Instruction Manual

MICRO-AMP
®
System
SP100FF Fixed-eld Sensor
Conceptual Drawing
Model SP100FF is a xed-eld convergent mode sensor that detects objects directly
by reection of light from the object's surface. The light is sensed at two receive points
and compared to dene a precise limit to the maximum sensing range. Objects in the
background are ignored, regardless of their surface reectivity.
This sensing response feature makes the SP100FF an ideal choice for detecting a part or a
surface that is only a small fraction of an inch in front of another surface. The SP100FF
is highly reliable for semiconductor wafer sensing. Wafers of all reectivities are sensed
without mechanical or system sensitivity adjustment. Other applications include cut-to-
length control, double-thickness detection, and precision edgeguiding. The SP100FF is
an excellent choice for precise position control (e.g. as a robotic end effector).
The SP100FF works in conjunction with Banner MICRO-AMP modulated amplier
model MA3A or MPC3A. Model MA3A is powered by +10 to 30V dc and uses a model
RS8 socket. Model MPC3A is powered by +5V dc and is designed for mounting directly
onto PC boards.
With a typical excess gain of 100X at the peak signal point (referenced to a 90% reec-
tance white test card), the SP100FF has enough optical energy to reliably sense material
of very low reectivity such as nitride-coated semiconductor wafers. The typical peak
signal point is 0.12 inch from the sensor face. Excess gain falls off sharply beyond the
peak signal point (see excess gain curve, below).
Printed in USA P/N 03523C4A
WARNING These photoelectric sensing devices do NOT include the self-checking redundant circuitry necessary to allow their use
in personnel safety applications. A failure or malfunction can result in either an energized or a de-energized output condition.
Never use these products as sensing devices for personnel protection. Their use as safety devicse may create an unsafe condition which
could lead to serious injury or death.
Only MACHINE-GUARD and PERIMETER-GUARD Systems, and other systems so designated, are designed to meet OSHA and ANSI machine safety
standards for point-of-operation guarding devices. No other Banner sensors or controls are designed to meet these standards, and they must NOT be used
as sensing devices for personnel protection.
Excess Gain Curve
The SP100FF uses two photoelements that operate with the modulated amplier in a dif-
ferential mode. The photoelements are mechanically convergent with the LED light source
at two different distances from the sensor face. The inner photoelement (R1) produces
a positive-going pulse which turns the output
of the amplier "on". The outer photoelement
(R2) produces a negative-going pulse that works to turn the amplier "off".
A target is sensed whenever the amount of light reaching receiver R1 is equal to or greater than the
amount of light "seen" by R2. The output of the amplier is cut off as soon as the amount of light at
R2 becomes greater than at R1. The location of this "crossover point" is dictated by the geometry of
the optoelement conguration, and remains the same regardless of the target's reectivity.
Reections even from highly-polished mirror-like surfaces are ignored if the reections originate from
beyond the crossover point. Modulated LED design offers very high excess gain at the convergent point
of R1 (see excess gain curve). As a result, even objects of very low reectivity may be sensed.
The rapid fall-off in signal strength over a very short distance (as seen in the excess gain curve) ac-
counts for the highly repeatable distance-sensing accuracy of the SP100FF, independent of target
surface reectivity.
Theory of Operation
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Optical design ensures an exact range limit, regardless of the
surface reectivity of the objects to be sensed
Powerful infrared light source and modulated amplication pro-
vide reliable sensing of objects with low surface reectivity
Sensor response to background objects is completely suppressed
Miniature size ts easily into tight areas of machines
Works with special versions of Banner's MICRO-AMP
®
Series
of modulated ampliers