White LED, backlight using same and liquid crystal display

1. A white LED comprising:

an ultraviolet emitting diode or a purple light emitting diode; and

phosphors for emitting visible lights including blue light, green light and red light;

wherein an emission spectrum of said white LED has: a first luminescence peak in a blue light region having a wavelength of 440-460 nm; a second luminescence peak in a green light region having a wavelength of 510-530 nm; and a third luminescence peak in a red light region having a wavelength of 620-640 nm,

wherein said phosphor for emitting blue color light is an europium activated halo-phosphate phosphor expressed by a general formula 1: (Sr 1-x-y Ba x Ca y Eu z ) 10 (PO 4 ) 6 .Cl 2 in which x, y, z respectively satisfy the relations x<0.2, y<0.1 and 0.005<z<0.1,

wherein said phosphor for emitting green color light is an europium and manganese activated aluminate phosphor expressed by a general formula 2: (Ba 1-x-y-z Sr x Ca y Eu z ) (Mg 1-u Mn u ) Al 10 O 17 in which x, y, z, u respectively satisfy the relations x<0.5, y<0.1, 0.15<z<0.4 and 0.3<u<0.6, and

wherein said phosphor for emitting red color light is an europium activated lanthanum oxysulfide phosphor expressed by a general formula 3: (La 1-x-y Eu x M y ) 2 O 2 S in which M is at least one element selected from Sb and Sn, and x, y respectively satisfy the relations 0.01<x<0.15, and y<0.03.

2. The white LED according to claim 1 , wherein each of said first to third luminescence peaks in the blue, green and red light regions has a half band width of 50 nm or less.

3. The white LED according to claim 1 , wherein a luminescence intensity of said ultraviolet emitting diode or the purple light emitting diode has a peak value in a wavelength range of 360-410 nm.

4. A backlight comprising the white LED according to claims 1 or 2 .

5. A liquid crystal display comprising:

a white LED according to claim 1 ;

a backlight using the white LED; and

color filters for filtering blue, green, red color lights,

wherein: a percentage of a spectrum area composed of light components having been transmitted the green color filter and having wavelengths of 400 to 500 nm with respect to a spectrum area composed of light components having wavelengths of 400 to 600 nm is 15% or less; and

a percentage of a spectrum area composed of light components having wavelengths of 400 to 550 nm with respect to the spectrum area composed of light components having wavelengths of 400 to 600 nm is 90% or more.

6. The liquid crystal display according to claim 5 , wherein a light emitting wavelength of the light emitting diode used in said white LED is 360 to 410 nm.

7. The liquid crystal display according to claim 5 , wherein the spectrum of the lights transmitted the blue color filter comprises: a first peak top existing in a wavelength range of 440 to 450 nm; and a second peak top existing in a wavelength range of 510 to 530 nm; and a height of the second peak top is ½ or less of a height of the first peak top.

8. The liquid crystal display according to any one of claims 5 to 7 , wherein a transmission factor at the blue color filter is 90% or less of a maximum transmission factor and a transmission factor at the green color filter is 95% or less of a maximum transmission factor when a light having wavelength of 500 nm is transmitted; and a transmission factor at the green color filter is 40% or less of a maximum transmission factor when a light having wavelength of 600 nm is transmitted.

9. A liquid crystal display comprising:

a backlight using a white LED; and

color filters for filtering blue, green, red color lights,

wherein: a percentage of a spectrum area composed of light components having been transmitted the green color filter and having wavelengths of 400 to 500 nm with respect to a spectrum area composed of light components having wavelengths of 400 to 600 nm is 15% or less; and

a percentage of a spectrum area composed of light components having wavelengths of 400 to 550 nm with respect to the spectrum area composed of light components having wavelengths of 400 to 600 nm is 90% or more.