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Publication numberUS3735193 A
Publication typeGrant
Publication dateMay 22, 1973
Filing dateDec 26, 1971
Priority dateDec 26, 1970
Also published asDE2164055A1, DE2164055B2
Publication numberUS 3735193 A, US 3735193A, US-A-3735193, US3735193 A, US3735193A
InventorsHiroshi Ikeuchi
Original AssigneeDenki Onkyo Co Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Deflection yoke
US 3735193 A
Abstract
A deflection yoke with four compensation coils which are provided at the core inside which a pair of horizontal deflection coils are mounted and act on the magnetic flux generated from said horizontal deflection coils to generate a compensation field which makes the horizontal deflection field pin cushion fields at both right and left areas of the beam scanning range and a barrel field at the middle area of the range.
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Description  (OCR text may contain errors)

United States Patent lkeuchi 1 May 22, 1973 1 DEFLECTION YOKE References Cited [75] Inventor: Hiroshi Ikeuchi, Yokohama, Japan UNITED STATES PATENTS Assigneel Denki ollkyo Tokyo, 3,668,580 6/1972 Barbin ..335 213 Japan 3,643,192 2/1972 Chiodi .335/213 [22] Filed: Dec. 26, 1971 App]. No.: 212,059

Foreign Application Priority Data 335/213; 315/27 GD, 27 XY Primary Examiner-George Harris Attorney -James E. Armstrong and Harold C. Wegner [57] ABSTRACT A deflection yoke with four compensation coils which are provided at the core inside which a pair of horizontal deflection coils are mounted and act on the magnetic flux generated from said horizontal deflection coils to generate a compensation field which makes the horizontal deflection field pin cushion fields at both right and left areas of the beam scanning range and a barrel field at the middle area of the range.

7 Claims, 11 Drawing Figures Patented May 22, 1973 3 Sheets-Sheet 1 Patented May 22, 1973 3 Sheets-Sheet 2 Patented May 22, 1973 7 3,735,193

5 Sheets-Sheet 5 FIGH PRIOR ART PRIOR ART DEFLECTION YOKE BACKGROUND OF THE INVENTION The present invention relates to the deflection yoke to be employed in the picture tube with the so-called delta gun type in which three electron guns are positioned respectively at the vertexes of an equilateral triangle.

The conventional television set employing this type of the picture tube is provided with a convergence device to converge three electron beams into the same hole of a shadow mask.

However, various misconvergences which are presumed to result from the deflection field of the deflection yoke appear on the screen of the picture tube in spite of the convergence being performed as specified in actual reception of a color television.

Of these misconvergences, the misconvergence referred to as S-ing clearly appears on a 110 deflected wide angle color TV picture tube.

The S-ing convergence is such that, as shown in FIG. 8, electron beams R and G diverge 180 from each other on a line parallel with horizontal axis X in reference to electron beam B even though three electron beams B, R and G are completely converged on vertical axis Y and horizontal axis X which pass through center of screen of the picture tube. This misconvergence is referred to as the S-ing misconvergence because divergence appears in the form of letter S.

It is known that this S-ing phenomenon can be reduced by making the deflection field of the deflection yoke assume a pin cushion distribution at both side areas and a barrel distribution at the middle area of the electron beam scanning range in the emission of the electron beams at the screen side as shown in FIG. 9. Therefore, it is proposed in conventional picture tubes to partly cut away the horizontal deflection coil as shown in FIG. if horizontal deflection coil D of the deflection yoke is of the saddle type and as shown in FIG. 11 if the horizontal deflection coil is toroidally wound.

However, if this approach is employed, the deflection yoke is disadvantageous because the distribution of the winding of the deflection coil is complicated, mass production of the deflection yoke is difficult, the chipped portion is formed in parallel with the winding of the deflection coil and the field distribution obtained .due to the chipped portion is the same at any cross section of the deflection field whereby the field distribution cannot be adjusted.

The saddle type deflection .coil is usually employed as the horizontal deflection coil for a television. Since this type of coil is made up by forming a saddle shaped clearance in the dies for winding wire and filling the clearance with an electric wire, it is disadvantageous because it is difficult to form the chipped portion as shown.

The present invention provides a deflect-ion yoke free from the disadvantages described above.

SUMMARY The deflection yoke according to the present invention is comprised of a pair of the toroidal type or saddle type vertical deflection coils, apair of the toroidal type or saddle type horizontal deflection coils, a core ,provided with said deflection coils, and four toroidal type or saddle type compensation coils provided at said core, wherein said compensation coils are overlapped on part of a pair of horizontal deflection coils and are arranged so as to produce magnetic fluxes which compensate the horizontal deflection magnetic field generated by the horizontal deflection coils, said compensation coils being respectively arranged symmetrically at both sides of each horizontal deflection coil in reference to the center line of the horizontal deflection coil and, at the same time, being positioned so that the deflection magnetic field of the horizontal deflection coils is compensated to the pin cushion fields at both side areas of the electron beam scanning range and to a barrel field at the middle area of the scanning range.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is illustrated in detail by the accompanying drawings whereon:

FIG. 1 is a plan view of a deflection yoke according to the present invention,

FIG. 2 is a magnified cross sectional front view along line IIII in FIG. 1,

FIG. 3 is an explanatory view of horizontal deflection magnetic field formed by this deflection yoke,

FIGS. 4 and 5 are plan views of the core illustrating the arrangement of compensation coils of this deflection yoke.

FIG. 6 is a circuit diagram of the compensation coil showing the other embodiment of this deflection yoke,

FIG. 7 is a diagram showing the waveform of the current to be supplied to the compensation coils shown in FIG. 6,

FIG. 8 is an explanatory view of the S-ing misconvergence by the conventional deflection yoke,

FIG. 9 is an explanatory view of the horizontal deflection magnetic field which compensates said S-ing misconvergence, and

FIGS. 10 and 11 are plan views illustrating conventional horizontal deflection coils.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, there is shown deflection yoke 1 comprised of a pair of toroidal-type vertical deflection coils 2, a pair of saddle-type'horizontal deflection coils 3, cylindrical core 4 around which said vertical deflection coils are wound, horn shaped bobbin 5 which is mounted on said core and is provided with horizontal deflection coils 3 at its inside surface, four compensation coils 6 which are wound around core 4, clamp belt 7 which clamps the core, flange 8 attached to the rear part of the core and a plurality of clamping segments 9 extended from the flange toward the rear side along the neck of the picture tube (not shown).

In this embodiment, compensation coils 6 are wound together with said vertical deflection coils 2 around core 4. Each compensation coil 6 is symmetrically wound in reference to center line L of each horizontal deflection coil 3 and is arranged so as to be overlapped with part of each horizontal deflection coil 3.

Compensation coils 6 are made to generate magnetic fluxes which offset partly the magnetic flux from horizontal deflection coils 3; accordingly, the compensation coils generate the magnetic fluxes in the direction opposite the magnetic flux generated from horizontal deflection coils 3.

Such oppositely oriented magnetic fluxes can be easily generated from the compensation coils by reversing the winding direction of each compensation coil or by selecting the direction of the current supplied to the compensation coils.

Referring to FIG. 3, there is shown a horizontal deflection magnetic field generated by horizontal deflection coils 3 and compensation coils 6.

If the magnetic fluxes from compensation coils 6 are not considered, the horizontal deflection magnetic field forms a conventional uniform magnetic field as shown with dotted lines. If the compensation magnetic fields of compensation coils 6 which are formed as shown with broken lines are applied to said magnetic field, part of the main deflection magnetic field from the horizontal deflection coils is offset by the compensation magnetic fields whereby the horizontal deflection magnetic field shows pin cushion distribution at both right and left side areas of the scanning range of the beams as shown with solid lines and a barrel distribution at the middle area of the scanning range. In other words, the horizontal deflection magnetic field which is desirable to compensate the S-ing misconvergence is formed in the magnetic fields generated by compensation coils 6.

The saddle type coil can be used as the compensation coils. In this case, four saddle type coils are arranged as in case of said embodiment.

If the compensation coils are wound in the reverse direction to the horizontal deflection coils, the horizontal deflection current can be supplied to compensation coils 6. In this case, the compensation coils can be connected in series and then can be connected in series to the horizontal deflection coils.

The ratio of the currents supplied to the horizontal deflection coils and the compensation coils can be predetermined; however, it is desirable to adjust the ratio of these currents by providing the current distributor in the circuit.

Thus, asymmetrical distortion due to error of the coil arrangement occurring in manufacturing the deflection yoke can be compensated.

If said current distributor can vary the ratio of the currents to be supplied to the compensation coils and the horizontal deflection coils during the scanning period, the distortion can be further rigorously compensated.

Compensation coils 6 need always not operate so as to offset the magnetic flux from horizontal deflection coils. If the horizontal deflection magnetic field shows a pin cushion distribution, the magnetic flux generated from compensation coils 6 can be superposed with the magnetic flux generated from the horizontal deflection coils.

In this case, the magnetic field generated by compensation coils 6 shows barrel distribution.

If the horizontal deflection magnetic field shows similarly the barrel distribution, the pin cushion distribution magnetic field may be formed by compensation coils 6.

However, as is well known, in case of the wide angle color picture tube, the integrated value of the horizontal deflection magnetic fields in planes intersecting at a right angle to the axial direction of the beam emission is made to cause a slight pin cushion type distribution to improve the convergence characteristic against divergence of three beams; accordingly, the horizontal deflection magnetic field may be actually a uniform magnetic field and a pin cushion distribution magnetic field.

If horizontal deflection coils 3 form a uniform magnetic field, compensation coils 6 are wound around core 4 as shown in FIG. 4.

Compensation coils 6 are positioned on outer side to be remote from each other at front side 31 of each horizontal deflection coil 3, that is, at the screen side of the picture tube, to offset the magnetic flux from the horizontal deflection coils and to form the deflection magnetic field as shown in FIG. 3, while it offsets the magnetic flux at the middle of the horizontal deflection field at rear side 32 of each horizontal deflection coil 3, that is, at the electron gun side of the picture tube and forms the pin cushion type magnetic field. On the other hand, if horizontal deflection coils 3 generate a pin cushion type magnetic field, compensation coils 6 are around core 4 so that they near each other at front side 31 of each horizontal deflection coil and are remote each other at rear side 32 as shown in FIG. 5.

In this embodiment compensation coils 6 are designed to generate magnetic fluxes in the same direction as horizontal deflection coils 3. Accordingly, the magnetic field formed by the horizontal deflection coils tend to show the barrel distribution at the front middle and the pin cushion distribution at the rear side area.

In this embodiment, the deflection yoke is advantageous because the aforementioned integration value of the horizontal deflection magnetic fields of deflection yoke 1 shows the pin cushion distribution, whereas it forms the deflection magnetic field at the screen side as shown in FIG. 9.

The deflection yoke according to the present invention is advantageous because the horizontal deflection magnetic field is compensated by compensation coils, the production of the deflection yokes is easy and the distribution of horizontal deflection magnetic field can be freely compensated.

Because said compensation coils cause the magnetic fields to act on the deflection magnetic field, they can compensate deflection distortion, which is different from the S-ing misconvergence, together with the S-ing misconvergence.

Compensation coils 6 shown in FIG. 6 are designed to compensate the S-ing misconvergence and, at the same time, to compensate the divergence position of three electron beams B, G and R. The following describes the divergence positions of three electron beams. As is shown from contemporary research, it is desirable for convergence without deterioration of the purity to diverge three electron beams so that the electron beams are respectively positioned at the vertexes of an equilateral triangle at any position on the screen of the picture tube. However, in case of the wide angle deflection picture tube, it is inevitable that the spot positions of three electron beams correspond to the vertexes of a scalene triangle at the positions near the top, bottom, right side and left side areas of the screen, due to the curvature of the screen. Accordingly, the deflection yoke is disadvantageous because the purity deteriorates due to convergence.

Four compensation coils 6 shown in FIG. 6 are divided into a pair of groups 6' containing two coils which are series connected and each group is parallel connected to power supply 10. These four compensation coils 6 are series connected to another power supply 11.

If power supply 10 is the deflection current source and the compensation current which has large amplitude at the initial stage and the final stage of vertical deflection period IV as shown in FIG. 7 and the same phase as the horizontal deflection current is supplied from other power supply 11, compensation coils 6 generate field f shown with dotted lines and fields f shown with broken lines. As described above, field, f, shown with dotted lines is effective to compensate the S-ing misconvergence, and fields f shown with broken lines acts to shift electron beams G and R in the horizontal deflection magnetic field.

Accordingly, with fields f the positions of two electron beams G and R can be shifted in reference to beam B which is positioned in the vertical direction and thus the positions of three electron beams can be adjusted with the compensation current from power supply 11 so that the spots of three electron beams are positioned respectively at vertexes of an equilateral triangle on the screen of the picture tube.

For such adjustment, however, the positions of three electron beams should be pre-adjusted so that the spots of three electron beams are respectively positioned at the vertexes of an equilateral triangle at a certain area on the screen and at the vertexes of an isosceles triangle at the other area on the screen. In addition, this preadjustment can be easily done.

Either of said power supplies l0 and 11 may be the horizontal deflection current source and the rest of power supplies may be selected according to the purpose of compensation of distortions except for the S-ing misconvergence.

What we claim is:

l. A deflection yoke comprised of a. a pair of vertical deflection coils,

b. a pair of horizontal deflection coils,

c. a core on which said deflection coils are mounted and d. four compensation coils which are arranged symmetrically in reference to the center line of each horizontal deflection coil, wherein said compensation coils are overlapped on part of said horizontal deflection coils respectively and are arranged to generate magnetic fluxes which cause the main deflection magnetic field generated from said horizontal deflection coils to be adjusted to show pin cushion distribution at both right and left side areas of the beam scanning range and to show barrel distribution at the middle area of said range, said horizontal deflection coils adapted to generate a uniform main deflection magnetic field and said compensation coils adapted to generate compensation magnetic fluxes which flow in the direction opposite the magnetic flux of said main deflection magnetic field.

2. A deflection yoke according to claim 1 wherein a horizontal deflection source is connected to said compensation coils.

3. A deflection yoke according to claim 2 wherein a current distributor is provided to vary the ratio of the horizontal deflection current supplied to said compensation coils and said horizontal deflection coils.

4. A deflection yoke according to claim 3 wherein said compensation coils are connected in series and the serially connected compensation coils are further connected in series with said horizontal deflection coils.

5. A deflection yoke according to claim I wherein said compensation coils are remote from each other at the front side of each horizontal deflection coil and closer to each other at the rear side of each horizontal deflection coil and are near to each other at the rear side of each horizontal deflection coil. 6. A deflection yoke comprised of a. a pair of vertical deflection coils, b. a pair of horizontal deflection coils, c. a core on which said deflection coils are mounted and d. four compensation coils which are arranged symmetrically in reference to the center line of each horizontal deflection coil, wherein said compensation coils are overlapped on part of said horizontal deflection coils respectively and are arranged to generate magnetic fluxes which cause the main deflection magnetic field generated from said horizontal deflection coils to be adjusted to show pin cushion distribution at both right and left side areas of the beam scanning range and to show barrel distribution at the middle area of said range, said horizontal deflection coils being designed so that the main deflection magnetic field generated by said horizontal deflection coils presents pin cushion type distribution, said compensation coils being arranged so that the coils are near each other at the front side of each horizontal deflection coil and are remote from each other at the rear side of said horizontal deflection coil, said compensation coils being designed to generate magnetic fluxes which flow in the same direction as the magnetic flux of the horizontal deflection coils whereby the magnetic fields of said compensation coils is superposed on the main deflection magnetic field. 7. A deflection yoke comprised of a. a pair of vertical deflection coils b. a pair of horizontal deflection coils, c. a core on which said deflection coils are mounted and d. four compensation coils which are arranged symmetrically in reference to the center line of each horizontal deflection coil, wherein said compensation coils are overlapped on part of said horizontal deflection coils respectively and are arranged to generate magnetic fluxes which cause the main deflection magnetic field generated from said horizontal deflection coils to be adjusted to show pin cushion distribution at both right and left side areas of the beam scanning range and to show barrel distribution at the middle area of said range, said four compensation coils being series connected in' a pair of groups respectively containing two coils, said coil groups being parallel connected to one power supply, said four compensation coils being series connected to another power supply, one of said two power supplies being adapted to cause said compensation coils to generate magnetic fields which make the main deflection magnetic field to show pin cushion distribution at both right and left side areas of the beam scanning range and barrel distribution at the middle area of said range and the other power supply being adapted to cause said compensation coils to generate magnetic fields which shift two of three electron beams except for a beam in the vertical direction in the horizontal deflection magnetic field.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3643192 *Jun 3, 1970Feb 15, 1972Rca CorpToroidal electromagnetic deflection yoke
US3668580 *Dec 7, 1970Jun 6, 1972Rca CorpToroidal deflection yoke having asymmetrical windings
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3849749 *Feb 12, 1973Nov 19, 1974Matsushita Electric Ind Co LtdDeflection coils producing pincushion and barrel deflection fields
US3911321 *Aug 27, 1973Oct 7, 1975IbmError compensating deflection coils in a conducting magnetic tube
US4039989 *Jan 11, 1977Aug 2, 1977U.S. Philips CorporationDeflection system for a color television display tube
US4096462 *Apr 7, 1977Jun 20, 1978Hitachi, Ltd.Deflection yoke device for use in color television receiver sets
US4228413 *Dec 11, 1978Oct 14, 1980Rca CorporationSaddle-toroid deflection winding for low loss and/or reduced conductor length
US4329671 *Apr 13, 1981May 11, 1982Rca CorporationAlignment-insensitive self-converging in-line color display
US4420734 *Mar 10, 1982Dec 13, 1983Hitachi, Ltd.Deflecting yoke for use in picture tube of projection color television receiver set
US4464643 *Mar 14, 1983Aug 7, 1984U.S. Philips CorporationDevice for displaying television pictures and deflection unit therefor
US4556857 *Oct 1, 1984Dec 3, 1985General Electric CompanyDeflection yoke for small gun-base CRT
US4737692 *Oct 25, 1985Apr 12, 1988Hitachi, Ltd.Pincushion distortion correction device
US4820958 *May 21, 1986Apr 11, 1989Kabushiki Kaisha ToshibaColor cathode ray tube device
US4851737 *Mar 5, 1987Jul 25, 1989Nokida Data Systems ABApparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment
US4899082 *May 13, 1988Feb 6, 1990Digital Equipment CorporationApparatus for compensating for image rotation in a CRT display
US4922153 *Sep 7, 1988May 1, 1990U.S. Philips CorporationMethod of, and device for, reducing magnetic stray fields
US5021712 *Nov 29, 1989Jun 4, 1991Digital Equipment CorporationApparatus for compensating for image rotation in a CRT display
US5561333 *Sep 14, 1994Oct 1, 1996Mti, Inc.Method and apparatus for reducing the intensity of magnetic field emissions from video display units
US5594615 *Dec 14, 1995Jan 14, 1997Mti, Inc.Method and apparatus for reducing the intensity of magenetic field emissions from display device
US7227318 *Feb 14, 2005Jun 5, 2007Matsushita Toshiba Picture Display Co., Ltd.Deflection device for projection tube and projection tube apparatus
EP0245711A2 *Apr 29, 1987Nov 19, 1987Mitsubishi Denki Kabushiki KaishaDeflecting yoke
WO2002091418A1 *Apr 18, 2002Nov 14, 2002Koninkl Philips Electronics NvDeflection system for cathode ray tubes
Classifications
U.S. Classification315/370, 335/213
International ClassificationH01J29/70, H01J29/76
Cooperative ClassificationH01J29/766, H01J2229/964, H01J29/705
European ClassificationH01J29/76F, H01J29/70B2D