The demand for ultraviolet products has exploded, how to make consumers a correct science?

Due to the spread of the new coronavirus around the world, UV products with sterilization and disinfection effects have been sought after by the people, and the demand has increased greatly. Manufacturers in the venue have increased their production, and players outside the venue are going to participate in the game. However, behind this UV carnival, there are some problems that cannot be ignored: ordinary consumers have a deep understanding of UV products and confuse mercury lamps with UV LEDs; at the same time, due to insufficient knowledge, if consumers use improperly, they may give Some harm to the body; some bad manufacturers use UVA, UVB or even ordinary white light to impersonate UVC, bully consumers and so on.


If these problems are not resolved, on the one hand, consumers will lose their trust in UV products, on the other hand, it will also disrupt the normal order of industry competition, leading to the emergence of bad money to expel good money. At present, the popularization and promotion of ultraviolet products is still a heavy responsibility. How to correctly understand UV products and UV LEDs to provide consumers with a popular science? The following will lead you to learn in depth from the "White Paper on the Development of UV LED Industry".



Scientific definition and wavelength division of UV

 

Ultraviolet (UV) refers to ultraviolet rays, which refers to the general term of radiation in the electromagnetic spectrum with wavelengths from 100nm to 400nm. Ultraviolet literally means "beyond purple". Because purple light has the shortest wavelength in visible light, ultraviolet light has a shorter wavelength than purple light and is invisible to the naked eye.

 

According to the difference of UV energy, it is divided into three common band types:


UVA: Also known as long-wave ultraviolet, the wavelength is 320-400nm, the ability to penetrate the atmosphere is the strongest, the least destructive, and the accumulation of time will cause damage to the organism.


UVB: Also known as medium-wave ultraviolet, the wavelength is 280-320nm, and it will be absorbed by the ozone layer in large quantities, which will have a profound impact on the growth and health of organisms.


UVC: also known as short-wave ultraviolet, with a wavelength of 200-280nm, the ability to penetrate the atmosphere is the worst, the most destructive to organisms, short-term exposure can burn the skin, long-term or high-intensity exposure can cause skin cancer.


According to photon theory, the shorter the wavelength, the stronger the energy and the more destructive it is to living things. Short-wave ultraviolet light even has super destructive power, can cut the chemical links of most compounds, and can also damage the RNA and DNA of cells, causing them to die immediately or lose their ability to reproduce.

 

The spectrum emitted by the sun to the earth originally contained the UV band, but due to the absorption of the earth's atmosphere, especially the ozone layer, blocking 97-99% of ultraviolet radiation, most of the UV cannot enter the earth's biosphere, and everything can live and multiply.


Note: 200nm to 100nm is the UVD band, which can only propagate in a vacuum and is not in the scope of industrial research.



Mercury lamp and UV LED


UV is a double-edged sword, and its physical properties make it destructive to living things, and it can also produce many practical uses, thereby making artificially obtaining UV commercially valuable. At present, the way humans obtain UV through industrial technology is mainly through mercury lamps and UV LEDs.



Mercury lamp: The energy difference between the excited electronic state and the ground state of mercury atoms falls within the ultraviolet range. The cathode ray tube emits high-energy electrons to make the mercury vapor atoms in an excited state, and the excited electrons return to the ground state to emit ultraviolet light.


UV LED: The light source of the UV band is manufactured using the principle of semiconductor light emission. The width of the forbidden band of the three or five group of semiconductor materials such as aluminum nitride, gallium nitride or indium gallium nitrogen falls between the blue and ultraviolet bands. The holes on the top are recombined, and the energy obtained during the recombination is released. By changing the material ratio, ultraviolet and visible light in different wavelength bands can be released.



Comparison of advantages of UVC LED and mercury lamp


At present, there are two main types of ultraviolet light sources used for sterilization: traditional mercury lamps and UVC LEDs; mercury lamps are the mainstream in the high-power market; UVC LEDs are currently only suitable for household appliances, domestic water treatment and surface sterilization lamps in the low-power market.


The corresponding disinfection area of ​​mercury lamps is generally 1W corresponding to 1㎡; according to the wavelength, it is mainly divided into: ozone type 185nm and ozone-free type 254nm; the former has no dead angle disinfection, which is more suitable for factories, workshops, hospitals and other places; the latter only works on the irradiation surface , It is more suitable for home and restaurant lighting.


In the long run, UVC LEDs do not contain mercury pollution, small size and other advantages, making it the only alternative to ultraviolet mercury lamps, and high expectations are placed.



It should be pointed out that compared with mercury lamps, UV LEDs need to continue to break through in terms of technology, efficiency, and cost. For example, when the radiation efficiency reaches more than 10% to 20%, and the cost is comparable to ultraviolet mercury lamps, it is more Opportunities in the household, commercial and even industrial fields, truly start large-scale applications.



Application fields of UV LED


In recent years, due to the wide application of UV LEDs, it can bring a new experience to people's lives and make it have huge market development potential, which is highly anticipated by the industry and the public. Each UV wavelength type has a specific application. Currently, the most widely used are UVA products, and the thresholds for UVB and UVC are higher, especially UVC.


UVA (320 ~ 400nm): UVA is generally harmless and can be used to treat certain skin diseases. UVA LEDs are mostly used in ultraviolet curing, anti-counterfeiting detection, photocatalysis, skin tanning, etc.


UVB (280 ~ 320nm): Most of the UVB in sunlight is absorbed by the atmospheric ozone layer. Long-term exposure may be harmful to human eyes and skin, but it is beneficial to the production of vitamin D and the treatment of serious skin diseases. UVB LED is mostly used in plants Growth and medical phototherapy.


UVC (200 ~ 280nm): Because it is extremely destructive, it has the ability to sterilize and disinfect. At present, UVC LEDs are mostly used for surface sterilization, air purification and water treatment.


It should be noted that each person's resistance to ultraviolet rays is different, and the cumulative amount of exposure to a certain limit will cause damage. UVA, UVB, and UVC can cause damage to the surface tissue of the eye. Therefore, when using UV products, it is necessary to avoid direct exposure of UV light to the human body. When designing products, the UV LED industry should also be very careful about safe design and safe use guidance.


Well, today's "White Paper on UV LED Industry Development" is here. After reading the article, I hope all readers will forward it more and more. While popularizing and propagating for customers and consumers, it will also purify the competitive environment of the industry and jointly promote the healthy development of the industry!