EP0125949B1 - Colour television tube with correction of low amplitude coma faults - Google Patents

Colour television tube with correction of low amplitude coma faults Download PDF

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Publication number
EP0125949B1
EP0125949B1 EP84400706A EP84400706A EP0125949B1 EP 0125949 B1 EP0125949 B1 EP 0125949B1 EP 84400706 A EP84400706 A EP 84400706A EP 84400706 A EP84400706 A EP 84400706A EP 0125949 B1 EP0125949 B1 EP 0125949B1
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EP
European Patent Office
Prior art keywords
coma
correction
horizontal
beams
dimension
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Expired
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EP84400706A
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German (de)
French (fr)
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EP0125949A1 (en
Inventor
Roger Pieri
Jacques Baudry
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Videocolor SA
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Videocolor SA
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Priority to AT84400706T priority Critical patent/ATE28012T1/en
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/701—Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least
    • H01J29/707—Arrangements intimately associated with parts of the gun and co-operating with external magnetic excitation devices
    • 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
    • H01J29/56—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses

Definitions

  • the invention relates to a display tube, in particular a television, in color of the self-converging type with three beams of coplanar electrons.
  • tube here is meant the system constituted by the tube proper, the deflector and the electron beam generators.
  • color images are usually obtained using a screen covered with luminescent substances of three fundamental colors, generally red, green and blue, which are excited by three electron beams, one for each color. These beams converge on the screen and are moved in lines from left to right and from top to bottom.
  • the screen is made up of triads, that is, sets of three dots, luminescent substances of the three colors.
  • the light intensity (luminance) and the color of each point of the image to be reproduced are obtained by the intensity of excitation of each of the elements of the triad.
  • each electron beam reaches only the points of the color to which it is assigned, on the one hand the three beams have different directions and, on the other hand, a shadow mask is placed in front of the screen.
  • the displacement of the beams along lines which is called scanning, is produced by two variable magnetic fields which deflect the beams one in the horizontal direction and the other in the vertical direction. These magnetic fields are generated by electric currents of variable intensity flowing in coils called deflectors.
  • the magnetic field through which these beams pass must have a particular non-uniform configuration in space, which is linked in particular to the rectangular and substantially planar shape of the screen and the coplanar arrangement of the beams.
  • the tube When convergence is obtained exclusively by the configuration of the magnetic field, the tube is said to be self-converging.
  • This autoconvergence is achieved mainly thanks to the shape of the windings of the deflector.
  • the conformation of these windings is generally not sufficient: there are usually convergence faults.
  • One of these is the so-called coma defect which results, in a tube with coplanar beams, by dimensions of the image produced by the central beam (generally green) different from the dimensions of the image produced by the lateral beams (red and blue). This defect is measured by the distance separating two adjacent vertical edges from the green and red-blue images and by the distance separating two adjacent horizontal edges from these images.
  • the invention relates to the case where the coma defect is of small amplitude, that is to say of the order of a millimeter or less, and of different directions in the horizontal (east-west) and vertical (north- south), the image (green) produced by the central beam being for example wider than the image produced by the lateral beams (red-blue) but of lower height than that of this image produced by the lateral beams.
  • the invention results from the observation that the magnetic pieces of coma correction known up to now are not suitable for the correction of this type of defect.
  • the magnetic elements are constituted by magnetic pads applied to the bottom of a cup constituting an electrode for outputting the electron guns, and which therefore has three openings for the passage of bundles, two of these pellets having the form of crowns or washers surrounding the openings provided for the lateral beams, two other pellets being elongated vertical bars placed on either side of the opening for the green central beam.
  • These magnetic elements are suitable for coma defects of large amplitude, 5 mm for example; but for faults of smaller amplitude they confer a correction of too high a value which causes a fault in the opposite direction.
  • coma defect correction elements comprise four plates of rectangular shape and whose plane is perpendicular to the axis of the tube, these plates being arranged above and below each of the lateral beams, with in addition perpendicular plates, with a plane parallel to the axis of the tube on each side of the central beam.
  • Such a configuration also does not make it possible to correct the defect in a coma of low amplitude, of the order of a millimeter or less and of different directions in the horizontal and vertical directions.
  • the tube according to the invention is characterized in that the magnetic coma correction elements, which are also flat patches, with a plane perpendicular to the direction of the beams, consist exclusively of four rectangular patches, preferably all identical, associated with the lateral beams , two of these pellets being below these respective beams and the other two pellets above these same beams, the length and the width of each patch being chosen as a function of the respective values of the coma defects in vertical and horizontal direction to correct.
  • the magnetic coma correction elements which are also flat patches, with a plane perpendicular to the direction of the beams, consist exclusively of four rectangular patches, preferably all identical, associated with the lateral beams , two of these pellets being below these respective beams and the other two pellets above these same beams, the length and the width of each patch being chosen as a function of the respective values of the coma defects in vertical and horizontal direction to correct.
  • the fault correction is carried out in a particularly simple manner. Furthermore, the correction means (or method) is easily adapted. ble from one type of tube to another because the length of each rectangular element is a direct function of the height of the coma defect to be corrected and, similarly, the width of each element is a direct function of the magnitude of the defect of coma in horizontal direction.
  • the sensitivity of the horizontal scanning is increased because, with the magnetic correction elements of the invention, the magnetic field of horizontal deflection is increased in particular for the lateral beams while the correction elements known up to now decrease the sensitivity of the horizontal scanning, that is to say require a higher power supply of the deflectors.
  • the color television tube 10 is of the type with a perforated mask 11 placed inside the tube in front of the screen 12 and with electron guns 13 producing three beams 14, 15 and 16 coplanar.
  • the central beam 14 is, in this example, that which is intended to excite the green phosphorus on the screen while the lateral beams 15 and 16 excite the blue and red phosphors respectively.
  • the displacement of these beams, in order to scan the screen 12, is carried out by supplying coils 17 of horizontal and vertical deflection which produce magnetic fields allowing the displacement of the three beams 14, 15, 16 respectively in horizontal and vertical directions.
  • the barrels 13 are arranged at the rear of the tube in the cylindrical part 18 called the neck.
  • the deflection coils 17 are arranged partly around the neck 18 and partly around the flared section 19 connecting the neck 18 to the slab 20 presenting the screen 12.
  • the deflector 17 is such that it practically ensures self-convergence, that is to say the convergence of the three beams 14, 15, 16 over the entire screen. However, there still remains the coma defect which is reflected on the screen (FIG. 2) by different dimensions of the images produced by the three beams.
  • the green central beam V 14 produces a rectangular image 21 while the blue lateral beams B and red R produce an image 22, also rectangular, narrower and higher than the image 21.
  • the vertical sides of the image 22 are therefore between the vertical sides of image 21, the distance between two adjacent vertical sides of images 21 and 22 being, in the example (tube whose screen diagonal measures 51 cm), of the order of 0 , 3 mm and the horizontal sides of image 21 are between the horizontal sides of image 22, the distance h between two neighboring horizontal sides in the example being of the order of 0.8 mm.
  • the magnetic field at the rear of the deflector 17 is modified, that is to say on the side of the barrels 13.
  • pellets or plates with high magnetic permeability are used which are supported by the last electrode 23 (FIGS. 3 and 4) of the barrels, that is to say the electrode facing the screen 12.
  • This electrode 23 has a cup shape with a cylindrical edge 25 and bottom 24 perpendicular to the axis 26 of the tube. This bottom is pierced with three holes or openings of coplanar axes lying in a plane passing through the horizontal axis of the screen.
  • the central hole 27 is intended to allow the green beam 14 to pass through while the lateral holes 28 and 29 allow the blue 15 and red beams to pass through 16.
  • the magnetic elements are welded to the bottom 24 of the cup 23. They consist of plates made of an iron-nickel alloy.
  • four rectangular plates 30, 31, 32, 33 are provided (made of an "hyster" at 48% nickel) above and below the openings 28 and 29.
  • the rectangular plate 30 is above the opening 28 with its large side 30, horizontal, the middle of this large side 30, being at the right of the axis of the hole 28 intended to allow the excitation beam of the blue phosphors to pass.
  • the perpendicular bisector on the side 30 passes through the center of the hole 28.
  • the plate 31 is below the hole 28, in a position symmetrical with the plate 30 relative to the center of the hole 18.
  • the plate 32 is disposed relative to the hole 29, like the plate 30 relative to the hole 28.
  • the plate 33 is arranged relative to the hole 29 like the plate 31 relative to the hole 28.
  • the axis of the hole 27 is 5.1 mm away from the axis of the hole 28 or 29 and the thickness of the plates is 0.25 mm.
  • the lines 40 of the vertical deflection magnetic field Vx are spaced from one another around the holes 28 and 29.
  • the vertical deflection magnetic field is therefore attenuated for the blue-red image.
  • the lines of vertical deflection field 41 are, around the hole 27, close to one another: the magnetic field of vertical deflection is therefore increased for the beam 14 of excitation of the green. So we get the correction in the chosen direction: increase of the vertical deviation for green and decrease of the vertical deviation for blue and red.
  • FIG. 5 also shows that the field lines 42 of horizontal deflection Hy are brought closer to each other around the holes 28 and 29. These lines of field of horizontal deflection are also brought closer to each other around the hole 27, but in a lesser extent.
  • the horizontal deflection magnetic field is therefore increased for the three excitation beams, but it is more increased for the blue and red phosphors than for the green.
  • the desired result is also obtained, that is to say a relative reduction in the horizontal deviation for green compared to the horizontal deviation for blue and red.
  • the curves 45, 46 and 47 are curves of variation of the horizontal defect d of coma as a function of the dimension A for three dimensions L, of values L o , L 1 and L 2 respectively .
  • Curves 48, 49 and 50 are similar to curves 45, 46 and 47 respectively, but for the defect h of vertical coma.
  • the plates according to the invention make it possible to reduce the power supply energy of the coils of horizontal deflection. In other words, unlike previous embodiments, the correction is not carried out to the detriment of the horizontal scanning sensitivity.
  • the long side of the plates 30 to 33 is horizontal, it should be noted that, as a variant, these long sides may have other directions, that is to say be oblique to the 'horizontal. In addition, these long sides are not necessarily all parallel to each other.
  • the elements 30 to 33 are simple plates without extension along the axis 26.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Color Television Image Signal Generators (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
  • Picture Signal Circuits (AREA)

Abstract

A color tube of the automatic convergence kind comprises three coplanar electron beams, with magnetic coma defect correction elements situated to the rear of the deflector unit. For the case where these defects are of small size, of the order of 1 mm or less in each direction, and of opposite sense in the horizontal and vertical directions, the correcting elements are formed by four plates of rectangular shape and whose plane is perpendicular to the axis of the tube. The plates are situated above and below each of the lateral beams and one dimension of each of the plates affects the amplitude of the correction in one direction, and the other dimension affects the coma correction in the other direction.

Description

L'invention est relative à un tube de visualisation, notamment de télévision, en couleurs du type autoconvergent à trois faisceaux d'électrons coplanaires.The invention relates to a display tube, in particular a television, in color of the self-converging type with three beams of coplanar electrons.

Par «tube» on entend ici le système constitué par le tube proprement dit, le déviateur et les générateurs de faisceaux d'électrons.By “tube” here is meant the system constituted by the tube proper, the deflector and the electron beam generators.

On sait qu'en télévision ou, de façon plus générale, en visualisation, les images en couleurs sont habituellement obtenues à l'aide d'un écran re- couvert de substances luminescentes de trois couleurs fondamentales, généralement le rouge, le vert et le bleu, qui sont excitées par trois faisceaux d'électrons, un pour chaque couleur. Ces faisceaux convergent sur l'écran et sont déplacés selon des lignes de gauche à droite et de haut en bas.We know that in television or, more generally, in visualization, color images are usually obtained using a screen covered with luminescent substances of three fundamental colors, generally red, green and blue, which are excited by three electron beams, one for each color. These beams converge on the screen and are moved in lines from left to right and from top to bottom.

L'écran est formé de triades, c'est-à-dire d'ensembles de trois points, de substances luminescentes des trois couleurs. L'intensité lumineuse (luminance) et la couleur de chaque point de l'image à reproduire sont obtenues par l'intensité d'excitation de chacun des éléments de la triade.The screen is made up of triads, that is, sets of three dots, luminescent substances of the three colors. The light intensity (luminance) and the color of each point of the image to be reproduced are obtained by the intensity of excitation of each of the elements of the triad.

Pour que chaque faisceau d'électrons n'atteigne que les points de la couleur à laquelle il est affecté, d'une part les trois faisceaux ont des directions différentes et, d'autre part, un masque perforé est disposé devant l'écran.So that each electron beam reaches only the points of the color to which it is assigned, on the one hand the three beams have different directions and, on the other hand, a shadow mask is placed in front of the screen.

Le déplacement des faisceaux selon des lignes, qui est appelé balayage, est produit par deux champs magnétiques variables qui dévient les faisceaux l'un en direction horizontale et l'autre en direction verticale. Ces champs magnétiques sont engendrés par des courants électriques d'intensité variable circulant dans des bobines appelées déviateurs.The displacement of the beams along lines, which is called scanning, is produced by two variable magnetic fields which deflect the beams one in the horizontal direction and the other in the vertical direction. These magnetic fields are generated by electric currents of variable intensity flowing in coils called deflectors.

Pour que les trois faisceaux convergent en tous les points de l'écran il faut que le champ magnétique traversé par ces faisceaux ait, dans l'espace, une configuration particulière, non uniforme, qui est liée notamment à la forme rectangulaire et sensiblement plane de l'écran et à la disposition coplanaire des faisceaux.In order for the three beams to converge at all points on the screen, the magnetic field through which these beams pass must have a particular non-uniform configuration in space, which is linked in particular to the rectangular and substantially planar shape of the screen and the coplanar arrangement of the beams.

Lorsque la convergence est obtenue exclusivement par la configuration du champ magnétique le tube est dit autoconvergent.When convergence is obtained exclusively by the configuration of the magnetic field, the tube is said to be self-converging.

Cette autoconvergence est réalisée principalement grâce à la forme des bobinages du déviateur. Mais la conformation de ces bobinages n'est en général pas suffisante: il subsiste habituellement des défauts de convergence. L'un de ceux-ci est le défaut dit de coma qui se traduit, dans un tube à faisceaux coplanaires, par des dimensions de l'image produite par le faisceau central (en général le vert) différentes des dimensions de l'image produite par les faisceaux latéraux (rouge et bleu). Ce défaut se mesure par la distance séparant deux bords verticaux adjacents des images verte, et rouge-bleu et par la distance séparant deux bords horizontaux adjacents de ces images.This autoconvergence is achieved mainly thanks to the shape of the windings of the deflector. However, the conformation of these windings is generally not sufficient: there are usually convergence faults. One of these is the so-called coma defect which results, in a tube with coplanar beams, by dimensions of the image produced by the central beam (generally green) different from the dimensions of the image produced by the lateral beams (red and blue). This defect is measured by the distance separating two adjacent vertical edges from the green and red-blue images and by the distance separating two adjacent horizontal edges from these images.

Pour corriger le défaut de coma il est connu, par exemple par le brevet français 2 425 146, de prévoir à l'arrière du déviateur, c'est-à-dire du côté des canons à électrons, des éléments à forte perméabilité magnétique de dispositions et configurations telles que le champ magnétique produit par le déviateur est modifié dans une mesure suffisante pour effectuer la correction.To correct the coma defect, it is known, for example from French patent 2,425,146, to provide at the rear of the deflector, that is to say on the side of the electron guns, elements with high magnetic permeability. arrangements and configurations such that the magnetic field produced by the deflector is modified to an extent sufficient to effect the correction.

L'invention vise le cas où le défaut de coma est de faible amplitude, c'est-à-dire de l'ordre du millimètre ou moins, et de sens différents dans les directions horizontale (est-ouest) et verticale (nord-sud), l'image (verte) produite par le faisceau central étant par exemple plus large que l'image produite par les faisceaux latéraux (rouge-bleu) mais de plus faible hauteur que celle de cette image produite par les faisceaux latéraux.The invention relates to the case where the coma defect is of small amplitude, that is to say of the order of a millimeter or less, and of different directions in the horizontal (east-west) and vertical (north- south), the image (green) produced by the central beam being for example wider than the image produced by the lateral beams (red-blue) but of lower height than that of this image produced by the lateral beams.

L'invention résulte de la constatation que les pièces magnétiques de correction de coma connues jusqu'à présent ne sont pas adaptées à la correction de ce type de défaut.The invention results from the observation that the magnetic pieces of coma correction known up to now are not suitable for the correction of this type of defect.

En particulier dans le brevet français 2 425 146 mentionné ci-dessus, les éléments magnétiques sont constitués par des pastilles magnétiques appliquées au fond d'une coupelle constituant une électrode de sortie des canons à électrons, et qui présente donc trois ouvertures pour le passage des faisceaux, deux de ces pastilles ayant la forme de couronnes ou rondelles entourant les ouvertures prévues pour les faisceaux latéraux deux autres pastilles étant des barres verticales allongées disposées de part et d'autre de l'ouverture pour le faisceau central vert. Ces éléments magnétiques conviennent pour des défauts de coma de grande amplitude, 5 mm par exemple; mais pour des défauts de plus faible amplitude ils confèrent une correction de trop forte valeur qui entraine un défaut en sens contraire.In particular in French patent 2,425,146 mentioned above, the magnetic elements are constituted by magnetic pads applied to the bottom of a cup constituting an electrode for outputting the electron guns, and which therefore has three openings for the passage of bundles, two of these pellets having the form of crowns or washers surrounding the openings provided for the lateral beams, two other pellets being elongated vertical bars placed on either side of the opening for the green central beam. These magnetic elements are suitable for coma defects of large amplitude, 5 mm for example; but for faults of smaller amplitude they confer a correction of too high a value which causes a fault in the opposite direction.

Par ailleurs dans le brevet US 4 142 131 est décrit un tube de télévision en couleurs dans lequel les éléments de correction de défauts de coma comprennent quatre plaquettes de forme rectangulaire et dont le plan est perpendiculaire à l'axe du tube, ces plaquettes étant disposées au-dessus et au-dessous de chacun des faisceaux latéraux, avec en plus des plaquettes perpendiculaires, de plan parallèle à l'axe du tube de chaque côté du faisceau central. Une telle configuration ne permet pas non plus de corriger le défaut de coma de faible amplitude, de l'ordre du millimètre ou moins et de sens différents dans les directions horizontale et verticale.Furthermore, in US Pat. No. 4,142,131, a color television tube is described in which the coma defect correction elements comprise four plates of rectangular shape and whose plane is perpendicular to the axis of the tube, these plates being arranged above and below each of the lateral beams, with in addition perpendicular plates, with a plane parallel to the axis of the tube on each side of the central beam. Such a configuration also does not make it possible to correct the defect in a coma of low amplitude, of the order of a millimeter or less and of different directions in the horizontal and vertical directions.

Le tube selon l'invention est caractérisé en ce que les éléments magnétiques de correction de coma, qui sont également des pastilles plates, de plan perpendiculaire à la direction des faisceaux sont constitués exclusivement par quatre pastilles rectangulaires de préférence toutes identiques, associées aux faisceaux latéraux, deux de ces pastilles étant au-dessous de ces faisceaux respectifs et les deux autres pastilles au-dessus de ces mêmes faisceaux, la longueur et la largeur de chaque pastille étant choisies en fonction des valeurs respectives des défauts de coma en direction verticale et horizontale à corriger.The tube according to the invention is characterized in that the magnetic coma correction elements, which are also flat patches, with a plane perpendicular to the direction of the beams, consist exclusively of four rectangular patches, preferably all identical, associated with the lateral beams , two of these pellets being below these respective beams and the other two pellets above these same beams, the length and the width of each patch being chosen as a function of the respective values of the coma defects in vertical and horizontal direction to correct.

La correction de défaut est réalisée ainsi de façon particulièrement simple. En outre le moyen (ou procédé) de correction est aisément adaptable d'un type de tube à un autre car la longueur de chaque élément rectangulaire est une fonction directe de la hauteur du défaut de coma à corriger et, de même, la largeur de chaque élément est une fonction directe de la grandeur du défaut de coma en direction horizontale.The fault correction is carried out in a particularly simple manner. Furthermore, the correction means (or method) is easily adapted. ble from one type of tube to another because the length of each rectangular element is a direct function of the height of the coma defect to be corrected and, similarly, the width of each element is a direct function of the magnitude of the defect of coma in horizontal direction.

De plus la sensibilité du balayage horizontal est augmentée car, avec les éléments magnétiques de correction de l'invention, le champ magnétique de déviation horizontale est augmenté notamment pour les faisceaux latéraux alors que les éléments de correction connus jusqu'à présent diminuent la sensibilité du balayage horizontal, c'est-à-dire nécessitent une plus forte alimentation des déviateurs.In addition, the sensitivity of the horizontal scanning is increased because, with the magnetic correction elements of the invention, the magnetic field of horizontal deflection is increased in particular for the lateral beams while the correction elements known up to now decrease the sensitivity of the horizontal scanning, that is to say require a higher power supply of the deflectors.

D'autres caractéristiques et avantages de l'invention apparaîtront avec la description de certains de ses modes de réalisation, celle-ci étant effectuée en se référant aux dessins ci-annexés sur lesquels:

  • - la figure 1 est une coupe schématique d'un tube de télévision en couleurs du type à masque perforé,
  • - la figure 2 est un schéma montrant l'effet du défaut de coma sur l'écran du tube de la figure 1,
  • - la figure 3 montre des éléments de correction du défaut de la figure 2,
  • - la figure 4 est une coupe selon la ligne 4-4 de la figure 3,
  • - la figure 5 est un schéma analogue à celui de la figure 3, mais à plus grande échelle, montrant l'effet des éléments de correction sur les champs magnétiques de déviation, et,
  • - la figure 6 est un graphique montrant l'effet sur le défaut de coma des dimensions des éléments de correction de la figure 3.
Other characteristics and advantages of the invention will appear with the description of some of its embodiments, this being carried out with reference to the attached drawings in which:
  • FIG. 1 is a diagrammatic section through a color television tube of the perforated mask type,
  • FIG. 2 is a diagram showing the effect of the coma defect on the screen of the tube in FIG. 1,
  • FIG. 3 shows elements for correcting the defect in FIG. 2,
  • FIG. 4 is a section along line 4-4 of FIG. 3,
  • FIG. 5 is a diagram similar to that of FIG. 3, but on a larger scale, showing the effect of the correction elements on the magnetic deflection fields, and,
  • - Figure 6 is a graph showing the effect on the coma defect of the dimensions of the correction elements of Figure 3.

Dans l'exemple le tube de télévision en couleurs 10 est du type à masque perforé 11 disposé à l'intérieur du tube devant l'écran 12 et à canons à électrons 13 produisant trois faisceaux 14, 15 et 16 coplanaires. Le faisceau central 14 est, dans cet exemple, celui qui est destiné à exciter le phosphore vert sur l'écran tandis que les faisceaux latéraux 15 et 16 excitent les phosphores respectivement bleu et rouge.In the example, the color television tube 10 is of the type with a perforated mask 11 placed inside the tube in front of the screen 12 and with electron guns 13 producing three beams 14, 15 and 16 coplanar. The central beam 14 is, in this example, that which is intended to excite the green phosphorus on the screen while the lateral beams 15 and 16 excite the blue and red phosphors respectively.

Le déplacement de ces faisceaux, afin de balayer l'écran 12, est effectué en alimentant des bobines 17 de déviation horizontale et verticale qui produisent des champs magnétiques permettant le déplacement des trois faisceaux 14, 15, 16 respectivement en directions horizontale et verticale.The displacement of these beams, in order to scan the screen 12, is carried out by supplying coils 17 of horizontal and vertical deflection which produce magnetic fields allowing the displacement of the three beams 14, 15, 16 respectively in horizontal and vertical directions.

Les canons 13 sont disposés à l'arrière du tube dans la partie cylindrique 18 appelée le col. Les bobines de déviation 17 sont disposées en partie autour du col 18 et en partie autour de la section évasée 19 reliant le col 18 à la dalle 20 présentant l'écran 12.The barrels 13 are arranged at the rear of the tube in the cylindrical part 18 called the neck. The deflection coils 17 are arranged partly around the neck 18 and partly around the flared section 19 connecting the neck 18 to the slab 20 presenting the screen 12.

Le déviateur 17 est tel qu'il assure pratiquement l'autoconvergence, c'est-à-dire la convergence des trois faisceaux 14, 15, 16 sur tout l'écran. Mais il subsiste cependant le défaut de coma qui se traduit sur l'écran (figure 2) par des dimensions différentes des images produites par les trois faisceaux. Ainsi le faisceau central vert V 14 produit une image rectangulaire 21 tandis que les faisceaux latéraux bleu B et rouge R produisent une image 22, également rectangulaire, plus étroite et plus haute que l'image 21. Les côtés verticaux de l'image 22 sont donc entre les côtés verticaux de l'image 21, la distance d'entre deux côtés verticaux adjacents des images 21 et 22 étant, dans l'exemple (tube dont la diagonale d'écran mesure 51 cm), de l'ordre de 0,3 mm et les côtés horizontaux de l'image 21 sont entre les côtés horizontaux de l'image 22, la distance h entre deux côtés horizontaux voisins étant dans l'exemple de l'ordre de 0,8 mm.The deflector 17 is such that it practically ensures self-convergence, that is to say the convergence of the three beams 14, 15, 16 over the entire screen. However, there still remains the coma defect which is reflected on the screen (FIG. 2) by different dimensions of the images produced by the three beams. Thus the green central beam V 14 produces a rectangular image 21 while the blue lateral beams B and red R produce an image 22, also rectangular, narrower and higher than the image 21. The vertical sides of the image 22 are therefore between the vertical sides of image 21, the distance between two adjacent vertical sides of images 21 and 22 being, in the example (tube whose screen diagonal measures 51 cm), of the order of 0 , 3 mm and the horizontal sides of image 21 are between the horizontal sides of image 22, the distance h between two neighboring horizontal sides in the example being of the order of 0.8 mm.

Pour corriger les défauts de coma on modifie le champ magnétique à l'arrière du déviateur 17, c'est-à-dire du côté des canons 13. A cet effet on utilise des pastilles ou plaquettes à forte perméabilité magnétique qui sont supportées par la dernière électrode 23 (figures 3 et 4) des canons, c'est-à-dire l'électrode tournée vers l'écran 12. Cette électrode 23 a une forme de coupelle à bord cylindrique 25 et fond 24 perpendiculaire à l'axe 26 du tube. Ce fond est percé de trois trous ou ouvertures d'axes coplanaires se trouvant dans un plan passant par l'axe horizontal de l'écran. Le trou central 27 est destiné à laisser passer le faisceau vert 14 tandis que les trous latéraux 28 et 29 laissent passer les faisceaux bleu 15 et rouge 16. Les éléments magnétiques sont soudés au fond 24 de la coupelle 23. Ils sont constitués par des plaquettes en un alliage de fer-nickel.To correct coma defects, the magnetic field at the rear of the deflector 17 is modified, that is to say on the side of the barrels 13. For this purpose, pellets or plates with high magnetic permeability are used which are supported by the last electrode 23 (FIGS. 3 and 4) of the barrels, that is to say the electrode facing the screen 12. This electrode 23 has a cup shape with a cylindrical edge 25 and bottom 24 perpendicular to the axis 26 of the tube. This bottom is pierced with three holes or openings of coplanar axes lying in a plane passing through the horizontal axis of the screen. The central hole 27 is intended to allow the green beam 14 to pass through while the lateral holes 28 and 29 allow the blue 15 and red beams to pass through 16. The magnetic elements are welded to the bottom 24 of the cup 23. They consist of plates made of an iron-nickel alloy.

Selon l'invention on prévoit quatre plaquettes rectangulaires 30, 31, 32, 33 (réalisées en «an- hyster» à 48% de nickel) au-dessus et au-dessous des ouvertures 28 et 29. La plaquette rectangulaire 30 est au-dessus de l'ouverture 28 avec son grand côté 30, horizontal, le milieu de ce grand côté 30, étant au droit de l'axe du trou 28 destiné à laisser passer le faisceau d'excitation des phosphores bleus. Autrement dit la médiatrice du côté 30, passe par le centre du trou 28. La plaquette 31 est au-dessous du trou 28, dans une position symétrique de la plaquette 30 par rapport au centre du trou 18.According to the invention, four rectangular plates 30, 31, 32, 33 are provided (made of an "hyster" at 48% nickel) above and below the openings 28 and 29. The rectangular plate 30 is above the opening 28 with its large side 30, horizontal, the middle of this large side 30, being at the right of the axis of the hole 28 intended to allow the excitation beam of the blue phosphors to pass. In other words, the perpendicular bisector on the side 30 passes through the center of the hole 28. The plate 31 is below the hole 28, in a position symmetrical with the plate 30 relative to the center of the hole 18.

La plaquette 32 est disposée par rapport au trou 29, comme la plaquette 30 par rapport au trou 28. De même la plaquette 33 est disposée par rapport au trou 29 comme la plaquette 31 par rapport au trou 28.The plate 32 is disposed relative to the hole 29, like the plate 30 relative to the hole 28. Likewise the plate 33 is arranged relative to the hole 29 like the plate 31 relative to the hole 28.

Dans l'exemple l'axe du trou 27 est distant de 5,1 mm de l'axe du trou 28 ou 29 et l'épaisseur des plaquettes est de 0,25 mm. La longueur A de chacune de celles-ci, c'est-à-dire la dimension en direction horizontale, est de 3,8 mm tandis que sa largeur, c'est-à-dire la dimension en direction verticale, est L = 1,75 mm.In the example, the axis of the hole 27 is 5.1 mm away from the axis of the hole 28 or 29 and the thickness of the plates is 0.25 mm. The length A of each of these, that is to say the dimension in the horizontal direction, is 3.8 mm while its width, that is to say the dimension in the vertical direction, is L = 1.75mm.

Comme le montre la figure 5 les lignes 40 du champ magnétique Vx de déviation verticale sont écartées les unes des autres autour des trous 28 et 29. Le champ magnétique de déviation verticale est donc atténué pour l'image bleue-rouge. Par contre les lignes 41 de champ de déviation verticale sont, autour du trou 27, rapprochées les unes des autres: le champ magnétique de déviation verticale est donc augmenté pour le faisceau 14 d'excitation du vert. On obtient donc la correction dans le sens choisi: augmentation de la déviation verticale pour le vert et diminution de la déviation verticale pour le bleu et le rouge.As shown in FIG. 5, the lines 40 of the vertical deflection magnetic field Vx are spaced from one another around the holes 28 and 29. The vertical deflection magnetic field is therefore attenuated for the blue-red image. On the other hand, the lines of vertical deflection field 41 are, around the hole 27, close to one another: the magnetic field of vertical deflection is therefore increased for the beam 14 of excitation of the green. So we get the correction in the chosen direction: increase of the vertical deviation for green and decrease of the vertical deviation for blue and red.

La figure 5 montre également que les lignes de champ 42 de déviation horizontale Hy sont rapprochées les unes des autres autour des trous 28 et 29. Ces lignes de champ de déviation horizontale sont également rapprochées les unes des autres autour du trou 27, mais dans une moindre mesure. Le champ magnétique de déviation horizontale est donc augmenté pour les trois faisceaux d'excitation, mais il est plus augmenté pour les phosphores bleu et rouge que pour le vert. On obtient également le résultat recherché, c'est-à-dire une diminution relative de la déviation horizontale pour le vert par rapport à la déviation horizontale pour le bleu et le rouge.FIG. 5 also shows that the field lines 42 of horizontal deflection Hy are brought closer to each other around the holes 28 and 29. These lines of field of horizontal deflection are also brought closer to each other around the hole 27, but in a lesser extent. The horizontal deflection magnetic field is therefore increased for the three excitation beams, but it is more increased for the blue and red phosphors than for the green. The desired result is also obtained, that is to say a relative reduction in the horizontal deviation for green compared to the horizontal deviation for blue and red.

On a constaté que la correction de défaut de coma en hauteur (h, figure 2) dépendait surtout de la dimension A des plaquettes et que la correction de défaut de coma en largeur (d, figure 2) dépendait surtout de la dimension L. Pour un déviateur déterminé donnant des défauts d et h donnés il est donc aisé de choisir les dimensions A et L des plaquettes 30,31,32,33.It was found that the correction of a coma defect in height (h, Figure 2) depended mainly on the dimension A of the inserts and that the correction of a coma defect in width (d, Figure 2) depended mainly on the dimension L. For a determined deflector giving given faults d and h it is therefore easy to choose the dimensions A and L of the plates 30,31,32,33.

Pour le choix des dimensions A et B on peut s'aider des abaques de la figure 6. Sur le diagramme de cette figure 6 on a porté en abscisses la dimension A d'une plaquette, en ordonnées les défauts A de coma (d ou h).For the choice of dimensions A and B we can use the abacuses of figure 6. On the diagram of this figure 6 we have plotted on the abscissa the dimension A of a plate, on the ordinate the defects A of coma (d or h).

Les courbes 45, 46 et 47 sont des courbes de variation du défaut horizontal d de coma en fonction de la dimension A pour trois dimensions L, de valeurs respectivement Lo, L1 et L2.The curves 45, 46 and 47 are curves of variation of the horizontal defect d of coma as a function of the dimension A for three dimensions L, of values L o , L 1 and L 2 respectively .

Les courbes 48, 49 et 50 sont analogues aux courbes respectivement 45, 46 et 47 mais pour le défaut h de coma vertical.Curves 48, 49 and 50 are similar to curves 45, 46 and 47 respectively, but for the defect h of vertical coma.

Le champ magnétique de déviation horizontale Hy étant augmenté pour l'ensemble des trois faisceaux et plus particulièrement pour les deux faisceaux latéraux, les plaquettes selon l'invention permettent de diminuer l'énergie d'alimentation des bobines de déviation horizontale. En d'autres termes, contrairement aux réalisations antérieures, la correction n'est pas effectuée au détriment de la sensibilité de balayage horizontal.The magnetic field of horizontal deflection Hy being increased for all of the three beams and more particularly for the two lateral beams, the plates according to the invention make it possible to reduce the power supply energy of the coils of horizontal deflection. In other words, unlike previous embodiments, the correction is not carried out to the detriment of the horizontal scanning sensitivity.

Bien que dans l'exemple décrit ci-dessus le grand côté des plaquettes 30 à 33 soit horizontal il est à noter qu'en variante ces grands côtés peuvent avoir d'autres directions c'est-à-dire être obliques par rapport à l'horizontale. En outre ces grands côtés ne sont pas forcément tous parallèles entre eux.Although in the example described above, the long side of the plates 30 to 33 is horizontal, it should be noted that, as a variant, these long sides may have other directions, that is to say be oblique to the 'horizontal. In addition, these long sides are not necessarily all parallel to each other.

De préférence, les éléments 30 à 33 sont de simples plaquettes sans extension selon l'axe 26.Preferably, the elements 30 to 33 are simple plates without extension along the axis 26.

Claims (7)

1. Television color tube of autoconvergent type laving three coplanar electron beams (14, 15, 16) and magnetic coma error correction elements behind the deflector (17), characterized in that the coma errors being of small amplitude, in the order of 1 mm or less in each direction, and of opposite senses in the horizontal and vertical directions, the correction elements are exclusively constituted by four small plates (30, 31, 32, 33) of rectangular shape the plane of which is perpendicular to the axis (26) of the tube, these small plates being located above and below each of the lateral beams (15, 16), the center of one side of each small plate lying on a line perpendicular to the lateral corresponding beam, one dimension (A) of each of the small plates affecting the amplitude of the correction in one direction and the other dimension (L) affecting the coma correction in the other direction.
2. Tube according to claim 1, characterized in that, the coma error being such that the image (21 ) produced by the central beam is wider and of less height than the image (22) produced by the lateral beams, the rectangular small plates have their major dimension (A) in the horizontal direction.
3. Tube according to claims 1 or 2, characterized in that the small plates (30, 31, 32, 33) are all identical.
4. Tube according to claim 2, characterized in that the horizontal coma error being in the order of 0,3 mm and the vertical coma error in the order of 0,8 mm, the horizontal dimension of one small plate being of the order of 4,5 mm and its vertical dimension in the order of 1,25 mm, the distance separating two adjacent beams prior to their deflection being of the order of 5,1 mm.
5. Tube according to any of the preceding claims, characterized in that the small plates are, in a manner known per se, rigidly affixed to the last electrode (23) of the electron gun (13).
6. Tube according to claim 1, characterized in that the rectangular small plates have their major dimensions oblique with respect to the horizontal direction.
7. Tube according to claim 6, characterized in that the major dimensions of the rectangular small plates are not parallel to each other.
EP84400706A 1983-04-18 1984-04-10 Colour television tube with correction of low amplitude coma faults Expired EP0125949B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84400706T ATE28012T1 (en) 1983-04-18 1984-04-10 COLOR TELEVISION WITH A CORRECTION OF LOW AMPLITUDE COMA ERROR.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8306312 1983-04-18
FR8306312A FR2544548B1 (en) 1983-04-18 1983-04-18 COLORED TELEVISION TUBE WITH CORRECTION OF LOW AMPLITUDE COMA DEFECTS

Publications (2)

Publication Number Publication Date
EP0125949A1 EP0125949A1 (en) 1984-11-21
EP0125949B1 true EP0125949B1 (en) 1987-06-24

Family

ID=9287970

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84400706A Expired EP0125949B1 (en) 1983-04-18 1984-04-10 Colour television tube with correction of low amplitude coma faults

Country Status (7)

Country Link
US (1) US4725757A (en)
EP (1) EP0125949B1 (en)
JP (1) JPH077643B2 (en)
AT (1) ATE28012T1 (en)
DE (1) DE3464438D1 (en)
FR (1) FR2544548B1 (en)
HK (1) HK27090A (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3665111D1 (en) * 1985-09-27 1989-09-21 Hitachi Ltd Convergence correcting device capable of coma correction for use in a cathode ray tube having in-line electron guns
JP2661024B2 (en) * 1986-12-27 1997-10-08 ソニー株式会社 Cathode ray tube
FR2818799A1 (en) * 2000-12-22 2002-06-28 Thomson Tubes & Displays DEFLECTION SYSTEM FOR COLOR CATHODE RAY TUBE CORRECTED IN COMA HORIZONTAL
CN1261966C (en) 2002-10-02 2006-06-28 Lg飞利浦显示器(韩国)株式会社 Colour cathode-ray tube and electronic gun

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4142131A (en) * 1975-11-12 1979-02-27 Hitachi, Ltd. Color picture tube
JPS5845135B2 (en) * 1975-11-12 1983-10-07 株式会社日立製作所 Henkojikaiseigyososhitsukikara-jiyuzoukan
US4225804A (en) * 1978-04-22 1980-09-30 Gte Sylvania N.V. Cathode ray tube coma correction device
US4457733A (en) * 1980-09-29 1984-07-03 Zenith Radio Corporation Method for providing coextensive raster patterns in television CRT in-line electron guns
JPS5780640A (en) * 1980-11-07 1982-05-20 Toshiba Corp Color picture tube unit
US4370593A (en) * 1980-12-30 1983-01-25 Rca Corporation In-line electron gun and method for modifying the same
JPS57126047A (en) * 1981-01-30 1982-08-05 Hitachi Ltd Color cathode-ray tube
JPS57187844A (en) * 1981-05-15 1982-11-18 Toshiba Corp Magnetic focusing crt
DE3126344A1 (en) * 1981-07-03 1983-02-24 Anton Dr. 7900 Ulm Casel Deflection unit for a three-beam colour television tube

Also Published As

Publication number Publication date
FR2544548B1 (en) 1985-12-27
JPH077643B2 (en) 1995-01-30
DE3464438D1 (en) 1987-07-30
JPS59198641A (en) 1984-11-10
HK27090A (en) 1990-04-12
US4725757A (en) 1988-02-16
ATE28012T1 (en) 1987-07-15
FR2544548A1 (en) 1984-10-19
EP0125949A1 (en) 1984-11-21

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