Transparent Storage Capacitor Electrodes in Liquid Crystal Displays
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Solution Overview
Problem
Medium and small-sized liquid crystal display devices face challenges in achieving a high aperture ratio and sufficient electrostatic capacity due to the use of opaque materials for storage capacitors, which reduces transmittance and increases manufacturing complexity.
Innovation Solution
The use of transparent conductive materials for the storage capacitor electrodes allows for increased area overlap without significantly reducing transmittance, enhancing electrostatic capacity and simplifying the manufacturing process by eliminating the need for specific patterning on the common electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If opaque materials are used for storage capacitor electrodes, then electrostatic capacity is increased, but transmittance is reduced and aperture ratio deteriorates
Solution Approach 1:
The patent changes the material parameter of the storage capacitor electrodes from opaque to transparent conductive material, enabling the electrodes to maintain electrostatic capacity while allowing light transmission. This parameter change resolves the contradiction by finding a material that satisfies both requirements simultaneously.
2Quantity of substance
If the area of overlap between upper and lower electrodes of storage capacitor is widened to increase capacitance, then electrostatic capacity is improved, but aperture ratio is degraded
Solution Approach 1:
The patent changes the optical parameter of the electrode material to transparent conductive material, which allows the electrode area to be expanded for higher capacitance without the same penalty to aperture ratio that would occur with opaque materials, since the transparent material does not block light transmission in the display area.
3Adaptability or versatility
If patterning process for transparent electrode is added to form liquid crystal domain, then PVA mode operation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent makes the transparent electrode serve multiple functions: it acts as both the common electrode for voltage control and as the domain formation structure for PVA mode operation. By forming protrusions on the substrate before depositing the transparent electrode material, the electrode itself creates the liquid crystal domains, eliminating the need for separate patterning processes.
4Adaptability or versatility
If independent process for forming protrusions is added, then liquid crystal domain formation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the protrusion formation process with the transparent electrode deposition process. The protrusions are formed on the substrate, and then the transparent electrode material is deposited over them in a single continuous manufacturing sequence, combining two functions into one integrated process flow rather than separate independent 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 improves the aperture ratio and electrostatic capacity of liquid crystal display devices while maintaining high transmittance, simplifying the manufacturing process and reducing the risk of misalignment between substrates.
Implementation Method 1
The storage capacitor is typically formed by forming a lower electrode and an upper electrode, and an insulating layer therebetween
Implementation Method 2
A liquid crystal display device controls light transmittance of a liquid crystal by using an electric field
Implementation Method 3
controls light transmittance of a liquid crystal by using an electric field, thereby displaying images
Data Source
AI summary
A liquid crystal display device is disclosed. The device includes: a first substrate (10), a thin film transistor (23,12,26,28) formed in a first, non-transmissive region (TFT) on the first substrate, including a gate electrode (12), a source electrode (26) and a drain electrode (28), and a storage capacitor (30,18,25) formed in a second, transmissive region (Cst) on the first substrate, where a first electrode (30) and a second electrode (25) of the storage capacitor are made of a transparent conductive material. A half-tone mask process is used to simultaneously fabricate the gate electrode (12) and the first electrode (30).