Optical Sensor Disc Self-Test for Contamination Detection
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Solution Overview
Problem
Optical sensors used in security technology are prone to functional impairment due to external environmental influences such as dirt and mechanical damage, which affect the permeability of the disc through which light rays are led, making secure object detection unreliable.
Innovation Solution
A test unit with multiple test transmitters and detectors is used to thoroughly monitor the disc for impairments, employing a reference element for error control and correction, allowing for continuous monitoring and compensation of temperature fluctuations and other variations, ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a test unit is added to monitor the disc for contamination and damage, then the reliability of object detection is improved, but the device complexity increases
Solution Approach 1:
The test transmitters and test detectors are integrated into the housing and share the same optical path through the disc with the main transmitting/receiving unit. The test unit uses the disc itself as the monitoring target, making the system self-diagnosing without requiring separate external monitoring equipment. This multi-functional approach allows the same optical components to serve both measurement and self-test purposes.
Solution Approach 2:
The optical sensor performs self-monitoring by using its own disc as the test object. The test unit detects impairments in the disc that would otherwise go unnoticed, allowing the system to self-diagnose contamination and damage conditions. This eliminates the need for separate external monitoring systems and reduces overall device complexity while improving reliability.
2Measurement precision
If multiple test transmitters and test detectors are arranged to cover the entire disc, then the measurement precision of disc inspection is improved, but the device complexity increases
Solution Approach 1:
The disc monitoring function is divided into multiple measurement zones, with different test transmitters and test detectors assigned to monitor specific angular ranges of the disc. Each test transmitter-detector pair covers a particular sector, and the combination of all pairs provides complete coverage. This segmentation allows precise localization of contamination or damage while using a manageable number of components.
Solution Approach 2:
The test transmitters and test detectors are arranged in the angular dimension around the disc, with each pair monitoring a specific angular range. By distributing the test components around the circumference of the disc rather than using a single point measurement, the system achieves comprehensive coverage and high measurement precision without requiring an excessive number of components.
3Reliability
If reference measurements are performed continuously to correct for temperature fluctuations, then the reliability of the test unit is improved, but the loss of time for actual measurements increases
Solution Approach 1:
Reference measurements are performed periodically at predetermined intervals rather than continuously. The control unit schedules reference measurements at appropriate times, such as when the deflection unit is in a specific angular position or when environmental conditions change significantly. This periodic approach maintains temperature compensation reliability while minimizing the time lost to reference measurements and ensuring timely object detection.
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
The solution provides a comprehensive review of the disc's condition, significantly increasing the functional reliability of the optical sensor by detecting and correcting for impairments, ensuring error-free operation and maintaining performance despite environmental changes.
Implementation Method 1
test transmitters (13) and test detectors (14) for monitoring the disc (4) for impairments... test light beams (16) emitted by the test transmitters (13) pass through different areas of the disc (4)
Implementation Method 2
employing a reference element for error control and correction, allowing for continuous monitoring and compensation of temperature fluctuations and other variations
Implementation Method 3
These transmitted light beams are periodically deflected by a deflection unit within a predetermined angular range
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a~4b
AI summary
The invention relates to an optical sensor (1) for detecting objects in a monitoring area, comprising a housing (3) and a transmitter/receiver unit (2) arranged within the housing (3). Light beams (8) emitted by a transmitter (9) of the transmitter/receiver unit (2) are guided within the monitoring area and pass through a disk (4). Light beams (8) reflected back from an object are guided through the disk (4) to a receiver (10) of the transmitter/receiver unit (2), and in an evaluation unit, received signals from the receiver (10) are evaluated to generate an object detection signal. A test unit for checking the transmittance of the disk (4) is provided, which includes at least one test transmitter (13) emitting test light beams (16) and a test detector (14 and/or 14'). The test light beams (16) are directed at the disk (4).A reference element (18) with defined transmission and/or reflection properties is provided, whereby a fault check of the test unit is carried out with the reference element (18) inserted in the beam path of the test light beams (16).