A field-sequential-color (FSC) scanning backlight system with tandem light guides (LGs) is introduced for a 32-inch color-filter-less liquid-crystal display (LCD). The tandem-type backlight module (BLM) can clearly define each scanning division without any shields and reduce the total thickness of the module down to 15 mm at the same time. According to the experiment, uniformity and efficiency were achieved upto 83% and 63% respectively using prismatic micro-bump structures over the bottom of LG. Light leakage to the adjacent partition was measured 9.8% as well. Based on the tandem optomechanical setup, the influences of image blur and color-breakup (CBU) from motion pictures were expected to be significantly reduced accordingly.