LCD Compensation Electrode Design for Ripple Reduction

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Solution Overview

Problem

Liquid crystal displays (LCDs) face increased manufacturing costs due to the need for different photomasks to form field generating electrodes and suffer from common voltage ripples caused by coupling between data lines and common electrodes, leading to display quality issues like flickering.

Innovation Solution

A liquid crystal display design that includes a compensation voltage line overlapping the data line, with the compensation electrode extending parallel to the data line and positioned between adjacent data lines, and a common electrode with cutouts to reduce coupling, allowing for the same layer formation and minimizing overlap areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If two field generating electrodes (pixel electrode and common electrode) are formed on one display panel to realize wider viewing angle, then lateral visibility is improved, but manufacturing cost increases due to requiring different photomasks

Engineering Contradiction:

Improveviewing angleVSAvoidmanufacturing cost

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The patent merges the formation process of the common electrode and pixel electrode by using the same photomask for both electrodes. The common electrode has cutouts that define both the common electrode regions and pixel electrode regions, allowing a single photomask to pattern both electrodes simultaneously, thereby reducing manufacturing complexity and cost while maintaining the dual-electrode structure for wide viewing angle

Inventive Principle:

Principle #5Merging (Combining)

2Area of stationary object

If data line and common electrode overlap each other to form the display structure, then electrode coverage is improved, but coupling between data line and common electrode generates common voltage ripple

Engineering Contradiction:

Improveelectrode coverageVSAvoidvoltage stability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces a compensation electrode as an intermediary element positioned between the data line and the common electrode. This compensation electrode acts as a mediator that compensates for the capacitive coupling effect between the data line and common electrode, preventing voltage ripple while allowing the data line and common electrode to maintain their overlapping positions for full coverage

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If common electrode and data line are positioned close together to maximize display area, then aperture ratio is improved, but coupling capacitance increases causing voltage ripple

Engineering Contradiction:

Improvedisplay areaVSAvoidcoupling capacitance

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful coupling capacitance effect into a beneficial compensation mechanism. By positioning the compensation electrode to overlap with the data line and connecting it to a compensation voltage source, the capacitive coupling between the data line and common electrode is transformed into a controlled compensation effect that eliminates voltage ripple while maintaining close spacing for maximum display area

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 design reduces manufacturing costs and prevents common voltage ripples, enhancing display quality by minimizing coupling between data lines and common electrodes, thus reducing flickering and improving overall performance.

Implementation Method 1

the data line and the common electrode overlap each other and couple such that a ripple of the common voltage may be generated

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

applying voltages to field-generating electrodes to generate an electric field in an LC layer that determines orientations of LC molecules therein to adjust polarization of incident light

Methodology Applied

Scientific EffectElectric field effect on liquid crystal orientation: Electric Field

Data Source

PatentUS11175545B2Liquid crystal display

Publication Date: 2021.11.16 SAMSUNG DISPLAY CO LTD

AI summary

A liquid crystal display according to an exemplary embodiment of the present disclosure includes: a gate line, a data line, and a compensation voltage line disposed on an insulation substrate; a first passivation layer disposed on the gate line, the data line, and the compensation voltage line; a pixel electrode connected to the gate line and the data line, and a compensation electrode connected to the compensation voltage line, disposed on the first passivation layer; and a common electrode formed on the first passivation layer, wherein the compensation electrode overlaps at least a portion of the data line, and the compensation voltage line is formed with the same layer as the data line.