Discussion On The Penetration Of LED Street Light in Heavy Fog Environment

LED light sources are divided into warm white, neutral white and cold white. The discharge radiation of traditional street lamps and sodium lamps is concentrated on two double-D lines of 589.0nm and 589.6nm. Therefore, the color temperature is generally about 2300K warm white light, which has obvious yellow under human vision. LED can produce light sources with different color temperatures through packaging technology, thus providing a variety of different options for road lighting.

At present, LED packaging technology can apply phosphors with different excitation wavelengths, adjust the dosage or proportion of phosphors, and obtain LED white light sources with different color temperatures. Different light sources emit different color temperatures. The low color temperature light source is characterized by relatively more red radiation in the energy distribution, which is often called "warm light". After the color temperature rises, the proportion of blue radiation in the energy distribution increases, which is often called "cold light". For white LED, the proportion of yellow light in low temperature light source is relatively high, while the proportion of high color temperature light source is relatively high. From the perspective of human vision, low color temperature gives people a warm and stable feeling, while high color temperature gives people a cool and refreshing feeling.

It is worth noting that in the first batch of LED street lamp color temperature selection, almost all manufacturers chose 6000K, or even above 6000K, which runs counter to the high-pressure sodium lamp. Why? Because under the technical conditions of early phosphors, the LED efficiency of cold white light source is higher. Compared with color temperature, people pay more attention to the physical properties of gravity effect. The most important way to improve the light efficiency is to improve the excitation efficiency of phosphors. The excitation efficiency of yellow powder is much higher than that of orange powder. Obviously, higher light efficiency with higher color temperature can be obtained. The light efficiency of 5500 ~ 6500k color temperature is 48.7% higher than that of warm white light below 3500K.