CSP-LEDs Combined With Light Guide Without Reflective Matrix for Antiglare Design

This study proposed a model with different luminous intensity profiles without reflective matrix bar for light fixtures that used asymmetric luminous intensity(ALI) CSP-LEDs (Chip Scale Package-Light emitting diode) combined with light guide as light source module, and analyzed illumination uniformity and unified glare rating (UGR) performance by using a classroom as an example. The study constructed a model of light fixture use in classrooms. Four important parameters affect the comfort of human eye that include UGR, illumination, uniformity of spatial and light distribution of light fixture, in particular, light distribution of light fixture was major affect factor for direct glare. Therefore, light fixture designers previously used many diverse structures to prevent glare, but which will result in a loss of light fixture efficiency about 25%-35% that caused by material absorption and ray loss. This study proposed used ALI CSP-LEDs combined with light guide as light source to optimize different light distribution angles without attached reflective matrix bar or second optical lens on light fixture to simulate a light fixture in a classroom and to evaluate UGR, illumination and uniformity values. We also consider the light fixture tilt angle caused effect of UGR and uniformity. On the basis of the simulation and experimental results, ALI CSP-LEDs beam angle relative to vertical and horizontal axes were 150° and 120°, respectively, the light distribution profile for a beam angle 90° provided the highest illumination uniformity and a UGR of less than 19. Thus, light fixtures with a light distribution angle of beam angle 90° supply human-friendly for anti-glare lighting.