Today SUNROLED introduce the LED Knowledge of LED Luminous Flux to you.

LED luminous flux (F, Flux)

The Unit is lumens, ie lm.  the definition of LED Lumous Flux is that the the light source emitted the light  in unit time.Similarly , the amount of light  is a description of the size of the total light. It is equivalent to the optical power. the light lminous flux is larger, which means that more light is emitted.

For isotropic light ( ie. light sources emit light with  the same density in all directions) , then F = 4πI. In other words , If the light source I was 1cd, the total luminous flux of 4π = 12.56 lm. Compared with the mechanics of the unit , flux is equivalent to pressure and the luminous intensity is equivalent to the pressure .  in order to make the irradiated object looks brighter, we must not only increase the flux, but also Converging means.  in fact, the area is reduced so as to get greater strength .

You know, the amount of flux is also man-made , may not be the same for the other animals , but it is not a completely natural thing , because this definition is based entirely on the response of the human eye to the light .
human has different feels to different colors of light, and this feeling determines the conversion between flux and optical power . For example, people is most sensitive to yellow-green 555nm , 1W = 683 lm,that means , 1W of power are transferred into all wavelength 555nm Light , that is 683 lumens. This is the maximum light conversion efficiencyand the scaling value, because the human is the most sensitive to light of 555nm. For other colors of light , such as 650nm red color , 1W light corresponds to only 73 lumens, this is because the human is not sensitive to red light . For white light , It is depending on the situation, because a lot of different spectral structure of light are white light. For example, LED white light, white and daylight TV  have a big difference, because of different spectra .

Now I take comon white color as example, 0.06W → 3-5LM, 0.2W →13-15LM, 1W → 60-80LM.