News > How do automatic door infrared sensors detect motion or presence?

How do automatic door infrared sensors detect motion or presence?

Edor | 2023/09/25

Automatic doors have become a ubiquitous feature of modern buildings, offering convenience, accessibility, and energy efficiency. Among the various technologies used to enable these doors to open and close seamlessly, infrared sensors play a pivotal role. In this article, we will explore how automatic door infrared sensors work to detect motion or the presence of individuals, making these doors responsive to the needs of pedestrians.

Understanding Infrared Sensors

Infrared sensors, also known as passive infrared (PIR) sensors, are devices that can detect infrared radiation, which is emitted by all objects with a temperature above absolute zero (-273.15°C or -459.67°F). In the context of automatic doors, PIR sensors are used to identify motion or the presence of people near the door.

1. Sensing Infrared Radiation:

Infrared sensors consist of multiple sensor elements or pyroelectric sensors. These sensors are typically made of a crystalline material that generates an electric charge when exposed to infrared radiation. When an object or a person enters the sensor's field of view, it emits varying amounts of infrared radiation based on its temperature and movement.

2. Sensitivity to Temperature Changes:

The key to the functionality of PIR sensors is their sensitivity to rapid temperature changes. When a warm object, like a person's body, moves within the sensor's range, it causes a significant temperature differential in the sensor's field of view. This change in temperature prompts the pyroelectric sensor to generate an electrical signal.

3. Detection Patterns:

Infrared sensors are designed with specific detection patterns or zones, which determine the area they cover. Common patterns include fan-shaped, cylindrical, or square zones. The choice of pattern depends on the door's design and intended use.

4. Signal Processing:

The electrical signal generated by the pyroelectric sensor is processed by the sensor's electronics. This processing distinguishes between random temperature fluctuations (such as those caused by changes in the environment) and significant changes associated with the presence of a person or motion.

5. Triggering the Door Mechanism:

Once the sensor detects a significant temperature change or motion within its detection zone, it sends a signal to the door's control system. The control system then activates the motor or mechanism responsible for opening the door.

Benefits of Infrared Sensors for Automatic Doors

1. Efficiency: Infrared sensors are highly efficient because they only activate the door when needed. This helps conserve energy by reducing unnecessary door openings.

2. Safety: Infrared sensors enhance safety by preventing doors from closing on individuals or objects in their path. They ensure that doors remain open or reopen if motion is detected.

3. Accessibility: Automatic doors equipped with infrared sensors provide greater accessibility to people with disabilities, including those using wheelchairs or mobility aids.

4. Convenience: The hands-free operation of automatic doors with infrared sensors offers convenience to all users, particularly when entering or exiting buildings with their hands full.


Automatic door infrared sensors are a remarkable technological advancement that enhances the functionality and efficiency of modern buildings. By detecting motion and the presence of individuals, these sensors provide a safe, convenient, and accessible solution for pedestrians. Their ability to respond to changes in temperature and motion ensures that automatic doors open and close precisely when needed, contributing to energy savings and a more comfortable environment for all.



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