The high temperature of led display is causing pressure to l Published：2018-09-03
Under the high temperature of summer, the car on the road will be spontaneously in combustion accident, not to mention the LED display under such a high temperature ,which effects will the high temperature cause to the LED display? Now, we will analyze the reasons and remind you that you should pay attention to the dissipation of led display.
The effects of high temperature on the LED video display are the following:
1, the high temperature will cause the LED display’s utter destruction
(1) If the LED display’s working temperature exceeds the temperature of the chip carrier , it will make the luminous efficiency of the LED display rapidly decreased, resulting in significant light failure and damage;
(2) Most of the LED display is packaged by transparent epoxy resin, if the temperature of junction exceeds the solid phase transition temperature (usually 125 ℃), the encapsulating material will transit to rubbery and coefficient of thermal expansion will increase, resulting in the failure of open circuit and LED display .
2, the high temperature will shorten the life of the LED display boards
LED display’s performance is reflected in the life of its light failure, which means the brightness is getting lower with the time passing by and finally extinguished. LED display is usually defined flux decay time 30 of its life.
The reasons that cause light failure of led display:
(1) the defects in the memory chip material of LED display at higher temperatures will rapidly multiply, even to the invade the luminous area, forming a large number of non-radiative recombination centers, severely reducing the luminous efficiency of the LED display. In addition, under the condition of high temperature, and micro-defects from the interface with the plate and the fast expansion of impurities within the material will be introduced into the light-emitting area, forming a large number of deep level, it will also accelerate the light’s failure of LED display .
(2) under high temperature, the transparent epoxy resin will denature and turn yellow, affect its performance, the higher the temperature is, the faster this process will be, which is a major cause of light failure of LED display.
(3) Effect of phosphor light decay is a main cause of bad light LED display, because phosphor decay is very serious at a high temperature.
Therefore, the high temperature is the main root cause of bad light LED display, LED display shorten life.
light of led display of various brands fades differently , usually LED display manufacturers will give a standard set of light failure curve. The light failure caused by high temperature is unrecoverable. The luminous flux which exists before the light decay called "initial luminous flux."
3, the increase of temperature will reduce the luminous efficiency of LED display
The reasons why temperature affect the light efficiency of LED display
(1) If the temperature increase , the concentration of electrons and holes will increase, energy gap will decrease, and the electron mobility will decrease.
(2) With the increase of temperature, the potential well of radiative recombination of electrons and holes reduce, causing non-radiative recombination (generate heat), thereby reducing the internal quantum efficiency of the LED display.
(3) increasing temperature make blue light wave of the chip shift to a longer wavelength, so that the wavelength of the chip and the emission does not match that of the phosphor excitation, which can also decrease the external extraction efficiency of white led.
(4) As the temperature rises, the quantum efficiency of the phosphor reduce, the light reduce as well as the external light extraction efficiency of the LED display reduce .
(5) silica gel performance is influenced by ambient temperature. As the temperature increases, thermal stress inside the silica also increase, resulting in the decrease of the refractive index of silica gel, thus affecting the efficiency of the LED display light.
4, the effect of temperature on the emission wavelength of the LED display (light colors)
The emission wavelength LED display can be divided into general peak wavelength and main wavelength. Peak wavelength is maximum intensity of the wavelength, dominant wavelength is determined by X, Y chromaticity coordinate, which reflects the human eye perception of color. Obviously, the changes of emission wavelength of the LED display caused by the junction temperature will cause the different feelings of human eye on the LED display light color directly .For an LED display device, energy gap directly determines the light of a wavelength or color. With temperature increases, the energy gap of the material will reduce, leading to longer wavelength of light-emitting device, the color turning into red.
5, high temperature will limit the maximum injection of LED display
The above points are the introduction of the effects of temperature on the LED display. From what is said above, we know that the temperature rise affects LED display a lot. So suitable and appropriate temperature is the focus of the protection of LED display.
To deal with the heat at high temperature LED display
LED display, especially those installed outdoors, the installation of fans, air conditioning, insulation boards around the LED display is necessary, and we should also pay attention to the waterproofing of fans, air conditioning, insulation boards. If it is indoors, making LED display work in condition of ventilation and cooling.