In order to get stable, reliable and simple white light, the most commonly used method is to use blue light LED chip to stimulate the yellow phosphor. LED radiation out of the wavelength of about 450nm blue light, blue light in this process is divided into two parts, part of the blue light excitation phosphor emitted about 570nm wavelength of yellow green light, and the other part of the blue light transmission and excitation of the phosphor produced by the combination of yellow and green light, as the picture shows.
Blue LED chip plus phosphor to produce white light
Color temperature is the most common indicator of light source spectral quality. According to the composition and composition of phosphor, white LED can provide color temperature between 2700 ~ 6500K cool white, neutral, warm white full range of color temperature range.
The color of the light emitted by the light source is the same as the blackbody (which is a complete radiator and black). When the light is radiated at a certain temperature, the temperature of the blackbody is called the color temperature of the light source. In the blackbody radiation, with the temperature is different, the color of the light is different, when the black body from the red - orange - yellow - yellow - white - blue - white gradient process, that is, the color temperature from low to high process. The higher the temperature of the "blackbody", the more blue the composition in the spectrum, and the less the red component. For example, incandescent light color is warm white, the color temperature is expressed as 2700K, while the daylight color lamp color temperature is 6000K.
Natural daytime changes in the sun just represents the luminous body of the color temperature changes. Morning and evening sunshine 2000 ~ 3000K (warm white); morning 8:00 sunshine 4000K (cool white); noon around the sun 5000 ~ 6000K (daylight color).
"Warm light" color temperature is low, and "cold light" color temperature is relatively high. After the increase of the color temperature, the proportion of blue radiation increases, and the content of blue light increases. At the same time, the brightness also affects the proportion of blue light.
In general, a color temperature of 2700 to 4000 K is referred to as a low color temperature. 5000 ~ 6500K color temperature is called high color temperature. High color temperature white light due to high content of blue, also known as "rich blue" white light.
What is the blue light of LED lighting?
As the LED light source has a small luminous area, high brightness characteristics, and Blu-ray than other light color wavelength is short, so there is greater radiation energy, the possible radiation hazards than other colors of light is greater. Blu-ray hazard refers to the light source in the 400 ~ 500nm Blu-ray band of the harm, if a LED lamp brightness is too high, then look at the eyes for a long time after the light may cause photochemical damage of the retina. The severity of the blue light depends on the amount of blue light that the human eye accumulates in the light.