Color conversion filters can improve the color rendering of LED lights

Toshiba and Toshiba Lighting Technology demonstrated at the "Lighting Show" that the color rendering of LED lights can be improved by simply installing a color conversion filter on the illuminated surface of the LED light. According to reports, even if ordinary LED lights with an average color rendering index (Ra) of 70 to 85 are used, the Ra can be increased to more than 90 by installing a color conversion filter. At present, the development of this technology has been basically completed, and Toshiba will consider whether to commercialize it based on the response of visitors at this exhibition.

During the on-site demonstration, LED light with Ra of 85 and R9 (bright red) of 46 was converted into light with Ra of 94 and R9 of 97, and the colors of objects under this light looked very bright. In the past, in order to improve the color rendering, it was necessary to install LED chips with higher color rendering in the lamps in most cases. After installing the color conversion filter of this time, the color rendering of lamps using ordinary LED chips can be easily improved. In addition, Toshiba also installed a filter on ordinary LED lights that can make red and green look very bright and demonstrated it.

Color conversion filters are made by mixing pigments into resin materials. The characteristic of pigments is that they can filter out light of specific wavelengths. For example, the pigments used in the filter that can improve R9 can filter out light with wavelengths close to red. After installing the color conversion filter, the brightness of the LED light will be reduced by nearly 10%, but under this light, the objects look very bright, so the reduction in brightness is not obvious.

Toshiba spent a lot of effort in selecting pigments when developing the filter. The reason is that the pigments used are organic materials, so there is a risk of rapid deterioration. Toshiba did not disclose the details of this, but said that it developed pigments with a lower risk of deterioration, ensuring the filter's life of 40,000 hours.

According to Toshiba, in addition to using pigments, the method of preparing color conversion filters can also be to lay a multi-layer film on the resin surface. However, when using a multi-layer film, it is dependent on the angle of light irradiation. For example, the color tone of light directly below the filter and the side direction of the filter will be different, but the filter mixed with pigments has no dependence on the angle of light irradiation.