| 摘要 |
PURPOSE:To keep the brightness characteristic nearly uniform by making the grain size range distribution of phosphor powder 50-150% of the center grain size for 95wt.% or more of the whole weight. CONSTITUTION:Phosphor powder is mixed with water and put in a sorting tank 3, water 4 is poured from below at a preset speed and flooded from an opening 3a at the upper end. Phosphor grains 2 are applied with the buoyancy corresponding to the flow speed of the water and the gravitational force corresponding to the diameter. Therefore, grains with a small grain size are accumulated at the upper side, and grains with a large grain size at the lower side. Accordingly, if the portion in the necessary grain size range is extracted and dried, phosphor powder with the desired grain size distribution can be obtained. Stickiness is applied to the desired portion of a photosensitive adhesive agent layer formed on a substrate, the said phosphor powder is dispersed and stuck on this portion, and the powder stuck to the undesired portion is removed and recovered for re-use to form a stripe pattern. Even if the powder is thus recovered and repeatedly used, the distribution range of the grain size is extremely narrow, many small-sized grains with small luminous brightness are removed, thereby the brightness characteristic can be kept nearly uniform.
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