| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin optical element for a backlight device, capable of excellently improving light distribution characteristics and color unevenness, and to provide a low-profile LED lighting device using the same.SOLUTION: Out of light emitted from the light-emitting surface of an LED light source 20, light near the center is diffused by a rough face in a center region 11a of an incidence surface 11 and enters into a first region 12a of an emission surface 12 in a color mixed state. Out of the light emitted from the light-emitting surface of the LED light source 20, light entering into a peripheral region 11b enters into a second region 12b of the emission surface 12. According to this embodiment, Z0 has a maximal value (Zmax) on the positive side in a range of 0.25(mm)≤R0≤0.65(mm), and so the beam of light passing through the rough face to enhance directivity is emitted to be further apart from a light axis OA to improve the light distribution characteristics. |
