| 简介 |
This invention provides a white LED having color reproducibility comparable to that of cold-cathode tubes and having improved brightness, and a backlight and a liquid crystal display device comprising the white LED. The white LED comprises at least one luminescent element selected from ultraviolet luminescent diodes, violet luminescent diodes, ultraviolet luminescent lasers, and violet luminescent lasers, and a fluorescent substance layer. In the fluorescent substance layer, a green fluorescent substance satisfies formula 1, a blue fluorescent substance satisfies formula 2 or 3, and a red fluorescent substance satisfies formula 4 or 5. A trivalent cerium and terbium activated rare earth boride fluorescent substance represented by formula 1 : M1-x-yCexTb yBO3 wherein M represents Sc, Y, La, Gd or Lu; and 0.03 < x < 0.3 and 0.03 < y < 0.3. A divalent europium activated halophosphate fluorescent substance represented by formula 2 : (M2, Eu) 10(PO4)6·Cl2 wherein M2 represents Mg, Ca, Sr, or Ba, or a divalent europium activated aluminate fluorescent substance represented by formula 3 : a(M31, Eu)O·bAl2O 3 wherein M3 represents Mg, Ca, Sr, Ba, Zn, Li, Rb or Cs; and 0 < a, 0 < b, and 0.2 <= a/b <= 1.5. A europium activated lanthanum oxysulfide fluorescent substance represented by formula 4 : (La1-x, Eux)2O2S wherein 0.01 < x < 0.15, or a europium activated yttrium oxysulfide fluorescent substance represented by formula 5 : (Y1-x, Eux)2 O2S wherein 0.01 < x < 0.15.
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