JPS5810354A - In-line-type color picture tube - Google Patents

Abstract

PURPOSE:To improve the shapes of beam spots over the entire surface of a fluorescent screen, and increase the resolution and improve the uniformity of the focus quality of an in-line-type color picture tube by providing asymmetrical lenses, which make the sectional shapes of electron beams incident upon main lenses laterally oblong, in the midst of electron-beam paths in front of the said main lenses. CONSTITUTION:A bipotential-type electron gun is constituted of three cathodes 9, 10 and 11 arranged on a horizontal line, a G1 electrode 12 having vertically- oblong slot-like beam-passing holes 13, 14 and 15, a G2 electrode 16 having circular beam-passing holes 17, 18 and 19, a box-like G3 electrode 20 and a box- like G4 electrode 31. Electron beams discharged from the cathodes 9, 10 and 11 come to have laterally-oblong sectional shapes by means of asymmetrical lenses developed by the beam-passing holes 13, 14 and 15 of the electrode 12, and become incident upon main lenses. When such electron beams having laterally- oblong sectional shapes are transmitted by the main lenses, the shapes of beam spots formed on a fluorescent screen are extremely improved from those obtained by use of electron beams with circular sections, and the diameters of the spots become small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-line color picture tube capable of obtaining high resolution over the entire area of the phosphor screen surface.

In general, the resolution of a color picture tube depends on the thickness and shape of the beam spot appearing on the phosphor screen surface. In order to obtain high resolution, the beam spot must be as small as possible and It is important that there is no shape distortion. It is also important that the three electron beams converge correctly at any one point on the phosphor screen surface.

However, the conventional self-convergence deflection yoke attached to an in-line color picture tube distributes the horizontal deflection magnetic field into a bin-cushion-like distribution as shown in Figure 1(a).
Then, since the vertical deflection magnetic field can be accurately sized into a barrel-shaped distribution as shown in FIG. 1(b), ':j 7 /(-
While this simplifies the sense circuit and convergence adjustment, it tends to cause large shape distortions in the beam spots caused by the three electron beams 1, 2.3 that are incident on the phosphor screen surface, particularly in the peripheral areas. That is, as shown in FIG. 2, in the central part of the phosphor screen surface 4, the beam spot 6 is a perfect circle, whereas in the peripheral part 6, there is a horizontally long elliptical high-intensity core part and this beam spot. A long vertically long low-luminance haze area 8 appears, and the resolution of the peripheral area is low, making it difficult to read the three pages of image information displayed in this area.

Convergence adjustment is facilitated by reducing the mutual spacing between the three electron beams 1 and 2°3 that pass through the deflection magnetic field, but in order to do so, the diameter of the electron beam passing hole in the main lens forming electrode must be reduced. If the need arises, doing so will cause lens aberrations, resulting in a decrease in resolution.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional art. Next, an in-line color picture tube according to the present invention will be described with reference to embodiments shown in the drawings.

In Fig. 3, three cathodes 9 are arranged horizontally in a straight line.
+ 10.11 is the beam passage hole 13 of the vertical slot
．． G1 electrode with 14', 15 G2 electrode with 12° circular beam passage hole 17, 18, 161 box-shaped G
3 electrodes20. Together with the box-shaped G4 electrode 31, it constitutes a pi-potential type electron gun. The G3 electrode 2o and the G4 electrode 31, which serve as main lens forming electrodes, have horizontally long rectangular openings 24. in the four mutually opposing surfaces.
HL-10B58-10354 (2) The internal space of the G3 electrode 20 and the internal space of the G4 electrode 31 are separated by two metal partition walls provided inside these electrodes 20 and 31, respectively. They are separated by plates 26°27 and 34.35°, respectively.

The operation of the G3 electrode 2o and the G4 electrode 31 will be explained with reference to FIG.
This is a front view seen from the side, and figure (b) is A of figure (a).
-A' cross-sectional view, and the figure (c) is the BB of the figure (a).
'It is a sectional view. The internal space of the G3 electrode 2o is a partition plate 26
, 2, the internal space of the G4 electrode 31 is horizontally divided into three parts by partition plates 34 and 35. However, since each of the horizontal directions of the lens spaces 28, 29, and 30, which are divided spaces within 2 degrees of the G3 electrode, are smaller than the vertical direction V, the lens spaces are vertically long rectangular. Therefore, the relatively short horizontal length is useful for reducing the distance between the main lenses, and the relatively long vertical length V
This helps ensure a large lens space.

, but such lens spaces 28, 29.30 and 52.
-1 Since the resulting lens electric field is asymmetric with respect to the axis, the strength of the lens action differs in the horizontal, vertical, and diagonal directions, causing a significant asymmetric haze in the beam spot appearing on the phosphor screen surface. arise.

Therefore, as shown in Fig. 4 (1) and (C), the partition plates 28, 27 and 34.
Rather than starting from each end face, from a certain distance inside, that is, near each opening end face 25.
It is set up to avoid. Therefore, the distance f between the tip of the partition plate 27 of the G3 electrode 20 and the tip of the partition plate 36 of the G4 electrode 31 is also larger than the distance q between the end surface of the opening 24 and the end surface of the opening 32, and the main lens is Lens space divided into three in the horizontal direction 28, 29.30. 36, 37.38,
They are generated at 26° and 33° near the opening end face of the horizontally long space that is not subject to such division.

In general, the lens effect becomes stronger as the aperture width or electrode spacing becomes smaller, so in a divided space whose horizontal length is smaller than the vertical direction V, the lens effect becomes stronger in the horizontal direction than in the vertical direction. . On the other hand, the lens action in the vicinity of the opening end face 25.33 of the horizontal 67-ji long space is stronger in the vertical direction than in the horizontal direction, so by combining both, the strength of the lens action in the horizontal direction and the vertical direction are It becomes possible to equalize the strength of the lens action.

Note that the broken line curves 39°4Q and 41.42 respectively show typical examples of equipotential lines occurring in the vertical section and the horizontal section.

Another problem here is that the strength of the lens action is not uniform in directions other than the horizontal and vertical directions, and the difference between the two directions is particularly large in the diagonal direction. It is not possible to produce a shaped beam spot. Figure 5 shows the shape of the beam spot generated at the center of the phosphor screen surface.
), (b), and (c) show changes in the beam spot shape when the potential of the G3 electrode 2o is lowered and the lens strength is changed from underfocus to overfocus. At the time of underfocus as shown in FIG. 7(a), it becomes a pincushion-like shape with an elongated portion 50 extending in the diagonal direction, and when overfocusing as shown in FIG. 52. At an intermediate potential between under-focus and over-focus, the beam spot becomes minimum as shown in FIG. 2(b). However, it is not small enough because the horizontal, vertical, and diagonal directions are not balanced.

In order to solve this problem, in the present invention, an axially asymmetric lens is provided in the electron beam path in front of the main lens to make the cross-sectional shape of the electron beam incident on the main lens horizontally elongated, as shown in FIG. In the embodiment, the axis asymmetric lens is obtained by forming the beam passing holes 13° 14.15 of the G1 electrode 12 into vertically elongated slots. in this case,
The electron beam emitted from the cathode 9°10.11 is G1
Due to the axis asymmetric lens created by the beam passage hole of the electrode 12, its cross-sectional shape is horizontally elongated, and the beam then enters the main lens.

The operation of the axis asymmetric lens will be explained with reference to FIG.
The figure (a) shows a vertical cross section near the G1 electrode, and the figure Φ
) shows the same horizontal cross section. In the vertical direction, since the width of the beam passage hole of the G1 electrode 12 is large, the outermost beam 4
4 emits the cathode portion sufficiently far from the axis. on the other hand,
Since the curvature of the equipotential line 42 occurring in front of the cathode is small, a crossover 40 occurs at a point relatively far from the cathode 10.

In addition, in the horizontal direction, the outermost beam 46 is emitted from the cathode portion near the axis, and the equipotential line 43 generated on the front surface of the cathode has a large curvature, so the crossover 4 is placed at a point relatively close to the cathode 1o.
yields 1. Therefore, the exit angle aH from the horizontal crossover 41 is larger than the exit angle (Lv) from the vertical crossover 4o, and the cross-sectional shape of the electron beam incident on the main lens is horizontally long.

When an electron beam with a horizontally elongated cross section is passed through the main lens, the shape of the beam spot produced on the phosphor screen surface becomes much better than when an electron beam with a circular cross section is used, and the spot diameter becomes smaller. To explain this experimental result with reference to Figure 7, the beam spot of 9·° to 2' during underfocus shown in Figure 7(a) remains horizontally long, but as shown in Figure 7(C).
At the time of overfocus shown in , haze 53 occurs only in the horizontal direction, and hardly occurs in the vertical and diagonal directions. At the time of optimum focus shown in (in the figure), a good beam spot of a vertically long ellipse with a minimum horizontal diameter and a slightly larger vertical diameter is obtained.

In this way, the fact that haze does not occur in the vertical and diagonal directions and that a vertically elliptical beam spot is obtained means that the vertical beam is still under-focused under the voltage conditions where the beam in the horizontal direction is just focused. This property is very advantageous in an in-line color picture tube as described below.

As mentioned above, the snawachi and self-convergence deflection yokes distort the horizontal deflection magnetic field into a bottle cushion-like distribution and the vertical deflection magnetic field into a barrel-like distribution, so the electron beam subjected to the deflection effect is distorted in the vertical direction. Overfocus occurs, producing a long haze in the vertical direction, while underfocus occurs in the horizontal direction, and the core shape becomes horizontally long (see FIG. 2). By the way, if the beam spot at the center of the phosphor screen surface (at the time of optimum focus) is underfocused in the vertical direction due to implementation of the present invention, the beam spot when deflection is applied will be as described above. As shown in Figure 8, the beam spot shape is improved over the entire area of the phosphor screen surface, the resolution is improved, and the uniformity of focus quality is improved. do.

As shown in FIG. 9, the partition plates 26 and 27 of the G3 electrode 20
If each of the tips 60, 61 of the partition plate 26, 27 is concave in an arc shape, the partition plate 26, 27 can start from the end face of the oblong opening 24. However, the horizontally elongated opening 24 is not limited to a rectangular shape.
As shown in Figure 0 (-), an elliptical shape that combines a straight a66 and a circular arc 66, or as shown in the same figure, an arc 70,
71 and 72 can be formed in a continuous arc shape, etc., and the same applies to the G4 electrode 31.

The electrode configuration for obtaining an electron beam having a horizontally elongated cross section is not limited to the above embodiment. In another embodiment shown in FIG. 11(aL(b)), three square beam passing holes 75 are provided in the G1 electrode 12, and tapered grooves 76 are provided above and below the beam passing holes 75.
By providing this, the same effect as described above is obtained. FIG. 2C shows a cross-sectional view when the tapered groove 76 is formed in an arc shape. In another embodiment shown in FIGS. 12(a) and 12(g), an auxiliary electrode plate 83 having a horizontally long slot 82 is provided on the cathode side surface of the electrode plate 81 having a vertically long slot 8Q.
In another embodiment shown in FIG. 13, the G2 electrode 16 is provided with three horizontally elongated slot-shaped beam passage holes 85, 86, and 87 to form an axially asymmetric lens. It has gained. Also, Fig. 14(a), (1
-), three circular holes 91, 92, 93
A G2 electrode is used in which an auxiliary electrode plate 95 having a horizontally elongated slot 96 is attached to an electrode plate 9o having a horizontal slot 96, and the auxiliary electrode plate 96 is arranged to face the G3 electrode 20. Furthermore, in the embodiment shown in FIG. 15, the beam passing holes 100101 and 102 on the entrance side of the G3 electrode 20 are formed into vertically long slots, thereby obtaining an axially asymmetric lens.

As has become clear from the above description, the in-line color picture tube of the present invention has horizontally long openings on the opposing surfaces of the two electrodes for forming the main lens, and the interior of the electrodes following these openings. The space is horizontally divided into three by a partition plate, avoiding the vicinity of the opening, and three vertically long lens spaces are formed here, while the electron beam path before reaching the main lens passes through this path. This device is provided with an axially asymmetric lens generating section to make the cross-sectional shape of the electron beam a long ellipse in the horizontal direction, and can generate a small diameter beam spot of a vertically long ellipse in the center of the phosphor screen surface. , the beam spot shape around the screen surface can be improved, and good convergence and high resolution can be obtained.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams showing the distribution of the horizontal deflection magnetic field and the distribution of the vertical deflection magnetic field due to the deflection yoke for self-contouring, and Figure 2 shows the distribution of the vertical deflection magnetic field of the conventional color picture tube. FIG. 3 is a perspective view showing an electron gun electrode of an in-line color picture tube embodying the present invention;
Figure 4 (a) is a front view of the G3 electrode of the color picture tube viewed from the 04 electrode side, Figure 4 (b) is a sectional view taken along line AA' in Figure 4 (a), and Figure 4 (C) is the same view. BB/cross section of figure (-), 6th
Figures (a), ■), and (C) are diagrams showing the shape of the beam spot obtained when an electron beam with a circular cross section is incident on the main lens of the same color picture tube, and Figure 6 (a) is a horizontally long cross section. Figure 7(a), (b), and (C) are vertical cross-sectional views of the axially asymmetric lens generating unit for forming an electron beam. Figure 8 shows the shape of the beam spot obtained when an electron beam with a horizontally elongated cross section is incident on the main lens. Figure 9 is a perspective view of a main part of an electrode for forming a main lens according to another embodiment of the present invention, and Figure 10 (
a) and (b) are respectively Me 14 of other embodiments of the present invention.
. 11(a) is a front view of the non-axisymmetric lens generating section of another embodiment of the present invention, and FIGS. 11(b) and 11(C) are Side sectional view, Figure 12 (
, ) and (b) are respectively a front view and a side sectional view of an axially asymmetric lens generating unit according to another embodiment of the present invention, and FIG. 13 is a perspective view of an axially asymmetric lens generating unit according to another embodiment of the present invention. ,
Figures 14) and (b) are respectively a front view and a side sectional view of an axially asymmetric lens generating unit according to another embodiment of the present invention, and Figure 16 is a perspective view of an axially asymmetric lens generating unit according to another embodiment of the present invention. It is a diagram. 12...G1 electrode, 16...G2 electrode,
2o...G3 electrode, 31...G4 electrode, 24°32...horizontal opening, 25.33...
... Near the opening end surface, 26, 27, 34.35...
...Partition plate, 28.29, 30, 36, 37.38.
...lens space. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 4 Figure 5 (αI <-b)
(C) Figure 6 21G Figure 9 M2O ((2-)
(b) Procedural amendment letter November 18, 1980 Mr. Commissioner of the Japan Patent Office 2. Name of the invention In-line color picture tube 3. Person making the amendment Relationship to the case Patent application Person address 1006 Kadoma, Kadoma City, Osaka Prefecture Name
(584) Matsushita Electric Industrial Co., Ltd. Representative Kiyoshi Miyama - 4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Column 6 for detailed description of the invention in the specification subject to the 6th amendment Contents of the amendment (1) "The horizontal direction is longer than the vertical direction V" on page 4, line 15 of the specification is corrected to "the horizontal direction is longer than the vertical direction V." (2) Correct "Direction V" on page 5, line 19 of the same book to "Length in one direction ■".

Claims (1)

[Claims] Each of the two main lens forming electrodes has a horizontally long aperture on opposing surfaces, and the space inside the electrode following this aperture is horizontally divided into three by a partition plate, avoiding the vicinity of the aperture. Three vertically long lens spaces are formed here, while an axially asymmetric lens is formed in the electron beam path before reaching the main lens to make the cross-sectional shape of the electron beam passing through the path a horizontally long ellipse. An in-line color picture tube characterized by having a live part.