Sensors: Reflective Optical Sensor
The reflective optical sensor (
Datasheet ) consists of an infrared LED, labelled "E"
for Emitter on the diagrand and on the package, and a phototransistor
that passes an amount of current proportional to the reflected light
received. The phototransistor is labelled "S" for Sensor. The one leg
of the sensor is connected to +5V, which supplies current, and the voltage
drop across the 10k resistor that we measure is proportional to the amount
of current.
There is a continuous voltage response for objects over a short range of
proximity to the sensor. The response is not linear. Linearity can be
approximated by the log of the log of the signal.