General knowledge of LED intensity

1. Definition of candlelight, international candlelight and Candela

Under the standard atmospheric pressure of 101325 newton per square meter, the luminous intensity of an absolute "black body" with an area of 1 / 60 square centimeter (that is, an ideal object that can absorb all external light without reflection) along the vertical direction is 1 candela at the solidification temperature of pure platinum (about 2042k to 1769 ℃). In addition, the three concepts of candlelight, international candlelight and candela are different and should not be equated. In terms of quantity, 60 candela is equal to 58.8 candela, and 1 candela of Hefner lamp is equal to 0.885 candela or 0.919 candela.

2. Luminous intensity and brightness

Luminous intensity is abbreviated as luminous intensity, the international unit is candela (candela) abbreviated CD. LCD refers to the luminous flux emitted by the light source within the unit solid angle in the specified direction. When the light source radiation is uniform, the light intensity is I = F/ Ω，Ω Is the solid angle, the unit is sphericity (SR), f is the luminous flux, the unit is lumen, for the point light source, I = f / 4. Luminosity refers to the ratio of the luminous intensity of the luminous surface in the specified direction to the area of the luminous surface perpendicular to and in the specified direction, in candela per square meter. For a diffuse surface, although the light intensity and flux in each direction are different, the brightness in each direction is equal. The TV screen is similar to such a diffuse surface, so viewing images from all directions has the same sense of brightness.

3. MCD value

MCD value is a nonstandard term in the industry. Because of different testing instruments, the measured MCD value of the same product varies from manufacturer to manufacturer. In the actual sales process, the two most commonly encountered concepts are lumen and brightness (MCD) value. As a salesperson, you don't need to fully understand the technology, but you need to keep in mind the MCD value of our conventional small power LED lights (subject to the parameters listed in the quotation).