Common Electrode Wire Routing for LCD Aperture Ratio
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Solution Overview
Problem
Conventional liquid crystal display devices face challenges in stabilizing the reference potential of a common electrode while maintaining a high aperture ratio, as extending the common electrode out of the display area increases interconnection resistance and decreases aperture ratio.
Innovation Solution
A display device design where a common electrode is placed to overlap pixel electrodes via an insulating film, with signal lines supplying image signals and a common electrode wire extending parallel to signal lines to provide a reference potential signal, reducing interconnection resistance and avoiding parasitic capacitance formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode is extended out of the display area to supply common voltage, then the common voltage can be supplied, but the interconnection resistance increases and aperture ratio decreases
Solution Approach 1:
The patent transitions from extending the common electrode in the planar direction (out of display area) to routing the common electrode wire in the vertical direction (parallel to signal lines) through the pixel electrode regions. This dimensional change allows the common electrode wire to pass through the display area without extending beyond it, maintaining aperture ratio while providing stable reference potential through reduced interconnection resistance.
Solution Approach 2:
The patent segments the common electrode into multiple common electrode wires that are distributed throughout the display area. Instead of one extended common electrode, multiple segmented wires run parallel to signal lines, each serving local pixel electrodes. This segmentation reduces the length of each wire segment, lowering interconnection resistance while keeping wires within the display area boundaries.
2Ease of manufacture
If the common electrode wire is disposed to overlap signal lines, then routing is simplified, but parasitic capacitances are formed between common electrode wire and signal lines
Solution Approach 1:
The patent extracts the common electrode wire from positions where it would overlap with signal lines. By carefully positioning the common electrode wire to pass through regions between signal lines and pixel electrodes, the design removes the harmful overlapping configuration while maintaining the simplified routing approach of running wires parallel to signal lines through the display area.
3Reliability
If signal lines are increased in number and arrangement space to accommodate common electrode wire placement, then reference potential stability is improved, but the frame width increases and definition decreases
Solution Approach 1:
The patent utilizes the vertical dimension (direction perpendicular to signal lines) for routing common electrode wires, rather than increasing horizontal space. By running common electrode wires parallel to and between signal lines in the vertical direction, the design provides multiple wire options without increasing frame width, thereby maintaining high definition while ensuring reference potential stability.
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 design stabilizes the reference potential of the common electrode, enhances display quality, and maintains a high aperture ratio, achieving higher definition and a narrower frame.
Implementation Method 1
a common electrode wire, placed in such a manner that a pixel electrode that is adjacent to two signal lines between which a pixel electrode is interposed is interposed between the common electrode wire and a signal line, that extends parallel to the signal lines and supplies the common electrode with at least a reference potential signal
Implementation Method 2
a common electrode placed in such a manner that at least part thereof overlaps the plurality of pixel electrodes via an insulating film
Implementation Method 3
A display is done on the basis of potential differences that are generated between the common electrode and the pixel electrodes
Data Source
AI summary
A liquid crystal display device includes pixel electrodes, a common electrode placed in such a manner that at least part thereof overlaps the pixel electrodes via an inter-transparent-electrode-film insulating film, at least two source lines, placed in such a manner that the pixel electrodes are interposed therebetween, that supply the pixel electrodes with image signals, and a common electrode wire, placed in such a manner that the pixel electrodes that are adjacent to the two source lines between which the pixel electrodes are interposed between the common electrode wire and the source lines, that extends parallel to the source lines and supplies the common electrode with at least a reference potential signal.