JPH0719538B2 - Picture tube - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a picture tube for exciting a fluorescent screen with an electron beam.

[Technical background of the invention and its problems]

A technique of adding color filter particles to the fluorescent surface of a color picture tube to reduce reflection of external light and improve image contrast is disclosed in US Pat. No. 3,308,326. The fluorescent surface of the color picture tube is red, which produces a color image.
Green and blue light-emitting phosphors are arranged in dots or stripes, and color filter particles of the same color as the emission color are mixed into each color phosphor, and the luminous efficiency is not significantly reduced. It greatly suppresses reflections and enhances the overall performance of the fluorescent screen.

The conventional phosphor screen with a color filter is the Japanese Examined Japanese Patent Publication Sho 57-3366.
As described in Japanese Unexamined Patent Publication (Kokai) No. 0, the surface of the phosphor particles constituting the phosphor screen is locally covered with small-diameter filter particles. That is, as shown in FIG. 4, color filter particles (42) having a particle diameter of 1/10 to 1/100 are locally attached to the surface of the phosphor particles (41). However, this filter particle is an electron beam (40) incident on the phosphor particle.
However, since it becomes a barrier, the energy loss is large, and when three color phosphors are used as in a color picture tube, the filter particles dropped from the phosphor particles are mixed with other color phosphors and the brightness decreases. There is much room for improvement, such as uneven brightness.

[Object of the Invention]

This invention eliminates the above-mentioned inconvenience, minimizes the loss of excitation energy by the filter particles, and prevents the particles from falling off from the phosphor particles, thereby improving the image contrast,
(EN) A video tube capable of improving brightness and preventing uneven brightness.

[Outline of Invention]

The present invention is characterized in that, in an image tube equipped with a phosphor screen and an electron gun for exciting and emitting the phosphor screen with electrons, filter particles are included in phosphor particles constituting the phosphor screen. The filter particle has a color similar to the emission color of the included phosphor particles, for example, in the case of a red-emitting phosphor, one having a red body color or exhibiting a black color is used, whereby the light absorption of the filter particle is It is maintained to have a greater effect on external light reflection than on emission. The particle size of the phosphor particles is 3μ from the viewpoint of emission characteristics and coating and adhesion.
m to 20 μm is preferable, on the other hand, the average particle size of the filter particles is 1/10 to 1/20 of the phosphor particles, that is, 0.01 μm to 1 μm, which is suitable for encapsulation in the phosphor particles.
The content also depends on the filter material, but is preferably 5% by weight or less.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a color picture tube, and a fluorescent screen (15) is provided on the inner surface of the panel (11) of the glass envelope (14) including the panel (11), the funnel (12), and the neck (13). It is formed by coating. A shadow mask (16) having a large number of holes is fixed near the fluorescent screen, while a neck (12) is fixed.
An electron gun (17) is installed in the interior so as to face the fluorescent screen (15) and the shadow mask (16).

As shown in FIG. 3, the phosphor screen (15) has a light absorption stripe layer (18) and a red light emitting phosphor layer (2) formed between them.
0), green light emitting phosphor layers (21) and blue light emitting phosphor layers (22) are arranged alternately. When the electron beam emitted from the electron gun (17) selectively strikes the phosphor screen (15) through the shadow mask (16), the phosphor is excited and emits light of a predetermined emission color.

The red-emitting phosphor layer (20) is composed of europium-activated yttrium oxysulfide (Y ₂ O ₂ S: Eu) phosphor particles, and red filter particles composed of red iron oxide (Fe ₂ O ₃ ) are included in the particles. To be done. That is, as shown in FIG. 1, the phosphor particles (23) are microcrystals having an average particle diameter of 5 to 20 μm, and the filter particles (24) are enclosed inside the crystals. The particle size of the filter particles does not have to be strictly specified, but practically it is in the range of 1/10 to 1/200 of the phosphor particles, and the selection range is wider than the conventional structure that adheres to the phosphor surface. It is possible to use a finer particle size.

4 and 5 show a conventional filter-coated phosphor,
4 shows a comparison with this embodiment, and in the conventional structure of FIG. 4, the depth t _{1 at} which the electron beam (40) penetrates the phosphor particles (41) is smaller due to the presence of the filter (42). In this embodiment of FIG. 5, since the filter (52) is inside, the electron beam (50) penetrates deeply into the phosphor particles (51) (t ₂ ) and the excitation efficiency can be increased. Also, in terms of the ability to absorb external light, the structure of FIG. 5 has a refractive index of the filter particles (52) such as red iron oxide that is close to the refractive index of the phosphor such as Y ₂ O ₂ S: Eu. There is no light reflection of the filter in the phosphor particles, and the external light entering the phosphor particles is captured and absorbed.

The filter-containing phosphor layer (20) of this embodiment can be manufactured as follows.

Yttrium oxide (Y ₂ O ₃ ), Europium oxide (Eu
Red iron oxide pigment simultaneously coprecipitate of each oxalates _{2 O 3) (Fe 2 O} 3)
0.2% by weight of the former was added and mixed, and the mixture was baked in a reducing atmosphere at about 900 to 1200 ° C. for 1 hour. Further, it was baked in hydrogen sulfide at 1100 ° C. for 1 hour. Predetermined particles were subjected to classification and surface treatment to obtain a phosphor composed of Y ₂ O ₂ S: Eu phosphor particles containing red iron oxide particles. As shown in FIG. 3, this phosphor was applied to a predetermined panel surface between the light absorption stripes (18) by a slurry method to obtain a red light emitting phosphor layer (20). This layer (20) is
About 7% improvement in red monochromatic brightness, and external light reflectance of the phosphor layer is 36%
From 32% to 32%. Moreover, red iron oxide particles do not mix with the phosphors of other colors, so that green, blue and luminance could be improved by about 2% after being manufactured.

A Y ₂ O ₃ S: Eu phosphor was produced in the same manner as in the example, using 10% by weight of red-colored, red-emitting calcium sulfide (CaS) phosphor particles in place of the red iron oxide pigment of 0.2% by weight. Then, when it was applied to the panel and evaluated, it was found that the brightness of the red monochromatic color was improved by about 10% and the external light reflectance was improved from 36% to 31% as compared with the conventional filter coating structure.

When 1% by weight of glass powder containing cadmium sulphide selenide was used in place of the red iron oxide pigment, the same evaluation as in the example was carried out. Was improved from 36% to 30%.

In the case of red-emitting phosphor, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, Z
n ₃ (PO ₄ ) ₂ : Mn, etc. as the base material, cadmium selenide, red iron oxide, chromium vermillion, chromium oxide coloring phosphor,
Filter particles such as colored glass may be used alone or in combination of two or more.

Copper sulfate (CuSO ₄ ), aluminum nitrate (Al (NO ₃ ) ₃ )
And zinc sulfide (ZnS) with a flux such as sulfur (S) and ammonium chloride (NH ₄ Cl) added with 1% by weight of chrome vermillion powder particles to the former and mixed, and under a reducing atmosphere, about 900 After calcination at ℃ ~ 1000 ℃ for 1 hour, after classification and surface treatment, ZnS containing green filter particles:
Cu phosphor particles were manufactured. This phosphor was applied to a panel by a slurry method and evaluated, and it was about 10 at a green monochromatic brightness with respect to a phosphor layer of a conventional structure coated with filter particles.
%, And the external light reflectance was also improved from 34% to 31%.

In the case of a green-emitting phosphor, including the above-mentioned examples, ZnS:
It is possible to combine Cu, ZnS: Au ・ Cu, ZnSiO ₄ : Mn, Y ₂ O ₂ S: Tb, InBO ₃ : Tb, etc. with nickel oxide, cobalt green, chromium oxide, vanadium oxide, green ceramic powder, etc. it can.

Zinc sulphide (ZnS) with a flux of silver sulfate (AgNO ₃ ) and ammonium chloride added to cobalt aluminate (Al ₂ O ₃
(1.5% by weight of nCoO), mixed and baked in a reducing atmosphere at about 900 ° C to 1000 ° C for 1 hour, then subjected to classification and surface treatment to obtain a phosphor containing ZnS: Ag phosphor particles containing a blue filter. Manufactured. This phosphor was adhered to the adhesive part of the photoresist film on the panel by a photoadhesive method to form a phosphor layer, which was evaluated. As a result, it was improved by about 8% in blue monochromatic brightness compared with the conventional filter coating structure. Reflectivity also ranges from 36% to 32
% Improved. According to this phosphor, there was no separation of blue filter particles seen in the conventional structure, and no pigment unevenness due to this was observed. In the case of a blue phosphor, ZnS: Ag can be used as a base material in combination with blue filter particles such as cobalt aluminate and ultramarine blue.

〔The invention's effect〕

As described above, the phosphor screen of the present invention is formed by the phosphor particles including the filter particles, and it is possible to improve the brightness and the contrast by improving the external light reflectance. Moreover, unlike the conventional filter coating structure, it is possible to avoid the complexity of the manufacturing process caused by the separation of the filter particles from the phosphor, and it is not necessary to add a large amount of the surface treatment agent to prevent the separation. The phosphor containing the filter can be manufactured by adding the filter particles in the conventional phosphor manufacturing process, and the manufacture of the phosphor does not need to be significantly changed. The particles of the filter can also be effective using black manganese oxide or graphite,
Further, the phosphor-containing phosphor of the present invention and the filter-covered phosphor can be used together to form a phosphor screen.

[Brief description of drawings]

FIG. 1 is a sectional view of phosphor particles for explaining an embodiment of the present invention, FIG. 2 is a sectional view for explaining one embodiment of the present invention, and FIG. 3 is a partially enlarged sectional view of FIG. 4 and 5 are schematic diagrams for explaining the conventional technique, and FIG. 5 is a schematic diagram for explaining the operation of the embodiment of the present invention. (15) ... Phosphor screen, (17) ... Electron gun, (20) ... Red emitting phosphor layer, (21) ... Green emitting phosphor layer, (22) ...
… Blue light emitting phosphor layer, (23) …… Phosphor particles, (24)…
... filter particles

Claims (3)

[Claims] 1. A video tube having a phosphor screen and an electron gun for exciting and emitting the phosphor screen, wherein the phosphor screen is a layer of phosphor particles having a predetermined particle size, and at least one of the phosphor particles is provided. An image tube characterized in that a part thereof contains filter particles of a color similar to the emission color of the phosphor particles or black. 2. The average particle size of the phosphor particles is 3 μm to 20 μm.
And the average particle size of the filter particles is 0.01 μm to 1 μm
The picture tube according to claim 1, wherein the phosphor particles are included in an amount of 5% by weight or less. 3. The picture tube according to claim 1, wherein the filter particles are colored phosphors.