Optical Sensor Test Signal Injection for Safety Monitoring
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Solution Overview
Problem
Existing optical sensors require complex monitoring circuits to check the function of transmitter and receiver components over their entire dynamic range, leading to high effort and complexity in fulfilling safety requirements for security applications.
Innovation Solution
The optical sensor employs a test unit that generates a binary switching signal based on defined test signals, allowing for a simplified evaluation of the sensor's functionality by comparing the digital output signal with a stored setpoint signal, thereby eliminating the need for complex monitoring circuits and ensuring proper functioning of both optical and electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex monitoring circuits are used to check the function of transmitter and receiver over their entire dynamic range, then the reliability of safety monitoring is improved, but the device complexity and effort for acceptance increase significantly
Solution Approach 1:
The patent extracts the monitoring function from complex continuous monitoring circuits and implements it through simple test signals that are injected into the sensor system. Instead of monitoring the entire dynamic range continuously, the system uses discrete test signals at specific light levels to verify functionality, thereby simplifying the monitoring circuit while maintaining safety reliability.
Solution Approach 2:
The patent changes the monitoring approach from continuous monitoring of the entire dynamic range to periodic injection of test signals with specific light levels. The test signals have defined characteristics (different light levels corresponding to different object distances) that allow verification of the sensor's response without requiring complex monitoring circuits to cover the full dynamic range.
2Reliability
If the entire dynamic range of transmitter and receiver is monitored, then complete functional testing is achieved, but the effort and time for acceptance by safety authorities increase
Solution Approach 1:
The patent performs preliminary functional verification by injecting test signals with predefined characteristics before formal acceptance. The test signals are designed to cover critical operating points (different light levels) in advance, so that the sensor's functionality can be verified quickly without requiring extensive testing during the acceptance process.
Solution Approach 2:
Instead of monitoring the entire dynamic range with fine granularity, the patent uses a partial approach by selecting specific test signals at critical light levels that represent key operating points. This partial monitoring of selected points is sufficient to verify functionality while significantly reducing the time and effort required for acceptance.
3Measurement precision
If high resolution analog-digital converters are used to digitize received signals, then measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces expensive high-resolution analog-digital converters with simpler digital evaluation that works directly with the received signals. Instead of using high-precision converters to capture analog signal variations, the system uses digital processing of signal levels, which achieves sufficient precision for safety applications while significantly reducing device complexity and cost.
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
This approach enables a complete functional test with minimal effort, ensuring the optical sensor meets safety standards and can be used in security technology without the need for extensive monitoring circuits, thus simplifying the acceptance process by safety authorities.
Implementation Method 1
at least one transmitter (4) that emits light beams (5) and at least one receiver (7) that receives light beams (5)
Data Source
Figure 1~4
Figure 5~6
Figure 7a~7f
AI summary
The invention relates to an optical sensor (1) for detecting objects in a monitoring area and comprises at least one light beam emitting transmitter (4) and at least one light beam receiving receiver (7). The transmitter (4) and the receiver (7) are arranged such that, when the monitoring area is clear, the light beams (5) from the transmitter (4) reach the receiver (7) unimpeded, and when an object enters the monitoring area, the light beams (5) strike the object and do not reach the receiver (7), or only reach it incompletely. An evaluation unit (8) is provided in which a binary switching signal is generated depending on the received signals present at the output of the receiver (7), the switching states of which indicate whether an object is located in the monitoring area or not. Test means are provided by means of which the transmitter (4) is operated in such a way that it emits a test signal.In a free monitoring area, the received test signal is converted into a digital output signal and compared with a digital target signal stored in the test equipment for error control of the optical sensor (1).