Light Blocking Film Placement in LCD TFTs
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Solution Overview
Problem
The challenge is to miniaturize the gate line driving circuit in liquid crystal display devices while ensuring that thin film transistors reliably react to signals, as existing configurations with light blocking films can impair transistor response.
Innovation Solution
The solution involves a liquid crystal display device design where a light blocking film is strategically placed under the gate electrode and semiconductor film, with electrical connections through insulating layers, allowing for miniaturization and improved signal response by using a metal film that overlaps the semiconductor and gate electrode, and is connected to the source electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light blocking film is provided under the gate electrode to prevent light-induced leakage current, then the reliability of the thin film transistor is improved, but the device complexity increases and the frame region cannot be narrowed
Solution Approach 1:
The patent merges the light blocking film with existing electrode structures by electrically connecting the light blocking film to the source electrode. This integration reduces the number of independent components and simplifies the overall device structure while maintaining the light blocking function that prevents leakage current.
Solution Approach 2:
The light blocking film is designed to serve multiple functions: it blocks light to prevent leakage current, and simultaneously acts as an electrode component by being electrically connected to the source electrode. This multi-functionality reduces device complexity by eliminating the need for separate light blocking structures.
2Productivity
If the frame region is narrowed to miniaturize the liquid crystal display device, then the productivity is improved, but the gate line driving circuit cannot be properly formed
Solution Approach 1:
The patent utilizes vertical layering to accommodate the gate line driving circuit within the frame region. By stacking functional layers (including the light blocking film connected to source electrodes), the design fits more functionality into a reduced horizontal area, enabling miniaturization while maintaining circuit functionality.
3Object-affected harmful factors
If a light blocking film is provided under the gate electrode, then light-induced leakage current is prevented, but the thin film transistor response to gate electrode signal deteriorates
Solution Approach 1:
The patent introduces an insulating film as an intermediary layer between the gate electrode and the light blocking film. This insulating layer mediates the interaction between the gate electrode and the light blocking film, preventing direct contact that would cause signal leakage while still allowing the light blocking function to operate effectively.
4Reliability
If an insulating film is provided between the gate electrode and the light blocking film, then the thin film transistor signal response is improved, but the device complexity increases
Solution Approach 1:
The insulating film is integrated into the existing multi-layer structure of the thin film transistor. Rather than being an additional separate component, it is incorporated as part of the gate electrode assembly, combining insulation functionality with the existing structural layers to minimize overall device complexity.
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 enables the miniaturization of the gate line driving circuit and enhances the reliability of thin film transistors' response to gate electrode signals, reducing parasitic capacitors and improving switching speed.
Implementation Method 1
a light blocking film may be provided under a gate electrode. The light blocking film is disposed to prevent light from the backlight from entering the semiconductor film
Data Source
AI summary
A liquid crystal display device is provided with a thin film transistor which includes a gate electrode film that is provided in a first electrode layer located over a first insulating layer, a semiconductor film that is disposed over the gate electrode film via a second insulating layer, a drain electrode and a source electrode that are provided in a second electrode layer located over the semiconductor film and are in contact with an upper surface of the semiconductor film, and a light blocking film that is disposed under the first insulating layer. At least a part thereof overlaps the semiconductor film and the gate electrode film in a plan view. One of the drain electrode and the source electrode is connected to a gate line, and the light blocking film is electrically connected to the source electrode.