What effect does the LED display have on high temperature operation?

In today's increasingly widespread use of LED displays, in order to maximize the benefits of display applications, application companies should have the basic knowledge of LED display maintenance. Whether it is an indoor LED display or an outdoor LED display, heat is generated during operation, and the generated heat causes the temperature of the LED display to rise. But what effect does the display have when it is working at high temperatures? Do you know? The following small series will be analyzed and analyzed with everyone.

Under normal circumstances, the indoor LED display has less heat due to low brightness, which can naturally dissipate heat. However, due to the high brightness of the outdoor LED display, the generated heat is large, and it needs to be dissipated by air conditioner or axial fan. Since the LED display is an electronic product, the increase in temperature affects the light decay of the LED display bead, affects the working efficiency of the driving IC, and the service life of the LED display.

LED display open and invalid

The operating temperature of the LED display exceeds the carrying temperature of the chip, which will cause the luminous efficiency of the LED display to decrease rapidly, resulting in obvious light decay and damage; the LED display is mostly encapsulated in transparent epoxy resin, if the junction temperature exceeds the solid phase transition At the temperature (usually 125 ° C), the encapsulating material will change to a rubbery state and the coefficient of thermal expansion will rise sharply, resulting in an open circuit and failure of the LED display.

Excessive temperature will affect the light decay of the LED display

The life of an LED display is characterized by its light decay, that is, the time is long, and the brightness is getting lower and lower until it is finally extinguished. The time at which the LED display's luminous flux decays by 30 is usually defined as its lifetime. High temperature is the main source of LED display light decay and shortening the life of LED display. The light decay of different brands of LED displays is different, usually led display manufacturers will give a set of standard light decay curves. The luminous flux attenuation of the LED display caused by high temperature is unrecoverable. The LED display does not have the luminous flux before the unrecoverable light attenuation, which is called the “initial luminous flux” of the LED display.

Increased temperature will reduce the luminous efficiency of the LED screen

When the temperature rises, the concentration of electrons and holes will increase, the band gap will decrease, and the electron mobility will decrease. When the temperature rises, the probability of electrons and holes radiating in the potential well will decrease, resulting in non-radiative recombination. Heat), thereby reducing the internal quantum efficiency of the LED display; the temperature rise causes the blue peak of the chip to shift to the long-wave direction, so that the emission wavelength of the chip does not match the excitation wavelength of the phosphor, and the external light of the white LED display is also caused. The extraction efficiency is reduced; as the temperature rises, the quantum efficiency of the phosphor decreases, the light emission decreases, and the external light extraction efficiency of the LED display screen decreases; the performance of the silica gel is greatly affected by the ambient temperature. As the temperature rises, the thermal stress inside the silica gel increases, causing the refractive index of the silica gel to decrease, thereby affecting the light effect of the LED display.

Effect of temperature on the wavelength of LED screen

The LED display wavelength is generally divided into a peak wavelength and a dominant wavelength. The peak wavelength is the wavelength with the highest light intensity, and the dominant wavelength can be determined by the X, Y chromaticity coordinates, reflecting the color perceived by the human eye. Obviously, the change of the wavelength of the LED display caused by the junction temperature will directly cause the human eye to feel different colors of the LED display. For a led display device, the forbidden band width of the luminescent material directly determines the wavelength or color of the device. As the temperature rises, the forbidden band width of the material will decrease, resulting in a longer wavelength of the device and a red shift in color.

Excessive temperature limits the maximum injection current of the LED screen

When purchasing LED display, pay attention to choose LED display chip brand, packaging manufacturer, driver IC brand, switching power supply brand, the quality of the brand will affect the quality of the LED display itself, and the brand is high. The product itself generates less heat and can better control the temperature of the LED display, thereby extending the life of the LED display.

LED display has great development prospects due to its advantages of energy saving, environmental protection and long life. LED displays are sensitive to temperature: they can affect LED display life, light efficiency, color, and more. So the right temperature is critical to the LED display.