Linear white light source, and backlight and liquid crystal display device using the same

1. A linear white light source comprising:

a base having a flat surface;

a plurality of light emitting diode chips linearly disposed on the flat surface of the base and each generating ultraviolet light having a wavelength of not less than 330 nm nor more than 410 nm; and

a phosphor layer continuously formed on the flat surface of the base to cover the plural light emitting diode chips and including a red light emitting phosphor, a green light emitting phosphor, and a blue light emitting phosphor,

wherein the plural light emitting diode chips are disposed at an interval of 1 mm or more and 5 mm or less, and

wherein the phosphor layer has a flat upper surface, and each of heights from the flat surface of the base to the flat upper surface of the phosphor layer in a first portion on which the light emitting diode chip is disposed and a second portion on which the light emitting diode chip is not disposed is in a range of 0.5 to 2 mm.

2. The linear white light source according to claim 1 ,

wherein the number of the light emitting diode chips is equal to or more than five.

3. The linear white light source according to claim 1 ,

wherein luminance unevenness of the linear white light source is not less than 1% nor more than 100%.

4. The linear white light source according to claim 1 ,

wherein the luminance unevenness of the linear white light source is not less than 50% nor more than 100%.

5. The linear white light source according to claim 1 ,

wherein the red light emitting phosphor comprises a phosphor powder with a composition expressed by a general formula (1):

(La 1-x-y Eu x M y ) 2 O 2 S  (1)

where, M is at least one element selected from Sb, Sm, Ga, and Sn, and x and y are values satisfying 0.01<x<0.15 and 0≦y<0.03, and/or a phosphor powder with a composition expressed by a general formula (2):

(Sr x Ca 1-x )SiAlN 3 :Eu  (2)

where, x is a value satisfying 0≦x<0.4.

6. The linear white light source according to claim 1 ,

wherein the green light emitting phosphor comprises a phosphor powder with a composition expressed by a general formula (3):

(Ba 1-x-y-z Sr x Ca y Eu z )(Mg 1-u Mn u )Al 10 O 17   (3)

where, x, y, z, and u are values satisfying 0≦x<0.2, 0≦y<0.1, 0.005<z<0.5, and 0.1<u<0.5, and/or a phosphor powder with a composition expressed by a general formula (4):

(Sr 2-x-y-z-u Ba x Mg y Eu z Mn u )SiO 4   (4)

where, x, y, z, and u are values satisfying 0.1<x<0.4, 0.005<y<0.21, 0.05<z<0.3, and 0.001<u<0.04.

7. The linear white light source according to claim 1 ,

wherein the blue light emitting phosphor comprises a phosphor powder with a composition expressed by a general formula (5):

(Sr 1-x-y-z Ba x Ca y Eu z ) 5 (PO 4 ) 3 Cl  (5)

where, x, y, and z are values satisfying 0≦x<0.5, 0≦y<0.1, and 0.005<z<0.1.

8. A backlight comprising the linear white light source according to claim 1 .

9. A liquid crystal display device comprising the backlight according to claim 8 .

10. The linear white light source according to claim 1 ,

wherein the phosphor layer comprises a transparent resin layer formed on the base, and the red, green, and blue light emitting phosphors dispersed in the transparent resin layer, and

wherein a total content of the red, green, and blue light emitting phosphors in the phosphor layer is in a range of 20 to 70 mass %.

11. The linear white light source according to claim 1 ,

wherein the base comprises a ceramic substrate made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body or a glass-ceramic body, and a plurality of metal patterns formed on the ceramic substrate, and

wherein each of the plural light emitting diode chips is mounted on one of the plural metal patterns.

12. The linear white light source according to claim 11 ,

wherein each of the plural metal patterns has a square-shape substantially, and

wherein an interval between the adjacent metal patterns is in a range of 0.03 to 0.2 mm.

13. The linear white light source according to claim 11 ,

wherein each of the plural light emitting diode chips includes a lower electrode and an upper electrode, and

wherein the lower electrode is electrically connected to the metal pattern where the light emitting diode chip is mounted, and the upper electrode is electrically connected to the adjacent metal pattern via a conductive wire.

14. The linear white light source according to claim 11 ,

wherein each of the plural metal patterns is made of at least one metal selected from Au, Al, Ag, Pt, Ti, and Ni.

15. The linear white light source according to claim 11 ,

wherein each of the plural metal patterns comprises a Ti layer formed on the ceramic substrate, and a metal layer formed on the Ti layer, and the metal layer is made of at least one metal selected from Au, Al, Ag, Pt, and Ni.