How old is the world's longest-lived incandescent bulb this year?
It is 115 years old this year. Still working at Livermore Fire Station in the United States. In order to observe the 100-year-old bulb, a real-time monitor was specially placed around it. It is said that the bulb has "destroyed" two video monitors.
The 100-year bulb has been working for 115 years since 1901. Apart from power outages, the bulb went out only once in 1976 and once in 2013. When firefighters moved the bulbs in 1976, instead of screwing them down with a screwdriver, they cut the sling and moved them to another place to continue their work under the escort of police and fire trucks.
People take good care of this 100-year-old light bulb. It is understood that the Livermore bulb is a hand-blown incandescent lamp with built-in carbon filament. Researchers compared the imitations of centuries-old bulbs with ordinary bulbs and found that the differences between Livermore bulbs and ordinary bulbs are mainly in two aspects:
First, the filament used is eight times thicker than the ordinary filament.
2. The filament used in a century-old light bulb may be a semiconductor made of carbon filament.
The higher the conductor temperature of the ordinary bulb, the lower the conductivity; but the higher the conductor temperature of the century-old bulb, the stronger the conductivity.
However, scientists have not yet figured out the exact reason for the longevity of Livermore bulbs. Although the exact date of the bulb's start is not clear, firefighters have designated June 18 as its "birthday" each year.
Livemore, translated into Chinese, means "live longer." So this light bulb has been on for more than 100 years at the Fire Station in Longer Living Areas in California, USA. If calculated in 115 years, this light really lights up more than 1 million hours!
It has to be said that this is only a magical example, because of various reasons, our usual use experience is: just bought back the lamp, the use is very bright. When the lamp is used for a long time, the brightness of the lamp slowly decreases until it is finally extinguished.
We all know that the life of lamps is slowly shortening, and when one day they are completely off, they will die. Many people are unavoidable to wonder why there is such a process in lamps and lanterns, and what causes it? In fact, in the final analysis, this is the problem of light decay of lamps. Simply speaking, the function mechanism of lamps and lanterns is declining with the increase of service life, just like human body. Either incandescent lamp, fluorescent lamp or LED lamp can not avoid the problem of light decay.
The light decay of lamps means that after a period of lighting, the light intensity of lamps will be lower than the original light intensity, and the lower part is the light decay of lamps. Different types of lamps have different causes of light decay.
For ordinary incandescent lamps, the larger the bulb shell, the smaller the light decay, that is, the evaporation deposition of tungsten to block the light output. The light decay of the inflatable bulb is relatively small because part of the gas prevents the evaporation of tungsten filament.
If an incandescent lamp uses the same filament and is made in different size bulb shells, the light decay of the large bulb shell at the same time point is smaller than that of the small bulb shell. In addition, the same is the inflatable bulb, the large glass shell bulb has a large internal space, gas convection to the glass shell has a relatively large heat dissipation area, relative to the small glass shell lamp temperature is much lower, the filament temperature is relatively low, the luminous efficiency is low, the evaporation rate of tungsten filament is also low, so the light decay is small.
The incandescent lamp will cause light decay because of the size of the lamp and the evaporation of tungsten filament. The reasons for light decay of fluorescent lamp are relatively complex, which are generally caused by the following reasons:
_Phosphor deterioration, in the process of fluorescent lamp operation, ultraviolet light will make the phosphor produce color center, resulting in new absorption bands in the lamp, so that the brightness of the phosphor appears attenuation.
The formation of absorption film, fluorescent lamp after a long time of discharge work, will form a layer of black absorption film on the surface of phosphor, the existence of this layer of absorption film will cause the reduction of light output.
When the fluorescent lamp works, there will be a large number of mercury ions or mercury atoms on the surface of the glass tube. Mercury ions will exchange with other ions in the glass tube. Over the years, the glass tube will be blackened, which will lead to the light decay of the fluorescent lamp and affect the luminous efficiency.
Although LED lamps are better than incandescent lamps and fluorescent lamps, they can not completely overcome the problem of light decay. There are two main factors for the light fading of LED:
Quality Problems of LED Products
The quality of the LED chip used is not good, and the brightness decay is fast.
Production process has defects, and the heat dissipation of LED chips can not be well derived from PIN foot, which leads to the high temperature of LED chips and intensifies the chip attenuation.
Conditions of Use
LED is driven by constant current. Some LED lamps are driven by voltage, which makes the LED decay too fast.
_Driving current is greater than rated driving condition.
In fact, there are many reasons leading to the light decay of LED products, but the most critical problem is heat dissipation. The better the heat dissipation performance, the lower the working temperature of the LED and the smaller the light decay, the longer the lifetime of the LED.
Lighting decay is a necessary process of lamp work. When we select lamps, we should try to select lamps with better quality and heat dissipation performance. In the process of using, we should also try to reduce the workload of lamps in order to delay the light decay rate.
