Like white light application manufacturers' selection of light effects, wavelengths, and light colors, the selection of deep ultraviolet UVC-LEDs also depends on application scenarios. When designing the scheme, it is the key to identify the most concerned parameters of the application scenario. Similarly, the packaging factory should also consider these when selecting chip parameters.
Accroding to the current market of UVC LED, the available deep ultraviolet UVC-LED optical power files range from 2 mW, 10 mW to 100 mW. While choosing the optical power that should be used, the sterilization effect and sterilization time are given priority. It is known that a 3 mW UVC-LED with an output angle of 60° can kill 99.99% of Escherichia coli on the surface within 10 seconds at a distance of 2 cm. Therefore, for humidifiers, ice machines, water dispensers, water tank antibacterial, smart toilets and other similar static sterilization scenarios, the mainstream usage is to use a 2~4 mW light power level UVC-LED; air purifiers, air conditioners and other flowing air sterilization The scene usually uses 2~3 10 mW UVC-LEDs; the total light power of dynamic water sterilization scenes such as direct drinking fountains should reach at least 50~100 mW. The cost of the solution can be roughly calculated based on the total mW.
When choosing the peak wavelength of UVC-LED, you need to understand the following technical points: 1. The most suitable wavelength for sterilization is 265 nm, not the characteristic wavelength of low-pressure UV mercury lamps at 254 nm. As shown in Figure 1 (right), UVC ultraviolet rays with a wavelength between 240 and 290 nm have a good sterilization effect; 2. For UVC-LED, the sterilization effect depends on both the peak wavelength and the optical power. For example, the bactericidal effect of 270 nm is 30% better than that of 280 nm; 30% higher light power is also 30% better. (So it can be converted, the bactericidal effect of 2.6 mW 280 nm UVC-LED and 2mW 270 nm UVC-LED is the same) However, considering that the average peak wavelength of each manufacturer has little difference, in fact, optical power is the most important measure of sterilization efficiency index.
Just like the arms race of major manufacturers in the early white LED market, the lamp bead life of deep ultraviolet LEDs is also regarded as an important standard for their product quality. With the lessons learned from white LEDs, I hope to tell readers that the best fit is the best.
Identifying the actual needs of the application scenarios for the life span is conducive to reducing the cost of the solution and bringing more market opportunities. Or take the mainstream UVC-LED products on the market as an example. The claimed life span is 15,000 hours at the highest and 2000 hours at the lowest. But how long does the application require? If we carefully analyze product requirements, we will find:
Humidifier: 0.8 hours/day*30 days/month*8 months/year*3 years=576 hours;
Direct drinking fountain: 20 minutes/day*30 days/month*12 months/year*5 years=600 hours;
Water tank for water dispenser: 1 hour/day*30 days/month*12 months/year*3 years=1080 hours;
Air conditioner: 2 hours/day*30 days/month*6 months/year*5 years=1800 hours (evaporator and filter sterilization program);
Air purifier: 5 hours/day*30 days/month*12 months/year*3 years=5400 hours.
Do you think 10,000 hours of UVC-LED is better than 5,000 hours?
Carefully calculate the life requirements of the application scenarios for the lamp beads, find the most matching lamp beads and price, and believe that the value of UVC-LED can be maximized from the perspective of suppliers and customers.
The material characteristics of the deep ultraviolet LED cause the horizontal light output ratio of the chip to be higher than the vertical light output. Therefore, the light output angle of the lamp bead packaged with a flat lens is usually between 120 and 140° (most manufacturers use this light output angle). If a ball lens is used for packaging, the light output angle is adjustable between 60 and 140°
In fact, no matter how large a UVC-LED is selected, you can design enough lamp beads to completely cover the sterilization space you need. In particular, in scenes that are not sensitive to the sterilization range, a small light exit angle can make the light more concentrated, so that the sterilization time is shorter.