Backlight
A backlight comprises a plurality of light sources mounted on a mounting substrate in rows; lenses respectively arranged on the light sources; and a reflective sheet disposed on the mounting substrate and provided with through-holes through which the light sources protrude, wherein a first light source spacing of the plurality of light sources in a row direction is set to Px, an inter-row spacing of the plurality of light sources in other direction orthogonal to the row direction is set to Py, a first maximum length of each of the through-holes in the reflective sheet in the row direction is set to a, an inter-row maximum length of each of the through-holes in the reflective sheet in the other direction is set to b, the reflectivity of the reflective sheet is set to a and the reflectivity of the mounting substrate is set to β, the following mathematical formula 1 is satisfied if P y > Px : α ( P x - a ) + β a α ( P y - b ) + β b · P y P x > 0 . 9 .
1. A backlight, comprising:
a plurality of light sources mounted in rows on a mounting substrate;
lenses arranged on each of the light sources, respectively; and
a reflective sheet disposed on the mounting substrate and provided with through-holes through which the light sources protrude,
wherein a first light source spacing of the plurality of light sources in a row direction is set to Px, an inter-row spacing of the plurality of light sources in other direction orthogonal to the row direction is set to Py, a first maximum length of each of the through-holes in the reflective sheet in the row direction is set to a, an inter-row maximum length of each of the through-holes in the reflective sheet in the other direction is set to b, the reflectivity of the reflective sheet is set to a and the reflectivity of the mounting substrate is set to β, the following mathematical formula 1 is satisfied if Py>Px:
α
(
P
x
-
a
)
+
β
a
α
(
P
y
-
b
)
+
β
b
·
P
y
P
x
>
0.9
.
(
formula
1
)
2. The backlight according to claim 1 , wherein,
the formula 1 is satisfied if Py/Px≥1.5.
3. The backlight according to claim 1 , wherein,
the formula 1 is satisfied if Py/Px≥2.
4. The backlight according to claim 1 , wherein,
the backlight is further provided with a diffusion plate covering the plurality of light sources, and
the following formula 2 is satisfied if a distance between the mounting substrate and the diffusion plate is set to h:
b/h≥ 0.7 (formula 2).
5. The backlight according to claim 1 , wherein,
the light sources are LEDs.
6. The backlight according to claim 1 , wherein,
the backlight is further provided with a diffusion plate covering the plurality of light sources,
the light sources are blue LEDs, and
a wavelength conversion sheet is provided on the diffusion plate.
7. The backlight according to claim 1 , wherein,
each of the lens has an ellipse or oval shape which has a longer length in the other direction than in the row direction when view from the top, or
each of the lens has a circular shape when view from the top.