PURPOSE: A light collecting sheet and a backlight unit for liquid crystal display device with improved center brightness are provided to mix the height and apex angle and improve excellent wide-viewing angle by recycling the light.;CONSTITUTION: A light collecting sheet(100) condenses the light by inserting the light into a backlight unit. The light collecting sheet includes a first plane(101) and a second plane(102). The light is inlaid by the first plane. The light comes out to the second face. A first prism and a second prism are loaded together. The first prism includes the first heights and the first apex angles. The second prism includes second heights higher than the first heights and the second apex angles in which they are bigger than the first apex angles.;COPYRIGHT KIPO 2010
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