Grooved Passivation Layer for LCD Transmittance and Voltage
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Solution Overview
Problem
Liquid crystal display (LCD) devices face challenges with low-voltage operability and optical transmittance due to the passivation layer, which absorbs or reflects light and weakens the electric field, requiring higher driving voltages and reducing transmittance.
Innovation Solution
The formation of grooves on the passivation layer between the pixel and common electrodes at predetermined depths, allowing for improved optical transmittance and reduced driving voltage by increasing the cell gap and decreasing the threshold voltage, without damaging the alignment layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed to protect the TFT, then the TFT is protected from damage, but the optical transmittance is deteriorated and the electric field is weakened
Solution Approach 1:
The passivation layer is selectively removed in specific regions (pixel regions and common electrode regions) to create local variations in optical properties and electric field distribution, while maintaining protection in other areas. This allows high transmittance where needed while preserving TFT protection elsewhere.
Solution Approach 2:
The passivation layer is divided into different regions: removed in pixel and common electrode regions, and retained in other areas. This segmentation allows the structure to simultaneously achieve high optical transmittance in display regions and adequate protection in non-display regions.
2Reliability
If a passivation layer is formed to protect the TFT, then the TFT is protected from damage, but the driving voltage must be increased
Solution Approach 1:
The passivation layer is selectively removed in electrode regions to locally enhance electric field strength, reducing the overall driving voltage required while maintaining TFT protection in other areas where the passivation layer remains intact.
3Illumination intensity
If the passivation layer is removed to improve transmittance, then optical transmittance is improved, but the TFT protection is reduced
Solution Approach 1:
The passivation layer is selectively removed only in regions where high transmittance is critical (pixel and common electrode regions), while maintaining the passivation layer in other areas to preserve TFT protection. This localized approach optimizes transmittance without compromising overall device reliability.
4Productivity
If electrodes are arranged closely to improve pixel density, then the pixel density is increased, but the transmittance is greatly deteriorated on the electrodes
Solution Approach 1:
The passivation layer is selectively removed in pixel and common electrode regions, allowing electrodes to be arranged closely for high pixel density while maintaining high transmittance in these regions. The local removal compensates for the transmittance loss that would otherwise occur due to closely spaced electrodes.
Data Source
AI summary
A liquid crystal display device includes a gate line on a substrate; a data line defining a pixel region by crossing the gate line; a thin film transistor formed at a crossing position between the gate line and the data line; a passivation layer protecting the thin film transistor; a pixel electrode connected with the thin film transistor; a common electrode generating an electric field with the pixel electrode; and a plurality of grooves on the passivation layer, wherein at least one of the pixel electrode and the common electrode is arranged at intervals in the pixel region, and the grooves are formed at intervals on the passivation layer disposed between the at least one of the pixel electrode and the common electrode arranged at intervals in the pixel region.