Electro-optical Device Holding Capacitor Light Shielding Layer
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Solution Overview
Problem
Active drive type liquid crystal devices face instability due to optical leakage current when intense light is incident on the semiconductor layer of the thin film transistor, leading to complex wiring and light shielding structures that compromise display performance.
Innovation Solution
An electro-optical device with a holding capacitor and a light shielding layer is implemented between the substrate and the transistor, featuring conductive layers and a light shielding layer that overlap each other to block light and ensure electrical capacitance, while the holding capacitor includes two capacitance elements electrically coupled in parallel to stabilize the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light shielding structure is introduced to block light incident on the semiconductor layer, then optical leakage current is suppressed, but the wiring structure becomes more complex
Solution Approach 1:
The patent combines the light shielding function and capacitance element function into a single integrated structure. The light shielding layer serves dual purposes: blocking light from reaching the semiconductor layer and acting as one of the capacitance electrodes. This merging eliminates the need for separate capacitance wiring structures, thereby suppressing optical leakage current while avoiding increased wiring complexity.
Solution Approach 2:
The light shielding layer is designed to perform multiple functions simultaneously: it acts as a light shielding barrier, a capacitance electrode, and a wiring conductor. By making the light shielding layer universal, the patent eliminates the need for additional dedicated capacitance wiring structures, thus maintaining operational stability without increasing device complexity.
2Reliability
If the capacitance element is disposed to cover the convex portion, then electrical capacitance is ensured, but the contact hole depth and wiring complexity increase
Solution Approach 1:
The patent merges the capacitance element with the light shielding layer structure. The light shielding layer itself forms part of the capacitance element, eliminating the need for separate capacitance wiring and deep contact holes. This integration ensures adequate electrical capacitance while avoiding increased wiring and contact hole complexity.
Solution Approach 2:
The patent extracts the capacitance function from the traditional separate capacitance wiring structure and integrates it directly into the light shielding layer. By taking out the need for complex capacitance wiring and deep contact holes, the invention simplifies the overall structure while maintaining the necessary electrical capacitance for stable display operation.
3Device complexity
If the light shielding layer and capacitance element are integrated, then device complexity is reduced, but light shielding effectiveness may be compromised
Solution Approach 1:
The patent combines the light shielding layer and capacitance element into a single integrated structure without compromising light shielding effectiveness. The light shielding layer maintains its light-blocking properties while simultaneously serving as a capacitance electrode, ensuring both operational stability and adequate electrical capacitance without increasing device complexity.
Solution Approach 2:
The patent applies local quality by ensuring the light shielding layer has appropriate light-blocking properties in the regions where it contacts the semiconductor layer, while maintaining its capacitance function in other regions. This localized optimization ensures effective light shielding where needed without sacrificing the electrical capacitance functionality of the integrated structure.
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 light shielding properties, suppresses optical leakage currents, and maintains stable display operation even with high-intensity light, ensuring improved electrical capacitance and display quality.
Implementation Method 1
a light shielding layer between the substrate and the transistor... enhances light shielding properties, suppresses optical leakage currents
Implementation Method 2
a holding capacitor between the substrate and the light shielding layer... ensures improved electrical capacitance and display quality
Data Source
AI summary
An electro-optical device includes a base material as a substrate, a TFT as a transistor, a scanning line as a light shielding layer between the base material and the TFT, and a holding capacitor between the base material and the scanning line. The holding capacitor includes a first conductive layer, a second conductive layer provided on the first conductive layer via a first capacitor insulating layer, a third conductive layer electrically connected to the second conductive layer via a first contact hole provided in an insulating layer covering the second conductive layer, and a fourth conductive layer provided on the third conductive layer via a second capacitor insulating layer.