JPS61240530A - Color picture tube - Google Patents

Abstract

PURPOSE:To reduce doming, by providing a glass layer on the side of a shadow mask, which faces an electron gun, so that the glass layer extends into the small and large holes of the mask on the bridges thereof and into the small holes on the bands of the mask. CONSTITUTION:Numerous oblong through holes 32a are regularly provided in the shadow mask 32 of a color picture tube so that the holes are located among the bridges 32b and bands 32c of the shadow mask. Each through hole 32a consists of a small hole 32a1, which is opposed to the electron gun of the picture tube, and a large hole 32a2, which is opposed to the fluorescent surface of the tube. A glass layer 33 is provided on the sides of the bridges 32b and the bands 32c, which face the electron gun, so that the glass layer extends into the small and large holes 32a1, 32a2 on the bridges and into the small holes 32a1 on the bands. The bridges 32b mechanically weakened due to the large holes 32a2 are thus reinforced by the glass layer 33 of small thermal expansion coefficient to reduce coming so as to make an image of high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a color picture tube, and in particular, to improving the color shift phenomenon on the screen caused by thermal expansion of a shadow mask having a large number of rectangular holes. It concerns a possible color picture tube.

[Technical background of the invention and its problems]

Next, an example of a conventional color picture tube will be explained with reference to FIGS. 3 to 6.

First, to explain the general structure of a color picture tube with reference to FIG. 3, it is a panel (1, ), a shadow mask (2) placed opposite to this panel (1) and whose peripheral portion is supported by a mask frame (3);
A funnel (4) sealed to the panel (1), a neck (41) welded to this funnel (4), and an electron that emits three electric beams sealed to this neck (4□) It is assembled in the tube axis (Z) direction with the gun (5) as the main component.

In such a color picture tube, the three electron beams emitted from the electron gun (5) are deflected by a deflection device (not shown) and then deflected into a rectangular shape bored in the effective part of the shadow mask (2). It passes through the through hole and hits each phosphor layer on the inner surface of the panel 0). At this time, all of the energy of the electron beam emitted from the electron gun (5) impinges on the shadow mask (2) except for the energy used to make the phosphor layer emit light.

In this ratio, the energy of the electron beam that causes the phosphor layer to emit light is approximately 20%, and the remaining 80% of the energy of the electron beam is absorbed by the shadow mask (2). The energy of this absorbed electron beam becomes thermal energy that heats the shadow mask (2), and when the screen is bright and uniform, the temperature rises to 60 to 80 degrees Celsius in several tens of seconds to several minutes after operation. Results have been reported.

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

At this time, the electron beam (6) impinges on the effective part of the shadow mask (2) almost uniformly, causing the temperature to rise overall, but the mask frame (3) normally It has a large heat capacity compared to the electron beam (6), and is hardly subject to direct impact with the electron beam (6), so thermal expansion is difficult.

As a result, the shadow mask (2) is deformed as shown by the arrow, causing overall doming at the position of the shadow mask (2□) indicated by the broken line. Therefore, the electric beam (6□) that passed through point P in the figure becomes an electron beam (6□) that passes through point P2,
If you observe from the front of the screen, the position of the electron beam hitting the phosphor layer will drift toward the center of the screen as shown by arrow (7), and the electron beam will hit other phosphor layers, causing color shift. I'll wake you up.

This phenomenon also occurs during local doming when a locally bright image is required on the phosphor screen (I□).

Next, how such a doming phenomenon occurs will be explained with reference to FIGS. 5 and 6. As shown in FIG. 5, the shadow mask (2) has many rectangular through holes ( 2a) are regularly provided with a bridge part (2b) on the short side and a band part (2c) on the long side, and these rectangular through holes (2a) are provided with small holes on the electron gun side ( 2a1), the center of the cross section of the shadow mask (2) is a step (13) because it is formed by a large hole (2a2) on the phosphor screen side.
The curve (11) has the following values. Therefore, when compressive force is applied from the direction of the arrow (12) due to thermal expansion of the shadow mask (2), the large hole (2a2) is the weakest mechanically.
This tends to bend toward the side, that is, toward the phosphor screen, and this is thought to be the main cause of the doming phenomenon.

Various proposals have been made to reduce this doming development.

Next, an example thereof will be explained with reference to FIG. That is, the shadow mask (22) has a hole (22a□) on the electron gun side.
, the rectangular through holes (22a) formed from the large holes (22a2) on the phosphor screen side are provided regularly, similar to that shown in FIG. 1 - Friso 1 on the surface of Umask (22) facing the electron gun
- A glass layer (25) is provided by coating and sintering a member such as glass.

However, such a shadow mask (22) has a small hole (22a1) on the electron gun side and a large hole (22a1) on the phosphor screen side.
The reinforcement of the bridge portion, which is extremely mechanically weak due to 2a2), is incomplete, and there is a problem in that the I-damping phenomenon cannot be sufficiently prevented.

〔Effect of the invention〕

The present invention has been made in view of these two problems, and an object of the present invention is to provide a color picture tube equipped with a shadow mask that can further reduce the doming phenomenon.

[Summary of the invention]

That is, the present invention comprises: a phosphor screen made of phosphor layers of three colors adhered to the inner surface of a panel; a shadow mask having a large number of rectangular through holes disposed adjacent to the phosphor screen; and an electron gun that emits an electron beam selectively emitted from a colored phosphor layer through a rectangular through hole, the rectangular through hole having a large hole on the phosphor screen side and a large hole on the electron gun side. It consists of a small hole and a bridge part on the short side.

In a color picture tube whose long sides are arranged regularly through band parts, the side walls of the small hole and the large hole on the bridge part side, including the surface of the bridge part and the band part facing the electron gun, and the band part. This is a color picture tube characterized in that a glass layer is provided on the side wall of the side small hole, and an embodiment is such that the glass layer on the side surface of the small hole is thicker than the side wall of the large hole.

[Embodiments of the invention]

An embodiment of the color picture tube of the present invention is shown in FIGS. 1 and 2.
This will be explained using figures.

In other words, the color picture tube has a panel (31) on the inner surface of which is formed a phosphor screen (31□) consisting of a phosphor layer that emits light in three colors: red, green, and red, and a panel (31) that is attached to the panel (31). a shadow mask (32) whose periphery is supported by a mask frame (33); a funnel (34) sealed to the panel (31); and a neck (34) welded to the funnel (34). ) and this neck (341,)
An electron gun (35
) are assembled in the direction of the tube axis (Z) as the main components.

As shown in FIG. 2, this shadow mask (32) has a large number of rectangular through holes (32a) regularly provided through bridge portions (32b) and band portions (32c). This rectangular through hole (32) is a small hole (32) on the electron gun side.
a) and the large hole (32a2) on the phosphor screen side are almost the same as those described above, but in this example, the bridge part (32b) and the pan 1 part (32c) are formed.
on the surface facing the electron gun, the side walls of the small hole (32a, ) and large hole (32a2) on the bridge part (32b) side, and the side wall of the small hole (32a, -) on the band part (32c) side. It is characterized by being provided with a glass layer (33). At this point, the glass layer (33) has small holes (32a, ) and large holes (3
2az) is not coated on the connection part (34). The reason why the glass layer (33) is not provided in this connection part (34) is as follows.
This is to prevent reflection of the electron beam.

With the above structure, the bridge part (32b), which is particularly mechanically weak, has a surface facing the phosphor screen, and the band part (32c) has a surface facing the phosphor screen and the large hole (32a2). The side walls are each removed and covered with a glass layer (33) having a smaller coefficient of thermal expansion than the shadow mask (32), and as a result, it is possible to reduce the doming phenomenon of the shadow mask.

In the above embodiment, the glass layer (33) was provided almost uniformly, but the glass layer on the side wall of the small hole (32a□) was formed on the side wall of the large hole (32a2).
), it is possible to further effectively reduce the doming phenomenon of the shadow mask (32).

〔Effect of the invention〕

As described above, according to the present invention, a color picture tube of extremely high quality can be provided.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a color picture tube of the present invention, in which FIG. 1 is an exploded explanatory view, FIG. 2(a) is an enlarged plan view of a shadow mask, and FIG. 2(b) is an enlarged plan view of a shadow mask. Figure 2 (a) A-A
A cross-sectional view taken along the line, No. 2 (c) is a cross-sectional view taken along the line shown in Fig. 2 (
a) is a sectional view taken along line B-B, Figures 3 to 6 are diagrams showing conventional color picture tubes, Figure 3 is an exploded explanatory view, and Figure 4 is a shadow An explanatory diagram of the utility drift due to overall doming of the mask, FIG. 5 is an enlarged plan view of the first to second masks, FIG. 6 is a cross-sectional view of FIG. 5 taken along the line C-C, FIG. 7 is an explanatory cross-sectional view showing an example of a shadow mask designed to reduce 1.marking. ■, 31... Panel 11.31□... Phosphor screen 2, 22.32... Shadow mask 2a, 22a, 32a... Rectangular through hole portion 25, 3
5...Glass layer agent Patent attorney I'2 - Male Figure 7 -IAI-

Claims (2)

[Claims] (1) A phosphor screen consisting of phosphor layers of three colors adhered to the inner surface of the panel, a shadow mask having a large number of rectangular through-holes disposed close to the phosphor screen, and phosphor layers of the three colors. an electron gun that emits an electron beam that causes the phosphor layer to selectively emit light through the rectangular through hole, and the rectangular through hole is connected to a large hole on the phosphor screen side and the electron gun. In the color picture tube, the bridge part and the band part are arranged regularly through a bridge part on the short side and a band part on the long side, respectively. 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 bridge portion side, including the surface where the small hole is placed, and on the side wall of the small hole on the band portion side. (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.