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Sensing Principles |
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A diffuse reflective sensor detects
an object by direct reflection off the object. The colour and texture of the object can
have a significant effect on the sensing distance. Light colour objects will be detected
at a greater distance than dark objects. Light Switching : The output of the sensor turns on when the object is present. Dark Switching : The output of the sensor turns on when the object is not present. |
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A background suppression sensors
works like a diffuse sensor except it has an adjustment to ignore the background - even if
the background is more reflective than the object. Also, the colour of the object has
little effect on the sensing distance. Light Switching : The output of the sensor turns on when the object is present. Dark Switching : The output of the sensor turns on when the object is not present. |
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A retro-reflective sensor uses a
reflector. When an object is placed between the sensor and reflector, the beam is
interrupted. A retro-reflective sensor has a much longer sensing distance than a diffuse
type. Light Switching : The output of the sensor turns on when the object is not present. Dark Switching : The output of the sensor turns on when the object is present. |
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A through beam sensor
has a separate transmitter and receiver. When an object is placed between the transmitter
and receiver, the beam is interrupted. A through beam system has the longest sensing range. Light Switching : The output of the sensor turns on when the object is not present. Dark Switching : The output of the sensor turns on when the object is present. |
