DE2313888A1 - BEAM ADJUSTER FOR A MULTI-BEAM COLOR TELEVISION TUBE - Google Patents

Description

RCA 65,808
GB-PA 12936/72
Filed: March 2, 1972

RCA Corporation, New York, NY (V.St.Ä.)

Beam adjustment device for a multi-beam color television picture tube.

The present invention relates to a static beam adjustment device with two permanent magnets for a multi-beam color television picture tube, in particular a color television picture tube in which the electron beams in a plane or row get lost. Color television picture tubes of this type will hereinafter be referred to as serial beam color television picture tubes.

It is known that the electron beams of a multi-beam color television picture tube by magnetic beam adjusters at a point in the center of the tube's screen To bring convergence. This adjustment is known as "static convergence". The most commonly used for static convergence Beam adjusting devices used contain a magnet arrangement which is located outside the tube neck of the picture tube and is arranged around this and cooperates with pole pieces located inside the tube, each of which is one of the Electron beam are assigned.

309840/0903

2313388

Disadvantage of this, known
is _r . that bother you int pipe inside arranged Polstücfee the Äblenkfeld ,, which is usually by a Sblenkspulensatz: ι is generated in a just little: aacialext distance! ναω the pole pieces on the neck, the picture tube is arranged. Similarly, the Äblenkfeid acts so that it is difficult _r a proper and independent from the magnetic Strahlablenkfeld beam convergence to achieve a * interfere with the intended for static beam convergence pole pieces.

A magnetic beam adjuster suitable for an in-line color television screen tube that does not require pole pieces inside the tube envelope is. has been proposed in German patent application P 22 26 335.0. The proposed static beam adjustment device contains a Magnethaiterungteil _r which can have the shape of a ring surrounding the neck of the picture tube and has four magnetic poles which are distributed at angular intervals of 90 ° on the catch of the ring and have alternating polarities, so that a magnetic quadrupole field for adjustment of the two outer, off-axis electron beams arise in opposite directions. This first ring-shaped part is assigned a second ring-shaped part which has six magnetic poles which are distributed over the circumference of the neck area at mutual angular distances of 60 °. The six magnetic poles have alternating polarities and generate a magnetic sextupole field to move the two outer electron beams in the same direction. None of these ring-shaped magnet arrangements has a significant influence on the middle of the three electron beams extending in a row or plane. The proposed beam adjustment device can be used with advantage in combination with two color purity rings, each magnetized along a ring diameter and allowing all three electron beams to be adjusted in the same direction, so that both the color purity and the convergence can be adjusted.

309840/0903

It is an object of the present invention to simplify a beam adjustment device of the type proposed.

This object is achieved according to the invention by a Beam adjustment device of the type mentioned, which is characterized is through a first non-magnetic holder part, the has a central opening for receiving the tube neck and the two permanent magnets on opposite sides of the opening with the poles of the same name directed towards them, a storage device that is used for the non-magnetic mounting part and has a central opening for receiving the neck of the tube, the support member having a number of magnetic poles magnetic fields build up around the central opening to produce diametrically opposite sides of the opening, and by a device for the adjustable mounting of the mounting part and the mounting device with respect to one another.

One for adjusting the convergence of several electron beams of a cathode ray tube arranged in a row or line suitable embodiment of the beam adjustment device according to the invention, a first arrangement which is rotatable about the neck region of the tube and which contains two magnets which with equal distances along the circumference of a magnet holder part, that surrounds the neck of the picture tube> are arranged and with poles of the same name point radially inwards towards the tube neck. This arrangement allows two outer electron beam bundles Adjust in opposite directions. Furthermore, there is a second arrangement with a plurality of magnetic pole regions provided that in the circumferential direction of a "other magnet holder parts s are equally spaced, which surrounds the neck, to create magnetic fields in the same direction on diametrically to generate opposite sides of the magnet holder part with which the two outer electron beams in the same Direction can be adjusted.

In another embodiment of the invention, the first arrangement contains a magnet holding part with three magnets,

309840/0903

231388

those at intervals of 120 ° along the circumference of the holder part arranged and directed with the same poles inwards towards the neck. The second arrangement contains a component at the inner circumference of which a plurality of magnetic pole regions are provided to apply negative fields in opposite directions Generate diametrically opposite sides of the component, through which the two outer electron beams in opposite directions Directions can be adjusted.

In yet another embodiment of the invention the above-mentioned arrangements each contain two similar magnet holder parts, with the polarity of the magnets in one part of the polarity of the magnets of the other part is opposite.

In yet another embodiment of the invention becomes only one magnetic holder part of each of the above Types are used, with these mounting parts, however, a radial movement of each magnet is possible by the amount of the To be able to control magnetic flux in the tube neck.

Developments and refinements of the invention are shown in marked the subclaims.

The following are exemplary embodiments of the invention explained in more detail using the drawing, it shows:

1 shows a schematic plan view of an embodiment of a beam adjustment device used for static convergence adjustment according to the invention, which is carried out on a serial beam color television picture tube is mounted;

Flg. Figure 2 is an exploded side view of the beam adjustment device according to FIG

3 shows an end view of the beam adjustment device, seen from the right according to Fig. 2y

4 and 5 the location of magnetic poles of the various Magnet mounting parts of the beam adjustment device according to Fig.

309840/0903

2313889

Pig. 6a, 6b and 6c show the effects of the beam adjustment device with regard to the adjustment of the electron beam in opposite directions;

Figures 7a, 7b and 7c show the effects of the beam adjustment device with regard to the adjustment of the electron beam in the same direction;

8a, 8b and 8c show the effects of the static Used convergence serving parts of the beam adjustment device Color purity ring arrangement with regard to the adjustment of all three electron beams in the same direction;

9 shows a magnet holding part for a beam adjustment device according to FIG another embodiment of the invention and

Fig. IO shows a cross section of the magnet holding part according to Fig. 9.

FIG. 1 is a simplified top view of an embodiment of a static beam adjustment device according to FIG Invention based on a color television picture tube with beam generating systems arranged in a row (row beam color television picture tube) is arranged. The color television picture tube has a bulb 11 made of glass with a front plate serving as a screen 12. In the interior of the piston 11, a shadow mask 13 is arranged in the vicinity of the front plate 12, which a plurality of openings 13a through which the electron beams get to various colored fluorescent elements arranged on the inside of the front panel and stimulate them. At the the side of the picture tube facing away from the front plate 12 is mounted a deflection unit 14 surrounding the tube neck, by means of which the electron beam can be deflected horizontally and vertically according to a grid across the screen.

Seen from the front plate 12, behind the deflection unit 14, there is a static tube that surrounds the tube neck Convergence adjustment serving beam adjustment device 16, which will be described in more detail below. In the throat of the

309840/0903

231388

Piston 11 of the picture tube is located, a not shown Series gun assembly, the three separate electron beams, namely a blue beam, a red beam and provides a green beam directed onto the faceplate 12 are. The purpose of the beam adjuster 16 is in making the three electron beams converge on a common area in the center of the screen. The beam adjustment device 16 is required because the three Electron beams in general because of manufacturing tolerances in the electron gun assembly and whose mounting in the picture tube does not converge on the same area in the center of the screen. The beam adjustment device should therefore make it possible to generate suitable magnetic fields with which the three electron beam bundles are not deflected Converged state in the center of the screen can be.

The beam adjusting device 16 is exploded in FIG shown. The beam adjustment device 16 includes a hollow cylindrical central part 17 which can be pushed over the neck of the picture tube. In front is a piece of the Middle part 17 is provided with a thread 20 onto which a collar-like nut 26 can be screwed, which is used to define the various parts of the blasting device after it has been set in the desired manner are. The hollow-cylindrical central part has 17 at the rear a collar 18 which forms a shoulder for abutment of the various parts of the beam adjustment device. From the back end Several fingers 19 protrude from the hollow cylindrical central part 17, which are secured by a metal clamp 21 can be pressed against the neck of the picture tube to To prevent middle part 17 from shifting with respect to the picture tube. As Fig. 1 shows, the setting is the static convergence serving beam adjustment device 16 attached behind the deflection unit 14 on the tube neck and extends essentially over the electron beam

309840/0903

231388

generating arrangement containing part of the tube neck.

FIG. 3 shows an end view of the beam adjustment device 16 seen from the right-hand side of FIG. 2 or FIG. 1, the neck of the piston 11 is shown in section.

The components of the beam adjustment device 16 according to FIG. 2 are described below in the order in which they are mounted on the central part 17. The first two components are two purity rings 22a and 22b, each of which has at least one protruding extension 22c that enables the purity rings to be turned easily. The purity rings 22a and 22b are separated by an intermediate paper ring 23a which facilitates independent rotation of the purity rings. The two color purity rings are followed by a second intermediate bearing ring 23b made of paper, which separates them from two essentially ring-shaped magnet holding parts 24a and 24b. The intermediate bearing ring 23b made of paper prevents the other components from rotating when the magnet holding parts 24a and 24b are rotated. The annular magnet holding parts 24a and 24b preferably each have one or more protruding lugs 24c which allow the annular magnet holding parts to be rotated individually. The magnet holding parts 24a and 24b are separated from a second set of annular magnet holding parts 25a and 25b by a third intermediate bearing ring 23c made of paper. The ring-shaped magnet holder parts 25a and 25b also preferably each have at least one protruding shoulder 25c in order to be able to turn them easily. The annular magnetic holder portions 25a and 25b are separated by a fourth intermediate layer ring 23d made of paper of the nut 26 which is screwed onto the threads 20 of the central portion 17 _r set to the different ring-shaped parts, after they have been adjusted. The screw nut 26 also preferably has at least one radially protruding shoulder 26a in order to be able to screw it comfortably onto the hollow cylindrical central part 17. Preferably all components are made of

309840/0903

Beam adjusting device 16 with the exception of the Kllemmbxide 21, the metal-made color purity rings 22a and 22b * of the various magnets in, the magnet holder parts ». 24a, 24b, 25a and 25b; and the intermediate bearing rings 23a-d made of plastic or another corresponding non-magnetic material to obtain a undesirable interaction between the components of the Beam adjustment device generated and the deflection unit generated fields as small as possible «Although the color purity rings are made of metal, they are wide enough away from the deflection unit, since the interaction does not interfere. The aforementioned magnets shown in Figs are shown in more detail, can both from a permeable and also consist of a non-permeable magnetic material? However, magnets made of non-permeable material are preferred. because with these in the vicinity of the rings there is no disturbing interaction with electromagnetic fields, such as the deflection field, entry.

The color purity rings 22a and 22b are preferred Metal rings that are magnetized in the diameter direction, like this that they each have two diametrically opposite one another Form magnetic poles of opposite polarity. The ring-shaped magnet holder part 24a has three recesses on one side, which have mutual angular distances of 120 ° and contain three permanent magnets, which are so arranged in them are that the three magnetic south poles point to the tube neck. The magnet holding part 24b is constructed accordingly with the exception that those with mutual angular distances three permanent magnets arranged at 120 ° point with their magnetic north poles to the opening receiving the tube neck. The annular magnet holding part 25a preferably contains two permanent magnets, which are in corresponding recesses are arranged on one side diametrically opposite one another so that their magnetic south poles at of the opening penetrated by the tube neck and there that of create corresponding magnetic fields emanating from the south poles.

309840/0903

The ring-shaped magnet holding part 25b corresponds to the magnet holding part 25a with the exception that the two permanent magnets have their magnetic north poles at that of the tube neck penetrated openings are arranged so that in this area two opposite magnetic north poles present are.

4 and 5, the magnet holder parts 25b and 24a of the beam adjustment device according to FIG. 2 and the position of the various magnetic poles are shown. The magnet holding part 25b shown in FIG. 4 contains two diametrically opposed permanent magnets _27f, the north pole of which is closest to the area of the magnet holding part 25b that encompasses the neck of the picture tube. The magnetic flux lines running outside the permanent magnets from the north pole to the south pole are shown schematically in dashed lines. The part of the flux lines that penetrates the tube neck is of importance here, since this part of the magnetic flux enables the electron beam to be shifted in order to set the static convergence. The magnetic lines of flux drawn in, which emanate from the permanent magnets 27, intersect the annular magnet holding part 25b at common points, which are denoted ^{by S 1} and N ^1. The letter S ¹ indicates the position of the effective magnetic poles, and the letter N ¹ to the position of the effective magnetic north poles. These magnetic poles have practically the same effect as if a permanent magnet were actually arranged there, the magnetic south pole of which is adjacent to the opening of the magnet holder part through which the tube neck passes. It has been found that the arrangement shown in Fig. 4 with only two permanent magnets 27 arranged in the manner shown can effect the same function, namely the displacement of the two outer electron beam without any significant influence on the inner beam, as the proposed arrangement in the four Permanent magnets are provided, two of which point with their north poles and two with their south poles to the tube neck. In the case of the in Fig.

309840/0903

The illustrated magnetic ring arrangement can therefore be saved considerably in comparison to the proposed arrangement. A further advantage of the present beam adjustment device is that the possibility of fluctuations in the magnetic field strength is significantly lower because only two real ones Permanent magnets can be used instead of four permanent magnets. Namely, it is desirable that all magnets in one predetermined ring or mounting part as possible the same magnetic Have strength. The through the magnet holding part 25b with the permanent magnets 27 generated magnetic quadrupole field enables the two outer electron beams by rotating the magnet holding part 25b with respect to the picture tube to move in opposite directions without significantly affecting the central, inner electron beam will.

The annular magnet holding part 24a shown in FIG. 5 contains three permanent magnets 27 of the same strength, which are arranged at angular intervals of 120 ° in the magnet holding part 24a. The permanent magnets 27 are each arranged so that their south pole is at the tube neck. As has been explained with reference to FIG. 4, the magnetic flux lines of the permanent magnets 27 effectively form additional magnetic poles in the middle between each two adjacent permanent magnets in the annular magnet holding part 24a. Since the actually present permanent magnets point with their south poles to the tube neck, ^{magnetic north poles are created at the points marked N 1} and magnetic south poles at the points marked S ^1. In the arrangement according to FIG. 5, the three permanent magnets 27 effectively form a magnetic sextupole field with only half the number of real magnetic pole pairs compared to the above-mentioned proposed arrangement. As in the case of the arrangement according to FIG. 4, this results in the advantages of saving costs and reducing the risk of differences in the magnetic fluxes. The arrangement according to FIG. 5 is made possible by rotating the magnet holding part 24a

309840/0903

with respect to the picture tube, a displacement of the two outer ones of the three electron beams running in a row or plane in the same direction without that mean electron beam is influenced appreciably.

The annular magnet support part 25a corresponds to this 4 shown magnet holder part 25b with the exception, that the permanent magnets with their south poles sum the tube neck point out, and that in the middle between the south poles magnetic North Poles arise. The ring-shaped magnet holder part 24b again corresponds to the ring-shaped shown in FIG Magnet support part 24a with the exception that the point three permanent magnets with their north poles to the tube neck and therefore in the middle between the three actual ones North poles produce three magnetic south poles.

The magnets 27 are in recesses in the side surfaces housed the annular magnet holder parts. An advantage of using separate permanent magnets that are in the desired angular distances are held in the annular magnet holder parts, is that easily magnets equal field strengths can be selected, so that a uniform movement of the two outer electron beams without significantly influencing the central electron beam can be reached. In the case of magnetizable rings, such as the color purity rings 22a and 22b, it increases with increasing Number of magnetic poles distributed around the ring more and more difficult to achieve the same force flows. While it is desirable that the magnets in a given ring or magnet holder part have the same strengths, but the amount of force fluxes generated by the different magnets can vary from the bracket part to be different bracket part to meet the requirements of the Convergence adjustment for different types of picture tubes to wear.

309840/0903

- 12 - ■■

FIGS. 6a, 6b and 6c show the joint effect of the in the figures shown one behind the other annular magnet holder parts 25a and 25b with respect to the adjustment of the two outer electron beams in opposite directions, as is the case for adjusting the convergence of all three electron beams may be required. In FIGS. 6a-6c and FIGS. 7a-7c described below and 8a-8c, only the magnetic poles of the permanent magnets 27 that are actually present, which are adjacent to the tube had are shown, so as not to make the drawing too confusing. The location of the virtual magnetic poles that are also still present, which are caused by the permanent magnets actually present can be generated from FIGS. 4 and 5.

In Fig. 6a the two annular magnet holder parts are 25a and 25b arranged so that the (real) magnetic poles actually present are offset from one another by 90 °. With this arrangement, the effects of the respective rings are increased, so that the two outer electron beams be shifted by the greatest possible distance in opposite directions «, in the case of the one shown in FIG. 6a Arrangement, the two outer electron beams are shifted vertically in opposite directions. The postponement The direction of the electron beam can be determined on the basis of the known RIGHT-HAND RULE.

Fig. 6b shows the two ring-shaped magnet holder parts 25a and 25b in an arrangement in which the respective magnetic poles coincide. Lift when the magnetic poles are aligned the magnetic fields occur independently of the angular position of the two rings with respect to the tube neck and there is no displacement the electron beam. Of course, this assumes that the relative strengths or flows of forces of all four magnets in the two ring-shaped mounting parts are the same.

Fig. 6c shows the two annular magnet holder parts 25a and 25b in such a mutual position that the

309840/0903

diametrical poles of one annular holder part with respect to the poles of the other annular holder part one Have an angular distance of about 60 °. With this setting there is again an adjustment of the two outer electron beam bundles in opposite directions without any significant influence on the middle bundle, the amount of adjustment however, it is somewhat smaller than in the case of the setting according to FIG. 6a, where the magnetic fields are fully added.

Figures 7a-7c show the effects of the two annular ones Magnet support parts 24a and 24b with regard to the adjustment of the two outer electron beams in practically the same direction without influencing the central electron beam. Fig. 7a shows the magnet holder parts 24a and 24b in a setting in which the magnetic poles one Have an angular distance of about 30 °. This results in a relatively small displacement of the two outer electron beam bundles in the direction indicated by arrows.

Fig. 7b shows the two ring-shaped magnet holder parts 24a and 24b in such a relative angular position that the respective magnetic poles coincide. The Magnetic fields reappear and there is no shift in the electron beam.

Fig. 7c shows the two ring-shaped magnet holder parts 24a and 24b in a relative position in which the respective magnets have an angular distance of about 60 °. With this setting the maximum displacement of the two outer electron beams occurs. This maximum shift can can be done in any direction by putting the two annular magnet holder parts together without changing their Relative position around the neck of the tube rotates.

Figures 8a-8c show the effects of the purity ring arrangement from the purity rings 22a and 22b. As mentioned, this ring arrangement is constructed in a known manner and since each ring is diametrically magnetized and has poles of opposite polarity, no virtual magnetic

309840/0903

pole on, as in the case of the annular mounting parts 24a and 24b and 25a and 25b. Suffice it to say that the purity rings are an adjustment of everyone enable three electron beams in the same direction by rotating one or both rings around the neck of the picture tube. The conventional purity rings have been discussed here to show how they work together with the previously described annular support parts can be used in a beam adjustment device, which both allows the setting of the static convergence as well as the color purity.

It was found that the interactions are used to adjust the static convergence and color purity Beam adjustment device with the field of the deflection unit is lowest when viewed in the direction of Tubular foot along the tube neck to the deflection unit arranges the various components in the following order: First the color purity rings 22a and 22b, then the ring-shaped holding parts 24a and 24b which generate the sextupole field and finally the annular holding parts 25a and 25b generating the magnetic quadrupole field, each with the associated magnets,

The above-described embodiment of the beam adjustment device included two sets of annular support members 24a and 24b and 25a and 25b, respectively, holding the magnets are each arranged in accordance with the teachings of the invention However, the invention can be applied to only one set of annular magnet support parts, the other being Set can be designed in a known or proposed manner. In such an embodiment, for example, the annular Bracket parts 25a and 25b be designed as described in connection with FIG. 4, so that for generating the quadrupole fields for each annular support part only two real magnets are required. Instead of the ring-shaped mounting parts 24a and 24b then viürden

309840/0903

corresponding components with six actual magnetic pole pairs each or magnets instead of just three as described in connection with FIG. Of course the reverse arrangement is also possible, in which case the annular holding parts 25a and 25b corresponding components each contain four real magnetic pole pairs or magnets, while the ring-shaped Bracket parts 24a and 24b are formed according to the invention and only three actual magnetic pole pairs or magnets contain.

9 shows a magnetic ring arrangement for a beam adjustment device used for static convergence adjustment according to another embodiment of the invention. Fig. Shows this magnetic ring arrangement in cross section. With that first described embodiment of the invention were in each case for the adjustment of the outer electron beam in opposite directions or in the same directions two ring-shaped magnet holder parts with the associated magnets are required. the The direction of the respective shift could be adjusted with only one ring of each pair, the associated one However, the second ring with the magnet of opposite polarity with respect to the first ring is used to set the amount the displacement to be effected in a given direction. Such an arrangement then ensures all setting options that are required for proper convergence of the three electron beams.

In the embodiment shown in FIGS it is possible to adjust the outer electron beam in the same or opposite direction both in terms of direction and amount with only one three magnets containing annular holder part and a two magnets containing 'annular holder part to control. Generally in other words, this can be effected by any arrangement which allows the strength of the magnetic field to be varied. One possibility for this is shown in FIG. 9, the one

309840/0903

Magnet ring 30 with two permanent magnets 27 shows the two replaced annular magnet holder parts 25a and 25b shown in FIG. 2 with the corresponding magnets. The magnetic ring 30 according to Fig. 9 has a number of radial tab-shaped lugs

31, which make it easier to twist around the tube neck. The magnetic ring 30 is provided with undercut grooves 32, which of the central opening to the outer periphery. Corresponding permanent magnets 27 are arranged in the grooves so that Poles of the same name point inwards to the central opening that accommodates the tube neck. On the permanent magnets 27 are by means of a suitable adhesive such as an epoxy resin, rods 28 or the like. attached / die.sich over the outer periphery of the Magnet rings 30 extend outwards ο The rods 28 allow a radial displacement of the permanent magnets 27 in the grooves

32. With this arrangement, the radial distance of the magnets from the neck of the picture tube and thus the magnetic field strength can be set. The direction of displacement of the electron beam is thus set by the rotation of the magnetic ring 30 and the amount of displacement of the electron beam the desired direction is determined by adjusting the radial position of the permanent magnets 27 by means of the rods 28 set. The dimensions of the grooves 32 are chosen so that the permanent magnets are held in the set position by the friction.

The poles of the permanent magnets 27 facing the neck of the tube can be either north or south poles and this then gives the polarity of the virtual poles, which are caused by the magnetic flux at an angular distance of 90 ° from the permanent magnets arise. The only ring 30 acts in the The same principle as was explained with reference to the ring-shaped magnet holding part 25b according to FIG.

In a corresponding manner, the two can each have three Annular mounting location 24a and 24b containing magnets (Fig. 2) can be replaced by a single ring which has three grooves 32 offset from one another by 120 °, the three

309840/0903

Permanent magnets 27 are included with adjusting members attached to them. Here, too, the three permanent magnets can again all be directed either with their north poles or with their south poles towards the tube neck, as long as the arrangement of all three magnets is the same. The magnetic flux emanating from the three magnets then again forms three virtual magnetic poles opposite polarity in the middle between any two adjacent of the three magnets. The magnetic ring 30 according to FIG. 9 and 10 and its counterpart containing three magnets can also be made of a non-magnetic material such as plastic exist and be mounted on a similar arrangement containing a cylindrical central part 17, as shown in FIG is.

309840/0903

Claims (10)

Claims Beam j us tiervor direction with two permanent magnets for a multi-beam color television picture tube, characterized by a non-magnetic mounting part (25b, 30) which has a central opening for receiving the tube neck and the two permanent magnets (27) on opposite sides of the central opening with directed towards this eponymous poles; one next to the non-magnetic holder part H eitler u. * L% t>
arranged device which has a central opening for receiving the tube neck, the holding device having a plurality of magnetic pole regions at its central opening which generate magnetic fields on diametrically opposite sides of the opening; and by a device for the adjustable mounting of the mounting part and the storage device with respect to one another. 2.) beam adjustment device according to claim 1, characterized characterized in that the magnetic fields generated on diametrically opposite sides of the opening are the same Have direction. 3.) beam adjusting device according to claim 1, characterized by a third permanent magnet (27), which together with the first two permanent magnets through the first non-magnetic mounting part (24a) is mounted at mutual angular distances of 120 ° with respect to the opening in such a way that that the same poles of all three permanent magnets point to the central opening and that the bearing device has magnetic fields in opposite directions Directions generated on diametrically opposite sides of the opening. 4.) beam adjusting device according to claim 2, characterized characterized in that the first holder part can be adjustably stored by rotating around the neck of the tube; that a second non-magnetic holder part with a second 309840/0903 Central opening is provided, which can be rotated around the tube neck is adjustable and contains at least one set of several permanent magnets equally spaced in the circumferential direction, all of which point with poles of the same name to the middle of the tube shark area and on diametrically opposite sides of the second central opening magnetic fields in opposite directions produce. 5.) beam adjustment device according to claim 1, 2 or 3, characterized in that the first support member includes a set of permanent magnets whose The number is the same as the permanent magnets that are already arranged on this part and that are spaced equally in the circumferential direction are arranged on the first mounting part, but with the opposite poles pointing towards the neck area; that the second device includes a second set of circumferentially spaced permanent magnets which are present in the same number as those of the first sentence but with the opposite poles to Point out the neck area. 6.) beam adjustment device according to claim 4, characterized characterized in that the first holding part contains a set of permanent magnets, the number of which is equal the permanent magnets already arranged on the first part and which in the circumferential direction at the same intervals on the first mounting part are distributed, but with opposite poles to the neck area indicate that the second non-magnetic Holding part contains a second set of permanent magnets evenly spaced around the circumference, the number of which is equal to that of the permanent magnets already mounted on the second mounting part, but those with opposite ones Point the poles towards the neck area. 7.) beam adjustment device according to claim 4, characterized in that the magnetic flux paths of the two magnets (27) arranged on the first holding part (25b) are effectively two poles (S ¹ ) of the first mentioned 309840/0903 Form magnetic poles of opposite polarity, which are diametrically opposed to each other and practically along the circumference be equidistant from the first-mentioned two magnetic poles; that the set of magnets of the second bracket part (24a) contains three permanent magnets (27) which are angularly spaced of 120 ° are distributed around the circumference of the neck area and their magnetic flux paths are effectively three magnetic poles that of the polarity opposite to the polarity of the first-mentioned magnetic poles, which are substantially the same Distances in the circumferential direction between the first three mentioned Magnetic poles (S) lie. 8 *) beam adjustment device according to claim 7, characterized characterized in that the first holder part includes a set of magnets located at the first two magnets and corresponding to the first two magnets except that their magnetic poles are reversed Have polarities; and in that the second support member includes a second set of magnets disposed with the one set and correspond to this one sentence, with the exception that the magnetic poles are of opposite polarities to have. 9.) beam adjustment device according to claim 7, characterized by a third device which is around the neck portion of the tube is rotatably arranged and includes two adjacent magnetic rings (22a, 22b), each are magnetized so that they have two diametrically opposite magnetic poles of opposite polarity. 10.) Beam adjustment device according to one of the preceding Claims, characterized in that the first and / or second mounting part and / or the storage device a radial movement of the magnets for changing allow the intensity of the magnetic fields in the neck area. 309840/0903