MXPA98000725A - Catodic color rays tube that has mascarade uniax tension focus - Google Patents

Abstract

The present invention relates to a cathodic ray tube (10) having an evacuated shell (11) with an electron gun (26) therein, to generate at least one electron beam (28). The casing (11) further includes a face plate panel (12) having a luminescent screen (22) with phosphor lines on an inner surface thereof. A uniaxial tension focusing mask (25), having a plurality of separate first metal cords (40) is located adjacent to an effective image area of the screen. The spacing between the first metal cords defines a plurality of slots (42) substantially parallel to the phosphor lines of the screen. Each of the first metal cords through the area of the effective image of the screen has a substantially continuous first insulating layer (64) on a side facing the screen thereof. A second insulating layer (66) is superimposed on the first insulating layer. A plurality of second metal cords (60) are oriented substantially perpendicular to the first metal cords, and are bonded thereto by the second insulating layer. The first insulating layer has a coefficient of thermal expansion that substantially agrees with, or is slightly lower than, that of the first cords. The second insulating layer has a coefficient of thermal expansion that is substantially identical to that of the first layer insulated

Description

TOBO OF COLOR CATHODIC RAYS THAT HAVE UNIAXIAL TENSION FOCUS MASK This invention relates to a color cathode ray tube (CRT), and more particularly, to a color cathode ray tube having a uniaxial tension focusing mask, and to the materials used in the manufacture of this mask.

BACKGROUND OF THE INVENTION A conventional color mask type cathode ray tube generally comprises an evacuated envelope having therein a luminescent screen with phosphor elements of three different emissive colors and configured in color groups in a cyclic order, elements for producing three convergent electron beams directed towards the screen, and a color selection structure, such as a masking plate, between the screen and the beam-producing elements. The masking plate acts as a parallax barrier that shades the screen. The differences in the angles of convergence of the incident electron beams, allow that the transmitted portions of the beams exist to the phosphor elements of the correct emissive color. One drawback of the shadow mask type cathode ray tube is that the masking plate, in the center of the screen, intercepts all but about 18 to 22 percent of the beam current; that is, it is said that the masking plate has a transmission of only about 18 to 22 percent. Accordingly, the area of the openings in the plate is approximately 18 to 22 percent of the area of the masking plate. Since there are no focus fields associated with the masking plate, there is a corresponding portion of the screen by the electron beams. In order to increase the transmission of the color selection electrode without increasing the size of the excited portions of the screen, focus color selection structures are required after the deviation. The focusing characteristics of these structures allow larger openings to be used to obtain greater transmission of the electron beam, than can be obtained with the conventional surplus mask. One of these structures is described in Japanese Patent Publication Number SHO 39-24981, by Sony, published on November 6, 1964. In that patented structure, mutually orthogonal conductor wires are connected at their crossing points by means of insulators, to provide large window openings through which the electron beams pass. A drawback of this structure is that the cross wires offer little protection to the insulators, so that the deflected electron beams will impact and charge the insulators electrostatically. Electrostatically charged insulators will distort the trajectories of the electron beams that pass through the window openings, causing poor registration of the beams with the elements of the phosphor screen. Another drawback of the structure is that the mechanical breaking of an insulator would allow an electrical short between the cross wires of the grid. Another color selection electrode focusing structure that overcomes some of the drawbacks of the above-described Japanese Patent Publication is described in U.S. Patent No. 4,443,499, issued April 17, 1984 to Lipp. The structure described in United States Patent Number 4,443,499 uses a masking plate having a thickness of approximately 0.15 millimeters (6 mils), with a plurality of rectangular openings therethrough, as a first electrode. Metal flanges separate the columns from the openings. The upper parts of the metal flanges are provided with a suitable insulating coating. A metallized coating is superimposed on the insulating coating to form a second electrode that provides the required electron beam that is focused when suitable potentials are applied to the masking plate and the metallized coating. In an alternative way, as described in U.S. Patent No. 4,650,435, issued March 17, 1987 to Tamutus, a metal masking plate, which forms the first electrode, is etched from a surface to provide parallel ditches where deposit the insulating material, and accumulate to form the insulating flanges. The masking plate is further processed by means of a series of photo-exposure, development, and recording steps, to provide openings between the flanges of the insulating material residing on the support plate. The metallization on the upper parts of the insulating flanges forms the second electrode. The two Patents of the United States of America described above eliminate the problem of short circuits between separate conductors, which was a drawback in the previous Japanese structure; however, the masking plates with openings of the Patents of the United States of North America, each have crossed members of a substantial dimension, which reduce the transmission of the electron beam. Additionally, the thickness of the masking plates is such that the deflected electrons will still impact, and electrostatically charge, the flanges of the insulating material. Accordingly, there is a need for a focus mask structure that overcomes the drawbacks of the above structures. One of these focus mask structures is described in pending U.S. Patent Application Serial Number 08 / 509,321 (RCA 87639), filed July 26, 1995, by R. Nosker and collaborators. The structure described in the pending application comprises a plurality of first separate metal cords having a thickness of approximately 0.051 millimeters (2 mils), which extend through an effective image area of the cathode ray tube shields. A first substantially continuous insulating layer, having a thickness approximately equal to that of the first metal cords, is disposed on a side facing the screen thereof. A second insulating layer is provided on the first insulating layer to facilitate the linking of a plurality of second metal cords, substantially perpendicular to the first metal cords, to the first insulating layer. The second insulating layer has a thickness of about half the first insulating layer.

COMPENDIUM OF THE INVENTION The present invention relates to a color cathode ray tube having a shell evacuated with an electron gun thereon, to generate at least one electron beam. The wrapping further includes a face plate panel having a luminescent screen with phosphor lines on an internal surface thereof. A uniaxial tension focusing mask, having a plurality of separate first metal cords, is located adjacent to an effective image area of the screen. The spacing between the first metal cords defines a plurality of grooves substantially parallel to the phosphor lines of the screen. Each of the first metal cords, through the effective image area of the screen has a first insulating layer substantially continuous on a side facing the screen thereof. A second insulating layer is superimposed on the first insulating layer. A plurality of second metal cords are oriented substantially perpendicular to the first metal cords, and are bonded thereto by the second insulating layer. The first insulating layer has a coefficient of thermal expansion substantially equal to or less than that of the first metal cords. The second insulating layer has a coefficient of thermal expansion that is substantially identical to that of the first insulating layer.

BRIEF DESCRIPTION OF THE DRAWINGS Now the invention will be described in greater detail, with reference to the accompanying drawings, in which: Figure 1 (Page 1) is a plan view, partially in axial section, of a cathode ray tube color that incorporates the invention. Figure 2 (Page 2) is a plan view of a uniaxial tension frame-mask assembly used in the cathode ray tube of Figure 1. Figure 3 (Page 2) is a front view of the assembly. of frame-mask taken along line 3-3 of Figure 2. Figure 4 (Page 3) is an amplified section of the uniaxial tension focusing mask shown within circle 4 of Figure 2. Figure 5 (page 3) is a section of the uniaxial voltage focusing mask and the luminescent screen, taken along lines 5-5 of Figure 4. Figure 6 (page 2) is an amplified view of a portion of the uniaxial voltage focusing mask within the circle 6 of Figure 5. Figure 7 (Page 3) is an amplified view of another portion of the uniaxial voltage focusing mask within the circle 7 of Figure 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 shows a color cathode ray tube 10 having a glass envelope 11 comprising a rectangular face plate panel 12 and a tubular neck 14 connected by a rectangular funnel 15. The funnel has an internal conductive coating (not shown) that is in contact with, and extends from, a first anode button 16, to the neck 14. A second anode button 17, located opposite the first anode button 16, is not contact with the conductive coating. The panel 12 comprises a cylindrical face plate 18, and a peripheral flange or side wall 20 which is sealed to the funnel 15 by a glass frit 21. A three-color luminescent phosphor screen 22, is carried by the surface internal of the face plate 18. The screen 22 is a line screen, shown in detail in Figure 5, which includes a multiplicity of screen elements comprised of red emitting phosphor lines, green emitters, and blue emitters , R, G, and B, respectively, configured in triads, including each triad a line of phosphorus of each of the three colors. Preferably, a light absorbing matrix 23 separates the phosphor lines. A thin conductive layer 24, preferably of aluminum, is superimposed on the screen 22, and provides an element for applying a first uniform anode potential to the screen, as well as to reflect the light, emitted from the phosphor elements, through the face plate to see 18. A multi-aperture, cylindrical color selection electrode, or uniaxial tension focusing mask, 25, is mounts in a removable manner, by means of conventional elements, inside the panel 12, in a previously determined separate relation with the screen 22. An electron gun 26, shown schematically by the dotted lines of Figure 1, is mounted centrally inside the necks 14 , to generate and direct three on-line electron beams 28, a central beam and two external lateral beams, along convergent paths through the mask 25, to the screen 22. The in-line direction of the beams 28 is normal to the plane of the paper. The cathode ray tube of Figure 1 is designed to be used with an external magnetic deflection yoke, such as yoke 30, shown in the vicinity of the junction of the funnel with the neck. When activated, the yoke 30 subjects the three beams to magnetic fields that cause the beams to scan a rectangular horizontal and vertical grid on the screen 22. The uniaxial tension mask 25 is formed from a thin rectangular sheet of approximately 0.05 millimeters (2 mils) thick, which is shown in Figure 2, and includes two long sides 32, 34, and two short sides 36, 38. The two long sides 32, 34 of the mask, parallel to the major central axis X , of the cathode ray tube, and the two short sides 36, 38, parallel to the minor central axis Y of the cathode ray tube. The mask 25 includes a portion with openings that is adjacent to, and superimposed on, an effective image area of the screen 22 that lies within the dotted center lines of Figure 2, which define the perimeter of the mask 25. As Shown in Figure 4, the uniaxial tension focusing mask 25 includes a plurality of first elongated metal cords 40, each having a transverse, or wide, dimension of approximately 0.3 millimeters (12 mils), separated by grooves substantially equally spaced 42, each having a width of approximately 0.55 millimeters (21.5 thousandths) which are parallel to the minor axis, Y, of the cathode ray tube, and the phosphor lines of the screen 22. In the color cathode ray tube having a diagonal dimension of 68 centimeters (27V), there are approximately 600 of the first metal cords 40. Each of the slots 42 extends from the long side 32 of the mask to the other long side 34, not shown in Figure 4. In Figures 1 to 3 a frame 44 is shown, for the mask 25, and includes four major members, two torsion tubes or curved members 46 and 48, and two tension arms or straight members 50 and 52. The two curved members 46 and 48 are parallel to the major axis, X, and one with the other. As shown in Figure 3, each of the straight members 50 and 52 includes two overlapping partial members or parts 54 and 56, each part having an L-shaped cross section. The overlapping portions 54 and 56 are welded together in where they are overlapped One end of each of the parts 54 and 56 is attached to one end of one of the curved members 46 and 48. The curvature of the curved members 46 and 48 is coupled with the cylindrical curvature of the uniaxial tension focusing mask. The long sides 32, 34 of the uniaxial tension focusing mask 25 are welded between the two curved members 46 and 48 that provide the necessary tension to the mask. Prior to welding to frame 44, the mask material is pre-stressed and darkened by tensioning the mask material while heating, in a controlled atmosphere of nitrogen and oxygen, at a temperature of about 500 ° C for 1 hour. The frame 44 and the mask material, when welded together, comprise a uniaxial tension mask assembly. With reference to Figures 4 and 5, a plurality of second metal cords 60 are provided, each having a diameter of approximately 0.025 millimeters (one thousandth), substantially perpendicular to the first metal cords 40, and separated therefrom by an insulator 62 formed on the side facing the screen of each of the first metal cords. The second metal cords 60 form cross members which facilitate the application of a second anode, or focus, potential for the mask 25. The preferred material for the second metal cords is Hy udO wire, available from Carpenter Technology, Reading, P.A. The vertical separation, between the second adjacent cords 60, is approximately 0.41 millimeters (16 mils). Unlike the cross members described in the prior art, which have a substantial dimension that significantly reduces the electron beam transmission of the masking plate, the relatively thin second metal cords 60 provide the essential focusing function to the present face mask. uniaxial focusing voltage 25, without adversely affecting its electron beam transmission. The uniaxial voltage focusing mask 25, described herein, provides a mask transmission, in the center of the screen, of about 60 percent, and requires that the second anode, or focusing voltage, ΔV, applied to the second cords 60, differ from the first anode voltage applied to the first metal cords 40 by less than about 1 kV, for a first anode voltage of about 30 kV. The insulators 62, shown in Figures 4 and 5, are disposed substantially continuously on the side facing the screen of each of the first metal cords 40. The second metal cords 60 are kneaded with the insulators 62 to electrically insulate to the second metal cords 60 of the first metal cords 40. As shown in Figure 6, each of the insulators 62 is formed from at least two layers. A first insulating layer 64 is formed of a suitable material having a thermal expansion and contraction behavior, to which it accords with the material of the mask 25. Additionally, the material for the first insulating layer 64 must have a relatively low melting temperature. , so that it can flow, sinter, and adhere to the laces of the mask within a temperature range of approximately 450 ° C. However, the insulating material must also be stable during the sealing of the chip of the panel of the face plate 12 of the cathode ray tube with the funnel 15, which occurs at an elevated temperature of about 450 ° C to 500 ° C. . Additionally, the first insulating layer 64 must have a dielectric breakdown strength greater than 4,000 volts / millimeter (100 volts / thousandth), with electrical resistivities in volume and surface greater than 1013 ohms-cm, and 103 ohms / square, respectively. The first insulating layer 64 must also have adequate mechanical strength and an adequate elastic modulus, must be of low gasification during processing and operation, and must retain these functional characteristics for an extended period of time within the radioactive environment of the tube. cathode rays. A second insulating layer 66 must be chemically, electrically, and mechanically compatible with the first insulating layer 64. The second layer 66 must also have good flow characteristics, it must be stable during the frit sealing of the panel of the face plate 12 to the funnel 15, and must adhere well to the second cords 60. The second insulating layer 66 also seals any defects in the first underlying insulating layer 64. Although only two insulating layers 64 and 66 are described, it should be evident that additional layers can be used. , if required, as long as the layers are compatible with each other, and with the first underlying metal cords 40. Suitable materials for the mask 25 include two points: high expansion, low carbon steels having a coefficient of thermal expansion (COE) within the range of 120-160 x 10"7 / ° C; an intermediate expansion alloy, such as iron, cobalt, nickel, for example KOVARMR, having a coefficient of thermal expansion within the range of 40-60 x 10 / ° C; and a low expansion alloy, such as an iron-nickel alloy, for example, INVARMR, which has a coefficient of thermal expansion within the range of 15 -30 x 10"7 / ° C.

Suitable materials with good electrical properties that can be used to form the first insulating layer 64 are mentioned in Table I.

TABLE I SYSTEMS OF TEMPERATURE COEFFICIENT COMMENTS MATERIAL EXPANSION NOMI- DE PROCESA- NAL (ÍO- C) NOMI¬ NAL (° C) 80-130 380-500 glass filler required for welding to improve the stability (vitreous) to heat and to adjust the COE 75-120 400-550 glass filler required to adjust solder the COE (devitrification) Conventional glasses 30-130 600-1000 approach based on chemistry (that is, not a solution to lower the subject matter that carries substantial process temperature, and / or Pb) to adjust the COE with filling Conventional glass - 0-140 800-1300 same as the previous ceramic Conventional Ceramics 0-130 1000-2000 approach based on the chemistry of the solution to lower the process temperature or vacuum deposit.

With the exception of glass vitreous and devitrification glasses mentioned in Table I, the other material systems have nominal processing temperatures outside the 500 ° C scale described above, however, these material systems can be adapted for use as first insulating layers, with the approaches illustrated in the last columns of Table I. A devitrification welding glass is one that melts at a specific temperature to form an insulator with a substantially high crystalline content, and does not melt at the same temperature or at a lower temperature; while a vitreous welding glass does not form a crystal glass insulator. The fillers that can be used in combination with the welding glasses described in Table I are mentioned in Table II.

TABLE II Filling Material Coefficient of Thermal Expansion (l (r7 / 0C) Beta-eucryptite -86 (Li2Al2Si06 Aluminum Titanate -19 (AlTi05) Silica Vitrea (SIO2) 5.5 Beta-spodumene 9 (Li2Al2Si4012) Wilemite (Zn2Si04) 25 Cordierite (Mg2Al4Si50lg 26 Celsius (BaAl2Si208) 27 Ganyte (ZnAl204) 40 Boron nitrate (BN) 40 Mulita (Al ^ S ^ O ^ 43 Anortite (CaAl2Si208 45 Clinoenestatite (MgSi0) 78 Magnesium titanate (MgTi03) 79 Alumina (A1203) 88 Forsterite (Mg2Si04) 94 Wolastonite (CaSi03) 94 Quartz 120 Fluorite 225 Cristobalite 125 (a ~ 225 ° C) 500 (a ~ 350 ° C) Preferred methods for synthesizing coupled expansion insulators for the three ranges of metal expansion, described above, are illustrated in Table III.

TABLE III High Expansion Matrix Expan Alloy-Low Alloy Alloy (eg Steel) Intermediate Expansion (eg ROYARA) (eg INVAR * 1 *) PZB, • matrix of high • expansion matrix • compounds with expansion, such as intermediate, such as fillings of low is or expansion PZBS, • Compound composites with relie- • accommodates the inflec-systems of bination with one plus expansion of the glass expansion of quartz, cristobamate and low with a small solder of lita, and fluorite addition of cristobalite devitrification or vitreous The processing methods for the insulators shown in Table I, to be applied to the first metal cords 40 of the mask 24, depend on the choice of the insulator. In Table IV a few examples of the application parameters of the insulator are shown.

TABLE IV Deposit Preparation System Standard Materiel Fixation Material Glasses • molten glass • spraying • brush • heat in soldering with a size • roller • abrasion an atmospide devitride particles averaged • electro deposit • mask and neutral fi ltration gave < 10 micrometers forético oxidant strip • mix and mill with • solvent binder immersion • Glass in cast • spraying • brush • heat in welding not fried up to a size • roller • abrasion an atmosphere • pro-electrophoretic particle • mask and neutral ra You sing medium < 10 micras • Oxidizing strip dip (vitreous) • mix and mill with binder and solvent Glasses • particle synthesis • spraying • brush • heat in conventional fines (- 1000 Å or • roller • abrasion several less) • immersion • mask and conditions • dispersion in atmospheric format to gel or in solution Ceramic • particle synthesis • spraying • brush • heat in conventional fines (- 1000 Å or • roller • abrasion several less) • immersion • mask and conditions • dispersion in atmospheric format to gel or in solution Ceramic • Particle synthesis • Spray • Brush • Glass heat the fines (~ 1000 Á or • Roller • Abrasion several conconventional less) • Immersion • Mask and conditions • Dispersion in atmospheric format to gel or in solution Glass, ceramics • Sparkling Objective • deposit • abrasion • not always mica, and glass. Vacuum • mask and requires ceramics with • PVD, CVD strip based on film deposition Compounds • dispersed during • depending • be • heat in condyles systems appropriate grinding appropriate atmospheric conditions with appropriate casings. dispersed particle phases EXAMPLE I In accordance with a preferred method for manufacturing the uniaxial tension focusing mask 25, a first coating of an insulating devitrifying solder glass is provided, for example, by spraying, on the side facing the screen of the first metal cords 40. The first metal cords, in this example, are formed of high-expansion low carbon steel, which has a coefficient of thermal expansion within the range of 120-160 x 10"7 / ° C. The devitrifying welding glass can be a PbO-ZnO-B2? 3 system, referred to in Table III as PZB, or a PbO-ZnO-B2? 3-Si02 system, referred to in Table III, as PZBS. Each of the glass systems has a coefficient of thermal expansion of approximately 75 - 120 x 10 / ° C, depending on the composition, in percentage by weight of the constituents.A suitable solvent and an acrylic binder are mixed with the glass. io of devitrifying welding, to give the first coating a modest degree of mechanical strength. Because the weld glass system has a coefficient of thermal expansion only slightly less than that of the high expansion steel of the cords 40, it is not necessary to add filler material to the weld glass system; although one or more of the quartz, fluorite, and cristobalite fillers may be added to make the coefficients of thermal expansion of glass and steel exactly match. In the case that it is desired to add fillers, quartz and / or fluorite can be added, to comprise up to 40 percent by weight, and the cristobalite can comprise less than 10 percent by weight of the devitrifying solder glass composition. The rest of the composition comprises PZB or PZBS. The first coating has a thickness of approximately 0.14 millimeters. The frame 44, to which the first metal cords 40 are attached, is placed in an oven, and the first coating is dried at a temperature of about 80 ° C. After drying, the first coating is contoured, in such a way that it is protected by the first metal cords 40, to prevent the electron beams 28, which pass through the slots 42, from hitting the insulator and loading it. The contouring is performed on the first coating by abrading or otherwise stirring any welding glass material of the first coating extending beyond the edge of the beads 40, and which would contact the deflected or non-diverted electron beams. The first coating is entirely removed from the first and last initial metal cords, i.e., the right and the left, hereinafter referred to as the first metal end cords 140, before the first coating is heated to the first coating. the sealing temperature.

The first metal end cords 140, which are outside the effective image area, will subsequently be used as bus bars to direct the second metal cords 60. To additionally secure the electrical integrity of the uniaxial tension focusing mask 25, removes at least a first additional metal cord 40 between the first metal end cords 140 and the first metal cords 40 that overlap the effective image area of the shields, to minimize the possibility of a short circuit. Accordingly, the first right and left metal end cords 140, outside the area of the effective image, are separated from the first metal cords 40 which overlap the image area, by a distance of at least 1.4 millimeters ( 55 thousandths), which is greater than the width of the equally spaced slots 42 that separate the first metal cords 40 through the image area. The frame 44, with the first metal cords 40 and the end cords 140 attached thereto (hereinafter referred to as the assembly), is placed in an oven and heated in air. The assembly is heated for a period of 30 minutes at a temperature of 300 ° C, and maintained at 300 ° C for 20 minutes. Then, during a period of 20 minutes, the oven temperature is increased to 460 ° C, and it is maintained at that temperature for 1 hour, to melt and crystallize the first coating, in order to form a first insulating layer 64 on the first metal cords 40, as shown in Figure 6. The resulting first insulating layer 64, after baking, is stable, and will not melt again during the frit seal of the panel of the face plate 12 to the funnel 15. , and has a thickness within the range of 0.5 to 0.9 millimeters (2 to 3.5 thousandths) through each of the cords 40. The preferred material for the first coating is a devitrified lead-zinc-borosilicate glass. which is melted on the scale of 400 ° C to 450 ° C, and is commercially available as SCC-11, in a number of glass suppliers, including SEM-COM, Toledo, OH, and Corning Glass, Corning, NY. Next, a second coating of a suitable insulating material, mixed with a solvent and a binder, is applied, for example, by spraying to the first insulating layer 64. Preferably, the second coating is a non-devitrifying solder glass (i.e. , vitreous) having a composition of 80 weight percent of PbO, 5 weight percent of ZnO, 14 weight percent of B2O3, 0.75 weight percent of Sn02, and optionally 0.25 percent by weight. CoO weight. A vitreous material is preferred for the second coating, because, when melted, it fills any void in the surface of the first insulating layer 64, without adversely affecting its electrical and mechanical characteristics, nor will it alter the temperature stability of the first layer. underlying insulation layer. Alternatively, a devitrifying welding glass can be used to form the second coating. The second coating is applied to a thickness of approximately 0.025 to 0.05 millimeters (1 to 2 thousandths). The second coating is dried at a temperature of 80 ° C, and is contoured as described above, to remove any excessive material that could be impacted by electron beams 28. The second coating has a coefficient of thermal expansion of approximately 110 x 10"7 / ° C and may contain up to 40 weight percent quartz and / or fluorite, and less than 10 weight percent cristobalite, i.e. the same concentration of fillers that is added to the first coating.

EXAMPLE II The first metal cords, in this second example, are formed of a low expansion iron-nickel alloy, such as INVARMR, which has a coefficient of thermal expansion within the range of 15-30 x 10"7. The expansion behavior of this material up to a temperature of 100 ° C remains low at approximately 15 x 10"7 / ° C; however, there is an inflection in the expansion behavior from 160 ° C to 271 ° C, due to a magnetic phase change that increases the coefficient of thermal expansion, within this temperature range, to approximately 30 x 10"7 / C. The devitrifying welding glass used with the iron-nickel cords 40, may be the PZB or PZBS system described above, because each of the glass systems has a coefficient of thermal expansion of approximately 75-120 x. 10 / ° C, depending on the composition of the constituents, the coefficient of thermal expansion of the glass should be reduced to slightly less than, or substantially equal to, that of the iron-nickel cord material. 40 percent by weight of a low expansion filler, such as Beta-eucryptite (Li2Al2Si06), Aluminum titanate (AlTi05), vitrea silica (Si02), or Beta-spodumene (Li2Al2Si012) to the Attribute of PZB or PZBS Additionally, up to 5 percent by weight of cristobalite is added to compensate for the inflection in the coefficient of thermal expansion of the iron-nickel alloy. The cristobalite has a coefficient of thermal expansion of 125 x 10"7 / ° C up to ~ 225 ° C, and 500 x 10" 7 / ° C up to ~ 350 ° C. The small amount of cristobalite added to the composite mixture provides a coupling between the expansion behavior of the iron-nickel alloy and the first weld glass coating. A suitable solvent and an acrylic binder are mixed with the devitrifying solder glass composite, to give the first coating a modest degree of mechanical strength. The rest of the composition comprises PZB or PZBS. The first coating has a thickness of approximately 0.14 millimeters. The frame 44, to which the first metal cords 40 are attached, is placed in an oven, and the first coating is dried at a temperature of about 80 ° C. After drying, the first coating is contoured, in such a way that it is protected by the first metal cords 40, to prevent the electron beams 28, which pass through the slots 42, from hitting the insulator and loading it. The contouring is performed, as described in the first example, by abrading or otherwise removing any of the welding glass material of the first coating extending beyond the edge of the beads 40, and making contact with the bundles of deflected or non-diverted electrons 28. The first coating is removed entirely from the first and last metal end first cords 140, before the first coating is heated to the sealing temperature. The first metal end cords 140, which are outside the area of the effective image, will subsequently be used as bus bars to direct the second metal cords 60. To additionally secure the electrical integrity of the uniaxial tension focusing mask 25, at least one additional first metal cord 40 is removed between the first metal end cords 140 and the first metal cords 40 which overlap the effective image area of the screen, to minimize the possibility of a short circuit. Accordingly, the first right and left metal end cords 140, outside the area of the effective image, are separated from the first metal cords 40 which overlap the image area, by a distance of at least 1.4 millimeters ( 55 thousandths), which is greater than the width of the equally spaced slots 42 that separate the first metal cords 40 through the image area. The assembly comprising the frame 44 with the first metal cords 40 and the end cords 140 attached thereto, is placed in an oven, and heated in air. The assembly is heated for a period of 30 minutes at a temperature of 300 ° C, and maintained at 300 ° C for 20 minutes. So, during a period of 20 minutes, the furnace temperature is increased to 460 ° C, and maintained at that temperature for 1 hour to melt and crystallize the first coating, to form a first insulating layer 64 over the first metal cords. , as shown in Figure 6. The resulting first insulating layer 64, after baking, has a thickness within the range of 0.5 to 0.9 millimeters (2 to 3.5 thousandths) through each of the 40 cords. Next, a second coating of a suitable insulating material, mixed with a solvent and a binder, for example, by spraying, is applied to the first insulating layer 64. Preferably, the second coating is a non-dewatering solder glass (it is say, vitreous) having a composition of 80 weight percent of PbO, 5 weight percent of ZnO, 14 weight percent of B2? 3, 0.75 weight percent of Sn02, and optionally 0.25 weight percent. percent by weight of CoO . Alternatively, a devitrifying welding glass can be used to form the second coating. The second coating is applied to a thickness of approximately 0.025 to 0.5 millimeters (1 to 2 mils). The second coating is dried at a temperature of 80 ° C, and contoured, as described above, to remove any excess material that could be impacted by the electron beams 28. The second coating has a coefficient of thermal expansion of about 15 x 30 x 10"/ ° C and may contain up to 40 percent by weight of low expansion fillings, such as Beta-eucryptite (Li2Al2Si06), Titanate Aluminum (AlTi05), vitreous silica (Si02), or Beta-spodumene (Li2Al2Si40? 2) and up to 5 percent by weight of cristobalite, that is, the same concentration of fillers that are added to the first coating.

EXAMPLE III The first metal cords, in this third example, are formed of an intermediate expansion iron-cobalt-nickel alloy, such as KOVARMR, which has a coefficient of thermal expansion within the range of 40-60 x 10" 7 / ° C. The devitrifying welding glass used with the intermediate expansion alloy cords 40, may be the PZB or PZBS system described above, because each of the glass systems has a coefficient of thermal expansion of approximately 75. x 120 x 10"7 / ° C depending on the composition of the constituents, the coefficient of thermal expansion of the glass should be reduced to substantially equal to that of the intermediate expansion alloy cord material. This is achieved by the inclusion of approximately 40 percent by weight of suitable fillers from the group consisting of low expansion fillings of Li2Al2SiOß, AITÍO5, if vitreous ° 2 and Li2Al2Si40? 2, and from the group of expansion fillings intermediate consisting of Zn2Si04, Mg2Al4Si50lg, BaAl2Si08, ZnAl204, BN, Al6Si2013, CaAl2Si2Og, MgSi03, MgTi03, A120, Mg2Si04, and CaSi03 such as Beta-eucryptite (Li2Al2Si06), Aluminum Titanate (AlTi05) vitrea silica (Si02), Beta-spodumene (Li2Al2Si0? 2), to the matrix of PZB or PZBS. A suitable solvent and an acrylic binder are mixed with the devitrifying solder glass composite, to give the first coating a modest degree of mechanical strength. The rest of the composition comprises PZB or PZBS. The first coating has a thickness of approximately 0.14 millimeters. The frame 44, to which the first metal cords 40 are attached, is placed in an oven, and the first coating is dried at a temperature of about 80 ° C. After drying, the first coating is contoured, in such a way that it is protected by the first metal cords 40, to prevent the electron beams 28, which pass through the slots 42, from hitting the insulator and loading it. The contouring is performed, as described in the first example, by abrading or otherwise removing any welding glass material from the first coating that extends beyond the edge of the cords 40, and which would make contact with. deflected or non-diverted electron beams 28. The first coating is removed entirely from the first and last first metal end cords 140, before the first coating is heated to the sealing temperature. The first metal end cords 140, which are outside the area of the effective image, will subsequently be used as bus bars to direct the second metal cords 60.

To further ensure the electrical integrity of the uniaxial tension focusing mask 25, at least one additional first metal cord 40 is removed between the first metal end cords 140 and the first metal cords 40 which overlap the area of the metal cord. Effective image of the screen, to minimize the possibility of a short circuit. Accordingly, the first right and left metal end cords 140, outside the area of the effective image, are separated from the first metal cords 40 which overlap the image area, by a distance of at least 1.4 millimeters ( 55 thousandths), which is greater than the width of the equally spaced slots 42 that separate the first metal cords 40 through the image area. The assembly comprising the frame 44 with the first metal cords 40 and the end cords 140 attached thereto, is placed in an oven, and heated in air. The assembly is heated for a period of 30 minutes at a temperature of 300 ° C, and kept at 300 ° C for 20 minutes. Then, during a period of 20 minutes the oven temperature is increased to 460 ° C, and it is maintained at that temperature for 1 hour to melt and crystallize the first coating, in order to form a first insulating layer 64 on the first cords of metal 40, as shown in Figure 6. The resulting first insulating layer 64, after baking, has a thickness within the range of 0.5 to 0.9 millimeters (2 to 3.5 thousandths) through each of the cords 40. Next, a second coating of a suitable insulating mial, mixed with a solvent and a binder, for example, by spraying, is applied to the first insulating layer 64. Preferably, the second coating is a non-devitrifying solder glass. (ie, vitreous), which has a composition of 80 weight percent of PbO, 5 weight percent of ZnO, 14 weight percent of B2? , 0.75 weight percent Sn02, and optionally 0.25 weight percent CoO. Alternatively, a devitrifying welding glass can be used to form the second coating. The second coating is applied to a thickness of approximy 0.025 to 0.05 millimeters (1 to 2 thousandths). The second coating is dried at a temperature of 80 ° C, and contoured, as described above, to remove any excess mial that could be impacted by the electron beams 28. The second coating has a coefficient of thermal expansion of about 40-60 x 10"7 / ° C and can contain up to 40 percent by weight of suitable fillers from the group consisting of low-expansion fillers of Li2Al2Si06, AlTi05, Vitro Si02 and Li2Al2Si012, and from the group of fillers intermediexpansion consisting of Zn2Si04, Mg2Al4Si5018, BaAl2Si208, ZnAl204, BN, Al6Si2013, CaAl2Si208, MgSi03, MgTi03, A1203, Mg2Si04, and CaSi03 Additional mial systems, such as conventional glass systems, glass systems, can also be used conventional ceramics, conventional ceramics, deposited films, and composites of these systems, which are mentioned in Table III, as suitable insulating coatings. for the metal cords 40 of the mask 25. The methods for preparation, deposition, pattern formation, and fixation, that is, sintering the heat treatment, of these mial systems, are summarized in the Table. III, and are suitably specific to allow an ordinary expert in this field to form insulating coatings therefrom. As shown in Figures 4, 5, and 7, a thick coating of a devitrifying solder glass containing silver is provided to make it conductive on the side facing the screen of the first left metal end cords and right 140. A conductor 65, formed of a short length of nickel wire, is embedded in the conductive welding glass on one of the first metal end cords. Then, the assembly, having the second dry and contoured coating that overlaps the first insulating layer 64, has the second metal cords 60 applied thereto, such that the second metal cords overlap the second coating of mial insulator, and are substantially perpendicular to the first metal cords 40. The second metal cords 60 are applied using a embossing accessory, not shown, which precisely maintains the desired separation of approximy 0.41 mm between the second adjacent metal cords. The second metal cords 60 also contact the conductive welding glass on the first metal end cords 140. Alternatively, the conductive welding glass can be applied at the junction between the second metal cords 60 and '. the first 140 metal end cords during, or after, the winding operation. Next, the assembly, which includes the embobinator fitting, is heated for 7 hours at a temperature of 460 ° C to melt the second coating of insulating material, as well as the conductive welding glass, to bond the second metal cords 60 in. of both a second insulating layer 66 and a conductive layer of glass 68. The second insulating layer 66 has a thickness, after sealing, of approximately 0.013 to 0.025 millimeters (0.5 to 1 thousandth). The height of the glass conductive layer 68 is not critical, but must be thick enough to firmly anchor the second metal cords 60 and the conductor 65 therein. The portions of the second metal cords 60 that extend beyond the glass conducting layer 68 are cut out to release the assembly of the embobinator fitting. As shown in Figure 4, the first metal end cords 140 are cut at the ends adjacent the long side or upper portion 32. The cords 140 are cut similarly adjacent the long side or lower portion 34, not shown in the Figure 4, of the mask 25, to provide gaps of approximately 0.4 millimeters (15 mils) therebetween, which will electrically insulate the first metal end cords 140. The first metal end cords 140 form busbars that allow for apply a second anode voltage to the second metal cords 60 when the conductor 65, embedded in the glass conductive layer 68, is connected to the second button of the anode 17.

Claims (20)

1. A color cathode ray tube (10) comprising an evacuated envelope (11) having thereon an electron gun (26) for generating at least one electron beam (28), a face plate panel (12) ) having a luminescent screen (22) with phosphor lines on an internal surface thereof, and a uniaxial tension focusing mask (25) having a plurality of first separated metal cords (40) that are adjacent to an area effective image of the screen, and defining a plurality of grooves (42) substantially parallel to the phosphor lines, each of the first metal cords having through the effective image area, a substantially continuous insulator (62) on one side facing the screen thereof, this insulator comprising more than one insulating layer (64, 66), and a plurality of second metal cords (60) oriented substantially perpendicular to the first metal cords, the second metal cords connecting to the insulator, wherein the insulator (62) comprises: a first insulating layer (64) having a coefficient of thermal expansion that is substantially coupled with, or is slightly lower than, the expansion coefficient thermal insulation of the first metal cords (40), and a second insulating layer (66) having a coefficient of thermal expansion substantially equal to the coefficient of thermal expansion of the first insulating layer.

2. A color cathode ray tube (10) comprising an evacuated envelope (11) having thereon an electron gun (26) for generating three electron beams (28), a face plate panel (12) ) having a luminescent screen (22) with phosphor lines on an internal surface thereof, and a uniaxial tension focusing mask (25) in proximity to the screen, the tension focusing mask having two long sides (32, 34) with a plurality of first transversely spaced metal cords (40) extending therebetween, the space between the first adjacent metal cords defining substantially equally spaced slots (42) parallel to the phosphor lines of the screen, the long sides of the mask being secured to a substantially rectangular frame (44) having two long sides and two short sides, each of the first metal cords having one area of the effective image of the p A first, substantially continuous first insulating layer (64) on one side facing the screen thereof, a second insulating layer (66) overlying the first insulating layer, and a plurality of second metal cords (6 = 9 oriented substantially perpendicular to the first metal cords, the second metal cords joining with the second insulating layer, wherein: the first insulating layer (64) has a coefficient of thermal expansion that is substantially coupled with, or is slightly lower that, the coefficient of thermal expansion of the first metal cords (40), and the second insulating layer (66) has a coefficient of thermal expansion substantially equal to the coefficient of thermal expansion of the first insulating layer. The cathode ray tube (10) as described in claim 2, wherein the first metal cords (40) have a coefficient of thermal expansion within the range of 15 x 160 x 10"7 / ° C. 4. The cathode ray tube (10) as described in claim 2, wherein the first insulating layer (64) has a coefficient of thermal expansion within the scale of 0 x 140 x 10"7 / ° C. The cathode ray tube (10) as described in claim 2, wherein the first metal cords (40) comprise a low carbon steel having a coefficient of thermal expansion within the scale of 120 x 160 x 10"7 / ° C 6. The cathode ray tube (10) as described in claim 5, wherein the first insulating layer (64) comprises a devitrified welding glass matrix, having a coefficient of thermal expansion within the range of 75-120 x 10"7 / ° C, this matrix being selected from the group that consists of PbO-ZnO-B203 and PbO-ZnO-B203-SiO2 7. The cathode ray tube (10) as described in claim 6, wherein the first insulating layer (64) comprises a composite material that includes the devitrified solder glass matrix, and a filler selected from the group consisting of cristobalite, fluorite, and quartz, the cristobalite comprising not more than 10 weight percent, comprising at least one of the fluorspar and the quartz percent by weight, and the devitrified solder glass matrix comprising the remainder of the composite material 8. The cathode ray tube (10) as described in claim 2, wherein the first metal cords (40) comprise a alloy hie low expansion nickel that has a coefficient of thermal expansion within the range of 15 - 30 x 10 / ° C. The cathode ray tube (10) as described in claim 8, wherein the first insulating layer (64) comprises a composite material consisting of a devitrified welding glass matrix, having a coefficient of thermal expansion within of the scale of 75 -120 x 10"/ ° C, selecting this matrix from the group consisting of PbO-ZnO-B203 and PbO-ZnO-B2? 3 ~ Si02, and at least two fillings for low the coefficient of thermal expansion within the range of 10 - 25 x 10 / ° C, one of these fillings having a low coefficient of thermal expansion, and the other having a high coefficient of thermal expansion, with an inflection that occurs at a temperature where the iron-nickel alloy undergoes an inflection due to the magnetic transitions 10. The cathode ray tube (10) as described in claim 9, wherein the filling of low coefficient of thermal expansion is selected from the group. what cons in Li2Al2SiOg, AlTi05, Si0 vitreous, and Li2Al2Si4012, and the filling that has a high thermal expansion coefficient comprises cristobalite. The cathode ray tube (10) as described in claim 10, wherein the filler having a low coefficient of thermal expansion, comprises up to 40 weight percent of the material of the composition, the cristobalite comprises up to 5 percent by weight, and the devitrifying solder glass matrix comprises the rest. The cathode ray tube (10) as described in claim 2, wherein the first metal cords (40) comprise an intermediate expansion alloy having a coefficient of thermal expansion within the range of 40-60 x 10'7 / ° C. The cathode ray tube (10) as described in claim 12, wherein the first insulating layer (64) comprises a composite material consisting of a devitrified welding glass matrix, having a coefficient of thermal expansion within of the scale of 75 x 120 x 10"7 / ° C, selecting the matrix from the group consisting of PbO-ZnO-B2? 3 and PbO-ZnO-B2? 3 ~ Si02, and at least one filling for low the coefficient of thermal expansion within the range of 40-60 x 10"7 / ° C, this filling having a low or intermediate thermal expansion coefficient. 14. The cathode ray tube (10) as described in claim 13, wherein the filler is selected from the group of low expansion fillings consisting of Li2Al2Si06, AlTi05, Vitro Si02 and Li2Al2Si40j2, and from the group of intermediate expansion fillers consisting of Zn2Si04, Mg2Al4Si501, BaAl2Si208, ZnAl204, BN, Al6Si2013, CaAl2Si208, MgSi03, MgTi03, Al203, Mg2Si04, and CaSi03, this filler comprising up to 40 weight percent of the composite material of the first insulating layer (64). 15. The cathode ray tube (10) as described in claim 2, wherein the second insulating layer (66) comprises a glass-solder glass consisting essentially of PbO-ZnO-B203-Sn? 2 and optionally COO. The cathode ray tube (10) as described in claim 9, wherein the second insulating layer (66) comprises a vitreous solder glass matrix having a composition comprising 80 weight percent of PbO, 5 percent by weight of ZnO, 14 percent by weight of B2? 3, 0.75 percent by weight of Sn02, and optionally 0.25 percent by weight of CoO, with a coefficient of thermal expansion of approximately 110 x 10"7 / ° C, and at least two fillings to lower the coefficient of thermal expansion of the scale of 10 - 25 x 10" / ° C having one of these fillings a low coefficient of thermal expansion, and the other having a high coefficient of thermal expansion, with an inflection that occurs at a temperature in which the iron-nickel alloy undergoes an inflection to magnetic transitions. 17. The cathode ray tube (10) as described in claim 16, wherein the low coefficient of thermal expansion filler is selected from the group consisting of Li2Al2Si06, AlTi05, Vitro Si02, and Li2Al2Si40? 2, and the filling having a high coefficient of thermal expansion with an inflection, comprises cristobalite. The cathode ray tube (10) as described in claim 17, wherein the low thermal expansion coefficient filler, comprises up to 40 weight percent of the second insulating layer (66), the cristobalite comprises up to 5 percent by weight, and the vitreous solder glass matrix comprises the rest. 19. The cathode ray tube (10) as described in claim 8, wherein the second insulating layer (66) comprises a glass vitreous solder matrix having a composition comprising 80 weight percent of PbO, 5 percent by weight of ZnO, 14 percent by weight of B2? 3, 0.75 percent by weight of Sn02, and optionally 0.25 percent by weight of CoO, with a coefficient of thermal expansion of approximately 110 x 10"7 / ° C, and at least one filling to lower the coefficient of thermal expansion within the range of 40 - 60 x 10 / ° C, these fillings having a low or intermediate thermal expansion coefficient. cathode rays (10) as described in claim 19, wherein the filler is selected from the group of low expansion fillers consisting of Li2Al2Si06, AlTi05, vitrous Si02 and Li2Al2Si40j2, and from the group of intermediate expansion fillers that consists of Zn2Si04, Mg2AlSi5018, Ba Al2Si208, ZnAl204, BN, Al6Si2013, CaAl2Si208, MgSi03, MgTi0, A1203, Mg2Si04, and CaSi03, this filler comprising up to 40 weight percent of the second insulating layer (66). SUMMARY The present invention relates to a color cathode ray tube (10) having an evacuated envelope (11) with an electron gun (26) therein, to generate at least one electron beam (28). The casing (11) further includes a face plate panel (12) having a luminescent screen (22) with phosphor lines on an inner surface thereof. A uniaxial tension focusing mask (25), having a plurality of separate first metal cords (40) is located adjacent to an effective image area of the screen. The spacing between the first metal cords defines a plurality of slots (42) substantially parallel to the phosphor lines of the screen. Each of the first metal cords through the effective image area of the screen has a first substantially continuous insulating layer (64) on a side facing the screen thereof. A second insulating layer (66) is superimposed on the first insulating layer. A plurality of second metal cords (60) are oriented substantially perpendicular to the first metal cords, and are bonded thereto by the second insulating layer. The first insulating layer has a coefficient of thermal expansion that substantially agrees with, or is slightly lower than, that of the first cords. The second insulating layer has a coefficient of thermal expansion that is substantially identical to that of the first insulating layer.