JPH0254846A - Color picture tube - Google Patents

Abstract

PURPOSE:To suppress the deterioration of color purity by doming by constituting a color picture tube so that the preset electron beams within three electron beams generate the required asymmetrical landing error. CONSTITUTION:A color picture tube provided with in-line-arranged three electron guns, a fluorescent screen with mosaic-shaped phosphors and a shadow mask is constituted so that beams RB and BB on both sides within three electron beams RB, GB and BB generate the required landing error asymmetrical against the Y-axis at the center of the fluorescent screen. The unbalance of the luminous area is made minimum at the time of the occurrence of doming in which the shadow mask is expanded and protruded via the heating by electron beams and the distance between the mask and the fluorescent screen is changed, and the deterioration of color purity due to apparent doming is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shadow mask type color picture tube having electron guns arranged in rows, that is, in-line.

[Prior Art] FIG. 6 is a partially cutaway side view of a conventionally used shadow mask type color picture tube. In the same figure, (
1) is a glass bulb, (2) is a fluorescent screen provided on panel part (1a), and (3) is the screen (2)
(4) is an electron gun that emits three electron beams for blue, green, and red;
Arranged inline.

Figure 7 shows the arrangement of the electron gun (4) and the fluorescent screen (2).
) is a diagram showing the correlation with the blue electron gun (BG).
The line electron gun (6G) and the red electron gun (RG) are connected to the tube axis (
They are arranged in a line on a horizontal axis (hereinafter referred to as the The explanation will be given assuming that the left half is A and the right half is B.

Next, the operation of the above configuration will be explained.

The above shadow mask (3) has a normal thickness of 0. lO~0.
It is generally a thin metal plate with a diameter of about 18 cm and a round or slit-shaped small hole (3a). One of the biggest drawbacks of such a shadow mask (3) is that the electron beam emitted from the electron gun (4) is accelerated and directly hits the shadow mask (3). ) is well known for its doming phenomenon, in which the temperature of an object increases and the projecting part swells due to thermal expansion.

This phenomenon is schematically shown in FIG. In Figure 8,
For example, a general case is shown in which the electron beam is scattered over the entire surface of the shadow mask (3), and the temperature of the shadow mask (3) reaches about 60°C. In this figure, it is written again that the shadow mask (3) changes from the cold state 1 (Ta) to the heated state (Tb), and at the same time the screen (2) and the shadow mask at the center of the panel part (la) are shown. (3) Distance 1
tQ (hereinafter referred to as Q value) changes from (Qa) to (Qb). For example, the amount of change in this Q value is 0.1
It is on the order of 5 to 0.2 ■. In addition, in FIG. 8, for example, one small hole (3a) of the shadow mask (3) is shown.
) due to temperature increase, from (Pa) to (
It is also written that it is moving to the position pb). The direction in which the position of this small hole (3a) moves from (Pa) to (pb) is always the direction inward from the center of the fluorescent screen (2) and the direction in which the Q value becomes smaller.

In FIG. 9 (^), the areas where doming is likely to occur or where doming is easily noticeable are shown with diagonal lines on a commonly used square fluorescent screen. 91st
'M(B) Fluorescently clean its doming (2)-
The movement of the electron beam at h, that is, the movement of the shadow mask and the distance (r) from the center (6) of the fluorescent screen (2)
) is shown as a function.

For example, for a color picture tube with a 110" deflection, 6
There is a range in which the beam movement due to doming is large near 0' deflection and, in the case of a 906-polarization color picture tube, near 50° deflection.

Incidentally, recently, a picture tube system that eliminates the need for dynamic convergence by combining an in-line electron gun and a shadow mask with small circular holes has been used in high-resolution picture tubes. In the case of such a high-resolution picture tube, the hole pitch of the shadow mask is approximately half that of the conventional one, 0.
It is set to about 30 mm. Therefore, the Q value used is about 5 to 71, which is half of the conventional value. The way in which doming occurs in a picture tube is the same as in the conventional case, but there are some differences, which will be explained below.

10(A) and 10(B) are for explaining the doming phenomenon on the right side of a high-resolution color picture tube, that is, the right hatched area in FIG. 9(A). Figure 10 (A)
Here, the blue, green, and red phosphor dots (O3) in normal condition,
For (GS) and (R5), each electron beam (
BB), (GB), (RB) are properly runned. In other words, the electron beam trio is correctly positioned at the center of the phosphor dot trio. This first
Figure O (^) shows only the electron beam trio that has passed through one hole in the shadow mask, where (BB), (
RB) is called a side beam. Each phosphor dot (8
3) The distance between the centers of , (Gs), and (R3) is (d
o).

Figure 1O (8) shows the phosphor dots (BS), (GS), (R5) and the electron beam (B[
l), (GB).

(RB), and as shown in the figure, the distance between the centers of the phosphor dots (BS), (GS), and (Is) (
do) remains the same, or electron beam (BB), (G
B) is the center-to-center distance of (RB) or (d).

Moreover, phosphor dots (BS), (GS), (R3
) with respect to the center of the electron beam (1'lB), (GB
), (RB) or to the left. This is called a Landink error.

The meshes in Figure 1O (A) and (B) indicate that the phosphor dots (BS), (GS), and (R3) are connected to the electron beam (
RB), (GB).

(RB) shows the location where it shines due to excitation. Here, as shown in FIG. 1O (IS), an electron beam (llll
'l), (GR), and (RB) all move by an equal distance to the left side, which is not a critical problem. That is, the human eye is more sensitive to changes in the balance of light from glowing phosphors that is visible to the human eye. In the case of Figure 10 (B), if only this balance is considered, d
<do, so the rightmost phosphor dot (BS)
The illuminated area is the smallest.

In other words, to the eye, it looks like a red pot.

This phenomenon can be easily understood from the explanation of FIG.

FIG. 11 is for explaining the movement of an electron beam on a fluorescent screen. In the same figure, (O is the electron beam (BB), (GB), (RB), each of which moves by the same amount, and the small hole (3a) in Figure 8 or (Pa)
This is the component that moves in the direction of the screen center (τ) when moving from (pb) to (pb). Also, ■ in Figure 11 is the Q value or AQ=
Due to the fact that Qa-Qb is smaller.

The central electron beam (GB) has electron beams on both sides (GB).
118), (RB) approaches each other, and this occurs because the off-axis distances of both side beams do not change when fired from the electron gun due to deviation of ΔQ from the predetermined Q value. 6 Furthermore, O) in Figure 11 is ``
The movement distance of electron beams (8B), (GB), (RB) is 1
- indicates (O+■). In the case of high-resolution color picture tubes, the original Q value is set small, so the problem is probably due to the change in Q value AQ due to doming.

[Problems to be Solved by the Invention] With the conventional color picture tube configured as described above, there was a problem in that color shift was easily noticeable due to changes in the Q value due to the doming phenomenon. In particular, when the Q value is originally small, such as in a high-resolution color picture tube, it is more likely that the color purity deteriorates due to changes in the Q value due to doming! Written by ili.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a color picture tube that can reduce deterioration of color purity even if a doming phenomenon occurs.

[Means for Solving the Problems] The color picture tube according to the present invention is configured to generate asymmetrical landing errors on both sides of the central portion of the fluorescent screen for the electron beams on both sides of the three electron beams. It is characterized by what it did.

[Operation] According to the present invention, even if the electron beam moves on the fluorescent screen due to the doming phenomenon, the electron beams on both sides will cause a landing error that is asymmetrical to each other. imbalance can be minimized. This reduces color purity degradation due to doming.

[Embodiment of Q-ming] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram for explaining the landing state of each electron beam of a color picture tube according to an embodiment of the present invention, and in detail, it has an in-line array of electron guns and a small circular phosphor dot type fluorescent screen. This figure shows the occurrence of landing errors on the left and right sides of the fluorescent screen for a trio of three-color electron beams regarding a small hole in a shadow mask on the X-axis where doming is easily noticeable in a high-resolution color picture tube. .

As is clear from Figure 1, on the right side of the Y axis (B),
The landing errors of the blue and red electron beams (BB) and (RB) are at least 20 degrees and Lop points, respectively, and the position of the phosphor dot is radially inward from the center (stone) of the fluorescent screen. It is composed of In addition, on the left side (8) of the Y-axis, landing errors occur asymmetrically on the left and right of the Y-axis at 10 pm and 20 pm, respectively, for the blue and red electron beams (RB) and (RR). is configured to be

The landing characteristics shown in Fig. 1 above can be obtained by, for example, adjusting the operating conditions of the picture tube at a high voltage of 26 KV and a white raster with a total electron beam amount of 500 JLA, and then adjusting the entire surface to correct the landing error. 1st
Printing of mosaic fluorescent dots sometimes involves correction that causes landing errors as shown in the figure.

Fig. fJS2 shows the doming state of the color picture tube configured as shown in Fig. 1 above, and in the same figure, the phosphor dots (83), (GS), (R3) or', where the mesh is inserted, are shown.
When doming occurs, the imbalance in the light emitting area due to the blue and red electron beams (BB) and (RB) is small when doming occurs in a place where the light beams are emitted by the excitation of the Yamashi beams RB), (GB), and (RB). This improves the appearance and reduces color shift due to doming.

FIG. 3 shows another embodiment of the present invention, in which it is applied to a flat tension type color picture tube.
Tb), (Pa), (I'b) are shown in Figures 6 and 8.
It is similar to that shown in the figure. Furthermore, Fig. 4 shows the relationship between the phosphor dots and the electron beam during doming in a flat tension type color picture tube, and corresponds to Fig. 9 (B). This is a diagram for explaining the movement of the beam, and corresponds to FIG. 11.

In the case of this flat tension type color picture tube, tension is applied to the shadow mask (3) in order to avoid doming as explained in Fig. 8. In this case, as shown in Fig. 4, The electron beam moves at the periphery of the fluorescent screen (2) by a distance 1t(r) from the center (stone). To do this, it is necessary to slightly correct the entire shadow mask (3) toward the fluorescent screen (2), but if this correction is completed,
Color purity deteriorates under other conditions. Therefore, during doming, the movement of the shadow mask (3) results in the result shown in FIG.

Therefore, in this other embodiment, the right side of the Y axis (B)
In this example, the landing error of the blue electron beam (BB) is made small and the landing error of the blue electron beam (BB) is made large on the left side (A) of the Y axis. We are trying to achieve this effect.

In addition, in each of the above embodiments, explanation has been given on both the left and right sides of the X axis, but the same effect can be obtained even if the same is carried out on both sides of the Y axis.

Further, in the embodiment L, a dot-type phosphor screen has been described, but the same effect as in the above embodiment can be obtained even if the present invention is applied to a stripe-type phosphor screen.

[Effects of the Invention] As described above, according to the present invention, by configuring the electron beams on both sides to generate asymmetrical landing errors on both sides of the central portion of the fluorescent screen, the electron beams on both sides during doming are By minimizing the unbalance of the light-emitting area due to doming, it is possible to improve the appearance and reduce deterioration of color purity due to doming.

In other words, the conspicuousness of color shift when toming occurs can be greatly reduced, which is particularly effective in improving the color purity of high-resolution color picture tubes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the landing state fS of an electron beam of a color picture tube according to one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the state during doming, and FIG. 3 is an explanatory diagram according to another embodiment of the present invention. Figure 4 is an enlarged cross-sectional view of the main parts of a flat tension type color picture tube.
The figure is a diagram for explaining the movement of the electron beam during doming compared to the one in Figure 3, Figure 6 is a cutaway side view of the color picture tube, and Figure 7 shows the correlation between the electron gun arrangement and the fluorescent screen. Figure 8 is an explanatory diagram of the doming phenomenon, Figure 9 (
A) is an explanatory diagram showing locations where doming is likely to occur, Figure 9 (B) is an explanatory diagram of the relationship between phosphor dots and electron beams during doming, and Figures 1o I24 (A) and (B) are diagrams showing the doming phenomenon. An explanatory diagram, FIG. 11, is a diagram for explaining the movement of an electron beam during doming. (2)... Fluorescent screen, (3)... Shadow mask, (BS), (GS), (R3)... Fluorescent dots, (8B), (GO). (RB)...electron beam, (BG), (GG),
(RG) - Electron gun. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) In a color picture tube equipped with three electron guns arranged in a row, a fluorescent screen forming a mosaic-like fluorescent screen, and a shadow mask placed opposite to the fluorescent screen, the electron guns A color picture tube characterized in that the electron beams on both sides of the three electron beams emitted by the above are configured to generate asymmetrical landing errors on both sides of the central portion of the fluorescent screen.