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The temperature and humidity sensor is used to measure the temperature and humidity in the air through certain detection devices, and then convert them into electrical signals or other required forms of information output according to certain rules to meet user needs.
Because temperature and humidity are closely related to each other both in physical quantities and in real life, temperature and humidity integrated sensors will be generated accordingly. Temperature and humidity sensor refers to the equipment or device that can convert temperature and humidity into electrical signals that can be easily measured and processed. Temperature and humidity sensors on the market generally measure temperature and relative humidity.
characteristic
1. Frequency response characteristics:
The frequency response characteristic of the temperature and humidity sensor determines the frequency range to be measured. The measurement conditions must be kept undistorted within the allowable frequency range. In fact, the response of the sensor always has a definite delay, and the shorter the delay time is, the better. With high frequency response of the sensor, the frequency range of the measurable signal is wide. Due to the influence of structural characteristics, the inertia of the mechanical system is large, and the frequency of the measurable signal of the sensor with low frequency is low. In the dynamic measurement, the response characteristics (steady state, transient, random, etc.) shall be based on the characteristics of the signal to avoid errors.
2. Linear range:
The linear range of the temperature and humidity sensor refers to the range where the output is proportional to the input. Theoretically, the sensitivity remains constant within this range. The wider the linear range of the sensor is, the larger its range is, and certain measurement accuracy can be guaranteed. When selecting the sensor, after the type of sensor is determined, first check whether its range meets the requirements.
3. Determine the type of sensor according to the measurement object and measurement environment:
In order to carry out a specific measurement, it is necessary to first consider what kind of temperature and humidity sensor should be used, which needs to be determined after analyzing various factors. Because, even if the same physical quantity is measured, there are many kinds of sensors for selection. Which one is more suitable, you need to consider the following specific issues according to the characteristics of the measurement and the use conditions of the sensor: the size of the range; Requirements of the measured position on the sensor volume; Whether the measurement mode is contact or non-contact; The method of signal extraction, wired or non-contact measurement; The source of the sensor, domestic or imported, whether the price is affordable, or self-developed.
4. Selection of sensitivity:
Generally, in the linear range of the temperature and humidity sensor, the higher the sensitivity of the sensor is, the better. Because only when the sensitivity is high, the value of the output signal corresponding to the measured change is relatively large, which is conducive to signal processing. However, it should be noted that the sensitivity of the sensor is high, and the external noise irrelevant to the measurement is easy to mix in, which will also be amplified by the amplification system, affecting the measurement accuracy. Therefore, it is required that the sensor itself should have a high signal-to-noise ratio to minimize the plant disturbance signal introduced from the outside.
5. Stability:
The ability of temperature and humidity sensor to keep its performance unchanged after being used for a period of time is called stability. In addition to the structure of the sensor itself, the main factor affecting the long-term stability of the sensor is the use environment of the sensor. Before selecting sensors, the use environment shall be investigated, and appropriate sensors shall be selected according to the specific use environment, or appropriate measures shall be taken to reduce the environmental impact. The stability of the sensor has quantitative indicators. After the service life is exceeded, it should be recalibrated before use to determine whether the performance of the sensor has changed.
type
Temperature and humidity sensors are divided into resistance type and capacitance type. The basic form of products is to coat the substrate with a humidity sensitive material to form a humidity sensitive film. After the water vapor in the air is adsorbed on the humidity sensitive material, the impedance and the medium constant of the element change greatly, thus making the humidity sensor.
Brief introduction of temperature and humidity sen