DE1910855A1 - Magnetic deflection system - Google Patents

Description

SANDERS ASSOCIATES, INC.

95 Canal Street

Nashua, New Hampshire 03060

Magnetic deflection system

Addendum to patent (P 15 64 746.8)

The main patent relates to a magnetic deflection system for a picture tube, which is characterized in that the side of the path of the cathode ray Deflection windings are widened at the front end, so that they generate a curved magnetic field, the Force streamlines are inclined outward in the direction of the path of the cathode ray, mainly around the deflected beam to be recorded vertically. The invention relates to a Improvement and further development of the arrangement of the main patent with the aim of creating special facilities for the To avoid correction of pillow-shaped distortions, which are still required in the arrangement of the main patent and consequently make the magnetic deflection system of a tube complicated and expensive. A simplification of the magnetic deflection system and an increase in it The invention achieves effectiveness in that the particles on opposite sides of the path are charged arranged deflection windings have sections which run generally in the direction of the web, as well as front transverse sections, which generally run perpendicular to the track and are given in the longitudinal direction on a conical shape

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outside widening extension of one of the windings limited pipe lie to a non-linear magnetic field to produce whose field lines curve inwards to the longitudinal axis of the tube, so that firstly the non-linear Field pillow-like distortions of what is written on the screen Images caused by differences in the radius of curvature of the screen and the deflection radius of the beam, corrected and secondly only a minimal field difference on Beam cross-section exists. The design of the magnetic deflection system according to the invention enables an exceedingly precise deflection of the cathode ray without impairing its concentration, so that tarnishing of the image point is avoided will.

An embodiment of the invention is shown in the drawing shown. Show it:

Fig. 1 pincushion distortions of the cathode ray a picture tube;

2 shows the structure of a picture tube in section;

3 is a perspective view

the deflection system according to the invention;

4 shows a representation of the course of the cathode ray in four different sectional planes of the picture tube. _;

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«7

A preferred exemplary embodiment of the deflection system according to the invention also corrects pillow-shaped distortions, to be precise without significant impairment of the desired deflection yoke characteristics described above. Pincushion distortions, as shown in FIG. ₀ 1, arise as a result of the different radius of curvature of the screen and the scanning path of the electron beam.

2 shows in detail a cathode ray tube 120 which generates an electron beam 122 impinging on a screen 120a. The beam is focused using a conventional magnetic lens so that its cross-section decreases as it approaches the screen. A deflection yoke 124 seated on the tube neck deflects the electron beam 122 in a controlled manner so that it impinges on the desired points on the screen. The deflection of the electron beam 122 takes place around a theoretical deflection center which lies approximately in the center of the deflection yoke 124. As Flg _u 2 shows the beam can deflect vertically to describe an arc 126 whose radius of curvature, the distance between the sheet and the deflection center in the deflection yoke 124 is € _c Also, the beam can be horizontally deflect to the same kind sheet to describe in a horizontal plane,

The screen 120a with the arch 126 (and also coincide with the arc described in the horizontal plane, a network of lines written by electron beam 122 would appear perfectly right-angled because the sine the deflection angle of the beam corresponds to the current in deflection yoke 124

009837-U5J7 * .-

U5

I Ii ί

~ * - 1910355

is proportional. As a result of the different radius of curvature of the screen and the scanning path of the beam, however, the network of lines actually written on the screen looks as in FIG Fig »1 from. The lines curve inward, and the ab ^ The distance between them increases with increasing distance from the center of the screen. That pillow-like distortion becomes stronger the larger the deflection angle, and becomes visible in cathode ray tubes with a deflection angle won over 40 °. With today's televisions and viewers, in which tubes with a deflection angle of up to 90 or are used, this distortion is therefore a serious problem «,

Previously, pincushion distortion has been corrected in one of three ways, but each with one particular disadvantage is connected «So can pillow-shaped Distortions can be corrected by manipulating the waveforms of the current applied to the deflection coils Art correction, however, is quite difficult and costly, as it is a cross-wise addition of the vertical and horizontal Requires deflection signals. In addition, the right attitude is difficult to maintain in her. the second possibility is to use the deflection field in the 3och by redistributing the deflection windings in the main style of the yoke. This second flflöglicbkafc will however rarely used because it requires the creation of an inhomogeneous field in the main part of the deflection yoke through which the Beam is very strongly distorted and defocused »

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-jf- 1910355

In the third and most used way to correct pincushion distortion, a static magnetic correction lens is used, which is arranged at a distance in front of the deflection yoke * This type correction device can be in which, in connection with FIG _e 1-6 of the main patent described 3och benutzem. But it also has several disadvantages. At first it is difficult to adjust "But it is even more greasy in mass production to ensure that such an adjustment is the same for all specimens". In addition, it is extremely greasy, if not impossible, to adjust the static lens to find, which corrects the pillow-shaped distortions and ensures that the distance between the lines of the network of lines remains the same. That is, the static lens can indeed straighten the horizontal and vertical lines in the network of lines of FIG. 1; however, since this is a static correction, it cannot restore the even spacing between the lines. »Finally, it can also cause other distortions. This type of correction cannot therefore be used where extreme precision is required.

3 shows a vertical deflector 130 of a deflection system which is used to correct for pincushion distortions and yet a linear beam deflection with only low beam distortion, aberration and defocusing let reach. For the sake of clarity, only a few turns are shown, with the space between them also exceeding

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is shown.

The associated horizontal deflection part is designed in exactly the same way as the vertical deflection part and is therefore not described in more detail. It is related to the deflecting part 130 in the same relationship as the deflecting part 12 to the deflecting part 10 in FIG. 1 of the main patent. That is, both baffles are nested and perpendicular to each other, as described in detail above. In addition, the invention are arranged two deflector members themselves still within a Ferritmantels similar to (flantel 14 of FIG _o 1 of the main patent, in the present embodiment "Hflit except uieiter below specifically mentioned details so the deflection system operates with the deflector 130 of Fig. 3 as well as the system shown in the main patent.

A bell-shaped hollow body belongs to the deflector part 130 132 of insulating material which is formed towards the rear as a generally cylindrical tube 134 and extends widened forward to a cone 136, the shape of which later will be described in more detail "Otherwise the hollow body 132 resembles the body 19 of FIG. 1 of the main patent"

On the outside of the hollow body 132 is a pair essentially identical, diametrically opposed windings 138, 140 arranged in the manner of a Helmholtz coil * In use, the deflector 130 is oriented so that the windings 138 and 140 are inside the hollow body generate a generally horiaontalea magnetic field. This horizontal magnetic field causes the vertical beam deflection «

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Both windings 138, 140 each form one right-angled spiral which sits on the hollow body 132 in the longitudinal direction. In the deflection part shown in more detail in FIG 130 each winding 138, 140 has four windings »Die Longitudinal sections 138a and 140a of these windings are distributed on the circumference of the hollow body 132 in the same way as the longitudinal sections 34a and 36a of the deflector 10 in Fig. 1 of the main patent, the front Uuer sections 138b and 140b of the two windings also run in a location around the circumference of the cone 136, and the rear "LJuer" portions 138c and 140c run generally around the circumference of the rear end of the tube 134.

The longitudinal sections 138a and 140a are distributed on the circumference of the tube 134 in accordance with a sine function arranged to generate a homogeneous magnetic deflection field inside the tube 134.

As FIG. 3 further shows, the front transverse sections 138b of the winding 138 are distributed on the cone 136 in such a way that the distance between them on the cone surface i becomes increasingly larger the closer one approaches the front end of the cone. More precisely, in the illustrated embodiment, the distance between successive transverse rib cuts increases linearly. In a typical case, the distance between the two innermost transverse sections 138b is, for example, 1.25 mm, the distance between the next two sections 2 _V 5 mm and between the third and fourth section 3 _; 75 mm. The length of the cone 136 is so large that the desired number of cross sections

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BATH ORIGINAL

can be accommodated.

The cross sections 140b have the same distribution u / ie the cross sections 138b,

A deflection system was also constructed in which the transverse sections 13Bb and 140b correspond to a power function, i.e. a quadratic function, are distributed " In this embodiment there are consecutive Sections further apart than in the linear distribution. This distribution therefore requires a longer cone 136 to accommodate the same number of conductors.

As shown in Fig, 3 and 4 AD show the two UJicklungen produce 138 and 140 of the vertical Ablenktei ^ s 130 when energized a generally horizontal IYIagnetf eld _f which the electron beam 122 (Fig. 2) deflects vertically, was u / ie previously described . This deflection field is generally homogeneous in the pipe 134. However, does the beam move further forward and away from the axis of the deflection yoke ujeg _? so it gets into the area of influence of the transverse sections 138b and 140b, which in the interior of the cone 136 cause a non-linear field distribution through which the pillow-shaped distortions are dynamically corrected "

Figures 4A-D illustrate the Faldverteilung inside of the hollow body 132 at the dan correspondingly-.feo <= <recorded stables on the longitudinal axis of the fiblonkteils 130 of Figo 3 »The solid Linisn provide the VOA vertical Ablenktsil 130 magnetic field generated is _a Ois Sfesbezeichnen the resulting in a similar (non-gszsigian tal deflecting part) field

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ORIGINAL BATHROOM

Fields and cone also forward, as shown in Fig * 2 of the The main patent shows, for better illustration they are shown in Fig. 4fl ~ D, however, without this forward curvature.

As shown in FIG. 4A, the electron beam 122 falls. at point A in the cylindrical part of the deflector 130, i.e. in the tube 134, essentially with the longitudinal axis of the deflector 130 together, and the beam diameter is relatively large at this point. In addition, the vertical and horizontal deflection fields are very linear and homogeneous here, as if through the field lines running essentially perpendicular to one another are indicated. This is important because of the diameter of the electron beam 122 is here relatively large in relation to the diameter of the deflection field, more precisely, the beam diameter and the strength of the deflection field are both relatively large. Therefore, even a slight field distortion results a relatively large difference in field strength and / or direction from one side of electron beam 122 to the other « Electrons from one part of the beam would therefore be deflected very differently than electrons from another part of the beam and thus one defocus and image distortion cause.

The deflection fields generated by the vertical and horizontal deflection part now deflect the electron beam 122 from the longitudinal axis of the yoke in the direction of the maximum deflection. AuBerdem takes the electron beam 122 gradually increasing in cross section from because it is focused by a focusing coil, as mentioned above "

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5 "-f / Λ" "■: *

fig, 4B illustrates the deflection fields at point B, the one immediately beyond the first pair of cross sections 138b, 14b. This pair of current-carrying conductors running around the circumference of the cone 136 causes the deflection fields the necessary inhomogeneity to correct pillow-shaped Distortions, such as those that occur when the beam is deflected from the axis of the shaft as shown, "nevertheless caused this irregularity in the field results in very little distortion of the electron beam 122, since the deflection field increases in cross section and thus becomes less strong at the same time the cross section of the electron beam 122 becomes smaller. Therefore, even with a relatively large one field inhonogeneity the absolute extent of the field change on Electron beam 122 is small and the beam is only minimally defocused

The correction process then continues, iuobai on the one hand the correction inhomogeneity in the magnetic field the closer the electron beam 122 moves approaches the screen, while on the other hand the field strength is increasing and simultaneously reducing the beam diameter. FIG. 4C shows, for example, the deflection fields at point C, which is immediately beyond the third pair of transverse sections 138b and 14Db were these three pairs of circumferential sections Lüicklungsabschnitts cause a relative in the fields Great irregularity, as indicated by the inward curving magnetic field lines. These Great inhomogeneity is required to correct the

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pincushion distortion needed as the electron beam is now relatively far away from the butt axis »However, the field strength and beam diameter are also here again much smaller than at points A and B, so that the inhomogeneous field is still only a relatively small one Causes point distortion and defocusing.

If one moves even further forward on the longitudinal axis of the deflecting part 130 and one comes to point D at the front end of the butt, the deflection fields become even more inhomogeneous and larger in order to reach the electron beam, which is now at its greatest distance from the yoke axis is to be able to make the necessary correction "At the same time, however, the field strength and the cross-section of the electron beam have decreased even further, so that there is only a small field strength" and directional difference at the beam. Therefore, the inhomogeneous fields cause even at this point no appreciable distortion vein defocusing of the electron beam 122 _O

In this way it becomes progressive through itself changing uniformities caused by the tapered overabsctinities 138b and 14Qb of the deflections are generated in the llflagnetfeidern, a dynamic correction of the pincushion distortions at the same time minimal beam distortion achieved. The reason for this is that on the one hand the inhomogeneity in the fields increases, while, on the other hand, the product of field strength and cross-section decreases even more rapidly, so that the non-linear

Fields only have a minimal tendency to distortion and defocusing to open the beam "It is important to le to point out that the correction of pillow-shaped distortions effected by the deflection yoke according to the invention is of a dynamic and not of a static nature. That is, the inhomogeneous Correction fields which act on the electron beam 122 change progressively as the beam passes through through the cone, the advantage of this dynamic correction over the normal correction made with a magnetic lens static correction consists in the fact that dynamic correction does not only involve pincushion distortions can be corrected, but such a correction without any change in the line spacing in the ideal right-angled Line network, as it occurs in a conventional system with a fixed magnetic correction lens, done o

luie best Fig _o 1 shows the main patent, tu-ird at conically outwards running windings, such as those in the deflector 12, the distance between the longitudinal portions 50a, 52a of the windings due to the slope of the cone always greater the further they are on extend up the cone. As has been found, a correction of pebble-shaped distortions can be achieved by arranging the conductors of the windings appropriately distributed in the area running up the cone.

If, for example, the longitudinal sections of each winding in the area running towards the cone are at the same branching distance from one another and not at a constant U-angle

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arranged from the center of the deflecting part 12, so uiird am The end of the cone creates an inhomogeneous field that is sufficient to correct pillow-shaped distortions. This corrective ladder distribution can instead of that described in connection with FIG Corrective action to be applied. In the other case it can also be used together with the construction of Fig. 3 to make an additional pillow-shaped correction To achieve distortions.

In addition to the common lens used for static correction of pillow-shaped distortions, is by the yoke construction according to the invention also the Ab ~ Steering effect somewhat improved. The reason for this is that the Transverse sections 138b and 140b are arranged at an increasingly larger distance from one another »This reduces the overall capacity of the yoke, even if in the present case Construction the windings have more turns than a comparable conventional yoke. Also eliminated the present construction the large adjustment difficulties that occur during manufacture and service, with which the usual correction devices consisting of magnetic lenses are afflicted,

As mentioned earlier, it is especially important that at the rear end of the deflection yoke, aleo at that of the beam generator facing end, a homogeneous field is maintained, since this is where the electron beam has its maximum cross-section and therefore most sensitive to minor ones Is inhomogeneities. From the standpoint of low aberrration, and When considering beam distortion, the effectiveness of the deflection

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yoke from Fig. 1 quite well. Due to the insulation-iziujischen each rear cross sections 34c, 36c, ¹ 50c and 51 <3 ^ Γ u / but iron the deflection at the rear end of the yoke '■■ "-" ■ - "^' a slight Inhomogehität in this way is suitable. Such a yoke-meniger is good for high-resolution image reproduction that requires extremely precise deflection and low beam distortion, aberration and defocusing.

Be Celtic is this problem, the deflector Menn in printed circuit technology manufactured ^ ¹ since the Plattierungsv / organg conditioned 'to keep the distance between the cross-sections of the windings applied high greater) than if one would use for the windings Läckdraht.

By suitable shaping of the Wickitingsqüeräbsebnitte on the pipe 134, the deflection system of FIG. 3 also corrects this field inhomogeneity occurring at the end of the deflection part. As previously admonished, the longitudinal sections 138a and 138a 140a on the circumference of the pipe 134 corresponding to a "Sirius" functionally distributed in order to '' obtain a homogeneous field throughout the pipe "

In practice, this conductor distribution is determined by a number of equations, the derivation of which is based on the assumption that the number of field-generating turns remains constant over the entire length of the pipe 134. However, one approaches the rear end of the tube 134 to the point 1, as one crosses while the innermost portion of the cross-winding; at this point there are thus too few turns (that is, one Ulin-

191035

manure). The radial distribution dBr longitudinal sections 138a and 140a, as determined by the original set of equations, does not produce anything absolutely homogeneous in this area Field more.

If you go from point 1 to point m, you cross another transverse section; are at this point so again two turns less, which in the area the field inhomogeneity becomes even stronger between the two outer transverse sections.

Only a few turns are shown in the deflecting part 130. (However, Klan can imagine that at a distraction with numerous turns the irregularity in the field at the rear end of the deflection part even larger and closed would result in significant beam distortion and aberration.

A deflection yoke with deflection parts constructed according to FIG. 3 corrects these field inhomogeneities occurring at the rear end of the yoke, if the cross sections of the windings (e.g. at 1 and m) designed accordingly.

More precisely, according to the invention, in the case of the angle sections 13Ba and 140a, the conductor course is changed in the angle sections in the areas between the successive transverse sections 138c and 140c in order to compensate for the reduced number of turns in these areas. For example, the fundamental equations that are decisive for the conductor distribution in the areas in which points 1 and m are located are changed in order to correct the reduced number of connections in these areas. Daa.Jie.iisst _{; f;} N in equation 1

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ui is reduced by each. The equations thus corrected then result in a new distribution of the winding sections for these areas, which creates a homogeneous field there is effected.

As FIG. 3 shows, the corrections made to the conductor distribution appear as rounded corners on the turns of winding 13B and as similarly rounded corners 152 on the turns of winding 1A0 at the rear End of deflector 130. Ideally, each corner consists of one or more short conductor sections 15Qa, 152a, those to compensate for the lower number of turns in successive Represent the redistribution of the conductor run in the angular sections provided for in the areas. These Corner sections can be clearly seen in Fig. 3, since only u turns are shown and the distance between them is exaggerated. As can be seen, in the ideal case each corner section forms the beginning and end of a transverse section end. In practice, however, the corners 150, 152 would appear less rounded if there were several Windings are relatively close to each other.

The same correction can also be made at the cone end of the deflection yoke in order to further improve its effectiveness. _{In this case, the electron beam finds a very homogeneous F 8} Id at any point in the yoke, including the two areas in which the transverse sections of the windings are located. Normally, however, this correction is not made at the cone end of the deflector parts of FIG. 3, because the redistribution just described

009837/1817 BADOFHGfMAL

the conductor sections are not completely compatible with the conductor distribution on the cone, which is more pillow-shaped for correction Distortion is required. The deflection yoke according to Fig. 3 also has the advantage that due to the distance between the transverse sections the capacity between the winches is reduced. This increases the resonance frequency of the hole and its deflection speed “Without the one described above Up to now it was practically not possible to distribute the conductors in the UJwinkel sections to be arranged from each other and still get a high-performance deflection yoke.

In relation to the center point of the ladder, a ladder distribution can be derived that is independent of the factors d, k and L of equation (1). Such a distribution can be represented as follows:

θ = tan " ¹ γ (2)

'~ "j \ i + i ~ \ 3 )

Y = \ fü)? . (4)

The expressions (2), (3) and (4) also make also eliminates certain ambiguities that can sometimes result from the application of equation (1). It should be noted that these expressions ~ like equation (1) also have a result in sinusoidal distribution. Although the expression (2) is expressed as a function of tangencies, it results from simple trigonometric substitution the equivalent sine function}

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g _n = sin

An improved magnetic deflection system has been described above which is capable of deflection in two Directions suitable. The deflection system according to the invention leaves but also work effectively there, ujo the distraction should only take place in one direction. In this case one can use a deflection yoke that is just one of the ones previously contains deflection parts. Sometimes a high-speed deflection can only go in one direction, for example in the horizontal direction. In this case the desired result can be achieved by using a deflection yoke with dsm deflector 12 in conjunction with a conventional one vertical deflector with lower deflection speed used. In addition, the inventiveGe Deflection system generally also in connection. with other types of particle generators for the controlled deflection of any particle beams with a charge, such as atwa one Proton beam, use.

In summary: ITlit the deflection system described above the magnetic fields generated in the system are shaped in such a way that that they are maximally used to deflect the beam. The total inductance of the 3ochs is limited to a minimum, so that the yoke has a high deflection speed. In addition, the deflection is very uniform, which means that the image reproduction is highly linear and Edge sharpness is characterized by the system according to the invention will also have better efficiencies, of the order of magnitude

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of 75 %, possible so that the power requirement of the system is minimal *

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Claims (10)

Claims 1 . IClagnetic deflection system according to patent application P 15 64 748.8, characterized in that each on opposite sides of the charged particle trajectory Deflecting windings have sections that run generally in the direction of the web, as well as front transverse sections, which are generally perpendicular to the track and distributed in the longitudinal direction on a cone-shaped outward extending extension of a pipe bounded by the windings in order to generate a non-linear lYlagnetfeld, whose field lines curve inwards to the longitudinal axis of the pipe, so that, firstly, the non-linear field is pincushion-shaped Distortions of the image written on the screen caused by differences in the stage of curvature of the screen and Deflection radius of the beam are conditioned, corrected, and secondly only a minimal field difference at the beam cross-section consists. 2. magnetic deflection system according to claim 1, characterized characterized in that the front transverse portions of each winding on the cone are spaced apart from each other at an increasingly larger distance are arranged. 3. (Magnetic deflection system according to claim 2 _r, characterized in that the distance between the transverse sections increases linearly in the direction of the outer end of the cone. 4. magnetic deflection system according to claim 2, characterized in that the distance between dea Quefabsctinitten increases in the direction of the outer end of the cone in accordance with a potential law. " 009837/1817 5. Magnetic deflection system according to claim 1,
characterized in that the front cross sections
are also distributed so that the magnetic field lines also curve outwards in the direction of the path, so that the field lines run generally perpendicular to the electron beam, and this is deflected by the deflection device towards the transverse sections of the windings. 6.! Magnetic deflection system according to claim 1, characterized in that on opposite sides
Sides of the web are arranged deflections, each having the shape of a generally right-angled spiral and
Include longitudinal sections which run generally in the direction of the web and rear transverse sections which run generally transverse to the web and are distributed generally parallel to it, and that the turns of each winding are at the rear
Winding ends have corners that are designed so that in
Area between the rear cross sections ain homogeneous field is maintained. 7. magnetic deflection system according to claim 6, characterized in that each winding has front transverse sections which are distributed so that the magnetic
Field lines also curve outward in the direction of the path so that they are generally perpendicular to the electron beam when it is deflected towards the front cross-sections. 8. Magnetic · deflection system according to claim 7, characterized characterized in that the existing corners of each winding at the front end of the winding are designed so that in the Ba- 009837/1817 BAD ORIQtNAt rich between the front transverse sections a homogeneous Field is retained. 9 "Magnetic deflection system according to claim 6, characterized characterized in that the longitudinal sections of the windings are arranged according to the following equation: ωό θ the angular position of the nth longitudinal section of the winding from the reference plane is at. of which it is a plane acts through the center point of the innermost winding loops and runs along the longitudinal axis of the tube, N is the number of turns of the winding, and η is the longitudinal section whose angular position is measured, ujobei θ at each rear transverse section is recalculated to the reduced joins N, which is N «2n, to be taken into account. 10. Iflagnetisches deflection system according to claim 1, characterized characterized in that the transverse sections of the deflection windings distributed in the longitudinal direction on an extension of one of the deflecting windings that widens conically outwards limited pipe lie in order to generate a non-linear magnetic field, the '"eldlinien inward to the longitudinal axis bend the pipe so that firstly the nonlinear field corrects pincushion distortions and secondly only there is a minimal field difference at the beam cross-section, that the cross sections are also distributed so that the magnetic field lines bend in the direction of the orbit so that they are generally perpendicular to the electron beam run towards the front quorum sections 009837/1817 BATH ORIGINAL of the windings that the windings also have rear transverse sections which lie in a direction generally parallel to the web and that the turns of each winding have corners which are shaped so that in the area between the rear cross sections a homogeneous field is maintained » 009837/1817