LED street lamp refers to that the light intensity of LED will be lower than the original light intensity after it is lit for a period of time, and the lower part is the light decay of LED street lamp. Generally, LED packaging manufacturers conduct tests under laboratory conditions (at room temperature of 25℃), and continuously light LED1000 hours with 20MA of direct current to compare the light intensity before and after lighting.
I.The reasons causing:
The light decay of LED street lamp products is the signal attenuation of light in transmission. At present, the degree of light decay of LED products made by leading manufacturers all over the world is different. High-power LED products also have light decay, which is directly related to temperature, mainly determined by chip, fluorescent powder and packaging technology. At present, the light decay of white LED in the market may be one of the first problems to enter into civil lighting.
The light decay of LED is mainly caused by the following two factors:
LED product quality problem
1. The LED chip adopted has poor constitution and fast brightness decay.
2. There are defects in the production process. LED chip heat dissipation cannot be properly derived from PIN PIN, leading to excessive LED chip temperature and aggravated chip attenuation.
Condition of use problem
1. LED is constant current drive, and some LED USES voltage drive to attenuate LED.
2. The driving current is greater than the rated driving condition.
In fact, there are many reasons leading to LED product light decay, the most critical is the heat problem. Although many manufacturers do not pay special attention to the heat dissipation of secondary products, the degree of light decay of these secondary LED products will be higher than that of LED products that pay attention to heat dissipation. The thermal resistance of the LED chip itself, the influence of the silver glue, the heat dissipation effect of the substrate, as well as the colloid and gold wire are all related to the light decay.
3.How to extend the life of LED, the key to extend its life is to reduce its junction temperature. The key to reduce junction temperature is to have a good radiator. It can send out the heat generated by LED in time.