Liquid Crystal Display Pressure Sensing via Capacitance Detection

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Solution Overview

Problem

Current liquid crystal display technologies can only determine two-dimensional touch coordinates and lack the capability for three-dimensional pressure sensing, limiting their functionality and human-computer interaction.

Innovation Solution

A method and device that utilize a transparent electrode array in a liquid crystal display to detect capacitance values between the electrode and a support array, allowing for the determination of pressure values by calculating changes in capacitance, enabling three-dimensional pressure sensing and improved interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a touch panel is added on the liquid crystal display to enable touch location sensing, then two-dimensional touch coordinates can be determined, but three-dimensional pressure sensing capability is still lacking

Engineering Contradiction:
Improvetouch location sensingVSAvoidpressure sensing capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent extends the sensing capability from two-dimensional touch coordinates to three-dimensional pressure sensing by utilizing the liquid crystal layer as an additional sensing dimension. The liquid crystal layer's optical properties change in response to pressure, enabling the system to detect pressure values in addition to touch location, thus adding a third dimension to the sensing capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The liquid crystal display serves multiple functions: it acts as both the display medium and the pressure sensing element. By integrating the pressure sensing function into the liquid crystal layer, the system achieves multi-functionality without requiring separate pressure sensing hardware, thereby resolving the contradiction between maintaining simplicity and enhancing versatility.

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

2Measurement precision

If transparent electrodes are arranged in the liquid crystal layer for capacitance detection, then pressure values can be determined through capacitance changes, but the device complexity increases

Engineering Contradiction:
Improvepressure value detectionVSAvoidelectrode arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the transparent electrodes with the existing liquid crystal display structure, integrating the pressure sensing function into the display itself. The electrodes are arranged within the liquid crystal layer, merging the display and sensing functions into a single integrated structure, thereby reducing overall device complexity while enabling precise pressure detection.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The liquid crystal layer itself serves as the sensing medium, utilizing its inherent optical properties that change in response to pressure. This self-service approach eliminates the need for separate complex sensing mechanisms, as the liquid crystal material naturally responds to pressure changes through optical property variations that can be detected by the integrated electrodes.

Inventive Principle:
Principle #25Self-service

3Productivity

If capacitance detection is performed during the liquid crystal display operation, then real-time pressure sensing is achieved, but display performance may be affected

Engineering Contradiction:
Improvereal-time pressure sensingVSAvoiddisplay performance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements capacitance detection at specific intervals or during designated time windows within the display operation cycle. By using periodic action rather than continuous detection, the system achieves real-time pressure sensing capability while minimizing interference with the display's normal operation, thus maintaining display performance reliability.

Inventive Principle:
Principle #19Periodic action

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

Enables the detection of pressure values, enhancing functionality beyond traditional touch sensing and improving human-computer interaction by providing three-dimensional pressure sensing capabilities.

Implementation Method 1

detecting a capacitance value between the transparent electrode and a support array in the liquid crystal layer of the liquid crystal display

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3130985B1Method and device for detecting pressure in mobile terminal
Publication Date: 2021.08.25 XIAOMI INC
  • EP3130985B1 patent drawingFigure 1~2
  • EP3130985B1 patent drawingFigure 3~4
  • EP3130985B1 patent drawingFigure 5

AI summary

The present disclosure relates to a method and a device for detecting pressure in a mobile terminal. The method includes: detecting a capacitance value between the transparent electrode and a support array in the liquid crystal layer of the liquid crystal display; and determining a pressure value performed by an operating member on the liquid crystal display according to the capacitance value detected. With the technical solution of the present disclosure, the pressure value on the liquid crystal display is determined by detecting the capacitance value between the transparent electrode and the support array in the liquid crystal layer of the liquid crystal display, such that detecting a third dimension pressure sensing other than touch sensing in the liquid crystal display is realized, more functions may be realized according to the pressure value detected, and human-computer interaction is improved.