EP0898295B1 - Procédé de fabrication d'une couche pour un goujon de contact - Google Patents

Procédé de fabrication d'une couche pour un goujon de contact Download PDF

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Publication number
EP0898295B1
EP0898295B1 EP98402061A EP98402061A EP0898295B1 EP 0898295 B1 EP0898295 B1 EP 0898295B1 EP 98402061 A EP98402061 A EP 98402061A EP 98402061 A EP98402061 A EP 98402061A EP 0898295 B1 EP0898295 B1 EP 0898295B1
Authority
EP
European Patent Office
Prior art keywords
coating
solution
resin
acrylic resin
stud
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP98402061A
Other languages
German (de)
English (en)
Other versions
EP0898295A1 (fr
Inventor
Ricky Shah
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LG Electronics Inc
Original Assignee
LG Electronics Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LG Electronics Inc filed Critical LG Electronics Inc
Publication of EP0898295A1 publication Critical patent/EP0898295A1/fr
Application granted granted Critical
Publication of EP0898295B1 publication Critical patent/EP0898295B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/88—Vessels; Containers; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/92—Means providing or assisting electrical connection with or within the tube
    • H01J2229/925—Means providing or assisting electrical connection with or within the tube associated with the high tension [HT], e.g. anode potentials

Definitions

  • This invention relates in general to color television picture tubes, and in particular to an improved stud coating composition and method for providing an electrical path between the color picture tube shadow mask and screened faceplate.
  • the color television cathode ray picture tube comprises a glass bulb, consisting of a funnel and a faceplate with the faceplate sealed to the flared end of the funnel.
  • An electron gun is mounted in the neck portion of the funnel to provide one or more electron beams.
  • the faceplate has a nearly flat inner surface upon which is deposited groups of phosphors that are excited by the electron beams.
  • the shadow mask provides color selection by masking groups of the phosphors so that they are excitable by only one of the electron beams.
  • the shadow mask is attached in a precise relationship with the faceplate by means of a plurality of suspension springs which detachably engage metal studs that extend from the faceplate.
  • An electrically conductive coating of colloidal graphite is applied to the internal surface of the funnel and has a high voltage applied thereto through an anode button in the funnel wall.
  • the electrical path for accomplishing this comprises one or more springs that extend from.the shadow mask into engagement with the funnel coating.
  • the anode potential on the shadow mask is conducted to the aluminum film through the shadow mask susponsion springs and the metal support studs.
  • the metal support studs are painted with a conductive "moustache" that extends to the aluminum film.
  • the material comprising the conductive moustache is commonly referred to as stud coating.
  • a prior art conductive material that formerly was in extensive use as a stud coating comprises a water-soluble silicate in a form suitable for application by a brush.
  • the water was driven off in a subsequent tube baking process, leaving a hard, electrically conductive film between the studs and the aluminum film.
  • the water based solutions commonly-contained either potassium silicate or sodium silicate as a binder and did not always "wet" properly nor adhere to components. Consequently, fragments of the coating often flaked off the studs and glass area and blocked one or more apertures in the shadow mask which often resulted in an unacceptable tube. Such particles in the gun area could also result in interelectrode arcing and/or cathode poisoning.
  • the water-soluble coatings required an extra baking cycle after aluminizing and before applying the stud Dag.
  • the glass frit type of stud coating described in the above-discussed patents manifests a deficiency during a breakdown or interruption in the production process. Specifically, a problem arises when tubes are subjected to the high Lehr temperatures for an extended time period, such as occurs when the production line stops. The lead oxide in the glass frit reacts with the carbon in the graphite to form carbon dioxide and lead and destroys the conductivity of the stud coating. In many instances close attention to Lehr heat control during line shutdowns can obviate the problem, although during extensive shutdowns, the difficulty may still be present.
  • the problem is often compounded by the fact that a sufficient amount of the stud coating may remain intact to enable the tube to pass final inspection and testing although it may be prone to recurrent arcing and ultimate failure in the field. While the problem is not severe in terms of numbers, it is catastrophic to the picture tube and an obvious expense and inconvenience to the consumer, since it may not show up during routine testing of the picture tube.
  • a principal object of the invention is to provide an increase in the performance reliability of color cathode ray tubes.
  • Another object of the invention is to provide a reduced manufacturing cost for color cathode ray tubes.
  • a further object of the invention is to provide a cathode ray tube with minimal stud coating-related arcing.
  • color cathode ray tubes have a phosphor bearing imaging faceplate overlaid successively with a lacquer film and an aluminum film.
  • a shadow mask is secured next to the faceplate by a plurality of-metallic studs extending from the faceplate.
  • An electrical bridge is provided between the shadow mask and the aluminum film via the studs and a stud coating to maintain the aluminum film at anode potential.
  • the shadow mask is electrically connected to the anode voltage that exists on the coating inside the funnel by springs that bridge the nonconductive glass frit seal between the picture tube faceplate and the funnel.
  • An improved bake-hard enable solution according to the invention for providing the stud coating electrical bridge or moustache as claimed comprises essentially a mixture of graphite particles in the micron-sized range.
  • the particles are In suspension in an evaporable solvent for the lacquer film.
  • the suspension includes a thickening agent in an amount sufficient to produce a paintable viscosity for application by a brush.
  • the solution may have a viscosity in the range of 200.8 Pa ⁇ s (200800 centripoises) and preferably about 0.55 Pa ⁇ s (550 centripoises) After baking, the solution may have an electrical resistance in the range of 100 to 500 ohms per square.
  • the electrically conductive stud coating of the invention may be compounded as follows (produces 3.75 l (one gallon). Equivalent materials supplied by other suppliers may be used.
  • the coating preparation should be performed in an area of adequate ventilation with suitable precautionary procedures, such as wearing rubber gloves, respirator masks, lab coats, hair nets and shoe covers being followed by involved personnel. Care must also be taken because of the flammability of the N-butyl acetate and the resin binder solution.
  • the stud coating prepared and used according to the invention eliminates the problem identified above in connection with the use of a glass frit based stud coating.
  • a major leature of the new stud coating is its flexibility (after processing) which enhances its resistance to flaking. Additionally, the inventive stud coating is less costly and still enables the benefit of not requiring an extra bake cycle for the picture tube.
  • the prior art frit-based stud coating was applied to the stud and aluminum film and subjected to a temperature of 450 degrees Centigrade for a period of two hours.
  • the resistivity of the coating rose from 300 ohms to 73.000 ohms.
  • the resistivity remained at 300 ohms.

Landscapes

  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Paints Or Removers (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)

Claims (8)

  1. Procédé de fabrication d'une couche d'enduction de goujon comprenant les étapes de :
    fournir un mélange de graphite colloïdal ;
    préparer une solution de résine acrylique capable de pénétrer le film de laque de la dalle d'un tube à image aluminé ;
    préparer une solution liante de résine ; et
    malaxer les solutions et le mélange de graphite.
  2. Procédé selon la revendication 1, dans lequel la solution de résine acrylique est préparée en dissolvant une résine acrylique dans le butylglycol.
  3. Procédé selon la revendication 2, dans lequel la solution liante de résine est préparée en faisant un mélange homogène de butylglycol, d'acétate de N-butyle et de résine liante.
  4. Procédé selon la revendication 3, dans lequel le pourcentage en poids de la solution d'enduction de goujon est approximativement :
    16% de graphite colloïdal ;
    14% de résine (liant) ;
    5% de résine acrylique ;
    15% d'acétate de N-butyle ; et
    50% de butylglycol.
  5. Couche d'enduction de goujon pour faire une connexion électrique entre les goujons et le film d'aluminium dans la dalle d'un tube à image couleur, comprenant :
    du graphite colloïdal dispersé dans une solution de résine acrylique et une solution liante de résine qui est capable de pénétrer le film de laque sous ledit film d'aluminium ;
    les solvants dans ladite couche d'enduction étant éliminé par étuvage avec ladite couche de laque lors d'une opération d'étuvage du tube et ladite connexion conductrice restant flexible pour résister à l'écaillage.
  6. Couche d'enduction selon la revendication 5, dans laquelle ladite solution de résine acrylique comprend une résine acrylique dissoute dans une solution de butylglycol.
  7. Couche d'enduction selon la revendication 6, dans laquelle ladite solution liante de résine comprend une résine liante, de l'acétate de N-butyle et du butylglycol.
  8. Procédé selon la revendication 7, dans lequel les pourcentages en poids de ladite solution d'enduction sont approximativement :
    16% de graphite colloïdal ;
    14% de résine (liant) ;
    5% de résine acrylique ;
    15% d'acétate de N-butyle ; et
    50% de butylglycol.
EP98402061A 1997-08-15 1998-08-14 Procédé de fabrication d'une couche pour un goujon de contact Expired - Lifetime EP0898295B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US91290997A 1997-08-15 1997-08-15
US912909 1997-08-15

Publications (2)

Publication Number Publication Date
EP0898295A1 EP0898295A1 (fr) 1999-02-24
EP0898295B1 true EP0898295B1 (fr) 2004-04-21

Family

ID=25432681

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98402061A Expired - Lifetime EP0898295B1 (fr) 1997-08-15 1998-08-14 Procédé de fabrication d'une couche pour un goujon de contact

Country Status (7)

Country Link
EP (1) EP0898295B1 (fr)
JP (1) JP3108406B2 (fr)
KR (1) KR100266622B1 (fr)
CN (1) CN1111572C (fr)
DE (1) DE69823284T2 (fr)
ID (1) ID21510A (fr)
TW (1) TW410359B (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1514828A1 (de) * 1965-06-24 1970-01-08 Telefunker Patentverwertungsgm Elektronenroehre
US4301041A (en) * 1979-10-22 1981-11-17 Zenith Radio Corporation Method and solution for conductive coating for use in cathode ray tubes
US5156770A (en) * 1990-06-26 1992-10-20 Thomson Consumer Electronics, Inc. Conductive contact patch for a CRT faceplate panel

Also Published As

Publication number Publication date
DE69823284T2 (de) 2005-05-19
KR19990023600A (ko) 1999-03-25
CN1111572C (zh) 2003-06-18
DE69823284D1 (de) 2004-05-27
CN1212980A (zh) 1999-04-07
EP0898295A1 (fr) 1999-02-24
KR100266622B1 (ko) 2000-09-15
JPH11135012A (ja) 1999-05-21
JP3108406B2 (ja) 2000-11-13
TW410359B (en) 2000-11-01
ID21510A (id) 1999-06-17

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