White LED, backlight using the same, and liquid crystal display device

Abstract

Disclosed are a white LED, which has color reproducibility comparable with that of a cold-cathode tube and improved brightness, and a backlight and a liquid crystal display device comprising the white LED. The white LED comprises at least one light emitting element selected from ultraviolet light emitting diodes, purple light emitting diodes, ultraviolet light emitting lasers, and purple light emitting lasers, and a phosphor layer. The phosphor layer comprises a green phosphor satisfying formula 1, a blue phosphor satisfying formula 2 or 3, and a red phosphor satisfying formula 4 or 5: a trivalent cerium- and terbium-activated rare earth boride phosphor represented by formula 1: M1-x-yCexTbyBO3 wherein M represents at least one element selected from Sc (scandium), Y (yttrium), La (lanthanum), Gd (gadolinium), and Lu (lutetium); and x and y are respective numbers of 0.03<x<0.3 and 0.03<y<0.3; a divalent europium-activated halophosphate phosphor represented by formula 2: (M2, Eu)10(PO4)6.Cl2 wherein M2 represents Mg (magnesium), Ca (calcium), Sr (strontium), or Ba (barium), or a divalent europium-activated aluminate phosphor represented by formula 3: a(M3, Eu)O.bAl2O3 wherein M3 represents Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), Zn (zinc), Li (lithium), Rb (rubidium), or Cs (cesium); and a and b are respective numbers of 0<a, 0<b, and 0.2≦a/b≦1.5; and a europium-activated lanthanum oxysulfide phosphor represented by formula 4: (La1-x, Eux)2O2S wherein x is a number satisfying 0.01<x<0.15), or a europium-activated yttrium oxysulfide phosphor represented by formula 5: (Y1-x, Eux)2O2S wherein x is a number satisfying 0.01<x<0.15.

Dependencies are inferred from the claim text.