Multi-Point Weighing Load Cell Parallel Circuit Adjustment

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Solution Overview

Problem

The existing multi-point type weighing equipment using load cells requires extensive time and cost for adjustment due to the need for individual setup and installation of resistance components for each load cell, especially when manufacturing equipment with multiple load cells.

Innovation Solution

A detection circuit configuration where four Wheatstone bridge circuits are connected in parallel, with temperature compensator and zero balance adjustment resistances only inserted in one load cell, allowing for simplified adjustment processes and reduced component count by equalizing output voltage variations across all load cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If individual resistance components (temperature compensator, zero balance adjustment resistance, output adjustment resistance) are installed for each load cell, then measurement precision is improved, but device complexity and manufacturing time increase significantly

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the adjustment functions of multiple load cells by connecting their Wheatstone bridge circuits in parallel. Instead of having separate temperature compensators and adjustment resistances for each load cell, the invention combines them into a single shared adjustment circuit that can be controlled by a microprocessor, thereby reducing device complexity while maintaining measurement precision across all load cells

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention creates a universal adjustment mechanism that serves multiple load cells simultaneously. The shared Wheatstone bridge circuit with common temperature compensator and zero balance adjustment resistance can be controlled by a microprocessor to independently adjust each load cell's output, making the adjustment system multi-functional and applicable to all load cells without requiring separate components for each

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If individual resistance components are installed for each load cell, then measurement precision is improved, but manufacturing time and cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoidmanufacturing time
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent merges the adjustment operations for multiple load cells into a single process. By connecting Wheatstone bridge circuits in parallel and sharing common adjustment components, the invention allows technicians to adjust all load cells simultaneously rather than individually, significantly reducing manufacturing time and cost while maintaining the required measurement precision

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention incorporates preliminary adjustment capabilities during the manufacturing process. The shared adjustment circuitry is designed to be configurable via microprocessor before the load cells are installed in the final weighing equipment, allowing pre-adjustment of balance and temperature compensation parameters to minimize on-site adjustment time

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If temperature compensator and adjustment resistances are added to each load cell, then temperature stability is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature stabilityVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges temperature compensation functionality into a shared circuit that serves all load cells. Instead of having separate temperature compensators for each load cell, the invention uses a common temperature compensator element in the parallel-connected Wheatstone bridge circuits, reducing device complexity while maintaining temperature stability across all measurements

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention implements feedback control through microprocessor-based adjustment. The system continuously monitors temperature and output voltage from all load cells and automatically adjusts the shared temperature compensator and zero balance resistance to maintain optimal performance, providing active feedback control that simplifies the overall system architecture

Inventive Principle:
Principle #23Feedback

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 configuration significantly reduces the time and cost associated with load cell adjustment, achieving minimal zero balance gap and temperature-dependent output voltage variations, resulting in a more efficient and cost-effective manufacturing process for multi-point type weighing equipment.

Implementation Method 1

strain gauges 54 - 57 of the same specification are joined by four points of the surface of flexure element 53. In strain gauges 54-57, the resistance produces the change by distortion

Methodology Applied
Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

if a Wheatstone bridge circuit, in which these four strain gauge as constituent factors, is formed, and a gap from that zero balance is detected, distortion of flexure element 53 is detectable as electric signal

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

temperature compensator 581 is, for example, formed with copper wire, and compensates a gap of zero balance of a Wheatstone bridge circuit depended on temperature utilizing change of resistance of copper wire depending on temperature

Methodology Applied
Scientific EffectTemperature coefficient of resistance: Thermal Expansion

Data Source

PatentEP2133671B1A multi-point type weighing equipment and a manufacturing method for the same
Publication Date: 2014.05.07 TANITA CORP
  • EP2133671B1 patent drawingFigure 1
  • EP2133671B1 patent drawingFigure 2
  • EP2133671B1 patent drawingFigure 3

AI summary

The time and cost which requires the adjustment of a load cell in case of manufacturing the multi-point type weighing equipment using a plurality of load cells are fully reduced. Four strain gauges comprise a Wheatstone bridge circuit for every load cell, and it has composition that these were connected in parallel. When all the load cells are not loaded, in order to make small the variation of the load cell of the output voltage depending on temperature between CD in case of input voltage being applied between AB as much as possible, temperature compensator (182) which is the first resistance for adjustment is provided in the Wheatstone bridge circuit corresponding to load cell (10). Also, when all the load cells are not loaded, in order to make minimum the absolute value of the output voltage between CD in case of input voltage being applied between AB as much as possible, zero balance adjustment resistance (183), which is the second resistance for adjustment, is also provided in this Wheatstone bridge circuit.