Optoelectronic Sensor Edge Detection via Dual Receiver Balance
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Solution Overview
Problem
Conventional optoelectronic sensors face challenges in reliably detecting object edges, especially when packaging is closely arranged or has inhomogeneous textures, leading to errors in signal interpretation and edge detection.
Innovation Solution
An optoelectronic sensor design with two light receivers arranged in a receiver plane, where the light transmission device generates a collimated light beam, allowing for an energetic balance assessment by comparing the intensities received by the light receivers, which changes direction based on whether it's a front or rear object edge, enabling robust edge detection even for closely spaced objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional triangulation sensor with a spatially resolving light receiver is used, then the sensor can detect packaging on a conveyor belt, but the sensor cannot reliably detect small gaps between closely arranged packaging or distinguish edges from inhomogeneous textures
Solution Approach 1:
The sensor divides the light receiver into two separate receivers (first light receiver and second light receiver) positioned at different locations. Each receiver independently records light intensity from the object surface, allowing the evaluation unit to compare signals and distinguish true edges from inhomogeneous textures by analyzing the differential response between the two receivers.
Solution Approach 2:
The evaluation unit acts as an intermediary that processes the signals from both light receivers. It compares the recorded light intensities, forms differences or ratios, and uses threshold values to determine whether a detected feature is a true object edge or an artifact caused by inhomogeneous textures or glossy surfaces, thereby filtering out false detections.
2Illumination intensity
If the light beam is oriented perpendicular to the object surface, then the light reception is maximized, but the sensor cannot distinguish between front and rear edges of objects
Solution Approach 1:
The sensor introduces asymmetry by positioning the first and second light receivers at different locations relative to the light beam path. This asymmetric arrangement causes the receivers to have different response characteristics when the light beam is oriented perpendicular to the object surface, enabling the system to distinguish between front and rear edges based on which receiver detects higher intensity light.
Solution Approach 2:
Instead of orienting the light beam perpendicular to the object surface to maximize reception, the patent inverts the approach by keeping the light beam perpendicular and using the asymmetric receiver positions to create distinguishable signal patterns. The evaluation unit then inverts the usual expectation by using the difference in receiver responses to determine edge direction, rather than relying on the light beam orientation itself.
3Productivity
If packaging is arranged closely together on the conveyor belt, then production efficiency is maximized, but the sensor cannot reliably detect transitions between consecutive packaging items
Solution Approach 1:
The sensor segments the detection task by using two spatially separated light receivers that independently monitor light intensity at different positions. This segmentation allows the system to detect transitions between closely arranged packaging items by analyzing the temporal and spatial pattern of signals from both receivers, enabling reliable gap detection even when packaging items are positioned very close together.
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 allows for reliable detection of object edges with high switching frequencies and low power consumption, offering a cost-effective solution that adapts to different gap widths and reduces errors from inhomogeneous textures and glossy surfaces.
Implementation Method 1
a light transmitter (23) and two light receivers (25) arranged in a receiving plane at least essentially symmetrically on both sides, i.e. to the left and right of the light transmitter (23)... The light transmitter (23), which includes a light source (27) and a transmitting lens (29), transmits a collimated or focused transmitted light beam (31), which falls on beverage cartons (11)... The light with Lambert characteristics remitted at the location of the light spot returns to the sensor as received light beams (35)
Data Source
Figure 1a)~1c)
Figure 2~3
AI summary
The sensor has a light transmission device comprising light transmitters (23) for generating a collimated or focused transmission light beam (31). Light receivers (25) receive a light spot generated by the transmission light beam on an object (11), and are arranged on opposite sides of the light transmission device. A control- and evaluation device (39) compares two receiving intensities of two images of the light spot with each other, evaluates a result of the comparison and detects an edge (41) of the object. An independent claim is also included for a method for detecting edges of moving objects.