Air Gap

Air Gap

Overview

When mounting glass laminated with a DISPLAX Touch sensor onto a monitor, it is essential to introduce a controlled air gap between the display and the touch sensor. This air gap significantly reduces the impact of electromagnetic interference (EMI) generated by the monitor, improving touch accuracy and stability.


Why an Air Gap Is Required

Monitors emit varying levels and types of electromagnetic noise depending on their design and electronics. If the touch sensor is mounted directly against the display, this noise can interfere with the touch signal, leading to:

  • False touches

  • Touch instability

  • Reduced touch sensitivity

  • Edge or border inaccuracies

A properly sized air gap acts as an EMI buffer, preventing the monitor’s electrical noise from coupling into the touch sensor.


To securely fix the glass with the laminated DISPLAX Touch sensor to a monitor:

  • Apply double-sided bonding tape around the bezel of the monitor

  • Recommended tape types:

    • 3M VHB tape

    • Or an equivalent high-quality industrial double-sided tape

This tape comes in varying thicknesses, and this mounting method naturally creates the required air gap between the display surface and the touch sensor.


Air Gap Specifications

ParameterRecommendation
Minimum air gap1 to 2 mm (recommended)
Maximum air gap10 mm
UniformityMust be consistent across the entire monitor
Adjustment goalAs narrow as possible once interference is no longer visible

⚠️ An uneven air gap can introduce touch distortion and should be avoided.


Testing Before Final Integration

Because EMI characteristics vary between monitors, testing is mandatory before final assembly.

  1. Temporarily place equal-sized, non-conductive, non-adhesive spacers on the monitor bezel:

    • Foam

    • Cork

    • Plastic spacers

  2. Mount the laminated glass on top

  3. Gradually increase the spacer thickness to adjust the air gap

  4. Observe the touch signal and behavior

  5. Stop increasing the air gap once:

    • False touches disappear

    • Touch becomes stable across the entire active area

Only after identifying the optimal air gap should permanent bonding tape be applied.


Best Practices

  • Always keep the air gap as small as possible while eliminating noise

  • Test center and edges of the touch sensor during evaluation

  • Different monitors of the same size may require different air gaps

  • Never use conductive materials as spacers


Summary

An air gap is a critical mechanical and electrical requirement when integrating DISPLAX Touch sensors with monitors. A uniform air gap of at least 2 mm, created using double-sided bezel tape, significantly improves EMI immunity and ensures reliable touch performance. Always test before final installation.


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