EP0638921A1 - In-line beam system for image tubes - Google Patents

Abstract

In-line beam systems (14) with self-converging deflecting units (deflectors) (15) have the disadvantage that during the deflection of the outer beams (R, B) vertical bars of the colours red are wider in the 3 DEG DEG deflection region than vertical bars of this colour in the 9 DEG DEG deflection region. The conditions, just described, are precisely reversed for the colour blue. In addition, it is found in these systems that, when modifying a grid 3 voltage which has been determined to be optimal, a convergence error occurs which is designated as grid 3 convergence running. According to the invention, a beam-producing system (14) is specified in which the s-distances (spacings) (A1, A3) in grid 1 (18) in grid 2 (19) and in the upper part (20.4) of grid 3 (20) are identical and the s-distance (A2) in the lower part (20.1) of grid 3 (20) is greater than the s-distance (A1) in grid 1 and smaller than the s-distance (A4) in grid 4 (21). In such a system, the vertical bars of the colours blue and red are largely homogenized in the 9 DEG DEG or 3 DEG DEG deflection region of the monitor (11). In addition, such a system (14) is resistant in terms of grid 3 convergence running when the grid 3 voltage is changed. <IMAGE>

Description

Technical field

The invention is concerned with an in-line beam system for picture tubes, in particular one which is suitable for eliminating the grid 3 convergence and upon deflection of the electron beams in the 9 ° and 3 ° range of the screen to produce this vertical bar largely homogenized in the stripe width.

State of the art

In-line beam systems for picture tubes have long been known in the prior art, so that only the essentials for understanding the invention need be discussed at this point.

In-line beam systems are usually formed by a cathode arrangement and a grid arrangement upstream of this cathode arrangement in the direction of the screen. The cathode arrangement comprises three cathodes arranged next to one another and arranged in one plane. The grid arrangement upstream of the cathode arrangement in the direction of the screen is usually formed by four grid electrodes spaced apart from one another. The grid closest to the cathode arrangement is called grid 1 or control grid. The grid 2, which is also called the screen grid, connects to the grid 1 in the direction of the screen. The combination of cathode, control grid and screen grid forms the so-called triode lens. Towards the screen connects Grid 2 the grid 3 electrode, which consists of four cup-shaped electrodes, two of which are each connected to their free edge and thereby form a cup-shaped electrode. The next electrode to the screen is the 4-electrode grid. The grid 3 and grid 4 electrodes form the focusing lens of the system. Typically, each electrode has three openings arranged next to one another, arranged in one plane and aligned with the cathodes, through which the electrons emitted by the cathodes pass in the direction of the screen. The openings in the grids 1 to 4, which are located in front of the central cathode, are aligned centrally to the tube axis. The openings in the grids 1 to 4, through which the electron beams emitted by the respective outer cathode pass, are — as explained in more detail below — also aligned with the central grid openings.

Before the orientation of the outer lattice openings to the respective middle lattice opening is discussed in more detail for the various lattices, the concept of the s-spacing should be explained for better understanding. This is understood to mean the lateral distance that a center line placed through an outer grid opening to the tube axis (Z), i.e. to a center line through the center opening of this grid.

According to the prior art, the s distances in the grids 1 to 3 are chosen to be the same size. As a result, the electron beams, which are emitted by the two outer cathodes, have the same distance from the middle one, at least according to theoretical considerations, on their way through the grids 1 to 3 Electron beam. The s-spacing, which is predominant between the central opening and the respective outer opening in grating 4, is greater than the s-spacing between the center openings and the outer openings of grating 1 to 3. This causes that at the transition of the two outer rays of grating 3 in grid 4 these are broken. The result is that the two outer beams are brought to convergence with the center beam at a point on the tube axis (Z).

The in-line beam system described above is used in the neck of the picture tube. The cathodes and the grids are contacted via contact pins, which are melted through the glass in the neck area of the picture tube. The so-called cone connects to the neck of the picture tube and then the screen. In the transition area from the neck to the cone, the deflection arrangement is attached to the outside of the picture tube, which causes the three electron beams generated by the beam system to be deflected via the screen. For in-line beam systems, a self-converging deflection system is usually used for this. This is understood to mean an arrangement which ensures that the convergence points are always on the screen both when the electron beams are deflected vertically and horizontally. In general, it can be said that self-convergence is achieved by exposing the electron beams to a predominantly barrel-shaped deflection field for the vertical direction and to a predominantly pillow-shaped deflection field for the deflection in the horizontal direction. Further details can be found in R. Mäusl, Fernsehtechnik, Hütig-Verlag, 1991, page 173 et seq., And B. Brown, Die self-converging Deflection series FTX, Funk-Technik 1976, page 764 ff.

An ideal system, i.e. a system, which has no assembly errors due to manufacturing tolerances, has a focusing voltage (also called grid 3 voltage) at a certain anode voltage, in which the spots on the screen are optimally focused visually. This focus voltage is called the optimal focus voltage and is used for a large number of tubes of this type of tube as a setting voltage for the convergence setting. Depending on the design of the electron beam system, the optimal focus voltage is approx. 25 to 35% of the anode voltage.

In terms of production technology, the convergence of the picture tube is set by magnetizing internal or external multipoles. Corresponding to the tube type to be set in each case, the anode voltage is applied to grid 4 and the optimal focus voltage which is decisive for this tube type but is only valid for a system free from structural errors. When the convergence setting is complete, the two outer beams are bent at the same angle in the direction of the center beam.

However, if a system has defects based on manufacturing tolerances, for example, a triode grid is offset horizontally, the electron beams no longer pass through the center of the main lens. The consequence of this is that the vertical beams receive a one-sided halo insert as a result of the spherical aberration of the main lens. These halo inserts can be eliminated that the voltage swing described in the last paragraph between the optimal focus voltage and the anode voltage is changed by "turning" the halo inserts by increasing the focus voltage. This weakening of the main lens effect, which is caused by an increase in the focus voltage, leads to the fact that the external beams are bent less strongly in the direction of the central beam in comparison with the example in the last paragraph and thus show a convergence error in a tube which has already been set. It is also known to reduce the focus voltage based on the voltage conditions described in the last paragraph. This measure is taken if, due to manufacturing tolerances, the design grid spacing or opening diameter is not maintained. For example, if the grating distance between grating 2 and grating 3 is too small, the effect of the grating 2/3 lens is increased. In order to normalize the effect of this lens, the focus voltage must be reduced. This also causes a convergence error, since this measure increases the effect of the main lens and, as a result, the outer beams are bent towards the center beam to a greater extent than is the case with optimum focus voltage.

The influence that the increase or decrease in the grid 3 voltage has on the convergence is referred to as grid 3 convergence running.

This grid 3 convergence run is extremely disadvantageous because it prevents a tube that is set under the effect of the optimal focus voltage that is only valid for the respective tube type, in terms of sharpness and convergence, from an optimal setting is received if the system has an assembly error. If it turns out after the convergence has been set that the respective tube is afflicted with an assembly error in the system, such an assembly error, which is unavoidable in current production, can only be reduced by modifying the grids with regard to sharpness and convergence 3 Voltage a compromise setting is made.

If vertical bars are generated on the screen by means of a previously described arrangement, it is striking that the vertical bars of the color red are deflected in the 3 ° range of the picture tube when the electron beams are deflected compared to a deflection in the 9 ° range of the picture tube by 20 to 30 % are wider. For the color blue, the relationships are exactly the opposite, i.e. The vertical bars of the color blue are also 20 to 30% wider in the 9 ° range than in the 3 ° range of the picture tube.

For the sake of clarity, it should be pointed out that the 9 ° range of the picture tube is the edge of the screen which is closest in the x direction to the electron beam gun which produces the color blue on the screen. The 3 ° -range is the edge of the picture tube which is closest to the color red in the x-direction of the electron beam gun. In general, it can be said that with (horizontal) deflection of the electron beams in the x-direction, the respective external beam of an in-line beam system which is spatially closest to the edge of the picture tube to which the horizontal deflection is performed, in comparison to a horizontal one Distraction to the other edge of the picture tube on the screen produces about 20-30% wider vertical bars. For the For reasons of clarity, however, registration is assumed that the external rays of the system generate the electron rays for the colors red and blue.

The causes of this inhomogeneity in the width of the vertical bars in the colors red and blue are largely known. One cause is that a predominantly pillow-shaped magnetic field for the horizontal deflection of the electron beams increases in strength from the inside, ie from the center of the tube to the outside. In addition, the electrons receive horizontal magnetic field components when deflected horizontally by this field. Another reason for the different vertical bar widths of the colors red and blue is the influence of the deflection stray field. The influence of this stray field prevents the electron beams from crossing the main lens (transition from grating 3 to grating 4) in the middle. If the electron beams are now deflected into the 3 ° range of the screen, the red-colored spots are strongly distorted in the horizontal direction and over-focused in the vertical direction. The consequences are the wide vertical bars of the color red that have already been mentioned in this area. The extent of the distortion of the red spot depends on the amount of the additional components of the pillow-shaped deflection field and on the amount of the displacement of the electron beams in the main lens by the deflection stray field. The electron beam of the color blue is less distorted in the horizontal direction when deflected into the 3 ° range of the picture tube and underfocused in the vertical direction. This results in narrow vertical bars of blue in the 3 ° range. When the electron beams are deflected into the 9 ° range, they are The proportions of the vertical bar widths are reversed accordingly, i.e. in the 9 ° range the vertical bars of red are narrower and those of blue are wider.

The invention is therefore based on the object of specifying an electron gun system for picture tubes which eliminates the 3-convergence grid and produces extensively homogenized Verkialbalken for the colors red and blue in the 3 o'clock and 9 o'clock (deflection) range .

Presentation of the invention

This object is achieved according to claim 1 in that the s-spacing in the lower part of grid 3 is greater than the s-spacing of grid 1 and grid 2 and smaller than the s-spacing of grid 4 and that the s-spacing of the upper grid part of grid 3 is equal to the s-spacing of grid 1 and grid 2. By increasing the s-distance in the lower part of grid 3 it is achieved that the electron beams of the colors red and blue are additionally bent towards the center beam when grid 2 passes into the lower part of grid 3.

By increasing the s-spacing in the lower part of the grid 3, the grid 3 convergence running which occurs with the modification of the grid 3 voltage is eliminated. If the grating 3 voltage is increased, the effect of the pre-focusing lens formed between grating 2 and grating 3 lower part increases and the effect of the main lens between grating 3 upper part and grating 4 decreases. This means that compared to an unchanged grid 3 voltage, the outer rays in the area between grid 2 and grid 3 lower part stronger and weaker in the main lens. In contrast, when the grid 3 voltage is reduced, the effect of the pre-focusing lens decreases and the effect of the main lens increases. This means that compared to an unchanged grating 3 voltage, the outer rays in the area between grating 2 and grating 3 lower part are weaker and broken more in the main lens. A shift of the convergence point on the tube axis (Z) is not associated with a modification of the grid 3 voltage if the change in the grid 3 voltage is within the limits according to claim 3. This is due to the fact that the modification of the refraction in the pre-focusing lens caused by a changed grating 3 voltage is quasi reset by a weaker or stronger refraction in the main lens with respect to the convergence point. This independence of the convergence, given the limits of claim 3, from a modification of the grid 3 voltage is of particular interest with regard to tubes which are set in relation to the convergence when an optimal focus voltage which is valid for the respective tube type is effective and which have a manufacturing-related assembly error in the blasting system. If tubes of this type are designed in accordance with the invention, the loss of sharpness caused by the construction errors can be eliminated by modifying the grid 3 voltage, without the convergence setting being changed by this measure.

In addition to eliminating grid 3 convergence running, the width of the vertical bars in the 3 ° and 9 ° range of the colors red and blue is largely homogenized. If the electron beams are deflected into the 3 ° range, the electron beam of the color red becomes effective the pre-focusing lens is "pre-bent" in a direction opposite to the deflection direction. A central crossing of this electron beam through the main lens can thus be achieved by superimposing the deflector stray field. This reduces the spherical aberration of the main lens and reduces the "deflection-related" influences that are otherwise responsible for the wide vertical bars in this deflection area. When the electron beams of the color blue are deflected into the 3 ° range, there is a positive superimposition of the effect of the deflecting stray field and the effect by the pre-focusing lens. In summary, it can be said that when the electron beams are deflected into the 3 ° range, the width (seen in the x direction) of the red beam is reduced and that of the blue beam is slightly increased.

When the electron beams are deflected into the 9 ° range of the picture tube, the situation is reversed accordingly.

Advantageous effects of the electron gun system set out in claim 1 can be achieved if, according to claim 2, the s-spacing of the lower part of grid 3 is increased by up to 40 µm compared to the s-spacing of grid 2.

] im Spannungsbereich zwischen ± 800 V gegen ein Gitter 3-Konvergenzlaufen resistent. Unter einer optimalen Gitter 3-Spannung (U_G3opt) wird eine solche verstanden, bei der die Elektronenstrahlen eines aufbaufehlerfreien System auf dem Bildschirm visuell optimal fokussiert sind. Diese optimale Gitter 3-Spannung oder Fokusspannung ist designabhängig und beträgt herkömmlich ca. 25 -35% der Anodenspannung (U_A).An electron gun system according to the invention is based on an optimal 3-voltage grid [ ${\text{U}}_{\text{G3opt}}{\text{= (0.30 ± 0.05) U}}_{\text{A)}}$

] resistant to a grid 3 convergence in the voltage range between ± 800 V. An optimal grid 3 voltage (U _G3opt ) is understood to be one in which the electron beams of a system free of defects on the screen are optimally focused visually. This optimal grid 3 voltage or focus voltage depends on the design and is conventionally approx. 25 -35% of the anode voltage (U _A ).

Brief presentation of the figures

Figur 1

eine Draufsicht auf eine Bildröhre;

Figur 2

ein Elektronenstrahlerzeugersystem; und

Figur 3

eine schematische Darstellung eines Elektronenstrahlerzeugersystems.

Show it:

Figure 1

a plan view of a picture tube;

Figure 2

an electron gun system; and

Figure 3

is a schematic representation of an electron gun system.

Ways of Carrying Out the Invention

The invention will now be explained in more detail with reference to the figures.

1 shows a picture tube 10. This picture tube 10 is formed by the screen 11, the cone 12 and the neck 13. In the neck 13 there is an in-line beam system 14 (shown in broken lines) which generates three electron beams (R, G, B). A magnetic deflection system 15 is attached to the transition from the neck 13 to the cone 12. This deflection system 15 deflects the electron beams (R, G, B) over the surface of the screen 11. For the horizontal deflection of the electron beams (R ', G', B ') this is indicated schematically by the broken line. It can be clearly seen from FIG. 1 that the outer electron beams (B, B 'and R, R') do not run parallel to the center beam (G, G '), but instead take an angle with the center beams (G, G'). With the lines Z, which are shown on the right and left of the picture tube according to FIG. 1, the tube axis is illustrated. If the middle electron beam (G) is not influenced by the deflection system 15, this electron beam (G) runs on the tube axis (Z). The line shown to the left of the picture tube according to FIG. 1 and designated x is the so-called x-axis of the picture tube, along which the electron beams are deflected by the deflection system 15 during horizontal deflection.

For the sake of completeness, it should be pointed out that the vertical deflection of the electron beams (R, G, B) takes place perpendicular to the plane of the paper. The deflection system 15 generates over its overall length L a predominantly "barrel-shaped" field line course for the vertical deflection and a predominantly "pillow-shaped" field line course for the horizontal deflection. The deflection system 15 is therefore a self-converging system.

FIG. 2 shows a top view of an in-line jet generator system. The in-line jet generator system 14 has a pressed glass plate 16, in which contact pins 17 are melted. The grid electrodes 18, 19, focusing electrodes 20, 21 and the convergence pot 22 adjoin this. The cathodes 23R, 23G, 23B, which are shown only schematically and in broken lines, are arranged within the grid electrodes. The control grid electrode 18 is the Grid electrode 1 and the screen grid electrode 19 the grid electrode 2. The focusing electrodes 20, 21 form the focusing lens. The individual parts of the in-line beam generator system 14 are held together by two glass rods 24.

The focusing electrode 20, which is also called a grating 3, consists of four cup-shaped electrodes 20.1 to 20.4, of which two electrodes are connected to one another by their free edge and thereby form a cup-shaped electrode. In all electrodes of the in-line beam generator system 14, three openings (arranged in greater detail with FIG. 3) are arranged through which the electron beams (R, G, B) generated by the three cathodes 23 pass and - as shown in FIG. 1 - Impact on the phosphor layer 25 applied to the inside of the screen 11. The tube axis Z is also shown in FIG. 2 by the lines indicated above and below the jet generator system. The dash-dotted arrows indicated above the convergence pot 22 illustrate that the central electron beam G runs on the tube axis Z and the two outer beams R, B run at an angle to the center beam G.

For the sake of completeness, it should be pointed out that the center beam G, which excites the green phosphor 25 on the screen 11 in the exemplary embodiments shown here, need not necessarily be used to excite the green phosphor 25. Rather, in another embodiment (not shown), the cathode assignment can be selected as it is in connection with another application filed under an earlier filing date the applicant is described.

In Figure 3, an in-line jet generator system 14 is shown schematically in plan view. The three cathodes 23R, 23G, 23B are arranged on the left side of FIG. Spaced from the cathodes 23R, 23G, 23B is first the grid 1 (18), then the grid 2 (19), then the focusing electrode 20 and then the grid 4 (21). Of the grid 3 electrode 20, only the grid 3 lower part 20.1 and the grid 3 upper part 20.4 are shown. Openings 27R, 27G, 27B are arranged in the electrodes 18 and 19 centrally to the cathodes 23R, 23G, 23B. The s-distances (A1) of the centers of the openings 27R to the centers of the openings 27G and the centers of the openings 27B to the centers of the openings 27G are the same and are 6.6 mm in the exemplary embodiment shown. The other electrodes 20 (20.1 and 20.4), 21 also have openings, which are designated 28 in FIG. The openings 28G, like the openings 27G, are aligned centrally to the cathode 23G or to the tube axis Z. With increasing distance of the openings 28 arranged in the grids 20 (20.1 and 20.4), 21 from the cathodes 23, these openings 28 have increasing cross sections. The opening cross sections in each individual grating 18 to 21 are of the same size for the different electron beams R, G, B. In this context, it is pointed out that in another embodiment (not shown), the opening cross sections per grating for the different electron beams can be of different sizes.

To better emphasize the invention in FIG. 3, the arrangement of a beam system 14 according to the invention is illustrated only for the external beam R, while the outer beam B shows an arrangement according to the prior art. In the inventive as well as in the system according to the prior art, the grating opening arrangement for the center beam G is the same.

As FIG. 3 further clarifies, the s spacings (A2R, A2B) in the lower part 20.1 of grid 3 (20) for the electron beams R and B are different in size. In the exemplary embodiment shown here, the s-distance (A2R) is 6.62 mm and the s-distance (A2B) as well as the s-distance (A1) is 6.6 mm. The s-distance (A3) in the upper part 20.4 of grid 3 (20) is the same for both the electron beam (R) and for the electron beam (B) and, like the s-distance (A1), is 6.6 mm. With (A4) the s-distance in grid 4 (21) is designated. It is 6.785 mm for the electron beam (R) and for the electron beam (B).

Due to these geometric conditions in the grid openings, an electron beam B emitted by the cathode 23B according to the prior art with a given grid 3 and grid 4 voltage in the transition from the upper part 20.4 of the grid 3 (20) to the grid 4 (21) corresponds to the solid line (B) bent towards the center beam (G). In this case, the grid 3 voltage is the focus voltage (U _G3opt ) that has been visually determined for this system or this tube type and is regarded as optimal.

If there are individual assembly errors in the system due to manufacturing tolerances or grid spacings or hole diameters not in accordance with the design in the triode area (not shown), then the grating 3 voltage is adjusted accordingly to the end setting of the tube in order to adjust the already mentioned compromise between sharpness and convergence. In the lower part of FIG. 3, the course of the blue electron beam according to the prior art is shown, the grating 3 (20) of which is subjected to a higher grating 3 voltage than the optimal focus voltage (U _G3opt ) for compromise adjustment. Because of the then smaller potential difference between grid 3 (20) and grid 4 (21), the electron beam (B) is bent less strongly in the transition region between the two grids in the direction of the center beam (G). This is indicated by the dashed line (B ''). By increasing the grid 3 voltage, the convergence of the beam (R) with the beam (G) can no longer be achieved at point (F), but only at point (F '). Convergence at point (F ') is the significant consequence of the grid 3 convergence run discussed earlier.

In the construction of the electron beam system 14 according to the invention, the electron beam (R) is not only in the transition from grid 3 [20 (20.4)] to grid 4 (21), but also in the transition from grid 2 (19) to grid 3 [20 (20.1 )] bent towards the center beam (G). This is achieved by increasing the s-spacing (A2R) in the lower part of grid 3 [20 (20.1)]. The remaining grid parts remain unchanged according to the prior art. This is shown for the course of the red electron beam in the upper part of FIG. 3. The solid course of the electron beam (R) is given when the grating 3 (20) has an optimal blue beam path (lower part of FIG 3) valid focus voltage (U _G3opt ) is applied. If the grid 3 voltage (U _G3opt ) which is optimal for this system is increased on the basis of this case, the effect of the pre-focusing lens 19, 20.1 is increased. This manifests itself in a stronger angling of the beam (R) in the transition area from grating 2 (19) to grating 3 [20 (20.1)] and is indicated in FIG. 3 by the dashed line (R ″). At the same time, the effect of the main lens (transition area from grating 3 20 (20.4) to grating 4 (21)) is weakened by increasing the grating 3 voltage. The latter is expressed in that the beam R ″ is angled less than the beam R in the direction of the center beam (G). The effect of the pre-focusing lens and the main lens in the beam path (R), despite the increase in the grating 3 voltage, means that the beam (R ″) at point (F) also converges with the center beam (G).

The relationships shown in the upper part of FIG. 3 for the increase in the grid 3 voltage apply in reverse for the decrease in the grid 3 voltage. In this case, the effect of the pre-focusing lens is weakened and the effect of the main lens is strengthened without a shift in the convergence point (F).

The independence of the grid 3 convergence run from an increase or decrease in the grid 3 voltage is given in a range of ± 800 volts based on the optimal grid 3 voltage (U _G3opt ). In the present exemplary embodiment, the optimal focus voltage (U _G3opt ) was approximately 8350 volts with an anode voltage (U _A ) of 28500 volts. The optimal focus voltage (U _G3opt ) was able to influence the convergence within a voltage range of ± 500 volts be modified.

The arrangement explained in this exemplary embodiment also showed for the colors blue and red in the 3 o'clock or. 9 o'clock deflection area, largely homogenized vertical beams.

Claims (3)

In-line beam system (14) for picture tubes (10), with a cathode arrangement which comprises three cathodes (23R, 23G, 23B) which are adjacent to one another and lie in one plane, - With electrode grids (18 - 21), which are each arranged at a distance from the cathode arrangement and which each have three mutually adjacent, arranged in one plane and aligned with the cathodes (23R, 23G, 23B), wherein at least the s distances (A 1) of grid 1 (18) and grid 2 (19) are the same size and the s distance (A 4) of grid 4 (21) is greater than the s distance (A 1) in grid 1 (18), and - With a self-converging deflection system (15), characterized by
that the s-distance (A 2) in the lower part (20.1) of grid 3 (20) is greater than the s-distance (A 1) in grid 1 (18) and smaller than the s-distance (A 4) in grid 4 (21) is and
that the s-distance (A 3) in the upper part (20.4) of grid 3 (20) is equal to the s-distance (A 1) in grid 1 (18). In-line blasting system according to claim 1,
characterized,
that the s-spacing (A 2) in the lower part (20.1) of grating 3 (20) is increased up to 40 µm compared to the s-spacing (A 1) in grating 2 (19). In-line blasting system according to claim 1 or claim 2,
characterized by
that the grid 3 voltage (U _G3 ) has a value that the formula

${\text{U}}_{\text{G3}}{\text{= U}}_{\text{A}}\text{(0.30 ± 0.05) ± 800 volts}$

follows and U _{A is} the anode voltage.

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