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In looking into all things infrared I keep coming across references to infrared sensors. When I think about infrared sensors I think of walking in front of automatic doors and they open, but I wanted to know if I was right and a bit more about them.
I know that an infrared sensor is an electronic device, they can be used for detecting an infrared heat signature or by emitting an infrared heat signature. All objects emit an infrared signal which can be detected by a sensor. This is how a motion detector works, the sensors detect a change in temperature in front of them and sets off an alarm.
Active infrared sensors
Sensors can be active or passive. Active sensors send out a signal and they take a snapshot of the response that comes back a bit like a sonar system. When something changes in that response, usually when someone or something gets in front of it then it triggers an action like a door opening. If you have a home security system this might be the way it works or a garage door opener.
Have you wondered how your tv remote works? It uses an infrared led that emits a signal from the end of the remote. You won’t be able to see it because infrared is invisible to the naked eye but there will be a receiver in your TV that will be able to see the light from the remote control and that trigger the action of turning it on or off.
So how does it know if you press different buttons? It emits the infrared light in pulses based on binary code with a different code for each action on the remote control and a specific code to identify the make and model of the TV so it doesn’t work on your other devices. How clever is that!
Have you noticed the new video doorbells that are becoming very popular? Well these doorbells work with motion sensors and infrared night vision. Motion sensors we’ve talked about but night vision is used in thermal cameras to detect heat at various ranges. Infrared is a great security tool.
Passive infrared sensors
A passive infrared sensor usually reads changes in temperature when something moves into the proximity of it. These are often used in cameras when filming wildlife or lights that you might have on the outside of your house. To get a wider range of view, these security sensors are often placed behind a lens. These can usually be adjusted so they don’t set off with small animals.
Some systems used a mixture of both of these types of sensors like shop doorways that emit a sound when you walk in to alert the shop assistant.
One of the great items that you can buy that uses passive infrared sensors is a trail camera. If you like to go camping or even in your own garden you can set up a trail camera which is set off to record by any movement within the field of view that it can cover.
These types of cameras are often used in tv documentaries when they are accumulating information about different breeds of animals but you can use this as a great teaching tool with your children to learn about the small animals that are in the area around you. You can buy these cameras for less than $100 and some for even less than $50 and the kids will love learning to set it up and watching the film afterwards.
Proximity infrared sensors
A proximity infrared sensor emit infrared waves that check the area in front of it for changes. They are often used for non contact of metallic objects. The most well known use is for a parking sensor on your car.
Did you know that you have a proximity sensor in your iphone? There is a sensor that detects when you move you phone to you ear by checking how close it is to an object and it puts the display to sleep so that you save power if you are having a long phone conversation but more importantly so that you don’t touch any controls by mistake with your hand while holding your phone to your ear.
Keep germs from building up around the soap dispenser by investing in an automatic infrared dispenser which can sense when you’re hands go underneath and will dispense the soap accordingly.
Infrared temperature sensor
Infrared temperature sensors are used to measure temperature without touching an object or person by measuring the radiated energy emitted. This energy measured is converted to an electrical signal and then changed into a temperature readout.
This is used in infrared cameras that can convert the infrared readings into temperatures. Most objects have a thermal output and it shows in the color range on the display. Most infrared cameras have a central point that will give you a temperature if you point the camera where you need to have that information but there is also a color range chart on the side of the screen so you can know the range of objects around that central point. These cameras can be used at home so you can audit your house for heat loss but they are often used by contractors in their line of work.
Infrared thermometers can be pretty versatile, you have personal thermometers which you can use to measure temperature via the ear or the forehead. Most people wouldn’t be without a thermometer if they have children so it is easy to check if they ever get too hot with a fever to be in danger, it’s a quick instant read and helps to give you peace of mind.
You can get a hand held infrared thermometer which makes measuring food or water temperature much easier when you don’t have to touch it, this is useful for people who sell food and they can check the temperature to keep it safe and if you take a bath or want to bathe your child you can make sure the temperature of the water is at a safe level.
As you can see the use of infrared sensors can be used in a variety of ways in so many products and most of these are there to improve your life, save you time or to protect you.