IPS LCD Aperture Ratio via Storage Capacitor Merging

Solution Overview

Problem

In-plane switching (IPS) mode liquid crystal display (LCD) devices have a reduced aperture ratio and luminance due to the additional light blocking regions created by common and pixel electrodes, which limits their viewing angle and brightness compared to TN mode LCDs.

Innovation Solution

The IPS mode LCD device incorporates a storage capacitor at the lower end of at least one electrode, overlapping with the light blocking region, to minimize the area occupied by the light blocking region and enhance the aperture ratio, while maintaining the in-plane electric field generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If common and pixel electrodes are added to generate in-plane electric field, then viewing angle characteristics are improved, but aperture ratio and luminance are reduced

Engineering Contradiction:

Improveviewing angle characteristicsVSAvoidaperture ratio

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The storage capacitor electrode is merged with the common electrode, forming a unified structure where the common electrode extends into the pixel electrode region. This integration allows the storage capacitor function to be achieved without adding separate electrode structures, thereby minimizing the area occupied by light-blocking regions and improving aperture ratio while maintaining viewing angle characteristics

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The common electrode serves dual functions: generating the in-plane electric field for liquid crystal switching (providing wide viewing angle characteristics) and forming the storage capacitor structure. This multi-functionality eliminates the need for separate storage capacitor electrodes that would otherwise occupy additional area and reduce aperture ratio

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If storage capacitor is formed with separate electrode structure, then storage function is achieved, but light blocking region area increases

Engineering Contradiction:

Improvestorage functionVSAvoidlight blocking region area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The storage capacitor electrode is merged with the common electrode, forming a unified structure where the common electrode extends into the pixel electrode region. This integration allows the storage capacitor function to be achieved without adding separate electrode structures, thereby minimizing the area occupied by light-blocking regions and improving aperture ratio while maintaining viewing angle characteristics

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The common electrode serves dual functions: generating the in-plane electric field for liquid crystal switching (providing wide viewing angle characteristics) and forming the storage capacitor structure. This multi-functionality eliminates the need for separate storage capacitor electrodes that would otherwise occupy additional area and reduce aperture ratio

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 increases the aperture ratio and luminance of the IPS mode LCD, improving viewing angles and reducing power consumption while maintaining the screen contrast ratio, even when using transparent conductors for electrodes.

Implementation Method 1

when a voltage is applied to an electrode, an in-plane electric field, namely, a field having a direction parallel to the substrate, is formed to align liquid crystal molecules horizontal to the substrate

Methodology Applied

Scientific EffectIn-plane electric field generation: Electric Field

Implementation Method 2

an in-plane electric field, namely, a field having a direction parallel to the substrate, is formed to align liquid crystal molecules horizontal to the substrate

Methodology Applied

Scientific EffectLiquid crystal alignment: Liquid Crystals

Implementation Method 3

at least one of the common and pixel electrodes has a first storage capacitor at its lower end

Methodology Applied

Scientific EffectCapacitance storage: Capacitance

Data Source

PatentUS7515237B2Liquid crystal display device with high aperture ratio having a metal layer and a storage electrode entirely overlapped with a common electrode

Publication Date: 2009.04.07 LG DISPLAY CO LTD

AI summary

Disclosed is an in-plane switching (IPS) mode liquid crystal display (LCD) device having an increased aperture ratio by overlapping a storage capacitor on a lower end of an electrode. The (IPS) mode liquid crystal display device (LCD) device includes first and second substrates; a gate line and a data line arranged horizontally and vertically to define a plurality of pixel regions on the first substrate; a switching device, having a gate electrode, a semiconductor layer and source and drain electrodes, at a crossing of the gate line and the data line; a passivation film on an entire surface of the first substrate including the switching device; a common electrode and a pixel electrode alternately disposed at an upper portion of the passivation film and generating an in-plane electric field, wherein at least one of the common and pixel electrodes has a first storage capacitor at its lower end; and a liquid crystal layer between the first and second substrates.