Luminous color What are warm light, sunlight and white light?

White light: the (white) light source between 3000-5000 K gives people a refreshing feeling.

Cold light: light source >; 5000 gives a cold (bluish white) feeling.

It is generally believed that the color temperature of standard white light is 6500K, and that of standard sunlight is about 5200 ~ 5500 K; The color temperature of news photography lamp is 3200 k; General tungsten lamp, the color temperature is about 2800K, such as purple light, above 9000K K.

Extended data

Through the corresponding feeling, the relative color temperature (CCT) of white light expressed by absolute temperature scale is often used to define its brightness, that is, "warm" or "cold". Warm white light is orange, and its relative color temperature is below 3500K (incandescent light source is 2700-2900K). Cold white light is more similar to cold color, such as blue, and its relative color temperature is above 5500K (6500K is the standard sunlight illumination).

The color rendering index (CRI) includes a value of 0- 100, which can reflect the ability of the light source to copy the colors of other illuminated objects relative to the reference light. According to the definition, the daylight color rendering index is 100. In shops, school buildings or offices, the color rendering index of lamps should be higher than 80. Table 1 summarizes the main terms used to define the amount of light. Tables 2 and 3 are examples of the correlation between brightness and illuminance corresponding to natural light and artificial light.

The light emitting diode itself emits a monochromatic light source, and its energy conversion efficiency is determined by the light emitting wavelength. The main wavelength emitted by semiconductor nodes is mainly determined by the energy gap between conduction band and valence band.

In addition, according to the node temperature, the released spectral lines have full width at half maximum (FWHM). At first, commercial LEDs were all red, but today almost all saturated colors can be achieved. The key problem of manufacturing LED is how to penetrate the general lighting market on a large scale and obtain energy-saving white LED. How do LEDs produce white light? At present, there are three main methods to generate white light from light emitting diodes.

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