Capacitive Keyboard Membrane Structure for Tactile Feedback

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Solution Overview

Problem

Conventional capacitive keyboards are expensive and lack tactile feedback, and their durability is compromised due to wear and tear from repeated use.

Innovation Solution

A capacitive touch keyboard design featuring a sensor layer, ground plane, and flexible sensed body, where the flexible sensed body forms a capacitor structure with the key sensing cell, providing tactile feedback and improved durability by reducing the need for deep key depression and minimizing wearout.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional capacitive keyboard design is used, then cost is reduced and structure is simplified, but tactile feedback is lacking

Engineering Contradiction:

Improvetactile feedbackVSAvoidkeyboard structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent employs a flexible sensed body (membrane) that deflects when pressed, providing tactile feedback to the user. This thin film structure maintains simplicity while enabling mechanical sensation through capacitive coupling between the membrane and sensing electrode.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If deep key depression is required for contact, then reliable input detection is achieved, but wearout and elastic fatigue occur

Engineering Contradiction:

Improveinput detection reliabilityVSAvoidkeyboard durability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent replaces direct mechanical contact with capacitive sensing. The flexible sensed body forms a capacitor with the sensing electrode, allowing detection of key presses through capacitance changes rather than physical contact, thereby eliminating wear and fatigue issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent detects key presses by monitoring changes in capacitance values rather than mechanical contact depth. This parameter change approach allows shallow key depression to be detected reliably through capacitance variation, reducing mechanical stress on components.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If conventional capacitive sensing is used, then contactless operation is achieved, but tactile feedback is insufficient

Engineering Contradiction:

Improvetactile feedbackVSAvoidlack of tactile sensation

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The flexible sensed body serves dual purposes: it provides tactile feedback through physical deflection that users can feel, and simultaneously maintains capacitive coupling for contactless sensing operation.

Inventive Principle:

Principle #30Flexible shells and thin films

4Loss of information

If repeated deep pressing is required, then adequate input signal is obtained, but elastic fatigue and wear occur

Engineering Contradiction:

Improveinput signal qualityVSAvoidcomponent lifespan

Core Design Contradiction:

Loss of informationVSDuration of action of stationary object

Solution Approach 1:

The patent substitutes mechanical contact-based signal generation with capacitive coupling. The flexible sensed body forms a capacitor with the sensing electrode, and key presses are detected through capacitance changes, eliminating the need for deep mechanical pressing and associated wear.

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 design enhances user experience with clear tactile feedback and improved durability by allowing shallow key depression and reducing fatigue, while also enabling gesture operations with a honeycomb pattern of hexagonal sensing cells for precise gesture recognition.

Implementation Method 1

the flexible sensed body and the key sensing cell jointly form a capacitor structure... a change on the capacitance of the keyboard is generated allowing the sensing circuit to recognize the depressed key

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8912930B2Capacitive touch keyboard

Publication Date: 2014.12.16 DECENTRALIZED MOTION INTELLIGENCE CO

AI summary

A capacitive touch keyboard includes a sensor layer, ground plane, a flexible sensed body, and a sensing circuit. The sensor layer includes a substrate and a key sensing cell which disposed on the substrate spaced apart from the ground plane. The flexible sensed body includes a sensed portion and a connected portion connected with the ground plane where the sensed portion obliquely extends to above the key sensing cell such that the flexible sensed body and the key sensing cell jointly form a capacitor structure. The sensing circuit is electrically connected to the sensing cell for probing a capacitance change. Therefore, features of more simplified structure design, tactile feel, and improved durability are provided in a capacitive keyboard.