Evaluation method of color rendering of LED lighting(I)
Color is one of the feelings of people, it is always with the observer's personal subjective experience. Everyone to see a color after the feeling that others are difficult to know. So the color of the study is always full of mysterious imagination. At the same time, the color and make the world become colorful, visual arts, image display and transmission, textile printing and dyeing, color printing, etc., are inseparable from the color of the study. So the color of the study, the color of the objective quantitative description, as many scientists to study the object.
Newton in 1664 with the prism to white sunlight scattered into different colors of the spectrum, laid the physical basis of light color. 1860 Maxwell with different intensity of red, yellow and green light with the light from the white light has been to a variety of colors of light, laid the basis for three-color chromaticity. On this basis, the 1931 International Commission on Illumination established the CIE chromaticity system and continued to improve. Today CIE chromaticity systems have been widely used to quantitatively express light colors.
The color can not be separated from the lighting, only in the light of the object is likely to show the color, and the color of light on people's psychology has a very big impact. Professor Yang Gongxia of Tongji University has made a very wonderful description in his fifth chapter, "The Visual and Visual Environment".
Under the same light source, the same object will show different colors. Such as green leaves in the green light, there are bright green, in the red light near the black. Thus, the light source of the object according to the color of the show, plays an important role. Light source in the irradiation of objects, the ability to fully display the color of the material, known as the light source color.
In 1965, the International Commission on Illumination recommended in the CIE chromaticity system, with the general color rendering index Ra to describe the light color. General color rendering index Ra is still very successful, has been widely accepted by the lighting industry, but there are some problems, this paper will be the color of the light color evaluation methods, as well as the progress of recent years introduced.
1. General color rendering index Ra
The color of the light source of the evaluation method, hoping to be both simple and practical. However, simple and practical is often two contradictory requirements. In the CIE color system, the general color rendering index Ra is such a compromise product: it is relatively simple, only a value of 100 or less, you can express the light color performance, Ra = 100 is considered the ideal color Sex.
However, sometimes people feel that is not the case. For example, in the incandescent light of the leaves, looks and not very bright. Where is the problem? Let's talk about what is the general color rendering index.
For the sake of simplicity, we only discuss the main constituent methods of the general color rendering index Ra, without discussing its specific calculation method.
In fact, in our daily life, we often check the color of the light source. Many people have this experience, careful ladies in the mall to buy clothes, often also to the outdoor sun and then look at its color. She did so, in fact, is to test the color of the light source of shopping malls: take a look at the same piece of clothing, under the lighting in the mall light and under the lighting of the sun, the color of the clothes are different. So describe the color of the light source, the need for two additional elements: daylight (reference light source) and clothes (colored objects).
For example: I am a friend, home decoration to buy wood flooring.
She saw the wood floor in the store color is like this: