Banner MINI-BEAM Series - Manual (Page 3)

P/N 69944 3
Banner Engineering Corp. • Minneapolis, MN U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
MINI-BEAM ® Universal Voltage Sensors
Installation
Guide
The sensing energy of a convergent mode
sensor is concentrated at the specified focus
point (see chart on page 1). Convergent-mode
sensors are less sensitive to background reflections,
compared with diffuse-mode sensors. However, if
background reflections are a problem:
• Skew the sensor position at a 10° to 25° angle to eliminate direct
reflections from shiny background surfaces.
• Reduce the reflectivity of the background by painting the surface(s) flat-black,
scuffing any shiny surface, or drilling a large hole, directly opposite the sensor.
• Reduce the Gain adjustment.
“Flooding” occurs when a portion of the
sensing beam passes around the object to be
sensed. “Burn-through” occurs when a portion of the
emitter’s light energy passes through a thin or translucent
object, and is sensed by the receiver.
To correct either problem, do one or more of the following to reduce the light
energy:
• Reduce the Gain adjustment on the receiver.
• Add an aperture to one or both lenses. (MINI-BEAM apertures, available from
Banner, fit neatly inside the lens assembly.)
• Intentionally misalign the emitter and receiver.
Object
Lo
w
Reflectivity
Bac
kgr
ound
If the alignment LED does not go OFF
when the object is removed from the
beam, the sensor is probably detecting
light reflected from some background object. To
remedy this problem:
• Reduce the reflectivity of the background by painting the
surface(s) flat-black, scuffing any shiny surface, or drilling
a large hole, directly opposite the diffuse sensor.
• Move the sensor closer to the object to be detected and reduce the Gain
adjustment. Rule of thumb for diffuse sensing: The distance to the nearest
background object should be at least three times the sensing distance.
Convergent-Mode Alignment
Light condition: object in beam
Dark condition: no object in beam
Alignment Tips
A highly reflective
object may reflect enough light back to a
retroreflective sensor to allow that object
to slip through the beam, without being
detected. This problem is called “proxing,” and
the following methods may be used to correct it:
• Position the sensor and retro target so the beam will not
strike a shiny surface perpendicular to the sensor lens.
• Reduce the Gain adjustment.
• Add a polarizing filter (for model SMU315LV).
Retr
o
Ta
rg
et
Retroreflective-Mode
Alignment
Light condition: no object in beam
Dark condition: object in beam
Emitter
Receiver
Opposed-Mode Alignment
Light condition: no object in beam
Dark condition: object in beam
Ob
ject Diffuse-Mode Alignment
Light condition: object in beam
Dark condition: no object in beam
p/n 69944 Rev. A