2018 年 4 巻 1 号 p. 44-63
The Liquid Crystal Display (LCD) system has permeated every aspect of our daily lives. However, few people are aware of the blue light hazard of a Light Emitting Diode (LED), which is widely used as a light source in the backlight system of display devices. Presently, many manufacturers take a series of countermeasures, and most of them focus on reducing blue light through software technology, as this technique is easy to conduct and cost-friendly. However, there are still two manufacturers that insist on hardware methods to reduce the blue light hazard, as they seek to maintain the color performance.In this paper, we have proposed a new method of reducing blue light via hardware and have evaluated both the software method and the hardware method by means of numerical analysis. The new design is based on a backlight system in which the original white LED is modified so that the blue-band energy is reduced by 50% and cyan light LEDs are added among the white light LEDs. In addition, we have optimized and adjusted the distribution of the LEDs’ energy to reduce the harm of the blue light, and we have simultaneously maintained good color performance. According to the simulation results, the newly designed backlight unit could effectively cut down over 50% of the blue light and maintain the correlated color temperature (CCT) at 6081K, which approaches the standard value of 6500K. In addition, the color rendering index (CRI) can also be maintained at 74.818, which is almost the same as an ordinary white LED without blue light filtering.
