How is LED color temperature defined and applied?

02/03/2020

We have already known that the LED strip lighting has many unique characteristics, which enables it to be utilized in various kinds of environments. For now, it has seized large market shares and is very popular among customers. Actually, besides colors, brightness, and service life, the color temperature of LED products also plays a very important role during the decoration. Different color temperatures may create different decoration effects. In this passage, we mainly talk about the definition of color temperature and the applications.

1) Definition of color temperature:

When heating a standard black body with complete absorptive and emissive power, its color will change along with the temperature. According to the Black Body Locus of the CIE Color Coordinate, the color changing process of the black body is: red— salmon red— yellow— yellowish white— white— blue white. During the heating process, if the color of the LED strip lighting is same or close to that of the black body, we define the temperature of the black body at that time as the color temperature of the light source, and we regard the absolute temperature K as the unit.

Generally speaking, the white or blue LED strip lighting has higher color temperature, and yellow or red ones have lower color temperature. At the same time, cold colors have higher color temperature than warm colors. Take the sunshine for example, the light color of sunshine also changes with time: it looks yellow in the morning, and the color temperature is about 3000K; it looks snow white at noon, and the color temperature increases to 4800—5800K (in cloudy days it is about 6500K); the color temperature of the sunshine decreases again to 2200K at dusk.

The color temperature is the reflection of human eyes upon the LED strip lighting, which is a complex feeling based on physics, physiology, and psychology. Sometimes the color temperature could be changed artificially. For example: if we adopt incandescent lamps of 3200K when taking a photograph, we could utilize a red light filter to add some red lights, which may cause that the photo has a lower color temperature. In the same way, we could reduce certain red lights on the TV to make the color temperature of the picture higher.

The favor of the LED strip lighting varies from person to person, which is closely related with the scenery we see everyday. For example, people who live near the equator often see sceneries of high color temperature (8000K at dusk and 17000K at noon, 11000K on average), so they prefer higher color temperature because it looks more real. On the contrary, people who live at higher latitudes (where the scenery has color temperature of 6000K on average) like low color temperature. Generally, as the average color temperature in China is around 8000-9500K, our TV stations usually take 9300K when recording shows. However, as European scenery is different from China, the color temperature of which is 6000K on average, their shows usually adopts this color temperature. This difference results that we may feel a little uncomfortable when we see European shows at the first sight.

2) Applications of color temperature

Different color temperatures may have different influences upon human feelings, so the application is also diverse according to various working environments of the LED strip lighting. Color temperature is the most general index to represent the quality of the lights emitted by LED strips. If the color temperature is below 2800k, the lights are mainly red and yellow, which could provide people with warm, pleasant, and lively atmosphere, but for unhappy people it may cause irritable feelings; if the color temperature is between 2800K and 5000K, there are proportionally red, green, and blue lights. The lights of the LED strip lighting are close to sunshine and provide people with natural, comfortable, and stable feelings; if the color temperature is between 5000 and 7000K, there are mainly blue lights, which is unpleasant to look at and provide people with calm, deserted, and serious feelings; if the color temperature is more than 7000K, the lights empurple and have lots of flares, which provide people with sad and grave feelings.

Generally speaking, most shopping centers hope to provide a warm environment for customers (i.e. a relatively comfortable environment), so they usually use the LED strip lighting the color temperature of which is around 3000-5000K. The lighting for sitting rooms should be diverse: there is not only basic lighting but also accent lighting and romantic lighting. Thus the illuminating effects should create an ideal atmosphere; the lighting for dining rooms should concentrate people's attention on the dining table. Meantime, the lighting should also be able to highlight the color of foods and arouse people's appetite; the lighting for bedrooms should better adopt neutral color temperature, which could create a relaxing atmosphere.

Usually the LED strip lighting of low color temperature could provide people with warm and sincere feelings. For wedding, we adopt low temperature to create a warm and romantic atmosphere. According to the professional study, the lights people see contain seven colors, and the color temperature is specially used to measure the color composition. Most living rooms adopt white energy-saving lamps in reality. Only if we replace them by the LED strip lighting of low color temperature, which contains many red lights, we could achieve hazy, easy, and warm atmosphere indoors.

In addition, we also should consider that the color temperature of the LED strip lighting should cooperate interactively with the key tone of the working environment. Places with warm tone should better adopt light sources of low color temperature (about 3000K), which could strengthen the warm feelings; places with cold tones should better adopt light sources of high color temperature (more than 5000K), which could create romantic feelings together with local spotlights of low color temperature.