Light source apparatus including splitter and image display apparatus including the same
The light source apparatus includes a light source, and a light guide plate configured to propagate a light beam from the light source in a specific direction. The light guide plate includes a splitter configured to split the light beam from the light source into a plurality of light beams, and to emit the plurality of light beams from the light guide plate. The splitter is configured such that a transmittance for a predetermined wavelength included in the light beam from the light source increases along the specific direction. A predetermined inequality is satisfied.
1 . A light source apparatus comprising:
a light source; and
a light guide plate configured to propagate a light beam from the light source in a specific direction,
wherein the light guide plate includes a splitter configured to split the light beam from the light source into a plurality of light beams, and to emit the plurality of light beams from the light guide plate,
wherein the splitter is configured such that a transmittance for a predetermined wavelength included in the light beam from the light source increases along the specific direction,
wherein the light guide plate is provided to face the splitter and includes a reflector configured to reflect the light beam from the light source, and
wherein the following inequality is satisfied:
2.
≤
n
/
m
0
≤
T
(
θ
)
≤
2
0
where n is the number of areas of the splitter with different transmittances, m is the number of light beams, and T(θ) is a transmittance of the reflector for the light beam from the light source that enters the reflector at an incident angle θ (°).
2 . The light source apparatus according to claim 1 , wherein the transmittance increases continuously or stepwise along the specific direction.
3 . The light source apparatus according to claim 1 , wherein the predetermined wavelength is a center wavelength or a wavelength having a highest intensity of the light beam from the light source.
4 . The light source apparatus according to claim 1 , wherein the following inequality is satisfied:
u
/
(
d
×
sin
θ
)
≤
0
.
5
0
where d is a thickness of the light guide plate, u is a width of a smallest area of the splitter among the areas with different transmittances, and θ is an incident angle of a principal ray incident on the splitter.
5 . The light source apparatus according to claim 1 , wherein the light guide plate is provided to face the splitter and includes a reflector configured to reflect the light beam from the light source, and
wherein the following inequality is satisfied:
8
0
≤
T
(
0
)
≤
1
0
0
where T(0) is a transmittance of the reflector for the light beam from the light source that enters the reflector at an incident angle of 0 (°).
6 . The light source apparatus according to claim 1 , wherein the following inequality is satisfied:
0.
<
W
/
R
<
0
.
0
3
where R is a center wavelength of at least one spectrum of the light beam from the light source, and W is a half maximum full-width of the spectrum.
7 . The light source apparatus according to claim 1 , wherein the splitter is a dielectric film configured such that the transmittance increases along the specific direction, and
wherein a thickness of the dielectric film changes along the specific direction.
8 . The light source apparatus according to claim 7 , wherein the splitter includes a dielectric gradient film that has a transmittance of 25% at a first position and a transmittance of 75% at a second position different from the first position in the specific direction.
9 . The light source apparatus according to claim 8 , wherein the following inequality is satisfied:
3
0
≤
T
x
≤
7
0
where Tx is a transmittance of the splitter at a third position as a middle of the first position and the second position in the specific direction.
10 . The light source apparatus according to claim 7 , wherein the following inequality is satisfied:
U
(
x
1
)
<
U
(
x
3
)
<
U
(
x
2
)
or
U
(
x
2
)
<
U
(
x
3
)
<
U
(
x
1
)
where U(x 1 ) is a thickness of the dielectric gradient film at a first position, U(x 2 ) is a film thickness at a second position different from the first position in the specific direction, and U(x 3 ) is a film thickness at a third position as a middle of the first position and the second position in the specific direction.
11 . The light source apparatus according to claim 1 , wherein the light guide plate is provided to face the splitter and includes a reflector configured to reflect the light beam from the light source, and
wherein the splitter reflects a part of the light beam from the light source and transmits another part of the light beam.
12 . An image display apparatus comprising:
the light source apparatus according to claim 1 ; and
an image display element illuminated by the light source apparatus.
13 . A light source apparatus comprising:
a light source; and
a light guide plate configured to propagate a light beam from the light source in a specific direction,
wherein the light guide plate includes a splitter configured to split the light beam from the light source into a plurality of light beams, and to emit the plurality of light beams from the light guide plate,
wherein the splitter is configured such that a transmittance for a predetermined wavelength included in the light beam from the light source increases along the specific direction,
wherein the light guide plate is provided to face the splitter and includes a reflector configured to reflect the light beam from the light source,
wherein the splitter reflects a part of the light beam from the light source and transmits another part of the light beam, and
wherein the following inequality is satisfied:
2.
≤
n
/
m
where n is the number of areas of the splitter with different transmittances, and m is the number of light beams.