US3299379A

US3299379A - Deflection yoke

Info

Publication number: US3299379A
Application number: US231890A
Authority: US
Inventors: Charles E Torsch
Original assignee: MUTER CO
Current assignee: MUTER CO
Priority date: 1962-10-22
Filing date: 1962-10-22
Publication date: 1967-01-17
Anticipated expiration: 1984-01-17

Description

Jan. 17, 1967 c. E. TORSCH DEFLECTION YOKE 4 Sheets Sheet 1' Filed Oct.v 22, 1962 Fj- 5 PRIOR ART PRIOR ART INVENTOR. CHHRLes E TORSCH TTORNEVS #9 7,1 QETORSCH 9 9,299,379

DEFLECTION YOKE Filed Oct. 22, 1962 4 Sheets-Sheet 2 PRiOR ART INVENTOR. Cnmuas E. TORSCH gal/Le, 1 TUE Jain. 17, 1967 c. E. TORSCH DEFLECTION YOKE 4 Sheets-$heet 3 Filed Oct. 22. 1962 INVENTOR. CHHRLES E Tonscu qaae, Tana TToRNEvs Jan. 17, 1967 Filed Oct. 22, 1962 (LE. TORS'CH DEFLECTION YOKE 4 Sheets-Sheet INVENTOR. CHFIRLES E. Torkscn TTORNEYS United States Patent Filed Oct. 22, 1962, Ser. No. 231,890 24 Claims. (Cl. 335-213) The present invention relates to cathode ray tube deflection devices, and more particularly to novel toroidal electromagnetic deflection coils for use with cathode ray tubes.

During the operation of a cathode ray tube, the cathode ray beam is continually deflected so as to trace a pattern, known as a raster, on the tube screen. The deflection is caused by passing the beam through a time-varying magnetic field which emanates from deflection coils mounted about the tube neck.

In order to prevent deflection defocusing at the periphery of the raster, it is generally desirable that the field generated by the coils be uniform andmore intense at the beam entry end of the deflection yoke. is usually achieved by the use of deflection coils having a cosine distribution. However, where .the cosine distribution is used in wide angle deflection, a further ditficulty arises. Since, in wide angle deflection the radius of curvature of the screen is usually much greater than the average distance from the center of the yoke to the screen, the raster collapses at the edges so that it is shaped like a pincushion rather than being rectangularas desired.

This type of distortion is usually compensated for by the use of additional elements, known as anti-pin-cushion magnets, which are generally positioned on a non-magnetic frame attached to the deflection yoke near the flare of the picture tube. The magnets serve to pull or stretch the raster into the desired shape. Such an arrangement is not only costly, but in certain applications, such as in color three gun tube arrangements, the use of pin-cushion correction magnets is undesirable as it creates color blemishes.

Moreover, the prior art windings utilized large amounts of copper, required more space within the core for the copper, and simultaneously consumed more power.

Accordingly, it is an object of this invention to provide a novel type of deflection yoke winding and coil arrangement which in itself decreases the distortion of the raster at its periphery and thereby minimizes the need for pincushion magnets for correcting such image distortion.

A further object is to provide a novel type of winding to create a maximum flux density with favorable distribution in the yoke region with a minimum of copper for the winding and minimum power consumption.

Another object is to provide a novel winding which decreases the energy losses during the deflection process, and enables the internal diameter of the core structure to be narrowed, and which causes a decrease in the energy storage in the quadrature windings.

A further object is to develop a winding for use in color television yokes for decreasing pin-cushion distortion where is it undesirable to use anti-pin-cushion magnets due to their creation of color blemishes.

Briefly, the foregoing objects are accomplished by the use of a toroidal coil having windings thereon wound in a tilted manner. Referring now to the drawings:

FIG. 1 is a cross-sectional elevation of a yoke assembly taken at 45 to the axis of the horizontal and vertical flux;

FIG. 2 is a cross-sectional elevation view of a right conical core having a prior art radial winding thereon;

FIG. 3 is a front view of the assembly of FIG. 2;

FIG. 4 is a cross-sectional elevation view of a right conical core having a tilt-ed winding thereon;

FIG. 5 is a front view of the assembly of FIG. 4;

This condition 3,299,379 Patented Jan. 17, 1967 FIG. 6 is a cross-sectional elevation view of a combined conical and cylindrical core having a prior art radial winding thereon;

FIG. 7 shows the core of FIG. 6, but with a tilted winding thereon;

FIG. 8 schematically shows a method of constructing a tilted winding;

FIG. 9 is a cross-sectional elevation of a curved-flare core having a tilted winding thereon; v

FIG. 10 is a front view of the assembly of FIG. 9;

FIG 11 is a front view of a core segment having an inverse tilted winding thereon.

Deflection coils are either of saddle or toroidal shape. The toroidal coil is one which is wound axially of the core, circumscribing at least a portion of both the inside and outside thereof. The saddle type coil generally fits adjacent only one side of the core. A deflection yoke may use either saddle coils, toroidal coils, or a combination thereof. The present invention relates to yokes wherein at least one of the coils utilized is toroidal.

Referring again to the drawings, FIG. 1 shows a deflection yoke 20 mounted on the neck 21 of a cathode ray tube 22 adjacent the flared or bulb portion 23 of the tube. The yoke includes a pair of saddle-type horizontal deflection coils 26 positioned adjacent the neck of the tube, an insulator 27 placed about the horizontal coils, and a ferromagnetic core 28, having a toroidal coil pair 30 wound thereon, placed about the insulator intermediate the front 31 and rear 32 flanged portions thereof.

As shown in FIG. 1, the toroidal coil pair comprises a pair of oppositely disposed

coil halves

34 and 35. Each coil half is wound axially of the core in a toroidal fashion and extends peripherally only along a portion of the core,

as shown, for example, in FIG. 2.

In order to permit wide angle deflection, cores are generally flared, the cores being smaller in internal dimension at the rear, i.e. the beam entrance end 37 of the core and larger in internal dimension at the front, i.e. beam exit end 38 of the core. This flaring permits the front end 39 of each coil half to be positioned upon the bulb portion 23 of the tube thereby enhancing the wide angle deflection. The cores generally have a front face 24 and a rear face 25 which separate the outside surface 46 of the core from the inside surface 47.

The flared cores may be in the shape of a regular cone as shown in FIG. 4, a combined cylinder and cone as shown in FIG. 6 or curved such as the circular flare shown in FIG. 9. v

For purposes of clarity in explaining the present invention, the windings shown will be of much larger conductor diameter, and the turns :fewer than might be the case in actual practice wherein more turns of finer wire may be utilized. In the past as shown in FIGS. 2 and 3, it has been the practice to wind toroids by winding each turn along the shortest axial distance, pulling the turn taut, and continuing to the next turn. Such procedure conformed to the natural shape of the core and utilized the least length of copper. As a result of this prior art turn alignment, the portions of theturns adjacent the front 33, i.e. beam exit end, of the core were spread apart. This is shown by viewing the front end portions 41 of the coil half 34 of FIG. 2. This is also apparent from me front end view, FIG. 3, wherein it is shown that the turns of the prior art winding were radially disposed relative to the central axis so that the planar extensions 36 ofthe turns pass through the longitudinal central axis 480E the core. Where such radially disposed windings were used in conjunction with cosine winding it was necessary to include large anti-pin-cushion magnets. It has been found that by using a novel substantially non-radial type of winding, the need for pin-cushion magnets has been decreased,

the winding inductance increased for the same number of turns, and the current through these turns decreased with a consequent increase in efiiciency. The novel winding embodies the use of increased length of copper winding per turn, but permits the cross-section to be decreased and the number of turns to be decreased while still producing the same inductance and magnetic field as the radial winding. Thus, there is a saving in both initial cost and in the cost of operation.

A deflection coil winding is generally composed of a series of superimposed layers. For purposes of clarity andsimplicity in explaining the type of winding embodying the present invention, only one layer, the first layer, will be described. It is to be understood that subsequent layers could be wound in the same manner with the width of the layers following conventional practice of a constant or gradient width.

FIG. 4 shows a preferred form wherein the novel windings are applied to a right conical core 28A. A characteristic of the preferred form of novel winding is that at least one of the turns in each layer is radially disposed. In the preferred form, the radial turn or directrix illustrate-d by turn '43 .in FIG. 4, is located intermediate the

sideedges

44 and 45 of each layer.

FIG. is a front view of theright cone of FIG. 4 and illustrates the manner of tilt of the turns of FIG. 4. The side turns 49 on either side of the radial-1y disposed directrix 43 are inclined or tilted so that their front end portions 41A converge from the radial. As a result, as shown in FIG. 5, the extended planes 36A of the side turns 49 pass beyond the central core axis 48A rather than passing through the central core axis as is the case with radially disposed turns.

In the form shown, the directrix 43 is located in the middle of the layer and the side turns 49 are symmetrically disposed on either side of the directrix. It is to be understood that the directrix turn need not be in the exact center of the coil, but might be towards one edge sothat more turns are located on one side of the directrix than on-the other.

It is apparent frornFIGS. 4 and 5 that the front end portions 41A ofthe turns are positioned close together, rather than being spaced apart as was the case with the front end portions 41 of theradial windings of FIG. 3.

A further characteristic of the preferred form of the tilted winding is that the circumferential span 52A of the front end of the coil may be closer in length to the length of the circumferential span 51A of the rear end of the coil than the front peripheral span 52 is to the rear peripheral span '51 of the prior art radial winding of FIG. 3. In the maximum tilt, the front coil span 52A is substantially the same as the rear coil span 51A. Another way of stating this characteristic is that the ratio of the front coil span to the rear coil span of the tilted winding is nearer unity than the corresponding ratio of a radially disposed winding.

A still further characteristic of thepreferred form of the tilted winding is that azimuthal angle 0 which is measured at aperture 39A, between a longitudinal axis of the wire of the winding'49 at corresponding inner segments of turns which are wound successively in the general direction of coil winding advancement, has a lesser value than a corresponding azimuthal angle 0 which is measured at aperture 37A between said longitudinal axis of saidsame segments of said same turns. The azimuthal angles 0 and 0 are illustrated in FIG. 5.

The inner surface 38A at the beam exit end 39 of the core has a diameter D1 at aperture 39A and which defines a circular cross section area A1 at the aperture 39A in a plane perpendicular to the axis 48A. At the opposite end of the core, the inner surface 38A at the beam entry end 37 of the core, has a diameter D2 which is less than D1 and defines a circular cross section area A2 at the aperture 3 7A at the beam entry end 37 which is correspondingly'less'than the value'of the cross sectional area point of greatest curvature of the flare.

4. A1 at aperture 39A. Since the cross sectional area A1 is greater than cross sectional area A2, the perimetrical dimension or circumference, P1, of the inner surface 38A of the core will be greater at the beam exit end 39 than at the corresponding perimetrical dimension P2 measured at the beam entry end 37.

FIG. 6 illustrates the prior art radial type of winding on a combined cylinder and cone type of core.

FIG. 7 illustrates a tilted winding on such a core. The front view for FIG. 7 is the same as FIG. 5.

FIG. 8 illustrates one Way of making a tilted winding. A turn 61, shown in dotted lines may be placed approximately 150 radial degrees with reference to the vertical, as shown at angle A'of FIG. 8. Then, using the juncture 6 2 of the turn with the rear inside edge 65 of the core as a pivot point, the turn is pivoted while adding more wire thereto, so as to enlarge the turn, until the projected plane 36A of the turn passes beyond the central axis 43A. For example, the turn 61 may be rotated until the front end portion 41A of the turn 61 is rotated until it is only with reference to the vertical as shown by angle B in FIG. 8. The next wire 62 is then laid so that the turns are touching at the front end portions 41A and at the rear end portions 71A. As the winding progresses, one of the turns 43 is so positioned that its planar extension will pass through the central axis thereby forming a directrix. The turns on the other side of this directrix are then aligned symmetrically to the first laid turns with the projected planes of the turns extending beyond the central axls.

It is to be understood that in actual practice more turns than one may be radial. However, it is preferred that at least more than half of the turns of each layer should be tilted.

Where the core has a

front face

24, 24A and 248, as shown .in FIGS. 3, 5 and 10, respectively, the difference between the radial windings of'FIG. 3 and the tilted windings of FIGS. 5 and 10 is most apparent where the plane projection of turns method of comparison is utilized.

It is to be noted that where a curved core is machine wound, an additional characteristic of the novel tilted windingmay appear. As shown in FIGS. 9 and 10 the rear end portions 71A of the turns are spread apart slightly as compared to the rear end portions 71 of the prior art'radial winding of FIGS.- 2 and 3. However,

unlike the radial arrangement, the length of the front spanSZB of the coil approaches the length of the rear span 51B, and in some cases is substantially the same. A further characteristic of the machine wound curved core arrangement is that the turns converge intermediate the front and rear ends of the coil, thereby giving the coil'a slightly inwardly bowed appearance, Thus the narrowest span of the wires is no longer located adjacent the rear end of the core, but at a point inter-mediate the front and rear ends of the coil. The'point of narrowest span, the intermediate span 56, is generally located at or near the For example, where the'curved core has a circular flare as shown in FIG. 9, and a chord'58 is drawn intermediate the ends of the circular segment, then the smallest span will be located at or near the greatest sagittal distance 59 of the circular segment from the chord. As a result, inductance is increased adjacent an important point in the path of the electron beam through the magnetic field.

In a modification such as shown in FIG. 11, it may be mal fixed value of peak-to-peak current through the horizontal or vertical coils.

It is to be understood that the word core, as used in the claims, could be a magnetic core, a non-magnetic core, or an air core. A support may be used for winding the toroid, the turns may be glued, and the support either retained as part of the core, or removed. Where the core is air, the reference axis then becomes the longitudinal central axis of the coil which would be in the same position as the

core axis

48A and 48B illustrated. Where the core is present, then the longitudinal, or central coil axis is the same as the longitudinal central core axis.

It is to be noted from FIGS. 5, l0 and 11 that the the planar extensions of the tilted turns are non-coplanar with the central core axis, i.e. the planar extensions pass obliquely of the central core axis. I

Whereas it is preferred that at least a pairof coil halves angularly disposed about the core bejutilized with each coil half having the tilted configuration it may be possible to use a tilted winding on only one coil half.

I claim:

1. A deflection coil for use in cathode ray beam deflection yokes including a series of turns of wire toroidally disposed on the core withat least some of the turns being tilted so as to be non-radially aligned on the inner surface of the core relative to the longitudinal central axis of the coil.

2.- A deflection coil according to claim 1, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the coil, pass obliquely with respect to the longitudinal central axis of the coil.

3. A deflection coil according to claim 1, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the coil, intersect the longitudinal central axis of the coil.

4. A deflection coil according to claim 3, wherein said tilted turns include more than half of the turns of the coil.

5. A deflection coil according to claim 4, including at least one turn, intermediate the side edges of the coil, said one turn being radially disposed so that the imaginary planar extension of the turn, when viewed from the front end of the coil, passes through the longitudinal central axis of the coil.

6. A deflection coil according to claim 1, wherein the coil includes a front end and a rear end, and wherein the portions of the turns of wire adjacent the front end of the coil, when viewed from the front end of the coil, are substantially contiguous throughout substantially their entire length adjacent the said front end of the coil.

7. A deflection coil for use in cathode ray beam deflection yokes, said coil having a front end and a rear end, a series of turns of wire toroidally wound from the front end to the rear end, the coil 'being curved about a longitudinal central axis, the inner diameter of the front end being greater than the inner diameter of the rear end with the peripheral span of the front end being substantially the same as the peripheral span of the rear end.

8. A deflection yoke for use on a cathode ray beam deflection tube, including a hollow core, at least one coil, said coil including a series of turns of wire toroidally disposed axially of the core with at least some of the turns being tilted so as to be non-radially aligned on the inner surface of the core relative to the longitudinal central axis of the core.

9. A deflection yoke according to claim 8, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the core, pass obliquely with respect to the longitudinal central axis of the core.

10. A deflection yoke according to claim 9, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the coil, intersect beyond the longitudinal central axis of the core. 7

11. A deflection yoke according to claim 9, wherein said tilted turns include more than half of the turns of the coil.

12. A deflection yoke according to claim 8, wherein at least one of the tilted turns is so positioned that a plane passing through the central axis of the core and through the point of juncture of the rear end of the turn with the inside rear edge of the core is at a greater angle relative to the vertical than is a plane passing through the central axis of the core and through the point of juncture of the front end of the turn with the inside front edge of the core.

13. A deflection yoke according to claim 12, wherein at least half of the turns of the coil are so tilted.

14. A deflection yoke for use on a cathode ray beam deflection tube including a hollow core, at least one coil, said coil including a series of turns of wire wound axially of the core in a toroidal fashion with at least some of the turns being positioned so that the turns are wound axially of the core in paths which are longer than the shortest axial toroidal path for the turn.

15. A deflection yoke for use on cathode ray tubes including a hollow core, said core being flared in a curved fashion, a coil including a series of turns wound axially of the core in a toroidal fashion, the coil having a front peripheral span, a rear peripheral span and an intermediate peripheral span, the intermediate peripheral span being less in length than either the front peripheral span or the rear peripheral span.

16. A deflection coil according to claim 1, wherein the coil includes a front end, a middle portion and a rear end and wherein the width of the middle portion is less than the width of the front or rear ends of the coil.

17. A deflection coil according to claim 1, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the coil, intersect between a confronting inner face of the coil and the longitudinal central axis of the coil.

18. A deflection yoke according to claim 8, wherein the tilted turns are so positioned that the imaginary planar extensions thereof, when viewed from the front end of the coil, intersect between a confronting inner face of the core and the longitudinal central axis of the core.

19. A deflection yoke according to claim 18, wherein the tilted turns include more than half of the turns of the coil.

20. A deflection yoke for a cathode ray tube comprising: a core of ferromagnetic material having a length, an annular outer surface, an annular inner surface, said inner surface defining a cavity extending longitudially through said core from a first aperture at one extreme of said length to a second aperture at another extreme of said length, a horizontal deflection coil and a vertical deflection coil, one of said deflection coils having a plurality of wire turns wound about said core, each of said wire turns circumscribing said inner and outer surfaces and having a segment extending through said cavity, said one deflection coil having turns of wire which are wound successively in the general direction of coil winding advancement separated by a first azimuthal angle 0 at said first aperture and separated by a corresponding second azimuthal angle 6 at said second aperture, said first and second azimuthal angles having the relation length, a horizontal deflection coil and a vertical deflection coil, one of said deflection coils having a plurality of wire turns Wound about said core, each of said wire turns circumscribing said inner and outer surfaces and having a segment extending through said cavity, said one deflection coil having turns of wire which are wound successively in the general direction of coil winding advancement separated by a first azimuthal angle at said first aperture and separated 'by a corresponding second azimuthal angle 0 at said second aperture, said first and second cross sectional areas and said azimuthal angles having the relation where A and A are measured in square inches and 9 and 0 are measured in degrees.

22. A deflection yoke for a cathode ray tube comprising: a core of ferromagnetic material having a length, a longitudinal axis, an outer annular surface, an inner annular surface, said inner surface defining a cavity extending longitudinally through said core from a first aperture at one extreme of said length to a second aperture of another extreme of said length, said outer surface having linear perimetrical dimensions p and p measured in a plane perpendicular to said axis at points along said surface corresponding to said first and second apertures respectively, a horizontal deflection coil-and a vertical deflection coil, one of said deflection coils having a plurality of wire turns wound about said core each of said wire turns circumscribingsaid inner and outer surfaces and having a segment extending through said cavity, said one deflection coil having turns of wire separated which are woundsuccessively in the general direction of coil winding advancement by a first azimuthal angle 6 "at said first aperture and separated -by a corresponding second azimuthal angle 6 atsaid second aperture said first and second perimetrical dimensions and said first and second azimuthal angles having the relation where p; and p are measured in inches and 6 and 0 are measured in degrees.

23. A deflection yoke for a cathode ray tube comprising: a core of ferromagnetic material having a length, an outer circular surface, an inner circular surface said inner surface defining a cavity extending longitudinally through said core from a first aperture at one extreme of said length to a secondaperture at another extreme of said length, saidouter circular surface having diameters D and D at positions along the length of said core corresponding to said first and second apertures'respectively, a horizontal deflection coil and a vertical deflectioncoil, one of said deflection coils having a plurality of wire turns wound aboutsaid core, each of said wire turns comprised of segments circumscribing said inner and outer surfaces and 'having' a segment extending through said cavity said one deflection coil having corresponding segments of turns of wire which are wound successively in the general direction of coil windings advancement separated by a first azimuthal angle 6 at said first aperture and separated 'by a corresponding second azimuthal angle 9 at said second aperture, said diameters D and D and said first and second azimuthal angles having the relation References Cited by the Examiner UNITED STATES PATENTS 2,925,542 2/ 1960 Gethmann 3l7200 3,015,152 '1/1962 Marley 317-2001X 3,045,139 7/1962 Lu=tz 317-200 3,117,258 1/1964 Allen 313- 76 BERNARD A. GILHEANY, Primary Examiner. JOHN'F. BURNS, G. HARRIS, JR., Assistant Examiners.

Claims

1. A DEFLECTION COIL FOR USE IN CATHODE RAY BEAM DEFLECTION YOKES INCLUDING A SERIES OF TURNS OF WIRE TOROIDALLY DISPOSED ON THE CORE WITH AT LEAST SOME OF THE TURNS BEING TILTED SO AS TO BE NON-RADIALLY ALIGNED ON THE INNER SURFACE OF THE CORE RELATIVE TO THE LONGITUDINAL CENTRAL AXIS OF THE COIL.