Pyroelectric infrared sensor is a kind of sensor that uses the heat radiated by the object to detect the target. It is widely used in security, automation control, wireless communication and other fields. The detection sensitivity of pyroelectric infrared sensor is one of the core indexes of its performance, which affects its performance and effect in practical applications. The following will analyze from many aspects what factors affect the detection sensitivity of pyroelectric infrared sensors.

1. Thermal radiation source: The working principle of the pyroelectric infrared sensor is to detect the infrared heat radiated by the surface of the object, so the thermal radiation source plays an important role in the detection sensitivity. The ideal thermal radiation source should have the characteristics of high radiation energy, stable radiation temperature and relatively small radiation amount with the background environment.

2. Detection module: The detection module of the pyroelectric infrared sensor is generally composed of an infrared detector, a response circuit and a signal processing circuit. The performance of the detection module directly affects the sensitivity of the sensor. Among them, the sensitivity, response speed, noise and other parameters of infrared detector determine the sensor's ability to perceive infrared radiation. The design quality and performance of the response circuit and signal processing circuit also have an impact on the sensitivity of the sensor.

3. Optical system: Optical system is the key link that converts infrared radiation into electrical signals. The optical system between the lens and the photodetector is crucial for the detection sensitivity of pyroelectric infrared sensors. The quality of the lens, the focal length and the choice of optical design parameters affect the energy of the light received by the detector, thus changing the sensitivity of the sensor. At the same time, the optical system also needs to have a good anti-interference ability to prevent interference signals such as background light and sunlight from negatively affecting the performance of the sensor.

4. Temperature change: The temperature change of the working environment of the pyroelectric infrared sensor will affect the performance of the sensor. The change of temperature will lead to the change of noise current, dark current and other parameters of the sensor, which will affect the sensitivity of the sensor. In general, the sensitivity of the sensor is higher at lower temperatures and lower at higher temperatures. Therefore, in practical applications, it is necessary to choose the appropriate sensor model according to the specific working environment temperature.

5. Background interference: pyroelectric infrared sensors will be affected by background interference when working. The background interference mainly comes from the temperature change of the surrounding environment, the heat radiation of the surrounding objects and the light. When the background interference exceeds the sensitivity of the sensor, false positives or false positives can be generated. In order to improve the sensitivity of the sensor, it is necessary to take corresponding anti-interference measures, such as calibration, filtering, increasing the signal-to-noise ratio of the detection module.

6. Target characteristics: The characteristics of the target object detected by the pyroelectric infrared sensor will also affect the detection sensitivity of the sensor. The size, shape, material, temperature difference and other factors of the target object will affect the infrared heat radiated by the target object. In general, the greater the temperature difference of the target object, the greater the infrared heat radiated, and the higher the sensitivity of the sensor.

In summary, the detection sensitivity of pyroelectric infrared sensor is affected by many factors. These factors include thermal radiation sources, detection modules, optical systems, temperature changes, background interference, and the characteristics of the target object. In the practical application, according to the specific scene requirements and environmental conditions to choose the appropriate sensor model and take the corresponding anti-interference measures, can improve the detection sensitivity of pyroelectric infrared sensor, improve its performance and effect.