Input Circuit Self-Test Using a Transistor Signal Copy
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Solution Overview
Problem
Industrial control apparatus input devices face challenges in reliably testing their own functionality, particularly in detecting component failures that lead to incorrect signal level recognition, which can result in dangerous errors.
Innovation Solution
An input device with a transistor-connected input circuit that simulates signal changes using a test signal to reliably test its functionality, allowing for the detection of all dangerous errors without altering the actual input signal, and also limits input current for energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a functionality test is implemented by actually changing the input signal, then the test can detect component failures, but the input signal is altered and additional loading occurs
Solution Approach 1:
The patent introduces a transistor as an intermediary component in the input signal path. The transistor simulates signal changes at the evaluation input without actually altering the input signal at the input connection point. This mediator allows the evaluation device to test functionality while the input signal remains unchanged, resolving the contradiction between reliable testing and avoiding signal alteration.
Solution Approach 2:
The patent creates a copy of the signal change effect by using the transistor to generate an identical change in the evaluation signal without modifying the original input signal. This copying approach allows the system to test functionality by simulating what would happen if the input signal changed, while keeping the actual input signal intact and avoiding additional loading.
2Reliability
If the transistor is used to simulate signal changes for testing, then functionality can be tested reliably, but the device complexity increases
Solution Approach 1:
The patent makes the transistor multi-functional by having it serve both as a signal simulation element for functionality testing and as a current-limiting component during normal operation. This universal approach allows the same component to enable reliable testing while also providing current limiting protection, thereby reducing the need for additional components and minimizing the increase in device complexity.
Solution Approach 2:
The patent merges the functionality test capability with the existing input circuit by integrating the transistor directly into the input signal path. This merging approach combines the testing function with the signal processing function, allowing the transistor to participate in both normal signal operation and test mode operation, thus avoiding the need for separate testing circuitry and reducing overall device complexity.
3Use of energy by moving object
If the transistor limits input current during normal operation, then energy efficiency improves, but the device complexity increases
Solution Approach 1:
The transistor serves dual purposes: simulating signal changes during functionality tests and limiting input current during normal operation. By making the transistor multi-functional, the patent achieves current limiting for energy efficiency without requiring a separate current-limiting component, thus minimizing the increase in device complexity while improving energy efficiency.
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 a reliable self-test of the input device functionality, effectively detecting dangerous errors and ensuring correct signal level recognition, while maintaining energy efficiency by limiting input current.
Implementation Method 1
The input circuit (4) comprises a transistor (T1) which is connected into the input signal path, and the input circuit (4) is designed to control a control terminal (B) of the transistor (T1) on the basis of the test signal (TS), in order to effect the first change of the evaluation signal (AS)
Implementation Method 2
the transistor (T1) additionally serves for limiting the input current which flows into the input connection point (1), in particular in normal operation and/or during the functionality test
Data Source
AI summary
An input device including an input circuit with an input connection point for applying an input signal and with an input signal path which leads from the input connection point to an evaluation input and on which a conversion of the input signal into an evaluation signal is effected, an evaluation device which includes the evaluation input and which is designed to recognise an input signal level of the input signal on the basis of the evaluation signal, wherein the evaluation device is further designed to carry out a functionality test of the input device and within the framework of the functionality test by way of providing a test signal to effect a first change of the evaluation signal and to test the functionality of the input device on the basis of the effected first change of the evaluation signal, wherein the input circuit includes a transistor which is connected into the input signal path, and the input circuit is designed to control a control terminal of the transistor on the basis of the test signal, in order to effect the first change of the evaluation signal.