Infrared thermopile is commonly used in non-contact temperature measurement scenarios, such as forehead thermometer, ear thermometer, thermal fault diagnosis of industrial equipment, etc. When the infrared radiation of the infrared thermopile irradiates the center of the thermopile, the temperature difference generated between the hot junction and the cold junction forms the output voltage. However, its output voltage depends not only on the infrared radiation of the target object, but also on the significant influence of ambient temperature drift. In order to achieve accurate temperature measurement, the NTC chip is integrated into the infrared thermopile to control the overall operating temperature error by monitoring the ambient temperature in real time.
In infrared thermopile, the NTC chip is usually integrated with the infrared thermopile chip on the same substrate, and the upper surface is electrically connected with the thermopile chip and the conductive contact of the substrate using the bonding process. This installation method ensures that the NTC chip can quickly and accurately sense the ambient temperature changes around the infrared thermopile, providing a basis for subsequent temperature monitoring. Specifically:
1. Temperature monitoring of infrared thermopile
The reason why NTC chip can accurately monitor the junction temperature of infrared thermopile is due to the resistance temperature characteristics (R-T characteristic) of semiconductor ceramic materials. When the ambient temperature changes, the NTC resistance value changes exponentially, which can be converted into a temperature reading through a voltage divider circuit. According to this reading, the infrared thermopile can use the algorithm to make corresponding adjustment measures to ensure its normal operation. For example, the ear thermometer uses an infrared thermopile to monitor the ambient temperature in real time through the NTC chip, and feeds the data back to the ear thermometer control system. The control system sends adjustment instructions based on the changes in ambient temperature to ensure that the ear thermometer can accurately measure human body temperature at different ambient temperatures.
2. Temperature compensation of infrared thermopile
When the ambient temperature fluctuates, the infrared thermopile output signal is prone to drift, resulting in errors in the measurement results. In order to solve this technical problem, the infrared thermopile will use NTC chip to measure the internal ambient temperature, and adjust the output signal of the infrared thermopile according to the compensation algorithm combined with the ambient temperature data, so as to eliminate the influence of ambient temperature changes on the measurement results, so as to improve the measurement accuracy. For example, the infrared thermopile in the forehead thermometer has a built-in NTC chip that monitors the ambient temperature in real time, which can provide a benchmark for subsequent body temperature measurements. When the ambient temperature changes, the NTC chip can quickly sense and transmit the signal to the forehead thermometer control system, which corrects the measurement results based on the ambient temperature, thereby improving the accuracy of temperature measurement.
NTC chip plays a core role in temperature sensing and error correction in infrared thermopile. In order to ensure stability and reduce the deviation rate during its temperature measurement process, EXSENSE Electronics recommends using DT series excellent-reliability silver termination NTC chip. The die-type structure of the NTC has a faster response speed than other types and is more sensitive during temperature measurement in infrared thermopile. The operating temperature of the silver termination NTC chip is -40℃~200℃, which can adapt to various harsh application scenarios of infrared thermopile and maintain its great electrical performance. DT series excellent-reliability silver termination NTC chip also has high accuracy characteristic, which provides a strong guarantee for the temperature data acquisition of infrared thermopile.
