LCD Light Shielding Layer Configuration for Leakage Current Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction of pixel size in liquid crystal display devices for compact and high-definition applications leads to a decrease in aperture ratio, requiring high-brightness backlights which cause leakage current and deteriorate the device characteristics, especially in head-up displays where light resistance of TFTs is essential.
Innovation Solution
A liquid crystal display device configuration that includes specific arrangements of light shielding layers, gate electrodes, semiconductor layers, and common electrodes to minimize light exposure and leakage current, with features such as longer light shielding layers, overlapping electrode configurations, and application of common voltage to the light shielding layers, which helps in reducing parasitic capacitance and improving operating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-brightness backlight is used to ensure display intensity, then aperture ratio is improved, but leakage current increases and device characteristics deteriorate
Solution Approach 1:
The light shielding layer is divided into multiple segments: a first light shielding layer extending in the first direction and a second light shielding layer extending in the second direction. This segmentation allows each layer to shield specific portions of the semiconductor layer from light, reducing overall light exposure and leakage current while maintaining the necessary aperture ratio for high-brightness backlight operation.
Solution Approach 2:
The first and second light shielding layers are positioned to overlap with the semiconductor layer in specific local areas. The first light shielding layer is arranged to overlap with one end of the semiconductor layer, while the second light shielding layer overlaps with the other end. This local quality approach provides targeted light shielding where leakage current is most problematic, without compromising the overall aperture ratio.
2Productivity
If pixel size is reduced for compact and high-definition display, then display density is improved, but aperture ratio decreases
Solution Approach 1:
The light shielding is achieved by extending light shielding layers in directions perpendicular to the pixel electrode arrangement. The first light shielding layer extends in the first direction (row direction) and the second light shielding layer extends in the second direction (column direction), creating a grid-like shielding pattern that effectively blocks light to the semiconductor layer without reducing the pixel aperture area.
Solution Approach 2:
The first and second light shielding layers are nested within the pixel structure, with the first light shielding layer positioned below the gate electrode and the second light shielding layer positioned below the semiconductor layer. This nested arrangement allows multiple shielding functions to be integrated within the existing pixel architecture without increasing overall pixel size.
3Reliability
If light shielding layers are extended to reduce leakage current, then light resistance is improved, but device complexity increases
Solution Approach 1:
The first light shielding layer and second light shielding layer are merged into a coordinated system where both layers work together to shield the semiconductor layer. The first light shielding layer extends in the first direction and the second light shielding layer extends in the second direction, creating a complementary shielding effect that reduces leakage current more effectively than either layer could alone, while the layers are designed to be integrated into the existing transistor fabrication process.
Data Source
AI summary
A liquid crystal display device includes: a liquid crystal layer sandwiched between a first substrate and a second substrate; a first light shielding layer that is provided on the first substrate; a first insulating layer provided on the first light shielding layer; a gate electrode that is provided on the first insulating layer; a second insulating layer provided on the gate electrode; a semiconductor layer that is provided on the second insulating layer, and is provided for each pixel; a source electrode and a drain electrode that partially overlap with the semiconductor layer; a pixel electrode that is provided on the second insulating layer; a third insulating layer provided on the semiconductor layer and the pixel electrode; and a common electrode that is provided on the third insulating layer, and includes a slit.