Temperature sensor, is a measure of environmental humidity dashboard, in industrial production and manufacturing, climate, environmental protection, national defense security, scientific research, aerospace engineering and other units, often must carry out the measurement and control of the relative humidity of air. And the temperature sensor often has such a key application, the key is due to the following points:
1. Precision and long-term reliability: The precision of temperature sensor should be ±2%~±5%RH, not up to this standard can not be used as a measurement verification application, temperature sensor to achieve ±2%~±3%RH precision is more difficult, the characteristics of general commodity materials are determined at room temperature (20°C +10°C) and clean steam body.
In actually application, because of the harm of dust, grease and harmful material, the application over time can cause embrittlement, precision is reduced, the precision of the temperature sensor fusion level to its long-term reliability to distinguish, generally speaking, the long-term reliability and life is harmful temperature sensor quality problem, drift quantity control in 1% RH standard of goods is very little, Generally ±2% or so, and higher.
2. Temperature sensor temperature index: humidity sensitive components in addition to the relative humidity of the air is sensitive, the temperature is also very sensitive, the temperature index is generally within the range of 0.2~0.8%RH/°C, and some humidity sensitive components in different air humidity, the temperature index and a gap. Temperature drift discrete system, which must be added to the power supply circuit temperature compensation.
Chooses microcontroller design mobile phone software compensation, or temperature compensation of the temperature sensor is to ensure that the whole WenFanChou precision, the linearization of the temperature sensor temperature drift curve immediately harm compensation effect, the temperature drift of discrete systems are usually damages not to good effect, can only choose to hardware temperature follow sex compensation would get real, and the compensation for the actual effect. The temperature category of the temperature sensor is the key main parameter. Most moisture sensitive components cannot do everything at around 40°C in normal operation.
3. The temperature sensor power supply system: hydroxide porcelain, polymer materials and lithium chloride wet sensitive raw materials release AC voltage, will cause the characteristic change, so that invalid, so this temperature sensor can not use ac voltage there must be a direct current component of the AC current. It must be an AC current power supply system.
4. Tolerance matching: at this stage, the temperature sensor is common phenomenon in the poor tolerance matching conditions, the same specifications of the controller can not exchange, and cause serious damage to the actual application effect, promoted difficult to repair, adjust, some manufacturers in this line made all kinds of hard, (but tolerance matching is still very poor) obtained the good actual effect.
5. Environmental humidity efficiency: the efficiency of environmental humidity is much more difficult than the efficiency of temperature. Temperature calibration usually uses a standard temperature meter as the standard, and the calibration specification of environmental humidity is difficult to maintain, dry hygrometer and some commonly used pointer hygrometer can not be used for calibration, precision can not ensure, with its provisions of natural environment standards are very strict requirements, General conditions (the most expensive in the environment humidity natural environment appropriate standard) in the lack of sound metrological verification equipment, generally with simple saturated salt solution metrological verification method, and determine its temperature.