US2811661A - Target structure for color television display tubes - Google Patents

Target structure for color television display tubes Download PDF

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Publication number
US2811661A
US2811661A US462698A US46269854A US2811661A US 2811661 A US2811661 A US 2811661A US 462698 A US462698 A US 462698A US 46269854 A US46269854 A US 46269854A US 2811661 A US2811661 A US 2811661A
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United States
Prior art keywords
grid
screen
deflection
center
tube
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Expired - Lifetime
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US462698A
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English (en)
Inventor
Edwin M Mcmillan
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Chromatic Television Laboratories Inc
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Chromatic Television Laboratories Inc
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Priority to NL200852D priority Critical patent/NL200852A/xx
Application filed by Chromatic Television Laboratories Inc filed Critical Chromatic Television Laboratories Inc
Priority to US462698A priority patent/US2811661A/en
Priority to GB28450/55A priority patent/GB814298A/en
Application granted granted Critical
Publication of US2811661A publication Critical patent/US2811661A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H04N9/22—Picture reproducers using cathode ray tubes using the same beam for more than one primary colour information
    • H04N9/26—Picture reproducers using cathode ray tubes using the same beam for more than one primary colour information using electron-optical colour selection means, e.g. line grid, deflection means in or near the gun or near the phosphor screen

Definitions

  • This invention relates to target structures for use in cathode-ray tubes for the display of television images in color, .which utilize post-deflection focusing to concenltrate an electron beam on a phosphor whichis emissive of a single color. Particularly it relates to .structures wherein the electronlenses utilized to focus the beam are the analogsof cylindrical optical lenses, and comprise a single .grid of closely spaced, parallel, linear conductors, tightly stretched and mounted adjacent to the display screen, in combination with a conducting coating on the surface of .the screen.
  • tubes of this character a plurality of ditterentphosphors are employed, respectively emissive of different colored light, on impact by the electron stream, the colors being components which additively produce White.
  • the phosphors are disposed in strips extending across the surface of the display screen, generally parallel to the direction of the electrodes of the lens-grid.
  • the component colors emitted by the phospors will ordiinarily'be red, green, and blue, and a group of strips, in-
  • the electrons constituting the beam are accelerated during their passage between grid and screen, their paths in this region are curved toward the axis'of the "tube and'the phosphor groups are therefore not geometrically alined with the center of deflection of thebeam as it'sc'ans "the screen surface.
  • the amount of deviation of'the beam from its rectilinear course increases with its scanning deflection, and this deviation does not increase linearly with either the angle of scanning deflection or 'its'tangent, the latter being proportional to the distance from the center of the grid to the point'of penetration thereof by the electron beam.
  • conductors of the lens-grid are divided into .two interleaved groups, electrically insulated, so thatwhen elec- .trical potentials are applied betweenthe conductors of the two groups the beam is deflected toward the more positive electrode and directed to a phosphor :whichis electro-optically-alined with the more positive of the-two electrodes.
  • the present invention attains its greatest value in tubes of the micro-deflection type, although it is not necessarily limited thereto.
  • the broad purpose of thepresent invention is to provide a target structure utilizing two-element electron lenses, in which the variations in the electro-optical parameters which affect the performance of a tube of this character are minimized, so that'the tube may be operated throughout substantially its full theoretical duty cycle, giving full brilliancy and high operative effectiveness, without employing additional and expensive compensating means to overcome the aberrations of the system.
  • Another objects of the invention are to provide a structure Wherein the highly eflicient type of color-control grid utilizing tautly stretched wires can be used; to provide a type of target structure wherein the display screen may be deposited directly upon the tube face or window; to provide a device whose construction requires no complex mechanical features and wherein the grid structure can be constructed and positioned in the same general fashion as in the case .of planar grids and screens, utilizing 'only relatively slight modifications; and to provide a type of display tube which has advantages'both Yin lightness, economy of manufacture, and ease of construction over tubes heretofore used.
  • the target structure of the present invention comprises the combination, in a cathode-ray tube which is otherwise of substantially conventional construction, of a lens grid of substantially circular,
  • the lens-grid is composed of tautly stretched, linear conductors, preferably fine
  • the wires are parallel, substantially uniformly spaced, and form elements of the cylindrical surface dcfined by the grid, their spacing being of the order of magnitude of one elemental area of the television image to be reproduced by the tube.
  • the display screen comprises strips of a'pluralityofdiiferent phosphors, preferably three, which are emissive, upon electron impact, of light of three component colors which additively pro prise white.
  • the phosphor strips are disposed in groups or colorcells, each of which comprises all of the .phosphors, one such cell being electro-optically alined with each interspace between an adjacent pairof wires.
  • colorcells each of which comprises all of the .phosphors, one such cell being electro-optically alined with each interspace between an adjacent pairof wires.
  • Fig. l is a semi-schematic, axial sectional view in plan of a television display tube embodying the invention, the plane of section being normal to the axis of the cylindrical grid structure;
  • Fig. 2 is a sectional view through the front end of the tube of Fig. l, the plane of section being parallei to the axis of the grid;
  • Fig. 3 is an isometric diagram of one form of frame for supporting a cylindrical grid structure
  • Fig. 4 is a fragmentary elevational view of the grid structure, the direction of view being parallel to the cylinder axis.
  • Fig. 5 is a fragmentary cross-section of the grid structure, taken on the plane 55 of Fig. 4, illustrating the means of supporting and connecting to the grid conductors.
  • Fig. 6 is a fragmentary elevation of the target structure, showing the relationship between the grid conductors and the phosphor pattern at the center of the screen;
  • Fig. 7 is a fragmentary cross-sectional view through the target, further showing the relationship between the grid conductors and the phosphor pattern.
  • Fig. 1 illustrates, diagrammatically, and in exaggerated form, a cathode-ray display tube embodying the present invention.
  • the tube is conventional in construction with the exception of the grid and screen structure, and it comprises evacuated envelope 1, having a generally funnel-shaped body, and an electron gun 3 mounted in the neck of the funnel.
  • the electron gun may be of any conventional type, embodying a cathode, a control grid, and one or more anodes, adapted to direct a concentrated beam of electrons axially toward the larger end of the envelope.
  • a base 5 includes plug connections for the various electrodes within the electron gun.
  • the beam is deflected from its axial path about a center of deflection or virtual source 7, to scan the target which forms the novel feature of the present invention.
  • the deflection of the beam may be accomplished by a deflecting yoke mounted to encircle the neck of the tube or it may be accomplished by pairs of deflecting plates within the tube; these equivalents being well understood and the means for accomplishing the deflection not being a part of the present invention are not here shown.
  • a face plate or window 9 forms the larger end of the envelope.
  • the body of the envelope 1 may be either of metal or of glass.
  • the face plate or window 9 is made separately and is connected to the body of the tube at a seal 11 which encircles the envelope. Included in the seal or supported thereby is a ring 12 to which the grid structure next to be described is secured.
  • the grid comprises a rigid frame across which are strung two interleaved sets of tightly stretched linear conductors, in practice, most conveniently fine wires.
  • the frame in this case comprises a pairof angles, 13, of structurally strong material.
  • One web 13' at each end of each angle is bent at right angles, to form an abutment against which an insulating endbeam rests, supported by the unbent web, as illustrated in Figs. 3 and 4.
  • the end-beam 15 may be formed of glass or ceramic. It is rectangular in cross-section, one face, that which rests against the webs of the angles 13, is preferably straight, while the other edge, to the right as illustrated in Fig. 4, is a substantially circular arc.
  • This surface is provided with notches 14 at substantially uniform intervals, these notches serving to position the grid Wires.
  • the end beams 15 are secured to the angle members 13 by bolts 16, which may also be used to attach the grid to the support ring 12.
  • the notches and wires are indicated symbolically, only a few being shown; in an actual tube the grid will comprise 500 or more conductors.
  • the linear conductors which form the grid are positioned by hooks in a manner best illustrated in Figs. 4 and 5.
  • Two sets of these hooks are used on each of the beams 15.
  • the hooks depend at right angles from continuous strips.
  • One of these strips 17, from which the hooks 17 depend is clamped between the web 13' and the beam 15, with the hooks extending under the lefthand surface of the beam as illustrated in Fig. 5.
  • the continuous strip 19 of the other set lies at the left of the beam, with the hooks extending above it, as shown in this same figure.
  • the strips 17 and 19 are preferably secured to the beam with insulating cement which reinforces the clamping of the beam to the metal angles 13 insofar as the strip 17 is concerned, and holds the strip 19 in place for winding.
  • a strip of insulation 21 overlies the continuous portion of the strip 19, and may also be temporarily cemented in place.
  • the continuous conductor, in this case a fine wire 23 is then laced around the structure, engaging the hook 17'.
  • the wires are tautly stretched and serve as an additional anchor for the strips 21 and hook strips 19, and the wires being positioned by alternate notches 14.
  • the wires forming a conductor of the second set of grid wires are then laced in place, engaging the hooks 19', these wires passing over the wires of the first set without contact. It may be desirable to interpose additional insulation at the cross-over, or the insulation between the two sets may be accomplished merely by their spacing.
  • the screen used with this particular arrangement is of a type which is now well known. It comprises narrow strips of different phosphors which are emissive, upon electron impact, of light of three component colors which additively produce white.
  • the phosphors are laid down in a repeating pattern, with the phosphor emissive of one color, preferably green, electro-optically centered between each pair of grid wires, as viewed from the center of deflection 7.
  • a strip of phosphor emissive of one of the other colors, say red, is electro-optically centered behind each of the wires 23, with a strip emissive of the third color, say blue, centered elecro-optically behind each of the wires 25.
  • Each pair of wires constitutes an aperture of a cylindrical electron lens.
  • the width of the strips is such that the spacing on centers of the green strips (if the order of the strips is that here described) is equal to or less than the width of one elementary area which is to be resolved in the television image to be displayed upon the tube.
  • the phosphor pattern as laid out in the manner thus described and illustrated fragmentarily in Figs. 6 and 7, is deposited upon the inner surface of the window 9 as indicated by the reference character 27.
  • a film of conducting material preferably aluminum, permeable to the cathode-ray beam which traces the television images presented.
  • the dimensions of the phosphor layer and the conducting film which covers'it aretoo small -to be shownin the sectional views of Figs. 1 and 2; the fragmentaryviews' of Figsi6 and' 7, Fig. 6 illustrating the relationship of the phosphor strips to the. grid electrode at thecenter of the screen where the electro-optical alinement and the geometrical alinement coincide, and the cross-sectional view ofFig. 7, are greatly exaggerated for illustrative purposes.
  • Fig. 7 there is shown the conducting film'35, overlying the phosphor coating.
  • the fragmentary view of Fig. 7 illustrates the position, relatively, of the grid electrodes and'the phosphor strips at the screen center, where geometrical,-optical, electron-optical:positions coincide.
  • the grid wires are maintained at .a potential whichis positive to the cathode of the electron gun',while ,the fi lm35is positive tothe electrodes of the grid.
  • the amount that'the' beam is deflectedfrom its straight-line course'bytitsfocussing action depends both upon the relative potentials of the cathode, "grid, and screen, and its angle and direction of deflection about the center of deflectionindicatedby the point'7in Fig; 1.
  • EquationsZ and 3 show that the variation in size of the focalspot and thesensitivity to deflection both vary most "rapidlyiori deflections parallel to the direction 'of the grid conductors; so"much so,' infact, that in the case of the planar-' grid andrscreen the amount of variation in these quantities is-nearly-twice as great if thegrid conductors? run'parallel to "thelonger; dimension of the-screen as is the case if they run -paralleltothe shorter dimension;
  • the-axis 'of the cylindrical grid is in 'a plane parallel to'theshorter'dimension of the screen.
  • Theradius of curvature of the grid is greater-thanthe distance from the center ofdeflection ot the cathode-ray beam to the grid, in order to avoidexcessive-curvature of theviewin'g surface, but even so; the angle of incidence 0 is greatly decreased, so that the variationiin the three important parameters is not-only reduced but becomes much 'more nearly linear.
  • the screen, to0,-' is preferablymade concave as viewed from the source of the; electron beam, preferably with 'a difierent degree of curvature from that applied to'th'e grid, so that the grid-screen 'dista'nce' 'b'ecomes"less as the sensitivity' to deflection increase'sg an'd 1 the displacement? of the focal spot thus mayb'e heldnearlyconstantp lBest compensation is obtained 'Whenth'e radii'ofcurvature ditfer' in the two dimensions,xbeing-longer in the plane parallel to-theaxis ofthe grid?
  • one method of design is to determine first the parameters of the grid which is to be used, solve the equations for variation in focus and sensitivity, giving the latter in terms of the screen distance D, and finally, through the use of the equations, choose radii of curvature for the screen so that D will vary inversely as its coefiicient in the solutions.
  • the closest approximation to uniformity of deflection sensitivity can be achieved with a screen having a barrelshaped" surface; i. .e., a surface which is generated by rotating an arc of long radius around the axis on a shorter radius.
  • a cylindrical screen maybe applied to obtain the values of the shorter radii in the planes passing through center and the edges of the screen.
  • the longer radius of the screen is that of a circle passing through the ends of these radii.
  • a screen cylindrical or nearly cylindrical in form is more difiicult to manufacture than that employing a spherical surface.
  • a compromise design wherein the sensitivity to deflection is perr'nittedto vary but the variation in focus is held to a minimum.
  • cylindrical grid and wit-h one '8 inch maximum separation between grid and screen will have the following characteristics:
  • Point Refraction Deflection Focusing Correction Center of Screen 0 1 06 Center of Vertical Edge"-.. 10 1.025 04 Center of Horizontal Edge 0 0.71 0. 06 Corner of Screen 0. 076 0.71 06 This is assuming a voltage ratio -ZZ- Z.75.
  • Such a construction leads to a large improvement in variation in focal-spot size as compared to a flat grid and screen.
  • the variation in deflection sensitivity is substantially the same as in the case of the planar grid and screen.
  • the minimum size of spot which can be obtained is approximately 3 mils in width.
  • the variation in sensitivity of deflection may be either greater or less than-with a flat grid, depending upon whetherithe percentage variation in D resulting from the greater distance between grid and screen at'the edges of the structure is greateror less, proportionally, than the variation in angular sensitivity; with relatively large minimum values of D there may; therefore, be improvement in performance even in the case of a fiat screen with the concave grid.
  • a cathode-ray tube for the display of television images in color, comprising an evacuated envelope and an electron gun therein adapted to direct an electron beam against a viewing area at one end thereof over which the beam is adapted to be deflected about a center of deflection to scan said viewing area, a target structure within said viewing area comprising a transparent base having a substantially uniformly curved concave surface facing said electron gun, a grid of tightly stretched linear conductors mounted adjacent to said base, said conductors being disposed along elements of a cylindrical surface having its axis substantially parallel to an axis of symmetry of said concave surface and being mutually spaced by distances of the order of magnitude of one elemental area of the television image to be reproduced, and a display screen deposited on the concave surface of said base and comprising strips of different phosphors respectively emissive on electron impact of light of the component colors of an additive color system and disposed in a repeating pattern of groups, each of which includes at least one strip of each of said said target
  • a cathode-ray tube for the display of television images in color, comprising an evacuated envelope and an electron gun therein adapted to direct an electron beam against a viewing area at one end thereof over which the beam is adapted to be deflected about a center of deflection to scan said viewing area, a target structure within said viewing area comprising atransparent base having a substantially spherically curved concave surface facing said electron gun, a grid oftightlystretchedlinearconductors mounted adjacent-to said base, said conductors being disposed along elements of a cylindrical surface having itsaxissubstantially parallel to'the chord of" said spherical surface and being mutually spaced by distances of the order of magnitude of one elemental area of the televisionimage to be reproduced, and a display screen deposited on the concave surface of said base and comprising strips of'different phosphors respectively emissive on electron impactof light of the component colors of an additive color system and disposed in a repeating'pattern of groups
  • a display tube for television signals including means fordirecting a beam of electrons in a direction substantially normal to a target area over which it is adapted to be deflected bidirectionally to scana raster, target structure Within said area comprising a grid of parallel linear.
  • a display screen mounted adjacent to said grid and comprising a transparent base, strips of phosphors emissive on electron impact of light of different colors additively producing white disposed on said base in a repeating pattern of groups including all of said phosphors, the centerof each group being electro-optically alined with the center of an interspace between adjacent conductors of said grid, and a conductive coating on said phosphors adapted to form with said grid elements of a multiplicity of electron lenses, the phosphorcoated surface of said base being concavely curved with respect to said grid in at least one dimension so that the separation between said grid and screen varies from pointto-point over the surface thereof as an inverse function of the angle of incidence of said beam at said grid when deflected thereto.
  • a display tube for television signals including means for directing a beam of electrons in a direction substantially normal to a target area over which it is adapted to be deflected bidirectionally to scan a raster, target structure within said area comprising a grid of parallel linear conductors disposed in two mutually insulated, interleaved sets and defining a cylindrical surface, connections for applying potential differences between said sets to produce a micro-deflection of electrons passing therebetween, and a display screen mounted adjacent to said grid and comprising a transparent base, strips of phosphors emissive on electron impact of light of different colors additively producing white disposed on said base in a repeating pattern of groups including all of said phosphors, the center of each group being electrooptically alined with the center of an interspace between adjacent conductors of said grid, and a conductive coating on said phosphors adapted to form with said grid elements of a multiplicity of electron lenses,.the phosphorcoated surface of said base being concavely curved
  • a display tube for television signals including means for directing a beam of electrons in a direction substantially normal to a target area over which it is adapted 11 to be deflected bidirectionallyto scan a raster, target structure within said area comprising a grid of parallel linear conductors disposed in two mutually insulated, interleaved sets and defining a cylindrical surface, connectionsfor applying potential diiferences between said sets to produce a micro-deflection of electrons passing therebetween, and a display screen mounted adjacent to said grid and comprising a transparent base, strips of phosphors emissive on electron impact of light of different colors additively producing white disposed on said base in a repeating pattern of groups including all of said phosphors, the center of each group being electro-optically alined with the center of an interspace between adjacent conductors of said grid, and a conductive coating on said phosphors adapted to form with said grid elements of a multiplicity of electron lenses, the phosphor-coated surface of said base being con
  • a cathode-ray tube for displaying television images in color which includes a screen having a repeating pattern of strips of phosphors emissive of different colored light deposited thereon and an electron gun for directing against said screen a beam of electrons adapted to be bidirectionally deflected thereacross about a center of deflection screen, a grid of tightly stretched linear conductors mounted adjacent to said screen, the conductors of said grid being disposed generally parallel to the phosphor strips comprising said pattern and defining a cylindrical surface having an axis more distant from said screen than said center of deflection, said surface being concave as viewed from said electron gun.
  • 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 over which said beam is adapted to be bidirectionally deflected about a center of deflection to trace a raster, a grid of tightly stretched substantially parallel linear conductors disposed in a cylindrical surface mounted in said target area, said surface being concave toward said electron gun and having a radius of curvature greater than the distance of said center of deflection to said grid, and a screen mounted behind said grid in said target area and concave as viewed from said electron gun and comprising a transparent base plate and a repeating pattern of strips of different phosphors deposited thereon, said strips being generally parallel to said linear conductors, said screen being so curved as to be nearer to said grid at the ends of said linear conductors than at the centers thereof.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US462698A 1954-10-18 1954-10-18 Target structure for color television display tubes Expired - Lifetime US2811661A (en)

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NL200852D NL200852A (nl) 1954-10-18
US462698A US2811661A (en) 1954-10-18 1954-10-18 Target structure for color television display tubes
GB28450/55A GB814298A (en) 1954-10-18 1955-10-06 Improvements in or relating to cathode ray tubes

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3516147A (en) * 1967-07-17 1970-06-23 A P Seedorff & Co Inc Method of fabrication of metallic frames

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3166197A (en) * 1963-05-27 1965-01-19 Robert C Caylor Removable attachment for vehicles

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2566713A (en) * 1947-04-04 1951-09-04 Rca Corp Color television
US2606303A (en) * 1951-02-17 1952-08-05 Bramley Jenny Color television tube and process
US2635203A (en) * 1951-01-02 1953-04-14 Rauland Corp Color television tube
USRE23672E (en) * 1946-11-16 1953-06-23 Television tube
US2692532A (en) * 1951-04-04 1954-10-26 Chromatic Television Lab Inc Cathode ray focusing apparatus
US2696571A (en) * 1950-02-10 1954-12-07 Rca Corp Color kinescope

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE23672E (en) * 1946-11-16 1953-06-23 Television tube
US2566713A (en) * 1947-04-04 1951-09-04 Rca Corp Color television
US2696571A (en) * 1950-02-10 1954-12-07 Rca Corp Color kinescope
US2635203A (en) * 1951-01-02 1953-04-14 Rauland Corp Color television tube
US2606303A (en) * 1951-02-17 1952-08-05 Bramley Jenny Color television tube and process
US2692532A (en) * 1951-04-04 1954-10-26 Chromatic Television Lab Inc Cathode ray focusing apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3516147A (en) * 1967-07-17 1970-06-23 A P Seedorff & Co Inc Method of fabrication of metallic frames

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GB814298A (en) 1959-06-03
NL200852A (nl)

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