Uneven Character Spacing in Inkjet Printing: Causes and How to Fix It

Character spacing irregularities in inkjet coding—such as compressed, stretched, or unevenly spaced text—can affect readability and create a poor visual impression. Whether using CIJ, TIJ, or DOD systems, this issue is usually mechanical, signal, or layout-related. This guide outlines the key reasons behind inconsistent character gaps and how to fix them effectively.

Typical Symptoms

• ⚠️ Text appears wavy or inconsistent in horizontal spacing
• ⚠️ Some characters overlap or are squeezed together
• ⚠️ Barcodes printed below text are aligned, but text is uneven
• ⚠️ Problem appears only at specific speeds or product types

Common Causes and Solutions

1. Encoder Signal Instability

• Cause: Speed feedback from encoder is inconsistent or noisy
• Fix:
  • Ensure encoder is mounted on a non-slipping roller
  • Secure encoder cabling and check for electromagnetic interference (EMI)
  • Test encoder pulse with oscilloscope or printer diagnostics tool

2. Layout or Font Rendering Error

• Cause: Font file corruption or message layout contains misaligned fields
• Fix:
  • Use default system fonts or regenerate the layout from scratch
  • Avoid custom spacing fields unless precisely configured
  • Preview text in software before production print

3. Printhead Misalignment to Conveyor Motion

• Cause: Printhead not mounted perfectly perpendicular to product travel
• Fix:
  • Recalibrate printhead angle to ensure 90° alignment
  • Use alignment guides or jig blocks during installation

4. Conveyor Speed Variation or Vibration

• Cause: Product moves inconsistently due to motor irregularities or vibration
• Fix:
  • Use conveyor with stabilized servo motor
  • Add stabilizers, top belts, or guiding rails to reduce wobble

5. Print Mode or Trigger Timing Error

• Cause: Print triggered too early or late based on sensor delay or product size
• Fix:
  • Adjust “print delay” and “print start offset” settings
  • Use precision sensors with narrow beam to detect product reliably

Best Practices

• ✅ Use verified layout files with preview before live printing
• ✅ Calibrate encoder, conveyor, and printhead position together
• ✅ Avoid custom fonts with excessive spacing variance
• ✅ Periodically check character spacing using a ruler or visual guide

FAQs

• Does this issue affect barcodes too? Barcodes are usually block-rendered and less affected, but any spacing issue in 1D barcodes can cause scan errors
• Can I manually fix character spacing? Yes—most systems allow custom kerning/spacing settings per message or font

Conclusion

Uneven character spacing in inkjet printing is typically caused by misalignment, unstable speed signals, or layout formatting errors. By correcting mechanical setup and verifying print logic in software, you can ensure consistent and professional code appearance. For layout optimization or encoder calibration assistance, contact Cheef Inkjet at sales@cheef.cn.