Conquering Visual Pain Points: Solutions for Warm-Cold Color Shift in LCM/INCELL Display Modules

As you swipe the screen of the latest flagship smartphone, have you ever noticed subtle tonal differences on either side—one leaning warm yellow, the other cool blue? This pesky warm-cold color shift represents a core challenge for high-end display modules, particularly in LCM (Liquid Crystal Module) and advanced INCELL (In-Cell Touch) technologies, where color consistency directly impacts user experience and brand reputation. This article deeply analyzes its causes and leading industry control strategies.

I. The Culprits Behind Color Shift: Variable Games in Precision Structures

LCM/INCELL modules are intricately stacked from TFT glass, color filter (CF), upper/lower polarizers, liquid crystal layers, and backlight systems. Color shift arises from minute fluctuations in three critical areas:

1. Spectral Discreteness of Backlight LEDs

As the "light source engine," batch variations in LED chips can cause color temperature fluctuations of thousands of Kelvin (e.g., ±0.02 color coordinate deviation corresponds to a 4500K–10,000K span), directly creating warm-cool divides on the screen.

2. Optical Property Variations in Polarizers

When light transmittance deviates by over 5%, the energy balance of RGB (RGB light) is disrupted, triggering hue shifts.

3. Nanoscale Differences in CF Layer Color Resist Film Thickness (Core Factor)

A coating tolerance of ±0.05μm can shift color coordinates by ±0.03, equivalent to a color temperature difference of over 1000K! The "yin-yang screen" phenomenon—where the left side appears yellow and the right blue—mostly stems from this.

II. Full-Chain Collaboration: A Systematic Approach to Eradicating Color Shift at Its Source

Leading manufacturers have compressed color coordinate fluctuations to ±0.01 (color temperature difference within ±900K) through end-to-end process refinement:

▶ Material Traceability: Batch-Locked Consistency

·Coordinated LCD-Backlight Procurement: 

A major manufacturer pre-stocks 500,000 LCD panels of the same batch for a single project, matched with homologous backlight LEDs, controlling color coordinate variation within ±0.015.

·Dedicated Polarizer Sourcing: 

Mixing polarizers from different suppliers once caused color coordinate deviations exceeding 0.02 in a batch, leading to a 12% scrap rate.

▶ Optical Matching: Precise Synchronization of LEDs and CF

·Standard Color Gamut Solutions:

Silicate phosphor LEDs use a "two large color blocks + four small color blocks" mixing strategy (e.g., Jufei Optoelectronics’ F-block scheme), with color coordinate control at ±0.01.

· High Color Gamut Solutions: 

RG phosphor LEDs require 1:4 and 2:3 block cross-ratio matching; a flagship phone achieved ±900K color temperature control via this method.

▶ Process Innovation: Nanoscale Control of CF Coating

Laser interferometers are introduced to monitor film thickness in real time, reducing color resist tolerance from ±0.05μm to ±0.03μm. This boosts yield from 82% to 95% and improves color coordinate consistency by 40%.

III. Terminal Validation: The Final Mile from Lab to User Experience

Mass production control requires rigorous scenario testing:

· Extreme Corner Sample Testing:

 Extract 100 samples with extreme color coordinate values (max/min X/Y) for subjective evaluation by clients. A tablet project with a 1500K color temperature difference saw only 37% user acceptance, forcing a production line recalibration.

· 3 Gamma Dynamic Compensation: 

Software-level color temperature calibration via R/G/B gain adjustment. Adjusting the Gamma value from 2.2 to 2.6 can lower screen color temperature from 6500K to 5500K, effectively neutralizing cool tones.

Conquering warm-cold color shift is not a single-point breakthrough but a deep collaboration among LCM manufacturers, backlight suppliers, and terminal brands. The industry has achieved ±0.01 color coordinate precision, yet user perception is evolving to the 0.005 magnitude. From quantum dot phosphors to perovskite technologies, next-gen material innovations will continue pushing color accuracy in display modules to new frontiers—because the ultimate uniformity of every inch of screen is a solemn commitment to visual experience.

About EDL

Founded in Shenzhen in 2010, EDL Electronics (EDL in brief) expanded the world leading factory in Longyan, Fujian in 2019. It is a specialized and innovative enterprise specializing in the design, development, production and sales of display products. EDL provides customers with a full range of cost-effective small and medium-sized display modules, solutions, and services with excellent quality worldwide. Oriented in technology and high quality, EDL keeps sustainable development, works to offer customers  better and stable services.