White LED technology innovation

Nichia Chemical Industry has developed a white light-emitting diode (LED) with a luminous efficiency of 100 lm/W. Samples were supplied in June 2006 (Fig. 1). It is planned to put into mass production in December of the same year. In terms of luminous efficiency, performance exceeds that of popular fluorescent lamps, and it can be compared with varieties with higher luminous efficiency. In 2005, the company said that it will mass produce 100lm/W products around 2010. The news announced this time will lead the production time by 3 to 4 years. The white LED that Nichia Chemical Industry will supply samples will get 6 lm of luminous flux at an input current of 20 mA. It belongs to a small power type with input power of only 0.06W. The specific price will be agreed in the future. Nichia Chemical Industry has published 113lm/W white LED development products at the academic conference. As the development of key technologies is proceeding smoothly, and this year will be the company's 50th anniversary, it decided to start production of 100lm/W products. Figure 1: The right side shows the lighting effect achieved with a white LED with a luminous efficiency of 100 lm/W. A total of 756 white LEDs with a luminous flux of 6 lm were used. The input power is 45W and the total luminous flux is 4536lm. On the left side is a fluorescent lighting with a luminous efficiency of 58.5 lm/W. Two 1170 lm fluorescent lamps were used with a total luminous flux of 2340 lm. The input power is 40W. Figure 2: Blue LED development blueprint. A luminous efficiency of 150 lm/W was achieved around 2007. Nichia Chemical Industry also announced the development blueprint after 2007. It is said that the development of 150lm/W products will be completed in 2007 (Fig. 2). Previously, other manufacturers have indicated that they will start production of 90lm/W~100lm/W products from 2006 to 2007, and Nichia Chemical Industry only announced one. Conservative value. “There is no technological breakthrough” In order to achieve a luminous efficiency of 100 lm/W, Nichia Chemical Industry has improved the shape and electrode structure of the blue LED chip constituting the white LED, the YAG-based yellow fluorescent material used in the chip, and the package shape 4 Big key technology. “These improvements have been steadily advanced long ago. This achievement can be said to be a gathering of previous work. There is no breakthrough in specific key technologies” (Shiyamyo City, the managing director of Nichia Chemical Industry Co., Ltd.). For a luminous efficiency of 150 lm/W, it is estimated that this goal can be achieved by optimizing the key technologies used in this adoption. While improving the luminous efficiency, it also worked hard on the hue of white light. By improving the additive of the YAG-based fluorescent material, an average color rendering index (Ra) of more than 80 is obtained. In general, in order to improve color rendering in a white LED using a blue LED chip, a method of adding a red or green fluorescent material or replacing a yellow fluorescent material with a material having green and red is generally employed. Nichia Chemical Industry believes that: "To get a white LED with Ra over 90, the fluorescent material must be fundamentally changed. However, the product use of Ra over 90 is generally limited only by the art gallery lighting, and Ra only needs 80 to be enough. The market size is very large. Therefore, by working hard on YAG-based fluorescent materials, it is enough to meet market requirements.” (Director Xiang Jingzhi) In high-power products with input power higher than one digit, the luminous efficiency reaches 100lm/W. Nichia has not disclosed whether it is put into production in advance. In 2005, the company said it would supply high-power products with luminous efficiencies of 100 lm/W around 2010. The company said that although it can now achieve 100lm/W in high-power products, it is too early to start production due to high production costs.


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