Tilted light coupling structure for the thickness reduction of a liquid crystal display backlight

It is hard to design a traditional edge-lit light guide plate (LGP) as an ultrathin structure, because the LGP thickness will be limited by the luminescence regional width of the LED source. In this paper, a tilted light coupling structure (TLCS) for a liquid crystal display (LCD) backlight is proposed that allows an inclined layout of an edge LED array to significantly reduce the LGP thickness. The design process and optical conditions of the TLCS are first discussed, and the effect of structural parameters on the coupling efficiency is also analyzed. After that, a fundamental model and an improved model are designed: namely, the planar TLCS and the curved TLCS. Design results show that the light coupling efficiency of the proposed TLCS can reach 95%, while the LGP thickness is reduced to 7% thinner than the luminescence regional width of the LED source. The proposed TLCS will have broad applications in light guiding devices. (C) 2019 Optical Society of America