Pixel Storage Capacitor Layout for Larger Display Openings
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Solution Overview
Problem
Existing electro-optical devices, such as liquid crystal devices, face a technical challenge in simultaneously increasing the capacitance value of storage capacitors and the size of the opening region, which affects display performance.
Innovation Solution
The implementation of a storage capacitor formed in the opening region using a transparent conductive film and dielectric film, with light shielding films to shield the transistor elements and prevent light leakage, allowing for increased capacitance without reducing the opening ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the storage capacitor is formed in the non-opening region to increase capacitance value, then the capacitance value is improved, but the opening region size is reduced
Solution Approach 1:
The patent extends the storage capacitor structure into the third dimension by forming the capacitor electrode and dielectric film in multiple layers. The capacitor electrode is formed on the light shielding film, and the dielectric film is formed on the capacitor electrode, creating a vertically stacked configuration that increases capacitance without occupying additional planar area in the opening region.
Solution Approach 2:
The storage capacitor is nested within the existing pixel structure by forming the capacitor electrode on the light shielding film that already exists in the non-opening region. The dielectric film is then formed on the capacitor electrode, creating a compact nested arrangement that utilizes the vertical space within the pixel structure rather than expanding horizontally into the opening region.
2Area of stationary object
If the opening region is enlarged to improve display performance, then the opening region size is improved, but the storage capacitor size is reduced
Solution Approach 1:
The patent resolves this contradiction by moving the storage capacitor formation into the vertical dimension. The capacitor electrode and dielectric film are stacked in layers above the light shielding film, allowing the opening region to be maximized in the horizontal plane while the capacitance is increased through vertical layering.
Solution Approach 2:
The light shielding film serves a dual function: it shields the transistor element from light in the non-opening region, and simultaneously serves as the base for forming the storage capacitor electrode. This local differentiation allows the same structure to fulfill multiple functions without compromising either light shielding or capacitance formation.
3Object-affected harmful factors
If the light shielding layer is provided to shield transistor elements, then the contrast ratio is improved, but the device complexity is increased
Solution Approach 1:
The light shielding film is designed to perform multiple functions simultaneously: it shields the transistor element from light to prevent unwanted activation, serves as an electrical connection structure, and provides the base for forming the storage capacitor electrode. This multi-functionality reduces the need for separate dedicated structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the light shielding function with the storage capacitor formation by forming the capacitor electrode directly on the light shielding film. This combining of functions reduces the total number of separate layers and structures needed, thereby limiting the increase in device complexity while maintaining effective light shielding.
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 enhances display performance by increasing the capacitance value and enlarging the opening region, thereby improving image quality and contrast ratio.
Implementation Method 1
a first light shielding film constituting a portion of a display region on a substrate and formed in a non-opening region through which light does not penetrate
Implementation Method 2
a storage capacitor is provided between the TFT and a pixel electrode made of a transparent electrode such as an ITO for the purpose of enhancing contrast in the displayed image
Implementation Method 3
a transparent pixel electrode formed on the dielectric film in the opening region, constituting a storage capacitor together with the transparent conductive film and the dielectric film
Data Source
AI summary
An electro-optical device includes a first light shielding film; a transistor element formed on the first light shielding film to overlap the first light shielding film; a second light shielding film formed on the transistor element to overlap the transistor element and electrically connected to an input terminal of the transistor element; a transparent conductive film extended toward an upper layer side of the second light shielding film in an opening region, through which light penetrates, of the display region; a dielectric film formed on the transparent conductive film in the opening region; and a transparent pixel electrode formed on the dielectric film in the opening region, constituting a storage capacitor together with the transparent conductive film and the dielectric film, and having a transparent pixel electrode which is electrically connected to the transistor element.