What type of sensor uses infrared light to prevent door closing?

The use of infrared safety sensors in elevator door systems is vital for ensuring passenger safety. These sensors emit infrared light beams across the doorway which, when interrupted by an object or a person, triggers a mechanism to stop the doors from closing. This technology is designed to prevent accidents that can happen if a door were to close on someone entering or exiting the elevator. By detecting the presence of obstacles, infrared safety sensors provide a reliable means to ensure that the elevator doors remain open until the way is clear, thus enhancing the overall safety and functionality of the elevator system.

In contrast, magnetic sensors typically utilize a magnetic field for position sensing and are not primarily designed for detecting physical presence or obstructions in the way of moving parts like elevator doors. Pressure sensors detect changes in pressure but are also not suited for this specific application of door-closing prevention, as they usually require direct contact rather than detecting presence through a non-contact method. Ultrasonic sensors use sound waves instead of light to detect objects, but infrared safety sensors are specifically tailored for door operation and have proven to be more effective in this particular context.