Reflective LCD Electrode Structure for High Aperture Ratio
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Solution Overview
Problem
The aperture ratio of reflective liquid crystal display elements decreases with decreasing pixel pitch, affecting optical characteristics due to the increasing gap between pixel electrodes, and existing solutions like overhangs on wiring layers do not fully mitigate this issue.
Innovation Solution
An electrode structure with a light reflection film, an insulating film, and a transparent conductive film divided into a two-dimensional matrix to form transparent pixel electrodes, connected via vias to underlying drive electrodes, which maintains aperture ratio and optical performance even at reduced pixel pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel pitch is reduced to increase display resolution, then definition is improved, but aperture ratio decreases due to increasing gap between pixel electrodes
Solution Approach 1:
The patent introduces a multi-layer structure where the light reflection film is positioned in a lower layer than the pixel electrodes. This vertical dimensionality change allows the light reflection film to extend into the gap regions between adjacent pixel electrodes, effectively utilizing the third dimension to maintain aperture ratio while reducing pixel pitch.
Solution Approach 2:
The light reflection film is divided into multiple regions corresponding to different pixels, with each region positioned in the lower layer beneath its corresponding pixel electrode. This segmentation allows each pixel's light reflection area to be optimized independently while collectively maintaining high aperture ratio across the entire display.
2Area of stationary object
If overhang is provided on wiring layer to occlude gap portion, then aperture ratio decrease is mitigated, but optical characteristics are affected by position difference between pixel electrode and wiring layer
Solution Approach 1:
The patent introduces a light reflection film as an intermediary element positioned in the lower layer. This light reflection film serves as a mediator that reflects light uniformly across the entire pixel area including gap regions, eliminating the optical characteristic issues caused by position differences between pixel electrodes and wiring layers that occur with overhang structures.
Solution Approach 2:
By moving the light reflection function to a lower layer dimension, the patent separates the light reflection function from the pixel electrode position, allowing uniform light reflection across the entire pixel area without being constrained by the horizontal position alignment issues that affect overhang-based solutions.
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 configuration effectively maintains a high aperture ratio and optical characteristics by ensuring that each pixel electrode is connected efficiently, preventing the decrease in reflectance associated with smaller pixel pitches.
Implementation Method 1
Reflective liquid crystal display elements such as an LCOS (Liquid Crystal On Silicon) and an HTPS (High Temperature Poly-Silicon) control reflection of light incident on the liquid crystal display elements to display images
Implementation Method 2
The pixel electrode is driven for each pixel, and thus the pixel electrodes need to be electrically insulated from each other
Data Source
AI summary
An electrode structure includes a light reflection film, an insulating film formed on the light reflection film, and a transparent conductive film formed on the insulating film. The transparent conductive film is divided into pieces in a two-dimensional matrix at a predetermined pitch to form transparent pixel electrodes. Each of the transparent pixel electrodes is connected to a corresponding one of drive electrodes formed in a lower layer underlying the light reflection film, through a corresponding one of vias penetrating the insulating film and the light reflection film and insulated from the light reflection film.