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LED luminous intensity of basic knowledge articles

Jun 01, 2017

First, the analysis of commonly used luminous intensity measurement units


The luminous intensity of the luminous body is measured in units of:

1. Illumination unit: Lux (Lux)

2. Luminous flux unit: lumen (Lumen)

3. luminous intensity unit: candlelight (Candle power)

Here first explain 1CD (candlelight: candela): refers to the complete radiation of the object, in the platinum freezing point temperature, every six tenths of a square centimeter area of the luminous intensity.

And then explain 1Lux (lux): refers to the perimeter of the received luminous flux of 1 lumens when the illumination. The relationship between illuminance and luminosity, distance is: E (illuminance) = I (luminosity) / r2 (distance square)

Finally, explain 1L (lumens): refers to a CD candle light in the distance of 1 cm, an area of 1 square centimeter on the plane of the luminous flux.


Second, LED luminous intensity unit doubt

Such as LED, incandescent type of active light-emitting body using candlelight (CD) for the luminous intensity unit. While the reflective or penetrating object uses lumen (L) luminous flux units. Illumination unit Lux (Lux) is used for photography and other fields. These three units of measure are numerically equivalent, but need to be understood from different perspectives. For example, the LCD projector's brightness (luminous flux) is 1600 lumens, if the projection to the size of 60 inches (1 square meters) of the total reflection screen, then the illumination of 1600 lux. And then assume that its light from the light source 1 cm, the output port area of 1 square centimeter, then the light port of the luminous intensity of 1600CD. However, in fact, because the LCD projector in the optical transmission loss, reflection or loss of light film and other reasons, its brightness can generally reach 50% efficiency is good. To the current application experience, the outdoor LED display in order to get the ideal display in the sun to achieve more than 4000CD / square meter brightness Caixing. Ordinary indoor LED, the maximum brightness of 700 ~ 2000 CD / square meters can be.