JPH0640469B2 - Color picture tube electron gun - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to the shape of electrodes constituting a main lens of an electron gun for a color picture tube.

[Background of the Invention]

FIG. 1 is a plan view of a color picture tube provided with an electron gun having a conventional structure. A phosphor screen 3 on which phosphors of three colors are alternately coated is supported by the inner surface of the face plate portion 2 of the glass envelope 1. Central axes 17, 18, 19 of cathodes 6, 7, 8
Is the G1 electrode 9, the G2 electrode 10 and the G constituting the main lens.
3 electrodes 11, G4 electrode 12, G5 electrode 13, G6 electrode 1
4 and the shielding cup 15 are aligned with the communication axes of the openings corresponding to the respective cathodes and are arranged substantially parallel to each other on a common plane. The central axis 18 is also the central axis of the electron gun assembly itself. Hereinafter, the direction along the common plane will be referred to as the horizontal direction. Of the cylindrical parts protruding inward from the openings of the G5 electrode 13 and the G6 electrode 14, the ends of the cylindrical parts arranged outward are inclined with respect to the central axes 17 and 19. .

The three electron beams emitted from each cathode have a central axis 1
The light enters the main lens along 7, 18, and 19. In the example of FIG. 1, the main lens is a so-called Uni-Potential Focusing electron lens formed by G3, G4, G5 electrodes, that is, a UPF lens, and a so-called Bi-Potential Focusing electron lens formed by G5, G6 electrodes, that is, It is composed of a combination of two electron lenses of a BPF lens. The G6 electrode 14 has the same potential as the shielding cup 15 and the conductive film 5 provided inside the glass envelope, and is supplied with a high voltage of about 20 to 30 KV. G
A focusing voltage of about 5 to 9 KV is applied to the 3, G5 electrodes. The G4 electrode is provided with two types of configurations: a case where a high potential common to the G6 electrode is applied and a case where a low potential of about 400 to 1000 V, which is almost the same as the G2 electrode, is applied. The electron beam incident on the main lens is focused by the two electron lenses. Since the main lens is formed in axial symmetry with respect to the central beam incident along the central axis 18, the central beam is focused by the main lens and then travels straight along the trajectory along the central axis 18. On the other hand, of the electron lenses forming the main lens formed along the outer central axes 17 and 19, the BPF formed by the G5 and G6 electrodes.
Since the end surface of the cylindrical portion of the lens is inclined,
The electron beam can be focused and deflected at the same time, as shown at −63750. Thus, the outer beam incident on the main lens along the outer central axes 17, 19 is focused by the main lens and at the same time concentrated in the central beam direction. As described above, the three electron beams form an image on the shadow mask 4 and are concentrated so as to overlap each other. The operation of concentrating each electron beam in this way is called static convergence (hereinafter abbreviated as STC).
Each electron beam is subjected to color selection by a shadow mask, and only the component that excites and emits the phosphor of the corresponding color passes through the aperture of the shadow mask and reaches the phosphor screen. In addition, an external magnetic deflection yoke 16 is provided to detect the electron beam on the fluorescent screen.

In the method shown in FIG. 1, the deflection amount of the outer electron beam is
It increases as the inclination angle of the end surface of the electrode cylindrical portion increases. In order to increase the inclination angle, it is necessary to increase the maximum value of the length of the cylindrical portion and keep the minimum value low. However, due to electrode manufacturing problems, the maximum value is 50
% Is the upper limit, and the above minimum is the electrode thickness.
A value about 2.5 times is the lower limit. Therefore, when using a metal plate of approximately the same thickness in the production of electrodes, the above maximum value decreases as the main lens aperture decreases, while
Since the minimum value remains constant, the angle of inclination of the end face of the cylinder portion decreases. As a result, the amount of deflection of the outer electron beam decreases, and ST
The problem that C cannot be taken occurs.

In order to solve this problem, not only the BPF lens portion but also the UPF lens portion formed by the G3, G4 and G5 electrodes has a non-axisymmetric structure to give a deflection force to the electron beam and compensate for the shortage of the deflection amount. That method is possible.

FIG. 2 shows an example in which the UPF lens portion has a non-axisymmetric structure disclosed in Japanese Patent Application Laid-Open No. 52-32714 and a deflection force is applied to the electron beam. That is, a pair of electrodes G
Of G3 and G4, the central axis of the G4 electrode opening, which is located on the phosphor screen side, is slightly deviated to the outside with respect to the central axis of the G3 electrode opening. Is biased to. Here, in order to fix all the electrode apertures with a cylindrical jig inserted from the G6 electrode side, the aperture diameter on the phosphor screen side of the adjacent electrode apertures is compared to the other aperture diameter. It is combined so that it does not become small. Further, a high voltage V ₀ common to the G6 electrode is applied to the G4 electrode, and a focusing voltage V _f lower than this is applied to the G3 and G5 electrodes.

However, in such a structure, the following problems still occur. That is, since the central axis 20 of the outer electron beam shown in FIG. 2 is deflected in the direction of the central axis 18, the outer electron beam is particularly deflected outwardly by the electrode 12 whose central axis is displaced.
It will pass through a portion largely deviated from the central axis of the opening. For this reason, the outer electron beam receives different focusing powers from the central axis 20 between the central beam side portion and the other side portion, so that a spot having a distorted shape is formed on the fluorescent screen.

FIG. 3 shows an outline of the spot shape at this time. Both sides of the central beam spot 30 have outer beam spot shapes 3
1, 31 '. The shaded area is a high-intensity area called the core, and the surrounding area is a low-intensity area called halo. In particular, the horizontal spread of the halo becomes remarkable, which deteriorates the vertical resolution of the color picture tube.

The same problem as described above occurs with respect to the main lens having a configuration in which the G4 electrode 12 is provided with substantially the same potential as the G2 electrode. At this time, according to the method of Japanese Examined Patent Publication No. 52-32714, the central axis of the outer opening of the G5 electrode 13 on the G4 electrode 12 side must be displaced to the outside as compared with the outer opening of the G4 electrode 12. I won't. Even with this configuration, the outer electron beam is G
Since it passes through a portion largely deviated inward from the central axis of the G4 electrode side opening of the five electrodes, the shape of the screen spot is distorted similarly to that shown in FIG.

Thus, the method of deflecting the electron beam in two steps is
As shown in JP-A-55-53853, when the G4 electrode potential is lower than the G3 and G5 electrode potentials, V _f
It may be used for the purpose of preventing the variation of the electron beam deviation amount with respect to the electron beam. In this case, the electron beam may be deflected between the G5 and G6 electrodes by the method of displacing the central axis of the aperture. Even in such a case, the problem of the distortion of the outer electron beam spot similarly occurs.

[Object of the Invention]

An object of the present invention is to provide an electron gun structure provided with an electron beam deflecting means capable of reducing spot distortion on the fluorescent surface of an outer electron beam.

[Outline of Invention]

Most of the causes of the distortion of the shape of the outer electron beam spot on the phosphor screen are that the center axis of the electrode opening on the phosphor screen side of the facing electrode openings is offset to the outside. Since the electron beam is deflected inward as it advances in the direction of the phosphor screen,
It passes through a portion largely deviated inward from the central axis of the phosphor screen side aperture. This causes an imbalance in the focusing force with respect to the electron beam, which distorts the spot.

Therefore, if it is possible to deflect the electron beam inward by displacing the center axis of the electrode aperture on the phosphor screen side of the opposite electrode apertures, the electron beam always passes near the center axis of the electrode aperture. Therefore, the spot distortion is lowered.
In the multi-stage main lens as shown in FIG. 1, of the electrodes facing each other, the potential of the electrode located on the phosphor screen side may be lower than the potential of the other electrode. In such a portion, the electron beam can be deflected inward by displacing the central axis of the aperture of the phosphor screen side electrode inward, and the object of the invention can be achieved.

Example of Invention

In order to confirm the effect of the present invention, the embodiment of the present invention shown in FIG. 4 and the conventional example shown in FIG. 5 were analyzed by an electron beam analysis program and the results were compared. Here, for the sake of simplicity, consider a main lens composed of cylindrical electrodes, and assume that the G3 electrode 11, the G4 electrode 12, the G5 electrode 13,
A beam deflecting means is provided in the UPF lens portion formed by. In the example of FIG. 4, the central axis of the G4 electrode side opening of the G5 electrode 13 to which the focusing voltage is applied according to the present invention is displaced inward, and in the example of FIG. 5, a high voltage is applied according to the conventional example. The opening of the G4 electrode 12 is offset to the outside as compared with the opening of the facing G3 electrode 11. In either case, in order to allow the fixing jig inserted from the G6 electrode 14 side during electrode assembly to penetrate, the opening diameter of the adjacent opening portions on the G6 electrode side does not become smaller than one opening diameter. Combined with.

The central orbit 20 of the electron beam and two orbits 45 and 46 which are incident at a constant angle (± 0.5 °) with respect to the central orbit.
To analyze. The value of the focusing voltage V _f when the orbit 45 incident at a positive angle coincides with the central orbit 17 on the phosphor screen 3 is V _fh1, and the orbit 46 incident at a negative angle is the central orbit on the phosphor screen 3. Focusing voltage V when it matches 20
The value of _f is V _fh2 . When V _fh1 and V _fh2 match, the focusing forces on both sides of the central orbit of the electron beam match, and the spot-shaped distortion on the phosphor screen disappears. Conversely, if the difference between these voltage values is large, the distortion becomes large. If the deviation of the central axis of the aperture is increased, the deflection amount of the electron beam is increased, and accordingly, the distortion of the spot shape is also increased.

FIG. 6 shows the relationship between the electron beam deflection amount and the spot distortion indicated by the difference between the values of V _fh1 and V _fh2 . The electron beam deflection amount is the electron beam center trajectory 20 shown in FIG.
Is represented by the deviation amount h from the central axis on the screen.
The value of h takes a value when the value of V _f becomes V _fh2 .
As can be seen from FIG. 6, as the amount of deflection of the central axis of the electrode aperture is increased and the amount of deflection of the electron beam is increased, V _fh1 and V _fh1
Although the disagreement of _fh2 spreads and the distortion of the electron beam spot becomes noticeable, the distortion in the example of FIG. 4 having the structure according to the present patent is suppressed as compared with the example of the conventional structure of FIG.

FIG. 7 shows an embodiment of the present invention. Unlike the electron gun shown as the conventional example in FIG. 1, the central axes of the G5 electrode 15 on both sides of the G4 electrode side aperture are deviated inward.
Therefore, the electron beam is deflected by the UPF lens part,
Even if the amount of deflection at the BPF lens portion is insufficient, the three electron beams can be concentrated and STC can be obtained. At this time, on the phosphor screen side, the central axis of the aperture is deviated in the direction in which the beam is deflected, that is, inside, so that the electron beam passes near the central axis of the aperture, and distortion is suppressed.

FIG. 8 shows an embodiment in which the present invention is applied to a main lens having a structure for giving a low potential common to the G2 electrode 10 to the G4 electrode 12. In this example, the central axis of the G3 electrode side opening of the G4 electrode 12 is displaced inward as compared with the opposing central axis of the G3 electrode opening.

FIG. 9 shows another embodiment of the present invention in which the present invention is applied to a main lens configured to provide a common focusing voltage V _f to the G3 electrode 11 and the G5 electrode 13 and a high voltage V ₀ common to the G4 electrode 12 and the G6 electrode 14. Here is an example. Center side 17 'of G4 electrode side opening of G5 electrode,
Central axis 1 common to the opposing openings of the G5 and G6 electrodes
7 ″ is gradually deviated inward as compared with the central axis 17 of the triode and the G3 and G4 electrode apertures. Therefore, the side beam central trajectory 20 is deflected in the central beam direction while Since the light passes through the center of the electrode aperture, the spot distortion on the fluorescent screen due to the deflection of the electron beam is reduced.

FIG. 10 shows a configuration in which the focusing voltage V _f common to the G3 electrode 11 and the G5 electrode 13 is applied, the low voltage V _G2 common to the G2 electrode 10 is applied to the G4 electrode 12, and the high voltage V ₀ is applied to the G6 electrode 14. It is another example in which the present invention is applied to a main lens. As compared with the central axis 17 of the opening of the triode and the G3 electrode 11, the central axis 17 'of the opening of the G4 electrode and the G5 electrode facing each other,
Since the central axes 17 ″ of the openings of the G5 electrode and the G6 electrode facing each other are gradually displaced inward, the strain of the spot is reduced.

FIG. 11 shows an embodiment in which the present patent is applied to a main lens configured to apply a high voltage V ₀ common to the third electrode 11 and the fifth electrode 13 and a focusing voltage V _f to the fourth electrode 12. BPF is provided between the third electrode and the fourth electrode and between the fourth electrode and the fifth electrode, respectively.
A lens is formed. Central axis 1 of the triode and the opening of the third electrode
Compared with 7, the third electrode side opening central axis 17 'of the fourth electrode,
Central axis 1 of the opening of the fourth electrode and the fifth electrode facing each other
Since 7 ″ is sequentially deviated in the direction of the central beam, the outer beam deflected in the direction of the central beam always passes near the central axis of each electrode aperture, so that the spot distortion is reduced.

FIG. 12 shows the BPF lens formed by the G5 electrode 13 and the G6 electrode 14 as the non-cylindrical electron lens structure shown in Japanese Patent Laid-Open No. 59-215640.
This is an example in which the present patent is applied to the UPF lens portion in combination with the UPF lens formed by the electrode 12 and the G5 electrode 13. Electrode plates 121, 1 having elliptical openings
22 are provided in the G3 electrode and the G4 electrode, respectively. G4, G5
The electrode aperture central axis 17 'is offset inward. Also, G
Among the cylindrical portions of the five electrodes protruding from the G4 electrode side opening to the inside of the G5 electrode, those located on the outer side have the cylindrical portion inclined with respect to the central axis 17 '. This is the central axis 17 and 1
This is to further increase the deflection force when the deflection amount is insufficient and the STC cannot be obtained only by the electron beam deflection due to the axis deviation 7 '. When the deviation of the central shaft 17 'with respect to the central shaft 17 is sufficiently large and the STC can be obtained only by this axial deviation, it is not necessary to incline the end of the cylinder, and a normal cylinder may be used.

Typical dimensions of this example are shown below.

○ Distance between the central axes of the openings of the triode and the G3 electrode 11; S
₁ = 5.78 ○ G4 electrode 12 and G5 electrode 13 hole center axis distance; S ₂ = 5.70 ○ G5 electrode cylinder height; h ₁ = 0.7; h ₂ = 2.0 ○ Center part elliptical hole semi-short diameter; a ₁ = 2.2; a ₂ = 2.5 ○ Outer elliptic semi-short diameter; b ₁ = 2.1; b ₂ = 2.5 ○ Electrode plate retreat amount; d ₁ = 4.0; d ₂ = 4.0 ○ G5, G6 electrode opening outer part radius; R = 4.0 (unit; mm) Here, h ₁ = h ₂ is set, and when the end surface of the cylindrical protruding portion of the G5 electrode 13 is not tilted, it is necessary to expand the dimension of S ₁ to 5.8 mm in order to take STC.

〔The invention's effect〕

According to the present invention, since the central axis of each electrode aperture is sequentially displaced in the direction in which the outer electron beam is deflected, that is, the central electron beam direction, the electron beam passes near the central axis of each aperture. Therefore, it is possible to reduce the distortion of the outer electron beam spot caused by passing through the portion deviated from the central axis. As a result, it is possible to suppress the deterioration of the cathode ray tube resolution caused by this distortion.

[Brief description of drawings]

FIG. 1 is a sectional view of a cathode ray tube having a conventional main lens, FIG. 2 is a sectional view of a conventional main lens, FIG. 3 is a view showing a beam spot shape on a screen, and FIG. 4 is the present invention. FIG. 5 is a sectional view of a main lens of one embodiment of the present invention, FIG. 5 is a sectional view of a main lens of a conventional method, FIG. 6 is a diagram showing a comparative analysis result of the embodiment of FIG. 4 and the conventional example of FIG. 7 to 12 are sectional views of electron guns according to other embodiments of the present invention. 1 ... glass envelope, 2 ... face plate, 3 ...
Fluorescent surface, 4 ... Shead mask, 5 ... Conductive film, 6,
7, 8 ... Cathode, 9 ... G1 electrode, 10 ... G2 electrode,
11 ... G3 electrode, 12 ... G4 electrode, 13 ... G5 electrode, 14 ... G6 electrode, 15 ... shielding cup, 16 ...
External magnetic deflection yoke, 17, 19 ... Central axis of triode for generating outer electron beam, 17 ', 17 "... Central axis of main lens aperture for focusing outer electron beam.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Iitaka 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Masakazu Fukushima 1-280, Higashi Koigakubo, Kokubunji, Tokyo Hitachi Central Research Laboratory, Ltd.

Claims (5)

[Claims] 1. A first electrode means for generating a plurality of electron beams and directing these electron beams along mutually parallel initial passages, and for focusing and concentrating each electron beam on a fluorescent screen. In the electron gun for a color picture tube, which is provided with a second electrode means that constitutes a substantially individual main lens in the passage of each electron beam, in the first half, each main lens is composed of a plurality of electron lenses, Among the plurality of electron lenses forming at least one main lens among the main lenses, at least one electron lens is formed non-axisymmetrically to concentrate each electron beam on the phosphor screen, and further, At least one of the electron lenses formed non-axisymmetrically has a pair of electrodes forming the electron lens, and the central axes of the holes of the electrodes provided on the first electrode means side face each other. Other electric Corresponding compared to the central axis of the aperture, the electron gun for a color picture tube, characterized in that is offset outwardly with respect to the electron gun assembly central axis of. 2. A G3 electrode, a G4 electrode, and a G5 in which the main lens is sequentially arranged from the first electrode means side to the phosphor screen side.
The G4 electrode and the G6 electrode are provided with four electrodes, and a high potential common to the G4 electrode and the G6 electrode is applied, a low potential common to the G3 electrode and the G5 electrode is applied, and an opening facing the G4 electrode of the G5 electrode is formed. Among them, the central axis of the hole which does not include the central axis of the electron gun structure is deviated to the central axis side of the electron gun structure as compared with the central axis of the G4 electrode opening facing each other. An electron gun for a color picture tube according to claim 1. 3. The center axes of the apertures of the G5 electrode and the G6 electrode facing each other are compared with the center axes of the corresponding electrode apertures in the first electrode means, and are displaced toward the electron gun structure center axis side. The electron gun for a color picture tube according to claim 2, wherein the electron gun is a color picture tube. 4. The G3 electrode, the G4 electrode, and the G4 electrode, which are sequentially arranged from the first electrode means side to the phosphor screen side, of the main lens.
A high potential is applied to the G6 electrode, a low potential is applied to the G3 electrode and the G5 electrode, and a potential lower than the low potential is applied to the G4 electrode. Of the openings facing each other, the central axis of the opening not including the central axis of the electron gun assembly is compared with the central axis of the facing G3 electrode opening, and is displaced toward the central axis of the electron gun assembly. An electron gun for a color picture tube according to claim 1. 5. The center axes of the apertures of the G5 electrode and the G6 electrode facing each other are compared with the center axes of the corresponding electrode apertures in the first electrode means, and are displaced toward the electron gun assembly center axis side. The electron gun for a color picture tube according to claim 4, wherein the electron gun is a color picture tube.