JPS61224243A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a color cathode-ray tube having high brightness by enlarging the diameter of electron beam pass hole section of shadowmask thereby suppressing production of heat from the shadowmask while maintaining constant the amount of electron beam to be projected from an electron gun. CONSTITUTION:A thin frit glass film 4 composed of PbO 75%, Zn 10%, B2O3 10% and other components, for example, is applied as thin insulation film from the minimum hole diameter section 3a to the wall section 3b at large hole side of fluorescent screen 2. Upon operation of color cathode-ray tube, the metal portion of shadowmask 3 will have high positive voltage (+) immdiately after operation and the incident electron beam 9 is slightly focused because of low potential on thin frit glass film 4. Upon continuous operation, the poten tial collision of electron beam 9 having negative potential (-) or the reflection beam 7 from the fluorescent screen 2 or the secondary electrons 8 and stabilize at negative potential (-) thus to focus the electron beam. Here, the thin frit glass film 4 is never formed at the side of shadowmask 3 facing against the electron gun.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a color cathode ray tube, and more particularly to a color cathode ray tube capable of improving brightness.

[Technical background of the invention and its problems]

The structure of a normal color cathode ray tube is shown in Figure 7.
Panel (31), fluorescent screen (32), shadow mask (3)
3), frame (34), inner shield (35),
Funnel (36), neck (37), electron beam (3)
It consists of an electron gun (38) that emits 9).

Next, the relationship among the panel (31), phosphor screen (32), shadow mask (33), and electron beam (39) will be explained with reference to FIG. That is, the fluorescent screen (32) is coated with a black coat (
40), a phosphor layer (41) that emits light in three colors, an aluminum vapor-deposited film (42), etc., and a shadow mask (3).
3) is provided with an electron beam passage hole (331) having a large hole diameter on the phosphor screen (32) side and a small hole diameter on the electron gun side. During operation of the color cathode ray tube, a part of the electron beam (39) hits the phosphor layer (41) through the electron beam passage hole (331) and emits light, but most of the electron beam (39) hits the shadow mask (33). As a result, the temperature of this shadow mask (33) is increased. In this case, as can be seen from the figure, the electron beam (39) passes through the electron beam passage hole (33+).
has a negative potential -, and the shadow mask (33) has a positive high potential -, so it is attracted and spread while the phosphor layer (41)
).

In order to increase the brightness of a color cathode ray tube with this structure, the current density of the electron beam (39) can be increased.
This results in a further increase in the temperature of the shadow mask (33), resulting in the problem of significant purity drift and deterioration of focus.

In addition, as another means, the electron beam passage hole (33+)
When the pore diameter is increased, the phosphor screen (
The diameter of the electron beam impinging on the phosphor layer (41) becomes larger, and the diameter of the electron beam impinging on the phosphor layer (41) increases, causing not only the phosphor layer (41) of the desired color but also the
There is a problem that there is a high possibility that the phosphor layer will collide with other phosphor layers adjacent to the phosphor layer.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems.
It is an object of the present invention to provide a bright color cathode ray tube that allows electron beams to strike only a phosphor layer of a desired color even if the hole diameter of an electron beam passage hole is increased.

[Summary of the invention]

That is, the present invention provides a color cathode ray tube that includes at least a panel on which a phosphor screen made of phosphor layers that emit light in three colors is formed, and a shadow mask disposed at a predetermined interval on the phosphor screen. A color cathode ray tube characterized in that a thin film of insulating material is coated on at least the side wall of the electron beam passage hole formed in the shadow mask on the side facing the phosphor screen, and is not coated on the side facing the electron gun. It is.

[Embodiments of the invention]

Next, the main parts of an embodiment of a color cathode ray tube according to the present invention will be explained with reference to FIG.

That is, the phosphor screen (2) formed on the panel (1) includes a black coat (10), a phosphor layer (11) that emits light in three colors,
This fluorescence =
3- Shadow mask (3) arranged at predetermined intervals on surface (2)
The electron beam passage hole (3I) is formed by etching from the electron gun side (not shown) and the fluorescent screen (2) side, so the minimum hole diameter part (3a) is not on the surface but in the middle of the plate thickness (5). Although it is generally farther away from the surface (2) side, there is an insulating layer on the large hole side wall (hereinafter simply referred to as the side wall) (3b) on the phosphor screen (2) side from the smallest hole diameter portion (3a). As a material thin film, for example, Pb075%, Zn010%, 8
A frit glass thin film (4) consisting of 20,310% other components is applied. The electron beam passage hole of this embodiment is similar to that shown by the dotted line in FIG. 8, and is larger than the usual one.

When the color cathode ray tube is operated with such a configuration, the metal portion of the shadow mask (3) is at a positive high voltage 10 immediately after operation, and the electron beam (9) is incident as shown by the broken line. However, since the frit glass thin film (4) has a low potential, it is somewhat focused.

If the operation continues in this state, the frit glass thin film (4)
is caused by the impact of a part of the negative potential electron beam (9) or by the fluorescent screen (
The potential further decreases due to the reflected beam (7) and secondary electrons (8) from 2), becomes stable at a negative potential, and acts to repel the electrons of the electron beam (9), so the electron beam It is focused as shown by the solid line.

In the normal operating state (current density) of a color cathode ray tube, focusing as shown by this solid line takes an extremely short time from immediately after operation until stabilization, so it can be considered that the start of operation = focusing. Here, the frit glass thin film (4) is not formed on the side of the shadow mask (3) facing the electron gun. This is because a part of the electron beam that should originally hit the vicinity of the electron beam passage hole (31) and be reflected toward the electron gun is deflected by the negative potential generated by the formation of the frit glass thin film. This is to prevent the phosphor from entering the phosphor screen side undesirably and hitting areas other than the original phosphor, thereby deteriorating the image quality.

In this way, in this example, by enlarging the conventional electron beam passage hole, the amount of electron beam emitted from the electron gun is not changed, the heat generation of the shadow mask is suppressed, and a bright color cathode ray tube can be used. It is possible to obtain.

Note that it is better to make the frit glass thin film (4) as thin as possible to prevent the incident electron beam (9) from hitting this frit glass thin film (4) and causing reflection and deteriorating the screen. ) and the frit glass thin film (4), the thicker the better to maintain the surface potential difference, but in the case of 18-21 inch television color cathode ray tubes, the voltage and shadow mask production should be
A value of about 15 microns was good. However, this depends on the working voltage, the pitch of the electron beam passage hole (31), and the plate thickness (5
), it may change depending on the deflection angle of the color cathode ray tube, etc.

In this case, as shown in Fig. 2, the frit glass thin film (4,) in a range that does not obstruct the passage of the electron beam (9) is the best for the focusing effect, but this frit glass thin film (41) is A frit glass thin film (4
2), a part of the electron beam (9) is reflected, resulting in deterioration of image quality, so it is preferable to make the thickness as thin as possible and as uniform as possible.

FIG. 4(a) shows that a frit glass thin film (4) is applied to the side wall (3b) and flat part (3C) on the phosphor screen side of another shadow mask (3), and the phosphor screen of the shadow mask (3) is The opposite surface is continuously covered with a frit glass thin film (4).

According to this embodiment, since the frit glass thin film (4) is also formed on the flat part of the shadow mask (3) on the phosphor screen side, the electric field strength is weaker than in the embodiment of FIG. 1, and the electron beam can be beamed more smoothly. It has the advantage that it can be focused and the beam spot is less likely to be deformed.

Furthermore, as shown in FIG. 4(b), it is also possible to form the flip 1 to the glass thin film (4) on a part of the side wall portion (3b) and the flat portion (3c), and in this case, as shown in FIG. ) has an effect similar to that of the embodiment shown in ().

Next, the frit glass thin film forming apparatus is shown in Figure 5.
~The process of forming a glass thin film will be explained with reference to FIG.

First, a shadow mask (23
) is placed on the support stand (26) inside the box (25).

Next, a solution prepared by dissolving, for example, nitrocellulose in isoamyl acetate is sprayed onto the phosphor screen side of the shadow mask (23) from the first nozzle (27) moving in the direction of the arrow (28), as shown in FIG. 6(b). The adhesive layer (22) shown is formed. In this case, since the adhesive layer (22) is applied by spraying, it is not applied to the side wall of the electron beam passage hole (23+) on the electron gun side.

Next, from the second nozzle (28), particles of frit glass (
After spraying 2'l I), leave it alone and let it fall onto Shadow Mask (23) and J2.

Next, particles of the frit glass are removed by spraying compressed air to form an adhesive layer (22
) only the frit glass particles (24+) remain. By heating in this state to evaporate the adhesive layer (22) and melt the frit glass particles (24+), and return the temperature to room temperature, a frit glass thin film (23) is formed on the shadow mask (23) as shown in FIG. 24) is formed.

In the embodiments described above, frit glass was used as the insulating material, but the material is not limited to this, and it goes without saying that soda glass or the like may also be used.

〔Effect of the invention〕

As described above, according to the present invention, since the electron beam convergence effect is obtained by the insulating material thin film, it is possible to enlarge the hole diameter of the electron beam passing hole portion of the first to second masks, thereby providing a bright color cathode ray tube. be able to.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of the main parts of the color cathode ray tube of the present invention.
FIGS. 2 and 3 are explanatory cross-sectional views showing different frit glass thin films, and FIGS. 4(a) and 4(b) are main parts of other embodiments of the present invention and still other embodiments. An enlarged sectional view, FIG. 5 is a sectional view for simple explanation of the frit glass thin film forming apparatus, and FIGS. 6(a), (b), (C) and (d
) is a cross-sectional view showing the steps of forming a frit glass thin film in order of process, FIG. 7 is a simplified cross-sectional view of a color cathode ray tube, and FIG. 8 is an enlarged cross-sectional view of the main part of FIG. 7. 1.31... Panel 2,32... Fluorescent screen 3
, 23. 33... Shadow mask 3, , 33. ...Electron beam passage hole portions 4, 4. ．． 4゜...Frit glass thin film 9.39...Electron beam
11.4] Phosphor layer agent Patent attorney I” Ni
- Male “Komi”: 1 Figure 6 Figure 8

Claims (3)

[Claims] (1) A color cathode ray tube comprising at least a panel on which a phosphor screen made of a phosphor layer that emits light in three colors is formed, and a shadow mask disposed at a predetermined interval on the phosphor screen, facing the phosphor screen. 1. A color cathode ray tube, characterized in that a thin film of an insulating material is coated on at least a side wall of an electron beam passage hole formed in the shadow mask on the side where the shadow mask is exposed. (2) The color cathode ray tube according to claim 1, wherein the insulating material thin film continuously covers a flat portion of the shadow mask that faces the phosphor screen. (3) The color cathode ray tube according to claim 1, wherein the insulating material thin film covers a part of the flat portion of the shadow mask facing the phosphor screen, and is continuous with the thin film on the side wall portion.