EP0655767A1 - Verhinderung der Elektronverfarburg von Glass - Google Patents

Verhinderung der Elektronverfarburg von Glass Download PDF

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Publication number
EP0655767A1
EP0655767A1 EP94118103A EP94118103A EP0655767A1 EP 0655767 A1 EP0655767 A1 EP 0655767A1 EP 94118103 A EP94118103 A EP 94118103A EP 94118103 A EP94118103 A EP 94118103A EP 0655767 A1 EP0655767 A1 EP 0655767A1
Authority
EP
European Patent Office
Prior art keywords
window
film
glass
accordance
cathode ray
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.)
Withdrawn
Application number
EP94118103A
Other languages
English (en)
French (fr)
Inventor
Nicholas Francis Borrelli
Kenneth Russell Salisbury
Donald John Lopata
Ahmad Sarhangi
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.)
Corning Inc
Original Assignee
Corning 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 Corning Inc filed Critical Corning Inc
Publication of EP0655767A1 publication Critical patent/EP0655767A1/de
Withdrawn legal-status Critical Current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
    • 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
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/28—Luminescent screens with protective, conductive or reflective layers

Definitions

  • alkali-free glasses do not brown under an equivalent amount of electron beam dose, they are not suitable for melting and forming the panel glass for CRT.
  • United States Patents 3,573,955 and 3,725,710 propose providing a thin, hard, transparent layer containing no more than 1% of easily reduced metal oxides between the window portion of a CRT and a phosphor layer inside the window leaching out lead and ion exchanging potassium ions for sodium, or other means of coating the window to provide the protective layer.
  • the present invention provides a practical method of providing protection, in modern cathode ray tubes, against discoloration due to electron bombardment, and meeting the various concerns described above, and providing a greater flexibility in the procedure for applying a protective film. It further provides a CRT having improved protection against discoloration (browning) due to electron bombardment.
  • the product aspect of the invention resides in a cathode ray tube comprising an envelope having a glass window portion capable of being discolored upon bombardment by high energy electrons, means mounted in the tube to produce a stream of high energy electrons and to direct the stream toward the window, a phosphor layer on the window and a thin oxide film between the window and the phosphor layer, the thin film being alkali-free, free of ions inherently reducible by electron bombardment, and of sufficient thickness and density to prevent any substantial electron penetration to the window.
  • the invention further resides in a method of preventing discoloration of glass by high energy electron bombardment which comprises providing a thin oxide layer on the surface of the glass that would otherwise be impacted by electrons, the layer being alkali-free, containing no ions inherently reducible by electron bombardment, having a thickness larger than the depth of penetration of the electron beam at a given acceleration potential, and having insufficient inherent color to interfere with desired color coordinate specification.
  • FIGURE 10 is a side view in cross-section. It represents a modified version of a typical cathode ray tube, designated by the numeral 10 and illustrating the present invention.
  • the envelope of cathode ray tube 10 includes a window, or faceplate, 12, a funnel portion 14 and a neck portion 16.
  • An electron gun 18, shown diagrammatically, is sealed in neck 16.
  • a phosphor layer 20 has heretofore been applied over the inside surface of window 12.
  • an oxide film 22 is applied on the inside surface of window 12 intermediate phosphor layer 20 and window 12.
  • Our invention provides a thin film of a pure oxide of sufficient thickness to substantially block penetration of electrons to the panel glass.
  • the film must not itself be subject to the discoloration mechanism. Nor can it exhibit any significant inherent color.
  • the layer must be:
  • the layer must be alkali-free to ensure that no mobile, positively-charged, ionic species is available to neutralize incoming electrons.
  • easily reducible ions such as lead, titanium, and bismuth, must be absent from the film. This avoids possible direct reduction by electron bombardment.
  • the fourth requirement minimal electron penetration into the panel glass, insures minimal reduction of lead through the normal browning mechanism.
  • Table I lists the maximum film thickness values predicted by the Spear formula for representative materials satisfying the first three requirements listed above. These values are determined for current and anticipated accelerating potentials. TABLE I Material Thickness, ⁇ m 20 kV 30 kV 40 kV SiO2 3 6 11 Al2O3 1.6 3.6 6.4 ZnO 1.1 2.6 4.6 SnO2 0.9 2.0 3.7 ITO (In2O3,ySnO2) 0.9 2.0 3.7
  • ITO is a commonly used designation for a dense, electroconducting film comprised of indium oxide (In2O3) doped with a few percent, e.g. 4%, of tin oxide. This material is particularly desirable for present purposes since it may also be applied for conducting purposes to bleed off excess charge. Thus, the art is familiar with the material and methods for its application on glass.
  • An ITO film of about 0.2 micron thickness is customarily used on devices such as LCD panels.
  • Test samples were prepared to determine the validity of the estimates.
  • Films were deposited by both plasma-assisted chemical vapor deposition (PCVD) and thermal-assisted chemical vapor deposition.
  • PCVD plasma-assisted chemical vapor deposition
  • the former can be carried out at 30-100°C, while the latter requires a temperature in the range of 400-500°C.
  • the former is employed if a substrate is temperature sensitive.
  • the latter is preferred since it gives a film with higher density and purity.
  • the oxide precursor may be a organo-metallic compound.
  • alumina film for example, triethylaluminum, triisobutylaluminum, trimethylamine alane, or aluminum chloride may be employed.
  • the source compound is oxidized to alumina and organic by-product gases. The latter are exhausted by vacuum while the alumina is deposited on the glass substrate.
  • Test samples were prepared in the manner described above. Oxides were deposited on discs cut from a commercial glass used to produce CRT windows. The discs were 4.8 cm (1 7/8") diameter and 11.43 mm thickness, and were ground and polished on both surfaces for film application.
  • a film thickness that provides a transmittance value of at lest 80% in this test should provide adequate protection.
  • a transmittance of 90% would be preferable.
  • the results recorded in TABLE II are qualitatively consistent with the predicted values in TABLE I. However, they bear out the earlier suggestion that a film thickness substantially less than the predicted maximum thickness will provide adequate protection. A film thickness necessary to protect to the same level at an accelerating potential of 30 kV would be approximately twice the values given in TABLE II for 20 kV exposure.
  • the relationship of the film thickness, and the ease and versatility of deposition, are very significant.
  • the film thickness is ⁇ one micron, the films adhere well. Also, adherence is not influenced by the thermal expansion mismatch between the film and the glass.
  • practical methods of coating large panels such as sol-gel techniques, are limited to thin films. It is considered equally important to find the right film for browning protection, and to provide a practical and inexpensive method of depositing the film on large panels. By employing a film of thickness no greater than about one micron, this is practical to achieve.

Landscapes

  • Surface Treatment Of Glass (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
EP94118103A 1993-11-29 1994-11-17 Verhinderung der Elektronverfarburg von Glass Withdrawn EP0655767A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US158228 1988-02-19
US15822893A 1993-11-29 1993-11-29

Publications (1)

Publication Number Publication Date
EP0655767A1 true EP0655767A1 (de) 1995-05-31

Family

ID=22567188

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94118103A Withdrawn EP0655767A1 (de) 1993-11-29 1994-11-17 Verhinderung der Elektronverfarburg von Glass

Country Status (3)

Country Link
EP (1) EP0655767A1 (de)
JP (1) JPH07262932A (de)
KR (1) KR950015528A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3725710A (en) * 1965-04-17 1973-04-03 Philips Corp Method of making a cathode-ray tube
EP0003551A1 (de) * 1978-02-02 1979-08-22 Siemens Aktiengesellschaft Verfahren zur Herstellung von elektrisch leitenden oder nichtleitenden Schichten für verbesserte Leuchtstoffhaftung auf planen oder in einer Richtung gekrümmten Substraten für Farb-Bildschirme
DE4106640A1 (de) * 1990-03-29 1991-10-02 Mitsubishi Electric Corp Projektionskathodenstrahlroehre

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3725710A (en) * 1965-04-17 1973-04-03 Philips Corp Method of making a cathode-ray tube
EP0003551A1 (de) * 1978-02-02 1979-08-22 Siemens Aktiengesellschaft Verfahren zur Herstellung von elektrisch leitenden oder nichtleitenden Schichten für verbesserte Leuchtstoffhaftung auf planen oder in einer Richtung gekrümmten Substraten für Farb-Bildschirme
DE4106640A1 (de) * 1990-03-29 1991-10-02 Mitsubishi Electric Corp Projektionskathodenstrahlroehre

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ANONYMOUS: "Display Tube with Enhance Luminescence. November 1978.", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 21, no. 6, NEW YORK, US, pages 2587 *

Also Published As

Publication number Publication date
KR950015528A (ko) 1995-06-17
JPH07262932A (ja) 1995-10-13

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