Dummy Poly-Silicon Layer for Electrostatic Discharge in LCD
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Solution Overview
Problem
The increasing demand for high definition and high aperture ratio in liquid crystal display devices makes it challenging to effectively manage electrostatic discharge, which can damage wirings and switching elements during manufacturing, particularly due to the limited space for arranging dummy poly-silicon semiconductor layers.
Innovation Solution
A liquid crystal display device structure is implemented with a first and second semiconductor layer, where the second semiconductor layer acts as a dummy pattern outside the active area to control electrostatic discharge by distributing electric charges away from the active area, using a specific capacitance distribution ratio to guide charges outside the active area and prevent breakdown between the semiconductor layers and gate lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy poly-silicon semiconductor layer is arranged in each pixel to control electrostatic discharge, then electrostatic protection is improved, but the aperture ratio and manufacturing complexity deteriorate due to space occupation
Solution Approach 1:
The patent extracts the dummy poly-silicon semiconductor layer from the active pixel area and relocates it to the non-active area. This separation removes the electrostatic protection function from the space-constrained pixel region while maintaining its protective capability in the larger non-active area, thereby resolving the contradiction between electrostatic protection and aperture ratio.
Solution Approach 2:
The dummy poly-silicon semiconductor layer in the non-active area serves multiple functions: it provides electrostatic discharge protection for the active area, acts as a charge distribution structure, and utilizes otherwise wasted space. This multi-functionality achieves effective electrostatic protection without compromising the aperture ratio.
2Reliability
If a dummy poly-silicon semiconductor layer is arranged in each pixel to control electrostatic discharge, then electrostatic protection is improved, but device complexity increases due to additional structure requirements
Solution Approach 1:
The patent merges the dummy poly-silicon semiconductor layer with the existing non-active area structures, combining electrostatic protection functionality with the charge distribution and grounding infrastructure already present in the non-active region. This integration avoids adding separate complex protection structures while maintaining effective electrostatic discharge control.
3Area of stationary object
If the dummy poly-silicon semiconductor layer is removed from the active area to improve aperture ratio, then aperture ratio is improved, but electrostatic protection capability deteriorates
Solution Approach 1:
The patent transitions the dummy poly-silicon semiconductor layer from a two-dimensional arrangement within the active pixel area to a configuration in the non-active area, utilizing the additional spatial dimension of the non-active region. This dimensional relocation maintains electrostatic protection effectiveness while freeing up space in the active area for improved aperture ratio.
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 solution effectively controls electrostatic discharge destruction, preventing defects and disconnections in the active area, thereby enhancing manufacturing yield and reducing display defects, while maintaining the high definition and aperture ratio requirements.
Implementation Method 1
capacitance formed between the poly-silicon semiconductor layer and the table is set to Ca, capacitance formed between the poly-silicon semiconductor layer and the gate electrode line through the gate insulating film is set to Cb
Implementation Method 2
the measure against electrostatic is indispensable. For example, there is a possibility that various wirings in an active area, a switching element, etc., are damaged with static electricity generated in the manufacturing process
Data Source
AI summary
A first semiconductor layer is formed in the shape of an island in an active area displaying images on an array substrate. A second semiconductor layer is formed in the shape of an island outside the active area. A first insulating film covers the first and second semiconductor layers. A gate line is formed on the first insulating film and extends in a first direction. The gate line includes a gate electrode crossing the first semiconductor layer and a crossing portion crossing the second semiconductor layer. A second insulating film covers the gate line. A source line is formed on the second insulating film and extends in a second direction. The source line includes a source electrode contacting with the first semiconductor layer. A drain electrode is formed on the second insulating film apart from the source line and contacting with the first semiconductor layer.