Switch Input Diagnosis Without Filter-Induced Response Delay
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Solution Overview
Problem
The existing safety input devices face issues with input responsiveness during self-diagnosis due to the use of low-pass filters, which can lead to failures in rapid response to input signals.
Innovation Solution
An input device that outputs a voltage selected from a first and a second voltage, receives this voltage via a switch, and determines changes in the input signal to confirm the conduction state, thereby improving responsiveness during self-diagnosis without the need for signal filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-pass filter is used to remove the pulse train signal for self-diagnosis, then the self-diagnosis function is achieved, but the input responsiveness deteriorates due to signal filtering
Solution Approach 1:
The patent segments the signal processing path into two independent channels: one for self-diagnosis (pulse train signal) and one for normal control (input signal). The self-diagnosis channel processes pulse train signals to verify wire conduction, while the control channel processes input signals without filtering to maintain rapid response. This segmentation allows both self-diagnosis reliability and input responsiveness to coexist without mutual interference.
2Measurement precision
If signal filtering is applied to achieve self-diagnosis, then the conduction state confirmation is improved, but the noise margin deteriorates due to filtering delays
Solution Approach 1:
The patent introduces a switching element as an intermediary that selectively connects different voltage sources to the input terminal. During self-diagnosis, a test voltage is applied; during normal operation, the input signal voltage is applied. This intermediary switching mechanism enables precise conduction state confirmation during diagnosis without introducing filtering delays that would reduce noise margin during normal operation.
Data Source
AI summary
An input device (10) is connectable to a switch (20) to receive a state of the switch (20) input as a voltage corresponding to the state. The input device (10) includes an output circuit (120) to output a first voltage or a second voltage different from the first voltage, an input circuit (150) to receive the voltage input from the output circuit (120) via the switch (20) in a closed state and output input signals (33) corresponding to the input voltage, a diagnoser (112) to determine whether the input signals change in response to switching of the voltage from the output circuit (120) to the second voltage, and a generator (113) to generate a state signal (34) indicating the state of the switch (20) based on the input signals (33). The second voltage differs from a reference voltage input to the input circuit (150) while the switch (20) is open.