High Uniformity and Tolerance Design for Direct-Lit LED Backlight Illumination Using Lagrange Interpolation

This paper proposes the use of a Lagrange interpolation polynomial to meet the illumination distribution requirements of single-LED units, in both a square and a triangular arrangement, for direct-lit backlighting to obtain uniform illumination to be used for designing secondary optical lenses. In addition, we propose the use of a wider illumination coverage of LED units to achieve excellent assembly displacement tolerance. We also define an evaluation formula for combining the uniformity and tolerance of the LED unit to select its ideal corresponding light intensity distribution as the target of the lens design in direct-lit LED backlight modules.