The amount of light emitted by the light source per unit time: LED luminous Flux (F, Flux) per unit lumen, i.e. Lm.The amount of light emitted by the light source in unit time is called the luminous flux of the light source.Similarly, this quantity is for the light source, and it describes the total amount of light emitted by the light source, which is equivalent to the light power.The greater the light flux, the more light is emitted.
F=4 PI I for isotropic light from a lamp pole (that is, the light from a light source is emitted at the same density in all directions).In other words, if the light source I is 1cd, the total luminous flux is 4 PI =12.56lm.Compared to mechanical units, luminous flux corresponds to pressure, and luminous intensity corresponds to pressure.In order for the point to be illuminated to look brighter, we need not only to increase the luminous flux, but also to increase the means of convergence, which is actually to decrease the area, in order to get more intensity.
Remember, light flux is also an artificial quantity, which may not be the same for other animals, much less something completely natural, because this definition is based entirely on the response of the human eye to light.
Human eyes perceive light of different colors differently, which determines the conversion relationship between luminous flux and luminous power.For the 555nm yellow and green light most sensitive to human eyes, 1W=683lm, that is to say, the power of 1W is converted into 555nm light with a wavelength of 683 lumens.This is the maximum light conversion efficiency and also the target value, because the human eye is most sensitive to light at 555nm.For other colors of light, such as red at 650nm, a watt of light is equivalent to only 73 lumens, because the human eye is not sensitive to red light.For white light, it depends, because a lot of different spectral structures are white.LED white light, TV white light and daylight, for example, vary widely, with different spectra.
Common white LED lumens are listed as follows: 0.06w → 3-5lm, 0.2w → 13-15lm, 1W→ 60-80lm.(for reference only)
