What is the effect of temperature on the LED display
Led display because of its energy saving, environmental protection, long life and other advantages of great prospects for development. But the temperature on the led display is very important, the impact of the temperature on the led display: led to the led display life and light efficiency, color and so on. So the appropriate temperature on the led display is essential.
The impact of the temperature on the led display has the following five points:
First, the temperature will lead to excessive sales led completely destroyed
(1) led display operating temperature exceeds the chip carrying temperature will make led display luminous efficiency quickly reduced, resulting in significant light failure, and cause damage;
(2) led display more transparent epoxy resin package, if the junction temperature exceeds the solid phase transition temperature (usually 125 ℃), the packaging material will change to the rubber and thermal expansion coefficient soared, resulting in led display open and failure The
Second, the temperature rise will shorten the life of the led display
Led display life for its light failure, that is, a long time, the brightness is getting lower and lower until the last extinguished. Usually defined led display luminous flux attenuation of 30 for its life.
Often cause led display light failure reasons are the following:
(1) led display chip material defects in the higher temperature will be rapid proliferation, reproduction, until the invasion of light, the formation of a large number of non-radiating composite center, seriously reduce the luminous efficiency of led display. In addition, the high temperature conditions, the material within the micro-defects and from the interface and the rapid expansion of the electrical plate will also be introduced into the light emitting area, the formation of a large number of deep level, the same will speed up the led display device light failure.
(2) high temperature transparent epoxy resin will be degeneration, yellow, affecting its light transmission performance, the higher the working temperature of this process will be faster, which is led display light failure is another major reason.
(3) phosphor light failure is also affecting the led display light failure of a major reason, because the phosphor at high temperature attenuation is very serious.
Therefore, the high temperature is caused by led display light failure, shorten the main source of led display life.
Different brands led display light failure is different, usually led display manufacturers will give a set of standard light decay curve. High temperature led led display luminous flux attenuation is irreversible, led display does not occur irreversible light attenuation before the luminous flux, called the led display "initial luminous flux".
Third, the temperature rise will reduce the luminous efficiency of led display
Temperature impact led display light efficiency reasons include the following aspects:
(1) the temperature increases, the concentration of electrons and holes will increase, the forbidden band width will be reduced, the electron mobility will be reduced.
(2) the temperature increases, the potential wells in the electrons and holes of the radiation recombination probability reduced, resulting in non-radiative composite (heat), thereby reducing the led display within the quantum efficiency.
(3) The temperature rise causes the blue light wave of the chip to shift to the long wave direction, so that the emission wavelength of the chip and the excitation wavelength of the phosphor do not match, which can cause the white light to reduce the external light extraction efficiency.
(4) With the temperature rise, the phosphor quantum efficiency is reduced, the light is reduced, led display external light extraction efficiency is reduced.
(5) silica gel performance by the ambient temperature greater impact. As the temperature increases, the thermal stress inside the silica gel increases, resulting in reduced refractive index of the silicone, which affects the luminous efficiency of the led display.
Fourth, the temperature on the led display light emitting wavelength (light color) effect
Led display light wavelength can be divided into peak wavelength and main wavelength. The peak wavelength is the wavelength of the maximum intensity, and the main wavelength can be determined by the X, Y chromaticity coordinates, reflecting the perceived color of the human eye. Obviously, the junction temperature caused by the led display light wavelength changes will directly cause the human eye on the led display light color different feelings. For a led display device, the band gap width of the material directly determines the wavelength or color of the device. As the temperature increases, the band gap of the material will decrease, resulting in a longer wavelength of the device and a redshift in color.
Fifth, the temperature is too high will limit the maximum injection current led display
The above is the temperature on the impact of the introduction of the introduction of the display, through the above description that the temperature rise on the impact of the led display is very large. So the right, the appropriate temperature is the focus of the led display.