US3814966A - Post-deflection acceleration type color cathode-ray tube - Google Patents

Post-deflection acceleration type color cathode-ray tube Download PDF

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Publication number
US3814966A
US3814966A US00286914A US28691472A US3814966A US 3814966 A US3814966 A US 3814966A US 00286914 A US00286914 A US 00286914A US 28691472 A US28691472 A US 28691472A US 3814966 A US3814966 A US 3814966A
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United States
Prior art keywords
shadow mask
ray tube
color cathode
graphite
secondary electron
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
US00286914A
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English (en)
Inventor
A Misumi
T Kasai
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.)
Hitachi Ltd
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Hitachi Ltd
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Filing date
Publication date
Priority claimed from JP8088571U external-priority patent/JPS4838761U/ja
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
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Publication of US3814966A publication Critical patent/US3814966A/en
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/80—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching
    • H01J29/81—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching using shadow masks
    • 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

  • Such graphite layers may also be applied on the phosphor screen and on the inner surface of the funnel portion of the tube to further improve the secondary electron preventing effect 3 Claims, 2 Drawing Figures POST-DEFLECT ION ACCELERATION TYPE COLOR CATHODE-RAY TUBE creased for improved brightness of the phosphor' field is produced between the shadow mask and the phosphor screen to form an electron lens in the vicinity of the shadow mask for reducing the diameter of the electron beams which strike the phosphor screen.
  • Color cathode-ray tubes of this type have such a disadvantage that the secondary electrons produced by electrons striking the phosphor screen, the shadow mask and/or the inner surface of the funnel portion are accelerated by the accelerating field produced between the phosphor screen and the shadow mask andthe thus accelerated secondary electrons impinge on the phosphor screen, deteriorating reproduced color images and hence the color purity.
  • An object of the present invention is to provide a post-deflection acceleration type color cathode'ray tube which is free from the above-mentioned drawbacks and which comprises electron gun means, a shadow mask havingthroughholes therein and ametalbacked phosphor screen, wherein a secondary electron preventing layer. made of graphite is provided at least on that surface of the shadow mask which faces the electron gun means.
  • FIG. 1 is across-sectional view of a portion of the face panel of a cathode-ray tube
  • FIG. 2 is a cross-sectional view of a portion of the shadow mask positioned adjacent the phosphor screen of the cathode ray tube.
  • numeral 1 in FIG. 1- designates a panel portion comprising a panel plate 2, a phosphor screen 3 which is formed on the inner surface of the panel plate 2, and ametal backing layer of aluminum, for example, which is coated on the phosphor screen 3.
  • Numeral 4 designates a layer. of graphite coated on the metal-backing layer 3a.
  • Numeral Sin FIG. 2 designates a shadow mask portion includinga shadow mask 6 arranged at a given distance from the phosphor screen 3 and containing a number of holes formed therethrough.
  • Numeral 7 generally designates a coating of graphite and involves, in the illustratedembodiment, layer 711 coated on that surface 6a of the shadow mask 6 which faces the electron gun means (not shown), layer 712 coated on. the other surface 6b of the shadow mask 6 which faces the panel portion 1 and layer 7c coated on the inner surface 60 of the through hole in the shadow mask 6.
  • Coating of the graphite layers 4 and 7 may be performed by dispersing flake-like graphite particles having a particle diameter of about 1p. into a dispersion medium such as water or ethyl alcohol containing some organic binder such as ethyl cellulose, methyl cellulose or the like, the dispersion concentration of the graphite particles being about 1 to 10 percent by weight, preferably 6 to 8 percent by weight, and then spraying the thus obtained dispersion system by means of, for example, a spray gun onto the metal-backing layer 311 on the phosphor screen 3 and the electron gun-side face 6a and panel portion side face 6b of the shadow mask 6 to form thereon graphite layers having a uniform thickness of about 3 to 20;!
  • a dispersion medium such as water or ethyl alcohol containing some organic binder such as ethyl cellulose, methyl cellulose or the like
  • the dispersion concentration of the graphite particles being about 1 to 10 percent by weight, preferably 6 to 8 percent
  • the density of the thus obtained layer 7 is about 0.3 to 2.25 g/cm with the binder having been removed by a heat treatment.
  • the heat treatment may be, for example, at 450C for 1 hour in air. If the particle size of graphite particles and the density and thickness of the resultant graphite layer deviate considerably from these limits, the adhesion of the graphite particles and the strength of the resultinglayers would be reduced. Also, the secondary electron preventing effect would be reduced, if the density and thickness of the graphite layers deviate considerably from the above-mentioned limits.
  • the above-mentioned limits on the concentration of the dispersion system ensure a maximum efficiency of the spraying operation.
  • the graphite layers 4, 7a, 7b and 7c coated in the mannerdescribed can considerably reduce the degree of deterioration of the color purity. This effect can be further improved, if another graphite layer is also applied on the inner surface of the funnel portion (not shown)..lnthis case, the graphite layer on the inner surface of the funnel portion does not require a strict uniformity in'thickness such as is required for the graphite layers 4, 7a, 7b and 70, so that it may be applied by a brush.
  • Any graphite layer having a density less than the range of density defined for the graphite layer of the present invention is inferior in its adhesion as well as its coating strength and thus it cannot be applied in practi cal use.
  • the thickness of a. graphite layer is considerably less than the lower limitof the above-mentioned range of thickness for the graphite layer, its secondary electron preventing effect is reduced, whereas if the thickness is considerably more than the upper limit of the range, its adhesion is reduced.
  • the secondary electron preventing layers have been provided on the metal-backed phosphor screen and on both surfaces of the shadow mask and the walls of the holes therein, the intended object can be practically attained when a secondary electron preventinglayer is provided at least on that surface of the shadow mask which faces the electron gun means.
  • a secondary electron preventing layer is provided on the phosphor screen, a relatively thin thickness in the rangeof thickness defined according to the present invention may be effectively utilized for purposes of improved brightness.
  • the thickness and the density of said secondary electron preventing layer being in the ranges of about 3 20 1. and about 0.3 2.25 g/cm, respectively.

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  • Electrodes For Cathode-Ray Tubes (AREA)
US00286914A 1971-09-08 1972-09-07 Post-deflection acceleration type color cathode-ray tube Expired - Lifetime US3814966A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP8088571 1971-09-08
JP8088571U JPS4838761U (cs) 1971-09-08 1971-09-08

Publications (1)

Publication Number Publication Date
US3814966A true US3814966A (en) 1974-06-04

Family

ID=26421844

Family Applications (1)

Application Number Title Priority Date Filing Date
US00286914A Expired - Lifetime US3814966A (en) 1971-09-08 1972-09-07 Post-deflection acceleration type color cathode-ray tube

Country Status (5)

Country Link
US (1) US3814966A (cs)
CA (1) CA959910A (cs)
DE (1) DE2243646A1 (cs)
FR (1) FR2152731B1 (cs)
GB (1) GB1404659A (cs)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4422005A (en) * 1980-07-09 1983-12-20 U.S. Philips Corporation Channel plate electron multiplier

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2758002B1 (fr) * 1996-12-27 2004-07-02 Thomson Tubes Electroniques Systeme de visualisation avec ecran d'observation luminescent

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US3035203A (en) * 1959-12-11 1962-05-15 Sylvania Electric Prod Cathode-ray tube
US3475639A (en) * 1967-01-19 1969-10-28 Television Cie Franc De Tricolor cathode ray tube having porous graphite layer on aluminum screen coating

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878411A (en) * 1955-03-21 1959-03-17 Chromatic Television Lab Inc Color television display screen
US3035203A (en) * 1959-12-11 1962-05-15 Sylvania Electric Prod Cathode-ray tube
US3475639A (en) * 1967-01-19 1969-10-28 Television Cie Franc De Tricolor cathode ray tube having porous graphite layer on aluminum screen coating

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4422005A (en) * 1980-07-09 1983-12-20 U.S. Philips Corporation Channel plate electron multiplier

Also Published As

Publication number Publication date
FR2152731A1 (cs) 1973-04-27
CA959910A (en) 1974-12-24
FR2152731B1 (cs) 1976-03-12
DE2243646A1 (de) 1973-03-22
GB1404659A (en) 1975-09-03

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