How to Set Up the Label Sensor of Pressure Sensitive Labeling Systems for Accurate Label Gap Detection

The accuracy of the label sensor setup directly determines labeling precision. The most intuitive way for an operator to verify correct adjustment is by observing the sensor's indicator light. In essence, the process teaches the sensor to distinguish between "label" and "gap"-that is, between the material itself and the space between labels.

The core function of the label sensor (a photoelectric sensor) is to reliably detect the gap between a label and its backing paper, or between consecutive labels. When properly calibrated, the sensor will show a distinct, stable signal change: for example, a red light when over a label and a green light when over a gap or backing paper.

 

Four-Step Calibration Guide for a Fiber Optic Label Sensor

 

Step 1: Install and Position

• Pass the label web smoothly through the sensor's detection slot, keeping it flat and wrinkle-free.
• Adjust the sensor so its light spot is centered on a label gap (typically a ~2mm clear area).

 

Step 2: Teach the Sensor

• Teach "Label Present"

Place a label under the sensor. Press and hold the set button until the indicator flashes (approx. 3 seconds), then release. The sensor stores the signal for "label."

• Teach "Label Absent":

Move a label gap (or backing paper) under the sensor. Hold the set button until the indicator flashes again (approx. 8 seconds), then release. The sensor now recognizes the "gap" signal.

 

Step 3: Verify Switching

Slowly move the label web so that labels and gaps pass alternately under the sensor.

Watch the indicator:

• Over a label → red (or off, indicating weak signal).
• Over a gap/backing → green (or on, indicating strong signal).

Stable, clear switching means the sensor is correctly set.

 

Step 4: Fine-Tune Sensitivity (If Needed)

If the signal flickers or fails to switch, adjust the sensitivity dial:

• Clockwise to increase sensitivity (easier triggering).
• Counterclockwise to decrease sensitivity.

Adjust until the transition between label and gap is sharp and consistent.

 

 

Notes for Common Sensor Types

1. Through-Beam Sensor (e.g., Leuze):

Detects differences in transmitted light. Label = low light (red), gap = high light (green). Ensure precise emitter–receiver alignment.

2. Reflective Sensor (e.g., SICK):

Detects differences in reflected light. Label = strong reflection (green), backing = weak reflection (red). Adjust sensitivity according to label surface.

3. Fiber Optic Amplifier Sensor:

Allows threshold setting via buttons or software. Use label and backing paper signal levels as the switching reference.

 

 

Troubleshooting Guide

1. Indicator Does Not Switch:

a. Verify label web is threaded correctly.

b. Clean the sensor lens if dirty or contaminated.

c. Check electrical connections and power.

 

2. Indicator Flickers or Triggers Unreliably:

a. Re-adjust sensitivity; may be set too high or too low.

b. For transparent, glossy, or holographic labels, consider a specialized sensor (e.g., UV or laser type).

c. Shield the sensor from ambient light, or use a modulated-light model.

 

 

Conclusion

Proper label sensor calibration is essential for consistent, accurate labeling. By following the Position → Teach → Verify → Fine-tune method, you establish a reliable detection signal that ensures precise label dispensing.

For support with special materials or complex setups for your pressure sensitive labeling systems, contact the YD Pack technical team.