Transparent Electrode Storage Capacitance in LCD
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Solution Overview
Problem
Liquid crystal display devices face challenges in securing a large storage capacitance and high aperture ratio while maintaining a low manufacturing cost, particularly due to the difficulty in forming sufficient storage capacitance as pixel sizes decrease with the transition to ultra-high definition displays.
Innovation Solution
The implementation of a liquid crystal display device structure that includes a gate electrode, a first insulating film, an element layer made of transparent oxide, and separate first and second transparent electrodes, where the second transparent electrode forms a storage capacitance with the first transparent electrode while being electrically insulated, allowing for a large storage capacitance and high aperture ratio without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal auxiliary capacitance electrode is used to secure storage capacitance, then the storage capacitance is sufficient, but the aperture ratio decreases due to light blocking
Solution Approach 1:
The patent changes the material parameter of the auxiliary capacitance electrode from opaque metal to transparent conductive material (such as ITO, IZO, or IGZO), maintaining the electrode's capacitance function while allowing light transmission. This material substitution resolves the contradiction by preserving storage capacitance without blocking light, thereby maintaining high aperture ratio.
2Manufacturing precision
If separate deposition steps are used for transparent electrodes and element layer, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the deposition processes for the transparent electrode and element layer into a single simultaneous deposition step. Both layers are formed from the same transparent oxide material layer in one process, eliminating the need for separate deposition equipment and process steps. This reduces manufacturing complexity and cost while maintaining sufficient precision through integrated process control.
3Measurement precision
If pixel size is reduced for ultra-high definition displays, then definition is improved, but storage capacitance becomes insufficient
Solution Approach 1:
The patent changes the material properties of the auxiliary capacitance electrode from opaque metal to transparent conductive oxide, enabling the electrode to be positioned closer to the pixel aperture without blocking light. This allows the overlapping area between electrodes to be optimized for capacitance while maintaining small pixel dimensions, thus achieving both ultra-high definition and sufficient storage capacitance.
Data Source
AI summary
A liquid crystal display device includes a gate electrode, a first insulating film, an element layer, a first transparent electrode, and a second transparent electrode. The first insulating film includes a part that covers the gate electrode. The element layer is directly disposed on the first insulating film, includes a channel region that faces the gate electrode across the first insulating film, and is made of a transparent oxide. The first transparent electrode is directly disposed on the first insulating film while being separated from the element layer, and has the same metal composition as the metal composition of the element layer. The second transparent electrode forms a storage capacitance with the first transparent electrode by facing the first transparent electrode while being electrically insulated from the first transparent electrode.