The wavelength of ultraviolet light is between visible and X-ray. The wavelength range is 10 ~ 400nm. However, many photovoltaic manufacturers believe that the wavelength of 430nm also belong to ultraviolet. Although many ultraviolet light is not seen by the human eye, it is still part of the violet visible spectrum known, UV LED in the past few years has made considerable progress. This is not only the result of technological advances in the production of solid-state UV devices, but also thanks to the increased demand for environmentally friendly UV lamps.
Application of UV LED and its protection
The current UV LED supply in the optoelectronic market includes a wavelength range of 265 to 420 nm in a variety of package formats such as perforation, surface mount and COB. UV LED generators have a variety of unique applications, however, each generator in the wavelength and output power are independent. Normally, UV light on the LED can be divided into three areas. They are defined as UV-A (UVA), UV-B (UVB) and U V-C (shortwave UV), respectively (see Figure 2).
UV A-type devices have been produced since 1990. These LEDs are typically used in such as forged detection or verification (currency, driver's license, etc.). The power output requirements of these applications are very low, the actual use of the wavelength range is between 390 ~ 420nm, lower wavelength products are not suitable for application. Because these LEDs are long lifecycle in the market and are easy to manufacture, they can be used as a variety of light sources and the cheapest UV products.
UVA LED components in the past few years has been a lot of growth. Most of this wavelength range (about 350 ~ 390nm) is used in commercial and industrial materials such as adhesives, coatings and inks for UV curing. Due to increased efficiency, reduced cost and miniaturization of the system, LED lamps have a greater advantage than traditional curing technologies such as mercury or fluorescent lamps. Therefore, the supply chain in the continuous use of LED technology, making the trend of using LED to become more and more obvious. Although the product cost of this wavelength range is significantly higher than the UV A zone, the rapid advancement in manufacturing technology and the steady increase in production are gradually lowering the price.
Lower UV A and higher UV B wavelength ranges (about 300-350 nm) are the most commercially available areas. These devices with great potential can be suitable for a variety of applications, including UV curing, biomedicine, DNA analysis and various types of sensing. There is a significant overlap in the three UV spectral ranges. Therefore, in the choice, not only to consider what is the most suitable application, but also need to consider what is the most cost-effective solution. Because the lower wavelength usually means higher LED cost.
UV B and UV C wavelength range (about 250 ~ 300nm) is a field that is still largely in the initial stage. However, the enthusiasm and demand for the application of such products in air and water purification systems are very strong. At present, only a handful of companies have the ability to produce UV LEDs in this wavelength range, while fewer companies can produce products with sufficient life, reliability and performance characteristics. Therefore, the cost of UVC / B devices is still high, difficult to use in some applications. However, the first commercial UVC LED disinfection system was launched in 2012, which will help promote the market forward.
Do the protection
A common question about UV LEDs is: do they bring security risks? As mentioned above, UV light has multiple levels. One of the most commonly used UV light sources is a black bulb. The product has been in use for decades and is used to produce luminous or fluorescent effects for posters, as well as in painting and currency verification. The light generated by these bulbs is usually in the UV A spectrum, closest to the visible wavelength and has a lower energy. Although high exposure has been shown to be associated with skin cancer and other potential problems such as accelerated skin aging, this part of the UVA spectrum is the safest of the three UV light. Light-emitting diodes (relative to standard incandescent or fluorescent bulbs) are also highly directional and have a very narrow viewing angle. Look at UV LEDs to damage your eyes. Therefore, it is preferable for the user to avoid exposure to the UVA product.
UV C and most UV B light are mainly used for sterilization and disinfection. These wavelengths of light are not only harmful to microorganisms, and if exposed to it, it is equally dangerous for humans and other forms of life. These LED lights should always be shielded, never look directly with the naked eye, even if it glow little. Exposure to light in these wavelengths may cause skin cancer and temporary or permanent vision loss or impairment.
All UV devices should have warning labels. In addition, before purchasing UV C or UV B UV lamps, many manufacturers require each customer to sign a document stating that they understand and agree to the use and handling of these products.