Piezoelectric Switch Unit for Leakage-Free Display Panel Driving

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Solution Overview

Problem

Current display technologies rely on semiconductor TFTs, which are limited by carrier mobility and stability issues due to light and temperature sensitivity, leading to poor switching performance and leakage currents, affecting display quality.

Innovation Solution

A switch unit utilizing a piezoelectric material layer to form an inverse piezoelectric transistor (IPZT) without a semiconductor active layer, where the piezoelectric material's thickness changes under an electric field to control electrical connections between electrodes, enabling stable on and off states and avoiding leakage currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If semiconductor TFTs are used in display technology, then the display can be manufactured with mature technology and high yield, but the switching performance is poor and leakage currents occur due to limitations in carrier mobility and stability

Engineering Contradiction:
Improveswitching performanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the semiconductor-based electrical switching mechanism with a piezoelectric mechanical deformation mechanism. The piezoelectric layer deforms under electric field to mechanically open/close the capacitor, eliminating reliance on semiconductor carrier mobility and achieving complete off-state with zero leakage current.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a composite structure combining piezoelectric material layer with traditional display components (electrodes, capacitor, OLED). This composite approach integrates the advantages of piezoelectric materials (high stability, complete switching) with existing display manufacturing processes and structures.

Inventive Principle:
Principle #40Composite materials

2Reliability

If semiconductor TFTs are used to control pixel capacitors, then the display structure can be maintained, but leakage currents affect display quality due to light and temperature sensitivity

Engineering Contradiction:
ImprovestabilityVSAvoidleakage current
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the semiconductor-based electrical switching mechanism with a piezoelectric mechanical deformation mechanism. The piezoelectric layer deforms under electric field to mechanically open/close the capacitor, eliminating reliance on semiconductor carrier mobility and achieving complete off-state with zero leakage current.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the semiconductor active layer from the transistor structure, replacing it with a piezoelectric-based mechanism. This extraction eliminates the source of light and temperature sensitivity inherent in semiconductor materials, achieving immunity to these environmental factors.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If inverse piezoelectric transistor is used without semiconductor active layer, then switching performance and stability are improved with rapid charge and discharge, but the device structure becomes more complex

Engineering Contradiction:
Improveswitching performanceVSAvoiddevice structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The piezoelectric layer serves multiple functions simultaneously: it acts as the switching element, the capacitor dielectric, and the actuator for mechanical deformation. This multi-functionality reduces the need for separate components and simplifies the overall device structure despite the advanced switching mechanism.

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

Solution Approach 2:

The patent merges the piezoelectric layer with the capacitor structure, where the piezoelectric material serves as both the switching element and the capacitor dielectric. This merging reduces the number of discrete components and simplifies fabrication while achieving superior switching performance.

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

The IPZT solution provides improved switching performance and stability by eliminating the limitations of semiconductor TFTs, achieving rapid charge and discharge while ensuring a completely off state and reducing leakage currents, thereby enhancing display quality.

Implementation Method 1

A switch unit utilizing a piezoelectric material layer to form an inverse piezoelectric transistor (IPZT) without a semiconductor active layer, where the piezoelectric material's thickness changes under an electric field to control electrical connections between electrodes

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3688524B1Switch unit and display panel
Publication Date: 2023.10.04 BOE TECHNOLOGY GROUP CO LTD
  • EP3688524B1 patent drawingFigure 1
  • EP3688524B1 patent drawingFigure 2
  • EP3688524B1 patent drawingFigure 3

AI summary

A display panel may include a plurality of switch units. Each of the plurality of the switch units include a first electrode (1); a second electrode (2); a third electrode (3); a fourth electrode (4) opposite to the first electrode (1); a piezoelectric material layer (5) between the first electrode (1) and the fourth electrode (4); a connecting electrode (6) above the fourth electrode (4) and electrically insulated from the fourth electrode (4); and a driving transistor comprising a driving gate. The driving gate may be the third electrode (3). An orthogonal projection of the second electrode (2) and an orthogonal projection of the third electrode (3) on a plane of the connecting electrode (6) may overlap the connecting electrode (6) respectively.