What do high lumens and low lumens of LED mean?

The high lumen and low lumen of LED refer to the intensity of light emitted.

The so-called lumen is a physical unit to describe the luminous flux, which is physically interpreted as that a candle (cd, candle intensity unit, equivalent to the luminous intensity of an ordinary candle) is on a solid angle (on a unit sphere with a radius of 1m, the angle represented by the spherical cone corresponding to the spherical cap of 1m corresponds to a circle with a middle section of about 65).

Considering that the solid angle of the whole sphere is 4π, the total luminous flux emitted by 1 candle is 4π lumens. The total solid angle of a ball of any size is 4π, so the total luminous flux of candlelight is fixed at 4π, which does not change with the change of distance, so it is wrong to say that the total luminous flux emitted by 1 candlelight is 1 lumen at about 0.28m around it.

Extended data

1967 The 13th French International Metrology Conference stipulated that Candeira, Candeira /m2, lumen and lux should be used as the units of luminous intensity, brightness, luminous flux and illuminance respectively, which is of great significance to unify the optical measurement units used in engineering technology.

The intelligent LED system developed by Taiwan Province Provincial Resources Planning Committee can also detect the change of ambient light intensity and the activities of pedestrians and vehicles at any time by using brightness sensors and microwave pedestrian and vehicle sensors, and transmit information, analyze and automatically adjust the light brightness through ZigBee wireless sensor network and PLC technology.

During the activities of unmanned vehicles, the system will automatically adjust the LED lighting to low lumen lighting that is environmentally safe; On the contrary, when people and vehicles are in intensive activities, high lumen LED lighting will be used to improve the driver's line of sight clarity and ensure driving safety.

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