Force Sensor Displacement Amplification for Precision Weight Measurement

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Solution Overview

Problem

Conventional force sensors face challenges in accurately measuring weight due to low durability, slow response times, and limited sensitivity, particularly when dealing with high-strength elastic bodies, which restricts their application in precise mechanisms.

Innovation Solution

A force sensor utilizing a displacement amplification mechanism, comprising a base, an elastic structure, an adjusting member, a lever, a sensor, and a circuit board, which amplifies the displacement of the elastic structure to enhance sensitivity and accuracy, allowing for precise weight measurement even with high-strength elastic bodies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the elastic body is designed to have low strength to achieve large displacement for measurement, then the measurement range is improved, but the capacity and durability of the force sensor decrease

Engineering Contradiction:

Improvemeasurement rangeVSAvoidcapacity and durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The force sensor is divided into two functional segments: a high-strength elastic body for structural integrity and a displacement amplification mechanism for measurement. This segmentation allows each part to be optimized independently - the elastic body provides strength while the amplification mechanism provides measurement sensitivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A displacement amplification mechanism acts as an intermediary between the high-strength elastic body and the measurement system. This intermediary converts small displacements of the strong elastic body into larger, more measurable displacements, enabling both high strength and accurate measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If a strain gauge is attached to a structure using adhesive, then the strain rate can be transferred to the strain gauge, but the adhesive distorts the strain rate and degrades mechanical properties

Engineering Contradiction:

Improvestrain transfer accuracyVSAvoidmechanical properties

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The invention extracts the measurement function from the structural component by using a separate displacement amplification mechanism. This eliminates the need for adhesive bonding between strain gauges and structures, removing the source of strain distortion and mechanical property degradation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the adhesive-bonded strain gauge mechanical system with an optical or capacitive sensing system that measures displacement without mechanical contact. This substitution eliminates adhesive-related distortion while maintaining strain measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Volume of moving object

If the force sensing resistor is used to measure displacement, then the sensor can be designed in small size, but the response time is slow and durability is poor

Engineering Contradiction:

Improvesensor sizeVSAvoidresponse time

Core Design Contradiction:

Volume of moving objectVSSpeed

Solution Approach 1:

The invention replaces the resistive sensing mechanism with optical or capacitive sensing that measures displacement through field interactions rather than mechanical resistance changes. This substitution dramatically improves response time while maintaining compact sensor design.

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 amplifies displacement, reducing position errors and preventing strength degradation, enabling accurate and sensitive weight measurement while maintaining high strength, thus overcoming the limitations of conventional sensors.

Implementation Method 1

a lever disposed below the elastic structure, and amplifying a displacement of the elastic structure transferred via the adjusting member by being in contact with the adjusting member

Methodology Applied

Scientific EffectLever: Lever

Implementation Method 2

a sensor disposed above the base, and generating an electric signal indicative of a distance from the sensor to the lever

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Data Source

PatentUS10151646B2Force sensor using displacement amplification mechanism and apparatus having the same for measuring weight

Publication Date: 2018.12.11 I2A SYST CO LTD

AI summary

Disclosed is a force sensor and an apparatus having the sensor for measuring weight. The force sensor and apparatus can enhance detection sensitivity by amplifying a displacement of an elastic body having high strength, thereby measuring weight. The sensor includes: a base; an elastic structure provided as a housing disposed on the base, and downwardly deformed when weight is applied to the elastic structure; an adjusting member coupled to an upper surface of the elastic structure by penetrating the upper surface; a lever disposed below the elastic structure, and amplifying a displacement of the elastic structure transferred via the adjusting member by being in contact with the adjusting member; a sensor disposed above the base, and generating an electric signal indicative of a distance from the sensor to the lever; and a circuit board disposed between an upper surface of the base and a lower surface of the sensor.