When a short-cycle pulse voltage with a frequency of approximately 60Hz is applied to a LED at a duty ratio of about 5%, the LED looks about twice as bright to the human eye in comparison with a LED driven by a direct voltage, the research group said.
The group was led by Masafumi Jinno, associate professor in the university’s Department of Electrical and Electronic Engineering at the Graduate School of Science and Engineering. The test result was unveiled at the “New Technology Presentation Meetings by Four Universities in Shikoku Region,” sponsored by Japan Science and Technology Agency (JST).
The group decided to drive the LEDs using a power supply with a shorter voltage cycle of about several hundred microseconds. As a result, the group discovered that, when a pulse voltage with a frequency of approximately 60Hz is applied at a duty ratio of about 5%, the impact by the Broca-Sulzer effect becomes greater than that of the Talbot-Plateau effect, so that the light emitted from the LED looks brighter to human eyes.
The Broca-Sulzer effect refers to a phenomenon in which light looks several times brighter to the eye than it actually is when exposed to a brief-duration light, such as a camera flash. The Talbot-Plateau effect is a principle where human eyes sense the average brightness of repeatedly flashed lights.