Patent Publication Number: US-3878490-A

Title: Direct-wound, precision deflection yoke with adhesive coated core

Description:
United States Patent 1 [111 3,878,490  
 Logan Apr. 15, 1975 [54] DIRECT-WOUND, PRECISION 3,566,321 2/1971 Brown 335/210 DEFLECTION YOKE WITH ADHESIVE 3,638,152 l/l972 Tsutsumi 335/213 3.710289 1/1973 Pax et al. 336/205 X COATED CORE [75] Inventor: James H. Logan, Baldwinsville, NY.  
 [73] Assignee: General Electric Company,  
 Syracuse, NY.  
 [22] Filed: Sept. 3, 1974 [21] Appl. No.: 502,689  
 [52] U.S. Cl. 335/210; 335/213; 336/205 [51] Int. Cl. H0lf 7/00 [58] Field of Search 336/205; 335/210, 213  
 [56] References Cited UNITED STATES PATENTS 3,111,609 11/1963 Webb 336/205 X 3,412,354 11/1968 Sattler 336/205 Primary E.\&#39;aminerG. Harris Attorney, Agent, or Firm-Marvin Snyder [57] ABSTRACT In direct-wound yokes, such as toroids, where individual wires are wound from end-cap to opposite end-cap along the core inner surface, the problem of layers of wire wound above and between adjacent wires forcing these wires out of place in a random manner is overcome by coating the inner surface of the core with an adhesive that increases friction and thus resists wire movement. The adhesive, applied in liquid form, remains tacky indefinitely, thus allowing turns to be removed and the parts reused if desired.  
 8 Claims, 3 Drawing Figures DIRECT-WOUND. PRECISION DEFLECTION YOKE WITI-I ADHESIVE COATED CORE This invention relates to magnetic yokesfor cathode ray tubes. and more particularly to a method and apparatus for holding individual turns. wound on a core. in a direct-wound yoke.  
  In direct-wound yokes such as toroidal yokes presently employed with cathode ray tubes of the color television type. individual wires are wound from endcap to opposite end-cap along the inner surface of the core or coil-form with only tension and friction holding them in place. Layers of wire wound above and between adjacent wires force the lower wires out of place in a random manner. thereby impairing the desired configuration of the magnetic field produced by the coil.  
  The present invention contemplates coating the inner surface of a core with an adhesive to increase friction and thereby resist sideward movement of wires. The adhesive material is applied in liquid form and remains tacky for an indefinite period of time. Tackiness of the adhesive permits turns to be removed and the yoke parts reused. Moreover. because the adhesive is essentially nonhardening. the coated cores or coil-forms can be stored for later use in production.  
  Accordingly. one object ofthe invention is to provide a method and apparatus for constructing a cathode ray tube magnetic deflection yoke of high precision.  
  Another object is to provide a method and apparatus for rapid fabrication of a cathode ray tube magnetic deflection yoke of the direct-wound type.  
  Another object is to provide a method and apparatus for positively maintaining coil turn segments in place on the core of a cathode ray tube magnetic deflection yoke without adversely affecting core integrity.  
  Briefly. in accordance with a preferred embodiment of the invention. a cathode ray tube magnetic deflection yoke of high precision comprises a magnetic core of flared configuration adapted to tit about a portion of such tube. a coating of pressure-sensitive adhesive on the inner surface of the core. and an innermost layer of coil turn segments wound atop the adhesive coating such that the-turn segments are restrained against sideward movement. A second layer of coil turn segments is wound over the innermost layer of coil turn segments. with at least a portion of each respective turn segment of the second layer being located above and between two adjacent turn segments. respectively. of the innermost layer of coil turns.  
  In accordance with another preferred embodiment of the invention. a cathode ray tube magnetic deflection yoke of high precision is fabricated by coating the inner surface of a yoke core with a pressure-sensitive adhesive. and thereafter winding an initial. innermost layer of coil turns directly on the adhesive coating. A second layer of turns may then be wound over the innermost layer of turns. with individual turn segments of the second layer&#39;being positioned between adjacent turn segments of the innermost layer. respectively.  
 I The features of the invention believed to be novel are set&#39;forth with particularity in the appended claims. The invention itself. however. both as to organization and method of operation. together with further objects and advantages thereof. may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:  
  FIG. I is an isometric view of a magnetic deflection yoke intended for use with the instant invention;  
  FIG. 2 is a sectional view along line A-A&#39; of FIG. 1 showing deflection coil wires undergoing external forces caused by wire tension. and a resolution of forces in the wires of the innermost coil; and  
  FIG. 3 is a sectional view along line A-A&#39; of FIG. I showing deflection coil wires when the inner surface of the yoke core is coated with a liquid. pressure-sensitive adhesive.  
 DESCRIPTION OF TYPICAL EMBODIMENTS In FIG. I. a cathode ray tube yoke 10 ofthc toroidal type is shown comprised of suitable magnetic material. such as a magnetically soft ferrite of the type described by E. C. Snellin&#39;g. l-&#34;crriuar jbr Linear .-lpplit&#39;uliun.v. l- Properlicx. [El-5E .S&#39;peclrum. January I972. pages 42-5 I formed generally in the shape of a cylinder having a flared end adapted to fit around the neck of a color television picture tube and extend over a portion ofthe neck and funnel regions thereof. A first insulative ring or end-cap I2 is attached to the front or flared end of core II as by a press fit or by use of an adhesive such as glue. and has formed therein a plurality of slots 14. A second insulative ring 13 is attached to the opposite end of core 11 in the same manner. and has formed therein a plurality of slots 15. Although only several slots 14 and 15 are shown. it is to be understood that slots I4 and 15 extend substantially around the entire circumference of end-caps l2 and 13. respectively.  
  Normally in deflection yoke I0. there are located two windings diametrically opposite each other. their centers situated on a vertical axis. to produce horizontal deflection of electron beams within the cathode ray tube. and two windings diametrically opposite each other. their centers situated on a horizontal axis. for producing vertical deflection of electron beams within the cathode ray tube. Other windings. such as quadripole triad correction or convergence correction windings. may be distributed around the core. For clarity of illustration. however. only a portion of the top and bottom horizontal windings are shown.  
  Turn segments 21. 22 and 23 of the bottom Horizontal winding are shown stretched over the inner surface of core ll. Turn segment 22. at the front end of core 11. fits within a slot 14 of end-cap 12. However. due to the flared shape of the core. segments 2! and 23 approach each other toward the rear of core 1 I such that turn segments 21 and 23 fit within adjacent ones of slots 15 with turn segment 22 situated directly above the space between turn segments 2] and 23. At a location intermediate the front and rear end-caps of yoke 10. the separation between turn segments 21 and 23 becomes less than the diameter of turn segment 22 so that segment 22 is required to climb atop turn segments 21 and 23. I  
  FIG. 2. which is a sectional view through turn segments 2!. 22 and 23 along line A-A&#39; in FIG. I. shows the geometrical relationship among turn segments 21. 22 and 23., along with a resolution of forces thereon due to tension in the turns and which act in a downward direction as illustrated by the downward-directed ar&#39; rows. The downward force of turn segment 22 acting on segments 21 and 23 tends to spread segments 21 and 23 apart. as indicated by the sideward-directed arrows. Thus. near the rear of the core (and over the entire length of the core in the case of narrow flare yokes.  
  -such as for tubes of about 70 and smaller deflection angles). there isa tendency for&#39;the coil turns to distort in shape.thereby adversely affecting the desiredconfigurationof the magnetic field producedby the coil.  
  to the inner surface of core 10. the core may still be easily handled, on its outside surface. Moreover. due to the, inward sag of the outer core surface resulting from the flared configuration of a wide deflection angle core. outer turn. segments 26.27 and 28 do not contact the outer core surface between end-caps 1. 2 and 13. so that little would be accomplished by applying adhesive to .the outercore surface. Additionally. turn transitions or crossovers&#39;gare primarily formed only. on the outer sur- --face of the core soas to minimize any adverse effect they may have on the magnetic field penetrating the cathode ray tube. and hence adhesive on the outersurface of the .core would be relativelyineffectual in bolding turn segments in place.  
  FIG. 3. which is a sectional view of yoke along line A-A&#34; in FlGpLshows howthe turn-segments are maintained in place by use of pressuresensitive adhesive 25. lnnermost turn segments 21 and 23are pressed into adhesive layer such that only a thin film that is a fraction of the wire radius in thickness separates them from the inner surface of core 1 1. example. ifthe wire diameter is 00221-0025 inchesftlie thickness of adhesive layer 25 is typically on the order ,of 0.005 inches. Thereafter. turn segment 2 2 is wound. about the core and.,where it contacts adhesive layer 25 it is prevented from sideward movement. Where. turn segment 22 rests atop turn segments 21 and 23. it cannot displace seg-&#39; ments 2] and 23 sideways due to presence .of adhesive layer 25 which prevents turn segments 21 and .23 from moving. Moreover turn segments 21 and 23 are not ..only retained in precise locations with respect to each other. btlt they arealso-retained at a precise position above the surface ofcore 11. As &#39;a result. turn segment 22 is likewise retained in a precisely determined location. Hence the invention lends itself to fabrication of high precision cathode ray tube deflectionyokes. C ore integrity is unaffected by the invention sincethere is no need to cause the turn segments of the yoke to penetrate into the material of the core or coilform in order to be retained positively in place.  
  The foregoing described a method and apparatus for rapidly fabricating a direct-wound cathode ray tube magnetic deflection yoke of high precision. The coil turn segments are positively maintained in place on the time without adversely affecting core integrity.  
 While only certain preferred features of the invention V have been shi-iwn by w ofilliistrtitioii. many modifications and changes will&#39;occur to those skilled in the art.  
 It is. therefore. to be understood that the appended claims are intended to cover -all such modifications and changes asfallwithin the true spirit of the invention.  
  I claim: l. A direct-wound. precision deflection yoke for a cathode ray tube. comprising:  
 amagn&#39;etic core of flared configuration adapted to fit about a portion of a cathode ray tube: a coating ofpressui&#39;e-sensitive adhesive on the inner surface of said core: a first layer of coil turn segments wound atop said coating of adhesive such that said turn segments are restrained against sideward movement: and a second layer of coilturn segments wound over said first layer of coil turn segments. each turn segment of said second layer being located above and bearing against apair of adjacent turn segments of said first layer at least over aportion of the length of said core. I 2. The apparatusof claim. Lwherein said core includes a slotted end-cap at front and rear ends thereof.  
 said first layer of coilturnv segmentsextending from slots in&#39;one of saidend-caps to corresponding slots in the other of said end-caps. respectively.  
  3. The apparatus of claim2 wherein eachsaid turn segment of said second layer estends .froma respective slot in the end-cap at the front of said coreand is spaced apart fromsaid pair df. adjacent turn segments of said first layer at the front of said core. y  
  4. The apparatus of claim l wherein each turn s ment of said second layer contacts said pressuresensitive adhesive over&#39; another portion of the length of said core I l 5. The apparatus of claim 3 wherein each turn segment of said second layer contacts said pressuresensitive adhesive over another portion of the length of said core.  
 6. The apparatus ofclairn l wherein thickness of said coating of pressure-sensitive adhesive is a fraction of the radius of&#39;ivire employed in said first and second layers of coil turn segments.  
 7. A method of fabricating&#39;ti toroidal magnetic deflection yoke for a&#39;cathode ray tubecomprising:  
 coating the&#39;inne&#39;r&#39; surface of aflared magnetic core with pressure sensitive adhesive; I  
 winding a first layer of coil&#39;turns&#39; about said core directly on said adhesive coating: and  
 winding a second layer of&#39;coilturns&#39;about said core such that each turn segment of said second layer bears against a pair of adjacent turn segments of said first layer at&#39;least over a portion&#39;of the length of said core. f&#34; i 4 8. The method o&#39;f claim 7 wherein each turn segment &#34;of said second layer makes contact with said pressuresaid core.