Coupled Comparator Signal Converter for Consistent Redundant Outputs
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Solution Overview
Problem
Existing signal converter circuits for safety-oriented devices face challenges in accurately identifying different functional states due to tolerances in comparator circuits and upstream filter arrangements, leading to inconsistent output signals.
Innovation Solution
The implementation of a signal converter circuit with bidirectional coupling between two comparator circuits via a coupling line, using presettable attenuation means to limit the influence between them, ensuring redundant signal conversion and eliminating tolerances while maintaining safety-oriented properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two comparator circuits are used for redundant signal conversion, then reliability is improved, but tolerances in the comparator circuits and upstream filter arrangements cause inconsistent output signals
Solution Approach 1:
The patent merges the reference inputs of two separate comparator circuits by electrically connecting them together. This allows the reference inputs to share a common signal level, ensuring that both comparators operate from the same reference potential. As a result, tolerances in individual comparator circuits and upstream filter arrangements are compensated, producing consistent output signals while maintaining redundant signal conversion for improved reliability.
2Measurement precision
If the reference inputs are electrically connected to eliminate tolerances, then output signal consistency is improved, but redundancy in signal conversion may be compromised
Solution Approach 1:
The patent applies local quality by making the reference inputs share a common signal level while keeping the comparator circuits themselves independent. The electrical connection is localized to only the reference inputs, not the entire comparator circuits. This allows the reference potential to be standardized (improving consistency) while the comparators maintain their independent operation (preserving redundancy), thus resolving the contradiction between consistency and reliability.
3Measurement precision
If a coupling line transmits signal levels between comparator circuits, then tolerances are compensated, but the influence between comparator circuits must be limited to maintain switching hysteresis
Solution Approach 1:
The patent changes the electrical parameters of the coupling line by selecting a specific resistance value (10 kΩ) that optimizes the trade-off between tolerance compensation and hysteresis preservation. This parameter selection ensures that the coupling line transmits enough signal to compensate for tolerances in the comparator circuits and upstream filters, while simultaneously limiting the influence to maintain the switching hysteresis of the comparators. The specific resistance value is chosen to satisfy both requirements without requiring complex additional circuitry.
Data Source
AI summary
A signal converter circuit includes a sensor connection, two comparator circuits, each having a signal input for an electric connection to the sensor connection, a reference input for an electric connection to a respectively assigned reference signal source and a signal output for a provision of an output signal, with a feedback line being formed between the respective signal output and the respective reference input, and further including two reference signal sources, each of the comparator circuits being configured for comparing a signal level at the signal input to a signal level at the reference input and for outputting a digital output signal as a function of a comparison result between the signal levels, wherein the two reference signal inputs are connected to one another via a coupling line being configured to transmit a presettable fraction of the respective signal level present at one reference input to the other reference input.