Photoelectric sensor Term definitions
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Infrared light
The wavelength spectrum of infrared light is 0.7 μm to 1 mm. It is divided in near-infrared (0.7 μm to 2.5 μm),
mid-wavelength infrared (2.5 μm to 4 μm), and far-infrared (4 μm to 1mm).
The wavelength spectrum used by general photoelectric sensors is near-infrared and visible light.
Transmission type
The sensor output switches between On and Off when a target passes between the phototransmitter and the photoreceiver, installed facing together, and blocks the light.
Diffuse reflection
The sensor output switches between On and Off when the light emitted from the phototransmitter is reflected on the target and enters into the photoreceiver.
Light modulation method
The period of light emission is constant to prevent influence from external light and make detection at long distances possible.
Light On/Dark On
Light on: Output when a specified amount of light is received.
Dark on: Output when the light that is being received is obstructed.
Detection distance
Transmission type: Shows the maximum distance between the phototransmitter and the photoreceiver at which stable detection is possible.
Reflection type: Shows the distance at which stable detection is possible when using the standard detection target (Kodak Gray Card 90% reflectance).
Hysteresis (reflection type)
The difference between the following distances: the distance at which the sensor switches on (operation) when the detection target approaches the detection surface and the distance when the sensor switches off (reset) when the detection target moves away.
Allowed illuminance from external light
Shows the ambient luminosity at which incorrect detections are prevented.
Dead zone (reflection type)
With reflection type, the zone separated from the light emission and reception areas near the detection surface is called "dead zone". Detection is not possible in this zone.
