Long time working of LED will cause aging, especially for high-power LED, the problem of light decay is more serious. When measuring the life of LED, it is not enough to take the damage of light as the end point of LED display life. It is more meaningful to define the life of led by the light attenuation percentage of LED, such as 5% or 10%.

Light decay: when charging the surface of the photosensitive drum, with the accumulation of charge on the surface of the photosensitive drum, the potential also increases, and finally reaches the “saturation” potential, which is the highest potential. The surface potential will decrease with the passage of time. Generally, the working potential is lower than this potential. The process that the potential naturally decreases with time is called “dark decay” process. When the photosensitive drum is scanned and exposed, the potential of the dark area (the surface of the photoconductor that is not illuminated by light) is still in the process of dark decay; In the bright region (the surface of the photoconductor irradiated by light), the carrier density in the photoconductive layer increases rapidly, the conductivity increases rapidly, and the photoconductive voltage is formed, the charge disappears rapidly, and the surface potential of the photoconductor also decreases rapidly. It’s called “light decline” and slows down in the end.