LIQUID CRYSTAL DISPLAY DEVICE
A liquid crystal display device includes light source sections 150 , a light guide plate 130 guiding light of the light source sections from a side edge and including a light emitting surface, and a liquid crystal panel 200 including a lower polarizer 230 opposed to the light emitting surface. The lower polarizer has a transmission axis generally along a light guide azimuth in which the light guide plate guides the light. The light guide plate includes a polarization converting section 131 on at least one of the light emitting surface and a rear surface. The polarization converting section reflects light made incident from the light guide azimuth in a different traveling azimuth and further reflects the light reflected in the different traveling azimuth to bring the traveling azimuth closer to the light guide azimuth to thereby convert polarization of the light traveling from the light guide azimuth.
1 . A liquid crystal display device comprising:
one or a plurality of light source sections;
a light guide plate including a light emitting surface that guides, from a side edge, light from the one or plurality of light source sections and emits the light in a planar shape; and
a liquid crystal panel including a lower polarizer on a side opposed to the light emitting surface, wherein
the lower polarizer has a transmission axis in a direction generally along a light guide azimuth in which the light guide plate guides the light,
the light guide plate includes a polarization converting section on at least one of the light emitting surface and a rear surface of the light emitting surface, and
the polarization converting section reflects light made incident from the light guide azimuth in a different traveling azimuth and further reflects the light reflected in the different traveling azimuth to bring the traveling azimuth closer to the light guide azimuth to thereby convert polarization of the light traveling from the light guide azimuth.
2 . The liquid crystal display device according to claim 1 , wherein the polarization converting section includes a prism having at least two slopes including a slope that reflects the light made incident from the light guide azimuth in the different traveling azimuth and a slope that further reflects the light reflected to the light reflected in the different traveling azimuth to bring the traveling azimuth closer to the light guide azimuth.
3 . The liquid crystal display device according to claim 2 , wherein
the prism is formed in a triangular shape in cross-section by the at least two slopes, and
normal lines of the at least two slopes are in an azimuth different from the light guide azimuth.
4 . The liquid crystal display device according to claim 3 , wherein the prism is formed in a shape of a linear groove extending in an azimuth different from an azimuth perpendicular to the light guide azimuth.
5 . The liquid crystal display device according to claim 3 , wherein the polarization converting section includes a prism row in which a plurality of the prisms are formed in a row, and
each of the prisms in the prism row has a shape of a liner groove extending in an azimuth different from an azimuth perpendicular to the light guide azimuth.
6 . The liquid crystal display device according to claim 3 , wherein the prism is formed in an isosceles triangular shape in cross-section, and the at least two slopes are formed symmetrical.
7 . The liquid crystal display device according to claim 5 , wherein
an angle formed by the azimuth in which each of the prisms extends and the light guide azimuth is equal to or smaller than 10 degrees, and
an apex angle b of the prism formed in a triangular shape in cross-section is in a range of 80 degrees≦b≦130 degrees.
8 . The liquid crystal display device according to claim 7 , wherein the apex angle b is in a range of 80 degrees≦b≦100 degrees.
9 . The liquid crystal display device according to claim 7 , wherein the apex angle b is in a range of 110 degrees≦b≦130 degrees.
10 . The liquid crystal display device according to claim 3 , wherein
the light emitting surface and the rear surface of the light guide plate are formed smooth, and
the at least two slopes of the prism included in the polarization converting section are formed smooth.
11 . The liquid crystal display device according to claim 3 , wherein the light guide plate includes a plurality of emitting sections that make light traveling on an inside of the light guide plate in the light guide azimuth incident on the light emitting surface at an angle smaller than a critical angle to thereby emit the light from the light emitting surface.
12 . The liquid crystal display device according to claim 11 , wherein the plurality of emitting sections reflect, in the light guide azimuth, the light traveling on the inside in the light guide azimuth and make the light incident on the light emitting surface at an angle smaller than the critical angle.
13 . The liquid crystal display device according to claim 11 , wherein the plurality of emitting sections are discontinuously arranged in a plurality of places on the light emitting surface or the rear surface.
14 . The liquid crystal display device according to claim 11 , wherein the polarization converting section and the plurality of emitting sections are arranged on the rear surface.
15 . The liquid crystal display device according to claim 14 , wherein a groove-like pattern is formed linearly along the light guide azimuth on the light emitting surface according to arrangement of the one or plurality of light source sections.
16 . The liquid crystal display device according to claim 14 , wherein
the polarization converting section includes a prism row in which a plurality of the prisms are formed in a row,
each of the prisms in the prism row has a shape of a liner groove extending in an azimuth different from an azimuth perpendicular to the light guide azimuth, and
the plurality of emitting sections are respectively arranged to overlap at least one of a ridge line and a valley line in the prism row.
17 . The liquid crystal display device according to claim 14 , wherein
the light guide plate includes the polarization converting section on the rear surface,
the polarization converting section includes a plurality of prism rows in which a plurality of the prisms are formed in rows,
each of the prisms in each of the prism rows has a shape of a linear groove extending in an azimuth different from an azimuth perpendicular to the light guide azimuth,
the plurality of prism rows are discontinuously arranged along the light guide azimuth, and
at least one of the plurality of emitting sections is arranged to be interposed between two of the plurality of prism rows discontinuously arranged.
18 . The liquid crystal display device according to claim 1 , wherein
a reflective polarizer is arranged between the lower polarizer and the light guide plate,
the reflective polarizer reflects light of a polarization component in a direction orthogonal to the transmission axis to the light guide plate side, and
the polarization converting section is formed on the rear surface of the light guide plate.
19 . The liquid crystal display device according to claim 1 , wherein the light guide plate includes a polarization converting section that totally reflects, at least twice, light traveling on an inside in the light guide azimuth to change a traveling azimuth of the light on at least one of the light emitting surface and the rear surface of the light emitting surface and converts polarization of the light.