Multi-Layer Lead Line Routing for Display Devices
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Solution Overview
Problem
In display devices, the proximity of lead lines to the liquid crystal layer can result in unintended voltage application and parasitic capacitance, leading to deteriorated display quality and an increased picture-frame region due to the need for more space to arrange lead lines.
Innovation Solution
A display device with multiple layers of lead lines formed from different conductive layers, where the lowest conductive layer forms the switching elements, allowing for a more remote placement of lead lines from the liquid crystal layer and enabling a denser arrangement without overlapping, thus reducing the picture-frame region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If lead lines are arranged densely to reduce picture-frame region, then area of picture-frame region is reduced, but lead lines may be placed too close to liquid crystal layer causing unintended voltage application and parasitic capacitance
Solution Approach 1:
The patent applies dimensional change by stacking lead lines in multiple layers (first, second, and third lead lines on different insulating films) rather than arranging them only in the planar direction. This vertical stacking allows higher density connection while maintaining safe distances from the liquid crystal layer, thus reducing picture-frame region area without causing parasitic capacitance issues.
Solution Approach 2:
The patent introduces insulating films (first insulating film, second insulating film, and third insulating film) as intermediary layers between the lead lines and the liquid crystal layer. These insulating films act as mediators that electrically isolate the lead lines from the liquid crystal layer, preventing unintended voltage application and parasitic capacitance while allowing the lead lines to be positioned closer to the display region.
2Manufacturing precision
If number of signal lines is increased to enhance display resolution, then display resolution is improved, but number of lead lines increases requiring larger picture-frame region
Solution Approach 1:
The patent resolves this contradiction by utilizing vertical stacking of lead lines in multiple layers. This allows the number of lead lines to increase proportionally with display resolution without requiring proportional increases in picture-frame region area, as the vertical dimension provides additional routing capacity within the same planar footprint.
3Area of stationary object
If lead lines are placed closer to liquid crystal layer to reduce picture-frame region, then area of picture-frame region is reduced, but display quality deteriorates due to parasitic capacitance
Solution Approach 1:
The patent introduces multiple insulating films (first, second, and third insulating films) as intermediary barriers between the lead lines and the liquid crystal layer. These insulating films maintain electrical isolation even when lead lines are positioned close to the liquid crystal layer in the vertical stacking arrangement, thus preventing parasitic capacitance formation while enabling picture-frame region reduction.
Data Source
AI summary
A display device according to an aspect of the present invention includes a first substrate, a second substrate, a liquid crystal layer, a plurality of signal lines, a plurality of switching elements, a plurality of connection terminals, and a plurality of lead lines. The plurality of lead lines include: first lead lines formed of a first conductive layer; second lead lines formed of a second conductive layer provided on a first insulating film covering the first lead lines; and third lead lines formed of a third conductive layer provided on a second insulating film covering the second lead lines. Among a plurality of conductive layers forming the switching elements, the lowest conductive layer is formed of the second conductive layer.