WO1998014978A1 - Dispositif d'affichage presentant un tube cathodique - Google Patents

Dispositif d'affichage presentant un tube cathodique Download PDF

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Publication number
WO1998014978A1
WO1998014978A1 PCT/IB1997/000881 IB9700881W WO9814978A1 WO 1998014978 A1 WO1998014978 A1 WO 1998014978A1 IB 9700881 W IB9700881 W IB 9700881W WO 9814978 A1 WO9814978 A1 WO 9814978A1
Authority
WO
WIPO (PCT)
Prior art keywords
display device
kvolt
cathode ray
ray tube
anode voltage
Prior art date
Application number
PCT/IB1997/000881
Other languages
English (en)
Inventor
Joseph Waltherus Johannes Maria VAN DER HEIJDEN
Original Assignee
Philips Electronics N.V.
Philips Norden Ab
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 Philips Electronics N.V., Philips Norden Ab filed Critical Philips Electronics N.V.
Priority to EP97929449A priority Critical patent/EP0880790A1/fr
Priority to JP10516334A priority patent/JP2000501561A/ja
Priority to KR1019980704145A priority patent/KR19990071861A/ko
Publication of WO1998014978A1 publication Critical patent/WO1998014978A1/fr

Links

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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
    • H01J29/503—Three or more guns, the axes of which lay in a common plane

Definitions

  • Display device having a cathode ray tube
  • the invention relates to a display device having a cathode ray tube comprising an in-line electron gun for generating three m-hne electron beams in a neck of the cathode ray tube, the m-hne electron gun comprising a mam lens pan having three apertures for passing the three electron beams, and a deflection unit, the display device having means to supply an anode voltage to an electrode of the main lens and having a cathodolummescent phosphor screen provided on a viewing panel of the cathode ray tube
  • Display devices of the type mentioned in the first paragraph are used, for instance, in computer monitors and television apparatuses
  • a display device in accordance with the invention is characterized in that, in operation, the anode voltage supplied to the electron gun lies in the range 16-22 kVolt and the product of the square root of the anode voltage (V a 0 ) and the electron beam pitch p in the main lens raised to the 3/2 power (p 3 2 ), i.e. V a 05 .p 3 ' 2 , is greater than 50 kVolt° 5 mm 3/2 .
  • the electron beam pitch is half the distance between the centres of the outer electron beams in the main lens of the gun.
  • Conventional cathode ray tubes have an anode voltage of 25-30 Kvolts.
  • the power consumed by a display device having a cathode ray rube is reduced substantially by reducing the anode voltage.
  • the energy dissipated in the deflection unit and the drive circuit for the deflection unit is roughly proportional to the anode voltage. Reducing the anode voltage reduce the energy consumption of the deflection unit, roughly in accordance with the anode voltage.
  • Image quality is decreases, however, appreciably if the value of V a 0 5 .p 3/2 is smaller than 50 kVolt° 5 mm 3 2 .
  • the influence of magnetic spot displacement due to the earth's magnetic field is roughly inversely proportional to V a 0 5 .p 3 2 and at values below 50 kVolt o 5 mm 3/2 the influence becomes appreciable, leading, in particular, to a reduction of the colour purity.
  • the earth's magnetic field influences the paths of the electron beams such that the beams at least partly impinge on phosphors of the "wrong colour” thereby negatively influencing the colour rendition. This effect results in a loss of colour purity. Reduction of the anode voltage reduces the value for V a 0 5 .p 3 2 and thus colour purity can be negatively influenced. In devices according to the invention this effect is, however, limited.
  • the influence could be reduced by increasing the dimensions of the black matrix. This, however, leads to a reduction of the luminance.
  • the negative effects on colour purity are usually at an acceptable level for values higher than 50 kVolt° 5 mm 3/2 .
  • the value for V a 0 5 .p 3 ' 2 is somewhat larger, i.e. larger than 55 kVolt 0 5 mm 3/2 , because magnetic fields other than the earth's magnetic field may be present in and around the device.
  • the value of V a 0 5 .p 3/2 is less than 80 kVol 3 mm 3/2 .
  • the cathode ray tube is provided with a black-matrix layer between the viewing panel and the phosphor screen, which black matrix has apertures for passing light generated by the phosphor screen, the apertures having a maximum dimension (e.g. width or length) below 125 micrometers in at least one direction.
  • the limitation to the value of V a 0 5 .p 3 2 is of particular importance.
  • the display device has means for applying oscillating currents having a frequency higher than 65 kHz to the deflection unit, the deflection unit having deflection coils comprising solid wires.
  • the deflection unit comprises coils wound from Litz wire.
  • Fig. 1 shows a display device having a cathode ray tube and a deflection unit
  • Fig. 2 shows a detail of the display device of figure 1
  • Fig. 3 is a diagrammatic, partly perspective view of an electron gun 5
  • Fig. 4 graphically shows the V a and p-values for the present invention.
  • Fig. 1 is a partly perspective view of a cathode ray tube 1.
  • Said cathode ray tube 1 comprises an evacuated envelope 3 having a display window (also called viewing panel) 2. and a neck 4.
  • a display window also called viewing panel
  • an electron gun 5 for generating, in this example, three electron beams 6, 7 and 8.
  • a luminescent display screen 9 which, in this example, comprises phosphor elements luminescing in red, green and blue.
  • said electron beams 6, 7 and 8 are deflected across the screen 9 by means of a deflection unit 10, which is located at the junction between the neck and the cone, and pass through the colour selection electrode, in this example the shadow mask 11 which comprises a thin plate having apertures 12.
  • the electron beams 6, 7 and 8 pass through said apertures 12 at a small angle with respect to each other and each electron beam impinges on phosphor elements of only one colour.
  • the screen and the shadow mask are at the same high voltage as the last electrode (anode) of the gun.
  • the electron beams are separated by a distance p, the electron beam pitch.
  • the distance p is the distance between the centres of adjacent electron beams in the main lens.
  • a black matrix is present between the phosphor screen 9 and the display window 3 .
  • a black matrix is a black layer with apertures for passing light emitted by the phosphor screen.
  • the display device comprises means 14 to supply voltages to the electron gun and means 15 to supply deflection currents to the deflection unit 10.
  • Fig. 2 shows is a sectional view of a colour display tube, showing in more detail a shadow mask 11, which is suspended in front of the screen 9.
  • the display window has a raised edge 17 in the corners of which supporting means, for example in the form of pins 18 having a free end portion 19, are provided.
  • the free end portion 19 of the pin 18 partly projects from an aperture in a resilient element 20 of the suspension means.
  • the shadow mask 11 is attached to a frame 24 to increase the sturdiness of the shadow mask.
  • Electron beam 8 passes through apertures 12 in the shadow mask and is incident on a phosphor element of screen 9.
  • the way in which the shadow mask is suspended is not essential and figure 2 merely shows an example.
  • the electron beam 8, upon impinging on the phosphor screen releases part or all of its kinetic energy and excites the phosphor, which emits light through the display window 2.
  • Figure 1 shows also the distance between the electron beams p, also called the electron beam pitch and figure 2 shows the distance q between the shadow mask 11 and the screen 9.
  • Electron gun 5 comprises a common control electrode 321, also referred to as G, electrode, in which three cathodes 322, 323 and 324 are secured.
  • the G, electrode is secured to supports 326 by means of connecting elements 325.
  • Said supports are made of glass. Examples of such supports are the supports which are commonly referred to as "beading rods" .
  • the electron gun 5 further comprises a common plate-shaped electrode 327, also referred to as G 2 electrode, which is secured to the supports by connecting elements 28.
  • the electron gun 3 comprises two supports 326.
  • the electron gun 3 further comprises the common electrodes 329 and 331 which are also secured to supports 326 by means of connecting elements (330 and 332, respectively). Between 329 and 332 the main lens is formed. In operation the anode voltage is supplied to electrode 332. In this example, the supports are secured on feed-through pins 335 by means of brackets 334. The electrical connections between the feed-through pins and the electrodes are not shown. One of the pins 335 is supplied with the anode voltage V a . Lead 336 interconnects this pin and the electrode 332.
  • Table 1 The approximate power consumption of a conventional display device is approximately given in table 1 below
  • the energy for horizontal deflection includes the energy for the generation of voltage in the horizontal deflection circuit and energy dissipated in the horizontal (line) deflection coils
  • the energy for vertical direction includes the energy dissipated in the frame (vertical) deflection coils and in the vertical deflection circuit
  • the total of the horizontal and vertical deflection power is hereinafter also refered to as "deflection power"
  • the screen power includes the product of the anode voltage and the total beam current
  • the power supply includes the power dissipation in the power supply circuitry
  • the category "other ' includes other power dissipating circuits (e g video circuitry)
  • the power consumption can be reduced, for example, by reducing the diameter of the neck of the envelope This allows the deflection unit to be positioned closer to the electron beams, which decreases the volume in which the electron beams are deflected, which should lead to a reduction of the energy necessary for deflecting the electron beams
  • the inventor has found, however, that such reduction is at least partly counteracted by an increase in ohmic losses in the deflection unit Comparing several designs a 30% reduction in the neck dimensions was found to lead an approximately 12% reduction in the power needed for deflecting the electron beams A 20% reduction was found to lead to a reduction of approximately 5 %
  • the distance q between the mask and the phosphor screen is inversely proportional to the electron beam pitch p according to the formula:
  • L is the gun to screen distance.
  • acute is the horizontal screen pitch (the distance between neighbouring phosphor areas of the same colour in the horizontal direction) and p is the electron beam pitch, i.e. the distance between the centres of neighbouring electron beams in the main lens.
  • the electron beams are influenced by magnetic fields such as the earth's magnetic field
  • the displacements of the electron beams due to this influence are proportional to q 1 and q : , on average to q 3 ' 2 .
  • the spot displacements are inversely proportional to the square root of the anode voltage
  • this parameter is limited to values higher than 50 kVolt o 5 mm 3 2 .
  • a black matrix having apertures below 125 micrometers, is present between the phosphor screen 9 and the viewing panel 2, it is important to limit the spot displacement
  • a spot displacement due to the earth's magnetic field is of the order of 10-15 micrometer
  • Reducing the parameter V a 0 5 p 3/2 increases the magnetic spot displacements
  • an increase of 5 micrometer in displacements will require a decrease of the apertures in the black matrix by 5 micrometer
  • the diameter of the aperture is then 120 micrometer
  • the luminance will be reduced by 9%, or alternatively the colour purity will be reduced
  • the luminance can be increased by increasing the beam current, this w ⁇ .11 however increase the required
  • V a ° 5 p 3/2 has the advantage that the electron beam spot performance in itself is improved or at least can be held at an acceptable level
  • Main lenses in an in-line electron gun show appreciable spherical aberrations To reduce these aberrations only the middle part of the lens is used
  • a reduction of the electron beam pitch p causes the distance between the apertures for passing the electron beams to be reduced
  • the diameter of the lenses formed in the mam lens is reduced, increasing the spherical aberrations
  • dynamic voltages could be applied to the electron gun (so-called DAF- solutions)
  • the dynamic signals needed for such a gun require additional power and the circuitry needed is expensive
  • V a ranges preferably between 18 and 21 kVolts
  • anode voltages lower than 18 kVolt the strength of the main lens is relatively small
  • An m-hne electron gun has a pre- focusmg lens in front of the mam lens As the strength of the main lens is reduced, the distance between the main lens and the pre-focusmg lens should be increased This leads to an increase of the overall dimension of the cathode ray tube
  • Figure 4 graphically shows the relation between the anode voltage V a m kVolt on the horizontal axis, the electron beam pitch p in mm on the vertical axis and the value for V a 0 5 p 3/2 (curved lines) At the left-hand side are, next to the figure indicated the values for V a 0 5 .p 3 2 .
  • the range of claim 1 is dotted, the range of claim 2 is indicated by a greater density of dots.
  • the present invention provides a display device having a cathode ray tube with an in-line electron gun with a main lens wherein the anode voltage is between 16 and 22 kVolt and the parameter V a 0 5 .p 3/2 is greater than 50 kVolt°' 5 mm 3 2 .
  • a reduction of the total power can be acheived without sacrificing colour purity.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)

Abstract

Dispositif d'affichage présentant une canon à électrons en ligne avec une lentille principale, dans lequel la tension anodique est comprise entre 16 et 22 kVolt et le paramètre Va?0,5.p3/2¿ est supérieur à 50 kVolt?0,5mm3/2¿. Une réduction de la puissance totale peut être obtenue sans pour autant sacrifier les performances d'entrée.
PCT/IB1997/000881 1996-09-30 1997-07-16 Dispositif d'affichage presentant un tube cathodique WO1998014978A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP97929449A EP0880790A1 (fr) 1996-09-30 1997-07-16 Dispositif d'affichage presentant un tube cathodique
JP10516334A JP2000501561A (ja) 1996-09-30 1997-07-16 陰極線管を有する表示装置
KR1019980704145A KR19990071861A (ko) 1996-09-30 1997-07-16 음극선관을구비한디스플레이장치

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP96202729 1996-09-30
EP96202729.8 1996-09-30

Publications (1)

Publication Number Publication Date
WO1998014978A1 true WO1998014978A1 (fr) 1998-04-09

Family

ID=8224450

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB1997/000881 WO1998014978A1 (fr) 1996-09-30 1997-07-16 Dispositif d'affichage presentant un tube cathodique

Country Status (5)

Country Link
EP (1) EP0880790A1 (fr)
JP (1) JP2000501561A (fr)
KR (1) KR19990071861A (fr)
CN (1) CN1131542C (fr)
WO (1) WO1998014978A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2918426A1 (de) * 1979-05-08 1980-11-20 Leybold Heraeus Gmbh & Co Kg Hochspannungsversorgungseinrichtung fuer leistungs-elektronenstrahlkanonen
CN85104126A (zh) * 1985-05-30 1986-11-26 株式会社日立制作所 彩色显像管的一字排列式电子枪
US4737682A (en) * 1987-07-20 1988-04-12 Rca Corporation Color picture tube having an inline electron gun with an einzel lens
US5077498A (en) * 1991-02-11 1991-12-31 Tektronix, Inc. Pinched electron beam cathode-ray tube with high-voltage einzel focus lens

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
NEC RES. & DEVELOP., Vol. 36, No. 1, January 1995, N. AIBARA et al., "36 cm (15 Inch) Power Saving Color Display Tube", pages 179-182. *
PROCEEDINGS OF THE SIXTEENTH INTERNATIONAL DISPLAY RESEARCH CONFERENCE, 1-3 October 1996, J.W.J.M. VAN DER HEIJDEN, PHILIPS COMPONENTS B.V., "A Low Power 15, CMT Design", pages 145-148. *
SID DIGEST, 1996, J. KIMIYA et al., "A 22,5-mm-Neck Color CRT Electron Gun with Simplified Dynamically Activated Quadrupole Lens", pages 795-798. *

Also Published As

Publication number Publication date
KR19990071861A (ko) 1999-09-27
CN1205112A (zh) 1999-01-13
EP0880790A1 (fr) 1998-12-02
JP2000501561A (ja) 2000-02-08
CN1131542C (zh) 2003-12-17

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