US2333806A

US2333806A - Coil structure

Info

Publication number: US2333806A
Application number: US399315A
Authority: US
Inventors: Mauerer Leopold
Original assignee: Jefferson Electric Co
Current assignee: Jefferson Electric Co
Priority date: 1939-06-02
Filing date: 1941-06-23
Publication date: 1943-11-09
Anticipated expiration: 1960-11-09

Description

L. MAUERER COIL STRUCTURE Nov. 9, 1943.

Original Filed June 2, 1939 Patented Nov. 9, 1943 con. STRUCTURE Leopold Manerer, Chicago, Ill., assignor to Jefferson Electric Company, Bellwood, 111., a corporation of Illinois Original application June 2, 1939, Serial No. 277,044. Divided and this application June 23, 1941, Serial No. 399,315

7 Claims. (Cl. 175-21) This invention relates to a coil structure, and more particularly to a coil structure having a thin winding section and a high ratio of window length to overall length which is particularly well adapted to use as a scanning yoke for television receiving apparatus in association with a cathode ray tube, and in television cameras on the camera tube.

Although other uses may be or become apparent for the coil assembly disclosed herein, the illustrated adaptation thereof is particularly adapted to television apparatus.

This application is a division of my copending application Serial #277,044, filed June 2, 1939, Patent No. 2,269,678, granted January 13, 1942.

It is an object of this invention to provide a coil assembly for controlling the deflection of the electron beam of a cathode ray tube, which coil assembly has improved magnetic efliciency brought about by the reduction of the high reluctance air gap between the coils thereof and the cathode ray tube.

Another object of this invention is to provide a coil assembly, the coils of which have axially thin end sections so that the coil window lengths are long as compared to the available space for the coils in the direction of the longitudinal axes thereof.

Another object of this invention is to provide a coil assembly including a plurality of coils, the magnetic axes of which are at right angles, and in which the coils are self-locating in their proper positions for such angular relations. Another object of this invention is to provide a scanning or deflecting yoke for use with a cathode ray tube in television apparatus in which the efnciency is improved by utilizing coils of such size and proportion that the sides thereof surround the entire circumference of the cathode ray tube.

Another object of this invention is to provide a coil assembly comprehending prewound and subsequently assembled and deformed coils.

Another object of this invention is to provide a. scanning yoke assembly for use with television apparatus including a cathode ray tube which produces a magnetic field which is substantially uniform over the entire cross sectional area that is traversed by the beam in the tube.

Another object of this invention is to provide a scanning yoke assembly for use with the oathode ray tube in television apparatus, in which assembly the longitudinal axes of the coils are substantially parallel to the longitudinal axis of the cathode ray tube.

Another object of this invention is to provide acompact and eillcient magnetic scanning yoke for use in television receivers or transmitters which utilize a cathode ray tube for reproducing television pictures or on a camera tube for producing pictures.

Another object of this invention is to provide a magnetic scanning yoke for television apparatus which may be easily and consistently manufactured in production quantities;

Further objects and advantages of the present inventionwill be apparent from the following description, reference being had to the accompanying drawing wherein a preferredembodiment of the present invention is clearly shown.

In the drawing: 1

Figure 1 is a side elevational view showing an adaptation of a preferred embodiment of this invention to television apparatus;

Figures 2 and 3 are respectively perspective and end views of a preferred embodiment of this invention;

Figure 4 is a side elevational view of the coil shown in Figures 2 and 3 with a portion cut away to show certain structural details; and

Figures 5 and 6 are fragmentary sectional 7 views indicating modifications of this invention.

r In Figure 1 a scanning yoke [0 made in accordance with this invention is shown applied to a cathode ray tube H, in conjunction with which it is adapted to operate as a part of television receiving apparatus. The cathode ray tube II is one of the type commonly in use for the purpoes specified and has a glass envelope l2 and a fluorescent screen at one end, as at l3. The tube il includes an electron gun, the end of which is indicated by dotted lines at It, and from which an electron beam is projected against the fluorescent screen at l3. The wall ll of the tube adjacent the fluorescent screen I3 flares outwardly to permit deflection of the electron beam over a greater fluorescent screen surfaces. A neck #5 of the envelope l2 encloses the electron gun M and extends a distance beyond the end of the gun. A base I6 is secured to the end of the neck l5 and has prongs l7 secured thereto to which the electrical connections are made to theinternal elements of the tube. A terminal 18' is secured to the envelope for making an electrical connection to a high voltage electrode or anode of the tube.

. The scanning or deflecting yoke 10 preferably fits closely around the neck I5 of the envelope l2 and preferably extends from the end of the gun It to the portion of the envelope where the spect to each other that their magnetic axes are' perpendicular. It is also preferable and particularly desirable that the longitudinal axes of the coils are parallel to the electron beam in its normal or undeflected position. The magnetic axes of the coils l3 and 20 extend across the neck I5 of the tube and are substantially perpendicular to the longitudinal axis, of the tube as well as the normal or undeflected beam. In order to improve the magnetic efllciency of the scanning or deflectingyoke l0, it is particularly desirable that the high reluctance air path between the coils and the envelope is minimized. Also, a low reluctance magnetic flux path 22 closely surrounds the outer surfaces of the coils and extends circumferentially around the neck l5 of the tube. As will be more fully explained, it is desirable that the window openings of the coils are as long as possible with respect to the space available for the scanning or deflecting coil assembly between the end of the electron gun It and the outwardly flaring portion of the envelope l2. This feature provides a greater effective length of the coils in the space available therefor. In addition to being desirable from the standpoint of magnetic efficiency that the distance between the coils l9 and and the envelope I2 of the tube is minimized, it is also desirable that the air gap or leakage space between the low reluctance magnetic return path 22 and the envelope I2 is also minimized. This reduces the reluctance of the magnetic path over which there is possibility of control, since the magnetic path through the tube is flxed by the dimensions of the tube. The previously mentioned features of construction of the scanning or deflecting yoke In, as well as the features of construction and assembly which provide a yoke consistent with the features will be more fully understood in considering the detailed description of structure which follows.

In the structure of the disclosed coil assembly, a form 23 of phenol fiber or other suitable insulating material provides a cylindrical support for the coils l9 and 20. The form 23 preferably has an internal diameter such that it fits snugly around the neck l5 of the cathode ray tube ll. Also, the wall of the form 23 is preferably thin so that the length of the flux path therethrough .is minimized; although, of course, it must be sufficiently thick to provide a support having ample rigidity. In referring to the cylindrical characteristics of the form, it is understood that while a circular cylindrical form is preferable, the term cylindrical as used herein covers forms having polygonal sections.

The coils l3 and 20 are so disposed with respect to the form 23 that the sides of the coils .9 and 20 are substantially parallel to the longitudinal axis of the form. This makes the longitudinal axes of the coils parallel to the longitudinal axis -of the form and consequently makes the longitudinal axes of the coils parallel to the electron beam of the cathode ray tube when that beam is in its normal or undeflected position and the scanning or deflecting yoke It is properly mounted on the tube. The coil sides which are adjacent the form are axially straight and sectionally conform to the outer surface of the envelope. The transverse disposition of the coils is such that their magnetic axes are perpendicular. Several assasoe advantages are gained by making the coils of such a width that the circumferential spread of the sides of one of the coils is substantially equal to the width of the window of the other of the coils. That is, the design of the coils is preferably such that the coil sides of each of the coils clrcumi'erentially covers one-fourth of the surface of the'form 23 or the coil sides are so proportioned in any event that the coil sides of each of the coils flt into the windows of the other of the coils. Some of the advantages which are attendant with this construction are:

(a) That the coils l3 and 20, when secured in position, naturally and automatically space themselves in such positions that their magnetic axes are perpendicular;

(b) The windings are spread over the entire circumference of the form so that a maximum number of turns can be put into a minimum of radial space;

(0) The magnetic efficiency of the yoke is improved by minimizing the radial air space required by the coil sides;

(d) The distribution of the magnetic fleld is substantially uniform over the entire cross sectional area of the cathode ray tube which is transversed by the electron beam in that tube; and

(e) Inconsistencies of manufacture of the yokes in quantity production are limited.

In the flnal assembled form of the yoke H), the end turns of the coil l8 and 20 extend outwardly from and circumferentially around the ends of the form 23; half of th end turns of each coil extending around one side of th form 23; and the other half of the end turns of each coil extending around the opposite side of the form 23. As indicated in the drawings, half of the end turns of the coil l9, indicated at 24 and 25 extend around one side of the form 23 and the other half of the end turns of the coil l9 indicated at 26 and 21 extend around a portion of the form 23 diametrically opposite the end turns at 24 and 25. Likewise, the coil 20 has half of its end turns, as at 28, extending around one side of the form 23 and the other half of its end turns extending around the diametrically opposite side of the form, as at 29 and 30.

The end turns such as 24, 25, 25, 21, 28, 29 and 30 of the coils l9 and 20 are preferably so relatively disposed that they extend radially outwardly from the form 23 and have a section which is axially thin. The end turns of half of the turns of each of the coils extend around diametrically opposite halves of the form 23. The

thin axial section of the end turns which is particularly desirable provides coil windows which are axially long as compared to the overall axial length of the finished coils l9 and 20 and the overall length of the finished yoke. The ratio of axial window length to the yoke length should be high to provide windows which are as long as possible in the space available for the yoke. As indicated in Figure 1, the space available for the yoke is that between the end of the electron- Althouzh the coil assembly may be impregnated with wax or some similar substance to help to hold the turns thereof in their assembled pomtions. this procedure is not particularly necessary when the coils are assembled on a form such as 23. The coils l9 and 23 are held in position with respect to the form 23 by a wrapping of an adhesive tape such as 32 which may b a cellulose tape. Also, to strengthen the end turns and better to secure their positions, wrappinzs of an adhesive tape, such as cellulose tape, surround the end turns 24, 25, 26, 21, 28, 29 and 30, as at 33, 34, 35, 36, 31, 38 and 39 respectively.

As illustrated. in Figure 4, the low reluctance magnetic flux path 22 which surrounds the windings of the coils l9 and 20 preferably comprises a plurality of layers 40 of magnetic wire wrapped circumferentially around the coils and having the layers 40 separated by paper 42 or other suitable insulating material. The low reluctance path 22 provides a return path for the fiux of the coils i9 and 2B which passes through the cathode ray tube II to effect deflection of the electron beam. Since the internal diameter of the form 23, and the consequent length of the air gap within the form 23, is determined by the diameter of the neck l of the cathode ray tube, the length of that portion of the flux path is determined. However, the magnetic efiiciency of the yoke is improved by minimizing the space between the low reluctance path 22 and the inside of the form 23. By utilizing the entire outer surface of the form 23 for winding space and eliminating gaps between the windings, a greater number of turns are wound in a given radial space to reduce the length of the air gap outside of the cathode ray tube and improve magnetic efilciency. It is important also, from the standpoint of minimizing the radial space required by coils i9 and 20, that the space factor of the windings themselves be kept high.

In the yoke illustrated in the drawing, each of the coil windings of each of the two coils i9 and 26 covers approximately one-fourth of the outer surface of the form 23. The sides of each of the coils are approximately the same width. It is understood, however, that the sides of one of the coils may be made wider than the sides of the other coil, but in such proportion that the sides of the two coils abut and cover the surface of the form 23. Such distribution of the coils on the surface of the form gives a distribution of the windings and their magnetic fields which are comparable to the picture proportions commonly utilized in television apparatus, as for example the proportions of 3 to 4.

In the modified structure disclosed in Figure 5, the coils i9 and have a plurality of layers; the coil i3 having layers such as 43 and 44. Although it is understood that the coils of any of the various forms disclosed may have either one or a-plurality of layers, the particular form disclosed in Figure 5 has a part of the layers, such as the layers 43 of the coil l9 and the layers 45 of the coil 20, which are of substantially the same width as, and fit into the window of the other coil to cover the entire circumference of the form 23. These

layers

43 and 45 accomplish the spacing of the windings upon the form and the self-alignment and positioning of the coils l9 and 20. The other layers, such as 44 and 46 of the coils are so distributed that they provide a desirable distribution of the magnetic fields of the coils. With the layers 44 and 43 distributed intermediate the edges of the coils l3 and 20 respectively, a type of distortion known in the art as "barrel distortion is obtained. This particular type of distortion is utilized in compensating for a characteristic of some cathode ray tubes. This distortion would normally tend to cause the sides of the image pattern to bulge or be convexly distorted from the normal or undistorted pattern. Although the inherent spacing alignment of the coils is not attendant with the spacing of the sides of each of the coils, one from the other, it is understood that other struc tural features of the yoke might be utilized with the coil sides spaced apart or separated on the form 23.

In the modified structure illustrated in Figure 6, the sides of one of the coils overlap the sides of the other coil as illustrated at 41 and 48 where the sides of the coil l9 overlap the sides of the coil 20. The overlapping of the coils in this manner provides a form of distortion which is known in the art as pincushion distortion. This type of distortion is sometimes desirable to compensate for other variations and character istics of the cathode ray tube.

In all of the forms of the yoke l0 which have been described herein, the sides of the coils i9 and 23 are preferably continuous, but it is understood that the halves of the coils may be separately wound, and then assembled and connected together. It is also a feature of the design and structure disclosed herein that yokes similar to those disclosed may be made on a removable form, supported by an impregnation or coating of wax or other suitable insulating material and the form then removed from the finished structure.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

Whatis claimed is:

1. A coil assembly comprising, in combination, a pair of coils having side portions and end portions and window openings defined by said pertions, portions of the coil turns comprising the side portions being substantially parallel and together defining a cylinder having an axis substantially parallel to said side portions, the side portions of each of the coils being of substantially the width of and fitting into the window openings of the other of the coils, and the end portions of the coils extending radially about said defined cylinder.

2. A coil assembly comprising, in combination, a pair of single layer coils having sides and ends and window openings defined by said sides and ends. the portions of the coil turns comprising the sides being substantially parallel and defining a cylinder, each of the sides of each of the coils covering substantially one quarter of the circumference of the defined cylinder and means securing the coils in position.

3. A coil assembly comprising, in combination, a cylindrical form, a pair of multi-layer coils having sides and ends and windows defined by the sides and ends, the turns of the sides being relatively disposed to define a cylinder and extending longitudinally of the defined cylinder, at least one of the layers of each of the sides of one of the coils being of substantially the width of and fitting into a window of the other coil, and means securing the coils in position.

4. A coil assembly comprising, in combination,

a pair of multi-layer coils having sides and ends and windows defined by the sides and ends, the turns oi! the sides being relatively disposed to define a cylinder and extending longitudinally of the defined cylinder, at least one of the layers 01 each of the sides oi one of the coils being of substantially the width of and fitting into a window of the other coil, the remaining layers of each of said sides of said coils being narrower than the window width of said other coil and symmetrically spaced with respect to other layers, and means securing the coils in position.

5. A coil assembly comprising, in combination, a pair of coils having sides and ends and windows defined by the portions of the coil turns comprising the side portions and ends, the sides of said coils being substantially parallel, said coils being disposed with their magnetic axes substantially perpendicular, and -the sides of one coil being or substantially the width 01' and fitting into the windows of the other coil.

6. A magnetic deflecting yoke for a cathode ray tube comprising a pair of coils each having side portions and end portions defining windows, each of said side portions being shaped to define a longitudinal section of a cylinder, the turns of the side portions of each coil extending longitudinally of and being spread over said defined cylindrical section so as to occupy the minimum of radial space, the side portions or one coil being so dimensioned and arranged as to seat in the windows of the other coil so that together all the side portions or said coils define a complete cylinder and upon assembly the axes or said coils automatically are arranged substantially perpendicularly to each other, the end portions of said coils extending in partial overlapping relation outwardly and radially from and about'said defined cylinder vto produce -a high ratio of window length to overall length. w

7. A magnetic deflecting yoke {(111 a cathode ray tube comprising a pair of coflsfeach having side portions and end portions defining windows,

each of said side portions being shaped to define a longitudinal section of a cylinder, the turns of the side portions of each coil extending longitudinally of and being spread over said defined cylindrical section so as to occupy the minimum or radial space, the side portions of one coil being so dimensioned and arranged as to seat in the windows of the other coil so that together all the side portions of said coil define a complete cylinder and'upon assembly thev axes of said coils automatically are arranged substantially perpendicularly to each other, the end portions of said coils extending in partial overlapping relation outwardly and radially Irom and about said defined cylinder to produce a high ratio of window length to overall length, and a low reluctance magnetic return path comprising a plurality of layers of magnetic material insulated from each other and extending circumferentially around the side portions between the end portions of said coils.

LEOPOLD MAUERER.