In the practical use of LED, light intensity calculation often uses data units which are easy to measure or change direction. CD/m2 is generally used as the unit of luminous intensity for the active luminescent body of LED display screen, and with the observation angle as the auxiliary parameter, which is equivalent to Lux, the unit of illumination on the surface of the screen; multiplying this value with the effective display area of the screen, we can get the luminous intensity of the whole screen in the best perspective, assuming the screen. If the luminous intensity of each pixel is constant in the corresponding space, this value can also be considered as the luminous flux of the whole screen. Generally, the brightness of outdoor LED display should reach 4000CD/m2 or more before it can display in daylight. The maximum brightness of ordinary indoor LED is about 700-2000 CD/m2.
The luminous intensity of a single LED is based on CD and is equipped with visual angle parameters. The luminous intensity has nothing to do with the color of the LED. The luminous intensity of a single tube varies from several mCDs to five thousand mCDs. The luminous intensity given by the LED manufacturer refers to the point where the luminous intensity of the LED is the strongest at 20 mA current, the best viewing angle and the center position. When encapsulating the LED, the shape of the top lens and the position of the chip from the top lens determine the angle of view and intensity distribution of the LED. Generally speaking, the larger the angle of view of the same LED, the smaller the maximum luminous intensity, but the accumulated luminous flux on the whole hemisphere remains unchanged.