Touch Pad Piezoelectric Press Detection for Uniform Button Triggering

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Solution Overview

Problem

Conventional notebook computer touch pads often require varying force application to trigger buttons effectively, leading to user inconvenience due to inconsistent displacement and potential failure in triggering switches when pressed at different locations.

Innovation Solution

Incorporating a piezoelectric sheet on the touch pad that generates a voltage upon deflection, allowing the controller to send a trigger signal when a predetermined voltage threshold is met, regardless of the pressing location, thus enabling consistent button triggering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a physical switch is disposed below the touch pad to detect button presses, then the touch pad can trigger button operations, but the switch is usually disposed at the middle of a side of the touch pad, resulting in that when the user presses the touch pad at different locations with the same force, the portion of the touch pad corresponding to the switch will produce different displacements, of which some may be unable to trigger the switch effectively

Engineering Contradiction:

Improvebutton triggering reliabilityVSAvoidpressing location flexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical switch system with a capacitive sensing system. The touch pad includes a capacitor array that detects changes in capacitance when pressed at different locations. This electrical field-based detection method eliminates the need for a physical switch at a specific location, allowing reliable button triggering regardless of where the user presses on the touch pad surface.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from a one-dimensional switch activation model (single point contact) to a two-dimensional capacitive sensing model. By distributing capacitors across the touch pad surface in an array configuration, the system can detect pressing events at multiple locations simultaneously, effectively adding spatial dimensionality to the detection capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the user presses the touch pad not at the portion corresponding to the switch, the user needs to press with much force for ensuring that the switch can be triggered effectively

Engineering Contradiction:

Improveswitch triggering effectivenessVSAvoidpressing force required

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The capacitive sensing system replaces the mechanical switch that required significant pressing force to activate. The capacitor array detects pressing events through changes in electrical field capacitance, which requires minimal force. This allows users to trigger button operations effectively regardless of pressing location without needing to apply excessive force.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a single touch pad is used in coordination with a physical switch, then the structure is simple, but the touch pad can only effectively trigger the switch when pressed at specific locations

Engineering Contradiction:

Improvetouch pad structure complexityVSAvoidpressing location adaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the touch pad into a capacitor array with multiple capacitive sensing elements distributed across the surface. This segmentation allows different regions of the touch pad to be independently detected, providing multiple effective pressing locations while maintaining a relatively simple overall structure based on standard capacitive touch technology.

Inventive Principle:

Principle #1Segmentation

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 solution ensures that the touch pad can send a trigger signal effectively regardless of the pressing location, providing consistent user input and improving usability by eliminating the need for precise force application.

Implementation Method 1

The piezoelectric sheet is fixed on the touch pad. The piezoelectric sheet generates a voltage when the touch pad is elastically deflected.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10928969B2Input device and electronic apparatus therewith

Publication Date: 2021.02.23 WISTRON CORP

AI summary

An input device includes a structural frame, a touch pad, a piezoelectric sheet fixed on the touch pad, and a controller electrically connected to the touch pad and the piezoelectric sheet. The touch pad has a first side, a second side opposite to the first side, and a touch-sensitive surface that has a button area located at the second side. The touch pad can be elastically deflected to move the second side relative to the structural frame. The piezoelectric sheet generates a voltage when the touch pad is elastically deflected. When determining that a press is performed on the button area and the voltage is larger than or equal to a corresponding predetermined value, the controller sends out a trigger signal. An electronic apparatus with the input device includes a display screen and a processor. The processor receives the trigger signal to control the display screen to display images.