as shown in Figure 17. It is to be noted that at any instant, the red, blue and green beams may not fall within the same aperture but, instead, may fall within apertures separated from aperture $170 as suggested by Figure 12, the only ultimate requirement being that the beams impinge upon a common trihedron or pyramid in target structure 124. As can be seen from Figures 17 and 22 grid 126 is a composite grid including portion 126A positioned closest to the electron guns and portion 126B spaced from portion 126A along the electron path and further from the electron guns than portion 126A. A high negative potential is applied to portion 126A and an equally high positive potential is applied to portion 126B. The two grid portions obviously must be insulated from each other and this is accomplished by insulating beads 157. The negative charge on portion 126A begins the deflection of each of the electron beams. It should be noted that portion 126B has hexagonal apertures of approximately the same size as portion 126A but the apertures of portion 126B are displaced from alignment with those of 126A one-half an aperture width in one direction and one-half a diagonal length in an orthogonal direction. The positive potential is applied to grid 126B so that the beams of electrons are pulled towards

elements

171, 172 and 173, as shown in '7 Figure 17. As a result of the fact that grid 126A is charged as far negatively as grid 126B is charged positively, the net deceleration of the electron beam through grid 126 is substantially zero while at the same time the desired discrete deflection of the respective electron beams is effected.

The deflected beams emerging from grid 126 impinge upon grid 127, shown in its entirety in Figure 18, which grid may be of the same grid pattern as grid 126 but is displaced both vertically and horizontally so that the intersection of

elements

171, 172 and 173, shown in Figure 17, is substantially aligned with the geometrical center of the aperture or interstice 190 of Figure 19, shown bounded by

elements

191, 192, 193, 194, 195 and 196. This orientation is indicated in Figure 16.

Grid 127 is charged negatively and, partially by reason of the relative displacement between

grids

126 and 127, accentuates the deflection of each of the electron beams so that upon emerging from grid 127 those beams have discrete and differing directions. The position of

guns

121, 122 and 123, as shown in Figure 13, is such that each beam takes a different path through

grids

126 and 127 and falls upon a predetermined face of a common trihedron which face carries the appropriate phosphor possessing the ability to produce one of the primary colors. For optimum color intensity each of the beams should have substantially normal incidence upon its associated phosphor. The orientation of the trihedronal elements forming target structure 124 is shown most clearly in Figure 21. In that figure there is shown a segment of target structure 124, shown in its entirety in Figure 20, viewed from the line of approach of the electron beams. Pyramidal element 210 has

faces

211, 212 and 213 bearing phosphors which produce red, blue and green light energy. As can be seen from Figure 12, to attain this normal incidence of the electron beams upon the related phosphors utilizing the deflection system of this invention, the three

electron guns

121, 122 and 123 may have a relatively wide angular displacement so that at any one instant the beam from any one gun falls at a point on grid 125 which is relatively widely separated from the point at which a beam from either of the other guns falls. This may necessitate having the

grids

125, 126 and 127 of greater area than target electrode 124.

If the beams from

electron guns

121, 122 and 123 are scanned over the complete surface of target 124, the beams will fall upon the predetermined sides of successive trihedronal elements making up the target electrode 124 and the originally scanned image will be reproduced. This scanning may be accomplished by any of the well known electromagnetic or electrostatic techniques. As has been indicated in connection with the four-gun tube, minor discrepancies of aperture size and grid spacing are tolerable and may be easily compensated by voltage adjustments on

grids

125, 126 and 127. Once again a high electron efliciency is realized because of the relatively wide spacing of the grid elements in grid 125 and the utilization of the negative potential thereon to accomplish the necessary convergence and initial positioning. The positioning of the grid combination with respect to the target electrode 124 is not critical, particularly as to lateral displacement, because of the discrete directions attained by the three electron beams upon emerging from the grid combination and the corresponding discrete directions of the trihedron faces.

For certain applications, such as in radar, the combination of two primary colors may provide a sutficient range of hues to indicate the desired information. The relationship of the electron guns, grid structures and target electrode is shown in Figure 23. In that

figure electron guns

230 and 231 are of a conventional variety. Electron beams emanating from those guns first fall upon a convergence and positioning grid 232 the apertures in which have the general configuration of a square or rectangle as shown in Figure 23. Convergence grid 232 is made up of'conductive elements 233 and 234 which are charged to a common negative potential. After each beam emerges from convergence and positioning grid 232, it falls in the area between successive elements 235 and 236 of first deflection grid 237. In the structure shown in Figure 23 positioning grid 237 is charged negatively and by reason of the repulsion between the electrons and the negatively charged grid elements the electron beam is given an initial displacement as shown. Each electron beam upon emerging from grid 237 impinges upon grid 233 which comprises elements 239 and 240 spaced the same distance as elements 235 and 236 but positioned midway between elements 235 and 236. This grid is charged positively and is spaced from grid 237 so that the attracting action of element 240 upon an impinging electron beam exceeds that of element 239, the initial displacement produced by grid 237 is accentuated and the beams emerging from grid 238 have discrete directions differing widely from each other and the beams approach surfaces 241 and 242 of target 243 with approximately normal incidence, as shown. Once again, by reason of the discrete directions of motion to which the electron beams have been confined and the corresponding orientation of the related phosphor laden surfaces, each gun will hit only one set of surfaces on target 243 throughout the scanning process.

In the discussion of the four-gun tube shown in Figures 1 and 2, and, in effect, in connection with the other color tubes thus far described, electrostatic deflection has been utilized to effect the desired development of separate electron beams having discrete and different directions. This same eflect can be realized by electromagnetic deflecting means. A possible embodiment is exhibited in various details in Figures 24 through 26. In Figure 24 convergence and positioning grid 245 corresponds to convergence grid 12 in Figure 1 and accomplishes the same results, namely convergence of the beam and positioning of it properly on the deflection grid 246.

As can be seen from Figure 24 the electron beams from the four guns cluster about alternate vertical elements 247 in which currents are flowing in a direction such that they produce flux lines flowing in a counterclockwise direction. By applying well known principles of electron optics, more specifically the so-called lefthand rule, it can be shown that electrons having the initial direction shown in Figure 24, namely a downward direction, will be deflected towards the axis of the wire adjacent which they are flowing. For a given orientation of pyramidal elements 248, the four electron beams emerging from deflection grid 246 must have discrete and difiering directions related to such pyramidal orientation. The convergent efiect of current carrying elements 247 with the aid of the effects produced by the fields surrounding elements 253 results in the acquisition by the four electron beams impinging upon grid 246 of the necessary discrete directions. As described earlier, each of the faces of any one pyramid carries a phosphor exhibiting a different color response upon impingement of an electron beam.

Further details of the deflection grid are indicated in Figure 26 which shows the direction of the magnetic fields surrounding each of the

vertical elements

247 and 253 constituting the deflection grid. The single dot indicates the head of an arrow directed in the same direction as the current flow (upward here) and each x indicates the position of each vertical element in which the current flow is in a relatively downward direction. By applying the left-hand rule it will become apparent that if the electron beams were directed downward towards the vertical elements in which the current is directed downward the beams will be diverged rather than converged. As has already been indicated this effect aids the desired deflection fields produced by current carrying elements 247.

Because of the extended length of deflection grid 24,6

9 in the direction of the electron movement, it is not neces sary to have a second layer of grids to realize the desired degree of beam deflection. The successive rows of de- :flection elements forming the deflection grid 246 may be joined electrically at alternate ends so as to require connection to a source of current of only the resulting two open ends of the grid.

- Convergence and positioning grid 245 may be formed by weaving, stamping or electro-forming.

It may be seen from the foregoing description that there has been provided a cathode ray tube for the reproduction of televised images in natural color which tube will provide a high intensity picture and also will be sufficiently compact to be adaptable for use in home television receivers and which will be relatively simple and inexpensive to manufacture by reason of the considerable reduction in the problem of registering the convergence and deflection grids with the target structure and with each other.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A cathode ray tube for presenting information in color, including a plurality of electron guns, a target structure including a plurality of sets of faces, the faces within each set lying in parallel planes at an angle toward the initial direction of the beams from said guns, and means for causing impingement of the beams upon the target faces substantially normal thereto including an apertured parallax grid between the guns and target for positioning the beams impinging thereon at similar locations in the apertures thereof, and a deflection grid between the parallax grid and target for deflecting the beams emerging from the parallax grid in a direction substantially normal to the target faces.

2. A cathode ray tube for presenting information in color, including a plurality of electron guns, a target structure including a plurality of sets of faces, the faces Within each set lying in parallel planes at an angle toward the initial direction of the beams from said guns, and means for causing impingment of the beams upon the target faces substantially normal thereto including an apertured parallax grid between the guns and target for positioning the beams impinging thereon at similar locations in the apertures thereof, and a deflection grid between the parallax grid and target for deflecting the beams emerging from the parallax grid in a direction substantially normal to the target faces, the number of such sets equalling the number of said guns.

3. A cathode ray tube for presenting information in color, including a plurality of electron guns, a target including a plurality of multi-hedrons with common orientation in which the sides are at an angle toward the initial direction of the beams from said guns, and means for causing impingement of the beams upon the sides substantially normal thereto including an apertured parallax grid between the guns and target for positioning the beams impinging thereon at similar locations in the apertures thereof, and an electromagnetic deflection grid between the parallax grid and target for deflecting the beams emerging from the parallax grid in a direction substantially normal to the sides.

4. A cathode ray tube including four electron guns, a target including a plurality of tetrahedrons oriented to provide four sets of faces, each set having a common direction differing from each other set, .a parallax convergence grid and first and second deflection grids interposed in that order between said guns and said target along the line of movement of the electrons from said guns, said convergence grid having substantially squareapertures therein of a first size, said first deflection grid having apertures therein of substantially square configuration and of substantially twice the size of said convergence grid apertures, said second deflection grid having apertures therein of substantially the same size as said first deflection grid but displaced from alignment with the apertures of said first grid substantially onehalf the width of one of said apertures in said first deflection grid, the spacing between said convergence grid and said first deflection grid being greater than the spacing between said first and second deflection grids, and means for applying electrostatic potentials to said convergence and deflection grids.

5. A cathode ray tube including four electron guns positioned at small angles with respect to each other, a target including a plurality of tetrahedrons oriented] to provide four sets of faces, each set having a common direction differing from each other set, .a parallax convergence grid and first and second deflection grids interposed in that order between said guns and said target along the line of movement of the electrons from said guns, said convergence grid having substantially square apertures therein of a first size, said first deflection grid having apertures therein of substantially square configuration and of substantially twice the size of said con- Wergence grid apertures, said second deflection grid having apertures therein of substantially the same size as said first deflection grid but displaced from alignment with the apertures in said first deflection grid substantially one-half the width of one of said apertures in said first deflection grid, the spacing between said convergence grid and said first deflection grid being greater than the spacing between said first and second deflection grids, and means for applying electrostatic potentials to said convergence and deflection grids.

6. For use in a color television reproducing tube, a grid combination including a parallax grid, and a deflection grid, said parallax grid being positioned with its interstices in substantial alignment with the interstices in said deflection grid and spaced a predetermined distance from said deflection grid, said parallax grid being adapted for the application of a negative potential thereto, whereby electrons impinging upon said parallax grid from a given source will fall consistently on predetermined portions of said deflection grid.

7. A cathode ray tube for reproduction of images in natural color including a plurality of cathode ray guns clustered about a common axis, a parallax grid .adapted for connection to a source of negative potential, a first deflection grid positioned parallel to said parallax grid and spaced therefrom .a predetermined distance, the interstices of said first deflection grid being in predetermined relation to the interstices in said parallax grid, whereby electron beams from each of said guns fall consistently on predetermined portions of said first deflection grid, said first deflection grid being adapted for connection to a source of deflection potential, a second deflection grid having interstices corresponding in size and configuration to said first deflection grid and positioned to supplement the deflection produced by said first deflection grid, whereby discrete and differing directions are given to the electron beams from each of said guns.

8. A cathode ray tube for presenting information in color, including three electron guns, a target including a plurality of equally spaced trihedrons each bearing on each of its three faces one of three different phosphors each responsive to electron bombardment to produce a primary color, and a plurality of grids interposed between said guns and said target, said plurality including a parallax grid, a first deflection grid and a second deflection grid positioned in that order along the line of motion of electrons flowing from said guns to said target, all of said grids having substantially hexagonal apertures of approximately equal size, said apertures of said parallax and first deflection grids being substantially aligned,

said second deflection grid being positioned with the apertures therein displaced from alignment with said first deflection grid one-half an aperture width in one direction and one-half a diagonal length in an orthogonal direction.

9. A cathode ray tube for presenting information in color, including a plurality of electron guns, a target including a plurality of multi-hedrons with common orientation in which the sides are at an angle toward the initial direction of the beams from saidguns, and means for causing impingement of the beams upon the sides substantially normal thereto including an apertured parallax gridbetween the guns and target for positioning the beams impinging thereon at similar locations in the apertures thereof, and an electromagnetic deflection grid between the parallax grid and target for deflecting the beams emerging from the parallax grid in a direction substantially normal to the sides, said electromagnetic deflection grid including a plurality of elements disposed parallel to each other and lying in planes normal to the plane of the parallax grid.

10. For use in a cathode ray tube, a grid combination including a parallax convergence grid and an electromagnetic deflection grid, said convergence grid being disposed in a first plane, said electromagnetic deflection grid including deflection elements disposed in a direction normal to said first plane.

11. A cathode ray tube for presenting information in color, including at least one electron gun, a parallax grid, at least one deflection grid and a target structure, in that order, said parallax grid and said deflection grid being spaced a predetermined distance from each other and having a predetermined relative orientation, said target structure bearing a plurality of phosphors each producing light energydiflerent from that produced by the others upon bombardment by electrons from said at least one electron gun; said parallax grid comprising a plurality of inter-connected closed conductive paths.

12. A cathode ray tube for presenting information in color, including at least one electron gun, a parallax grid, at least one deflection grid and a target structure, in that order, said parallax grid and said deflection grid being spaced a predetermined distance from each other and having a predetermined relative orientation, said target structure bearing a plurality of phosphors each producing light energy different from that produced by the others upon bombardment by electrons from said at least one electron gun; said parallax grid and said deflection grid each including a plurality of interconnected closed conductive paths.

References Cited in the file of this patent UNITED STATES PATENTS