Line Following TCRT5000 IR Infrared Reflective IR Sensor Module ,TCRT5000 infrared sensor emits infrared emitting diode continuously when no infrared rays emitted or reflected back is reflected back but the strength is not large enough, the phototransistor has been in the off state, and the output terminal of the module is high, indicating that the diode has been in the off state; in the object to be detected within the detection range, and the intensity of the reflected infrared rays is large enough, phototransistor saturated, and the output terminal of the module is low, the indicator LED is lit.

In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends the information to other electronics, frequently a computer processor. Sensors are always used with other electronics.

Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, and in innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure  and flow measurement, for example into MARG sensors.

Line Following TCRT5000 IR Feature :

Using infrared reflection sensors TCRT5000
Test reflection distance: 1mm to 25mm
Clean and 3, the comparator output, signal waveform,
driving ability is strong, for more than 15 ma.
With many adjustable precision potentiometer to adjust sensitivity
The working voltage of 3.3V to 5V
Output form: digital switch output (0 and 1)
Has a fixed bolt hole, convenient installation
Small board PCB size: 3.2cm x 1.4cm
The LM393, use of wide voltage comparator
Size:3.1×1.3cm (approx.)

Use for: en.wikipedia.org
The electricity meter pulse data sampling; Fax machine, shredder paper detection; Obstacle detection; Black and white line detection.