High-Precision TFT Panel Flatness Measurement

3C03.TFT Panel Flatness Measurement: Ensuring Precision in Display Manufacturing

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3C03.TFT Panel Flatness Measurement: Ensuring Precision in Display Manufacturing

Aug 15, 2025

1. Why TFT Panel Flatness Measurement Matters

In the production of TFT (Thin Film Transistor) panels, surface flatness is a key factor affecting optical performance, assembly alignment, and final product quality.

Optical performance: Uneven surfaces can cause light leakage, color distortion, and reduced display uniformity.
Assembly accuracy: Poor flatness may lead to misalignment in lamination processes.
Yield rate: Early detection of flatness defects reduces scrap and rework costs.

2. Common Measurement Methods: Pros and Cons

Measurement Method	Principle	Advantages	Limitations
Contact-type stylus profiler	Physical probe scans the surface profile	High resolution; suitable for small-area inspection	Slow; risk of scratching surface; unsuitable for delicate TFT glass
Laser triangulation	Measures displacement via light reflection angle	Fast, non-contact	Limited accuracy on transparent or reflective TFT surfaces
White-light interferometry	Interference pattern analysis	Very high resolution; suitable for optical surface inspection	Limited range; sensitive to vibrations
Chromatic confocal measurement	Wavelength-based height detection	High precision; works on transparent, reflective surfaces; no contact	Higher cost; requires proper optical alignment

3. Principle and Process of Chromatic Confocal Measurement

Chromatic confocal displacement sensors use broad-spectrum light and a focus-wavelength detection principle:

Step 1: White light passes through a chromatic lens, dispersing into different wavelengths along the optical axis.
Step 2: Only the wavelength in perfect focus on the TFT panel surface is reflected back into the sensor.
Step 3: The sensor’s spectrometer detects this peak wavelength, converting it into a precise height or flatness value.

Why it’s ideal for TFT flatness measurement:

Measures both transparent glass and coated layers without surface damage.
High sampling speed up to 32kHz for inline inspection (currently, the highest model is the CP series).
Immune to reflectivity issues common with TFT surfaces.

4. TronSight’s Solution

The TronSight TS-C Series Chromatic Confocal Displacement Sensor delivers:

Up to 32kHz sampling rate with 16-channel fully synchronous acquisition for large-area panel inspection.
EtherCAT protocol compatibility for integration into automated inspection systems.
Probes with ±60° maximum measuring angle and minimum diameter of 3.8mm, adaptable to various process environments.
Capable of multi-layer glass measurement, including protective films and optical coatings.