白光LED色彩渲染的光譜設計考慮

　　在這篇文章中，國家標準與技術研究所（NIST）的專家們分析了各種白光LED模型，通過模擬它們的顯色性能和發光效率。結果多芯片和熒光粉型白光LED的設計提供一定的指導。

　　介紹

　　一般照明光源最重要的特點之一是顯色。顏色渲染是光源的特性，它告訴物體在給定照明下的顏色是多么自然。如果渲染效果不佳，光源對一般照明不起作用。1992美國能源政策法案規定的最低要求的發光效率（流明每瓦）和顯色指數（CRI）2幾種常見燈具產品銷往美國。這是白光LED用于一般照明的一個重要方面的類型。

　　White light from LEDs is realized by a mixture of multicolor LEDs or by combinations of phosphors excited by blue or UV LED emission， and thus they have greater freedom in spectral design than conventional sources. Questions arise on how the spectra of white LEDs should be designed for good color-rendering performance， e.g.， whether RGB white LEDs can satisfy the need or a four-color mixture is needed， or whether much broader， continuous spectra are required. To evaluate the color-rendering performance of light sources， the CRI，2 recommended by the Commission Internationale de l’éclairage （CIE）， is available and widely used， but it is known to have deficiencies，3，4 especially when used for sources having narrowband spectra. A poor correlation between visual evaluation of RGB white LEDs and the CRI is reported.5 The color-rendering problems of white LEDs are being investigated by the CIE Technical Committee 1-62 with a future plan to develop a new metric.