Functional light-guide plate characterized by optical micro-deflector and micro-reflector for LCD backlight

The optical structure of a conventional backlight illumination system used for transmissive LCD of a mobile terminal is investigated. A structured LGP based on the total internal reflection is designed and fabricated. The LGP is characterized by optical micro-deflectors (MD) and micro-reflectors (MR). The guided light inside the LGP is reflected on the MR elements and directed toward the MID elements. The coming light ray is refracted on the MID element and as a result the ray is deflected on the LGP. The emergent light on the LGP has a wide zenith angle due to the LGP surface normal. A prism sheet whose function is based on the 'total internal reflection is set on the LGP. The emanated light from the LGP is reflected on the surface of the prism structure and redirected toward the surface normal. The illumination cone of the novel backlight is limited to horizontal range of +/- 17 degrees and vertical range of +/- 11 degrees. The illumination cone on the novel structure can be shaped by optical designs of the MID and MR elements. The peak brightness on the novel backlight structure is 1.44 times that of the conventional one. In this backlight structure, only one TIR prism sheet is used and a thickness reduction of about 250 mum is achieved.