JPH06336587A - Production of stimulable phosphor - Google Patents

Abstract

PURPOSE:To produce a stimulable phosphor for dispersed EL having a high luminance, a high efficiency, and a long life. CONSTITUTION:A zinc sulfide-based stimulable phosphor for dispersed EL is produced through two baking steps provided that the intermediate stimulable phosphor formed by activating copper obtained at the first baking step is treated with a wet ball mill to break up fused particles and simultaneously to generate defects in stimulable phosphor particles by the impact force of the treatment to thereby facilitate the formation of a conductive layer at the subsequent second baking step. Eliminating fused particles improves the efficiency of the resulting phosphor, and facilitating the formation of the conductive layer contributes to high luminance and long life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a phosphor, and more particularly to a method of manufacturing a phosphor for a dispersion type EL, which has high brightness, high efficiency and long life.

[0002]

2. Description of the Related Art Conventionally, in a dispersion type EL phosphor, a copper compound is added as an activator to zinc sulfide, and a halide is added as a co-activator, and the first firing is performed at 1000 ° C. to 1200 ° C. And then re-baked at a relatively low temperature of 600 ° C. to 900 ° C. (see, for example, Japanese Patent Laid-Open No.
2-61294).

[0003]

By the way, the phosphor obtained by the conventional manufacturing method contains a lot of particles in which the particles are fused to each other in the first firing, and even if it reaches a finished product. Since it is not improved, there is a drawback that current leakage occurs at the fused portion when an electric field is applied, leading to a decrease in luminous efficiency.

[0004] The obtained phosphor in the conventional manufacturing method, formation of the conductive layer in the particles (Cu _x S) is insufficient, not applied effective electric field to the luminescent center, becomes low brightness Further, there is a drawback that life characteristics are deteriorated due to diffusion of Cu in the conductive layer when the EL panel is driven.

An object of the present invention is to provide a method for producing a phosphor having high brightness, high efficiency and long life, which solves the above problems.

[0006]

In order to solve the above problems, the method for producing a phosphor of the present invention comprises a step of producing an intermediate phosphor by firing a mixture of a base material and an additive. And a step of subjecting the intermediate phosphor to a wet ball mill, and a step of re-baking at a temperature lower than the above-mentioned baking.

Further, the diameter of the balls used in the ball milling step is 0.1 to 5 mm.

[0008]

According to the present invention, by applying a wet ball mill after the first firing, it is possible to loosen the intermediate phosphor in which the particles are fused to each other, which occurs at the fused portion when an electric field is applied. By suppressing unnecessary leak current, the light emission efficiency can be improved.

Further, by introducing a lattice defect into the phosphor particles by an impact force and a shearing force obtained from a wet ball mill, and facilitating the formation of a conductive layer in the subsequent second firing, a high brightness and a long duration can be obtained. It is possible to obtain a long-life phosphor.

In particular, when a small-diameter ball having a diameter of 0.1 to 5 mm is used, the effect of the ball mill is exerted evenly on individual phosphor particles, and the impact force for controlling lattice defects can be reduced. As a result, the particles are not crushed, and the above effects are further improved.

[0011]

EXAMPLES The method for producing the phosphor of the present invention will be described below.

First, 0.05 to 0.2 mol% ZnS of copper sulfide as an activator and 5 to 20 mol% ZnS of magnesium chloride as a coactivator are added to zinc sulfide (ZnS),
Baking is performed at 1000 ° C to 1200 ° C for 3 to 8 hours. After washing with water, 100 g of the obtained intermediate phosphor and 100 ml of water were added.
A proper amount of alumina balls of 1 to 5φ is mixed and ball mill is performed for 1 hour. After drying, baking was performed again at 600 to 800 ° C. for 1 to 3 hours, and then copper sulfide and the like adhering to the surface of the phosphor was removed with a 10% sodium cyanide aqueous solution to obtain an EL phosphor.

An EL panel was manufactured using the phosphor obtained by the above-mentioned manufacturing method, and an AC voltage was applied to the EL panel to measure the brightness and life characteristics. The results are shown in FIGS. The luminance and efficiency (= luminance / power) of the product of the present invention are significantly improved as compared with the conventional product, as is clear from the figure. In addition, the life was remarkably improved, and in comparison with constant voltage driving, the luminance half time was about 200 hours, which was about twice as long as the conventional product for about 100 hours.

[0014]

As described above, according to the present invention, the intermediate phosphor obtained after the first firing is subjected to a wet ball mill in the step of producing the dispersion type EL phosphor, and then the first firing is performed. Baking at a lower temperature can provide a phosphor having remarkably high brightness, high efficiency, and long life.

[Brief description of drawings]

FIG. 1 EL using a phosphor produced according to the present invention
Panel brightness-power characteristics

FIG. 2 EL using a phosphor produced according to the present invention
Panel life characteristics diagram

Claims (2)

[Claims] 1. A step of producing an intermediate phosphor by firing a mixture of a base material and an additive, a step of wet-milling the intermediate phosphor, and a step of re-firing at a temperature lower than the firing. A method for producing a phosphor, which comprises: 2. The ball used in the ball milling step has a diameter of 0.1 to 5 mm or less.
A method for producing the described phosphor.