Force Measuring Device Reference Unit

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Solution Overview

Problem

High-resolution force-measuring devices with electromagnetic force compensation require reference voltages or currents with higher stability and lower noise, particularly to suppress popcorn noise and temperature-dependent noise, which existing semiconductor-based solutions fail to adequately address.

Innovation Solution

A force-measuring device with a reference unit loaded with a reference mass that generates a regulated reference current through a magnetic field, using a principle of electromagnetic force compensation, which automatically corrects external disturbances and is designed to be cost-effective and compact, with optional compensation for buoyancy and temperature influences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If semiconductor-based reference voltage sources (e.g., Zener diodes) are used, then the device complexity is reduced and cost is lowered, but the noise behavior and temperature stability deteriorate due to popcorn noise and temperature-dependent properties

Engineering Contradiction:
Improvereference unit structureVSAvoidreference voltage stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces the semiconductor-based electrical reference system with a mechanical reference system using a reference mass, reference lever, and electromagnetic force compensation mechanism. This substitution eliminates semiconductor-related noise (popcorn noise) and temperature-dependent electrical properties, achieving superior stability and noise performance while maintaining reasonable device complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental operating parameters of the reference unit from electrical (Zener diode breakdown voltage) to mechanical-electromagnetic (gravitational force on reference mass compensated by electromagnetic force). This parameter change enables the reference to achieve better noise behavior and temperature stability, as mechanical gravitational references are inherently more stable than semiconductor electrical references

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If conventional reference voltages are used in high-resolution force-measuring devices, then the manufacturing cost is reduced, but the measurement precision deteriorates due to insufficient reference stability and higher noise levels

Engineering Contradiction:
Improvereference unit costVSAvoidforce measurement resolution
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces conventional electrical reference voltage sources with a mechanical reference mass system that uses gravitational force as the reference. This mechanical reference provides superior noise behavior and temperature stability, enabling high-resolution force measurements while remaining cost-effective by avoiding complex temperature compensation circuits and high-precision semiconductor references

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The reference unit uses a reference mass whose gravitational force serves as its own reference standard, eliminating the need for external calibration or complex stabilization systems. The electromagnetic force compensation automatically adjusts to maintain equilibrium, providing a self-regulating reference that achieves high measurement precision without requiring expensive additional components

Inventive Principle:
Principle #25Self-service

3Measurement precision

If electromagnetic force compensation is used for high-resolution measurements, then the measurement precision is improved, but the device complexity increases due to the requirement for highly stable and low-noise reference voltages

Engineering Contradiction:
Improveforce measurement resolutionVSAvoidreference unit structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex electrical reference system with a mechanical reference system that inherently provides the required stability. The reference mass on a reference lever with electromagnetic compensation creates a mechanical-electromagnetic system that is simpler than high-precision electrical references, as it uses fundamental gravitational force rather than complex semiconductor physics

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The reference unit serves multiple functions: it provides a stable reference force, acts as a noise filter, compensates for temperature variations, and can be used for calibration. This multi-functionality is achieved through a relatively simple mechanical-electromagnetic structure, avoiding the need for separate systems for each function and thereby reducing overall device complexity

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 solution provides a precise, low-noise reference variable suitable for high-resolution measurements, effectively suppressing system-immanent and external disturbances, while being economically viable and compactly integrated into the force-measuring device.

Implementation Method 1

the reference unit is a force-measuring device loaded with a reference mass which, according to the principle of electromagnetic force compensation, generates a reference current which can be regulated by means of a measuring and control device in such a way that it generates a magnetic field in a first reference coil held by a reference lever, which Magnetic field of a reference magnet, preferably a permanent magnet, interacts in such a way that a force acts on the reference lever

Methodology Applied
Scientific EffectElectromagnetic force compensation: Lorentz Force

Implementation Method 2

a force acts on the reference lever, by means of which the reference mass can also be compensated for the force that also acts on the reference lever

Methodology Applied
Scientific EffectGravitation: Gravitation

Data Source

PatentEP1898193B1Force measuring device and reference unit
Publication Date: 2016.06.01 METTLER TOLEDO GMBH
  • EP1898193B1 patent drawingFigure 1~1a
  • EP1898193B1 patent drawingFigure 2
  • EP1898193B1 patent drawingFigure 3

AI summary

The force measuring device (1000) has a measuring unit (100a) and a reference unit (100R) which serves to provide a reference quantity, a reference current (IREF) or a reference voltage (UREF), by means of which the force (FMO) to be determined of a measured object can be measured by the measuring unit (100a). According to the invention, the reference unit (100R) is a force measuring device loaded with a reference mass (mREF), which generates a reference current (IREF) according to the principle of electromagnetic force compensation, which can be controlled by means of a measuring and control device (3,4) in such a way that it generates a magnetic field in a first reference coil (1R;1Ra) held by a reference lever (105R), which interacts with the magnetic field of a reference magnet (2R) in such a way that a force acts on the reference lever (105R), by means of which the force (FREF) of the reference mass (mREF) also acting on the reference lever (105R) can be compensated.