A monolithic segmented functional light guide for 2-D dimming LCD backlight

An edge-lit backlight with a thin structure and 2-D dimming function is a highlighted requirement. To achieve a thin backlight unit for 2-D dimmable displays, a monolithic functional light-guide plate (LGP) was segmented by using a recessed U-groove with graded height as semi-partitions. The height of the U-groove controls the cross-talk between the segments. A single segment was characterized with an array of louver-shaped micro-prisms that function as unilateral reflectors for light distributing, directing, and extracting. Arrays of rounded micro-prisms, and lenticular prisms for in-and out-coupling, are designed on the light injection surface and front surface of the LGP for light-cone shaping on the BLU. The light guide has a length of 73.0 mm, a width of 40.7 mm, and a thickness of 0.7 mm. The LGP was segmented into 16 segments where the width and graded height of the recessed U-prism between the segments is 0.020 mm and 0.10-0.50 mm, respectively. By using the monolithic light-guide plate, the cross-talk is suppressed to 20% and 4% at the center of first and second neighboring segments, respectively.