Covering the entire visible wavelength LED light source

Japan Industrial Technology Research Institute (Nissan Research) announced in February 1, 2016, and Nichia chemical industries jointly developed a LED light source covering the whole visible range. Since this light source can be used as a standard light source for the evaluation of solid state lighting devices, the two institutions will be named the "LED"".

Figure 1: the new development of the "standard LED" and the use of schematic diagram by Nissan research and provide nichia.

According to reports, in the LED lighting appliances and organic EL lighting fixtures and other solid elements in the lighting apparatus, as a measure of brightness indicators, the total light flux and color evaluation is very important. In these evaluations, it is necessary to measure the intensity of light at different wavelengths with a high precision. In order to measure the light with high precision, the light source of the evaluation object is compared with the standard light source. However, there is no standard light source that can be used for high-precision optical measurement of solid state lighting devices and cover the entire visible range.

The Nissan research is different from Nichia with central wavelength of multiple LED elements and a variety of fluorescent material, developed in the visible light range (380nm ~ 720nm) have sufficient light source light intensity of the "standard LED" (Figure 1). In the LED manufacturing and development of the use of the "standard LED", can be used for high precision characteristics of solid state lighting fixture evaluation, is expected to accelerate product development and improve performance.

Combining multiple LED elements

The white LED is not sufficient for the wavelength range from 420 to 720nm (the blue dashed line in Figure 2), and is not suitable for the standard light source for the whole visible range. The development of the "standard LED" through the different center wavelength of a plurality of LED elements, improve the light intensity of 380nm ~ 430nm wavelength range, at the same time longer than the 430nm wavelength range, a variety of fluorescent material combination of blue, green and red fluorescence, improved light intensity. As a result, the "standard LED" has sufficient light intensity in the wavelength range of visible light (the red line in Figure 2).

Figure 2: the "standard LED" (red) spectra and spectral sample previous white LED (blue), by Nissan research and provide nichia.

The diameter of the standard LED is 62mm, and the diameter of the luminous part is 12mm. A temperature control mechanism is arranged to keep the temperature of the light emitting part at a certain level. Through this mechanism, the magnitude of the light intensity changes with the change of the temperature around the "standard LED" is reduced to below 0.01%/ C (Figure 3 left). Compared with the previous white LED, to achieve a stability of about 20 times (white LED light intensity fluctuation range of about 0.15 to 0.2 degrees Celsius). In addition, the previous white LED in the light, the intensity of light will be substantially changed, and the "standard LED" light after the light intensity is almost no change (Figure 3 right).

Figure 3: light intensity occurs with the variation of ambient temperature changes (left) and change with the lighting time and the occurrence of (right), by Nissan research and provide nichia.

In the future, Nichia chemical industries will promote the "LED standard" for mass production, Nissan research will be further improved in the "standard LED" in the development of the spectral precision measurement technology, light source evaluation technology research and development of surface emitting light and ultraviolet and infrared range.

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