Integrated backlight module to provide a collimated and uniform planar light source

We report a novel integrated backlight module (IBLM), which is composed of a compound optical film (COF) and a light guide plate (LGP) without any microstructure. The COF proposed in the paper comprises functions of a conventional microstructure that adjusts the emergent light and two cross brightness enhancement films (BEF). The four surfaces of the LGP are coated with highly reflective film. The COF can not only adjust the distribution of the output light by varying the density of the microstructure on the COF, but also can collimate the two cross-direction lights into the normal direction. The horizontal and vertical full width at half maxima of angular intensity of the IBLM with the proposed COF for the optimum are of 14 and 24 deg, respectively. The spatial uniformity and total optical efficiency of the IBLM have reached 85% and 77.2%, respectively. The optical efficiency has been increased by 1.3 times and the on-axis luminance has improved by 5.1 times by using a backlight module (BLM) with the COF, in comparison with the conventional edge-lit BLM that we researched [Appl. Opt. 55, 1494 (2016)]. Most importantly, the COF only needs to be configured with a relatively low-cost and easily-manufactured LGP; therefore, the BLM with the adopted COF can be further developed for large-sized application. (C) 2016 Optical Society of America