Optoelectronic Sensor Dynamic Illumination Control
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Solution Overview
Problem
Optoelectronic sensors face challenges in achieving reliable illumination while adhering to laser safety standards, particularly in safety applications where high light power is needed for accurate distance measurement, but must avoid eye protection violations, especially at short ranges where the light output is critical.
Innovation Solution
The solution involves a dynamic illumination control system that initially uses a lower light output for short-range object detection and gradually increases power as objects move further away, ensuring maximum allowable light power is maintained in the working area without exceeding laser safety limits, using a pulsed illumination and combining detection methods for reliable object identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high optical output power is used for illumination, then sufficient light for accurate distance measurement is provided, but laser safety class limits are exceeded causing eye protection violations
Solution Approach 1:
The patent applies dynamics by making the optical output power adjustable rather than fixed. The illumination unit's power is dynamically adapted based on the detected distance to objects - using higher power for distant objects and lower power for near objects. This resolves the contradiction by allowing high illumination intensity when needed for range while automatically reducing power at short distances to maintain eye safety compliance.
Solution Approach 2:
The patent changes the parameter of optical output power based on operating conditions. By detecting object distance and adjusting the illumination power accordingly, the system transitions between different power states. This enables the sensor to provide sufficient light for accurate measurement at long ranges while staying within laser safety class 1 limits at short ranges where objects are closer.
2Object-affected harmful factors
If optical output power is reduced to comply with laser safety class 1, then eye protection is ensured, but illumination becomes insufficient for accurate distance measurement
Solution Approach 1:
The system dynamically adjusts illumination power based on real-time distance detection. When objects are far away, the system uses higher power to ensure sufficient illumination for accurate measurement. When objects are close, it automatically reduces power to maintain safety compliance. This dynamic adaptation ensures both measurement precision and eye safety are maintained under different operating conditions.
Solution Approach 2:
The illumination power parameter is changed according to the detected object distance. The system transitions between different power levels - using maximum permissible power for distant targets to ensure measurement accuracy, and reducing power for near targets to maintain safety compliance. This parameter adaptation resolves the contradiction between sufficient illumination and safety compliance.
3Length of stationary object
If fixed high power illumination is used to ensure sufficient light at working distance, then measurement range is extended, but eye safety is compromised in the near field
Solution Approach 1:
The patent implements dynamic power adjustment where the illumination unit adapts its output based on detected object distances. For distant objects at the maximum detection range, higher power is used to ensure sufficient illumination. For near-field objects, the power is automatically reduced to maintain eye safety. This dynamic behavior extends the effective detection range while protecting against near-field eye exposure risks.
Solution Approach 2:
The system applies different illumination power levels to different spatial zones - using higher power for the far field where detection range is needed and lower power for the near field where eye safety is critical. This local differentiation of illumination quality resolves the contradiction between extending detection range and protecting against near-field eye exposure.
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 ensures continuous compliance with laser safety standards while providing sufficient light for optimal sensor performance, preventing eye exposure and ensuring reliable detection of intrusions, even at short ranges, thereby enhancing safety applications.
Implementation Method 1
a laser light source (24) and a number of optical components (26) arranged along the optical path of one another
Implementation Method 2
optical components (26) arranged along the optical path of one another
Implementation Method 3
optical components (26) arranged along the optical path of one another
Implementation Method 4
a photodetector array (16) and associated circuitry (30) for evaluating the signals from the individual photodetectors (16) in parallel
Data Source
AI summary
An optoelectronic sensor (10) for monitoring a working area (42) is provided, the working area (42) being located within a detection area (20) of the sensor (10) and in a first distance from the sensor (10), wherein the sensor (10) comprises an illumination unit (22) with a light source (24) for at least partially illuminating the working area (42), and an object detection unit (30) for detecting forbidden objects in the working area (42), wherein an illumination control (28) of the illumination unit (22) is configured to, during a startup period,initially activate the illumination unit (28) with a lower power such that a provisional working area (40, 40a-c) in a second distance from the sensor (10) less than the first distance is illuminated at most with a predetermined maximum light output;test whether there is a forbidden object intrusion into the provisional working area (40, 40a-c); andif no forbidden object intrusion is detected, activate the illumination unit (28) with a higher power such that the working area (42) is illuminated at most with the predetermined maximum light output.The illumination control (28) comprises a short range object detection unit (39) configured to test the provisional working area (40, 40a-c) in a different way than the object detection unit (30) tests the working area (42).