Principles and characteristics of temperature and humidity sensor

Temperature and humidity sensor is a sensor which, after the temperature and humidity in the air by a certain detecting means, the measured temperature and humidity, according to certain rules into an electric signal output, or other desired forms of information, to meet the needs of users .
As the temperature and humidity both from the physical quantity itself or in real people's lives are closely related, so the temperature and humidity sensors will be integrated consequential. Temperature and humidity sensor means or device capable of converting means and the amount of temperature measured amount of moisture to be easily processed electrical signal. Temperature and humidity sensors are generally on the market to measure the temperature and relative humidity amounts.
Modern isothermal temperature sensor in principle and structure vary, depending on how the measurement object, the measurement object and the measurement environment reasonable selection of temperature and humidity sensor, is measured during a certain amount of the first problem to be solved. When the temperature and humidity sensor is determined, with the support of the measuring method and apparatus it will be determined. Measurements success depends largely on the temperature and humidity sensor selection is reasonable.

1, the frequency response characteristic:
the frequency response characteristics of temperature and humidity sensor determines the frequency range to be measured, must be kept within the allowable frequency range undistorted measurement conditions, in fact, the overall response of the sensor are - given delay, the shorter the delay time is desired the better. High frequency response of the sensor can be measured on the wide range of signal frequencies, and the characteristics of the structure due to the impact, the mechanical system inertia larger, due to a lower frequency lower frequency sensor detectable signal. In dynamic measurement, should be in accordance with the characteristics of the response characteristic (the steady state, transient, random, etc.) signals, so as to avoid producing an error.
2, the range of linear:
linear range of temperature and humidity sensor means is proportional to the input range of the output. In theory, within this range, the sensitivity remains constant. Wider linear range of the sensor, the greater the range, and can ensure a certain degree of accuracy. In the choice of sensor type after a sensor to determine when the first look meets the requirements of its range.
3, determine the type of sensor and the measurement object in accordance with the measurement environment:
Can only be determined after a specific survey work, we must first consider the temperature and humidity sensor which uses the principle, which requires analysis of many factors - to be carried out. Because, even in the same physical measurement, there are various principles of the sensor are available, the principle of the sensor which is more appropriate to consider include specific questions to be measured according to the conditions and characteristics of the sensor: size range; the measured position requires the sensor volume; measurement of contact or non-contact type; extraction method of a signal, wired or non-contact measurement; origin sensor, domestic or import, the price can withstand, or developed.
4, sensitivity selection:
In general, the linear range of temperature and humidity sensors, the desired sensitivity of the sensor as high as possible. Because only the high sensitivity, the value of the output signal is measured corresponding to the change is rather large, it is conducive to signal processing. It is to be noted that the high sensitivity of the sensor to be measured independent of the ambient noise is easily mixed, will be enlarge the system, affecting the measurement accuracy. Therefore, the requirements of the sensor itself should have a high signal to noise ratio, reducing factory staff to make scrambled signal introduced from the outside world.
6, stability:
temperature and humidity sensor after a period of use, the ability to maintain its performance does not change is called stability. Factors affecting long-term stability of the sensor in addition to the structure of the sensor itself, mainly sensor's environment. Before selecting a sensor, they should use the environment to investigate, and select the appropriate sensor according to the specific use of the environment, or to take appropriate measures to reduce the environmental impact. There are quantitative indicators of the stability of the sensor, after use beyond should be re-calibrated before use, to determine whether the performance of the sensor changes.