Light Field Camera Optical Inspection for Cigarette Pack Defects
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Solution Overview
Problem
High-speed production systems in the cigarette industry make optical inspection of cigarettes and packs challenging due to limitations in sensors and cameras, leading to inaccurate results when end faces are at different depth levels.
Innovation Solution
A method using a light field camera to record 3D images, generating raw image data that includes depth information for reliable optical inspection, allowing for the detection of defects and accurate evaluation of objects at varying depth levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensors and cameras are used for optical inspection, then the inspection speed can keep up with high production speeds, but the measurement precision and reliability deteriorate when objects are at different depth levels
Solution Approach 1:
The patent transitions from conventional 2D imaging to 3D light field imaging, adding a depth dimension to the inspection system. This allows simultaneous capture of objects at different depth levels with equal sharpness, resolving the contradiction between measurement precision and device complexity by fundamentally changing the imaging dimension rather than adding complex mechanical adjustment mechanisms
Solution Approach 2:
The patent changes the imaging parameter from standard focal plane capture to light field capture, which records not only intensity but also directional information of light rays. This parameter change enables post-processing refocusing at any depth level while maintaining sharpness, solving the precision issue without requiring complex real-time mechanical adjustments
2Adaptability or versatility
If multiple separate images with different focus planes are recorded, then objects at different depths can be captured, but the device complexity and processing requirements increase
Solution Approach 1:
The patent merges multiple focus plane information into a single light field image capture. Instead of requiring multiple separate imaging systems or sequential focusing operations, the light field camera integrates all depth information in one shot, reducing device complexity while maintaining adaptability to capture objects at varying depths
Solution Approach 2:
The light field camera provides multi-functionality by enabling refocusing at any depth level from a single captured image. This universal capability replaces the need for multiple specialized imaging systems, achieving depth adaptability without proportionally increasing device complexity
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
Enables fully automatic, reliable optical inspection of cigarettes and packs by generating test images with a large depth of field, ensuring all end faces are captured with high sharpness regardless of depth, and detecting defects such as protruding cigarettes or incorrect label positions.
Implementation Method 1
a light field camera (10) is used, which records a (light field) image in or with three spatial dimensions (3D image) of the at least one test object (12)
Data Source
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AI summary
The invention relates to a method for inspecting objects to be tested during the manufacture or packaging of cigarettes (11) or other smokable products – test objects – during the production process, in which at least one test object is subjected to an optical inspection. The invention is characterized in that a (light field) image of the at least one test object is recorded using a light field camera (10), that raw image data representing the image are generated, and that depth information is obtained from the raw image data, which is used to check whether the at least one test object is defective.