GP2Y0A21YK0F is a distance measuring sensor unit,
composed of an integrated combination of PSD
(position sensitive detector) , IRED (infrared emitting
diode) and signal processing circuit.
The variety of the reflectivity of the object, the
environmental temperature and the operating duration
are not influenced easily to the distance detection
because of adopting the triangulation method.
This device outputs the voltage corresponding to the
detection distance. So this sensor can also be used as
a proximity sensor.