Electrostatic Charge Correction in Precision Balances
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Solution Overview
Problem
Existing balances face significant measurement errors due to electrostatic charges on non-conductive weighing objects, particularly when using glass or polymer containers, as these charges induce forces that interfere with the weighing result, especially in precise measurements, and current solutions like ionized air generators or electrostatic sensors have limitations such as air drafts, incomplete charge neutralization, and irrelevance of total charge measurement.
Innovation Solution
A method involving a balance with a force-measuring cell and a load receiver, where a first electrode near the weighing object is alternately applied with predefined positive and negative voltages to measure the difference in forces, determining the influence of electrostatic charges on the weighing result, and sending this difference as an input signal to a processor unit to correct the measurement, without additional sensors or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ionized air generators are used to neutralize electrostatic charges, then measurement errors are reduced, but air drafts are generated that interfere with weighing
Solution Approach 1:
The patent extracts the harmful air draft generation function from the ionized air generator by using alternative electrode configurations that neutralize charges through direct contact or proximity without requiring air movement. The ion generator is replaced or supplemented with electrodes that create electric fields to neutralize charges in place.
Solution Approach 2:
The patent introduces electrodes as intermediaries between the charged object and ground potential. These electrodes provide a controlled path for charge neutralization through electric field interaction, avoiding the need for ionized air streams that cause drafts.
2Measurement precision
If fixed amount of ionized air is used to neutralize charges, then neutralization occurs, but the amount of ionized air does not adapt to varying charge magnitudes
Solution Approach 1:
The patent implements dynamic adaptability by using feedback circuits that continuously monitor the charge state of the weighing object and adjust the neutralization process accordingly. The system transitions from fixed ionized air output to dynamically controlled electrode voltage adjustment based on real-time charge measurements.
Solution Approach 2:
The patent employs feedback mechanisms where electrostatic sensors detect the charge magnitude and polarity, and this information is fed back to control the voltage applied to neutralization electrodes, creating a closed-loop system that adapts to varying charge conditions.
3Difficulty of detecting and measuring
If electrostatic sensors are used to detect charges, then charge presence is detected, but the sensor location limits the validity of measurements
Solution Approach 1:
The patent divides the charge detection function into multiple electrostatic sensors positioned at different locations around the weighing object. This segmentation allows measurement of charge distribution across different spatial zones, providing comprehensive charge information.
Solution Approach 2:
The patent makes the electrode system multi-functional by using the same electrodes for both weighing force measurement and electrostatic charge detection. This universal approach eliminates the need for separate sensor locations and integrates both measurement functions into a single system.
4Difficulty of detecting and measuring
If additional sensors are added to detect electrostatic charges, then charge measurement is enabled, but device complexity increases
Solution Approach 1:
The patent makes the existing force-measuring cell and electrode system multi-functional, using it for both weight measurement and electrostatic charge detection. This eliminates the need for additional dedicated sensors and reduces overall system complexity.
Solution Approach 2:
The patent merges the charge detection function with the existing weighing measurement system by using the same electrodes and measurement circuits for both purposes, thereby avoiding additional hardware complexity.
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 method accurately estimates and corrects for the impact of electrostatic charges on the weighing result, reducing measurement errors and enhancing sensitivity, while maintaining minimal additional electronic circuitry and avoiding air drafts, with the ability to determine charge polarity and magnitude for targeted de-ionization.
Implementation Method 1
a first electrode which is arranged in the vicinity of the weighing object is alternately supplied with a first predefined positive voltage and a second predefined negative voltage
Implementation Method 2
the forces acting on the force-measuring cell, respectively, during application of the first voltage and during application of the second voltage are measured
Data Source
AI summary
A method estimates the effect on the weighing result of a balance (1) that is caused by electrostatic charges on an object (2) received on a load receiver (6) thereof. A first predefined positive voltage (U1) and a second predefined negative voltage (U2) of equal magnitude are alternatingly applied to a first electrode (12) in the vicinity of the weighing object. The forces acting on a force-measuring cell (17) are measured and are registered as the first and second measurement results. The difference between the respective measurement results represents the magnitude of the influence that the electrostatic charges residing on the weighing object are having on the weighing result. The difference also represents an essentially proportional part of the force resulting from electrostatic charges on the weighing object which causes a change in the weighing result and is sent as a signal to a processor unit.