一. Basic knowledge of the LED
LED takes from Light Emitting Diode, Chinese translated into “light-emitting diodes (leds), as the name implies light-emitting diodes (leds) is a kind of electric energy into Light energy can be electronic device has the characteristics of the Diode. The different leds emit from the infrared to the different wavelengths of light blue, currently emit violet and ultraviolet light-emitting diodes (leds) have also been born. There are painted in blue light LED phosphors, the blue light is converted into the white light of white LED.
Luminous Intensity of LED:
The measuring unit of luminous intensity unit of illuminance (Lux), luminous flux unit (Lumen), unit of luminous intensity (Candle based power).
1 CDrefers to the object of all radiation, freezing point temperature in platinum, luminous intensity per square centimeter one over sixty area.(before 2.2 cm in diameter, the quality of 75.5 grams of oil, candle, burning 7.78 grams per hour, the flame height is 4.5 cm, the luminous intensity along the horizontal direction)
1L (lumens) refers to the candle light in the distance is 1 cm 1 CD, covers an area of 1 square centimeters of flux on the plane.
1 lux (lux) refers to the luminous flux 1 l evenly distributed on the 1 square meter area of the intensity of illumination.
In fact, intensity calculation often use easier surveying and mapping unit of data or to use. For LED display the active light using CD/m2 as a general unit of luminous intensity, and cooperate with the viewing Angle for the auxiliary parameter, Its equivalent in the screen surface to the illumination unit lux;The numerical multiplication and screen the effective display area, get the whole screen on the best Angle of luminous intensity.
A single LED luminous intensity is an unit with the CD: The luminous intensity of single pipe from several mCD to five thousand mCD. The luminous intensity of LED manufacturers have given refers to the LED at 20 ma shed light up, the best Angle of luminous intensity and center position on the biggest point.Encapsulate leds when the shape of the top of the lens and the LED chip from the top of the lens position determines the Angle and light intensity distribution of LED.In general the same LED Angle, the greater the maximum luminous intensity is smaller, but in the entire three-dimensional hemisphere on the cumulative flux constant.