Stacked Electrode Capacitor Structure for Small-Pixel LCDs
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Solution Overview
Problem
As liquid crystal display devices are downsized, forming a sufficient capacitor in each pixel becomes difficult due to the reduction in pixel electrode area, which affects the display quality and definition.
Innovation Solution
The implementation of a stacked electrode structure with varying insulating film thicknesses and strategic connection of electrodes to a potential supply line outside the display area, ensuring sufficient capacitor formation without reducing the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pixel electrode area is reduced to downsize the liquid crystal display device, then the device size is reduced, but the capacitor formation in each pixel becomes insufficient
Solution Approach 1:
The patent extends the capacitor electrode structure from the pixel region into the non-display area, utilizing the third dimension (spatial extension beyond pixel boundaries) to increase capacitance without reducing pixel electrode area. The potential supply line is positioned in the non-display area, allowing capacitor electrodes to overlap across the insulating film in this extended region.
Solution Approach 2:
The non-display area is utilized for dual purposes: it serves as a region for routing potential supply lines and simultaneously as a space for forming capacitor structures. This multi-functional use of the non-display area allows the device to maintain compact pixel regions while ensuring sufficient capacitance.
2Volume of moving object
If the pixel electrode area is reduced to downsize the liquid crystal display device, then the device size is reduced, but the aperture ratio is compromised
Solution Approach 1:
The capacitor structure is formed by extending electrodes into the non-display area along the planar dimension, utilizing space outside the pixel array. This allows capacitance enhancement without encroaching on the pixel electrode area or aperture ratio within the display region.
Solution Approach 2:
The device is divided into distinct functional regions: the display area containing pixel electrodes and the non-display area containing potential supply lines and capacitor structures. This spatial segmentation allows independent optimization of display quality and electrical performance without mutual interference.
3Reliability
If the insulating film thickness is increased to improve capacitor formation, then the capacitance is improved, but the gas discharge issue increases
Solution Approach 1:
The insulating film exhibits varying thickness characteristics at different locations: it is thicker in regions where capacitor electrodes overlap to provide sufficient capacitance, and thinner or absent in other regions to prevent gas discharge. This localized variation in insulating film properties optimizes both capacitor formation and electrical stability.
Solution Approach 2:
The insulating film thickness parameter is dynamically adjusted across different spatial regions of the device. By changing the thickness parameter locally rather than uniformly, the patent achieves sufficient capacitance where needed while maintaining electrical stability and preventing gas discharge in critical regions.
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 configuration maintains high definition and display quality by ensuring adequate capacitor formation, even with reduced pixel electrode sizes, and reduces capacitance dispersion and gas discharge issues.
Implementation Method 1
a first insulating film provided on the first electrode and having a first thickness, a second insulating film provided on the second electrode and having a second thickness
Implementation Method 2
a common electrode and a pixel electrode, which oppose each other while interposing an insulating layer, form a capacitor to holding the potential applied to a liquid crystal layer
Data Source
AI summary
According to one embodiment, a display device includes a substrate, a switching element provided on the substrate and including a relay electrode, a first electrode provided further away from the substrate than the switching element, a first insulating film provided on the first electrode and having a first thickness, a second electrode provided on the first insulating film, a second insulating film provided on the second electrode and having a second thickness and a third electrode provided on the second insulating film and supplied with a same potential as that of the first electrode. The second thickness is greater than the first thickness.