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Label Printer Sensors and Calibration

Learn how to calibrate and troubleshoot label printers in Bravo by adjusting sensors for accurate tag printing.

Label Printing Basics – Calibration and Moveable Sensors.

 

Calibrating a Label printer serves one purpose: Determining where it can start and stop printing on a Label. 

There are various sensors and sensing methods, but the outcome is usually the same. Manual calibration is almost never preferred as this usually disables automatic calibrations until the printer is factory reset.  This can pose long-term consistency issues and prevent the customer from resolving calibration issues by themselves.

Sensing Methods

  • Gap / Web Sensing: Detecting the space between each label.  This is best for labels that are uniform in size.
  • Mark Sensing: Detecting a mark underneath the label.  These work better for labels that vary in height (such as barbell labels).
  • Continuous: This is best for labels that do not have a gap between them nor a mark to determine the start.

Adjustable Sensors

Some printers such as the Zebra ZD series and the Godex G500 have moveable sensors.  How do you know where to position the sensor?  Here are a few key points:

  1. The position of the sensor does not affect the print horizontally (left to right).
  2. The position of the sensor must be underneath the printable area.
  3. If the label is non-uniform (such as barbell) you always want the sensor aligned with the tallest part of the label.

If the sensor is not underneath the printable area, the labels will likely feed endlessly, skip labels, or cause errors before or after the print.

The following diagram can help explain a little better. In each diagram, the top label shows what the sensor picks up and the bottom label would be the outcome:

  1. If the sensor is in the position shown above, we see that it is aligned with the center of the barbell.  After calibrating, the printer will think the label starts at the “B” position which is not the actual starting point of the printable area.
  2. In this situation, the label will begin to print almost halfway down the label where you’ll be attempting to use offsets to correct the issue.  This is not the proper way to resolve these issues.

Compare that with a correct sensor position.  In the example below, the sensor will first see the widest area of the label (A) and begin printing at the ideal vertical position. Neither of these examples will affect how the printer moves the data left or right.  They will both align identically horizontally. With that in mind, issues with the label printing too far left or right should be addressed differently.

Now imagine the above scenario but with a uniform label.  The sensor position won’t matter much if it’s underneath the printable area.

Here are real-world examples of a Barbell being used with a Godex Printer – with the labels centered in the printer, we want to match the sensor position on the left to ensure it picks up the label correctly when calibrating.  The Circled area is the sensor which goes underneath the label and the section of the label that it would detect when calibrating.  In the good example, it would know to start from the highest area of the label.  In the second picture with the X, the sensor will start printing 1/3 down the label and cause everything to print too low and to print across multiple labels: