MXPA96006576A - Deflection coil with reduced distortion of - Google Patents

Abstract

The present invention relates to a deflection coil mounted on a neck of a cathode ray tube, comprising: a core made of magnetic material, a horizontal deflection winding arranged adjacent to the core to produce a horizontal deflection field; vertical deflection winding disposed adjacent the core to produce a vertical deflection field including a pair of chair-shaped coils, each with a plurality of winding turns forming first and second side sections extending in a longitudinal direction of the bobbin, a front end turn section, disposed adjacent a screen end of the bobbin between the first and second side sections, and a rear end turn section disposed remote from the screen end and between the side sections, the end section Extreme back turn is built in such a way that it concentrates most of its deva turns swimming near a barrel end to maintain a ratio less than 0.15, between a length of a region of the rear end turn section that includes 50% of all winding turns in the rear end turn section, including the turn of winding closest to the end of the barrel, and an effective length of the vertical deflection field, which results in a center of vertical deflection that is shifted to one side of the barrel of the spool relative to a center of horizontal deflection, thereby that a relation between a first length separating the centers of deviation and an effective length of the field of vertical deviation is greater than 0.09, in order to significantly reduce the distortion of the shape

Description

DEFLECTION COIL WITH REDUCED NETWORK DISTORTION DESCRIPTION OF THE INVENTION The invention relates to a color kinescope image system (CRT). A CRT with a large screen size, such as a 89 cm diagonal, which is substantially flat is more susceptible to geometric distortions than a CRT with a non-planar face plate. To obtain high performance, a support-support deflection (S-S) coil has been used. An S-S offset coil has the advantage of providing design flexibility not available in a toroidal support (S-T) construction. North-South spin distortion (NS-spin) is a geometric distortion that distorts straight horizontal lines in parabolas. NS-spin distortion is more difficult to correct on a CRT that has a 4: 3 aspect ratio than on a CRT that has an aspect ratio of 16: 9. Permanent magnets have been used to correct the distortion of NS-turn in a CRT having an aspect ratio of 4: 3. This is achieved by mounting two small bar magnets horizontally at the top and at the bottom, respectively, of the front end of the vertical deflection coil, referred to as spin magnets. It may be desirable to reduce the distortion of NS-turn in a CRT having a 4: 3 aspect ratio without using permanent magnets. This is due to the tolerance in permanent magnets that tends to vary over a large scale. In addition, when the CRT screen is large such as a 89 cm diagonal, the magnets can not provide adequate correction. In addition, the magnets may have an undesirable effect, for example, in coverage or color purity.

BRIEF DESCRIPTION OF THE INVENTION One embodiment of the deflection coil in one aspect of the invention includes a vertical deflection winding disposed adjacent a core to produce a vertical deflection field. The vertical deflection winding includes a pair of chair-shaped coils, each having a plurality of winding turns forming first and second side sections extending in a longitudinal direction of the coil. The vertical deflection winding includes a front end turn section, disposed adjacent a screen end of the spool, between the first and second side sections and a rear end turn section disposed away from the screen end and between the side sections . The rear end return section is constructed in such a way that it concentrates most of its winding turns near the gun end. A ratio of less than 0.15 is maintained between a length of a region of the rear end turn section that includes 50% of all winding turns in the rear end turn section, including the winding turn closest to the gun end , and the effective length of the vertical magnetic field. The result is that a vertical deflection center is shifted to one side of the coil's gun relative to a center of horizontal deflection. A relation between a first length that separates the centers of deviation and an effective length of the field of vertical deviation is greater than 0.09, so that it significantly reduces the network distortion.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 illustrates a cross-section of one embodiment of the diverting coil, in one aspect of the invention, mounted on a cathode ray tube; FIGURE 2 illustrates a more detailed side cross section of the coil of FIGURE 1; FIGURE 3 illustrates a side view of a vertical deflection coil that is included in the coil of FIGURE 1; FIGURE 4 illustrates a top view of the vertical deflection coil of FIGURE 1; FIGURE 5 illustrates a shunt that is included in the coil of FIGURE 1; FIGURE 6 illustrates the field distribution functions VQ (Z) and Hn (Z) of the coil of FIGURE 1; and FIGURE 7 illustrates the field distribution functions V2 (Z) and H2 (Z) of the coil of FIGURE 1.

DETAILED DESCRIPTION In FIGURE 1, a CRT 10 includes a screen or faceplate 11 on which repeating groups of triplets of red, green and blue phosphor are deposited. The CRT 10 is of the A89FDT type with a Super Flat Plate size of 35V or 89 centimeters along a diagonal. The maximum deviation angle is 108 °. The distance of the reference line of the deviation towards the interior of the screen in the center of the screen, called as the projection distance, is 366 millimeters. The faceplate 11 has an aspect ratio of 4: 3.

The outline of the inner surface of the faceplate 11 is defined by the following equation.

Zc = Al • X2 + A2 • X4 + A3 • Y2 + A4 • X2 • Y2 + A5 • X4 • Y2 + A6 • Y4 + A7 • X2 • Y4 + A8 • X6 • Y4 + A9 • Y6 where: Zc is the distance of a tangent in plane towards the center of the contour of the inner surface. X and Y represent distances from the center, in the directions of the major and minor axes, respectively. Al a A9 are coefficients that depend on the diagonal dimension of the faceplate. For a CRT tube faceplate 10 with a viewing screen having a diagonal dimension of 89 cm, the appropriate coefficients Al to A9 are shown in Table I. A CRT with the contour defined by these coefficients can benefit in the distortion characteristics of NS-turn, when inventive aspects described herein are used. The dimensions X and Y must be in millimeters to use the coefficients of the Table.

TABLE Al = 0.201580000 X 10"03 A2 = 0.281067084 X 10-09 A3 = 0.265056338 X 10" 03 A4 = -0.420000000 x 10-09 A5 = -0.356545690 X 10"14 A6 = 0.915000000 x 10-09 A7 = -0.880800000 X 10"14 A8 = 0.140253045 X 10-24 A9 = 0.295636862 X 10" 14 An electron gun assembly of FIGURE 1 is mounted on a neck portion 12 of the opposite front plate of the tube. The gun assembly 15 produces 3 horizontal line beams, R, G, and B. A support-support bias coil assembly, generally designated at 16, is mounted around the neck and flange portion of the tube by a suitable assembly of plastic coil or liner 19. Coil 16 also includes a widened ferrite core 17, a pair of chair-type vertical deflection coils 18V, modeling an inventive aspect, and a pair of horizontal deflection coils of support type 18H . Deflection coil 16 is of the self-convergence and comma-free type.

FIGURE 2 illustrates a cross-sectional side view of the coil 16, including the core 17. FIGURE 3 illustrates a side view, and FIGURE 4 a top view of the coil 16, when the core 17 is removed for the purpose of Show the 18V coil in more detail. Similar symbols and numbers in FIGURES 1-4 indicate similar items or functions. The plastic coil assembly 19 of FIGURE 2 serves to support the support-type horizontal deflection coils 18H and the support-type vertical deflection coils 18V, in an appropriate orientation relative to one another and relative to the other. enlarged ferrite core 17 surrounding both coils 18V and 18H. Each support coil 18V of FIGURE 3 is formed by winding turns 70 including all winding turns of the coil. The winding turns 70 having N70 = 126 winding turns, have a rear end turn section 14a adjacent to the light input end of the electron gun 15 of FIGURE 1 (gun side or end). Section 14a has Na = 120 winding conductors. The support coil 18V of FIGURE 3 also has a rear end return section 14c, which has Nc = 6 winding conductors. The support coil 18H has a rear end return section 14b. The sections 14a and 14b and 14c of FIGURES 2-4 are not inclined from the neck of the tube, and are herein referred to as flat rear end turns. With a support coil of this type, the core 17 can be formed as a single piece. A longitudinal axis or Z of the coil 16 or the CRT of FIGURE 1 is defined in a conventional manner. In each plane of the coil 16 defined by a corresponding coordinate Z, which is perpendicular to the Z axis, a corresponding Y axis is defined in parallel to a vertical axis or smaller of the screen 11. Similarly, a corresponding X axis is defined in parallel to a horizontal axis or greater of the screen 11. The coordinate X = Y = 0 in each plane of the coil 16 is located on the axis Z. The winding turns 70 of FIGURE 3 including all the winding turns of the 18V coil, form a pair of side sections 71 and a front end return section 72 of the corresponding support coil 18V. The winding turns 70 also form a rear end return section 14a extending from a winding turn 80, ie at an end closest to the side of the gun, to a winding turn 81. Advantageously, there is no gap Significantly, where a winding turn is present, in the winding turns of section 14a, that is, between winding turns 80 and 81 in section 14a. The majority (Na = 120) of the winding turns of the winding turns 70 form the extreme return section 14a. Whereas, a significantly smaller number of the winding 70 (Nc = 6) form the rear end return section 14c. A recess 90 in the windings separates section 14c from section 14a. The section 14c is furthermore disposed from the beam input end of the coil 16 than in the section 14a. According to an inventive aspect, those winding turns of the winding turns 70 forming the section 14c are used to reduce the internal trilemma. The front end return section 72 and the rear end return sections 14a and 14c are generally disposed in a direction perpendicular to the axis Z. The side sections 71 extend between the lightning inlet end and the lightning exit end of the coil 16. A substantial number (Na = 120) of winding turns 70 of the coil 18V forming the section 14a of FIGURE 2, are generally farther from the front plate 11 and closer to the gun assembly 15 of the FIGURE 1, that the winding turns forming the end return section 14b of the coils 18H of FIGURE 2. The effect on the deviation field of the winding window 75 of FIGURE 3, which are formed by the winding turns 70, is determined by a distance WW between sections 71.

Each branch of a pair of branches 22a and 22b of FIGURES 1 and 2, which has a trapezoidal shape, as shown in FIGURE 5, is arranged symmetrically with respect to the axis Y. The branch 22b of FIGURES 1 and 2 is arranged at 6 o'clock and the shunt 22a is disposed at 12 o'clock on the Y-axis, in a symmetrical shape with respect to the X-axis. The trapezoidal construction allows each of the shunts 22a and 22b of FIGURE 5 to occupy the same angular scale in each XY plane, where the derivation is located. Parameters such as angular scale, length and coordinates are selected on the Z axis of each of the leads 22a and 22b, to correct the external trilemma and the signal reversion between the external and internal trilemma. These parameters are also selected to correct parabolas of horizontal and vertical coma, which is the inversion of the comma signal between the axis and the corner, and to correct East-West turns. Advantageously, the simple or almost rectangular trapezoidal geometry of the leads 22a and 22b improves the manufacturing capacity and reduces the sensitivity of the derivation placement. Near a lightning input end of the coil 16 of FIGS. 1-3, a vertical deflection field, produced by the coils 18V, is preferably configured as a punch to correct the vertical coma error. To reduce the over-convergence at the 6 and 12-hour points, the vertical deflection field produced by the vertical deflection coil 18V is made with the barrel shape in an intermediate portion of the coil, between the inlet and outlet ends of the coil beam 16. The horizontal deviation coils 18H can be of a conventional construction, such as that used in a conventional ST coil. FIGURE 6 illustrates a solid line of a field distribution function HQ (Z) that provides the magnitude of the horizontal deviation field in the X-axis direction and a broken line as a VQ (Z) field distribution function that provides the magnitude of the vertical deflection field in the direction of the Y axis in coil 16 of FIGURE 1. The functions HQ (Z) and VQ (Z) are used in the theory of first order aberration. Similarly, FIGURE 7 illustrates the field distribution function H2 (Z) that provides the variation of the magnitude of the field of horizontal deviation in the direction of the X axis, and the field distribution function V2 (Z) that provides the variation in the field of vertical deviation in the Y direction. The functions HQ (Z) and VQ (Z) are used in the theory of third-order aberration. Similar symbols in FIGURES 1-7 indicate similar items or functions. The resistance or intensity of the magnetic field produced by the deflection coil 18H of FIGURE 1, can be measured with a suitable probe. Such a measurement can be made for a given coordinate Z = Zl for a coordinate Y = 0 and for a given coordinate X = XI. For the purpose of measuring, the XI coordinate varies in the direction of the X axis, the direction of horizontal deviation. The plane, in which X = XI varies, is separated from the lower edges of the upper support coil 18H of FIGURE 2, from those of the inner support coil 18H. The results of measuring the resistance of the magnetic field as a function of the X coordinate, for a constant coordinate Z = Zl and for a coordinate Y = 0, can be used to compute, in a well-known way, functions or distribution coefficients of field HQ (Zl), H2 (Z1), H4 (Zl) and other higher coefficients of an energy series H (X) = H0 (Z1) + H2 (Z1) X2 + H4 (Z1) X4. The term H (X) represents the resistance of the magnetic field as a function of the X coordinate in the coordinates Z = Z1, Y = 0. Then, a graph is plotted representing the variation of each of the coefficients HQ (Z), H2 (Z), H¿ (Z) and other higher order coefficients, as a function of the Z coordinate. In an analogous way, the coefficients VQ (Z), V2 (Z), V4 (Z) and other coefficients of higher order, can be evaluated as a function of the Z coordinate with respect to the vertical deflection coil 18V. To obtain the functions shown in FIGURES 6 and 7, each of the X and Y coordinates are measured in millimeters. A center of vertical deflection 50 is defined as the coordinate Z = Z (c) of FIGURE 6 of a vertical line that divides the area bounded by the function curve VQ (Z) into two parts of equal areas, one towards its side right and the other to his left side. The center of vertical deviation Z (c) is equal to JVQ (Z) «Z« dz JVo (Z) «dz A horizontal deviation center coordinate 51 is defined in a similar way. An effective length \ of the vertical deflection field is defined as a vertical deviation field of constant magnitude ranging from Z = Z (0) to Z = Z (0) + Ai which causes approximately the same curvature of image field as the real field VQ (Z). The vertical deflection field is assumed to be centered around Z = Z (c) = Z (0) +. 2 The length A. equals A vertical deviation peak coordinate 52 is defined as the Z coordinate, in which a VPEAK peak of the VQ (Z) function occurs. Similarly, a horizontal deviation peak coordinate 53 is defined as the Z coordinate, in which an HPEAK peak of the HQ (Z) function occurs. According to an inventive aspect, extending most of the winding turns 70, which form the extreme return section 14a of FIGURE 2, very close to the gun assembly 15 of FIGURE 1, that the extreme return section 14b of FIGURE 2, the vertical deflection center coordinate 50 of FIGURE 6 is significantly changed toward the gun assembly 15 of FIGURE 1, with respect to the horizontal deflection center coordinate 51 of FIGURE 6. FIGURE 6 6, a difference of DIFF between the centers of deviation is 14 millimeters. The effective length A. of the vertical deflection field is 107.1 mm. A relationship between the difference DIFF and the effective length? of the vertical deflection field of coil 16 is equal to 14 / 107.1 = .13. When such a ratio of 0.13 is employed, the reduction in the distortion of NS-spin obtained is so effective that the NS-spin magnets are no longer required to eliminate the distortion NS-turn on the flat front plate 11 of the CRT 10 of the FIGURE 1 having an aspect ratio of, for example, 4: 3 and a size of 89 cm or 35V.

The displacement of the vertical deflection center coordinate 30 very close to the side of the gun or input end of the beam results in a ratio between the difference DIFF and the effective length X of the vertical deflection field of the coil 16, which is greater than 0.09. Such arrangements significantly reduce the distortion of NS-spin, when such ratio is less than 0.09, the distortion reduction of NS-spin may not be significant. When such a ratio is greater than 0.11, the NS-turn magnets are no longer required to eliminate the distortion of NS-turn of a CRT faceplate, not shown, which has an aspect ratio which, for example, is 16 : 9 and a size equal to 34V. According to another inventive aspect, the aforementioned significant magnitude of the difference in DIFF of FIGURE 6 between the central vertical deflection coordinate 50 and the central horizontal deflection coordinate 51 is produced without significantly lengthening the vertical deflection coil 18V of the FIGURE 1. As shown in FIGURE 6, the function curve VQ (Z) has a shape that is similar to that of the HQ (Z) function, except for being shifted to the input end of the beam. The displacement of the vertical deflection center 50 towards the gun assembly 15 of FIGURE 1 is obtained by shifting the vertical coordinate of vertical deflection 52 of FIGURE 6 relative to the horizontal coordinate of deviation 53 by a length, DIFF2 = 13.4 mm , which is approximately equal to the difference of DIFF. The relation between the difference DIFF2 between the coordinates 52 and 53 and the effective length X, of the field of vertical deviation, is equal to 0.125. By maintaining such a ratio greater than at least 0.06, a total length L of the coil 18V of the coil 16 of FIGURE 3, in the direction of the Z axis, remains small. The length L is measured between a winding turn 82, which is very close to the screen end, in the front end return section 72, and the winding turn 80 that is closest to the gun side in section 14a. Such a ratio that is greater than 0.06 is maintained by forming the extreme return section 14a of most of the rear portions (95% in this illustration) of the winding turns 70. Advantageously, by forming the section 14c of less than 10% (5% in this illustration) of the back portions of the winding turn 70, the internal trilemma can effectively be reduced. A portion having a length of 14a = 11mm is defined as the end turn section portion 14a extending from the winding turn 80 of the section 14a that is closest to the side of the coil gun 16 to a turn of winding 83. Between the winding turns 80 and 83, 50% of the winding turns of the winding turns of the end return sections 14a and 14c, combined, are arranged. The length l >;? 4a in this illustration, therefore covers 63 winding turns. A relation between the length L14a and the effective length? of the coil 18V of the coil 16 is equal to approximately 0.1. By maintaining such a ratio smaller than 0.15, the total length L of the coil 18V of the coil 16 is kept small, ie 79.6 mm in this illustration. The coil 18V of FIGURE 3 extends between the return winding portion 80 that is closest to the side of the gun and the turning winding portion 82 that is closer to the side of the shield. The 18V coil is shorter than 90 mm and, therefore, has the advantage that it facilitates the use of the CRT 10 with a short neck, thus facilitating the use of a small cabinet of smaller size for a television receiver . The leads 22a and 22b of FIGURES 1 and 2 improve the field distribution function V2 (Z) of FIGURE 7. By concentrating most of the winding turns of the vertical deflection coil 18V of FIGURE 3, in one small region, that is, generally closer to the input end of the beam than the winding turns of the horizontal deflection coil 18H to move the center of vertical deflection, a short coil can be used. As a result, North-South magnets can be eliminated for a large flat screen having an aspect ratio of, for example, 4: 3.

Claims (16)

1. A deflection coil mounted on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field including a pair of chair-shaped coils, each having a plurality of winding turns forming first and second side sections extending in a longitudinal direction of the coil, a front end turn section, disposed adjacent a screen end of the bobbin between the first and second side sections, and a rear end turn section disposed away from the screen end and between the side sections, such a turn section rear end being constructed in a way to concentrate most of its winding turns near the gun end to maintain a ratio of less than 0.15, between a length of a region of the rear end turn section that includes 50% of all the winding turns in the back end back section, including the turn of devan closer to the gun end, and the effective length of the vertical deflection field that results in a center of vertical deflection that is shifted to one side of the coil gun relative to a center of horizontal deflection, so that a The relationship between the first length separating the deviation centers and an effective length of the vertical deviation field is greater than 0.09, in order to significantly reduce the network distortion.

2. A deviation coil according to claim 1, characterized in that the displacement of the vertical deflection field reduces the North-South distortion, so that they do not employ North-South magnets.

3. A deflection coil according to claim 1, further characterized in that it comprises a pair of taps at opposite ends of a Y axis of the coil, each having a trapezoidal shape to improve the field distribution function V2 (Z).

4. A deflection coil according to claim 1, characterized in that the rear end return section includes a first portion near the gun end, and a second additional portion of the gun end and having a gap therebetween so that the Most of the winding turns are included in the first portion.

5. A deviation coil according to claim 4, characterized in that the winding turns of the second portion are used to reduce the internal trilemma.

6. A deflection coil for mounting on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field, having a center of vertical deflection, i.e., displaced to one side of the coil gun relative to a center of horizontal deflection, so that a ratio is greater than 0.06, between the distance separating the point on the longitudinal axis, where a peak magnitude of the field distribution function VQ (Z) occurs, and the point where a peak magnitude of a function of Field distribution HQ (Z) occurs, and an effective length of the vertical deflection field.

7. A deflection coil according to claim 6, characterized in that the displacement of the vertical deflection field reduces the North-South distortion and no North-South magnets are used.

8. A deflection coil for mounting on a neck of a cathode ray tube, with a screen having a flat front plate of 35V, or greater and with an aspect ratio of 4: 3, characterized in that it comprises: a core made of material magnetic; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field, the deflection fields having a vertical deflection center that is displaced to one side of the coil gun, relative to a center of horizontal deflection, so that a relationship between a length separating the centers of deflection and an effective length of the vertical deflection field is significantly in order to compensate for the trend of the flat face plate of 35V, or greater, and an aspect ratio of 4: 3, produces a distortion of the North-South network, without using North-South magnets.

9. A deflection coil for mounting on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field having a vertical deflection center, i.e., offset to one side of the coil gun relative to a center of horizontal deflection, so that a relation between a length, which separates the center of deflection and an effective length of the vertical deflection field is greater than 0.09, in order to significantly reduce the network distortion, the vertical deflection winding including a pair of coils in the shape of chair, each having a plurality of winding turns forming first and second side sections, extending in a longitudinal direction of the coil, a front end turn section extending from the first and second side sections near a screen end of the coil, and a rear end turn section disposed away from the screen end and between the sections The winding turns of the rear end return section are arranged near the gun end to maintain a length of the vertical deflection winding between the winding turns at opposite ends of the windings. Front and back extreme sections, shorter than 90 mm.

10. A deviation coil according to claim 9, characterized in that the displacement of the vertical deflection field reduces the North-South distortion, so that the North-South magnets are eliminated.

11. A deflection coil for mounting on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field having a vertical deflection center, which is shifted to one side of the coil gun relative to a center of horizontal deflection, so that a relationship between a length separating the centers of deviation and an effective length of the field of vertical deviation, is greater than 0.09, so that significantly reduces the network distortion, the vertical deflection winding comprising a pair of chair-shaped coils , each including a plurality of winding turns forming first and second side sections extending in a longitudinal direction of the spool, a front end turn section, disposed adjacent a screen end of the spool, between the first and second sections laterals, and a rear end turn section, disposed away from the screen end in a direction transverse to the longitudinal direction and between the side sections, the rear end turn section including a winding portion extending from a winding turn closest to the gun side and including a greater part of the winding turns of the rear end turn section, the winding portion being formed without any gap between the adjacent turns.

12. A deviation coil according to claim 11, characterized in that the displacement of the vertical deflection field reduces the North-South distortion, so that no North-South magnets are used.

13. A deflection coil mounted on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding arranged adjacent to the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field including a pair of chair-shaped reels, each having a plurality of winding turns forming first and second side sections, extending in a longitudinal direction of the bobbin, a front end turn section, disposed adjacent the screen end of the bobbin between the first and second side sections, and a rear end turn section disposed away from the screen end and between the side sections, the turn section rear end being constructed in such a way that it concentrates its winding turns near the gun end to move a center of vertical deflection towards a gun side of the coil relative to a center of horizontal deflection, so that a ratio between the first length that separates the centers of deviation and an effective length of the field of Vertical deviation is greater than 0.11, in order to significantly reduce network distortion.

14. A deviation coil according to claim 13, characterized in that the displacement of the vertical deflection field reduces the North-South distortion, so that no North-South magnets are used.

15. A deflection coil mounted on a neck of a cathode ray tube, characterized in that it comprises: a core made of magnetic material; a horizontal deflection winding disposed adjacent the core to produce a horizontal deflection field; and a vertical deflection winding disposed adjacent the core to produce a vertical deflection field including a pair of chair-shaped coils, each having a plurality of winding turns forming first and second side sections extending in a longitudinal direction of the coil, a front end turn section, disposed adjacent to one screen end of the bobbin between the first and second side sections and a rear end turn section disposed away from the screen end and between the side sections, the end turn section rear being constructed in such a way that it concentrates more than 90% of its winding turns near the gun end in a first portion of the rear end return section and less than 10% winding turns near the end of the screen in a second portion of the back end back section, so that a gap is formed along the je Z between the first and second portions.

16. A deviation coil according to claim 15, characterized in that the second portion provides an internal trilemma correction.