Diffuse Mode Alignment

Object

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 ad-

justment. Rule of thumb for diffuse sensing: The distance to the nearest back-

ground object should be at least three times the sensing distance.

Note:

• Light condition: sensor output is ON when there is no object in beam

• Dark condition: sensor output is ON when there is an object in beam

Retroreflective Mode Alignment

Retro

Target

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 SM312LV).

Note:

• Light condition: sensor output is ON when there is no object in beam

• Dark condition: sensor output is ON when there is an object in beam

Convergent Mode Alignment

Object

Low

Reflectivity

Background

The sensing energy of a convergent mode sensor is concentrated at the specified

focus point. 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.

Note:

• Light condition: sensor output is ON when there is no object in beam

• Dark condition: sensor output is ON when there is an object in beam

MINI-BEAM dc-Voltage Series

4

www.bannerengineering.com - tel: 763-544-3164

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