he radiant flux Φe marked in red in the report is the optical power. From the perspective of energy conservation, it is understood that the LED consumes 31.21W of electric power, 11.97W (accounting for 38.36%) becomes optical power, 19.24W (accounting for 61.64%) Converted into heat power, 3922lm of light was emitted.
If the thermal power is not considered (pretending to only consume 11.97W of electricity), the ultimate luminous efficiency or luminous efficiency (LER) that this device can achieve is:
What the hell is LER?
Above, we talked about a professional term optical visual performance (LER), but shit, what the hell is this? Hold in a hurry, ask me.
Now suppose we have invented an ideal LED that does not generate heat and can convert electrical power P100% into optical power PV. (In the theoretical world, ideals are still necessary, although they cannot always be realized)
The luminous efficacy at this time is the theoretical maximum value. This value also has a scientific name called luminous efficacy of radiation (LER).
The theoretical calculation formula of LER is as follows (I know you don’t understand~~):
The Km in the formula is called the maximum luminous efficiency, which is equal to 683lm/W, which means the most sensitive yellow-green light (555nm) of the human eye. The light power of 1W is equivalent to 683lm luminous flux.
When the shape of the spectrum is determined, the optical performance (LER) is also determined. (Do you know that there is a portable artifact for measuring spectrum?)
The theory and formula are not good (yong) understand, let me give you another chestnut