Alternating Source and Drain Electrode Branches in LCD TFTs
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Solution Overview
Problem
The existing U-type thin-film transistors (TFTs) in liquid-crystal displays (LCDs) have low channel region efficiency and high parasitic capacitance, leading to increased load on the gate line and decreased charging rate due to inefficient current flow and large parasitic capacitance values between electrodes.
Innovation Solution
The design includes a TFT structure with source and drain electrode branches arranged alternately, each with specific width and shape regions, and a drain electrode connector, reducing parasitic capacitance and enhancing current driving capability by optimizing the channel region formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a U-type TFT structure is used, then the transistor can be formed with conventional processes, but the parasitic capacitance between gate electrode and source/drain electrodes is large
Solution Approach 1:
The source and drain electrodes are divided into multiple separate branches instead of continuous structures. The source electrode is segmented into first, second, and third source electrode branches, while the drain electrode is segmented into first and second drain electrode branches. This segmentation reduces the overlapping area between gate electrode and source/drain electrodes, thereby reducing parasitic capacitance while maintaining conventional manufacturing compatibility
Solution Approach 2:
The patent employs asymmetric electrode configurations where source and drain electrodes have different branch arrangements and dimensions. The source electrode branches have different widths and positions relative to the gate electrode, and the drain electrode branches are asymmetrically positioned. This asymmetry optimizes the channel region formation and minimizes parasitic capacitance by reducing symmetric overlapping areas
2Power
If the channel region width is increased to improve current flow, then the driving capability is enhanced, but the parasitic capacitance increases and charging rate decreases
Solution Approach 1:
The channel region is formed through multiple segmented electrode branches rather than a single wide electrode. The first, second, and third source electrode branches combined with first and second drain electrode branches create an effective channel width of 10 μm or more through their collective arrangement, while each individual branch maintains narrow dimensions that minimize parasitic capacitance
Solution Approach 2:
The patent transitions from considering only channel width to utilizing two-dimensional electrode arrangement. The electrode branches are positioned at different locations and orientations relative to the gate electrode, creating an extended channel path that achieves high driving capability through spatial distribution rather than simple width increase
3Object-affected harmful factors
If the source and drain electrodes are positioned close to each other to reduce channel width, then the parasitic capacitance is reduced, but the current flow efficiency decreases
Solution Approach 1:
The electrode structure is segmented into multiple branches with optimized spacing. The source electrode branches and drain electrode branches are positioned close to each other in certain regions to minimize parasitic capacitance, while the overall arrangement maintains sufficient channel width for efficient current flow. The segmentation allows different parts of the electrode structure to serve different functions
Data Source
AI summary
A liquid-crystal display including: a gate line extending in a first direction; a gate electrode protruding from the gate line; a gate insulating layer arranged on the gate electrode; an active layer arranged on the gate insulating layer while being insulated from the gate electrode; a data line arranged on the active layer and extending in a second direction; a source electrode protruding from the data line, having a portion overlapping the gate electrode on a plane, and including a plurality of source electrode branches that are separate from each other; a drain electrode being separate from the source electrode, and including a plurality of drain electrode branches, each being arranged between two of the plurality of source electrode branches, and a drain electrode connecting part connecting the plurality of drain electrode branches; a pixel electrode defining a pixel region; a liquid-crystal layer arranged on the pixel electrode.