| 摘要 |
Overlapping first and second light guide plates have incidence faces located opposite to each other. Each light guide plate has an emission restraint region, an emission gradually-increasing region and an emission promotion region arranged in order from incidence face toward distal end face. In each emission gradually-increasing region, emission light quantity increases gradually away from each emission restraint region toward each emission promotion region. The emission gradually-increasing regions of the light guide plates overlap each other. The emission promotion region of the second light guide plate overlaps with the emission restraint region of the first light guide plate while the emission restraint region of the second light guide plate overlaps the emission promotion region of the first light guide plate. Light from LEDs is limited by windows. Color-mixing of the LED-light occurs in each emission restraint region to become whitened light gaining emission intensity in the emission promotion regions.
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