US3475639A - Tricolor cathode ray tube having porous graphite layer on aluminum screen coating - Google Patents

Tricolor cathode ray tube having porous graphite layer on aluminum screen coating Download PDF

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Publication number
US3475639A
US3475639A US685823A US3475639DA US3475639A US 3475639 A US3475639 A US 3475639A US 685823 A US685823 A US 685823A US 3475639D A US3475639D A US 3475639DA US 3475639 A US3475639 A US 3475639A
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US
United States
Prior art keywords
screen
graphite layer
porous graphite
ray tube
cathode ray
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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
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US685823A
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English (en)
Inventor
Jean Pierre Driffort
Pierre Lebel
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Compagnie Francaise de Television SA
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Television Cie Franc De
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Publication date
Application filed by Television Cie Franc De filed Critical Television Cie Franc De
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    • 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
    • H01J29/30—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines
    • H01J29/32—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines with adjacent dots or lines of different luminescent material, e.g. for colour television
    • 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
    • H01J29/185—Luminescent screens measures against halo-phenomena
    • 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

  • This invention relates to color television image tubes which include at least one post-accelerating and postfocusing grid located near the screen.
  • the image definition thus deteriorates and the background of the screen becomes brighter so that the contrast is weaker.
  • the color fidelity and saturation are impaired since the secondary electrons knocked out of the luminescent elements of each of the three primary colors fall back onto elements of any color.
  • the luminescent elements of the screen are generally covered by a very thin aluminum layer, and a small fraction of the primary electrons arriving at the screen are reflected either by the luminescent layer or by the aluminum. These reflected primary electrons act like the secondary electrons and thus also contribute to the development of the halo.
  • the halo can be suppressed or attenuated to some extent by providing the screen with a decelerating layer which absorbs a major part of the energy of the reflected or secondary electrons.
  • a light material is used which has a low coefficient of secodnary electron emission and a high thermal energy evacuation factor, such as graphite.
  • a three-gun, tricolor picture tube having a luminescent screen and a post-focusing grid adjacent the screen, said screen being provided with a thin coating and a decelerating graphite layer deposited on the aluminum coating, wherein the graphite layer is porous and has a density d and a thickness e such that the product d.e is comprised between 2.6 and 5.1, d being expressed in gr./cm. and e in nucrons.
  • the density of the porous graphite layer is comprised between 0.2 and 0.3, while the thickness thereof is comprised between 13 and 17 microns.
  • FIG. 1 illustrates in section the application of the improvement in accordance with the invention to a tricolor image tube with three electron guns.
  • the improved part of the tube includes a post-focusing grid, composed of wires such as 1, 1a, 2, 2a, and a luminescent screen 3 having a plane surface parallel to the grid.
  • the screen 3 comprises, in the order listed: a porous powdered graphite layer 4 between 13 and 17 microns in thickness; a high-reflectivity metal layer 5, preferably aluminum, vaporised on under vacuum and having a thickness of about 5 microns; and tricolor luminescent strips 6, 7, 8, 7 8 etc. arranged on a flat glass plate 9.
  • the electron beams 10, 11, 12 strike the respective strips 6, 7, 8 due to the focusing effect of the screen-grid arrangement.
  • the porous graphite layer 4 is applied to the aluminum layer 5 by spraying on a colloidal suspension of graphite grains in ethyl alcohol.
  • the grain diamteer is in the order of 1 micron.
  • a fihn-forming product which may be a colloidal or a methyl methacrylate, is added.
  • the film-forming product is eliminated subsequently during the normal heat treatment phases in the process of manufacture of the screen, and the carbon combustion residues of this product ensure cohesion between the grains themselves and between the grains and the layer 5.
  • Spraying is effected using a suitable spray gun, and in this phase of the process the contexture of the deposit can be controlled to a large extent by choosing or adjusting the various parameters involved: (a) size of the gun nozzle; (b) nature of the fluid (air, nitrogen, argon, etc.); (c) fluid pressure; (d) size of the graphite grains; (e) concentration of graphite in the suspension; (f) nature of the liquid in which the graphite is in suspension, and of any additional products which may modify the physical and chemical characteristics of the suspension.
  • the thickness of the graphite layer can be adjusted with great accuracy by suitably fixing the duration of the spraying operation for a constant flow of fluid to the spray gun.
  • the Applicants have determined experimentally that the product brilliancexcontrast reaches a maximum when the product thicknessxdensity of the graphite layer has a value between 260 and 510 micrograms/cmfi.
  • the brilliance increases as the density of the graphite layer reduces, but layers having a density below 0.2 gr./cm. do not generally have sufficient uniformity and stability. It has been found that the best results are obtained with a density between 0.2 and 0.3, and a thickness between 13 and 17 microns.
  • the range of densities from 0.2 to 0.3 corresponds in terms of the ratio of volumetric occupation by the porous graphite to a range between 9 and 13%. It is within this range that the porous graphite layer gives the best results.
  • a color TV picture tube including a tricolor luminescent screen, three electron guns each adapted to emit an electron beam toward said screen, and a postfocusing grid located on the path of said electron beams adjacent said screen, said screen being provided with a thin aluminum coating on the side facing said electron guns and a porous graphite layer deposited on said aluminum coating, the density d, whose value lies between 0.2 and 0.3 grams per cubic centimeter, and the thickness e in microns of said porous graphite layer being 4 such that the product d.e is comprised between 2.6 and 5.1.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US685823A 1967-01-19 1967-11-27 Tricolor cathode ray tube having porous graphite layer on aluminum screen coating Expired - Lifetime US3475639A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR91730A FR1515211A (fr) 1967-01-19 1967-01-19 Perfectionnement aux écrans luminescents de tubes de télévision en couleurs
FR126302A FR93385E (fr) 1967-01-19 1967-10-30 Perfectionnement aux écrans luminescents de tubes de télévision en couleurs.

Publications (1)

Publication Number Publication Date
US3475639A true US3475639A (en) 1969-10-28

Family

ID=26174552

Family Applications (1)

Application Number Title Priority Date Filing Date
US685823A Expired - Lifetime US3475639A (en) 1967-01-19 1967-11-27 Tricolor cathode ray tube having porous graphite layer on aluminum screen coating

Country Status (10)

Country Link
US (1) US3475639A (hr)
BE (1) BE707508A (hr)
CH (1) CH459294A (hr)
DE (1) DE1537070A1 (hr)
DK (1) DK124299C (hr)
ES (1) ES348526A1 (hr)
FR (2) FR1515211A (hr)
GB (1) GB1152290A (hr)
NL (1) NL6800398A (hr)
SE (1) SE323983B (hr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814966A (en) * 1971-09-08 1974-06-04 Hitachi Ltd Post-deflection acceleration type color cathode-ray tube
DE2357397A1 (de) * 1972-12-04 1974-06-27 Hitachi Ltd Verfahren zur herstellung eines films zum verhindern von sekundaerelektronenemission und mit einem solchen film ausgestattete farbbildroehre
US3873343A (en) * 1971-09-08 1975-03-25 Hitachi Ltd Method of forming secondary electron emission preventing layer for post-deflection acceleration type color picture tube
US4025661A (en) * 1972-11-13 1977-05-24 Rca Corporation Method of making viewing-screen structure for a cathode-ray tube
US4160187A (en) * 1975-11-05 1979-07-03 Gte Sylvania Incorporated Post-deflection acceleration crt system
US4221990A (en) * 1973-02-14 1980-09-09 Hitachi, Ltd. Phosphor screen for post-focusing type color picture tube
US4353005A (en) * 1976-04-12 1982-10-05 U.S. Philips Corporation Camera tube with mutually insulated, light absorbing particles on gun side of target
US5639330A (en) * 1990-03-14 1997-06-17 Matsushita Electric Industrial Co., Ltd. Method of making an image display element
US11400507B2 (en) * 2016-04-22 2022-08-02 Cosma Engineering Europe Gmbh Method for increasing the plastic deformability of a workpiece using an absorption agent

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3703401A (en) * 1970-12-28 1972-11-21 Rca Corp Method for preparing the viewing-screen structure of a cathode-ray tube
NL7504324A (nl) * 1975-04-11 1976-10-13 Philips Nv Kathodestraalbuis voor het weergeven van gekleurde beelden.
GB2120840A (en) * 1982-05-12 1983-12-07 Philips Electronic Associated Contrast improvement in vacuum image display devices

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2858466A (en) * 1955-11-25 1958-10-28 Westinghouse Electric Corp Method of reducing secondary emission from bombarded surfaces
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US2916664A (en) * 1954-12-06 1959-12-08 Westinghouse Electric Corp Electron discharge device
US3223872A (en) * 1962-08-13 1965-12-14 Paramount Pictures Corp Color screen with electron- and lightabsorptive material separating adjacent color strips

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2916664A (en) * 1954-12-06 1959-12-08 Westinghouse Electric Corp Electron discharge device
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US2858466A (en) * 1955-11-25 1958-10-28 Westinghouse Electric Corp Method of reducing secondary emission from bombarded surfaces
US3223872A (en) * 1962-08-13 1965-12-14 Paramount Pictures Corp Color screen with electron- and lightabsorptive material separating adjacent color strips

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814966A (en) * 1971-09-08 1974-06-04 Hitachi Ltd Post-deflection acceleration type color cathode-ray tube
US3873343A (en) * 1971-09-08 1975-03-25 Hitachi Ltd Method of forming secondary electron emission preventing layer for post-deflection acceleration type color picture tube
US4025661A (en) * 1972-11-13 1977-05-24 Rca Corporation Method of making viewing-screen structure for a cathode-ray tube
DE2357397A1 (de) * 1972-12-04 1974-06-27 Hitachi Ltd Verfahren zur herstellung eines films zum verhindern von sekundaerelektronenemission und mit einem solchen film ausgestattete farbbildroehre
US4221990A (en) * 1973-02-14 1980-09-09 Hitachi, Ltd. Phosphor screen for post-focusing type color picture tube
US4160187A (en) * 1975-11-05 1979-07-03 Gte Sylvania Incorporated Post-deflection acceleration crt system
US4353005A (en) * 1976-04-12 1982-10-05 U.S. Philips Corporation Camera tube with mutually insulated, light absorbing particles on gun side of target
US5639330A (en) * 1990-03-14 1997-06-17 Matsushita Electric Industrial Co., Ltd. Method of making an image display element
US11400507B2 (en) * 2016-04-22 2022-08-02 Cosma Engineering Europe Gmbh Method for increasing the plastic deformability of a workpiece using an absorption agent

Also Published As

Publication number Publication date
DK124299B (hr) 1972-10-02
DK124299C (da) 1973-02-19
DE1537070A1 (de) 1970-07-30
NL6800398A (hr) 1968-07-22
FR93385E (fr) 1969-03-21
ES348526A1 (es) 1969-06-16
GB1152290A (en) 1969-05-14
SE323983B (hr) 1970-05-19
BE707508A (hr) 1968-04-16
CH459294A (fr) 1968-07-15
FR1515211A (fr) 1968-03-01

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