Working principle of ultraviolet sensors
Ultraviolet (UV) sensors convert UV signals into electrical signals using photosensitive elements. Their operating modes are generally classified into two types: photovoltaic (PV) mode and photoconductive mode. Photovoltaic mode does not require a series battery; current flows through the series resistor, and the sensor acts as a small battery, outputting voltage. However, this mode is more difficult to manufacture and has a higher cost. Photoconductive mode requires a series battery; the sensor acts as a resistor, and its resistance changes with the intensity of light. This mode is easier to manufacture and has a lower cost.
The Development History of Ultraviolet Sensors
The earliest ultraviolet sensors were based on pure silicon, but according to research by the National Institute of Standards and Technology (NIST), pure silicon diodes also respond to visible light, forming unwanted electrical signals, resulting in low accuracy.
More than a decade ago, a Japanese company produced GaN-based crystals, becoming a pioneer in GaN technology and opening up the GaN market. This led to the development of GaN ultraviolet sensors, whose accuracy far exceeds that of single-crystal silicon, making them the most commonly used ultraviolet sensor material.
Later, group II-VI ZnS materials were also developed and applied to the field of ultraviolet sensors. From a research and development perspective and performance testing, its accuracy is nearly 10^5 times higher than that of GaN-based sensors. To a certain extent, ZnS-based ultraviolet sensors will be on par with GaN-based ones.
The function of ultraviolet sensors
1. Its role in the medical field
Scientists have discovered that ultraviolet light with a wavelength of around 310nm has a strong melanin-producing effect on the skin, accelerating skin metabolism and enhancing skin regeneration. This makes it effective in treating photosensitive skin diseases such as vitiligo, pityriasis rosea, polymorphic light eruption, chronic actinic dermatitis, and actinic prurigo. Therefore, ultraviolet phototherapy is increasingly used in the medical field. When using it, the intensity of the ultraviolet light must be carefully controlled, which requires the use of ultraviolet sensors for monitoring.
2. Its role in the field of flame detection
Ultraviolet (UV) flame detectors are the common name for ultraviolet (UV) flame detectors. UV flame detectors detect fires by detecting the ultraviolet light produced by burning materials. Besides UV flame detectors, there are also infrared (IR) flame detectors on the market, also known as linear beam smoke detectors. UV flame detectors are suitable for locations where open flames are likely to occur during a fire. They can be used in locations with strong flame radiation or where there is no smoldering stage. The UV sensor used for flame detection needs to be heat-resistant and highly sensitive.
3. Its role in the field of arc detection
High-voltage equipment can experience arc discharges due to insulation defects. These discharges are accompanied by significant light radiation, including abundant ultraviolet (UV) light. By detecting the UV radiation generated by arc discharges, the safe operating status of high-voltage power equipment can be assessed. UV imaging is an effective method for arc discharge detection, offering a clear and intuitive view and good detection and localization capabilities. However, the UV signal is relatively weak, posing some challenges in its detection.
4. Banknote recognition
Ultraviolet (UV) light recognition technology primarily utilizes UV sensors to detect fluorescent anti-counterfeiting features and the matte finish of banknotes. This technology can identify most counterfeit banknotes (such as those that have been washed, bleached, or pasted). It is used not only in ATM deposit verification but also in banknote counting machines, banknote detectors, and other financial equipment. Generally, it uses fluorescence and ultraviolet light to perform comprehensive reflection and transmission detection of banknotes. The authenticity is determined by the different absorption and reflectivity of ultraviolet light between banknotes and other types of paper.
Jianda Renke UV transmitters convert ultraviolet light into measurable electrical signals using photosensitive elements, enabling online UV monitoring. The circuitry employs imported American industrial-grade microprocessor chips and high-precision UV sensors, ensuring excellent reliability and accuracy. The product features a wall-mounted, high-protection housing with an IP65 rating, providing protection against rain and snow. This product can be widely used in environmental monitoring, meteorological monitoring, agriculture, forestry, and other environments to measure ultraviolet light in the atmosphere and under artificial light sources.
Features:
1. Employs ultraviolet measurement devices with high sensitivity to 240-370 nm to accurately measure ultraviolet intensity.
2. The viewing window uses high-quality light-transmitting material with an ultraviolet transmittance of over 98%, avoiding the problem of low ultraviolet measurement values caused by the absorption of ultraviolet rays by traditional PMMA and PC materials.
Multiple analog output signals are available, including 3.4-20mA, 0-10V, and 0-5V.
4. Wall-mounted waterproof casing with a high level of protection, suitable for long-term outdoor use in rain and snow environments.
5.10-30V DC wide voltage power supply.
With the development of new mechatronics technologies, the performance of ultraviolet sensors will be further improved, their detection results will be more accurate, their detection distance will be longer, and their dynamic detection performance will be better. Therefore, the application prospects of ultraviolet sensors will be broader.
