9
OMRON Scientific Technologies Inc.
© OMRON STI 0613 PN99804-0060 Rev. B
26
9 I
NSTALLATION
9
9 . 1 R
E F L E CT I V E
S
U RF AC E
I
N T E R F ER EN CE
A reflective surface adjacent to the detection zone can deflect the optical beam and may cause an
obstruction in the zone not to be detected. (See
Figure 9-1
through
Figure 9-5
.) The reflective surface
may be part of the machine, mechanical guard or workpiece. Therefore, a minimum distance (d) must
exist between the reflective object and the center line of the detection zone. The Test Procedure
(Appendix B)
must
be used to test for this condition.
Figure 9-1 Worst Case Alignment Example
The interruption is clearly detected. The reflective object is outside of the beam angle.
Figure 9-2 Unsafe Mounting Example (1)
The interruption is not detected because of the reflection. The reflective object is inside the beam
angle.
Figure 9-3 Unsafe Mounting Example (2)
Interruption is not detected because of the reflection. Reflective surface interference may also appear
above and below the sensing field
Transmitter
Receiver
Beam Angle, a
d
Reflective Surface
Operating Range, R
a
a
Perimeter of danger area
Receiver
Reflective Surface
Reflection
Interruption
a
Sensing Field
Transmitter
Transmitter
Receiver
Approach direction
Central beam
Light beam interrupted
d
Reflective Surface
Perimeter of danger area
Reflection
Interruption
a
Beam Angle, a
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