The lamp that I just bought is very bright when used. After a long time of use, the brightness of the lamp slowly becomes low until it is finally extinguished.
We all know that this is the life of the luminaire is slowly shortening, and when it is not lit up one day, it will be dead. Many people can't help but wonder why the lamps have such a process. What is the cause?
In fact, in the end, this is the problem of the light decay of the luminaire. Simply put, the luminaire is the same as the human body. As the service life increases, the functional mechanism of the luminaire is constantly decreasing. Whether it is incandescent, fluorescent, or LED lights, the problem of light decay cannot be avoided.
The light decay of a luminaire means that after a period of illumination, the light intensity of the luminaire will be lower than the original light intensity, and the lower part is the light decay of the luminaire. Different types of lamps cause different causes of light decay.
Ordinary incandescent lighting
For ordinary incandescent lamps, the larger the bubble shell, the smaller the light decay, that is, proportional to the evaporation output of tungsten blocking the light output. The gas bulb will be relatively light due to the partial gas blocking the evaporation of the tungsten filament.
If the same filament is used for incandescent lamps, it is made in different sizes of bulbs. Relatively speaking, the light decay at the same time point is indeed smaller than that of the small bulb.
In addition, the same bubble is filled, the bulb of the large glass bulb has a large internal space, and the gas convection to the bulb has a relatively large heat dissipation area. The temperature of the relatively small bulb lamp is much lower, the temperature of the filament is relatively low, and the luminous efficiency is low. The evaporation rate of the silk is also low, so the light decay is small.
Fluorescent light decay
Incandescent lamps cause light decay due to the size of the bulb and the amount of evaporation of the tungsten filament. The cause of the light decay of the fluorescent lamp is relatively complicated, which is generally caused by the following reasons:
â—† The phosphor is degraded. During the operation of the fluorescent lamp, the ultraviolet light causes the phosphor to generate a color center, which causes a new absorption band to be generated in the lamp, thereby attenuating the brightness of the phosphor.
â—† The formation of the light absorbing film, after a long period of discharge work, a black light absorbing film will be formed on the surface of the phosphor. The presence of this light absorbing film will reduce the light output.
â—† When the lamp is blackened, when the fluorescent lamp is working, there will be a large amount of mercury ions or mercury atoms on the surface of the glass tube. The mercury ions will exchange ions with other ions in the glass tube. After many years, the glass tube will be blackened, resulting in Fluorescent lamps have a light decay that affects luminous efficiency.
LED lighting
Although LED lamps are improved over incandescent lamps and fluorescent lamps, they cannot completely overcome the problem of light decay. There are two main factors for the light decay of LEDs:
LED product quality problems
â—† The quality of the LED chip used is not good, and the brightness is attenuated faster.
â—† There are defects in the production process. The heat dissipation of the LED chip cannot be well derived from the PIN pin, resulting in the LED chip temperature being too high and the chip attenuation is intensified.
Conditional problem
â—† The LED is driven by constant current. Some LED lamps use voltage driving to make the LED decay too fast.
â—† The drive current is greater than the rated drive condition.
In fact, there are many reasons for the light decay of LED products, but the most critical issue is the heat dissipation problem. The better the heat dissipation performance, the lower the operating temperature of the LED, the smaller the light decay, and the longer the LED life.
Light decay is a necessary process for luminaire work. When selecting lamps, we should try to select lamps with better quality and heat dissipation performance. In the process of use, we should also reduce the working load of the lamps to delay the light decay speed and extend the lamps. life.
Xinxiang Mina Import & Export Co., Ltd. , https://www.mina-motor.cn