JPH05171142A - Green-light emitting fluorescent material - Google Patents

Abstract

PURPOSE:To obtain the subject fluorescent material emitting green light having improved color purity and useful for color CRT, etc., by attaching a light-green pigment to the surface of Cu-doped zinc sulfide fluorescent particles. CONSTITUTION:The objective fluorescent material is produced by attaching 0.05-5wt.% of Pr2O3 and a light-blue pigment composed mainly of TiO2-CoO-Al2 O3-LiO2 to the surface of Cu-doped zinc sulfide fluorescent particles. The amount of Cu dopant of the Cu-doped zinc sulfide fluorescent material is preferably 4X10<-5> to 2X10<-4>g (40-200ppm).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green light emitting phosphor, and more particularly to a green light emitting phosphor which is suitable for a color cathode ray tube and emits green light with improved color purity.

[0002]

2. Description of the Related Art As the information-oriented society advances, for example in high-definition televisions and computer terminal displays, there is a strong demand for improvement of the color reproduction range of images. Particularly in fields where color expression is important, such as clothing design and print publishing fields, the color difference of products poses a graphic problem. And, as a phosphor for a color cathode ray tube normally used for this type of image display, a silver activated zinc sulfide phosphor (ZnS: Ag) as a blue light emitting phosphor, and a copper activated zinc sulfide phosphor as a green light emitting phosphor ( ZnS: Cu), europium activated yttrium oxysulfide phosphor (Y
₂ O ₂ S: Eu) is used.

[0003]

By the way, in a color cathode ray tube having a phosphor layer composed of a mixture of the above-mentioned three kinds of phosphors, the color gamut thereof is 3 connecting the three points of the CIE color system. It is inside the prism and the chromaticity points that represent green are relatively closer to the yellowish-green direction. In other words, there is a demand for a green-emitting phosphor having a large x value in the CIE color system, reproduction of vivid green is not always sufficient, and a small x value and a high y value.

In response to such a demand, a manganese-activated zinc silicate phosphor (Zn ₂ SiO ₄ : Mn) has been developed as a green light emitting phosphor. However, the above Zn ₂ SiO ₄ : Mn
The phosphor has a low emission brightness of about 50% as compared with ZnS: Cu, and has a long afterglow time, which causes a phenomenon that an image flows in a fast moving image. Furthermore, although a rare earth phosphor has been developed as a green light emitting phosphor, there are problems in terms of brightness and emission color. The present inventors, as a result of proceeding with the investigation in response to such a situation, when a light green pigment is attached to the surface of ZnS: Cu particles, which is a phosphor that emits green light,
It has been found that the reproduction of bright green color is easily achieved.

The present invention is based on the above findings, and has a small x value and a high y value of the luminescent color in the CIE color system, and exhibits high brightness. Therefore, it is strongly demanded to improve the color reproduction range of an image. An object of the present invention is to provide a green-emitting phosphor suitable for emitting the green component of the above.

[0006]

The green light emitting phosphor of the present invention is characterized in that a light green pigment is attached to the surface of Cu activated zinc sulfide phosphor particles, and the light green pigment is Pr ₂ O ₃
Is preferred as the main component, and it is further desirable that the light green pigment also contains a light blue pigment having TiO ₂ —CoO—Al ₂ O ₃ —LiO ₂ as the main component.

In the green light emitting phosphor according to the present invention, it is preferable that the light green pigment is contained in an amount of 0.05 to 5% by weight based on the Cu-activated zinc sulfide phosphor particles. Activated zinc sulfide phosphor has a Cu activation amount of 4 × 10 ^-5
~ 2 × 10 ^-4 grams (40-200ppm) is desirable.

Explaining the structure of the present invention, first, in terms of the Cu activation amount of the Cu-activated zinc sulfide phosphor forming the matrix, the relationship between the Cu activation amount and the brightness is as shown in FIG. 1 (a). Also, the relationship between the Cu activation amount and the x and y values of the CIE color system is as shown in Fig. 1 (b). When the Cu activation amount is less than 40 ppm, the y value decreases greatly. Purity also decreases. On the other hand, when the Cu activation amount exceeds 200 ppm, the brightness decreases, the x value also increases, and the emission color shifts to the yellow-green direction, making it impossible to obtain clear green emission. Here, the more preferable amount of Cu activation is 50 to 100 ppm.

Next, in terms of the adhesion of the light green pigment,
For example, in the case of a green-emitting phosphor having 1.0% by weight of a light green pigment, such as Pr ₂ O ₃ , adhered to the surface of a zinc sulfide phosphor having a Cu activation of 80 ppm, the reflection spectrum of the green-emitting phosphor is the curve shown in FIG. 2A and the emission spectrum is as shown by the curve B in FIG. 2, and the emission spectrum of the Cu sulfide phosphor having a Cu activation rate of 80 ppm without attaching the light green pigment to the surface (see FIG. 2). The color purity is superior to that of the curve C). That is, as is clear from FIG.
In the case of a zinc sulfide phosphor with a light green pigment on the surface, the filter effect of the pigment selectively absorbs the emission of light with a long wavelength of 580 nm or more and the emission of light with a wavelength of 500 nm or less. Is being improved. Here, examples of the light green pigment include PrF _{3 and the} like in addition to Pr ₂ O ₃ described above.

On the other hand, the emission brightness of the green light emitting phosphor in which the weight ratio of Pr ₂ O ₃ attached to the surface of the zinc sulfide phosphor particles having a Cu activation amount of 60 ppm was changed, and the CIE color system (CIE emission color Every time)
The relationship between the x value and the y value of is as shown in FIGS. 3 (a) and 3 (b), respectively. That is, the amount of light green pigment attached is 0.
When the amount is less than 05% by weight, the x value is almost unchanged (the adhesion effect is not observed), and when the amount exceeds 5% by weight, the decrease in brightness becomes large. When the attached amount of the light green pigment is within the above range, x
Although the value decreases with the increase of the attached amount, on the other hand, the y value increases and the emission color shifts to the short wavelength side. Generally, the attached amount of the light green pigment is selected to be 0.1 to 2.0% by weight. These tendencies are similar in the Cu activation amount range of 40 to 200 ppm.

Further, in the present invention, it is possible to use a light blue pigment containing TiO ₂ —CoO—Al ₂ O ₃ —Li ₂ O as a main component in combination with the light green pigment. Can be improved. For example, zinc sulfide phosphor particles surface of Cu-activating quantity 60 ppm, pale blue pigments pale green pigment and _{TiO 2 -CoO-Al 2 O 3} -Li 2 O main component composed mainly of Pr ₂ O ₃ Reflection spectrum (curve D) and emission spectrum (curve E) of a zinc sulfide phosphor with mixed pigments attached
Was as shown in FIG. As can be seen from FIG.
The green emission from the Cu-activated zinc sulfide phosphor is selectively transmitted, so that the emission color purity is improved. Also the wavelength
Since the reflectance at 550 nm or more is reduced, the external light reflectance is reduced and the contrast characteristics are improved even when applied to the formation of a phosphor layer for a cathode ray tube, for example.

[0012]

The green light emitting phosphor according to the present invention emits a bright green component with high brightness by attaching a light green pigment to the surface of particles. Therefore, when applied (used) as a green-emitting phosphor component in a color cathode-ray tube or the like, where improvement of the color reproduction range of an image is strongly demanded,
Always and surely present the required display function that is easy to distinguish.

[0013]

EXAMPLES Examples of the present invention will be described below.

Example 1 A silica ball and pure water were added to Pr ₂ O ₃ powder and sufficiently stirred and dispersed to prepare a 10% pigment dispersion liquid in advance.
On the other hand, per 1 g of zinc sulfide (ZnS) powder, copper sulfate (CuSO ₄
・ 5H ₂ O) 2.36 × 10 ^-4 g, aluminum nitrate (Al (NO ₃ ) ₃
・ 9H ₂ O) 8.35 × 10 ^-4 g, potassium iodide (KI) as flux
1 × 10 ^-3 g, ammonium iodide (NH ₄ I) 3 × 10 ^-3 g
Was added to form a slurry and mixed and dried. Next, the dried / mixed product was housed in a quartz tube, the inside of the quartz tube was kept in a reducing atmosphere with hydrogen sulfide, and the mixture was baked at a temperature of 980 ° C. for 100 minutes to obtain a Cu-activated zinc sulfide phosphor.
1 kg of the Cu-activated zinc sulfide phosphor produced above was washed several times with pure water, dispersed and stirred in pure water, and 100 g of the previously prepared 10% pigment dispersion liquid was added to it. After mixing, 4 cc of acrylic emulsion resin (45%) was added and further stirred, and then diluted sulfuric acid was added to adjust the pH to 2-3. Then, after washing with pure water several times, the solid content is allowed to settle, the precipitated solid is dispersed in a ball mill, washed with water, filtered, dried, and sieved with a 400-mesh sieve to obtain a surface. A green light emitting phosphor having 1.0% by weight of the pigment applied was obtained.

The green-emitting phosphor obtained above emits chromaticity CIEx = 0.271, y = 0.620 when excited by electron beam.
And luminescence chromaticity CIE before pigment deposition, x = 0.281, y = 0.
The emission color was shifted to a shorter wavelength compared to 618, and the brightness was about 98% of that of the phosphor before the pigment was applied, and it was a highly efficient phosphor showing bright green light emission.

Example 2 A silica ball and pure water were added to a mixed pigment (mixing ratio 1: 1) of Pr ₂ O ₃ powder and TiO ₂ —CoO—Al ₂ O ₃ —Li ₂ O powder, and the mixture was thoroughly stirred. A 10% pigment dispersion was prepared in advance by dispersion. On the other hand, per 1 g of zinc sulfide (ZnS) powder, copper sulfate (CuSO ₄ / 5H ₂ O) 2.36 × 10 ^-4 g, aluminum nitrate (A
_{l (NO 3) 3 · 9H} 2 O) 8.35 × 10 -4 g, potassium iodide as a flux ^{(KI) 1 × 10 -3 g} , ammonium iodide (NH ₄ I)
3 × 10 ⁻³ g was added to form a slurry, which was mixed and dried. Then, the dry mixture was placed in a quartz tube, and the quartz tube was kept in a reducing atmosphere with hydrogen sulfide,
It was baked at a temperature of 980 ° C for 100 minutes to obtain a Cu-activated zinc sulfide phosphor.

Cu-Activated Zinc Sulfide Phosphor 1k Prepared Above
After washing g with pure water several times, disperse and stir in pure water, add 100 g of the previously prepared 10% pigment dispersion and mix well, then add acrylic emulsion resin (45%) 4cc After adding and stirring, dilute sulfuric acid is added to adjust the pH to 2-3.
Adjusted to. Then, after washing with pure water several times, the solid content is allowed to settle, and the precipitated solid is dispersed in a ball mill, washed with water, filtered, dried, and sieved with a 400-mesh sieve to obtain the surface. A green light emitting phosphor having 1.0% by weight of the pigment applied was obtained.

The green light-emitting phosphor obtained above emits chromaticity CIEx = 0.260, y = 0.623 when excited by electron beam.
And luminescence chromaticity CIE before pigment deposition, x = 0.281, y = 0.
The emission color purity was improved compared to 618, and the brightness was about 97% of that of the phosphor before the pigment was applied, and it was a highly efficient phosphor showing bright green light emission.

Example 3 A silica ball and pure water were added to a mixed pigment (mixing ratio 1: 2) of Pr ₂ O ₃ powder and TiO ₂ —CoO—Al ₂ O ₃ —Li ₂ O powder, and the mixture was thoroughly stirred. A 10% pigment dispersion was prepared in advance by dispersion. On the other hand, per 1 g of zinc sulfide (ZnS) powder, copper sulfate (CuSO ₄ / 5H ₂ O) 3.9 × 10 ^-4 g, aluminum nitrate (A
_{l (NO 3) 3 · 9H} 2 O) 1.4 × 10 -4 g, potassium iodide as a flux ^{(KI) 1 × 10 -3 g} , ammonium iodide (NH ₄ I)
3 × 10 ⁻³ g was added to form a slurry, which was mixed and dried. Then, the dry mixture was placed in a quartz tube, and the quartz tube was kept in a reducing atmosphere with hydrogen sulfide,
It was baked at a temperature of 980 ° C for 100 minutes to obtain a Cu-activated zinc sulfide phosphor. Cu activated zinc sulfide phosphor manufactured above 1 kg
Was washed several times with pure water, dispersed and stirred in pure water, 100 g of the previously prepared 10% pigment dispersion was added and mixed well, and then 4 cc of acrylic emulsion resin (45%) was added. After adding and further stirring, dilute sulfuric acid was added to adjust the pH to 2-3. Then, after washing with pure water several times, the solid content is allowed to settle, and the precipitated solid is dispersed in a ball mill, washed with water, filtered, dried, and sieved with a 400-mesh sieve to obtain the surface. A green light emitting phosphor having 1.0% by weight of the pigment applied was obtained.

The green-emitting phosphor obtained above emits chromaticity CIEx = 0.264, y = 0.620 when excited by electron beam.
And luminescence chromaticity CIE before pigment deposition, x = 0.281, y = 0.
The emission color purity was improved compared to 618, and the brightness was about 97% of that of the phosphor before the pigment was applied, and it was a highly efficient phosphor showing bright green light emission.

In the above, Pr ₂ O _{3 is} used as the light green pigment.
TiO ₂ -CoO-Al ₂ O ₃ powder, and as a pale blue pigment -
Li ₂ O powder was used.
₃ powder, and as a light blue pigment, for example, CoO-Al ₂ O
₃ powders may be used. Also, as a light green pigment, Pr ₂ O
₃ powder and PrF ₃ powder and a mixture _{of, TiO 2 -CoO-Al 2 O} 3 -Li 2 O powder and CoO-Al ₂ O ₃ as a pale blue pigment
You may use what mixed the powder.

[0022]

As can be seen from the above description, the green light-emitting phosphor according to the present invention is selectively absorbed by applying an appropriate amount of the light blue-green pigment on the surface of the particles, and has a narrow emission band. In addition to excellent green coloration, it exhibits good characteristics in which a decrease in brightness is suppressed. Moreover, since it is possible to lower the external light reflectance, the improvement and improvement of the contrast characteristics have been achieved at the same time. Therefore, when it is applied to a color display configuration, for example, it contributes to a significant improvement of the display function. become.

[Brief description of drawings]

FIG. 1 (a) is a curve diagram showing an example of the relationship between Cu activation concentration and emission luminance of a green light emitting phosphor according to the present invention, and (b) is a Cu activation concentration of a green light emitting phosphor according to the present invention. The curve figure which shows the example of a relationship of CIE luminescence chromaticity.

FIG. 2 is a curve diagram showing an example of a reflection spectrum, an emission spectrum of a green light emitting phosphor according to the present invention and an emission spectrum of a conventional green light emitting phosphor.

FIG. 3 (a) is a curve diagram showing an example of the relationship between the amount of light green pigment deposited on the green light emitting phosphor according to the present invention and the emission brightness, and FIG. 3 (b) is a light green color of the green light emitting phosphor according to the present invention. Pigment coverage and CIE
The curve diagram which shows the example of a relationship of luminescence chromaticity.

FIG. 4 is a curve diagram showing an example of a reflection spectrum and an emission spectrum of a green light emitting phosphor to which a light green pigment according to the present invention is attached.

[Explanation of symbols]

 None

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiromi Morikawa 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Electronic Engineering Co., Ltd.

Claims (5)

[Claims] 1. A green light emitting phosphor comprising a Cu-activated zinc sulfide phosphor particle surface and a light green pigment attached to the surface thereof. 2. Pr ₂ O on the surface of Cu-activated zinc sulfide phosphor particles.
A green light-emitting phosphor comprising a light green pigment containing ₃ as a main component attached thereto. 3. Pr ₂ O on the surface of Cu-activated zinc sulfide phosphor particles.
A green light-emitting phosphor characterized by being formed by adhering a light blue pigment containing ₃ and TiO ₂ —CoO—Al ₂ O ₃ —LiO ₂ as a main component. 4. The green light-emitting phosphor according to claim 1, 2 or 3, wherein the amount of the light green pigment deposited is 0.05 to 5% by weight based on the Cu-activated zinc sulfide phosphor particles. Green-emitting phosphor. 5. The green-emitting phosphor according to claim 1, 2, 3 or 4, wherein the Cu-activated zinc sulfide phosphor has a Cu activation amount of 4 × 10 ⁻⁵ to 2 × 10 ⁻⁴ g (40 to 200 ppm) is a green-emitting phosphor.