LCD Texture Defects via Dual-Pixel Voltage Control
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Solution Overview
Problem
Liquid crystal display (LCD) technologies face challenges in controlling liquid crystal molecules at the middle of micro-slits in patterned vertical alignment mode LCDs, leading to texture defects and irregular transmittance due to misalignment and incomplete rotation of liquid crystals under electric fields.
Innovation Solution
The implementation of a structure with a first and second pixel electrode, a passivation layer, and a texture control electrode, where the effective voltages applied to the liquid crystal layer are differentiated by varying the thickness of the passivation layer and applying voltages to the pixel electrodes, ensuring 0.3<V2/V1<0.9 to achieve uniform transmittance and prevent texture defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a patterned pixel electrode with micro-slits is used to align liquid crystal molecules in different directions, then the viewing angle is widened, but the liquid crystal molecules at the middle of micro-slits become difficult to control, leading to texture defects
Solution Approach 1:
A texture control electrode is introduced as an intermediary element between the pixel electrode and the liquid crystal layer. This electrode applies a specific effective voltage (V2) to the liquid crystal layer, mediating the alignment control in regions where the patterned pixel electrode alone is insufficient, particularly at the middle portions of micro-slits. The passivation layer serves as a physical intermediary that enables voltage differentiation between the two electrodes.
Solution Approach 2:
The texture control electrode applies a locally differentiated effective voltage (V2) that is distinct from the pixel electrode voltage (V1). By controlling the effective voltage ratio (0.3<V2/V1<0.9), the system creates different electric field conditions in different regions of the liquid crystal layer, enabling precise local control of liquid crystal alignment in the middle of micro-slits while maintaining the overall patterned structure for wide viewing angle.
2Device complexity
If the same voltage is applied to both pixel electrodes, then the structure is simple, but the effective voltages differ due to passivation layer thickness variations, causing non-uniform transmittance
Solution Approach 1:
The system implements a feedback mechanism where the effective voltage ratio (V2/V1) is monitored and controlled within the range of 0.3 to 0.9. This feedback control compensates for variations in passivation layer thickness, ensuring that despite structural differences, the liquid crystal layer receives appropriately differentiated voltages that result in uniform transmittance across the display.
Solution Approach 2:
The invention changes the voltage parameter applied to the texture control electrode relative to the pixel electrode. By setting the effective voltage ratio (V2/V1) between 0.3 and 0.9, the system optimizes the electric field distribution to compensate for passivation layer variations, achieving uniform transmittance without requiring identical passivation layer thickness throughout.
3Reliability
If the passivation layer thickness is varied to control effective voltage, then the effective voltage can be differentiated, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of varying the passivation layer thickness to control effective voltage, the invention changes the voltage parameter (applying different voltages V1 and V2 to the pixel electrode and texture control electrode respectively). This approach achieves the same effective voltage differentiation while maintaining a uniform, easily manufacturable passivation layer structure.
Solution Approach 2:
The invention moves from controlling effective voltage through the physical dimension (passivation layer thickness) to controlling it through the electrical dimension (applied voltage values). By adjusting the voltage parameter rather than the physical structure, the system achieves effective voltage control with simpler manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures uniform rotation of liquid crystal molecules across the pixel area, eliminating texture defects and enhancing transmittance by adjusting the electric field distribution, thereby improving display quality and reducing manufacturing complexities.
Implementation Method 1
a liquid crystal layer including vertically aligned liquid crystal molecules between the first and second substrates
Implementation Method 2
∈p is a dielectric constant of the passivation layer, dp is a thickness of the passivation layer, and ∈LC is a dielectric constant of the liquid crystal layer
Data Source
AI summary
A liquid crystal display includes a first substrate, a first pixel electrode, a second pixel electrode, a second substrate, and a liquid crystal layer. The first pixel electrode is formed on the first substrate. The second pixel electrode overlaps with at least a part of the pixel electrode with the first insulating layer interposed therebetween. The second pixel electrode has a plurality of elongated openings and applies a voltage to the liquid crystal layer that is different from the voltage the first pixel electrode applies to the liquid crystal layer.