US3764514A - Apparatus for coating a pattern mask for use in forming a color crt screen structure - Google Patents

Apparatus for coating a pattern mask for use in forming a color crt screen structure Download PDF

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Publication number
US3764514A
US3764514A US00310704A US3764514DA US3764514A US 3764514 A US3764514 A US 3764514A US 00310704 A US00310704 A US 00310704A US 3764514D A US3764514D A US 3764514DA US 3764514 A US3764514 A US 3764514A
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United States
Prior art keywords
coating
mask
electrode
applying
suspension
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Expired - Lifetime
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US00310704A
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English (en)
Inventor
J Debernardis
W Slobbe
K Speigel
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GTE Sylvania Inc
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GTE Sylvania Inc
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Assigned to NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP. reassignment NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP. ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981. (SEE DOCUMENT FOR DETAILS). Assignors: GTE PRODUCTS CORPORATION A DE CORP.
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D1/00—Electroforming
    • C25D1/12—Electroforming by electrophoresis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
    • H01J9/142—Manufacture of electrodes or electrode systems of non-emitting electrodes of shadow-masks for colour television tubes
    • H01J9/144—Mask treatment related to the process of dot deposition during manufacture of luminescent screen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines

Definitions

  • Each of the apertures therein being ofa substantially round or elongated shaping, is cognitively related to a specific grouping of similar-shaped phosphor dots, comprising the spatially related screen pattern, in a manner to enable the selected electron beams traversing the apertures to impinge the proper phosphor dots therebeneath.
  • an opaque interstitial web having multitudinous windows defined as bare glass areas that are of a size smaller than the related mask apertures.
  • the phosphor pattern elements are then disposed on these window areas upon photo-exposure through the same size mask apertures by one of the various processes known to the art. While the aforedescribed dot-erosion procedure is an acceptable production technique, it necessitates the inclusion of additional process steps.
  • the improved apparatus utilizing a formed foraminous electrode temporarily modifies the apertures member by electrophoretically disposing a basic or first coating of a substantially semiporous structure on the mask in a manner to effect predeterminate temporal reduction in the sizes of the initially defined apertures.
  • the foraminous electrode, the discrete spacing thereof from the mask, along with the handling of the coating suspension comprises an improved coating apparatus which provides for a markedly improved modified mask structure.
  • FIG. 2a is an enlarged sectional view of the apertured pattern member of the mask showing the temporary modification thereof;
  • FIG. 2b is an enlarged sectional view of a portion of the mask-screen assembly illustrating utilization of the showning still other embodiments of the coating apparatus.
  • F IG. 1 a prior art view illustrating a shadow mask type of color cathode ray tube 11 in an operable environment denoted diagrammatically as 12.
  • the encompassing envelope 13 of the tube includes a funnel portion 15 to which a viewing panel 17 is suitably attached as by a continuous bead of bonding frit 19.
  • a metallic shadow mask structure 21 which comprises a curved or domed multiapertured pattern member 23 formed of, for example, an iron alloy material having a strengthening means or a perimetral frame 25 integral with the periphery thereof.
  • This peripheral frame has a plurality of springlike positioning means 27, attached at spaced-apart locations thereon, which mate with supporting protuberances such as metal studs 29 projecting inwardly from the sidewall portion 31 of the viewing panel 17.
  • a patterned screen structure 33 Disposed on the interior surface of the viewing panel is a patterned screen structure 33, the elements of which are formed in accordance with the apertures 35 in the adjacent mask pattern member 23, the substantially domed contour of the mask being related to the surface contour of the interior of the panel.
  • the phosphor area is dimensioned as b being at least as large as or preferably larger than the associated window area 39. To facilitate clarity in the drawing, the usually present aluminum coating or backing on the screen structure is omitted. Spaced rearward from the screen structure 33 is the shadow mask multi-opening pattern member 23, wherein a representative aperture,
  • 35 is dimensioned as c and is larger than the related window area 39.
  • the aforementioned windows and related phosphor areas are usually formed in accordance with the shapings of the apertures by known photo-exposure techniques.
  • An exemplary electron beam 45 emanating within the tube from a source not shown, is directed toward the mask-screen assembly 47.
  • a portion of the beam that is sized by the large aperture 35 traverses therethrough, impinges a related phosphor area 43 therebeneath and substantially excites the whole of the phosphor area to a state of luminescence. Since each of the excited phosphor areas 43 in this window-limited screen is as large as or larger than its associated window area 39, the total area of each window comprising the screen pattern is fully luminous.
  • the resultant display in an operating tube is easily discernible by the viewer 48.
  • This apertured member for example, is formed of a basic material 53 such as S.A.E. 1010 cold rolled steel having a conventional thickness d within the range of 0.005 to 0.007 inches, and is normally domed in a manner related to the interior contour of the viewing panel as priorly shown in FIG. 1.
  • the mask structure is priorly subjected to a known controlled atmospheric heat treatment to form a dark coating comprising a mixture of iron oxides, not shown, on both the inner and outer surfaces thereof. It is conventionally desired to retain such dark coating for use in the finished tube to enhance efficiency and uniformity in the radiation of heat in the mask induced by electron bombardment.
  • An exemplary initially formed aperture 55 in the pattern member material 53 is dimensioned as e and may be in the order of 0.0145 inches.
  • the invention being a temporary coated modification 56 of the mask member is consummated by applying a basic or first coating 57 to the apertured member 51 to effect a predeterminate reduction in the order of 0.0015 to 0.0025 inch in the sizes of the initially defined apertures in the pattern member.
  • This first coating is in the form of at least one electrophoretically disposed substantially semiporous application of a discrete particulate material that is substantially absorbent and non-reflective of ultraviolet radiant energy in substantially the 340 to 380 nanometer range. This material characteristic is a very important consideration in photo-exposing both the basic window pattern and the subsequently disposed pattern of phosphor elements thereover.
  • the affected area of sensitized coating is light-polymerized as a pattern dot having the dimension m, this being directly related to the dimension n of the light beam which is sized by the modified aperture 55.
  • This polymerized pattern dot 67 subsequently becomes a window in the opaque interstitial webbing of the color screen structure such as taught in the previously mentioned web-forming procedure disclosed in US. Pat. Application Ser. No. 41,535
  • the temporary duo coatings 57 and 61 are expeditiously and completely removed from the shadow mask by treatment with a weak solvent, such as acetic acid, followed by a water rinse. Such coating removal treatment is in no way deleterious to the mask material.
  • the precisely formed apertures are maintained as initially fabricated, and the dark iron oxide coating formed on the surface of the mask material is desirably retained to enhance uniform heat radiation in the finished tube.
  • a plurality of supportive means 81 attached in a spaced-apart manner about the mask frame 77, are mated with stud-like projections 83 extending from mask holding means 85.
  • This partially shown mask holding means is constructed to move the mask in a vertical predetermined manner to effect immersion and removal of the domed apertured portion 75 into and out of the electrophoretic suspension 79 by appropriate mechanical actuation means not shown. It is also within the scope of the invention for the mask holding means to be substantially stationary with the suspension holding container 87 being capable of vertical reciprocative movement to effect immersion and removal of the apertured portion of the mask into and out of the coating suspension. Such teaching is intended to be within the delineation shown in FIG. 3. In either instance, conventional mechanical movement means is applicable to effect the defined vertical motion required.
  • the coating suspension is held by a non-conductive liquid-holding container 87 having sufficient depth to accommodate a formed foraminous electrode 89 which is a freestanding member edge supported by a perimetric frame 91 positioned relative to the bottom 93 of the coating bath container.
  • the container which has a closed sidewall 92 upstanding from the bottom portion 93 and an open top 94, is of a size whereof the lateral dimensions are larger than those of the mask member to facilitate positioning of the mask and allow for unimpeded circulation of the coating suspension therein. There is, for example, an approximate two inch spacing between the mask and the sidewalls of the container 87 to foster circulation of the suspension therein.
  • the container 87 Within the container 87 are a plurality of spaced-apart agitation means 113, such as ultrasonic transducers or fluid or mechanical vibrators, which are operated to continue the suspension and expedite flow of the suspended particles through the foraminous elec trode.
  • spaced apart out-flow means 115 which one is shown, maintain the desired level of suspension within the container.
  • the several outflow means discharge into a collector reservoir 117, from which the coating suspension is conveyed by a pumping means 1 19 and discharge piping 121 back to the supply reservoir 105 to form a recirculation system.
  • the liquid-holding container 87 has at least one outlet valving means 123 located in the bottom of the container to facilitate drainage and cleaning.
  • the coating procedure is accomplished by invertedly positioning the domed apertured pattern member 75 of the shadow mask in the first coating bath 79 to a predetermined depth in spaced relationship to the aforedescribed foraminous electrode structure 89 as for example in the order of 0.5 to 1.0 inch spacing. Movement is initiated and maintained within the electrophoretic bath by activation of the plural agitation means 113 to provide homogeneity and circulation of the suspension.
  • power supply 101 is then activated by switching means 103 to apply an electrical potential of, for example, 100 to 200 volts to establish a coating application current of a sufficiency, such as two amperes, between the mask 73 (cathode) and the electrode 89 (anode); the voltage being dependent upon the interelectrode anode-to-cathode spacing therebetween.
  • An electrical potential activation period of from one to two minutes, effects a semiporous cataphoretic deposition of from 1.0 to 1.5 mils of particulate material, such as zinc oxide, on the pattern portion of the mask which temporarily modifies or reduces the size of the apertures therein.
  • the relationship between mask-coating thickness and anode-to-cathode spacing is an important consideration during the electrophoretic coating procedure.
  • the current density varies in accordance with the inter-electrode spacing, the closer the electrodes, the thicker the coating.
  • the cathodeto-anode spacing at x is greater than at w; therefore, the thickness of the coating deposition at location x is less than coating thickness at w. Since the coated mask thickness evidences a gradually increasing thickness from x to w, the gradient of aperture dimensions exhibits a gradual temporary reduction in size.
  • the upward inflowing first coating suspension material is moved substantially through the foraminous electrode 89 in an expansive substantially uniform gentle Welling manner which enhances the uniformity of the suspension material reaching the mask.
  • the coating suspension supply means includes a peripheral trough-like open channel 141 which is likewise affixed to the exterior of the liquid holding container 87.
  • the outer wall 149 of the channel is of a height greater than that of the closed sidewall 92 of the container which, in this embodiment, determines the depth of the coating bath.
  • the coating suspension 79 is moved in a manner reverse to that previously described from the collector reservoir 117 by pump means 119 through supply piping 111' into the peripheral open channel 114, from whence it overflows into the container 87.
  • the outflow of the suspension is down through the infundibular bottom into the collector reservoir relative thereto in accordance with the recirculation system shown.
  • the improved apparatus incorporates features to smooth out suspension flow patterns, maintain a homogeneous suspension dispersion, facilitates addition of coating replenishment, provides for circulation of suspension to the work area on a continuous basis, and thereby enhances the uniformity of coating deposition in a manner that is expeditiously, consistently and satisfactorily reproducible from a production concept.
  • Apparatus for applying an electrophoretic coating to substantially the pattern portion of a formed and strengthened pattern mask member having peripheral support means attached thereto, said mask being subsequently utilized in forming the patterned screen structure of a color cathode ray tube, said apparatus accomodating said pattern mask comprising: a
  • liquid-holding container adapted to hold an electrophoretic coating suspension comprising a formed bottom portion with an encompassing side formation and an open-top and having lateral dimensions sufficient to accommodate said mask member;
  • a foraminous metallic electrode member immersed in said electro-phoretic coating suspension said electrode member being positioned relative to the bottom of said container in a manner to provide for the free circulation of said coating suspension through the foraminous openings in said electrode, the foraminous portion of said electrode member being shaped relative to the contour of said mask pattern portion to provide predetermined spacing therebetween;
  • agitation means oriented in said coating suspension to initiate movement of said coating suspension to provide homogeneity therein and said circulation 'thereof;
  • a direct current voltage source connected to supply an electrical coating potential between said electrode and said mask
  • Apparatus for applying an electrophoretic coating to a pattern mask member according to claim 1 wherein said liquid-holding container has coating suspension supply means and outflow means associated with reservoir and pump means to provide a substantially continuous flow of coating suspension upon activation of said pump means.
  • Apparatus for applying an electrophoretic coating to a pattern mask member according to claim 11 wherein said coating suspension supply means includes a peripheral trough-like channel affixed to the exterior of said liquid-holding container in a manner to faciliing to a pattern mask member according to claim 11 wherein said coating reservoir means has agitation means positioned therein to promote the homogeneous dispersion of the solids in said coating suspension.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US00310704A 1972-11-30 1972-11-30 Apparatus for coating a pattern mask for use in forming a color crt screen structure Expired - Lifetime US3764514A (en)

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US31070472A 1972-11-30 1972-11-30

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US (1) US3764514A (fi)
BE (1) BE805860A (fi)
CA (1) CA1020117A (fi)
DE (1) DE2359005C3 (fi)
FR (1) FR2209205B3 (fi)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3863086A (en) * 1972-11-30 1975-01-28 Gte Sylvania Inc Coated pattern mask for use in forming a color CRT screen structure and method for coating the mask
US5531880A (en) * 1994-09-13 1996-07-02 Microelectronics And Computer Technology Corporation Method for producing thin, uniform powder phosphor for display screens

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851408A (en) * 1954-10-01 1958-09-09 Westinghouse Electric Corp Method of electrophoretic deposition of luminescent materials and product resulting therefrom
US3070441A (en) * 1958-02-27 1962-12-25 Rca Corp Art of manufacturing cathode-ray tubes of the focus-mask variety
US3321657A (en) * 1962-12-18 1967-05-23 American Optical Corp Electrostatic printing cathode ray tube with conducting wires in face plate
US3360450A (en) * 1962-11-19 1967-12-26 American Optical Corp Method of making cathode ray tube face plates utilizing electrophoretic deposition
US3525679A (en) * 1964-05-05 1970-08-25 Westinghouse Electric Corp Method of electrodepositing luminescent material on insulating substrate

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851408A (en) * 1954-10-01 1958-09-09 Westinghouse Electric Corp Method of electrophoretic deposition of luminescent materials and product resulting therefrom
US3070441A (en) * 1958-02-27 1962-12-25 Rca Corp Art of manufacturing cathode-ray tubes of the focus-mask variety
US3360450A (en) * 1962-11-19 1967-12-26 American Optical Corp Method of making cathode ray tube face plates utilizing electrophoretic deposition
US3321657A (en) * 1962-12-18 1967-05-23 American Optical Corp Electrostatic printing cathode ray tube with conducting wires in face plate
US3525679A (en) * 1964-05-05 1970-08-25 Westinghouse Electric Corp Method of electrodepositing luminescent material on insulating substrate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3863086A (en) * 1972-11-30 1975-01-28 Gte Sylvania Inc Coated pattern mask for use in forming a color CRT screen structure and method for coating the mask
US5531880A (en) * 1994-09-13 1996-07-02 Microelectronics And Computer Technology Corporation Method for producing thin, uniform powder phosphor for display screens

Also Published As

Publication number Publication date
CA1020117A (en) 1977-11-01
BE805860A (fr) 1974-04-10
DE2359005A1 (de) 1974-06-06
DE2359005C3 (de) 1978-03-09
DE2359005B2 (de) 1977-07-14
FR2209205B3 (fi) 1976-10-15
FR2209205A1 (fi) 1974-06-28

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Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.,

Free format text: ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981.;ASSIGNOR:GTE PRODUCTS CORPORATION A DE CORP.;REEL/FRAME:003992/0284

Effective date: 19810708

Owner name: NORTH AMERICAN PHILIPS CONSUMER ELECTRONICS CORP.

Free format text: ASSIGNS ITS ENTIRE RIGHT TITLE AND INTEREST, UNDER SAID PATENTS AND APPLICATIONS, SUBJECT TO CONDITIONS AND LICENSES EXISTING AS OF JANUARY 21, 1981.;ASSIGNOR:GTE PRODUCTS CORPORATION A DE CORP.;REEL/FRAME:003992/0284

Effective date: 19810708