US2745035A - Color television tube target structure - Google Patents

Color television tube target structure Download PDF

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Publication number
US2745035A
US2745035A US399754A US39975453A US2745035A US 2745035 A US2745035 A US 2745035A US 399754 A US399754 A US 399754A US 39975453 A US39975453 A US 39975453A US 2745035 A US2745035 A US 2745035A
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Prior art keywords
grid
screen
color
phosphor
center
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US399754A
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Ernest O Lawrence
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Chromatic Television Laboratories Inc
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Chromatic Television Laboratories Inc
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Priority to NL193468D priority Critical patent/NL193468A/xx
Priority to BE534345D priority patent/BE534345A/xx
Application filed by Chromatic Television Laboratories Inc filed Critical Chromatic Television Laboratories Inc
Priority to US399754A priority patent/US2745035A/en
Priority to DEC10457A priority patent/DE1080595B/de
Priority to FR1117283D priority patent/FR1117283A/fr
Priority to GB37000/54A priority patent/GB773339A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/80—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching
    • H01J29/803—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching for post-acceleration or post-deflection, e.g. for colour switching
    • H01J29/806—Electron lens mosaics, e.g. fly's eye lenses, colour selection lenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/30—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines
    • H01J29/32—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines with adjacent dots or lines of different luminescent material, e.g. for colour television
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/20—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours
    • H01J31/201—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/16—Picture reproducers using cathode ray tubes

Definitions

  • the invention relates to tubes of the type in which a plurality of dierent phosphors which are emissive of light, on electron impact, of diierent component colors additive to-produce white light, are distributed in a repetitive pattern which covers substantially the entire area of a display screen which forms one element of the target structure,
  • the sub-areas of the screen occupied by the individual phosphors in tubes of this type are in at least one dimension of smaller size than the elemental areas or picture points of the images to be reproduced by the system and the display of individual colors is controlled by conlining the beam of cathode rays which traces the image to the particular phosphor or phosphors emissive of the color desired.
  • the type of tube to which this invention specifically pertains the restriction of the beam to a size which will limit it to an individual phosphor sub-area is accomplished by means of a multiplicity of electron lenses which converge the beam to a size smaller than that of the apertures through which it falls. It is the structure used so to converge the beam that forms the second element of the target.
  • This may be a perforated screen or one or more grids comprised of linear conductors; however it may be constructed, whether of a single perforated plate, a single array of approximately parallel wires or narrow strips or tapes or a plurality of such sets of conductors, its function is the same, and for convenience it will generally be referred to hereinafter as the lensgrid or simply the grid.”
  • the conductors of the lens-grid may occupy a very small proportion of its over-all area and the proportion of the beam intercepted by the structure is thus reduced from a minimum of two-thirds to something in therneighborhood of fteen percent or even less.
  • Arrangements of 2,745,035 Patented May 8, 1956 utilizes the display screen itself (which is made conducting) as one element of the multiplicity of electron lenses.
  • conductivity is provided by depositing a thin lilm of metal, preferably aluminum, on the surface of the phosphor layer which covers the screen so that the metal film is faced toward the electron beam source.
  • the grid structure is biased by a voltage which is substantially the same as that used to accelerate the beam as it issues from an electron gun (or guns) of substantially conventional type.
  • the conducting lilm on the screen is made positive with respect to the grid, and by properly adjusting the ratio of the voltage applied to accelerate the beam to that between grid and screen al greater or less degree of convergence of the beam, after passing the grid, may be obtained.
  • the Y additional advantage in the fact that a relatively low voltthus broadly indicated.
  • a target structure which will display the saine color over all parts of the screen under given conditions of color control applied to the tube, and thus give equal delity of color reproduction throughout the picture field; to provide means and methods for so positioning the phosphor areas with relation to the grid as to accomplish such color fidelity; to provide means and methods of the character described which are applicable to tubes of many types, including both those which use a plurality of electron guns and achieve their color control by virtue of the angle of incidence of the Various beams at the grid and those wherein the color control effected by means of micro-deflection at the grid; to
  • the invention comprises a target structure including a substantially plane base on which phosphors emissive of a plurality of'component colors additive to produce white are deposited in a repetitive pattern of groups, each of which includes all of the phosphors employed, the dimensions of each group being, in one direction atleast, of the order of magnitude of one elemental area of the picture to be' reproduced.
  • Means are provided for rendering the screen conducting and for applying an acceleration potential vthereto relative to a grid, which is mounted in a plane substantially parallel to the screen and is provided with apertures corresponding in number to the phosphor groups.
  • Fig. l is a schematic illustration of a cathode-ray tube of a type embodying the instant inYention, ,Operating-circuits for this tube being illustrated in block form;
  • Fig. 2 is an illustration of a portion ,of one type of display screen as used in the tube illustrated in Fig. 1, showing the pattern in which the phosphors are .disposed on the screen;
  • Fig. 3 is a similar view of a portion of a display screen f wherein the phosphors are disposed ⁇ in a linear or a strip pattern;
  • Fig. 4 comprises graphs illustrative of .the relationships
  • Fig. 5 is a diagrammatic illustration showing an elec- ⁇ tron trajectory between a single grid and the display screen
  • Fig. 6 is a series of graphs illustrating the displace,- ment of the focal spot upon the screen, with respect to the perpendicular Idropped from the centers of the apertures in the grid, with varying anglesV of -incidence thereto and with different types of grids or degrees'of focusing;
  • Fig. 7 is an exaggerated illustration of the shape .of the pattern of phosphors upon adisplay screen with a target structure employing uniform spacing of apertures in the grid;
  • Fig. 8 is a similarly exaggerated diagram illustrating the shape of the electrode structure .for use with a screen. having a rectilinear pattern of phosphors thereon.
  • a tube basically of conventional form, which is indicated at 1 of Fig. l.
  • a tube comprises the .usual evacuated envelope .3, which may be of al1 lglass construction or of metal and glass.
  • lt has the usual viewing window 5 at its enlarged end and an electron gun 7 in the neck.
  • Such a gun comprises an electron emitting cathode 9, a control grid 11, a rst anode 13 and 4a second anode 15.
  • the tube as shown for the purpose of illustrating one form of deflection control, is provided with pairs of deflecting plates 17 and 19 forl deflecting a beam ot cathode rays, produced by the gun, vertically .and 'horizontally respectively.
  • Fig.- 2 shows the disposal of the color areas upon adisplay surface 25. Basically,as this ligure indicates, the three l phosphors which contribute luminescence in the primary colors of the additive systems are disposed upon the base 25 in strips which extend completely acrossthe display area in one dimension. Strips 25,1 ,are continuous, 'consisting entirely of a phosphor luminescent in a single primary color. These strips are substantially uniform in Width and are parallel, spaced apart by a distance ⁇ Substantially equal to their own width in this particular screen, although, as will be shown hereinafter, this is not a necessary condition.
  • Intermediate strips 252 are discontinuous, comprising alternate blocks, 252 and 25"z, of the two remaining primary colors.
  • the blocks 25'2, 252 as here shown are square, and the junctionsbetween the blocks are alined across the display surf-ace so that the blocks in any one row, transverse to the direction of the continuous strips, are all of one color.
  • Fig. l may be considered, for the present purposes, as intended primarily for a field-sequential system and therefore strip 2,51 has been indicated, by the letter G, as luminescent in green, withl the block 252 luminescent in blue and blocks 25"'2 in red.
  • a lens grid structure Spaced from the plane of the display surface 2S, by a distance short in comparison with the ytotal length of the path of the ⁇ electron beam, is a lens grid structure which is comprised of two sets of linear electrodes, those in each set being parallel and substantially uniformly spaced, although, as will hereinafter be shown, neither the width of the phosphor strip nor the spacing of the grid conductors is necessarily exactly uniform.
  • the non-uniformitics are, however, although important, very small indeed,
  • the electrodes are conveniently tine wires, although they may be narrow strips or tapes, mounted edge-on to ⁇ the beam path. In the particular tube shown the first set of these electrodes, designated alternately as 2,7 and 27", is mounted generally parallel to the phosphor strips -on the display surface.
  • Electrodes 27 are connected to a common conductor 31; intermediate electrodes 27 are similarly connected to a common conductor 31. It may be noted that the mode of support for .electrodes 27 and 27 is not important to this specific invention and hence is not shown in detail. Various methods .of constructing such grids are shownin United States Letters Patents Nos. 2,653,263 and 2,695,372 of Ernest O. lLawrence, or in United States Patent No. 2,721,288, granted'on October 1S. 1955, to .laines T. Vale. VLeads 8, connecting to conductors 31 and 31', are provided for applying proper potentials to the electrodes of the structure, as by the horizontal coloroscillator 33.
  • a ⁇ second substantially similar set of linear conductors 35 and 35", similar to conductors 27 and 27 is mounted as'closely as conveniently possible to the rst set, between the latter and the electron gun. Leads 39 conneet to these electrodes and are also brought out of the tube so that the necessary potential relative to other elements can be applied thereto by a vertical color control oscillator 37. Owing to the difliculty of diagrammatic representation only two electrodes 35 and 35 of this second set are shown in Fig. l.
  • An electron permeable electrode substantially coextensive with the display surface, is placed, with respect to the lens grid structure, so that when proper relative potentials are applied to the elements of the system electrons from the beam passing through the lens grid will be focused substantially on the display surface.
  • a afnemen film is microscopic in thickness and serves the triple purpose of Vestablishing the lens forming the electric field with the lens grid structure, reecting luminescence from the screen outwardly through the window 5 and suppressing secondary emission of electrons from the display surface.
  • This film is not shown in Fig. 2 but is indicated by the reference character referred in Fig. 1 to the surface of the base 25 and the connection 41 for applying the focusing potential.
  • Fig. 2 shows the relative positions of the phosphar strips and the electrodes at the center of the screen.
  • electrods 27 bisect the continuous strips 251, while the electrodes 27' similarly bisect the discontinuous strips 252.
  • transverse electrodes 35 bisect the blocks 252 in the transverse direction while electrodes 35 bisect the remaining blocks 252.
  • the electrons entering the mesh can be brought into focus in the plane of the display surface and electrode 40.
  • an electron following a path which is the average of all of the electron paths in the beam would strike the display surface at the junction of the three different color phosphors in the center of the quadrilateral area defined by the mesh.
  • the focal point will be shifted to a degree depending upon the magnitude of the potentials applied. Undeected, the luminescence produced will be an unsaturated green. If the electrodes 35 be made negative with respects to electrodes 35', the beam will be deflected toward the latter and the resultant color will be yellow; if a reverse potential is applied a blue-green will result. Making electrode 27 negative with respect to electrode 27 results in mixed red and blue, or purple luminescence, whereas opposite deflection will give green. Electrodes 27 and 35 both made negative with respect to the other electrodes in their respective sets will give red luminescence while electrodes 27 and 35' nega tive will give blue.
  • each mesh of the lensgrid defines an area of the display surfaces in which all electrons entering that mesh may be brought into focus and that this area is so divided that one-half is luminescent in one primary color and one-quarter luminescent in each of the two others.
  • the area thus defined is very slightly larger in size than the lens grid mesh and lies directly behind the latter as viewed from the electron gun.
  • the correspondence in size between the meshes and the corresponding subareas of the screen (which may be referred to as phosphor groups or color cells) is not exact nor do the display screen areas lie perpendicularly behind the meshes which converge the electrons upon them except at the center of the screen.
  • the relative positions of any individual mesh and the center of the area of the display screen controlled thereby may be computed.
  • the velocities of the electrons in the beam are proportional to the square roots of the potentials through which they have fallen.
  • the ratio between thetransverse and the longitudinal velocity of the electrons is known, this being the tangent of the angle of deflection.
  • the average longitudinal velocity of the electrons between the lens grid and the display surface is their velocity at the lens-grid plus one-half of the difference between that and their final velocity.
  • the displacement of the point of impact of the mean-path electron from the base of the perpendicular dropped from the center of the mesh to the display surface will therefore be defined by an angle whose tangent is the transverse velocity over the mean velocity between the lens grid and the display surface; the distancev between the plane of the lens grid and the display surface being known, this defines the center of the area controlled by the individual mesh in question; the positions of the centers being defined and being also arranged in a regular quadrilateral array or repeating pattern, this establishes the areas themselves.
  • the velocity of electrons arriving at the lens grid is determined solely by the difference of potential between the latter and the cathode.
  • the longitudinal component of this velocity is proportional to the cosine and the transverse component proportional to the sine of the angle between the path of the electron and the perpendicular to the lens-grid at the lensgrid itself.
  • the velocity of the mean path electron as it reaches the display screen surface will again depend wholly upon the potential difference between the screen and the cathode, but the potential gradient between the lens grid and the screen will add velocity to the longitudinal component only; the transverse component will be unaffected.
  • a tube of the character here described is to be operated to reproduce television images in substantially natural or true colors, with equal color fidelity throughout the screen
  • the centers of the color cells or phosphor groups must be electro-optically alined with the grid meshes which control them, and the electron beam as it passes through any individual mesh must be converged to such an extent that it may be so deflected as to fall on one phosphor only of the three comprising the group.
  • the target structure must be designed so as to aline the grid apertures and their corresponding color cells for the degree of focusing desired. ln order to make such tubes commercially feasible the arrangements should be such that some degree of tolerance in spot size and focusing potentials is allowed for, even when it is desirable to use a focal spot of the maximum permissible size. What the factors are which control the positioning of the phosphor cells and the apertures will be considered in detail herein* after.
  • the illustration is of only a small portion at the center of the screen.
  • the phosphors are disposed in strips 45B, 45ex and 45B, indicating strips of red, green, and blue respectively arranged in the order red, green, blue, green, red, etc., two green strips being included for each one of the two other colors.
  • the strips forming the screen in this case are parallel or very nearly so, as shown the strips are all of equal width, but this is not a necessary feature.
  • Linear conductors for example, the wires 47 and 47 extend across the screen in a direction generally parallel to the direction of the strips, the wires 47 being centered in front of the red strips 45a and the wires 47 similarly centered above the blue strips 45B at the center of the screen depicted in Fig. 3. this geometrical positioning no longer obtains, owing to the curvature of the electron trajectories as described above and to be considered more fully hereinafter.
  • the apertures and the color cells are, however, effectively electro-optically alined throughout the target.
  • the electrodes 47 correspond in connection to electrodes 27 of Fig. l, while electrodes 47 correspond to electrodes 27.
  • the similarly designated electrodes are electrically connected and deflecting potentials are applied from the horizontal color control oscillator 33, it being recognized that the electrodes may run either horizontally or vertically and that horizontal is in this case only specified as a matter of convenience, although there are certain advantages in having the color strips and electrodes vertical upon the screen and effecting the color control by horizontal deflection, and in the discussion it will be assumed that this is the case.
  • Equation l reduces to Ay K n ya 1+ ⁇ /1+A
  • the width W of the spot is equal to 1.)
  • M y 1+ ya y0 being a negative quantity. If W is negative the spot is overfocused, the focal point being between the grid and screen, the beam diverging after it passes through focus. If
  • W should theoretically be zero, and the spot a geometrical line without width.
  • Curve 49 of Fig. 4 is a graphical representation of Equation 3, and curve Slof the same figure shows the size of spot obtained as measured on an actual tube, with values of K ranging from zero (no post-deflection focusing) to eight. ln this curve the actual spacing between the wires of the grid was 231/3 mils.
  • the upper scale of the ligure is given in terms of the quantity K; in the lower scale the figures represent the relative voltages of screen and grid with respect to cathode, which is K l.
  • lf D is the distance between the screen and the grid
  • d is the displacement of the center of the phosphor group from the base of a perpendicular dropped from the center of the corresponding aperture
  • the relationship given verbally in the broad description of the invention can be expressed by the equation or, using the same notation as was used in discussing focussing
  • the aspect ratio of the screen will be, under present standards, 4:3.
  • the average width of the phosphor groups measured from the center of a red strip to the center of the nearest blue strip, will be about 30 mils, and the maximum angle of deflection, on the diagonal, may be taken as 36.
  • the maximum value of the angle a, parallel to the grid wires will be approximately 231/2 while the maximum component normal to the grid wires, will be 30.2 approximately.
  • the number of phosphor groups or color cells will be 479, formed between 480 grid wires.
  • K 0; i. e., where no post-deflection focusing is employed.
  • the quantity 11 tan is, of course, directly proportional to the lateral dimension of the screen.
  • the displacement d is equal to the combined widths of several phosphor groups; 5.4 such groups on the horizontal axis of the screen and 5% such groups at the upper and lower edges.
  • the displacement also differs from the displacement required under the similar triangle law by from 31/3 to 3.51 phosphor groups at axis and corners of the screen respectively.
  • FIG. 5 the diagram of Fig. 5, whereon is shown an electron trajectory between grid and screen, using the same voltage ratio K that was assumed in plotting the curves of Fig. 6 that have so far been discussed.
  • the broken line G indicates the plane of the grid, and the solid line S that of the screen.
  • the small circles 47, 47 indicate the conductors so numbered in Fig. 3.
  • the slope of line 66 is inversely proportional to the average velocity of the electrons between grid and screen.
  • the curved portion of the solid line 63 indicates the parabolic trajectory of the electron between the grid and the screen.
  • the short dashes across the line S indicate the edges yof the color cells. The drawing is approximately to scale and indicates clearly how far the electrons would miss the color cells upon which they were intended to impinge if the screen were so dimensioned that the respective color cells lay either directly behind the centers of the apertures or followed the similar-triangle law.
  • the ratio of the spacings between the centers of the phosphor groups and the centers of the corresponding apertures should be always greater than unity and less than the ratio of the distances from the center of deflection of the beam to the screen and the grid respectively if the phosphor groups and the apertures are to be substantially electro-optically alined; i. e., if a converging beam through the aperture is to fall entirely within the limits of a single phosphor, emissive of the same color, when it is directed to any part of the screen.
  • Fig. 6 The curves of Fig. 6 are drawn for both greater maximum angles of scanning deilection and a greater gridto-scre'en spacing than are satisfactory for use with a constant ratio of grid wire pitch to phosphor group Y width.
  • Either the wire pitch or the phosphor group spacing may be varied either continuously, in order to provide substantially perfect correction, or in zones to apply corrections which are completely adequate in a practical tube and which do not involve errors greater than those inevitable in Acommercial manufacture.
  • the zone construction is preferred, since the changes in pitch as between adjacent apertures or phosphor groups are extremely minute-a fraction of a millionth of an inch on the average-and it is much more practical to make the corrections when they have become cumulatively of appreciable value.
  • the 14% inch sc reen in the tube described is only 324 mils wider than the corresponding grid on the central axis of the screen and only 310 mils wider at the top and bottom, a difference of only 14 mils as between center and edges.
  • the total differ.- ence in screen and grid dimensions is only 2%%.
  • the widthof'the color cells is 30 mils
  • the corresponding wire pitch is 29.325 mils, a difference of very slightly over 2/3 mil.
  • the ratio of the spacing should be such that the phosphor groups are about 2.44 percent wider than the grid wire spacing ⁇ at the center and about 1% percent wider at the corners of the field.
  • Either curve 53 or 55 can be approximated by no more than three straight lines without involving an error of more than l mil at any part of the field, a maximum If errors of as much as 10% can be tolerated, the same spacing ratio may be used at the center and edges of the field. Where only this first order correction is employed the correct spacing ratio may be approximated by the use of straight grid wires and strictly parallel and straight phosphor strips. The displacements necessary for such an approximation may be derived from a curve drawn midway between curves 53 and 55. Preferably, however, a second order correction is applied.
  • the first order correction of phosphor-width to gridwire-pitch ratio can be made in two Ways; the Width of the phosphor groups may be varied while the grid pitch is kept constant throughout the width of the screen or the pitch of the grid wires may be varied while the width of the phosphor groups is maintained constant.
  • the Width of the phosphor groups may be varied while the grid pitch is kept constant throughout the width of the screen or the pitch of the grid wires may be varied while the width of the phosphor groups is maintained constant.
  • the curve 55 indicating the relative displacement of the grid apertures and the phosphor groups
  • the curve may be approximated by two or more straight lines; it is seldom necessary to use more than three.
  • the wires are positioned by bars of glass or like material which are accurately notched and are mounted at the edges of the screen, one on each side of the viewing area. The wires are stretched across these bars and are positioned by the notches therein. All of the notches can be made simultaneously with an array of accurately spaced cutters mounted on a single shaft, and since the accuracy may be built into the cutters the actual formation of the notches becomes a simple and inexpensive process.
  • the error in the tube used for illustration may be made less than one mil at any position along the upper and lower edges of the screen.
  • the screen may be laid out to a very large scale with the widths of the phosphor groups Varied in the inverse manner; the width of the phosphor groups will be greatest in the central portion of the screen with zones of successively decreasing width as the edges of the screen are approached.
  • the design thus constructed may be then reduced photographically to proper size and silk screen stencils or other printing devices made therefrom. If the particular service in which the tube is to be employed will permit a compromise in which only the first order correction is necessary it is obvious that a curve intermediate curve S3 and 55 can be constructed in the same manner to determine grid pitch or phosphor group spacing as the case may be.
  • the second order correction can also be applied in two different ways, irrespective of the method employed in the rst order of correction.
  • One way which has proved very satisfactory in practice is to make a gelatin print of the screen pattern, mount this print in a frame, the sides of which may be bowed outwardly, and stretch the frame and the gelatin print by the necessary 14 mils (in the present case) to accomplish the second order correction.
  • the gelatin print can then be rephotographed, while stretched, and the resulting negative used as a master from which any desired number of duplicates may be formed.
  • the second order correction can be applied to the grid, whether or not the first order correction was so applied.
  • damp rods of undulatory form which may be used to prevent vibration of the grid wires under the electro-static forces set up by the color-switching process.
  • damp rods may be preformed, as shown in the application mentioned.
  • the undulations in the damp rods, passing under and over alternate grid wires, serve to position these wires laterally and by forming the damp rods with the correct pitches for Various zones, longitudinally of the Wires, the grid as a whole can be pulled into a slightly pin-cushion form which will give the desired correction.
  • the displacement d is proportional to the component of velocity imparted to the beam by the scanning deilection, measured in the direction of that component of velocity, multiplied by the electron transit time between the plane of the grid and the plane of the screen.
  • the focusing effect can be computed in accordance with the same general method employed in the case of a single grid, but this can only be done with a degree of accuracy which approximates that obtainable in a single grid if the two grids either lie so close together that they may be treated as if they lay in a single plane and Equation l modied by multiplying the right-hand terrn by 1/2 may be applied to give nearly correct results or if they are separated by a distance which is large in comparison to the separation of the grid wires, so that each grid, when viewed from the other, can be treated as if it were an equi-potential surface.
  • the fields between the wires of the two grids are sutilciently warped to introduce inaccuracies which are greater than those obtained with the focusing formula given in Equation 1, supra.
  • J and K are respectively the ratio of the intergrid voltage kand of the second-grid-toscreen voltage to the voltage between the cathode and the irst grid; C is the distance between grids and D' is the distance from the ⁇ second grid to the screen.
  • the angle a, measured parallel to the electrodes of the first grid is of course transverse to those of the second.
  • the minimum-size spot is obtained when the quantity on the left of each of these equations becomes -lg when C becomes small as compared to the pitch of the grid electrodes the assumptionof uniform eld between the two grids, on which the focusing equations are based, is no longer valid.
  • J approaches zero
  • K approaches 8 for a spot of minimum size at the center of the field.
  • the displacement d under these circumstances is represented by curve 67 of Fig. 6.
  • the spacing D' from second grid to screen is 360 mils and the inter-grid spacing 80 mils, the pitch of both grids being substantially equal and approximately 30 mils. With the proper focusing voltages this gives a substantially square spot.
  • the pattern of Fig. 2 possesses the unusual character- 1 istie that it permits the display of saturated colors even where the dimensions of the spot are equal to those of the aperture, provided the deflection of the beam is correct to centerthespot on the proper color phosphor. As a result it permits of a large latitude in the choice of the degree of post-deection focusing to be used,-par ticularly when employed with multi-gun tubes where the factor of rcolor-deiiection sensitivity does not enter; In
  • the degree of focusing desirable with double-grid tubes using a phosphor pattern of the type illustra-ted in Fig. 2 depends in some degree on the system by which color information is transmitted. 'Single-gun' tubes us-ing this type of pattern may be used with the NTSC system without breaking up the substantially :continuously Atransmit-V ted -color information into dot-sequential form.
  • the .pattern of Fig. 2 the transition from any color to any other .can be made direc-tly as it is unnecessary 'to traverse the green strip, for example, ⁇ in passing from red to blue and the electrodes .can be so biased that when no color deflection is applied Ithe resultant light is a pure white.
  • the color displayed then depends on the direction of deflection and the saturation on its amplitude.
  • a cathode-ray tulbe for displaying television images in color including means for directing ya iiow of electrons against a target area across which they are adapted to be defiected ⁇ in two dimensions from -a center of defiection to trace a raster defining a field of view;
  • Ia target insaid area comprising a display screen including a base, phosphors emissive on electron impact of light of different componen-t colors additive to produce white light disposed over substantially 4the entire area of said base in a repeating pattern composed of groups of all of said phosphors, the area covered by each group being in at least one dimension of the order of magnitude of one elemental area of the television 4image to be reproduced and an Aelectron permeable conducting layer covering said phosphors; an electrode structure mounted adjacen-t and substantially parallel to said screen, 'and terminals for applying different electrical potentials to vsaid conducting layer and said electrode structure, respectively, said electrode structure having :apertures
  • a cathode-ray tube for displaying television images in color including means for directing a flow of electrons against a target area across which they are adapted to'be deflected in two dimensions from a center of deflection to trace la raster defining
  • any three successive strips comprises a group including all of said phosphors the width of which is of the order of magnitude of one elemental area of the television images to lbe re-.
  • tors mounted adjacent and substantially parallel yto said screen with the conductors .thereof crossing said screen in the same direction as said phosphorstrips and defining therebetween a multiplicity of apertures through which 4said electron flow may be directed to corresponding single groups of said strips, the ratio of the widths of the groups of three strips to the widths of the corre sponding apertures being greater at the longitudinal centers'of the groups of strips than lat the ends thereof.
  • each adjacent pair of said linear conductors is uniformly spaced throughout its length and said groups of phosphor strips are wider attheir centers than at the ends thereof.
  • a cathode-ray tube for displaying television images in color-including means for directing a ow of electrons against a target area across which lthey are adapted to be defiected in two dimensions from a center of deflection to trace a raster defining a field of view;
  • a target in said area comprising a display screen including a base, phosphors emissive on electron impact of light of different component colors additive to produce white light disposed over substantially the entire area of said base in a repeating pattern composed of groups of all of said phosphors, the area covered by each group vbeing in at least one dimension of the order -of magnitude of one elemental area of the television image to be reproduced and an electron permeabley conducting layer covering said phosphors; an electrode structure mounted adjacent and substantially parallel to said screen, and terminals for applying different electrical potentials to said conducting' constant, and the ra-tio of aperture spacing to group spac-v ing increasing from yzone to Zone -outwardly
  • a cathode-ray tube for displaying television im-f ages in color including means for directing a flow of elec trons against a target area across which they are adapted y to be deflected in two dimensions from a center of deflection to trace a raster defining a field of view, a display screen disposed in said target area comprising a base,
  • phosphors emissive on electron impact of light of dif' ferent component colors additive to produce white light disposed on said base, and an electron permeable conducting layer covering said phosphors, said phosphors being disposed over substantially the entirearea ⁇ of said base in a repeating pattern composed of groups of all of said phosphors, the area covered by each group being, in at least one dimension, of the order of magnitude of one elemental area of the television image to be r reproduced, an electrode structure mounted adjacentand substantially parallel to said screen, and terminals 'for applying different electrical potentials to said electrode structure and said conducting layer respectively, said electrode structure being apertured to define the pupils of a l multiplicity of electron lenses through each of which electrons of said iiow can be focused on a single one of said groups of phosphors, the ratio of'the spacings between the centers of said apertures and the centers of the respective groups of phosphors on which electrons of said iiow entering said apertures impinge being less than unity and greater than the ratio of
  • a cathode-ray tube for displaying television images in color including means for directing a flow of electrons against a target area across which they Vare adapted to be deflected in two dimensions from a center of deflection to trace a raster defining a eld of View, ai display screen disposed in said target area comprising a v base, phosphors emissive on electron impact of light of different component colors additive to produce white light disposed on said base, and an electron permeable conducting layer covering said phosphors, said phosphors ⁇ being disposed over substantially the entire area of said base in a repeating pattern composed of.
  • the electrode structure being apertured to define the pupils of a multiplicity of electron lenses through each of ywhich electrons of said ow can be focused on a single one of said groups of phosphors, the ratio of the spacings between the centers of said apertures and the centers of the respective groups of phosphors on which electrons of said flow entering said apertures impinge being less than unity and greater than the ratioy of the distance from said center of deflection to said grid to the distance from said center of deliection to said screen, said ratio of spacings being greater adjacent to the edges of said screen than at the center thereof.
  • a cathode-ray tube for displaying television images in color, including an electron gun for directing a beam of cathode rays against a target area across which yit is adapted to be deflected in two dimensions from aJ including phosphors emissive of all of said component colors being of the order-'of magnitude of one elemental area of the television images to be reproduced, a grid of elongated linear electrodes mounted in a plane substantially'parallel to said screen and adjacent thereto, and com prising two interleaved and mutually insulated sets, terminals for applying different electrical potentials to the electrodesy of said two sets and to said conductingV layer,
  • theV ratio of the spacings between thel electrodes of said j two sets tothe spacings of the centers of said. groups being less than unity and greater than the ratio of the distance between the center of deflection of said beam and said grid to the distance from said center ofA delico. tion to said screen.
  • color including an electron gunfor-directing a beam of cathode rays against a target area across which it is adapted to be deflected in two dimensions from a center ⁇ of deflection, to trace a raster denin'g a fieldl of View, a display screen disposed in said targetxarea comprising abase, strips of phosphors emissive on electron impact of light of different component colors additive to produce white deposited on said base in a cyclic order, and an electron permeable'conducting layer deposited over said phosphor strips, the width of each group of strips including phosphors emissive of all of said component colors being of the order of magnitude of one elemental area of the television images to be reproduced, and each group of strips being wider at the center than at'the ends thereof, a grid of elongated linear electrodes mounted in a plane substantially parallel to said screenV and adjacent thereto, and terminals for applying different electrical potentials to said conducting layer and said grid, the ratio of the spacing of
  • a cathode-ray tube for displaying television imagesin color
  • an electron gun for directing a beam of cathode-rays against a target area across which said beam is adapted to be deected in two dimensions from a center of deilection to vtrace a raster defining a field of view
  • a substantially plane display screen disposed in said area, said screen comprising a base, strips of phosphors emissive on electron impact of light of different component colors additive to produce white light disposed on said base in a cyclic order and an electron.- permeable conducting layervdeposited over said phosphorv strips, the width of each group of strips including phosphors emissive of all of saidY component colors being of the order of magnitude of one elemental area of the television images to be reproduced, a grid of elongated linearl electrodes mounted adjacent to said screen in a plane substantially parallel to the plane thereof, said electrodes being oriented with their length in directions generally parallel to the length of said strips, and terminals for applying different
  • a cathode-ray tube fordisplaying television images in color
  • an electron gun for directing a beam of cathode raysl against a target areaacrosgsgwhieh said beam is adapted to be detiected in two dimensions from a center of deflection to trace a raster defining a eld of view, a substantially plane display screen disposed-fili ⁇ said area, said screen comprising a base, strips of phonphors emissive-on electron impact of; light of.
  • dierent component colors additive to produce ⁇ white light vdisposed on said base in a cyclic order and an electron-permeable, conducting layer deposited over said phosphor strips,xthe width of each group of strips including phosphors emissive of all of said component colors beingv ofY the order cimesnitude ofone elemental area of the television imagestoby reproduced, a grid of elongated linear electrodesJ mountedadjacent to said screen in a plane substantially parallel t0 the plane thereof, andterminals for applying diierent pov; tentials tosaid conducting layer and to said grid, said elec.- trodes being oriented in directions generally.y parallel to the length of said strips, the spacing of said electrodes being uniform at the midpointof the length of said elec!
  • a cathode-.ray tube for displaying television im.- ages in color including an electron gunforv directing a beam of cathode rays against a target area across, which said beam is adapted to be deflected in two dimensions from a center of deection to trace araster deninga leld of view, a substantially plane display screen disposed in said area, said screen comprising a base, stripsof phosphors emissive on electron impact of lightof different component colors additive to produce white light disposed on said base in a cyclic order andan electron-permeable conducting layer.
  • each group of strips including phosphors emis.v sive of all lof said component colors being of the order of magnitude ofl one elemental area ofthe television imf ages to be reproduced, allof saidV groups having the same.
  • a cathode-ray tubeL for displaying television i111-,v ages in color including means for directing a owofekC- trons against a target area across which they are adaptedv to be deflected in two dimensions from a center'of' der ilectionv totrace a raster defining a ieldvof view, ⁇ a display screen .disposed in 'said target area comprising a bum phosphors emissive on ⁇ electron.
  • an electrode structure mount ed adjacent'and substantially parallel to said screen, and' salcl flow entering said apertures impinge being uniform throughout said target area and less than unity and greater than the ratio of the distance from said center of deflection to said electrode structure to the distance from said center of deection to said screen.
  • a cathode-ray tube for displaying television images in color, including an electron gun for directing a beam of cathode rays against a target area across which it is adapted to be deected in two dimensions from a center of deection to trace a raster dening a field of View, a display screen disposed in said target area comprising a base, and strips of phosphors emissive on electron impact of light of diierent component colors additive to produce white deposited on said base in a cyclic order, the width of each group of strips including phosphors emissive of all of said component colors being of the order of magnitude of one elemental area of the television images to be reproduced, an electron permeable conducting layer deposited over said phosphor strips, a grid of elongated linear electrodes mounted in a plane substantially parallel to said screen and adjacent thereto, and terminals for applying diierent electrical potentials to said conducting layer and said grid, the ratio of the spacing of the electrodes comprising said grid to the spacing between the centers
  • a cathode-ray tube for displaying television images in color, including means for directing a ow of electrons against a target area across which they are adapted to be deflected in two dimensions from a center of deection to trace a raster defining a substantially rectangular field of view, a display screen disposed in said target area comprising a base, phosphors emissive on electron impact of light of different component colors additive to produce white light disposed on said base in a repeating pattern composed of groups of all of said phosphors, the dimensions of each of said groups being in one dimension at least of the order of magnitude of one elemental area of the ltelevision image to be reproduced and said pattern covering substantially the entire area of said eld of View, an electrode structure mounted adjacent to said base and symmetrically disposed with respect thereto and equidistant from the corners of said raster and having apertures therein defining the pupils of a multiplicity of electron lenses through each of which said electron ow can be focused on a single one

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US399754A 1953-12-22 1953-12-22 Color television tube target structure Expired - Lifetime US2745035A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL193468D NL193468A (en(2012)) 1953-12-22
BE534345D BE534345A (en(2012)) 1953-12-22
US399754A US2745035A (en) 1953-12-22 1953-12-22 Color television tube target structure
DEC10457A DE1080595B (de) 1953-12-22 1954-12-21 Kathodenstrahlroehre zur Wiedergabe von Farbfernsehbildern
FR1117283D FR1117283A (fr) 1953-12-22 1954-12-22 Anticathode pour tube de télévision en couleurs
GB37000/54A GB773339A (en) 1953-12-22 1954-12-22 Improvements in or relating to target structures for use in colour television tubes

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US399754A US2745035A (en) 1953-12-22 1953-12-22 Color television tube target structure

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US2745035A true US2745035A (en) 1956-05-08

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BE (1) BE534345A (en(2012))
DE (1) DE1080595B (en(2012))
FR (1) FR1117283A (en(2012))
GB (1) GB773339A (en(2012))
NL (1) NL193468A (en(2012))

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2925532A (en) * 1955-12-01 1960-02-16 Rca Corp Polychromatic electroluminescent means
US2945974A (en) * 1957-01-14 1960-07-19 Kaiser Ind Corp Electronic device
US3237038A (en) * 1963-10-14 1966-02-22 Rca Corp Screen electrode for color cathode ray tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2260853A (en) * 1991-10-22 1993-04-28 Gec Ferranti Defence Syst Colour display screens
CN1459203A (zh) 2001-03-09 2003-11-26 皇家菲利浦电子有限公司 指示型图像显示器件

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US866065A (en) * 1906-06-25 1907-09-17 Albert Priestman Apparatus for controlling the flow of liquids.
US2532511A (en) * 1946-11-16 1950-12-05 Okolicsanyi Ferene Television
US2631259A (en) * 1950-07-12 1953-03-10 Rca Corp Color television

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE736575C (de) * 1938-07-11 1943-06-22 Fernseh Gmbh Kathodenstrahlroehre zur Erzeugung mehrfarbiger Bilder auf einem Leuchtschirm
US2446791A (en) * 1946-06-11 1948-08-10 Rca Corp Color television tube
US2568448A (en) * 1947-09-23 1951-09-18 Gen Electric Parallax correction in color television

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US866065A (en) * 1906-06-25 1907-09-17 Albert Priestman Apparatus for controlling the flow of liquids.
US2532511A (en) * 1946-11-16 1950-12-05 Okolicsanyi Ferene Television
US2631259A (en) * 1950-07-12 1953-03-10 Rca Corp Color television

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2925532A (en) * 1955-12-01 1960-02-16 Rca Corp Polychromatic electroluminescent means
US2945974A (en) * 1957-01-14 1960-07-19 Kaiser Ind Corp Electronic device
US3237038A (en) * 1963-10-14 1966-02-22 Rca Corp Screen electrode for color cathode ray tube

Also Published As

Publication number Publication date
DE1080595B (de) 1960-04-28
FR1117283A (fr) 1956-05-22
GB773339A (en) 1957-04-24
NL193468A (en(2012))
BE534345A (en(2012))

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