Cut Sheet

Volume 8—Sensing Solutions CA08100010E—July 2015 www.eaton.com V8-T5-5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5.0
Photoelectric Sensors
Introduction
Modes of Detection
Thru-Beam
Source and detector
elements are mounted in
separate housings and
aligned facing each other
across an area which the
target object crosses.
Detection occurs when an
object blocks the entire
effective beam (the column
of light that travels in a
straight line between lenses).
See Page V8-T12-27.
Reflex
The source and detector are
mounted in a single sensor
housing and are positioned
parallel to one another on the
same side of the object to be
detected. The light beam is
transmitted from the source to
a retroreflector that returns the
light to the detector. Detection
occurs when the target object
blocks the entire effective
beam. See Page V8-T12-28.
Reflex Detection Mode
Diffuse Reflective
The source and detector
elements are mounted in a
single sensor housing and are
positioned on the same side
of the object to be detected
and aligned with crossed
fields of view. When the target
moves into this area light
from the source is reflected
off the target surface back to
the detector and detection
occurs. See Page V8-T12-28.
Diffuse Reflective Detection
Mode
Perfect Prox
Perfect Prox
is a special
type of diffuse reflective
sensor that combines
extremely high sensing
power (excess gain) with a
sharp optical cutoff. This
allows the sensor to reliably
detect targets regardless of
variations in color,
reflectance, contrast or
surface shape, while ignoring
background objects that are
just slightly beyond the target
range. See Page V8-T12-28.
Range
Each sensor listed in this catalog has a specific operating range. In general, thru-beam sensors
offer the greatest range (most power), followed by reflex and then diffuse reflective sensors.
Operating ranges vary, and there is some overlap among types and models. See Applying Excess
Gain on Page V8-T12-30.
Excess Gain
Excess gain is a measure of
the sensing power available
in excess of that required to
detect an object. The
following excess gain chart
shows this measurement
graphically. Find your required
range on the x-axis of the
graph. Then move up to the
curve to read the excess gain
value from the y-axis. An
excess gain value of 1 is the
minimum level required for
sensor operation. Eaton
normally recommends
excess gain levels ≥10 for
reliable sensor operation. See
Page V8-T12-30.
Photoelectric Sensor
Excess Gain Graph
Note: The excess gain charts in
this catalog represent the
minimum excess gain provided
by the sensor (unless otherwise
noted). Actual performance may
be better.
Contamination
The chart on Page V8-T12-32 shows the excess gain recommended in environments with varying
levels of contamination for each sensing mode.
Detector
Source
Target
Target
Reex
Sensor
Retroreector
Beam Complete
No Object Present
Object Detected
Source
Detector
Source
Detector
Diffuse
Reective
Sensor
Target
Beam Not Complete
No Object Present
Object Detected
Source
Detector
Source
Detector
Fixed Focus
Perfect Prox
Sensor
Target
Background
1000
10
1
10.1 10 100
RANGE (feet)
EXCESS GAIN
100
RANGE (mm)
0.30.03 3.0 30.5