Electrodynamic Scale Overload Detection by Resistance Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing scales using electrodynamic force compensation struggle to accurately analyze and quantify overload conditions, as they exceed the load measuring range of the A/D converter and/or the output stage's capacity, leading to potential damage and inability to provide precise weight readings.
Innovation Solution
The scale switches to an overload mode by reducing the electrical load resistance, allowing the output stage to supply a higher coil current to compensate for forces outside the regular load range, using existing components like A/D converters and output stages, and employing additional resistors to extend the load capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scale operates in regular measuring mode with fixed load resistance, then measurement precision is maintained within the designated load range, but the device cannot accurately detect or quantify overload conditions exceeding this range
Solution Approach 1:
The patent implements dynamic switching between two operating modes: regular measuring mode with higher load resistance for precision, and overload mode with lower load resistance for extended range detection. The system automatically transitions between modes based on detected overload conditions, allowing the load resistance to adapt dynamically rather than remaining fixed
Solution Approach 2:
The patent changes the electrical parameter (load resistance) of the measuring system to accommodate different operating conditions. By switching between two discrete resistance values, the system can accurately measure both normal weights and overload conditions with the same hardware infrastructure
2Adaptability or versatility
If the output stage capacity is increased to handle overload forces, then overload detection range is extended, but the device complexity and power consumption increase
Solution Approach 1:
The patent makes the existing output stage multi-functional by using it in two different configurations: for precision measurement within the normal range and for overload detection beyond the normal range. The same output stage hardware serves both purposes through resistance switching, eliminating the need for separate measurement and overload detection circuits
Solution Approach 2:
The patent introduces a resistance switching mechanism as an intermediary element that modifies the electrical characteristics of the measuring system. This intermediary allows the output stage to operate effectively in both normal and overload conditions without requiring the output stage itself to be redesigned for higher capacity
3Reliability
If a threshold value is set to stop output when exceeded, then legal metrological requirements are met, but no precise information about overload type or magnitude is obtained
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the measuring signal and automatically detects when overload conditions occur. Instead of simply stopping output, the system provides feedback about the overload state by switching modes and continuing to provide measurement information, enabling both compliance and information retention
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
Enables accurate quantification of overload forces, minimizing damage to the scale and ensuring continuous force detection, even when exceeding the intended load range, with seamless transitions between modes.
Implementation Method 1
The controller regulates the output voltage of the output stage in such a way that the resulting current conducted through the coil compensates for the relative movement through electrodynamic interaction with the magnet and the coil and magnet are moved back into the rest position relative to each other
Implementation Method 2
The current required for this force compensation and flowing through the coil is a measure of the force and is therefore measured. To measure the coil current, it can be passed through a measuring resistor, for example, that produces a voltage drop dependent on the current
Data Source
AI summary
The disclosure relates to a scale operating according to the principle of electrodynamic force compensation and to a method for its operation. An automatic switchover from a measuring mode to an overload mode is provided for detecting overload forces. In this overload mode the load resistance formed by a coil and at least one measuring resistor is reduced in order to allow a higher coil current at the same output stage power.