EP0637833A1 - Tube à rayons cathodiques en couleurs - Google Patents

Tube à rayons cathodiques en couleurs Download PDF

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Publication number
EP0637833A1
EP0637833A1 EP94202200A EP94202200A EP0637833A1 EP 0637833 A1 EP0637833 A1 EP 0637833A1 EP 94202200 A EP94202200 A EP 94202200A EP 94202200 A EP94202200 A EP 94202200A EP 0637833 A1 EP0637833 A1 EP 0637833A1
Authority
EP
European Patent Office
Prior art keywords
apertures
colour
rows
selection electrode
electron beam
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.)
Granted
Application number
EP94202200A
Other languages
German (de)
English (en)
Other versions
EP0637833B1 (fr
Inventor
Albertus Aemilius Seyno Sluyterman
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.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
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 Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0637833A1 publication Critical patent/EP0637833A1/fr
Application granted granted Critical
Publication of EP0637833B1 publication Critical patent/EP0637833B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream
    • H01J29/07—Shadow masks for colour television tubes
    • H01J29/076—Shadow masks for colour television tubes characterised by the shape or distribution of beam-passing apertures
    • 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
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream
    • H01J29/07—Shadow masks for colour television tubes

Definitions

  • the invention relates to a colour cathode ray tube comprising an electron gun for generating at least one electron beam, a colour selection electrode having rows of apertures, a display screen and means for deflecting the electron beam across the colour selection electrode in a line deflection direction transverse to the row of apertures.
  • Such display devices are known. They are used, inter alia , in television receivers.
  • Moiré effect causes light and dark lines or lines of a deviating colour in the image.
  • lines are written on the display screen in the line deflection direction by the electron beam(s).
  • the number of lines written on the display screen (the so-called number of active lines) is system-dependent.
  • the NTSC system approximately 450 active lines are written (the NTSC signal comprises 525 lines).
  • a colour cathode ray tube preferably does not exhibit disturbing Moiré effects for "normal" display or HDTV-display, irrespective of whether such a tube is used in a PAL, SECAM or NTSC system.
  • the colour cathode ray tube in accordance with the invention is characterized in that the number of apertures per row ranges between 690 and 780.
  • a first preferred range is defined in that the number of apertures ranges between 705 and 750, more particularly between 705 and 730. This range is very suitable for PAL (or SECAM) systems both for normal and HDTV display.
  • a second preferred range is defined in that the number of apertures ranges between 730 and 750. This range is very suitable for dual PAL-NTSC HDTV applications.
  • a third preferred range is defined in that the number of apertures ranges between 730 and 780, more particularly between 750 and 780. This range is very suitable for NTSC applications both for normal and HDTV display.
  • the invention also relates to a display device comprising such a colour cathode ray tube.
  • the invention further aims at providing a display device comprising a colour cathode ray tube having an electron gun for generating at least one electron beam, a colour selection electrode having rows of apertures, a display screen and means for deflecting the electron beam across the colour selection electrode in a line deflection direction transverse to the rows of apertures, so that no disturbing Moiré effects occur.
  • the display device in accordance with the invention is characterized in that, in operation, the lines are subjected to interlaced scanning and the ratio between the number of apertures and the number of lines scanned across the apertures is approximately 4/6 or 5/6.
  • the above-mentioned ratio is equal, within a 0.1% margin, to the so-called s/a v ratio, where s is the scan pitch for the entire frame and a v is the mask pitch.
  • s is the scan pitch for the entire frame
  • a v is the mask pitch.
  • a ratio of approximately 4/6 is used and for an NTSC display device a ratio of approximately 5/6 is used.
  • a PAL (SECAM), NTSC display device is to be understood to mean within the scope of the invention a display device which is suitable for receiving, respectively, a PAL (SECAM) and an NTSC signal.
  • Fig. 1 is a partly perspective view of a cathode ray tube 1.
  • Said cathode ray tube 1 comprises an evacuated envelope 2 having a display window 3, a cone 4 and a neck 5.
  • an electron gun 6 for generating, in this example, three electron beams 7, 8 and 9.
  • a luminescent display screen 10 which, in this example, comprises phosphor elements luminescing in red, green and blue.
  • said electron beams 7, 8 and 9 are deflected across the screen 10 by means of a deflection unit 11, 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 12 which comprises a thin plate having apertures 13.
  • the electron beams 7, 8 and 9 pass through said apertures 13 at a small angle with respect to each other and each electron beam impinges on phosphor elements of only one colour.
  • Said Figure also diagrammatically shows the drive mechanism 14 of the electron gun and the deflection unit as well as the receiving means 15 for receiving a signal 16.
  • Fig. 2 is a top view of a detail of a colour selection electrode.
  • Said colour selection electrode 20 comprises a number of rows of apertures 21. Said rows extend transversely to the line deflection direction x. In successive rows the apertures are offset relative to each other in a direction transverse to the line deflection direction. Scanning lines 22 are also shown. Said lines diagrammatically show where the electron beam(s) is (are) incident on the shadow mask.
  • the number of lines which are incident on the shadow mask and which impinges on the display screen after passing through the apertures of the shadow mask is approximately 540 for a "standard” display and twice as many for a HDTV display.
  • the number of active lines of the NTSC system is approximately 450 for "standard” display and 900 for HDTV display.
  • the scanning-line pitch s is shown. This is the distance between the scanning lines.
  • the distance between the apertures (mask pitch) a v is also shown.
  • Table 1 shows that if N ranges between approximately 690 and 780 a fairly good display is obtained for each of the systems and display variants.
  • a colour cathode ray tube comprising a colour selection electrode having such a number of apertures can be used in each system.
  • the range between 705 and 750, more particularly 705-730 is very suitable.
  • the range between 730 and 750 is very suitable and for NTSC applications the range between 730 and 780, in particular 750-780, is suitable.
  • the invention makes it possible to provide a colour cathode ray tube which can be used in the various existing systems and applications without the occurrence of disturbing Moiré effects. By virtue thereof, a substantial saving in costs can be achieved; in various types of display devices the same colour-cathode ray tube can be used. It is also possible to use the same colour selection electrode for different types of colour cathode ray tubes.
  • the invention also provides a cathode ray tube which does not exhibit disturbing Moiré patterns when it is used for HDTV applications (double line frequencies).
  • Table 1 above represents one aspect of the invention, which aspect relates to the number of apertures in one row.
  • Table 2 lists the ratios between the number of scanning lines and the number of apertures per row for the different ranges, the number of apertures per row and the different systems. This ratio is equal, within a 0.1% margin, to the ratio between the distance between the scanning lines (also referred to as scan pitch s) and the distance between the apertures in a row (also referred to as mask pitch a v ).
  • the ratio s/a v can be calculated from the number of apertures per row and the number of scanning lines. If N0 is the number of apertures and N s is the number of effective scanning lines, then s/a v is defined by (N0 - 1)/(N s - 1) .
  • s/a v is substantially equal to N0/N s .
  • a few embodiments exhibiting exceptionally few Moiré effects are given in bold print.
  • the s/a v ratio is an important parameter for the occurrence of Moiré effects.
  • Table 2 Number of apertures per row PAL SECAM PAL-HDTV SECAM-HDTV NTSC NTSC-HDTV 690-770 1,285-1,434 0,643-0,717 1,524-1,708 0,762-0,854 705-730 1,313-1,359 0,657-0,68 1,557-1,612 0,779-0,806 730-750 1,359-1,397 0,68-0,699 1,612-1,657 0,806-0,829 750-780 1,397-1,434 0,699-0,717 1,657-1,708 0,829-0,854
  • An embodiment of the invention in accordance with the second aspect of the invention is characterized in that in interlaced systems the ratio s/a v (which corresponds to the number of apertures divided by the number of lines in one field) is approximately 4/6 or 5/6.
  • the ratio s/a v (which corresponds to the number of apertures divided by the number of lines in one field) is approximately 4/6 or 5/6.
  • two fields are scanned, a first field having half the overall number of lines and the distance between successive lines being twice the scan pitch, followed by a second field, also having half the overall number of lines and the distance between two successive lines also being twice the scan pitch, with the lines of the second field extending between the lines of the first field. It has been found, both theoretically and in practice, that in such systems the Moiré effect is substantially reduced and is minimal for the indicated value.
  • the ratio is preferably approximately 4/6 and in the NTSC system the ratio is approximately 5/6 (see Table 2, third column, third row (PAL-SECAM-HDTV) and Table 2, fifth column, fifth row (NTSC-HDTV)). In the above Table these ranges are given in bold print (for a 7% overscan). "Approximately” is to be understood to mean in this connection that the difference between the s/a v ratio and the ideal ratio is less than approximately 2% of said ideal ratio (4/6 or 5/6).
  • a frame can also be scanned by means of the so-called progressive scanning method, i.e. all lines of the complete frame are successively scanned.
  • the ratio s/a v is preferably approximately equal to 4/3 or 5/3.
  • the overall number of lines in each frame is scanned.
  • Table 2 above lists in bold print s/a v ranges for PAL and NTSC systems which do not overlap, i.e. under the given conditions the number of apertures of an "ideal" PAL system do not correspond to the number of apertures of an "ideal" NTSC system.
  • Table 3 below shows that such an overlap is possible.
  • Table 3 the preferred ranges are given in bold print.
  • the difference between Table 2 and Table 3 is that in Table 2 the overscan is 7% for each system, whereas in Table 3 a distinction is made between a PAL (SECAM) system and an NTSC system.
  • SECAM SECAM
  • NTSC NTSC
  • a change in overscan causes a change of the scan pitch s and hence of the ratio s/a v .
  • a 2% (or 6%) overscan of a PAL system in combination with an 8% (or 12%) overscan of an NTSC system causes the "ideal" number of apertures to change from approximately 737 to 751 or 723.
  • the "ideal" number of apertures can be varied slightly further if the difference in overscan is also changed. For example, if a difference in overscan of 5% is used, a combination of 7% (PAL) and 12% (NTSC) can be used. The "ideal" number of apertures then amounts to 717.
  • Table 3 above deals with a third aspect of the invention.
  • This aspect of the invention relates to the ratio s/a v in combination with a manipulation of this ratio which is governed by the incoming signal.
  • An embodiment of the invention in accordance with the third aspect of the invention relates to a display device comprising a colour cathode ray tube having an electron gun for generating at least one electron beam, a colour selection electrode having rows of apertures, a display screen and means for deflecting the electron beam across the colour selection electrode in a line-deflection direction transverse to the rows of apertures, and comprising means for receiving a picture signal and means for controlling the overscan as a function of the incoming signal.
  • the two systems presently in use are PAL and NTSC.
  • the number of apertures per row ranges between 710 and 760. Within this range, it is possible to maximally reduce the Moiré effect for the two systems presently in use.
  • the difference in overscan is 5-7%.
  • the receiving means 15 comprises a means for influencing the overscan as a function of the incoming signal. This results in an adaptation of the scan pitch s and hence the ratio s/a v .
  • the electron gun simultaneously generates three electron beams, each electron beam generating an image in red, green or blue.
  • the electron gun may alternatively generate a single electron beam which sequentially generates the three different colour images.
  • each row has an equal number of apertures. Small variations, within the indicated range, in the number of apertures may however occur, for example to improve the edges of the image displayed.
  • the colour selection electrode may have a small number (fewer than five) of rows having a smaller number of apertures than indicated in the claims.

Landscapes

  • Electrodes For Cathode-Ray Tubes (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Details Of Television Scanning (AREA)
EP94202200A 1993-08-02 1994-07-28 Tube à rayons cathodiques en couleurs Expired - Lifetime EP0637833B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE9300804 1993-08-02
BE9300804A BE1007430A3 (nl) 1993-08-02 1993-08-02 Kleurenkathodestraalbuis en beeldweergeefinrichting.

Publications (2)

Publication Number Publication Date
EP0637833A1 true EP0637833A1 (fr) 1995-02-08
EP0637833B1 EP0637833B1 (fr) 1998-10-07

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94202200A Expired - Lifetime EP0637833B1 (fr) 1993-08-02 1994-07-28 Tube à rayons cathodiques en couleurs

Country Status (6)

Country Link
EP (1) EP0637833B1 (fr)
JP (1) JP3577574B2 (fr)
KR (1) KR100314691B1 (fr)
BE (1) BE1007430A3 (fr)
DE (1) DE69413763T2 (fr)
TW (1) TW273031B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996008030A1 (fr) * 1994-09-07 1996-03-14 Philips Electronics N.V. Tube cathodique couleur et dispositif d'affichage
WO1996011490A1 (fr) * 1994-10-05 1996-04-18 Philips Electronics N.V. Tube a rayons cathodiques couleur et dispositif d'affichage

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7694721B2 (en) 2006-08-31 2010-04-13 Fu Zhun Precision Industry (Shen Zhen) Co., Ltd. Miniature liquid cooling device having an integral pump
US7753662B2 (en) * 2006-09-21 2010-07-13 Fu Zhun Precision Industry (Shen Zhen) Co., Ltd. Miniature liquid cooling device having an integral pump therein

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4326147A (en) * 1975-08-18 1982-04-20 Hitachi, Ltd. Slotted shadow mask having apertures spaced to minimize moire
EP0321202A1 (fr) * 1987-12-17 1989-06-21 Mitsubishi Denki Kabushiki Kaisha Tube à rayons cathodiques du type masques d'ombre

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS581955A (ja) * 1981-06-26 1983-01-07 Toshiba Corp マスク集束型カラ−受像管
NL9000530A (nl) * 1990-03-08 1991-10-01 Philips Nv Schaduwmasker kleurenweergeefbuis.
US5030881A (en) * 1990-07-02 1991-07-09 Rca Licensing Corporation Color picture tube with shadow mask having improved aperture border
JPH04249039A (ja) * 1991-02-01 1992-09-04 Nec Corp カラー受像管

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4326147A (en) * 1975-08-18 1982-04-20 Hitachi, Ltd. Slotted shadow mask having apertures spaced to minimize moire
EP0321202A1 (fr) * 1987-12-17 1989-06-21 Mitsubishi Denki Kabushiki Kaisha Tube à rayons cathodiques du type masques d'ombre

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996008030A1 (fr) * 1994-09-07 1996-03-14 Philips Electronics N.V. Tube cathodique couleur et dispositif d'affichage
WO1996011490A1 (fr) * 1994-10-05 1996-04-18 Philips Electronics N.V. Tube a rayons cathodiques couleur et dispositif d'affichage

Also Published As

Publication number Publication date
DE69413763D1 (de) 1998-11-12
JP3577574B2 (ja) 2004-10-13
BE1007430A3 (nl) 1995-06-13
KR100314691B1 (ko) 2002-03-21
TW273031B (fr) 1996-03-21
JPH0778572A (ja) 1995-03-20
EP0637833B1 (fr) 1998-10-07
KR950006930A (ko) 1995-03-21
DE69413763T2 (de) 1999-05-20

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