1854, Henry Gaubert, a German watchmaker who immigrated to the United States, made the first practical electric lamp with carbonized bamboo wire in a vacuum glass bottle, which lasted for 400 hours, but he did not apply for a patent in time.
1860, joseph swan, an Englishman, also made a carbon filament lamp, but he failed to obtain a good vacuum environment to make the carbon filament work for a long time.
In 874, two electrical technicians in Canada applied for a patent for electric light: nitrogen was filled under a glass bulb and carbon rods were electrified to emit light, but they did not have enough financial resources to continue to improve the invention, so they sold the patent to Edison at 1875.
Edison tried to improve the filament after purchasing the patent, and finally made a carbonized bamboo filament lamp that could last for 1200 hours in 1880.
At the beginning of the 20th century, carbonized filament was replaced by tungsten filament, and tungsten filament incandescent lamp is still in use today.
1938, the fluorescent lamp was born. 1998 white LED lamp was born.
Extended data:
The main types of electric lights:
1, incandescent lamp
Ordinary incandescent light bulbs, commonly used incandescent light bulbs, are what most of us think of as light bulbs. It has the advantages of low price, good color rendering (Ra= 100), continuous dimming and simple structure. Therefore, tungsten filament bulbs also have different styles to match different lamps.
2, halogen tungsten lamp
Inflatable incandescent lamp, the filling gas contains some halogen elements or halides. It has all the characteristics of ordinary lighting incandescent lamp, the light efficiency and service life are more than twice as long as those of ordinary lighting incandescent lamp, and the volume is small.
3. Fluorescent lamp
Features: high light efficiency, long life and good light color. Fluorescent lamps are straight tube type, ring type and compact type. It is a widely used energy-saving lighting source. Using straight fluorescent lamp instead of incandescent lamp can save electricity by 70~90% and prolong life by 5~ 10 times.
4. Halogen bulbs
Halogen lamp, also called halogen tungsten bulb, is a kind of incandescent lamp. The principle is to inject halogen gas such as iodine or bromine into the bulb. At high temperature, the evaporated tungsten wire reacts chemically with halogen, and the evaporated tungsten will solidify again on the tungsten wire to form a balanced cycle to avoid premature fracture of the tungsten wire.
5, LED lights
The core of LED is a wafer composed of P-type semiconductor and N-type semiconductor. There is a transition layer between P-type semiconductor and N-type semiconductor, which is called pn junction. In the PN junction of some semiconductor materials, when the injected minority carriers recombine with the majority carriers, the excess energy will be released in the form of light, thus directly converting electric energy into light energy.
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