JPH05132669A - Pigment-adhered blue color-emitting fluorescent material and color cathode ray tube - Google Patents

Abstract

PURPOSE:To provide the subject fluorescent material excellent in the fastness, chemical stability and reflection spectrum characteristics and useful for color cathode ray tubes having high contrast fluorescent surfaces, etc., by adhering a CoO-ZnO-SiO blue pigment to the surface of a blue color-emitting fluorescent material. CONSTITUTION:A silver-activating zinc sulfide blue color-emitting fluorescent material is mixed with distilled water to form a slurry, which is mixed with a CoO-ZnO-SiO pigment as a blue pigment and with an aqueous solution containing gelatin and acacia gum as binders at a temperature of 45 deg.c. The mixture is adjusted to a pH of 4.1 with acetic acid, naturally cooled to room temperature, and subsequently cured with a 50% glutar aldehyde aqueous solution. The pigment thus produced is adhered to the surface of a blue color- emitting fluorescent material to provide the objective pigment-adhered blue color-emitting fluorescent material in which the blue pigment excellent in the fastness, chemical stability and reflection spectrum characteristics is adhered and which is useful for color cathode tubes, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigmented blue light emitting phosphor suitable for a phosphor film such as a color cathode ray tube and a color cathode ray tube provided with a blue light emitting phosphor film containing blue pigment particles on the inner surface of a face plate.

[0002]

2. Description of the Related Art In order to improve the contrast of an image on a color cathode ray tube, a fluorescent display tube, or the like, a method using a pigmented phosphor in which filter particles that absorb reflection of external light on a phosphor screen is attached to the surface of the phosphor, and A method of using colored glass for a face plate of a cathode ray tube is known. The method of using colored glass for the face plate of the cathode ray tube is by reducing the transmittance of the glass,
Although the contrast can be relatively easily selected in the practical range, the ratio of absorbing not only the external light but also the light emitted from the fluorescent film is high, so that the brightness is significantly lowered. Further, the method of using the pigmented phosphor for the fluorescent film is an effective method for improving the contrast without reducing the brightness of the screen as much as possible.

By the way, the above filter material is sometimes used to sharpen the emission spectrum of the phosphor. This filter material is required to have a high transmittance in the emission wavelength region of the phosphor and a low transmittance in other wavelength regions. Due to this characteristic of transmittance, it is possible to absorb a light component that does not match the light emission of the phosphor itself and improve the contrast under bright outside light. In the blue light emitting phosphor, a pigment that absorbs as little as possible near the emission peak of 450 nm and that absorbs as much as possible in other wavelength regions may be used.

As a blue pigment of this kind, Japanese Patent Laid-Open No. 54-2
Ultramarine (3NaAl ・ SiO ₂・ Na ₂
S ₂ ), dark blue (Fe ₄ [Fe (CN) ₆ ] ₃・ nH
₂ O), cobalt aluminate (CoO ・ nAl ₂ O ₃ ).
, Cerulean blue (CoO.nSnO ₂ ), copper sulfide (CuS), etc. have been proposed. However, generally used cobalt aluminate is not effective for the purpose of improving the contrast because its body color does not match the emission spectrum of the blue phosphor, and in particular, its reflectance near 490 nm is high.

Further, although some of the ultramarine blues that are practically used have excellent characteristics as compared with cobalt aluminate, they have extremely poor chemical stability, so that they are attached to a phosphor or applied to a cathode ray tube. Has the drawback of fading. In order to prevent this discoloration, a method of coating a ultramarine pigment with a silicic acid compound is also known, but when it is applied to a cathode ray tube, its body color is significantly changed by electron beam irradiation, and the peak of the emission spectrum of the fluorescent screen is increased. Has the drawback of shifting.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned drawbacks and provides a blue pigment excellent in fastness, chemical stability and reflection spectrum characteristics, which is excellent when applied to a cathode ray tube. An object of the present invention is to provide a pigmented blue light emitting phosphor capable of emitting blue light and a color cathode ray tube provided with a blue light emitting phosphor film containing the above blue pigment on the inner surface of a face plate.

[0007]

The present invention provides a pigmented blue light emitting phosphor in which a blue pigment is attached to the surface of a blue light emitting phosphor, and CoO.ZnO.SiO _{2 is} used as the blue pigment.
In a color cathode-ray tube equipped with a blue light-emitting phosphor with a pigment and a blue light-emitting phosphor film containing blue pigment particles on the inner surface of a face plate, CoO.ZnO.SiO is used as the blue pigment particles. A color cathode ray tube characterized by using a ₂ type pigment.

Here, the CoO.ZnO.SiO ₂ type pigment is usually a raw material containing Co, Zn and Si.
It is obtained by firing at a temperature of 0 ° C. or higher for several tens of minutes to several tens of hours, cooling and then pulverizing, and is a mixture of respective oxides or a complex oxide thereof, a mixture of cobalt silicate and zinc silicate, or both. Of solid solution, and further, a mixture thereof and the like. Note that xCoO · yZn
The composition ratio of O · zSiO ₂ pigment is 0.05 ≦ x / z ≦
1.5, 0.1 ≦ y / z ≦ 2.0 range (particularly 0.2
≦ x / z ≦ 1.0, 0.3 ≦ y / z ≦ 1.7). If it deviates from this range, the color tone changes, and it is not suitable as a blue pigment to be combined with a blue-emitting phosphor. The composite oxide includes a mixture of respective oxides or a double oxide thereof, a mixture of cobalt silicate and zinc silicate, a solid solution of both, and a mixture thereof.

If necessary, various fluxes and other elements may be added during the firing of the above pigment. Specifically, Li, Na, K, Ca, Mg, Ba, Fe, N
i, Cu, Mn, Ti, V, Al, Sn, Sb, Cr,
Pr etc. may be contained. These elements can be added in the range of about 10% by weight or less. If it exceeds this range, it becomes impossible to obtain a preferable color tone as a blue pigment.

The method for synthesizing this blue pigment is not particularly limited, but for example, it can be synthesized by the following method. (1) Dry Mixing and Firing Method Raw materials containing Co, Zn and Si are blended in a predetermined ratio and mixed by a ball mill, and then 1000 ° C to 1200 ° C.
It is obtained by firing at a temperature of several tens of minutes to several tens of hours, cooling, pulverizing, and classifying.

(2) Coprecipitation method An alkaline aqueous solution is added to an aqueous solution containing cobalt and zinc to coprecipitate cobalt and zinc as hydroxides, and water is replaced with an organic solvent, and then silicon oxide is precipitated by hydrolysis. Is a method of depositing on the surface of the above and baking in air at about 800 to 900 ° C (see Japanese Patent Application No. 3-240237). As the cobalt and zinc compounds used for adjusting the aqueous solution here, chlorides, fluorides, iodides, bromides, sulfates, nitrates and the like can be used, and as the organic solvent for water displacement, ethanol, Methanol or the like can be used, and silicic acid alkoxide or the like can be used as the silicon raw material.

(3) Coprecipitation / dry mixing firing method An organic compound which dissolves itself in water in an aqueous solution containing cobalt and zinc and reacts with cobalt and zinc to form a sparingly water-soluble or water-insoluble substance is a precipitant. Is added as co-precipitate, cobalt and zinc are co-precipitated, dried, silicon oxide is mixed, and the mixture is fired in the range of about 900 to 1000 ° C. in air (see Japanese Patent Application No. 36890/1992). The aqueous solution containing cobalt and zinc used here is the same as the above coprecipitation method. As a precipitant, it dissolves in water and reacts with cobalt and zinc to form a poorly water-soluble or water-insoluble substance. It is preferable to use an organic compound such as oxalic acid or tartaric acid. Further, as the silicon oxide, it is preferable to use an anhydride of ultrafine particles having a specific surface area of 100 m ² / g or more, which is more excellent in reactivity.

The blue light-emitting phosphor that can be used in the present invention has a major part of the emission spectrum within the range of 380 to 500 nm, and specifically, it is a silver-activated zinc sulfide-based phosphor [ZnS: Ag, X (X is halogen or A
l), ZnS: Ag, M, X (M is Ga, In, etc., X is halogen or Al)], Y ₂ SiO ₅ : Ce, Ca ₂ B
₅ O ₉ Cl: Eu, (Ba _x Mg _1-x ) O.nAl ₂ O
₃ : Eu (0 ≦ x ≦ 1, 7 ≦ n ≦ 8), SrSi ₃ O _{8
Cl 4: Eu, CaWO 4,} CaWO 4: Pb, BaF
Examples include Cl: Eu, Gd ₂ O ₂ S: Tb, ZnS: Zn, and the like.

The amount of the above blue pigment attached to the blue light emitting phosphor is preferably in the range of 0.3 to 30% by weight. If the adhesion amount is below the lower limit, the filter effect is too small, and
When the upper limit is exceeded, the emission brightness becomes insufficient.

[0015]

The present inventors have used a pigment having a body color matching the emission spectrum of a blue light emitting phosphor for a fluorescent film of a cathode ray tube to deteriorate or discolor it even if it is irradiated with an electron beam for a long time in vacuum. As a result of various investigations on pigments having a small amount, it was found that the above CoO.ZnO.SiO ₂ system blue pigment satisfies the above conditions, and a pigmented blue light emitting phosphor to which the blue pigment is attached is applied to a face plate, The blue light emitting fluorescent film containing blue pigment particles, which is applied as a pigment layer between the face plate and the blue light emitting fluorescent film, can maintain the brightness and obtain a fluorescent screen with high contrast, and even under bright external light. We have found that we can provide an easy-to-read color CRT.

FIG. 1 shows xCoO.yZnO.zSiO.₂
Pigments (x = 0.36, y = 0.6, z = 1.0) and
Compare the diffuse reflectance spectra of cobalt aluminate pigments
2 is a graph showing a typical blue light emitting phosphor.
The emission spectrum of ZnS: Ag, Cl phosphor
It is a graph. As is clear from comparing FIG. 1 and FIG.
In addition, the emission spectrum of the phosphor and the diffuse reflectance of the pigment, that is, the body
Color is xCoO / yZnO from cobalt aluminate pigment
・ ZSiO₂It turns out that the pigments are more consistent
It In addition, cobalt aluminate pigment is around 490nm
Has a unique peak, but xCoO.yZnO.zSi
O ₂The pigment does not have such a peculiar peak and is 480 to 520.
Cobalt aluminate pigment with filter effect in nm
Turns out to be better.

FIG. 3 shows deterioration caused by electron beam irradiation. The xCoO.yZnO.zSiO ₂ pigment, the cobalt aluminate pigment, and ultramarine blue were applied to a metal plate, and the strength was 20 KV and 30 μA / cm ² . Change of the body color when irradiated with the electron beam of
It is shown by the y value. As is clear from FIG. 3, the body color changes greatly in the order of ultramarine blue and cobalt aluminate pigments, but the xCoO.yZnO.zSiO ₂ pigment shows almost no change, and has robustness and chemical stability. It turns out to be excellent. This means that the body color and the emission color do not change even when used for a long time in a cathode ray tube or the like, and is extremely effective in practical use.

FIG. 6 is a partially cutaway side view of the color cathode ray tube of the present invention, and FIG. 7 is an enlarged cross-sectional view of the main part of the phosphor screen of FIG. The formation of the pigment layer on the face plate can be performed by using the photolithography technique as in the case of forming the fluorescent film. First, a first pigment slurry such as a green pigment and a photosensitive binder such as ammonium dichromate (hereinafter referred to as ADC) and polyvinyl alcohol (hereinafter referred to as PVA) are formed on the inner surface of the face plate 1 on which the black matrix 2 is formed in advance. ) Is applied and dried to form a film, which is exposed through a shadow mask and developed to form the green pigment layer 3 in a predetermined pattern. Then a second pigment slurry, for example,
Using the blue pigment slurry in which the blue pigment and the photosensitive binder are mixed, the blue pigment layer 4 is formed in a predetermined pattern at a position different from the green pigment layer 3 in the same procedure as above. Further, using a third pigment slurry, for example, a red pigment slurry, the red pigment layer 5 is formed in a predetermined pattern at a position different from the green pigment layer 3 and the blue pigment layer 4 in the same procedure as described above.
To form. Then, a green phosphor, a blue phosphor, and a red phosphor are applied on the pigment layers of the respective colors by a photolithography technique to form a green phosphor picture element 6, a blue phosphor picture element 7 and a red phosphor picture element. 8 is formed, and an aluminum film is further vapor-deposited thereon to form a metal pack 9 to complete the phosphor screen on the face plate 1. A panel 10 provided with this face plate 1 is sealed to a funnel 11 and an electron gun 12 is attached to complete a color CRT.

[0019]

【Example】

Example 1 To 100 parts of silver-activated zinc sulfide blue light emitting phosphor, 100 parts of distilled water was added to form a slurry, and xCoO 2 was added.
.YZnO.zSiO ₂ pigment (x = 0.36, y = 0.
6, z = 1.0) 1 part was added and heated to 45 ° C.,
Add 0.36 parts of gelatin and 0.3 parts of gum arabic as an aqueous solution as a binder, and add pH with acetic acid.
Was adjusted to 4.1 and allowed to cool to room temperature, and then 7.5 parts of a 50% glutaraldehyde aqueous solution was added to cure the binder. In addition, the amount of the above-mentioned pigment adhered is 3 parts, 5 parts,
A pigment was similarly attached by changing to 7 parts to obtain a pigmented phosphor of the example. Further, for comparison, 1 part, 3 parts, 5 parts, and 7 parts of cobalt aluminate were respectively attached instead of the above-mentioned pigments in the same manner as in the above-mentioned example to obtain a pigmented phosphor of the comparative example. FIG. 4 shows the diffuse reflectances at 490 nm and 450 nm of the two types of pigmented phosphors of the two types of Examples and Comparative Examples, and the vertical axis represents (490 nm reflectance) / (450 nm reflectance). This is a graph in which the horizontal axis represents the amount of pigment attached. As is clear from FIG. 4, the example shows a smaller value than the comparative example,
You can see that the filter effect is great. In addition, FIG.
FIG. 6 is a graph comparing diffuse reflectance distributions of a phosphor to which 7 parts of pigment is attached in the above example and a phosphor to which 3 parts of pigment is attached in the comparative example. As is clear from FIG. 5, the phosphor of the comparative example shows a peak in the vicinity of 490 nm, but the phosphor of the example does not have such a peak and is in good agreement with the emission spectrum of the phosphor. I understand.

(Example 2) 5% by weight of xCoO.yZnO.zSiO ₂ composite oxide (x = 1.0, y = 1.0, z = 1.0) produced by a dry mixing firing method as a blue pigment,
PVA (degree of polymerization 2400, degree of saponification 88%) 2% by weight,
Using a pigment slurry having a composition of 0.15% by weight of sodium dichromate (manufactured by Kanto Chemical Co., Inc.), 0.15% by weight of sodium dichromate, 0.03% by weight of a surfactant, and the balance water, a face was formed by a photolithography method. A blue pigment layer having an average thickness of 1 μm was formed on the inner surface of the plate. Next, ZnS: Ag, Cl was used as a blue light emitting phosphor, and a blue phosphor pixel was formed on the blue pigment layer by a conventional method. For comparison, instead of the above blue pigment, cobalt aluminate and ultramarine blue were applied in the same thickness as in the above example to form a phosphor screen in the same manner as in the above example.

(Comparison of Brightness and Contrast) When the brightness and the contrast of the phosphor screens of the above Examples and Comparative Examples were measured, the results shown in Table 1 were obtained. Note that the contrast value is the ratio of the brightness of the bright part (the part that shines white in the mounted state) and the brightness of the dark part (the part that does not emit light in the mounted state) when external light is applied to the face plate surface. As shown. As is clear from Table 1, the phosphor screens of the examples showed less decrease in white luminance and maintained high contrast as compared with the two comparative examples.

[0022]

[Table 1]

[0023]

EFFECTS OF THE INVENTION By adopting the above constitution, the present invention provides a blue pigment having a diffuse reflectance matching the emission spectrum of a blue-emitting phosphor, and having excellent fastness and chemical stability. Can be attached to a blue-emitting phosphor, and
It has become possible to provide an excellent blue light-emitting phosphor that is free from deterioration and color shift in the attaching process, the applying process and the use of a cathode ray tube. Further, by providing the layer of the above-mentioned blue pigment between the face plate and the blue light emitting fluorescent film, it is possible to maintain the brightness and obtain a fluorescent screen with high contrast, and as a result, the screen of the screen can be displayed even under bright illumination. It is now possible to provide easy-to-read color CRTs.

[Brief description of drawings]

[Figure 1] Cobalt aluminate pigment and CoO / ZnO / S
3 is a graph showing a diffuse reflectance spectrum of an iO ₂ pigment.

FIG. 2 ZnS: Ag, which is a typical blue light-emitting phosphor,
7 is a graph showing an emission spectrum of a Cl phosphor.

FIG. 3 Ultramarine blue, cobalt aluminate pigment, and CoO
FIG. 5 is a graph showing the color shift when irradiating a ZnO / SiO ₂ pigment with an electron beam by x and y values in the CIE method.

FIG. 4 Cobalt aluminate pigment and CoO / ZnO
FIG. 5 is a graph showing the ratio R ₄₉₀ / R ₄₅₀ of the peaks of the diffuse reflectance spectrum at 490 nm and 450 nm for the blue light emitting phosphor to which the SiO ₂ pigment is attached.

FIG. 5: Cobalt aluminate pigment and CoO / ZnO
- is a graph showing the diffuse reflectance distributions of blue-emitting phosphor of the SiO ₂ type pigment is deposited.

FIG. 6 is a partially cutaway side view of a color CRT which is one specific example of the present invention.

7 is an enlarged cross-sectional view of a main part of the phosphor screen of FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display area C09K 11/63 CPL 6917-4H 11/64 CPP 6917-4H 11/68 CQC 6917-4H 11/79 CQC 6917-4H 11/84 CPD 6917-4H H01J 29/20 7129-5E

Claims (4)

[Claims] 1. A pigmented blue light-emitting phosphor obtained by adhering a blue pigment on the surface of a blue light-emitting phosphor, wherein a CoO.ZnO.SiO ₂ pigment is used as the blue pigment. Phosphor. 2. A CoO.ZnO.SiO ₂ based pigment L
i, Na, K, Ca, Mg, Ba, Fe, Ni, Cu,
The blue light-emitting phosphor with a pigment according to claim 1, wherein a blue pigment containing Mn, Ti, V, Al, Sn, Sb, Cr, Pr or the like is used. 3. The composition ratio of xCoO.yZnO.zSiO ₂ pigment is 0.05 ≦ x / z ≦ 1.5, 0.1 ≦ y / z.
3. A range of ≦ 2.0, wherein the range is ≦ 2.0.
A blue light emitting phosphor with a pigment as described above. 4. A color CRT having a blue light emitting fluorescent film containing blue pigment particles on the inner surface of a face plate, wherein a CoO.ZnO.SiO ₂ pigment is used as the blue pigment particles.