摘要 |
In a light reflection pattern formed on a bottom surface of a light conductive plate, an inclined surface of grooves positioned at a predetermined distance or farther from a lamp includes a non-flat portion whose inclination angle varies gradually. Light rays traveling in the light conductive plate are reflected at the non-flat portion with an appropriate angle suitable for increasing a viewing field angle and exit out from a top surface of the light conductive plate. Consequently, the viewing field angle at the portion positioned at a predetermined distance or farther from the lamp can be increased.
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