OPR20: Teach-in Details

Using the latest SDD (version > 2.0) for OPR20 you get an additional page inside the SDD - called "Teach-In Details".

This page helps you to understand why the OPR is detecting some material successfully and others not. It helps you to diagnose your application.

To understand what's actually shown you need to understand a bit of the detection principle.

The OPR20 uses 8 emission LEDs in 2 rows (marked with A1...4 and B1...4).
The signal of each LED is received by two array lines (Z1 and Z2).
Out of this results that internally 16 array signal curves exist to be evaluated:

If glossy material is detected the signal curve will have

• high amplitude
• low width

If matt material is detected the signal curve will have

• low amplitude
• high width

The teach-in algorithm of OPR20 uses this two main criteria to distinguish between gloss and non-gloss.

To visualize the process we draw the width of the signal on the X and the amplitude of the signal on the Y axis. Each measurement of the sensor is a dot in the plot.

To simplify the whole detection OPR20 has internal automatic algorithms to find the best out of the 16 available curves. It analyses all signals and finds the curve which is best to evaluate (evaluating amplitude, width, steepness, etc.). This is done during Teach-in and during process in run-mode.
So all the time each signal is processed - but only one finds its way into the plot above.

During teach-in the sensor stores the position of the measurement in the plot (red dot) and defines a rectangular area around it .
If a measurement in run-mode (yellow dots) hits this rectangular area the material is similar to the material during teach-in.

The sensitivity setting of OPR20 is found in the size of the rectangular area. 
Coarse sensitivity = big area
Fine sensitivity = small area

For a 1-point teach there is one area in the plot like above.
For a 2-point teach there are two areas.
And for a 3-point teach there is a third area (the background area).

All the rest of the plot is hysteresis.

The OPR20 will change its switching state as soon as a measurement value (yellow dot) hits one of the dedicated areas (Teach-point 1, TP1 // Teach-point 2, TP2 // Backgroud, TP3).

All measurements which are in-between do not affect the switching state. It is a complete hysteresis area. So if the measurement value travels from area 1 to area 2 the sensor keeps switched on until the measurement value hits area 2.

If the boxes of TP1 and TP2 overlap due to coarse sensitivity or due to similar teach-points OPR20 shows a teach-in failure.
Using this tool you can now simply evaluate if there is enough glossy-difference between material A and material B.

The 'Teach-in Details' page shows the measurement value as a red cross.
Teach-in area 1 and Teach-in area 2 are shown as blue boxes.
The background area is shown in black.

The monitoring tool starts automatically and you will immediately see a red cross jumping around.

In the lower right corner you find the current measurement value of amplitude and width which is shown right now.

Additionally a graphic which shows the OPR20 from the backside (not looking into the lens).
The highlighted LED (in this case A2) and the highlighted array line (in this casw Z2) are the origin of the measurement which is shown. That means in this example situation the best signal came curve resulted from LED A2 and array line Z2.

If the automatic / cyclic measurement mode is too fast or if you like to have a single measurement on a specific point on a material you can switch to 'manual' measuring mode.
The Sample button will be enabled and will allow you to do single measurements.

The switching output of the OPR20 is not affected by this. It is still working!

If you like to see the distribution of a lot of measurements or keep track of the whole travel through of a product you can activate the checkbox 'Trace measurement value'.
Using the number below you can decide how many measurement values will be stored in the plot.
0 = maximum possible amount of measurement values.

Finally there is a button to reload the teach-in areas if needed.

If you not already have the newest SDD files you can download them here as attachment (they are also available directly in SOPAS and on sick.com)