With the increasing prevalence of LED displays, users should have a basic understanding of their maintenance to maximize their advantages. Both indoor and outdoor LED displays generate heat during operation, leading to temperature increases. But do you know the effects of high-temperature operation on outdoor LED displays?
1. Open Circuit Failure in LED Displays
When the operating temperature of an LED display exceeds the chip's load temperature, it rapidly reduces the luminous efficiency of the LED screen, causing significant light decay and damage. LED displays are primarily made of transparent epoxy resin. If the junction temperature exceeds the solid-phase transition temperature (typically 125°C), the packaging material will transform into a rubbery state, and the coefficient of thermal expansion will increase sharply, leading to open circuit failures in the LED display. Excessive temperature affects the light decay of outdoor LED displays, thus shortening their lifespan.
2. Accelerated Light Decay
The lifespan of an outdoor LED display is reflected in its light decay, meaning its brightness decreases over time until it goes out. High temperature is a major factor causing light decay in LED displays and shortens their lifespan. Light decay varies between different brands of LED electronic screens; typically, Shenzhen LED display manufacturers provide a standard light decay curve. The light flux decay of outdoor LED displays caused by high temperature is irreversible. The light flux before irreversible light decay is called the "initial light flux" of the LED electronic screen.
3. Reduced Luminous Efficiency
Increased temperature reduces the luminous efficiency of outdoor LED electronic displays, mainly in the following ways:
a. Changes in Electron and Hole Concentration
Increased temperature increases the concentration of electrons and holes, reduces the band gap, and decreases electron mobility, affecting the luminous efficiency of the LED.
b. Reduced Radiative Recombination
Increased temperature reduces the likelihood of radiative recombination of holes in the potential well, leading to non-radiative recombination (heating), thus reducing the internal quantum efficiency of the LED electronic screen.
c. Changes in Emission Wavelength
Increased temperature causes the blue peak of the chip to shift towards longer wavelengths, creating a mismatch between the chip's emission wavelength and the excitation wavelength of the phosphor mixture, which also reduces the external light extraction efficiency of white LEDs. d. Reduced Quantum Efficiency of Phosphors
As temperature rises, the quantum efficiency of phosphors decreases, leading to reduced luminous output and a decrease in the external light extraction efficiency of the LED electronic display.
e. Impact on Silicone Performance
The performance of silicone is more significantly affected by ambient temperature. As temperature increases, internal thermal stress in the silicone increases, causing a decrease in its refractive index, thus affecting the luminous efficiency of the LED electronic display.
In summary, sustained high temperatures have multifaceted effects on outdoor LED displays. They can not only cause open-circuit faults but also accelerate light decay, reduce luminous efficiency, and ultimately affect the normal operation and lifespan of the display. Therefore, users should pay attention to the heat dissipation of outdoor LED displays and take effective heat dissipation measures, such as installing air conditioners or axial fans, to ensure stable operation of the display at a suitable temperature and to fully realize its display effect.
