LCD Array Substrate Transparent Composite Electrode Aperture Ratio
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Solution Overview
Problem
Conventional liquid crystal display (LCD) array substrates have a reduced aperture ratio due to the large area of opaque metal common electrodes used in storage capacitors, leading to increased power consumption to maintain brightness.
Innovation Solution
The array substrate design incorporates a transparent lower electrode and a composite upper electrode with both transparent and metal portions for the storage capacitor, allowing for a smaller metal electrode area while maintaining capacitor capacity, and uses a planarization layer to connect the pixel electrode to the source/drain electrode, enhancing the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of the common electrode is increased to increase storage capacitor capacity, then the storage capacitor capacity is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent applies composite materials by using a combination of transparent conductive material (such as ITO) and metal conductive material in the upper electrode of the storage capacitor. This composite structure allows the electrode to provide both high capacitance (through the metal portion) and light transmission (through the transparent portion), thereby resolving the contradiction between increasing capacitor capacity and maintaining aperture ratio.
2Quantity of substance
If the area of the common electrode is increased to increase storage capacitor capacity, then the storage capacitor capacity is improved, but the power consumption is increased
Solution Approach 1:
The composite upper electrode structure with transparent conductive material allows light to pass through the capacitor region, maintaining display brightness without requiring increased backlight power. Simultaneously, the metal portion ensures sufficient capacitance is achieved, avoiding the need to increase overall electrode area and thus preventing increased power consumption.
3Area of stationary object
If transparent conductive material is used for the upper electrode to increase aperture ratio, then the aperture ratio is improved, but the storage capacitor capacity is reduced
Solution Approach 1:
The patent applies local quality by creating different regions within the upper electrode with different material compositions. The transparent conductive material region provides light transmission for high aperture ratio, while the metal conductive material region provides high conductivity and capacitance. This localized differentiation allows the electrode to simultaneously achieve both high aperture ratio and sufficient storage capacitor capacity.
Data Source
AI summary
A method for fabricating an array substrate for a liquid crystal display (LCD) is provided. A semiconductor layer and a transparent lower electrode formed on a substrate is provided and covered by a first dielectric layer serving as a gate dielectric layer and a capacitor dielectric layer. A gate electrode and an upper electrode comprising a transparent electrode portion and a metal electrode portion are formed on the first dielectric layer and covered by a second dielectric layer. A source/drain electrode, a planarization layer, and a pixel electrode are sequentially formed on the second dielectric layer, in which the source/drain electrode is electrically connected to the semiconductor layer through the first and second dielectric layers and the pixel electrode is electrically connected to the source/drain electrode through the planarization layer. An array substrate for an LCD is also disclosed.