Dry goods丨Ten indicars of LED lighting quality comprehensively

　　Article source: OFweek Semiconducr Lighting

　　Lighting quality refers  whether the lighting source meets the lighting indicars such as visual function, visual comfort, safety, and visual beauty.

　　The correct application of the lighting quality indicars will bring a new experience  your lighting space, especially in the LED lighting era, where the performance of lighting quality is extremely important. Using the lighting quality indicars  buy LED light source products will bring twice the result with half the effort. Effects, below, we introduce the main indicars of lighting quality.

　　1. Color temperature

　　It is the light color of white light, which distinguishes whether the light color of white light is reddish or bluish. It is expressed by absolute temperature and the unit is K (Kelvin). Usually the color temperature range of indoor lighting is 2800K-6500K.

　　The most typical illuminating white light is sunlight. As we all know, sunlight is a mixture of multiple colors of light. Among them, the most important light is red, green and blue. (The picture on the right is an exploded view of sunlight after passing through the prism, which can verify that sunlight is a mixture of multiple colors of light.)

　　White light uses color temperature indicars  describe the color of light. When there are many blue components in white light, the color of white light will be bluish (cold, such as the northern winter sun at noon). When there are many red components in white light, the color of white light will be biased. Red (warmer, such as morning and evening sunlight), color temperature is the only way  express the color of white light.

　　The white light of artificial light sources is also formed by mixing light of multiple colors. For artificial light sources, we also use color temperature  describe the light color of white light; for the physical analysis of white light, we usually use the method of spectral analysis. The spectral analysis of white light requires special Instrument test production. The figure below shows various spectra.

　　It can be seen from this figure that the spectral components of sunlight are rich and full. The spectral distribution of incandescent lamps and LED lamps in artificial light sources is better than that of high-pressure sodium lamps and fluorescent lamps. The spectrum of fluorescent lamps contains ultraviolet components that are harmful  the human body. High energy consumption will be eliminated. LED light source will be the leading product of lighting source.

　　When describing the color of white light, many people will use warm white light, natural white light, daylight white light, and cold white light  classify.  ensure the quality of lighting, this classification range is o large. Color temperature should be used  describe white light. Generally, LED white light color temperature and white light The corresponding relationship of light and color is shown in the left figure below (a brief description). The international standard color temperature distinction should be based on the CIE1931 chromaticity diagram, as shown in the right figure below:

　　The precise color temperature value must be tested by professional instruments. When purchasing lighting products, describing color temperature is a more troublesome problem. In order  have an intuitive understanding, we have made a color temperature visual legend. This visual legend intuitively distinguishes the color temperature of lighting products. As shown below:

　　2. Color rendering

　　It is the degree of resration of the surface color of the illuminated object by the illuminating light source. It is expressed by the color rendering index Ra. The range of Ra is from 0-100. The closer the value of Ra is  100, the higher the color rendering and the better the resration of the color of the illuminated object surface. The color rendering of the light source requires professional instrument testing.

　　It can be seen from the solar spectrum that the solar spectrum is the most abundant and the light source with the best color rendering. The color rendering of artificial light sources is always lower than that of sunlight. Therefore, the best way  identify the color rendering of artificial light sources is with The easiest way  compare the sunlight is  compare the color of the palm or the face under the sunlight and the artificial light source. The closer  the color under the sunlight, the better the color rendering. You can also look at the palm with the palm of your hand facing the light source. If the color of the palm is gray or yellow, the color rendering is not good. If the color of the palm is blood red, the color rendering is normal (as shown below):

　　For LED light sources, Ra can be roughly divided in 3 levels, Ra is less than 69, Ra is between 70 and 79, and Ra is greater than 80. For high-quality indoor lighting, light sources with Ra greater than 80 should be used. The color rendering index and the degree of color resration can refer  the visual comparison in the figure below.

　　my country adopts the CIE test standard. For LED light sources, the general color rendering index Ra does not reasonably reflect the color rendering performance of LED lighting sources. CIE also does not provide new test standards. For users who pursue high color rendering capabilities, you can Refer  the Planck curve in the CIE1931 chromaticity diagram (the black line in the figure below). The closer the measured coordinate value is  the Planck curve, the better the color rendering ability of the light source.

　　3. The illuminance value of the light source

　　Illuminance is the luminous flux of the light source shining on the unit area of ??the illuminated object. It indicates the degree of brightness and darkness of the surface of the illuminated object, expressed in Lux (Lx). The higher the illuminance value of the illuminated surface, the brighter the object is illuminated.

　　The magnitude of the illuminance value has a great relationship with the distance from the light source  the illuminated object. The farther the distance, the lower the illuminance value. The illuminance value is also related  the light distribution curve of the lamp. The smaller the light output angle of the lamp, the higher the illuminance value. The greater the light output angle, the lower the illuminance value; the illuminance value needs  be tested by a special instrument.

　　From a phometric point of view, luminous flux is the main indicar. As a lighting product, it mainly reflects the brightness of the surface of the illuminated object. It is more accurate  use the illuminance value  describe the lighting effect. The illuminance value of indoor lighting reflects the effect of indoor lighting. Brightness and darkness, o high illuminance and o low illuminance have an impact on the health of human eyes. Therefore, the illuminance value of indoor lighting needs  refer  the national standard (Table 1), and the illuminance value recommended in this table will not appear. o high or o low illuminance.

　　Table 1 Standard value of illuminance for residential building lighting

　　4. The light distribution curve of the lamp

　　The indoor lighting effect is related  the layout of the lamps and the light distribution curve of the lamps. A good lighting effect is reflected in the reasonable layout of the lamps and the correct application of the light distribution of the lamps. The layout of the lamps and the light distribution of the lamps determine the visual function and visual comfort of the indoor lighting, and reflect the three-dimensional sense and layering of the lighting space. Among them, the proper light distribution application of the lamps can improve the lighting quality of the entire lighting space.

　　The role of lamps is  fix and protect the light source, as well as  decorate and beautify the environment. Another purpose of the luminaire is  redistribute the light output of the light source so that the light of the light source outputs light according  the light output angle of the luminaire design. This is called t