DE1918877A1 - Color picture tubes - Google Patents

Description

Color picture tube

The invention relates generally to multi-beam color picture tubes, and more particularly to tubes in which the various beams through the optical center of a common electron lens, through which the rays on the color phosphor screen are imaged, with coma errors and spherical aberration caused by the lens being eliminated will"

In multi-beam color picture tubes of this type, for example for the tube with a single electron gun as described in the pending U.S. application serial no. 697.414 of January 12, 1968 by the applicant of the present application are three with mutual lateral Electron beams extending at a distance are emitted or generated by a beam generator or a cathode arrangement and directed into a common, substantially horizontal or vertical plane, the central beam with the optical axis of the single electronic converging lens coincides, while the two outer rays converge be guided in such a way that they optimally

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see the center point of the lens intersect and look up out of the lens Paths emerge which lead away from the "optical" axis. Between the focusing lens and the fluorescent screen there is one Device for electrostatic convergence deflection arranged, of which the striving away from the optical axis Rays are deflected essentially in the plane of origin of the rays, so that all rays become one common Point on a beam selector device, such as a pinhole, converge, enforce this and then on assigned Falling color phosphors of a fluorescent screen. Between the converging lens and the beam selector (shadow mask) is exerted an influence on the rays by magnetic fields; the magnetic fields are created when horizontal and vertical sweep signals on a main deflection yoke, whereby the rays are caused to scan the phosphor screen in the required grid. The convergence deflector the said color picture tube expediently contains a first pair of spaced apart, interconnected plates between which the central beam passes, as well as a second pair of plates, the one outside of the former Plates is arranged so that the diverging rays pass between the first and second plates and are brought to convergence by deflection with the help of electric fields that arise between the plates, if there is a voltage on the first two plates and a different voltage on the two second plates is placed.

If the said convergence baffles are far away from the magnetic fields of the main deflection yoke, the neck part of the tubular piston becomes undesirably long and therefore requires a greater housing depth of the television receiver to accommodate the tube can. If on the other hand the neck portion of the tube is shortened, with the result that the convergence baffles near the main deflector range, a magnetic field of the yoke induces a current flow

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in the closed path by the interconnected first plates is formed, between which the central ray passes through, and such a current creates a magnetic field that deflects the central beam so that a exact convergence with the other two rays does not come about.

The invention is therefore intended to provide a multi-beam color picture tube of the type mentioned, in which the convergence baffles are in the vicinity of the Hauptablenkjochs or even overlap it axially so that the halo part of the tubular bulb is kept as short as possible, where, in addition, any convergence error resulting from the physical proximity between the convergence baffles and the main deflection yoke is avoided.

The convergence error that results from mutual proximity of convergence baffles and main deflection yoke would, is compensated according to the invention by the fact that the second or other baffles have other geometrical relationships than the associated first baffle plates, so that those arising between the first and second plates electrical fields exert unequal deflection effects on the rays passing through. The different ones mentioned Geometric relationships can also be given by different distances between the first and the second plates, which serve to deflect one of the divergent rays; and the first and second plates, which serve to deflect the other divergent beam so that the field strength in the two divergent beams fields traversed is different «The different geometrical relationships can also or express it exclusively in the fact that the second plates are different sizes in the longitudinal direction of the associated have first plates, so that the two divergent beams are different in the associated electric fields to travel long distances

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These and other features, special features and advantages of the The subject matter of the invention emerges from the following description of exemplary embodiments and the associated Drawings" .

Fig. 1 is a schematic section on a horizontal Plane passing through the axis of a single electron gun equipped multi-beam color picture tube runs;

FIG. 2 is a partial section through the same plane as in FIG. ₄ , 1, in which the construction of part of such a tube is shown, the piston neck length of which is to be reduced;

Fig. 3 shows a cross section along de? Line 3-3 in Figure 2 dar;

4 and 5 are partial sections showing the arrangement of the convergence baffles in a tube according to FIGS. 2 and Figures 3 and represent two embodiments of the invention to remove convergence errors.

1 shows a multi-beam color picture tube (10) equipped with a single electron gun, in which the principles of the invention can be applied; the stirrer has a glass bulb (not shown) as a neck part and a conical part running from the neck part to the fluorescent screen S; On the luminescent screen S there are the usual arrangements of color phosphors S _R , S ~ and S "as well as a radiation-separating pinhole arrangement or shadow mask Gp. Inside the neck part is the individual electron gun A with the cathodes K _R , K" and K _g are formed by a beam generating source, the beam generating surfaces of which, as can be seen, lie in a plane which is essentially perpendicular to the axis of the electron gun. The beam-generating surfaces are arranged along a straight line, so that the beams B _R , Bq and Bg emitted by them in a substantially horizontal or

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otherwise common plane containing the axis of the electron gun, the communication beam Bg coinciding with this axis. A first grid G. stands at a distance from the beam generating surfaces of the cathodes IC "K" and Kg and has openings _{g 1R} , g _1G and g 1ßf which lie in the grid in alignment with the associated beam generating _{surfaces of the cathode} grid G _2, the distance from the first grid G "is arranged are openings ^ 2R * & 2G ¹ ^ ^ 2B ^{8 esenen"} are aligned with the corresponding apertures of the grid G. ₁ in the axial direction of the usual grid G offset tubular grids or electrodes G ₃ or G ^ or Gg are provided, the cathodes K _R , Kq and K ₈ , the grids G. and G ₂ and the electrodes G ₃ , G4 and Gg in the arrangement shown with not shown Brackets made of insulation material are mounted.

For the operation of the electron gun according to FIG. 1, the grids G 1 and G and the electrodes G ₃ , G and G _{5 are} supplied with suitable voltages. For example, the grid G ^ receives a voltage between 0 and -400 V, the grid G ₂ 0 to 500 V, the electrode G ₃ and the electrode G ₅ a voltage between 13 and 20 kV and the electrode Gj a voltage from 0 to 400 V, whereby all voltages are based on the cathode voltage as a reference value. Accordingly, the voltage distributions between the respective electrodes and cathodes and their lengths and diameters can be essentially the same as in a single-potential single-beam electron gun, which consists of a single cathode and a first and a second grid with a single opening.

With the voltage distribution given above, an electron lens field arises between the grid G ₂ and the electrode G ₃ and forms an auxiliary lens L ¹ drawn in dashed lines, and an electron lens field is produced around the axis of the electrode G ₄ by the electrodes G ₃ , G ₄ and G ₅ , which forms a main converging lens L, which is also shown in dashed lines

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is drawn. In a typical application of an electron gun A, bias voltages of 100 V or 0 V or 300 V or 20 kV or 200 V or 20 V are applied to the cathodes K _R or Kg or Kg or the first grid G ₁ or the second grid G2 or the electrodes G, or G. or G ₅ , respectively.

The electron gun according to FIG. 1 also includes auxiliary devices F for the converging deflection of electron beams; These devices comprise a first pair of shielding ^{plates P and P 1} , which are attached at a distance on either side of the axis of the electron gun, and a second pair of P axially extending deflector plates Q and Q ¹ , which, as can be seen from the drawing, the shielding plates P. and P ¹ face each other on their outsides. In the drawing, these plates are indicated in a straight line, but the deflection plates Q and Q ¹ , as is known per se, can also be designed to be slightly curved or bent outwards.

The shielding plates P and P * are equally charged and arranged in the same way, so that the central electron beam Β _β passes practically undeflected between the shielding plates P and P ^1; the deflection plates Q and Q *, however, are negatively charged to the plates P and P *, so that the electron beams E _ß and B _{R concerned are} deflected in a converging manner, as shown in the drawing at the corresponding points in the area between the plates P and Q or P ¹ and Q * is indicated. _{Specifically, a voltage V p} equal to the voltage applied to the electrode Gg can be applied to the two shielding plates P and P * _{, and a voltage V Q lower than V p} by about 200 to 300 V can be applied the associated baffles Q and Q 'are laid; this brings the shielding plates P and P 'to the same potential, and deflection or convergence voltages arise between the plates P * and Q * and the plates P and Q, and the deflection or convergence voltage VC generates electric fields that provide the deflection required for the Bring convergence of B ″ and B ″.

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When the tube is in operation, the electron beams B _R , Bg and B_, which emanate from the beam-emitting surfaces K _R , K "and K _{B of} the cathode, run through the associated grid openings g _1R , g _1G and g- _B and are brightly controlled with red, Green and blue light control signals fed between the cathodes and the first grid G ... The respective electron beams then pass through the common auxiliary lens L ¹ and overlap in the center of the main lens L, from where they continue as beams B _R and B "diverging from beam B '. The middle electron beam Bg then continues practically undeflected between the shielding ^{plates P and P 1} , because these two plates have the same potential. The electron beam B i passing between the plates P ^{1 and Q 1} _{and the electron beam B R} passing between the plates P and Q are deflected to convergence due to the convergence deflection voltage existing between these plates, and the system shown in FIG. 1 is intended to be so designed that the electron beams B _ß , B ^ and Bp converge as desired or intersect at a common point which _{lies in an opening of the shadow mask G p} , and diverge from there and fall on the respective color phosphors of a fluorescent screen arrangement S. The fluorescent colored screen S consists of a large number of groups of vertically running red, green and blue fluorescent strips or spots S _R , S 1 and S ~, each group of color phosphors representing a color image element. The common point of convergence of the penalties corresponds to one of the resulting color picture elements

Electron beam scanning of the surface of the color phosphor screen is effected by horizontal and vertical deflection yokes D, which receive horizontal and vertical sweep signals, creating a color image on the color screen. As with this structure each electron beam for focusing by the center of the main lens L of the electron gun A is guided, are those by the impingement of the rays on the fluorescent screen S resulting beam spots are practically free of coma

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and / or astigmatism errors of the main lens, whereby a better color image resolution can be achieved »

In FIGS. 2 and 3, one possibility for assembling the tube shown schematically in FIG. 1 is shown; the plates P and P ¹ can then be held at their ends closest to the electrode G ^ by angle pieces 12 and 13, .the sit on a flange 11 at the adjacent end of a tubular extension of the electrode G ₅ , which in turn in the tube neck N by insulating washers 24 and 25 is supported, between which getter rings 22 and 23 are attached at a suitable point. The j) front ends of the plates P and P * are connected on their sides by clamp elements 21 extending between them. The voltage VP is supplied to the plates P and P * by a contact spring 18 which leads from one of the clamp elements 21 to a conductive layer 17 which is attached to the inside of the cone part C of the tube piston and extends into the adjacent neck part. The voltage Vp is applied to the layer via a (not shown) anode button in the funnel portion C and to the electrode G ₅ of the plates P and P * over, the angle pieces, the voltage Vp 12 and 13 from the electrode G ₅ from be transferred to the electrode G ^ by means of a conductor not shown. The layer 17 also brings the voltage Vp as anode voltage to the shadow mask G _p .

Pins 14 run outward from the plates P and P * and have glass beads IS at their outer ends, by means of which the plates Q and Q 'are held and at the same time insulated from the plates P and P'. The voltage Vq is transmitted to the plate Q through a conductor 20 starting from a button 19 in the neck portion N and through a conductor 16 which runs between the plates Q and Q 'and is spaced from the plates P and P ¹ the plate Q ¹ .

In order to keep the neck part N of the tube piston as short as possible, the convergence deflector F is close to the main deflector yoke D arranged; the two bodies can join

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even, as shown in Fig. 2, overlap in the axial direction. However, when the convergence deflector F is arranged in this way, it lies within the magnetic field, the vertical field lines of which are generated by the main deflection yoke D so that the rays can scan the phosphor screen in the horizontal direction. The plate P, the clamp elements 21, plate P ', angle parts 12, 13 and the electrode G ₅ together form a closed circuit, and the induction flux changes in the magnetic field of the yoke D cause a current to flow in the closed circuit; the induced current in turn creates a magnetic field between the plates P and P ¹ which acts on the central beam B- in a direction opposite to the horizontal scanning movement of the beams. Since the magnetic field resulting from the induced current between the plates P and P * has no influence on the other beams Bp and B _B, the point at which the beam Bg reaches the shadow mask Gp suffers a delay at every moment during a horizontal scanning movement with respect to the point on the shadow mask at which the two rays B _R and B _ß converge; this creates poor convergence.

According to the invention, this defective convergence is avoided or corrected in that the. Convergence * deflection plates Q and Q * have different geometrical positions compared to the associated shielding plates P and P *, so that the electric fields between the plates P and Q or the plates P * and Q ^{1 have} different deflecting effects on the beams B ₆ and * Bp exercise, whereby the rays can clear the shadow mask in the same point as the ray B _Q , in spite of the fact that the rays B _R and B _{ß are} not exposed to the magnetic field between the plates P and P * during the HoTizontal scan the central jet B _Q acts *

In Fig. 4 it is shown how the different geometric relationships between the plates Q, Q * and the

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Plates P, P 'can be expressed by the distances that ■ the plates Q and P or, Q ^a and P ^{1 have} from one another. According to FIG. 4, the distance d between the plates P and Q is greater than the distance d ^f between the plates E ¹ and Q ¹ ; It follows that the strength of the electric field between the plates P ¹ and Q ¹ and therefore the deflecting force acting on the beam B _{R is} greater than the field strength between the plates P and Q and thus the strength of the deflecting force acting _{on the beam B ß} The convergence deflection of the beam B _R will therefore be greater than the convergence deflection of the beam B _ß , so that the rays B _R and B _ß converge together with the beam B _fi at a common point on the shadow mask «

5 shows that the geometrically different relationships mentioned on the plates Q, Q ¹ and P, P * can also relate to the lengths over which the plates P, P 'or «Q, Q * extend. According to FIG. 5, the plate Q has a length 1 in the direction of the tube axis which is less than the corresponding length extension 1 'of the plate Q *. Correspondingly, the beam B _{ß runs} a longer distance within the electric field between the plates P and Q than the beam B, when this passes through the electric field between the plates P * and Q '. Again, the convergence deflection of the beam B _{R is} greater than the convergence deflection of the beam Β _β , so that exact convergence of the three rays Bg, Bg and B _{ß is achieved} at a common point on the shadow mask «

Of course, the measures according to the invention, which are shown individually in FIGS. 4 and 5, can be combined, so fc * nn e.g. the plate Q is placed at a greater distance from the plate P than the plate Q * from the plate. P * has, and the plate Q can be made shorter than the plate Q *.

The foregoing are certain embodiments of the invention

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described and drawn in detail; Of course, the invention is not limited to this embodiment. forms limited * Rather, various changes and modifications are possible within the scope of the professional Can lie and not go beyond the scope of the invention.

Patent claims:

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Claims (1)

P a t en ta η s ρ r ü c h e . • / Multi-beam color picture tube, with a fluorescent screen (S) with groups of color phosphors and these associated openings of a shadow mask (Gp), with beam generating _{devices (A) 1} which direct a number of electron beams (B) against the fluorescent screen (S) so that they fall onto the respective screen points through the associated openings, old an imaging system (L) that images the electron beams (B) on the luminescent screen (S) and has an optical center through which all electron beams (B) run, whereby a beam ( Bg) runs along the optical axis of the lens system (L), while the other two beams (B _R , Bg) hit the axis form an angle and diverge away from the lens (L), with one converging the electron beams (B) deflecting system (F) between the lens (L) and the shadow mask (G _p ) for deflecting the two rays (B _ß , B _R ), which run on the diverging paths, so that convergence of all rays (B) at a the opening of the shadow mask occurs, and with a system of magnetic yokes (D) between the lens (L) and the shadow mask (Gp), a magnetic field is generated through which the rays (B) are simultaneously deflected onto the shadow mask (Gp), characterized in that the convergence deflection system (F) has a first, interconnected, spaced-apart pair of plates (P, P *) so that one (Bq) of the electron beams can pass between the plates, that one at a distance from the first pair of plates (P, P ¹ ) arranged outside this pair of plates (Q, Q *) is provided so that a beam of the other two electron beams (B _R , B _ß ) between 909845/1057 a first plate CP) and a second plate (Q) passes through, and that a first voltage (V _p ) to the first _{pair of plates (P 1} P ¹ ) and a different second voltage (Vq) to the second pair of plates (Q, Q ¹ ) can be laid, so that the voltage difference between the first plates (P, P ¹ ) and the second plates (Q, Q ¹ ) creates electrical fields between the plates, which cause the convergence of the rays (B), the convergence - Deflection system (F) is arranged close to the magnetic yokes (D) in order to reduce the required tube length, whereby the magnetic field of the yokes (D) causes a current to flow in the interconnected first plates (P, P ') and a magnetic field between them generated, which acts on the one beam (Bg) and causes a deficient convergence of the beams (B), and the defective convergence is eliminated by the fact that different geometrical relationships between the second plates (Q, Q ') and the first plates (P 'P' ) so that the electric fields cause unequal deflection effects on the two tin electron beams (B _R , B _ß ) and restore the convergence of these beams with the one beam (Bg) 2, multi-beam color picture tube according to claim 1, characterized in that the second plates (Q, Q ') have unequal distances from the first plates (P, P ¹ ), so that the electric fields have unequal field strengths. 3. Multi-beam color picture tube according to claim 1, characterized in that the second plates (Q, Q *) in the direction of the electron beams (B) passing between them have a different extent than the associated first plates (P, P ¹ ), so that the two electron beams (B _R , B ₈ ) differently large distances through the assigned 909845/1067 arranged electric fields through it. 4 · multi-beam color picture tube according to claim 1, characterized in, that the convergence deflection system (F) and the magnetic yokes (D) each other in the direction of the tube axis overlap. The patent attorney • 09845/1057