Thread: What is the difference between infrared sensor and the pyroelectric sensor?

I am looking for a sensor that when you walk into a room the light will turn and stay on even if your not moving in the room and will only turn off when exting. Will the infrared sensor or the pyroelectric sensor work for my application? Or is there a different kind sensor out there ?

Infrared sensors are usualy designed to detects near infrared. Pyroelectric sensors (aka passive infrared or PIR)are usualy designed to detect a wide band of infrared.

I'd like also to invite your question to a group dedicated to sensors: http://tech.groups.yahoo.com/group/sensorforum

I know I answered your other question, but here are some references. The last one from hamamatsu ( a manufacture) is very informative.

Take a good look at these articles. You will see many similarities.

http://en.wikipedia.org/wiki/Passive_infrared_sensor
http://en.wikipedia.org/wiki/Pyroelectric

Note where they discuss design of these the materials are the same; gallium nitride (GaN), caesium nitrate (CsNO3), polyvinyl fluorides.


Here is a document that will tell you everything you want to know ... and much more I'm sure. It goes into detail about the terminology and physics of these sensors (both photoelectric and pyroelectric)

http://sales.hamamatsu.com/assets/applications/SSD/Characteristics_and_use_of_infrared_detectors.pdf

I hope you get this cleared up ... good luck.

Edit: Note, SensorForum is correct also. Near infrared is the same as shortwave IR and the "wide band" he mentions refers to IR extending out into the longer wavelengths (heat)