The color temperature of LED street lights in different lighting scenes gives people different feelings. In low-light scenes, low-color temperature light makes people feel happy and comfortable; high-color temperature light makes people feel gloomy, dim, and cold; in high-light scenes, low-color temperature light makes people feel stuffy; high-color temperature light makes people feel comfortable and happy.
The new method of LED color temperature adjustment adopts the PWM dimming drive power supply solution, adds a color temperature adjustment circuit to the back-end circuit of the power supply, and the color temperature adjustment circuit adopts PWM switch dimming to adjust the conduction time ratio of the cold white light LED array and the warm white light LED array to achieve color temperature adjustment.
LED street lights with a color temperature of about 5000K emit white light, and those with a color temperature of about 3000K emit yellow light or warm white light. Yellow light or warm white light of around 3000K is more suitable for road lighting, while LED street lights with a color temperature of around 5000K are not suitable for road lighting. Because the color temperature of 5000K will make people feel very cold and dazzling visually, it will cause excessive visual fatigue, and under this color temperature condition, people’s long-distance observation ability will also decrease. During the packaging process, by applying phosphors with different excitation wavelengths and adjusting the amount or proportion of phosphors, LED white light sources with different color temperatures can be obtained. Color temperature is a scale representing the color of the light source. When the radiation of an absolute black body is exactly the same as the radiation of the light source in the visible light region, the temperature of the black body is the color temperature of the light source.
Different light sources emit different color temperatures. The characteristic of low color temperature light sources is that the red radiation in the energy distribution is relatively more, usually called “warm light”; when the color temperature increases, the proportion of blue radiation in the energy distribution increases, usually called “cold light”.
Medium color temperature, color temperature is between 3000–6000K. People do not have a particularly obvious visual psychological effect under this color tone, and feel refreshed; so it is called “neutral” color temperature. When illuminated by a medium color temperature light source, blue feels cool.
High color temperature: When the color temperature exceeds 6000K, the light color is blue, giving people a cool feeling. When illuminated by a high color temperature light source, objects feel cold. Color temperature and brightness Under the irradiation of a high color temperature light source, if the brightness is not high, it will give people a gloomy atmosphere; under the irradiation of a low color temperature light source, if the brightness is too high, it will give people a stuffy feeling.