What is a lumen unit?

Lumen was originally defined as a standard candle made of whale oil with a mass of 75.5g and a straight passage of 2.2cm. Under the condition of burning 7.78g per hour and a flame height of 4.5cm, if the center point is a sphere with a radius of 1m, the luminous flux on the sphere of 1m2 is 1cm. According to the relationship between the surface area and the radius of a sphere, a candlelight light source can produce a luminous flux of 12.566 lumens.

The luminous flux of a uniform point light source is equal to one candle in a unit solid angle. For example, if we use a parabolic reflector to concentrate the light of LED lamp beads in one direction, it will look very bright. If the reflector is removed, the light will drop immediately. In this process, the luminous flux of LED lamp beads has not changed, so lumen is not equal to brightness.

Lumen illumination value:

Unit lux.

1, night: 0.00 1-0.02.

2. Moonlit night: 0.02-0.3.

3, indoor cloudy: 5-50.

4. It is cloudy outside: 50-500.

5. Adequate indoor sunshine: 100— 1000.

6. The illumination in the sun at noon in summer: about 10*9 power.

7. Illumination required for reading books and periodicals: 500-600.