What is the impact of high-temperature operation of LED electronic screen?

What is the impact of high-temperature operation of LED electronic screen?

Date: October 16, 2019 Source: Tuosheng Optoelectronics

What is the impact of high-temperature operation of LED electronic screen? In today's increasingly widespread use of LED electronic screens, in order to make the use of display screens more efficient, application companies should have the basic knowledge of LED electronic screen maintenance. Whether it is an indoor LED electronic screen or an outdoor LED electronic screen, heat is generated during the operation, and the generated heat will cause the temperature of the LED electronic screen to rise. But what is the effect of the display in the high temperature working state, you know? The following extension of the photoelectric and everyone to analyze and analyze.

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

First, the LED electronic screen open circuit and failure: LED electronic screen operating temperature exceeds the chip's carrying temperature will make the LED electronic screen's luminous efficiency quickly reduce, resulting in significant light decay, and damage; LED electronic screen mostly with transparent epoxy In the package, if the junction temperature exceeds the solid phase transition temperature (usually 125 ° C), the packaging 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 electronic screen. Excessive temperature will affect the light decay of the LED electronic screen

The life of an LED electronic screen is manifested by its light decay, that is, the time is long, and the brightness is getting lower and lower until it is extinguished. The time at which the LED electronic screen's luminous flux is attenuated 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 electronic screen. The light decay of different brands of LED electronic screens is different. Usually, LED electronic screen manufacturers will give a set of standard light decay curves. The LED electronic screen luminous flux attenuation caused by high temperature is unrecoverable, and the LED electronic screen has no unrecoverable luminous flux before the light attenuation, which is called the "initial luminous flux" of the LED electronic screen.

Second, the increase in temperature will reduce the luminous efficiency of the LED electronic screen: as the temperature increases, the concentration of electrons and holes will increase, the band gap will decrease, the electron mobility will decrease; the temperature will rise, and the electrons in the potential well will The radiation recombination probability of holes is reduced, resulting in non-radiative recombination (heat generation), thereby reducing the internal quantum efficiency of the LED electronic screen; the temperature rise causes the blue light peak of the chip to shift toward the long wavelength, so that the emission wavelength of the chip and the phosphor The excitation wavelength mismatch will also cause the external light extraction efficiency of the white LED electronic screen to decrease. As the temperature rises, the quantum efficiency of the phosphor decreases, the light emission decreases, and the external light extraction efficiency of the LED electronic screen decreases. The performance of the silica gel is affected by the ambient temperature. Big. 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 electronic screen.