A Downlight Luminaire with High Luminous Efficacy

A design method and manufacturing process of downlight luminaire with a truncated frusto-conical light shade is proposed in this article. The measurement results showed that the optimal illumination was 212.8 lux, and the luminaire exhibited 70% of the optimal illumination within an illumination range of 1.84 m
²
. For normal- and warm-white light-emitting devices (LEDs), the optimal efficiencies of the proposed luminaires were 158 and 117 lm/W, respectively.