The harm of high temperature led display, led display is very critical to the ambient temperature. In theory, it works best at room temperature around 25 degrees celsius. In practice, however, that ambient temperature of the outdoor display is quite complex in application, with the highest temperature in sum likely to be above 60 c and the lowest temperature in winter likely to be below - 20 C.. Too high a temperature can lead to the complete destruction of led display, led display life performance for its light failure, that is, over time, the brightness is lower and lower, until finally extinguished. The time at which the led display screen luminous flux decays 30 is generally defined as its lifetime. There are usually the following reasons for the light failure of led displays:
Defects existing in the chip materials of Hefei led display screen will multiply and multiply rapidly at high temperature, until they invade the luminous area, forming a large number of non-radiation composite centers, which severely reduces the luminous efficiency of led display screen. In addition, at high temperature, micro-defects in materials and fast-expanding impurities from interfaces and plates will also be introduced into the luminescent region, forming a large number of deep energy levels, which will also accelerate the light attenuation of led display devices.
Transparent epoxy resin will denature and yellow at high temperature, which will affect its light transmission performance. the higher the working temperature, the faster this process will be, which is another main reason of led display screen light failure. The light attenuation of fluorescent powder in led display screen is also one of the main reasons that affect the light attenuation of led display screen, because the attenuation of fluorescent powder at high temperature is very serious.
The increase of temperature will reduce the luminous efficiency of led display screen. the reasons why temperature affects the luminous efficiency of led display screen include the following aspects: the concentration of electrons and holes will increase, the forbidden band width will decrease and the electron mobility will decrease with the increase of temperature. With the increase of temperature, the radiation recombination probability of electrons and holes in the potential well decreases, resulting in non-radiation recombination ( heat generation ), thus reducing the internal quantum efficiency of led display screen. The increase of temperature leads to the shift of blue light peak of the chip to the long wave direction, which makes the emission wavelength of the chip mismatch with the excitation wavelength of fluorescent powder, and also leads to the decrease of light extraction efficiency outside the white led display screen.
As the temperature rises, the quantum efficiency of fluorescent powder decreases, the light emission decreases, and the extraction efficiency of external light of led display screen decreases. The performance of silica gel is greatly influenced by ambient temperature. With the increase of temperature, the thermal stress inside the silica gel increases, which leads to the decrease of the refractive index of the silica gel, thus affecting the light efficiency of the led display screen.