LightEmittingDiode from the LED is the acronym for the words, the Chinese translation of "light-emitting diodes", as its name implies is a light-emitting diodes can be converted into electrical energy of the electronic device has a light emitting diode characteristics. At present different light-emitting diodes can be issued from the blue to different infrared wavelengths of light, purple and even the current issue of ultra-violet light emitting diodes have been born. In addition to blue LED's phosphor coating, Blu-ray will be converted into white light white LED.

LED colors and Technology:

LED manufacturers of different materials can be produced with different photon energy, so as to control LED issued by the wavelength of light, that is, or the color spectrum. The first LED material is used by arsenic (As) and gallium (Ga), the PN junction forward voltage drop (VF, can be interpreted as a light or voltage) to 1.424V, issued for the infrared light spectrum . Another commonly used material for the LED of phosphorus (P) and gallium (Ga), the PN junction forward voltage drop to 2.261V, issued as a green light.


Based on these two materials, early use of LED industry GaAs1-xPx Zhu wood structure, in theory, can be produced from the infrared light until the green light to any wavelength within the framework of the LED, subscript X on behalf of the phosphorus element to replace the percentage of arsenic elements. PN through the General knot can drop LED wavelength of color. GaAs0.6P0.4 have a typical red LED, GaAs0.35P0.65 the orange light LED, GaAs0.14P0.86 the yellow LED, and so on. As the making of the adoption of gallium, arsenic, phosphorus three elements, so-called LED these three elements LED. The GaN (GaN) blue LED, GaP the green LED and GaAs infrared LED, known as the second element LED. At present up-to-date technology is mixed with aluminum (Al), calcium (Ca), indium (In) and nitrogen (N) of the four elements of the AlGaInN the four elements of the material elements of the four LED, can cover all visible light, as well as some of the purple Outside the scope of the light spectrum.

Luminous intensity:

Luminous intensity of the illumination unit to measure units (lux Lux), luminous flux units (lumens Lumen), luminous intensity unit (candlelight Candlepower)

1CD (candlelight) refers to the total radiation of objects in the platinum freezing point temperature, the sixtieth per square cm area of luminous intensity. (Refer to the past with a diameter of 2.2 cm and weight of 75.5 grams of whale You Zhu, burning 7.78 grams per hour, the flame height of 4.5 cm, along the horizontal direction of luminous intensity)

1L (lumens) refers to the candlelight 1CD exposure in the range of 1 cm, with an area of 1 square centimeters of the surface of the luminous flux.

1Lux (lux) means 1L of flux evenly distributed in the area of 1 square meters of illumination.

Active general-use light-emitting luminous intensity unit candlelight CD, such as incandescent, LED and so on;-reflection or through the use of object flat lumens luminous flux L, such as LCD projector, and so on; and illumination units lux Lux, for general photography, etc.领域. To measure the value of the three units is the equivalent, but from different points of view to understand. For example: If an LCD projector brightness (luminous flux) for the 1600 lumens, the projector screen to the total reflection of the size of 60 inches (1 m), the illumination for its 1600 lux, I assume that the light from a light source Cm, I light up an area of 1 square cm, while the population of light intensity for Luminescence 1600CD. The real LCD projector light as a result of the dissemination of wear and tear, or light reflection of the wear and tear film and the uneven distribution of light, the light will be greatly reduced, generally 50% on the efficiency of a well.

Actual use, light is often calculated using data from the Survey and Mapping easier to change or to use.

The LED light-emitting display such initiatives generally used CD / m as a unit luminous intensity and angle of observation with a supplement to the parameters of its equivalent in the surface of the screen illumination units lux; this value with an effective screen-display area Multiply that by the whole body of the screen in the best perspective on the luminous intensity, assuming that each pixel screen body of luminous intensity in the corresponding space constant, this value could also be considered as a whole body of the luminous screen. General outdoor LED displays have to meet the 4000CD / m above the brightness of sunlight in order to have a good display. General indoor LED, the largest in the brightness of 700 ~ 2000CD / square meters.

LED luminous intensity of a single CD to the unit, at the same time with perspective parameters, LED luminous intensity and color does not matter. The one-tube luminous intensity from a few mCD ranging from five to mCD. LED manufacturers are given the intensity of light-emitting LED refers to the 20mA current to light up the best angle and the center of luminous intensity on the biggest points. LED package at the top of the lens and the shape of the LED chip away at the top of the lens determines the location of the LED light intensity and angle distribution. Generally speaking, the same LED bigger perspective, the most luminous intensity of the smaller, but throughout the hemisphere, three-dimensional surface of a total flux of change.

When the number of LED emission rules more closely, the luminous sphere overlay each other, resulting in the entire light-emitting plane luminous intensity is more evenly distributed. In the calculation of the intensity of light-emitting display, to be based on LED and LED perspective of emissions density, manufacturers will provide the greatest point value multiplied by the intensity of light-emitting 30% to 90%, as the average one-tube luminous intensity.

General LED light for a long life, generally marked with the manufacturer for more than 100,000 hours, should also pay attention to the actual brightness of the LED cycle of decay, such as the taillights of the car for most of the UR red light tube to a few dozen hours later, the brightness Only half of the original. LED brightness decay cycle and the production of materials technology has a great deal, general economic conditions in the permit should be selected brightness over the slow decay of the four elements of LED.

Color, white balance:

White is red and green and blue light according to the proportion of a mixture, when the green light in the brightness of 69%, and the red light for 21% of blue light for 10%, blending people could only see the eyes of pure white . However, red and green and blue LED's chromaticity coordinates of the process due to other reasons can not achieve the full effect of chromatography, and the primary color control, including the deviation of the primary colors and white light brightness to be known as the color.

As for the full-color LED display for color, brightness and the best in order to achieve the lowest cost, to select the three primary colors into a more or less luminous intensity ratio of 3:6:1 for the LED devices composed of pixels.

White Balance requirements of the three primary colors in the same gray value of the transfer is still under for the synthesis of pure white.

Primary color, color:

Color refers to the synthesis of a variety of colors to the basic colors. In light of the primary colors red, green, blue, the next picture shows spectrum table, the table of the top three primary colors for the ideal wavelength. If there are deviations primary colors, synthetic colors of the region can be reduced, the spectral form of the triangle will be reduced from the visual point of view, the color deviation will not only enrich the degree of reduction.

LED issued by the red, green and blue light of different wavelengths, in accordance with its identity and can be divided into purple, pure red, orange-red, orange, orange, yellow, green, pure green, green, blue and green, Chunlan, such as blue-violet, orange-red , Green, blue and purple than pure red, pure green, Chunlan much cheaper price. The three primary colors of green in the most important because green and white accounted for 69% of the brightness and color in a horizontal row at the center of the list. Therefore, the color balance of price and purity of the relationship between the two, Green is considering focusing on the target.


Reference link: http://www.17led.com/LEDdisplay/2008-03/43.html