Inductive Touch Force Sensor Without Frequency Scanning

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Solution Overview

Problem

Existing touch recognition technologies face challenges in accurately sensing touch location and force using inductive sensors due to low precision and increased hardware costs when combined with other sensors, and require time-consuming frequency scanning methods.

Innovation Solution

An inductive touch force sensor system that uses a single inductive sensor to detect touch location and force by measuring resonant frequency shifts without frequency scanning, incorporating a determination circuit to analyze changes in inductance and reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an inductive sensor is combined with another sensor (touch sensor or pressure sensor), then touch location and touch force sensing precision is improved, but hardware manufacturing cost increases

Engineering Contradiction:

Improvetouch location and touch force sensing precisionVSAvoidhardware manufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The inductive sensor is designed to perform multiple functions: detecting touch location, touch force, and power button states using a single sensor component, eliminating the need for separate touch sensors or pressure sensors while maintaining sensing precision

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system measures changes in inductance values and resonant frequencies of the inductive sensor to differentiate between touch location, touch force magnitude, and power button states, enabling precise multi-parameter detection with a single sensor

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If frequency scanning method is used to measure inductance changes, then measurement accuracy is improved, but measurement time increases

Engineering Contradiction:

Improveinductance measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system applies a predetermined AC signal at a fixed frequency to the inductive sensor and directly measures the resulting inductance values and resonant frequencies, eliminating the need for time-consuming frequency scanning while maintaining measurement accuracy through direct measurement techniques

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical frequency scanning process with an electronic direct measurement system that uses voltage division ratios and resonant frequency detection to determine inductance changes, significantly reducing measurement time

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If inductive coils are densely arranged to detect touch force for each minute area, then touch force recognition precision is improved, but device complexity increases

Engineering Contradiction:

Improvetouch force recognition precisionVSAvoidsensor arrangement complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The inductive sensor array is divided into multiple independent channels, each with its own inductive coil that can be independently controlled and measured, allowing dense arrangement while simplifying the overall system architecture through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system applies AC signals periodically to different inductive coil channels and measures their responses in a systematic sequence, enabling complex multi-channel measurements to be performed in an organized manner that reduces control complexity

Inventive Principle:

Principle #19Periodic action

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 allows for rapid and accurate detection of touch location and force, reducing hardware costs and power consumption, while enabling precise measurement of inductance changes without the need for frequency scanning, enhancing user interface capabilities.

Implementation Method 1

an inductive coil formed on a substrate that is spaced apart from the target layer... sense the strength of a touch (the magnitude of a force applied in a Z-axis direction)... using inductance varying depending on a change in the distance between a target layer and a coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a first resonance circuit coupled to the inductive coil, and configured to have a first resonant frequency attributable to first inductance due to the inductive coil... by measuring resonant frequency shifts

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11460357B2Electronic device including power-on button and inductive touch force sensor

Publication Date: 2022.10.04 DAMOATECH CO LTD

AI summary

An inductive force sensor includes a reference resonance circuit, a first resonance circuit, and a determination circuit configured to obtain information about a first resonant frequency, attributable to first inductance due to an inductive coil based on the displacement between a target and the inductive coil formed by an external force input in a Z-axis direction, and a reference resonant frequency. The determination circuit determines the displacement of the target and the external force in the Z-axis direction based on the first resonant frequency and the reference resonant frequency.