Capacitive Pressure Sensing in Touch Display Modules

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Solution Overview

Problem

Current 3D touch display devices with larger display modules have poor sensitivity in detecting pressure due to the mechanical strength requirements, which limits the deformation and thus the sensitivity of the pressure touch detection.

Innovation Solution

A touch display device design that includes a pressure sensing layer and a voltage reference layer arranged between the display panel and the back plate, forming a capacitance to detect pressure changes, with the pressure touch detection chip determining pressure values based on these changes, improving sensitivity and enabling lighter, thinner, and more integrated products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the display module size is increased to meet mechanical strength requirements, then the structural strength is improved, but the pressure touch sensitivity deteriorates

Engineering Contradiction:

Improvemechanical strengthVSAvoidpressure touch sensitivity

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The pressure sensing layer is integrated within the display module structure, merging the pressure detection function with the display structure. This allows the pressure sensing electrodes to be positioned close to the touch surface while maintaining overall structural strength, resolving the contradiction between size/strength and sensitivity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

A pressure sensing layer with sensing electrodes is introduced as an intermediary component between the touch surface and the pressure touch detection chip. This intermediary structure enables precise pressure detection through capacitance changes without requiring the entire display module to be flexible or deformable, thus maintaining structural strength while improving sensitivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the pressure touch unit is placed external to the display module, then the structural simplicity is improved, but the pressure detection sensitivity deteriorates

Engineering Contradiction:

Improvestructural simplicityVSAvoidpressure detection sensitivity

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If the display module size is increased, then the mechanical strength is improved, but the deformation capability under finger pressure deteriorates

Engineering Contradiction:

Improvemechanical strengthVSAvoiddeformation capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent replaces mechanical deformation detection with capacitance-based detection. Instead of relying on visible deformation of the display module under pressure, the system uses sensing electrodes that detect changes in capacitance caused by pressure-induced displacement of the touch surface. This substitution allows the display module to maintain its mechanical strength while still enabling precise pressure detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enhances pressure touch sensitivity by detecting deformation within the display module, allowing for more accurate and precise pressure detection compared to traditional methods where the pressure touch unit is external to the display module.

Implementation Method 1

The pressure sensing layer and the voltage reference layer are opposite to each other and arranged in different layers. The pressure touch detection chip is configured to determine a value of a pressure on the display panel according to a detected change of capacitance between the pressure sensing layer and the voltage reference layer.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11442570B2Touch display device

Publication Date: 2022.09.13 HEFEI BOE OPTOELECTRONIC TECH CO LTD

AI summary

A touch display device includes a display panel; a backlight that includes a back plate; a pressure touch detection chip; a pressure sensing layer and a voltage reference layer arranged between the display panel and the back plate, the pressure sensing layer and the voltage reference layer are opposite to each other and arranged in different layers. The pressure sensing layer includes a plurality of sensing electrodes arranged as an array, where each sensing electrode is electrically connected to the pressure touch detection chip through a lead wire. The voltage reference layer is configured to receive a stable reference voltage signal; and the pressure touch detection chip is configured to determine a value of a pressure on the display panel according to a detected change of capacitance between the pressure sensing layer and the voltage reference layer.