Delta CS24D - Manual (Page 27)

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9. Characteristics
9.1 Temperature
The feedback circuitry automatically compensates for the normal LED intensity variation
with temperature yielding a typical stability of 0.05%/C. In the most critical applications,
the CS24D should be maintained at a constant temperature since the LED color varies
slightly with temperature.
9.2 Edge Effects
The CS24D series have large sensing areas. (The CS24D-02, for example, sees an area
of approximately 0.5 inches square). When material is entering or leaving the sensing
area, the color can appear wrong for a variety of static and dynamic conditions. For best
results, read the discrete outputs only when the CS24D sees the intended material over
the entire viewing area. The Hold input
can be used to “capture” the data.
9.3 Convex and Concave Surfaces
Glossy convex surfaces can reflect directly
into the sensor, reducing the stability of
readings. To avoid this, try to keep convex
surfaces perpendicular to the narrow axis
of the sensor. Concave surfaces should be
avoided if possible.
9.4 Angle of CS24D to Material
Generally, the most consistent readings
are obtained if the material is perpendicular
to the CS24D in both planes. If angle
differences cannot be avoided, it is preferable
to have the angle the narrow
way and the standoff at the longer end
of the recommended range (2 inches for the
CS24D-02). In some cases when dealing
with shiny materials, angling the sensor
(along the narrow axis) slightly with respect
to the target may produce more consistent
readings.
9.5 Distance Performance
The amplitudes of the readings reach the maximum value at the nominal standoff
distance or slightly closer (about 1.5" for CS24D-02 and CS24D-03) and then decrease
with distance. The ratios of Red/Intensity, Green/Intensity and Blue/Intensity are adjusted
to be constant within the specified tolerance over the specified working range of the
sensor. As the sample is moved further from the CS24D, the ratios will gradually
become less consistent. This effect, along with the decrease in signal amplitude, limits
the usable range of the CS24D. In applications where the differences in samples are
large, the CS24D-02 and -03 may work well out to 3" or more.