Have you ever wondered just how automatic doors work? How is it that so many types of automatic doors, from sliding glass doors at the supermarket to rollup doors at warehouses, seem to know just when to open? Believe it or not, there are several types of automatic door sensors, and there's a very precise science behind each one.
Here are a few of the most common.
Proximity sensors. Several types of automatic doors are outfitted with proximity sensors. These sensors are usually mounted above the door, and they emit an electromagnetic or infrared beam and look for changes in the projected field. Proximity sensors only need to pick up on changes in the beam to activate the door.
Different types of proximity sensors can be set to react to various types of movement. For example, some sensors respond exclusively to metal (ideal if your business uses forklifts) while others work better with wood or plastic targets. Some of the most common facilities using proximity sensors include transportation buildings, waste management facilities, and large warehouses or factories.
Motion detectors. Most commercial automatic doors are equipped with motion detectors that respond to moving objects. By measuring changes in spaces anywhere from 5 to 80 feet, motion detectors are an optimum choice for automatic doors. Depending on the technology in the device, motion sensors simply emit a beam and then react to the changes in the beam.
There are four types of motion detector sensors:
- the passive infrared which detects body heat
- the ultrasonic which emits pulses of ultrasonic waves and thus detects moving objects,
- the microwave sensor which emits microwave pulses and measures the changes reflecting from an object in motion
- the tomographic detector which uses radio waves to sense motion over large areas.
While motion detectors have long been popular for commercial doors, these detectors are also becoming a favorite for automatic lighting systems simply for the reduced energy costs.
Loop detectors. For areas where forklifts or other vehicles will frequently pass through, automatic doors are often outfitted with loop detectors. Loop detectors are a series of wires connected to a device in a circuit board. The wires create a looping electromagnetic current. When the current is disrupted by a forklift or car, the loop detector responds by opening the door. Most facilities are outfitted with entrance and exit loop detectors so that the door closes only when drivers are at a safe distance.
Remote transmitters. Some automatic doors are operated by remote transmitters – a.k.a., a person clicking a button or entering a code. Sound complex? Not really. Think of the remote control for your TV, or the key code your employees enter to access the building.
These types of automatic sensors are more common in areas that require higher security or simply experience lower traffic. Remote transmitters most often activate when they receive the correct radio wave signal from the remote control or keypad device.
Automatic door sensors are popular with businesses because they save time and manpower, but more and more businesses are going automatic to save on energy costs.