- Sensor use high power infrared opto-electrical diode and highly sensitive transistor
- Detecting distance can be changed from 4-13 mm.
- Non-contact detect method.
One the left is the overview of opto-electrical diode, it’s made up of transmit diode and receiver, on the right view, A, K is the positive and negtive of the infrared transmit diode, and C, E is the positive and negtive of the receiver.
So when A end connects to high TTL and K connects to low, the infrared transmit can send infrared light. And adding external circuits to detect signal on receiver end.
The resistors are used to limit the current, R1=510Ω，R2=20kΩ
When receiver receive the return infrared light, the receiver end will connected through, E ends will output high TTL, which close to Vcc value, if not the E ends output low TTL close to GND.
The white materials absorb less light and reflect most of the light wave; but the black material can absorb most of the light and reflect few. So based on this point, we should just select correct distance (1cm e.g.) and use the circuit above to detect white or black line.