US3668580A

US3668580A - Toroidal deflection yoke having asymmetrical windings

Info

Publication number: US3668580A
Application number: US95847A
Authority: US
Inventors: Robert Lloyd Barbin
Original assignee: RCA Corp
Current assignee: RCA Licensing Corp
Priority date: 1970-12-07
Filing date: 1970-12-07
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06
Also published as: FR2117187A5; BR7108077D0; IT946061B; CA955992A; ES397751A1; DE2159385C3; NL7116732A; AT333860B; SE373230B; ATA1035071A; BE776321A; DE2159385B2; GB1373524A; DE2159385A1

Abstract

A toroidal deflection yoke for a delta gun shadow mask color television picture tube includes windings having asymmetric conductor distributions to correct for effects such as unsymmetrical misconvergence of the electron beams across the scanned raster. For convergence which is unsymmetrical top to bottom, an asymmetric change top to bottom is made in the conductor distribution in either the horizontal or vertical coil windings and for convergence which is unsymmetrical left to right an asymmetric change left to right is made in the conductor distributions in either the horizontal or vertical coil windings.

Description

United States Patent Barbin [541 TOROIDAL DEFLECTION YOKE HAVING ASYMIVIETRICAL WINDINGS [72] Inventor; Robert Lloyd Barbin, Lancaster, Pa. [73] Assignee: RCA Corporation [22] Filed: Dec. 7, 1970 [21] Appl.N0.: 95,847

52 05.0. ..335/213,3l3/76 51 man. .;....H 01ts 5s FieldofSearch ..335/2l0,2 l3;313/75,76,77; 336/229; 315/27 [56] References Cited UNITED STATES PATENTS 2,925,542 2/1960 Gethmann ..3 1 7/200 3,430,099 2/ l 969 Ashly ..3 /27 3,548,350 12/1970 Archer .335/2l0 VERT. WIRES- HORIZ. WIRES- 1 June 6, 1972 FOREIGN PATENTS 0R APPLICATIONS 514,170 11/1939 Great Britain ..335/2l0 Primary Examiner-George Harris Attorney-Eugene M. Whitacre ABS! RACT A toroidal deflection yoke for a delta gun shadow mask color television picture tube includes windings having asymmetric conductor distributions to correct for effects such as unsymmetrical rnisconvergence of the electron beams across the scanned raster. For convergence which is unsymmetrical top to bottom, an asymmetric change top to bottom is made in the conductor distribution in either the horizontal or vertical coil windings and for convergence which is unsymmetrical left to right an asymmetric change left to right is made in the conductor distributions in either the horizontal or vertical coil windings.

8 Claims, 5 Drawing Figures PATENTEDJUH s we SHEET 10F 2 //v VEN TOR Robert L. Barbz'n B A T TORNE Y PATENTEDJun 6|9I2 3,668,580

sum 20F z SZMGREEN) MBLUE) (3Z1(BLUE)/3IQ(RED) BICL (RED) 34 G 30 -\*33(GREEN) ssmREEm Fig, 2. Fig. 3.

VERT. WlRES-- HORIZ. WIRES- O #vygvfoe Robert L. Barbin ATTORNEY TOROIDAL DEFLECTION YOKE HAVING.

- ASYMMETRICAL WINDINGS BACKGROUND OF THE INVENTION This invention relates to toroidal deflection yokes having asymmetrical conductor winding distributions.

The problem of minimizing the misconvergence of the three electron beams emitted'by the electron guns of .a delta gun shadow mask color television picture tube as the'beams are deflected to form a raster scan are well recognized. The problem of minimizing the misconvergence, particularly in the cornerslof the raster, increases as large screen wide deflection angle kinescopes, such as the 25V 110 kinescopes, are utilized in television receivers. In the past sometimes it has been necessary to utilize expensive and relatively complex dynamic comer correction circuitry in conjunctionwith saddle-type deflectionyokes in addition to the normal horizontal and vertical scan rate dynamic correction circuitry to achieve acceptable convergence. It is known that toroidal deflection yokesmay be utilized advantageously with large screen wide deflection angle kinescopes. One example of such a toroidal yoke is disclosed in copending application Ser. No. 42,927 filed June 3, 1970, by Wayne R. Chiodi and entitled Toroidal Electromagnetic Deflection Yoke. This application describes a toroidal deflection yoke which requires no dynamic corner convergence correction. The conductor winding distribution in each of the symmetrical vertical and horizontal coil portions is such that only a minimum number of parameters, i.e., number of conductor turns and spacing of conductors, need be varied for producing a yoke which yields satisfactory performance. Such a yoke is desirable in that it is less expensive to make than saddle-type yokes and does not require the use of dynamic comer convergence correction circuitry in addition to the dynamic convergence circuitry ordinarily used.

However, there are some aspects of the convergence problem that are extremely difficult if not impossible to correct with a deflection yoke having symmetrical conductor distributions in each portion of the horizontal and vertical deflection coils. For example, theasymmetrical disposition of the three electron guns in the neck of the kinescope afiects the convergence differently at the top of the raster than at the bottom. This is caused by the guns being at the apices of an equilateral triangle with the red and green guns lying along one horizontal line and the blue gun being disposed between the 'red and green guns not on the same line. Even though a symmetrical yoke' produces a symmetrical field it is in general non-uniform so that the blue beam, for example, which is displaced vertically in the neck of the tube, such that when deflected to the top goes through a portion of the yoke field which has a different shape than the portion of the yoke field it goes through when deflected to the bottom. A similar situation exists for the red and green beams. Further, it has been determined that misconvergence from the left side of the raster to the right may change as a function of the direction of scan. In the following specification, the misconvergence will be described in relation to individual scanning lines of the red, blue and green electron beams and of the composite scan raster of the red, blue and green electron beams. The term crossover refers to the condition in which the red beam is low on the left and high on the right side of the raster in relation to the green electron beam. The term crossunder" refers to the condition in which the red electron beam is high on the left side and low on the right side of the raster in relation to the green electron beam. I

In accordance with the invention a toroidal yoke for a delta gun shadow mask color television picture tube comprises vertical and horizontal winding conductors in each of four quadrants defined by the vertical and horizontal deflection axis. To correctfor unsymmetrical convergence of the raster lines top to bottom, the conductors of one of the vertical and horizontal coil winding portions in the top two quadrants have an asymmetric distribution relative to the conductors of the corresponding one of the vertical and horizontal coil winding portions in the bottom two quadrants. To correct for unsymmetrical convergence leftv to right, the conductors of one of the vertical and horizontal coil winding portions in the two left quadrants have an asymmetric distribution relative to the conductors of the corresponding one of the vertical and horizontal coil winding portions in the two right quadrants.

In one embodiment the yoke is designed to operate in conjunction with a kinescope displaying both top to bottom and left to right misconvergence of the raster lines. The conductors in one of the vertical and horizontal coil winding portions in the top two quadrants have an asymmetrical winding distribution relative to the conductor distribution of the corresponding coil winding portions in the bottom two quadrants and the conductors in one of the vertical and horizontal coil winding portions in the two left quadrants have an asymmetric distribution relative to the conductors in the corresponding coil winding portions in the two right quadrants.

In another embodiment the conductors of both the vertical and horizontal coil winding portions of two adjacent quadrants lying on one side of one of the deflection axes have respective asymmetric distributions relative to the conductors of the corresponding coil winding portions of adjacent quadrants lying on the other side of the particular deflection axis.

FIG. 1 is a side view, partly broken and partly in section of a kinescope and a toroidal deflection yoke positioned relative thereto;

FIG. 2 is a diagrrna illustrating top to bottom unsymmetrical convergence of the scanning lines of a raster of a color television picture tube;

FIG. 3 is a diagram illustrating left to right unsymmetrical convergence of the scanning lines of a-raster of a color television picture tube;

FIG. 4 is a diagram illustrating the asymmetrical winding distribution of a toroidal deflection yoke according to the invention; and

FIG. 5 is a schematic representation of the windings of the yoke illustrated in FIG. 4.

DESCRIPTION OF THE INVENTION dots 14 are disposed on the inside surface of the faceplate 13.

Mounted within picture tube 11 is a shadow mask 15 having apertures 16 through which the electron beams are directed to impinge upon the phosphor dots 14. The rear portion of picture tube 11 contains an electron gun assembly 17 including three electron guns disposed at the apices of an equilateral triangle, the red and green guns lying on the left and right sides of the bottom of the triangle and the blue gun disposed at a point midway between and above the red and green guns. A getter structure 18 is mounted adjacent the electron gun assembly along the inside surface of glass envelope 12. The getter extends beyond deflection yoke 20 and terminates in a structure 19 disposed against the envelope in front of the deflection yoke. The getter is flashed after the tube envelope is sealed and evacuated to eliminate any gases remaining within the sealed envelope. v

A toroidally wound deflection yoke 20 encircles the flared bulb section of picture tube 11, the inside surface of which electron beams horizontally and vertically to scan a raster on the faceplate 13. The return portions of conductors 21 are stretched between the front and

rear rings

24 and 23 on the outside of core 22.

FIG. 2 is a diagram'illustrating in exaggerated form scanning lines of the red, blue and green electron beams at the top and I bottom of a raster. The raster lines illustrated in FIG. 2 could be observed on the face of kinescope ll of FIG. 1 when appropriate operating potentials and test signals are applied to the'system. At the bottom of rectangular raster 30 are three scanning lines; a red line 31, a blue line 32 and a green line 33. In this illustration the red, blue and green lines at the bottom of theraster are superimposed and the red and

green lines

31 and 33 are shown dotted for illustrative purposes. FIG. 2

shows a raster which illustrates a type of asymmetric top to bottom beam convergence which may be encountered when a symmetrically wound toroidal yoke, one having symmetrical conductor distributions in all four quadrants, is utilized with a delta gun shadow mask picture tube. The

lines

31, 32 and 33 at the bottom of the raster are shown as representing an ideal situation in which the width of the three lines is the same and the convergence is the same from one side of the raster to the other. At the top of raster 30 are shown a red line 31a, a blue line 32a and a green line 33a. The lines at the top of the raster illustrate a form of unsymmetrical misconvergence which is blue lines cross at a point 34 in the center of the raster. This ideal condition inthe center of the raster is caused by the static on-axis convergence apparatus which is normally adjusted to create this condition. In the prior art, with the red,

'blue and green rasters as illustrated in FIG. 2 the misconvergence condition wouldbe improved by altering symmetrically the winding distribution of the yoke conductors. Such a scheme is describedin the copendingChiodi application previously referred to. However, any symmetrical change in the distribution of the yoke conductors to improve the misconvergence at the top of the raster would result in the previously converged lines at the bottom of the raster becoming misconverged. Thus, a compromise would have to be achieved whereby the m'isconvergencewas balanced as closelyas possible between the top and bottom portions of the raster. i I

' FIG. 3 is a diagram illustrating a raster 30 in which the red, blue and green rasters are misconverged left to right across the raster. For the purpose of explaining this raster condition it will be assumed that there is no top to bottom unsymmetrical misconvergence such as described in conjunction with FIG. 2. Further, to simplify the explanation of the left to right unsymmetrical misconvergence problem the raster 30 in FIG. 3 is shown to have unsymmetrical misconvergence only at the bottom of the rasterand not at the top. Thus, the red, blue and

green raster lines

310, 32a and 33a, respectively, at the top of the raster are superimposed and are of the same width. The red and

green raster lines

31a and 33a are shown dotted and slightly separated for illustrative purposes.

At the bottom of raster 30 of FIG. 3 the red line 31 is shown high on the left and high on the right relative to green raster line 33. As illustrated in FIG. 3, the blue raster line 32 is located vertically halfway between the red and green lines and is approximately the same width as the red and green lines but it is shifted to the left relative to those lines. It is believed this conditionis created by the interaction of the electromagnetic scanning field and the getter structure, which, as illustrated in FIG. 1, extends through and beyond the yoke core. It should be noted that if the direction of the horizontal scan is reversed from the direction indicated in FIG. 2 the position of the red and green lines is reversed from that shown, and the blue line is shifted to the right relative to the red and green lines.

Similar to the situation described in conjunction with FIG. 2, if a prior art symmetrically wound toroidal yoke were utilized with a kinescope displaying a raster condition as shown in FIG. 3, the approach to correct the unsymmetrical misconvergence would be to symmetrically change the conductor distribution in the yoke quadrants. However, any change which is made to improve the left side misconvergence would only make the right side worse, or vice versa.

To solve the misconvergence problem illustrated in FIG. 3 in which there was no left to right misconvergence at the top of the raster but only at the bottom, the yoke was built having left to right conductor asymmetry only in the two lower quadrants. However, it is to be understood that it may be desirable to change the conductor asymmetry slightly in the top two quadrants as well to correct the problem. This is best determined empirically when designing a yoke for a particular type kinesco e. Further, if the left to right misconvergence were present at the top and bottom of the raster the yoke would have asymmetric conductors left to right in both the top and bottom quadrants.

The raster conditions illustrated in FIGS. 2 and 3 were discussed separately for simplicity, but it is to be understood that both conditions may exist simultaneously. Thus, attempting to correctthe unbalanced top to bottom and left to right misconvergence by symmetrically changing the conductor distribution in the quadrants of a toroidal yoke cannot eliminate the problem which is caused by the asymmetry of the delta electron gun assembly and the interaction of the horizontal scanning field with the getter.

FIG. 4 is a diagrammatic view illustrating a typical winding distribution of a toroidally wound deflection yoke according to the invention. This yoke has an asymmetric conductor distribution to compensate for the unsymmetrical misconvergence conditions illustrated in FIGS. 2 and 3. The view represents the active conductors at the front or large end of the yoke. The yoke comprises a ferrite core 40 having a first layer of conductors 41 and a second layer of conductors 42 wound around the core. Although the conductors are shown in two layers, the conductors may actually comprise a single layer with first layer representing the first group of conductors wound about the core, and the second layer representing another group of conductors subsequently wound on the core and interspersed between the conductors first laid down. It is to be understood that the return wires for conductors 41 and 42 would be disposed around the front of the yoke and travel to the back of the yoke outside the core 40. The yoke illustrated is divided into quadrants I, II, III, and IV by respective vertical and

horizontal axes

43 and 44, respectively. As illustrated the wires comprising the vertical deflection coil are indicated by the conductors marked with an X." The horizontal wires are unmarked. It should be noted that the conductor distribution of the first layer of conductors 41 is symmetrical in all four quadrants. The conductors 41 are interconnected with the conductors 42 of the second layer as shown schematically in FIG. 5 with reference to the letters of each coil winding portion. For the purpose of describing the invention, attention will be given to the conductors 42 in the second layer, the second layer containing the asymmetric distribution of conductors in the different quadrants.

The yoke illustrated in FIG. 4 is wound to correct for bothtop to bottom and left to right unsymmetrical misconvergence. For simplicity the winding distribution affecting each of the misconvergence will be described separately.

' The conductor distribution for correcting the top to bottom unsymmetrical misconvergence illustrated inFIG. 2 is shown in quadrants I and IV of FIG. 4. It is to be understood that if the yoke were only required to correct a top to bottom misconvergence problem that the winding distribution in quadrant III would be symmetrical with that of quadrant IV; quadrants I and II would also be symmetrical, shown. Referring to the conductor distribution in quadrant I extending I then one space,

I red lines are above the counterclockwise from horizontal axis 44, horizontal conductorsextend to 0, then one space, vertical conductors from H ,to G, tow spaces and horizontal conductors-from P to Q.

Referring to the conductor distribution in quadrant IV extending clockwise from axis 44, horizontal conductors extend to N, vertical conductors from o to'N', one space, two horizontal conductors, one space and three horizontal conductors extending to L. Therefore, it can be seen that there is. an asymmetry in the horizontal conductors between quadrants I and IV. This asymmetry alters the deflection field such that the unsymmetrical misconvergence top to bottom as seen in FIG. 2 is greatly reduced. It should be noted that the horizontal conductor distribution was altered to accomplish this. However, it has been determined that the vertical conductors in quadrants I and IV (and II and III) could also have their distribution altered asymmetrically depending on the type of change required. Further, both the vertical and horizontal conductor distribution in the top and bottom quadrants could be altered asymmetrically if the misconvergence problem requires that amount of change. The choice of which conductors to alter can best be determined empirically for a given type yoke-kinescope combination. The fundamental teaching of the invention is that the conductor distribution of the top quadrant must be asymmetric relative to the distribution of the conductors in the bottom two quadrants to achieve the best balance of top to bottom unsymmetrical misconvergence.

The approach to providing a toroidal deflection yoke which will correct left to right unsymmetrical misconvergence such as illustrated in FIG. 3 is similar to that described above for top to bottom unsymmetrical misconvergence. Referring again to FIG. 4, it should be noted that the conductor distribution, both vertical and horizontal, is the same in the right and left quadrants I and II. However, it should be noted that there is asymmetry between the horizontal conductors in the second layer 42 of the bottom pair of left and right quadrants III and IV. In quadrant III the pertinent horizontal conductors are grouped one conductor, one space and four conductors. As can be seen in FIG. 4, the pertinent horizontal conductors in layer 42 of quadrant IV are grouped two conductors, one

space and three conductors. This asymmetry of conductors corrects the misconvergence illustrated in FIG. 3 in which the green lines at both the left and right and the blue line is shifted to the left. It has been determined that the asymmetric conductor distribution should be made in that portion of the yoke corresponding to its closest associated portion of the raster. Thus, in FIG. 3 the left to right misconvergence was present at the bottom of the raster and not the top so only the conductors in the bottom two quadrants of FIG. 4 have their distribution asymmetrical. As mentioned in conjunction with the top to bottom misconvergence discussion, it is also applicable to a left to right misconvergence problem that the conductor distribution of either or both of the vertical and horizontal conductors in the left and right quadrants may be made asymmetrical to minimize and best balance the unsymmetrical misconvergence.

As described above, a toroidal yoke may be built according to the invention to correct either or both of the top to bottom and left to right convergence problems. The yoke illustrated in FIG. 4 corrects for both the convergence problems illustrated in FIGS. 2 and 3.

FIG. 5 is a schematic representation of the yoke windings illustrated in FIG. 4. The letters in FIG. 5 correspond to the letters of the end conductors of winding portions in FIG. 4. The horizontal coil windings may be series or parallel connected to be driven by vacuum tube or transistor deflection current sources. For series connection temiinals A and J are jumpered and the deflection current is applied to terminals Q and H. For parallel connection terminals J and H and Q and A, respectively, are jumpered and the deflection current applied to the two jumpered terminals. The vertical coil windings are noramlly series connected as shown and the vertical deflection current is applied between terminals Q and A.

The invention was described as being incorporated in a toroidal deflection yoke which corrected for asymmetrical misconvergence caused by the asymmetry of the delta electron gun assembly and the interaction of the electromagnetic scanning field with the getter. However, the same technique of building a yoke having asymmetric conductor distributions may be applied to correct for other system convergence unbalances such as caused by the vertical component of the earth's magnetic field. It should be noted that only the normal on-axis dynamic convergence waveforms are required for a system utilizing a deflection yoke in accordance with the invention. No special dynamic corner correction waveform circuitry is required as the asymmetric windings eliminates the need therefor.

What is claimed is:

1. A toroidal deflection yoke for a delta gun shadow mask color television picture tube displaying a raster having unsymmetrical convergence along one of the deflection axes, comprising:

vertical and horizontal coil winding portions in each of four quadrants defined by the vertical and horizontal deflection axes,

the conductor distribution of one of the vertical and horizontal coil winding portions in a first quadrant being selected to be asymmetrical relative to the winding distribution of the corresponding one of the vertical and horizontal coil winding portions of a second quadrant adjacent said first quadrant, said first and second quadrants lying on one side of the deflection axis along which said unsymmetrical convergence appears 2. A toroidal deflection yoke according to claim 1 wherein said raster displays unsymmetrical top to bottom convergence and the conductor distribution of coil winding portions of one of two adjacent top and bottom quadrants bounded by the vertical deflection axis is asymmetric relative to the conductor distribution of corresponding coil winding portions in the other of said quadrants.

3. A toroidal deflection yoke according to claim 1 wherein said raster displays unsymmetrical left to right convergence and the conductor distribution of coil winding portions of one of two adjacent left and right quadrants bounded by the horizontal deflection axis is asymmetric relative to the conductor distribution of corresponding coil winding portions in the other of said quadrants.

4. A toroidal deflection yoke for a delta gun shadow mask color television picture tube in which tube the electron beams are unsymmetrically misconverged top to bottom and left to right, comprising:

vertical and horizontal coil winding portions in each of four quadrants defined by the vertical and horizontal deflection axes of said yoke;

the conductor distribution of at least one of the vertical and horizontal coil winding portions in one of adjacent quadrants on one side of and bounded by the vertical deflection axis being asymmetric relative to the coil winding distribution of the corresponding at least one of the vertical and horizontal coil winding portions of the other of said adjacent quadrants for producing a magnetic field for correcting said unsymmetrical top to bottom misconvergence; and

the conductor distribution of at least one of the vertical and horizontal coil winding portions in one of adjacent quadrants on one side of and bounded by the horizontal deflection axis being asymmetric relative to the coil winding distribution of the corresponding at least one of the vertical and horizontal coil winding portions of the other of said adjacent quadrants for producing a magnetic field for correcting said unsymmetrical left to right misconvergence.

5. A toroidal defection yoke according to claim 4 wherein the conductor distribution of the horizontal coil winding portions of one of adjacent quadrants bounded by the vertical deflection axes is asymmetrical relative to the conductor of .7 the other of said adjacent quadrants bounded by said vertical deflection axis; and V the conductor distribution of the horizontal coil winding 7 portions of one of adjacent quadrants bounded by the horizontal deflection axis is asymmetrical relative to the conductor distribution of the other of said adjacent quadrants bounded by said horizontal deflection axis.

6. A toroidal deflection yoke according to claim 4 wherein the conductor distribution of the vertical coil winding portions of one of adjacent quadrants bounded by the vertical deflection axes is asymmetrical relative to the conductor of the other of said adjacent quadrants bounded by said vertical deflection other of said quadrants bounded by the vertical deflection axis; and

the conductor distribution of both horizontal and vertical coil winding portions in one of two adjacent quadrants bounded by the horizontal deflection axis is asymmetric relative to the corresponding horizontal and vertical coil winding portions in.the other of said quadrantsbounded by the horizontal deflection axis.

8. A toroidal deflection yoke for a delta gun shadow mask color television picture tube, the electron beams of which picture tube are unsymmetrically converged top to bottom and left to right, comprising:

vertical and horizontal coil winding portions in each of four quadrants defined by the deflection axes of the yoke, the number of conductor turns in each coil winding portion being the same in all of said quadrants;

the distribution of conductors of at least one of the vertical and horizontal coil winding portions in one of two adjacent quadrants on one side of and bounded by the vertical deflection axis being asymmetric relative to the conductor distribution of the corresponding at least one of the vertical and horizontal coil winding portions in the other of said two adjacent quadrants for producing a deflection field such as to correct said top to bottom unsymmetrical misconvergence; and

the distribution of conductors of at least one of the vertical and horizontal coil winding portions in one of two adjacent quadrants on one side of and bounded by the horizontal deflection axis being asymmetric relative to the conductor distribution of the corresponding at least one of the vertical and horizontal coil winding portions in the other of said two adjacent quadrants for producing a deflection field such as to correct said left to right unsymmetrical misconvergence.

Disclaimer 3,668,580.Robe1't Lloyd Barbi'n, Lancaster, Pa. TOROIDAL DEFLEC- TION YOKE HAVING ASYMMETRIOAL WINDINGS. Patent dated June 6, 1972. Disclaimer filed Oct. 16, 1972, by the assignee,

RCA Corporation. Hereby enters this disclaimer to claims 1 and 3 of said patent.

[Oficz'al Gazette December 24, 1974.]

Disclaimer 3,668,580.R0be1't Lloyd Barbi n, Lancaster, Pa. TOROIDAL DEFLEC- TION YOKE HAVING ASYMMETRICAL WINDINGS. Patent dated June 6, 1972. Disclaimer filed Oct. 16, 1972, by the assignee,

[Oflicz'al Gazette December 24, 1.974.]

Claims

1. A toroidal deflection yoke for a delta gun shadow mask color television picture tube displaying a raster having unsymmetrical convergence along one of the deflection axes, comprising: vertical and horizontal coil winding portions in each of four quadrants defined by the vertical and horizontal deflection axes, the conductor distribution of one of the vertical and horizontal coil winding portions in a first quadrant being selected to be asymmetrical relative to the winding distribution of the corresponding one of the vertical and horizontal coil winding portions of a second quadrant adjacent said first quadrant, said first aNd second quadrants lying on one side of the deflection axis along which said unsymmetrical convergence appears

2. A toroidal deflection yoke according to claim 1 wherein said raster displays unsymmetrical top to bottom convergence and the conductor distribution of coil winding portions of one of two adjacent top and bottom quadrants bounded by the vertical deflection axis is asymmetric relative to the conductor distribution of corresponding coil winding portions in the other of said quadrants.

4. A toroidal deflection yoke for a delta gun shadow mask color television picture tube in which tube the electron beams are unsymmetrically misconverged top to bottom and left to right, comprising: vertical and horizontal coil winding portions in each of four quadrants defined by the vertical and horizontal deflection axes of said yoke; the conductor distribution of at least one of the vertical and horizontal coil winding portions in one of adjacent quadrants on one side of and bounded by the vertical deflection axis being asymmetric relative to the coil winding distribution of the corresponding at least one of the vertical and horizontal coil winding portions of the other of said adjacent quadrants for producing a magnetic field for correcting said unsymmetrical top to bottom misconvergence; and the conductor distribution of at least one of the vertical and horizontal coil winding portions in one of adjacent quadrants on one side of and bounded by the horizontal deflection axis being asymmetric relative to the coil winding distribution of the corresponding at least one of the vertical and horizontal coil winding portions of the other of said adjacent quadrants for producing a magnetic field for correcting said unsymmetrical left to right misconvergence.

5. A toroidal defection yoke according to claim 4 wherein the conductor distribution of the horizontal coil winding portions of one of adjacent quadrants bounded by the vertical deflection axes is asymmetrical relative to the conductor of the other of said adjacent quadrants bounded by said vertical deflection axis; and the conductor distribution of the horizontal coil winding portions of one of adjacent quadrants bounded by the horizontal deflection axis is asymmetrical relative to the conductor distribution of the other of said adjacent quadrants bounded by said horizontal deflection axis.

6. A toroidal deflection yoke according to claim 4 wherein the conductor distribution of the vertical coil winding portions of one of adjacent quadrants bounded by the vertical deflection axes is asymmetrical relative to the conductor of the other of said adjacent quadrants bounded by said vertical deflection axis; and the conductor distribution of the vertical coil winding portions of one of adjacent quadrants bounded by the horizontal deflection axis is asymmetrical relative to the conductor distribution of the other of said adjacent quadrants bounded by said horizontal deflection axis.

7. A toroidal deflection yoke according to claim 4 wherein the conductor distribution of both horizontal and vertical coil winding portions in one of two adjacent quadrants bounded by the vertical deflection axis is asymmetric relative to the corresponding horizontal and vertical coil winding portions in the other of said quadrants bounded by the vertical deflection axis; and the conductor distribution of both horizontal and vertical coil winding portions in one of two adjacent quadrants bounded by the horizontal deflection axis is asymmetric relative to the corresponding horizontal and vertical coil winding portions in the oTher of said quadrants bounded by the horizontal deflection axis.

8. A toroidal deflection yoke for a delta gun shadow mask color television picture tube, the electron beams of which picture tube are unsymmetrically converged top to bottom and left to right, comprising: vertical and horizontal coil winding portions in each of four quadrants defined by the deflection axes of the yoke, the number of conductor turns in each coil winding portion being the same in all of said quadrants; the distribution of conductors of at least one of the vertical and horizontal coil winding portions in one of two adjacent quadrants on one side of and bounded by the vertical deflection axis being asymmetric relative to the conductor distribution of the corresponding at least one of the vertical and horizontal coil winding portions in the other of said two adjacent quadrants for producing a deflection field such as to correct said top to bottom unsymmetrical misconvergence; and the distribution of conductors of at least one of the vertical and horizontal coil winding portions in one of two adjacent quadrants on one side of and bounded by the horizontal deflection axis being asymmetric relative to the conductor distribution of the corresponding at least one of the vertical and horizontal coil winding portions in the other of said two adjacent quadrants for producing a deflection field such as to correct said left to right unsymmetrical misconvergence.