Stereo Imaging for Transparent Pill Detection in Blister Packer
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Solution Overview
Problem
Traditional inspection systems face difficulties in detecting transparent or specular objects, such as pills in blister packaging, due to similarities in intensity levels with empty compartments, and struggle with high-speed production environments where noise degrades inspection processes.
Innovation Solution
A stereo imaging system using linear cameras for high-speed image capture and real-time 3D reconstruction, processing noise measurements to determine the presence of transparent or specular objects by mapping 3D images onto height maps, enabling effective discrimination between empty and occupied compartments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional 2D image inspection systems are used, then the system is simple to operate, but it cannot effectively discriminate between empty compartments and compartments with transparent pills because intensities with and without transparent pills are similar
Solution Approach 1:
The patent transitions from 2D intensity-based inspection to 3D depth-based inspection by capturing stereo images and reconstructing depth maps. This dimensional change allows the system to detect transparent pills through their physical presence in 3D space rather than relying on intensity differences that are imperceptible in 2D images.
Solution Approach 2:
The patent introduces depth information as an intermediary parameter between the transparent pill and the detection system. By mapping 3D reconstructed images onto depth maps, the system creates an intermediate representation that highlights the presence of transparent objects through depth variations, enabling discrimination that is impossible with direct 2D intensity analysis.
2Productivity
If conventional camera equipment is used for 3D reconstruction, then the system is easier to manufacture, but it is difficult to achieve high resolution reconstructions in sufficient time to operate in high production rate environments
Solution Approach 1:
The patent employs high-speed linear cameras that capture images at periodic intervals as the blister pack moves along the conveyor. This periodic capture at high frame rates enables the system to build 3D reconstructions rapidly, matching the high production speed while maintaining resolution through the concentrated sampling of the moving object.
Solution Approach 2:
The patent replaces conventional frame-based camera systems with linear cameras that scan continuously. This substitution enables higher effective frame rates and faster 3D reconstruction by capturing image data line-by-line as the object moves, rather than requiring complete frames at each capture moment, thus achieving both high speed and high resolution.
3Measurement precision
If noise reduction techniques are applied to improve image quality, then measurement precision improves, but the inspection process becomes more complex and time-consuming
Solution Approach 1:
The patent converts the noise generated by transparent pills in 3D reconstructed images into a useful detection signal. Instead of treating the noise as interference to be eliminated, the system uses the presence and characteristics of this noise as the primary indicator for detecting transparent pills, thereby transforming a harmful artifact into a beneficial detection mechanism.
Solution Approach 2:
The patent changes the detection parameter from intensity (in 2D images) to depth-related noise characteristics (in 3D reconstructions). By analyzing noise in the depth map rather than attempting to reduce all noise, the system efficiently identifies transparent pills without requiring complex noise reduction processing, thus maintaining fast processing speeds.
Data Source
AI summary
A system and method of inspection may include capturing image data by a stereo imaging device. A determination as to whether noise indicative of a transparent or specular object exists in the image data may be made. A report that a transparent or specular object was captured in the image data may be made.