WHITE LED FOR BACKLIGHT WITH PHOSPHOR PLATES

摘要

A white light LED (20) for use in backlighting or otherwise illuminating an LCD (10) is described where the white light LED (20) comprises a blue LED (22) over which is affixed a preformed red phosphor platelet (26) and a preformed green phosphor platelet (28). In one embodiment, to form a platelet, a controlled amount of phosphor powder (34) is placed in a mold and heated under pressure to sinter the grains together. The platelet can be made very smooth on all surfaces. A UV LED (43) may also be used in conjunction with red (44), green (45), and blue (46) phosphor plates. The LED dies vary in color and brightness and are binned in accordance with their light output characteristics. Phosphor plates with different characteristics are matched to the binned LEDs to create white light LEDs with a consistent white point for use in backlights for liquid crystal displays.