Photoelectric Sensor Circuit for Standalone Fault Detection
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Solution Overview
Problem
The existing methods for detecting abnormalities in transmission-type photoelectric sensors, particularly when connected alone, are costly and not advantageous due to the need for a slave PLC with complex sensor abnormality diagnosing means.
Innovation Solution
A photoelectric sensor configuration with a light emitter and receiver, utilizing switching elements and a monitoring circuit to detect abnormalities through output signal states, allowing for simple detection of disconnections and light beam integrity, reducing the need for complex PLC-based diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor abnormality diagnosing means is mounted in the slave of the PLC to detect abnormalities in transmission-type photoelectric sensors, then abnormality detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The photoelectric sensor performs self-diagnosis by monitoring its own operation status through the monitoring circuit that detects abnormalities in the light beam and circuit connections. The sensor autonomously generates abnormality detection signals without requiring external PLC slave intervention, enabling the system to serve itself in detecting faults.
Solution Approach 2:
The abnormality detection function is extracted from the PLC slave and integrated directly into the photoelectric sensor itself. This separates the diagnostic capability from the control system, allowing the sensor to independently monitor its own status and report abnormalities through dedicated signal lines.
2Device complexity
If a transmission-type photoelectric sensor is connected alone without PLC slave integration, then device complexity is reduced, but abnormality detection capability is lost
Solution Approach 1:
The standalone photoelectric sensor incorporates self-diagnostic functionality through the monitoring circuit that continuously checks light beam presence and circuit connection status. This enables the sensor to autonomously detect and signal abnormalities without requiring complex external PLC slave systems.
Solution Approach 2:
A monitoring circuit acts as an intermediary between the light emitter, light receiver, and output signals. This intermediary component specifically monitors light beam integrity and circuit connections, generating abnormality detection signals that provide fault information without requiring PLC slave integration.
3Measurement precision
If complex PLC-based sensor abnormality diagnosing means is used, then measurement precision of abnormality detection is improved, but ease of operation deteriorates
Solution Approach 1:
The photoelectric sensor autonomously performs precision abnormality detection through its integrated monitoring circuit that continuously evaluates light beam presence and circuit connection status. This self-service capability eliminates the need for complex PLC slave configurations, making the sensor easy to install and operate while maintaining high detection precision.
Solution Approach 2:
The abnormality detection functionality is extracted from the PLC system and embedded directly in the photoelectric sensor. This extraction simplifies operation by providing standalone diagnostic capability with clear abnormality detection signals that do not require complex PLC programming or configuration.
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 reliable and cost-effective detection of abnormalities in transmission-type photoelectric sensors, including disconnections and light beam issues, without requiring a complex PLC-based system, thus simplifying the configuration and reducing costs.
Implementation Method 1
a light emitting unit configured to emit a light beam
Implementation Method 2
a light receiving unit configured to detect that the emitted light beam has changed due to a detection target
Data Source
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AI summary
A photoelectric sensor including a light emitter and a light receiver that are separated from each other is provided. The light emitter includes a light emitting unit configured to emit a light beam, and a power supply circuit configured to receive supply of electric power through a first power supply line leading to an outside of the light emitter and to supply required electric power to the light emitting unit. The light receiver includes: a first switching element connected to a second power supply line leading to an outside of the light receiver, the first switching element serving to output a first output signal; a second switching element connected to the second power supply line and serving to output a second output signal; and a detection circuit configured to switch a conducting state of each of the first switching element and the second switching element in accordance with an intensity of light detected. A third power supply line is provided such that one end of the third power supply line is electrically connected to the first power supply line inside the light emitter, and the other end of the third power supply line is electrically connected to the second power supply line outside the light receiver.