Load Cell Temperature Compensation via Dual Sensor Segmentation

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Solution Overview

Problem

Existing load cell units face challenges in achieving stable high-precision weighing due to unbalanced temperature distributions in distortional members, which are not sufficiently considered in output compensation.

Innovation Solution

A load cell unit is designed with a distortional member featuring a free-end block, a fixed-end block, upper and lower beam portions, and strain gauges. The unit includes first and second temperature sensors to detect representative and localized temperatures, enabling temperature compensation based on temperature differences across the load cell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single temperature sensor is used to detect temperature for compensation, then the device complexity is reduced, but the measurement precision of temperature distribution cannot capture unbalanced temperature states

Engineering Contradiction:
Improvetemperature distribution detectionVSAvoidnumber of temperature sensors
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The temperature detection system is segmented into multiple independent temperature sensors positioned at different locations within the load cell unit. This segmentation enables simultaneous detection of temperature at multiple points, capturing unbalanced temperature distributions without requiring a single complex sensor system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different temperature sensors are positioned at specific locations (e.g., near the heat source and at the beam portion) to detect local temperature characteristics. This local quality approach allows the system to capture temperature variations at different regions, enabling accurate detection of unbalanced temperature states while keeping each sensor simple.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If temperature compensation is performed without considering unbalanced temperature distribution, then the compensation process is simplified, but the weighing precision deteriorates

Engineering Contradiction:
Improveweighing precisionVSAvoidcompensation process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary detection of temperature at multiple locations using separate temperature sensors before the compensation calculation is performed. By acquiring temperature data at different positions in advance, the system can calculate temperature differences and perform compensation that accounts for unbalanced temperature distributions, improving weighing precision without requiring complex real-time adjustment mechanisms.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If multiple temperature sensors are positioned on side surfaces of the distortional member, then temperature detection coverage is improved, but the wires from sensors interfere with distortion measurement

Engineering Contradiction:
Improvetemperature detection coverageVSAvoiddistortion measurement accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

Temperature sensors are positioned at intermediate locations (such as the beam portion or near the heat source) rather than directly on the side surfaces where wires would interfere with distortion measurement. These intermediate positions serve as mediators that provide sufficient temperature detection coverage while avoiding the interference problem of wires affecting the distortional member's distortion measurement.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for effective temperature compensation in both balanced and unbalanced states, stabilizing the output and achieving high-precision weighing.

Implementation Method 1

a first temperature sensor that is disposed at the upper beam portion or the lower beam portion and at a portion connecting the two notched parts of the respective beam portion, and that acquires a representative temperature of the load cell as a whole

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 2

a second temperature sensor that is disposed at one of the free-end block and the fixed-end block, a temperature of the beam portion connecting the notched parts is used as the representative temperature of the load cell as a whole

Methodology Applied
Scientific EffectTemperature detection:

Implementation Method 3

a temperature difference compensating unit configured to perform temperature compensation in an unbalanced state on the digital value acquired from the converter unit based on a temperature difference between a first temperature detected by the first temperature sensor and a second temperature detected by the second temperature sensor

Methodology Applied
Scientific EffectTemperature compensation:

Implementation Method 4

strain gauges provided on top surfaces of two notched parts of the upper beam portion and bottom surfaces of two notched parts of the lower beam portion

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Data Source

PatentEP3882581B2Load cell unit and weighing equipment
Publication Date: 2025.04.23 ISHIDA CO LTD
  • EP3882581B2 patent drawingFigure 1
  • EP3882581B2 patent drawingFigure 2
  • EP3882581B2 patent drawingFigure 3

AI summary

A load cell unit includes: a load cell that is provided with a distortional member including a free-end block, a fixed-end block, an upper beam portion connecting an upper end of the free-end block and an upper end of the fixed-end block, and a lower beam portion connecting a lower end of the free-end block and a lower end of the fixed-end block; a first temperature sensor that is disposed at the upper beam portion or the lower beam portion; and a second temperature sensor that is disposed at one of the free-end block and the fixed-end block.