Basic Knowledge of Photoelectric Sensors

Glossary of Photoelectric Sensors

Glossary

Term	Description	Term	Description
Sensing distance	Through-beam The distance between an emitter and receiver.	Light ON	The control output turns ON, when the received light amount exceeds the threshold.
	Retro reflective The distance between a sensor and reflector.	Dark ON	The control output turns ON, when the received light amount falls below the threshold.
	Diffuse reflective The distance between a sensor and standard detection object.	Laser off input	An external input can be used to stop light emittance of the sensor.
Minimum detectable object (Diameter)	The minimum object size that the sensor can detect.	External input	Output of a sensor can be made, according to status of an external input.
Response time	Time to turn on or off an output, according to presence of an object.	External Teach	Teach setting of a sensor can be triggered by an external input.
Hysteresis	A distance between a point that a Diffuse-reflective type makes an output on a standard detection object and, then, a point that it turns the output off.	Off-delay timer	An output is held for a preset time. The function can be combined with controller programs.
Repeat accuracy	A variation range in which a sensor performs detection.