EP1557862A1 - Tube à rayons cathodiques comportant un panneau - Google Patents

Tube à rayons cathodiques comportant un panneau Download PDF

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Publication number
EP1557862A1
EP1557862A1 EP04075133A EP04075133A EP1557862A1 EP 1557862 A1 EP1557862 A1 EP 1557862A1 EP 04075133 A EP04075133 A EP 04075133A EP 04075133 A EP04075133 A EP 04075133A EP 1557862 A1 EP1557862 A1 EP 1557862A1
Authority
EP
European Patent Office
Prior art keywords
cathode ray
panel portion
ray tube
glass thickness
curvature
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Withdrawn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
EP04075133A
Other languages
German (de)
English (en)
Inventor
Eric Mark Sloot
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.)
LG Philips Displays Netherlands BV
Original Assignee
LG Philips Displays Netherlands BV
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 LG Philips Displays Netherlands BV filed Critical LG Philips Displays Netherlands BV
Priority to EP04075133A priority Critical patent/EP1557862A1/fr
Publication of EP1557862A1 publication Critical patent/EP1557862A1/fr
Withdrawn legal-status Critical Current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
    • 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 panel portion with a long axis, a short axis and a diagonal, and provided with a skirt, a funnel portion and a neck portion comprising an electron gun for generating one or more electron beam(s), and a deflection system mounted on said funnel portion for generating electromagnetic fields for deflecting said electron beam(s) and a colour selection electrode.
  • the invention also relates to a panel portion for a cathode ray tube.
  • the invention also relates to a display apparatus comprising a CRT.
  • Cathode ray tubes of the type described in the opening paragraph are known.
  • An example is given in US 6,274,977.
  • the colour selection electrode is often also called a shadow mask.
  • the cathode ray tubes have to meet a number of sometimes conflicting conditions. They have to be strong for safety reasons, provide a good image, i.e. provide an image of high quality, be cheap, and have a nearly flat front. Although every one of these conditions is relatively easily obtainable, it is very difficult to provide for a cathode ray tube which meets all or most such requirements simultaneously, i.e. provide a good balance between costs and quality.
  • the cathode ray tube is characterized in that the color selection electrode is made of a material with a high thermal expansion coefficient and in that the panel portion has the following features:
  • the inventor has realized that the indicated ranges of ratios of curvature on the inner side of the panel portion allow in particular the doming behavior to be considerably improved in relation to known devices having a color selection electrode with a high thermal expansion coefficient, thus providing an improvement in image quality, while in relation to devices having a color selection electrode made of a material with a small thermal expansion coefficient, considerable cost savings (approximately 10% of total costs of the CRT) are obtained while yet preserving a high standard in image quality.
  • the cathode ray tube of the invention provides, in relation to prior art devices, a better balance between costs and quality.
  • a material having a large thermal expansion coefficient has a thermal expansion coefficient of larger than 5 10 -6 °C -1 .
  • An example of such a material is Akoca steel having athermal expansion coefficient of 11.7 10 -6 °C -1
  • an example of a material having a low thermal expansion coefficient is Invar with a thermal expansion coefficient of approximately 1.2 10 -6 °C -1 .
  • the aspect ratio of the cathode ray tube is 3:4
  • FIG.1 A cathode ray tube and a picture display device according to a preferred embodiment of the invention is shown in FIG.1.
  • cathode ray tube 1 which includes a panel portion, sometimes also called a display window 2, a funnel portion 3, and a neck portion 4 (or neck as it is called hereinbelow).
  • a means 5 for generating electron beam(s) in this example three in-line electron beams 6, the in-line plane being parallel to the long axis of the display screen, such means are herewithin in short described by the word "electron gun”.
  • a means for generating an electron beam is usually an in-line electron gun.
  • Such designs are standard designs.
  • the inner surface of the panel portion 2 comprises a large number of phosphor elements which form a display screen 8.
  • the middle one of the electron beams 6 substantially coincides with the tube axis 7.
  • the direction of the tube axis is hereinbelow denoted by the z-direction.
  • the direction along the long axis of the display screen is denoted by the x-direction, the direction along the short axis of the display screen by the y-direction.
  • the line scanning direction i.e. the direction in which scanning with the highest frequency takes place is usually parallel to the long axis (the x-direction) of the display screen.
  • the electron beams 6 are deflected by means of a deflection system 9 covering a part of the funnel portion 3. It is in particular this part 3a of the outer contour that the invention relates to.
  • Said deflection system 9 comprises a line deflection subsystem 12 and a frame deflection subsystem 13, in order to create a two-dimensional picture on the display screen 8.
  • the deflection system 9 is made up of sets of coils, one set for the line deflection subsystem 12 and another set for the frame deflection subsystem 13.
  • the figure shows an in-line CRT, having a shadow mask 14. The electron beams pass apertures in the shadow mask 14 before they hit the screen 8.
  • the figure also indicates the x-direction, i.e. the direction along the long axis of the display screen and the z-direction.
  • the z-coordinate of the deflection plane is usually (and hereinbelow) taken to be zero, with positive values of z being closer to the display screen.
  • the panel portion (8) has an elongated shape with two perpendicular axes of symmetry : a long axis whose length, measured from screen end to screen end, is L scr and a short axis whose length is S scr . Often the short axis is the vertical axis, the long axis is the horizontal axis.
  • the panel portion comprises an upstanding wall 21 and a front part 22.
  • Figure 2 also shows the maximum deflection angle ⁇ as being the angle between the tube axis (7) and the deflected electron beam (10) when the electron beam is deflected so as to hit a point on the display screen which is the furthest away from the intersection between the tube axis (7) and the display screen.
  • a scr is usually 3/4 or 9/16.
  • the aspect ratio is 3 ⁇ 4.
  • the outer side of the panel portion is nearly flat, i.e. it has an outside radius of curvature R of more than 30000 mm (30 m). If there are more than one radii of curvature, for instance vertically and horizontally each of the radii of curvature has a value of more than 30000 mm. Preferably all radii of curvature are larger than 40000 mm. Preferably the outside radius is less than 100000 mm (100 m). For nearly completely flat front surfaces sometimes shows hollow impressions.
  • the thicknesses of the panel portion, except for the centre glass thickness are taken at the end of the screen The following thicknesses are of importance:
  • the invention is based on the following insights:
  • the thickness variations of the panel portion are set between the indicated limits. This strengthens the shadow mask and makes it less susceptible for doming. Use is made of a shadow mask of high thermal expansion coefficient. A considerable reduction in prize, compared to devices using a shadow mask with a small thermal expansion coefficient, while yet preserving high image quality is obtained.
  • the quite considerably thickness variations of the glass which prima facie one could imagine to have a "rounding" effect on the image as perceived by the viewer, do not noticeably negatively influence the overall flatness impression of the image, as long as the curvature on the outside of the front portion is small, i.e. radius R is large. Even larger inner radii of curvature (i.e.
  • the cathode ray tube in accordance with the invention pairs a flat image reproduction, to a cost reduction, while yet preserving image quality, in particular reducing doming errors.
  • Doming constitutes for color selection electrodes made of a material with a high thermal expansion coefficient, and such in contrast to color selection electrodes made of a material with a small thermal expansion (such as Invar), a serious problem with a serious detrimental effect on image quality.
  • Figure 3 illustrates in more detail a panel portion. The thicknesses are taken at the end of the screen area, i.e. where the phosphor layer ends.
  • Figure 4 illustrates in a graphical form the ranges for the ratios. Indicated are the ratios in accordance with the invention, as well as for the ratio T c /T d for preferred embodiments. Indicated in this figure are also, for easy reference, the ratios mentioned in US 6,274,977, by means of the dotted lines. There are clear differences in the ratios, furthermore, US 6,274,977 does not discuss the material for the shadow mask.
  • the invention is particular useful for CRT's in the range between 20" and 27".
  • a cathode ray tube (1) comprises an panel portion (2), a funnel portion (3) and a neck portion (4) with an electron gun (5) and a shadow mask.
  • the shadow mask is made of a material with a high thermal expansion coefficient, and the panel portion has an outside radius of curvature (R) larger than 30000 mm.
  • the thicknesses of the panel portion have the following ratios:

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
EP04075133A 2004-01-20 2004-01-20 Tube à rayons cathodiques comportant un panneau Withdrawn EP1557862A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04075133A EP1557862A1 (fr) 2004-01-20 2004-01-20 Tube à rayons cathodiques comportant un panneau

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04075133A EP1557862A1 (fr) 2004-01-20 2004-01-20 Tube à rayons cathodiques comportant un panneau

Publications (1)

Publication Number Publication Date
EP1557862A1 true EP1557862A1 (fr) 2005-07-27

Family

ID=34626518

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04075133A Withdrawn EP1557862A1 (fr) 2004-01-20 2004-01-20 Tube à rayons cathodiques comportant un panneau

Country Status (1)

Country Link
EP (1) EP1557862A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825632A1 (fr) * 1996-08-23 1998-02-25 Sony Corporation Enveloppe en verre pour tube image couleur, et ledit tube
EP0923107A1 (fr) * 1997-12-10 1999-06-16 Kabushiki Kaisha Toshiba Tube à rayons cathodiques
JP2002298760A (ja) * 2001-01-25 2002-10-11 Nippon Electric Glass Co Ltd 陰極線管用ガラスパネル
US6566802B1 (en) * 1999-11-06 2003-05-20 Lg Electronics Inc. Structure of panel for flat type cathode ray tube
EP1376645A2 (fr) * 2002-06-26 2004-01-02 LG. Philips Displays Korea Co., Ltd. Tube à rayons cathodiques
WO2004038755A1 (fr) * 2002-10-28 2004-05-06 Koninklijke Philips Electronics N.V. Dispositif d'affichage presentant un ecran d'affichage plat

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825632A1 (fr) * 1996-08-23 1998-02-25 Sony Corporation Enveloppe en verre pour tube image couleur, et ledit tube
EP0923107A1 (fr) * 1997-12-10 1999-06-16 Kabushiki Kaisha Toshiba Tube à rayons cathodiques
US6566802B1 (en) * 1999-11-06 2003-05-20 Lg Electronics Inc. Structure of panel for flat type cathode ray tube
JP2002298760A (ja) * 2001-01-25 2002-10-11 Nippon Electric Glass Co Ltd 陰極線管用ガラスパネル
EP1383156A1 (fr) * 2001-01-25 2004-01-21 Nippon Electric Glass Company., Ltd. Panneau de verre pour tube à rayons cathodique
EP1376645A2 (fr) * 2002-06-26 2004-01-02 LG. Philips Displays Korea Co., Ltd. Tube à rayons cathodiques
WO2004038755A1 (fr) * 2002-10-28 2004-05-06 Koninklijke Philips Electronics N.V. Dispositif d'affichage presentant un ecran d'affichage plat

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 2003, no. 02 5 February 2003 (2003-02-05) *

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