EP0516218B1 - Tube à rayons cathodiques avec fenêtre d'image - Google Patents

Tube à rayons cathodiques avec fenêtre d'image Download PDF

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Publication number
EP0516218B1
EP0516218B1 EP92201429A EP92201429A EP0516218B1 EP 0516218 B1 EP0516218 B1 EP 0516218B1 EP 92201429 A EP92201429 A EP 92201429A EP 92201429 A EP92201429 A EP 92201429A EP 0516218 B1 EP0516218 B1 EP 0516218B1
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EP
European Patent Office
Prior art keywords
cathode ray
ray tube
display window
axis
value
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
EP92201429A
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German (de)
English (en)
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EP0516218A1 (fr
Inventor
Gijsbertus Bakker
Paul Daamen
Frank Gersmann
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Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
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Priority to EP92201429A priority Critical patent/EP0516218B1/fr
Publication of EP0516218A1 publication Critical patent/EP0516218A1/fr
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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
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/861—Vessels or containers characterised by the form or the structure thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/86—Vessels and containers
    • H01J2229/8613—Faceplates
    • H01J2229/8616—Faceplates characterised by shape
    • H01J2229/862—Parameterised shape, e.g. expression, relationship or equation

Definitions

  • the invention relates to a cathode ray tube comprising a display window having a curved substantially rectangular outside surface with a long axis and a short axis.
  • Cathode ray tubes are used in, inter alia , television receivers, computer monitors and DGD (Data Graphics Display) devices.
  • cathode ray tubes having substantially flat display windows i.e. having display windows with a relatively small average curvature
  • conventional cathode ray tubes exhibit a disturbing distortion of reflections of light sources.
  • Devices in which cathode ray tubes are used are often arranged in rooms which are artificially lit by elongated horizontally arranged light sources which extend parallel to the display window. Examples of such light sources are fluorescent lamps. The most important source of disturbing reflections in such rooms are said elongated light sources.
  • the disturbing effect which reflections of such light sources have on conventional display windows is somewhat comparable to a distorting-mirror effect, and it gives the impression that the display window is very convex even if the average curvature of the display window is very small.
  • a further effect which may occur in the image displayed is that as a result of said reflections a straight line situated right next to a curved reflection image appears to be curved. A viewer perceives this effect as a decrease in picture quality.
  • the invention provides a cathode ray tube in which said adverse effects are reduced.
  • the reflection image of an elongated horizontal light source has a maximum for the y-value on the short axis
  • the reflection image of a vertical elongated light source has a minimum for the x-value on the long axis.
  • a "distorting-mirror" effect does not occur. Two reflection images of one point of a light source are never formed on the display window. By virtue thereof, the display window is perceived as being flat and reflections of the light sources are disturbing to a minor degree only.
  • the conditions stated in the formula above will hereinafter also be referred to as "formula 1".
  • the Y-coordinate is a constant.
  • B1, B2 and B3 are shortened forms of ( ⁇ z/ ⁇ X) y etc. If this condition regarding ⁇ z/ ⁇ x is satisfied, relatively little distortion takes place in the reflection of a vertically arranged linear light source. Said conditions will hereinafter also be referred to as "formula 3".
  • a cathode ray tube in this example colour display tube 1, comprises an evacuated envelope 2 which consists of a display window 3, a cone portion 4 and a neck 5.
  • an electron gun 6 for generating three electron beams 7, 8 and 9 which extend in one plane, the in-line plane, which in this case is the plane of the drawing.
  • a display screen 10 is situated on the inside of the display window.
  • the display screen 10 comprises a large number of phosphor elements luminescing in red, green and blue.
  • the electron beams 7, 8 and 9 are deflected across the display screen 9 by means of deflection unit 11 and pass through a colour selection electrode 12 which is arranged in front of the display window 3 and which comprises a thin plate having apertures 13.
  • the colour selection electrode is suspended in the display window by means of suspension means 14.
  • the three electron beams 7, 8 and 9 pass through the apertures 13 of the colour selection electrode at a small angle with each other and, hence, each electron beam impinges on phosphor elements of only one colour.
  • Fig. 2 is a partly perspective elevational view of a display window.
  • z is termed the sagittal height.
  • the z-axis extends perpendicularly to the tangent plane to the centre of the outside surface of the display window and is indicated in the Figure.
  • the short axis is indicated as the y-axis, the long axis is indicated as the x-axis. Said axes extend perpendicularly to each other and to the z-axis.
  • the outside surface is constructed such that it is mirror symmetrical relative to the short and the long axes.
  • the centre of the outside surface coincides with the point of intersection of the long and the short axes.
  • the x-coordinate of a point can be found by projecting said point perpendicularly onto the x-axis.
  • the x-coordinate is equal to the distance along the x-axis between the centre of the outside surface and the point of projection on the x-axis.
  • the sign is positive on one side of the short axis and negative on the other side.
  • the y-coordinate of a point can be found by projecting said point perpendicularly onto the y-axis.
  • the y-coordinate is equal to the distance along the y-axis between the centre of the outside surface and the point of projection on the y-axis.
  • the sign is positive on one side of the long axis and negative on the other side.
  • the X-value of a point is equal to the x-coordinate divided by half the length of the long axis, so that the x-value for the edge of the outside surface at the end of the long axis is 1, and -1 at the opposite end of the long axis.
  • the Y-value of a point is equal to the y-coordinate divided by half the length of the short axis, so that the Y-value for the edge of the outside surface at the end of the short axis is 1, and -1 at the opposite end of the short axis.
  • Figs. 3a up to and including 3d show front views of a few reflection images on the outside surface of the display window.
  • Said points correspond to a point at an edge of the outside surface at the end of the long axis (point 32) and to a point at the end of the short axis, respectively.
  • Said points correspond to the edges of the display screen, i.e. if lines are drawn from said points in the z-direction, said lines intersect the edges of the display screen.
  • the outside surface is characterized in that it conforms to the characterizing part of claim 1.
  • Fig. 3a shows a reflection image 31 of an elongated light source which is arranged parallel to the x-axis, for z xy /signXY ⁇ 0 for the outside surface (Fig. 3a) and for z xy varying over the outside surface such that also positive values of z xy occur (Fig. 3b).
  • a reflection image as shown in Fig. 3b gives the disturbing impression that the display window is very convex.
  • the reflection image as shown in Fig. 3a does not have this disadvantage.
  • a similar effect occurs with elongated light sources which are arranged parallel to the y-axis.
  • 3c shows a reflection image 31 of an elongated light source which is arranged parallel to the x-axis, for a cathode ray tube the outside surface of which complies with the formula - ⁇ (z xx z yy ) ⁇ z xy /signXY
  • Fig. 3d shows a reflection image 31 for a situation in which there are points 34 which do not comply with the above formula.
  • the radius of curvature of the outside surface at a point is dependent on the direction along which the radius of curvature is taken. For each point a radius of curvature in the x- or in the y-direction can be defined. Likewise the radius of curvature in any direction in between the x- and y-direction can be defined.
  • the curvature of the reflection image 41 is much smaller than the curvature of the reflection image 42.
  • (B1-B3)/(B1-B2) 0.25, so that the condition (B1-B3)/(B1-B2) ⁇ 0.1 ("formula 3") is not satisfied.
  • z A*X2 + B*Y2 + C*X2*Y2 + E(Y2-Y4)*(1-X2) where A > 0, B > 0, C ⁇ 0 and E ⁇ 0, the conditions of "formula 1" are satisfied if: C-E ⁇ 0 and C+E ⁇ 0 (or in other words E/C ⁇ 1) and if it holds that -1/2 ⁇ (A+C)(B+C) ⁇ C+E.
  • the cathode ray tube can be, for example, a monochrome cathode ray tube or a black-white cathode ray tube.
  • the evacuated envelope comprises one neck 5; however, in further examples the cathode ray tube may comprise more than one neck having an electron gun.
  • a number of descriptions of surfaces are given. However, the invention is not limited to said examples nor to the manner in which they are described.
  • the most clearly visible and, hence, most disturbing reflections occur at the outside surface of the display screen. Reflections may also occur at the inside surface of the display window. The disturbing effects of the latter reflections are reduced if the inside surface of the display window complies with the above formulae 1,2 and/or 3, where z, X and Y relate to points on the inside surface. In embodiments, both the inside surface and the outside surface may comply with the formulae.
  • cathode ray tubes comprising a shadow mask
  • said cathode ray tubes comprising a shadow mask are characterized in that the maximum values of (A1 - A3)/(A1 - A2) and/or (B1 - B3)/(B1 - B2) for the inside surface are smaller than 0.20 and greater than 0.1.
  • Doming occurs in cathode ray tubes comprising a shadow mask. Doming is a phenomenon which causes picture quality to be adversely affected as a result of bulging of the shadow mask. It is very difficult to attain an acceptable degree of doming when the maximum values of (A1 - A3)/(A1 - A2) and/or (B1 - B3)/(B1 - B2) are smaller than 0.1.
  • Cathode ray tubes of the invention can have an aspect ratio of 3:4, or smaller than 3:4 e.g. smaller than 3:5, e.g. 9:16.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)

Claims (8)

  1. Tube à rayons cathodiques comprenant une fenêtre d'affichage présentant une surface externe courbe sensiblement rectangulaire avec un axe long et un axe court, caractérisé en ce que la surface externe de la fenêtre d'affichage est donnée par : z = f(X,Y)
    Figure imgb0028
     où X est la coordonnée x divisée par la moitié de la longueur de l'axe long, Y est la coordonnée y divisée par la moitié de la longueur de l'axe court, et chaque point situé en dehors de l'axe long ou de l'axe court répond à la formule : -√ (z xx z yy ) < z xy /signXY < 0
    Figure imgb0029
     où zxx = δ²z/δX², zyy = δ²z/δY² et zxy = δ²z/(δXδY)
    signXY = + 1 pour X > 0, Y > 0 et pour X < 0, Y < 0 et
    signXY = -1 pour X > 0, Y > 0 et pour X < 0, Y > 0.
  2. Tube à rayons cathodiques selon la revendication 1, caractérisé en ce que, pour chaque ligne ayant une valeur Y constante, on peut écrire que :
    δz/δY = A₁, A₂ et A₃, pour X = 0,1 et 0,5, respectivement, où (A₁-A₃)/(A₁-A₂) < 0,1.
  3. Tube à rayons cathodiques selon la revendication 1 ou 2, caractérisé en ce que, pour chaque ligne ayant une valeur X constante, on peut écrire que :
    δz/δX = B₁, B₂ et B₃ pour Y = 0,1 et 0,5, respectivement, où (B₁-B₃)/(B₁-B₂) < 0,1.
  4. Tube à rayons cathodiques comprenant une fenêtre d'affichage présentant une surface externe courbe sensiblement rectangulaire avec un axe long et un axe court, caractérisé en ce que la surface interne de la fenêtre d'affichage est donnée par : z = f(X,Y)
    Figure imgb0030
     où X est la coordonnée x divisée par la moitié de la longueur de l'axe long, Y est la coordonnée y divisée par la moitié de la longueur de l'axe court, et chaque point situé en dehors de l'axe long ou de l'axe court répond à la formule : -√ (z xx z yy ) < z xy /signXY < 0
    Figure imgb0031
     où zxx = δ²z/δX², zyy = δ²z/δY² et zxy = δ²z/(δXδY)
    signXY = + 1 pour X > 0, Y > 0 et pour X < 0, Y < 0 et
    signXY = -1 pour X > 0, Y < 0 et pour X < 0, Y > 0.
  5. Tube à rayons cathodiques selon la revendication 4, caractérisé en ce que, pour chaque ligne ayant une valeur Y constante, on peut écrire que :
    δz/δY = A₁, A₂ et A₃, pour X = 0,1 et 0,5, respectivement, où (A₁-A₃)/(A₁-A₂) < 0,1.
  6. Tube à rayons cathodiques selon la revendication 4 ou 5, caractérisé en ce que, pour chaque ligne ayant une valeur X constante, on peut écrire que :
    δz/δX = B₁, B₂ et B₃ pour Y = 0,1 et 0,5, respectivement, où (B₁-B₃)/(B₁-B₂) < 0,1.
  7. Tube à rayons cathodiques selon la revendication 4, ledit tube à rayons cathodiques comprenant un masque perforé, caractérisé en ce que, pour chaque ligne ayant une valeur Y constante, on peut écrire que :
    δz/δY = A₁, A₂ et A₃ pour X = 0,1 et 0,5, respectivement, où la valeur maximum de (A₁-A₃)/(A₁-A₂) se situe entre 0,1 et 0,2.
  8. Tube à rayons cathodiques selon la revendication 4 ou 7, ledit tube à rayons cathodiques comprenant un masque perforé, caractérisé en ce que, pour chaque ligne ayant une valeur X constante, on peut écrire que :
    δz/δX = B₁, B₂ et B₃ pour Y = 0,1 et 0,5, respectivement, où la valeur maximum de (B₁-B₃)/(B₁-B₂) se situe entre 0,1 et 0,2.
EP92201429A 1991-05-29 1992-05-20 Tube à rayons cathodiques avec fenêtre d'image Expired - Lifetime EP0516218B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP92201429A EP0516218B1 (fr) 1991-05-29 1992-05-20 Tube à rayons cathodiques avec fenêtre d'image

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
EP91201277 1991-05-29
EP91201277 1991-05-29
EP92200351 1992-02-10
EP92200351 1992-02-10
EP92201429A EP0516218B1 (fr) 1991-05-29 1992-05-20 Tube à rayons cathodiques avec fenêtre d'image

Publications (2)

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EP0516218A1 EP0516218A1 (fr) 1992-12-02
EP0516218B1 true EP0516218B1 (fr) 1995-10-25

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Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4570101A (en) * 1983-09-06 1986-02-11 Rca Corporation Cathode-ray tube having a faceplate panel with a smooth aspherical screen surface
JP2609605B2 (ja) * 1987-03-20 1997-05-14 株式会社日立製作所 シヤドウマスク形カラー受像管
FR2634945B1 (fr) * 1988-07-27 1996-04-26 Videocolor Procede de fabrication d'un tube de television en couleurs a haute definition et tube de television trichrome a haute definition
JPH0614454B2 (ja) * 1990-03-22 1994-02-23 松下電子工業株式会社 シャドウマスク型カラー受像管

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