EP0517320B1 - Farbbildröhre mit Coma-Korrektur - Google Patents
Farbbildröhre mit Coma-Korrektur Download PDFInfo
- Publication number
- EP0517320B1 EP0517320B1 EP19920201573 EP92201573A EP0517320B1 EP 0517320 B1 EP0517320 B1 EP 0517320B1 EP 19920201573 EP19920201573 EP 19920201573 EP 92201573 A EP92201573 A EP 92201573A EP 0517320 B1 EP0517320 B1 EP 0517320B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- field
- coma
- deflection
- display tube
- shaped
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 206010010071 Coma Diseases 0.000 title claims description 50
- 238000010894 electron beam technology Methods 0.000 claims description 16
- 206010073261 Ovarian theca cell tumour Diseases 0.000 claims description 4
- 208000001644 thecoma Diseases 0.000 claims description 4
- 238000011144 upstream manufacturing Methods 0.000 claims description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000011521 glass Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 201000009310 astigmatism Diseases 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910000595 mu-metal Inorganic materials 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
Images
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
- H01J29/70—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
- H01J29/702—Convergence correction arrangements therefor
- H01J29/703—Static convergence systems
Definitions
- the invention relates to a colour display tube comprising an electron gun of the "in-line" type for generating three electron beams whose axes are coplanar, a deflection unit comprising a first and a second deflection rail for generating a first and a second deflection field for deflecting the electron beams in the operating display tube across said display screen in two mutually perpendicular directions, the direction of the first deflection field being parallel to said plane, and convergence correction means which, during deflection, keep the electron beams converged on a display screen arranged on a wall of the envelope and having a short display screen axis and a long display screen axis.
- deflection units may be used for deflecting the electron beams in colour display tubes.
- these deflection units are generally self-convergent.
- conventional deflection units having field deflection coils of the saddle type and field deflection coils of the toroidal type the winding technique used does not permit of rendering the unit entirely self-convergent.
- coma a certain convergence error remains, which error is commonly referred to as coma.
- This coma error becomes manifest, for example, in a larger raster (horizontal and vertical) for the outer beams with respect to the central beam.
- the horizontal and vertical deflection of the central beam is smaller than that of the outer beams.
- this can be corrected by providing elements (referred to as field shapers) of a material (for example of mu-metal) having a high magnetic permeability around the outer beams at the end of the gun.
- the peripheral field at the arc of the outer electron beams is shielded to some extent by these elements, so that these beams are deflected to a lesser extent and the coma error is reduced.
- a first problem is that the shielding means around the outer electron beams detrimentally influence the spot shape of these beams.
- the correction of the field coma (Y coma) is anisotropic. In other words, the correction in the corners is less than the correction at the end of the field axis (the field axis is the display screen axis which is parallel to the field deflection direction). This is caused by the positive "lens" action of the line deflection coil (approximately quadratically with the line deflection) for vertical beam displacements. (The field deflection coil has a corresponding lens action, but it does not contribute to the relevant anisotropic effect.)
- a colour display tube of the type described in the opening paragraph is characterized in that the convergence correction means effect a first, or field deflection field which is characterized in that an electron beam entering the field deflection field first passes an area with a barrel-shaped delection field component and next an adjoining area with a pincushion-shaped deflection field component.
- convergence correction means comprise a first coma corrector which is positioned at the gun side of the first deflection coil and provides the pincushion-shaped field component, and a second coma corrector which, viewed in the direction of propagation of electrons, is positioned upstream of the first coma corrector and provides the barrelshaped field component.
- the invention is based, inter alia , on the recognition that the problem of the anisotropic Y coma (referred to as "green doop") can be reduced by making suitable use of the Z dependence of the anisotropic Y coma.
- This dependence implies that as the coma correction takes place at a larger distance (in the Z direction) from the "lens" formed by the line deflection coil, the action of said "lens” becomes more effective so that the coma correction acquires a stronger anisotropic character.
- the invention utilizes this aspect in that a pincushion-shaped component is realised at the entrance side of the field deflection field, so that coma is corrected, and in that barrel-shaped component is realised upstream of said area, so that the anisotropic character of the correction will be less anisotropic.
- Field coma errors at the end of the vertical axis and in the corners can be corrected effectively and to an approximately equal extent by effecting particularly a pincushion-shaped component which has a strength which is sufficient to correct the field coma in the corners, but which is more pincushion-shaped than is necessary for coma correction at the ends of the vertical axis, and by effecting a barrel-shaped vertical deflection field component at a location located closer to the electron gun or around the electron gun, which field component corrects the overcompensation at the ends of the vertical axis.
- the deflection unit can be moved in the axial direction, for example, for colour purity adjustment without this influencing the convergence.
- the display tube according to the invention is very suitable for use with a field deflection coil of the toroidal type, particularly when the display tube should be free from raster correction.
- Fig. 1 is a longitudinal section of a display tube according to the invention. It is a colour display tube of the "in-line" type.
- a glass envelope 1 which is composed of a display window 2, a cone 3 and a neck 4, said neck accommodates an integrated electron gun system 5 which generates three electron beams 6, 7 and 8 whose axes are coplanar prior to deflection.
- the axis of the central ("green") electron beam 7 coincides with the tube axis 9.
- the display window 2 has a large number of phosphor element triplets on its inner side. The elements may be rows or dots.
- Each triplet comprises an element of a blue-luminescing phosphor, an element of a green-luminescing phosphor and an element of a red-luminescing phosphor. All triplets combined constitute the display screen 10.
- the phosphor rows are substantially perpendicular to said plane through the beam axes.
- a shadow mask 11 having a very large number of elongate apertures 12 for passing the electron beams 6, 7 and 8 each impinging upon phosphor elements of one colour only is arranged in front of the display screen.
- the three coplanar electron beams are deflected by a system 13 of deflection coils, which is not completely self converging because of the fact that a field coma error occurs, which system comprises a line deflection coil 16, a yoke ring 15 and a field deflection coil 16'.
- Coma correction coil 14' produces a (positive) six-pole field by which a pincushion-shaped field distribution is effected so that the green beam is deflected in the direction of deflection of the field deflection coil to a greater extent than the side beams.
- Correction coil 14 produces a (negative) six-pole field by which a barrel-shaped field distribution is effected, so that the green beam is deflected in the direction of deflection of the vertical deflection coil to a lesser extent than the side beams.
- Green droop means that the field coma is corrected at the end of the vertical axis but is insufficiently corrected in the corners.
- Fig. 2a shows a situation where the field coma correction is insufficient
- Fig. 2b shows the green droop situation.
- This problem becomes worse as the axial distance between the location of coma correction and the centre of the line deflection coil increases.
- Use can be made of the axial dependence of the green droop for solving the problem of the green droop.
- the problem can be solved by overcorrecting the field coma at the entrance side of the field deflection field (see Fig. 2c) and by performing an opposite correction at a location "upstream" (see Fig.
- the method described in this Application is based on coma correction by means of field-shielding components arranged around the paths of individual electron beams.
- the drawback of coma correction by partially shielding the beams is that the spot shape of the side beams is detrimentally influenced.
- the invention provides, inter alia , a solution for correcting field coma and preventing the green droop, while the spot shape of the side beames is minimally influenced.
- the deflection unit can be moved in the axial direction, for example, for colour purity adjustment without any convergence side effects.
- Figure 3, 4 and 5 show modifications of embodiments of coma correctors 14' each comprising one or more magnetic cores with such a coil arrangement that a positive six-pole field is generated upon energization.
- Figures 3, 4 and 5 show, in this order, increasingly simplified embodiments (i.e. magnetic cores provided with fewer coils).
- the (overcompensated) coma correction can also be performed by means of coma correction means of the type used in the Philips colour display tube systems 30AX, 45AX or as described in PHN 10.667 (USP 4,524,340) or PHN 12.132 (USP 4,874,983).
- the corrector 14 which works in the opposite way and this enlarges the original coma error to some extent may comprise correctors of the type shown in Figs. 3, 4 and 5, with such an energization of the coils that the field direction is opposite to that shown in Figures 3, 4 and 5. This means that a negative sixpole field is generated.
Landscapes
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Claims (6)
- Farbbildröhre mit einem Elektronenstrahlerzeugungssystem (5) zum Erzeugen von drei Elektronenstrahlen (6, 7, 8), deren Achsen koplanar sind, mit einer Ablenkeinheit (13) mit einer ersten und einer zweiten Ablenkspule zum Erzeugen eines Bild- und eines Zeilen-Ablenkfeldes (16, 16') zum Ablenken der Elektronenstrahlen im Betrieb der Wiedergaberöhre über den genannten Wiedergabeschirm (10) in zwei senkrecht aufeinander stehenden Richtungen (x, y), wobei die Richtung des Bild-Ablenkfeldes sich parallel zu der genannten Ebene der Strahlenachsen erstreckt und mit Konvergenzkorrekturmitteln (14, 14'), die während der Ablenkung die Elektronenstrahlen auf einen an einer Wand der Hülle vorgesehenen Wiedergabeschirm konvergiert halten, und wobei der Schirm eine kurze und eine lange Achse aufweist, dadurch gekennzeichnet, daß die Konvergenzkorrekturmittel dazu beitragen ein Bild-Ablenkfeld herbeiführen, das eine derartige verteilung aufweist, daß die in das Bildablenkfeld eintreffenden Elektronenstrahlen zunächst durch ein Gebiet mit einem tonnenförmigen Ablenkfeldanteil hindurchgehen und danach durch ein Gebiet mit einem kissenförmigen Ablenkfeldanteil.
- Farbwiedergaberöhre nach Anspruch 1, dadurch gekennzeichnet, daß die Konvergenzkorrekturmittel eine erste Koma-Korrekturstufe (14') aufweisen, die an der Elektronenstrahlerzeugungssystemseite der BildAblenkspule vorgesehen ist und den kissenförmigen Bildfeldanteil schafft, und eine zweite Koma-Korrekturstufe (14), die, in der Fortpflanzungsrichtung der Elektronen gesehen, stromaufwärts der ersten Koma-Korrekturstufe vorgesehen ist und den tonnenförmigen Bildfeldanteil schafft.
- Farbwiedergaberöhre nach Anspruch 2, dadurch gekennzeichnet, daß die erste Koma-Korrekturstufe (14') an den Enden der kurzen Wiedergabeschirmachse die Koma überkompensiert und daß die zweite Koma-Korrekturstufe (14) die von der ersten Koma-Korrekturstufe erzeugte Überkompensation korrigiert.
- Farbwiedergaberöhre nach Anspruch 2, dadurch gekennzeichnet, daß die erste Koma-Korrekturstufe (14') ein auf wenigstens einem Kern gewickeltes Spulensystem aufweist, das bei Erregung ein Sechspol-Magnetfeld erzeugt.
- Farbwiedergaberöhre nach Anspruch 2, dadurch gekennzeichnet, daß die zweite Koma-Korrekturstufe (14) ein auf wenigstens einem Magnetkern gewickeltes Spulensystem aufweist, das bei Erregung ein Sechspol-Magnetfeld erzeugt.
- Farbwiedergaberöhre nach Anspruch 2, dadurch gekennzeichnet, daß wenigstens eine der Koma-Korrekturstufen wenigstens zwei plattenförmige Magnetelemente (17, 17') aufweist, die derart in dem Bildablenkfeld vorgesehen sind, daß ein Sechspolfeldanteil verwirklicht wird.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19920201573 EP0517320B1 (de) | 1991-06-05 | 1992-06-02 | Farbbildröhre mit Coma-Korrektur |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP91201380 | 1991-06-05 | ||
EP91201380 | 1991-06-05 | ||
EP19920201573 EP0517320B1 (de) | 1991-06-05 | 1992-06-02 | Farbbildröhre mit Coma-Korrektur |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0517320A2 EP0517320A2 (de) | 1992-12-09 |
EP0517320A3 EP0517320A3 (en) | 1993-11-18 |
EP0517320B1 true EP0517320B1 (de) | 1996-10-16 |
Family
ID=26129287
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19920201573 Expired - Lifetime EP0517320B1 (de) | 1991-06-05 | 1992-06-02 | Farbbildröhre mit Coma-Korrektur |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0517320B1 (de) |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3725831A (en) * | 1972-01-14 | 1973-04-03 | Rca Corp | Magnetic beam adjusting arrangements |
NL8300032A (nl) * | 1983-01-06 | 1984-08-01 | Philips Nv | Inrichting voor het weergeven van televisiebeelden en afbuigeenheid daarvoor. |
NL8301534A (nl) * | 1983-05-02 | 1984-12-03 | Philips Nv | Inrichting voor het weergeven van televisiebeelden met een afbuigeenheid met comacorrecties. |
NL8601003A (nl) * | 1986-03-28 | 1987-10-16 | Philips Nv | Kleurenbeeldbuis met een afbuigeenheid met beeldbalanscorrectiemiddelen. |
NL8701276A (nl) * | 1987-05-29 | 1988-12-16 | Philips Nv | Beeldweergeefsysteem met afbuigeenheid met dubbel zadelspoelenstelsel. |
-
1992
- 1992-06-02 EP EP19920201573 patent/EP0517320B1/de not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0517320A3 (en) | 1993-11-18 |
EP0517320A2 (de) | 1992-12-09 |
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