A fluorescent lamp has no filament, so what does it shine on?

With the development of science and technology, tungsten lamps have gradually withdrawn from the market. We all know that light bulbs use electric cathodes to heat tungsten filaments into incandescent light. Many friends are curious. Fluorescent lamps have almost replaced tungsten lamp, and most importantly, they save more electricity. They basically replaced the tungsten light bulbs in life. How does it shine?

What are fluorescent lamps also called? Fluorescent lamp? . The lamp tube is a cylindrical glass tube, which is actually a low-voltage discharge tube. Electrodes are installed at both ends, and the inner wall is coated with fluorescent substances such as magnesium tungstate and zinc silicate. During manufacturing, air is removed and a small amount of mercury and argon is filled. After electrifying, the mercury vapor discharge in the tube produces ultraviolet rays, which excite the fluorescent substance and make it emit visible light. Different luminescent substances produce different colors, similar to sunlight (the fluorescent substance is calcium halophosphate). Fluorescent lamps have soft light, higher luminous efficiency than incandescent lamps, and the temperature is about 40-50? The power consumption is only 1/3- 1/5 of incandescent lamp with the same brightness.

After 1950s, most fluorescent lamps used calcium halophosphate, commonly known as halogen powder. Halogen powder is cheap, but the luminous efficiency is not high enough, the thermal stability is poor, the light attenuation is large, and the luminous flux maintenance rate is low. Therefore, it is not suitable for compact fluorescent lamps with small diameters.

1974, Philips Company in the Netherlands first successfully developed the phosphors yttrium oxide (emitting red light with a peak wavelength of 6 1 1nm), magnesium aluminate (emitting green light with a peak wavelength of 54 1nm) and barium magnesium aluminate (emitting blue light). These three materials are very sensitive to human eyes. The peak wavelength is 450nm) and mixed into tricolor phosphor (full name of rare earth tricolor phosphor) according to a certain proportion. Its luminous efficiency is high (the average luminous efficiency is above 80lm/W, which is about 5 times that of incandescent lamp), the color temperature is 2500K-6500K and the color rendering index is about 85. As a raw material for fluorescent lamps, it can greatly save energy, which is the reason for efficient and energy-saving fluorescent lamps. It can be said that the development and application of rare earth tricolor phosphors is an important milestone in the development history of fluorescent lamps. Without tricolor phosphors, it is impossible to have a new generation of compact, efficient and energy-saving fluorescent lamps with small diameter. However, rare earth tricolor phosphor also has its disadvantages, the biggest disadvantage is its high price.