JPS5816293B2 - color - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color picture tube in which color shift caused by thermal expansion of a shadow mask is improved.

A conventional shadow mask type color picture tube is constructed as shown in FIG.

That is, a funnel-shaped funnel part 2 is connected to a neck part 1 containing an electron gun (not shown).

Panel portion 3 is joined.

A fluorescent surface (not shown) is formed on the inner surface 3 of this panel portion 3, and a shadow mask 4 is formed at a predetermined distance from this fluorescent surface.
is installed.

This shadow mask 4 is usually obtained by chemically etching a mild steel plate of 0.1 to 0.18 mm into a desired arrangement to form through holes, and then press-molding it into a desired shape.The shadow mask body has a spherical shape. 4. and a skirt portion 4□ connected thereto.

In such a shadow mask 4, the skirt portion 42 is welded and fixed to the Z-shaped frame 5 in cross section, which is disposed within the panel 3.

The frame 5 is provided with springs 6 at a plurality of locations, and the springs 6 are fitted into panel pins 7 protruding from the inner wall of the panel 3.

In this way, the shadow mask main body 41 is mounted within the panel 3 while maintaining a predetermined distance from the fluorescent surface.

The conventional color picture tube with the above configuration is incorporated into a common color television receiver and operated, but the anode loss during operation is usually 25KV x 700 to 1200μA, or about 30W
reach.

As is well known, the electron beam transmittance of the shadow mask body 41 is normally 14 to 18%.
The amount of beam colliding with □ is at least 82%.

That is, it is thought that the anode loss is mostly the velocity energy of the electron beam, and 82% of it collides with the shadow mask body 4 and is converted into thermal energy, so the shadow mask 4 is considered to be receiving 24.6 W of energy. It will be done.

As a result of the temperature of the shadow mask 4 rising due to such thermal energy, the shadow mask body 4□ causes thermal expansion.

That is, as soon as the operation starts, the shadow mask main body 4□ thermally expands, resulting in 4. in FIG. It expands from the position to the 4: position.

This is clear from the figure 4. This means that hole A of the shadow mask at 41 has been moved to position A' on 41 with thermal expansion.

Movement of the hole of this shadow mask body 4 A-)A'
Therefore, the electron beam passing through hole A (or A') is 8 → 8
', and a beam spot movement of Δr-PP' occurs on the inner surface 3 of the panel 3, that is, on the surface coated with the fluorescent film.

Figure 2 shows an example of a commonly used 18-inch striped length color picture tube, with a radius of 1 inch from the center of the panel.
It is a diagram illustrating the relationship between the beam movement amount Δr value and time at a position of 457πm.

What appears in Figure 3 shows the landing of the beam spot 10 that is created after passing through the ideal stripe phosphor 9 and the hole (slit) A at the observation point in this example, and the shadow Mask body 4. The normal margin 17 for movement of the beam spot due to expansion is only about 37.5 μ.

Therefore, the maximum amount of beam spot movement in Figure 2 is 67μ.
The value was -29.5μ, which caused a so-called mislanding, which destroyed the white uniformity of the screen and degraded the image quality.

In order to eliminate this drawback, the conventional method was to
As shown in FIG. 5 shown in FIG. The connecting portion 12 having the same shape as the connecting portion 12 is formed.

However, in such a structure, the depth of the notches 19 and 19' must be at least half the width of the skirt portion 4□ otherwise the mask body 4. Since the thermal expansion of the skirt portion is absorbed by the skirt portion and the expansion toward the inner surface of the panel is not reduced, the frame portion and the notch 1 are removed as shown in Figures 4 and 5.
A gap 30 is formed near the top of 9 and 19'.

This gap 30 is exposed to light in the black coating process, that is, in the screening process, and the phosphor is attached to the light leakage area.

There was a drawback that this part was prone to emitting light.

The shadow mask 4 used in the color picture tube of the present invention eliminates the above-mentioned drawbacks, drastically reduces the movement of the beam spot due to thermal expansion of the shadow mask body 41 compared to the conventional example, and provides a color picture tube with excellent image quality. In addition to this, it also solves the problem of light leakage during the black coating process.

Next, the relationship between the skirt portion 4□ of the shadow mask bottom and the frame 5 in one embodiment applied to the color picture tube of the present invention will be explained with reference to FIG.

In the figure, the same reference numerals as in FIGS. 4 and 5 indicate the same parts.

That is, the notches 19.19' are formed on both sides of the welding point 11 in the skirt portion 4□ of the shadow mask back, similar to the conventional one, but in this embodiment, the notches 19.19' are formed on both sides of the welding point 11.
The depth of the notch 19' is made shallower than that of the conventional one, and narrow notches 20 and 20' are provided at the top of each incision close to the bending part.

Further, a hatched portion 21 near the bent portion of the skirt portion between the notches 20 and 20' is formed to be thin by etching or the like.

As a result, the mask skirt portion 4□ changes from a strongly fixed state to an elastic state.

Therefore, beam projection is performed as described above, and the shadow mask body 4. When the shadow mask main body 41 undergoes thermal expansion, the amount of thermal expansion of the shadow mask body 41 can be distributed to the skirt portion 42, so that the amount of beam movement is reduced.

Better white uniformity image quality can be obtained.

Furthermore, by narrowing the width of the notches 20, 20', light leakage during the black coating process can be prevented.

That is, in the conventional structure, it was impossible to deepen the cuts 19 and 19' shown in FIG. 4 or 5 in order to prevent this light leakage, but with the structure of this embodiment, By doing so, it became possible to provide the slits 20 and 20' close to the bending portion.

As a result, the ability to absorb the expansion of the shadow mask main body toward the inner surface of the panel is improved, and the amount of beam movement can be further reduced.

Next, to explain the formation state of the cuts 19, 19' and notches 20, 20' numerically, the shadow mask material thickness is 0.1
Width of 5mm shadow mask skirt portion 42: 151nr
/L, in the one shown in Figure 4, the width of each cut 19.19' was 4 mm and the depth was 11 mm, but in the one shown in Figure 6, the width of each cut 19°19' was 4 mm each, and the depth was 11 mm. length 5mm,
The width of the notch was 0.1 mm and the depth was 8 mm, making a total depth of 13 mm.

In this case, the thickness of the thin portion 20 was set to 0.1 mm on average.

FIG. 7 shows a comparison between the conventional shadow mask and the embodiment of the shadow mask applied to the present invention described above.
4□' and 4'' respectively indicate the shadow mask body before expansion, the shadow mask body after expansion of the conventional structure, and the shadow mask body after expansion in the embodiment of the present invention.

8°8', 8'' are beam trajectories passing through the same shadow mask in each of the above cases, and P,
P'.

y is the screen landing position in each case.

As is clear from FIG. 7, the beam movement amount PP''(△r) in the embodiment of the present invention is smaller than the beam movement amount PP'(△r) in the conventional case.

Next, the table below shows the results of comparative data obtained through actual experiments.

The operating conditions are EbXIb = 37.5 W, and the beam movement is the maximum amount within 5 minutes.

FIGS. 8 to 10 show other embodiments of the shadow mask skirt portion to which the present invention is applied.

That is, FIG. 8 shows the cutting depth 19.19' of the conventional example shown in FIG.
Notches 20 and 20' are formed on the axis of the cut 19 and 19', and two thinner portions (hatched portions) are provided at 21 and 21'.

In Fig. 9, tapered notches 20, 20' are formed so as to form a continuation line with the tops of the notches 19, 19', so that the thinner part (shaded part) 21 does not reach the notches. be.

In FIG. 10, notches 20, 20' are provided along the length of one side of a notch 1919'.

Other combinations of these embodiments (not shown), cut portion 1
Various modifications are possible within the scope of the claims, such as bending the axes of the notches 9, 19' and the notches 20, 20'.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional view for explaining the operation of a conventional shadow mask type color picture tube, and FIG. 2 is a curve diagram showing time and beam movement amount in the shadow mask type color picture tube of FIG. Fig. 3 is an explanatory diagram showing the relationship between the striped phosphor and the beam spot, and Figs. 4 and 5 are main parts showing the relationship between the skirt portion and frame of a conventional improved shadow mask having notches. 6 is a cross-sectional view of a main part showing the relationship between the skirt portion and the frame of a shadow mask applied to the color picture tube of the present invention, and FIG. 1 is a cross-sectional view of a conventional color picture tube and a color picture tube of the present invention. 8 to 10 are simplified explanatory diagrams showing modified examples of the skirt portion of the shadow mask applied to the present invention. 4...Shadow mask, 9...Stripe phosphor, 10...Beam spot, 11...
・・・・・・Welding point. 19.19'...notch part, 20,20'...
...Notsuchi, 21...Thin part.

Claims (1)

[Claims] 1. In a shadow mask type color picture tube comprising a frame fixed to a skirt portion on the peripheral edge of a shadow mask main body at a plurality of welding points, a pair of notches are provided on both sides of the welding points. A color picture tube characterized in that a notch narrower in width than the notch is provided at the top of the notch, and a thin portion is interposed between the pair of notches.