JPH0393135A - Color picture tube - Google Patents

Abstract

PURPOSE:To display a picture with good resolution over the whole area of the fluorescent screen by installing a generating means of an axial asymmetrical lens electric field and by generating a lens electric field which becomes a diverging type in the horizontal direction and a focusing type in the vertical direction. CONSTITUTION:Longitudinal electron beam through holes 4a-4c and long sideways electron beam through holes 5a-5c are made in the end face at a second focusing electrode side of a first focusing electrode 4 and in the end face at a first focusing electrode side of a second focusing electrode 5 respectively as a generating means of an axial asymmetrical lens electric field. As a result of an increase in a deflection angle of an electron beam, therefore, a potential difference is produced between a first auxiliary electrode 18 and a second auxiliary electrode 19 and between the second auxiliary electrode 19 and the first focusing electrode 4, respectively. The potential difference generates an axial asymmetrical lens which is a diverging type in the horizontal direction and a focusing type in the vertical direction. It is thereby possible to generate a beam spot almost in a circle over the whole area of a fluorescent screen and get a good resolution over the whole area thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color picture tube device configured to provide high resolution over the entire area of a phosphor screen.

The resolution characteristics of prior art color picture tube devices are highly dependent on the size and shape of the beam spot. That is, good resolution characteristics cannot be obtained unless the beam spot generated on the phosphor screen surface by the impact of the electron beam has a small diameter and is close to a perfect circle.

However, the electron beam trajectory from the electron gun to the phosphor screen surface becomes longer as the deflection angle of the electron beam increases. If the optimal focus voltage is maintained at the optimum focus voltage, the periphery of the phosphor screen will be in an overfocus state, and a beam spot will be small in diameter at the periphery, making it impossible to obtain good resolution.

Therefore, a so-called dynamic focus method is used, which increases the focus voltage as the deflection angle of the electron beam increases and weakens the main lens action.As described below, this method is suitable for driving in-line color picture tubes. is not suitable. In other words, in an in-line color picture tube in which three electron beam emitters are arranged horizontally in a straight line, the horizontal deflection magnetic field distribution is shaped like a bottle cushion, and the vertical deflection magnetic field distribution is shaped like a barrel, in order to obtain a self-convergence effect. Since the electron beams are each distorted in the horizontal direction, the three electron beams passing through the electron beams are subjected to a diverging effect in the horizontal direction and a converging effect in the vertical direction, resulting in a horizontally long and flat cross-sectional shape.

The divergence effect acts in a direction that cancels out the overfocus of the beam spot due to the elongation of the electron beam trajectory as the deflection angle of the electron beam increases. Maintains optimal focus. However, in the vertical direction, since the focusing effect is added, the degree of overfocus increases, resulting in a long haze portion in the beam spot, resulting in a loss of resolution. If you try to correct this overfocus using the dynamic focus method described above,
The beam spot becomes underfocused in the horizontal direction, making it impossible to obtain an appropriate correction effect.

This problem can be considerably improved by the invention described in, for example, Japanese Unexamined Patent Publication No. 61-99249. In the color picture tube of this invention, as shown in FIG.
a. l b, I Cs control grid electrode 2, accelerating electrode 3, first focusing electrode 4, second focusing electrode 5, and final accelerating electrode 6 are arranged in sequence, as shown in (a) and (b) in Fig. 10. As shown, the first focusing electrode 4 has vertically elongated electron beam passing holes 4a, 4b, 4c on the end surface on the second focusing electrode 5 side, and
The second focusing electrode 5 has a horizontally elongated electron beam passage hole 6a on the end face on the first focusing electrode side. 5b and 5c, respectively, and the second focusing electrode 5 and the final accelerating electrode 6 have electron beam passing holes 5d, 5e, 5f and 6a = 6b for main lens generation.
It has v6c. Then, a constant focus voltage V I"oc is applied to the first focusing electrode 4, a constant high voltage is applied to the final acceleration electrode 6, and a constant high voltage is applied to the second focusing electrode 5 from the focus voltage Vfoc to increase the deflection angle of the electron beam. A dynamic voltage that gradually increases accordingly is applied.When the potential of the second focusing electrode 5 becomes higher than the potential VPOC of the first focusing electrode 4 due to the application of the dynamic voltage,
Between both electrodes 4 and 5 are vertically elongated electron beam passing holes 4a and 4b.
, 4c and a horizontally elongated electron beam passage hole 5 a = 5
A quadrupole lens electric field is generated by b + 5 c, and the potential difference between the second focusing electrode 5 and the final accelerating electrode 6 is reduced, so that the lens action of the main lens is weakened. Due to these two effects, the beam spot of the electron beam deflected to the periphery of the phosphor screen surface maintains an optimal focus state in the horizontal direction and is free from haze in the vertical direction. Note that 7 in the figure indicates a dynamic voltage generation circuit.

Problems to be Solved by the Invention However, moiré (bright and dark striped patterns) is likely to occur due to interference between the scanning line of the electron beam and the hole arrangement of the shadow mask. Moiré is a type of image noise, and when it occurs, it not only causes extreme discomfort to the eyes, but also deteriorates the image quality.

Moire is more likely to occur as the vertical diameter of the beam spot becomes smaller, so when designing an electron gun, care must be taken to prevent the vertical diameter of the beam spot from becoming too small. However, in such a conventional color picture tube device, when a dynamic voltage with a change amount sufficient to bring the beam spot into optimal focus at each position on the phosphor screen surface is applied to the second focusing electrode, the fluorescence changes as shown in FIG. Although the beam spot 9 at the periphery of the body screen surface 8 no longer has a haze portion, it takes on a horizontally elongated shape generated only by the high-brightness core portion, and its vertical diameter becomes small. Since the vertical diameter becomes too small at a low beam current when the beam spot diameter is the smallest, moiré is likely to occur.

The reason why the beam spot has a horizontally elongated shape even though the electron beam is in the optimal focus state both in the horizontal and vertical directions is due to the properties of the electron lens system in the conventional example described above. This can be explained with reference to Figure 12. This figure shows the behavior of an electron beam that is deflected in the horizontal direction and maintained in an optimal focus state by applying a dynamic voltage. a) is a horizontal cross section, and in the same figure (ω is a vertical cross section cut along the deflection direction of the electron beam. 10 is a crossover portion of the electron beam, which corresponds to the object point of the lens system; 11 is the envelope line of the electron beam, 12 is the main lens, l3 is a convex lens representing the horizontal focusing action of the axially asymmetric lens electric field generated between the first focusing electrode and the second focusing electrode, and 14 is also the vertical direction. 15 is a concave lens that represents a diverging action in the horizontal direction due to the horizontal deflection magnetic field of the self-convergence deflection yoke; 16 is a convex lens that represents a focusing action in the vertical direction due to the same magnetic field; 17
indicates the impact point of the deflected beam.

In this way, it can be replaced with an optical lens system in which a convex lens, a convex lens, and a concave lens are sequentially arranged in the horizontal direction, and a concave lens, a convex lens, and a convex lens are sequentially arranged in the vertical direction from the side of the crossover section 10, which is the object point, In order to achieve optimal focusing in the horizontal and vertical directions, the incident angle α-■ must become small in the horizontal direction because the final stage is a concave lens.

With such a lens system, the electron beam is emitted from the crossover section 10, which is the object point, at an angle α with respect to the central axis, passes through the lens system, and enters the incident point l7 on the phosphor screen surface 8. If the angle is α′, the relationship is different in the horizontal and vertical directions, and the vertical incidence angle α
'V becomes larger than the horizontal incidence angle α'H. Generally, the magnification M of an electron lens system can be expressed as M=(α/α−>f, where V and V= are the potentials at the crossover portion and the phosphor screen surface, respectively. Therefore, The horizontal direction of the lens system is given by:

Then, since α−v>α′H as mentioned above, Mv
<MH. In other words, in the conventional color picture tube device mentioned above, the lens magnification in the vertical direction is smaller than the lens magnification in the horizontal direction, so the vertical diameter of the beam spot becomes smaller and moire is more likely to occur. .

#Solving the dog 1. Kiki, who is in the process of solving the dog The present invention has been made with the above-mentioned points in mind. A first focusing electrode and a second focusing electrode to which a dynamic voltage is applied that gradually increases from the focus voltage as the deflection angle of the electron beam increases are sequentially arranged between the control grid electrode and the final acceleration electrode. An axially asymmetrical lens electric field generating means is provided on at least one of opposing end surfaces of the first focusing electrode and the second focusing electrode, and the lens electric field is formed in a converging form in the horizontal direction and in a diverging form in the vertical direction. In the color picture tube device, a flat-shaped first auxiliary electrode is connected to the first focusing electrode, and a flat-shaped second M auxiliary electrode is connected to the second confectionery t-pole. , are sequentially arranged between the accelerating electrode and the first focusing electrode, and at least one of the opposing end surfaces of the first auxiliary electrode and the second auxiliary electrode and the second auxiliary N. An axially asymmetric lens electric field generating means is provided on at least one of the opposing end faces of the pole and the first focusing electrode to generate a lens electric field that is diverging in the horizontal direction and converging in the vertical direction.

Effect With this configuration, in the preceding stage of the axially asymmetrical lens electric field generated between the first focusing electrode and the second focusing electrode, an electric field is generated in the opposite direction, that is, it is diverging in the horizontal direction and in the vertical direction. Since a focused axially asymmetric lens electric field is generated, the lens magnification in the horizontal and vertical directions can be made almost equal, and a nearly circular beam spot can be generated over the entire area of the phosphor screen surface, resulting in good resolution. Not only can this be obtained over the above range, but also the vertical diameter of the beam spot will not become too small, so moiré can be prevented from occurring.

Embodiment As shown in FIG. 1, three cathodes 1a, lb, and lc arranged horizontally in line are a control grid electrode 2, an acceleration electrode 3, a first auxiliary electrode 18, a second auxiliary electrode 19, and a second auxiliary electrode 19. 1
The focusing electrode 4, the second focusing electrode 5, and the final acceleration electrode 6 constitute an in-line electron gun.

Vertically elongated electron beam passing holes 4a, 4b, 4c are formed on the end surface of the first focusing electrode 4 on the second focusing electrode side, and horizontally elongated electron beam passing holes 5 are formed on the end surface of the second focusing electrode 5 on the lth focusing electrode side.
a, 5b. 5c are respectively provided as axis asymmetric lens electric field generating means, and electrons for generating the main lens electric field are provided on the end face of the second focusing electrode 5 on the final acceleration electrode 6 side and on the end face of the four second focusing electrodes of the final acceleration electrode 6. Beam passage hole 5d. 5
e, 5f and 6a. 6b. 6c are provided respectively as in the conventional case.

Since the first auxiliary electrode 18 is connected to the first focusing electrode 4, a constant focus voltage VFoc is applied thereto. Since the second auxiliary electrode 19 is connected to the second focusing electrode 5, it is subjected to a dynamic voltage that gradually increases from the focus voltage v foc as the deflection angle of the electron beam increases.

The end surfaces of the first auxiliary electrode 18, the second auxiliary electrode 19, and the first focusing electrode 4 on the second auxiliary electrode side are as shown in FIG. 2(a).
(b). Non-circular electron beam passing holes 18a, 18b as shown in (C). 18c; 19a. 19b,1
9c; 4d. 4e and 4f are provided as axis-asymmetric lens electric field generating means, respectively. However, the electron beam passing holes 18a, 18b of the first auxiliary electrode 18. Each of 18c has a circular opening on the surface of the three accelerating electrodes, and
The surface of the second auxiliary electrode 19 has a horizontally long rectangular opening. Further, the electron beam passing hole 19a of the second auxiliary electrode 19,
19b. Reference numeral 19c has a rectangular shape with its long axis in the vertical direction, and electron beam passing holes 4d, 4e, and 4f provided in the end face of the first focusing electrode 4 on the second auxiliary electrode 19 side have their long axes in the horizontal direction. It is rectangular.

Therefore, as the deflection angle of the electron beam increases, potential differences occur between the first auxiliary electrode l8 and the second auxiliary electrode 19 and between the second auxiliary electrode 19 and the first focusing electrode 4, respectively. An axially asymmetric lens electric field is generated that is horizontally divergent and vertically convergent.

To explain the behavior of the electron beam in this electron lens system with reference to Figure 3, (a) in the figure is a cross section in the horizontal direction, and (b) in the figure is a cross section along the deflected electron beam. The horizontal cross-sections of the axially asymmetric lens electric fields generated by the first auxiliary electrode, the second auxiliary electrode, and the first focusing electrode are focused by the concave lens 20 in the vertical direction. The lens action is shown by a convex lens 21, respectively. Note that other symbols in the figure correspond to those described above.

The electron beam emitted from the crossover section 10 at an angle α with respect to the central axis is subjected to lens effects of divergence in the horizontal direction and convergence in the vertical direction by the concave lens 20 and the convex lens 2l.

In the horizontal direction, it expands to an angle larger than α, and in the vertical direction, it narrows to an angle smaller than α, so
Vertical incident angle α of the electron beam that passes through the electron lens system and enters the horizontal deflection point 17 of the phosphor screen surface 8
1 is no longer too large than the horizontal incidence angle α'H, and α=+”α′H.

That is, the lens magnification Mv in the vertical direction and the lens magnification MH in the horizontal direction can be set to MYΣMH.

Although the above description has been made of the case where the electron beam is deflected in the horizontal direction on the phosphor screen surface, the same explanation as above applies also to the case where the electron beam is deflected in the vertical direction.

As explained above, by applying a dynamic voltage, the beam spot can always be kept in the optimal focus state in the horizontal and vertical directions, and the magnification of each lens system in the horizontal and vertical directions can also be kept almost the same. Even the beam spot caused by the electron beam deflected to the periphery of the phosphor screen surface can be made into a nearly circular shape as shown in FIG. 4, and the vertical diameter of the beam spot can be prevented from becoming too small. It becomes possible to project a high-quality image with high resolution and no moiré over the entire area of the phosphor screen surface.

In an example using a 110° deflection rectangular color picture tube, the final accelerating voltage was 30 kV, the first focusing electrode and the first
When the focus voltage to the auxiliary electrode is 8 kV, the second
The dynamic voltage for the focusing electrode and the second auxiliary electrode 19 is approximately 1.2 KV with respect to the focus voltage of 30 KV. That is, a suitable value for the maximum amplitude of the dynamic voltage is about 1.2 KV.

When the effective aperture of the main lens is 7.8 m, the distance from the axially asymmetric lens generated between both focusing electrodes to the main lens can be 12.5 m, and in this case, the rectangular shape of both focusing electrodes The dimensions of the electron beam passage hole can be such that the long side is 4.5 mm and the short side is 3.6 mm. Further, the distance from the axis asymmetric lens to the second auxiliary electrode is 19. 5+m+, and the distance from the second auxiliary electrode to the cathode can be set to 4wwm.

The horizontally long opening of the electron beam passing hole of the first auxiliary electrode, the vertically long electron beam passing hole of the second auxiliary electrode, and the first focusing electrode 4
The horizontally elongated beam passing hole on the end face on the second auxiliary electrode side allows the vertical incident angle α゛V and horizontal incidence angle α″V of the electron beam deflected to the peripheral part of the phosphor screen surface to be α−H”α 'V.

The distance between the first auxiliary electrode and the second auxiliary electrode and the distance between the second auxiliary electrode and the first focusing electrode are both 0.5 m.
+s, the long sides of the horizontally elongated opening, the vertically elongated electron beam passing hole, and the horizontally elongated beam passing hole can be set to 3 m to 4 m, and the short sides can be set to 1 m to 2 III1.

In the above-mentioned embodiment, the second auxiliary electrode had a vertically elongated electron beam passage hole, and the end face of the first focusing electrode on the second auxiliary electrode side had a horizontally elongated electron beam passage hole. In another embodiment shown in FIG. 6, the electron beam passing holes 19a to 19c of the second auxiliary electrode 19 are circular in the middle part of the plate thickness of the second auxiliary electrode 19, and vertically elongated on both sides, as shown in FIG. 6(a). The electron beam passing hole 4d. 4e, 4f are
As shown in FIG. 6(b), it has a circular shape with a horizontally long opening.

In another embodiment shown in FIG. 7, the second IM auxiliary electrode 18, the second M auxiliary electrode 19, and the second
The electron beam passage holes on the end face of the auxiliary electrode are each circular, and the first
A pair of screen-like portions 18d are provided on the surface of the auxiliary electrode 18 on the second auxiliary electrode side and the surface of the first focusing electrode 4 on the second auxiliary electrode side, projecting horizontally from the upper and lower positions of each electron beam passage hole of the electrode. , 18e. L8f; 4g. 4h, 4i, respectively, and on both sides of the second auxiliary electrode 19, a pair of screen-like portions 19d. 19e, 19f; 1
9g. 19h and 19i are respectively provided as axis asymmetric lens electric field generating means.

In this manner, by arranging the horizontal and vertical screen portions facing each other, it is possible to generate an axially asymmetrical lens electric field similar to the case where non-circular electron beam passage holes are arranged facing each other.

Effects of the Invention As described above, according to the present invention, it is possible not only to display an image with good resolution over the entire area of the phosphor screen surface, but also to prevent the occurrence of moiré. Since the two focusing electrodes can be connected to each other within the tube, there is no need to add an electrode terminal extraction bin.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an electron gun of a color picture tube device embodying the present invention, Fig. 2 (a) to (C) are side views of each electrode of the electron gun, and Fig. 3 (a) , (b) is a diagram depicting the horizontal and vertical lens electric fields acting on the electron beam in the same device replaced by an optical lens system, and Figure 4 shows the beam spot generated on the phosphor screen surface of the same device. FIG. 5 is a plan view schematically showing the shape, FIG. 5 is a cross-sectional view of a main part of an electron gun in another embodiment of the present invention, and FIG.
(b) is a side view of each electrode of the electron gun, and FIG. 7 is a cross-sectional view of the main parts of the electron gun in another embodiment of the present invention.
(a) to (C) in Fig. 8 are side views of each electrode of the electron gun;
FIG. 9 is a cross-sectional view of an electron gun of a conventional color picture tube device.
10(a) and 10(b) are side views of each electrode of the electron gun, and FIG. 11 is a plan view schematically showing the shape of the beam spot generated on the phosphor screen surface of the device. (a) in Figure 12. (b) is a diagram in which the horizontal and vertical lens electric fields acting on the electron beam in the same device are replaced with an optical lens system. 2...Control grid electrode, 3...Acceleration electrode, 4...First focusing electrode, 5...Second focusing electrode, 6...・・Final accelerating electrode, 8・・・・・・
Phosphor screen surface, 18...first auxiliary electrode,
19...Second auxiliary electrode.

Claims (2)

[Claims] (1) An accelerating electrode to which a constant accelerating voltage is applied, a first focusing electrode to which a constant focusing voltage is applied, and a dynamic voltage that gradually increases from the focusing voltage as the deflection angle of the electron beam increases. A second focusing electrode is sequentially arranged between the control grid electrode and the final acceleration electrode, and an axially asymmetric lens electric field generating means is provided on at least one of the opposing end surfaces of the first focusing electrode and the second focusing electrode. In a color picture tube device that generates a lens electric field that is convergent in the horizontal direction and divergent in the vertical direction between both focusing electrodes, a flat first auxiliary electrode is connected to the first focusing electrode. and a flat second auxiliary electrode connected to the second focusing electrode is sequentially arranged between the accelerating electrode and the first focusing electrode, and the first auxiliary electrode and the second auxiliary electrode are An axially asymmetric lens electric field generating means is provided on at least one of the opposing end surfaces and at least one of the opposing end surfaces of the second auxiliary electrode and the first focusing electrode, and has a divergent type in the horizontal direction and a convergent type in the vertical direction. A color picture tube device characterized by generating a lens electric field. (2) The electron beam passing hole of the first auxiliary electrode has a non-circular opening with its long axis in the horizontal direction on the end surface on the second auxiliary electrode side, and the electron beam passing hole of the second auxiliary electrode has a non-circular opening with its long axis in the horizontal direction. The electron beam passage hole of the first focusing electrode is a non-circular opening having a long axis in the horizontal direction, and the electron beam passing hole of the first focusing electrode is a non-circular opening with the long axis in the horizontal direction. 2. The color picture tube device according to claim 1, further comprising: a second auxiliary electrode on an end surface thereof on the second auxiliary electrode side.