LED display working temperature required high temperature _ to display what damage

by:Xinyao LCD     2020-04-07
LED display are very picky about the environment temperature. At room temperature is 25 degrees Celsius in theory, its working state is the most ideal. But in fact, outdoor displays in the complexity of the application of environmental temperature, the highest temperature in summer may be in more than 60 degrees Celsius, the lowest temperature in winter may be in - Below 20 degrees Celsius. LED, IC work efficiency and performance, brightness is inconsistent, the screen display also natural become spent as a whole. Under the condition of different temperatures, red, green, blue three kinds of the brightness of the light attenuation and drop is different, at 25 degrees Celsius, the white balance is normal, but in 60 degrees Celsius when had fallen to the brightness of the three colors, and its attenuation values are not consistent, so will produce the whole screen brightness decline and the phenomenon of partial color, the quality of the whole screen will drop. A, high temperature will lead to the LED display screen thoroughness destruction 1) LED display working temperature than the chip bearing temperature will reduce the luminous efficiency quickly LED display, produces obvious droop, and cause damage; ( 2) LED display in a transparent epoxy resin encapsulation, more if the junction temperature more than solid phase transition temperature ( Usually for 125 ℃) , encapsulation materials will surge to rubber shape and thermal expansion coefficient, resulting in LED display open and failure. Second, the temperature will shorten the life of the LED display LED display life characterized by its light failure, which is longer, the brightness is less and less, until finally go out. Usually define LED display light flux attenuation of 30 time for its life. Usually the cause of LED display light failure has the following several aspects: ( 1) LED display chip material defects in high temperature rapid proliferation, reproduction, and invasion light-emitting area, forming a lot of the radiative recombination centers, severely reduce the luminous efficiency of LED display. In addition, under the condition of high temperature, micro defects within the material and the fast expansion of impurity from the interface and panels will also introduce the light emitting area, to form the deep level, will also accelerate the droop of LED display device. ( 2) Transparent epoxy resin is modified, when high temperature yellow, affect the pervious to light performance, working temperature, the higher the faster the process will be carried out, this is the LED display is a major cause of droop. ( 3) Droop of phosphor is also a major factor affecting the LED display light failure, because of phosphor at high temperature attenuation is very severe. So, the high temperature is LED display light failure, shorten the service life of LED display primary sources. Different brands of LED display light failure is different, usually LED display manufacturer will give you a set of standard droop curve. High temperature caused by the LED display light flux attenuation is unrecoverable, LED display not happened before the unrecoverable light attenuation of luminous flux, referred to as the 'initial luminous flux of LED display. Three, temperature can reduce temperature affect the LED luminous efficiency of LED display screen causes include the following aspects: (light efficiency 1) Temperature, the concentration of electrons and holes will increase, the forbidden band width will decrease, electron mobility will decrease. ( 2) Temperature increases, the potential well of radiative recombination of electrons and holes, less likely to cause the radiative recombination ( Produce heat) To reduce the internal quantum efficiency of LED display. ( 3) Temperature lead to blue chip peaks shift towards long wave, make the emission wavelength of chips and excitation wavelength of phosphor do not match, can cause the white light LED display external light extraction efficiency lower. ( 4) As temperatures rise, phosphor quantum efficiency is reduced, the light, LED display external light extraction efficiency. ( 5) Silica gel performance are greatly influenced by environmental temperature. As the temperature increases, the silicone internal thermal stress increase, results in the decrease of the refractive index of a silica gel, which affects LED display lights. Four, temperature on the LED display light wavelength ( Light color) The influence of the wavelength of light emitting peak wavelength can generally be divided into LED display and the main wavelength. Peak wavelength of the light intensity of the largest wavelength and the dominant wavelength can be determined by the X, Y chromaticity coordinates, reflects the perception by the human eye color. Obviously, the junction temperature caused by the LED display light wavelength change will directly cause the human to LED display light color different feelings. For a LED display device, light emitting area materials forbidden band width values directly determines the wavelength of light emitting device or color. Temperature of the forbidden band width of materials will decrease, lead to light wavelengths longer, the color red shift. Five, the temperature too high can limit the maximum current injection of LED display above is the introduction of the influence of temperature on the LED display screen, through the introduction of the above that the influence of temperature on the LED display is very large. So the suitable, appropriate temperature is the key of LED display. 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