A theoretical basis for supporting the color rendering index of a tungsten filament lamp is 100: the color rendering is compared with sunlight, and the principle of solar illumination is heat and light, that is, the sun is regarded as a black body. The principle of the luminescence of the tungsten filament lamp is the same as the principle of the solar illuminating. After the energization, the tungsten filament generates heat and then illuminates. The two principles are the same, and both are heated and illuminate, so the color development of the light emitted by the tungsten filament lamp and the sunlight The color rendering is the same, so the color rendering is 100. This argument has some truth but is not completely correct, and the reasoning process is too big. The filament in the tungsten lamp is tungsten wire. The melting point of the tungsten wire is 3410 degrees, which means that the color temperature of the tungsten lamp is up to 3410 degrees. Due to various reasons, the color temperature of the tungsten lamp in the market is mostly 2700°. The temperature of the heating element (tungsten wire) is 2700 degrees. Because the principle of illumination of the tungsten lamp and the sun is the same, the color rendering property of the tungsten lamp is Ra=100, and the step is too large. The surface temperature of the sun is about 5,500 degrees Celsius, the center temperature is about 20 million degrees Celsius, and the temperature of the solar layer is about 500,000 degrees Celsius. When the temperature of the heating element is high, the color temperature is high, and when the color temperature is high, the color is blue, and when the color temperature is low, it is reddish yellow. That is to say, the same black body heats up and emits light, while the temperature is high, the blue light is much, and the low temperature is red and yellow light. From this point, it can be seen that the light emitted by the tungsten lamp contains relatively more red yellow light, and the light emitted by the sun contains relatively more blue light. We can see objects because there is light that illuminates the object. The object reflects the light into our eyes. We can distinguish the color of the object because objects of different colors reflect different colors of light. The color of the object is not only related to the object itself. Also related to the light source that illuminates it, the green light red apple, the black apple will be seen. The principle of illumination of a tungsten filament lamp is the same as that of the sun. However, the light it emits contains more red and yellow light and less blue light. Its color rendering is different from sunlight, especially for blue objects. The color is developed because it lacks the blue spectrum itself. . The following is a spectrum of sunlight and tungsten lamps: Blue objects are absolutely different under incandescent light and under sunlight, and there is very little blue spectrum in the light emitted by tungsten lamps. The spectral distribution of the light source determines the color rendering of the light source. If the spectrum of a certain wavelength band contained in the light source is small, then the color of the light source of the light source of the light source is inevitably poor, and if the light source contains a certain The spectrum of a band is very large, and the color rendering of the color of the object of the band of the light source is high. Taking lighters as an example, ordinary lighters and straight-through lighters are all hot and luminous, and the light colors are different. Ordinary lighter flame red yellow, straight into the lighter flame blue. The use of these two kinds of light to illuminate a white wall, the result is also different, straight into the lighter blue flame to illuminate the wall, the white wall will also become a blue wall. So is the color rendering index of incandescent lamps 100? The color rendering index of an incandescent lamp is 100, which is indeed Ra=100. The key to the problem is how is this color rendering index measured? In theory: The color rendering is compared to the sun. In fact, when measuring the color rendering index of incandescent lamps, this is measured: (Source: http://blog.sina.com.cn/s/blog_5460f7a30101agwb.html) The color rendering index of a light source with a low color temperature (less than 5000 K) is based on the Planck radiator as a reference standard rather than sunlight. The tungsten filament lamp has a color rendering index Ra=100 compared to the Planck radiator. in conclusion: The color rendering index of a tungsten lamp is indeed 100. However, its color rendering is not high. Our eyes are right, it is really yellowish, and it is very different from daylight. The problem lies in the evaluation criteria of the color rendering index.
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The color rendering of an incandescent lamp is 100? impossible.
Life experience tells us that incandescent lamps are one yuan in the market, and they are yellow. Why is his color rendering index Ra=100?