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WLED

WLED white light-emitting Diode means white LED


LED basic knowledge
LED is the abbreviation of Light Emitting Diode, which is translated as “light emitting Diode” in Chinese. It is an electronic device that can convert electrical energy into light energy and has the characteristics of a Diode. Different light-emitting Diodes can emit light of different wavelengths from infrared to blue. There are also white light LEDs that are coated with phosphor powder on blue LEDs to convert blue light into white light.

WLED

LED color and technology
The color and process of the LED: different materials are used to make the LED, which can generate photons with different energies, thereby controlling the wavelength of the light emitted by the LED, which is the spectrum or color. The material used in the first LED in history is arsenic (As) gallium (Ga), and the emitted light is infrared spectrum. Another commonly used LED material is phosphorous (P) gallium (Ga), which emits green light.
Because the three elements of gallium, arsenic, and phosphorus are used in manufacturing, these LEDs are commonly called three-element light-emitting tubes. The GaN (gallium nitride) blue LED, GaP green LED and GaAs infrared LED are called two-element light-emitting tubes. The latest technology is a four-element LED made of AlGaInN, a four-element material that mixes four elements of aluminum (Al), calcium (Ca), indium (In), and nitrogen (N), which can cover all visible light and part of ultraviolet light. The spectral range.

LED luminous intensity
The measurement units of luminous intensity include illuminance unit (Lux), luminous flux unit (Lumen), and luminous intensity unit (Candle power)
1CD (Candlelight) refers to the luminous intensity of a completely radiant object at the freezing point temperature of platinum, per sixtieth of the square centimeter area.

1L (Lumen) refers to the luminous flux of 1 CD candle illuminating a plane with a distance of 1 cm and an area of ​​1 square cm.

1Lux (lux) refers to the illuminance where 1L of luminous flux is evenly distributed on an area of ​​1 square meter.
Generally, active luminous bodies use luminous intensity unit candle CD, such as incandescent lamps, LEDs, etc.; reflective or transmissive objects use luminous flux unit lumens L, such as LCD projectors, etc.; and illuminance unit Lux, generally used in photography and other fields .

The three measurement units are equivalent in value, but need to be understood from different angles. For example: if the brightness (luminous flux) of an LCD projector is 1600 lumens, and the size of the projection onto the total reflection screen is 60 inches (1 square meter), its illuminance is 1600 lux, assuming that its light exit is 1 Cm, the area of ​​the light exit is 1 square centimeter, the luminous intensity of the light exit is 1600CD. However, the brightness of a real LCD projector will be greatly reduced due to the loss of light propagation, the loss of reflection or light-transmitting film, and the uneven light distribution. Generally, an efficiency of 50% is good.

In actual use, light intensity calculations often use data units that are easier to map or change directions. For the active luminous body of the LED display screen, CD/square meter is generally used as the luminous intensity unit, and the observation angle is the auxiliary parameter, which is equivalent to the lux unit of the illuminance on the surface of the screen; this value is compared with the effective display area of ​​the screen. Multiply to obtain the luminous intensity of the entire screen at the best viewing angle. Assuming that the luminous intensity of each pixel in the screen is constant in the corresponding space, this value can be regarded as the luminous flux of the entire screen.

Generally, the outdoor LED display must reach a brightness of 4000CD/square meter or more to have an ideal display effect in sunlight. Ordinary indoor LED, the maximum brightness is about 700-2000 CD/m2.