自动门传感器主要应用微波传感器和红外线传感器，传感器的主要负责外部信息

Automatic door sensors mainly use microwave sensors and infrared sensors, and the sensor is mainly responsible for the transmission of external information to the main controller with a pulse signal. <br>The working principle of the microwave sensor is the Doppler principle. We know that any wave has the characteristic of reflection. When a wave of a certain frequency hits a blocking object, a part of the wave will be reflected back. If the blocking object is stationary, the wavelength of the reflected wave is constant. The object moves toward the wave source, and the wavelength of the reflected wave is shorter than the wavelength of the wave source. If the blocking object moves away from the wave source, the wavelength of the reflected wave is longer than the wavelength of the wave source. The change in wavelength means the frequency. The change. Microwave induction knows that a moving object is approaching or far away from the change of the reflected wave. The characteristics of this type of sensor are fast response speed; higher sensitivity; wide sensing area, high safety and stability, and not affected by temperature, air flow, dust and smoke. The <br>infrared sensor is based on infrared technology. When someone enters the sensing range, a dedicated sensor Detect the change of the infrared spectrum of the human body, the load is automatically connected, and the person does not leave the sensing range, it will continue to be connected; after the person leaves, the load will be automatically turned off after a delay. Its characteristics do not have any radiation, the device consumes less energy, and has good concealment. However, the disadvantages of being vulnerable to various light sources, heat sources, and radiation interference outweigh its advantages in the design of automatic doors. <br>So this design adopts microwave sensor, and its main features are in line with the design of this paper.

Automatic door sensor mainly uses microwave sensor and infrared sensor, the sensor is mainly responsible for external information incoming to the main controller a pulse signal.<br>Microwave sensors work on the Doppler principle. We know that any wave has the characteristics of reflection, when a certain frequency of waves hit the blocker, there will be a part of the wave is reflected back, if the blocker is stationary, the wavelength of the reflected wave is constant, if the blocker is moving towards the wave source, the wavelength of the reflected wave is shorter than the wavelength of the wave source, if the blocker is moving away from the wave source direction, the wavelength of the reflected wave is longer than the wavelength of the wave source, which means that the wavelength changes. Microwave sensing is known to be approached or far away from moving objects through changes in reflected waves. The characteristics of these sensors react quickly; Higher sensitivity; The sensing area is wide, the safety stability is high, not affected by temperature, airflow, dust and smoke<br>Infrared sensor is based on infrared technology, when someone enters the sensing range, the special sensor detects changes in the human infrared spectrum, automatically switch on the load, the person does not leave the sensing range, will continue to be connected; When a person leaves, the delay automatically shuts down the load. Its characteristics do not have any radiation, the device energy consumption is less, good concealment. However, susceptible to a variety of light sources, heat sources, radiation interference and other disadvantages greater than its advantages in the automatic door design this aspect.<br>Therefore, this design uses microwave sensor, its main characteristics are in line with the design of this paper.

The automatic door sensor mainly uses microwave sensor and infrared sensor. The sensor is mainly responsible for transmitting external information to the main controller as a pulse signal.<br>The working principle of microwave sensor is Doppler principle. We know that any wave has the characteristics of reflection. When a wave of a certain frequency touches a barrier, a part of the wave will be reflected back. If the barrier is stationary, the wavelength of the reflected wave is constant. If the barrier is moving towards the wave source, the wavelength of the reflected wave will be shorter than that of the wave source. If the barrier is moving away from the wave source, the wavelength of the reflected wave will be shorter The wavelength of the radiation wave is longer than that of the wave source. The change of wavelength means the change of frequency. It is through the change of reflected wave that microwave induction knows that there are moving objects approaching or far away. This kind of sensor features fast response, higher sensitivity, wide sensing area, high safety and stability, and is not affected by temperature, air flow, dust and smoke<br>The infrared sensor is based on the infrared technology. When someone enters the sensing range, the special sensor detects the change of the infrared spectrum of the human body and automatically turns on the load. If the person does not leave the sensing range, it will continue to turn on; after the person leaves, it will automatically turn off the load with delay. It is characterized by no radiation, low energy consumption and good concealment. However, it is easy to be affected by various light sources, heat sources, radiation interference and other disadvantages, which is greater than its advantages in the design of automatic doors.<br>Therefore, this design uses microwave sensor, its main characteristics are in line with the design of this paper.<br>