US3663854A - Shadow-mask having rectangular apertures - Google Patents

Shadow-mask having rectangular apertures Download PDF

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Publication number
US3663854A
US3663854A US10978A US3663854DA US3663854A US 3663854 A US3663854 A US 3663854A US 10978 A US10978 A US 10978A US 3663854D A US3663854D A US 3663854DA US 3663854 A US3663854 A US 3663854A
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United States
Prior art keywords
electron
shadow
electron gun
mask
blue
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
US10978A
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English (en)
Inventor
Asahide Tsuneta
Makoto Ikegaki
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Toshiba Corp
Original Assignee
Tokyo Shibaura Electric Co Ltd
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Filing date
Publication date
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
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Publication of US3663854A publication Critical patent/US3663854A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/20—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours
    • H01J31/201—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode
    • H01J31/203—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode with more than one electron beam
    • H01J31/205—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes for displaying images or patterns in two or more colours using a colour-selection electrode with more than one electron beam with three electron beams in delta configuration

Definitions

  • the electron gun corresponding to blue is smaller in diameter than the remaining electron guns, and the axes of said electron guns are arranged to form an isosceles triangle in such a manner that the electron gun having a small diameter has its axis on the apex of the isosceles triangle.
  • Fluorescent dots upon which electron beams emitted from said electron guns impinge are substantially in the form of thin rectangles or ellipses which extend substantially at right angles to the beam scanning direction. Adjacent to said fluorescent dots is disposed a shadow-mask having a plurality of rectangularly shaped beam passing holes.
  • This invention relates to cathode-ray tubes and more particularly to an improved color cathode-ray tube of the shadow-mask type.
  • a known color cathode-ray tube of this nature disadvantageously produces a dark image picture due to the fact that electron beams emitted from electron guns are mostly impinged upon a shadow-mask and thereby consumed when they pass through beam passing holes formed in the mask so that the beam effectively impinged on a fluorescent surface is of less intensity.
  • the beam passing holes in a prior art tube are circular and electron beams emitted from three electron guns corresponding to red, green and blue are passed through the beam passing holes intersectingly at different angles.
  • the fluorescent surface has three circular'fluorescent dots of red, green and blue for a single beam passing hole at places thereof to be impinged. Beam deflection errors, however, are caused at the edge portions on the fluorescent surface, while at the central portion thereof the electron guns are subjected to physical deformation mainly due to heat, thus causing a shift between places to be impinged by the beams and the fluorescent dots.
  • all-the three electron guns have the same outside diameter and are arranged such that their axes define the apices of a normal (equilateral) triangle.
  • the outside diameter of each electron gun will have to be uniformly reduced thereby to narrow the neck portion of an envelope around which a beam deflec tion device is to be mounted.
  • this reduction in the outside diameter of the electron guns will necessitate a reduction in the outside diameter of electron lenses within the electron guns.
  • the object of this invention is to provide a shadow-mask type color cathode-ray tube in which the transmittivity of electron beams of a shadow-mask can be increased without damaging the color reproduction property, to provide a light image and in which the outside diameter of a neck portion thereof can be minimized without causing spherical aberration, thereby decreasing the beam deflection power.
  • the above object can be attained by the provisions of fluorescent dots shaped substantially in the form of a long, non-circle, namely, a thin or long rectangle or ellipse and which extend in a direction substantially perpendicular to a beam scanning direction, a shadowmask provided with substantially rectangular beam passing holes disposed adjacent to said dots, and an electron gun unit including three electron guns corresponding to red, green and blue wherein said electron gun corresponding to blue is smaller in outside diameter than the rest.
  • the electron guns are arranged in the form of an isosceles triangle with the blue election gun forming the apex of the triangle.
  • FIG. 1 is a schematic perspective view of the color cathoderay tube embodying this invention
  • FIG. 2 is an enlarged plan view showing a part of a shadow mask shown in FIG. 1;
  • FIG. 3 is a similar view showing a part of a fluorescent layer shown in FIG. 1;
  • FIG. 4 is a schematic view showing the arrangement at tip ends of electron guns of a three-electron gun unit shown in FIG. 1;
  • FIG. 5 shows the relative positions of various elements of the cathode-ray tube of this invention.
  • the cathode-ray tube comprises a glass bulb 1 and a shadow-mask 7.
  • the glass bulb 1 comprises a neck portion 2 having therein three electron guns 3a, 3b and 3C corresponding to red, green and blue, a funnel portion 4 connected to said neck portion 2 and extending therefrom in the form of a funnel, and a face plate 5 connected to the open edge of said funnel portion 4 and provided with a fluorescent layer 6 formed of red, green and blue fluorescent dots.
  • the shadowmask 7 is positioned adjacent to the fluorescent layer 6 by means of a supporting frame 11 supported by a supporting member (not shown) and includes a plurality of beam passing holes 8 of such a shape as will be described later. Although not shown, a beam deflection device is provided on the outer circumference of the neck portion 2.
  • each electrode of the electron guns 3a and'3b corresponding to red and green has been varied in diameter from the electrode of the electron gun 3c for blue. More particularly, the electrode of the electron gun 30 has been formed to have a diameter smaller than that of each electrode of the remaining electron guns.
  • the electron guns have been arranged in such a manner that their axes define a non-equilateral triangle, namely an isosceles triangle having its apex corresponding to the axis of the electrode of the electron gun 3c for blue. It has been found that, with the arrangement above described, the electron guns may be disposed in the neck portion 2 of a diameter sufiiciently small not to substantially increase spherical aberration and to decrease the deflection power.
  • the electron gun 3b in charge of green gives great influence on the resolution of a color picture, and red tends to become conspicuous when the electron beam causes an aberration.
  • the reason for forming the electrode of the electron gun 3c (blue) to have a smaller diameter than those of the other electron guns is due to the fact that its influences on resolution and aberration are relatively inconspicuous as compared with those for red and green.
  • a is the horizontal pitch of the beam passing holes 8 in the shadow-mask
  • d is the horizontal length thereof
  • e is the vertical length thereof.
  • FIG. 3 illustrates fluorescent dots R, 100 and 108 where:
  • f is the spacing with respect to the horizontal direction (beam scanning direction) between the two given fluorescent dots
  • a1 is the pitch of the dots for the same color with respect to the horizontal direction
  • d1 is the horizontal length of the dots.
  • the dots 6 and the holes 8 may be thin ellipses other than rectangles.
  • the distance mentioned can be represented in terms of the distance Sx of the deflected position of the electron beams within the deflection plane from the axis of the electron gun unit, by denoting the distance between the tip end of the electron gun and the fluorescent screen 6 as Lsg, the distance in the line scanning direction between the tip portion of the electron gun and the axis of the electron gun unit as Sgx, the distance between the beam deflection position of the deflection device and the screen 6 as L, the distance between the shadow-mask and the screen 6 as q, the pitch of the holes 8 in the shadow-mask as a, and further by denoting, as described above, the horizontal spacing between the fluorescent dots shown in FIG. 3, for example, between the dots 10B and 10R as f.
  • the axis of the electron gun electrode Bg in charge of blue is generally located on the Y-axis extending in the direction substantially perpendicular to said direction of beam scanning and has a diameter smaller than those of the other electrodes Rg and Gg, so that the electrode Bg with its axis located on the Y-axis may be disposed in a position closer to the other two electrodes in such a manner that the axes of the respective electrodes take the apices of an isosceles triangle, with the result that the overall outside diameter of the electron gun unit can be reduced.
  • the electron gun 30 (blue) may be about 7 mm in outside diameter and each of the electron guns 3a and 3b may have an outside diameter of about 10 mm, thereby reducing the overall diameter of the unit to attain the aforesaid purposes.
  • the position of shadow-mask and the fluorescent screen can be determined from the equations (1 and (2) above on the basis of the above arrangement of the electron guns.
  • the width GR of the guard ring can be obtained from GR (d1 d )/2 where d is the lateral or horizontal length of a beam spot and d1 f 01/3. Between d and the lateral length d of the holes in the shadow-mask exists the experimental relationship d 1.15d. Thus, the width of the guard ring perpendicular to the direction of scanning be ignored, so that the size of the holes 8 in the shadow-mask 7 may accordingly be increased to provide an improved beam transmittivity, which may be obtained, from FIG. 2, by:
  • a cathode-ray tube was prepared in the manner shown in FIG. 5 by respectively selecting the distance Lsg between the tip ends of electron guns and a fluorescent screen to 264 mm, the distance L between a deflection plane to the fluorescent screen to 194 mm, the pitch of holes in a shadow-mask with respect to a horizontal direction to 0.60 mm, the distance Sg between the central axis of the electron gun unit and the electrode axes (red and blue) at the tip ends thereof to 5.78 mm, the distance Sgb between the central axis of the electron gun unit and the axis of the electrodes (blue) to 6.79 mm, and the angle 0 of the axis of each of the electron guns (red and green) with respect to the X-axis to 16".
  • the tube of this inveiition displays various improvements.
  • the luminescence of the tube can be greatly improved by 20 to 43 percent as compared with those of the tubes for comparison.
  • the electron guns are arranged in the form of a nonequilateral triangle, in particular, an isosceles triangle, the overall diameter of the electron gun unit can be reduced when compared with that in a known device, whereby the amount of deflection voltage can be decreased.
  • the axis of the electron gun (blue) has been described to be perpendicular to the direction of beam scanning. I-Iowever, similar results will be obtained by arranging said axis in such a position as that of said red or green electron gun in the manner already discussed.
  • a shadow-mask type color cathode ray tube comprising:
  • a multi-color image screen including a plurality of interspersed groups of elemental fluorescent dots including blue;
  • electron gun means including a plurality of electron guns for projecting a corresponding plurality of electron beam components towards said image screen, said electron gun corresponding to the blue fluorescent dots having an outside diameter smaller than those of the other electron guns, and said electron guns being arranged in an isosceles triangle having its apex corresponding to said electron gun for blue; and
  • a shadow-mask having a plurality of substantially rectangular shaped apertures therein, said shadow-mask being disposed between said screen and said electron gun means for selectively directing said electron beam components onto said fluorescent dots;
  • the distance Sx between a position at which each of said beam components is deflected and the axis of the electron gun unit as measured in the direction of scanning, and the distance q between the shadow-mask and the fluorescent surface being defined by where a is the pitch of the beam passing apertures of said shadow-mask in the direction of scanning, L is the distance between the deflection position and the fluorescent surface, Sgx is the distance in the direction of scanning between the tip portion of the electron gun and the axis of the electron gun unit, and Lvg is the distance between the tip end of each electron gunand the fluorescent surface.
  • a shadow-mask type color cathode-ray tube according to claim 1 wherein said fluorescent dots in each group are red,

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  • Electrodes For Cathode-Ray Tubes (AREA)
US10978A 1969-02-17 1970-02-12 Shadow-mask having rectangular apertures Expired - Lifetime US3663854A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP44011084A JPS4826175B1 (de) 1969-02-17 1969-02-17

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US3663854A true US3663854A (en) 1972-05-16

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US10978A Expired - Lifetime US3663854A (en) 1969-02-17 1970-02-12 Shadow-mask having rectangular apertures

Country Status (5)

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US (1) US3663854A (de)
JP (1) JPS4826175B1 (de)
DE (1) DE2007212A1 (de)
FR (1) FR2035551A5 (de)
GB (1) GB1250288A (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777204A (en) * 1972-03-30 1973-12-04 Gte Sylvania Inc Tri-color cathode ray tube employing a shadow mask having elongated apertures
US3828216A (en) * 1970-02-14 1974-08-06 Sony Corp Color display tube with elongated phosphor dots and shadow mask apertures
US3883770A (en) * 1972-01-19 1975-05-13 Hitachi Ltd Colour picture tubes
US3944867A (en) * 1974-03-15 1976-03-16 Zenith Radio Corporation Shadow mask having ribs bounding rectangular apertures
US3949411A (en) * 1973-02-09 1976-04-06 Hitachi, Ltd. Exposure apparatus
DE2611335A1 (de) 1975-03-19 1976-09-23 Rca Corp Kathodenstrahlroehre mit lochmaske und verfahren zum herstellen einer solchen roehre
US4127791A (en) * 1975-12-18 1978-11-28 U.S. Philips Corporation Cathode ray tube shadow mask with slotted apertures
US4186326A (en) * 1973-06-18 1980-01-29 Matsushita Electronics Corporation Shadow mask having vertical pitch about 8/(2n-1) times horizontal pitch
DE2659998C2 (de) * 1975-03-19 1986-12-18 Rca Corp., New York, N.Y. Kathodenstrahlröhre mit gewellter Farbauswahl-Lochmaske
US5378959A (en) * 1992-02-20 1995-01-03 Videocolor, S.P.A. Shadow mask type color picture tube with reduced moire
US5525858A (en) * 1994-01-14 1996-06-11 Videocolor, S.P.A. Color picture tube with reduced primary and secondary moire

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5449676U (de) * 1977-09-14 1979-04-06

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2764628A (en) * 1952-03-19 1956-09-25 Columbia Broadcasting Syst Inc Television
US2850658A (en) * 1956-02-21 1958-09-02 Rca Corp Non-symmetrical cathodes in cathode ray tubes
GB807129A (en) * 1956-01-21 1959-01-07 Philips Electrical Ind Ltd Improvements in or relating to colour-television picture tubes
US2922073A (en) * 1955-03-22 1960-01-19 Kendon Electronics Inc Color reproduction systems of the cathode ray tube type
CH393417A (de) * 1961-03-08 1965-06-15 Philips Nv Kathodenstrahlröhre zum Wiedergeben farbiger Bilder
US3393336A (en) * 1965-05-20 1968-07-16 Cft Comp Fse Television Three gun color tube with central gun of smaller cross-section than lateral guns

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2764628A (en) * 1952-03-19 1956-09-25 Columbia Broadcasting Syst Inc Television
US2922073A (en) * 1955-03-22 1960-01-19 Kendon Electronics Inc Color reproduction systems of the cathode ray tube type
GB807129A (en) * 1956-01-21 1959-01-07 Philips Electrical Ind Ltd Improvements in or relating to colour-television picture tubes
US2850658A (en) * 1956-02-21 1958-09-02 Rca Corp Non-symmetrical cathodes in cathode ray tubes
CH393417A (de) * 1961-03-08 1965-06-15 Philips Nv Kathodenstrahlröhre zum Wiedergeben farbiger Bilder
US3393336A (en) * 1965-05-20 1968-07-16 Cft Comp Fse Television Three gun color tube with central gun of smaller cross-section than lateral guns

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3828216A (en) * 1970-02-14 1974-08-06 Sony Corp Color display tube with elongated phosphor dots and shadow mask apertures
US3883770A (en) * 1972-01-19 1975-05-13 Hitachi Ltd Colour picture tubes
US3777204A (en) * 1972-03-30 1973-12-04 Gte Sylvania Inc Tri-color cathode ray tube employing a shadow mask having elongated apertures
US3949411A (en) * 1973-02-09 1976-04-06 Hitachi, Ltd. Exposure apparatus
US4186326A (en) * 1973-06-18 1980-01-29 Matsushita Electronics Corporation Shadow mask having vertical pitch about 8/(2n-1) times horizontal pitch
US3944867A (en) * 1974-03-15 1976-03-16 Zenith Radio Corporation Shadow mask having ribs bounding rectangular apertures
DE2611335A1 (de) 1975-03-19 1976-09-23 Rca Corp Kathodenstrahlroehre mit lochmaske und verfahren zum herstellen einer solchen roehre
DE2659998C2 (de) * 1975-03-19 1986-12-18 Rca Corp., New York, N.Y. Kathodenstrahlröhre mit gewellter Farbauswahl-Lochmaske
US4127791A (en) * 1975-12-18 1978-11-28 U.S. Philips Corporation Cathode ray tube shadow mask with slotted apertures
US5378959A (en) * 1992-02-20 1995-01-03 Videocolor, S.P.A. Shadow mask type color picture tube with reduced moire
US5525858A (en) * 1994-01-14 1996-06-11 Videocolor, S.P.A. Color picture tube with reduced primary and secondary moire

Also Published As

Publication number Publication date
FR2035551A5 (de) 1970-12-18
GB1250288A (de) 1971-10-20
DE2007212A1 (de) 1970-09-03
JPS4826175B1 (de) 1973-08-07

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