FFS-LCD Common Electrode and Passivation Layer Mask Merging
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Solution Overview
Problem
The manufacturing of liquid crystal displays with two field generating electrodes on one panel incurs high costs and can result in signal delays due to the need for multiple photomasks and potential voltage signal delays between common electrodes.
Innovation Solution
A liquid crystal display design where the common electrode and passivation layer have matching cutouts, allowing for simultaneous formation using a single photomask, and a connection portion with a low resistance metal to prevent signal delays, including a common voltage line that extends parallel to the gate or data lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If two field generating electrodes (pixel electrode and common electrode) are formed on one display panel, then side visibility is improved, but manufacturing cost increases due to requiring different photomasks for each electrode
Solution Approach 1:
The patent merges the formation of the common electrode and passivation layer into a single photomask process. The common electrode pattern and passivation layer pattern are combined into one photomask design, allowing both structures to be formed simultaneously during the same photolithography step. This eliminates the need for separate photomasks for each electrode type, thereby reducing manufacturing cost while maintaining the wide viewing angle benefit of having two field generating electrodes on one panel
2Stability of the object's composition
If common electrodes are connected to each other to maintain voltage, then voltage stability is improved, but signal delay occurs in the common electrode
Solution Approach 1:
The patent applies local quality by differentiating the material properties in different regions of the common electrode structure. The common electrode is formed with a two-layer structure: a base layer (e.g., ITO) providing electrical conductivity and a upper layer (e.g., Mo, Al, or Cu) providing low resistance. This local variation in material quality reduces overall resistance and minimizes signal delay while maintaining voltage stability across connected common electrodes
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 reduces manufacturing costs and prevents signal delays in the common electrode while forming two field generating electrodes on one panel, enhancing efficiency and performance.
Implementation Method 1
an upper connection portion disposed on the lower connection portion that includes a low resistance metal
Implementation Method 2
the common electrode and passivation layer have matching cutouts, allowing for simultaneous formation using a single photomask
Data Source
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AI summary
A fringe-field switching liquid crystal display (FFS-LCD) includes a plurality of pixel electrodes (191) and a common electrode (270), disposed on a first substrate (110) so as to overlap each other with a passivation layer (180y) interposed therebetween, and a connection portion (27) disposed between a common voltage applying unit and the common electrode (270). The common electrode (270) has a plurality of first cut-outs or slits (271); in order to reduce the number of photolithographic masks required to fabricate the display, the passivation layer (180y) is manufactured by using the same mask employed to form the common electrode (270) and thus has a plurality of second cut-outs or slits (181); the first cut-outs (271) and the second cut-outs (181) have the same planar shape and are located at corresponding positions in the display. The connection portion (27) includes a lower connection layer (27p) formed in the same layer as the common electrode (270) and an upper connection layer (27q) disposed on the lower connection layer and including a low resistance metal; this structure minimises signal delays in the connection portion (27).