Summary:In recent years, air quality has deteriorated sharply, and many large and medium-sized cities are also facing haze weather. Some cities have an averag
In recent years, air quality has deteriorated sharply, and many large and medium-sized cities are also facing haze weather. Some cities have an average of more than 100 haze days per year. Most of the cities with severe smog are economically developed, and they often play a leading role in the promotion of LED street lights. Therefore, it is of great significance to study and discuss the selection of LED street lights in haze weather.
LED light sources are divided into three types: warm white, neutral white, and cool white. The discharge radiation of traditional street lamps and sodium lamps is concentrated on two double D lines of 589.0nm and 589.6nm, so the color temperature is generally about 2300K warm white light, which is obviously yellow under human vision. LEDs can manufacture light sources with different color temperatures through packaging technology, thereby providing a variety of different options for road lighting.
At present, LED packaging technology can obtain LED white light sources with different color temperatures by applying phosphors with different excitation wavelengths and adjusting the amount or ratio of phosphors. The color temperature of light emitted by different light sources is different. The characteristic of the low color temperature light source is that in the energy distribution, there is relatively more red radiation, which is often called "warm light". After the color temperature rises, the proportion of blue radiation in the energy distribution increases, often called "cold light". For white LEDs, the proportion of yellow light in low-temperature light sources is relatively high, while the proportion of high-color temperature light sources 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 have chosen 6000K, or even 6000K or more, which runs counter to the high-pressure sodium lamp. Why? Because under the technical conditions of early phosphors, the light-emitting diodes of cold white light sources are more efficient. Compared with color temperature, people pay more attention to the physical properties of light effect. The most important way to improve light efficiency is to increase 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.