Liquid Crystal Display Storage Capacitor Vertical Stacking
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Solution Overview
Problem
Liquid crystal display devices face challenges in securing a sufficient storage capacitor when the area available for its disposition is small, particularly due to imbalances in the layout of TFT substrates caused by shared memories or spacers, leading to incorrect gradation display and increased power consumption.
Innovation Solution
The solution involves creating a storage capacitor in a layer below the pixel electrode with a shield layer interposed between the pixel electrode and the storage capacitor, or by laminating counter electrodes to increase capacitance, and adjusting the capacitance between the pixel electrode and the scanning line to prevent direct-current electric field application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage capacitor is disposed in the available area on the TFT substrate, then the capacitance value is sufficient, but the layout becomes unbalanced and causes incorrect gradation display
Solution Approach 1:
The patent moves the storage capacitor from the planar layout on the TFT substrate to a three-dimensional structure by forming it in a layer below the pixel electrode. This vertical stacking allows the storage capacitor to occupy space in the Z-direction rather than competing for XY-plane area, resolving the layout balance issue while maintaining sufficient capacitance value.
Solution Approach 2:
The storage capacitor is nested within the pixel structure by forming it in a layer below the pixel electrode. The capacitor occupies the same horizontal footprint as the pixel but extends downward in the layer structure, effectively nesting the storage function within the pixel's vertical space without disrupting the planar layout balance.
2Area of stationary object
If the storage capacitor is disposed in a layer below the pixel electrode, then the layout balance is maintained, but the area for the storage capacitor becomes insufficient
Solution Approach 1:
By transitioning to three-dimensional stacking, the storage capacitor achieves sufficient capacitance through increased vertical layering rather than expanding horizontal area. The capacitor is formed in lower layers beneath the pixel electrode, utilizing the Z-dimension to provide adequate capacitance while maintaining planar layout balance.
3Reliability
If the storage capacitor is created by laminating counter electrodes in three layers or more, then the capacitance is sufficient in small areas, but the device complexity increases
Solution Approach 1:
The lower layers that form the storage capacitor are also utilized as counter electrodes for the liquid crystal cell. By making these layers serve dual purposes - as both storage capacitor electrodes and liquid crystal counter electrodes - the patent achieves sufficient capacitance without adding dedicated complex structures, thereby controlling device complexity.
4Reliability
If the capacitance between pixel electrode and scanning line is increased, then direct-current electric field application is prevented, but the power consumption increases
Solution Approach 1:
The patent establishes the capacitance between the pixel electrode and scanning line as a preliminary protective measure during the display operation. By pre-configuring this capacitance relationship in the device structure, the system prevents direct-current electric field application to the liquid crystal from the outset, avoiding cumulative damage while managing power consumption through optimized capacitance values.
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 approach ensures a necessary storage capacitor is secured even in constrained areas, preventing direct-current electric field application and maintaining accurate gradation display while reducing power consumption.
Implementation Method 1
creating the storage capacitor of an adjacent liquid crystal cell in a layer below a pixel electrode with a shield layer interposed between the storage capacitor and the pixel electrode
Implementation Method 2
a storage capacitor Cs for supplying a lack of capacitance of each liquid crystal cell
Implementation Method 3
sandwiching a liquid crystal layer between a TFT substrate having the TFT disposed thereon and a CF (Color Filter) substrate
Data Source
AI summary
The present invention provides a liquid crystal display device for displaying a desired image by a display unit, the display unit being formed by sandwiching a liquid crystal layer between a thin film transistor substrate and a CF substrate and arranging liquid crystal cells formed by the liquid crystal layer in a form of a matrix, wherein the thin film transistor substrate is created by disposing at least a transistor used to drive a liquid crystal cell and a pixel electrode of the liquid crystal cell on an insulating substrate, and a part or all of a storage capacitor of an adjacent liquid crystal cell is created in a layer below the pixel electrode with a shield layer interposed between the pixel electrode and the storage capacitor.