Touchpad Pressure Sensor Eliminates Dome Switch Wear

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Solution Overview

Problem

Laptop computers face issues with touch pad malfunctions due to the integration of touch pads and click buttons, leading to inadvertent cursor movement and inappropriate clicking, and dome switches suffer from performance deterioration and contamination due to frequent use.

Innovation Solution

A touch pad device with a touch pad cover, a pressure sensor substrate, and a frame that detects pressure inputs based on changes in electrical characteristics, eliminating the need for separate components like dome switches and reducing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the touch pad and click button are integrated, then the touch pad area is increased, but the cursor moves inadvertently and clicking becomes inappropriate

Engineering Contradiction:

Improvetouch pad areaVSAvoidcursor control accuracy

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The touch pad surface is divided into multiple sensing regions with different pressure thresholds. The first region (click button area) requires a first pressure threshold to be exceeded for cursor movement, while the second region (touch pad area) requires a second pressure threshold to be exceeded. This segmentation allows the same surface to serve dual functions without inadvertent cursor movement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the touch pad surface are assigned different pressure sensitivity characteristics. The click button region has a higher pressure threshold than the touch pad region, creating local quality differences that prevent inadvertent cursor movement while maintaining a unified surface structure.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If a dome switch is used for the click button, then the clicking function is achieved, but the dome switch deteriorates and gets contaminated due to frequent use

Engineering Contradiction:

Improveclicking functionVSAvoiddome switch durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The mechanical dome switch is replaced with a pressure sensor that detects pressure through electrical resistance changes. This substitution eliminates the mechanical wear and sealing issues associated with dome switches, as the pressure sensor has no moving parts or sealing members that can deteriorate from frequent use.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The clicking detection mechanism changes from mechanical deformation (dome switch) to electrical parameter changes (pressure sensor resistance). This parameter change allows for more durable operation without the physical degradation issues of mechanical switches.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If a dome switch with sealing member is used, then moisture prevention is achieved, but the sealing member and dome switch are damaged due to frequent use

Engineering Contradiction:

Improvemoisture preventionVSAvoidsealing member durability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The sealed mechanical dome switch is replaced with a pressure sensor that requires no sealing member. The pressure sensor detects pressure through electrical resistance changes without mechanical movement, eliminating the need for sealing components that can be damaged by frequent use.

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

The solution effectively senses push or pressure inputs on the touch pad cover, reducing the risk of malfunctions and extending the lifespan of the touch pad device while lowering manufacturing costs.

Implementation Method 1

a magnitude of a pressure inputted to the touch pad cover is detected on the basis of a change in electrical characteristics outputted from the pressure sensor in response to bending of the substrate

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS11768548B2Touch pad device and portable computer comprising same

Publication Date: 2023.09.26 HIDEEP INC

AI summary

The present disclosure relates to a touch pad device and a portable computer including the same, and more particularly, to a touch pad device capable of sensing an inputted push of an object, and a portable computer including the same. A touch pad device according to one embodiment includes: a touch pad cover; a substrate disposed under the touch pad cover and including a pressure sensor; and a frame configured to support the substrate, in which a magnitude of a pressure inputted to the touch pad cover is detected on the basis of a change in electrical characteristics outputted from the pressure sensor in response to bending of the substrate.