Multi-Layer Electrode Reflectance Reduction for IPS LCD Chuck Blot
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Solution Overview
Problem
In-plane switching (IPS) mode liquid crystal display (LCD) devices face issues with 'chuck blot' phenomena due to external light reflection during the photolithography process, leading to non-uniform light exposure and resulting in critical dimension deficiencies and reduced contrast ratios.
Innovation Solution
The implementation of a multi-layer structure for the common and pixel electrodes, including a reflectance reducing layer and a conductor layer, which prevents external light reflection and ensures uniform exposure, thereby preventing the 'chuck blot' and enhancing the contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductor is used for common and pixel electrodes to enhance aperture ratio and luminance, then aperture ratio and luminance are improved, but contrast ratio deteriorates because complete black luminance cannot be obtained
Solution Approach 1:
The patent applies composite materials by combining a transparent conductor layer (such as ITO) with a reflectance reducing layer (such as black resin or opaque metal oxide). This composite structure allows the electrode to maintain transparency for light transmission while the reflectance reducing layer absorbs stray light to prevent reflection, thereby simultaneously achieving high luminance through the transparent conductor and high contrast ratio through the light-absorbing properties of the reflectance reducing layer.
2Manufacturing precision
If external light reflection is reduced by using a reflectance reducing layer, then chuck blot phenomenon is prevented and manufacturing precision is improved, but device complexity increases due to multi-layer structure
Solution Approach 1:
The patent uses composite materials by integrating a reflectance reducing layer with the transparent conductor layer to form a multi-layer electrode structure. This composite structure prevents external light reflection during fabrication, ensuring uniform photoresist exposure and consistent electrode width across the substrate, thereby improving manufacturing precision while the added layer is managed through standard deposition processes.
3Reliability
If a multi-layer structure with reflectance reducing layer is implemented, then light reflection is minimized and chuck blot is prevented, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the reflectance reducing layer on the transparent conductor layer before performing photolithography patterning. This preliminary step ensures that external light reflection is minimized during the subsequent photoresist exposure process, preventing chuck blot phenomenon and ensuring uniform electrode width. The reflectance reducing layer is prepared in advance to create optimal conditions for the critical patterning step.
4Area of stationary object
If transparent conductor is used for electrodes, then aperture ratio is enhanced, but contrast ratio deteriorates due to light leakage in normal black mode
Solution Approach 1:
The patent employs composite materials by combining a transparent conductor layer with a reflectance reducing layer to create an electrode structure that simultaneously achieves high aperture ratio and high contrast ratio. The transparent conductor layer maintains high light transmittance for large aperture ratio, while the reflectance reducing layer absorbs stray light to prevent light leakage in normal black mode, thereby achieving complete black luminance and high contrast 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 prevents the 'chuck blot' phenomenon and improves the contrast ratio of the IPS mode LCD devices by reducing light reflection and ensuring consistent electrode widths, resulting in better aperture ratios and luminance.
Implementation Method 1
at least one of the common electrode and the pixel electrode includes a multi-layer having a conductor layer and a reflectance reducing layer
Data Source
AI summary
An in-plane switching mode liquid crystal display device includes first and second substrates facing each other, a gate line and a data line arranged on the first substrate crossing each other and defining a pixel region, a switching device at a crossing of the gate line and the data line, a common electrode and a pixel electrode alternately disposed in the pixel region, at least one of the common electrode and the pixel electrode including a multi-layer having a conductor layer and a reflectance reducing layer, and a liquid crystal layer formed between the first and second substrates.