介绍了背光源顶白不良，探讨了顶白的形成机理。研究发现表面光滑反射片对导光板网点间留白区域的挤压是产生顶白的根本原因。由此提出通过改善背板局部凸起高度和增加反射片粗糙度来改善顶白。结果表明：顶白发生率随背板局部凸起高度降低和反射片表面粗糙度增加而明显降低。控制模具凸棱厚度可调整回压量，进而降低背板局部凸起高度。模具凸棱厚度为0.05 mm时，背板局部凸起高度均值由无回压时的0.21 mm降低至0.11 mm，加速试验条件下对应顶白发生率由50%降低至18.7%；涂布不同大小粒子可调整反射片表面粗糙度。当反射片涂布Bead粒子径为40 μm，对应粗糙度为6.29 μm时，并搭配段差回压后背板，改善后背光源在加速试验条件下无顶白发生。同时，经光学、老化及振动测试，改善后背光源未发现其它相关不良。

This paper reports the extruded white spot (EWS) of BLU and the associated caused reasons, and studies the impaction of the height of local convexity on back cover and the roughness of reflector film on EWS. The results show that the incidence of EWS significantly reduces with the decrease in the height of local convexity. Under the best back-pressure process, the mean value of local convexity decline from 0.21 mm to 0.11mm. Accordingly, the incidence of EWS declines from 50% to 18.7% during THO ＆VIB accelerated tests. The anti-EWS ability of reflector film is obviously improved with the increase in roughness. There is no EWS occurred, when the roughness is 6.29 μm together with using back-pressure back cover.