Array Substrate With Top Gate Thin Film Transistor For Liquid Crystal Display

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Solution Overview

Problem

Existing liquid crystal display devices have a limited visual angle due to all liquid crystal molecules within a pixel unit having the same deflection angle, resulting from a single pixel electrode configuration.

Innovation Solution

The array substrate incorporates multiple pixel electrodes, where each first pixel electrode is connected to a first thin film transistor and the second pixel electrode to a second thin film transistor, with the first pixel electrode acting as a gate for a top gate thin film transistor, allowing for different voltage levels and deflection angles within the same pixel unit by varying the channel coverage and discharge rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single pixel electrode is used in each pixel unit, then the device complexity is reduced, but the visual angle is limited due to uniform deflection angle of liquid crystal molecules

Engineering Contradiction:
Improvepixel electrode configurationVSAvoidvisual angle
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The pixel unit is segmented into multiple pixel electrodes (first pixel electrode and second pixel electrode) instead of using a single electrode. Each pixel electrode is independently controlled by separate thin film transistors, enabling different voltage levels and deflection angles for liquid crystal molecules in different regions, thereby expanding the visual angle while maintaining manageable device complexity through modular segmentation.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If multiple pixel electrodes are used with different voltage levels, then the visual angle is increased, but the device complexity increases due to additional transistors and control circuits

Engineering Contradiction:
Improvevisual angleVSAvoidtransistor and electrode configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention merges the pixel electrode function with the thin film transistor gate structure. The first pixel electrode serves dual purposes: as a display electrode and as a gate for the first thin film transistor. This integration reduces the need for separate control structures, thereby increasing visual angle through multiple electrodes while minimizing the increase in device complexity through functional merging.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The first pixel electrode is designed to perform multiple functions: it acts as a display electrode for liquid crystal control and simultaneously serves as the gate electrode for the first thin film transistor. This multi-functionality reduces the overall component count and device complexity while enabling the multiple voltage levels needed for expanded visual angle.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the first pixel electrode covers the channel area, then voltage discharge control is improved for different deflection angles, but parasitic capacitance increases between the pixel electrode and channel

Engineering Contradiction:
Improvevoltage discharge controlVSAvoidparasitic capacitance
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The invention carefully controls the geometric parameters of the first pixel electrode, specifically its coverage area over the channel. By optimizing the extent of coverage, the design achieves sufficient voltage discharge control for creating different deflection angles while minimizing the overlapping area that would generate parasitic capacitance between the pixel electrode and the transistor channel.

Inventive Principle:
Principle #35Parameter changes

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 enables liquid crystal molecules within the same pixel unit to have multiple deflection angles, significantly increasing the visual angle of the liquid crystal display device.

Implementation Method 1

When the first pixel electrode discharges, carrier migration is generated within the gate of the corresponding top gate thin film transistor (i.e. the first pixel electrode) such that the channel between the source and the drain in the top gate thin film transistor is conducting

Methodology Applied
Scientific EffectCarrier migration: Conduction (electrical)

Implementation Method 2

The deflection angle of the liquid crystal molecules within the liquid crystal region to which the pixel unit corresponds can be controlled by means of an electric field formed between the pixel electrode and the common electrode

Methodology Applied
Scientific EffectElectric field: Electric Field

Data Source

PatentEP3306385B1Array substrate, liquid crystal display panel and liquid crystal display device
Publication Date: 2021.01.20 BOE TECHNOLOGY GROUP CO LTD
  • EP3306385B1 patent drawingFigure 1
  • EP3306385B1 patent drawingFigure 2
  • EP3306385B1 patent drawing

AI summary

The present disclosure relates to the field of display technologies, wherein it discloses an array substrate, a liquid crystal display panel and a liquid crystal display device for increasing the visual angle of the liquid crystal display device. The array substrate comprises a plurality of pixel units arranged in an array. At least one pixel unit comprises a first pixel electrode and a second pixel electrode. The first pixel electrode is connected with a first thin film transistor and the second pixel electrode is connected with a second thin film transistor; wherein a channel is provided between a source and a drain of the first thin film transistor, the projection of the first pixel electrode on the plane where the channel resides covers at least part of the channel, and the first pixel electrode and the source and drain of the first thin film transistor constitute a top gate thin film transistor. The liquid crystal display panel comprises the array substrate provided by the above technical solution. The liquid crystal display device comprises the liquid crystal display panel provided by the above technical solution. The array substrate, the liquid crystal display panel and the liquid crystal display device provided by the present disclosure are used in a liquid crystal display apparatus.