TFD LCD Aperture Ratio via Integrated MIM Diodes
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Solution Overview
Problem
Current thin film diode (TFD) liquid crystal display (LCD) devices face issues with asymmetric current-voltage diagrams, remnant shades, and inhomogeneous gray scales, which reduce pixel aperture due to the occupation of space by four MIM diodes, complicating the manufacturing process and lowering yield.
Innovation Solution
Designing four back-to-back diodes within the selecting lines on a substrate to increase pixel aperture, while maintaining a simple process and high yield, by forming a transparent conductive layer, semiconductor insulation layer, and metal layers to create MIM diodes within the scanning lines, allowing for a larger pixel electrode area without occupying additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four MIM diodes are used to improve current-voltage symmetry and eliminate remnant shade, then driving circuit performance is improved, but pixel aperture is reduced
Solution Approach 1:
The patent combines the functions of the four MIM diodes into a single integrated structure located at the corner of the pixel electrode. Instead of distributing four separate diodes across the pixel area, they are merged into one compact unit that occupies minimal space while maintaining the required electrical functionality for symmetric current-voltage characteristics and remnant shade elimination.
Solution Approach 2:
The patent relocates the MIM diodes from occupying planar space within the pixel electrode to being positioned at the corner region, effectively utilizing the vertical and lateral dimensions more efficiently. This dimensional reorganization allows the diodes to be embedded in the corner without significantly reducing the active pixel aperture area.
2Ease of operation
If TFT is used to control liquid crystal alignment, then active driving is achieved, but fabrication process becomes complicated
Solution Approach 1:
The patent extracts the driving function from the complex TFT structure and implements it using simpler MIM diodes. By removing the transistor component and using only diode-based switching, the fabrication process is simplified while maintaining active driving capability. This extraction of the essential driving function eliminates the need for complex photolithographic processes required for TFT fabrication.
Solution Approach 2:
The patent uses simpler MIM diode structures instead of complex TFTs, effectively replacing expensive and complex fabrication processes with cheaper and simpler ones. The MIM diodes can be fabricated with fewer photolithographic steps, reducing manufacturing complexity and cost while still achieving the required active driving functionality for liquid crystal control.
Data Source
AI summary
Metal-Insulator-Metal (MIM) diodes in back-to-back thin film diode (TFD) liquid crystal display (LCD) device are formed on dual selective lines respectively. A transparent conductive layer on a first substrate comprises a pixel electrode, a first bottom layer, a second bottom layer, a third bottom layer, and a fourth bottom layer. A semiconductor insulator layer with a first contact hole on the first bottom layer and a second contact hole on the third bottom layer covers the first substrate and the transparent conductive layer. A metal conductive layer comprises a first selective line, a second selective line, a first top layer, and a second top layer, wherein an overlapped region between the first bottom layer and the first top layer is a first MIM diode, an overlapped region between the second bottom layer and the first top layer is a second MIM diode, an overlapped region between the third bottom layer and the second top layer is a third MIM diode, and an overlapped region between the fourth bottom layer and the second top layer is a fourth MIM diode. The first selective line electrically connects to the first bottom layer via the first contact hole, and the second selective line electrically connects to the third bottom layer via the first contact hole. The first and second top layers respectively isolated to the first and second selective lines are in the conformation of the first and second selective lines respectively.