Touch Display Force Sensing via Piezo Sensor Array

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Solution Overview

Problem

Existing touch-sensitive electronic devices lack effective methods to distinguish between inadvertent touches and intentional inputs on their displays, particularly in determining the force and location of multiple simultaneous touches, which affects user interaction and feedback.

Innovation Solution

The electronic device employs a combination of touch-sensitive displays and force sensors to detect and differentiate between touches by determining applied force values and locations, using piezo actuators for tactile feedback and a method that involves force and torque balancing equations to identify intentional inputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple force sensors are used to detect touch force, then measurement precision of touch force is improved, but device complexity increases

Engineering Contradiction:
Improvetouch force measurement precisionVSAvoidsensor array complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The touch detection function is segmented into multiple independent force sensors arranged in an array across the touch-sensitive display. Each sensor independently measures force at its location, enabling precise determination of both magnitude and location of touches through distributed measurement points.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solution transitions from single-point force measurement to multi-point spatial distribution measurement. By arranging sensors in an array across the display surface, the system adds spatial dimensionality to force detection, enabling differentiation of multiple simultaneous touches through their distinct locations.

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

2Adaptability or versatility

If force sensors are integrated into the touch-sensitive display, then touch force detection capability is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvetouch force detection capabilityVSAvoidsensor integration precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The force sensing capability is merged directly into the touch-sensitive display structure by integrating the sensor array within the display assembly. This combination eliminates the need for separate force sensing components and simplifies the overall system architecture while maintaining detection versatility.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The touch-sensitive display serves multiple functions: it displays visual information, detects touch location through the touch-sensitive component, and measures touch force through the integrated force sensors. This multi-functionality reduces the need for additional specialized components.

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

3Ease of operation

If tactile feedback mechanism is added, then user interaction quality is improved, but device complexity increases

Engineering Contradiction:
Improveuser interaction qualityVSAvoidfeedback mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

A tactile feedback mechanism is implemented to provide force feedback to the user during interaction with the touch-sensitive display. This feedback loop enhances user interaction quality by providing sensory confirmation of touch actions and improving the perceived responsiveness of the device.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The tactile feedback mechanism serves the dual purpose of both actuation and sensing. The same mechanical structure that provides tactile feedback to the user also serves as the sensing element for detecting touch force, eliminating the need for completely separate actuation and sensing systems.

Inventive Principle:
Principle #25Self-service

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 approach enhances user interaction by providing accurate differentiation between inadvertent and intentional touches, allowing for precise selection of features and improved tactile feedback, thereby enhancing the usability of portable electronic devices with touch-sensitive displays.

Implementation Method 1

determining a first force value by a first sensor and a second force value by a second sensor

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP2390766B1Electronic device including touch-sensitive display and method of controlling same
Publication Date: 2013.09.25 BLACKBERRY LTD
  • EP2390766B1 patent drawingFigure 1
  • EP2390766B1 patent drawingFigure 2~3
  • EP2390766B1 patent drawingFigure 4

AI summary

A method includes detecting a first touch at a first location and a second touch at a second location on a touch-sensitive display, determining a first force value by a first sensor and a second force value by a second sensor, wherein the first force value and the second force value are determined at a time when the first touch and the second touch are both detected, and determining a first applied force value for the first touch and a second applied force value for the second touch based on the first force value and the second force value and based on the first location and the second location.