US3094649A

US3094649A - Magnetic deflection yokes

Info

Publication number: US3094649A
Application number: US104359A
Authority: US
Inventors: Marley John
Original assignee: Hazeltine Research Inc
Current assignee: Hazeltine Research Inc
Priority date: 1955-08-23
Filing date: 1961-04-20
Publication date: 1963-06-18
Anticipated expiration: 1980-06-18

Description

June 18, 1963 J. MARLEY MAGNETIC DEFLECTION YoKEs l 3 Sheets-Sheet 2 Original Filed Aug. 23, 1955 l l l I l l l June 18, 1963 .LMARLEY 3,094,649

MAGNETIC DEFLECTION YoxEs Original Filed Aug. 23, 1955 3 Sheets-Sheet 3 United States Patent O 3,094,649 MAGNETIC DEFLECTIQN YOKES John Marley, Wayne, NJ., assigner to Hazeltine Research, Inc., Chicago, lill., a corporation of Illinois Original application Aug. 23, 1955, Ser. No. 530,029, now

Patent No. 3,015,152, dated Jan. 2, 1962. Divided and this application Apr. 20, 1961, Ser. No. 104,359

7 Claims. (Cl. 317-200) General The invention is directed to a method of manufacturing electron-beam deflection yokes utilized -to effect lateral motion of beams of electrons or similar electr-ical particles and is particularly directed to a method of manufacturing magnetic deflection yokes of this type. These yokes are particularly useful for dellecting the electron beams in cathode-ray Ytubes of the types conventionally employed in Oscilloscopes, target indicators, and most commonly used in television receivers. To a large degree the stringency of the requirements of deflection yokes determines the methods of manufacturing these yokes. Since television deflection yokes have the most exacting requirements, the process of manufacturing such a yoke will be described herein. However, it should be understood that the method of manufacturing deflection yokes in accordance with the present invention may be employed in other than the manufacture of television yokes.

This application is a division of application Serial No. 530,029, filed August 23, 1955, now Patent No. 3,015,152 and entitled Process of Manufacturing Magnetic Dedection Yokes.

The fundamental principles underlying television transmission and reception and the details of the apparatus employed are so well known it is deemed unnecessary for the purpose of the present invention to describe a complete television transmitter or receiver. It is well knovm in the art to employ cathode-ray tubes of various forms in conventional television receivers to reproduce televised images. To effect such reproduction, the cathode-ray tubes include means for emitting an electron beam which is intensity modulated -by video-frequency information. This beam is focused into an extremely narrow beam to provide the high definition required in reproducing the televised image and is deflected in two orthogonal directions to scan a rectangular raster on the image screen of the picture tube to provide a two-dimensional reproduced image. Focusing of the electron beam is ordinarily accomplished by providing nonuniform magnetic or elecftric fields of regular conguration in the space traversed by the electron beam between the cathode and the image screen. Deflection of the focused electron beam is effected by developing varying electric or magnetic fields in the space traversed by the beam between the point of focusing and the image screen. The present invention is directed to deflection yokes for developing such varying magnetic deflection fields.

As is well known, a beam of electrons passing through a magnetic field is deflected in a direction perpendicular to the instantaneous direction of motion of the electrons in the beam and to the lines of magnetic force cut by the beam. In order to effect continuous and uniform deflection of the beam in the horizontal and vertical directions, the intensities of the components of the magnetic field in these two directions are Varied, usually by employing separate coils of complex configurations with their axes mutually perpendicular in which the magnitudes of the currents in the separate coils are varied independently to provide mutually perpendicular elds.

Progressive advancements in the art of television have imposed rather stringent requirements upon deflection yokes. A deflection yoke should be an efficient power er' ICC converter, provide linear scanning, develop uniform de- -flection fields which do not cause defocusing, and be free from resonant ringing and from undesired interaction of the vertical and horizontal fields. In addition, the yoke should be inexpensive and there should be a high degree of consistency between the deflection fields developed by yokes of the same construction. With the advent of the wide-angle picture tubes having deflection angles approaching and having an extremely short neck portion, it has become difficult to satisfy these requirements.

It has been conventional to utilize saddle yokes, socalled because of the saddlelike configuration of each of the four coils which combine to form the yoke. Because of the complex configuration of these coils, saddle yokes require complex winding apparatus which individually winds each of thefour coils and which, in spite of its complexity, fails to maintaina uniform or any other desired spatial relationship to the turns in each coil or to wind coils which are consistently the same. After the winding process, .the coils usuallyrequire additional shaping by manual or mechanical means to assume the saddle form. The latter operationintroduces additional inconsistencies betweencoils and addi-tional irregularities within each coil. "Pour coils so formed are then nested with a winding of one coil in the cavity or window of another Eto provide the complete deflection yoke. The latter assembly operation introduces additional inconsistency characteristics between yokes of the same type. As a result of the above-mentioned factors, saddle yokes have field irregularities and a lack of consistency in fields developed by yokes of the same time. To compensate for the field irregularities and the variations between lields developed by. differentcoils of thesame type, only a small segment at 'the center of the field pattern developed by a yoke is used for deflection. The inner surfaces of the coils forming the yoke are spaced from the neck of the tube in order to minimize the effects of field irregularities which are strongest in the vicinity of the coil surfaces. Since only a relatively small portion of the total field developed by a yoke is employed, conventional saddley yokes tend to be expensive, large, and heavy, and they develop deflection fields which are less uniform than is desired and which fail to provide the degree of control of deflection of the beam required for best reproduction of the image. The present methods of physically windingl wire into complex coil forms -and then assembling the complex coils into a saddle yoke make the elimination of the above-described undesired factors extremely difficult. Therefore, it is desirable to practice new methods of manufacturing deflection yokes, thereby producing improved deflection yokes.

It is, therefore, an object of the present invention to provide deflection yokes which do not have the deficiencies and limitations of prior yokes.

It is an additional object of the present invention to provide deflection yokes utilizing printed wiring techniques.

n It is still another object of the present invention to provide deflection yokes which are easily and simply produced to have constant kmagnetic characteristics.

It isy a further object of the present invention to provide deflection yokes in which a plurality of windings lare preformed in fixed spatial relationship.

In accordance with the present invention, a cathoderay tube deflection-'yoke comprises a'yoke core including individual core Walis land a ldielectric sheet bearing a continuous loop-type conductor pattern encircling a wall of the yoke c ore so that the two coils formed by the two lsides of the loop-type conductorpattern fall in different 'radial quadrants of the core.

Referring to the drawings:

FIG. l is a perspective view of a deflection yoke in accordance with the present invention, mounted on the neck of a cathode-ray tube shown in fragmentary form;

FIG. 2 is a front elevation view of the yoke of FIG. l,

Vwith la portion cut away to show interior detail;

Description of Deflection Yoke In FIG. 1 a perspective view of a deflection yoke 10 manufactured in accordance with the present invention is shown, mounted on the neck of .a cathode-ray tube 11 which may be, for example, the picture tube of a television receiver. The yoke V is circular in cross section and preferably tits closely around the neck of the tube 11 with one end of the yoke, more specifically the beam-exit end, extending over at least a small length of the flared portion of the tube 11. The yoke 10 includes four complete coils 12-15, inclusive, which are identical in shape and form, but which ldiffer in size and may differ in the size or number of conductors. Each of these coils surrounds 180 of the surface of a ring core 16. For example, as represented in FIG. 2, the coil 12 occupies the first 4and fourth quadrants, the coil 13 the second and third, the coil 14 the first and second, and the coil 15 the third and fourth quadrants of the circle formed by the core 16. As is lapparent from the drawing, the dimensions of the

coils

14 and 15 are such that they may be placed within the outer coils -12 and 13.

Each of the coils `12--15, inclusive, is supported on a dielectric sheet and, when in their assembled form as shown in FIG. l, each includes a pair of distinct, though interconnected, windings. Referring to FIGS. 1 and 2,

the coil 12, for example, has a pair of

distinct windings

12a and 12b. These windings are shown in FIG. 3 in more detail and in unfolded form. The two distinct windings result when the dielectric sheet 17 of FIG. 3 is rolled up around, for example, the end turns 12d, the winding 12a being formed by the rolled-up side 12a; while the winding 12b is formed by the rolled-up side 12b. It is apparent that these two -windings are interconnected by the end turns 12C and 12d.

The coils 12-15, inclusive, are so disposed with respect to each other around the neck of the tube as to develop mutually perpendicular magnetic axes to effect horizontal yand vertical deection of the beam in the tube. For example, assuming the coils 12 and `13 having windings 12a, I12b and 13a, 13b develop the vertical deection iield, then

windings

14a, 14b and 15a, 15b of

coils

14 and 15, respectively, are utilized to develop the horizontal deflection field. Each of the coil windings such as, for example, the winding 12a of coil 12 occupies approximately 60 of the circumference of the ring core 16, the

windings

12a, 12b and 13a, 13b individually overlapping portions of the windings I14a, 14b and 15a, 15b.

-Referring now to FIG. 3, each of the coils .i12-15, inclusive, as represented by coil 11 in FIG. 3, is supported on a sheet of dielectric material 17 and has rectangularly disposed at ends corresponding to the ends 12e and 12d as well as at sides corresponding to the

sides

12a and 12b. By flat is meant that the ends and sides of the coil lay iiat against the surface of the dielectric sheet 17. The sides of these coils, as represented by the sides 12a tand 12b in FIG. 3, have alternate beam-deflection sections 18 and current-return sections 19, connected by alternate aring and converging sections 20. For the form of coil construction shown in FIG. 3, the beam-deflection sections 18 are relatively narrow in the vertical dimension of the drawing, while the current-return sections 19 are relatively wide sections. This configuration is desirable so that the conductors of the flaring and converging sections 20, which form the end turns of the assembled struc- 4 ture, will fan out radially from the cathode-ray tube axis. It will be noted that the coil 12, when viewed in its unfolded form as shown in FIG. 3, is a continuous coil winding having a plurality of elongated rectangular-like turns which progress in a spiral-like manner towards the center region of the unfolded coil winding.

The conductors in each of the coils 12-15, inclusive, are formed by employing printed circuit techniques and are, for example, approximately 15 mils wide, 1.5 mils thick, and are separated from each other by approximately 15 mils. For simplicity of representation, in FIGS. 1 and 3 only a few conductors have been shown representing each `of the windings and the relative conductor sizes and spacings are not to scale. In practice, the density of the conductors, as well as the total number and size of the conductors, is controlled by the field strength desired. The pattern of the spacings of the conductors is determined .by the field pattern desired. For example, if a cosine eld pattern is needed to correct lfor such problems as pin-cushion or barrel distortion, then the windings are spaced or have distributed -density according to a cosine pattern.

The

side windings

12a and 12b, specifically the narrow sections 18 of these windings, provide the deflection energy for dellecting the cathode-ray tube beam, the wide, flaring and converging sections 19' and 20 Serving lonly to complete Ithe current path for the narrow sections. The center portion of the dielectric sheet may be omitted when the sheet is manufactured or may be cut out before or after the conductors have been formed on the sheet, thus leaving an open region 21 as shown in FIG. 3. In addition, slits, represented by the dashed lines in FIG. 3, are made between conductors in Vthe converging and flaring sections 20 to facilitate the winding of the sheet of conductors into a tubular form and the bending of the tube to fit over an `arc of the core 16. The lengths of the different sections in the coil sides are made progressively longer. That is, for example, the length of the second narrow section, counting yfrom the end 12d in a coil side such as side 12b, is longer than that of the first, and the third is longer than that of the second. The difference in length is determined by the thickness of the dielectric sheet, resulting in the successive circumferences or" the layers of the sheet when wound in tubular form becoming progressively larger.

A group of coils of the type represented by FIG. 3, after each has been rolled into a attened or rectangular tube about an axis parallel to the coil ends, for example, the ends 12C and 12d, are combined on the ring core 16 in the order represented in FIG. 1 to provide a complete deflection yoke. The core 16 may be, for example, of ferromagnetic material such as ferrite in order to provide a low reluctance return path for the magnetic flux developed by the coils and preferably is separable into quadrant pieces to facilitate the threading of the tubular coil structure onto the core in the desired order. The coils enclose the walls of the core, land the

coil sides

12a and 12b are parallel to the axis of the core. The beamdeflection or narrow sections 18 of the coil sides are superposed on the inner and the wide or current-return sections 19 superposed on the outer walls of the core 16. The coils are secured about the circumference of the core, after being adjusted in proper spatial relationship, by means of an adhesive on the core or by adhesive tape.

Method of Manufacturing Deflection Yoke The process of manufacturing a deflection yoke in accordance with the present invention commences with the preparation of an elongated rectangular-like coil winding, such as represented by FIG. 3, on each of a plurality of dielectric sheets. These sheets may be, for example, of some thin flexible plastic material, such as vinylite or a phenolic Fiberglas, and are either of a rectangular shape, including a center portion, or of similar shape, without the center portion. By means of conventional printed wiring processes a coil, for example coil 12 having

sides

12a and 12b and ends 12C and 12d and in which the sides. have alternate wide and narrow sections connected by alternate flaring and converging sections, is formed on each dielectric sheet. The printing process may, for example, comprise etching the conductors for each coil out of a thin copper plating coating the dielectric sheet, conventionally known as copper-clad. Alternatively, each coil may be impressed or sprayed onto the dielectric sheet to form copper, silver, or other conductive material. `Conventional printing or spraying processes can be employed. In forming the coils on. the dielectric sheet, each setV of four sections of a coil', for example the sections including. a wide, a narrow, a flaring, and a converging portion, is' made progressively longer to compensate for the additional circumference in each coil layer of four. sections. The lengths of the first four sections are determined by the length of the rst narrowy section and the thickness of the core. The length of the rst narrow section is determined by the deflection force desiredl and is limited by the. available length on the neck of the picture tube. Each coil is one continuous loop of conductors having terminals as indicated by the reference letters` T and T in FIG. 3. If desired, slits, as represented by the dashed lines, are cut or otherwise formed between the conductors in the flaring and converging sections to facilitate the forming of the dielectric sheet and the coil thereon into a flattened tube. If slits are provided, they should be slightly longer than the flaring and converging sections, but not so long as to disturbthe fixed spacing of at least the conductors in each narrow section.

Each sheet so prepared is rolled on a mandrel or by other means about .an axis parallel to the ends of the coil so that the coil sides are normal to this axis and form rings at the ends of the tube formed by the sheet. The

folding process is such that corresponding sections in eachv side, as well as the two end sections, are superposed. In other words, each layer in the flattened tube includes a set of the four coil sections with, for example, all of the beam-deflectiony or narrow sections 18 in the different layers superposed. For

coils

14 and 15, the interior dimensions of the tubes formed by the coils are approximately equal to the outside dimensions of the coil 16.

Coils

12 and 13 form tubes in which the internal dimensions are approximately equal to the outside dimensions of the

coils

14 and 15. 'In view of the difference in size ofthe tubes formed by the-different coils, coils 12 and 13 have longer sides andv each ofthe-sections in each side is correspondingly longer than the sides and the sections of

coils

14 and 15.

As previously mentioned, the core 16 is preferably broken into four quadrant pieces having irregular rather than machined mating edges. The irregular mating edges of adjacent pieces provide greater contact surfaces, thereby decreasing interface effects. One quadrant of the core 16 is threaded through the internal openings in the tubes formed by the

coils

14 and 12 in the order mentioned to provide the upper right-hand or first quadrant of the yoke of FIGS, l and 2. In a similar manner, the second quadrant of the core 16 is threaded through the tubes formed by

coils

14 and 13, the third quadrant through the tubes formed by

coils

15 and 13, and the fourth quadrant through the tubes formed by coils 1S and 12 in that order. The quadrant sections of the core are then fitted together to form the cylindrical or ring core 16 and are secured in that position by use of adhesive or by tape which secures the different coils in proper position. A dust cover (not shown) and a magnetic shield (not shown) may be added to enclose and protect the coils. In addition, considering PIG. 3, not all of the end turns at ends 12e .and 12d need cross over at the very ends. Some may cross over at intermediate points to delete the total number of turns per layer of coil as the layers build up. This saves cost and space with little loss in magnetic iiux.

Modijed Coil Structure of FIG. 4

Referring now to FIG. 4 of the drawings, there is shown.` an alternative formof conductor pattern thatmay be printed on the dielectric .sheet 11 and which should be mentioned iny detail because `of the reduced. energy losses` associated with` a deflectionyoke which utilizes suchl a conductor pattern. The conductor pattern, as shown on the unfolded dielectric. sheet 1'7 of FIG. 4, is similar to the pattern on the unfolded dielectric sheet shownin FIG. 3,v except that the current-return sections 19 on

opposite sides

12a and 12b of the conductor pattern` havev beenl positioned more closely to one another.

The conductor pattern on the dielectric sheet 1T of FIG. 4 is` rolled up in thev samev manner as previously describe-d, so asV to form` a flattened tubular structurey which may be placed on the ring coreV 16 of. the deflection yoke. It will be apparent that when this is done, the more closelyy spaced current-return sections 19 will lay on top of one another onY the outside of lthe core 16. Now, as. the current flow in the current-return sections =19 making up the side 12a is owing in a direction opposite to the current flowing4 in the sections. 19 making, up the side 12b, the magnetic fields produced by adjacent sections'on the two sides 12m and 12b of the conductor pattern will partially cancel one another. means that less-energy will be stored in the magnetic fields produced by the current-return sections and, hence, the energylosses due to eddy currents, etc., Will be reduced, thus resulting in a more efficient operation. of a deflection yoke utilizing such conductor patterns.

While the conductor configuration shown in FIG. 4 indicates one manner in which the current-return sections 19 of the coil 12 may be spaced more closely to one another, it Will be apparent to those skilled in the art that other configurations are possible for producing the desired magnetic field cancellation. Any conductor pattern whereink the current-return sections on opposite sides of the conductor pattern are brought into a closely adjacent relationship with one another will produce the desired results.

In deflection yokes of any of the foregoing types,.the conductors in each of the coils areA constrained asa result of being printed in `fixed position to have fixed and consistent spatial relationships with respect to each other. As a result, uniform coils or coils with conductors nonuniformly distributed in any desired pattern are consistently manufactured. The magnetic fields developed-by coils manufactured in the manner described herein are as exact and controlled in pattern as desired and are consistently duplicated. This results in a relatively inexpensive and light-weight deflection yoke which provides greatly improved deflection and has a minimum disturbing effect on the focusing of an electron beam.

Though relatively simple deflection yokes and their manufacture have been described and no extensive discussion of techniques for correcting for Well-known deciencies in 'yokes has been presented, it should be apparent to those skilled in the art that many of the practices which are conventionally employed to develop magnetic field patterns of suitable distribution to correct for field deficiencies may equally well be employed in the preparation `of a yoke such as described herein. In fact, the use of printed-wiring techniques facilitates the obtaining of many of these corrective effects `by simplifying the grading of conductor size and spacing of conductors in any desired manner to obtain field patterns which provide the corrective effects desired.

While there have been described what are, at present, considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover .all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A cathode-ray tube deflection yoke comprising: a yoke core including individual core walls and a dielectric sheet, bearing a continuous loop-type conductor pattern encircling a wall of the yoke core so that the two coils formed by the two sides of the loop-type conductor pattern fall in different radial quadrants of the core.

2. A cathode-ray tube deection yoke comprising: a yoke core including individual core walls and a dielectric sheet, having printed thereon a continuous loop-type conductor pattern, encircling a wall of the yoke core so that the two coils formed by the two sides of the looptype conductor pattern fall in diierent radial quadrants of the core.

3. A cathode-ray tube deflection yoke comprising: a yoke core including individual core Walls and a dielectric sheet, bearing a continuous loop-type conductor pattern having two elongated sides joined by two short sides, encircling a Wall of the yoke core so that the two coils formed by the two elongated sides of the loop-type conductor pattern fall in diierent radial quadrants of the core with the short sides positioned on top of one another on the outer side of the core so that their magnetic fields tend to cancel each other.

4. A cathode-ray tube deflection yoke comprising: a yoke core including individual core walls Iand a dielectric sheet, fbearing a continuous loop-type conductor pattern having two elongated sides joined by two short sides with the elongated sides having alternate wide and narrow sections connected by alternate aring land converging sections, the dielectric sheet encircling a Wall of the yoke core so that for each elongated side of the loop-type con-` ductor pattern the narrow sections are superimposed on top of one another on the inner side of the core, the wide sections are superimposed on top of one another on the outer side of the core, the flaring sections are superimposed on top of one another on one end of the core, and the converging sections are superimposed on top of one another on the other end of the core and so that the two deflection coils thus formed fall in different radial quadrants of the core with the conductors in the aring and converging sections directed radially of the core to minimize the effects of their magnetic elds.

5. A cathode-ray tube deection yoke comprising: a yoke core including individual core walls and a dielectric sheet, bearing a continuous loop-type conductor pattern having two elongated sides joined by two short sides with the elongated sides having alternate sections which are spaced nearer to and farther from one another and are connected by intervening oblique sections, the dielectric sheet encircling a wall of the yoke core so that for each elongated side of the loop-type conductor pattern the farther-spaced sections are superimposed on top of one another on the inner side of the core, the nearerspaced sections are superimposed on top of one another on the outer `side of the core, and the oblique sections are superimposed on top of one another on the two ends of the core and so that the inner portions of the two deflection coils thus formed fall in diierent radial quadrants of the core with the nearer-spaced outer portions closely adjacent one another so that their magnetic fields tend to cancel each other.

6. A cathode-ray tube deflection yoke comprising: a yoke core including individual core walls and two sets of coils comprising a plurality of dielectric sheets, each bearing a continuous loop-type conductor pattern, wrapped around the yoke core so that the two coils formed by the two sides of each of the loop-type conductor patterns fall in `different radial quadrants of the core, one set of the coils encircling a wall of the core to produce a first deflection ield and the other set surrounding the core wall to produce a second deection eld at right angles to the rst field.

7. A cathode-ray tube deflection yoke comprising: a yoke core including individual core walls, a rst set of coils for producing a first deflection eld and comprising two dielectric sheets, each bearing a continuous loop-type conductor pattern, encircling a wall of the yoke core so that the two coils formed by the two sides of each of the loop-type conductor patterns fall in adjacent radial quadrants of the core with one pair on one half of the core and the other pair on the other half; and a second set of coils for producing a second deflection eld at References Cited in the file of this patent UNITED STATES PATENTS Over et a1. Dec. 24, 1957 Hanlet Apr. 8, 1958

Claims

1. A CATHODE-RAY TUBE DEFLECTION YOKE COMPRISING: A YOKE CORE INCLUDING INDIVIDUAL CORE WALLS AND A DIELECTRIC SHEET, BEARING A CONTINUOUS LOOP-TYPE CONDUCTOR PATTERN ENCIRCLING A WALL OF THE YOKE CORE SO THAT THE TWO COILS FORMED BY THE TWO SIDES OF THE LOOP-TYPE CONDUCTOR PATTERN FALL IN DIFFERENT RADIAL QUADRANTS OF THE CORE.