[Source: "High-tech LED - Technology and Applications" January issue Zhang Yucong / Yin Jian]
I. Introduction
With the improvement of people's quality of life, the concept of the lamp is no longer stuck in the lighting. If solid-state lighting technology is adopted, the designer can obtain new functions, such as adjusting the white color temperature, and changing the current of each chip. Chip brightness, the adjustment of color temperature and color rendering index.
Solid-state lighting also has the advantages of energy saving, cost reduction, and extended equipment working time. These advantages have promoted the wide application of LED technology in the lighting market.
Second, the color temperature adjustable white LED
2.1 Basic concepts
The color temperature refers to a value indicating the color of light by the temperature of a black body (a virtual object that can theoretically completely absorb external light). The unit is K (Kelvin). The wavelength distribution (hue) of the black body emitting light varies depending on the temperature. In general, when the color temperature is low, it looks red, and when the color temperature is high, it turns blue.
The spectral distribution of the light source determines the optical parameters of the light source. The color temperature is used to measure and calculate the color component of the light. The color rendering affects the color of the object observed by the human eye.
2.2 LED white light basic principle
At present, there are two main mainstreams of white LED production technology on the market:
1. A yellow phosphor is excited by a blue chip. A part of the blue light is absorbed by the phosphor, and the phosphor is excited to emit yellow light. The emitted yellow light is mixed with the remaining blue light to adjust their intensity ratio to obtain white light of various color temperatures;
2. LEDs of two (or more) different colored lights are combined to form white light.
Comparing the above two white LED methods, (1) the most mature technology and low cost, but the color shift and color rendering are not good, and should be improved with appropriate red and yellow phosphors; and method (2) color rendering The best, but the cost is higher.
At present, high color rendering white LEDs require a color rendering index to be in a given range to maximize their luminous efficiency, which is a problem that is optimized according to constraints. The color temperature tunability is a white LED that cannot be based on phosphors. To overcome this problem, the color temperature can be adjusted only by multi-chip packaging.
For more information, please refer to the January issue of "High-tech LED-Technology and Applications" magazine.
I. Introduction
With the improvement of people's quality of life, the concept of the lamp is no longer stuck in the lighting. If solid-state lighting technology is adopted, the designer can obtain new functions, such as adjusting the white color temperature, and changing the current of each chip. Chip brightness, the adjustment of color temperature and color rendering index.
Solid-state lighting also has the advantages of energy saving, cost reduction, and extended equipment working time. These advantages have promoted the wide application of LED technology in the lighting market.
Second, the color temperature adjustable white LED
2.1 Basic concepts
The color temperature refers to a value indicating the color of light by the temperature of a black body (a virtual object that can theoretically completely absorb external light). The unit is K (Kelvin). The wavelength distribution (hue) of the black body emitting light varies depending on the temperature. In general, when the color temperature is low, it looks red, and when the color temperature is high, it turns blue.
The spectral distribution of the light source determines the optical parameters of the light source. The color temperature is used to measure and calculate the color component of the light. The color rendering affects the color of the object observed by the human eye.
2.2 LED white light basic principle
At present, there are two main mainstreams of white LED production technology on the market:
1. A yellow phosphor is excited by a blue chip. A part of the blue light is absorbed by the phosphor, and the phosphor is excited to emit yellow light. The emitted yellow light is mixed with the remaining blue light to adjust their intensity ratio to obtain white light of various color temperatures;
2. LEDs of two (or more) different colored lights are combined to form white light.
Comparing the above two white LED methods, (1) the most mature technology and low cost, but the color shift and color rendering are not good, and should be improved with appropriate red and yellow phosphors; and method (2) color rendering The best, but the cost is higher.
At present, high color rendering white LEDs require a color rendering index to be in a given range to maximize their luminous efficiency, which is a problem that is optimized according to constraints. The color temperature tunability is a white LED that cannot be based on phosphors. To overcome this problem, the color temperature can be adjusted only by multi-chip packaging.
For more information, please refer to the January issue of "High-tech LED-Technology and Applications" magazine.
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