Plant Growth under High Power Operation of White-Light-Emitting-Diodes by Operating-Current-Pulse-Width Control

Abstract

Operating-current-pulse-width control (OCPWC) has been applied to the operation of white-light-emitting diodes used for plant growth. Plants were grown under light form LEDs driven by pulsed current using OCPWC as well as DC. Plant growth, i.e., the difference in the weight of a plant before and after the growth was found to be roughly proportional to the average current (and thus optical output power). In particular, when the LEDs were driven with an average current being 1.5 times higher than the standard condition, plant growth results in 1.6 times higher than the case for DC operation with the standard current. In addition, even after the operation for more than 900 hours with the 1.5 times current, the output power from the LEDs remained unchanged. These results suggest that OCPWC enables high power operation of LEDs suppressing degradation, and that the proposed technique is useful to increase plant growth per a facility and to reduce the production cost of plants.