Which group do the Proximity sensors belong to?

Question

I was actually doing some research about motion/gesture sensors. well there are different types of motion sensors like : Passive Infrared (PIR), Area reflection type, Ultrasonic, and etc.

Well, I know that even proximity sensors are widely used as motion sensors. Since it doesn't emit the rays can i consider proximity sensors as PIR sensors?

1. Does it belong to PIR group?

on the other hand, there are some proximity detectors which they combine proximity sensor and the LED.

2. Are these proximity detectors simply behave like Rx/Tx pair sensors?

Thank you!

Answer 1

You've got things upside-down:

Proximity detectors aren't a subgroup of PIR sensors. But it's possible that there are PIR sensors which are used as proximity detectors.

Point being, multiple sensor technologies can be used as proximity detectors. For instance:

• IR photoreflector (IR LED and IR photodiode)
• capacitive sensor
• ultrasonic rangefinder
• IR rangefinder (an IR LED and a linear IR CCD, see Sharp GP series stuff)
• even a Hall effect sensor could be used as a proximity sensor if you're sensing the proximity of a particular magnetic target.

etc.

Answer 2

Proximity Sensor is one which detects something that is present around. The above mentioned all the sensors are proximity sensors, I suppose.

PIR is one which does not emit any radiation but it senses the radiation emitted from the bodies that are present around that is why it is called as Passive infra-red sensor.

And for your first question answer is NO, as PIR is one of the proximity sensor.

Proximity sensors may or may not have Rx/Tx pair.

Thank you