Infrared (IR) sensors can detect infrared radiation (heat) and movement. It has a various use cases including:
Automatic Doors - active or passive infrared sensors can be used for this application.
Using active infrared sensors - the sensor emits infrared light and detects changes in the reflected signals when something comes closer. Object detect monitoring system moves a motor to open the door.
Using passive infrared sensors - detect body heat and motion to trigger the signals when something comes closer. Object detect monitoring system moves a motor to open the door.
Automatic closing is implemented after object detection, wait for a delay then check again if there is nothing come by then close.
Remote Controls - active infrared sensors are used in this application.
When user press a button, the remote control’s microcontroller generates a specific binary code corresponding to that action.
The IR LED at the front of the remote blinks to set binary code pattern.
TV has an IR receiver module to demodulates the signal and extracts the binary code.
Decoded signal map with specific user’s input and execute the command.
(NOTE: the binary code is defined by each TV brand)
Flame Detection - active infrared sensors are used in this application.
Special IR flame sensors can detect IR radiation from flames.
(NOTE: fire produces the certain IR radiation range and flicker at specific frequencies.)
The system monitors the flame-like IR radiation and trigger an alarm.
(NOTE: to avoid false alarm, other sensors can detect wavelengths of sunlight or heat sources as comparison)
Blind Spot Detection - active infrared sensors are used in this application.
IR sensors emit infrared beams and measure the reflected signal and whenever any object enters the blind spot, compare with IR reflection pattern.
(NOTE: The pattern is defined by the intensity of IR signal and reflection time)
Analyzing pattern can be improved with machine learning.
Heart Rate Monitoring - active infrared sensors are used in this application.
Measures light absorption changes as blood pulses through veins and arteries. Heart rate is changing with blood volume. The amount of blood volume reflect absorption of IR light. More blood, more absorption.
Process the signal to calculate beat per minute.
The infrared(IR) sensor is a common sensor that is embedded many different application in our life. Five examples are introduced above. Many special sensors are designed for each application. A single IR sensor cannot be used for all applications. Depending on industry, it could be required to safety certificate to use it. In this article, the infrared(IR) sensors have two types: active infrared sensor and passive infrared sensor. The active infrared sensor is used in more various applications than the passive infrared sensor. Also, to avoid the false alarm, the sensor fusion is an option to consider.