JPH0775145B2 - Color picture tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color picture tube, and in particular, it is possible to improve a color shift phenomenon of a screen due to thermal expansion of a shadow mask having a large number of rectangular through holes. It concerns a possible color picture tube.

[Technical background of the invention and its problems]

An example of a conventional color picture tube will be described with reference to FIGS. 3 to 6.

First, referring to FIG. 3, a schematic structure of a color picture tube will be described. A panel (1) having an inner surface formed with a phosphor screen (1 ₁ ) composed of phosphor layers emitting three colors of blue, green and red.
And this panel (1), facing the mask frame
The shadow mask (2) supported by (3), the funnel (4) sealed to the panel (1), the neck (4 ₁ ) welded to this funnel (4), and this neck (4 ₁ ) Is assembled in the tube axis (Z) direction with the electron gun (5) for emitting three electron beams sealed in () as the main constituent part. In such a color picture tube, the three electron beams emitted from the electron gun (5) are deflected by a deflecting device (not shown), and then a rectangular transparent hole formed in the effective portion of the shadow mask (2). After passing through the holes, the phosphor layers formed on the inner surface of the panel (1) are projected. At this time, all the electron beams emitted from the electron gun (5) impinge on the shadow mask (2) except those used for causing the phosphor layer to emit light. The energy of the electron beam that causes the phosphor layer to emit is about 20% of the energy of the electron beam that strikes the shadow mask (2), and the remaining 80% of the electron beam energy is the shadow mask ( It is absorbed by 2). The energy of the absorbed electron beam becomes the heat energy for heating the shadow mask (2), and when the screen is bright and uniform, the temperature is 60 to 80 ° C in several tens of seconds to several minutes after the operation.
Experimental results have been reported that the temperature rises.

Next, the movement of the electron beam passing through the same rectangular through hole on the phosphor screen (1 ₁ ) due to the thermal expansion of the shadow mask (2) when the screen is bright and uniform will be described with reference to FIG.

In the case of this bright and uniform screen, the effective portion of the shadow mask (2) is almost uniformly bombarded with the electron beam (6) and the temperature rises as a whole. However, the mask frame (3) usually has a large heat capacity as compared with the shadow mask (2), and since the electron beam (6) hardly hits directly, thermal expansion does not occur easily.

As a result, the shadow mask (2) deforms as shown by the arrow,
Doming is entirely caused at the position of the shadow mask (2 ₁ ) indicated by the broken line. Therefore, the electron beam (6 ₁ ) passing through the point P ₁ in the figure becomes an electron beam (6 ₂ ) passing through the point P _2, and when observed from the front of the screen, the projection position of the electron beam on the phosphor layer is Purity drift toward the center of the screen as shown by the arrow (7) and impinges on another phosphor layer to cause color shift.

This phenomenon also occurs in the case of local doming that occurs when a locally bright image is displayed on the phosphor screen (1 ₁ ).

Next, how the doming phenomenon occurs will be described with reference to FIGS.
In (2), as shown in FIG. 5, a large number of rectangular through holes (2
a) is the bridge part (2b) on the short side and the band part (2b) on the long side.
It is regularly provided through c). Further, these rectangular through holes (2a) are formed by a small hole (2a ₁ ) on the electron gun side and a large hole (2a ₂ ) on the phosphor screen side. Therefore, the cross-sectional center of the shadow mask (2) is a curve (11) having a step (13). Therefore, the shadow mask (2)
When a compressive force is applied from the direction of the arrow (12) due to the thermal expansion of the, the mechanically weakest large hole (2a ₂ ) side, that is, the phosphor screen side is easily bent, which is the main cause of the doming phenomenon. Conceivable.

Various proposals have been made to reduce this doming phenomenon.

An example thereof will be described with reference to FIG. That is, the shadow mask (22) is regularly provided with a rectangular through hole (22a) formed from a small hole (22a ₁ ) on the electron gun side and a large hole (22a ₂ ) on the phosphor screen side. This is similar to the shadow mask shown in FIG. 5, but in this shadow mask (22), a glass layer (25) obtained by coating a member such as frit glass on the surface facing the electron gun and sintering the same. Is provided.

However, in such a shadow mask (22), the reinforcement of the bridge, which is extremely mechanically weakened by the small hole (22a ₁ ) on the electron gun side and the large hole (22a ₂ ) on the phosphor screen side, is incomplete. However, there is a problem that the doming phenomenon cannot be sufficiently prevented.

〔The invention's effect〕

The present invention has been made in view of the above problems, and an object thereof is to provide a color picture tube including a shadow mask capable of further reducing the doming phenomenon.

[Outline of Invention]

That is, the present invention provides a phosphor screen composed of a three-color phosphor layer adhered and formed on the inner surface of the panel, and a shadow mask having a large number of rectangular through-holes which are provided in opposition in proximity to the phosphor screen. An electron gun that emits an electron beam that selectively emits light from the three-color phosphor layer through the rectangular through-hole portion, the rectangular through-hole portion being the large hole on the phosphor screen side and the electron gun side. In a color picture tube that is formed of small holes, the short side of this rectangular through hole is regularly provided through the bridge section and the long side is through the band section, the bridge section and the band section face the electron gun. A color picture tube characterized in that a glass layer is provided on the side wall of the small hole and the large hole on the side of the bridge including the surface to be installed and on the side wall of the small hole on the side of the band, which is smaller than the side wall of the large hole. As an embodiment, the glass layer on the side surface of the hole is thick. That.

Example of Invention

An embodiment of the following color picture tube of the present invention is shown in FIGS.
It will be described with reference to the drawings.

The color picture tube is provided on the inner surface of a panel (31) having a phosphor screen (31 ₁ ) formed of a phosphor layer that emits three colors of blue, green, and red, and is opposed to the panel (31). , A shadow mask (32) whose periphery is supported by a mask frame (33) and a funnel (34) sealed to a panel (31)
And a neck (34 ₁ ) welded to this funnel (34)
And an electron gun (35) for emitting three electron beams sealed in the neck (34 ₁ ) as main constituent parts are assembled in the tube axis (Z) direction.

As shown in FIG. 2, in the shadow mask (32), a large number of rectangular through holes (32a) are formed in the bridge portion (32b) and the band portion (32).
It is regularly provided through c). And this rectangular through-hole portion (32) is composed of a small hole (32a ₁ ) on the electron gun side and a large hole (32a ₂ ) on the phosphor screen side, which is almost the same as the shadow mask described above. However, in the present embodiment, the surfaces of the bridge portion (32b) and the band portion (32c) facing the electron gun, the small hole (32a ₁ ) and the large hole (32a ₂ ) on the bridge portion (32b) side are provided. Side wall and the small hole (32
A glass layer (33) is provided on the side wall of a ₁ ). The glass layer (33) is not applied to the connecting portion (34) between the small hole (32a ₁ ) and the large hole (32a ₂ ). The reason why the glass layer (33) is not provided in the connecting portion (34) is to prevent reflection of the electron beam.

This glass layer (33) is formed, for example, by applying a dispersion liquid obtained by uniformly dispersing fine particles of lead borate glass into a butyl acetate alcohol solution in which a few percent of nitrocellulose is dissolved by a spray method, and then drying. You can In this case, the surface of the bridge portion (32b) and the band portion (32c) facing the electron gun and the small hole (32
a ₁ ) and the side wall of the large hole (32a ₂ ) and the small hole (3
The glass layer (33) is formed on the side wall of 2a ₁ ) by spraying from the front of the surface of the shadow mask (32) facing the electron gun. At this time, the band portion (32c) side, the glass on the side walls for the difference in diameters of the small holes (32a ₁₎ and the large hole (32a ₂₎ is large, a band portion (32c) side of the large hole (32a ₂₎ Layer (3
3) is not formed. The thickness of the glass layer (33) can be adjusted by controlling the spraying time, for example.

Due to the above structure, the mechanically weak bridge part (32b) faces the phosphor screen, and the band part (32c) faces the phosphor screen and the large hole (32a ₂ ). Except for the side wall, the shadow mask (32) will be covered with a glass layer (33) having a smaller thermal expansion coefficient,
As a result, it is possible to reduce the doming phenomenon of the shadow mask.

Although the glass layer (33) is provided almost uniformly in the above-mentioned embodiment,
By making the glass layer on the side wall of the small hole (32a ₁ ) thicker than the glass layer on the side wall of the large hole (32a ₂ ), the doming phenomenon of the shadow mask (32) can be further effectively reduced.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a color picture tube of extremely good quality.

[Brief description of drawings]

1 and 2 are views showing a color picture tube of the present invention. FIG. 1 is an exploded explanatory view, FIG. 2 (a) is an enlarged plan view of a shadow mask, and FIG. 2 (b) is Figure 2 (a) is A-A
FIG. 2 (c) is a cross-sectional view taken along line BB, and FIG. 2 (c) is a cross-sectional view taken along line BB. FIGS. FIG. 3 is a diagram showing a color picture tube of FIG.
FIG. 4 is an exploded view, FIG. 4 is an explanatory view of the purity drift due to the overall doming of the shadow mask, FIG. 5 is an enlarged plan view of the shadow mask, and FIG. 6 is CC of FIG.
FIG. 7 is a cross-sectional view taken along the line, and FIG. 7 is an explanatory cross-sectional view showing an example of a shadow mask designed to reduce doming. 1,31 …… Panel, 1 ₁ , 31 ₁ …… Phosphor screen 2,22,32 …… Shadow mask 2a, 22a, 32a …… Rectangular through hole 25,35 …… Glass layer

Claims (2)

[Claims] 1. A phosphor screen composed of a three-color phosphor layer adhered and formed on the inner surface of a panel, and a shadow mask having a large number of rectangular through-holes, which are opposed to each other in proximity to the phosphor screen. An electron gun for emitting an electron beam for selectively emitting light from the three-color phosphor layer through the rectangular through hole portion, the rectangular through hole portion being a large hole on the phosphor screen side. In the color picture tube which is formed of the small holes on the side of the electron gun, the short side of the rectangular through-hole portion is regularly provided through the bridge portion and the long side thereof through the band portion, the bridge portion and the A glass layer is provided on sidewalls of the small hole and the large hole on the bridge portion side including a surface of the band portion facing the electron gun, and on sidewalls of the small hole on the band portion side. A color picture tube. 2. The color picture tube according to claim 1, wherein the glass layer on the side wall of the small hole is thicker than the side wall of the large hole.