IPS Liquid Crystal Display Capacitive Electrode Voltage Stability

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Solution Overview

Problem

Conventional IPS liquid crystal display devices face challenges in reducing manufacturing costs and increasing added capacitance, leading to variations in pixel voltage due to gate voltage fluctuations, which affects the visibility angle characteristic and manufacturing efficiency.

Innovation Solution

The implementation of a capacitive electrode formed on the gate insulating film and under the inorganic passivation film, opposite to the pixel electrode, to increase added capacitance and reduce pixel voltage shifts, while maintaining a reduced number of layers and photolithographic processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the number of layers and photolithographic processes is reduced to lower manufacturing cost, then manufacturing cost decreases, but added capacitance cannot be increased sufficiently, leading to pixel voltage variation

Engineering Contradiction:

Improvemanufacturing costVSAvoidpixel voltage stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent combines the common electrode and capacitive electrode into a single integrated structure. The capacitive electrode is formed as part of the common electrode layer, eliminating the need for separate capacitive electrode layers while still providing the necessary capacitance compensation function. This merging reduces the total number of layers and photolithographic processes while maintaining pixel voltage stability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The common electrode serves dual functions: as the common electrode for the IPS display mode and as the capacitive electrode for voltage compensation. By making the common electrode extend into the pixel region and function as both electrodes, the patent achieves multi-functionality that reduces layer count while maintaining both display performance and voltage stability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If added capacitance is increased to reduce pixel voltage variation, then pixel voltage stability improves, but the number of layers and photolithographic processes increases, raising manufacturing cost

Engineering Contradiction:

Improvepixel voltage stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the common electrode and capacitive electrode into a single integrated structure. The capacitive electrode is formed as part of the common electrode layer, eliminating the need for separate capacitive electrode layers while still providing the necessary capacitance compensation function. This merging reduces the total number of layers and photolithographic processes while maintaining pixel voltage stability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes the planar dimension by extending the common electrode into the pixel region where it functions as the capacitive electrode. Instead of adding layers in the vertical dimension, the solution extends functionality in the horizontal plane, allowing the same layer to serve multiple purposes without increasing layer count.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If a top gate type TFT structure is used with common electrode opposing n+ region, then added capacitance is increased, but the number of layers and structural complexity increases

Engineering Contradiction:

Improveadded capacitanceVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

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 approach enhances the visibility angle characteristic by increasing added capacitance, thereby stabilizing pixel voltage and reducing manufacturing costs through a more efficient pixel structure with fewer layers and processes.

Implementation Method 1

a capacitive electrode 108 is formed on the gate insulating film 103. The capacitive electrode 108 forms added capacitance 150 with the pixel electrode 101

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The liquid crystal molecule is rotated with an electric field which occurs between the pixel electrode and the common electrode

Methodology Applied

Scientific EffectElectric Field: Electric Field

Data Source

PatentUS9329444B2Liquid crystal display device

Publication Date: 2016.05.03 MAGNOLIA WHITE CORP

AI summary

A liquid crystal display device includes a TFT substrate, an opposite substrate, and a liquid crystal between the TFT substrate and the opposite substrate. In the TFT substrate, there are formed in the following order, a first pixel electrode and a second pixel electrode, a first scan line and a second scan line which extend in a first direction and are arranged in a second direction, a first insulating film, a first video signal line and a second video signal line which extend in the second direction and are arranged in the first direction, a second insulating film, and a common electrode. The first pixel electrode and the second pixel electrode are formed in an area surrounded by the first scan line, the second scan line, the first video signal line and the second video signal line.