What is different about the Sharp IR Sensor?
Comparison to Other Sensors
A normal infrared or light sensor simply determines if a object is bouncing back light. This means that you can only tell whether or not there is an object present. Most of the time this is good enough, but there are situations where you also need to know exactly how far away that object is. This is where the Sharp IR sensor comes into play. The Sharp sensor has a special detector that not only determines if there is light, but can also measure how far away an object is and return an analog value of the distance.
How it Works
The detector in the Sharp IR sensor is similar to the imaging sensor found in digital cameras. Since the detector and the IR LED have a fixed distance and orientation towards eachother, the distance of a object will affect the angle at which the light bounces back. By finding where the light hits the detector, it is possible to calculate the angle or the light and then the distance of the object. The readings, finding of the angle, and the basic trigonometry required to find the distance are all done in the sensor itself to give the distance value.