Force-Sensitive Key Structure for Analog Press Detection

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Solution Overview

Problem

Conventional keyboards lack the ability to provide diverse or multi-level application effects, as they can only generate digital triggering signals corresponding to the on or off state of a key press.

Innovation Solution

A force-sensitive key module and switch structure that converts pressing force into an analog sensing signal, allowing impedance changes based on the magnitude of the pressing force, thereby enabling diverse or multi-level application effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional digital switch structures are used, then the key structure can generate triggering signals in on/off states, but the key structure cannot provide diverse or multi-level application effects

Engineering Contradiction:

Improveapplication effectsVSAvoidsignal processing

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter type of the output signal from digital (binary on/off) to analog (continuous impedance values). The force-sensitive layer converts pressing force magnitude into varying impedance values, which directly correspond to different pressing depths. This parameter change enables diverse application effects without increasing device complexity, as the analog impedance variation naturally encodes multiple information levels.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the key structure is pressed, then a triggering signal is generated, but the pressing force magnitude cannot be distinguished

Engineering Contradiction:

Improvepressing force detectionVSAvoidsensing mechanism

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical force measurement mechanisms with an electrical impedance-based sensing system. The force-sensitive layer uses electrical impedance changes to reflect mechanical pressing force magnitude, substituting mechanical measurement with electrical measurement. This approach achieves precise force detection while keeping the sensing mechanism simple and integrated into the existing key structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for force detection from mechanical displacement or contact force to electrical impedance. The force-sensitive layer's impedance varies continuously with pressing force magnitude, providing precise measurement capability. This parameter substitution simplifies the sensing mechanism while enhancing measurement precision.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the same key structure is used for repeated pressing, then the key can be operated multiple times, but no additional information about pressing intensity is provided

Engineering Contradiction:

Improverepeated operation capabilityVSAvoidpressing intensity information

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent changes the output signal parameter from binary digital states to continuous analog impedance values. This allows the key structure to maintain repeated operation capability while simultaneously providing pressing intensity information through impedance variation. The analog parameter encodes both the occurrence and the intensity of each press, preventing information loss.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent makes the key structure universal by enabling it to perform both traditional digital switching and analog force sensing functions simultaneously. The same force-sensitive layer that detects pressing occurrence also measures pressing intensity through impedance variation, allowing one structure to fulfill multiple information-providing roles without requiring separate mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 force-sensitive key module can generate analog sensing signals in response to varying pressing forces, allowing for multi-level control functions and expanding the application capabilities of keyboards beyond simple on/off states.

Implementation Method 1

the force-sensitive layer generates an analog sensing signal in response to the pressing force. When a magnitude of the pressing force is changed, the analog sensing signal is correspondingly changed according to an impedance change of the force-sensitive layer.

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS12266484B2Force-sensitive key module and force-sensitive switch structure thereof

Publication Date: 2025.04.01 PRIMAX ELECTRONICS LTD

AI summary

A force-sensitive key module and a force-sensitive switch structure are provided. The force-sensitive switch structure includes a first protective layer, a second protective layer, a first conductive layer, a second conductive layer and a force-sensitive layer. The first protective layer receives a pressing force. The second conductive layer is aligned with the first conductive layer. The force-sensitive layer is installed on the first conductive layer or the second conductive layer. When the first protective layer receives the pressing force, an electric connection between the first conductive layer and the second conductive layer is established, and the force-sensitive layer generates an analog sensing signal in response to the pressing force. When a magnitude of the pressing force is changed, the analog sensing signal is correspondingly changed according to an impedance change of the force-sensitive layer.