Multispectral Light Bar Layout for Stable Conveyor Code Imaging
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Solution Overview
Problem
Existing lighting systems for industrial sorting facilities face challenges such as shifting shadows and specular reflections due to the use of multiple LED rows, complex circuit design due to different electrical characteristics of LEDs, and ambient noise from high current switching, which impair code detection in high-speed imaging.
Innovation Solution
A light bar arrangement with evenly distributed LEDs of different colors, synchronized flashing, and optimized lens positioning, along with a current regulation system to maintain consistent irradiance and reduce noise, is employed to stabilize illumination and improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple rows of LEDs are used to provide uniform illumination across the conveyor belt, then illumination uniformity is improved, but shadow stability deteriorates due to shifting shadows and specular reflections
Solution Approach 1:
The light bar is divided into multiple independently controllable LED rows (first LED row, second LED row, third LED row) with different colors (e.g., blue, red, infrared). Each row can be activated separately to provide illumination from different angles, allowing the system to maintain uniform illumination while minimizing shadow interference by selecting appropriate rows for different detection needs.
Solution Approach 2:
The patent employs periodic activation of different LED rows in sequence. The control system activates different rows at different time intervals during the imaging process, allowing the camera to capture images with illumination from multiple angles without simultaneous shadow interference. This temporal separation of illumination sources eliminates the shadow shifting problem while maintaining comprehensive illumination coverage.
2Productivity
If high current is used to illuminate the conveyor belt rapidly, then imaging speed is improved, but ambient noise increases due to high current switching
Solution Approach 1:
The patent uses periodic activation of LED rows with controlled current levels. Instead of continuous high current operation, the system activates specific LED rows in rapid succession during the imaging cycle, maintaining high imaging speed while allowing current to be reduced between activations. This periodic operation minimizes ambient noise from high current switching while preserving the ability to capture high-speed images.
Solution Approach 2:
Different LED rows are optimized for different functions: some rows use higher currents for general illumination, while other rows use lower currents for specific detection purposes. The control system selectively activates rows based on the specific imaging requirements, localizing high current usage to only when and where needed, thereby reducing overall ambient noise while maintaining imaging performance.
3Measurement precision
If different colors of LEDs are used for multi-spectral imaging, then code detection accuracy is improved, but device complexity increases due to different electrical characteristics of LEDs
Solution Approach 1:
The patent employs a universal control architecture that manages multiple LED rows with different colors (blue, red, infrared) through a single control system. The control circuit is designed to handle the different electrical characteristics of various LED types by implementing adaptive current regulation and timing control, allowing one control unit to manage multi-color LEDs without requiring separate control circuits for each color, thus reducing overall device complexity.
Solution Approach 2:
The control system dynamically adjusts current levels and activation timing for different LED rows based on real-time imaging requirements. The system can switch between different LED rows and adjust their current levels flexibly, allowing the same control architecture to optimize performance for different detection tasks while managing the electrical complexity of multi-color LEDs through adaptive rather than static control.
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 stable and uniform illumination, reduces image noise, and enhances code detection accuracy in high-speed imaging, improving the reliability of automated sorting systems.
Implementation Method 1
Applicant favors light emitting diodes (LEDs) for generating the different colors of light
Implementation Method 2
transform electrical energy to optical energy
Implementation Method 3
a monochrome camera system captures a first frame under blue light... and an instant later captures a second frame under red light
Data Source
AI summary
In one aspect, an elongated lighting module includes plural colors of LEDs that flash in a cyclical sequence to provide multi-spectral illumination. Several such modules can be arranged end-to-end to span a conveyor system that transports a stream of plastic waste items in a recycling center, enabling capture of differently-illuminated image frames depicting the items. Each module may include N LEDs of a first color (e.g., red) and M LEDs of a second color (e.g., blue), where N and M are different. Drive circuitry can be simplified by configuring the LEDs in strings of common colors, but with different counts. Electrical noise due to switching transients can be reduced by operating the LEDs at a low current when not being flashed. A great variety of other features and arrangements are also detailed.