Introduction: Emanaka, an associate professor of information and electronic information engineering at the Department of Research in Physiology and Engineering, Ehime University, has developed a pulse-driven control method that doubles the brightness of LEDs by utilizing the sensitization characteristics of the human eye. When a cycle high-speed pulse voltage having a duty ratio of about 5% and a frequency of about 60 Hz is applied to the LED, the brightness perceived by the human eye is about twice as large as when the DC voltage is applied. The evaluation experiments conducted by the subjects showed that the brightness perceived by the blue LED was 1.5 to 1.9 times, the green LED was 2.0 to 2.2 times, and the red LED was 1.0 to 1.3 times. "With this method, the brightness of an LED with a luminous efficiency of 100 lm/W can be achieved with a 50 lm/W LED simulation" (Shenno). The results have been published in the "New Technology Briefing Session of Four Universities in the Four Countries" sponsored by the Science and Technology Promotion Agency (JST).
The sensitization of the human eye generally follows two rules. One is called the "Broca-Sulzer effect." After receiving an instant flash like a shutter, the brightness perceived by the human eye is several times the actual brightness. However, after repeatedly receiving the flash, the human eye will feel the average brightness over the repeated time, called the "Talbot-Plateau effect." Previously, people have always believed that "even if the LED is pulse-driven according to the Talbot-Plateau effect, the brightness that people feel will not change" (Shenno).
Kamano said, "The Talbot-Plateau effect was discovered during the period of mercury fluorescent lamps driven by low-speed power supplies with voltage cycles of around several hundred ms." Therefore, this time I thought of driving a LED with a high-speed power supply with a voltage cycle of several hundred ns. As a result, when a pulse voltage having a duty ratio of about 5% and a frequency of about 60 Hz is used, the effect of the Broca-Sulzer effect is larger than that of the Talbot-Plateau effect, and the human eye can feel higher brightness. The verification experiment uses three colors of LEDs manufactured by Nichia Chemical Industry Co., Ltd., the blue LED with the wavelength of 464nm is modeled as "NSPB500S", the green LED with wavelength of 520nm is "NSPG510S", and the red LED with wavelength of 633nm is "NSPR510CS". ".
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